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Sample records for brain aquaporin aqp4

  1. Immunohistochemical localization of aquaporin 4 (AQP4 in the porcine gastrointestinal tract

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    Marcin Bartłomiej Arciszewski

    2015-01-01

    Full Text Available The water channel aquaporin-4 (AQP4 is a protein widely expressed on plasma membrane of a variety of epithelial cells. In this study we investigated the expression of AQP4 in the gastrointestinal tract of the pig using immunohistochemical staining. We found no presence of AQP4 in the different regions of the pig stomach. In the porcine small intestine moderate immunoreactivity to AQP4 was detected in enterocytes (along the villi and in the bottom of the crypts, duodenal Brunner’s glands and in enteric ganglia in cells lying in close vicinity to myenteric as well as submucous neurons. In superficial epithelial cells of the colonic mucosa as well as of caecal and colonic glands a very strong immunoreactivity to AQP4 was found. Both in the myenteric and submucous ganglia of the large intestine AQP4-positive cells surrounding enteric neurons were observed. We concluded that AQP4 expression in the porcine gastrointestinal tract showed some species-dependent differences in relation to other species. Based on the presented distribution pattern of AQP4, it is likely that the aquaporin plays a role in mucous (but not acid secretion and intestinal absorptive processes in the pig.

  2. Aquaporin-4 autoantibodies in Neuromyelitis Optica: AQP4 isoform-dependent sensitivity and specificity.

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    Francesco Pisani

    Full Text Available Neuromyelitis Optica (NMO is an autoimmune demyelinating disease, characterized by the presence of autoantibody (NMO-IgG to Aquaporin-4 (AQP4. NMO-IgG identification supports NMO diagnosis and several diagnostic tests have been developed, but their sensitivity is too variable, and some assay show low sensitivity. This impairs correct diagnosis of NMO. By cell based assay (CBA we here evaluate the efficacy of different strategies to express AQP4 in mammalian cells in terms of: a AQP4 translation initiation signals; b AQP4 isoforms (M1 and M23 and fluorescent tag position; c NMO serum concentration and AQP4 degradation. Our results demonstrate that when using AQP4-M1, the nucleotide in position -3 of the AUG greatly affects the AQP4-M1/M23 protein ratio, NMO-IgG binding, and consequently test sensitivity. Test sensitivity was highest with M23 expressing cells (97.5% and only 27.5% with AQP4-M1. The fluorescent tag added to the N-terminus of AQP4-M23 considerably affected the NMO-IgG binding, and test sensitivity, due to disruption of AQP4 suprastructures. Furthermore, sera used at high concentration resulted in AQP4 degradation which affected test sensitivity. To further evaluate the reliability of the M23 based CBA test, samples of one NMO patient collected during about 2 years clinical follow-up were tested. The results of serum titer correlated with disease activity and treatment response. In conclusion, we provide a molecular explanation for the contrasting CBA test data reported and suggest the use of M23 with a C-terminus fluorescent tag as the proper test for NMO diagnosis.

  3. New isoforms of rat Aquaporin-4

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    Moe, Svein Erik; Sorbo, Jan Gunnar; Søgaard, Rikke

    2008-01-01

    Aquaporin-4 (AQP4) is a brain aquaporin implicated in the pathophysiology of numerous clinical conditions including brain edema. Here we show that rat AQP4 has six cDNA isoforms, formed by alternative splicing. These are named AQP4a-f, where AQP4a and AQP4c correspond to the two classical M1 and M...

  4. ME-16IS AQUAPORIN4 (AQP4) INVOLVED IN ADULT HUMAN MEDULLOBLASTOMA DISSEMINATION OR IN A BENEFICIAL BARRIER FORMATION?

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    Pollo, Bianca; Mazzetti, Samanta; Patanè, Monica; Calatozzolo, Chiara; Di Meco, Francesco; Silvani, Antonio

    2014-01-01

    Medulloblastoma (MDB) is a highly malignant embryonal brain tumor located in the cerebellum with tendency to leptomeningeal dissemination, common in children, rare in adults. Recent genetic analysis suggested classification into four subgroups according to gene expression profiles, including the Wingless signaling pathway-activated group (WNT group), the Sonic Hedgehog signaling pathway-activated group (SHH group), group 3and 4, with distinct molecular, clinicopathological, and prognostic characteristics. AQP4 is the main water channel in the normal central nervous system (CNS) responsible for salt and water balance maintaining. When the blood-brain barrier become disrupted, as in gliomas, water moves from the vasculature into the extracellular space in an AQP4-independent manner, down a hydrostatic gradient to form a vasogenic edema. Moreover, AQPs have a role promoting tumor progression, cell migration and metastasis. Aim of our study was to evaluate for the first time AQP4 expression in adult MDB to focus its role in edema, tumor invasion and dissemination. We analyzed by immunohistochemistry AQP4 expression in 40 adult MDBs, also investigated for GAB1, ß-catenin, filamin-A, NPR3, according to molecular subgroups. Desmoplastic histology and Sonic hedgehog (SHH) pathway activation were more common feature, with GAB-1 and filamin-A expression. Only one case showed nuclear staining for ß-catenin. None expressed NPR3. In classical MDB, AQP4 staining was localized in glial endfoot surrounding tumor vessels. This AQP4 distribution was lost in the desmoplastic type, where the nodular areas were negatives, surrounded by glial elements AQP4 intensely stained. In the molecular layer of the cerebellar cortex in the tumor proximity in classic type MDB it has been observed migrating tumor cells along glial processes AQP4 stained. This finding was mainly observed in patients with early dissemination. These observations could suggest a role for AQP4 in adult MDB, not only in

  5. Regulation and Function of AQP4 in the Central Nervous System

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    Assentoft, Mette; Larsen, Brian Roland; MacAulay, Nanna

    2015-01-01

    Aquaporin 4 (AQP4) is the predominant water channel in the mammalian brain and is mainly expressed in the perivascular glial endfeet at the brain-blood interface. Based on studies on AQP4(-/-) mice, AQP4 has been assigned physiological roles in stimulus-induced K(+) clearance, paravascular fluid ...

  6. Neuroimmunological Implications of AQP4 in Astrocytes

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    Hiroko Ikeshima-Kataoka

    2016-08-01

    Full Text Available The brain has high-order functions and is composed of several kinds of cells, such as neurons and glial cells. It is becoming clear that many kinds of neurodegenerative diseases are more-or-less influenced by astrocytes, which are a type of glial cell. Aquaporin-4 (AQP4, a membrane-bound protein that regulates water permeability is a member of the aquaporin family of water channel proteins that is expressed in the endfeet of astrocytes in the central nervous system (CNS. Recently, AQP4 has been shown to function, not only as a water channel protein, but also as an adhesion molecule that is involved in cell migration and neuroexcitation, synaptic plasticity, and learning/memory through mechanisms involved in long-term potentiation or long-term depression. The most extensively examined role of AQP4 is its ability to act as a neuroimmunological inducer. Previously, we showed that AQP4 plays an important role in neuroimmunological functions in injured mouse brain in concert with the proinflammatory inducer osteopontin (OPN. The aim of this review is to summarize the functional implication of AQP4, focusing especially on its neuroimmunological roles. This review is a good opportunity to compile recent knowledge and could contribute to the therapeutic treatment of autoimmune diseases through strategies targeting AQP4. Finally, the author would like to hypothesize on AQP4’s role in interaction between reactive astrocytes and reactive microglial cells, which might occur in neurodegenerative diseases. Furthermore, a therapeutic strategy for AQP4-related neurodegenerative diseases is proposed.

  7. Aquaporin-4 in brain and spinal cord oedema.

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    Saadoun, S; Papadopoulos, M C

    2010-07-28

    Brain oedema is a major clinical problem produced by CNS diseases (e.g. stroke, brain tumour, brain abscess) and systemic diseases that secondarily affect the CNS (e.g. hyponatraemia, liver failure). The swollen brain is compressed against the surrounding dura and skull, which causes the intracranial pressure to rise, leading to brain ischaemia, herniation, and ultimately death. A water channel protein, aquaporin-4 (AQP4), is found in astrocyte foot processes (blood-brain border), the glia limitans (subarachnoid cerebrospinal fluid-brain border) and ependyma (ventricular cerebrospinal fluid-brain border). Experiments using mice lacking AQP4 or alpha syntrophin (which secondarily downregulate AQP4) showed that AQP4 facilitates oedema formation in diseases causing cytotoxic (cell swelling) oedema such as cerebral ischaemia, hyponatraemia and meningitis. In contrast, AQP4 facilitates oedema elimination in diseases causing vasogenic (vessel leak) oedema and therefore AQP4 deletion aggravates brain oedema produced by brain tumour and brain abscess. AQP4 is also important in spinal cord oedema. AQP4 deletion was associated with less cord oedema and improved outcome after compression spinal cord injury in mice. Here we consider the possible routes of oedema formation and elimination in the injured cord and speculate about the role of AQP4. Finally we discuss the role of AQP4 in neuromyelitis optica (NMO), an inflammatory demyelinating disease that produces oedema in the spinal cord and optic nerves. NMO patients have circulating AQP4 IgG autoantibody, which is now used for diagnosing NMO. We speculate how NMO-IgG might produce CNS inflammation, demyelination and oedema. Since AQP4 plays a key role in the pathogenesis of CNS oedema, we conclude that AQP4 inhibitors and activators may reduce CNS oedema in many diseases. Copyright (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Aquaporins in Brain Edema and Neuropathological Conditions

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    Aristotelis S. Filippidis

    2016-12-01

    Full Text Available The aquaporin (AQP family of water channels are a group of small, membrane-spanning proteins that are vital for the rapid transport of water across the plasma membrane. These proteins are widely expressed, from tissues such as the renal epithelium and erythrocytes to the various cells of the central nervous system. This review will elucidate the basic structure and distribution of aquaporins and discuss the role of aquaporins in various neuropathologies. AQP1 and AQP4, the two primary aquaporin molecules of the central nervous system, regulate brain water and CSF movement and contribute to cytotoxic and vasogenic edema, where they control the size of the intracellular and extracellular fluid volumes, respectively. AQP4 expression is vital to the cellular migration and angiogenesis at the heart of tumor growth; AQP4 is central to dysfunctions in glutamate metabolism, synaptogenesis, and memory consolidation; and AQP1 and AQP4 adaptations have been seen in obstructive and non-obstructive hydrocephalus and may be therapeutic targets.

  9. Superresolution Imaging of Aquaporin-4 Cluster Size in Antibody-Stained Paraffin Brain Sections

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    Smith, Alex J.; Verkman, Alan S.

    2015-01-01

    The water channel aquaporin-4 (AQP4) forms supramolecular clusters whose size is determined by the ratio of M1- and M23-AQP4 isoforms. In cultured astrocytes, differences in the subcellular localization and macromolecular interactions of small and large AQP4 clusters results in distinct physiological roles for M1- and M23-AQP4. Here, we developed quantitative superresolution optical imaging methodology to measure AQP4 cluster size in antibody-stained paraffin sections of mouse cerebral cortex and spinal cord, human postmortem brain, and glioma biopsy specimens. This methodology was used to demonstrate that large AQP4 clusters are formed in AQP4−/− astrocytes transfected with only M23-AQP4, but not in those expressing only M1-AQP4, both in vitro and in vivo. Native AQP4 in mouse cortex, where both isoforms are expressed, was enriched in astrocyte foot-processes adjacent to microcapillaries; clusters in perivascular regions of the cortex were larger than in parenchymal regions, demonstrating size-dependent subcellular segregation of AQP4 clusters. Two-color superresolution imaging demonstrated colocalization of Kir4.1 with AQP4 clusters in perivascular areas but not in parenchyma. Surprisingly, the subcellular distribution of AQP4 clusters was different between gray and white matter astrocytes in spinal cord, demonstrating regional specificity in cluster polarization. Changes in AQP4 subcellular distribution are associated with several neurological diseases and we demonstrate that AQP4 clustering was preserved in a postmortem human cortical brain tissue specimen, but that AQP4 was not substantially clustered in a human glioblastoma specimen despite high-level expression. Our results demonstrate the utility of superresolution optical imaging for measuring the size of AQP4 supramolecular clusters in paraffin sections of brain tissue and support AQP4 cluster size as a primary determinant of its subcellular distribution. PMID:26682810

  10. AQP4e-Based Orthogonal Arrays Regulate Rapid Cell Volume Changes in Astrocytes.

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    Lisjak, Marjeta; Potokar, Maja; Rituper, Boštjan; Jorgačevski, Jernej; Zorec, Robert

    2017-11-01

    Water channel aquaporin 4 (AQP4) plays a key role in the regulation of water homeostasis in the brain. It is predominantly expressed in astrocytes at the blood-brain and blood-liquor interfaces. Although several AQP4 isoforms have been identified in the mammalian brain, two, AQP4a (M1) and AQP4c (M23), have been confirmed to cluster into plasma membrane supramolecular structures, termed orthogonal arrays of particles (OAPs) and to enhance water transport through the plasma membrane. However, the role of the newly described water-conductive mammalian isoform AQP4e is unknown. Here, the dynamics of AQP4e aggregation into OAPs and its role in the regulation of astrocyte water homeostasis have been studied. Using super-resolution structured illumination, atomic force, and confocal microscopies, the results revealed that, in female rat astrocytes, AQP4e isoform colocalizes with OAPs, affecting its structural dynamics. In hypoosmotic conditions, which elicit cell edema, OAP formation was considerably enhanced by overexpressed AQP4e. Moreover, the kinetics of the cell swelling and of the regulatory volume decrease was faster in astrocytes overexpressing AQP4e compared with untransfected controls. Furthermore, the increase in maximal cell volume elicited by hypoosmotic stimulation was significantly smaller in AQP4e-overexpressing astrocytes. For the first time, this study demonstrates an active role of AQP4e in the regulation of OAP structural dynamics and in water homeostasis.SIGNIFICANCE STATEMENT Water channel aquaporin 4 (AQP4) plays a key role in the regulation of water homeostasis in the brain. To date, only AQP4a and AQP4c isoforms have been confirmed to enhance water transport through plasmalemma and to cluster into orthogonal arrays of particles (OAPs). We here studied the dynamics, aggregation, and role in the regulation of astrocyte water homeostasis of the newly described water-conductive mammalian isoform AQP4e. Our main findings are as follows: brain edema

  11. Mildly Reduced Brain Swelling and Improved Neurological Outcome in Aquaporin-4 Knockout Mice following Controlled Cortical Impact Brain Injury.

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    Yao, Xiaoming; Uchida, Kazuyoshi; Papadopoulos, Marios C; Zador, Zsolt; Manley, Geoffrey T; Verkman, Alan S

    2015-10-01

    Brain edema following traumatic brain injury (TBI) is associated with considerable morbidity and mortality. Prior indirect evidence has suggested the involvement of astrocyte water channel aquaporin-4 (AQP4) in the pathogenesis of TBI. Here, focal TBI was produced in wild type (AQP4(+/+)) and knockout (AQP4(-/-)) mice by controlled cortical impact injury (CCI) following craniotomy with dura intact (parameters: velocity 4.5 m/sec, depth 1.7 mm, dwell time 150 msec). AQP4-deficient mice showed a small but significant reduction in injury volume in the first week after CCI, with a small improvement in neurological outcome. Mechanistic studies showed reduced intracranial pressure at 6 h after CCI in AQP4(-/-) mice, compared with AQP4(+/+) control mice (11 vs. 19 mm Hg), with reduced local brain water accumulation as assessed gravimetrically. Transmission electron microscopy showed reduced astrocyte foot-process area in AQP4(-/-) mice at 24 h after CCI, with greater capillary lumen area. Blood-brain barrier disruption assessed by Evans blue dye extravasation was similar in AQP4(+/+) and AQP4(-/-) mice. We conclude that the mildly improved outcome in AQP4(-/-) mice following CCI results from reduced cytotoxic brain water accumulation, though concurrent cytotoxic and vasogenic mechanisms in TBI make the differences small compared to those seen in disorders where cytotoxic edema predominates.

  12. [Aquaporin water channels in the brain and molecular mechanisms of brain edema].

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    Sobue, Kazuya; Asai, Kiyofumi; Katsuya, Hirotada

    2006-06-01

    Aquaporins(AQPs) are a family of water selective channel. Transcripts of AQP1, AQP3, AQP4, AQP5, AQP8, and AQP9 are detected in the brain. Especially in astrocytes, AQP4 is abundantly expressed in end feet at the blood-brain barrier. Brain AQPs play important roles in the regulation of water homeostasis and the cerebro spinal fluid formation. Recently, AQP4 and AQP9 have been reported to involve in the brain water accumulation in the brain edema. Studies of transgenic mouse and brain injury models reveal that AQP4 may play a role not in the edema formation, but in the fluid elimination. Further study of AQPs functions in the brain may provide new insights into the brain edema and allow the design of novel anti edema medications.

  13. Targeted deletion of Aqp4 promotes the formation of astrocytic gap junctions.

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    Katoozi, Shirin; Skauli, Nadia; Rahmani, Soulmaz; Camassa, Laura M A; Boldt, Henning B; Ottersen, Ole P; Amiry-Moghaddam, Mahmood

    2017-12-01

    Aquaporin-4 (AQP4) is the predominant water channel in the brain and is expressed in high density in astrocytes. By fluxing water along osmotic gradients, AQP4 contributes to brain volume and ion homeostasis. Here we ask whether deletion of Aqp4 leads to upregulation of the gap junctional proteins connexin-43 (Cx43) and connexin-30 (Cx30). These molecules couple adjacent astrocytes to each other and allow water and ions to redistribute within the astrocyte syncytium. Immunogold analysis of parietal cortex and hippocampus showed that the number of gap junctions per capillary profile is increased in AQP4 knockout (AQP4 KO) mice. The most pronounced changes were observed for Cx43 in hippocampus where the number of connexin labeled gap junctions increased by 100% following AQP4 KO. Western blot analysis of whole tissue homogenates showed no change in the amount of Cx43 or Cx30 protein after AQP4 KO. However, AQP4 KO led to a significant increase in the amount of Cx43 in a Triton X-100 insoluble fraction. This fraction is associated with connexin assembly into gap junctional plaques in the plasma membrane. In line with our immunoblot data, RT-qPCR showed no significant increase in Cx43 and Cx30 mRNA levels after AQP4 KO. Our findings suggest that AQP4 KO leads to increased aggregation of Cx43 into gap junctions and provide a putative mechanistic basis for the enhanced tracer coupling in hippocampi of AQP4 KO mice. The increased number of gap junctions in AQP4 deficient mice may explain why Aqp4 deletion has rather modest effects on brain volume and K+ homeostasis.

  14. Differences in distribution and regulation of astrocytic aquaporin-4 in human and rat hydrocephalic brain

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    Skjolding, Anders Daehli; Holst, Anders Vedel; Broholm, Helle

    2013-01-01

    in human hydrocephalic cortex relative to controls was quantified by western blotting (n=28). A second biopsy (n=13) was processed for immunohistochemistry (GFAP, CD68, CD34 and aquaporin-4) and double immunofluorescence (aquaporin-4+GFAP and aquaporin-4+CD34). Brain tissue from human controls and kaolin......-induced hydrocephalic rats was processed in parallel. Immunohistochemistry and immunofluorescence were assessed qualitatively. Results:  Western blotting showed that AQP4 abundance was significantly increased (p...

  15. Aquaporin-4 independent Kir4.1 K+ channel function in brain glial cells.

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    Zhang, Hua; Verkman, A S

    2008-01-01

    Functional interaction of glial water channel aquaporin-4 (AQP4) and inwardly rectifying K+ channel Kir4.1 has been suggested from their apparent colocalization and biochemical interaction, and from the slowed glial cell K+ uptake in AQP4-deficient brain. Here, we report multiple lines of evidence against functionally significant AQP4-Kir4.1 interactions. Whole-cell patch-clamp of freshly isolated glial cells from brains of wild-type and AQP4 null mice showed no significant differences in membrane potential, barium-sensitive Kir4.1 K+ current or current-voltage curves. Single-channel patch-clamp showed no differences in Kir4.1 unitary conductance, voltage-dependent open probability or current-voltage relationship. Also, Kir4.1 protein expression and distribution were similar in wild-type and AQP4 null mouse brain and in the freshly isolated glial cells. Functional inhibition of Kir4.1 by barium or RNAi knock-down in primary glial cell cultures from mouse brain did not significantly alter AQP4 water permeability, as assayed by calcein fluorescence quenching following osmotic challenge. These studies provide direct evidence against functionally significant AQP4-Kir4.1 interactions in mouse glial cells, indicating the need to identify new mechanism(s) to account for altered seizure dynamics and extracellular space K+ buffering in AQP4 deficiency.

  16. Phosphorylation of rat aquaporin-4 at Ser(111) is not required for channel gating

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    Assentoft, Mette; Kaptan, Shreyas; Fenton, Robert A

    2013-01-01

    Aquaporin 4 (AQP4) is the predominant water channel in the mammalian brain and is mainly expressed in the perivascular glial endfeet at the brain-blood interface. AQP4 has been described as an important entry and exit site for water during formation of brain edema and regulation of AQP4 is theref...

  17. Comparison of spontaneous brain activity revealed by regional homogeneity in AQP4-IgG neuromyelitis optica-optic neuritis versus MOG-IgG optic neuritis patients: a resting-state functional MRI study

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    Wang J

    2017-10-01

    Full Text Available Junqing Wang,1,* Yuan Tian,2,* Yi Shao,3,* Hui Feng,1 Limin Qin,1 Weiwei Xu,1 Hongjuan Liu,1 Quangang Xu,1 Shihui Wei,1 Lin Ma2 1Department of Ophthalmology, 2Department of Radiology, Chinese PLA General Hospital, Beijing, 3Department of Ophthalmology, the First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People’s Republic of China *These authors contributed equally to this work Objective: Many previous studies have demonstrated that neuromyelitis optica (NMO patients have abnormalities of brain anatomy and function. However, differences in spontaneous brain activity between myelin oligodendrocyte glycoprotein (MOG-IgG ON and aquaporin 4(AQP4-neuromyelitis optica-optic neuritis (ON remain unknown. In the current study, we investigated the brain neural homogeneity in MOG-IgG ON versus AQP4-IgG NMO-ON subjects by regional homogeneity (ReHo method using magnetic resonance imaging (MRI. Patients and methods: A total of 32 NMO-ON and ON subjects (21 with AQP4-IgG+NMO-ON and 11 with MOG-IgG+ON and 34 healthy controls (HCs closely matched for age were recruited, and scans were performed for all subjects. A one-way analysis of variance (ANOVA was performed to determine the regions in which the ReHo was different across the three groups. NMO-ON and ON subjects were distinguished from HCs by a receiver operating characteristic (ROC curve. The relationship between the mean ReHo in many brain regions and clinical features in NMO subjects was calculated by Pearson correlation analysis. Results: Compared with HCs, MOG-IgG+ON subjects had significantly decreased ReHo values in the posterior lobe of the left cerebellum and increased ReHo values in the left inferior frontal gyrus, right prefrontal gyrus, and left precentral/postcentral gyrus. AQP4-IgG+NMO-ON subjects showed higher ReHo values in the left inferior frontal gyrus and right middle temporal/occipital gyrus. Compared with MOG-IgG+ON subjects, AQP4-IgG+NMO-ON subjects had lower Re

  18. Comparison of brain and spinal cord magnetic resonance imaging features in neuromyelitis optica spectrum disorders patients with or without aquaporin-4 antibody.

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    Fan, Moli; Fu, Ying; Su, Lei; Shen, Yi; Wood, Kristofer; Yang, Li; Liu, Yaou; Shi, Fu-Dong

    2017-04-01

    The spinal cord and brain measurements are rarely investigated in neuromyelitis optica (NMO) patients with and without antibodies to aquaporin-4 (AQP4), directly compared to multiple sclerosis (MS) patients. To investigate magnetic resonance imaging (MRI) features of both brain and spinal cord in NMO patients with and without antibodies to AQP4, compared with MS patients and healthy controls (HC). We recruited 55 NMO including 30 AQP4 (+) and 25 AQP4 (-), 25 MS and 25 HC. Brain and spinal cord MRIs were obtained for each participant. Brain lesions (BL), whole brain and deep grey matter volumes (DGMV), white matter diffusion metrics and spinal cord lesions were measured and compared among groups. The incidence of BL was lower in the AQP4 (+) group than in the AQP4 (-) and MS groups (p<0.05). In the AQP4 (+) group, there was a lower incidence of infratentorial lesions (ITL) and higher spinal cord lesions length than in the MS group (p<0.05). The thalamic and hippocampal volumes were smaller in the AQP4 (-) group and MS group than in the HC group (p<0.05). The NMO patients with AQP4 (-) showed higher prevalence of BL, ITL, and similar spinal cord lesion length, compared to AQP4 (+), and demonstrated deep grey matter atrophy, suggesting an intermediate phenotype between that of typical MS and NMO. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Protection of Vascular Endothelial Growth Factor to Brain Edema Following Intracerebral Hemorrhage and Its Involved Mechanisms: Effect of Aquaporin-4.

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    Heling Chu

    Full Text Available Vascular endothelial growth factor (VEGF has protective effects on many neurological diseases. However, whether VEGF acts on brain edema following intracerebral hemorrhage (ICH is largely unknown. Our previous study has shown aquaporin-4 (AQP4 plays an important role in brain edema elimination following ICH. Meanwhile, there is close relationship between VEGF and AQP4. In this study, we aimed to test effects of VEGF on brain edema following ICH and examine whether they were AQP4 dependent. Recombinant human VEGF165 (rhVEGF165 was injected intracerebroventricularly 1 d after ICH induced by microinjecting autologous whole blood into striatum. We detected perihemotomal AQP4 protein expression, then examined the effects of rhVEGF165 on perihemotomal brain edema at 1 d, 3 d, and 7 d after injection in wild type (AQP4(+/+ and AQP4 knock-out (AQP4(-/- mice. Furthermore, we assessed the possible signal transduction pathways activated by VEGF to regulate AQP4 expression via astrocyte cultures. We found perihemotomal AQP4 protein expression was highly increased by rhVEGF165. RhVEGF165 alleviated perihemotomal brain edema in AQP4(+/+ mice at each time point, but had no effect on AQP4(-/- mice. Perihemotomal EB extravasation was increased by rhVEGF165 in AQP4(-/- mice, but not AQP4(+/+ mice. RhVEGF165 reduced neurological deficits and increased Nissl's staining cells surrounding hemotoma in both types of mice and these effects were related to AQP4. RhVEGF165 up-regulated phospharylation of C-Jun amino-terminal kinase (p-JNK and extracellular signal-regulated kinase (p-ERK and AQP4 protein in cultured astrocytes. The latter was inhibited by JNK and ERK inhibitors. In conclusion, VEGF reduces neurological deficits, brain edema, and neuronal death surrounding hemotoma but has no influence on BBB permeability. These effects are closely related to AQP4 up-regulation, possibly through activating JNK and ERK pathways. The current study may present new insights to

  20. Association of Perivascular Localization of Aquaporin-4 With Cognition and Alzheimer Disease in Aging Brains.

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    Zeppenfeld, Douglas M; Simon, Matthew; Haswell, J Douglas; D'Abreo, Daryl; Murchison, Charles; Quinn, Joseph F; Grafe, Marjorie R; Woltjer, Randall L; Kaye, Jeffrey; Iliff, Jeffrey J

    2017-01-01

    Cognitive impairment and dementia, including Alzheimer disease (AD), are common within the aging population, yet the factors that render the aging brain vulnerable to these processes are unknown. Perivascular localization of aquaporin-4 (AQP4) facilitates the clearance of interstitial solutes, including amyloid-β, through the brainwide network of perivascular pathways termed the glymphatic system, which may be compromised in the aging brain. To determine whether alterations in AQP4 expression or loss of perivascular AQP4 localization are features of the aging human brain and to define their association with AD pathology. Expression of AQP4 was analyzed in postmortem frontal cortex of cognitively healthy and histopathologically confirmed individuals with AD by Western blot or immunofluorescence for AQP4, amyloid-β 1-42, and glial fibrillary acidic protein. Postmortem tissue and clinical data were provided by the Oregon Health and Science University Layton Aging and Alzheimer Disease Center and Oregon Brain Bank. Postmortem tissue from 79 individuals was evaluated, including cognitively intact "young" individuals aged younger than 60 years (range, 33-57 years), cognitively intact "aged" individuals aged older than 60 years (range, 61-96 years) with no known neurological disease, and individuals older than 60 years (range, 61-105 years) of age with a clinical history of AD confirmed by histopathological evaluation. Forty-eight patient samples (10 young, 20 aged, and 18 with AD) underwent histological analysis. Sixty patient samples underwent Western blot analysis (15 young, 24 aged, and 21 with AD). Expression of AQP4 protein, AQP4 immunoreactivity, and perivascular AQP4 localization in the frontal cortex were evaluated. Expression of AQP4 was associated with advancing age among all individuals (R2 = 0.17; P = .003). Perivascular AQP4 localization was significantly associated with AD status independent of age (OR, 11.7 per 10% increase in localization; z

  1. Brain expression of the water channels Aquaporin-1 and -4 in mice with acute liver injury, hyperammonemia and brain edema

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    Eefsen, Martin; Jelnes, Peter; Schmidt, Lars E

    2010-01-01

    Cerebral edema is a feared complication to acute liver failure (ALF), but the pathogenesis is still poorly understood. The water channels Aquaporin-1 (Aqp1) and -4 (Aqp4) has been associated with brain edema formation in several neuropathological conditions, indicating a possible role of Aqp1 and...

  2. Simvastatin pretreatment protects cerebrum from neuronal injury by decreasing the expressions of phosphor-CaMK II and AQP4 in ischemic stroke rats.

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    Zhu, Min-xia; Lu, Chao; Xia, Chun-mei; Qiao, Zhong-wei; Zhu, Da-nian

    2014-12-01

    Excitotoxicity and cytotoxic edema are the two major factors resulting in neuronal injury during brain ischemia and reperfusion. Ca2+/calmodulin-dependent protein kinase II (CaMK II), the downstream signal molecular of N-methyl-D-aspartate receptors (NMDARs), is a mediator in the excitotoxicity. Aquaporin 4 (AQP4), expressed mainly in the brain, is an important aquaporin to control the flux of water. In a previous study, we had reported that pretreatment of simvastatin protected the cerebrum from ischemia and reperfusion injury by decreasing neurological deficit score and infarct area (Zhu et al. PLoS One 7:e51552, 2012). The present study used a middle cerebral artery occlusion (MCAO) model to further explore the pleiotropic effect of simvastatin via CaMK II and AQP4. The results showed that simvastatin reduced degenerated cells and brain edema while decreasing the protein expressions of phosphor-CaMK II and AQP4, and increasing the ratios of Bcl-2/Bax, which was independent of cholesterol-lowering effect. Immunocomplexes formed between the subunit of NMDARs-NR3A and AQP4 were detected for the first time. It was concluded that simvastatin could protect the cerebrum from neuronal excitotoxicity and cytotoxic edema by downregulating the expressions of phosphor-CaMK II and AQP4, and that the interaction between NR3A and AQP4 might provide the base for AQP4 involving in the signaling pathways mediated by NMDARs.

  3. Striatal adenosine signaling regulates EAAT2 and astrocytic AQP4 expression and alcohol drinking in mice.

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    Lee, Moonnoh R; Ruby, Christina L; Hinton, David J; Choi, Sun; Adams, Chelsea A; Young Kang, Na; Choi, Doo-Sup

    2013-02-01

    Adenosine signaling is implicated in several neuropsychiatric disorders, including alcoholism. Among its diverse functions in the brain, adenosine regulates glutamate release and has an essential role in ethanol sensitivity and preference. However, the molecular mechanisms underlying adenosine-mediated glutamate signaling in neuroglial interaction remain elusive. We have previously shown that mice lacking the ethanol-sensitive adenosine transporter, type 1 equilibrative nucleoside transporter (ENT1), drink more ethanol compared with wild-type mice and have elevated striatal glutamate levels. In addition, ENT1 inhibition or knockdown reduces glutamate transporter expression in cultured astrocytes. Here, we examined how adenosine signaling in astrocytes contributes to ethanol drinking. Inhibition or deletion of ENT1 reduced the expression of type 2 excitatory amino-acid transporter (EAAT2) and the astrocyte-specific water channel, aquaporin 4 (AQP4). EAAT2 and AQP4 colocalization was also reduced in the striatum of ENT1 null mice. Ceftriaxone, an antibiotic compound known to increase EAAT2 expression and function, elevated not only EAAT2 but also AQP4 expression in the striatum. Furthermore, ceftriaxone reduced ethanol drinking, suggesting that ENT1-mediated downregulation of EAAT2 and AQP4 expression contributes to excessive ethanol consumption in our mouse model. Overall, our findings indicate that adenosine signaling regulates EAAT2 and astrocytic AQP4 expressions, which control ethanol drinking in mice.

  4. Lost Polarization of Aquaporin4 and Dystroglycan in the Core Lesion after Traumatic Brain Injury Suggests Functional Divergence in Evolution

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    Hui Liu

    2015-01-01

    Full Text Available Objective. To understand how aquaporin4 (AQP4 and dystroglycan (DG polarized distribution change and their roles in brain edema formation after traumatic brain injury (TBI. Methods. Brain water content, Evans blue detection, real-time PCR, western blot, and immunofluorescence were used. Results. At an early stage of TBI, AQP4 and DG maintained vessel-like pattern in perivascular endfeet; M1, M23, and M1/M23 were increased in the core lesion. At a later stage of TBI, DG expression was lost in perivascular area, accompanied with similar but delayed change of AQP4 expression; expression of M1, M23, and DG and the ratio of M1/M2 were increased. Conclusion. At an early stage, AQP4 and DG maintained the polarized distribution. Upregulated M1 and M23 could retard the cytotoxic edema formation. At a later stage AQP4 and DG polarized expression were lost from perivascular endfeet and induced the worst cytotoxic brain edema. The alteration of DG expression could regulate that of AQP4 expression after TBI.

  5. Metal ion toxins and brain aquaporin-4 expression: an overview

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    Adriana eXimenes-Da-Silva

    2016-06-01

    Full Text Available Metal ions such as iron, zinc, and manganese are essential to metabolic functions, protein synthesis, neurotransmission, and antioxidant neuroprotective mechanisms. Conversely, non-essential metals such as mercury and lead are sources of human intoxication due to occupational activities or environmental contamination. Essential or non-essential metal accumulation in the central nervous system (CNS results in changes in blood-brain barrier (BBB permeability, as well as triggering microglia activation and astrocyte reactivity and changing water transport through the cells, which could result in brain swelling. Aquaporin-4 is the main water channel in the CNS, is expressed in astrocyte foot processes in brain capillaries and along the circumventricular epithelium in the ventricles, and has important physiological functions in maintaining brain osmotic homeostasis and supporting brain excitability through regulation of the extracellular space. Some evidence has pointed to a role of AQP4 during metal intoxication in the brain, where it may act in a dual form as a neuroprotector or a mediator of the development of oxidative stress in neurons and astrocytes, resulting in brain swelling and neuronal damage. This mini-review presents the way some metal ions affect changes in AQP4 expression in the CNS and discuss the ways in which water transport in brain cells can be involved in brain damage.

  6. TRPV4 and AQP4 Channels Synergistically Regulate Cell Volume and Calcium Homeostasis in Retinal Müller Glia.

    Science.gov (United States)

    Jo, Andrew O; Ryskamp, Daniel A; Phuong, Tam T T; Verkman, Alan S; Yarishkin, Oleg; MacAulay, Nanna; Križaj, David

    2015-09-30

    Brain edema formation occurs after dysfunctional control of extracellular volume partly through impaired astrocytic ion and water transport. Here, we show that such processes might involve synergistic cooperation between the glial water channel aquaporin 4 (AQP4) and the transient receptor potential isoform 4 (TRPV4), a polymodal swelling-sensitive cation channel. In mouse retinas, TRPV4 colocalized with AQP4 in the end feet and radial processes of Müller astroglia. Genetic ablation of TRPV4 did not affect the distribution of AQP4 and vice versa. However, retinas from Trpv4(-/-) and Aqp4(-/-) mice exhibited suppressed transcription of genes encoding Trpv4, Aqp4, and the Kir4.1 subunit of inwardly rectifying potassium channels. Swelling and [Ca(2+)]i elevations evoked in Müller cells by hypotonic stimulation were antagonized by the selective TRPV4 antagonist HC-067047 (2-methyl-1-[3-(4-morpholinyl)propyl]-5-phenyl-N-[3-(trifluoromethyl)phenyl]-1H-pyrrole-3-carboxamide) or Trpv4 ablation. Elimination of Aqp4 suppressed swelling-induced [Ca(2+)]i elevations but only modestly attenuated the amplitude of Ca(2+) signals evoked by the TRPV4 agonist GSK1016790A [(N-((1S)-1-{[4-((2S)-2-{[(2,4-dichlorophenyl)sulfonyl]amino}-3-hydroxypropanoyl)-1-piperazinyl]carbonyl}-3-methylbutyl)-1-benzothiophene-2-carboxamide]. Glial cells lacking TRPV4 but not AQP4 showed deficits in hypotonic swelling and regulatory volume decrease. Functional synergy between TRPV4 and AQP4 during cell swelling was confirmed in the heterologously expressing Xenopus oocyte model. Importantly, when the swelling rate was osmotically matched for AQP4-positive and AQP4-negative oocytes, TRPV4 activation became independent of AQP4. We conclude that AQP4-mediated water fluxes promote the activation of the swelling sensor, whereas Ca(2+) entry through TRPV4 channels reciprocally modulates volume regulation, swelling, and Aqp4 gene expression. Therefore, TRPV4-AQP4 interactions constitute a molecular system

  7. Differential aquaporin 4 expression during edema build-up and resolution phases of brain inflammation

    Science.gov (United States)

    2011-01-01

    Background Vasogenic edema dynamically accumulates in many brain disorders associated with brain inflammation, with the critical step of edema exacerbation feared in patient care. Water entrance through blood-brain barrier (BBB) opening is thought to have a role in edema formation. Nevertheless, the mechanisms of edema resolution remain poorly understood. Because the water channel aquaporin 4 (AQP4) provides an important route for vasogenic edema resolution, we studied the time course of AQP4 expression to better understand its potential effect in countering the exacerbation of vasogenic edema. Methods Focal inflammation was induced in the rat brain by a lysolecithin injection and was evaluated at 1, 3, 7, 14 and 20 days using a combination of in vivo MRI with apparent diffusion coefficient (ADC) measurements used as a marker of water content, and molecular and histological approaches for the quantification of AQP4 expression. Markers of active inflammation (macrophages, BBB permeability, and interleukin-1β) and markers of scarring (gliosis) were also quantified. Results This animal model of brain inflammation demonstrated two phases of edema development: an initial edema build-up phase during active inflammation that peaked after 3 days (ADC increase) was followed by an edema resolution phase that lasted from 7 to 20 days post injection (ADC decrease) and was accompanied by glial scar formation. A moderate upregulation in AQP4 was observed during the build-up phase, but a much stronger transcriptional and translational level of AQP4 expression was observed during the secondary edema resolution phase. Conclusions We conclude that a time lag in AQP4 expression occurs such that the more significant upregulation was achieved only after a delay period. This change in AQP4 expression appears to act as an important determinant in the exacerbation of edema, considering that AQP4 expression is insufficient to counter the water influx during the build-up phase, while the

  8. Characterization of the spectrum of Korean inflammatory demyelinating diseases according to the diagnostic criteria and AQP4-Ab status.

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    Kim, Sung-Min; Waters, Patrick; Woodhall, Mark; Yang, Ji Won; Yang, Hyeran; Kim, Jee-Eun; Sung, Jung-Joon; Park, Kyung Seok; Lee, Kwang-Woo

    2014-04-29

    The relative frequencies of demyelinating diseases among Korean patients with idiopathic inflammatory demyelinating disease of the central nervous system (IIDD) have not been sufficiently studied. We therefore describe a cohort of 203 patients with IIDD from three centers in Korea whose syndromes were identified precisely according to international clinical criteria and autoantibody to aquaporin 4 (AQP4-Ab) status. In total, 260 consecutive patients were screened and 203 were included from three hospitals in Korea. All were tested for AQP4-Ab by using a cell-based assay. Patients who met the criteria for definite neuromyelitis optica (NMO) or had a positive AQP4-Ab test result were defined as the NMO group. Among the others, patients were assessed if they had acute disseminated encephalomyelitis, multiple sclerosis (MS), acute transverse myelitis, optic neuritis, or other demyelinating disease as a clinically isolated syndrome of the brain. Eighteen percent of patients were classified as the NMO group, 2% as acute disseminated encephalomyelitis, 18% as MS, 41% as acute transverse myelitis, 11% as optic neuritis, and 8% as other clinically isolated syndrome of the brain. AQP4-Ab was positive in 18% of patients and the relative frequency of NMO to MS (NMO/MS ratio) was 1.06. The mean duration of follow up in our patients was 64 months. Among Korean patients with idiopathic inflammatory demyelinating diseases, the incidence of NMO may be similar to that of MS, and the overall positivity of AQP4-Ab could be lower than previously reported. In addition, acute transverse myelitis that is not associated with MS or NMO can be relatively common in these patients. Further population-based studies with AQP4-Ab are needed to determine the exact incidence of NMO and other idiopathic inflammatory demyelinating diseases in Korea.

  9. Aquaporin 4 as a NH3 Channel*

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    Assentoft, Mette; Kaptan, Shreyas; Schneider, Hans-Peter; Deitmer, Joachim W.; de Groot, Bert L.; MacAulay, Nanna

    2016-01-01

    Ammonia is a biologically potent molecule, and the regulation of ammonia levels in the mammalian body is, therefore, strictly controlled. The molecular paths of ammonia permeation across plasma membranes remain ill-defined, but the structural similarity of water and NH3 has pointed to the aquaporins as putative NH3-permeable pores. Accordingly, a range of aquaporins from mammals, plants, fungi, and protozoans demonstrates ammonia permeability. Aquaporin 4 (AQP4) is highly expressed at perivascular glia end-feet in the mammalian brain and may, with this prominent localization at the blood-brain-interface, participate in the exchange of ammonia, which is required to sustain the glutamate-glutamine cycle. Here we observe that AQP4-expressing Xenopus oocytes display a reflection coefficient NH3. Taken together with an NH4Cl-mediated intracellular alkalization (or lesser acidification) of AQP4-expressing oocytes, these data suggest that NH3 is able to permeate the pore of AQP4. Exposure to NH4Cl increased the membrane currents to a similar extent in uninjected oocytes and in oocytes expressing AQP4, indicating that the ionic NH4+ did not permeate AQP4. Molecular dynamics simulations revealed partial pore permeation events of NH3 but not of NH4+ and a reduced energy barrier for NH3 permeation through AQP4 compared with that of a cholesterol-containing lipid bilayer, suggesting AQP4 as a favored transmembrane route for NH3. Our data propose that AQP4 belongs to the growing list of NH3-permeable water channels. PMID:27435677

  10. Aquaporin 4 as a NH3 Channel.

    Science.gov (United States)

    Assentoft, Mette; Kaptan, Shreyas; Schneider, Hans-Peter; Deitmer, Joachim W; de Groot, Bert L; MacAulay, Nanna

    2016-09-02

    Ammonia is a biologically potent molecule, and the regulation of ammonia levels in the mammalian body is, therefore, strictly controlled. The molecular paths of ammonia permeation across plasma membranes remain ill-defined, but the structural similarity of water and NH3 has pointed to the aquaporins as putative NH3-permeable pores. Accordingly, a range of aquaporins from mammals, plants, fungi, and protozoans demonstrates ammonia permeability. Aquaporin 4 (AQP4) is highly expressed at perivascular glia end-feet in the mammalian brain and may, with this prominent localization at the blood-brain-interface, participate in the exchange of ammonia, which is required to sustain the glutamate-glutamine cycle. Here we observe that AQP4-expressing Xenopus oocytes display a reflection coefficient NH3 Taken together with an NH4Cl-mediated intracellular alkalization (or lesser acidification) of AQP4-expressing oocytes, these data suggest that NH3 is able to permeate the pore of AQP4. Exposure to NH4Cl increased the membrane currents to a similar extent in uninjected oocytes and in oocytes expressing AQP4, indicating that the ionic NH4 (+) did not permeate AQP4. Molecular dynamics simulations revealed partial pore permeation events of NH3 but not of NH4 (+) and a reduced energy barrier for NH3 permeation through AQP4 compared with that of a cholesterol-containing lipid bilayer, suggesting AQP4 as a favored transmembrane route for NH3 Our data propose that AQP4 belongs to the growing list of NH3-permeable water channels. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. AQP4-dependent water transport plays a functional role in exercise-induced skeletal muscle adaptations.

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    Davide Basco

    Full Text Available In this study we assess the functional role of Aquaporin-4 (AQP4 in the skeletal muscle by analyzing whether physical activity modulates AQP4 expression and whether the absence of AQP4 has an effect on osmotic behavior, muscle contractile properties, and physical activity. To this purpose, rats and mice were trained on the treadmill for 10 (D10 and 30 (D30 days and tested with exercise to exhaustion, and muscles were used for immunoblotting, RT-PCR, and fiber-type distribution analysis. Taking advantage of the AQP4 KO murine model, functional analysis of AQP4 was performed on dissected muscle fibers and sarcolemma vesicles. Moreover, WT and AQP4 KO mice were subjected to both voluntary and forced activity. Rat fast-twitch muscles showed a twofold increase in AQP4 protein in D10 and D30 rats compared to sedentary rats. Such increase positively correlated with the animal performance, since highest level of AQP4 protein was found in high runner rats. Interestingly, no shift in muscle fiber composition nor an increase in AQP4-positive fibers was found. Furthermore, no changes in AQP4 mRNA after exercise were detected, suggesting that post-translational events are likely to be responsible for AQP4 modulation. Experiments performed on AQP4 KO mice revealed a strong impairment in osmotic responses as well as in forced and voluntary activities compared to WT mice, even though force development amplitude and contractile properties were unvaried. Our findings definitively demonstrate the physiological role of AQP4 in supporting muscle contractile activity and metabolic changes that occur in fast-twitch skeletal muscle during prolonged exercise.

  12. Phosphorylation of rat aquaporin-4 at Ser(111) is not required for channel gating.

    Science.gov (United States)

    Assentoft, Mette; Kaptan, Shreyas; Fenton, Robert A; Hua, Susan Z; de Groot, Bert L; MacAulay, Nanna

    2013-07-01

    Aquaporin 4 (AQP4) is the predominant water channel in the mammalian brain and is mainly expressed in the perivascular glial endfeet at the brain-blood interface. AQP4 has been described as an important entry and exit site for water during formation of brain edema and regulation of AQP4 is therefore of therapeutic interest. Phosphorylation of some aquaporins has been proposed to regulate their water permeability via gating of the channel itself. Protein kinase (PK)-dependent phosphorylation of Ser(111) has been reported to increase the water permeability of AQP4 expressed in an astrocytic cell line. This possibility was, however, questioned based on the crystal structure of the human AQP4. Our study aimed to resolve if Ser(111) was indeed a site involved in phosphorylation-mediated gating of AQP4. The water permeability of AQP4-expressing Xenopus oocytes was not altered by a range of activators and inhibitors of PKG and PKA. Mutation of Ser(111) to alanine or aspartate (to prevent or mimic phosphorylation) did not change the water permeability of AQP4. PKG activation had no effect on the water permeability of AQP4 in primary cultures of rat astrocytes. Molecular dynamics simulations of a phosphorylation of AQP4.Ser(111) recorded no phosphorylation-induced change in water permeability. A phospho-specific antibody, exclusively recognizing AQP4 when phosphorylated on Ser(111) , failed to detect phosphorylation in cell lysate of rat brain stimulated by conditions proposed to induce phosphorylation of this residue. Thus, our data indicate a lack of phosphorylation of Ser(111) and of phosphorylation-dependent gating of AQP4. Copyright © 2013 Wiley Periodicals, Inc.

  13. Probenecid protects against transient focal cerebral ischemic injury by inhibiting HMGB1 release and attenuating AQP4 expression in mice.

    Science.gov (United States)

    Xiong, Xiao-Xing; Gu, Li-Juan; Shen, Jian; Kang, Xian-Hui; Zheng, Yue-Ying; Yue, Si-Biao; Zhu, Sheng-Mei

    2014-01-01

    Stroke results in inflammation, brain edema, and neuronal death. However, effective neuroprotectants are not available. Recent studies have shown that high mobility group box-1 (HMGB1), a proinflammatory cytokine, contributes to ischemic brain injury. Aquaporin 4 (AQP4), a water channel protein, is considered to play a pivotal role in ischemia-induced brain edema. More recently, studies have shown that pannexin 1 channels are involved in cerebral ischemic injury and the cellular inflammatory response. Here, we examined whether the pannexin 1 channel inhibitor probenecid could reduce focal ischemic brain injury by inhibiting cerebral inflammation and edema. Transient focal ischemia was induced in C57BL/6J mice by middle cerebral artery occlusion (MCAO) for 1 h. Infarct volume, neurological score and cerebral water content were evaluated 48 h after MCAO. Immunostaining, western blot analysis and ELISA were used to assess the effects of probenecid on the cellular inflammatory response, HMGB1 release and AQP4 expression. Administration of probenecid reduced infarct size, decreased cerebral water content, inhibited neuronal death, and reduced inflammation in the brain 48 h after stroke. In addition, HMGB1 release from neurons was significantly diminished and serum HMGB1 levels were substantially reduced following probenecid treatment. Moreover, AQP4 protein expression was downregulated in the cortical penumbra following post-stroke treatment with probenecid. These results suggest that probenecid, a powerful pannexin 1 channel inhibitor, protects against ischemic brain injury by inhibiting cerebral inflammation and edema.

  14. H95 Is a pH-Dependent Gate in Aquaporin 4

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    Kaptan, Shreyas; Assentoft, Mette; Schneider, Hans Peter

    2015-01-01

    Aquaporin 4 (AQP4) is a transmembrane protein from the aquaporin family and is the predominant water channel in the mammalian brain. The regulation of permeability of this protein could be of potential therapeutic use to treat various forms of damage to the nervous tissue. In this work, based on ...

  15. Expression of glucose transporter-1 and aquaporin-4 in the cerebral cortex of stroke-prone spontaneously hypertensive rats in relation to the blood-brain barrier function.

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    Ishida, Hiroyuki; Takemori, Kumiko; Dote, Kensaku; Ito, Hiroyuki

    2006-01-01

    Cerebral edema is an important initial event in cases of stroke among humans. Although hypertension is a major risk factor for endothelial injury, the precise mechanisms regulating brain microvascular changes are still unknown. To elucidate the pathogenesis of increases in vascular permeability in the cerebral cortex, we investigated the expression of glucose transporter-1 (GLUT-1) in endothelial cells and aquaporin-4 (AQP4) in astrocytes in relation to blood-brain barrier (BBB) function. Using male stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY), the particular localization of both GLUT-1 and AQP4 was investigated by immunohistochemistry. Quantitative changes in these molecules were examined by Western blot analysis in these rats at 6 weeks and 20 weeks of age. Furthermore, to investigate the expression of these molecules at the mRNA level, reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was carried out using 20-week-old SHRSP and age-matched WKY. We confirmed the localization of GLUT-1 in endothelial cells and that of AQP4 in the end feet of astrocytes around microvessels, as determined by electron immunohistochemistry. No significant differences were found in the expression of these molecules in rats at 6 weeks of age, whereas GLUT-1 expression was lower, but that of AQP4 was higher, in SHRSP after the establishment of hypertension. Furthermore, GLUT-1 mRNA expression was lower in SHRSP, and AQP4 mRNA expression was also lower in SHRSP than in WKY at 20 weeks of age. These results indicate that AQP4 may play a much more important role in BBB function than GLUT-1, and thereby also in water distribution in the cerebral cortex of SHRSP with severe hypertension.

  16. Peritumoral Brain Edema in Meningiomas Depends on Aquaporin-4 Expression and Not on Tumor Grade, Tumor Volume, Cell Count, or Ki-67 Labeling Index.

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    Gawlitza, Matthias; Fiedler, Eckhard; Schob, Stefan; Hoffmann, Karl-Titus; Surov, Alexey

    2017-04-01

    The aim of this study was to investigate to which degree the peritumoral brain edema in patients with meningiomas depends on aquaporin-4 (AQP4) expression, tumor grade, tumor volume, Ki-67 expression, and cell count. Thirty-three patients (25 women, 8 men; mean age 56.6 ± 16.0 years) with an intracranial meningioma underwent a standardized magnetic resonance (MR) examination prior to surgical resection. Edema indices (EIs) and tumor volumes were measured on the MR images. Tumor grade was classified according to the World Health Organization, and the proliferation index was estimated on Ki-67 antigen-stained specimens. Tumor cell count was evaluated. Eighteen specimens were stained for AQP4 expressioon. Significant intergroup differences between AQP4 expression grades and EIs were observed (P = 0.03), and a positive correlation was detected between EIs and AQP4 expression grades (r = 0.54; P tumor grading, tumor volume, Ki-67 expression, or cell count. Moreover, we observed no significant positive or negative correlations between the EI and tumor grading (P = 0.7), tumor volume (P = 0.19), Ki-67 index (P = 0.9), and cell count (P = 0.34). Peritumoral brain edema in patients with meningiomas may depend on AQP4 expression grades and not on tumor grade, tumor volume, Ki-67 expression, and cell count. The amount of edema predicted AQP4 expressions with moderate-to-good sensitivity and specificity.

  17. Aquaporin-4 in Astroglial Cells in the CNS and Supporting Cells of Sensory Organs—A Comparative Perspective

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    Corinna Gleiser

    2016-08-01

    Full Text Available The main water channel of the brain, aquaporin-4 (AQP4, is one of the classical water-specific aquaporins. It is expressed in many epithelial tissues in the basolateral membrane domain. It is present in the membranes of supporting cells in most sensory organs in a specifically adapted pattern: in the supporting cells of the olfactory mucosa, AQP4 occurs along the basolateral aspects, in mammalian retinal Müller cells it is highly polarized. In the cochlear epithelium of the inner ear, it is expressed basolaterally in some cells but strictly basally in others. Within the central nervous system, aquaporin-4 (AQP4 is expressed by cells of the astroglial family, more specifically, by astrocytes and ependymal cells. In the mammalian brain, AQP4 is located in high density in the membranes of astrocytic endfeet facing the pial surface and surrounding blood vessels. At these locations, AQP4 plays a role in the maintenance of ionic homeostasis and volume regulation. This highly polarized expression has not been observed in the brain of fish where astroglial cells have long processes and occur mostly as radial glial cells. In the brain of the zebrafish, AQP4 immunoreactivity is found along the radial extent of astroglial cells. This suggests that the polarized expression of AQP4 was not present at all stages of evolution. Thus, a polarized expression of AQP4 as part of a control mechanism for a stable ionic environment and water balanced occurred at several locations in supporting and glial cells during evolution. This initially basolateral membrane localization of AQP4 is shifted to highly polarized expression in astrocytic endfeet in the mammalian brain and serves as a part of the neurovascular unit to efficiently maintain homeostasis.

  18. Linking binge alcohol-induced neurodamage to brain edema and potential aquaporin-4 upregulation: evidence in rat organotypic brain slice cultures and in vivo.

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    Sripathirathan, Kumar; Brown, James; Neafsey, Edward J; Collins, Michael A

    2009-02-11

    Brain edema and derived oxidative stress potentially are critical events in the hippocampal-entorhinal cortical (HEC) neurodegeneration caused by binge alcohol (ethanol) intoxication and withdrawal in adult rats. Edema's role is based on findings that furosemide diuretic antagonizes binge alcohol-dependent brain overhydration and neurodamage in vivo and in rat organotypic HEC slice cultures. However, evidence that furosemide has significant antioxidant potential and knowledge that alcohol can cause oxidative stress through non-edemic pathways has placed edema's role in question. We therefore studied three other diuretics and a related non-diuretic that, according to our oxygen radical antioxidant capacity (ORAC) assays or the literature, possess minimal antioxidant potential. Acetazolamide (ATZ), a carbonic anhydrase inhibitor/diuretic with negligible ORAC effectiveness and, interestingly, an aquaporin-4 (AQP4) water channel inhibitor, prevented alcohol-dependent tissue edema and neurodegeneration in HEC slice cultures. Likewise, in binge alcohol-intoxicated rats, ATZ suppressed brain edema while inhibiting neurodegeneration. Torasemide, a loop diuretic lacking furosemide's ORAC capability, also prevented alcohol-induced neurodamage in HEC slice cultures. However, bumetanide (BUM), a diuretic blocker of Na(+)-K(+)-2Cl(-) channels, and L-644, 711, a nondiuretic anion channel inhibitor--both lacking antioxidant capabilities as well as reportedly ineffective against alcohol-dependent brain damage in vivo--reduced neither alcohol-induced neurotoxicity nor (with BUM) edema in HEC slices. Because an AQP4 blocker (ATZ) was neuroprotective, AQP4 expression in the HEC slices was examined and found to be elevated by binge alcohol. The results further indicate that binge ethanol-induced brain edema/swelling, potentially associated with AQP4 upregulation, may be important in consequent neurodegeneration that could derive from neuroinflammatory processes, for example, membrane

  19. Diagnostic utility of aquaporin-4 in the analysis of active demyelinating lesions

    Science.gov (United States)

    Popescu, Bogdan F.G.; Guo, Yong; Jentoft, Mark E.; Parisi, Joseph E.; Lennon, Vanda A.; Pittock, Sean J.; Weinshenker, Brian G.; Wingerchuk, Dean M.; Giannini, Caterina; Metz, Imke; Brück, Wolfgang; Shuster, Elizabeth A.; Carter, Jonathan; Boyd, Clara D.; Clardy, Stacey Lynn; Cohen, Bruce A.

    2015-01-01

    Objective: To assess, in a surgical biopsy cohort of active demyelinating lesions, the diagnostic utility of aquaporin-4 (AQP4) immunohistochemistry in identifying neuromyelitis optica (NMO) or NMO spectrum disorder (NMOSD) and describe pathologic features that should prompt AQP4 immunohistochemical analysis and AQP4–immunoglobulin G (IgG) serologic testing. Methods: This was a neuropathologic cohort study of 20 surgical biopsies (19 patients; 11 cord/9 brain), performed because of diagnostic uncertainty, interpreted as active demyelinating disease and containing 2 or more of the following additional features: tissue vacuolation, granulocytic infiltrates, or astrocyte injury. Results: AQP4 immunoreactivity was lost in 18 biopsies and increased in 2. Immunopathologic features of the AQP4 loss cohort were myelin vacuolation (18), dystrophic astrocytes and granulocytes (17), vascular hyalinization (16), macrophages containing glial fibrillary acid protein (GFAP)–positive debris (14), and Creutzfeldt-Peters cells (0). All 14 cases with available serum tested positive for AQP4-IgG after biopsy. Diagnosis at last follow-up was NMO/NMOSD (15) and longitudinally extensive transverse myelitis (1 each relapsing and single). Immunopathologic features of the AQP4 increased cohort were macrophages containing GFAP-positive debris and granulocytes (2), myelin vacuolation (1), dystrophic astrocytes (1), Creutzfeldt-Peters cells (1), and vascular hyalinization (1). Diagnosis at last follow-up was multiple sclerosis (MS) and both tested AQP4-IgG seronegative after biopsy. Conclusions: AQP4 immunohistochemistry with subsequent AQP4-IgG testing has diagnostic utility in identifying cases of NMO/NMOSD. This study highlights the importance of considering NMOSD in the differential diagnosis of tumefactive brain or spinal cord lesions. AQP4-IgG testing may avert biopsy and avoid ineffective therapies if these patients are erroneously treated for MS. PMID:25503621

  20. Histamine treatment induces rearrangements of orthogonal arrays of particles (OAPs) in human AQP4-expressing gastric cells

    Science.gov (United States)

    Carmosino, Monica; Procino, Giuseppe; Nicchia, Grazia Paola; Mannucci, Roberta; Verbavatz, Jean-Marc; Gobin, Renèe; Svelto, Maria; Valenti, Giovanna

    2001-01-01

    To test the involvement of the water channel aquaporin (AQP)-4 in gastric acid physiology, the human gastric cell line (HGT)-1 was stably transfected with rat AQP4. AQP4 was immunolocalized to the basolateral membrane of transfected HGT-1 cells, like in native parietal cells. Expression of AQP4 in transfected cells increased the osmotic water permeability coefficient (Pf) from 2.02 ± 0.3 × 10−4 to 16.37 ± 0.5 × 10−4 cm/s at 20°C. Freeze-fracture EM showed distinct orthogonal arrays of particles (OAPs), the morphological signature of AQP4, on the plasma membrane of AQP4-expressing cells. Quantitative morphometry showed that the density of OAPs was 2.5 ± 0.3% under basal condition and decreased by 50% to 1.2 ± 0.3% after 20 min of histamine stimulation, mainly due to a significant decrease of the OAPs number. Concomitantly, Pf decreased by ∼35% in 20-min histamine-stimulated cells. Both Pf and OAPs density were not modified after 10 min of histamine exposure, time at which the maximal hormonal response is observed. Cell surface biotinylation experiments confirmed that AQP4 is internalized after 20 min of histamine exposure, which may account for the downregulation of water transport. This is the first evidence for short term rearrangement of OAPs in an established AQP4-expressing cell line. PMID:11564760

  1. Intermittent Fasting Protects against Alzheimer’s Disease Possible through Restoring Aquaporin-4 Polarity

    Directory of Open Access Journals (Sweden)

    Jingzhu Zhang

    2017-11-01

    Full Text Available The impairment of amyloid-β (Aβ clearance in the brain plays a causative role in Alzheimer’s disease (AD. Polarity distribution of aquaporin-4 (AQP4 is important to remove Aβ from brain. AQP4 polarity can be influenced by the ratio of two AQP4 isoforms M1 and M23 (AQP4-M1/M23, however, it is unknown whether the ratio of AQP4-M1/M23 changes in AD. Histone deacetylase 3 has been reported to be significantly increased in AD brain. Moreover, evidence indicated that microRNA-130a (miR-130a possibly mediates the regulation of histone deacetylase 3 on AQP4-M1/M23 ratio by repressing the transcriptional activity of AQP4-M1 in AD. This study aimed to investigate whether intermittent fasting (IF, increasing the level of an endogenous histone deacetylases inhibitor β-hydroxybutyrate, restores AQP4 polarity via miR-130a mediated reduction of AQP4-M1/M23 ratio in protection against AD. The results showed that IF ameliorated cognitive dysfunction, prevented brain from Aβ deposition, and restored the AQP4 polarity in a mouse model of AD (APP/PS1 double-transgenic mice. Additionally, IF down-regulated the expression of AQP4-M1 and histone deacetylase 3, reduced AQP4-M1/M23 ratio, and increased miR-130a expression in the cerebral cortex of APP/PS1 mice. In vitro, β-hydroxybutyrate was found to down-regulate the expression of AQP4-M1 and histone deacetylase 3, reduce AQP4-M1/M23 ratio, and increase AQP4-M23 and miR-130a expression in 2 μM Aβ-treated U251 cells. Interestingly, on the contrary to the result observed in 2 μM Aβ-treated cells, AQP4 expression was obviously decreased in cells exposed to 10 μM Aβ. miR-130a mimic decreased the expression of AQP4-M1 and the ratio of AQP4-M1/M23, as well as silencing histone deacetylase 3 caused the up-regulation of AQP4 and miR-130a, and the reduction of AQP4-M1/M23 ratio in U251 cells. In conclusion, IF exhibits beneficial effects against AD. The mechanism may be associated with recovery of AQP4 polarity

  2. Intermittent Fasting Protects against Alzheimer's Disease Possible through Restoring Aquaporin-4 Polarity.

    Science.gov (United States)

    Zhang, Jingzhu; Zhan, Zhipeng; Li, Xinhui; Xing, Aiping; Jiang, Congmin; Chen, Yanqiu; Shi, Wanying; An, Li

    2017-01-01

    The impairment of amyloid-β (Aβ) clearance in the brain plays a causative role in Alzheimer's disease (AD). Polarity distribution of aquaporin-4 (AQP4) is important to remove Aβ from brain. AQP4 polarity can be influenced by the ratio of two AQP4 isoforms M1 and M23 (AQP4-M1/M23), however, it is unknown whether the ratio of AQP4-M1/M23 changes in AD. Histone deacetylase 3 has been reported to be significantly increased in AD brain. Moreover, evidence indicated that microRNA-130a (miR-130a) possibly mediates the regulation of histone deacetylase 3 on AQP4-M1/M23 ratio by repressing the transcriptional activity of AQP4-M1 in AD. This study aimed to investigate whether intermittent fasting (IF), increasing the level of an endogenous histone deacetylases inhibitor β-hydroxybutyrate, restores AQP4 polarity via miR-130a mediated reduction of AQP4-M1/M23 ratio in protection against AD. The results showed that IF ameliorated cognitive dysfunction, prevented brain from Aβ deposition, and restored the AQP4 polarity in a mouse model of AD (APP/PS1 double-transgenic mice). Additionally, IF down-regulated the expression of AQP4-M1 and histone deacetylase 3, reduced AQP4-M1/M23 ratio, and increased miR-130a expression in the cerebral cortex of APP/PS1 mice. In vitro, β-hydroxybutyrate was found to down-regulate the expression of AQP4-M1 and histone deacetylase 3, reduce AQP4-M1/M23 ratio, and increase AQP4-M23 and miR-130a expression in 2 μM Aβ-treated U251 cells. Interestingly, on the contrary to the result observed in 2 μM Aβ-treated cells, AQP4 expression was obviously decreased in cells exposed to 10 μM Aβ. miR-130a mimic decreased the expression of AQP4-M1 and the ratio of AQP4-M1/M23, as well as silencing histone deacetylase 3 caused the up-regulation of AQP4 and miR-130a, and the reduction of AQP4-M1/M23 ratio in U251 cells. In conclusion, IF exhibits beneficial effects against AD. The mechanism may be associated with recovery of AQP4 polarity, resulting from

  3. Molecular pathology of brain matrix metalloproteases, claudin5, and aquaporins in forensic autopsy cases with special regard to methamphetamine intoxication.

    Science.gov (United States)

    Wang, Qi; Ishikawa, Takaki; Michiue, Tomomi; Zhu, Bao-Li; Guan, Da-Wei; Maeda, Hitoshi

    2014-05-01

    Methamphetamine (METH) is a highly addictive drug of abuse and toxic to the brain. Recent studies indicated that besides direct damage to dopamine and 5-HT terminals, neurotoxicity of METH may also result from its ability to modify the structure of blood-brain barrier (BBB). The present study investigated the postmortem brain mRNA and immunohistochemical expressions of matrix metalloproteases (MMPs), claudin5 (CLDN5), and aquaporins (AQPs) in forensic autopsy cases of carbon monoxide (n = 14), METH (n = 21), and phenobarbital (n = 17) intoxication, compared with mechanical asphyxia (n = 15), brain injury (n = 11), non-brain injury (n = 21), and sharp instrument injury (n = 15) cases. Relative mRNA quantification using Taqman real-time PCR assay demonstrated higher expression of AQP4 and MMP9, lower expression of CLDN5 in METH intoxication cases and lower expression of MMP2 in phenobarbital intoxication cases. Immunostaining results showed substantial interindividual variations in each group, showing no evident differences in distribution or intensity among all the causes of death. These findings suggest that METH may increase BBB permeability by altering CLDN5 and MMP9, and the self-protective system maybe activated to eliminate accumulating water from the extracellular space of the brain by up-regulating AQP4. Systematic analysis of gene expressions using real-time PCR may be a useful procedure in forensic death investigation.

  4. Test of the 'glymphatic' hypothesis demonstrates diffusive and aquaporin-4-independent solute transport in rodent brain parenchyma

    Science.gov (United States)

    Yao, Xiaoming; Dix, James A; Jin, Byung-Ju

    2017-01-01

    Transport of solutes through brain involves diffusion and convection. The importance of convective flow in the subarachnoid and paravascular spaces has long been recognized; a recently proposed ‘glymphatic’ clearance mechanism additionally suggests that aquaporin-4 (AQP4) water channels facilitate convective transport through brain parenchyma. Here, the major experimental underpinnings of the glymphatic mechanism were re-examined by measurements of solute movement in mouse brain following intracisternal or intraparenchymal solute injection. We found that: (i) transport of fluorescent dextrans in brain parenchyma depended on dextran size in a manner consistent with diffusive rather than convective transport; (ii) transport of dextrans in the parenchymal extracellular space, measured by 2-photon fluorescence recovery after photobleaching, was not affected just after cardiorespiratory arrest; and (iii) Aqp4 gene deletion did not impair transport of fluorescent solutes from sub-arachnoid space to brain in mice or rats. Our results do not support the proposed glymphatic mechanism of convective solute transport in brain parenchyma. PMID:28826498

  5. Abnormal distribution of AQP4 in minor salivary glands of primary Sjögren's syndrome patients.

    Science.gov (United States)

    Sisto, Margherita; Lorusso, Loredana; Ingravallo, Giuseppe; Nico, Beatrice; Ribatti, Domenico; Ruggieri, Simona; Lofrumento, Dario Domenico; Lisi, Sabrina

    2017-06-01

    A decreased saliva production occurs in primary Sjögren's syndrome (pSS), an autoimmune disease characterized by oral and ocular dryness due to dysfunction of the lacrimal and salivary glands (SGs). Since water movement is involved in saliva secretion, the expression, localization, and function of the water channels aquaporins (AQPs) have been extensively studied in SGs. To date, the presence of AQP4 remains controversial and ambiguous in human SGs. We investigated by immunohistochemistry, high-resolution confocal microscopy and quantitative image analysis, Western blot and real-time RT-PCR, the presence of the AQP4 gene, and the distribution of AQP4 protein in healthy controls and pSS SG biopsies. Through the immunohistochemical analysis, we demonstrated that AQP4 presence is confined to the basal region of acini, to the lateral and apical membrane of intercalated and striated ducts in both control and pSS glands. The most striking observation was the discovery of AQP4 localization in myoepithelial cells (MECs) that surround acini lobules and intercalated ducts, and the demonstration of AQP4-downregulated immunoreactivity in pSS MECs. Our studies suggest that the capacity for water flow across the membrane of MECs may be altered in pSS, identifying AQP4 as a promising new therapeutic agent to treat xerostomia.

  6. Differential water permeability and regulation of three aquaporin 4 isoforms

    DEFF Research Database (Denmark)

    Fenton, Robert A; Moeller, Hanne B; Zelenina, Marina

    2010-01-01

    Aquaporin 4 (AQP4) is expressed in the perivascular glial endfeet and is an important pathway for water during formation and resolution of brain edema. In this study, we examined the functional properties and relative unit water permeability of three functional isoforms of AQP4 expressed...... in the brain (M1, M23, Mz). The M23 isoform gave rise to square arrays when expressed in Xenopus laevis oocytes. The relative unit water permeability differed significantly between the isoforms in the order of M1 > Mz > M23. None of the three isoforms were permeable to small osmolytes nor were they affected...... by changes in external K(+) concentration. Upon protein kinase C (PKC) activation, oocytes expressing the three isoforms demonstrated rapid reduction of water permeability, which correlated with AQP4 internalization. The M23 isoform was more sensitive to PKC regulation than the longer isoforms...

  7. Aquaporin-4: A Potential Therapeutic Target for Cerebral Edema

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    Guanghui Tang

    2016-09-01

    Full Text Available Aquaporin-4 (AQP4 is a family member of water-channel proteins and is dominantly expressed in the foot process of glial cells surrounding capillaries. The predominant expression at the boundaries between cerebral parenchyma and major fluid compartments suggests the function of aquaporin-4 in water transfer into and out of the brain parenchyma. Accumulating evidences have suggested that the dysregulation of aquaporin-4 relates to the brain edema resulting from a variety of neuro-disorders, such as ischemic or hemorrhagic stroke, trauma, etc. During edema formation in the brain, aquaporin-4 has been shown to contribute to the astrocytic swelling, while in the resolution phase, it has been seen to facilitate the reabsorption of extracellular fluid. In addition, aquaporin-4-deficient mice are protected from cytotoxic edema produced by water intoxication and brain ischemia. However, aquaporin-4 deletion exacerbates vasogenic edema in the brain of different pathological disorders. Recently, our published data showed that the upregulation of aquaporin-4 in astrocytes probably contributes to the transition from cytotoxic edema to vasogenic edema. In this review, apart from the traditional knowledge, we also introduce our latest findings about the effects of mesenchymal stem cells (MSCs and microRNA-29b on aquaporin-4, which could provide powerful intervention tools targeting aquaporin-4.

  8. Effect of Alcohol on Diffuse Axonal Injury in Rat Brainstem: Diffusion Tensor Imaging and Aquaporin-4 Expression Study

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    Lingmei Kong

    2013-01-01

    Full Text Available The aim of this study is to assess the effects of alcohol on traumatic brain injury by using diffusion tensor imaging (DTI and evaluate aquaporin-4(AQP4 expression changes in rat brainstems following acute alcohol intoxication with diffuse axonal injury (DAI. We further investigated the correlation between the AQP4 expression and DTI in the brain edema. Eighty-five rats were imaged before and after injury at various stages. DTI was used to measure brainstem apparent diffusion coefficient (ADC and fractional anisotropy (FA, with immunostaining being used to determine AQP4 expression. After acute alcoholism with DAI, ADC values of the brainstem first decreased within 6 h and then elevated. FA values began to decline by 1 h, reaching a minimum at 24 h after trauma. There was a negative correlation between ADC values and brainstem AQP4 expression at 6 h and positive correlation at 6 h to 24 h. Changes of ADC and FA values in DAI with acute alcoholism indicate the effects of ethanol on brain edema and the severity of axonal injury. The correlations between ADC values and the brainstem AQP4 expression at different time points suggest that AQP4 expression follows an adaptative profile to the severity of brain edema.

  9. Treadmill pre-training ameliorates brain edema in ischemic stroke via down-regulation of aquaporin-4: an MRI study in rats.

    Science.gov (United States)

    He, Zhijie; Wang, Xiaolou; Wu, Yi; Jia, Jie; Hu, Yongshan; Yang, Xiaojiao; Li, Jianqi; Fan, Mingxia; Zhang, Li; Guo, Jinchun; Leung, Mason C P

    2014-01-01

    Treadmill pre-training can ameliorate blood brain barrier (BBB) dysfunction in ischemia-reperfusion injury, however, its role in ischemic brain edema remains unclear. This study assessed the neuroprotective effects induced by treadmill pre-training, particularly on brain edema in transient middle cerebral artery occluded model. Transient middle cerebral artery occlusion to induce stroke was performed on rats after 2 weeks of treadmill pre-training. Magnetic resonance imaging (MRI) was used to evaluate the dynamic impairment of cerebral edema after ischemia-reperfusion injury. In addition, measurements of wet and dry brain weight, Evans Blue assay and Garcia scores were performed to investigate the cerebral water content, BBB permeability and neurologic deficit, respectively. Moreover, during ischemia-reperfusion injury, the expression of Aquaporin 4 (AQP4) was detected using immunofluorescence and Western bloting analyses. Treadmill pre-training improved the relative apparent diffusion coefficient (rADC) loss in the ipsilateral cortex and striatum at 1 hour and 2.5 hours after cerebral ischemia. In the treadmill pre-training group, T2W1 values of the ipsilateral cortex and striatum increased less at 7.5 hours, 1 day, and 2 days after stroke while the brain water content decreased at 2 days after ischemia. Regarding the BBB permeability, the semi-quantitative amount of contrast agent leakage of treadmill pre-training group significantly decreased. Less Evans Blue exudation was also observed in treadmill pre-training group at 2 days after stroke. In addition, treadmill pre-training mitigated the Garcia score deficits at 2 days after stroke. Immunofluorescence staining and Western blotting results showed a significant decrease in the expression of AQP4 after treadmill ischemia following pre-training. Treadmill pre-training may reduce cerebral edema and BBB dysfunction during cerebral ischemia/reperfusion injury via the down-regulation of AQP4.

  10. Aquaporin-4 IgG autoimmune syndrome and immunoreactivity associated with thyroid cancer

    DEFF Research Database (Denmark)

    Soelberg, Kerstin; Larsen, Stine Rosenkilde; Mørch, Marlene

    2016-01-01

    Tumor cells can express so-called onconeural antigens, which are normally restricted to mature neurons and glial cells in the CNS.1 The detection of neural-reactive immunoglobulin G (IgG) aids the diagnosis of paraneoplastic neurologic syndromes (PNS)1; however, the diagnostic utility and potential...... pathogenicity of autoantibodies vary between neurologic diseases. By contrast, anti-aquaporin-4 (AQP4) IgG from patients with neuromyelitis optica spectrum disorder (NMOSD) is a specific biomarker for NMOSD. AQP4 is the most abundant water channel in the CNS, particularly abundant on astrocytes, forming...... the glia limitans of the blood–brain barrier. There is compelling evidence that AQP4-IgG reactivity and pathogenicity is restricted to the CNS, probably through an impaired blood–brain barrier. The clinical features of NMOSD include inflammation of the optic nerve, spinal cord, and specific brain areas...

  11. Cellular and subcellular aquaporin-4 distribution in the mouse neurohypophysis and the effects of osmotic stimulation.

    Science.gov (United States)

    Mesbah-Benmessaoud, Ouahiba; Benabdesselam, Roza; Hardin-Pouzet, Hélène; Dorbani-Mamine, Latifa; Grange-Messent, Valérie

    2011-01-01

    Water channel aquaporin-4 (AQP4) is the most abundant water channel in the rodent brain and is mainly expressed in cerebral areas involved in central osmoreception and osmoregulation. The neurohypophysis is the release site of hypothalamic neurohormones vasopressin and oxytocin, which are involved in the regulation of the water balance. The authors investigated the cellular and subcellular distribution of AQP4 in the mouse neurohypophysis before and after chronic osmotic stimulation, using immunofluorescence microscopy and immunoperoxidase electron microscopy. They showed that AQP4 was abundant in the mouse hypophysis, mainly in the neural lobe. AQP4 was discontinuously distributed along pituicytes plasma membranes, in the dense neurosecretory granules and microvesicles of nerve endings and fibers, and along the luminal and abluminal membranes of fenestrated capillary endothelial cells. After chronic osmotic stimulation, AQP4 immunolabeling was enhanced. Taken together, these results suggest that AQP4 could be involved in the pituicyte sensor effect during osmoregulation, the modification and/or maturation mechanism of neurosecretory granules during neurohormone release, and the blood perfusion of the hypophysis.

  12. Lack of association between AQP4 polymorphisms and risk of inflammatory demyelinating disease in a Korean population.

    Science.gov (United States)

    Park, Tae-Joon; Kim, Jeong-Hyun; Kim, Ho Jin; Bae, Joon Seol; Cheong, Hyun Sub; Park, Byung Lae; Shin, Hyoung Doo

    2014-02-25

    Multiple sclerosis (MS) and neuromyelitis optica (NMO) are demyelinating autoimmune inflammatory diseases that affect the central nervous system (CNS). Previous genome-wide or candidate gene studies have suggested that genetic variants might be associated with the risk of MS or NMO. Aquaporin 4 (AQP4) is a commonly distributed water channel in astrocytes of the CNS, and its expression is decreased in NMO lesions due to astrocyte cytotoxicity. Previous studies have suggested the associations of AQP4 single nucleotide polymorphisms (SNPs) with MS and/or NMO. However, there have been few replication studies in various ethnic populations. This study, as the first of its kind performed in an Asian population, investigated associations of AQP4 SNPs with the risk of inflammatory demyelinating disease (IDD), including MS and NMO, in a Korean population. A total of seven common AQP4 SNPs were selected based on status of linkage disequilibrium (LD), and then genotyped in 178 IDD cases (79 MS and 99 NMO patients) and 237 normal controls. Statistical analyses showed no significant associations between AQP4 SNPs/haplotypes and development of IDD, including MS and NMO (P>0.05). Further replications in larger cohorts and other ethnic groups are needed. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Fluoxetine requires the endfeet protein aquaporin-4 to enhance plasticity of astrocyte processes

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    Barbara eDi Benedetto

    2016-02-01

    Full Text Available Morphological alterations in astrocytes are characteristic for post mortem brains of patients affected by major depressive disorder (MDD. Recently, a significant reduction in the coverage of blood vessels (BVs by aquaporin-4 (AQP-4-positive astrocyte endfeet has been shown in the prefrontal cortex (PFC of MDD patients, suggesting that either alterations in the morphology of endfeet or in AQP-4 distribution might be responsible for the disease phenotype or constitute a consequence of its progress. Antidepressant drugs (ADs regulate the expression of several proteins, including astrocyte-specific ones. Thus, they may target AQP-4 to induce morphological changes in astrocytes and restore their proper shape or relocate AQP-4 to endfeet. Using an animal model of depression, rats selectively bred for high anxiety-like behavior (HAB, we confirmed a reduced coverage of BVs in the adult PFC by AQP-4-immunoreactive (AQP-4-IR astrocyte processes with respect to nonselected Wistar rats (NAB, thereby validating it for our study. A further evaluation of the morphology of astrocyte in brain slices (ex vivo and in vitro using an antibody against the astrocyte-specific cytoskeletal protein glial fibrillary acidic protein (GFAP revealed that HAB astrocytes extended less processes than NAB cells. Furthermore, short-term drug treatment in vitro with the AD fluoxetine (FLX was sufficient to increase the plasticity of astrocyte processes, enhancing their number in NAB-derived cells and recovering their basal number in HAB-derived cells. This enhanced FLX-dependent plasticity occurred, however, only in the presence of intact AQP-4, as demonstrated by the lack of effect after the downregulation of AQP-4 with RNAi in both NAB and HAB cells. Nonetheless, a similar short-term treatment did neither modulate the coverage of BVs with AQP-4-positive astrocyte endfeet in NAB nor in HAB rats, although dosage and time of treatment were sufficient to fully recover GFAP expression

  14. Age-Related Modulations of AQP4 and Caveolin-1 in the Hippocampus Predispose the Toxic Effect of Phoneutria nigriventer Spider Venom

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    Edilene S. Soares

    2016-11-01

    Full Text Available We have previously demonstrated that Phoneutria nigriventer venom (PNV causes blood–brain barrier (BBB breakdown, swelling of astrocytes end-feet and fluid permeation into brain interstitium in rats. Caveolae and water channels respond to BBB alterations by co-participation in shear stress response and edema formation/resolution. Herein, we showed post-natal developmental-related changes of two BBB-associated transporter proteins: the endothelial caveolin-1 (Cav-1, the major scaffolding protein from caveolae frame, and the astroglial aquaporin-4 (AQP4, the main water channel protein expressed in astrocytic peri-vascular end-feet processes, in the hippocampus of rats intraperitoneally-administered PNV. Western blotting protein levels; immunohistochemistry (IHC protein distribution in CA1, CA2, and CA3 subfields; and gene expression by Real Time-Polymerase Chain Reaction (qPCR were assessed in post-natal Day 14 (P14 and 8–10-week-old rats over critical periods of envenomation. The intensity and duration of the toxic manifestations indicate P14 neonate rats more vulnerable to PNV than adults. Histologically, the capillaries of P14 and 8–10-week-old rats treated with PNV showed perivascular edema, while controls did not. The intensity of the toxic manifestations in P14 decreases temporally (2 > 5 > 24 h, while inversely the expression of AQP4 and Cav-1 peaked at 24 h when clinically PNV-treated animals do not differ from saline controls. IHC of AQP4 revealed that hippocampal CA1 showed the least expression at 2 h when toxic manifestation was maximal. Subfield IHC quantification revealed that in P14 rats Cav-1 peaked at 24 h when toxic manifestations were absent, whereas in 8–10-week-old rats Cav-1 peaked at 2 h when toxic signs were highest, and progressively attenuated such increases until 24 h, remaining though significantly above baseline. Considering astrocyte-endothelial physical and functional interactions, we hypothesize that age

  15. Aquaporin 9 in rat brain after severe traumatic brain injury

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    Hui Liu

    2012-03-01

    Full Text Available OBJECTIVE: To reveal the expression and possible roles of aquaporin 9 (AQP9 in rat brain, after severe traumatic brain injury (TBI. METHODS: Brain water content (BWC, tetrazolium chloride staining, Evans blue staining, immunohistochemistry (IHC, immunofluorescence (IF, western blot, and real-time polymerase chain reaction were used. RESULTS: The BWC reached the first and second (highest peaks at 6 and 72 hours, and the blood brain barrier (BBB was severely destroyed at six hours after the TBI. The worst brain ischemia occurred at 72 hours after TBI. Widespread AQP9-positive astrocytes and neurons in the hypothalamus were detected by means of IHC and IF after TBI. The abundance of AQP9 and its mRNA increased after TBI and reached two peaks at 6 and 72 hours, respectively, after TBI. CONCLUSIONS: Increased AQP9 might contribute to clearance of excess water and lactate in the early stage of TBI. Widespread AQP9-positive astrocytes might help lactate move into neurons and result in cellular brain edema in the later stage of TBI. AQP9-positive neurons suggest that AQP9 plays a role in energy balance after TBI.

  16. Aquaporin 4 Molecular Mimicry and Implications for Neuromyelitis Optica

    OpenAIRE

    Vaishnav, Radhika A.; Liu, Ruolan; Chapman, Joab; Andrew M Roberts; Ye, Hong; Rebolledo-Mendez, Jovan D.; Tabira, Takeshi; Fitzpatrick, Alicia H.; Achiron, Anat; Running, Mark P.; Friedland, Robert P.

    2013-01-01

    Neuromyelitis Optica (NMO) is associated with antibodies to aquaporin 4 (AQP4). We hypothesized that antibodies to AQP4 can be triggered by exposure to environmental proteins. We compared human AQP4 to plant and bacterial proteins to investigate the occurrence of significantly similar structures and sequences. High similarity to a known epitope for NMO-IgG, AQP4(207-232), was observed for corn ZmTIP4-1. NMO and non-NMO serum was assessed for reactivity to AQP4(207-232) and the corn peptide. N...

  17. What proportion of AQP4-IgG-negative NMO spectrum disorder patients are MOG-IgG positive? A cross sectional study of 132 patients.

    Science.gov (United States)

    Hamid, Shahd H M; Whittam, Daniel; Mutch, Kerry; Linaker, Samantha; Solomon, Tom; Das, Kumar; Bhojak, Maneesh; Jacob, Anu

    2017-08-24

    Antibodies to myelin oligodendrocyte glycoprotein (MOG-IgG) have been described in patients with neuromyelitis optica spectrum disorders (NMOSD) without aquaporin-4 antibodies (AQP4-IgG). We aimed to identify the proportion of AQP4-IgG-negative NMOSD patients who are seropositive for MOG-IgG. In a cross sectional study, we reviewed all patients seen in the National NMO clinic over the last 4 years (after the availability of MOG-IgG testing), including clinical information, MRI, and antibody tests. 261 unique patients were identified. 132 cases satisfied the 2015 NMOSD diagnostic criteria. Of these, 96 (73%) were AQP4-IgG positive and 36 (27%) were AQP4-IgG negative. These 36 patients were tested for MOG-IgG and 15/36 (42%) tested positive. 20% (25/125) of the patients who did not satisfy NMOSD criteria had MOG-IgG. Approximately half of seronegative NMOSD is MOG-Ig seropositive and one in five of non-NMOSD/non-MS demyelination is MOG-IgG positive. Since MOG-associated demyelinating disease is likely different from AQP4-IgG disease in terms of underlying disease mechanisms, relapse risk and possibly treatment, testing for MOG-IgG in patients with AQP4-IgG-negative NMOSD and other non-MS demyelination may have significant implications to management and clinical trials.

  18. Neuromyelitis optica spectrum disorders: comparison of clinical and magnetic resonance imaging characteristics of AQP4-IgG versus MOG-IgG seropositive cases in the Netherlands.

    Science.gov (United States)

    van Pelt, E D; Wong, Y Y M; Ketelslegers, I A; Hamann, D; Hintzen, R Q

    2016-03-01

    Neuromyelitis optica spectrum disorders (NMOSDs) are a group of rare inflammatory demyelinating disorders of the central nervous system. The identification of specific antibodies directed to aquaporin 4 (AQP4-IgG) led to the distinction from multiple sclerosis. However, up to 25% of the clinically diagnosed NMO patients are seronegative for AQP4-IgG. A subgroup of these patients might be identified by antibodies directed to myelin oligodendrocyte glycoprotein (MOG-IgG). Our objective was to investigate whether the clinical characteristics of these patients differ. Using a cell-based assay, samples of 61 AQP4-IgG seronegative patients and 41 AQP4-IgG seropositive patients with clinically NMOSD were analysed for the presence of MOG-IgG. Clinical characteristics of the AQP4-IgG, MOG-IgG seropositive and double seronegative NMOSD patients were compared. Twenty of the 61 AQP4-IgG seronegative patients tested MOG-IgG seropositive (33%). MOG-IgG seropositive patients were more frequently males in contrast to AQP4-IgG seropositive patients (55% vs. 15%, P IgG seropositive patients were 2.4 times more likely to suffer from relapses compared with MOG-IgG seropositive patients (relative risk 2.4, 95% confidence interval 1.2-4.7). AQP4-IgG seropositive patients had higher Expanded Disability Status Scale levels at last follow-up (P IgG seronegative NMO patients with generally a favourable monophasic disease course. © 2015 EAN.

  19. Eye movement abnormalities in AQP4-IgG positive neuromyelitis optica spectrum disorder.

    Science.gov (United States)

    Sun, Houliang; Cui, Shilei; Gao, Fei; You, Qisheng; Li, Yong; Wang, Jiawei; Zhang, Xiaojun

    2018-01-15

    Neuromyelitis optica spectrum disorder (NMOSD) has been recognized as a disease characterized by severe visual afferent impairment. Abnormal eye movements, as the other important neuro-ophthalmic manifestation of NMOSD, were commonly overlooked. The aim of our study was to describe the ocular motor manifestations of AQP4-IgG positive NMOSD patients, and explore the value of eye movement abnormalities in the evaluation of the disabled disease. Systemic clinical bedside ocular motor examinations and quantitative horizontal saccadic eye movement assessments were performed in 90 patients with AQP4-IgG positive NMOSD. General disability was evaluated by expanded disability status scale (EDSS). Vision-specific functional status was evaluated by the National Eye Institute-Visual Function Questionnaire (NEI-VFQ 25) and the 10-item neuro-ophthalmic supplement. Brain magnetic resonance imaging (MRI) was acquired in all patients. In clinical examination, eye movement abnormalities were found in 38% of NMOSD patients. Abnormalities in the quantitative saccadic test were found in 67% of NMOSD patients, including 48% of patients with clinically normal eye movements. EDSS scores in patients with clinical eye movement abnormality were significantly higher (Peye movement abnormalities (P=0.031). Eye movement abnormalities were common in AQP4-IgG positive NMOSD patients, and were associated with general disability and specific visual handicap. The systemic clinical eye movement examination combined with the quantitative saccade test was easy to perform, and could provide additional useful information in evaluating NMOSD. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Detection of Antibodies against Human and Plant Aquaporins in Patients with Multiple Sclerosis

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    Aristo Vojdani

    2015-01-01

    Full Text Available Multiple sclerosis (MS is an autoimmune disease that affects the body’s central nervous system. Around 90% of MS sufferers are diagnosed with relapsing-remitting MS (RRMS. We used ELISA to measure IgG, IgA, and IgM antibodies against linear epitopes of human and plant aquaporins (AQP4 as well as neural antigens in RRMS patients and controls to determine whether patients suffering from RRMS have simultaneous elevations in antibodies against these peptides and antigens. In comparison to controls, significant elevations in isotype-specific antibodies against human and plant AQP4 and neural antigens such as MBP, MOG, and S100B were detected in RRMS patients, indicating a high correlation in antibody reaction between plant aquaporins and brain antigens. This correlation between the reactivities of RRMS patients with various tested antigens was the most significant for the IgM isotype. We conclude that a subclass of patients with RRMS reacts to both plant and human AQP4 peptides. This immune reaction against different plant aquaporins may help in the development of dietary modifications for patients with MS and other neuroimmune disorders.

  1. Goreisan Inhibits Upregulation of Aquaporin 4 and Formation of Cerebral Edema in the Rat Model of Juvenile Hypoxic-Ischemic Encephalopathy

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    Yoshiaki Yano

    2017-01-01

    Full Text Available Secondary cerebral edema regulation is of prognostic significance in hypoxic-ischemic encephalopathy (HIE, and aquaporin 4 (AQP4 plays an important role in the pathogenesis of cerebral edema. The traditional Japanese herbal medicine Goreisan relieves brain edema in adults; however, its effect and pharmacological mechanism in children are unknown. We investigated the effects of Goreisan on HIE-associated brain edema and AQP4 expression in a juvenile rat model, established by combined occlusion of middle cerebral and common carotid arteries. Magnetic resonance imaging showed that the lesion areas were significantly smaller in the Goreisan- (2 g/kg treated group than in the nontreated (saline group at 24 and 48 h postoperatively. AQP4 mRNA levels in the lesion and nonlesion sides were significantly suppressed in the Goreisan group compared with the nontreated group 36 h postoperatively. Western blotting revealed that levels of AQP4 protein were significantly decreased in the Goreisan group compared with the nontreated group in the lesion side 72 h postoperatively, but not at 12 or 36 h. After 14 days, the Goreisan group had a significantly better survival rate. These findings suggest that Goreisan suppresses brain edema in HIE and improves survival in juvenile rats, possibly via regulation of AQP4 expression and function.

  2. Age-related hearing loss: Aquaporin 4 gene expression changes in the mouse cochlea and auditory midbrain

    Science.gov (United States)

    Christensen, Nathan; D'Souza, Mary; Zhu, Xiaoxia; Frisina, Robert D.

    2009-01-01

    Presbycusis – age-related hearing loss, is the number one communication disorder, and one of the top three chronic medical conditions of our aged population. Aquaporins, particularly aquaporin 4 (Aqp4), are membrane proteins with important roles in water and ion flux across cell membranes, including cells of the inner ear and pathways of the brain used for hearing. To more fully understand the biological bases of presbycusis, 39 CBA mice, a well-studied animal model of presbycusis, underwent non-invasive hearing testing as a function of sound frequency (auditory brainstem response – ABR thresholds, and distortion-product otoacoustic emission – DPOAE magnitudes), and were clustered into four groups based on age and hearing ability. Aqp4 gene expression, as determined by genechip microarray analysis and quantitative real-time PCR, was compared to the young adult control group in the three older groups: middle aged with good hearing, old age with mild presbycusis, and old age with severe presbycusis. Linear regression and ANOVA showed statistically significant changes in Aqp4 gene expression and ABR and DPOAE hearing status in the cochlea and auditory midbrain – inferior colliculus. Down-regulation in the cochlea was seen, and an initial down-, then up-regulation was discovered for the inferior colliculus Aqp4 expression. It is theorized that these changes in Aqp4 gene expression represent an age-related disruption of ion flux in the fluids of the cochlea that are responsible for ionic gradients underlying sound transduction in cochlear hair cells necessary for hearing. In regard to central auditory processing at the level of the auditory midbrain, aquaporin gene expression changes may affect neurotransmitter cycling involving supporting cells, thus impairing complex sound neural processing with age. PMID:19070604

  3. Age-related hearing loss: aquaporin 4 gene expression changes in the mouse cochlea and auditory midbrain.

    Science.gov (United States)

    Christensen, Nathan; D'Souza, Mary; Zhu, Xiaoxia; Frisina, Robert D

    2009-02-09

    Presbycusis -- age-related hearing loss, is the number one communication disorder, and one of the top three chronic medical conditions of our aged population. Aquaporins, particularly aquaporin 4 (Aqp4), are membrane proteins with important roles in water and ion flux across cell membranes, including cells of the inner ear and pathways of the brain used for hearing. To more fully understand the biological bases of presbycusis, 39 CBA mice, a well-studied animal model of presbycusis, underwent non-invasive hearing testing as a function of sound frequency (auditory brainstem response -- ABR thresholds, and distortion-product otoacoustic emission -- DPOAE magnitudes), and were clustered into four groups based on age and hearing ability. Aqp4 gene expression, as determined by genechip microarray analysis and quantitative real-time PCR, was compared to the young adult control group in the three older groups: middle aged with good hearing, old age with mild presbycusis, and old age with severe presbycusis. Linear regression and ANOVA showed statistically significant changes in Aqp4 gene expression and ABR and DPOAE hearing status in the cochlea and auditory midbrain -- inferior colliculus. Down-regulation in the cochlea was seen, and an initial down-, then up-regulation was discovered for the inferior colliculus Aqp4 expression. It is theorized that these changes in Aqp4 gene expression represent an age-related disruption of ion flux in the fluids of the cochlea that are responsible for ionic gradients underlying sound transduction in cochlear hair cells necessary for hearing. In regard to central auditory processing at the level of the auditory midbrain, aquaporin gene expression changes may affect neurotransmitter cycling involving supporting cells, thus impairing complex sound neural processing with age.

  4. Functional analysis of the aquaporin gene family in Caenorhabditis elegans

    National Research Council Canada - National Science Library

    Chunyi George Huang; Todd Lamitina; Peter Agre; Kevin Strange

    .... Eight canonical aquaporin-encoding genes (aqp) are present in the worm genome. Expression of aqp-2, aqp-3, aqp-4, aqp-6, or aqp-7 in Xenopus oocytes increased water permeability five- to sevenfold...

  5. Relative CO2/NH3 selectivities of AQP1, AQP4, AQP5, AmtB, and RhAG.

    Science.gov (United States)

    Musa-Aziz, Raif; Chen, Li-Ming; Pelletier, Marc F; Boron, Walter F

    2009-03-31

    The water channel aquaporin 1 (AQP1) and certain Rh-family members are permeable to CO(2) and NH(3). Here, we use changes in surface pH (pH(S)) to assess relative CO(2) vs. NH(3) permeability of Xenopus oocytes expressing members of the AQP or Rh family. Exposed to CO(2) or NH(3), AQP1 oocytes exhibit a greater maximal magnitude of pH(S) change (DeltapH(S)) compared with day-matched controls injected with H(2)O or with RNA encoding SGLT1, NKCC2, or PepT1. With CO(2), AQP1 oocytes also have faster time constants for pH(S) relaxation (tau(pHs)). Thus, AQP1, but not the other proteins, conduct CO(2) and NH(3). Oocytes expressing rat AQP4, rat AQP5, human RhAG, or the bacterial Rh homolog AmtB also exhibit greater DeltapH(S)(CO(2)) and faster tau(pHs) compared with controls. Oocytes expressing AmtB and RhAG, but not AQP4 or AQP5, exhibit greater DeltapH(S)(NH(3)) values. Only AQPs exhibited significant osmotic water permeability (P(f)). We computed channel-dependent (*) DeltapH(S) or P(f) by subtracting values for H(2)O oocytes from those of channel-expressing oocytes. For the ratio DeltapH(S)(CO(2))*/P(f)*, the sequence was AQP5 > AQP1 congruent with AQP4. For DeltapH(S)(CO(2))*/DeltapH(S)(NH(3))*, the sequence was AQP4 congruent with AQP5 > AQP1 > AmtB > RhAG. Thus, each channel exhibits a characteristic ratio for indices of CO(2) vs. NH(3) permeability, demonstrating that, like ion channels, gas channels can exhibit selectivity.

  6. Aquaporin-3 and aquaporin-4 are sorted differently and separately in the trans-Golgi network.

    Directory of Open Access Journals (Sweden)

    Eva C Arnspang

    Full Text Available Aquaporin-3 (AQP3 and aquaporin-4 (AQP4 are homologous proteins expressed in the basolateral plasma membrane of kidney collecting duct principal cells, where they mediate the exit pathway for apically reabsorbed water. Although both proteins are localized to the same plasma membrane domain, it is unknown if they are sorted together in the Golgi, or arrive in the same or different vesicles at the plasma membrane. We addressed these questions using high resolution deconvolution imaging, spinning disk and laser scanning confocal microscopy of cells expressing AQP3 and AQP4. AQP3 and AQP4 were observed mostly in separate post-Golgi carriers, and spinning disk microscopy showed that most of AQP3 and AQP4 were delivered to the plasma membrane in separate vesicles. In contrast, VSV-G and LDL-R, two well-characterized basolateral proteins, co-localized to a high degree in the same post-Golgi carriers, indicating that the differential sorting of AQP3 and AQP4 is specific and regulated. Significantly, a chimeric AQP3 containing the AQP4 cytoplasmic tails co-localized with AQP4 in post-Golgi vesicles. These results indicate that AQP3 and AQP4 are separated into different post-Golgi carriers based on different cytoplasmic domain sorting signals, and are then delivered separately to the plasma membrane.

  7. Analysis of clinical features of five multiple sclerosis patients with positive serum aquaporin 4 antibody

    Directory of Open Access Journals (Sweden)

    Yang HE

    2015-03-01

    Full Text Available Objective To investigate the clinical features of multiple sclerosis (MS patients with positive serum aquaporin 4 (AQP4 antibody.  Methods A total of 18 MS patients who had been diagnosed in accord with McDonald Criteria (2010 were enrolled and were divided into AQP4 positive group (N = 5 and AQP4 negative group (N = 13. In combination with accessory examination, clinical features and laboratory data of MS patients were correlatively studied between 2 groups in association with follow-up study in Outpatient Clinic.  Results Five seropositive patients, including 2 men and 3 women, were collected. The median age of onset was 43 years and the median clinical course was 4 months. Compared with patients with negative AQP4 antibody, MS patients with positive AQP4 antibody demonstrated increased spinal cord lesions and optic nerve involvement. MRI revealed multiple abnormal long T1 and long T2 signals in brain and cervicothoracic spinal cord (3/5, and multiple  abnormal long T1 and long T2 signals in cervicothoracic spinal cord (2/5 in seropositive group. Relatively more patients in seropositive group had increased cerebral spinal fluid (CSF IgG index (4/4 and 24 h intrathecal IgG synthesis rate (3/4, and positive oligoclonal bands (OBs, 3/4. Two patients presented with positive anti-nuclear antibody (ANA and one Sjögren's syndrome (SS in seropositive group.  Conclusions There were some differences in clinical features between AQP4 antibody positive MS and classical MS, suggesting distinctive pathogenesis may exist between these two entities, which need to be emphasized and treated accordingly from the diagnostic and therapeutic points of view. HE Yang and YANG Ting-ting contributed equally to this studyDOI: 10.3969/j.issn.1672-6731.2015.03.012

  8. Highly encephalitogenic aquaporin 4-specific T cells and NMO-IgG jointly orchestrate lesion location and tissue damage in the CNS.

    Science.gov (United States)

    Zeka, Bleranda; Hastermann, Maria; Hochmeister, Sonja; Kögl, Nikolaus; Kaufmann, Nathalie; Schanda, Kathrin; Mader, Simone; Misu, Tatsuro; Rommer, Paulus; Fujihara, Kazuo; Illes, Zsolt; Leutmezer, Fritz; Sato, Douglas Kazutoshi; Nakashima, Ichiro; Reindl, Markus; Lassmann, Hans; Bradl, Monika

    2015-12-01

    In neuromyelitis optica (NMO), astrocytes become targets for pathogenic aquaporin 4 (AQP4)-specific antibodies which gain access to the central nervous system (CNS) in the course of inflammatory processes. Since these antibodies belong to a T cell-dependent subgroup of immunoglobulins, and since NMO lesions contain activated CD4(+) T cells, the question arose whether AQP4-specific T cells might not only provide T cell help for antibody production, but also play an important role in the induction of NMO lesions. We show here that highly pathogenic, AQP4-peptide-specific T cells exist in Lewis rats, which recognize AQP4268-285 as their specific antigen and cause severe panencephalitis. These T cells are re-activated behind the blood-brain barrier and deeply infiltrate the CNS parenchyma of the optic nerves, the brain, and the spinal cord, while T cells with other AQP4-peptide specificities are essentially confined to the meninges. Although AQP4268-285-specific T cells are found throughout the entire neuraxis, they have NMO-typical "hotspots" for infiltration, i.e. periventricular and periaqueductal regions, hypothalamus, medulla, the dorsal horns of spinal cord, and the optic nerves. Most remarkably, together with NMO-IgG, they initiate large astrocyte-destructive lesions which are located predominantly in spinal cord gray matter. We conclude that the processing of AQP4 by antigen presenting cells in Lewis rats produces a highly encephalitogenic AQP4 epitope (AQP4268-285), that T cells specific for this epitope are found in the immune repertoire of normal Lewis rats and can be readily expanded, and that AQP4268-285-specific T cells produce NMO-like lesions in the presence of NMO-IgG.

  9. Super-resolution imaging of aquaporin-4 orthogonal arrays of particles in cell membranes

    National Research Council Canada - National Science Library

    Rossi, Andrea; Moritz, Tobias J; Ratelade, Julien; Verkman, A S

    2012-01-01

    Aquaporin-4 (AQP4) is a water channel expressed in astrocytes, skeletal muscle and epithelial cells that forms supramolecular aggregates in plasma membranes called orthogonal arrays of particles (OAPs...

  10. Frequency and prognostic impact of antibodies to aquaporin-4 in patients with optic neuritis

    DEFF Research Database (Denmark)

    Jarius, Sven; Frederiksen, Jette Lautrup Battistini; Waters, Patrick

    2010-01-01

    Antibodies to aquaporin-4 (AQP4-Ab) are found in 60-80% of patients with neuromyelitis optica (NMO), a severely disabling inflammatory CNS disorder of putative autoimmune aetiology, which predominantly affects the optic nerves and spinal cord....

  11. Status of diagnostic approaches to AQP4-IgG seronegative NMO and NMO/MS overlap syndromes

    DEFF Research Database (Denmark)

    Juryńczyk, Maciej; Weinshenker, Brian; Akman-Demir, Gulsen

    2016-01-01

    Distinguishing aquaporin-4 IgG(AQP4-IgG)-negative neuromyelitis optica spectrum disorders (NMOSD) from opticospinal predominant multiple sclerosis (MS) is a clinical challenge with important treatment implications. The objective of the study was to examine whether expert clinicians diagnose...... into four groups (NMO, MS, indeterminate, other) and management into three groups (MS drugs, immunosuppression, no treatment). The mean proportion of agreement for the diagnosis was low (p o = 0.51) and ranged from 0.25 to 0.73 for individual patients. The majority opinion was divided between NMOSD versus......: MS (nine cases), monophasic longitudinally extensive transverse myelitis (LETM) (1), acute disseminated encephalomyelitis (ADEM) (1) and recurrent isolated optic neuritis (RION) (1). Typical NMO features (e.g., LETM) influenced the diagnosis more than features more consistent with MS (e.g., short TM...

  12. Aquaporin-4-Immunoglobulin G-autoimmune syndrome in a Paraneoplastic Context

    DEFF Research Database (Denmark)

    Soelberg, Kerstin; Grauslund, Jakob; Lillevang, Søren Thue

    ON the patient had been treated for thyroid cancer, by thyroidectomy and radioactive iodine. Five years later he was diagnosed with disseminated colon cancer. Further three years later he was still positive for AQP4-IgG, had no relapse of NMOSD and died due to his cancer. Conclusions: This case suggests that AQP......Background: Serum autoantibody against the astrocytic water channel aquaporin 4 (AQP4-IgG) is a biomarker for neuromyelitis optica spectrum disorder (NMOSD). In some patients the presence of AQP4-IgG reflects a tumor-driven immune response. Methods: AQP4-IgG was measured with a recombinant...

  13. Aquaporin 4 molecular mimicry and implications for neuromyelitis optica.

    Science.gov (United States)

    Vaishnav, Radhika A; Liu, Ruolan; Chapman, Joab; Roberts, Andrew M; Ye, Hong; Rebolledo-Mendez, Jovan D; Tabira, Takeshi; Fitzpatrick, Alicia H; Achiron, Anat; Running, Mark P; Friedland, Robert P

    2013-07-15

    Neuromyelitis optica (NMO) is associated with antibodies to aquaporin 4 (AQP4). We hypothesized that antibodies to AQP4 can be triggered by exposure to environmental proteins. We compared human AQP4 to plant and bacterial proteins to investigate the occurrence of significantly similar structures and sequences. High similarity to a known epitope for NMO-IgG, AQP4(207-232), was observed for corn ZmTIP4-1. NMO and non-NMO sera were assessed for reactivity to AQP4(207-232) and the corn peptide. NMO patient serum showed reactivity to both peptides as well as to plant tissue. These findings warrant further investigation into the role of the environment in NMO etiology. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. [A case of anti-AQP4 antibody-positive recurrent myelitis overlapped with autoimmune disorders including incomplete CREST syndrome revealed multiple discontinuous cord lesions].

    Science.gov (United States)

    Takahashi, Makio; Nagata, Rie; Ozaki, Akihiko; Kaneko, Satoshi; Saiki, Hidemoto; Matsumoto, Sadayuki

    2009-01-01

    A 65-year-old woman presenting with multiple autoimmune disorders including incomplete CREST overlapping with aquaporin 4 (AQP4) antibody-positive recurrent myelitis was reported. She also clinically suffered from Sjogren syndrome and primary biliary cirrhosis (PBC). She had dysesthesia below C4 level, mild motor weakness and hyperreflexia without pathological reflexes on bilateral lower extremities. A T2-weighted MRI indicated multiple discontinuous spinal cord lesions at C1-5 and T7/8. A visual evoked potential study disclosed bilateral prolonged latency of P100. She clinically manifested not only incomplete CREST syndrome (facial teleangiectasia, sclerodactyly in bilateral fingers, and Raynaud's phenomenon), but also Sjögren (sicca syndrome) and PBC (jaundice). Immunoserological study showed that she was positive for anti-nuclear, anti-centromere, and anti-AQP4 (= NMO-IgG) antibodies. A combination therapy with corticosteroid and plasmapheresis was effective for all clinical symptoms. Therefore, this case stresses on the relevance of anti-AQP 4 antibody to the other overlapping autoimmune disorders, such as CREST syndrome, when recurrent myelitis is clinically diagnosed.

  15. Altered aquaporin expression in glaucoma eyes

    DEFF Research Database (Denmark)

    Tran, Thuy Linh; Bek, Toke; Cour, Morten la

    2014-01-01

    Aquaporins (AQP) are channels in the cell membrane that mainly facilitate a passive transport of water. In the eye, AQPs are expressed in the ciliary body and retina and may contribute to the pathogenesis of glaucoma and optic neuropathy. We investigated the expression of AQP1, AQP3, AQP4, AQP5...

  16. Aquaporins in Digestive System.

    Science.gov (United States)

    Zhu, Shuai; Ran, Jianhua; Yang, Baoxue; Mei, Zhechuan

    2017-01-01

    In this chapter, we mainly discuss the expression and function of aquaporins (AQPs ) expressed in digestive system . AQPs in gastrointestinal tract include four members of aquaporin subfamily: AQP1, AQP4, AQP5 and AQP8, and a member of aquaglyceroporin subfamily: AQP3. In the digestive glands, especially the liver, we discuss three members of aquaporin subfamily: AQP1, AQP5 and AQP8, a member of aquaglyceroporin subfamily: AQP9. AQP3 is involved in the diarrhea and inflammatory bowel disease; AQP5 is relevant to gastric carcinoma cell proliferation and migration; AQP9 plays considerable role in glycerol metabolism , urea transport and hepatocellular carcinoma. Further investigation is necessary for specific locations and functions of AQPs in digestive system.

  17. Aquaporins in Cardiovascular System.

    Science.gov (United States)

    Tie, Lu; Wang, Di; Shi, Yundi; Li, Xuejun

    2017-01-01

    Recent studies have shown that some aquaporins (AQPs ), including AQP1, AQP4, AQP7 and AQP9, are expressed in endothelial cells, vascular smooth muscle cells and heart of cardiovascular system. These AQPs are involved in the cardiovascular function and in pathological process of related diseases, such as cerebral ischemia , congestion heart failure , hypertension and angiogenesis. Therefore, it is important to understand the accurate association between AQPs and cardiovascular system, which may provide novel approaches to prevent and treat related diseases. Here we will discuss the expression and physiological function of AQPs in cardiovascular system and summarize recent researches on AQPs related cardiovascular diseases.

  18. Characterization of aquaporin 4 protein expression and localization in tissues of the dogfish (Squalus acanthias.

    Directory of Open Access Journals (Sweden)

    Christopher P Cutler

    2012-02-01

    Full Text Available The role of aquaporin water channels in Elasmobanchs such as the dogfish Squalus acanthias is completely unknown. This investigation determines the expression and cellular and sub-cellular localization of AQP4 protein in dogfish tissues. Two polyclonal antibodies were generated (AQP4/1 and AQP4/2. Western blots using the AQP4/1 antibody showed two bands (35.5kDa and 49.5kDa in most tissues similar to mammals. Liver and rectal gland showed further bands. However, unlike in mammals, AQP4 protein was expressed in all tissues including respiratory tract and liver. The AQP4/2 antibody appeared much less specific in blots. Both antibodies were used in immunohistochemistry and showed similar cellular localizations, although the AQP4/2 antibody had a more restricted sub-cellular distribution compared to AQP4/1 and therefore appeared to be more specific. In kidney a sub-set of tubules were stained which may represent intermediate tubule segments. AQP4/1 and AQP4/2 antibodies localized to the same tubules segments in serial sections although the intensity and sub-cellular distribution were different. AQP4/2 showed a basal or basolateral membrane distribution whereas AQP4/1 was often distributed throughout the cell including the nucleus. In rectal gland and cardiac stomach AQP4 was localized to secretary tubules but again AQP/1 and AQP/2 showed different sub-cellular distributions. In gill, both antibodies stained large cells in the primary filament and secondary lamellae. Again AQP4/1 antibody stained most or all the cell including the nucleus, whereas AQP4/2 had a plasma membrane and sometimes cytoplasmic distribution. Two types of large mitochondria-rich cells are known to exist in elasmobranches, that express either Na,K ATPase or V-type ATPase. Using Na,K-ATPase and V-type ATPase antibodies, AQP4 was colocalized with these proteins using the AQP4/1 antibody. Results show AQP4 is expressed in both (and all branchial Na,K ATPase and V-type ATPase

  19. Inhibition of HMGB1 reduces rat spinal cord astrocytic swelling and AQP4 expression after oxygen-glucose deprivation and reoxygenation via TLR4 and NF-κB signaling in an IL-6-dependent manner.

    Science.gov (United States)

    Sun, Lin; Li, Man; Ma, Xun; Feng, Haoyu; Song, Junlai; Lv, Cong; He, Yajun

    2017-11-25

    Spinal cord astrocyte swelling is an important component to spinal cord edema and is associated with poor functional recovery as well as therapeutic resistance after spinal cord injury (SCI). High mobility group box-1 (HMGB1) is a mediator of inflammatory responses in the central nervous system and plays a critical role after SCI. Given this, we sought to identify both the role and underlying mechanisms of HMGB1 in cellular swelling and aquaporin 4 (AQP4) expression in cultured rat spinal cord astrocytes after oxygen-glucose deprivation/reoxygenation (OGD/R). The post-natal day 1-2 Sprague-Dawley rat spinal cord astrocytes were cultured in vitro, and the OGD/R model was induced. We first investigated the effects of OGD/R on spinal cord astrocytic swelling and HMGB1 and AQP4 expression, as well as HMGB1 release. We then studied the effects of HMGB1 inhibition on cellular swelling, HMGB1 and AQP4 expression, and HMGB1 release. The roles of both toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway and interleukin-6 (IL-6) in reducing cellular swelling resulting from HMGB1 inhibition in spinal cord astrocytes after OGD/R were studied. Intergroup data were compared using one-way analysis of variance (ANOVA) followed by Dunnett's test. The OGD/R increased spinal cord astrocytic swelling and HMGB1 and AQP4 expression, as well as HMGB1 release. Inhibition of HMGB1 using either HMGB1 shRNA or ethyl pyruvate resulted in reduced cellular volume, mitochondrial and endoplasmic reticulum swelling, and lysosome number and decreased upregulation of both HMGB1 and AQP4 in spinal cord astrocytes, as well as HMGB1 release. The HMGB1 effects on spinal cord astrocytic swelling and AQP4 upregulation after OGD/R were mediated-at least in part-via activation of TLR4, myeloid differentiation primary response gene 88 (MyD88), and NF-κB. These activation effects can be repressed by TLR4 inhibition using CLI-095 or C34, or by NF-κB inhibition using BAY 11

  20. [Involvement of aquaporin-4 in synaptic plasticity, learning and memory].

    Science.gov (United States)

    Wu, Xin; Gao, Jian-Feng

    2017-06-25

    Aquaporin-4 (AQP-4) is the predominant water channel in the central nervous system (CNS) and primarily expressed in astrocytes. Astrocytes have been generally believed to play important roles in regulating synaptic plasticity and information processing. However, the role of AQP-4 in regulating synaptic plasticity, learning and memory, cognitive function is only beginning to be investigated. It is well known that synaptic plasticity is the prime candidate for mediating of learning and memory. Long term potentiation (LTP) and long term depression (LTD) are two forms of synaptic plasticity, and they share some but not all the properties and mechanisms. Hippocampus is a part of limbic system that is particularly important in regulation of learning and memory. This article is to review some research progresses of the function of AQP-4 in synaptic plasticity, learning and memory, and propose the possible role of AQP-4 as a new target in the treatment of cognitive dysfunction.

  1. Aquaporin-4 antibody titration in NMO patients treated with rituximab: A retrospective study.

    Science.gov (United States)

    Valentino, Paola; Marnetto, Fabiana; Granieri, Letizia; Capobianco, Marco; Bertolotto, Antonio

    2017-03-01

    We undertook an observational retrospective study to investigate the usefulness of aquaporin-4 (AQP4) antibodies (Ab) titration in the management of patients with neuromyelitis optica (NMO) treated with rituximab (RTX) by studying (1) the correlation between AQP4-Ab titer and disease activity, (2) the influence of RTX on antibody levels, and (3) the association between AQP4-Ab levels and responsiveness to RTX. A cell-based assay was used for AQP4-Ab titration in 322 serum samples from 7 patients with NMO treated with RTX (median follow-up 65 months), according to a treatment-to-target approach. Serum samples were collected every month following standardized procedures. (1) In group analysis, AQP4-Ab titers correlated with the disease activity, showing higher titers during and preceding relapses than during remission. However, in individual analysis, an increase in AQP4-Ab titers and CD19+ B cells did not always precede a relapse. (2) A reduction of AQP4-Ab titers in the short-term and long-term period was observed during RTX treatment. (3) Reduction of AQP4-Ab titers was observed in responder patients both 3 months after RTX infusion and in the long-term follow-up. In one nonresponder patient, AQP4-Ab levels never decreased during the treatment period. Titration of AQP4-Abs could be useful in the clinical management of patients with NMO treated with RTX: titration before each reinfusion and 3 months after each reinfusion may provide information about responsiveness to RTX. Although a relationship among AQP4-Ab levels, disease activity, and response to RTX was observed, the usefulness of AQP4-Ab titration to predict relapses is limited.

  2. Brain MRI abnormalities in neuromyelitis optica

    Energy Technology Data Exchange (ETDEWEB)

    Wang Fei, E-mail: feiwang1973@gmail.com [Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, 45 Chang-Chun St, Xuanwu District, Beijing 100053 (China); Liu Yaou, E-mail: asiaeurope80@gmail.com [Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, 45 Chang-Chun St, Xuanwu District, Beijing 100053 (China); Duan Yunyun, E-mail: duanyun2003@sohu.com [Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, 45 Chang-Chun St, Xuanwu District, Beijing 100053 (China); Li Kuncheng, E-mail: kunchengli@yahoo.com.cn [Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, 45 Chang-Chun St, Xuanwu District, Beijing 100053 (China); Education Ministry Key Laboratory for Neurodegenerative Disease, Xuanwu Hospital, Capital University of Medical Sciences, 45 Chang-Chun St, Xuanwu District, Beijing 100053 (China)

    2011-11-15

    Objective: The purpose of this study was to explore brain MRI findings in neuromyelitis optica (NMO) and to investigate specific brain lesions with respect to the localization of aquaporin-4 (AQP-4). Materials and methods: Forty admitted patients (36 women) who satisfied the 2006 criteria of Wingerchuk et al. for NMO were included in this study. All patients received a neurological examination and MRI scanning including brain and spinal cord. MRIs were classified as normal, nonspecific, multiple sclerosis-like, typical abnormalities. MS-like lesions were too few to satisfy the Barkhof et al. criteria for MS. Confluent lesions involving high AQP-4 regions were considered typical. Non-enhancing deep white matter lesions other than MS-like lesions or typical lesions were classified as nonspecific. Results: Brain MRI lesions were delineated in 12 patients (25%). Four patients (10%) had hypothalamus, brainstem or periventricle lesions. Six (15%) patients were nonspecific, and 2 (5%) patients had multiple sclerosis-like lesions. Conclusion: Brain MRIs are negative in most NMO, and brain lesions do not exclude the diagnosis of NMO. Hypothalamus, brainstem or periventricle lesions, corresponding to high sites of AQP-4 in the brain, are indicative of lesions of NMO.

  3. Enlarged extracellular space of aquaporin-4-deficient mice does not enhance diffusion of Alexa Fluor 488 or dextran polymers.

    Science.gov (United States)

    Xiao, F; Hrabetová, S

    2009-06-16

    Aquaporin-4 (AQP4) water channels expressed on glia have been implicated in maintaining the volume of extracellular space (ECS). A previous diffusion study employing small cation tetramethylammonium and a real-time iontophoretic (RTI) method demonstrated an increase of about 25% in the ECS volume fraction (alpha) in the neocortex of AQP4(-/-) mice compared to AQP4(+/+) mice but no change in the hindrance imposed to diffusing molecules (tortuosity lambda). In contrast, other diffusion studies employing large molecules (dextran polymers) and a fluorescence recovery after photobleaching (FRAP) method measured a decrease of about 10%-20% in lambda in the neocortex of AQP4(-/-) mice. These conflicting findings on lambda would imply that large molecules diffuse more readily in the enlarged ECS of AQP4(-/-) mice than in wild type but small molecules do not. To test this hypothesis, we used integrative optical imaging (IOI) to measure tortuosity with a small Alexa Fluor 488 (molecular weight [MW] 547, lambda(AF)) and two large dextran polymers (MW 3000, lambda(dex3) and MW 75,000, lambda(dex75)) in the in vitro neocortex of AQP4(+/+) and AQP4(-/-) mice. We found that lambda(AF)=1.59, lambda(dex3)=1.76 and lambda(dex75)=2.30 obtained in AQP4(-/-) mice were not significantly different from lambda(AF)=1.61, lambda(dex3)=1.76, and lambda(dex75)=2.33 in AQP4(+/+) mice. These IOI results demonstrate that lambda measured with small and large molecules each remain unchanged in the enlarged ECS of AQP4(-/-) mice compared to values in AQP4(+/+) mice. Further analysis suggests that the FRAP method yields diffusion parameters not directly comparable with those obtained by IOI or RTI methods. Our findings have implications for the role of glial AQP4 in maintaining the ECS structure.

  4. From finch to fish to man: role of aquaporins in body fluid and brain water regulation.

    Science.gov (United States)

    Schrier, R W; Chen, Y-C; Cadnapaphornchai, M A

    2004-01-01

    Charles Darwin, in his Origin of the Species, noted that different species of finches on the Galapagos Islands had adapted their beak size based on where they sought their food. Homer Smith, in his book From Fish to Philosopher, discussed the evolution of the nephron from a single conduit in salt water vertebrates, to nephrons with large glomerular capillaries and proximal and distal tubules in fresh water vertebrates, to smaller glomerular capillaries in amphibians, to nephrons with loops of Henle to allow for urinary concentration and dilution in mammals. The kidney with its million nephrons has emerged as the vital organ for regulating body fluid composition and volume. With the recent discovery of aquaporin water channels, our understanding of volume regulation has been greatly enhanced. This article reviews current knowledge regarding: 1) the unifying hypothesis of body fluid volume regulation; 2) brain aquaporins and their role in pathophysiologic states; and 3) function and regulation of renal aquaporins in the syndrome of inappropriate antidiuretic hormone secretion (SIADH).

  5. MOG-IgG in NMO and related disorders: a multicenter study of 50 patients. Part 4: Afferent visual system damage after optic neuritis in MOG-IgG-seropositive versus AQP4-IgG-seropositive patients.

    Science.gov (United States)

    Pache, Florence; Zimmermann, Hanna; Mikolajczak, Janine; Schumacher, Sophie; Lacheta, Anna; Oertel, Frederike C; Bellmann-Strobl, Judith; Jarius, Sven; Wildemann, Brigitte; Reindl, Markus; Waldman, Amy; Soelberg, Kerstin; Asgari, Nasrin; Ringelstein, Marius; Aktas, Orhan; Gross, Nikolai; Buttmann, Mathias; Ach, Thomas; Ruprecht, Klemens; Paul, Friedemann; Brandt, Alexander U

    2016-11-01

    Antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) have been reported in patients with aquaporin-4 antibody (AQP4-IgG)-negative neuromyelitis optica spectrum disorders (NMOSD). The objective of this study was to describe optic neuritis (ON)-induced neuro-axonal damage in the retina of MOG-IgG-positive patients in comparison with AQP4-IgG-positive NMOSD patients. Afferent visual system damage following ON was bilaterally assessed in 16 MOG-IgG-positive patients with a history of ON and compared with that in 16 AQP4-IgG-positive NMOSD patients. In addition, 16 healthy controls matched for age, sex, and disease duration were analyzed. Study data included ON history, retinal optical coherence tomography, visual acuity, and visual evoked potentials. Eight MOG-IgG-positive patients had a previous diagnosis of AQP4-IgG-negative NMOSD with ON and myelitis, and eight of (mainly recurrent) ON. Twenty-nine of the 32 eyes of the MOG-IgG-positive patients had been affected by at least one episode of ON. Peripapillary retinal nerve fiber layer thickness (pRNFL) and ganglion cell and inner plexiform layer volume (GCIP) were significantly reduced in ON eyes of MOG-IgG-positive patients (pRNFL = 59 ± 23 μm; GCIP = 1.50 ± 0.34 mm(3)) compared with healthy controls (pRNFL = 99 ± 6 μm, p IgG-positive patients (0.35 ± 0.88 logMAR). There were no significant differences in any structural or functional visual parameters between MOG-IgG-positive and AQP4-IgG-positive patients (pRNFL: 59 ± 21 μm; GCIP: 1.41 ± 0.27 mm(3); Visual acuity = 0.72 ± 1.09 logMAR). Importantly, MOG-IgG-positive patients had a significantly higher annual ON relapse rate than AQP4-IgG-positive patients (median 0.69 vs. 0.29 attacks/year, p = 0.004), meaning that on average a single ON episode caused less damage in MOG-IgG-positive than in AQP4-IgG-positive patients. pRNFL and GCIP loss correlated with the number of ON episodes in MOG

  6. Glymphatic fluid transport controls paravascular clearance of AAV vectors from the brain.

    Science.gov (United States)

    Murlidharan, Giridhar; Crowther, Andrew; Reardon, Rebecca A; Song, Juan; Asokan, Aravind

    2016-09-08

    Adeno-associated viruses (AAV) are currently being evaluated in clinical trials for gene therapy of CNS disorders. However, host factors that influence the spread, clearance, and transduction efficiency of AAV vectors in the brain are not well understood. Recent studies have demonstrated that fluid flow mediated by aquaporin-4 (AQP4) channels located on astroglial end feet is essential for exchange of solutes between interstitial and cerebrospinal fluid. This phenomenon, which is essential for interstitial clearance of solutes from the CNS, has been termed glial-associated lymphatic transport or glymphatic transport. In the current study, we demonstrate that glymphatic transport profoundly affects various aspects of AAV gene transfer in the CNS. Altered localization of AQP4 in aged mouse brains correlated with significantly increased retention of AAV vectors in the parenchyma and reduced systemic leakage following ventricular administration. We observed a similar increase in AAV retention and transgene expression upon i.c.v. administration in AQP4-/- mice. Consistent with this observation, fluorophore-labeled AAV vectors showed markedly reduced flux from the ventricles of AQP4-/- mice compared with WT mice. These results were further corroborated by reduced AAV clearance from the AQP4-null brain, as demonstrated by reduced transgene expression and vector genome accumulation in systemic organs. We postulate that deregulation of glymphatic transport in aged and diseased brains could markedly affect the parenchymal spread, clearance, and gene transfer efficiency of AAV vectors. Assessment of biomarkers that report the kinetics of CSF flux in prospective gene therapy patients might inform variable treatment outcomes and guide future clinical trial design.

  7. Noninvasive monitoring of brain edema after hypoxia in newborn piglets.

    Science.gov (United States)

    Malaeb, Shadi N; Izzetoglu, Meltem; McGowan, Jane; Delivoria-Papadopoulos, Maria

    2017-12-06

    BackgroundDevelopment of cerebral edema after brain injury carries a high risk for brain damage and death. The present study tests the ability of a noninvasive cerebral edema monitoring system that uses near-infrared spectroscopy (NIRS) with water as the chromophore of interest to detect brain edema following hypoxia.MethodsVentilated piglets were exposed to hypoxia for 1 h, and then returned to normal oxygen levels for 4 h. An NIRS sensor was placed on the animal's head at baseline, and changes in light attenuation were converted to changes in H2O. Cerebral water content and aquaporin-4 protein (AQP4) expression were measured.ResultsThe system detected changes in NIRS-derived water signal as early as 2 h after hypoxia, and provided fivefold signal amplification, representing a 10% increase in brain water content and a sixfold increase in AQP4, 4 h after hypoxia. Changes in water signal correlated well with changes in cerebral water content (R=0.74) and AQP4 expression (R=0.97) in the piglet brain.ConclusionThe data show that NIRS can detect cerebral edema early in the injury process, thus providing an opportunity to initiate therapy at an earlier and more effective time-point after an insult than is available with current technology.Pediatric Research advance online publication, 6 December 2017; doi:10.1038/pr.2017.264.

  8. Atomic force microscopy on plasma membranes from Xenopus laevis oocytes containing human aquaporin 4.

    Science.gov (United States)

    Orsini, Francesco; Santacroce, Massimo; Cremona, Andrea; Gosvami, Nitya N; Lascialfari, Alessandro; Hoogenboom, Bart W

    2014-11-01

    Atomic force microscopy (AFM) is a unique tool for imaging membrane proteins in near-native environment (embedded in a membrane and in buffer solution) at ~1 nm spatial resolution. It has been most successful on membrane proteins reconstituted in 2D crystals and on some specialized and densely packed native membranes. Here, we report on AFM imaging of purified plasma membranes from Xenopus laevis oocytes, a commonly used system for the heterologous expression of membrane proteins. Isoform M23 of human aquaporin 4 (AQP4-M23) was expressed in the X. laevis oocytes following their injection with AQP4-M23 cRNA. AQP4-M23 expression and incorporation in the plasma membrane were confirmed by the changes in oocyte volume in response to applied osmotic gradients. Oocyte plasma membranes were then purified by ultracentrifugation on a discontinuous sucrose gradient, and the presence of AQP4-M23 proteins in the purified membranes was established by Western blotting analysis. Compared with membranes without over-expressed AQP4-M23, the membranes from AQP4-M23 cRNA injected oocytes showed clusters of structures with lateral size of about 10 nm in the AFM topography images, with a tendency to a fourfold symmetry as may be expected for higher-order arrays of AQP4-M23. In addition, but only infrequently, AQP4-M23 tetramers could be resolved in 2D arrays on top of the plasma membrane, in good quantitative agreement with transmission electron microscopy analysis and the current model of AQP4. Our results show the potential and the difficulties of AFM studies on cloned membrane proteins in native eukaryotic membranes. Copyright © 2014 John Wiley & Sons, Ltd.

  9. Super-resolution imaging of aquaporin-4 orthogonal arrays of particles in cell membranes.

    Science.gov (United States)

    Rossi, Andrea; Moritz, Tobias J; Ratelade, Julien; Verkman, A S

    2012-09-15

    Aquaporin-4 (AQP4) is a water channel expressed in astrocytes, skeletal muscle and epithelial cells that forms supramolecular aggregates in plasma membranes called orthogonal arrays of particles (OAPs). AQP4 is expressed as a short isoform (M23) that forms large OAPs, and a long isoform (M1) that does not form OAPs by itself but can mingle with M23 to form relatively small OAPs. AQP4 OAPs were imaged with ~20 nm spatial precision by photoactivation localization microscopy (PALM) in cells expressing chimeras of M1- or M23-AQP4 with photoactivatable fluorescent proteins. Native AQP4 was imaged by direct stochastic optical reconstruction microscopy (dSTORM) using a primary anti-AQP4 antibody and fluorescent secondary antibodies. We found that OAP area increased from 1878±747 to 3647±958 nm(2) with decreasing M1:M23 ratio from 1:1 to 1:3, and became elongated. Two-color dSTORM indicated that M1 and M23 co-assemble in OAPs with a M1-enriched periphery surrounding a M23-enriched core. Native AQP4 in astrocytes formed OAPs with an area of 2142±829 nm(2), which increased to 5137±1119 nm(2) with 2-bromopalmitate. PALM of AQP4 OAPs in live cells showed slow diffusion (average ~10(-12) cm(2)/s) and reorganization. OAP area was not altered by anti-AQP4 IgG autoantibodies (NMO-IgG) that cause the neurological disease neuromyelitis optica. Super-resolution imaging allowed elucidation of novel nanoscale structural and dynamic features of OAPs.

  10. TRPV4 and AQP4 Channels Synergistically Regulate Cell Volume and Calcium Homeostasis in Retinal Müller Glia

    DEFF Research Database (Denmark)

    Jo, Andrew O; Ryskamp, Daniel A; Phuong, Tam T T

    2015-01-01

    (-/-) mice exhibited suppressed transcription of genes encoding Trpv4, Aqp4, and the Kir4.1 subunit of inwardly rectifying potassium channels. Swelling and [Ca(2+)]i elevations evoked in Müller cells by hypotonic stimulation were antagonized by the selective TRPV4 antagonist HC-067047 (2-methyl-1......-{[(2,4-dichlorophenyl)sulfonyl]amino}-3-hydroxypropanoyl)-1-piperazinyl]carbonyl}-3-methylbutyl)-1-benzothiophene-2-carboxamide]. Glial cells lacking TRPV4 but not AQP4 showed deficits in hypotonic swelling and regulatory volume decrease. Functional synergy between TRPV4 and AQP4 during cell swelling was confirmed...... and facilitates the time course and amplitude of hypotonicity-induced swelling and regulatory volume decrease. We confirm the crucial facets of the signaling mechanism in heterologously expressing oocytes. These results identify the molecular mechanism that contributes to dynamic regulation of glial volume...

  11. Evaluation of Clinical Interest of Anti-Aquaporin-4 Autoantibody Followup in Neuromyelitis Optica

    Directory of Open Access Journals (Sweden)

    Jean-Baptiste Chanson

    2013-01-01

    Full Text Available Neuromyelitis optica (NMO is an autoimmune disease in which a specific biomarker named NMO-IgG and directed against aquaporin-4 (AQP4 has been found. A correlation between disease activity and anti-AQP4 antibody (Ab serum concentration or complement-mediated cytotoxicity has been reported, but the usefulness of longitudinal evaluation of these parameters remains to be evaluated in actual clinical practice. Thirty serum samples from 10 NMO patients positive for NMO-IgG were collected from 2006 to 2011. Anti-AQP4 Ab serum concentration and complement-mediated cytotoxicity were measured by flow cytometry using two quantitative cell-based assays (CBA and compared with clinical parameters. We found a strong correlation between serum anti-AQP4 Ab concentration and complement-mediated cytotoxicity (P<0.0001. Nevertheless, neither relapse nor worsening of impairment level was closely associated with a significant increase in serum Ab concentration or cytotoxicity. These results suggest that complement-mediated serum cytotoxicity assessment does not provide extra insight compared to anti-AQP4 Ab serum concentration. Furthermore, none of these parameters appears closely related to disease activity and/or severity. Therefore, in clinical practice, serum anti-AQP4 reactivity seems not helpful as a predictive biomarker in the followup of NMO patients as a means of predicting the onset of a relapse and adapting the treatment accordingly.

  12. Correlation Between Aquaporin 4 Expression and Different DWI Parameters in Grade I Meningioma.

    Science.gov (United States)

    Schob, Stefan; Surov, Alexey; Wienke, Andreas; Meyer, Hans Jonas; Spielmann, Rolf Peter; Fiedler, Eckhard

    2017-02-01

    Diffusion-weighted imaging (DWI) measures water diffusion in biological tissues. Cellular water transport depends on aquaporins (AQPs). The expression of aquaporins might differ in several pathologic disorders. Therefore, the aim of this study was to evaluate the associations between AQP4 expression and different DWI parameters in meningioma. Twenty-three patients with meningioma grade I were included in this retrospective study. DWI was obtained with three b values (0; 500; 1000) using a 1.5-T device. ADCmean, ADCmin, ADCmax, and true diffusion coefficients (D) were obtained in every patient. Aquaporin 4 expression was quantified immunohistochemically in four immunoreactivity levels. The estimated DWI parameters (mean value ± standard deviation, 10-3 mm2 s-1) of the tumors were as follows: ADCmin 0.67 ± 0.16, ADCmean 0.94 ± 0.23, ADCmax 1.29 ± 0.50, and D 0.65 ± 0.23. The mean level of the AQP4 expression was 2.02 ± 0.75 points. A statistically significant correlation between AQP4 expression and ADCmax was identified (r = 0.508, p = 0.013). No significant correlations between AQP4 and other DWI parameters were found. A clear correlation between AQP4 expression and ADCmax values in grade I meningioma was identified. There were no significant correlations between AQP4 expression and other DWI parameters, such as ADCmin, ADCmean, and D.

  13. Treadmill exercise ameliorates ischemia-induced brain edema while suppressing Na⁺/H⁺ exchanger 1 expression.

    Science.gov (United States)

    Nishioka, Ryutaro; Sugimoto, Kana; Aono, Hitomi; Mise, Ayano; Choudhury, Mohammed E; Miyanishi, Kazuya; Islam, Afsana; Fujita, Takahiro; Takeda, Haruna; Takahashi, Hisaaki; Yano, Hajime; Tanaka, Junya

    2016-03-01

    Exercise may be one of the most effective and sound therapies for stroke; however, the mechanisms underlying the curative effects remain unclear. In this study, the effects of forced treadmill exercise with electric shock on ischemic brain edema were investigated. Wistar rats were subjected to transient (90 min) middle cerebral artery occlusion (tMCAO). Eighty nine rats with substantially large ischemic lesions were evaluated using magnetic resonance imaging (MRI) and were randomly assigned to exercise and non-exercise groups. The rats were forced to run at 4-6m/s for 10 min/day on days 2, 3 and 4. Brain edema was measured on day 5 by MRI, histochemical staining of brain sections and tissue water content determination (n=7, each experiment). Motor function in some rats was examined on day 30 (n=6). Exercise reduced brain edema (Peffects, but orally administered corticosterone mimicked the ameliorating effects of exercise. Exercise prevented the ischemia-induced expression of mRNA encoding aquaporin 4 (AQP4) and Na(+)/H(+) exchangers (NHEs) (n=5 or 7, Prat brains and also in mixed glial cultures. Corticosterone at ~10nM reduced NHE1 and AQP4 expression in mixed glial and pure microglial cultures. Dexamethasone and aldosterone at 10nM did not significantly alter NHE1 and AQP4 expression. Exposure to a NHE inhibitor caused shrinkage of microglial cells. These results suggest that the stressful short-period and slow-paced treadmill exercise suppressed NHE1 and AQP4 expression resulting in the amelioration of brain edema at least partly via the moderate increase in plasma corticosterone levels. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Cortical astrogliosis and increased perivascular aquaporin-4 in idiopathic intracranial hypertension.

    Science.gov (United States)

    Eide, Per Kristian; Eidsvaag, Vigdis Andersen; Nagelhus, Erlend A; Hansson, Hans-Arne

    2016-08-01

    The syndrome idiopathic intracranial hypertension (IIH) includes symptoms and signs of raised intracranial pressure (ICP) and impaired vision, usually in overweight persons. The pathogenesis is unknown. In the present prospective observational study, we characterized the histopathological changes in biopsies from the frontal brain cortical parenchyma obtained from 18 IIH patients. Reference specimens were sampled from 13 patients who underwent brain surgery for epilepsy, tumors or acute vascular diseases. Overnight ICP monitoring revealed abnormal intracranial pressure wave amplitudes in 14/18 IIH patients, who underwent shunt surgery and all responded favorably. A remarkable histopathological observation in IIH patients was patchy astrogliosis defined as clusters of hypertrophic astrocytes enclosing a nest of nerve cells. Distinct astrocyte domains (i.e. no overlap between astrocyte processes) were lacking in most IIH biopsy specimens, in contrast to their prevalence in reference specimens. Evidence of astrogliosis in IIH was accompanied with significantly increased aquaporin-4 (AQP4) immunoreactivity over perivascular astrocytic endfeet, compared to the reference specimens, measured with densitometry. Scattered CD68 immunoreactive cells (activated microglia and macrophages) were recognized, indicative of some inflammation. No apoptotic cells were demonstrable. We conclude that the patchy astrogliosis is a major finding in patients with IIH. We propose that the astrogliosis impairs intracranial pressure-volume reserve capacity, i.e. intracranial compliance, and contributes to the IIH by restricting the outflow of fluid from the cranium. The increased perivascular AQP4 in IIH may represent a compensatory mechanism to enhance brain fluid drainage. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Neuroinflammation and Neurodegeneration in Adult Rat Brain from Binge Ethanol Exposure: Abrogation by Docosahexaenoic Acid

    Science.gov (United States)

    Tajuddin, Nuzhath; Moon, Kwan-Hoon; Marshall, S. Alex; Nixon, Kimberly; Neafsey, Edward J.; Kim, Hee-Yong; Collins, Michael A.

    2014-01-01

    Evidence that brain edema and aquaporin-4 (AQP4) water channels have roles in experimental binge ethanol-induced neurodegeneration has stimulated interest in swelling/edema-linked neuroinflammatory pathways leading to oxidative stress. We report here that neurotoxic binge ethanol exposure produces comparable significant effects in vivo and in vitro on adult rat brain levels of AQP4 as well as neuroinflammation-linked enzymes: key phospholipase A2 (PLA2) family members and poly (ADP-ribose) polymerase-1 (PARP-1). In adult male rats, repetitive ethanol intoxication (3 gavages/d for 4 d, ∼9 g/kg/d, achieving blood ethanol levels ∼375 mg/dl; “Majchrowicz” model) significantly increased AQP4, Ca+2-dependent PLA2 GIVA (cPLA2), phospho-cPLA2 GIVA (p-cPLA2), secretory PLA2 GIIA (sPLA2) and PARP-1 in regions incurring extensive neurodegeneration in this model—hippocampus, entorhinal cortex, and olfactory bulb—but not in two regions typically lacking neurodamage, frontal cortex and cerebellum. Also, ethanol reduced hippocampal Ca+2-independent PLA2 GVIA (iPLA2) levels and increased brain “oxidative stress footprints” (4-hydroxynonenal-adducted proteins). For in vitro studies, organotypic cultures of rat hippocampal-entorhinocortical slices of adult age (∼60 d) were ethanol-binged (100 mM or ∼450 mg/dl) for 4 d, which augments AQP4 and causes neurodegeneration (Collins et al. 2013). Reproducing the in vivo results, cPLA2, p-cPLA2, sPLA2 and PARP-1 were significantly elevated while iPLA2 was decreased. Furthermore, supplementation with docosahexaenoic acid (DHA; 22:6n-3), known to quell AQP4 and neurodegeneration in ethanol-treated slices, blocked PARP-1 and PLA2 changes while counteracting endogenous DHA reduction and increases in oxidative stress footprints (3-nitrotyrosinated proteins). Notably, the PARP-1 inhibitor PJ-34 suppressed binge ethanol-dependent neurodegeneration, indicating PARP upstream involvement. The results with corresponding models

  16. Neuroinflammation and neurodegeneration in adult rat brain from binge ethanol exposure: abrogation by docosahexaenoic acid.

    Directory of Open Access Journals (Sweden)

    Nuzhath Tajuddin

    Full Text Available Evidence that brain edema and aquaporin-4 (AQP4 water channels have roles in experimental binge ethanol-induced neurodegeneration has stimulated interest in swelling/edema-linked neuroinflammatory pathways leading to oxidative stress. We report here that neurotoxic binge ethanol exposure produces comparable significant effects in vivo and in vitro on adult rat brain levels of AQP4 as well as neuroinflammation-linked enzymes: key phospholipase A2 (PLA2 family members and poly (ADP-ribose polymerase-1 (PARP-1. In adult male rats, repetitive ethanol intoxication (3 gavages/d for 4 d, ∼ 9 g/kg/d, achieving blood ethanol levels ∼ 375 mg/dl; "Majchrowicz" model significantly increased AQP4, Ca+2-dependent PLA2 GIVA (cPLA2, phospho-cPLA2 GIVA (p-cPLA2, secretory PLA2 GIIA (sPLA2 and PARP-1 in regions incurring extensive neurodegeneration in this model--hippocampus, entorhinal cortex, and olfactory bulb--but not in two regions typically lacking neurodamage, frontal cortex and cerebellum. Also, ethanol reduced hippocampal Ca+2-independent PLA2 GVIA (iPLA2 levels and increased brain "oxidative stress footprints" (4-hydroxynonenal-adducted proteins. For in vitro studies, organotypic cultures of rat hippocampal-entorhinocortical slices of adult age (∼ 60 d were ethanol-binged (100 mM or ∼ 450 mg/dl for 4 d, which augments AQP4 and causes neurodegeneration (Collins et al. 2013. Reproducing the in vivo results, cPLA2, p-cPLA2, sPLA2 and PARP-1 were significantly elevated while iPLA2 was decreased. Furthermore, supplementation with docosahexaenoic acid (DHA; 22:6n-3, known to quell AQP4 and neurodegeneration in ethanol-treated slices, blocked PARP-1 and PLA2 changes while counteracting endogenous DHA reduction and increases in oxidative stress footprints (3-nitrotyrosinated proteins. Notably, the PARP-1 inhibitor PJ-34 suppressed binge ethanol-dependent neurodegeneration, indicating PARP upstream involvement. The results with corresponding models

  17. Physical training improves non-spatial memory, locomotor skills and the blood brain barrier in diabetic rats.

    Science.gov (United States)

    de Senna, Priscylla Nunes; Xavier, Léder Leal; Bagatini, Pamela Brambilla; Saur, Lisiani; Galland, Fabiana; Zanotto, Caroline; Bernardi, Caren; Nardin, Patrícia; Gonçalves, Carlos Alberto; Achaval, Matilde

    2015-08-27

    Type 1 diabetes mellitus (T1DM) progressively affects cognitive domains, increases blood-brain barrier (BBB) permeability and promotes neurovascular impairment in specific brain areas. Physical exercise, on the other hand, has beneficial effects on brain functions, improving learning and memory. This study investigated the effects of treadmill training on cognitive and motor behavior, and on the expression of proteins related to BBB integrity, such as claudin-5 and aquaporin-4 (AQP4) in the hippocampus and striatum in diabetic rats. For this study, 60 Wistar rats were divided into four groups (n=15 per group): non-trained control (NTC), trained control (TC), non-trained diabetic (NTD), trained diabetic (TD). After diabetic induction of 30 days by streptozotocin injection, the exercise groups were submitted to 5 weeks of running training. After that, all groups were assessed in a novel object-recognition task (NOR) and the rotarod test. Additionally, claudin-5 and AQP4 levels were measured using biochemical assays. The results showed that exercise enhanced NOR task performance and rotarod ability in the TC and TD animals. Diabetes produced a decrease in claudin-5 expression in the hippocampus and striatum and reduced AQP4 in the hippocampus. Exercise preserved the claudin-5 content in the striatum of TD rats, but not in the hippocampus. The reduction of AQP4 levels produced by diabetes was not reversed by exercise. We conclude that exercise improves short-term memory retention, enhances motor performance in diabetic rats and affects important structural components of the striatal BBB. The results obtained could enhance the knowledge regarding the neurochemical benefits of exercise in diabetes. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Highly encephalitogenic aquaporin 4-specific T cells and NMO-IgG jointly orchestrate lesion location and tissue damage in the CNS

    DEFF Research Database (Denmark)

    Zeka, Bleranda; Hastermann, Maria; Hochmeister, Sonja

    2015-01-01

    In neuromyelitis optica (NMO), astrocytes become targets for pathogenic aquaporin 4 (AQP4)-specific antibodies which gain access to the central nervous system (CNS) in the course of inflammatory processes. Since these antibodies belong to a T cell-dependent subgroup of immunoglobulins, and since ...

  19. Effects of acupuncture at GV20 and ST36 on the expression of matrix metalloproteinase 2, aquaporin 4, and aquaporin 9 in rats subjected to cerebral ischemia/reperfusion injury.

    Directory of Open Access Journals (Sweden)

    Hong Xu

    Full Text Available BACKGROUND/PURPOSE: Ischemic stroke is characterized by high morbidity and mortality worldwide. Matrix metalloproteinase 2 (MMP2, aquaporin (AQP 4, and AQP9 are linked to permeabilization of the blood-brain barrier (BBB in cerebral ischemia/reperfusion injury (CIRI. BBB disruption, tissue inflammation, and MMP/AQP upregulation jointly provoke brain edema/swelling after CIRI, while acupuncture and electroacupuncture can alleviate CIRI symptoms. This study evaluated the hypothesis that acupuncture and electroacupuncture can similarly exert neuroprotective actions in a rat model of middle cerebral artery occlusion (MCAO by modulating MMP2/AQP4/APQ9 expression and inflammatory cell infiltration. METHODS: Eighty 8-week-old Sprague-Dawley rats were randomly divided into sham group S, MCAO model group M, acupuncture group A, electroacupuncture group EA, and edaravone group ED. The MCAO model was established by placement of a suture to block the middle carotid artery, and reperfusion was triggered by suture removal in all groups except group S. Acupuncture and electroacupuncture were administered at acupoints GV20 (governing vessel-20 and ST36 (stomach-36. Rats in groups A, EA, and ED received acupuncture, electroacupuncture, or edaravone, respectively, immediately after MCAO. Neurological function (assessed using the Modified Neurological Severity Score, infarct volume, MMP2/AQP4/AQP9 mRNA and protein expression, and inflammatory cell infiltration were all evaluated at 24 h post-reperfusion. RESULTS: Acupuncture and electroacupuncture significantly decreased infarct size and improved neurological function. Furthermore, target mRNA and protein levels and inflammatory cell infiltration were significantly reduced in groups A, EA, and ED vs. group M. However, MMP2/AQP levels and inflammatory cell infiltration were generally higher in groups A and EA than in group ED except MMP2 mRNA levels. CONCLUSIONS: Acupuncture and electroacupuncture at GV20 and ST36

  20. Acid suppression by proton pump inhibitors enhances aquaporin-4 and KCNQ1 expression in gastric fundic parietal cells in mouse.

    Science.gov (United States)

    Matsuzaki, Juntaro; Suzuki, Hidekazu; Minegishi, Yuriko; Sugai, Etsuko; Tsugawa, Hitoshi; Yasui, Masato; Hibi, Toshifumi

    2010-12-01

    The widespread use of proton pump inhibitors (PPIs) is known to cause sporadic gastric fundic gland polyps (FGPs). Altered expression and localization of the water or ion transport proteins might contribute to the excess fluid secretion into the cystic lumen for the development of FGPs. We investigated the alteration of the murine gastric fundic mucosa after PPI treatment, and examined the expression of water channel aquaporin-4 (AQP4) and potassium channel KCNQ1, which are expressed only in the parietal cells in the gastric mucosa. Male 5-week-old C57BL/6J mice were administered lansoprazole (LPZ) by subcutaneous injection for 8 weeks. The expression of AQP4 and KCNQ1 were investigated by Western blotting, quantitative RT-PCR, and immunohistochemistry. The expression of mucin-6 (Muc6), pepsinogen, and sonic hedgehog (Shh) were also investigated as mucosal cell lineage markers. Gastric mucosal hyperplasia with multiple cystic dilatations, exhibiting similar histological findings to the FGPs, was observed in the LPZ-treated mice. An increase in the number of AQP4-positive parietal cells and KCNQ1-positive parietal cells was observed. The extension of the distribution of AQP4-positive cells toward the surface of the fundic glands was also observed. The expression levels of AQP4 mRNA and protein were significantly enhanced. The expression of KCNQ1 mRNA was correlated with that of AQP4 mRNA in the LPZ-treated mice. Mucous neck-to-zymogenic cell lineage differentiation was delayed in association with decreased expression of Shh in the LPZ-treated mice. PPI administration increased the number of parietal cells with enhanced expression of AQP4 and KCNQ1.

  1. Renal aquaporins and water balance disorders

    DEFF Research Database (Denmark)

    Kortenoeven, Marleen; Fenton, Robert A.

    2013-01-01

    BACKGROUND: Aquaporins (AQPs) are a family of proteins that can act as water channels. Regulation of AQPs is critical to osmoregulation and the maintenance of body water homeostasis. Eight AQPs are expressed in the kidney of which five have been shown to play a role in body water balance; AQP1, AQP......2, AQP3, AQP4 and AQP7. AQP2 in particular is regulated by vasopressin. SCOPE OF REVIEW: This review summarizes our current knowledge of the underlying mechanisms of various water balance disorders and their treatment strategies. MAJOR CONCLUSIONS: Dysfunctions of AQPs are involved in disorders...... associated with disturbed water homeostasis. Hyponatremia with increased AQP levels can be caused by diseases with low effective circulating blood volume, such as congestive heart failure, or osmoregulation disorders such as the syndrome of inappropriate secretion of antidiuretic hormone. Treatment consists...

  2. Methylprednisolone Administration Following Spinal Cord Injury Reduces Aquaporin 4 Expression and Exacerbates Edema

    Directory of Open Access Journals (Sweden)

    Eibar Ernesto Cabrera-Aldana

    2017-01-01

    Full Text Available Spinal cord injury (SCI is an incapacitating condition that affects motor, sensory, and autonomic functions. Since 1990, the only treatment administered in the acute phase of SCI has been methylprednisolone (MP, a synthetic corticosteroid that has anti-inflammatory effects; however, its efficacy remains controversial. Although MP has been thought to help in the resolution of edema, there are no scientific grounds to support this assertion. Aquaporin 4 (AQP4, the most abundant component of water channels in the CNS, participates in the formation and elimination of edema, but it is not clear whether the modulation of AQP4 expression by MP plays any role in the physiopathology of SCI. We studied the functional expression of AQP4 modulated by MP following SCI in an experimental model in rats along with the associated changes in the permeability of the blood-spinal cord barrier. We analyzed these effects in male and female rats and found that SCI increased AQP4 expression in the spinal cord white matter and that MP diminished such increase to baseline levels. Moreover, MP increased the extravasation of plasma components after SCI and enhanced tissue swelling and edema. Our results lend scientific support to the increasing motion to avoid MP treatment after SCI.

  3. Methylprednisolone Administration Following Spinal Cord Injury Reduces Aquaporin 4 Expression and Exacerbates Edema

    Science.gov (United States)

    Martínez-Cruz, Angelina; Reyes-Sánchez, Alejandro; Guizar-Sahagún, Gabriel

    2017-01-01

    Spinal cord injury (SCI) is an incapacitating condition that affects motor, sensory, and autonomic functions. Since 1990, the only treatment administered in the acute phase of SCI has been methylprednisolone (MP), a synthetic corticosteroid that has anti-inflammatory effects; however, its efficacy remains controversial. Although MP has been thought to help in the resolution of edema, there are no scientific grounds to support this assertion. Aquaporin 4 (AQP4), the most abundant component of water channels in the CNS, participates in the formation and elimination of edema, but it is not clear whether the modulation of AQP4 expression by MP plays any role in the physiopathology of SCI. We studied the functional expression of AQP4 modulated by MP following SCI in an experimental model in rats along with the associated changes in the permeability of the blood-spinal cord barrier. We analyzed these effects in male and female rats and found that SCI increased AQP4 expression in the spinal cord white matter and that MP diminished such increase to baseline levels. Moreover, MP increased the extravasation of plasma components after SCI and enhanced tissue swelling and edema. Our results lend scientific support to the increasing motion to avoid MP treatment after SCI. PMID:28572712

  4. Human Aquaporin-4 and Molecular Modeling: Historical Perspective and View to the Future

    Directory of Open Access Journals (Sweden)

    Giuseppe Felice Mangiatordi

    2016-07-01

    Full Text Available Among the different aquaporins (AQPs, human aquaporin-4 (hAQP4 has attracted the greatest interest in recent years as a new promising therapeutic target. Such a membrane protein is, in fact, involved in a multiple sclerosis-like immunopathology called Neuromyelitis Optica (NMO and in several disorders resulting from imbalanced water homeostasis such as deafness and cerebral edema. The gap of knowledge in its functioning and dynamics at the atomistic level of detail has hindered the development of rational strategies for designing hAQP4 modulators. The application, lately, of molecular modeling has proved able to fill this gap providing a breeding ground to rationally address compounds targeting hAQP4. In this review, we give an overview of the important advances obtained in this field through the application of Molecular Dynamics (MD and other complementary modeling techniques. The case studies presented herein are discussed with the aim of providing important clues for computational chemists and biophysicists interested in this field and looking for new challenges.

  5. Elevation of AQP4 and selective cytokines in experimental autoimmune encephalitis mice provides some potential biomarkers in optic neuritis and demyelinating diseases.

    Science.gov (United States)

    Sun, Li; Weng, Huan; Li, Zhenxin

    2015-01-01

    Idiopathic optic neuritis (ION) is an inflammation of the optic nerve that may result in a complete or partial loss of vision. ION is usually due to the immune attack of the myelin sheath covering the optic nerve. ION acts frequently as the first symptoms of multiple sclerosis (MS) and neuromyelitis optica (NMO), or other inflammatory demyelinating disorders. The pathogenic progression of ION remains unclear. Experimental autoimmune encephalitis (EAE) is a commonly used model of idiopathic inflammatory demyelinating disorders (IIDDs); the optic nerve is affected in EAE as well. The specific mediators of demyelination in optic neuritis are unknown. Recent studies have indicated what T-cell activation in peripheral blood is associated with optic neuritis pathogenesis. The object of the present study was to determine whether certain cytokines (IL-6, IL-17A, and IL-23) and AQP4 contribute to the demyelinating process using EAE model. We have found that IL-6R, AQP4 and IL-23R are significantly increased in mRNA and protein levels in optic nerves in EAE mice compared to control mice; serum AQP4, IL-6, IL-17A, IL-23 are increased whereas transforming growth factor beta (TGF-β) is decreased in EAE mice. These results suggest that AQP4 and selective cytokines in serum are associated with ION pathogenesis in the animal model, and these results shine light for future clinical diagnosis as potential biomarkers in ION patients.

  6. Clinical features and sera anti-aquaporin 4 antibody positivity in patients with demyelinating disorders of the central nervous system from Tianjin, China.

    Science.gov (United States)

    Yang, Chun-Sheng; Zhang, Da-Qi; Wang, Jing-Hua; Jin, Wei-Na; Li, Min-Shu; Liu, Jie; Zhang, Cun-Jin; Li, Ting; Shi, Fu-Dong; Yang, Li

    2014-01-01

    To investigate the clinical characteristics and sera anti-aquaporin 4 (AQP4) antibody positivity in patients with inflammatory demyelinating disorders (IDDs) of the central nervous system (CNS) in Tianjin, China. We retrospectively evaluated 234 patients with IDDs including neuromyelitis optica (NMO), recurrent optic neuritis (rON), longitudinally extensive transverse myelitis (LETM), clinically isolated syndrome (CIS), and multiple sclerosis (MS) groups. Sera from 217 patients were determined for AQP4-Ab. The clinical characteristics and sera anti-AQP4 positivity were compared. The IDDS comprised 63 MS, 51 NMO, 56 LETM, 10 rON, and 54 CIS. Compared with MS, NMO had a higher frequency of occurrence in women, intractable hiccup and nausea (IHN), medullospinal lesion, longitudinally extensive spinal cord lesions (LESCL) and bilateral ON, disease onset at a later age, and worsening residual disability. AQP4-Ab-positive rates were 84.1% and 69% in NMO and NMO spectrum disorders (NMOSD), respectively, whereas it was undetectable in all of the MS sera samples. We comprehensively contrast the distinct clinical features of MS, NMO, and NMOSD in our center. A sensitive AQP4-Ab assay is necessary for the early diagnosis of NMOSD in our patients. Neither medullospinal lesion nor IHN is unique in NMO. © 2013 John Wiley & Sons Ltd.

  7. Aquaporin-4 Immuneglobulin G testing in 36 consecutive Jamaican patients with inflammatory central nervous system demyelinating disease

    Directory of Open Access Journals (Sweden)

    Sherri Sandy

    2014-08-01

    Full Text Available Epidemiological studies of neuromyelitis optica (NMO in Jamaica are lacking. Here we reviewed the clinical records of 700 patients undergoing neurological evaluation at the Kingston Public Hospital, the largest tertiary institution in Jamaica over a 4 month period. We investigated the diagnostic utility of Aquaporin-4 ImmuneglobulinG (AQP4-IgG testing in 36 consecutive patients with a diagnosis of an inflammatory demyelinating disorder (IDD of the central nervous system (CNS. Patients were classified into 3 categories: i NMO, n=10; ii multiple sclerosis (MS, n=14 and iii unclassified IDD (n=12. All sera were tested for AQP-IgG status by cell binding assay (Euroimmun. No MS cases were positive. Ninety per cent of NMO cases were positive. Four of 12 patients with unclassified IDD tested positive for AQP4-IgG. AQP4-IgG seropositivity was associated with a lower socioeconomic status, higher EDSS (P=0.04 and lower pulmonary function than the seronegative cases (P=0.007. Aquaporin-4 autoimmunity may account for a significant proportion of Jamaican CNS IDDs.

  8. In vivo measurement of brain extracellular space diffusion by cortical surface photobleaching.

    Science.gov (United States)

    Binder, Devin K; Papadopoulos, Marios C; Haggie, Peter M; Verkman, A S

    2004-09-15

    Molecular diffusion in the brain extracellular space (ECS) is an important determinant of neural function. We developed a brain surface photobleaching method to measure the diffusion of fluorescently labeled macromolecules in the ECS of the cerebral cortex. The ECS in mouse brain was labeled by exposure of the intact dura to fluorescein-dextrans (M(r) 4, 70, and 500 kDa). Fluorescein-dextran diffusion, detected by fluorescence recovery after laser-induced cortical photobleaching using confocal optics, was slowed approximately threefold in the brain ECS relative to solution. Cytotoxic brain edema (produced by water intoxication) or seizure activity (produced by convulsants) slowed diffusion by >10-fold and created dead-space microdomains in which free diffusion was prevented. The hindrance to diffusion was greater for the larger fluorescein-dextrans. Interestingly, slowed ECS diffusion preceded electroencephalographic seizure activity. In contrast to the slowed diffusion produced by brain edema and seizure activity, diffusion in the ECS was faster in mice lacking aquaporin-4 (AQP4), an astroglial water channel that facilitates fluid movement between cells and the ECS. Our results establish a minimally invasive method to quantify diffusion in the brain ECS in vivo, revealing stimulus-induced changes in molecular diffusion in the ECS with unprecedented spatial and temporal resolution. The in vivo mouse data provide evidence for: (1) dead-space ECS microdomains after brain swelling; (2) slowed molecular diffusion in the ECS as an early predictor of impending seizure activity; and (3) a novel role for AQP4 as a regulator of brain ECS.

  9. Evidence of Positive Selection of Aquaporins Genes from Pontoporia blainvillei during the Evolutionary Process of Cetaceans.

    Science.gov (United States)

    São Pedro, Simone Lima; Alves, João Marcelo Pereira; Barreto, André Silva; Lima, André Oliveira de Souza

    2015-01-01

    Marine mammals are well adapted to their hyperosmotic environment. Several morphological and physiological adaptations for water conservation and salt excretion are known to be present in cetaceans, being responsible for regulating salt balance. However, most previous studies have focused on the unique renal physiology of marine mammals, but the molecular bases of these mechanisms remain poorly explored. Many genes have been identified to be involved in osmotic regulation, including the aquaporins. Considering that aquaporin genes were potentially subject to strong selective pressure, the aim of this study was to analyze the molecular evolution of seven aquaporin genes (AQP1, AQP2, AQP3, AQP4, AQP6, AQP7, and AQP9) comparing the lineages of cetaceans and terrestrial mammals. Our results demonstrated strong positive selection in cetacean-specific lineages acting only in the gene for AQP2 (amino acids 23, 83, 107,179, 180, 181, 182), whereas no selection was observed in terrestrial mammalian lineages. We also analyzed the changes in the 3D structure of the aquaporin 2 protein. Signs of strong positive selection in AQP2 sites 179, 180, 181, and 182 were unexpectedly identified only in the baiji lineage, which was the only river dolphin examined in this study. Positive selection in aquaporins AQP1 (45), AQP4 (74), AQP7 (342, 343, 356) was detected in cetaceans and artiodactyls, suggesting that these events are not related to maintaining water and electrolyte homeostasis in seawater. Our results suggest that the AQP2 gene might reflect different selective pressures in maintaining water balance in cetaceans, contributing to the passage from the terrestrial environment to the aquatic. Further studies are necessary, especially those including other freshwater dolphins, who exhibit osmoregulatory mechanisms different from those of marine cetaceans for the same essential task of maintaining serum electrolyte balance.

  10. Evidence of Positive Selection of Aquaporins Genes from Pontoporia blainvillei during the Evolutionary Process of Cetaceans.

    Directory of Open Access Journals (Sweden)

    Simone Lima São Pedro

    Full Text Available Marine mammals are well adapted to their hyperosmotic environment. Several morphological and physiological adaptations for water conservation and salt excretion are known to be present in cetaceans, being responsible for regulating salt balance. However, most previous studies have focused on the unique renal physiology of marine mammals, but the molecular bases of these mechanisms remain poorly explored. Many genes have been identified to be involved in osmotic regulation, including the aquaporins. Considering that aquaporin genes were potentially subject to strong selective pressure, the aim of this study was to analyze the molecular evolution of seven aquaporin genes (AQP1, AQP2, AQP3, AQP4, AQP6, AQP7, and AQP9 comparing the lineages of cetaceans and terrestrial mammals.Our results demonstrated strong positive selection in cetacean-specific lineages acting only in the gene for AQP2 (amino acids 23, 83, 107,179, 180, 181, 182, whereas no selection was observed in terrestrial mammalian lineages. We also analyzed the changes in the 3D structure of the aquaporin 2 protein. Signs of strong positive selection in AQP2 sites 179, 180, 181, and 182 were unexpectedly identified only in the baiji lineage, which was the only river dolphin examined in this study. Positive selection in aquaporins AQP1 (45, AQP4 (74, AQP7 (342, 343, 356 was detected in cetaceans and artiodactyls, suggesting that these events are not related to maintaining water and electrolyte homeostasis in seawater.Our results suggest that the AQP2 gene might reflect different selective pressures in maintaining water balance in cetaceans, contributing to the passage from the terrestrial environment to the aquatic. Further studies are necessary, especially those including other freshwater dolphins, who exhibit osmoregulatory mechanisms different from those of marine cetaceans for the same essential task of maintaining serum electrolyte balance.

  11. Effects of beta-hydroxybutyrate on brain vascular permeability in rats with traumatic brain injury.

    Science.gov (United States)

    Orhan, Nurcan; Ugur Yilmaz, Canan; Ekizoglu, Oguzhan; Ahishali, Bulent; Kucuk, Mutlu; Arican, Nadir; Elmas, Imdat; Gürses, Candan; Kaya, Mehmet

    2016-01-15

    This study investigates the effect of beta-hydroxybutyrate (BHB) on blood-brain barrier (BBB) integrity during traumatic brain injury (TBI) in rats. Evans blue (EB) and horseradish peroxidase (HRP) were used as determinants of BBB permeability. Glutathione (GSH) and malondialdehyde (MDA) levels were estimated in the right (injury side) cerebral cortex of animals. The gene expression levels for occludin, glucose transporter (Glut)-1, aquaporin4 (AQP4) and nuclear factor-kappaB (NF-κB) were performed, and Glut-1 and NF-κB activities were analyzed. BHB treatment decreased GSH and MDA levels in intact animals and in those exposed to TBI (P<0.05). Glut-1 protein levels decreased in sham, BHB and TBI plus BHB groups (P<0.05). NF-κB protein levels increased in animals treated with BHB and/or exposed to TBI (P<0.05). The expression levels of occludin and AQP4 did not significantly change among experimental groups. Glut-1 expression levels increased in BHB treated and untreated animals exposed to TBI (P<0.05). While NF-κB expression levels increased in animals in TBI (P<0.01), a decrease was noticed in these animals upon BHB treatment (P<0.01). In animals exposed to TBI, EB extravasation was observed in the ipsilateral cortex regardless of BHB treatment. Ultrastructurally, BHB attenuated but did not prevent the presence of HRP in brain capillary endothelial cells of animals with TBI; moreover, the drug also led to the observation of the tracer when used in intact rats (P<0.01). Altogether, these results showed that BHB not only failed to provide overall protective effects on BBB in TBI but also led to BBB disruption in healthy animals. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Perinatal changes in expression of aquaporin-4 and other water and ion transporters in rat lung.

    Science.gov (United States)

    Yasui, M; Serlachius, E; Löfgren, M; Belusa, R; Nielsen, S; Aperia, A

    1997-11-15

    1. At birth, rapid removal of lung liquid from potential airspaces is required to establish pulmonary gas exchange. To investigate the role for water channels, aquaporins (AQP) and ion transporters in this process, the mRNA expression of AQP, Na+,K(+)-ATPase and the amiloride-sensitive Na+ channel (ENaC) were studied in the fetal and postnatal rat lung. 2. The mRNA expression of all transporters studied increased postnatally. 3. The following water channels were expressed in the lung, AQP1, 4 and 5. The most specific perinatal induction pattern was observed for AQP4. A sharp and transient increase of AQP4 mRNA occurred just after birth coinciding with the time course for clearance of lung liquid. This transient induction of AQP4 mRNA at birth was lung-tissue specific. Around birth there was a moderate increase in AQP1 mRNA, which was not transient. AQP5 increased continuously until adulthood. 4. Fetal lung AQP4 mRNA was induced by both beta-adrenergic agonists and glucocorticoid hormone, which are factors that have been suggested to accelerate the clearance of lung liquid. 5. Immunocytochemistry revealed that AQP4 was located in the basolateral membranes of bronchial epithelia in newborn rats, consistent with the view that this is the major site for perinatal lung liquid absorption. 6. The Na+,K(+)-ATPase alpha 1 subunit and ENaC alpha-subunit mRNA also increased around birth, suggesting that they co-operatively facilitate lung liquid clearance at birth. 7. These data indicate that removal of lung liquid at birth is associated with pronounced and well-synchronized changes in the expression of AQP and the ion transporters studied. The transient perinatal induction of AQP4, which could be prenatally induced by beta-adrenergic agonists, and the localization of this water channel strongly suggest that it plays a critical role for removal of lung liquid at the time of birth.

  13. [Effect of Weichang'an pill on intestinal digestion enzymes and the AQP4 concentration in proximal colon in IBS-D rats].

    Science.gov (United States)

    Hu, Rui; Zhang, Tongmao; Tang, Fang

    2010-11-01

    To investigate the influence of Weichang'an pill on the treatment of diarrhea-predominant irritable bowel syndrome (IBS-D) in model rats. Animal model of compound diarrhea was induced by a lactose enriched diet in the Wistar rat, combining with restraint stress. Twenty four female Wistar rats were randomly divided into normal group, model group and 60 mg x kg(-1) x d(-1) Weichang'an pill group. The rate of weight increase, the incubation period of diarrhea and the diarrhea index were observed. Then 45 female Wistar rats randomly divided into five groups: control group, model group and Weichang'an pill groups of high, medium and low doses (80, 60, 40 mg x kg(-1) x d(-1)). The indexes of thymus and spleen were calculated. The activities of LDH, MDH and disaccharidase in intestinal organization were inspected. Serum D-xylose content and the AQP4 concentration in proximal colon were detected. After taking Weichang'an pill for 4 days, the rate of weight increase in Weichang'an pill group was higher than the model group's. While the rate of diarrhea was lower significantly. So the best cycle of taking medicine was 4 days. The indexes of thymus and spleen of model group were decreased than that of control group. And the activities of LDH, MDH and disaccharidase in intestinal organization were also decreased. But the AQP4 concentration in proximal colon was increased. Compared with the model group, the indexes of thymus and spleen increased remarkably in the group of medium doses. Meanwhile, the activities of LDH, MDH and disaccharidase increased. But the AQP4 concentration didn't change. Weichang'an pill has the effect of antidiarrhea. It can adjust the sugar's catabolism through increasing the activity of intestinal digestive ferment.

  14. D184E mutation in aquaporin-4 gene impairs water permeability and links to deafness.

    Science.gov (United States)

    Nicchia, G P; Ficarella, R; Rossi, A; Giangreco, I; Nicolotti, O; Carotti, A; Pisani, F; Estivill, X; Gasparini, P; Svelto, M; Frigeri, A

    2011-12-01

    Aquaporins (AQPs) play a physiological role in several organs and tissues, and their alteration is associated with disorders of water regulation. The identification of molecular interactions, which are crucial in determining the rate of water flux through the channel, is of pivotal role for the discovery of molecules able to target those interactions and therefore to be used for pathologies ascribable to an altered AQP-dependent water balance. In the present study, a mutational screening of human aquaporin-4 (AQP4) gene was performed on subjects with variable degrees of hearing loss. One heterozygous missense mutation was identified in a Spanish sporadic case, leading to an Asp/Glu amino acid substitution at position 184 (D184E). A BLAST analysis revealed that the amino acid D184 is conserved across species, consistently with a crucial role in the structure/function of AQP4 water channels. The mutation induces a significant reduction in water permeability as measured by the Xenopus laevis oocytes swelling assay and by the use of mammalian cells by total internal reflection microscopy. By Western blot, immunofluorescence and 2D Blue Native/SDS-PAGE we show that the reduction in water permeability is not ascribable to a reduced expression of AQP4 mutant protein or to its incorrect plasma membrane targeting and aggregation into orthogonal arrays of particles. Molecular dynamics simulation provided a molecular explanation of the mechanism whereby the mutation induces a loss of function of the channel. Substituting glutamate for aspartate affects the mobility of the D loop, which acquires a higher propensity to equilibrate in a "closed conformation", thus affecting the rate of water flux. We speculate that this mutation, combined with other genetic defects or concurrently with certain environmental stimuli, could confer a higher susceptibility to deafness. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

  15. Differential Expression of Aquaporins in Experimental Models of Acute Lung Injury.

    Science.gov (United States)

    Vassiliou, Alice G; Manitsopoulos, Nikolaos; Kardara, Matina; Maniatis, Nikolaos A; Orfanos, Stylianos E; Kotanidou, Anastasia

    2017-01-01

    The mammalian lung expresses at least three aquaporin (AQP) water channels whose precise role in lung injury or inflammation is still controversial. Three murine models of lung inflammation and corresponding controls were used to evaluate the expression of Aqp1, Aqp4, Aqp5 and Aqp9: lipopolysaccharide (LPS)-induced lung injury; HCl-induced lung injury; and ventilation-induced lung injury (VILI). All models yielded increased lung vascular permeability, and inflammatory cell infiltration in the broncho-alveolar lavage fluid; VILI additionally produced altered lung mechanics. Lung expression of Aqp4 decreased in the models that targeted primarily the alveolar epithelium, i.e. acid aspiration and mechanical ventilation, while Aqp5 expression decreased in the model that appeared to target both the capillary endothelium and alveolar epithelium, i.e. LPS. Participation of aquaporins in the acute inflammatory process depends on localization and the type of lung injury. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  16. Water transport between CNS compartments: contributions of aquaporins and cotransporters

    DEFF Research Database (Denmark)

    MacAulay, N; Zeuthen, T

    2010-01-01

    pores in analogy to the aquaporins. The putative role of cotransport proteins and uniports for the water flux into the glial cells, through the choroid plexus and across the endothelial cells of the blood-brain-barrier will be discussed and compared to the contribution of the aquaporins....

  17. Theoretical Studies of AQP4 in Water and Gas Phases, Nano Simulation of the Monte Carlo Method by Molecular Mechanics Force Fields

    OpenAIRE

    Ebrahim Shahmansoorian; Maryam Hashemy; Saharnaz Ahmadi; Zohreh Jamali; Nastaran Asghari Moghaddam; Reza Rasoolzadeh

    2014-01-01

    Aquaporins are membrane water channels that play critical roles in controlling the water contents of cells. These channels are widely distributed in all kingdoms of life, including bacteria, plants, and mammals. More than ten different aquaporins have been found in human body, and several diseases, such as congenital cataracts and nephrogenic diabetes insipidus, are connected to the impaired function of these channels. They form tetramers in the cell membrane, and facilitate the transport of ...

  18. Effects of Acute Systemic Hypoxia and Hypercapnia on Brain Damage in a Rat Model of Hypoxia-Ischemia.

    Directory of Open Access Journals (Sweden)

    Wanchao Yang

    Full Text Available Therapeutic hypercapnia has the potential for neuroprotection after global cerebral ischemia. Here we further investigated the effects of different degrees of acute systemic hypoxia in combination with hypercapnia on brain damage in a rat model of hypoxia and ischemia. Adult wistar rats underwent unilateral common carotid artery (CCA ligation for 60 min followed by ventilation with normoxic or systemic hypoxic gas containing 11%O2,13%O2,15%O2 and 18%O2 (targeted to PaO2 30-39 mmHg, 40-49 mmHg, 50-59 mmHg, and 60-69 mmHg, respectively or systemic hypoxic gas containing 8% carbon dioxide (targeted to PaCO2 60-80 mmHg for 180 min. The mean artery pressure (MAP, blood gas, and cerebral blood flow (CBF were evaluated. The cortical vascular permeability and brain edema were examined. The ipsilateral cortex damage and the percentage of hippocampal apoptotic neurons were evaluated by Nissl staining and terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate-biotin nick end labeling (TUNEL assay as well as flow cytometry, respectively. Immunofluorescence and western blotting were performed to determine aquaporin-4 (AQP4 expression. In rats treated with severe hypoxia (PaO2 50 mmHg, hypercapnia protected against these pathophysiological changes. Moreover, hypercapnia treatment significantly reduced brain damage in the ischemic ipsilateral cortex and decreased the percentage of apoptotic neurons in the hippocampus after the CCA ligated rats were exposed to mild or moderate hypoxemia (PaO2 > 50 mmHg; especially under mild hypoxemia (PaO2 > 60 mmHg, hypercapnia significantly attenuated the expression of AQP4 protein with brain edema (p < 0.05. Hypercapnia exerts beneficial effects under mild to moderate hypoxemia and augments detrimental effects under severe hypoxemia on brain damage in a rat model of hypoxia-ischemia.

  19. Increased occurrence of anti-AQP4 seropositivity and unique HLA Class II associations with neuromyelitis optica (NMO), among Muslim Arabs in Israel.

    Science.gov (United States)

    Brill, Livnat; Mandel, Micha; Karussis, Dimitrios; Petrou, Panayiota; Miller, Keren; Ben-Hur, Tamir; Karni, Arnon; Paltiel, Ora; Israel, Shoshana; Vaknin-Dembinsky, Adi

    2016-04-15

    Previous studies have revealed different human leukocyte antigen (HLA) associations in multiple sclerosis (MS) and neuromyelitis optica (NMO), further discriminating these two demyelinating pathological conditions. In worldwide analyses, NMO and opticospinal MS are represented at higher proportions among demyelinating conditions in African, East-Asian and Latin American populations. There are currently no data regarding the prevalence of NMO in Middle East Muslims. The population in Israel is diverse in many ways, and includes subpopulations, based on religion and ethnicity; some exhibit genetic homogeneity. In Israel, the incidence of MS is lower in the Muslim population than the Jewish population and Muslims carry different allele frequency distribution of HLA haplotypes. To evaluate the occurrence of anti-AQP4 seropositivity in the Israeli Muslim population among patients with central nervous system (CNS) demyelinating conditions; and to identify the HLA DR and DQ profiles of Muslim Arab Israeli patients with NMO spectrum of diseases (NMOSD). The prevalence of anti-AQP4 seropositivity was analyzed in 342 samples, obtained from patients with various CNS demyelinating conditions and in a validation set of 310 samples. HLA class II alleles (HLA-DRB1 and DQB1) were examined in DNA samples from 35 Israeli Muslim Arabs NMO patients and compared to available data from 74 Israeli Muslim controls. Our data reveal a significantly increased prevalence of anti-AQP4 seropositivity, indicative of NMOSD, in Muslim Arab Israeli patients with initial diagnosis of a CNS demyelinating syndrome. In this population, there was a positive association with the HLA-DRB1*04:04 and HLA-DRB1*10:01 alleles (p=0.03), and a strong negative association with the HLA-DRB1*07 and HLA-DQB1*02:02 alleles (p=0.003, p=0.002). Our findings indicate a possibly increased prevalence of NMOSD in Muslim Arabs in Israel with distinct (positive and negative) HLA associations. Further studies in patients with

  20. Functional consequences of neuromyelitis optica-IgG astrocyte interactions on blood-brain barrier permeability and granulocyte recruitment.

    Science.gov (United States)

    Vincent, Thierry; Saikali, Philippe; Cayrol, Romain; Roth, Alejandro D; Bar-Or, Amit; Prat, Alexandre; Antel, Jack P

    2008-10-15

    Autoantibody neuromyelitis optica-IgG (NMO-IgG) recognizing aquaporin-4 (AQP4) is implicated as playing a central role in the physiopathology of NMO. The aim of this in vitro-based study was to characterize functional consequences of interaction between NMO-IgG and cells of the neurovascular unit (astrocytes and brain endothelium) that would provide insight into recognized features of NMO, namely altered blood-brain barrier (BBB) permeability and granulocyte recruitment. We used sera from NMO and longitudinally extensive transverse myelitis cases shown to bind in a characteristic perivascular pattern to primate cerebellar slices. Using flow cytometry, we found that sera from NMO-IgG-positive patients reacted with CNS-derived human fetal astrocytes, whereas sera from multiple sclerosis patients did not. We demonstrated that NMO-IgG binding to astrocytes alters aquaporin-4 polarized expression and increases permeability of a human BBB endothelium/astrocyte barrier. We further demonstrated that NMO-IgG binding to human fetal astrocytes can result in NK cell degranulation, astrocyte killing by Ab-dependent cellular cytotoxicity and complement-dependent granulocyte attraction through the BBB model. Our study highlights important functional roles for NMO-IgG that could account for pathological lesions and BBB dysfunction observed in NMO.

  1. Relative CO(2)/NH(3) selectivities of mammalian aquaporins 0-9.

    Science.gov (United States)

    Geyer, R Ryan; Musa-Aziz, Raif; Qin, Xue; Boron, Walter F

    2013-05-15

    Previous work showed that aquaporin 1 (AQP1), AQP4-M23, and AQP5 each has a characteristic CO(2)/NH(3) and CO(2)/H(2)O permeability ratio. The goal of the present study is to characterize AQPs 0-9, which traffic to the plasma membrane when heterologously expressed in Xenopus oocytes. We use video microscopy to compute osmotic water permeability (P(f)) and microelectrodes to record transient changes in surface pH (ΔpH(S)) caused by CO(2) or NH(3) influx. Subtracting respective values for day-matched, H(2)O-injected control oocytes yields the channel-specific values P(f)* and ΔpH(S)*. We find that P(f)* is significantly >0 for all AQPs tested except AQP6. (ΔpH(S)*)(CO(2)) is significantly >0 for AQP0, AQP1, AQP4-M23, AQP5, AQP6, and AQP9. (ΔpH(S)*)(NH(3)) is >0 for AQP1, AQP3, AQP6, AQP7, AQP8, and AQP9. The ratio (ΔpH(S)*)(CO(2))/P(f)* falls in the sequence AQP6 (∞) > AQP5 > AQP4-M23 > AQP0 ≅ AQP1 ≅ AQP9 > others (0). The ratio (ΔpH(S)*)(NH(3))/P(f)* falls in the sequence AQP6 (∞) > AQP3 ≅ AQP7 ≅ AQP8 ≅ AQP9 > AQP1 > others (0). Finally, the ratio (ΔpH(S)*)(CO(2))/(-ΔpH(S)*)(NH(3)) falls in the sequence AQP0 (∞) ≅ AQP4-M23 ≅ AQP5 > AQP6 > AQP1 > AQP9 > AQP3 (0) ≅ AQP7 ≅ AQP8. The ratio (ΔpH(S)*)(CO(2))/(-ΔpH(S)*)(NH(3)) is indeterminate for both AQP2 and AQP4-M1. In summary, we find that mammalian AQPs exhibit a diverse range of selectivities for CO(2) vs. NH(3) vs. H(2)O. As a consequence, by expressing specific combinations of AQPs, cells could exert considerable control over the movements of each of these three substances.

  2. Therapeutic Cleavage of Anti–Aquaporin-4 Autoantibody in Neuromyelitis Optica by an IgG-Selective Proteinase

    Science.gov (United States)

    Tradtrantip, Lukmanee; Asavapanumas, Nithi

    2013-01-01

    Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system caused by binding of pathogenic IgG autoantibodies (NMO-IgG) to astrocyte water channel aquaporin-4 (AQP4). Astrocyte damage and downstream inflammation require NMO-IgG effector function to initiate complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC). Here, we evaluated the potential therapeutic utility of the bacterial enzyme IdeS (IgG-degrading enzyme of Streptococcus pyogenes), which selectively cleaves IgG antibodies to yield Fc and F(ab′)2 fragments. In AQP4-expressing cell cultures, IdeS treatment of monoclonal NMO-IgGs and NMO patient sera abolished CDC and ADCC, even when IdeS was added after NMO-IgG was bound to AQP4. Binding of NMO-IgG to AQP4 was similar to that of the NMO-F(ab′)2 generated by IdeS cleavage. NMO-F(ab′)2 competitively displaced pathogenic NMO-IgG, preventing cytotoxicity, and the Fc fragments generated by IdeS cleavage reduced CDC and ADCC. IdeS efficiently cleaved NMO-IgG in mice in vivo, and greatly reduced NMO lesions in mice administered NMO-IgG and human complement. IgG-selective cleavage by IdeS thus neutralizes NMO-IgG pathogenicity, and yields therapeutic F(ab′)2 and Fc fragments. IdeS treatment, by therapeutic apheresis or direct administration, may be beneficial in NMO. PMID:23571414

  3. Aquaporins in Plants.

    Science.gov (United States)

    Maurel, Christophe; Boursiac, Yann; Luu, Doan-Trung; Santoni, Véronique; Shahzad, Zaigham; Verdoucq, Lionel

    2015-10-01

    Aquaporins are membrane channels that facilitate the transport of water and small neutral molecules across biological membranes of most living organisms. In plants, aquaporins occur as multiple isoforms reflecting a high diversity of cellular localizations, transport selectivity, and regulation properties. Plant aquaporins are localized in the plasma membrane, endoplasmic reticulum, vacuoles, plastids and, in some species, in membrane compartments interacting with symbiotic organisms. Plant aquaporins can transport various physiological substrates in addition to water. Of particular relevance for plants is the transport of dissolved gases such as carbon dioxide and ammonia or metalloids such as boron and silicon. Structure-function studies are developed to address the molecular and cellular mechanisms of plant aquaporin gating and subcellular trafficking. Phosphorylation plays a central role in these two processes. These mechanisms allow aquaporin regulation in response to signaling intermediates such as cytosolic pH and calcium, and reactive oxygen species. Combined genetic and physiological approaches are now integrating this knowledge, showing that aquaporins play key roles in hydraulic regulation in roots and leaves, during drought but also in response to stimuli as diverse as flooding, nutrient availability, temperature, or light. A general hydraulic control of plant tissue expansion by aquaporins is emerging, and their role in key developmental processes (seed germination, emergence of lateral roots) has been established. Plants with genetically altered aquaporin functions are now tested for their ability to improve plant tolerance to stresses. In conclusion, research on aquaporins delineates ever expanding fields in plant integrative biology thereby establishing their crucial role in plants. Copyright © 2015 the American Physiological Society.

  4. The subcellular distribution of aquaporin 5 in the cochlea reveals a water shunt at the perilymph-endolymph barrier.

    Science.gov (United States)

    Hirt, B; Penkova, Z H; Eckhard, A; Liu, W; Rask-Andersen, H; Müller, M; Löwenheim, H

    2010-07-28

    Aquaporins are membrane water channel proteins that have also been identified in the cochlea. Auditory function critically depends on the homeostasis of the cochlear fluids perilymph and endolymph. In particular, the ion and water regulation of the endolymph is essential for sensory transduction. Within the cochlear duct the lateral wall epithelium has been proposed to secrete endolymph by an aquaporin-mediated flow of water across its epithelial tight junction barrier. This study identifies interspecies differences in the cellular distribution of aquaporin 5 (AQP5) in the cochlear lateral wall of mice, rats, gerbils and guinea pigs. In addition the cellular expression pattern of AQP5 is described in the human cochlea. Developmental changes in rats demonstrate longitudinal and radial gradients along the cochlear duct. During early postnatal development a pancochlear expression is detected. However a regression to the apical quadrant and limitation to outer sulcus cells (OSCs) is observed in the adult. This developmental loss of AQP5 expression in the basal cochlear segments coincides with a morphological loss of contact between OSCs and the endolymph. At the subcellular level, AQP5 exhibits polarized expression in the apical plasma membrane of the OSCs. Complementary, the basolateral membrane in the root processes of the OSCs exhibits AQP4 expression. This differential localization of AQP5 and AQP4 in the apical and basolateral membranes of the same epithelial cell type suggests a direct aquaporin-mediated transcellular water shunt between the perilymph and endolymph in the OSCs of the cochlear lateral wall. In the human cochlea these findings may have pathophysiological implications attributed to a dysfunctional water regulation by AQP5 such as endolymphatic hydrops (i.e. in Meniere's disease) or sensorineural hearing loss (i.e. in Sjögren's syndrome). Copyright (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

  5. Expression of water channel proteins (aquaporins) in the rat Eustachian tube and middle ear mucosa.

    Science.gov (United States)

    Kang, Sung-Ho; Chang, Ki-Hong; Ohcho, Shuji; Lee, Haa-Yung; Cha, Kiweon; Moon, Sung-Kyun; Andalibi, Ali; Lim, David J

    2007-07-01

    Diverse expression of the different subtypes of aquaporins in different parts of the Eustachian tube and middle ear suggests region-specific functions of the aquaporins in the normal physiology of the tubotympanum and also suggests that they may play roles in the pathophysiology of otitis media. The epithelial cells of the middle ear and Eustachian tube must maintain adequate water balance for normal function of the mucociliary system. Since aquaporins (AQPs) are known to play critical roles in water homeostasis, we investigated their expression in the tubotympanum of the rat. The expression of AQP subtypes 1, 2, 4, 5, and 7 were examined in the rat Eustachian tube and middle ear using RT-PCR, Western blotting, and immunohistochemistry. Transcripts for AQP 1, 4, and 5 were detected in the Eustachian tube and middle ear. Expression of these molecules at the protein level was confirmed by Western blot analysis. Immunohistochemical analysis demonstrated that AQP 4 was localized to the basolateral membranes of ciliated epithelial cells while AQP 5 was localized to the apical surface of serous gland cells, but not goblet cells, in the rat Eustachian tube. AQP 1 was found to be expressed by the subepithelial fibroblasts.

  6. Central Role of Maladapted Astrocytic Plasticity in Ischemic Brain Edema Formation.

    Science.gov (United States)

    Wang, Yu-Feng; Parpura, Vladimir

    2016-01-01

    Brain edema formation and the ensuing brain damages are the major cause of high mortality and long term disability following the occurrence of ischemic stroke. In this process, oxygen and glucose deprivation and the resulting reperfusion injury play primary roles. In response to the ischemic insult, the neurovascular unit experiences both intracellular and extracellular edemas, associated with maladapted astrocytic plasticity. The astrocytic plasticity includes both morphological and functional plasticity. The former involves a reactive gliosis and the subsequent glial retraction. It relates to the capacity of astrocytes to buffer changes in extracellular chemical levels, particularly K(+) and glutamate, as well as the integrity of the blood-brain barrier (BBB). The latter involves the expression and activity of a series of ion and water transport proteins. These molecules are grouped together around glial fibrillary acidic protein (GFAP) and water channel protein aquaporin 4 (AQP4) to form functional networks, regulate hydromineral balance across cell membranes and maintain the integrity of the BBB. Intense ischemic challenges can disrupt these capacities of astrocytes and result in their maladaptation. The maladapted astrocytic plasticity in ischemic stroke cannot only disrupt the hydromineral homeostasis across astrocyte membrane and the BBB, but also leads to disorders of the whole neurovascular unit. This review focuses on how the maladapted astrocytic plasticity in ischemic stroke plays the central role in the brain edema formation.

  7. A Single Amino Acid Substitution Prevents Recognition of a Dominant Human Aquaporin-4 Determinant in the Context of HLA-DRB1*03:01 by a Murine TCR.

    Directory of Open Access Journals (Sweden)

    Benjamine Arellano

    Full Text Available Aquaporin 4 (AQP4 is considered a putative autoantigen in patients with Neuromyelitis optica (NMO, an autoinflammatory disorder of the central nervous system (CNS. HLA haplotype analyses of patients with NMO suggest a positive association with HLA-DRB1* 03:01. We previously showed that the human (h AQP4 peptide 281-300 is the dominant immunogenic determinant of hAQP4 in the context of HLA-DRB1*03:01. This immunogenic peptide stimulates a strong Th1 and Th17 immune response. AQP4281-300-specific encephalitogenic CD4+ T cells should initiate CNS inflammation that results in a clinical phenotype in HLA-DRB1*03:01 transgenic mice.Controlled study with humanized experimental animals. HLA-DRB1*03:01 transgenic mice were immunized with hAQP4281-300, or whole-length hAQP4 protein emulsified in complete Freund's adjuvant. Humoral immune responses to both antigens were assessed longitudinally. In vivo T cell frequencies were assessed by tetramer staining. Mice were followed clinically, and the anterior visual pathway was tested by pupillometry. CNS tissue was examined histologically post-mortem. Flow cytometry was utilized for MHC binding assays and to immunophenotype T cells, and T cell frequencies were determined by ELISpot assay.Immunization with hAQP4281-300 resulted in an in vivo expansion of antigen-specific CD4+ T cells, and an immunoglobulin isotype switch. HLA-DRB1*03:01 TG mice actively immunized with hAQP4281-300, or with whole-length hAQP4 protein were resistant to developing a neurological disease that resembles NMO. Experimental mice show no histological evidence of CNS inflammation, nor change in pupillary responses. Subsequent analysis reveals that a single amino acid substitution from aspartic acid in hAQP4 to glutamic acid in murine (mAQP4 at position 290 prevents the recognition of hAQP4281-300 by the murine T cell receptor (TCR.Induction of a CNS inflammatory autoimmune disorder by active immunization of HLA-DRB1*03:01 TG mice with

  8. A Single Amino Acid Substitution Prevents Recognition of a Dominant Human Aquaporin-4 Determinant in the Context of HLA-DRB1*03:01 by a Murine TCR.

    Science.gov (United States)

    Arellano, Benjamine; Hussain, Rehana; Miller-Little, William A; Herndon, Emily; Lambracht-Washington, Doris; Eagar, Todd N; Lewis, Robert; Healey, Don; Vernino, Steven; Greenberg, Benjamin M; Stüve, Olaf

    2016-01-01

    Aquaporin 4 (AQP4) is considered a putative autoantigen in patients with Neuromyelitis optica (NMO), an autoinflammatory disorder of the central nervous system (CNS). HLA haplotype analyses of patients with NMO suggest a positive association with HLA-DRB1* 03:01. We previously showed that the human (h) AQP4 peptide 281-300 is the dominant immunogenic determinant of hAQP4 in the context of HLA-DRB1*03:01. This immunogenic peptide stimulates a strong Th1 and Th17 immune response. AQP4281-300-specific encephalitogenic CD4+ T cells should initiate CNS inflammation that results in a clinical phenotype in HLA-DRB1*03:01 transgenic mice. Controlled study with humanized experimental animals. HLA-DRB1*03:01 transgenic mice were immunized with hAQP4281-300, or whole-length hAQP4 protein emulsified in complete Freund's adjuvant. Humoral immune responses to both antigens were assessed longitudinally. In vivo T cell frequencies were assessed by tetramer staining. Mice were followed clinically, and the anterior visual pathway was tested by pupillometry. CNS tissue was examined histologically post-mortem. Flow cytometry was utilized for MHC binding assays and to immunophenotype T cells, and T cell frequencies were determined by ELISpot assay. Immunization with hAQP4281-300 resulted in an in vivo expansion of antigen-specific CD4+ T cells, and an immunoglobulin isotype switch. HLA-DRB1*03:01 TG mice actively immunized with hAQP4281-300, or with whole-length hAQP4 protein were resistant to developing a neurological disease that resembles NMO. Experimental mice show no histological evidence of CNS inflammation, nor change in pupillary responses. Subsequent analysis reveals that a single amino acid substitution from aspartic acid in hAQP4 to glutamic acid in murine (m)AQP4 at position 290 prevents the recognition of hAQP4281-300 by the murine T cell receptor (TCR). Induction of a CNS inflammatory autoimmune disorder by active immunization of HLA-DRB1*03:01 TG mice with human hAQP4281

  9. Aquaporins as gas channels.

    Science.gov (United States)

    Herrera, Marcela; Garvin, Jeffrey L

    2011-10-01

    Gas molecules play important roles in human physiology. Volatile substances produced by one cell often regulate neighboring cells in a paracrine fashion. While gaseous molecules have traditionally been thought to travel from cell to cell by free diffusion through the bilayer portion of the membrane, this does not explain their rapid physiological actions. The recent observations that: (1) water channels can transport other molecules besides water, and (2) aquaporins are often expressed in tissues where gas (but not water) transport is essential suggest that these channels conduct physiologically important gases in addition to water. This review summarizes recent findings on the role of aquaporins as gas transporters as well as their physiological significance.

  10. Glymphatic distribution of CSF-derived apoE into brain is isoform specific and suppressed during sleep deprivation.

    Science.gov (United States)

    Achariyar, Thiyagaragan M; Li, Baoman; Peng, Weiguo; Verghese, Philip B; Shi, Yang; McConnell, Evan; Benraiss, Abdellatif; Kasper, Tristan; Song, Wei; Takano, Takahiro; Holtzman, David M; Nedergaard, Maiken; Deane, Rashid

    2016-12-08

    Apolipoprotein E (apoE) is a major carrier of cholesterol and essential for synaptic plasticity. In brain, it's expressed by many cells but highly expressed by the choroid plexus and the predominant apolipoprotein in cerebrospinal fluid (CSF). The role of apoE in the CSF is unclear. Recently, the glymphatic system was described as a clearance system whereby CSF and ISF (interstitial fluid) is exchanged via the peri-arterial space and convective flow of ISF clearance is mediated by aquaporin 4 (AQP4), a water channel. We reasoned that this system also serves to distribute essential molecules in CSF into brain. The aim was to establish whether apoE in CSF, secreted by the choroid plexus, is distributed into brain, and whether this distribution pattern was altered by sleep deprivation. We used fluorescently labeled lipidated apoE isoforms, lenti-apoE3 delivered to the choroid plexus, immunohistochemistry to map apoE brain distribution, immunolabeled cells and proteins in brain, Western blot analysis and ELISA to determine apoE levels and radiolabeled molecules to quantify CSF inflow into brain and brain clearance in mice. Data were statistically analyzed using ANOVA or Student's t- test. We show that the glymphatic fluid transporting system contributes to the delivery of choroid plexus/CSF-derived human apoE to neurons. CSF-delivered human apoE entered brain via the perivascular space of penetrating arteries and flows radially around arteries, but not veins, in an isoform specific manner (apoE2 > apoE3 > apoE4). Flow of apoE around arteries was facilitated by AQP4, a characteristic feature of the glymphatic system. ApoE3, delivered by lentivirus to the choroid plexus and ependymal layer but not to the parenchymal cells, was present in the CSF, penetrating arteries and neurons. The inflow of CSF, which contains apoE, into brain and its clearance from the interstitium were severely suppressed by sleep deprivation compared to the sleep state. Thus, choroid plexus

  11. Aquaporin-2 membrane targeting

    DEFF Research Database (Denmark)

    Olesen, Emma T B; Fenton, Robert A

    2017-01-01

    The targeting of the water channel aquaporin-2 (AQP2) to the apical plasma membrane of kidney collecting duct principal cells is regulated mainly by the antidiuretic peptide hormone arginine vasopressin (AVP). This process is of crucial importance for the maintenance of body water homeostasis...

  12. Aquaporins in complex tissues

    DEFF Research Database (Denmark)

    Hamann, S; Zeuthen, T; La Cour, M

    1998-01-01

    Multiple physiological fluid movements are involved in vision. Here we define the cellular and subcellular sites of aquaporin (AQP) water transport proteins in human and rat eyes by immunoblotting, high-resolution immunocytochemistry, and immunoelectron microscopy. AQP3 is abundant in bulbar......, predicting specific roles for each in the complex network through which water movements occur in the eye....

  13. The Role of Brain-Reactive Autoantibodies in Brain Pathology and Cognitive Impairment

    Directory of Open Access Journals (Sweden)

    Simone Mader

    2017-09-01

    Full Text Available Antibodies to different brain proteins have been recently found to be associated with an increasing number of different autoimmune diseases. They need to penetrate the blood–brain barrier (BBB in order to bind antigens within the central nervous system (CNS. They can target either neuronal or non-neuronal antigen and result in damage either by themselves or in synergy with other inflammatory mediators. Antibodies can lead to acute brain pathology, which may be reversible; alternatively, they may trigger irreversible damage that persists even though the antibodies are no longer present. In this review, we will describe two different autoimmune conditions and the role of their antibodies in causing brain pathology. In systemic lupus erythematosus (SLE, patients can have double stranded DNA antibodies that cross react with the neuronal N-methyl-d-aspartate receptor (NMDAR, which have been recently linked to neurocognitive dysfunction. In neuromyelitis optica (NMO, antibodies to astrocytic aquaporin-4 (AQP4 are diagnostic of disease. There is emerging evidence that pathogenic T cells also play an important role for the disease pathogenesis in NMO since they infiltrate in the CNS. In order to enable appropriate and less invasive treatment for antibody-mediated diseases, we need to understand the mechanisms of antibody-mediated pathology, the acute and chronic effects of antibody exposure, if the antibodies are produced intrathecally or systemically, their target antigen, and what triggers their production. Emerging data also show that in utero exposure to some brain-reactive antibodies, such as those found in SLE, can cause neurodevelopmental impairment since they can penetrate the embryonic BBB. If the antibody exposure occurs at a critical time of development, this can result in irreversible damage of the offspring that persists throughout adulthood.

  14. Aquaporin 4-specific T cells and NMO-IgG cause primary retinal damage in experimental NMO/SD.

    Science.gov (United States)

    Zeka, Bleranda; Hastermann, Maria; Kaufmann, Nathalie; Schanda, Kathrin; Pende, Marko; Misu, Tatsuro; Rommer, Paulus; Fujihara, Kazuo; Nakashima, Ichiro; Dahle, Charlotte; Leutmezer, Fritz; Reindl, Markus; Lassmann, Hans; Bradl, Monika

    2016-08-08

    Neuromyelitis optica/spectrum disorder (NMO/SD) is a severe, inflammatory disease of the central nervous system (CNS). In the majority of patients, it is associated with the presence of pathogenic serum autoantibodies (the so-called NMO-IgGs) directed against the water channel aquaporin 4 (AQP4), and with the formation of large, astrocyte-destructive lesions in spinal cord and optic nerves. A large number of recent studies using optical coherence tomography (OCT) demonstrated that damage to optic nerves in NMO/SD is also associated with retinal injury, as evidenced by retinal nerve fiber layer (RNFL) thinning and microcystic inner nuclear layer abnormalities. These studies concluded that retinal injury in NMO/SD patients results from secondary neurodegeneration triggered by optic neuritis.However, the eye also contains cells expressing AQP4, i.e., Müller cells and astrocytes in the retina, epithelial cells of the ciliary body, and epithelial cells of the iris, which raised the question whether the eye can also be a primary target in NMO/SD. Here, we addressed this point in experimental NMO/SD (ENMO) induced in Lewis rat by transfer of AQP4268-285-specific T cells and NMO-IgG.We show that these animals show retinitis and subsequent dysfunction/damage of retinal axons and neurons, and that this pathology occurs independently of the action of NMO-IgG. We further show that in the retinae of ENMO animals Müller cell side branches lose AQP4 reactivity, while retinal astrocytes and Müller cell processes in the RNFL/ganglionic cell layers are spared. These changes only occur in the presence of both AQP4268-285-specific T cells and NMO-IgG.Cumulatively, our data show that damage to retinal cells can be a primary event in NMO/SD.

  15. Linking Binge Alcohol-Induced Neurodamage to Brain Edema and Potential Aquaporin-4 Upregulation: Evidence in Rat Organotypic Brain Slice Cultures and In Vivo

    OpenAIRE

    Sripathirathan, Kumar; Brown, James; Neafsey, Edward J.; Collins, Michael A.

    2009-01-01

    Brain edema and derived oxidative stress potentially are critical events in the hippocampal-entorhinal cortical (HEC) neurodegeneration caused by binge alcohol (ethanol) intoxication and withdrawal in adult rats. Edema's role is based on findings that furosemide diuretic antagonizes binge alcohol–dependent brain overhydration and neurodamage in vivo and in rat organotypic HEC slice cultures. However, evidence that furosemide has significant antioxidant potential and knowledge that alcohol can...

  16. Aquaporin-3 in Cancer

    OpenAIRE

    Saw Marlar; Jensen, Helene H.; Frédéric H. Login; Nejsum, Lene N

    2017-01-01

    Increasing evidence suggests that the water/glycerol channel aquaporin-3 (AQP3) plays a pivotal role in cancer metastasis. AQP3 knockout mice were resistant to skin tumor formation and overexpression correlated with metastasis and poor prognosis in patients with breast or gastric cancer. In cultured cancer cells, increased AQP3 expression stimulated several intracellular signaling pathways and resulted in increased cell proliferation, migration, and invasion as well as aggravation of epitheli...

  17. The neuromyelitis optica presentation and the aquaporin-4 antibody in HIV-seropositive and seronegative patients in KwaZulu-Natal, South Africa

    Directory of Open Access Journals (Sweden)

    Ahmed I. Bhigjee

    2017-01-01

    Full Text Available Background: The association of the anti-aquaporin-4 (AQP-4 water channel antibody with neuromyelitis optica (NMO syndrome has been described from various parts of the world. There has been no large study describing this association from southern Africa, an HIV endemic area. HIV patients often present with visual disturbance or features of a myelopathy but seldom both either simultaneously or consecutively. We report our experience of NMO in the era of AQP-4 testing in HIV-positive and HIV-negative patients seen in KwaZulu-Natal, South Africa.Methods: A retrospective chart review was undertaken of NMO cases seen from January 2005 to April 2016 in two neurology units serving a population of 7.1 million adults. The clinical, radiological and relevant laboratory data were extracted from the files and analysed.Results: There were 12 HIV-positive patients (mean age 33 years, 9 (75% were women and all 12 were black patients. Of the 17 HIV-negative patients (mean age 32 years, 15 (88% were women and 10 (59% were black people. The clinical features in the two groups ranged from isolated optic neuritis, isolated longitudinally extensive myelitis or combinations. Recurrent attacks were noted in six HIV-positive patients and six HIV-negative patients. The AQP-4 antibody was positive in 4/10 (40% HIV-positive patients and 11/13 (85% HIV-negative patients. The radiological changes ranged from longitudinal hyperintense spinal cord lesions and long segment enhancing lesions of the optic nerves. Three patients, all HIV-positive, had tumefactive lesions with incomplete ring enhancement.Conclusion: This study confirms the presence of AQP-4-positive NMO in southern Africa in both HIV-positive and HIV-negative patients. The simultaneous or consecutive occurrence of optic neuritis and myelitis in an HIV-positive patient should alert the clinician to test for the AQP-4 antibody. It is important to recognise this clinical syndrome as specific therapy is available. We

  18. Water Channels Aquaporin 4 and -1 Expression in Subependymoma Depends on the Localization of the Tumors.

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    Susan Noell

    Full Text Available We analyzed aquaporin 4 and -1 expression in subependymomas, benign and slow growing brain tumors WHO grade I. Ten subependymoma cases were investigated, five of the fossa inferior and five of the fossa superior.Using immunohistochemistry, we observed different aquaporin expression patterns depending on localization: aquaporin 4 and -1 were detected in infratentorial subependymomas in the entire tumor tissue. In contrast, supratentorial subependymomas revealed aquaporin 4 and -1 expression only in border areas of the tumor. PCR analyses however showed no difference in aquaporin 4 expression between all subependymomas independent of localization but at higher levels than in normal brain. In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples. The reason for the different distribution pattern of aquaporin 4 in subependymomas still remains unclear. On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found. This was similar to our previous findings in malignant glioblastomas. From these studies, we know that extracellular matrix molecules within the tumor like agrin and its receptor alpha-dystroglycan are involved in forming orthogonal arrays of particles. In subependymomas neither agrin nor alpha-dystroglycan were detected around blood vessels.Taken together, we show in this study that in the benign subependymomas aquaporins 1 and 4 are dramatically redistributed and upregulated. We speculate that extracellular environments of infra- and supratentorial subependymomas are different and lead to different distribution patterns of aquaporin 4 and -1.

  19. Activation of P2X7 promotes cerebral edema and neurological injury after traumatic brain injury in mice.

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    Donald E Kimbler

    Full Text Available Traumatic brain injury (TBI is a leading cause of death and disability worldwide. Cerebral edema, the abnormal accumulation of fluid within the brain parenchyma, contributes to elevated intracranial pressure (ICP and is a common life-threatening neurological complication following TBI. Unfortunately, neurosurgical approaches to alleviate increased ICP remain controversial and medical therapies are lacking due in part to the absence of viable drug targets. In the present study, genetic inhibition (P2X7-/- mice of the purinergic P2x7 receptor attenuated the expression of the pro-inflammatory cytokine, interleukin-1β (IL-1β and reduced cerebral edema following controlled cortical impact, as compared to wild-type mice. Similarly, brilliant blue G (BBG, a clinically non-toxic P2X7 inhibitor, inhibited IL-1β expression, limited edemic development, and improved neurobehavioral outcomes after TBI. The beneficial effects of BBG followed either prophylactic administration via the drinking water for one week prior to injury or via an intravenous bolus administration up to four hours after TBI, suggesting a clinically-implementable therapeutic window. Notably, P2X7 localized within astrocytic end feet and administration of BBG decreased the expression of glial fibrillary acidic protein (GFAP, a reactive astrocyte marker, and attenuated the expression of aquaporin-4 (AQP4, an astrocytic water channel that promotes cellular edema. Together, these data implicate P2X7 as a novel therapeutic target to prevent secondary neurological injury after TBI, a finding that warrants further investigation.

  20. Therapeutic effects of Euphorbia Pekinensis and Glycyrrhiza glabra on Hepatocellular Carcinoma Ascites Partially Via Regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 Signal Axis

    Science.gov (United States)

    Zhang, Yanqiong; Yan, Chen; Li, Yuting; Mao, Xia; Tao, Weiwei; Tang, Yuping; Lin, Ya; Guo, Qiuyan; Duan, Jingao; Lin, Na

    2017-02-01

    To clarify unknown rationalities of herbaceous compatibility of Euphorbia Pekinensis (DJ) and Glycyrrhiza glabra (GC) acting on hepatocellular carcinoma (HCC) ascites, peritoneum transcriptomics profiling of 15 subjects, including normal control (Con), HCC ascites mouse model (Mod), DJ-alone, DJ/GC-synergy and DJ/GC-antagonism treatment groups were performed on OneArray platform, followed by differentially expressed genes (DEGs) screening. DEGs between Mod and Con groups were considered as HCC ascites-related genes, and those among different drug treatment and Mod groups were identified as DJ/GC-combination-related genes. Then, an interaction network of HCC ascites-related gene-DJ/GC combination-related gene-known therapeutic target gene for ascites was constructed. Based on nodes’ degree, closeness, betweenness and k-coreness, the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis with highly network topological importance was demonstrated to be a candidate target of DJ/GC combination acting on HCC ascites. Importantly, both qPCR and western blot analyses verified this regulatory effects based on HCC ascites mice in vivo and M-1 collecting duct cells in vitro. Collectively, different combination designs of DJ and GC may lead to synergistic or antagonistic effects on HCC ascites partially via regulating the Frk-Arhgdib-Inpp5d-Avpr2-Aqp4 axis, implying that global gene expression profiling combined with network analysis can offer an effective way to understand pharmacological mechanisms of traditional Chinese medicine prescriptions.

  1. Aquaporins in the Eye

    DEFF Research Database (Denmark)

    Tran, Thuy Linh; Hamann, Steffen; Heegaard, Steffen

    2017-01-01

    The major part of the eye consists of water . Continuous movement of water and ions between the ocular compartments and to the systemic circulation is pivotal for many physiological functions in the eye. The movement of water facilitates removal of the many metabolic products of corneal-, ciliary...... pressure. In the retina, water is transported into the vitreous body and across the retinal pigment epithelium to regulate the extracellular environment and the hydration of the retina. Aquaporins (AQPs ) take part in the water transport throughout the eye....

  2. Aquaporin Protein-Protein Interactions

    Directory of Open Access Journals (Sweden)

    Jennifer Virginia Roche

    2017-10-01

    Full Text Available Aquaporins are tetrameric membrane-bound channels that facilitate transport of water and other small solutes across cell membranes. In eukaryotes, they are frequently regulated by gating or trafficking, allowing for the cell to control membrane permeability in a specific manner. Protein–protein interactions play crucial roles in both regulatory processes and also mediate alternative functions such as cell adhesion. In this review, we summarize recent knowledge about aquaporin protein–protein interactions; dividing the interactions into three types: (1 interactions between aquaporin tetramers; (2 interactions between aquaporin monomers within a tetramer (hetero-tetramerization; and (3 transient interactions with regulatory proteins. We particularly focus on the structural aspects of the interactions, discussing the small differences within a conserved overall fold that allow for aquaporins to be differentially regulated in an organism-, tissue- and trigger-specific manner. A deep knowledge about these differences is needed to fully understand aquaporin function and regulation in many physiological processes, and may enable design of compounds targeting specific aquaporins for treatment of human disease.

  3. MOG-IgG in NMO and related disorders: a multicenter study of 50 patients. Part 1: Frequency, syndrome specificity, influence of disease activity, long-term course, association with AQP4-IgG, and origin.

    Science.gov (United States)

    Jarius, Sven; Ruprecht, Klemens; Kleiter, Ingo; Borisow, Nadja; Asgari, Nasrin; Pitarokoili, Kalliopi; Pache, Florence; Stich, Oliver; Beume, Lena-Alexandra; Hümmert, Martin W; Trebst, Corinna; Ringelstein, Marius; Aktas, Orhan; Winkelmann, Alexander; Buttmann, Mathias; Schwarz, Alexander; Zimmermann, Hanna; Brandt, Alexander U; Franciotta, Diego; Capobianco, Marco; Kuchling, Joseph; Haas, Jürgen; Korporal-Kuhnke, Mirjam; Lillevang, Soeren Thue; Fechner, Kai; Schanda, Kathrin; Paul, Friedemann; Wildemann, Brigitte; Reindl, Markus

    2016-09-26

    Antibodies to myelin oligodendrocyte glycoprotein (MOG-IgG) have been suggested to play a role in a subset of patients with neuromyelitis optica and related disorders. To assess (i) the frequency of MOG-IgG in a large and predominantly Caucasian cohort of patients with optic neuritis (ON) and/or myelitis; (ii) the frequency of MOG-IgG among AQP4-IgG-positive patients and vice versa; (iii) the origin and frequency of MOG-IgG in the cerebrospinal fluid (CSF); (iv) the presence of MOG-IgG at disease onset; and (v) the influence of disease activity and treatment status on MOG-IgG titers. 614 serum samples from patients with ON and/or myelitis and from controls, including 92 follow-up samples from 55 subjects, and 18 CSF samples were tested for MOG-IgG using a live cell-based assay (CBA) employing full-length human MOG-transfected HEK293A cells. MOG-IgG was detected in 95 sera from 50 patients with ON and/or myelitis, including 22/54 (40.7 %) patients with a history of both ON and myelitis, 22/103 (21.4 %) with a history of ON but no myelitis and 6/45 (13.3 %) with a history of longitudinally extensive transverse myelitis but no ON, and in 1 control patient with encephalitis and a connective tissue disorder, all of whom were negative for AQP4-IgG. MOG-IgG was absent in 221 further controls, including 83 patients with AQP4-IgG-seropositive neuromyelitis optica spectrum disorders and 85 with multiple sclerosis (MS). MOG-IgG was found in 12/18 (67 %) CSF samples from MOG-IgG-seropositive patients; the MOG-IgG-specific antibody index was negative in all cases, indicating a predominantly peripheral origin of CSF MOG-IgG. Serum and CSF MOG-IgG belonged to the complement-activating IgG1 subclass. MOG-IgG was present already at disease onset. The antibodies remained detectable in 40/45 (89 %) follow-up samples obtained over a median period of 16.5 months (range 0-123). Serum titers were higher during attacks than during remission (p IgG to human full-length MOG by

  4. Osmotic water transport in aquaporins

    DEFF Research Database (Denmark)

    Zeuthen, Thomas; Alsterfjord, Magnus; Beitz, Eric

    2013-01-01

    no evidence for coupling between water and solute fluxes in the pore. In confirmation of molecular dynamic simulations, we conclude that the magnitude of the osmotic water permeability and the reflection coefficient are determined by processes at the arginine selectivity filter located at the outward......Abstract  We test a novel, stochastic model of osmotic water transport in aquaporins. A solute molecule present at the pore mouth can either be reflected or permeate the pore. We assume that only reflected solute molecules induce osmotic transport of water through the pore, while permeating solute...... molecules give rise to no water transport. Accordingly, the rate of water transport is proportional to the reflection coefficient σ, while the solute permeability, P(S), is proportional to 1 - σ. The model was tested in aquaporins heterologously expressed in Xenopus oocytes. A variety of aquaporin channel...

  5. Expression, Distribution and Role of Aquaporin Water Channels in Human and Animal Stomach and Intestines

    Directory of Open Access Journals (Sweden)

    Cui Zhu

    2016-08-01

    Full Text Available Stomach and intestines are involved in the secretion of gastrointestinal fluids and the absorption of nutrients and fluids, which ensure normal gut functions. Aquaporin water channels (AQPs represent a major transcellular route for water transport in the gastrointestinal tract. Until now, at least 11 AQPs (AQP1–11 have been found to be present in the stomach, small and large intestines. These AQPs are distributed in different cell types in the stomach and intestines, including gastric epithelial cells, gastric glands cells, absorptive epithelial cells (enterocytes, goblet cells and Paneth cells. AQP1 is abundantly distributed in the endothelial cells of the gastrointestinal tract. AQP3 and AQP4 are mainly distributed in the basolateral membrane of epithelial cells in the stomach and intestines. AQP7, AQP8, AQP10 and AQP11 are distributed in the apical of enterocytes in the small and large intestines. Although AQP-null mice displayed almost no phenotypes in gastrointestinal tracts, the alterations of the expression and localization of these AQPs have been shown to be associated with the pathology of gastrointestinal disorders, which suggests that AQPs play important roles serving as potential therapeutic targets. Therefore, this review provides an overview of the expression, localization and distribution of AQPs in the stomach, small and large intestine of human and animals. Furthermore, this review emphasizes the potential roles of AQPs in the physiology and pathophysiology of stomach and intestines.

  6. Aquaporins in human breast cancer: identification and involvement in carcinogenesis of breast cancer.

    Science.gov (United States)

    Shi, Zhonghua; Zhang, Ting; Luo, Liang; Zhao, Hua; Cheng, Jing; Xiang, Jingying; Zhao, Chun

    2012-09-01

    Aquaporins (AQPs) play important roles in water and glycerol transport. Recently, the role of AQPs in human carcinogenesis has become an area of great interest. However, little is known about the function of AQPs in human breast cancer. The aim of this study was to investigate the expression profile of AQPs in human breast cancer and its significance. In this study, we screened the expression profile of AQP0-12 in breast cancer tissues and corresponding normal tissues by RT-PCR, Western blotting and immunohistochemistry. AQP1, 3-5, and 10-12 were expressed in human breast cancer and/or normal breast tissues, and AQP1 and 3-5 exhibited differential expression. AQP1 was expressed in cell membranes and its expression was higher in cancer than that in normal tissues. AQP4 was expressed in the cell membrane and cytoplasm and was detected markedly stronger in normal than in cancer tissues. AQP5 was expressed mainly in cell membranes in carcinoma tissues, but was almost absent in normal breast tissues. Expression of AQP5 was associated with cellular differentiation, lymph node invasion, and clinicopathological staging. These observations suggested that several subtypes of the AQP family play a role in human breast carcinogenesis. Copyright © 2011 Wiley Periodicals, Inc.

  7. Selective expression of aquaporin 1, 4 and 5 in the rat middle ear.

    Science.gov (United States)

    Minami, S; Kobayashi, H; Yamashita, A; Yanagita, T; Uezono, Y; Yokoo, H; Shiraishi, S; Saitoh, T; Asada, Y; Komune, S; Wada, A

    2001-08-01

    The middle ear cavity is an air-filled space that must be maintained for effective sound transmission to the inner ear. To examine the mechanisms of water homeostasis in the middle ear, we investigated whether aquaporins (AQPs), a family of water-permeable channels, were expressed in the middle ear. Reverse transcription-polymerase chain reaction and immunoblot analyses revealed that mRNAs encoding AQP1, 4 and 5 (but not 2 or 3) subtypes were expressed in rat middle ear epithelium; AQP1, 4 and 5 were detected as 28-, 30- and 30-kDa proteins, respectively. Immunohistochemical analysis showed that AQP1 was localized at capillary endothelial cells and fibroblasts in lamina propria mucosae; AQP4 was present solely at the basolateral membrane of ciliated cells, whereas AQP5 was on the apical surface of ciliated cells as well as of flat and columnar epithelial cells. The characteristic different localizations of AQP1, 4 and 5 subtypes in the middle ear suggest that middle ear water homeostasis requires the coordinated operation of these AQPs.

  8. Expression, Distribution and Role of Aquaporin Water Channels in Human and Animal Stomach and Intestines.

    Science.gov (United States)

    Zhu, Cui; Chen, Zhuang; Jiang, Zongyong

    2016-08-29

    Stomach and intestines are involved in the secretion of gastrointestinal fluids and the absorption of nutrients and fluids, which ensure normal gut functions. Aquaporin water channels (AQPs) represent a major transcellular route for water transport in the gastrointestinal tract. Until now, at least 11 AQPs (AQP1-11) have been found to be present in the stomach, small and large intestines. These AQPs are distributed in different cell types in the stomach and intestines, including gastric epithelial cells, gastric glands cells, absorptive epithelial cells (enterocytes), goblet cells and Paneth cells. AQP1 is abundantly distributed in the endothelial cells of the gastrointestinal tract. AQP3 and AQP4 are mainly distributed in the basolateral membrane of epithelial cells in the stomach and intestines. AQP7, AQP8, AQP10 and AQP11 are distributed in the apical of enterocytes in the small and large intestines. Although AQP-null mice displayed almost no phenotypes in gastrointestinal tracts, the alterations of the expression and localization of these AQPs have been shown to be associated with the pathology of gastrointestinal disorders, which suggests that AQPs play important roles serving as potential therapeutic targets. Therefore, this review provides an overview of the expression, localization and distribution of AQPs in the stomach, small and large intestine of human and animals. Furthermore, this review emphasizes the potential roles of AQPs in the physiology and pathophysiology of stomach and intestines.

  9. Expression of aquaporin water channels in the vagina in premenopausal women.

    Science.gov (United States)

    Kim, Sun-Ouck; Oh, Kyung Jin; Lee, Hyun Suk; Ahn, Kyuyoun; Kim, Soo Wan; Park, Kwangsung

    2011-07-01

    Aquaporins (AQPs) are membrane proteins that facilitate water movement across biological membranes. This study builds on a previous report on the distinct localization of AQPs in the rat vagina. The purposes of this study were to investigate the localization and expression of the AQPs in the vaginal tissue of premenopausal women. Anterior vaginal tissue was collected during transvaginal uterine myomectomy or hysterectomy from 10 premenopausal women (mean age, 40 years) for Western blot and immunohistochemistry. The expression and cellular localization of AQP1-9 were determined in the human vagina by Western blot and immunohistochemistry. Immunolabeling showed that AQP1 was mainly expressed in the capillaries and venules of the vagina, AQP2 was expressed in the cytoplasm of the epithelium, AQP3 was mainly associated with the plasma membrane of the vaginal epithelium, and both AQP5 and AQP6 were expressed in the cytoplasm throughout all vaginal epithelium. Western blot analysis revealed bands at 28 kDa for AQP1, 2, 3, 5, and 6 proteins. However, AQP4, 7, 8, and 9 were not detected. The distinct localization of AQPs in the human vagina suggests that AQP1, 2, 3, 5, and 6 may play an important role in vaginal lubrication in women. © 2011 International Society for Sexual Medicine.

  10. Neuromielitis óptica con alta expresión de acuaporina-4 y anticuerpos anti-acuaporina-4 positivos en suero Neuromyelitis optica with high aquaporin-4 expression and positive serum aquaporin-4 autoantibodies

    Directory of Open Access Journals (Sweden)

    Alejandra Báez

    2012-04-01

    Full Text Available La presencia de anticuerpos IgG en suero, con blanco en los canales de acuaporina-4, es específica de la neuromielitis óptica (NMO. El 60% de los pacientes con NMO presentan lesiones cerebrales en la resonancia magnética (RM; en un 8% (mayoría niños estas lesiones se consideraron "atípicas". Presentamos dos pacientes con NMO y lesiones en el SNC de alta expresión de acuaporina-4. Caso 1: varón de 50 años, que comenzó con pérdida de visión en ojo derecho (OD. Recibió tratamiento empírico con metilprednisolona 1 g/d x 3 días. Al mes presentó dolor generalizado y hemiparesia derecha; nuevamente recibió metilprednisolona 1 g/d x 5 días e IgG IV 400 mg/kg/d × 5 días. Recuperó la deambulación persistiendo el dolor y fenómenos paroxísticos en los 4 miembros. Potenciales evocados visuales: P100, ojo izquierdo (OI 123 mseg. OD sin respuesta. La RM de cerebro (FLAIR mostró hiperintensidad en nervio óptico derecho, hipotálamo y comisura blanca anterior. RM cervical: lesión medular extensa (5 cuerpos vertebrales. Caso 2: mujer de 53 años, con disminución de la agudeza visual en ambos ojos y parestesias en miembros inferiores que remitieron espontáneamente. Evolucionó al mes con cuadriparesia e incontinencia esfinteriana. Recibió metilprednisolona 1 g/d x 5 días, sin mejoría. Potenciales evocados visuales: P100 OI 124 mseg. OD 128 mseg. RM cerebro: (FLAIR hiperintensidad hipotalámica y periacueductal. RM cervical: lesión medular extensa (7 cuerpos vertebrales. Anticuerpos anti-acuaporina-4 positivos en ambos pacientes (inmunofluorescencia indirecta. Las lesiones consideradas "atípicas", como aquí, en sitios con alta densidad de proteínas canales de agua AQP4 deberán considerarse para el diagnóstico diferencial.Disease-specific aquaporin-4 antibodies (NMO-IgG are the main effector of lesions in neuromyelitis optica (NMO patients. Brain MRI lesions are detected in 60% of them, with 8% (almost infants at sites of high

  11. Aquaporin-3 and aquaporin-4 are sorted differently and separately in the trans-Golgi network

    DEFF Research Database (Denmark)

    Christensen, Eva Arnspang; Sundbye, S.; Nelson, W. J.

    2013-01-01

    observed mostly in separate post-Golgi carriers, and spinning disk microscopy showed that most of AQP3 and AQP4 were delivered to the plasma membrane in separate vesicles. In contrast, VSV-G and LDL-R, two well-characterized basolateral proteins, co-localized to a high degree in the same post...

  12. Aquaporin-3 and aquaporin-4 are sorted differently and separately in the trans-Golgi network

    DEFF Research Database (Denmark)

    Christensen, Eva Arnspang; Sundbye, Sabrina Maria Gade; Nelson, W. James

    2013-01-01

    observed mostly in separate post-Golgi carriers, and spinning disk microscopy showed that most of AQP3 and AQP4 were delivered to the plasma membrane in separate vesicles. In contrast, VSV-G and LDL-R, two well-charcterized basolateral proteins, co-localized to a high degree in the same post-Golgi carriers...

  13. Molecular pathology of brain edema after severe burns in forensic autopsy cases with special regard to the importance of reference gene selection.

    Science.gov (United States)

    Wang, Qi; Ishikawa, Takaki; Michiue, Tomomi; Zhu, Bao-Li; Guan, Da-Wei; Maeda, Hitoshi

    2013-09-01

    Brain edema is believed to be linked to high mortality incidence after severe burns. The present study investigated the molecular pathology of brain damage and responses involving brain edema in forensic autopsy cases of fire fatality (n = 55) compared with sudden cardiac death (n = 11), mechanical asphyxia (n = 13), and non-brain injury cases (n = 22). Postmortem mRNA and immunohistochemical expressions of aquaporins (AQPs), claudin5 (CLDN5), and matrix metalloproteinases (MMPs) were examined. Prolonged deaths due to severe burns showed an increase in brain water content, but relative mRNA quantification, using different normalization methods, showed inconsistent results: in prolonged deaths due to severe burns, higher expression levels were detected for all markers when three previously validated reference genes, PES1, POLR2A, and IPO8, were used for normalization, higher for AQP1 and MMP9 when GAPDH alone was used for normalization and higher for MMP9, but lower for MMP2 when B2M alone was used for normalization. Additionally, when B2M alone was used for normalization, higher expression of AQP4 was detected in acute fire deaths. Furthermore, the expression stability values of these five reference genes calculated by geNorm demonstrated that B2M was the least stable one, followed by GAPDH. In immunostaining, only AQP1 and MMP9 showed differences among the causes of death: they were evident in most prolonged deaths due to severe burns. These findings suggest that systematic analysis of gene expressions using real-time PCR might be a useful procedure in forensic death investigation, and validation of reference genes is crucial.

  14. Aquaporin 4 as a NH3 Channel

    DEFF Research Database (Denmark)

    Assentoft, Mette; Kaptan, Shreyas; Schneider, Hans-Peter

    2016-01-01

    Ammonia is a biologically potent molecule, and the regulation of ammonia levels in the mammalian body is, therefore, strictly controlled. The molecular paths of ammonia permeation across plasma membranes remain ill-defined, but the structural similarity of water and NH3 has pointed to the aquapor...... route for NH3 Our data propose that AQP4 belongs to the growing list of NH3-permeable water channels....

  15. [Expression of aquaporin 3 and aquaporin 9 in placenta and fetal membrane with idiopathic polyhydramnios.].

    Science.gov (United States)

    Zhu, Xue-Qiong; Jiang, Shan-Shan; Zou, Shuang-Wei; Hu, Ying-Chun; Wang, Yu-Huan

    2009-12-01

    To investigate the pathogenesis role of aquaporin 3 and aquaporin 9 in idiopathic polyhydramnios by detecting their expression and distribution in fetal membranes and placenta. Twenty-one of term pregnancy women with idiopathic polyhydramnios were enrolled as patient group matched with 30 women with normal term pregnancy as control group. The expression and localization of aquaporin 3 and aquaporin 9 in fetal membranes and placenta were detected by real-time polymerase chain reaction and streptavidin peroxidase immunohistochemiscal staining. (1) The mRNA expressions of aquaporin 3 and aquaporin 9 were detected in amnion, chorion and placental tissue in both patient group and control group. Both aquaporin 3 and aquaporin 9 were demonstrated positive staining in the amnion epithelia, chorion cytotrophoblasts and placental trophoblast. (2) The ratio of aquaporin 3 and aquaporin 9 mRNA expressions in amnion in patient group comparing to those in control group were 5.00 and 3.25, while in chorion they were 2.03 and 2.08. When compared with those in amnion and chorion of control group, there was a significant difference (P polyhydramnios. Further investigation should be needed to clarify the regulatory mechanism of aquaporin 3 and aquaporin 9 expressions.

  16. Robust High Performance Aquaporin based Biomimetic Membranes

    DEFF Research Database (Denmark)

    Helix Nielsen, Claus; Zhao, Yichun; Qiu, C.

    2013-01-01

    Aquaporins are water channel proteins with high water permeability and solute rejection, which makes them promising for preparing high-performance biomimetic membranes. Despite the growing interest in aquaporin-based biomimetic membranes (ABMs), it is challenging to produce robust and defect......% rejection for urea and a water permeability around 10 L/(m2h) with 2M NaCl as draw solution. Our results demonstrate the feasibility of using aquaporin proteins in biomimetic membranes for technological applications....

  17. Plant aquaporins: roles in plant physiology.

    Science.gov (United States)

    Li, Guowei; Santoni, Véronique; Maurel, Christophe

    2014-05-01

    Aquaporins are membrane channels that facilitate the transport of water and small neutral molecules across biological membranes of most living organisms. Here, we present comprehensive insights made on plant aquaporins in recent years, pointing to their molecular and physiological specificities with respect to animal or microbial counterparts. In plants, aquaporins occur as multiple isoforms reflecting a high diversity of cellular localizations and various physiological substrates in addition to water. Of particular relevance for plants is the transport by aquaporins of dissolved gases such as carbon dioxide or metalloids such as boric or silicic acid. The mechanisms that determine the gating and subcellular localization of plant aquaporins are extensively studied. They allow aquaporin regulation in response to multiple environmental and hormonal stimuli. Thus, aquaporins play key roles in hydraulic regulation and nutrient transport in roots and leaves. They contribute to several plant growth and developmental processes such as seed germination or emergence of lateral roots. Plants with genetically altered aquaporin functions are now tested for their ability to improve plant resistance to stresses. This article is part of a Special Issue entitled Aquaporins. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Aquaporins in desert rodent physiology.

    Science.gov (United States)

    Pannabecker, Thomas L

    2015-08-01

    Desert rodents face a sizeable challenge in maintaining salt and water homeostasis due to their life in an arid environment. A number of their organ systems exhibit functional characteristics that limit water loss above that which occurs in non-desert species under similar conditions. These systems include renal, pulmonary, gastrointestinal, nasal, and skin epithelia. The desert rodent kidney preserves body water by producing a highly concentrated urine that reaches a maximum osmolality nearly three times that of the common laboratory rat. The precise mechanism by which urine is concentrated in any mammal is unknown. Insights into the process may be more apparent in species that produce highly concentrated urine. Aquaporin water channels play a fundamental role in water transport in several desert rodent organ systems. The role of aquaporins in facilitating highly effective water preservation in desert rodents is only beginning to be explored. The organ systems of desert rodents and their associated AQPs are described. © 2015 Marine Biological Laboratory.

  19. Urea transport mediated by aquaporin water channel proteins.

    Science.gov (United States)

    Li, Chunling; Wang, Weidong

    2014-01-01

    Aquaporins (AQPs) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, thirteen aquaporins have been characterized. They are distributed wildly in specific cell types in multiple organs and tissues. Each AQP channel consists of six membrane-spanning alpha-helices that have a central water-transporting pore. Four AQP monomers assemble to form tetramers, which are the functional units in the membrane. Some of AQPs also transport urea, glycerol, ammonia, hydrogen peroxide, and gas molecules. AQP-mediated osmotic water transport across epithelial plasma membranes facilitates transcellular fluid transport and thus water reabsorption. AQP-mediated urea and glycerol transport is involved in energy metabolism and epidermal hydration. AQP-mediated CO2 and NH3 transport across membrane maintains intracellular acid-base homeostasis. AQPs are also involved in the pathophysiology of a wide range of human diseases (including water disbalance in kidney and brain, neuroinflammatory disease, obesity, and cancer). Further work is required to determine whether aquaporins are viable therapeutic targets or reliable diagnostic and prognostic biomarkers.

  20. Aquaporins in salivary glands and pancreas.

    Science.gov (United States)

    Delporte, Christine

    2014-05-01

    Salivary glands and pancreas are involved in saliva secretion, pancreatic fluid secretion and insulin secretion. These functions are essential for proper oral, pancreatic and glucose homeostasis. Aquaporins are water-permeable transmembrane protein involved in the physiology of these secretory gland functions. This review gives an overview of the morphology of salivary glands and pancreas, the expression and localization of aquaporins, the secretion roles and mechanisms, the physiological roles of aquaporins, and the role of aquaporins in pathophysiological conditions. Several aquaporins are expressed in salivary glands and pancreas, and some play important physiological roles. Modulation of aquaporin expression and/or trafficking may contribute to the pathogenesis of diseases affecting salivary glands and pancreas glands such as xerostomic conditions, pancreatic insufficiencies and diabetes. Aquaporins are involved in physiological and pathophysiological processes in salivary glands and pancreas. They could represent therapeutic targets for the treatment of diseases affecting the salivary glands and pancreas. This article is part of a Special Issue entitled Aquaporins. © 2013.

  1. Astroglial redistribution of aquaporin 4 during spongy degeneration in a Canavan disease mouse model.

    Science.gov (United States)

    Clarner, Tim; Wieczorek, Nicola; Krauspe, Barbara; Jansen, Katharina; Beyer, Cordian; Kipp, Markus

    2014-05-01

    Canavan disease is a spongiform leukodystrophy caused by an autosomal recessive mutation in the aspartoacylase gene. Deficiency of oligodendroglial aspartoacylase activity and a subsequent increase of its substrate N-acetylaspartate are the etiologic factors for the disease. N-acetylaspartate acts as a molecular water pump. Therefore, an osmotic-hydrostatic mechanism is thought to be involved in the development of the Canavan disease phenotype. Astrocytes express water transporters and are critically involved in regulating and maintaining water homeostasis in the brain. We used the ASPA(Nur7/Nur7) mouse model of Canavan disease to investigate whether a disturbance of water homeostasis might be involved in the disease's progression. Animals showed an age-dependent impairment of motor performance and spongy degeneration in various brain regions, among the basal ganglia, brain stem, and cerebellar white matter. Astrocyte activation was prominent in regions which displayed less tissue damage, such as the corpus callosum, cortex, mesencephalon, and stratum Purkinje of cerebellar lobe IV. Immunohistochemistry revealed alterations in the cellular distribution of the water channel aquaporin 4 in astrocytes of ASPA(Nur7/Nur7) mice. In control animals, aquaporin 4 was located exclusively in the astrocytic end feet. In contrast, in ASPA(Nur7/Nur7) mice, aquaporin 4 was located throughout the cytoplasm. These results indicate that astroglial regulation of water homeostasis might be involved in the partial prevention of spongy degeneration. These observations highlight aquaporin 4 as a potential therapeutic target for Canavan disease.

  2. Ammonia and urea permeability of mammalian aquaporins

    DEFF Research Database (Denmark)

    Litman, Thomas; Søgaard, Rikke; Zeuthen, Thomas

    2009-01-01

    The human aquaporins,AQP3,AQP7, AQP8,AQP9, and possibly AQP10, are permeable to ammonia, and AQP7, AQP9, and possibly AQP3, are permeable to urea. In humans, these aquaporins supplement the ammonia transport of the Rhesus (Rh) proteins and the urea transporters (UTs). The mechanism by which...... and 9 are found together with Rh proteins in cells exposed to portal blood coming from the intestine. In the kidney, AQP3 might participate in the excretion of NH(4) (+) in the collecting duct. The interplay between the ammonia-permeable aquaporins and the other types of ammonia- and urea...

  3. Expression of aquaporins and vasopressin type 2 receptor in the stria vascularis of the cochlea.

    Science.gov (United States)

    Nishioka, R; Takeda, T; Kakigi, A; Okada, T; Takebayashi, S; Taguchi, D; Nishimura, M; Hyodo, M

    2010-02-01

    Recently, considerable evidence has been accumulated to support the novel view that water homeostasis in the inner ear is regulated via the vasopressin-aquaporin 2 (VP-AQP2) system in the same fashion as in the kidney. Indeed, multiple subtypes of AQPs including AQP-2 are reported to be expressed in the cochlea. However, the mechanism that underlies VP-AQP-2 mediated water homeostasis remains to be elucidated. In the present study, the localizations of AQP-1, -2, -3, -4, -5, -7, -8, -9, and vasopressin type 2 receptor (V2-R) in the stria vascularis (SV) were molecular biologically and immunohistochemically examined to evaluate the role of the AQP water channel system in water homeostasis of the SV. A RT-PCR study revealed that AQPs and V2-R mRNA are expressed in the cochlea. As for their immunohistochemical localization, the AQP-2 protein is expressed on the basal side of the basal cells of the SV, and proteins of AQP-3 and V2-R are expressed on the apical side of the basal cells. AQP-7 and -9 proteins are expressed on the apical side of marginal cells. AQP-4, -5, and -8 protein expressions could not be detected in the lateral wall of the cochlea. From the present results, water flux in the SV is thought to be regulated at the level of the basal cells by vasopressin. Furthermore, such a distribution of AQP-2, -3, and V2-R suggests that VP-AQP-2 mediated water transport might work actively in the basal cells from perilymph towards endolymph containing AQP-1, -7 and -9. Copyright 2009 Elsevier B.V. All rights reserved.

  4. Aquaporin 4 as a NH3 Channel

    National Research Council Canada - National Science Library

    Assentoft, Mette; Kaptan, Shreyas; Schneider, Hans-Peter; Deitmer, Joachim W; de Groot, Bert L; MacAulay, Nanna

    2016-01-01

    .... The molecular paths of ammonia permeation across plasma membranes remain ill-defined, but the structural similarity of water and NH3 has pointed to the aquaporins as putative NH3-permeable pores...

  5. Altered expression of aquaporins 1 and 4 coincides with neurodegenerative events in retinas of spontaneously diabetic Torii rats.

    Science.gov (United States)

    Fukuda, Masahide; Nakanishi, Yoriko; Fuse, Masanori; Yokoi, Norihide; Hamada, Yasuhiro; Fukagawa, Masafumi; Negi, Akira; Nakamura, Makoto

    2010-01-01

    Evidence is mounting that not only microangiopathy, but also neurodegenerative events occur in the retinas of humans and rodents with early diabetes. Diverse pathologies are known to alter the amount and/or location of glial expression of the water-selective channels aquaporins (AQPs) 1 and 4. However, the temporal relationships among glial activation, the altered expression of the AQP proteins and neuronal death in the retinas of diabetic animals remains to be investigated. Male spontaneously diabetic Torii (SDT) rats reportedly develop diabetes by 40 weeks of age at the latest and manifest proliferative diabetic retinopathy at 50 weeks or later. This study compared temporal changes in neuroretinal apoptosis, glial fibrillary acidic protein (GFAP) expression and the expression of AQPs 1 and 4 between SDT rat retinas and age-matched Sprague-Dawley (SD) rat retinas. Cell death was detected by terminal deoxynucleotidyl transferase-mediated deoxy-uridine triphosphate nick end-labeling on retinal flatmounts and activated caspase 3 immunofluorescence of retinal cryosections. The expression of GFAP and AQPs 1 and 4 was assessed by immunohistochemistry of cryosections and retinal flatmounts. Diabetes started to develop around 15 weeks in SDT rats. Apoptotic cells in the ganglion cell layer and the inner nuclear layer were significantly more numerous in 40-week-old SDT rat retinas than in either age-matched SD rat retinas or 10-week-old SDT rats. GFAP immunoreactivity was confined to the nerve fiber layer both in SD and SDT rats at 10 weeks, whereas it spanned the whole retina in SDT rats, but not in SD rats, at 40 weeks. AQP1 was expressed in the outer retina, whereas AQP4 was expressed in the perivascular and end feet of Müller cells and astrocytes in the inner retina in the control SD rats and the SDT rats at 10 weeks. The perivascular AQPs shifted from AQP4 to AQP1 in 40-week-old SDT rats that exhibited marked hyperglycemia. Thus, the development of diabetes increases

  6. Distinct brain imaging characteristics of autoantibody-mediated CNS conditions and multiple sclerosis.

    Science.gov (United States)

    Jurynczyk, Maciej; Geraldes, Ruth; Probert, Fay; Woodhall, Mark R; Waters, Patrick; Tackley, George; DeLuca, Gabriele; Chandratre, Saleel; Leite, Maria I; Vincent, Angela; Palace, Jacqueline

    2017-03-01

    Brain imaging characteristics of MOG antibody disease are largely unknown and it is unclear whether they differ from those of multiple sclerosis and AQP4 antibody disease. The aim of this study was to identify brain imaging discriminators between those three inflammatory central nervous system diseases in adults and children to support diagnostic decisions, drive antibody testing and generate disease mechanism hypotheses. Clinical brain scans of 83 patients with brain lesions (67 in the training and 16 in the validation cohort, 65 adults and 18 children) with MOG antibody (n = 26), AQP4 antibody disease (n = 26) and multiple sclerosis (n = 31) recruited from Oxford neuromyelitis optica and multiple sclerosis clinical services were retrospectively and anonymously scored on a set of 29 predefined magnetic resonance imaging features by two independent raters. Principal component analysis was used to perform an overview of patients without a priori knowledge of the diagnosis. Orthogonal partial least squares discriminant analysis was used to build models separating diagnostic groups and identify best classifiers, which were then tested on an independent cohort set. Adults and children with MOG antibody disease frequently had fluffy brainstem lesions, often located in pons and/or adjacent to fourth ventricle. Children across all conditions showed more frequent bilateral, large, brainstem and deep grey matter lesions. MOG antibody disease spontaneously separated from multiple sclerosis but overlapped with AQP4 antibody disease. Multiple sclerosis was discriminated from MOG antibody disease and from AQP4 antibody disease with high predictive values, while MOG antibody disease could not be accurately discriminated from AQP4 antibody disease. Best classifiers between MOG antibody disease and multiple sclerosis were similar in adults and children, and included ovoid lesions adjacent to the body of lateral ventricles, Dawson's fingers, T1 hypointense lesions (multiple

  7. The expression of aquaporin 8 and aquaporin 9 in fetal membranes and placenta in term pregnancies complicated by idiopathic polyhydramnios.

    Science.gov (United States)

    Zhu, Xueqiong; Jiang, Shanshan; Hu, Yingchun; Zheng, Xiaoqun; Zou, Shuangwei; Wang, Yuhuan; Zhu, Xuejie

    2010-10-01

    Aquaporins are a family of membrane-bound water channel proteins that regulate the flow of water across a variety of biological membranes. The expression of aquaporin 8 and aquaporin 9 has been demonstrated in human chorioamniotic membrane and placenta. But their roles in the pathophysiology of polyhydramnios are unclear. To study the expression of aquaporin 8 and aquaporin 9 in fetal membranes and placenta in term pregnancies complicated by idiopathic polyhydramnios and to explore the association between aquaporin expressions and polyhydramnios. The placentas were collected from 51 patients who underwent elective Cesarean sections at term, of which 21 cases had idiopathic polyhydramnios and the other 30 had normal amniotic fluid volume. Real-time polymerase chain reaction and immunohistochemistry techniques were used to determine the expression and localization of aquaporin 8 and aquaporin 9 in the amnion, chorion and placenta. Expression of aquaporin 8 and aquaporin 9 was detected in the amnion, chorion and placenta and located in amnion epithelia, chorion cytotrophoblasts and placental trophoblast. Compared to normal amniotic fluid volume group, the expression of aquaporin 8 in amnion, and aquaporin 9 in amnion and chorion, were significantly increased in idiopathic polyhydramnios group; however, their expression in the placenta was significantly decreased. When polyhydramnios occurs, expression of aquaporin 8 and aquaporin 9 in fetal membranes and placenta is an adaptive change, which may be involved in the regulation of amniotic fluid volume. However, the modulation factors of the aquaporin 8 and aquaporin 9 expressions need further study. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  8. Aquaporin-4 autoantibody: a neurogenic cause of anorexia and weight loss.

    Science.gov (United States)

    Fung, Eva Lai-Wah; Tsung, Lilian Li-Yan; Dale, Russell C

    2012-01-01

    Neuromyelitis optica (NMO) is a severe inflammatory demyelinating disease often associated with a highly specific autoantibody, aquaporin-4 antibody. Although the classic syndrome involves the optic nerves and spinal cord, aquaporin-4 antibody has been important in defining the true spectrum of NMO, which now includes brain lesions in areas of high aquaporin-4 expression. Brainstem involvement, specifically area postrema involvement in the medulla, has been associated with intractable vomiting in some patients with NMO. We describe a 14-year-old female with positive aquaporin-4 antibody whose clinical course was dominated by severe anorexia with associated weight loss (from 68-41kg; body mass index 25.2-15.6). Magnetic resonance imaging showed lesions in the medulla, pons, and thalami. Although she had asymptomatic radiological longitudinally extensive transverse myelitis, she never had symptoms or signs referable to the spinal cord or the optic nerves. We propose that anorexia and weight loss should be considered part of the NMO spectrum, probably related to area postrema involvement. © The Authors. Developmental Medicine & Child Neurology © 2011 Mac Keith Press.

  9. Pollen Aquaporins: The Solute Factor.

    Science.gov (United States)

    Pérez Di Giorgio, Juliana A; Soto, Gabriela C; Muschietti, Jorge P; Amodeo, Gabriela

    2016-01-01

    In the recent years, the biophysical properties and presumed physiological role of aquaporins (AQPs) have been expanded to specialized cells where water and solute exchange are crucial traits. Complex but unique processes such as stomatal movement or pollen hydration and germination have been addressed not only by identifying the specific AQP involved but also by studying how these proteins integrate and coordinate cellular activities and functions. In this review, we referred specifically to pollen-specific AQPs and analyzed what has been assumed in terms of transport properties and what has been found in terms of their physiological role. Unlike that in many other cells, the AQP machinery in mature pollen lacks plasma membrane intrinsic proteins, which are extensively studied for their high water capacity exchange. Instead, a variety of TIPs and NIPs are expressed in pollen. These findings have altered the initial understanding of AQPs and water exchange to consider specific and diverse solutes that might be critical to sustaining pollen's success. The spatial and temporal distribution of the pollen AQPs also reflects a regulatory mechanism that allowing a properly adjusting water and solute exchange.

  10. Aquaporin mediated water flux as a target for diuretic development.

    Science.gov (United States)

    Laski, M E; Pressley, T A

    1999-11-01

    Within the past decade an entire family of membrane proteins--aquaporins--which function as transmembrane water channels has been identified; they occur throughout the plant, animal, and bacterial kingdoms. Several family members permit glycerol and urea permeability. Most aquaporins are inhibited by mercury. Constitutively expressed aquaporin 1 is the major permeability channel of the proximal tubule, descending thin limb of the loop of Henle, and it is also found in vasa recta. Aquaporin 2 is expressed in the principal cells of the collecting duct where it shuttles between intracellular vesicles and the apical membrane in response to vasopressin. Aquaporin 2 mutations cause nephrogenic diabetes insipidus; increased aquaporin 2 activity is implicated in the pathophysiology of heart failure, cirrhosis, and nephrotic syndrome. Aquaporins 3 and 4 provide basolateral membrane water channels in the collecting duct. These 4 channels and 6 others are also found elsewhere throughout the body. The physiological importance of several of the channels remains unknown. Aquaporin 1 inhibitors might induce useful diuresis, but humans who lack aquaporin 1 have no significant clinical disease. Inhibition of aquaporin 2 activity by vasopressin receptor antagonists may be useful in heart failure, cirrhosis, nephrotic syndrome, and the syndrome of inappropriate antidiuretic hormone (ADH) release.

  11. Effects of gonadectomy and testosterone treatment on aquaporin expression in the kidney of normotensive and hypertensive rats.

    Science.gov (United States)

    Loh, Su Yi; Giribabu, Nelli; Salleh, Naguib

    2017-07-01

    We tested the hypothesis that testosterone-induced increase in blood pressure was due to changes in aquaporin (AQP) expression in kidneys. In this study, expression level of kidney AQPs was investigated under testosterone influence. Adult normotensive Wistar Kyoto (WKY) and hypertensive SHR male and female rats underwent gonadectomy. For female rats, testosterone was given for six weeks duration, two weeks following ovariectomy via subcutaneous silastic implant. Mean arterial pressure (MAP) was measured in all the rats after eight weeks via carotid artery cannulation and the rats were then sacrificed and kidneys were harvested for analyses of AQP-1, 2, 3, 4, 6, and 7 mRNA and protein expressions by quantitative real-time PCR and Western blotting, respectively. Distribution of AQP subunits' protein in kidneys was observed by immunofluorescence. In male WKY rats, MAP, AQP-1, 2, 4, and 7 protein; and mRNA expression decreased however AQP-3 protein and mRNA expression increased following orchidectomy. The vice versa effects were observed in testosterone-treated ovariectomized female WKY rats. However, no changes in AQP-6 expression were observed. Meanwhile, in adult male SHR rats, MAP and expression level of all AQP subunits decreased following orchidectomy. The opposite effects were seen in ovariectomized female SHR rats following testosterone treatment. Immunofluorescence study showed AQP-1 and AQP-7 were distributed in the proximal convoluted tubules (PCT) while AQP-2, AQP-4, and AQP-6 were distributed in the collecting ducts (CDs). AQP-3 was distributed in the PCT and CD. In conclusion, changes in AQP subunit expression in kidneys could explain changes in blood pressure under testosterone influence. Impact statement This study provides fundamental understanding on the mechanisms underlying testosterone-induced increase in blood pressure which involve regulation of aquaporin channel subunits in the kidneys. A better understanding of this issue can help to explain

  12. Aquaporins in Salivary Glands: From Basic Research to Clinical Applications.

    Science.gov (United States)

    Delporte, Christine; Bryla, Angélic; Perret, Jason

    2016-01-27

    Salivary glands are involved in saliva secretion that ensures proper oral health. Aquaporins are expressed in salivary glands and play a major role in saliva secretion. This review will provide an overview of the salivary gland morphology and physiology of saliva secretion, and focus on the expression, subcellular localization and role of aquaporins under physiological and pathophysiological conditions, as well as clinical applications involving aquaporins. This review is highlighting expression and localization of aquaporins in human, rat and mouse, the most studied species and is pointing out possible difference between major salivary glands, i.e., parotid, submandibular and sublingual glands.

  13. Aquaporins in Salivary Glands: From Basic Research to Clinical Applications

    Directory of Open Access Journals (Sweden)

    Christine Delporte

    2016-01-01

    Full Text Available Salivary glands are involved in saliva secretion that ensures proper oral health. Aquaporins are expressed in salivary glands and play a major role in saliva secretion. This review will provide an overview of the salivary gland morphology and physiology of saliva secretion, and focus on the expression, subcellular localization and role of aquaporins under physiological and pathophysiological conditions, as well as clinical applications involving aquaporins. This review is highlighting expression and localization of aquaporins in human, rat and mouse, the most studied species and is pointing out possible difference between major salivary glands, i.e., parotid, submandibular and sublingual glands.

  14. Aquaporin-2 regulation in health and disease

    DEFF Research Database (Denmark)

    Radin, M J; Yu, Ming-Jiun; Stødkilde-Jørgensen, Lene

    2012-01-01

    Aquaporin-2 (AQP2), the vasopressin-regulated water channel of the renal collecting duct, is dysregulated in numerous disorders of water balance in people and animals, including those associated with polyuria (urinary tract obstruction, hypokalemia, inflammation, and lithium toxicity) and with di......Aquaporin-2 (AQP2), the vasopressin-regulated water channel of the renal collecting duct, is dysregulated in numerous disorders of water balance in people and animals, including those associated with polyuria (urinary tract obstruction, hypokalemia, inflammation, and lithium toxicity...... several transcription factor-binding elements in the 5′ flanking region of the AQP2 gene have been identified, and candidate transcription factors corresponding to these elements have been discovered in proteomics studies. Here, we review progress in this area and discuss elements of vasopressin signaling...

  15. Aquaporin-4-autoimmunity in patients with systemic lupus erythematosus

    DEFF Research Database (Denmark)

    Asgari, Nasrin; Jarius, Sven; Laustrup, Helle

    2018-01-01

    to antibody-mediated autoimmune disease. OBJECTIVE: To estimate the prevalence of NMOSD in SLE and investigate the immunogenetic background for an association of NMOSD and SLE. METHODS: The study included a predominantly population-based cohort with clinical and serological investigations of 208 patients......G and other autoantibodies, including myelin oligodendrocyte glycoprotein (MOG), was determined blinded to clinical diagnosis. RESULTS: Of 208 patients with SLE, 45(22%) had neuropsychiatric (NP) SLE, and CNS involvement predominated in 30 of 45 (67%) patients. Serum AQP4-IgG was detected in 2 of 30 (6...

  16. Fungal aquaporins: cellular functions and ecophysiological perspectives.

    Science.gov (United States)

    Nehls, Uwe; Dietz, Sandra

    2014-11-01

    Three aspects have to be taken into consideration when discussing cellular water and solute permeability of fungal cells: cell wall properties, membrane permeability, and transport through proteinaceous pores (the main focus of this review). Yet, characterized major intrinsic proteins (MIPs) can be grouped into three functional categories: (mainly) water transporting aquaporins, aquaglyceroporins that confer preferentially solute permeability (e.g., glycerol and ammonia), and bifunctional aquaglyceroporins that can facilitate efficient water and solute transfer. Two ancestor proteins, a water (orthodox aquaporin) and a solute facilitator (aquaglyceroporin), are supposed to give rise to today's MIPs. Based on primary sequences of fungal MIPs, orthodox aquaporins/X-intrinsic proteins (XIPs) and FPS1-like/Yfl054-like/other aquaglyceroporins are supposed to be respective sister groups. However, at least within the fungal kingdom, no easy functional conclusion can be drawn from the phylogenetic position of a given protein within the MIP pedigree. In consequence, ecophysiological prediction of MIP relevance is not feasible without detailed functional analysis of the respective protein and expression studies. To illuminate the diverse MIP implications in fungal lifestyle, our current knowledge about protein function in two organisms, baker's yeast and the Basidiomycotic Laccaria bicolor, an ectomycorrhizal model fungus, was exemplarily summarized in this review. MIP function has been investigated in such a depth in Saccharomyces cerevisiae that a system-wide view is possible. Yeast lifestyle, however, is special in many circumstances. Therefore, L. bicolor as filamentous Basidiomycete was added and allows insight into a very different way of life. Special emphasis was laid in this review onto ecophysiological interpretation of MIP function.

  17. Biomimetic aquaporin membranes coming of age

    DEFF Research Database (Denmark)

    Tang, Chuyang; Wang, Zhining; Petrinić, Irena

    2015-01-01

    Membrane processes have been widely used for water purification because of their high stability, efficiency, low energy requirement and ease of operation. Traditional desalting membranes are mostly dense polymeric films with a "trade off" effect between permeability and selectivity. Biological...... membranes, on the other hand, can perform transport in some cases with exceptional flux and rejection properties. In particular the discovery of selective water channel proteins - aquaporins - has prompted interest in using these proteins as building blocks for new types of membranes. The major challenge...

  18. Aquaporins and membrane diffusion of CO2 in living organisms.

    Science.gov (United States)

    Kaldenhoff, Ralf; Kai, Lei; Uehlein, Norbert

    2014-05-01

    Determination of CO2 diffusion rates in living cells revealed inconsistencies with existing models about the mechanisms of membrane gas transport. Mainly, these discrepancies exist in the determined CO2 diffusion rates of bio-membranes, which were orders of magnitudes below those for pure lipid bilayers or theoretical considerations as well as in the observation that membrane insertion of specific aquaporins was rescuing high CO2 transport rates. This effect was confirmed by functional aquaporin protein analysis in heterologous expression systems as well as in bacteria, plants and partly in mammals. This review summarizes the arguments in favor of and against aquaporin facilitated membrane diffusion of CO2 and reports about its importance for the physiology of living organisms. Most likely, the aquaporin tetramer forming an additional fifth pore is required for CO2 diffusion facilitation. Aquaporin tetramer formation, membrane integration and disintegration could provide a mechanism for regulation of cellular CO2 exchange. The physiological importance of aquaporin mediated CO2 membrane diffusion could be shown for plants and cyanobacteria and partly for mammals. Taking the mentioned results into account, consequences for our current picture of cell membrane transport emerge. It appears that in some or many instances, membranes might not be as permeable as it was suggested by current bio-membrane models, opening an additional way of controlling the cellular influx or efflux of volatile substances like CO2. This article is part of a Special Issue entitled Aquaporins. © 2013.

  19. Anti-aquaporin 4 antibody-positive acute disseminated encephalomyelitis.

    Science.gov (United States)

    Okumura, Akihisa; Nakazawa, Mika; Igarashi, Ayuko; Abe, Shinpei; Ikeno, Mitsuru; Nakahara, Eri; Yamashiro, Yuichiro; Shimizu, Toshiaki; Takahashi, Toshiyuki

    2015-03-01

    To describe the clinical and neuroimaging features of a young female patient with acute disseminated encephalomyelitis associated with anti-aquaporin-4 antibodies. The patient had mild encephalopathy 14 days after influenza vaccination. Cerebrospinal fluid analysis revealed an increased cell count and a marked increase in myelin basic protein. Magnetic resonance imaging (MRI) demonstrated multiple lesions in the juxtacortical white matter. The patient was diagnosed with acute disseminated encephalomyelitis and treated with methylprednisolone pulse therapy. She recovered in 1 month. However, right retrobulbar optic neuritis appeared 2 months after discharge, and serum anti-aquaporin 4 antibodies were measured with a cell-based assay. Anti-aquaporin 4 antibodies were present in the patient's serum. She was treated with a prolonged course of oral prednisolone. The patient was negative for serum anti-aquaporin 4 antibodies 8 months after the second clinical event, and prednisolone was discontinued 13 months after the second clinical event. Serum anti-aquaporin 4 antibodies remained negative 4 months after the discontinuation of prednisolone. There was no evidence of relapse at 9 months after discontinuation of steroids. This case will expand the spectrum of anti-aquaporin-4 antibody-related central nervous system disorders. The measurement of anti-aquaporin 4 antibody may be considered in patients with a clinical diagnosis of acute disseminated encephalomyelitis and a second clinical event within a short interval. Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  20. Small-Molecule Screening Identifies Modulators of Aquaporin-2 Trafficking

    Science.gov (United States)

    Bogum, Jana; Faust, Dörte; Zühlke, Kerstin; Eichhorst, Jenny; Moutty, Marie C.; Furkert, Jens; Eldahshan, Adeeb; Neuenschwander, Martin; von Kries, Jens Peter; Wiesner, Burkhard; Trimpert, Christiane; Deen, Peter M.T.; Valenti, Giovanna; Rosenthal, Walter

    2013-01-01

    In the principal cells of the renal collecting duct, arginine vasopressin (AVP) stimulates the synthesis of cAMP, leading to signaling events that culminate in the phosphorylation of aquaporin-2 water channels and their redistribution from intracellular domains to the plasma membrane via vesicular trafficking. The molecular mechanisms that control aquaporin-2 trafficking and the consequent water reabsorption, however, are not completely understood. Here, we used a cell-based assay and automated immunofluorescence microscopy to screen 17,700 small molecules for inhibitors of the cAMP-dependent redistribution of aquaporin-2. This approach identified 17 inhibitors, including 4-acetyldiphyllin, a selective blocker of vacuolar H+-ATPase that increases the pH of intracellular vesicles and causes accumulation of aquaporin-2 in the Golgi compartment. Although 4-acetyldiphyllin did not inhibit forskolin-induced increases in cAMP formation and downstream activation of protein kinase A (PKA), it did prevent cAMP/PKA-dependent phosphorylation at serine 256 of aquaporin-2, which triggers the redistribution to the plasma membrane. It did not, however, prevent cAMP-induced changes to the phosphorylation status at serines 261 or 269. Last, we identified the fungicide fluconazole as an inhibitor of cAMP-mediated redistribution of aquaporin-2, but its target in this pathway remains unknown. In conclusion, our screening approach provides a method to begin dissecting molecular mechanisms underlying AVP-mediated water reabsorption, evidenced by our identification of 4-acetyldiphyllin as a modulator of aquaporin-2 trafficking. PMID:23559583

  1. Regulation and Function of Aquaporin-1 in Glioma Cells

    Directory of Open Access Journals (Sweden)

    Yasuhiko Hayashi

    2007-09-01

    Full Text Available Glioblastoma multiformes (GBMs express increased aquaporin (AQP 1 compared to normal brain. AQPs may contribute to edema, cell motility, shuttling of H2O and H+ from intracellular to extracellular space. We sought to gain insight into AQPs function in GBM. In cultured 9L gliosarcoma cells, AQPs expression was induced by dexamethasone, platelet-derived growth factor, NaCl, hypoxia, D-glucose (but not L-glucose, fructose. Induction of AQPs expression correlated with the level of glycolysis, maximized by increasing medium D-glucose or fructose and decreasing O2, was quantified by measuring lactate dehydrogenase (LDH activity and medium lactate concentration. Upregulation of the protease cathepsin B was also observed in 9L cells cultured under glycolytic conditions. Immunohistochemical staining of human GBM specimens revealed increased coincident expression of AQPs, LDH, cathepsin B in glioma cells associated with blood vessels at the tumor periphery. GBMs are known to exhibit aerobic glycolysis. Increased glucose metabolism at the tumor periphery may provide a scenario by which upregulation of AQPs, LDH, cathepsin B contributes to acidification of the extracellular milieu and to invasive potential of glioma cells in perivascular space. The specific upregulation and metabolic consequences of increased AQPs in gliomas may provide a therapeutic target, both as a cell surface marker and as a functional intervention.

  2. Polyphenols as Modulators of Aquaporin Family in Health and Disease

    Directory of Open Access Journals (Sweden)

    Diana Fiorentini

    2015-01-01

    Full Text Available Polyphenols are bioactive molecules widely distributed in fruits, vegetables, cereals, and beverages. Polyphenols in food sources are extensively studied for their role in the maintenance of human health and in the protection against development of chronic/degenerative diseases. Polyphenols act mainly as antioxidant molecules, protecting cell constituents against oxidative damage. The enormous number of polyphenolic compounds leads to huge different mechanisms of action not fully understood. Recently, some evidence is emerging about the role of polyphenols, such as curcumin, pinocembrin, resveratrol, and quercetin, in modulating the activity of some aquaporin (AQP isoforms. AQPs are integral, small hydrophobic water channel proteins, extensively expressed in many organs and tissues, whose major function is to facilitate the transport of water or glycerol over cell plasma membranes. Here we summarize AQP physiological functions and report emerging evidence on the implication of these proteins in a number of pathophysiological processes. In particular, this review offers an overview about the role of AQPs in brain, eye, skin diseases, and metabolic syndrome, focusing on the ability of polyphenols to modulate AQP expression. This original analysis can contribute to elucidating some peculiar effects exerted by polyphenols and can lead to the development of an innovative potential preventive/therapeutic strategy.

  3. Elevated cAMP increases aquaporin-3 plasma membrane diffusion

    DEFF Research Database (Denmark)

    Marlar, Saw; Christensen, Eva Arnspang; Koffman, Jennifer Skaarup

    2014-01-01

    Regulated urine concentration takes place in the renal collecting duct upon arginine vasopressin (AVP) stimulation, where subapical vesicles containing aquaporin-2 (AQP2) are inserted into the apical membrane instantly increasing water reabsorption and urine concentration. The reabsorped water ex...

  4. Desalination by biomimetic aquaporin membranes: Review of status and prospects

    DEFF Research Database (Denmark)

    Tang, C.Y.; Zhao, Y.; Wang, R.

    2013-01-01

    Based on their unique combination of offering high water permeability and high solute rejection aquaporin proteins have attracted considerable interest over the last years as functional building blocks of biomimetic membranes for water desalination and reuse. The purpose of this review is to prov......Based on their unique combination of offering high water permeability and high solute rejection aquaporin proteins have attracted considerable interest over the last years as functional building blocks of biomimetic membranes for water desalination and reuse. The purpose of this review......; including an overview of our own recent developments in aquaporin-based membranes. Finally we outline future prospects of aquaporin based biomimetic membrane for desalination and water reuse....

  5. Plant aquaporins: multifunctional water and solute channels with expanding roles.

    Science.gov (United States)

    Tyerman, S. D.; Niemietz, C. M.; Bramley, H.

    2002-02-01

    There is strong evidence that aquaporins are central components in plant water relations. Plant species possess more aquaporin genes than species from other kingdoms. According to sequence similarities, four major groups have been identified, which can be further divided into subgroups that may correspond to localization and transport selectivity. They may be involved in compatible solute distribution, gas-transfer (CO2, NH3) as well as in micronutrient uptake (boric acid). Recent advances in determining the structure of some aquaporins gives further details on the mechanism of selectivity. Gating behaviour of aquaporins is poorly understood but evidence is mounting that phosphorylation, pH, pCa and osmotic gradients can affect water channel activity. Aquaporins are enriched in zones of fast cell division and expansion, or in areas where water flow or solute flux density would be expected to be high. This includes biotrophic interfaces between plants and parasites, between plants and symbiotic bacteria or fungi, and between germinating pollen and stigma. On a cellular level aquaporin clusters have been identified in some membranes. There is also a possibility that aquaporins in the endoplasmic reticulum may function in symplasmic transport if water can flow from cell to cell via the desmotubules in plasmodesmata. Functional characterization of aquaporins in the native membrane has raised doubt about the conclusiveness of expression patterns alone and need to be conducted in parallel. The challenge will be to elucidate gating on a molecular level and cellular level and to tie those findings into plant water relations on a macroscopic scale where various flow pathways need to be considered.

  6. Auxin regulates aquaporin function to facilitate lateral root emergence.

    Science.gov (United States)

    Péret, Benjamin; Li, Guowei; Zhao, Jin; Band, Leah R; Voß, Ute; Postaire, Olivier; Luu, Doan-Trung; Da Ines, Olivier; Casimiro, Ilda; Lucas, Mikaël; Wells, Darren M; Lazzerini, Laure; Nacry, Philippe; King, John R; Jensen, Oliver E; Schäffner, Anton R; Maurel, Christophe; Bennett, Malcolm J

    2012-10-01

    Aquaporins are membrane channels that facilitate water movement across cell membranes. In plants, aquaporins contribute to water relations. Here, we establish a new link between aquaporin-dependent tissue hydraulics and auxin-regulated root development in Arabidopsis thaliana. We report that most aquaporin genes are repressed during lateral root formation and by exogenous auxin treatment. Auxin reduces root hydraulic conductivity both at the cell and whole-organ levels. The highly expressed aquaporin PIP2;1 is progressively excluded from the site of the auxin response maximum in lateral root primordia (LRP) whilst being maintained at their base and underlying vascular tissues. Modelling predicts that the positive and negative perturbations of PIP2;1 expression alter water flow into LRP, thereby slowing lateral root emergence (LRE). Consistent with this mechanism, pip2;1 mutants and PIP2;1-overexpressing lines exhibit delayed LRE. We conclude that auxin promotes LRE by regulating the spatial and temporal distribution of aquaporin-dependent root tissue water transport.

  7. Glutathionylation of the Aquaporin-2 Water Channel

    Science.gov (United States)

    Tamma, Grazia; Ranieri, Marianna; Di Mise, Annarita; Centrone, Mariangela; Svelto, Maria; Valenti, Giovanna

    2014-01-01

    Aquaporin-2 (AQP2) is the vasopressin-regulated water channel that controls renal water reabsorption and urine concentration. AQP2 undergoes different regulated post-translational modifications, including phosphorylation and ubiquitylation, which are fundamental for controlling AQP2 cellular localization, stability, and function. The relationship between AQP2 and S-glutathionylation is of potential interest because reactive oxygen species (ROS), produced under renal failure or nephrotoxic drugs, may influence renal function as well as the expression and the activity of different transporters and channels, including aquaporins. Here, we show for the first time that AQP2 is subjected to S-glutathionylation in kidney and in HEK-293 cells stably expressing AQP2. S-Glutathionylation is a redox-dependent post-translational modification controlling several signal transduction pathways and displaying an acute effect on free cytosolic calcium concentration. Interestingly, we found that in fresh kidney slices, the increased AQP2 S-glutathionylation correlated with tert-butyl hydroperoxide-induced ROS generation. Moreover, we also found that cells expressing wild-type human calcium-sensing receptor (hCaSR-wt) and its gain of function (hCaSR-R990G; hCaSR-N124K) had a significant decrease in AQP2 S-glutathionylation secondary to reduced ROS levels and reduced basal intracellular calcium concentration compared with mock cells. Together, these new findings provide fundamental insight into cell biological aspects of AQP2 function and may be relevant to better understand and explain pathological states characterized by an oxidative stress and AQP2-dependent water reabsorption disturbs. PMID:25112872

  8. Disruption of the leptomeningeal blood barrier in neuromyelitis optica spectrum disorder

    DEFF Research Database (Denmark)

    Asgari, Nasrin; Flanagan, Eoin P.; Fujihara, Kazuo

    2017-01-01

    Objective: To describe leptomeningeal blood-barrier impairment reflected by MRI gadoliniumenhanced lesions in patients with aquaporin-4 immunoglobulin G (AQP4-IgG)-positive neuromyelitis optica spectrum disorder (NMOSD). Methods: A retrospective case series of 11 AQP4-IgG-positive NMOSD patients...... with leptomeningeal enhancement (LME) were collected from 5 centers. External neuroradiologists, blinded to the clinical details, evaluated MRIs. Results: LME was demonstrated on postcontrast T1-weighted and fluid-attenuated inversion recovery images as a sign of leptomeningeal blood-barrier disruption and transient....... Conclusion: This study suggests that altered leptomeningeal blood barrier may be accompanied by intraparenchymal blood-brain barrier breakdown in patientswith AQP4-IgG-positive NMOSD during relapses....

  9. Rhipicephalus (Boophilus) microplus aquaporin as an effective vaccine antigen to protect against cattle tick infestations

    Science.gov (United States)

    A cDNA encoding an aquaporin from the cattle tick, Rhipicephalus microplus, was isolated from transcriptomic studies. Bioinformatic analysis indicates this aquaporin, designated RmAQP1, shows greatest amino acid similarity to the human aquaporin 7 family. Members of this family of water-conducting c...

  10. Hypothalamic abnormality in patients with inflammatory demyelinating disorders.

    Science.gov (United States)

    Gao, Cong; Wu, Linzhan; Chen, Xiaohui; Long, Youming; Zhong, Rong; Yang, Ning; Chen, Yaotang

    2016-11-01

    Hypothalamic lesions in neuromyelitis optica (NMO) patients might be more specific for NMO than multiple sclerosis (MS). However, this is controversial. To characterize clinical features of patients with inflammatory demyelinating disorders (IDDs) with visible hypothalamic lesions using magnetic resonance imaging (MRI). Patients with IDDs (n = 429) were recruited retrospectively. Of 52 patients with hypothalamic images enrolled, 42 were positive for aquaporin-4 (AQP4) antibodies, including 28 patients with NMO, 6 with recurrent transverse myelitis, 3 with recurrent optic neuritis, and 5 with brainstem and brain syndrome. The remaining 10 patients were anti-AQP4-negative, including 3 with MS, 3 with acute disseminated encephalomyelitis, and 4 with other disorders. In the AQP4-positive group, manifestations, including ataxia, intractable hiccup and nausea, syndrome of inappropriate antidiuretic hormone secretion and encephalopathy were more frequent in those with hypothalamic lesions than those without. Cell counts of cerebrospinal fluid in patients with hypothalamic lesions differed from patients without lesions. Brain MRI abnormalities were more frequent in brainstem and hemisphere of the hypothalamic lesion group. Hypothalamic lesions were observed frequently in patients with AQP4 antibodies. Clinical manifestations and paraclinical features in AQP4-positive patients with hypothalamic lesions differed from those without lesions.

  11. Hypermagnesemia does not prevent intracranial hypertension and aggravates cerebral hyperperfusion in a rat model of acute hyperammonemia

    DEFF Research Database (Denmark)

    Bjerring, Peter Nissen; Eefsen, Martin; Larsen, Fin Stolze

    2011-01-01

    Intravenous infusion of magnesium sulfate prevents seizures in patients with eclampsia and brain edema after traumatic brain injury. Neuroprotection is achieved by controlling cerebral blood flow (CBF), intracranial pressure, neuronal glutamate release, and aquaporin-4 (Aqp4) expression...... rats receiving ammonia infusion/vehicle and MgSO4) /saline. The effect of MgSO(4) on mean arterial pressure (MAP), intracranial pressure (ICP), CBF, cerebral glutamate and glutamine, and aquaporin-4 expression was studied. Finally, the effect of MgSO4 on MAP, ICP, and CBF was studied, using two...

  12. Expression Analysis of Sugarcane Aquaporin Genes under Water Deficit

    Directory of Open Access Journals (Sweden)

    Manassés Daniel da Silva

    2013-01-01

    Full Text Available The present work is a pioneer study specifically addressing the aquaporin transcripts in sugarcane transcriptomes. Representatives of the four aquaporin subfamilies (PIP, TIP, SIP, and NIP, already described for higher plants, were identified. Forty-two distinct aquaporin isoforms were expressed in four HT-SuperSAGE libraries from sugarcane roots of drought-tolerant and -sensitive genotypes, respectively. At least 10 different potential aquaporin isoform targets and their respective unitags were considered to be promising for future studies and especially for the development of molecular markers for plant breeding. From those 10 isoforms, four (SoPIP2-4, SoPIP2-6, OsPIP2-4, and SsPIP1-1 showed distinct responses towards drought, with divergent expressions between the bulks from tolerant and sensitive genotypes, when they were compared under normal and stress conditions. Two targets (SsPIP1-1 and SoPIP1-3/PIP1-4 were selected for validation via RT-qPCR and their expression patterns as detected by HT-SuperSAGE were confirmed. The employed validation strategy revealed that different genotypes share the same tolerant or sensitive phenotype, respectively, but may use different routes for stress acclimation, indicating the aquaporin transcription in sugarcane to be potentially genotype-specific.

  13. Role of Aquaporin 0 in lens biomechanics.

    Science.gov (United States)

    Sindhu Kumari, S; Gupta, Neha; Shiels, Alan; FitzGerald, Paul G; Menon, Anil G; Mathias, Richard T; Varadaraj, Kulandaiappan

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5(-/-)), AQP0 KO (heterozygous KO: AQP0(+/-); homozygous KO: AQP0(-/-); all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0(+/-) lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and together they help to confer

  14. Water permeability and characterization of aquaporin-11.

    Science.gov (United States)

    Yakata, Kaya; Tani, Kazutoshi; Fujiyoshi, Yoshinori

    2011-05-01

    The water permeability of aquaporin-11 (AQP11), which has a cysteine substituted for an alanine at a highly conserved asparagine-proline-alanine (NPA) motif in the water channel family, is controversial. Our previous study, however, showed that AQP11 is water permeable in proteoliposomes in which AQP11 molecules were reconstituted after purification with Fos-choline 10, which is the most suitable detergent available for stable solubilization of AQP11. In our previous study, we were unable to exclude the effect of the detergent on the water conductance. Therefore, in the present study, we measured the water permeability of AQP11 without detergent using vesicles that directly formed from Sf9 cell membranes expressing AQP11 molecules. The water permeability of AQP11 was 8-fold lower than that of AQP1 and 3-fold higher than that of mock-infected cell membrane, and was reversibly inhibited by mercury ions. Considering the slow but constant water permeable functions of AQP11, we performed homology modeling to search for a common structural feature. When comparing our model with those of other AQP structures, we found that Tyr83 facing the channel pore might be a key amino acid residue that decreases the water permeation of AQP11. Our findings indicate that AQP11 could be involved in slow but constant water movement across the membrane. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Recombinant Production of Human Aquaporin-1 to an Exceptional High Membrane Density in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Bomholt, Julie; Hélix-Nielsen, Claus; Scharff-Poulsen, Peter

    2013-01-01

    In the present paper we explored the capacity of yeast Saccharomyces cerevisiae as host for heterologous expression of human Aquaporin-1. Aquaporin-1 cDNA was expressed from a galactose inducible promoter situated on a plasmid with an adjustable copy number. Human Aquaporin-1 was C-terminally tag......In the present paper we explored the capacity of yeast Saccharomyces cerevisiae as host for heterologous expression of human Aquaporin-1. Aquaporin-1 cDNA was expressed from a galactose inducible promoter situated on a plasmid with an adjustable copy number. Human Aquaporin-1 was C...... at 15°C in a yeast host over-producing the Gal4p transcriptional activator and growth in amino acid supplemented minimal medium. In-gel fluorescence combined with western blotting showed that low accumulation of correctly folded recombinant Aquaporin-1 at 30°C was due to in vivo mal-folding. Reduction...

  16. Role of aquaporins during teleost gametogenesis and early embryogenesis

    Directory of Open Access Journals (Sweden)

    Francois eChauvigne

    2011-09-01

    Full Text Available Aquaporins are believed to be involved in homeosmotic mechanisms of marine teleosts. Increasing data suggest that these molecular water channels play critical roles associated with the adaptation of gametes and early embryos to the external spawning environment. In this mini-review, we discuss recent studies suggesting the function of aquaporin-mediated fluid homeostasis during spermatozoa activation and egg formation in teleosts. In addition, we address the potential role of water channels in osmosensing and cell migration during early embryonic development.

  17. Role of Aquaporin 0 in lens biomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Sindhu Kumari, S.; Gupta, Neha [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); Shiels, Alan [Washington University School of Medicine, St. Louis, MO (United States); FitzGerald, Paul G. [Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, CA (United States); Menon, Anil G. [University of Cincinnati College of Medicine, Cincinnati, OH (United States); Mathias, Richard T. [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States); Varadaraj, Kulandaiappan, E-mail: kulandaiappan.varadaraj@stonybrook.edu [Physiology and Biophysics, Stony Brook University, Stony Brook, NY (United States); SUNY Eye Institute, NY (United States)

    2015-07-10

    Maintenance of proper biomechanics of the eye lens is important for its structural integrity and for the process of accommodation to focus near and far objects. Several studies have shown that specialized cytoskeletal systems such as the beaded filament (BF) and spectrin-actin networks contribute to mammalian lens biomechanics; mutations or deletion in these proteins alters lens biomechanics. Aquaporin 0 (AQP0), which constitutes ∼45% of the total membrane proteins of lens fiber cells, has been shown to function as a water channel and a structural cell-to-cell adhesion (CTCA) protein. Our recent ex vivo study on AQP0 knockout (AQP0 KO) mouse lenses showed the CTCA function of AQP0 could be crucial for establishing the refractive index gradient. However, biomechanical studies on the role of AQP0 are lacking. The present investigation used wild type (WT), AQP5 KO (AQP5{sup −/−}), AQP0 KO (heterozygous KO: AQP0{sup +/−}; homozygous KO: AQP0{sup −/−}; all in C57BL/6J) and WT-FVB/N mouse lenses to learn more about the role of fiber cell AQPs in lens biomechanics. Electron microscopic images exhibited decreases in lens fiber cell compaction and increases in extracellular space due to deletion of even one allele of AQP0. Biomechanical assay revealed that loss of one or both alleles of AQP0 caused a significant reduction in the compressive load-bearing capacity of the lenses compared to WT lenses. Conversely, loss of AQP5 did not alter the lens load-bearing ability. Compressive load-bearing at the suture area of AQP0{sup +/−} lenses showed easy separation while WT lens suture remained intact. These data from KO mouse lenses in conjunction with previous studies on lens-specific BF proteins (CP49 and filensin) suggest that AQP0 and BF proteins could act co-operatively in establishing normal lens biomechanics. We hypothesize that AQP0, with its prolific expression at the fiber cell membrane, could provide anchorage for cytoskeletal structures like BFs and

  18. Down-regulation of aquaporins (AQP3) expression by RNA ...

    African Journals Online (AJOL)

    Aquaporins (AQPs) represent a family of homologous water channels expressed in many epithelial and endothelial cells. Most tumors have been shown to exhibit high vascular permeability and interstitial fluid pressure. Here, we tested the regulation on the expression of AQP3 by RNA interference (RNAi) in the human lung ...

  19. Aquaporin-Based Biomimetic Polymeric Membranes: Approaches and Challenges

    DEFF Research Database (Denmark)

    Habel, Joachim Erich Otto; Hansen, Michael; Kynde, Søren

    2015-01-01

    In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs...

  20. Bladder function impairment in aquaporin-2 defective nephrogenic diabetes insipidus.

    NARCIS (Netherlands)

    Shalev, H.; Romanovsky, I.; Knoers, N.V.A.M.; Lupa, S.; Landau, D.

    2004-01-01

    BACKGROUND: The aim of this study was to describe the urological complications associated with nephrogenic diabetes insipidus (NDI) due to a mutation in aquaporin-2 (AQP2), a collecting-duct protein activated by ADH signalling. METHODS: We provide a case series description of a group of seven

  1. Recombinant production of human Aquaporin-1 to an exceptional high membrane density in Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Julie Bomholt

    Full Text Available In the present paper we explored the capacity of yeast Saccharomyces cerevisiae as host for heterologous expression of human Aquaporin-1. Aquaporin-1 cDNA was expressed from a galactose inducible promoter situated on a plasmid with an adjustable copy number. Human Aquaporin-1 was C-terminally tagged with yeast enhanced GFP for quantification of functional expression, determination of sub-cellular localization, estimation of in vivo folding efficiency and establishment of a purification protocol. Aquaporin-1 was found to constitute 8.5 percent of total membrane protein content after expression at 15°C in a yeast host over-producing the Gal4p transcriptional activator and growth in amino acid supplemented minimal medium. In-gel fluorescence combined with western blotting showed that low accumulation of correctly folded recombinant Aquaporin-1 at 30°C was due to in vivo mal-folding. Reduction of the expression temperature to 15°C almost completely prevented Aquaporin-1 mal-folding. Bioimaging of live yeast cells revealed that recombinant Aquaporin-1 accumulated in the yeast plasma membrane. A detergent screen for solubilization revealed that CYMAL-5 was superior in solubilizing recombinant Aquaporin-1 and generated a monodisperse protein preparation. A single Ni-affinity chromatography step was used to obtain almost pure Aquaporin-1. Recombinant Aquaporin-1 produced in S. cerevisiae was not N-glycosylated in contrast to the protein found in human erythrocytes.

  2. Recombinant Production of Human Aquaporin-1 to an Exceptional High Membrane Density in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Bomholt, Julie; Helix Nielsen, Claus; Scharff-Poulsen, Peter

    2013-01-01

    In the present paper we explored the capacity of yeast Saccharomyces cerevisiae as host for heterologous expression of human Aquaporin-1. Aquaporin-1 cDNA was expressed from a galactose inducible promoter situated on a plasmid with an adjustable copy number. Human Aquaporin-1 was C...... at 15°C in a yeast host over-producing the Gal4p transcriptional activator and growth in amino acid supplemented minimal medium. In-gel fluorescence combined with western blotting showed that low accumulation of correctly folded recombinant Aquaporin-1 at 30°C was due to in vivo mal-folding. Reduction...... and generated a monodisperse protein preparation. A single Ni-affinity chromatography step was used to obtain almost pure Aquaporin-1. Recombinant Aquaporin-1 produced in S. cerevisiae was not N-glycosylated in contrast to the protein found in human erythrocytes....

  3. Differential expression of aquaporin-3 and aquaporin-5 in pancreatic ductal adenocarcinoma.

    Science.gov (United States)

    Direito, Inês; Paulino, Jorge; Vigia, Emanuel; Brito, Maria Alexandra; Soveral, Graça

    2017-06-01

    Aquaporin-5 (AQP5) and -3 (AQP3) are protein channels that showed to be up-regulated in a variety of tumors. Our goal was to investigate the expression pattern of AQP5 and AQP3 in pancreatic ductal adenocarcinomas (PDA) and correlate with cell proliferation, tumor stage and progression, and clinical significance. 35 PDA samples in different stages of differentiation and locations were analyzed by immunohistochemistry for expression of AQP5, AQP3 and several markers of cell proliferation and tumorigenesis. In PDA samples AQP5 was overexpressed in the apical membrane of intercalated and intralobular ductal cells while AQP3 was expressed at the plasma membrane of ductal cells. AQP5 was also found in infiltrative cancer cells in duodenum. Simultaneous overexpression of EGFR, Ki-67, and CK7, with decreased E-cad and increased Vim that characterize epithelial mesenchymal transition, tumor formation and invasion, strongly suggest AQP3 and AQP5 involvement in cell proliferation and transformation. AQP3 overexpression is reinforced in late and more aggressive PDA stages whereas AQP5 is related with tumor differentiation, suggesting it may represent a novel marker for PDA aggressiveness and intestinal infiltration. These findings suggest AQP3 and AQP5 involvement in PDA development and the usefulness of AQP5 in early PDA diagnosis. © 2017 Wiley Periodicals, Inc.

  4. Electrostatic tuning of permeation and selectivity in aquaporin water channels

    DEFF Research Database (Denmark)

    Jensen, Mogens O Stibius; Tajkhorshid, E.; Schulten, K.

    2003-01-01

    of the single file remains intact during the permeation, indicating that a disrupted water chain is unlikely to be the mechanism of proton exclusion in aquaporins. Specific hydrogen bonds between permeating water and protein at the channel center (at two conserved Asp-Pro-Ala "NPA'' motifs), together...... stronger than water-protein interactions, except near a conserved, positively charged Arg residue. We find that variations of the protein electrostatic field through the channel, owing to preserved structural features, completely explain the bipolar orientation of water. This orientation persists despite...... water translocation in single. le and blocks proton transport. Furthermore, we find that for permeation of a cation, ion-protein electrostatic interactions are more unfavorable at the conserved NPA motifs than at the conserved Arg, suggesting that the major barrier against proton transport in aquaporins...

  5. Aquaporin-Based Biomimetic Polymeric Membranes: Approaches and Challenges

    Science.gov (United States)

    Habel, Joachim; Hansen, Michael; Kynde, Søren; Larsen, Nanna; Midtgaard, Søren Roi; Jensen, Grethe Vestergaard; Bomholt, Julie; Ogbonna, Anayo; Almdal, Kristoffer; Schulz, Alexander; Hélix-Nielsen, Claus

    2015-01-01

    In recent years, aquaporin biomimetic membranes (ABMs) for water separation have gained considerable interest. Although the first ABMs are commercially available, there are still many challenges associated with further ABM development. Here, we discuss the interplay of the main components of ABMs: aquaporin proteins (AQPs), block copolymers for AQP reconstitution, and polymer-based supporting structures. First, we briefly cover challenges and review recent developments in understanding the interplay between AQP and block copolymers. Second, we review some experimental characterization methods for investigating AQP incorporation including freeze-fracture transmission electron microscopy, fluorescence correlation spectroscopy, stopped-flow light scattering, and small-angle X-ray scattering. Third, we focus on recent efforts in embedding reconstituted AQPs in membrane designs that are based on conventional thin film interfacial polymerization techniques. Finally, we describe some new developments in interfacial polymerization using polyhedral oligomeric silsesquioxane cages for increasing the physical and chemical durability of thin film composite membranes. PMID:26264033

  6. Molecular Identification of First Putative Aquaporins in Snails

    OpenAIRE

    Pieńkowska, Joanna R.; Kosicka, Ewa; Wojtkowska, Małgorzata; Kmita, Hanna; Lesicki, Andrzej

    2014-01-01

    Aquaporins (AQPs), also known as water channel proteins, are members of a large protein family termed Major Intrinsic Proteins (MIP). The mammalian AQPs have been most comprehensively described, while knowledge about AQPs in invertebrates is limited mainly to insects. Not a single AQP protein has been described in snails to date. Consequently, we decided to search for the proteins in gastropod representatives, namely Lymnaea stagnalis, Catascopia occulta, and Stagnicola palustris (Mollusca; G...

  7. Novel Commercial Aquaporin Flat-Sheet Membrane for Forward Osmosis

    DEFF Research Database (Denmark)

    Xia, Lingling; Andersen, Mads Friis; Hélix-Nielsen, Claus

    2017-01-01

    commercially available thin-film composite (TFC) FO membrane to incorporate aquaporin proteins into its polyamide-based selective layer. The membrane tested, which is a first-generation membrane, achieved water fluxes of 14.0 and 8.8 L m–2 h–1 with low reverse salt fluxes of 4.6 and 4.0 g m–2 h–1 in pressure...

  8. Aquaporin-2 excretion in hospitalized patients with cirrhosis

    DEFF Research Database (Denmark)

    Busk, Troels M.; Moller, Soren; Pedersen, Erling B.

    2017-01-01

    Background and Aim: Urinary aquaporin-2 (AQP2) is a parameter of water transport in the principal cells in the distal part of the nephron and involved in water retention in cirrhosis and may be a marker of renal function. The aim of the study was to evaluate AQP2 as a predictor of renal insuffici......Background and Aim: Urinary aquaporin-2 (AQP2) is a parameter of water transport in the principal cells in the distal part of the nephron and involved in water retention in cirrhosis and may be a marker of renal function. The aim of the study was to evaluate AQP2 as a predictor of renal...... for urine AQP2 and urine osmolality.  Results: There was no difference in AQP2 between the three groups. Urine osmolality was significantly lower in patients in Group 3 versus Group 1 and Group 2 (P = 0.0004). No relation was found between AQP2 and glomerular filtration rate or creatinine; however, AQP2...... was a significant predictor of the development of renal insufficiency (P = 0.0485). In a univariate analysis, AQP2 was a significant predictor of 14 and 28-day survival, but this was not confirmed in multivariate analysis.  Conclusions: Aquaporin-2 was not associated with disease severity or markers of renal...

  9. Expression and prognostic value of aquaporin 1, 3 in cervical carcinoma in women of Uygur ethnicity from Xinjiang, China.

    Directory of Open Access Journals (Sweden)

    Rui Chen

    Full Text Available BACKGROUND: Overexpression of several aquaporins has been reported in different types of human cancer but the role of aquaporins in carcinogenesis has not yet been clearly defined. There is few report concerning role of aquaporins in human cervical carcinogenesis so far. Here, we determined the expression and prognostic value of aquaporin 1, 3 in cervical carcinoma in Chinese women of Uygur ethnicity. METHODS AND RESULTS: Real-time PCR analyses demonstrated aquaporin 1, 3 mRNA were differentially expressed in cervical carcinoma, CIN 2-3 and mild cervicitis. Immunofluorescent and immunohistochemical analyses demonstrated aquaporin 1 was predominantly localized to stromal endothelial cells in cervical lesions. Aquaporin 3 was localized to the membrane of normal squamous epithelium, CIN and carcinoma cells. Aquaporin 1 and 3 were upregulated in cervical cancer compared to mild cervicitis and CIN2-3 (P<0.05; Tumor expression of aquaporin 1, 3 significantly increased in advanced stage disease, and patients with deeper tumor infiltration, lymph node metastases or larger tumor volume (P<0.05. Multivariate analysis demonstrated that aquaporin 1, 3 were not independent prognostic factors in cervical carcinoma. CONCLUSION: Aquaporins may participate in the initiation and progression of cervical carcinoma by promoting tumor growth, invasion or lymph node metastasis. Further study is required to determine whether aquaporins have potential as prognostic factors in cervical cancer.

  10. A Gold Coordination Compound as a Chemical Probe to Unravel Aquaporin-7 Function

    NARCIS (Netherlands)

    Madeira, Ana; de Almeida, Andreia; de Graaf, Chris; Camps, Marta; Zorzano, Antonio; Moura, Teresa F; Casini, Angela; Soveral, Graça

    2014-01-01

    Aquaporins (AQPs) are membrane water/glycerol channels that are involved in many physiological functions. Aquaporin-based modulators are predicted to have potential utility in the treatment of several diseases, as well as chemical tools to assess AQPs function in biological systems. We recently

  11. Regulation of Aquaporin Z osmotic permeability in ABA tri-block copolymer

    Directory of Open Access Journals (Sweden)

    Wenyuan Xie

    2015-08-01

    Full Text Available Aquaporins are transmembrane water channel proteins present in biological plasma membranes that aid in biological water filtration processes by transporting water molecules through at high speeds, while selectively blocking out other kinds of solutes. Aquaporin Z incorporated biomimetic membranes are envisaged to overcome the problem of high pressure needed, and holds great potential for use in water purification processes, giving high flux while keeping energy consumption low. The functionality of aquaporin Z in terms of osmotic permeability might be regulated by factors such as pH, temperature, crosslinking and hydrophobic thickness of the reconstituted bilayers. Hence, we reconstituted aquaporin Z into vesicles that are made from a series of amphiphilic block copolymers PMOXA-PDMS-PMOXAs with various hydrophobic molecular weights. The osmotic permeability of aquaporin Z in these vesicles was determined through a stopped-flow spectroscopy. In addition, the temperature and pH value of the vesicle solutions were adjusted within wide ranges to investigate the regulation of osmotic permeability of aquaporin Z through external conditions. Our results show that aquaporin Z permeability was enhanced by hydrophobic mismatch. In addition, the water filtration mechanism of aquaporin Z is significantly affected by the concentration of H+ and OH- ions.

  12. Distribution of aquaporins in the nasal passage of Octodon degus, a South-American desert rodent and its implications for water conservation Distribución de acuaporinas en los pasajes nasales de Octodon degus, un roedor de ambientes desérticos sudamericanos: implicaciones en la conservación de agua

    Directory of Open Access Journals (Sweden)

    PEDRO GALLARDO

    2008-03-01

    Full Text Available Rodents from arid and semiarid environments live under conditions where the spatial and temporal availability of water is limited. Octodon degus is a South-American desert-dwelling rodent inhabiting arid and semiarid habitats of central and northern Chile. Its survival depends on morphological, physiological and behavioral adaptations that allow water conservation. This rodent has a high urine concentrating ability, high capacity of fecal dehydration and low evaporative water loss, related to the ability of the nasal passages to condense water from the exhaled air; this water must be absorbed in order to avoid its accumulation in the nasal passages and potential loss through the nostrils. We hypothesize that aquaporins (AQPs might be present in the nasal mucosa; therefore, we studied the distribution of AQP-1, AQP-2, AQP-3 and AQP-4 through immunocytochemistry. Intense AQP-1 labeling was observed throughout the subepithelial vascular network; no AQP-1 immunoreactivity was detected in olfactory and non-olfactory epithelial cells. No signal was detected for AQP-2 and 4. AQP-3 distribution was restricted to the surface non-olfactory epithelial cells lining the turbinates in narrow passages and blind spaces. Therefore, AQP-1 and AQP-3 coincided at the level of the turbinates, although in different cell types which suggest a pathway for water removal from the nasal surface first through AQP-3 in non-olfactory epithelial cells and then into the capillary lumen through AQP-1Los roedores de ambientes áridos y semiáridos viven bajo una disponibilidad limitada de agua tanto espacial como temporal. Octodon degus es un roedor sudamericano que habita ambientes áridos y semiáridos del norte y zona central de Chile. Su supervivencia depende de adaptaciones morfológicas, fisiológicas y conductuales que permiten optimizar la conservación de agua. Este tiene una alta capacidad de concentración urinaria y de deshidratación de la fecas además de una baja

  13. Structural features of aquaporin 4 supporting the formation of arrays and junctions in biomembranes.

    Science.gov (United States)

    Höfinger, Siegfried; Yamamoto, Eiji; Hirano, Yoshinori; Zerbetto, Francesco; Narumi, Tetsu; Yasuoka, Kenji; Yasui, Masato

    2012-09-01

    A limited class of aquaporins has been described to form regular arrays and junctions in membranes. The biological significance of these structures, however, remains uncertain. Here we analyze the underlying physical principles with the help of a computational procedure that takes into account protein-protein as well as protein-membrane interactions. Experimentally observed array/junction structures are systematically (dis)assembled and major driving forces identified. Aquaporin 4 was found to be markedly different from the non-junction forming aquaporin 1. The environmental stabilization resulting from embedding into the biomembrane was identified as the main driving force. This highlights the role of protein-membrane interactions in aquaporin 4. Analysis of the type presented here can help to decipher the biological role of membrane arrays and junctions formed by aquaporin. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Recombinant Production of Human Aquaporin-1 to an Exceptional High Membrane Density in Saccharomyces Cerevisiae

    DEFF Research Database (Denmark)

    Bomholt, Julie; Helix Nielsen, Claus; Scharff-Poulsen, Peter

    2014-01-01

    of solutes. Aquaporins constitute a family of physiologically very important integral membrane proteins that are found in all three kingdoms, eubacteria, archaea and eukaryotes. As protein channels, they facilitate passive transport of water across cell membranes. In the present study the yeast Saccharomyces...... cerevisiae was exploited as a host for heterologous expression of human aquaporins. Aquaporin cDNA was expressed from a galactose inducible promoter situated on a plasmid with an adjustable copy number. Human aquaporin was C-terminally tagged with yeast-enhanced GFP to quantify functional expression...... transcription factor and growth in amino acid supplemented minimal medium. In-gel fluorescence combined with western blotting showed that low accumulation of correctly folded recombinant Aquaporin-1 at 30oC was due to in vivo mal-folding. Reduction of the expression temperature to 15oC almost completely...

  15. On the definition, nomenclature and classification of water channel proteins (aquaporins and relatives).

    Science.gov (United States)

    Benga, Gheorghe

    2012-01-01

    A water channel protein (WCP) or a water channel can be defined as a transmembrane protein that has a specific three-dimensional structure with a pore that provides a pathway for water permeation across biological membranes. The pore is formed by two highly conserved regions in the amino acid sequence, called NPA boxes (or motifs) with three amino acid residues (asparagine-proline-alanine, NPA) and several surrounding amino acids. The NPA boxes have been called the "signature" sequence of WCPs. WCPs are a family of proteins belonging to the Membrane Intrinsic Proteins (MIPs) superfamily. In addition, in the MIP superfamily (with more than 1000 members) there are also proteins with no channel activity. The WCP family include three subfamilies: aquaporins, aquaglyceroporins and S-aquaporins. (1) The aquaporins (AQPs) are water selective or specific water channels, also named by various authors as "orthodox", "ordinary", "conventional", "classical", "pure", "normal", or "sensu strictu" aquaporins); (2) The aquaglyceroporins are permeable to water, but also to other small uncharged molecules, in particular glycerol; this family includes the glycerol facilitators, abbreviated as GlpFs, from glycerol permease facilitators. The "signature" sequence for aquaglyceroporins is the aspartic acid residue (D) in the second NPA box. (3) The third subfamily of WCPs have little conserved amino acid sequences around the NPA boxes, unclassifiable to the first two subfamilies. I recommend to use always for this subfamily the name S-aquaporins. They are also named "superaquaporins", "aquaporins with unusual (or deviated) NPA boxes", "subcellular aquaporins", or "sip-like aquaporins". I also recommend to use always the spelling aquaporin (not aquaporine), and, for various AQPs, the abbreviation AQP followed immediately by the number, (e.g. AQP1), with no space or--which might create confusions with "minus". Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Effect of repetitive daily ethanol intoxication on adult rat brain: significant changes in phospholipase A2 enzyme levels in association with increased PARP-1 indicate neuroinflammatory pathway activation.

    Science.gov (United States)

    Tajuddin, Nuzhath F; Przybycien-Szymanska, Magdalena M; Pak, Toni R; Neafsey, Edward J; Collins, Michael A

    2013-02-01

    Collaborating on studies of subchronic daily intoxication in juvenile and adult rats, we examined whether the repetitive ethanol treatments at these two life stages altered levels of key neuroinflammation-associated proteins-aquaporin-4 (AQP4), certain phospholipase A2 (PLA2) enzymes, PARP-1 and caspase-3-in hippocampus (HC) and entorhinal cortex (EC). Significant changes in the proteins could implicate activation of specific neuroinflammatory signaling pathways in these rats as well as in severely binge-intoxicated adult animals that are reported to incur degeneration of vulnerable neurons in HC and EC. Male Wistar rats, ethanol-intoxicated (3 g/kg i.p.) once daily for 6 days over an 8-day interval beginning at 37 days old and repeated at age 68-75 days, were sacrificed 1 h after the day 75 dose (blood ethanol, 200- 230 mg/dl). Analysis of HC with an immunoblot technique showed that AQP4, Ca(+2)-dependent PLA2 (cPLA2 IVA), phosphorylated (activated) p-cPLA2, cleaved (89 kD) PARP (c-PARP), and caspase-3 levels were significantly elevated over controls, whereas Ca(+2)-independent PLA2 (iPLA2 VIA) was reduced ∼70%; however, cleaved caspase-3 was undetectable. In the EC, AQP4 was unchanged, but cPLA2 and p-cPLA2 were significantly increased while iPLA2 levels were diminished (∼40%) similar to HC, although just outside statistical significance (p = 0.06). In addition, EC levels of PARP-1 and c-PARP were significantly increased. The ethanol-induced activation of cPLA2 in association with reduced iPLA2 mirrors PLA2 changes in reports of neurotrauma and also of dietary omega-3 fatty acid depletion. Furthermore, the robust PARP-1 elevations accompanied by negligible caspase-3 activation indicate that repetitive ethanol intoxication may be potentiating non-apoptotic neurodegenerative processes such as parthanatos. Overall, the repetitive ethanol treatments appeared to instigate previously unappreciated neuroinflammatory pathways in vivo. The data provide insights

  17. Decreased levels of aquaporin-4 in the cerebrospinal fluid of patients with idiopathic intracranial hypertension.

    Science.gov (United States)

    Doppler, Kathrin; Schütt, Morten; Sommer, Claudia

    2016-12-01

    Idiopathic intracranial hypertension is characterized by increased intracranial pressure. Its pathogenesis is largely unknown. Aquaporins may play a role in the homeostasis of cerebrospinal fluid. We aimed to elucidate the role of aquaporins in idiopathic intracranial hypertension by measuring the level of aquaporin-1 and aquaporin-4 in the cerebrospinal fluid and plasma of 28 patients and 29 controls by enzyme-linked immunosorbent assay. The adipokines leptin and retinol-binding protein 4 were also measured. We found a reduction in aquaporin-4 in the cerebrospinal fluid of patients. Leptin levels were increased in the cerebrospinal fluid and plasma of patients and were correlated with weight, body mass index and body fat. There was no difference between patients and controls in the levels of aquaporin-1 and retinol-binding protein 4. Our data suggest that an imbalance of aquaporin-4 in the cerebrospinal fluid of patients with idiopathic intracranial hypertension may contribute to the pathogenesis of this disorder. © International Headache Society 2016.

  18. Can Stabilization and Inhibition of Aquaporins Contribute to Future Development of Biomimetic Membranes?

    Directory of Open Access Journals (Sweden)

    Janet To

    2015-08-01

    Full Text Available In recent years, the use of biomimetic membranes that incorporate membrane proteins, i.e., biomimetic-hybrid membranes, has increased almost exponentially. Key membrane proteins in these systems have been aquaporins, which selectively permeabilize cellular membranes to water. Aquaporins may be incorporated into synthetic lipid bilayers or to more stable structures made of block copolymers or solid-state nanopores. However, translocation of aquaporins to these alien environments has adverse consequences in terms of performance and stability. Aquaporins incorporated in biomimetic membranes for use in water purification and desalination should also withstand the harsh environment that may prevail in these conditions, such as high pressure, and presence of salt or other chemicals. In this respect, modified aquaporins that can be adapted to these new environments should be developed. Another challenge is that biomimetic membranes that incorporate high densities of aquaporin should be defect-free, and this can only be efficiently ascertained with the availability of completely inactive mutants that behave otherwise like the wild type aquaporin, or with effective non-toxic water channel inhibitors that are so far inexistent. In this review, we describe approaches that can potentially be used to overcome these challenges.

  19. Molecular Pathogenesis of Neuromyelitis Optica

    Directory of Open Access Journals (Sweden)

    Simon A Broadley

    2012-10-01

    Full Text Available Neuromyelitis optica (NMO is a rare autoimmune disorder, distinct from multiple sclerosis, causing inflammatory lesions in the optic nerves and spinal cord. An autoantibody (NMO IgG against aquaporin-4 (AQP4, a water channel expressed on astrocytes is thought to be causative. Peripheral production of the antibody is triggered by an unknown process in genetically susceptible individuals. Anti-AQP4 antibody enters the central nervous system (CNS when the blood brain barrier is made permeable and has high affinity for orthogonal array particles of AQP4. Like other autoimmune diseases, Th17 cells and their effector cytokines (such as interleukin 6 have been implicated in pathogenesis. AQP4 expressing peripheral organs are not affected by NMO IgG, but the antibody causes extensive astrocytic loss in specific regions of the CNS through complement mediated cytotoxicity. Demyelination occurs during the inflammatory process and is probably secondary to oligodendrocyte apoptosis subsequent to loss of trophic support from astrocytes. Ultimately, extensive axonal injury leads to severe disability. Despite rapid advances in the understanding of NMO pathogenesis, unanswered questions remain, particularly with regards to disease mechanisms in NMO IgG seronegative cases. Increasing knowledge of the molecular pathology is leading to improved treatment strategies.

  20. Preparative scale production of functional mouse aquaporin 4 using different cell-free expression modes.

    Directory of Open Access Journals (Sweden)

    Lei Kai

    Full Text Available The continuous progress in the structural and functional characterization of aquaporins increasingly attracts attention to study their roles in certain mammalian diseases. Although several structures of aquaporins have already been solved by crystallization, the challenge of producing sufficient amounts of functional proteins still remains. CF (cell free expression has emerged in recent times as a promising alternative option in order to synthesize large quantities of membrane proteins, and the focus of this report was to evaluate the potential of this technique for the production of eukaryotic aquaporins. We have selected the mouse aquaporin 4 as a representative of mammalian aquaporins. The protein was synthesized in an E. coli extract based cell-free system with two different expression modes, and the efficiencies of two modes were compared. In both, the P-CF (cell-free membrane protein expression as precipitate mode generating initial aquaporin precipitates as well as in the D-CF (cell-free membrane protein expression in presence of detergent mode, generating directly detergent solubilized samples, we were able to obtain mg amounts of protein per ml of cell-free reaction. Purified aquaporin samples solubilized in different detergents were reconstituted into liposomes, and analyzed for the water channel activity. The calculated P(f value of proteoliposome samples isolated from the D-CF mode was 133 µm/s at 10°C, which was 5 times higher as that of the control. A reversible inhibitory effect of mercury chloride was observed, which is consistent with previous observations of in vitro reconstituted aquaporin 4. In this study, a fast and convenient protocol was established for functional expression of aquaporins, which could serve as basis for further applications such as water filtration.

  1. Electrostatics of aquaporin and aquaglyceroporin channels correlates with their transport selectivity

    Science.gov (United States)

    Oliva, Romina; Calamita, Giuseppe; Thornton, Janet M.; Pellegrini-Calace, Marialuisa

    2010-01-01

    Aquaporins are homotetrameric channel proteins, which allow the diffusion of water and small solutes across biological membranes. According to their transport function, aquaporins can be divided into “orthodox aquaporins”, which allow the flux of water molecules only, and “aquaglyceroporins”, which facilitate the diffusion of glycerol and other small solutes in addition to water. The contribution of individual residues in the pore to the selectivity of orthodox aquaporins and aquaglyceroporins is not yet fully understood. To gain insights into aquaporin selectivity, we focused on the sequence variation and electrostatics of their channels. The continuum Poisson-Boltzmann electrostatic potential along the channel was calculated and compared for ten three-dimensional-structures which are representatives of different aquaporin subfamilies, and a panel of functionally characterized mutants, for which high-accuracy three-dimensional-models could be derived. Interestingly, specific electrostatic profiles associated with the main selectivity to water or glycerol could be identified. In particular: (i) orthodox aquaporins showed a distinctive electrostatic potential maximum at the periplasmic side of the channel around the aromatic/Arg (ar/R) constriction site; (ii) aquaporin-0 (AQP0), a mammalian aquaporin with considerably low water permeability, had an additional deep minimum at the cytoplasmic side; (iii) aquaglyceroporins showed a rather flat potential all along the channel; and (iv) the bifunctional protozoan PfAQP had an unusual all negative profile. Evaluation of electrostatics of the mutants, along with a thorough sequence analysis of the aquaporin pore-lining residues, illuminated the contribution of specific residues to the electrostatics of the channels and possibly to their selectivity. PMID:20147624

  2. Trace organic contaminant rejection by aquaporin forward osmosis membrane: Transport mechanisms and membrane stability.

    Science.gov (United States)

    Xie, Ming; Luo, Wenhai; Guo, Hao; Nghiem, Long D; Tang, Chuyang Y; Gray, Stephen R

    2017-12-28

    We investigated transport mechanisms of trace organic contaminants (TrOCs) through aquaporin thin-film composite forward osmosis (FO) membrane, and membrane stability under extreme conditions with respect to TrOC rejections. Morphology and surface chemistry of the aquaporin membrane were characterised to identify the incorporation of aquaporin vesicles into membrane active layer. Pore hindrance model was used to estimate aquaporin membrane pore size as well as to describe TrOC transport. TrOC transport mechanisms were revealed by varying concentration and type of draw solutions. Experimental results showed that mechanism of TrOC transport through aquaporin-embedded FO membrane was dominated by solution-diffusion mechanism. Non-ionic TrOC rejections were molecular-weight dependent, suggesting steric hindrance mechanisms. On the other hand, ionic TrOC rejections were less sensitive to molecular size, indicating electrostatic interaction. TrOC transport through aquaporin membrane was also subjected to retarded forward diffusion where reverse draw solute flux could hinder the forward diffusion of feed TrOC solutes, reducing their permeation through the FO membrane. Aquaporin membrane stability was demonstrated by either heat treatment or ethanol solvent challenges. Thermal stability of the aquaporin membrane was manifested as a relatively unchanged TrOC rejection before and after the heat treatment challenge test. By contrast, ethanol solvent challenge resulted in a decrease in TrOC rejection, which was evident by the disappearance of the lipid tail of the aquaporin vesicles from infrared spectrum and a notable decrease in the membrane pore size. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Aquaporin-5: from structure to function and dysfunction in cancer.

    Science.gov (United States)

    Direito, Inês; Madeira, Ana; Brito, Maria Alexandra; Soveral, Graça

    2016-04-01

    Aquaporins, a highly conserved group of membrane proteins, are involved in the bidirectional transfer of water and small solutes across cell membranes taking part in many biological functions all over the human body. In view of the wide range of cancer malignancies in which aquaporin-5 (AQP5) has been detected, an increasing interest in its implication in carcinogenesis has emerged. Recent publications suggest that this isoform may enhance cancer cell proliferation, migration and survival in a variety of malignancies, with strong evidences pointing to AQP5 as a promising drug target and as a novel biomarker for cancer aggressiveness with high translational potential for therapeutics and diagnostics. This review addresses the structural and functional features of AQP5, detailing its tissue distribution and functions in human body, its expression pattern in a variety of tumors, and highlighting the underlying mechanisms involved in carcinogenesis. Finally, the actual progress of AQP5 research, implications in cancer biology and potential for cancer detection and prognosis are discussed.

  4. The role of aquaporins in the kidney of euryhaline teleosts

    DEFF Research Database (Denmark)

    Engelund, Morten Buch; Madsen, Steffen S

    2011-01-01

    WATER BALANCE IN TELEOST FISH IS MAINTAINED WITH CONTRIBUTIONS FROM THE MAJOR OSMOREGULATORY ORGANS: intestine, gills, and kidney. Overall water fluxes have been studied in all of these organs but not until recently has it become possible to approach the mechanisms of water transport at the molec......WATER BALANCE IN TELEOST FISH IS MAINTAINED WITH CONTRIBUTIONS FROM THE MAJOR OSMOREGULATORY ORGANS: intestine, gills, and kidney. Overall water fluxes have been studied in all of these organs but not until recently has it become possible to approach the mechanisms of water transport...... at the molecular level. This mini-review addresses the role of the kidney in osmoregulation with special emphasis on euryhaline teleosts. After a short review of current knowledge of renal functional morphology and regulation, we turn the focus to recent molecular investigations of the role of aquaporins in water...... and solute transport in the teleost kidney. We conclude that there is much to be achieved in understanding water transport and its regulation in the teleost kidney and that effort should be put into systematic mapping of aquaporins to their tubular as well as cellular localization....

  5. Tubular localization and expressional dynamics of aquaporins in the kidney of seawater-challenged Atlantic salmon

    DEFF Research Database (Denmark)

    Engelund, Morten Buch; Madsen, Steffen S

    2015-01-01

    Most vertebrate nephrons possess an inherited ability to secrete fluid in normal or pathophysiological states. We hypothesized that renal aquaporin expression and localization are functionally regulated in response to seawater and during smoltification in Atlantic salmon and thus reflect a shift...... in renal function from filtration towards secretion. We localized aquaporins (Aqp) in Atlantic salmon renal tubular segments by immunohistochemistry and monitored their expressional dynamics using RT-PCR and immunoblotting. Three aquaporins: Aqpa1aa, Aqp1ab and Aqp8b and two aquaglyceroporins Aqp3a and Aqp......10b were localized in the kidney of salmon. The staining for all aquaporins was most abundant in the proximal kidney tubules and there was no clear effect of salinity or developmental stage on localization pattern. Aqp1aa and Aqp3a were abundant apically but extended throughout the epithelial cells...

  6. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    DEFF Research Database (Denmark)

    Li, Zhenyu; Linares, Rodrigo Valladares; Bucs, Szilard

    2017-01-01

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused, by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin...... based biomimetic membrane in simulated membrane cleaning processes. The effects of cleaning agents on water flux and salt rejection were evaluated. The membrane showed a good resistance to the chemical agents. The water flux after chemical cleaning showed significant increases, particularly after...... with secondary wastewater effluent as the feed solution and seawater as the draw solution showed a stable flux and high salt rejection. The average rejection of the dissolved organic carbon from wastewater after the 15-day test was 90%. The results demonstrated that the aquaporin based biomimetic FO membrane...

  7. Seronegative Neuromyelitis Optica Spectrum - The challenges on disease definition and pathogenesis

    Directory of Open Access Journals (Sweden)

    Douglas Kazutoshi Sato

    2014-06-01

    Full Text Available Neuromyelitis optica spectrum disorders (NMOSD are characterized by severe optic neuritis and/or longitudinally extensive transverse myelitis, and some brain lesions are also unique to NMOSD. Serum autoantibodies against aquaporin-4 (AQP4 are detected in most cases of NMOSD. However, some patients with NMOSD remain seronegative despite repetitive testing during attacks with highly sensitive cell-based assays. The differential diagnosis of NMOSD is not restricted to multiple sclerosis and it includes many diseases that can produce longitudinally extensive myelitis and/or optic neuritis. We review the clinical features, imaging, and laboratory findings that can be helpful on the diagnostic work-up, discuss the differences between AQP4 antibody positive and negative patients with NMOSD, including features of NMOSD with antibodies against myelin oligodendrocyte glycoprotein.

  8. Genome-wide identification and characterization of aquaporin gene family in common bean (Phaseolus vulgaris L.).

    Science.gov (United States)

    Ariani, Andrea; Gepts, Paul

    2015-10-01

    Plant aquaporins are a large and diverse family of water channel proteins that are essential for several physiological processes in living organisms. Numerous studies have linked plant aquaporins with a plethora of processes, such as nutrient acquisition, CO2 transport, plant growth and development, and response to abiotic stresses. However, little is known about this protein family in common bean. Here, we present a genome-wide identification of the aquaporin gene family in common bean (Phaseolus vulgaris L.), a legume crop essential for human nutrition. We identified 41 full-length coding aquaporin sequences in the common bean genome, divided by phylogenetic analysis into five sub-families (PIPs, TIPs, NIPs, SIPs and XIPs). Residues determining substrate specificity of aquaporins (i.e., NPA motifs and ar/R selectivity filter) seem conserved between common bean and other plant species, allowing inference of substrate specificity for these proteins. Thanks to the availability of RNA-sequencing datasets, expression levels in different organs and in leaves of wild and domesticated bean accessions were evaluated. Three aquaporins (PvTIP1;1, PvPIP2;4 and PvPIP1;2) have the overall highest mean expressions, with PvTIP1;1 having the highest expression among all aquaporins. We performed an EST database mining to identify drought-responsive aquaporins in common bean. This analysis showed a significant increase in expression for PvTIP1;1 in drought stress conditions compared to well-watered environments. The pivotal role suggested for PvTIP1;1 in regulating water homeostasis and drought stress response in the common bean should be verified by further field experimentation under drought stress.

  9. The influence of natural mineral water on aquaporin water permeability and human natural killer cell activity.

    Science.gov (United States)

    Kitagawa, Yoshichika; Liu, Chengwei; Ding, Xiaodong

    2011-05-27

    Aquaporins are the intrinsic membrane proteins functioning as water channel to transport water and/or mineral nutrients across the biological membrane systems. In this research, we aimed to clarify if the selected mineral water can affect aquaporin functions in vitro and the assumption of the mineral water can modify aquaporin expression and activate natural killer cell activity in human body. First, we expressed six human and eight plant aquaporin genes in oocytes and compared the effect of different kinds of natural mineral water on aquaporin activity. The oocyte assay data show that Hita tenryosui water could promote water permeability of almost all human and plant aquaporins in varying degrees, and freeze-dry and organic solvent extraction could reduce AQP2 activity but pH change and boiling could not. Second, each volunteer in two groups (10 in one group) received an oral Hita tenryosui or tap water load of 1000 ml/day for total four weeks. We found that these two kinds of water did not directly affect the relative expression levels of AQP1 and AQP9 in the blood cells, but intriguingly, the natural killer cell activities of the volunteers drinking Hita tenryosui water were significantly improved, suggesting that Hita tenryosui water has obvious health function, which opens a new and interesting field of investigation related to the link between mineral water consumption and human health and the therapies for some chronic diseases. Published by Elsevier Inc.

  10. Aquaporins: a family of highly regulated multifunctional channels.

    Science.gov (United States)

    Hachez, Charles; Chaumont, François

    2010-01-01

    Aquaporins (AQPs) were discovered as channels facilitatingwater movement across cellular membranes. Whereas much of the research has focused on characterizing AQPs with respect to cell water homeostasis, recent discoveries in terms of the transport selectivity of AQP homologs has shed new light on their physiological roles. In fact, whereas some AQPs behave as "strict" water channels, others can conduct a wide range ofnonpolar solutes, such as urea or glycerol and even more unconventional permeants, such as the nonpolar gases carbon dioxide and nitric oxide, the polar gas ammonia, the reactive oxygen species hydrogen peroxide and the metalloids antimonite, arsenite, boron and silicon. This suggests that AQPs are also key players in various physiological processes not related to water homeostasis. The function, regulation and biological importance of AQPs in the different kingdoms is reviewed in this chapter, with special emphasis on animal and plant AQPs.

  11. Aquaporins 6-12 in the human eye

    DEFF Research Database (Denmark)

    Tran, Thuy Linh; Bek, Toke; Holm, Lars

    2012-01-01

    was detected in the corneal epithelium, corneal endothelium, trabecular meshwork endothelium, ciliary epithelia, lens epithelium, the inner and outer limiting membrane of the retina, the retinal pigment epithelium and the capillary endothelium of all parts of the eye. AQP9 immunolabelling was detected......Purpose: Aquaporins (AQPs) are widely expressed and have diverse distribution patterns in the eye. AQPs 0-5 have been localized at the cellular level in human eyes. We investigated the presence of the more recently discovered AQPs 6-12 in the human eye. Methods: RT-PCR was performed on fresh tissue...... from two human eyes divided into the cornea, corneal limbus, ciliary body and iris, lens, choroid, optic nerve, retina and sclera. Each structure was examined to detect the mRNA of AQPs 6-12. Twenty-one human eyes were examined using immunohistochemical and immunofluorescence techniques to determine...

  12. Aquaporin-1 is a Maxwell's Demon in the Body

    CERN Document Server

    Shu, Liangsuo; Xiaokang,; Qian, Liu Xin; Huang, Suyi; Jin, Shiping; Yang, Baoxue

    2015-01-01

    Aquaporin-1 (AQP1) is a membrane protein which is selectively permeable to water. Due to its hourglass shape, AQP1 can sense the information of solute molecules in osmosis. At the cost of consuming this information, AQP1 can move water against its chemical potential gradient: it works as one kind of Maxwell's Demon. This effect was detected quantitatively by measuring the water osmosis of mice erythrocytes. This ability may protect the erythrocytes from the eryptosis elicited by osmotic shock when they move in the kidney, where a large gradient of urea is required for the urine concentrating mechanism. This finding anticipates a new beginning of inquiries into the complicated relationships among mass, energy and information in bio-systems.

  13. A molecular modeling approach defines a new group of Nodulin 26-like aquaporins in plants.

    Science.gov (United States)

    Rougé, Pierre; Barre, Annick

    2008-02-29

    The three-dimensional models built for the Nod26-like aquaporins all exhibit the typical alpha-helical fold of other aquaporins containing the two ar/R and NPA constriction filters along the central water channel. Besides these structural homologies, they readily differ with respect to the amino acid residues forming the ar/R selective filter. According to these discrepancies in both the hydrophilicity and pore size of the ar/R filter, Nod26-like aquaporins can be distributed in three subgroups corresponding to NIP-1, NIP-II and a third subgroup of Nod26-like aquaporins exhibiting a highly hydrophilic and widely open filter. However, all Nod26-like aquaporins display a bipartite distribution of electrostatic charges along the water channel with an electropositive extracellular vestibular portion followed by an electronegative cytosolic vestibular portion. The specific transport of water, non-ionic solutes (glycerol, urea, ammoniac), ions (NH4+) and gas (NH(3)) across the Nod26-like obviously depends on the electrostatic and conformational properties of their central water channel.

  14. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    KAUST Repository

    Li, Zhenyu

    2017-07-27

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin based biomimetic membrane in simulated membrane cleaning processes. The effects of cleaning agents on water flux and salt rejection were evaluated. The membrane showed a good resistance to the chemical agents. The water flux after chemical cleaning showed significant increases, particularly after cleaning with NaOCl and Alconox. Changes in the membrane structure and increased hydrophilicity in the surrounding areas of the aquaporin may be accountable for the increase in water permeability. The membrane shows stable salt rejection up to 99% after all cleaning agents were tested. A 15-day experiment with secondary wastewater effluent as the feed solution and seawater as the draw solution showed a stable flux and high salt rejection. The average rejection of the dissolved organic carbon from wastewater after the 15-day test was 90%. The results demonstrated that the aquaporin based biomimetic FO membrane exhibits chemical resistance for most agents used in membrane cleaning procedures, maintaining a stable flux and high salt rejection.

  15. Molecular dynamics simulations of the transport of reactive oxygen species by mammalian and plant aquaporins.

    Science.gov (United States)

    Cordeiro, Rodrigo M

    2015-09-01

    Aquaporins are responsible for water transport across lipid membranes. They are also able to transport reactive oxygen species, playing an important role in redox signaling. Certain plant aquaporins have even the ability to be regulated by oxidative stress. However, the underlying mechanisms are still not fully understood. Here, molecular dynamics simulations were employed to determine the activation free energies related to the transport of reactive oxygen species through both mammalian and plant aquaporin models. Both aquaporins may transport hydrogen peroxide (H2O2) and the protonated form of superoxide radicals (HO2). The solution-to-pore transfer free energies were low for small oxy-radicals, suggesting that even highly reactive hydroxyl radicals (HO) might have access to the pore interior and oxidize amino acids responsible for channel selectivity. In the plant aquaporin, no significant change in water permeability was observed upon oxidation of the solvent-exposed disulfide bonds at the extracellular region. During the simulated time scale, the existence of a direct oxidative gating mechanism involving these disulfide bonds could not be demonstrated. Simulation results may improve the understanding of redox signaling mechanisms and help in the interpretation of protein oxidative labeling experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Genome Wide Identification, Phylogeny, and Expression of Aquaporin Genes in Common Carp (Cyprinus carpio).

    Science.gov (United States)

    Dong, Chuanju; Chen, Lin; Feng, Jingyan; Xu, Jian; Mahboob, Shahid; Al-Ghanim, Khalid; Li, Xuejun; Xu, Peng

    2016-01-01

    Aquaporins (Aqps) are integral membrane proteins that facilitate the transport of water and small solutes across cell membranes. Among vertebrate species, Aqps are highly conserved in both gene structure and amino acid sequence. These proteins are vital for maintaining water homeostasis in living organisms, especially for aquatic animals such as teleost fish. Studies on teleost Aqps are mainly limited to several model species with diploid genomes. Common carp, which has a tetraploidized genome, is one of the most common aquaculture species being adapted to a wide range of aquatic environments. The complete common carp genome has recently been released, providing us the possibility for gene evolution of aqp gene family after whole genome duplication. In this study, we identified a total of 37 aqp genes from common carp genome. Phylogenetic analysis revealed that most of aqps are highly conserved. Comparative analysis was performed across five typical vertebrate genomes. We found that almost all of the aqp genes in common carp were duplicated in the evolution of the gene family. We postulated that the expansion of the aqp gene family in common carp was the result of an additional whole genome duplication event and that the aqp gene family in other teleosts has been lost in their evolution history with the reason that the functions of genes are redundant and conservation. Expression patterns were assessed in various tissues, including brain, heart, spleen, liver, intestine, gill, muscle, and skin, which demonstrated the comprehensive expression profiles of aqp genes in the tetraploidized genome. Significant gene expression divergences have been observed, revealing substantial expression divergences or functional divergences in those duplicated aqp genes post the latest WGD event. To some extent, the gene families are also considered as a unique source for evolutionary studies. Moreover, the whole set of common carp aqp gene family provides an essential genomic

  17. Diabetes Insipidus in Mice with a Mutation in Aquaporin-2.

    Directory of Open Access Journals (Sweden)

    2005-08-01

    Full Text Available Congenital nephrogenic diabetes insipidus (NDI is a disease characterized by failure of the kidney to concentrate urine in response to vasopressin. Human kindreds with nephrogenic diabetes insipidus have been found to harbor mutations in the vasopressin receptor 2 (Avpr2 gene or the vasopressin-sensitive water channel aquaporin-2 (Aqp2 gene. Development of a treatment is rendered difficult due to the lack of a viable animal model. Through forward genetic screening of ethylnitrosourea-mutagenized mice, we report the identification and characterization of a mouse model of NDI, with an F204V mutation in the Aqp2 gene. Unlike previously attempted murine models of NDI, our mice survive to adulthood and more exactly recapitulate the human disorder. Previous in vitro experiments using renal cell lines suggest recessive Aqp2 mutations result in improper trafficking of the mutant water pore. Using these animals, we have directly proven this hypothesis of improper AQP2 translocation as the molecular defect in nephrogenic diabetes insipidus in the intact organism. Additionally, using a renal cell line we show that the mutated protein, AQP2-F204V, is retained in the endoplasmic reticulum and that this abnormal localization can be rescued by wild-type protein. This novel mouse model allows for further mechanistic studies as well as testing of pharmacological and gene therapies for NDI.

  18. Aquaporin-1 Expression in Proliferative Vitreoretinopathy and in Epiretinal Membranes

    Directory of Open Access Journals (Sweden)

    Elie Motulsky

    2014-01-01

    Full Text Available Purpose. Aquaporin-1 (AQP1 is involved in cell migration and proliferation; therefore, the purpose of the study was to investigate its expression in proliferative vitreoretinopathy (PVR and epiretinal membranes (ERM. Methods. 19 membranes from PVR and ERM were collected following eye surgery. AQP1 mRNA and protein expressions were determined by RT-qPCR and immunofluorescence in the membranes from PVR and ERM. Results. AQP1 mRNA and protein were expressed in both PVR and ERM as shown by RT-qPCR and immunofluorescence. AQP1 protein expression was heterogeneous among and between PVR and ERM and colocalized with alpha-smooth muscle actin (αSMA and with glial fibrillary acidic protein (GFAP. There were a higher percentage of cells coexpressing AQP1 and αSMA than AQP1 and GFAP. GFAP and αSMA did not colocalize. Conclusion. Our data show for the first time AQP1 expression in both PVR and ERM. AQP1 is expressed mostly by the αSMA-positive cells, presumably myofibroblasts, but also by GFAP-positive cells, assumed to be glial cells. These original findings warrant further functional investigations aiming at studying the potential role of AQP1 in cell migration and proliferation occurring during the development of PVR and ERM.

  19. Beyond water homeostasis: Diverse functional roles of mammalian aquaporins.

    Science.gov (United States)

    Kitchen, Philip; Day, Rebecca E; Salman, Mootaz M; Conner, Matthew T; Bill, Roslyn M; Conner, Alex C

    2015-12-01

    Aquaporin (AQP) water channels are best known as passive transporters of water that are vital for water homeostasis. AQP knockout studies in whole animals and cultured cells, along with naturally occurring human mutations suggest that the transport of neutral solutes through AQPs has important physiological roles. Emerging biophysical evidence suggests that AQPs may also facilitate gas (CO2) and cation transport. AQPs may be involved in cell signalling for volume regulation and controlling the subcellular localization of other proteins by forming macromolecular complexes. This review examines the evidence for these diverse functions of AQPs as well their physiological relevance. As well as being crucial for water homeostasis, AQPs are involved in physiologically important transport of molecules other than water, regulation of surface expression of other membrane proteins, cell adhesion, and signalling in cell volume regulation. Elucidating the full range of functional roles of AQPs beyond the passive conduction of water will improve our understanding of mammalian physiology in health and disease. The functional variety of AQPs makes them an exciting drug target and could provide routes to a range of novel therapies. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Reconstituted aquaporin 1 water channels transport CO2 across membranes.

    Science.gov (United States)

    Prasad, G V; Coury, L A; Finn, F; Zeidel, M L

    1998-12-11

    Biological membranes provide selective barriers to a number of molecules and gases. However, the factors that affect permeability to gases remain unclear because of the difficulty of accurately measuring gas movements. To determine the roles of lipid composition and the aquaporin 1 (AQP1) water channel in altering CO2 flux across membranes, we developed a fluorometric assay to measure CO2 entry into vesicles. Maximal CO2 flux was approximately 1000-fold above control values with 0.5 mg/ml carbonic anhydrase. Unilamellar phospholipid vesicles of varying composition gave widely varying water permeabilities but similar CO2 permeabilities at 25 degreesC. When AQP1 purified from human red blood cells was reconstituted into proteoliposomes, however, it increased water and CO2 permeabilities markedly. Both increases were abolished with HgCl2, and the mercurial inhibition was reversible with beta-mercaptoethanol. We conclude that unlike water and small nonelectrolytes, CO2 permeation is not significantly altered by lipid bilayer composition or fluidity. AQP1 clearly serves to increase CO2 permeation, likely through the water pore; under certain circumstances, gas permeation through membranes is protein-mediated.

  1. Oxygen-dependent regulation of aquaporin-3 expression

    Directory of Open Access Journals (Sweden)

    Hoogewijs D

    2016-04-01

    Full Text Available David Hoogewijs,1,2 Melanie Vogler,3 Eveline Zwenger,3 Sabine Krull,3 Anke Zieseniss3 1Institute of Physiology, University of Duisburg-Essen, Essen, Germany; 2Institute of Physiology, University of Zürich, Zürich, Switzerland; 3Institute of Cardiovascular Physiology, University Medical Center Göttingen, University of Göttingen, Göttingen, GermanyAbstract: The purpose of this study was to investigate whether aquaporin-3 (AQP3 expression is altered in hypoxia and whether hypoxia-inducible transcription factor (HIF-1 regulates the hypoxic expression. AQP3 mRNA expression was studied in L929 fibrosarcoma cells and in several tissues derived from mice that were subjected to hypoxia. Computational analysis of the AQP3 promoter revealed conserved HIF binding sites within close proximity to the translational start site, and chromatin immunoprecipitation assays confirmed binding of HIF-1 to the endogenous hypoxia response elements. Furthermore, hypoxia resulted in increased expression of AQP3 mRNA in L929 fibrosarcoma cells. Consistently, shRNA-mediated knockdown of HIF-1 greatly reduced the hypoxic induction of AQP3. In addition, mRNA analysis of organs from mice exposed to inspiratory hypoxia demonstrated pronounced hypoxia-inducible expression of AQP3 in the kidney. Overall, our findings suggest that AQP3 expression can be regulated at the transcriptional level and that AQP3 represents a novel HIF-1 target gene. Keywords: transcriptional regulation, oxygen, hypoxia-inducible factor, hypoxia response element

  2. Hepatocyte and Sertoli Cell Aquaporins, Recent Advances and Research Trends

    Directory of Open Access Journals (Sweden)

    Raquel L. Bernardino

    2016-07-01

    Full Text Available Aquaporins (AQPs are proteinaceous channels widespread in nature where they allow facilitated permeation of water and uncharged through cellular membranes. AQPs play a number of important roles in both health and disease. This review focuses on the most recent advances and research trends regarding the expression and modulation, as well as physiological and pathophysiological functions of AQPs in hepatocytes and Sertoli cells (SCs. Besides their involvement in bile formation, hepatocyte AQPs are involved in maintaining energy balance acting in hepatic gluconeogenesis and lipid metabolism, and in critical processes such as ammonia detoxification and mitochondrial output of hydrogen peroxide. Roles are played in clinical disorders including fatty liver disease, diabetes, obesity, cholestasis, hepatic cirrhosis and hepatocarcinoma. In the seminiferous tubules, particularly in SCs, AQPs are also widely expressed and seem to be implicated in the various stages of spermatogenesis. Like in hepatocytes, AQPs may be involved in maintaining energy homeostasis in these cells and have a major role in the metabolic cooperation established in the testicular tissue. Altogether, this information represents the mainstay of current and future investigation in an expanding field.

  3. A Review: Expression of Aquaporins in Otitis Media

    Directory of Open Access Journals (Sweden)

    Su Young Jung

    2017-10-01

    Full Text Available Otitis media (OM refers to inflammatory diseases of the middle ear (ME, regardless of cause or pathological mechanism. Among the molecular biological studies assessing the pathology of OM are investigations of the expression of aquaporins (AQPs in the ME and Eustachian tube (ET. To date, fifteen studies have evaluated AQPs expression in the ME and ET. Although the expression of individual AQPs varies by species and model, eleven types of AQP, AQP1 to AQP11, were found to be expressed in mammalian ME and ET. The review showed that: (1 various types of AQPs are expressed in the ME and ET; (2 AQP expression may vary by species; and (3 the distribution and levels of expression of AQPs may depend on the presence or absence of inflammation, with variations even in the same species and same tissue. Fluid accumulation in the ME and ET is a common pathological mechanism for all types of OM, causing edema in the tissue and inducing inflammation, thereby possibly involving various AQPs. The expression patterns of several AQPs, especially AQP1, 4 and 5, were found to be altered in response to inflammatory stimuli, including lipopolysaccharide (LPS, suggesting that AQPs may have immunological functions in OM.

  4. Differential expression of aquaporin 3 in Triturus italicus from larval to adult epidermal conversion

    Directory of Open Access Journals (Sweden)

    E Brunelli

    2009-06-01

    Full Text Available By using immunohistochemical techniques applied to confocal microscopy, the presence of aquaporin 3 water channel in the epidermis of Triturus italicus (Amphibia, Urodela has been shown. We analysed the expression of aquaporin 3 (AQP3 during the larval, pre-metamorphic and adult phases; we also showed the localization of the water-channel protein AQP3 in free-swimming conditions and during aestivation in parallel with histological analysis of the skin, focusing on the possible relationship between protein expression and terrestrial habitats. Our results indicate that aquaporin is produced as the epidermis modifies during the functional maturation phase starting at the climax. Moreover, our data suggest an increase in enzyme expression in aestivating newts emphasizing the putative functional importance of differential expression related to a distinct phase of the biological cycle.

  5. Water transport and functional dynamics of aquaporins in osmoregulatory organs of fishes

    DEFF Research Database (Denmark)

    Madsen, Steffen S; Engelund, Morten B; Cutler, Christopher P

    2015-01-01

    Aquaporins play distinct roles for water transport in fishes as they do in mammals-both at the cellular, organ, and organismal levels. However, with over 32,000 known species of fishes inhabiting almost every aquatic environment, from tidal pools, small mountain streams, to the oceans and extreme...... salty desert lakes, the challenge to obtain consensus as well as specific knowledge about aquaporin physiology in these vertebrate clades is overwhelming. Because the integumental surfaces of these animals are in intimate contact with the surrounding milieu, passive water loss and uptake represent two...... of the major osmoregulatory challenges that need compensation. However, neither obligatory nor regulatory water transport nor their mechanisms have been elucidated to the same degree as, for example, ion transport in fishes. Currently fewer than 60 papers address fish aquaporins. Most of these papers identify...

  6. Yeast aquaporin regulation by 4-hydroxynonenal is implicated in oxidative stress response.

    Science.gov (United States)

    Rodrigues, Claudia; Tartaro Bujak, Ivana; Mihaljević, Branka; Soveral, Graça; Cipak Gasparovic, Ana

    2017-05-01

    Reactive oxygen species, especially hydrogen peroxide (H 2 O 2 ), contribute to functional molecular impairment and cellular damage, but also are necessary in normal cellular metabolism, and in low doses play stimulatory role in cell proliferation and stress resistance. In parallel, reactive aldehydes such as 4-hydroxynonenal (HNE), are lipid peroxidation breakdown products which also contribute to regulation of numerous cellular processes. Recently, channeling of H 2 O 2 by some mammalian aquaporin isoforms has been reported and suggested to contribute to aquaporin involvement in cancer malignancies, although the mechanism by which these membrane water channels are implicated in oxidative stress is not clear. In this study, two yeast models with increased levels of membrane polyunsaturated fatty acids (PUFAs) and aquaporin AQY1 overexpression, respectively, were used to evaluate their interplay in cell's oxidative status. In particular, the aim of the study was to investigate if HNE accumulation could affect aquaporin function with an outcome in oxidative stress response. The data showed that induction of aquaporin expression by PUFAs results in increased water permeability in yeast membranes and that AQY1 activity is impaired by HNE. Moreover, AQY1 expression increases cellular sensitivity to oxidative stress by facilitating H 2 O 2 influx. On the other hand, AQY1 expression has no influence on the cellular antioxidant GSH levels and catalase activity. These results strongly suggest that aquaporins are important players in oxidative stress response and could contribute to regulation of cellular processes by regulation of H 2 O 2 influx. © 2017 IUBMB Life, 69(5):355-362, 2017. © 2017 International Union of Biochemistry and Molecular Biology.

  7. Effects of Proteoliposome Composition and Draw Solution Types on Separation Performance of Aquaporin-Based Proteoliposomes

    DEFF Research Database (Denmark)

    Zhao, Yang; Vararattanavech, Ardcharaporn; Li, Xuesong

    2013-01-01

    Aquaporins are a large family of water transport proteins in cell membranes. Their high water permeability and solute rejection make them potential building blocks for high-performance biomimetic membranes for desalination. In the current study, proteoliposomes were prepared using AquaporinZ from...... Escherichia coli cells, and their separation properties were characterized by stopped-flow measurements. The current study systematically investigated the effect of proteoliposome composition (lipid type, protein-to-lipid ratio (PLR), and the addition of cholesterol) on water permeability and NaCl retention...

  8. Aquaporin 11 insufficiency modulates kidney susceptibility to oxidative stress.

    Science.gov (United States)

    Atochina-Vasserman, Elena N; Biktasova, Asel; Abramova, Elena; Cheng, Dong-Sheng; Polosukhin, Vasiliy V; Tanjore, Harikrishna; Takahashi, Saki; Sonoda, Hiroko; Foye, Liberty; Venkov, Christo; Ryzhov, Sergey V; Novitskiy, Sergey; Shlonimskaya, Natalia; Ikeda, Masahiro; Blackwell, Timothy S; Lawson, William E; Gow, Andrew J; Harris, Raymond C; Dikov, Mikhail M; Tchekneva, Elena E

    2013-05-15

    Aquaporin 11 (AQP11) is a newly described member of the protein family of transport channels. AQP11 associates with the endoplasmic reticulum (ER) and is highly expressed in proximal tubular epithelial cells in the kidney. Previously, we identified and characterized a recessive mutation of the highly conserved Cys227 to Ser227 in mouse AQP11 that caused proximal tubule (PT) injury and kidney failure in mutant mice. The current study revealed induction of ER stress, unfolded protein response, and apoptosis as molecular mechanisms of this PT injury. Cys227Ser mutation interfered with maintenance of AQP11 oligomeric structure. AQP11 is abundantly expressed in the S1 PT segment, a site of major renal glucose flux, and Aqp11 mutant mice developed PT-specific mitochondrial injury. Glucose increased AQP11 protein expression in wild-type kidney and upregulation of AQP11 expression by glucose in vitro was prevented by phlorizin, an inhibitor of sodium-dependent glucose transport across PT. Total AQP11 levels in heterozygotes were higher than in wild-type mice but were not further increased in response to glucose. In Aqp11 insufficient PT cells, glucose potentiated increases in reactive oxygen species (ROS) production. ROS production was also elevated in Aqp11 mutation carriers. Phenotypically normal mice heterozygous for the Aqp11 mutation repeatedly treated with glucose showed increased blood urea nitrogen levels that were prevented by the antioxidant sulforaphane or by phlorizin. Our results indicate an important role for AQP11 to prevent glucose-induced oxidative stress in proximal tubules.

  9. Oxidative gating of water channels (aquaporins) in corn roots.

    Science.gov (United States)

    Ye, Qing; Steudle, Ernst

    2006-04-01

    An oxidative gating of water channels (aquaporins: AQPs) was observed in roots of corn seedlings as already found for the green alga Chara corallina. In the presence of 35 mM hydrogen peroxide (H2O2)--a precursor of hydroxyl radicals (*OH)--half times of water flow (as measured with the aid of pressure probes) increased at the level of both entire roots and individual cortical cells by factors of three and nine, respectively. This indicated decreases in the hydrostatic hydraulic conductivity of roots (Lp(hr)) and of cells (Lp(h)) by the same factors. Unlike other stresses, the plant hormone abscisic acid (ABA) had no ameliorative effect either on root LP(hr) or on cell Lp(h) when AQPs were inhibited by oxidative stress. Closure of AQPs reduced the permeability of acetone by factors of two in roots and 1.5 in cells. This indicated that AQPs were not ideally selective for water but allowed the passage of the organic solute acetone. In the presence of H2O2, channel closure caused anomalous (negative) osmosis at both the root and the cell level. This was interpreted by the fact that in the case of the rapidly permeating solute acetone, channel closure caused the solute to move faster than the water and the reflection coefficient (sigma s) reversed its sign. When H2O2 was removed from the medium, the effects were reversible, again at both the root and the cell level. The results provide evidence of oxidative gating of AQPs, which leads on to inhibition of water uptake by the roots. Possible mechanisms of the oxidative gating of AQPs induced by H2O2 (*OH) are discussed.

  10. Immunogenic potential of Rhipicephalus (Boophilus) microplus aquaporin 1 against Rhipicephalus sanguineus in domestic dogs

    Science.gov (United States)

    This study evaluated a recombinant aquaporin 1 protein of Rhipicephalus (Boophilus) microplus (RmAQP1) as antigen in a vaccine against R. sanguineus. Five dogs were immunized with RmAQP1 (10 µg) + adjuvant (Montanide) (G1), and five were inoculated with adjuvant only (G2), three times. Twenty-one da...

  11. Role of aquaporin activity in regulating deep and shallow root hydraulic conductance during extreme drought

    Science.gov (United States)

    Daniel M. Johnson; Mark E. Sherrard; Jean-Christophe Domec; Robert B. Jackson

    2014-01-01

    Key message Deep root hydraulic conductance is upregulated during severe drought and is associated with upregulation in aquaporin activity. Abstract In 2011, Texas experienced the worst single-year drought in its recorded history and, based on tree-ring data, likely itsworst in the pastmillennium. In the Edwards Plateau of Texas, rainfall was 58 % lower and the mean...

  12. Aquaporin-1 Expression in Retinal Pigment Epithelial Cells Overlying Retinal Drusen

    DEFF Research Database (Denmark)

    Tran, Thuy Linh; Bek, Toke; Dornonville de la Cour, Morten

    2016-01-01

    PURPOSE: In the outer retina, age-related macular degeneration (AMD) results in reduced hydraulic conductivity in Bruch's membrane, possibly leading to altered water transport in retinal pigment epithelial (RPE) cells. We hypothesize that RPE cells may express aquaporin-1 (AQP1) to compensate...

  13. Reversed polarized delivery of an aquaporin-2 mutant causes dominant nephrogenic diabetes insipidus.

    NARCIS (Netherlands)

    Kamsteeg, E.J.; Bichet, D.G.; Konings, I.B.M.; Nivet, H.; Lonergan, M.; Arthus, M.F.; Os, C.H. van; Deen, P.M.T.

    2003-01-01

    Vasopressin regulates body water conservation by redistributing aquaporin-2 (AQP2) water channels from intracellular vesicles to the apical surface of renal collecting ducts, resulting in water reabsorption from urine. Mutations in AQP2 cause autosomal nephrogenic diabetes insipidus (NDI), a disease

  14. Aquaporins of the PIP2 class are required for efficient anther dehiscence in tobacco

    NARCIS (Netherlands)

    Bots, M.L.; Vergeldt, F.J.; Wolters-Arts, M.; Weterings, K.; As, van H.; Mariani, C.

    2005-01-01

    Several processes during sexual reproduction in higher plants involve the movement of water between cells or tissues. Before flower anthesis, anther and pollen dehydration takes place before the release of mature pollen at dehiscence. Aquaporins represent a class of proteins that mediates the

  15. A precise spacing between the NPA domains of aquaporins is essential for silicon permeability in plants.

    Science.gov (United States)

    Deshmukh, Rupesh Kailasrao; Vivancos, Julien; Ramakrishnan, Gowsica; Guérin, Valérie; Carpentier, Gabriel; Sonah, Humira; Labbé, Caroline; Isenring, Paul; Belzile, Francois J; Bélanger, Richard R

    2015-08-01

    The controversy surrounding silicon (Si) benefits and essentiality in plants is exacerbated by the differential ability of species to absorb this element. This property is seemingly enhanced in species carrying specific nodulin 26-like intrinsic proteins (NIPs), a subclass of aquaporins. In this work, our aim was to characterize plant aquaporins to define the features that confer Si permeability. Through comparative analysis of 985 aquaporins in 25 species with differing abilities to absorb Si, we were able to predict 30 Si transporters and discovered that Si absorption is exclusively confined to species that possess NIP-III aquaporins with a GSGR selectivity filter and a precise distance of 108 amino acids (AA) between the asparagine-proline-alanine (NPA) domains. The latter feature is of particular significance since it had never been reported to be essential for Si selectivity. Functionality assessed in the Xenopus oocyte expression system showed that NIPs with 108 AA spacing exhibited Si permeability, while proteins differing in that distance did not. In subsequent functional studies, a Si transporter from poplar mutated into variants with 109- or 107-AA spacing failed to import, and a tomato NIP gene mutated from 109 to 108 AA exhibited a rare gain of function. These results provide a precise molecular basis to classify higher plants into Si accumulators or excluders. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  16. Characterization of V71M mutation in the aquaporin-2 gene causing ...

    Indian Academy of Sciences (India)

    ... Discussion Meetings · Public Lectures · Lecture Workshops · Refresher Courses · Symposia. Home; Journals; Journal of Genetics; Volume 87; Issue 3. Characterization of V71M mutation in the aquaporin-2 gene causing nephrogenic diabetes insipidus. N. Bougacha-Elleuch M. Ben Lassoued N. Miled S. Zouari H. Ayadi.

  17. Functionality of aquaporin-2 missense mutants in recessive nephrogenic diabetes insipidus.

    NARCIS (Netherlands)

    Marr, N.; Kamsteeg, E.J.; Raak, M.M.J.P. van; Os, C.H. van; Deen, P.M.T.

    2001-01-01

    Aquaporin-2 (AQP2) missense mutants in recessive nephrogenic diabetes insipidus (NDI) are all retained in the endoplasmic reticulum (ER), but some could function as water channels. No conclusions could be drawn about the water permeability (Pf) of others, because there was no method for quantifying

  18. The aquaporin-2 water channel in autosomal dominant primary nocturnal enuresis.

    NARCIS (Netherlands)

    Deen, P.M.T.; Dahl, N.; Caplan, M.J.

    2002-01-01

    PURPOSE: Nocturnal enuresis is one of the most common diagnoses in a pediatric clinic. Recently, linkage analysis revealed a 2-point lod score of 4.2 in 6 families with dominant primary nocturnal enuresis around the aquaporin-2 (AQP2) water channel locus. Since primary nocturnal enuresis is

  19. Fouling Characterization of Forward Osmosis Biomimetic Aquaporin Membranes Used for Water Recovery from Municipal Wastewater

    DEFF Research Database (Denmark)

    Zarebska, Agata; Petrinic, Irena; Hey, Tobias

    , organic, and biological fouling, membrane characterization is not a trivial task. The aim of this work is to characterize fouling of FO biomimetic aquaporin membranes during water recovery from municipal wastewater. Membrane fouling was characterized using Scanning Electron Microscopy, X-ray Dispersive...

  20. Demeclocycline Attenuates Hyponatremia by Reducing Aquaporin-2 Expression in the Renal Inner Medulla

    DEFF Research Database (Denmark)

    Kortenoeven, Marleen L. A.; Sinke, Anne P.; Hadrup, Niels

    2013-01-01

    Binding of vasopressin to its type-2 receptor in renal collecting ducts induces cAMP signaling, transcription and translocation of aquaporin-2 (AQP2) water channels to the plasma membrane and water reabsorption from the pro-urine. Demeclocycline is currently used to treat hyponatremia in patients...

  1. Apelin-13 as a novel target for intervention in secondary injury after traumatic brain injury

    Directory of Open Access Journals (Sweden)

    Hai-jun Bao

    2016-01-01

    Full Text Available The adipocytokine, apelin-13, is an abundantly expressed peptide in the nervous system. Apelin-13 protects the brain against ischemia/reperfusion injury and attenuates traumatic brain injury by suppressing autophagy. However, secondary apelin-13 effects on traumatic brain injury-induced neural cell death and blood-brain barrier integrity are still not clear. Here, we found that apelin-13 significantly decreases cerebral water content, mitigates blood-brain barrier destruction, reduces aquaporin-4 expression, diminishes caspase-3 and Bax expression in the cerebral cortex and hippocampus, and reduces apoptosis. These results show that apelin-13 attenuates secondary injury after traumatic brain injury and exerts a neuroprotective effect

  2. Two putative-aquaporin genes are differentially expressed during arbuscular mycorrhizal symbiosis in Lotus japonicus

    Science.gov (United States)

    2012-01-01

    Background Arbuscular mycorrhizas (AM) are widespread symbioses that provide great advantages to the plant, improving its nutritional status and allowing the fungus to complete its life cycle. Nevertheless, molecular mechanisms that lead to the development of AM symbiosis are not yet fully deciphered. Here, we have focused on two putative aquaporin genes, LjNIP1 and LjXIP1, which resulted to be upregulated in a transcriptomic analysis performed on mycorrhizal roots of Lotus japonicus. Results A phylogenetic analysis has shown that the two putative aquaporins belong to different functional families: NIPs and XIPs. Transcriptomic experiments have shown the independence of their expression from their nutritional status but also a close correlation with mycorrhizal and rhizobial interaction. Further transcript quantification has revealed a good correlation between the expression of one of them, LjNIP1, and LjPT4, the phosphate transporter which is considered a marker gene for mycorrhizal functionality. By using laser microdissection, we have demonstrated that one of the two genes, LjNIP1, is expressed exclusively in arbuscule-containing cells. LjNIP1, in agreement with its putative role as an aquaporin, is capable of transferring water when expressed in yeast protoplasts. Confocal analysis have demonstrated that eGFP-LjNIP1, under its endogenous promoter, accumulates in the inner membrane system of arbusculated cells. Conclusions Overall, the results have shown different functionality and expression specificity of two mycorrhiza-inducible aquaporins in L. japonicus. One of them, LjNIP1 can be considered a novel molecular marker of mycorrhizal status at different developmental stages of the arbuscule. At the same time, LjXIP1 results to be the first XIP family aquaporin to be transcriptionally regulated during symbiosis. PMID:23046713

  3. Hypercalcemia induces targeted autophagic degradation of aquaporin-2 at the onset of nephrogenic diabetes insipidus.

    Science.gov (United States)

    Khositseth, Sookkasem; Charngkaew, Komgrid; Boonkrai, Chatikorn; Somparn, Poorichaya; Uawithya, Panapat; Chomanee, Nusara; Payne, D Michael; Fenton, Robert A; Pisitkun, Trairak

    2017-05-01

    Hypercalcemia can cause renal dysfunction such as nephrogenic diabetes insipidus (NDI), but the mechanisms underlying hypercalcemia-induced NDI are not well understood. To elucidate the early molecular changes responsible for this disorder, we employed mass spectrometry-based proteomic analysis of inner medullary collecting ducts (IMCD) isolated from parathyroid hormone-treated rats at onset of hypercalcemia-induced NDI. Forty-one proteins, including the water channel aquaporin-2, exhibited significant changes in abundance, most of which were decreased. Bioinformatic analysis revealed that many of the downregulated proteins were associated with cytoskeletal protein binding, regulation of actin filament polymerization, and cell-cell junctions. Targeted LC-MS/MS and immunoblot studies confirmed the downregulation of 16 proteins identified in the initial proteomic analysis and in additional experiments using a vitamin D treatment model of hypercalcemia-induced NDI. Evaluation of transcript levels and estimated half-life of the downregulated proteins suggested enhanced protein degradation as the possible regulatory mechanism. Electron microscopy showed defective intercellular junctions and autophagy in the IMCD cells from both vitamin D- and parathyroid hormone-treated rats. A significant increase in the number of autophagosomes was confirmed by immunofluorescence labeling of LC3. Colocalization of LC3 and Lamp1 with aquaporin-2 and other downregulated proteins was found in both models. Immunogold electron microscopy revealed aquaporin-2 in autophagosomes in IMCD cells from both hypercalcemia models. Finally, parathyroid hormone withdrawal reversed the NDI phenotype, accompanied by termination of aquaporin-2 autophagic degradation and normalization of both nonphoshorylated and S256-phosphorylated aquaporin-2 levels. Thus, enhanced autophagic degradation of proteins plays an important role in the initial mechanism of hypercalcemic-induced NDI. Copyright © 2016

  4. The lineage-specific evolution of aquaporin gene clusters facilitated tetrapod terrestrial adaptation.

    Science.gov (United States)

    Finn, Roderick Nigel; Chauvigné, François; Hlidberg, Jón Baldur; Cutler, Christopher P; Cerdà, Joan

    2014-01-01

    A major physiological barrier for aquatic organisms adapting to terrestrial life is dessication in the aerial environment. This barrier was nevertheless overcome by the Devonian ancestors of extant Tetrapoda, but the origin of specific molecular mechanisms that solved this water problem remains largely unknown. Here we show that an ancient aquaporin gene cluster evolved specifically in the sarcopterygian lineage, and subsequently diverged into paralogous forms of AQP2, -5, or -6 to mediate water conservation in extant Tetrapoda. To determine the origin of these apomorphic genomic traits, we combined aquaporin sequencing from jawless and jawed vertebrates with broad taxon assembly of >2,000 transcripts amongst 131 deuterostome genomes and developed a model based upon Bayesian inference that traces their convergent roots to stem subfamilies in basal Metazoa and Prokaryota. This approach uncovered an unexpected diversity of aquaporins in every lineage investigated, and revealed that the vertebrate superfamily consists of 17 classes of aquaporins (Aqp0 - Aqp16). The oldest orthologs associated with water conservation in modern Tetrapoda are traced to a cluster of three aqp2-like genes in Actinistia that likely arose >500 Ma through duplication of an aqp0-like gene present in a jawless ancestor. In sea lamprey, we show that aqp0 first arose in a protocluster comprised of a novel aqp14 paralog and a fused aqp01 gene. To corroborate these findings, we conducted phylogenetic analyses of five syntenic nuclear receptor subfamilies, which, together with observations of extensive genome rearrangements, support the coincident loss of ancestral aqp2-like orthologs in Actinopterygii. We thus conclude that the divergence of sarcopterygian-specific aquaporin gene clusters was permissive for the evolution of water conservation mechanisms that facilitated tetrapod terrestrial adaptation.

  5. The lineage-specific evolution of aquaporin gene clusters facilitated tetrapod terrestrial adaptation.

    Directory of Open Access Journals (Sweden)

    Roderick Nigel Finn

    Full Text Available A major physiological barrier for aquatic organisms adapting to terrestrial life is dessication in the aerial environment. This barrier was nevertheless overcome by the Devonian ancestors of extant Tetrapoda, but the origin of specific molecular mechanisms that solved this water problem remains largely unknown. Here we show that an ancient aquaporin gene cluster evolved specifically in the sarcopterygian lineage, and subsequently diverged into paralogous forms of AQP2, -5, or -6 to mediate water conservation in extant Tetrapoda. To determine the origin of these apomorphic genomic traits, we combined aquaporin sequencing from jawless and jawed vertebrates with broad taxon assembly of >2,000 transcripts amongst 131 deuterostome genomes and developed a model based upon Bayesian inference that traces their convergent roots to stem subfamilies in basal Metazoa and Prokaryota. This approach uncovered an unexpected diversity of aquaporins in every lineage investigated, and revealed that the vertebrate superfamily consists of 17 classes of aquaporins (Aqp0 - Aqp16. The oldest orthologs associated with water conservation in modern Tetrapoda are traced to a cluster of three aqp2-like genes in Actinistia that likely arose >500 Ma through duplication of an aqp0-like gene present in a jawless ancestor. In sea lamprey, we show that aqp0 first arose in a protocluster comprised of a novel aqp14 paralog and a fused aqp01 gene. To corroborate these findings, we conducted phylogenetic analyses of five syntenic nuclear receptor subfamilies, which, together with observations of extensive genome rearrangements, support the coincident loss of ancestral aqp2-like orthologs in Actinopterygii. We thus conclude that the divergence of sarcopterygian-specific aquaporin gene clusters was permissive for the evolution of water conservation mechanisms that facilitated tetrapod terrestrial adaptation.

  6. Two putative-aquaporin genes are differentially expressed during arbuscular mycorrhizal symbiosis in Lotus japonicus

    Directory of Open Access Journals (Sweden)

    Giovannetti Marco

    2012-10-01

    Full Text Available Abstract Background Arbuscular mycorrhizas (AM are widespread symbioses that provide great advantages to the plant, improving its nutritional status and allowing the fungus to complete its life cycle. Nevertheless, molecular mechanisms that lead to the development of AM symbiosis are not yet fully deciphered. Here, we have focused on two putative aquaporin genes, LjNIP1 and LjXIP1, which resulted to be upregulated in a transcriptomic analysis performed on mycorrhizal roots of Lotus japonicus. Results A phylogenetic analysis has shown that the two putative aquaporins belong to different functional families: NIPs and XIPs. Transcriptomic experiments have shown the independence of their expression from their nutritional status but also a close correlation with mycorrhizal and rhizobial interaction. Further transcript quantification has revealed a good correlation between the expression of one of them, LjNIP1, and LjPT4, the phosphate transporter which is considered a marker gene for mycorrhizal functionality. By using laser microdissection, we have demonstrated that one of the two genes, LjNIP1, is expressed exclusively in arbuscule-containing cells. LjNIP1, in agreement with its putative role as an aquaporin, is capable of transferring water when expressed in yeast protoplasts. Confocal analysis have demonstrated that eGFP-LjNIP1, under its endogenous promoter, accumulates in the inner membrane system of arbusculated cells. Conclusions Overall, the results have shown different functionality and expression specificity of two mycorrhiza-inducible aquaporins in L. japonicus. One of them, LjNIP1 can be considered a novel molecular marker of mycorrhizal status at different developmental stages of the arbuscule. At the same time, LjXIP1 results to be the first XIP family aquaporin to be transcriptionally regulated during symbiosis.

  7. Two putative-aquaporin genes are differentially expressed during arbuscular mycorrhizal symbiosis in Lotus japonicus.

    Science.gov (United States)

    Giovannetti, Marco; Balestrini, Raffaella; Volpe, Veronica; Guether, Mike; Straub, Daniel; Costa, Alex; Ludewig, Uwe; Bonfante, Paola

    2012-10-09

    Arbuscular mycorrhizas (AM) are widespread symbioses that provide great advantages to the plant, improving its nutritional status and allowing the fungus to complete its life cycle. Nevertheless, molecular mechanisms that lead to the development of AM symbiosis are not yet fully deciphered. Here, we have focused on two putative aquaporin genes, LjNIP1 and LjXIP1, which resulted to be upregulated in a transcriptomic analysis performed on mycorrhizal roots of Lotus japonicus. A phylogenetic analysis has shown that the two putative aquaporins belong to different functional families: NIPs and XIPs. Transcriptomic experiments have shown the independence of their expression from their nutritional status but also a close correlation with mycorrhizal and rhizobial interaction. Further transcript quantification has revealed a good correlation between the expression of one of them, LjNIP1, and LjPT4, the phosphate transporter which is considered a marker gene for mycorrhizal functionality. By using laser microdissection, we have demonstrated that one of the two genes, LjNIP1, is expressed exclusively in arbuscule-containing cells. LjNIP1, in agreement with its putative role as an aquaporin, is capable of transferring water when expressed in yeast protoplasts. Confocal analysis have demonstrated that eGFP-LjNIP1, under its endogenous promoter, accumulates in the inner membrane system of arbusculated cells. Overall, the results have shown different functionality and expression specificity of two mycorrhiza-inducible aquaporins in L. japonicus. One of them, LjNIP1 can be considered a novel molecular marker of mycorrhizal status at different developmental stages of the arbuscule. At the same time, LjXIP1 results to be the first XIP family aquaporin to be transcriptionally regulated during symbiosis.

  8. Abnormal increase in urinary aquaporin-2 excretion in response to hypertonic saline in essential hypertension

    Directory of Open Access Journals (Sweden)

    Graffe Carolina

    2012-03-01

    Full Text Available Abstract Background Dysregulation of the expression/shuttling of the aquaporin-2 water channel (AQP2 and the epithelial sodium channel (ENaC in renal collecting duct principal cells has been found in animal models of hypertension. We tested whether a similar dysregulation exists in essential hypertension. Methods We measured urinary excretion of AQP2 and ENaC β-subunit corrected for creatinine (u-AQP2CR, u-ENaCβ-CR, prostaglandin E2 (u-PGE2 and cyclic AMP (u-cAMP, fractional sodium excretion (FENa, free water clearance (CH2O, as well as plasma concentrations of vasopressin (AVP, renin (PRC, angiotensin II (Ang II, aldosterone (Aldo, and atrial and brain natriuretic peptide (ANP, BNP in 21 patients with essential hypertension and 20 normotensive controls during 24-h urine collection (baseline, and after hypertonic saline infusion on a 4-day high sodium (HS diet (300 mmol sodium/day and a 4-day low sodium (LS diet (30 mmol sodium/day. Results At baseline, no differences in u-AQP2CR or u-ENaCβ-CR were measured between patients and controls. U-AQP2CR increased significantly more after saline in patients than controls, whereas u-ENaCβ-CR increased similarly. The saline caused exaggerated natriuretic increases in patients during HS intake. Neither baseline levels of u-PGE2, u-cAMP, AVP, PRC, Ang II, Aldo, ANP, and BNP nor changes after saline could explain the abnormal u-AQP2CR response. Conclusions No differences were found in u-AQP2CR and u-ENaCβ-CR between patients and controls at baseline. However, in response to saline, u-AQP2CR was abnormally increased in patients, whereas the u-ENaCβ-CR response was normal. The mechanism behind the abnormal AQP2 regulation is not clarified, but it does not seem to be AVP-dependent. Clinicaltrial.gov identifier NCT00345124.

  9. Neuromyelitis optica IgG and natural killer cells produce NMO lesions in mice without myelin loss.

    Science.gov (United States)

    Ratelade, Julien; Zhang, Hua; Saadoun, Samira; Bennett, Jeffrey L; Papadopoulos, Marios C; Verkman, A S

    2012-06-01

    The pathogenesis of neuromyelitis optica (NMO) involves targeting of NMO-immunoglobulin G (NMO-IgG) to aquaporin-4 (AQP4) on astrocytes in the central nervous system. Prior work provided evidence for complement-dependent cytotoxicity (CDC) in NMO lesion development. Here, we show that antibody-dependent cellular cytotoxicity (ADCC), in the absence of complement, can also produce NMO-like lesions. Antibody-dependent cellular cytotoxicity was produced in vitro by incubation of mouse astrocyte cultures with human recombinant monoclonal NMO-IgG and human natural killer cells (NK-cells). Injection of NMO-IgG and NK-cells in mouse brain caused loss of AQP4 and GFAP, two characteristic features of NMO lesions, but little myelin loss. Lesions were minimal or absent following injection of: (1) control (non-NMO) IgG with NK-cells; (2) NMO-IgG and NK-cells in AQP4-deficient mice; or (3) NMO-IgG and NK-cells in wild-type mice together with an excess of mutated NMO-IgG lacking ADCC effector function. NK-cells greatly exacerbated NMO lesions produced by NMO-IgG and complement in an ex vivo spinal cord slice model of NMO, causing marked myelin loss. NMO-IgG can thus produce astrocyte injury by ADCC in a complement-independent and dependent manner, suggesting the potential involvement of ADCC in NMO pathogenesis.

  10. The zebrafish genome encodes the largest vertebrate repertoire of functional aquaporins with dual paralogy and substrate specificities similar to mammals

    Directory of Open Access Journals (Sweden)

    Chauvigné François

    2010-02-01

    Full Text Available Abstract Background Aquaporins are integral membrane proteins that facilitate the transport of water and small solutes across cell membranes. These proteins are vital for maintaining water homeostasis in living organisms. In mammals, thirteen aquaporins (AQP0-12 have been characterized, but in lower vertebrates, such as fish, the diversity, structure and substrate specificity of these membrane channel proteins are largely unknown. Results The screening and isolation of transcripts from the zebrafish (Danio rerio genome revealed eighteen sequences structurally related to the four subfamilies of tetrapod aquaporins, i.e., aquaporins (AQP0, -1 and -4, water and glycerol transporters or aquaglyceroporins (Glps; AQP3 and AQP7-10, a water and urea transporter (AQP8, and two unorthodox aquaporins (AQP11 and -12. Phylogenetic analyses of nucleotide and deduced amino acid sequences demonstrated dual paralogy between teleost and human aquaporins. Three of the duplicated zebrafish isoforms have unlinked loci, two have linked loci, while DrAqp8 was found in triplicate across two chromosomes. Genomic sequencing, structural analysis, and maximum likelihood reconstruction, further revealed the presence of a putative pseudogene that displays hybrid exons similar to tetrapod AQP5 and -1. Ectopic expression of the cloned transcripts in Xenopus laevis oocytes demonstrated that zebrafish aquaporins and Glps transport water or water, glycerol and urea, respectively, whereas DrAqp11b and -12 were not functional in oocytes. Contrary to humans and some rodents, intrachromosomal duplicates of zebrafish AQP8 were water and urea permeable, while the genomic duplicate only transported water. All aquaporin transcripts were expressed in adult tissues and found to have divergent expression patterns. In some tissues, however, redundant expression of transcripts encoding two duplicated paralogs seems to occur. Conclusion The zebrafish genome encodes the largest repertoire of

  11. Voluntary Exercise Promotes Glymphatic Clearance of Amyloid Beta and Reduces the Activation of Astrocytes and Microglia in Aged Mice

    Directory of Open Access Journals (Sweden)

    Xiao-fei He

    2017-05-01

    Full Text Available Age is characterized by chronic inflammation, leading to synaptic dysfunction and dementia because the clearance of protein waste is reduced. The clearance of proteins depends partly on the permeation of the blood–brain barrier (BBB or on the exchange of water and soluble contents between the cerebrospinal fluid (CSF and the interstitial fluid (ISF. A wealth of evidence indicates that physical exercise improves memory and cognition in neurodegenerative diseases during aging, such as Alzheimer’s disease (AD, but the influence of physical training on glymphatic clearance, BBB permeability and neuroinflammation remains unclear. In this study, glymphatic clearance and BBB permeability were evaluated in aged mice using in vivo two-photon imaging. The mice performed voluntary wheel running exercise and their water-maze cognition was assessed; the expression of the astrocytic water channel aquaporin 4 (AQP4, astrocyte and microglial activation, and the accumulation of amyloid beta (Aβ were evaluated with immunofluorescence or an enzyme-linked immunosorbent assay (ELISA; synaptic function was investigated with Thy1–green fluorescent protein (GFP transgenic mice and immunofluorescent staining. Voluntary wheel running significantly improved water-maze cognition in the aged mice, accelerated the efficiency of glymphatic clearance, but which did not affect BBB permeability. The numbers of activated astrocytes and microglia decreased, AQP4 expression increased, and the distribution of astrocytic AQP4 was rearranged. Aβ accumulation decreased, whereas dendrites, dendritic spines and postsynaptic density protein (PSD95 increased. Our study suggests that voluntary wheel running accelerated glymphatic clearance but not BBB permeation, improved astrocytic AQP4 expression and polarization, attenuated the accumulation of amyloid plaques and neuroinflammation, and ultimately protected mice against synaptic dysfunction and a decline in spatial cognition

  12. Gene interference regulates aquaporin-4 expression in swollen tissue of rats with cerebral ischemic edema: Correlation with variation in apparent diffusion coefficient.

    Science.gov (United States)

    Hu, Hui; Lu, Hong; He, Zhanping; Han, Xiangjun; Chen, Jing; Tu, Rong

    2012-07-25

    To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquaporin-4 (control group) or siRNA- aquaporin-4 solution (1:800) (RNA interference group) into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25-6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5-4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson's correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient (r = -0.806, P coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracellular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.

  13. Water transport in brain:

    DEFF Research Database (Denmark)

    MacAulay, Nanna; Hamann, Steffan; Zeuthen, Thomas

    2004-01-01

    It is generally accepted that cotransporters transport water in addition to their normal substrates, although the precise mechanism is debated; both active and passive modes of transport have been suggested. The magnitude of the water flux mediated by cotransporters may well be significant: both...... the number of cotransporters per cell and the unit water permeability are high. For example, the Na(+)-glutamate cotransporter (EAAT1) has a unit water permeability one tenth of that of aquaporin (AQP) 1. Cotransporters are widely distributed in the brain and participate in several vital functions: inorganic......(+)-lactate cotransporters. We have previously determined water transport capacities for these cotransporters in model systems (Xenopus oocytes, cell cultures, and in vitro preparations), and will discuss their role in water homeostasis of the astroglial cell under both normo- and pathophysiologal situations. Astroglia...

  14. Structure of the formate transporter FocA reveals a pentameric aquaporin-like channel.

    Science.gov (United States)

    Wang, Yi; Huang, Yongjian; Wang, Jiawei; Cheng, Chao; Huang, Weijiao; Lu, Peilong; Xu, Ya-Nan; Wang, Pengye; Yan, Nieng; Shi, Yigong

    2009-11-26

    FocA is a representative member of the formate-nitrite transporter family, which transports short-chain acids in bacteria, archaea, fungi, algae and parasites. The structure and transport mechanism of the formate-nitrite transporter family remain unknown. Here we report the crystal structure of Escherichia coli FocA at 2.25 A resolution. FocA forms a symmetric pentamer, with each protomer consisting of six transmembrane segments. Despite a lack of sequence homology, the overall structure of the FocA protomer closely resembles that of aquaporin and strongly argues that FocA is a channel, rather than a transporter. Structural analysis identifies potentially important channel residues, defines the channel path and reveals two constriction sites. Unlike aquaporin, FocA is impermeable to water but allows the passage of formate. A structural and biochemical investigation provides mechanistic insights into the channel activity of FocA.

  15. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    DEFF Research Database (Denmark)

    Li, Zhenyu; Linares, Rodrigo Valladares; Bucs, Szilard

    2017-01-01

    based biomimetic membrane in simulated membrane cleaning processes. The effects of cleaning agents on water flux and salt rejection were evaluated. The membrane showed a good resistance to the chemical agents. The water flux after chemical cleaning showed significant increases, particularly after...... cleaning with NaOCl and Alconox. Changes in the membrane structure and increased hydrophilicity in the surrounding areas of the aquaporin may be accountable for the increase in water permeability. The membrane shows stable salt rejection up to 99% after all cleaning agents were tested. A 15-day experiment...... with secondary wastewater effluent as the feed solution and seawater as the draw solution showed a stable flux and high salt rejection. The average rejection of the dissolved organic carbon from wastewater after the 15-day test was 90%. The results demonstrated that the aquaporin based biomimetic FO membrane...

  16. Inhibition of the aquaporin 3 water channel increases the sensitivity of prostate cancer cells to cryotherapy

    Science.gov (United States)

    Ismail, M; Bokaee, S; Davies, J; Harrington, K J; Pandha, H

    2009-01-01

    Aquaporins (AQPs) are intrinsic membrane proteins that facilitate selective water and small solute movement across the plasma membrane. In this study, we investigate the role of inhibiting AQPs in sensitising prostate cancer cells to cryotherapy. PC-3 and DU145 prostate cancer cells were cooled to 0, −5 and −10°C. The expression of AQP3 in response to freezing was determined using real-time quantitative polymerase chain reaction (RT–qPCR) and western blot analysis. Aquaporins were inhibited using mercuric chloride (HgCl2) and small interfering RNA (siRNA) duplex, and cell survival was assessed using a colorimetric assay. There was a significant increase in AQP3 expression in response to freezing. Cells treated with AQP3 siRNA were more sensitive to cryoinjury compared with control cells (Pcryotherapy. PMID:19513079

  17. Kanglaite attenuates UVB-induced down-regulation of aquaporin-3 in cultured human skin keratinocytes

    Science.gov (United States)

    SHAN, SHI-JUN; XIAO, TING; CHEN, JOHN; GENG, SHI-LING; LI, CHANG-PING; XU, XUEGANG; HONG, YUXIAO; JI, CHAO; GUO, YING; WEI, HUACHEN; LIU, WEI; LI, DAPENG; CHEN, HONG-DUO

    2012-01-01

    Ultraviolet (UV) radiation plays an important role in the pathogenesis of skin photoaging. Depending on the wavelength of UV, the epidermis is affected primarily by UVB. One major characteristic of photoaging is the dehydration of the skin. Membrane-inserted water channels (aquaporins) are involved in this process. In this study we demonstrated that UVB radiation induced aquaporin-3 (AQP3) down-regulation in cultured human skin keratinocytes. Kanglaite is a mixture consisting of extractions of Coix Seed, which is an effective anti-neoplastic agent and can inhibit the activities of protein kinase C and NF-κB. We demonstrated that Kanglaite inhibited UVB-induced AQP3 down-regulation of cultured human skin keratinocytes. Our findings provide a potential new agent for anti-photoaging. The related molecular mechanisms remain to be further elucidated. PMID:22211241

  18. Cardiac Morphology and Function, and Blood Gas Transport in Aquaporin-1 Knockout Mice.

    Science.gov (United States)

    Al-Samir, Samer; Wang, Yong; Meissner, Joachim D; Gros, Gerolf; Endeward, Volker

    2016-01-01

    We have studied cardiac and respiratory functions of aquaporin-1-deficient mice by the Pressure-Volume-loop technique and by blood gas analysis. In addition, the morphological properties of the animals' hearts were analyzed. In anesthesia under maximal dobutamine stimulation, the mice exhibit a moderately elevated heart rate of technique yielded normal end-diastolic and end-systolic left ventricular volumes, the deficient hearts are characterized by thin ventricular walls in combination with normal intraventricular volumes. The aquaporin-1-deficient heart thus seems to be at a disadvantage compared to the wild-type heart by a reduced left-ventricular wall thickness and an increased diffusion distance between blood capillaries and muscle mitochondria. While under the present quasi-resting conditions these morphological alterations have no consequences for cardiac function, we expect that the deficient hearts will show a reduced maximal cardiac output.

  19. Bidirectional water fluxes and specificity for small hydrophilic molecules in aquaporins 0-5

    DEFF Research Database (Denmark)

    Meinild, A K; Klærke, Dan Arne; Zeuthen, T

    1998-01-01

    for the osmotic water permeability (L p) were obtained in swelling as in shrinkage experiments demonstrating, for the first time, that aquaporins are bidirectional. The reflection coefficients (¿) of urea, glycerol, acetamide, and formamide at 23¿°C were: AQP0: 1, 1, 0.8, 0.6; AQP1: 1, 0.8, 1, 1; AQP2: 1, 0.8, 1...

  20. Plant and animal aquaporins crosstalk: what can be revealed from distinct perspectives

    OpenAIRE

    Sutka, Moira; Amodeo, Gabriela; Ozu, Marcelo

    2017-01-01

    Aquaporins (AQPs) can be revisited from a distinct and complementary perspective: the outcome from analyzing them from both plant and animal studies. (1) The approach in the study. Diversity found in both kingdoms contrasts with the limited number of crystal structures determined within each group. While the structure of almost half of mammal AQPs was resolved, only a few were resolved in plants. Strikingly, the animal structures resolved are mainly derived from the AQP2-lineage, due to their...

  1. What Really Prevents Proton Transport through Aquaporin? Charge Self-Energy versus Proton Wire Proposals

    OpenAIRE

    Burykin, Anton; Warshel, Arieh

    2003-01-01

    The nature of the control of water/proton selectivity in biological channels is a problem of a fundamental importance. Most studies of this issue have proposed that an interference with the orientational requirements of the so-called proton wire is the source of selectivity. The elucidation of the structures of aquaporins, which have evolved to prevent proton transfer (PT), provided a clear benchmark for exploring the selectivity problem. Previous simulations of this system have not examined,...

  2. The Lineage-Specific Evolution of Aquaporin Gene Clusters Facilitated Tetrapod Terrestrial Adaptation

    OpenAIRE

    Finn, Roderick Nigel; Chauvigné, François; Hlidberg, Jón Baldur; Cutler, Christopher P.; Cerdà, Joan

    2014-01-01

    A major physiological barrier for aquatic organisms adapting to terrestrial life is dessication in the aerial environment. This barrier was nevertheless overcome by the Devonian ancestors of extant Tetrapoda, but the origin of specific molecular mechanisms that solved this water problem remains largely unknown. Here we show that an ancient aquaporin gene cluster evolved specifically in the sarcopterygian lineage, and subsequently diverged into paralogous forms of AQP2, -5, or -6 to mediate wa...

  3. The Role of Aquaporins in pH-Dependent Germination of Rhizopus delemar Spores.

    Science.gov (United States)

    Turgeman, Tidhar; Shatil-Cohen, Arava; Moshelion, Menachem; Teper-Bamnolker, Paula; Skory, Christopher D; Lichter, Amnon; Eshel, Dani

    2016-01-01

    Rhizopus delemar and associated species attack a wide range of fruit and vegetables after harvest. Host nutrients and acidic pH are required for optimal germination of R. delemar, and we studied how this process is triggered. Glucose induced spore swelling in an acidic environment, expressed by an up to 3-fold increase in spore diameter, whereas spore diameter was smaller in a neutral environment. When suspended in an acidic environment, the spores started to float, indicating a change in their density. Treatment of the spores with HgCl2, an aquaporin blocker, prevented floating and inhibited spore swelling and germ-tube emergence, indicating the importance of water uptake at the early stages of germination. Two putative candidate aquaporin-encoding genes-RdAQP1 and RdAQP2-were identified in the R. delemar genome. Both presented the conserved NPA motif and six-transmembrane domain topology. Expressing RdAQP1 and RdAQP2 in Arabidopsis protoplasts increased the cells' osmotic water permeability coefficient (Pf) compared to controls, indicating their role as water channels. A decrease in R. delemar aquaporin activity with increasing external pH suggested pH regulation of these proteins. Substitution of two histidine (His) residues, positioned on two loops facing the outer side of the cell, with alanine eliminated the pH sensing resulting in similar Pf values under acidic and basic conditions. Since hydration is critical for spore switching from the resting to activate state, we suggest that pH regulation of the aquaporins can regulate the initial phase of R. delemar spore germination, followed by germ-tube elongation and host-tissue infection.

  4. The Role of Aquaporins in pH-Dependent Germination of Rhizopus delemar Spores

    Science.gov (United States)

    Turgeman, Tidhar; Shatil-Cohen, Arava; Moshelion, Menachem; Teper-Bamnolker, Paula; Skory, Christopher D.; Lichter, Amnon; Eshel, Dani

    2016-01-01

    Rhizopus delemar and associated species attack a wide range of fruit and vegetables after harvest. Host nutrients and acidic pH are required for optimal germination of R. delemar, and we studied how this process is triggered. Glucose induced spore swelling in an acidic environment, expressed by an up to 3-fold increase in spore diameter, whereas spore diameter was smaller in a neutral environment. When suspended in an acidic environment, the spores started to float, indicating a change in their density. Treatment of the spores with HgCl2, an aquaporin blocker, prevented floating and inhibited spore swelling and germ-tube emergence, indicating the importance of water uptake at the early stages of germination. Two putative candidate aquaporin-encoding genes—RdAQP1 and RdAQP2—were identified in the R. delemar genome. Both presented the conserved NPA motif and six-transmembrane domain topology. Expressing RdAQP1 and RdAQP2 in Arabidopsis protoplasts increased the cells' osmotic water permeability coefficient (Pf) compared to controls, indicating their role as water channels. A decrease in R. delemar aquaporin activity with increasing external pH suggested pH regulation of these proteins. Substitution of two histidine (His) residues, positioned on two loops facing the outer side of the cell, with alanine eliminated the pH sensing resulting in similar Pf values under acidic and basic conditions. Since hydration is critical for spore switching from the resting to activate state, we suggest that pH regulation of the aquaporins can regulate the initial phase of R. delemar spore germination, followed by germ-tube elongation and host-tissue infection. PMID:26959825

  5. Brain vascular changes in Cockayne syndrome.

    Science.gov (United States)

    Hayashi, Masaharu; Miwa-Saito, Naho; Tanuma, Naoyuki; Kubota, Masaya

    2012-04-01

    Cockayne syndrome (CS) and xeroderma pigmentosum (XP) are caused by deficient nucleotide excision repair. CS is characterized by cachectic dwarfism, mental disability, microcephaly and progeria features. Neuropathological examination of CS patients reveals dysmyelination and basal ganglia calcification. In addition, arteriosclerosis in the brain and subdural hemorrhage have been reported in a few CS cases. Herein, we performed elastica van Gieson (EVG) staining and immunohistochemistry for collagen type IV, CD34 and aquaporin 4 to evaluate the brain vessels in autopsy cases of CS, XP group A (XP-A) and controls. Small arteries without arteriosclerosis in the subarachnoid space had increased in CS cases but not in either XP-A cases or controls. In addition, string vessels (twisted capillaries) in the cerebral white matter and increased density of CD34-immunoreactive vessels were observed in CS cases. Immunohistochemistry findings for aquaporin 4 indicated no pathological changes in either CS or XP-A cases. Hence, the increased subarachnoid artery space may have caused subdural hemorrhage. Since such vascular changes were not observed in XP-A cases, the increased density of vessels in CS cases was not caused by brain atrophy. Hence, brain vascular changes may be involved in neurological disturbances in CS. © 2011 Japanese Society of Neuropathology.

  6. Aquaporins and unloading of phloem-imported water in coats of developing bean seeds.

    Science.gov (United States)

    Zhou, Yuchan; Setz, Nathan; Niemietz, Christa; Qu, Hongxia; Offler, Christina E; Tyerman, Stephen D; Patrick, John W

    2007-12-01

    Nutrients are imported into developing legume seeds by mass flow through the phloem, and reach developing embryos following secretion from their symplasmically isolated coats. To sustain homeostasis of seed coat water relations, phloem-delivered nutrients and water must exit seed coats at rates commensurate with those of import through the phloem. In this context, coats of developing French bean seeds were screened for expression of aquaporin genes resulting in cloning PvPIP1;1, PvPIP2;2 and PvPIP2;3. These genes were differentially expressed in all vegetative organs, but exhibited their strongest expression in seed coats. In seed coats, expression was localized to cells of the nutrient-unloading pathway. Transport properties of the PvPIPs were characterized by expression in Xenopus oocytes. Only PvPIP2;3 showed significant water channel activity (Pos = 150-200 microm s(-1)) even when the plasma membrane intrinsic proteins (PIPs) were co-expressed in various combinations. Permeability increases to glycerol, methylamine and urea were not detected in oocytes expressing PvPIPs. Transport active aquaporins in native plasma membranes of seed coats were demonstrated by measuring rates of osmotic shrinkage of membrane vesicles in the presence and absence of mercuric chloride and silver nitrate. The functional significance of aquaporins in nutrient and water transport in developing seeds is discussed.

  7. Dynamics and energetics of permeation through aquaporins. What do we learn from molecular dynamics simulations?

    Science.gov (United States)

    Hub, Jochen S; Grubmüller, Helmut; de Groot, Bert L

    2009-01-01

    Aquaporins (AQPs) are a family of integral membrane proteins, which facilitate the rapid and yet highly selective flux of water and other small solutes across biological membranes. Molecular dynamics (MD) simulations contributed substantially to the understanding of the molecular mechanisms that underlie this remarkable efficiency and selectivity of aquaporin channels. This chapter reviews the current state of MD simulations of aquaporins and related aquaglyceroporins as well as the insights these simulations have provided. The mechanism of water permeation through AQPs and methods to determine channel permeabilities from simulations are described. Protons are strictly excluded from AQPs by a large electrostatic barrier and not by an interruption of the Grotthuss mechanism inside the pore. Both the protein's electric field and desolvation effects contribute to this barrier. Permeation of apolar gas molecules such as CO(2) through AQPs is accompanied by a large energetic barrier and thus can only be expected in membranes with a low intrinsic gas permeability. Additionally, the insights from simulations into the mechanism of glycerol permeation through the glycerol facilitator GlpF from E. coli are summarized. Finally, MD simulations are discussed that revealed that the aro-matic/arginine constriction region is generally the filter for uncharged solutes, and that AQP selectivity is controlled by a hydrophobic effect and steric restraints.

  8. Silicon-mediated Improvement in Plant Salinity Tolerance: The Role of Aquaporins

    Directory of Open Access Journals (Sweden)

    Juan J. Rios

    2017-06-01

    Full Text Available Silicon (Si is an abundant and differentially distributed element in soils that is believed to have important biological functions. However, the benefits of Si and its essentiality in plants are controversial due to differences among species in their ability to take up this element. Despite this, there is a consensus that the application of Si improves the water status of plants under abiotic stress conditions. Hence, plants treated with Si are able to maintain a high stomatal conductance and transpiration rate under salt stress, suggesting that a reduction in Na+ uptake occurs due to deposition of Si in the root. In addition, root hydraulic conductivity increases when Si is applied. As a result, a Si-mediated upregulation of aquaporin (PIP gene expression is observed in relation to increased root hydraulic conductivity and water uptake. Aquaporins of the subclass nodulin 26-like intrinsic proteins are further involved in allowing Si entry into the cell. Therefore, on the basis of available published results and recent developments, we propose a model to explain how Si absorption alleviates stress in plants grown under saline conditions through the conjugated action of different aquaporins.

  9. NH3 and NH4+ permeability in aquaporin-expressing Xenopus oocytes

    DEFF Research Database (Denmark)

    Holm, Lars M.; Jahn, Thomas Paul; Møller, Anders Laurell Blom

    2005-01-01

    We have shown recently, in a yeast expression system, that some aquaporins are permeable to ammonia. In the present study, we expressed the mammalian aquaporins AQP8, AQQP9, AQP3, AQP1 and a plant aquaporin TIP2;1 in Xenopus oocytes to study the transport of ammonia (NH3) and ammonium (NH4+) under...... opencircuit and voltage-clamped conditions. TIP2;1 was tested as the wild-type and in a mutated version (tip2;1) in which the water permeability is intact. When AQP8-, AQP9-, AQP3- and TIP2;1-expressing oocytes were placed in a well-stirred bathing medium of low buffer capacity, NH3 permeability was evident...... from the acidification of the bathing medium; the effects observed with AQP1 and tip2;1 did not exceed that of native oocytes. AQP8, AQP9, AQP3, and TIP2;1 were permeable to larger amides, while AQP1 was not. Under voltage-clamp conditions, given sufficient NH3, AQP8, AQP9, AQP3, and TIP2;1 supported...

  10. The gating mechanism of the human aquaporin 5 revealed by molecular dynamics simulations.

    Directory of Open Access Journals (Sweden)

    Lorant Janosi

    Full Text Available Aquaporins are protein channels located across the cell membrane with the role of conducting water or other small sugar alcohol molecules (aquaglyceroporins. The high-resolution X-ray structure of the human aquaporin 5 (HsAQP5 shows that HsAQP5, as all the other known aquaporins, exhibits tetrameric structure. By means of molecular dynamics simulations we analyzed the role of spontaneous fluctuations on the structural behavior of the human AQP5. We found that different conformations within the tetramer lead to a distribution of monomeric channel structures, which can be characterized as open or closed. The switch between the two states of a channel is a tap-like mechanism at the cytoplasmic end which regulates the water passage through the pore. The channel is closed by a translation of the His67 residue inside the pore. Moreover, water permeation rate calculations revealed that the selectivity filter, located at the other end of the channel, regulates the flow rate of water molecules when the channel is open, by locally modifying the orientation of His173. Furthermore, the calculated permeation rates of a fully open channel are in good agreement with the reported experimental value.

  11. Investigation of age-related changes in the expression of aquaporin-1 and aquaporin-5 in the salivary glands of mice.

    Science.gov (United States)

    Sapmaz, Emrah; Uysal, Murat; Tumer, Mehmet Kemal; Sapmaz, Hilal Irmak; Somuk, Battal Tahsin; Arici, Akgul; Tas, Ufuk

    2016-09-01

    The increased AQP5 expression associated with ageing in glands, which mainly secreted a serous solution, suggests a compensation for the decreased amount of saliva secretion associated with age progression. To investigate the change in aquaporin-1 (AQP1) and aquaporin-5 (AQP5) expression in the salivary glands in young and elder mice. Twelve female mice from the Balb/C genus (30-50 g) were used. The mice were separated into two groups: Group I had 2-month-old mice and Group II had 18-month-old mice. Salivary glands (glandula parotidea, glandula sublungualis, glandula submaxillaris) were excised and examined immunohistochemically and histopathologically. AQP1 and AQP5 expression of young and elder mice was evaluated using the H-score. A p-value less than 0.05 was considered statistically significant. Upon histopathological examination, the acini of glands were found to be atrophic in elder mice. The number and diameter of intercalated ducts were increased. Indeed, the amount of adipose tissue in the gland was increased. Upon immunohistochemical examination, both AQP1 and AQP5 levels in sublingual glands of elder mice were increased (p gland of elder mice (p < 0.01).

  12. Synthesis of robust and high-performance aquaporin-based biomimetic membranes by interfacial polymerization-membrane preparation and RO performance characterization

    DEFF Research Database (Denmark)

    Zhao, Yang; Qiu, Changquan; Li, Xuesong

    2012-01-01

    Aquaporins are water channel proteins with excellent water permeability and solute rejection, which makes them promising for preparing high-performance biomimetic membranes. Despite the growing interest in aquaporin-based biomimetic membranes (ABMs), it is challenging to produce robust and defect...

  13. Aquaporin genes GintAQPF1 and GintAQPF2 from Glomus intraradices contribute to plant drought tolerance

    Science.gov (United States)

    Li, Tao; Hu, Ya-Jun; Hao, Zhi-Peng; Li, Hong; Chen, Bao-Dong

    2013-01-01

    Arbuscular mycorrhizal (AM) symbiosis, established between AM fungi (AMF) and roots of higher plants, occurs in most terrestrial ecosystems. It has been well demonstrated that AM symbiosis can improve plant performance under various environmental stresses, including drought stress. However, the molecular basis for the direct involvement of AMF in plant drought tolerance has not yet been established. Most recently, we cloned two functional aquaporin genes, GintAQPF1 and GintAQPF2, from AM fungus Glomus intraradices. By heterologous gene expression in yeast, aquaporin localization, activities and water permeability were examined. Gene expressions during symbiosis in expose to drought stress were also analyzed. Our data strongly supported potential water transport via AMF to host plants. As a complement, here we adopted the monoxenic culture system for AMF, in which carrot roots transformed by Ri-T DNA were cultured with Glomus intraradices in two-compartment Petri dishes, to verify the aquaporin gene functions in assisting AMF survival under polyethylene glycol (PEG) treatment. Our results showed that 25% PEG significantly upregulated the expression of two aquaporin genes, which was in line with the gene functions examined in yeast. We therefore concluded that the aquaporins function similarly in AMF as in yeast subjected to osmotic stress. The study provided further evidence to the direct involvement of AMF in improving plant water relations under drought stresses. PMID:23435173

  14. Functional and transcriptional induction of aquaporin-1 gene by hypoxia; analysis of promoter and role of Hif-1α.

    Directory of Open Access Journals (Sweden)

    Irene Abreu-Rodríguez

    Full Text Available Aquaporin-1 (AQP1 is a water channel that is highly expressed in tissues with rapid O(2 transport. It has been reported that this protein contributes to gas permeation (CO(2, NO and O(2 through the plasma membrane. We show that hypoxia increases Aqp1 mRNA and protein levels in tissues, namely mouse brain and lung, and in cultured cells, the 9L glioma cell line. Stopped-flow light-scattering experiments confirmed an increase in the water permeability of 9L cells exposed to hypoxia, supporting the view that hypoxic Aqp1 up-regulation has a functional role. To investigate the molecular mechanisms underlying this regulatory process, transcriptional regulation was studied by transient transfections of mouse endothelial cells with a 1297 bp 5' proximal Aqp1 promoter-luciferase construct. Incubation in hypoxia produced a dose- and time-dependent induction of luciferase activity that was also obtained after treatments with hypoxia mimetics (DMOG and CoCl(2 and by overexpressing stabilized mutated forms of HIF-1α. Single mutations or full deletions of the three putative HIF binding domains present in the Aqp1 promoter partially reduced its responsiveness to hypoxia, and transfection with Hif-1α siRNA decreased the in vitro hypoxia induction of Aqp1 mRNA and protein levels. Our results indicate that HIF-1α participates in the hypoxic induction of AQP1. However, we also demonstrate that the activation of Aqp1 promoter by hypoxia is complex and multifactorial and suggest that besides HIF-1α other transcription factors might contribute to this regulatory process. These data provide a conceptual framework to support future research on the involvement of AQP1 in a range of pathophysiological conditions, including edema, tumor growth, and respiratory diseases.

  15. Urine Aquaporin-2: A Promising Marker of Response to the Arginine Vasopressin Type-2 Antagonist, Tolvaptan in Patients with Congestive Heart Failure

    Directory of Open Access Journals (Sweden)

    Teruhiko Imamura

    2016-01-01

    Full Text Available Aquaporin-2, a member of the aquaporin family, is an arginine vasopressin-regulated water channel expressed in the renal collecting duct, and a promising marker of the concentrating and diluting ability of the kidney. The arginine vasopressin type-2 antagonist, tolvaptan, is a new-generation diuretic; it is especially indicated in patients with decompensated heart failure refractory to conventional diuretics. However, the ideal responders to tolvaptan have not yet been identified, and non-responders experience worse clinical courses despite treatment with tolvaptan. Urine aquaporin-2 has recently been demonstrated as a promising predictor of response to tolvaptan. We here validated aquaporin-2-guided tolvaptan therapy in patients with decompensated heart failure. Long-term efficacy of tolvaptan treatment in the responders defined by aquaporin-2 needs to be validated in the future prospective study.

  16. Expression of CXCL4 and aquaporin 3 and 10 mRNAs in patients with otitis media with effusion.

    Science.gov (United States)

    Jin, Zhe; Cha, Sung Ho; Choi, Yong-Sung; Kim, Young Il; Choi, Sun A; Yeo, Seung Geun

    2016-02-01

    Bacterial infections in children with underdeveloped Eustachian tubes are a major cause of otitis media with effusion (OEM), and persistent effusion in the middle ear in these patients is a major cause of surgical intervention. CXCL4 is associated with bacterial infection, and aquaporins 3 and 10 are associated with water metabolism. This study assessed the expression of mRNAs encoding CXCL-4 and aquaporins 3 and 10 in the effusion of pediatric OME patients, and the association of this expression with clinical manifestations. Levels of CXCL4 and aquaporin 3 and 10 mRNA were assayed by real-time RT-PCR in the middle ear effusion of 38 pediatric patients with OME requiring ventilation tube insertion. The relationships of these mRNA levels with the presence of bacteria; concomitant diseases such as allergic rhinitis, sinusitis, and adenoid disease; recurrence of OME; and number of ventilation tube insertions were evaluated. CXCL4 and aquaporin 3 and 10 mRNAs were expressed in middle ear effusion of all OME patients. CXCL-4 mRNA levels were significantly lower when bacteria were present and in patients with concomitant diseases (p0.05 each). The levels of CXCL4 and aquaporin 10 mRNAs were significantly correlated (p<0.05). Expression of CXCL4 and aquaporin 3 and 10 mRNAs in middle ear effusion is associated with the pathophysiology of OME. CXCL4 mRNA levels are significantly lower in patients with than without concomitant diseases or bacterial infections. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Medical Devices; Immunology and Microbiology Devices; Classification of the Aquaporin-4 Autoantibody Immunological Test System. Final order.

    Science.gov (United States)

    2017-10-30

    The Food and Drug Administration (FDA or we) is classifying the Aquaporin-4 autoantibody immunological test system into class II (special controls). The special controls that apply to the device type are identified in this order and will be part of the codified language for the Aquaporin-4 autoantibody immunological test system's classification. We are taking this action because we have determined that classifying the device into class II (special controls) will provide a reasonable assurance of safety and effectiveness of the device. We believe this action will also enhance patients' access to beneficial innovative devices, in part by reducing regulatory burdens.

  18. Prognostic Significance of Aquaporin 5 Expression in Non-small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Young Min Jo

    2016-03-01

    Full Text Available Background: Aquaporins are water channel proteins that play a major role in the movement of water in various human tissues. Recently, it has been found that aquaporins have influence in the carcinogenesis of human malignancies. We analyzed the prognostic impact of aquaporin 5 (AQP5 in non-small lung cancer (NSCLC. Methods: Seventy-six cases of NSCLC were studied, including 44 cases of adenocarcinoma (ADC and 32 cases of squamous cell carcinoma (SQCC. Tissue microarray was constructed and immunohistochemical staining for AQP5 was performed. Results: AQP5 was positive in 59.2% of the total enrolled NSCLCs (63.7% in ADC and 53.1% in SQCC. The difference in expression of AQP5 according to the histologic grade of the tumor was significant (p<.047, but not in a serial order. When ADC and SQCC were separately evaluated, no significant difference was observed according to the histologic grade of the tumor (p=.076 in ADC and p=.631 in SQCC. No difference was observed between AQP5 expression and other demographic data and tumor characteristics. Disease-free survival (DFS was higher in AQP5 negative cases than positive cases in ADC (p=.047, but no significance was found in SQCC (p=.068. We were unable to find a significance between AQP5 overexpression and overall survival in either ADC (p=.210 or SQCC (p=.533. Conclusions: AQP5 expression is associated with DFS in ADC of the lung and tumor grade of NSCLC. The present study suggests that AQP5 can be a prognostic factor of NSCLC.

  19. In vivo studies of aquaporins 3 and 10 in human stratum corneum

    DEFF Research Database (Denmark)

    Jungersted, Jakob Mutanu; Bomholt, Julie; Bajraktari, Niada

    2013-01-01

    Aquaporins (AQPs) constitute one family of transmembrane proteins facilitating transport of water across cell membranes. Due to their specificity, AQPs have a broad spectrum of physiological functions, and for keratinocytes there are indications that these channel proteins are involved in cell...... by AQP3 and AQP10 antibodies. In conclusion, identification of AQP3 and AQP10 protein in SC in an in vivo model is new. Together with the new “minimal-invasive” method for SC collection presented, this opens for new possibilities to study the role of AQPs in relation to function of the skin barrier....

  20. The water channel aquaporin-1 contributes to renin cell recruitment during chronic stimulation of renin production

    DEFF Research Database (Denmark)

    Tinning, Anne Robdrup; Jensen, Boye L; Schweda, Frank

    2014-01-01

    Processing and release of secretory granules involve water movement across granule membranes. It was hypothesized that the water channel aquaporin-1 (AQP-1) contributes directly to recruitment of renin-positive cells in the afferent arteriole. AQP1(-/-) and (+/+) mice were fed a low NaCl diet (LS......, 0.004% w/w) for 7 days and given enalapril (ACEI, 0.1 mg/ml) in the drinking water for 3 days. There were no differences in plasma renin concentration at baseline. After LS-ACEI, plasma renin concentration increased markedly in both genotypes but was significantly lower in AQP1(-/-) compared...

  1. Renal aquaporins and sodium transporters with special focus on urinary tract obstruction

    DEFF Research Database (Denmark)

    Frøkiaer, Jørgen; Li, Chunling; Shi, Yimin

    2003-01-01

    of NaCl. The major sodium transporters and channels in the individual renal tubule segments have been identified and the regulation of these transporters and channels are fundamental for renal sodium reabsorption and for establishing the driving force. In this mini-review the role of renal aquaporins...... and sodium transporters and channels is briefly described and their key role for the impaired urinary concentrating capacity in response to urinary tract obstruction is reviewed. Thus this review updates previous detailed reviews (1-5)....

  2. Cardiac Morphology and Function, and Blood Gas Transport in Aquaporin-1 Knockout Mice

    OpenAIRE

    Samer eAl-Samir; Yong eWang; Joachim D Meißner; Gerolf eGros; Volker eEndeward

    2016-01-01

    We have studied cardiac and respiratory functions of aquaporin-1-deficient mice by the Pressure-Volume-loop technique and by blood gas analysis. In addition, the morphological properties of the animals' hearts were analyzed. In anesthesia under maximal dobutamine stimulation, the mice exhibit a moderately elevated heart rate of < 600 min−1 and an O2 consumption of ~0.6 ml/min/g, which is about twice the basal rate. In this state, which is similar to the resting state of the conscious animal, ...

  3. Chronic noradrenaline increases renal expression of NHE-3, NBC-1, BSC-1 and aquaporin-2.

    Science.gov (United States)

    Sonalker, Prajakta A; Tofovic, Stevan P; Bastacky, Sheldon I; Jackson, Edwin K

    2008-05-01

    1. Because chronic activation of the renal sympathetic nervous system promotes sodium and water retention, it is conceivable that long-term exposure of the kidney to the sympathetic neurotransmitter noradrenaline upregulates the expression of key renal epithelial transport systems. 2. To test this hypothesis, we used immunoblotting of renal cortical and medullary tissue to investigate the abundance of major transport systems expressed along the renal tubule in response to long-term (15 days) infusions of noradrenaline (600 ng/min) in rats. 3. Mean arterial blood pressure and heart rate were significantly elevated in rats receiving chronic infusions of noradrenaline (128 +/- 10 mmHg and 492 +/- 16 b.p.m., respectively) compared with animals treated with saline only (89 +/- 3 mmHg and 376 +/- 14 b.p.m., respectively). 4. Chronic infusions of noradrenaline also increased the protein abundance of the cortical Na(+)/H(+) exchanger isoform 3 (NHE-3; 2.5-fold; P = 0.0142), the cortical sodium-bicarbonate cotransporter NBC-1 (2.5-fold; P = 0.0067), the bumetanide-sensitive sodium-potassium-chloride cotransporter BSC-1/NKCC2 in the inner stripe of outer medulla (threefold; P = 0.0020) and aquaporin-2 in the inner medulla (twofold; P = 0.0039). 5. In contrast, noradrenaline did not significantly affect expression of the thiazide-sensitive Na(+)-Cl(-) cotransporter in the cortex, Na(+)/K(+)-ATPase-alpha(1) in the cortex and inner stripe of the outer or inner medulla, the inwardly rectifying K(+) channel (ROMK-1) in the inner stripe of the outer medulla or aquaporin-1 in the cortex or inner medulla. Noradrenaline did significantly, but modestly (less than twofold), increase aquaporin-1 in the inner stripe of the outer medulla. 6. We conclude that noradrenaline-induced increases in the expression of NHE-3, NBC-1, BSC-1 and aquaporin-2 are likely to play an important role in the regulation of salt and water transport by noradrenaline in the kidney and may explain, at least in

  4. Convergence spasm due to aquaporin-positive neuromyelitis optica spectrum disorder

    Directory of Open Access Journals (Sweden)

    Pınar Özçelik

    2017-06-01

    Full Text Available A female 27 presented with nausea and diplopia for 1 week. On examination she had normal vertical gaze but would develop convergence with miosis whenever she made horizontal saccades. Pupils were 6 mm and unreactive to light. MRI showed extensive hyperintensity in the dorsal midbrain and thalamus. Spinal MRI and CSF were both normal. Serum aquaporin-4-antibody was positive. She was treated with steroids and plasmapheresis and after 3 months convergence spasm resolved but pupils remained unreactive. Neuromyelitis optica often presents with brainstem signs, rarely a dorsal midbrain syndrome. Convergence spasm is occasionally of organic neurologic origin.

  5. Concerted action of two cation filters in the aquaporin water channel

    DEFF Research Database (Denmark)

    Wu, Binghua; Steinbronn, Christina; Alsterfjord, Magnus

    2009-01-01

    Aquaporin (AQP) facilitated water transport is common to virtually all cell membranes and is marked by almost perfect specificity and high flux rates. Simultaneously, protons and cations are strictly excluded to maintain ionic transmembrane gradients. Yet, the AQP cation filters have not been...... identified experimentally. We report that three point mutations turned the water-specific AQP1 into a proton/alkali cation channel with reduced water permeability and the permeability sequence: H(+) >>K(+) >Rb(+) >Na(+) >Cs(+) >Li(+). Contrary to theoretical models, we found that electrostatic repulsion...

  6. Requirement for asparagine in the aquaporin NPA sequence signature motifs for cation exclusion

    DEFF Research Database (Denmark)

    Wree, Dorothea; Wu, Binghua; Zeuthen, Thomas

    2011-01-01

    Two highly conserved NPA motifs are a hallmark of the aquaporin (AQP) family. The NPA triplets form N-terminal helix capping structures with the Asn side chains located in the centre of the water or solute-conducting channel, and are considered to play an important role in AQP selectivity. Although...... electrophysiology, we found that an analogous mammalian AQP1 N76S mutant excluded protons and potassium ions, but leaked sodium ions, providing an argument for the overwhelming prevalence of Asn over other amino acids. We conclude that, at the first position in the NPA motifs, only Asn provides efficient helix cap...

  7. New insights into the regulation of aquaporins by the arbuscular mycorrhizal symbiosis in maize plants under drought stress and possible implications for plant performance.

    Science.gov (United States)

    Bárzana, Gloria; Aroca, Ricardo; Bienert, Gerd Patrick; Chaumont, François; Ruiz-Lozano, Juan Manuel

    2014-04-01

    The relationship between modulation by arbuscular mycorrhizae (AM) of aquaporin expression in the host plant and changes in root hydraulic conductance, plant water status, and performance under stressful conditions is not well known. This investigation aimed to elucidate how the AM symbiosis modulates the expression of the whole set of aquaporin genes in maize plants under different growing and drought stress conditions, as well as to characterize some of these aquaporins in order to shed further light on the molecules that may be involved in the mycorrhizal responses to drought. The AM symbiosis regulated a wide number of aquaporins in the host plant, comprising members of the different aquaporin subfamilies. The regulation of these genes depends on the watering conditions and the severity of the drought stress imposed. Some of these aquaporins can transport water and also other molecules which are of physiological importance for plant performance. AM plants grew and developed better than non-AM plants under the different conditions assayed. Thus, for the first time, this study relates the well-known better performance of AM plants under drought stress to not only the water movement in their tissues but also the mobilization of N compounds, glycerol, signaling molecules, or metalloids with a role in abiotic stress tolerance. Future studies should elucidate the specific function of each aquaporin isoform regulated by the AM symbiosis in order to shed further light on how the symbiosis alters the plant fitness under stressful conditions.

  8. A novel mutation affecting the arginine-137 residue of AVPR2 in dizygous twins leads to nephrogenic diabetes insipidus and attenuated urine exosome aquaporin-2

    DEFF Research Database (Denmark)

    Hinrichs, Gitte R; Hansen, Louise H; Nielsen, Maria R

    2016-01-01

    Mutations in the vasopressin V2 receptor gene AVPR2 may cause X-linked nephrogenic diabetes insipidus by defective apical insertion of aquaporin-2 in the renal collecting duct principal cell. Substitution mutations with exchange of arginine at codon 137 can cause nephrogenic syndrome of inappropr...... administration. While a similar urine exosome release rate was shown between probands and controls by western blotting for the marker ALIX, there was a selective decrease in exosome aquaporin-2 versus aquaporin-1 protein in probands compared to controls....

  9. Downregulation of aquaporin-1 in alveolar microvessels in lungs adapted to chronic heart failure

    DEFF Research Database (Denmark)

    Müllertz, Katrine M; Strøm, Claes; Trautner, Simon

    2011-01-01

    The threshold pressure for lung edema formation is increased in severe chronic heart failure (CHF) due to reduced microvascular permeability. The water channel aquaporin-1 (AQP1) is present in the pulmonary microvascular endothelium, and a number of studies suggest the importance of AQP1 as a mol......The threshold pressure for lung edema formation is increased in severe chronic heart failure (CHF) due to reduced microvascular permeability. The water channel aquaporin-1 (AQP1) is present in the pulmonary microvascular endothelium, and a number of studies suggest the importance of AQP1......-ligated rats (24 h: 58 ± 5% of sham; 3 weeks: 8 ± 3% of sham; 9 weeks: 16 ± 6% of sham) and after AB (30 weeks: 37 ± 5% of sham), whereas the protein levels of the specific endothelial cell marker PECAM-1 was increased 3 weeks after LAD ligation (229 ± 20% of sham), but unchanged after 9 weeks and in the AB...

  10. Rapid shoot-to-root signalling regulates root hydraulic conductance via aquaporins.

    Science.gov (United States)

    Vandeleur, Rebecca K; Sullivan, Wendy; Athman, Asmini; Jordans, Charlotte; Gilliham, Matthew; Kaiser, Brent N; Tyerman, Stephen D

    2014-02-01

    We investigated how root hydraulic conductance (normalized to root dry weight, Lo ) is regulated by the shoot. Shoot topping (about 30% reduction in leaf area) reduced Lo of grapevine (Vitis vinifera L.), soybean (Glycine max L.) and maize (Zea mays L.) by 50 to 60%. More detailed investigations with soybean and grapevine showed that the reduction in Lo was not correlated with the reduction in leaf area, and shading or cutting single leaves had a similar effect. Percentage reduction in Lo was largest when initial Lo was high in soybean. Inhibition of Lo by weak acid (low pH) was smaller after shoot damage or leaf shading. The half time of reduction in Lo was approximately 5 min after total shoot decapitation. These characteristics indicate involvement of aquaporins. We excluded phloem-borne signals and auxin-mediated signals. Xylem-mediated hydraulic signals are possible since turgor rapidly decreased within root cortex cells after shoot topping. There was a significant reduction in the expression of several aquaporins in the plasma membrane intrinsic protein (PIP) family of both grapevine and soybean. In soybean, there was a five- to 10-fold reduction in GmPIP1;6 expression over 0.5-1 h which was sustained over the period of reduced Lo . © 2013 John Wiley & Sons Ltd.

  11. Regulation of Arabidopsis leaf hydraulics involves light-dependent phosphorylation of aquaporins in veins.

    Science.gov (United States)

    Prado, Karine; Boursiac, Yann; Tournaire-Roux, Colette; Monneuse, Jean-Marc; Postaire, Olivier; Da Ines, Olivier; Schäffner, Anton R; Hem, Sonia; Santoni, Véronique; Maurel, Christophe

    2013-03-01

    The water status of plant leaves depends on the efficiency of the water supply, from the vasculature to inner tissues. This process is under hormonal and environmental regulation and involves aquaporin water channels. In Arabidopsis thaliana, the rosette hydraulic conductivity (Kros) is higher in darkness than it is during the day. Knockout plants showed that three plasma membrane intrinsic proteins (PIPs) sharing expression in veins (PIP1;2, PIP2;1, and PIP2;6) contribute to rosette water transport, and PIP2;1 can fully account for Kros responsiveness to darkness. Directed expression of PIP2;1 in veins of a pip2;1 mutant was sufficient to restore Kros. In addition, a positive correlation, in both wild-type and PIP2;1-overexpressing plants, was found between Kros and the osmotic water permeability of protoplasts from the veins but not from the mesophyll. Thus, living cells in veins form a major hydraulic resistance in leaves. Quantitative proteomic analyses showed that light-dependent regulation of Kros is linked to diphosphorylation of PIP2;1 at Ser-280 and Ser-283. Expression in pip2;1 of phosphomimetic and phosphorylation-deficient forms of PIP2;1 demonstrated that phosphorylation at these two sites is necessary for Kros enhancement under darkness. These findings establish how regulation of a single aquaporin isoform in leaf veins critically determines leaf hydraulics.

  12. Effect of hyperglycemia on expression of aquaporins in the rat vagina.

    Science.gov (United States)

    Lee, Hyun-Suk; Li, Zhengri; Kim, Sun-Ouck; Ahn, Kyuyoun; Kim, Noel N; Park, Kwangsung

    2012-09-01

    To investigate the effect of hyperglycemia on the expression of the aquaporin (AQP) isoforms in the diabetic rat vagina. Female Sprague-Dawley rats (230-240 g, n = 45) were divided into control (n = 10) and experimental (n = 35) groups. Diabetes in the experimental group was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). STZ-induced diabetic rats were left untreated or given subcutaneous injections of insulin (3 U/d). After 2 and 4 weeks, the blood glucose was measured, and the vaginal blood flow was assessed by Doppler flowmetry. The expression and cellular localization of AQP1 and AQP2 in the rat vagina were determined by Western blot and immunohistochemistry. The vaginal blood flow (mL/min/100 g tissue) after pelvic nerve stimulation was significantly lower in the STZ-induced diabetic rats (21.9 ± 6.5 at 2 weeks and 21 ± 2.8 at 4 weeks) compared with the control group (55.5 ± 8.9 at 2 weeks and 52.9 ± 6.5 at 4 weeks; P vagina. These results suggest that decreased vaginal lubrication in diabetic women might result from changes in aquaporin expression, in addition to a reduction in the vaginal blood flow response. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Immunogenic potential of the recombinant Rhipicephalus microplus aquaporin protein against the tick Rhipicephalus sanguineus Latreille, 1806 in domestic dogs

    Science.gov (United States)

    Aquaporins regulate water transport through the highly hydrophobic lipid bilayer of cell membranes. As ticks ingest large volumes of host blood in relation to their size, they are required to concentrate blood components and have efficient water transport mechanisms. This study aimed to evaluate the...

  14. Multilfiltration Bed Replacement (MFBR) System for the International Space Station using Aquaporin Membranes and Humidity Condensate Ersatz Wastewater

    Science.gov (United States)

    Shaw, Hali L.; Howard, Kevin; Flynn, Michael T.; Beeler, David; Kawashima, Brian; Andersen, Thomas A. E.; Kleinschmidt, Kim; Vogel, Jorg; Parodi, Jurek

    2017-01-01

    The Multifiltration Bed system in the International Space Station (ISS) Water Processor Assembly (WPA) needs to be improved by reducing or eliminating the usage rate of expendable media, removing dimethylsilanediol (DMSD), and reducing the overall system mass. The WPA contains two multifiltration beds, each with a mass of approximately 50 kg. Reducing the mass of the WPA is an important part of evolving the ISS system for future exploration missions. The Multifiltration Bed Replacement (MFBR) technology is based on biomimetic membranes, which derive their unique characteristics from aquaporins, or water channel proteins. Aquaporin membranes were commercialized by the company Aquaporin AS. Tests were conducted using the Aquaporin Inside Hollow Fiber Module to determine the maximum water recovery ratio and membrane life. Samples were analyzed for total organic carbon (TOC), DMSD, acetate, ions, and volatiles such as ethanol and acetone. The results indicate that at a 97.498.1 water recovery ratio, the membrane module can reject approximately 50 of the TOC and specific conductance using the simulated ISS MSFC humidity condensate ersatz. Additionally, the life of the membrane was determined to be a minimum of 7103 hours.

  15. PATIENTS WITH AUTOSOMAL NEPHROGENIC DIABETES-INSIPIDUS HOMOZYGOUS FOR MUTATIONS IN THE AQUAPORIN-2 WATER-CHANNEL GENE

    NARCIS (Netherlands)

    VANLIEBURG, AF; VERDIJK, MAJ; KNOERS, VVAM; VANESSEN, AJ; PROESMANS, W; MALLMANN, R; MONNENS, LAH; VANOOST, BA; VANOS, CH; DEEN, PMT

    1994-01-01

    Mutations in the X-chromosomal V2 receptor gene are known to cause nephrogenic diabetes insipidus (NDI). Besides the X-linked form, an autosomal mode of inheritance has been described. Recently, mutations in the autosomal gene coding for water-channel aquaporin 2 (AQP2) of the renal collecting duct

  16. Structure and Stability of the Spinach Aquaporin SoPIP2;1 in Detergent Micelles and Lipid Membranes

    DEFF Research Database (Denmark)

    Plasencia, Ines; Survery, Sabeen; Ibragimova, Sania

    2011-01-01

    Background: SoPIP2;1 constitutes one of the major integral proteins in spinach leaf plasma membranes and belongs to the aquaporin family. SoPIP2;1 is a highly permeable and selective water channel that has been successfully overexpressed and purified with high yields. In order to optimize...

  17. Expression of aquaporin 9 in rat liver and efferent ducts of the male reproductive system after neonatal diethylstilbestrol exposure

    DEFF Research Database (Denmark)

    Wellejus, Anja; Jensen, Henrik E; Loft, Steffen

    2008-01-01

    Aquaporins (AQP) have important solute transport functions in many tissues including the epididymal efferent ducts (ED) and in the liver. We investigated the effect of neonatal exposure to diethylstilbestrol (DES) on AQP9 expressions in the ED and in the liver of rats. DES was administered from d...

  18. Aquaporin-3 expressed in the basolateral membrane of gill chloride cells in Mozambique tilapia Oreochromis mossambicus adapted to freshwater and seawater.

    Science.gov (United States)

    Watanabe, Soichi; Kaneko, Toyoji; Aida, Katsumi

    2005-07-01

    We have cloned a homologue of mammalian aquaporin-3 (AQP3) from gills of Mozambique tilapia using a reverse transcription-polymerase chain reaction (RT-PCR). The deduced amino acid sequence shared 64-75% homology with other vertebrate AQP3 homologues. RT-PCR revealed that tilapia AQP3 was expressed in the brain, pituitary, kidney, spleen, intestine, skin, eye and gill in tilapia adapted to freshwater (FW) and seawater (SW). We also examined functional characteristics of tilapia AQP3 using Xenopus oocytes as an in vitro transcribed cRNA expression system. Osmotic water permeability (Pf) of Xenopus oocytes expressing tilapia AQP3 was about 30-fold higher than that of control oocytes, and was 80% inhibited by treatment with 0.3 mmol l(-1) HgCl2. Light-microscopic immunocytochemistry of branchial epithelia revealed that tilapia AQP3 was expressed in gill chloride cells of FW- and SW-adapted tilapia. Electron-microscopic immunocytochemistry further demonstrated that tilapia AQP3 was localized in the basolateral membrane of gill chloride cells. Basolateral localization of AQP3 in gill chloride cells suggests that AQP3 is involved in regulatory volume changes and osmoreception, which could trigger functional differentiation of chloride cells.

  19. New insights into the regulation of aquaporins by the arbuscular mycorrhizal symbiosis in maize plants under drought stress and possible implications for plant performance

    National Research Council Canada - National Science Library

    Bárzana, Gloria; Aroca, Ricardo; Bienert, Gerd Patrick; Chaumont, François; Ruiz-Lozano, Juan Manuel

    2014-01-01

    The relationship between modulation by arbuscular mycorrhizae (AM) of aquaporin expression in the host plant and changes in root hydraulic conductance, plant water status, and performance under stressful conditions is not well known...

  20. Interaction between sodium dodecyl sulfate and membrane reconstituted aquaporins: A comparative study of spinach SoPIP2;1 and E. coli AqpZ

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; Vararattanavech, Ardcharaporn; Plasencia, Inés

    2011-01-01

    of two aquaporins with high structural homology SoPIP2;1 and AqpZ using identical reconstitution conditions. Our CD results indicate that SDS, when added to membrane-reconstituted aquaporins in concentrations below the SDS critical micelle concentration (CMC, ~8mM), causes helical rearrangements of both...... aquaporins. However, we do not find compelling evidence for unfolding. In contrast when SDS is added to detergent stabilized aquaporins, SoPIP2;1 partly unfolds, while AqpZ secondary structure is unaffected. Using a fluorescent polarity sensitive probe (Badan) we show that SDS action on membrane...... reconstituted SoPIP2;1 as well as AqpZ is associated with initial increased hydrophobic interactions in protein transmembrane (TM) spanning regions up to a concentration of 0.1× CMC. At higher SDS concentrations TM hydrophobic interactions, as reported by Badan, decrease and reach a plateau from SDS CMC up...

  1. Cloning of aquaporin-1 of the blue crab, Callinectes sapidus: its expression during the larval development in hyposalinity.

    Science.gov (United States)

    Chung, J Sook; Maurer, Leah; Bratcher, Meagan; Pitula, Joseph S; Ogburn, Matthew B

    2012-09-03

    Ontogenetic variation in salinity adaptation has been noted for the blue crab, Callinectes sapidus, which uses the export strategy for larval development: females migrate from the estuaries to the coast to spawn, larvae develop in the ocean, and postlarvae (megalopae) colonize estuarine areas. We hypothesized that C. sapidus larvae may be stenohaline and have limited osmoregulatory capacity which compromises their ability to survive in lower salinity waters. We tested this hypothesis using hatchery-raised larvae that were traceable to specific life stages. In addition, we aimed to understand the possible involvement of AQP-1 in salinity adaptation during larval development and during exposure to hyposalinity. A full-length cDNA sequence of aquaporin (GenBank JQ970426) was isolated from the hypodermis of the blue crab, C. sapidus, using PCR with degenerate primers and 5' and 3' RACE. The open reading frame of CasAQP-1 consists of 238 amino acids containing six helical structures and two NPA motifs for the water pore. The expression pattern of CasAQP-1 was ubiquitous in cDNAs from all tissues examined, although higher in the hepatopancreas, thoracic ganglia, abdominal muscle, and hypodermis and lower in the antennal gland, heart, hemocytes, ovary, eyestalk, brain, hindgut, Y-organs, and gill. Callinectes larvae differed in their capacity to molt in hyposalinity, as those at earlier stages from Zoea (Z) 1 to Z4 had lower molting rates than those from Z5 onwards, as compared to controls kept in 30 ppt water. No difference was found in the survival of larvae held at 15 and 30 ppt. CasAQP-1 expression differed with ontogeny during larval development, with significantly higher expression at Z1-2, compared to other larval stages. The exposure to 15 ppt affected larval-stage dependent CasAQP-1 expression which was significantly higher in Z2- 6 stages than the other larval stages. We report the ontogenetic variation in CasAQP-1 expression during the larval development

  2. Identification and characterization of plasma membrane aquaporins isolated from fiber cells of Calotropis procera.

    Science.gov (United States)

    Aslam, Usman; Khatoon, Asia; Cheema, Hafiza Masooma Naseer; Bashir, Aftab

    2013-07-01

    Calotropis procera, commonly known as "milkweed", possesses long seed trichomes for seed dispersal and has the ability to survive under harsh conditions such as drought and salinity. Aquaporins are water channel proteins expressed in all land plants, divided into five subfamilies plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), NOD26-like proteins (NIPs), small basic intrinsic proteins (SIPs), and the unfamiliar X intrinsic proteins (XIPs). PIPs constitute the largest group of water channel proteins that are involved in different developmental and regulatory mechanisms including water permeability, cell elongation, and stomata opening. Aquaporins are also involved in abiotic stress tolerance and cell expansion mechanisms, but their role in seed trichomes (fiber cells) has never been investigated. A large number of clones isolated from C. procera fiber cDNA library showed sequence homology to PIPs. Both expressed sequence tags (ESTs) and real-time polymerase chain reaction (PCR) studies revealed that the transcript abundance of this gene family in fiber cells of C. procera is greater than that of cotton. Full-length cDNAs of CpPIP1 and CpPIP2 were isolated from C. procera fiber cDNA library and used for constructing plant expression vectors under constitutive (2×35S) and trichome-specific (GhLTP3) promoters. Transgenic tobacco plants were developed via Agrobacterium-mediated transformation. The phenotypic characteristics of the plants were observed after confirming the integration of transgene in plants. It was observed that CpPIP2 expression cassette under 2×35S and GhLTP3 promoter enhanced the numbers of stem and leave trichomes. However, 2×35S::CpPIP2 has a more amplified effect on trichome density and length than GhLTP3::CpPIP2 and other PIP constructs. These findings imply the role of C. procera PIP aquaporins in fiber cell elongation. The PIPs-derived cell expansion mechanism may be exploited through transgenic approaches for

  3. Identification and Functional Analysis of the First Aquaporin from Striped Stem Borer, Chilo suppressalis

    Directory of Open Access Journals (Sweden)

    Ming-Xing Lu

    2018-02-01

    Full Text Available Aquaporins are integral membrane proteins some of which form high capacity water-selective channels, promoting water permeation across cell membranes. In this study, we isolated the aquaporin transcript (CsDrip1 of Chilo suppressalis, one of the important rice pests. CsDrip1 included two variants, CsDrip1_v1 and CsDrip1_v2. Although CsDrip1_v2 sequence (>409 bp was longer than CsDrip1_v1, they possessed the same open reading frame (ORF. Protein structure and topology of CsDrip1 was analyzed using a predicted model, and the results demonstrated the conserved properties of insect water-specific aquaporins, including 6 transmembrane domains, 2 NPA motifs, ar/R constriction region (Phe69, His194, Ser203, and Arg209 and the C-terminal peptide sequence ending in “SYDF.” Our data revealed that the Xenopus oocytes expressing CsDrip1 indicated CsDrip1 could transport water instead of glycerol, trehalose and urea. Further, the transcript of CsDrip1 expressed ubiquitously but differentially in different tissues or organs and developmental stages of C. suppressalis. CsDrip1 mRNA exhibited the highest level of expression within hindgut and the third instar larvae. Regardless of pupae and adults, there were significantly different expression levels of CsDrip1 gene between male and female. Different from at low temperature, the transcript of CsDrip1 in larvae exposed to high temperature was increased significantly. Moreover, the mRNA levels of CsDrip1 in the third instar larvae, the fifth instar larvae, pupae (male and female, and adults (male and female under different humidities were investigated. However, the mRNA levels of CsDrip1 of only female and male adults were changed remarkably. In conclusions, CsDrip1 plays important roles in maintaining water homeostasis in this important rice pest.

  4. Herbivory of maize by southern corn rootworm induces expression of the major intrinsic protein ZmNIP1;1 and leads to the discovery of a novel aquaporin ZmPIP2;8

    OpenAIRE

    Lawrence, Susan D.; Novak, Nicole G.; Xu, Hao; Cooke, Janice E. K.

    2013-01-01

    Aquaporins channel water and other neutral molecules through cell membranes. Aquaporin gene expression is subject to transcriptional control and can be modulated by factors affecting water balance such as salt, abscisic acid and drought. During infestation of maize by southern corn rootworm (SCR), an insect that chews into and significantly damages maize roots, three maize aquaporins were differentially expressed upon prolonged infestation. Using a brief infestation of maize roots ZmNIP1;1 tr...

  5. The wheat aquaporin gene TaAQP7 confers tolerance to cold stress in transgenic tobacco.

    Science.gov (United States)

    Huang, Chao; Zhou, Shiyi; Hu, Wei; Deng, Xiaomin; Wei, Shuya; Yang, Guangxiao; He, Guangyuan

    2014-01-01

    Aquaporin proteins (AQPs) have been shown to be involved in abiotic stress responses. However, the precise role of AQPs, especially in response to cold stress, is not understood in wheat (Triticum aestivum). In the present study, quantitative real time polymerase chain reaction (qRT-PCR) analysis revealed that TaAQP7 expression increased in leaves, but decreased in roots after cold treatment. Expression of TaAQP7 in tobacco plants resulted in increased root elongation and better growth compared with wild-type (WT) plants under cold stress. Moreover, after cold treatment, the transgenic tobacco lines exhibited higher chlorophyll contents, lower levels of malondialdehyde (MDA), and less ion leakage (IL) than WT plants. Thus, expression of TaAQP7 enhanced cold stress tolerance in transgenic tobacco. Taken together, our results suggest that TaAQP7 confers cold stress tolerance by relieving membrane damage in the transgenic plants.

  6. Effects of intratympanic injection of steroids on changes in rat inner ear aquaporin expression.

    Science.gov (United States)

    Fukushima, Munehisa; Kitahara, Tadashi; Uno, Yoshihiro; Fuse, Yuka; Doi, Katsumi; Kubo, Takeshi

    2002-09-01

    Although steroid treatment is generally administered for patients with inner ear disorders, including Meniere's disease, the mechanism via which steroids exert their effects remains to be clarified. The aquaporins (AQPs) are a family of small transmembrane water transporters, and it has recently been revealed that they play a role in regulating homeostasis in the inner ear fluids. In order to elucidate the action points of steroids in the inner ear, we firstly identified AQPI, 2, 3, 4, 5 and 6 mRNAs in the rat cochlea and AQP1, 3, 4, 5 and 6 in the rat endolymphatic sac by means of reverse transcription-polymerase chain reaction. Subsequently, we found that intratympanic injections of steroids upregulated AQPI mRNA of the rat cochlea in a dose-dependent manner. These results suggest that steroids may affect water homeostasis in the rat inner ear mainly via AQP1.

  7. Characterization of protein phosphatase 2A acting on phosphorylated plasma membrane aquaporin of tulip petals.

    Science.gov (United States)

    Azad, Abul Kalam; Sawa, Yoshihiro; Ishikawa, Takahiro; Shibata, Hitoshi

    2004-05-01

    A protein phosphatase holo-type enzyme (38, 65, and 75 kDa) preparation and a free catalytic subunit (38 kDa) purified from tulip petals were characterized as protein phosphatase 2A (PP2A) by immunological and biochemical approaches. The plasma membrane containing the putative plasma membrane aquaporin (PM-AQP) was prepared from tulip petals, phosphorylated in vitro, and used as the substrate for both of the purified PP2A preparations. Although both preparations dephosphorylated the phosphorylated PM-AQP at 20 degrees C, only the holo-type enzyme preparation acted at 5 degrees C on the phosphorylated PM-AQP with higher substrate specificity, suggesting that regulatory subunits are required for low temperature-dependent dephosphorylation of PM-AQP in tulip petals.

  8. Functional characterization of water transport and cellular localization of three aquaporin paralogs in the salmonid intestine

    DEFF Research Database (Denmark)

    Madsen, Steffen S; Olesen, Jesper H; Bedal, Konstanze

    2011-01-01

    with an investigation of the distribution and cellular localization of three aquaporins (Aqp1aa, -1ab, and -8ab) in pyloric caeca, middle (M), and posterior (P) intestine of the Atlantic salmon. In vitro iso-osmotic water absorption (J(v)) was higher in SW than FW-trout and was inhibited by (mmol L(-1)): 0.1 KCN (41......(v) by 20%. In the presence of glucose, mucosal addition of phloridzin inhibited water transport by 20%, suggesting that water transport is partially linked to the Na(+)-glucose co-transporter. Using polyclonal antibodies against salmon Aqp1aa, -1ab, and -8ab, we detected Aqp1aa, and -1ab immunoreactivity...

  9. Biological significance and topological basis of aquaporin-partnering protein-protein interactions.

    Science.gov (United States)

    Ji, Hongtao; Dong, Hansong

    2015-01-01

    Aquaporins (AQPs) are intramolecular channels essential for transport of H2O, CO2, and other small substrates across membranes. Through this function, AQPs can modulate CO2 uptake and assimilation in plants and regulate water relations and many other physiological processes in all living organisms. To execute their physiological roles, AQPs may experience 3 types of hetero-molecular interaction, between AQPs and their kinases; between AQP isoforms; and between AQPs and other proteins that are neither AQPs nor kinases. Interacting with non-AQP non-kinase proteins may enable AQPs to extend their functions beyond substrate transport, and most fascinatingly, to serve as a gateway control for translocation of virulence effectors from pathogenic bacteria into the cytosol of eukaryotic cells. In this mini review, we will summarize the latter 2 types of interaction and discuss the physiological and/or pathological significance. We will also discuss a research angle to elucidate the structural basis of AQP-partnering protein interactions.

  10. Acidosis-induced downregulation of hepatocyte mitochondrial aquaporin-8 and ureagenesis from ammonia.

    Science.gov (United States)

    Molinas, Sara M; Soria, Leandro R; Marrone, Julieta; Danielli, Mauro; Trumper, Laura; Marinelli, Raúl A

    2015-08-01

    It has been proposed that, during metabolic acidosis, the liver downregulates mitochondrial ammonia detoxification via ureagenesis, a bicarbonate-consuming process. Since we previously demonstrated that hepatocyte mitochondrial aquaporin-8 channels (mtAQP8) facilitate the uptake of ammonia and its metabolism into urea, we studied whether mtAQP8 is involved in the liver adaptive response to acidosis. Primary cultured rat hepatocytes were adapted to acidosis by exposing them to culture medium at pH 7.0 for 40 h. Control cells were exposed to pH 7.4. Hepatocytes exposed to acid medium showed a decrease in mtAQP8 protein expression (-30%, p acidosis also showed decreased protein expression of hepatic mtAQP8 (-50%, p acidosis, a mechanism that may contribute to decreased ureagenesis from ammonia in response to acidosis.

  11. Simple and inexpensive hardware and software method to measure volume changes in Xenopus oocytes expressing aquaporins.

    Science.gov (United States)

    Dorr, Ricardo; Ozu, Marcelo; Parisi, Mario

    2007-04-15

    Water channels (aquaporins) family members have been identified in central nervous system cells. A classic method to measure membrane water permeability and its regulation is to capture and analyse images of Xenopus laevis oocytes expressing them. Laboratories dedicated to the analysis of motion images usually have powerful equipment valued in thousands of dollars. However, some scientists consider that new approaches are needed to reduce costs in scientific labs, especially in developing countries. The objective of this work is to share a very low-cost hardware and software setup based on a well-selected webcam, a hand-made adapter to a microscope and the use of free software to measure membrane water permeability in Xenopus oocytes. One of the main purposes of this setup is to maintain a high level of quality in images obtained at brief intervals (shorter than 70 ms). The presented setup helps to economize without sacrificing image analysis requirements.

  12. Hypotonicity-induced Renin exocytosis from juxtaglomerular cells requires aquaporin-1 and cyclooxygenase-2

    DEFF Research Database (Denmark)

    Friis, Ulla G; Madsen, Kirsten; Svenningsen, Per

    2009-01-01

    The mechanism by which extracellular hypotonicity stimulates release of renin from juxtaglomerular (JG) cells is unknown. We hypothesized that osmotically induced renin release depends on water movement through aquaporin-1 (AQP1) water channels and subsequent prostanoid formation. We recorded...... membrane capacitance (C(m)) by whole-cell patch clamp in single JG cells as an index of exocytosis. Hypotonicity increased C(m) significantly and enhanced outward current. Indomethacin, PLA(2) inhibition, and an antagonist of prostaglandin transport impaired the C(m) and current responses to hypotonicity....... Hypotonicity also increased exocytosis as determined by a decrease in single JG cell quinacrine fluorescence in an indomethacin-sensitive manner. In single JG cells from COX-2(-/ -) and AQP1(-/ -) mice, hypotonicity increased neither C(m) nor outward current, but 0.1-muM PGE(2) increased both in these cells...

  13. A preliminary study of aquaporin 1 immunolocalization in chronic subdural hematoma membranes.

    Science.gov (United States)

    Basaldella, Luca; Perin, Alessandro; Orvieto, Enrico; Marton, Elisabetta; Itskevich, David; Dei Tos, Angelo Paolo; Longatti, Pierluigi

    2010-07-01

    Aquaporin 1 (AQP1) is a molecular water channel expressed in many anatomical locations, particularly in epithelial barriers specialized in water transport. The aim of this study was to investigate AQP1 expression in chronic subdural hematoma (CSDH) membranes. In this preliminary study, 11 patients with CSDH underwent burr hole craniectomy and drainage. Membrane specimens were stained with a monoclonal antibody targeting AQP1 for immunohistochemical analysis. The endothelial cells of the sinusoid capillaries of the outer membranes exhibited an elevated immunoreactivity to AQP1 antibody compared to the staining intensity of specimens from the inner membrane and normal dura. These findings suggest that the outer membrane might be the source of the increased fluid accumulation responsible for chronic hematoma enlargement.

  14. Control of the selectivity of the aquaporin water channel family by global orientational tuning

    DEFF Research Database (Denmark)

    Jensen, Morten Østergaard; Tajkhorshid, E.; Nollert, P.

    2002-01-01

    and orientation of a single file of seven to nine water molecules inside the channel. Two conserved asparagines force a central water molecule to serve strictly as a hydrogen bond donor to its neighboring water molecules. Assisted by the electrostatic potential generated by two half-membrane spanning loops......Aquaporins are transmembrane channels found in cell membranes of all life forms. We examine their apparently paradoxical property, facilitation of efficient permeation of water while excluding protons, which is of critical importance to preserving the electrochemical potential across the cell...... membrane. We have determined the structure of the Escherichia coli aquaglyceroporin GlpF with bound water, in native (2.7 angstroms) and in W48F/F200T mutant (2.1 angstroms) forms, and carried out 12-nanosecond molecular dynamics simulations that define the spatial and temporal probability distribution...

  15. Herbivory of maize by southern corn rootworm induces expression of the major intrinsic protein ZmNIP1;1 and leads to the discovery of a novel aquaporin ZmPIP2;8

    National Research Council Canada - National Science Library

    Lawrence, Susan; Novak, Nicole; Xu, Hao; Cooke, Janice

    2013-01-01

    .... During infestation of maize by southern corn rootworm (SCR), an insect that chews into and significantly damages maize roots, three maize aquaporins were differentially expressed upon prolonged infestation...

  16. Hydraulic conductivity and contribution of aquaporins to water uptake in roots of four sunflower genotypes.

    Science.gov (United States)

    Adiredjo, Afifuddin Latif; Navaud, Olivier; Grieu, Philippe; Lamaze, Thierry

    2014-12-01

    This article evaluates the potential of intraspecific variation for whole-root hydraulic properties in sunflower. We investigated genotypic differences related to root water transport in four genotypes selected because of their differing water use efficiency (JAC doi: 10.1111/jac.12079. 2014). We used a pressure-flux approach to characterize hydraulic conductance (L 0 ) which reflects the overall water uptake capacity of the roots and hydraulic conductivity (Lp r ) which represents the root intrinsic water permeability on an area basis. The contribution of aquaporins (AQPs) to water uptake was explored using mercuric chloride (HgCl2), a general AQP blocker. There were considerable variations in root morphology between genotypes. Mean values of L 0 and Lp r showed significant variation (above 60% in both cases) between recombinant inbred lines in control plants. Pressure-induced sap flow was strongly inhibited by HgCl2 treatment in all genotypes (more than 50%) and contribution of AQPs to hydraulic conductivity varied between genotypes. Treated root systems displayed markedly different L 0 values between genotypes whereas Lp r values were similar. Our analysis points to marked differences between genotypes in the intrinsic aquaporin-dependent path (Lp r in control plants) but not in the intrinsic AQP-independent paths (Lp r in HgCl2 treated plants). Overall, root anatomy was a major determinant of water transport properties of the whole organ and can compensate for a low AQP contribution. Hydraulic properties of root tissues and organs might have to be taken into account for plant breeding since they appear to play a key role in sunflower water balance and water use efficiency.

  17. Water and CO₂ permeability of SsAqpZ, the cyanobacterium Synechococcus sp. PCC7942 aquaporin.

    Science.gov (United States)

    Ding, Xiaodong; Matsumoto, Tadashi; Gena, Patrizia; Liu, Chengwei; Pellegrini-Calace, Marialuisa; Zhong, Shihua; Sun, Xiaoli; Zhu, Yanming; Katsuhara, Maki; Iwasaki, Ikuko; Kitagawa, Yoshichika; Calamita, Giuseppe

    2013-03-01

    Cyanobacteria possess Aquaporin-Z (AqpZ) membrane channels which have been suggested to mediate the water efflux underlying osmostress-inducible gene expression and to be essential for glucose metabolism under photomixotrophic growth. However, preliminary observations suggest that the biophy-sical properties of transport and physiological meaning of AqpZ in such photosynthetic microorganisms are not yet completely assessed. In this study, we used Xenopus laevis oocyte and proteoliposome systems to directly demonstrate the water permeability of the cyanobacterium Synechococcus sp. PCC7942 aquaporin, SsAqpZ. By an in vitro assay of intracellular acidification in yeast cells, SsAqpZ was found to transport also CO2 . Consistent with this result, during the entire exponential phase of growth, Synechococcus SsAqpZ-null-mutant cells grew slower than the corresponding wild-type cells. This phenotype was stronger with higher levels of extracellular CO2 . In line with the conversion of CO2 gas into HCO3(-) ions under alkaline conditions, the impairment in growth of the SsAqpZ-null strain was weaker in more alkaline culture medium. Cyanobacterial SsAqpZ may exert a pleiotropic function in addition to the already reported roles in macronutrient homeostasis and osmotic-stress response as it appears to constitute an important pathway in CO2 uptake, a fundamental step in photosynthesis. Copyright © 2013 Soçiété Française des Microscopies and Soçiété de Biologie Cellulaire de France.

  18. What really prevents proton transport through aquaporin? Charge self-energy versus proton wire proposals.

    Science.gov (United States)

    Burykin, Anton; Warshel, Arieh

    2003-12-01

    The nature of the control of water/proton selectivity in biological channels is a problem of a fundamental importance. Most studies of this issue have proposed that an interference with the orientational requirements of the so-called proton wire is the source of selectivity. The elucidation of the structures of aquaporins, which have evolved to prevent proton transfer (PT), provided a clear benchmark for exploring the selectivity problem. Previous simulations of this system have not examined, however, the actual issue of PT, but only considered the much simpler task of the transfer of water molecules. Here we take aquaporin as a benchmark and quantify the origin of the water/proton selectivity in this and related systems. This is done by evaluating in a consistent way the free energy profile for transferring a proton along the channel and relating this profile to the relevant PT rate constants. It is found that the water/proton selectivity is controlled by the change in solvation free energy upon moving the charged proton from water to the channel. The reason for the focus on the elegant concept of the proton wire and the related Grotthuss-type mechanism is also considered. It is concluded that these mechanisms are clearly important in cases with flat free energy surfaces (e.g., in bulk water, in gas phase water chains, and in infinitely long channels). However, in cases of biological channels, the actual PT mechanism is much less important than the energetics of transferring the proton charge from water to different regions in the channels.

  19. Roles of Aquaporins in Setaria viridis Stem Development and Sugar Storage

    Directory of Open Access Journals (Sweden)

    Samantha Alison McGaughey

    2016-12-01

    Full Text Available Setaria viridis is a C4 grass used as a model for bioenergy feedstocks. The elongating internodes in developing S. viridis stems grow from an intercalary meristem at the base, and progress acropetally towards fully expanded cells that store sugar. During stem development and maturation, water flow is a driver of cell expansion and sugar delivery. As aquaporin proteins are implicated in regulating water flow we analysed elongating and mature internode transcriptomes to identify putative aquaporin encoding genes that had particularly high transcript levels during the distinct stages of internode cell expansion and maturation. We observed that SvPIP2;1 was highly expressed in internode regions undergoing cell expansion, and SvNIP2;2 was highly expressed in mature sugar accumulating regions. Gene co-expression analysis revealed SvNIP2;2 expression was highly correlated with the expression of five putative sugar transporters expressed in the S. viridis internode. To explore the function of the proteins encoded by SvPIP2;1 and SvNIP2;2 we expressed them in Xenopus laevis oocytes and tested their permeability to water. SvPIP2;1 and SvNIP2;2 functioned as water channels in X. laevis oocytes and their permeability was gated by pH. Our results indicate that SvPIP2;1 may function as a water channel in developing stems undergoing cell expansion and SvNIP2;2 is a candidate for retrieving water and possibly a yet to be determined solute from mature internodes. Future research will investigate whether changing the function of these proteins influences stem growth and sugar yield in S. viridis.

  20. Roles of Aquaporins inSetaria viridisStem Development and Sugar Storage.

    Science.gov (United States)

    McGaughey, Samantha A; Osborn, Hannah L; Chen, Lily; Pegler, Joseph L; Tyerman, Stephen D; Furbank, Robert T; Byrt, Caitlin S; Grof, Christopher P L

    2016-01-01

    Setaria viridis is a C 4 grass used as a model for bioenergy feedstocks. The elongating internodes in developing S. viridis stems grow from an intercalary meristem at the base, and progress acropetally toward fully expanded cells that store sugar. During stem development and maturation, water flow is a driver of cell expansion and sugar delivery. As aquaporin proteins are implicated in regulating water flow, we analyzed elongating and mature internode transcriptomes to identify putative aquaporin encoding genes that had particularly high transcript levels during the distinct stages of internode cell expansion and maturation. We observed that SvPIP2;1 was highly expressed in internode regions undergoing cell expansion, and SvNIP2;2 was highly expressed in mature sugar accumulating regions. Gene co-expression analysis revealed SvNIP2;2 expression was highly correlated with the expression of five putative sugar transporters expressed in the S. viridis internode. To explore the function of the proteins encoded by SvPIP2;1 and SvNIP2;2 , we expressed them in Xenopus laevis oocytes and tested their permeability to water. SvPIP2;1 and SvNIP2;2 functioned as water channels in X. laevis oocytes and their permeability was gated by pH. Our results indicate that SvPIP2;1 may function as a water channel in developing stems undergoing cell expansion and SvNIP2;2 is a candidate for retrieving water and possibly a yet to be determined solute from mature internodes. Future research will investigate whether changing the function of these proteins influences stem growth and sugar yield in S. viridis .

  1. Plant Aquaporins: genome-wide identification, transcriptomics, proteomics, and advanced analytical tools

    Directory of Open Access Journals (Sweden)

    Rupesh Kailasrao Deshmukh

    2016-12-01

    Full Text Available Aquaporins (AQPs are channel-forming integral membrane proteins that facilitate the movement of water and many other small molecules. Compared to animals, plants contain a much higher number of AQPs in their genome. Homology-based identification of AQPs in sequenced species is feasible because of the high level of conservation of protein sequences across plant species. Genome-wide characterization of AQPs has highlighted several important aspects such as distribution, genetic organization, evolution and conserved features governing solute specificity. From a functional point of view, the understanding of AQP transport system has expanded rapidly with the help of transcriptomics and proteomics data. The efficient analysis of enormous amounts of data generated through omic scale studies has been facilitated through computational advancements. Prediction of protein tertiary structures, pore architecture, cavities, phosphorylation sites, heterodimerization, and co-expression networks has become more sophisticated and accurate with increasing computational tools and pipelines. However, the effectiveness of computational approaches is based on the understanding of physiological and biochemical properties, transport kinetics, solute specificity, molecular interactions, sequence variations, phylogeny and evolution of aquaporins. For this purpose, tools like Xenopus oocyte assays, yeast expression systems, artificial proteoliposomes, and lipid membranes have been efficiently exploited to study the many facets that influence solute transport by AQPs. In the present review, we discuss genome-wide identification of AQPs in plants in relation with recent advancements in analytical tools, and their availability and technological challenges as they apply to AQPs. An exhaustive review of omics resources available for AQP research is also provided in order to optimize their efficient utilization. Finally, a detailed catalog of computational tools and analytical

  2. Transient receptor potential vanilloid 4 regulates aquaporin-5 abundance under hypotonic conditions

    Science.gov (United States)

    Sidhaye, Venkataramana K.; Güler, Ali D.; Schweitzer, Kelly S.; D’Alessio, Franco; Caterina, Michael J.; King, Landon S.

    2006-01-01

    Aquaporin-5 (AQP5) is expressed in epithelia of lung, cornea, and various secretory glands, sites where extracellular osmolality is known to fluctuate. Hypertonic aquaporin (AQP) induction has been described, but little is known about the effects of a hypotonic environment on AQP abundance. We report that, when mouse lung epithelial cells were exposed to hypotonic medium, a dose-responsive decrease in AQP5 abundance was observed. Hypotonic reduction of AQP5 was blocked by ruthenium red, methanandamide, and miconazole, agents that inhibit the cation channel transient receptor potential vanilloid (TRPV) 4 present in lung epithelial cells. Several observations indicate that TRPV4 participates in hypotonic reduction of AQP5, including a requirement for extracellular calcium to achieve AQP5 reduction; an increase in intracellular calcium in mouse lung epithelial (MLE) cells after hypotonic stimulation; and reduction of AQP5 abundance after addition of the TRPV4 agonist 4α-Phorbol-12,13-didecanoate (4α-PDD). Similarly, addition of hypotonic PBS to mouse trachea in vivo decreased AQP5 within 1 h, an effect blocked by ruthenium red. To confirm a functional interaction, AQP5 was expressed in control or TRPV4-expressing human embryonic kidney (HEK) cells. Hypotonic reduction of AQP5 was observed only in the presence of TRPV4 and was blocked by ruthenium red. Combined with earlier studies, these observations indicate that AQP5 abundance is tightly regulated along a range of osmolalities and that AQP5 reduction by extracellular hypotonicity can be mediated by TRPV4. These findings have direct relevance to regulation of membrane water permeability and water homeostasis in epithelia of the lung and other organs. PMID:16537379

  3. Cardiac Morphology and Function, and Blood Gas Transport in Aquaporin-1 Knockout Mice.

    Directory of Open Access Journals (Sweden)

    Samer eAl-Samir

    2016-05-01

    Full Text Available We have studied cardiac and respiratory functions of aquaporin- 1-deficient mice by the Pressure-Volume-loop technique and by blood gas analysis. In addition, the morphological properties of the animals’ hearts were analysed. In anesthesia under maximal dobutamine stimulation, the mice exhibit a moderately elevated heart rate of < 600 min-1 and an O2 consumption of ~0.6 ml/min/g, which is about twice the basal rate. In this state, which is similar to the resting state of the conscious animal, all cardiac functions including stroke volume and cardiac output exhibited resting values and were identical between deficient and wildtype animals. Likewise, pulmonary and peripheral exchange of O2 and CO2 were normal. In contrast, several morphological parameters of the heart tissue of deficient mice were altered: 1 left ventricular wall thickness was reduced by 12%, 2 left ventricular mass, normalized to tibia length, was reduced by 10-20%, 3 cardiac muscle fiber cross sectional area was decreased by 17%, and 4 capillary density was diminished by 10%. As the P-V-loop technique yielded normal end-diastolic and end-systolic left ventricular volumes, the deficient hearts are characterized by thin ventricular walls in combination with normal intraventricular volumes. The aquaporin-1-deficient heart thus seems to be at a disadvantage compared to the wildtype heart by a reduced left-ventricular wall thickness and an increased diffusion distance between blood capillaries and muscle mitochondria. While under the present quasi-resting conditions these morphological alterations have no consequences for cardiac function, we expect that the deficient hearts will show a reduced maximal cardiac output.

  4. A decrease in the permeability of aquaporin zero as a possible cause for presbyopia.

    Science.gov (United States)

    Gerometta, R; Candia, O A

    2016-01-01

    The crystalline lens appears to be a simple organ with the sole role of focusing light upon the retina. However, numerous studies have underscored its dynamic nature with a host of compartmentalized physiological processes. As the individual ages, the normal lens develops two inescapable processes, presbyopia and cataracts. Yet, to date, there is no uniform explanation for presbyopia and many factors have been proposed as contributors including continuous enlargement of the lens, loss of power of the ciliary muscle and hardening of the lens fibers. Proposed explanations are incomplete and need experimental confirmation. This paper analyzes the possible causes for presbyopia and proposes a new one for it: a decrease in the permeability of aquaporin zero (AQP-0) also known as major intrinsic protein (MIP). Based on original findings of our laboratory, this paper proposes that a fluid flow exists inside the avascular lens. This fluid enters and leaves the lens during the accommodation process. We believe that for this to occur the lens utilizes the permeability of aquaporin zero which is abundant in the membrane of the fiber cells. Volume change due to fluid traversing the surface of the lens occurs during accommodation. We present the hypothesis that increasing the permeability of AQP-0 would facilitate accommodation. Therefore, defects in AQP-0 permeability may be a cause for presbyopia. We would also like to propose that it is possible to visualize and measure the fluid volume lost during un-accommodation and determine if the fluid is lost across the anterior, posterior or both surfaces. An age-related loss in lens water permeability could reduce fluid fluxes during the shape changes of accommodation potentially contributing to presbyopia. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Diagnosis of neuromyelitis optica (NMO) spectrum disorders: is MRI obsolete?

    Energy Technology Data Exchange (ETDEWEB)

    Downer, Jonathan James; Carter, Ranjana; Kueker, Wilhelm; Quaghebeur, Gerardine [John Radcliffe Hospital, Department of Neuroradiology, Oxford (United Kingdom); Leite, Maria Isabel; Palace, Jacqueline [Oxford University, Department of Clinical Neurology, Oxford (United Kingdom)

    2012-04-15

    Neuromyelitis optica (NMO) is a severe demyelinating disease that preferentially involves spinal cord and optic nerve. It is part of a spectrum of neurological conditions associated with antibodies to aquaporin-4 (AQP4). This study investigates the role of MRI where novel, more sensitive AQP4 antibody immunoassay techniques are being used. Retrospective review of neuroimaging in 69 patients (25 antibody positive, 44 antibody negative), investigated in the context of suspected NMO or NMO spectrum disorder, was performed independently by two consultant neuroradiologists. Longitudinally extensive, central spinal cord lesions were more frequent in AQP4 positive patients (95.2% vs 35.5%, p < 0.0001; 85.7% vs 45.2%, p = 0.015). Multiple sclerosis diagnostic criteria were less frequently fulfilled on brain MRI in antibody positive patients (5.6% vs 33.3%, p = 0.035). Juxtacortical and corpus callosal lesions were also less common in this group (16.7% vs 46.7%, p = 0.063; 5.6% vs 46.7%, p = 0.0034). Hypothalamic and periependymal disease related to the aqueduct was not seen in antibody negative patients. T1 hypointensity was more common in cord lesions of antibody positive patients (75.0% vs 35.3%, p = 0.037). However, this characteristic did not discriminate antibody positive and negative longitudinally extensive cord lesions (73.3% vs 62.5%, p = 0.66). The NMO spectrum of diseases are among an increasing number of neurological conditions defined by serological tests. However, despite improved immunoassay techniques, MRI of the brain and spinal cord continues to be among the first-line investigations in these patients, providing valuable diagnostic information that will help guide patient management. (orig.)

  6. Atypical presentations of neuromyelitis optica

    Directory of Open Access Journals (Sweden)

    Douglas Sato

    2011-10-01

    Full Text Available Neuromyelitis optica (NMO is an inflammatory disease of central nervous system classically characterized by acute, severe episodes of optic neuritis and longitudinally extensive transverse myelitis, usually with a relapsing course. The identification of an autoantibody exclusively detected in NMO patients against aquaporin-4 (AQP-4 has allowed identification of cases beyond the classical phenotype. Brain lesions, once thought as infrequent, can be observed in NMO patients, but lesions have different characteristics from the ones seen in multiple sclerosis. Additionally, some AQP-4 antibody positive patients may present with a variety of symptoms not being restricted to optic neuritis and acute myelitis during the first attack or in a relapse. Examples are not limited to, but may include patients only with brain and/or brainstem lesions, narcolepsy with hypothalamic lesions or patients with intractable hiccups, nausea and vomiting. The prompt identification of NMO patients with atypical presentations may benefit these patients with institution of early treatment to reduce disability and prevent further attacks.

  7. Brain Basics

    Medline Plus

    Full Text Available ... About Us Home > Health & Education > Educational Resources Brain Basics Introduction The Growing Brain The Working Brain Brain ... called the hypothalamic-pituitary-adrenal (HPA) axis. Brain Basics in Real Life Brain Basics in Real Life— ...

  8. Patients with autosomal nephrogenic diabetes insipidus homozygous for mutations in the aquaporin 2 water-channel gene

    Energy Technology Data Exchange (ETDEWEB)

    Lieburg, A.F. van; Verdijk, M.A.J.; Knoers, V.V.A.M.; Monnens, L.A.H.; Oost, B.A. van; Os, C.H. van; Deen, P.M.T. [Univ. of Nijmegen (Netherlands); Essen, A.J. van [Univ. of Groningen (Netherlands); Proesmans, W. [Univ. of Leuven (Belgium); Mallmann, R. [Univ. of Bonn (Germany)

    1994-10-01

    Mutations in the X-chromosomal V2 receptor gene are known to cause nephrogenic diabetes insipidus (NDI). Besides the X-linked form, an autosomal mode of inheritance has been described. Recently, mutations in the autosomal gene coding for water-channel aquaporin 2 (AQP2) of the renal collecting duct were reported in an NDI patient. In the present study, missense mutations and a single nucleotide deletion in the aquaporin 2 gene of three NDI patients from consanquineous matings are described. Expression studies in Xenopus oocytes showed that the missense AQP2 proteins are nonfunctional. These results prove that mutations in the AQP2 gene cause autosomal recessive NDI. 32 refs., 4 figs.

  9. Aquaporins-2 and -4 regulate glycogen metabolism and survival during hyposmotic-anoxic stress in Caenorhabditis elegans.

    Science.gov (United States)

    LaMacchia, John C; Roth, Mark B

    2015-07-15

    Periods of oxygen deprivation can lead to ion and water imbalances in affected tissues that manifest as swelling (edema). Although oxygen deprivation-induced edema is a major contributor to injury in clinical ischemic diseases such as heart attack and stroke, the pathophysiology of this process is incompletely understood. In the present study we investigate the impact of aquaporin-mediated water transport on survival in a Caenorhabditis elegans model of edema formation during complete oxygen deprivation (anoxia). We find that nematodes lacking aquaporin water channels in tissues that interface with the surrounding environment display decreased edema formation and improved survival rates in anoxia. We also find that these animals have significantly reduced demand for glycogen as an energetic substrate during anoxia. Together, our data suggest that reductions in membrane water permeability may be sufficient to induce a hypometabolic state during oxygen deprivation that reduces injury and extends survival limits. Copyright © 2015 the American Physiological Society.

  10. Development of supported biomimetic membranes for insertion of aquaporin protein water channels for novel water filtration applications

    DEFF Research Database (Denmark)

    Hansen, Jesper Søndergaard

    Aquaporins represent a class of membrane protein channels found in all living organisms that selectively transport water molecules across biological membranes. The work presented in this thesis was motivated by the conceptual idea of incorporating aquaporin water channels into biomimetic membranes...... to develop novel water separation technologies. To accomplish this, it is necessary to construct an efficient platform to handle biomimetic membranes. Moreover, general methods are required to reliable and controllable reconstitute membrane proteins into artificially made model membranes....... These are the topics of this thesis, and are divided into three main chapters. Chapter 2 reviews recent advances in the design and construction of biomimetic membrane arrays. Moreover, current and novel strategies for the reconstitution of membrane proteins into biomimetic membranes are reviewed. Chapter 3 presents...

  11. Gas-tight triblock-copolymer membranes are converted to CO₂ permeable by insertion of plant aquaporins.

    Science.gov (United States)

    Uehlein, Norbert; Otto, Beate; Eilingsfeld, Adrian; Itel, Fabian; Meier, Wolfgang; Kaldenhoff, Ralf

    2012-01-01

    We demonstrate that membranes consisting of certain triblock-copolymers were tight for CO₂. Using a novel approach, we provide evidence for aquaporin facilitated CO₂ diffusion. Plant aquaporins obtained from heterologous expression were inserted into triblock copolymer membranes. These were employed to separate a chamber with a solution maintaining high CO₂ concentrations from one with depleted CO₂ concentrations. CO₂ diffusion was detected by measuring the pH change resulting from membrane CO₂ diffusion from one chamber to the other. An up to 21 fold increase in diffusion rate was determined. Besides the supply of this proof of principle, we could provide additional arguments in favour of protein facilitated CO₂ diffusion to the vivid on-going debate about the principles of membrane gas diffusion in living cells.

  12. Aquaporin-8 mediates human esophageal cancer Eca-109 cell migration via the EGFR-Erk1/2 pathway

    OpenAIRE

    Chang, Heng; Shi, Yong-Hua; Talaf, Tuo-Kan; Lin, Chen

    2014-01-01

    Abnormal expression of aquaporins (AQPs) has been reported in several human cancers. Epidermal growth factor receptor (EGFR)-extracellular signal-regulated kinases1/2 (ERK1/2) are associated with tumorigenesis and cancer progression and may upregulate AQPs expression. In this study, we investigated acquaporin-8 expression and signaling via epidermal growth factor receptor-extracellular signal-regulated kinases1/2 in human esophageal cancer Eca-109 cells by western blot, immunofluorescence and...

  13. The Role of Aquaporin and Tight Junction Proteins in the Regulation of Water Movement in Larval Zebrafish (Danio rerio)

    OpenAIRE

    Kwong, Raymond W. M.; Yusuke Kumai; Perry, Steve F

    2013-01-01

    Teleost fish living in freshwater are challenged by passive water influx; however the molecular mechanisms regulating water influx in fish are not well understood. The potential involvement of aquaporins (AQP) and epithelial tight junction proteins in the regulation of transcellular and paracellular water movement was investigated in larval zebrafish (Danio rerio). We observed that the half-time for saturation of water influx (K(u)) was 4.3±0.9 min, and reached equilibrium at approximately 30...

  14. Aquaporins in the wild: natural genetic diversity and selective pressure in the PIP gene family in five neotropical tree species

    OpenAIRE

    Audigeos, Delphine; Buonamici, Anna; Belkadi, Laurent; Rymer, Paul; Boshier, David; Scotti-Saintagne, Caroline; Vendramini, Giovanni

    2010-01-01

    Abstract Background Tropical trees undergo severe stress through seasonal drought and flooding, and the ability of these species to respond may be a major factor in their survival in tropical ecosystems, particularly in relation to global climate change. Aquaporins are involved in the regulation of water flow and have been shown to be involved in drought response; they may therefore play a major adaptive role in these species. We describe genetic diversity in the PIP sub-family of the widespr...

  15. Reduced water permeability and altered ultrastructure in thin descending limb of Henle in aquaporin-1 null mice

    OpenAIRE

    Chou, Chung-Lin; Knepper, Mark A.; Hoek, Alfred N. van; Brown, Dennis; Yang, Baoxue; Ma, Tonghui; Verkman, A. S.

    1999-01-01

    It has been controversial whether high water permeability in the thin descending limb of Henle (TDLH) is required for formation of a concentrated urine by the kidney. Freeze-fracture electron microscopy (FFEM) of rat TDLH has shown an exceptionally high density of intramembrane particles (IMPs), which were proposed to consist of tetramers of aquaporin-1 (AQP1) water channels. In this study, transepithelial osmotic water permeability (Pf) was measured in isolated perfused segments (0.5–1 mm) o...

  16. Glymphatic clearance controls state-dependent changes in brain lactate concentration

    DEFF Research Database (Denmark)

    Lundgaard, Iben; Lu, Minh Lon; Yang, Ezra

    2017-01-01

    accumulation of lactate in cervical, but not in inguinal lymph nodes when mice were anesthetized. Thus, our study suggests that brain lactate is an excellent biomarker of the sleep-wake cycle and increases further during sleep deprivation, because brain lactate is inversely correlated with glymphatic......Brain lactate concentration is higher during wakefulness than in sleep. However, it is unknown why arousal is linked to an increase in brain lactate and why lactate declines within minutes of sleep. Here, we show that the glymphatic system is responsible for state-dependent changes in brain lactate...... concentration. Suppression of glymphatic function via acetazolamide treatment, cisterna magna puncture, aquaporin 4 deletion, or changes in body position reduced the decline in brain lactate normally observed when awake mice transition into sleep or anesthesia. Concurrently, the same manipulations diminished...

  17. Aquaporins in the wild: natural genetic diversity and selective pressure in the PIP gene family in five Neotropical tree species.

    Science.gov (United States)

    Audigeos, Delphine; Buonamici, Anna; Belkadi, Laurent; Rymer, Paul; Boshier, David; Scotti-Saintagne, Caroline; Vendramin, Giovanni G; Scotti, Ivan

    2010-06-29

    Tropical trees undergo severe stress through seasonal drought and flooding, and the ability of these species to respond may be a major factor in their survival in tropical ecosystems, particularly in relation to global climate change. Aquaporins are involved in the regulation of water flow and have been shown to be involved in drought response; they may therefore play a major adaptive role in these species. We describe genetic diversity in the PIP sub-family of the widespread gene family of Aquaporins in five Neotropical tree species covering four botanical families. PIP Aquaporin subfamily genes were isolated, and their DNA sequence polymorphisms characterised in natural populations. Sequence data were analysed with statistical tests of standard neutral equilibrium and demographic scenarios simulated to compare with the observed results. Chloroplast SSRs were also used to test demographic transitions. Most gene fragments are highly polymorphic and display signatures of balancing selection or bottlenecks; chloroplast SSR markers have significant statistics that do not conform to expectations for population bottlenecks. Although not incompatible with a purely demographic scenario, the combination of all tests tends to favour a selective interpretation of extant gene diversity. Tropical tree PIP genes may generally undergo balancing selection, which may maintain high levels of genetic diversity at these loci. Genetic variation at PIP genes may represent a response to variable environmental conditions.

  18. Aquaporins in the wild: natural genetic diversity and selective pressure in the PIP gene family in five Neotropical tree species

    Directory of Open Access Journals (Sweden)

    Vendramin Giovanni G

    2010-06-01

    Full Text Available Abstract Background Tropical trees undergo severe stress through seasonal drought and flooding, and the ability of these species to respond may be a major factor in their survival in tropical ecosystems, particularly in relation to global climate change. Aquaporins are involved in the regulation of water flow and have been shown to be involved in drought response; they may therefore play a major adaptive role in these species. We describe genetic diversity in the PIP sub-family of the widespread gene family of Aquaporins in five Neotropical tree species covering four botanical families. Results PIP Aquaporin subfamily genes were isolated, and their DNA sequence polymorphisms characterised in natural populations. Sequence data were analysed with statistical tests of standard neutral equilibrium and demographic scenarios simulated to compare with the observed results. Chloroplast SSRs were also used to test demographic transitions. Most gene fragments are highly polymorphic and display signatures of balancing selection or bottlenecks; chloroplast SSR markers have significant statistics that do not conform to expectations for population bottlenecks. Although not incompatible with a purely demographic scenario, the combination of all tests tends to favour a selective interpretation of extant gene diversity. Conclusions Tropical tree PIP genes may generally undergo balancing selection, which may maintain high levels of genetic diversity at these loci. Genetic variation at PIP genes may represent a response to variable environmental conditions.

  19. Adaptable interaction between aquaporin-1 and band 3 reveals a potential role of water channel in blood CO2transport.

    Science.gov (United States)

    Hsu, Kate; Lee, Ting-Ying; Periasamy, Ammasi; Kao, Fu-Jen; Li, Li-Tzu; Lin, Chuang-Yu; Lin, Hui-Ju; Lin, Marie

    2017-10-01

    Human CO 2 respiration requires rapid conversion between CO 2 and HCO 3 - Carbonic anhydrase II facilitates this reversible reaction inside red blood cells, and band 3 [anion exchanger 1 (AE1)] provides a passage for HCO 3 - flux across the cell membrane. These 2 proteins are core components of the CO 2 transport metabolon. Intracellular H 2 O is necessary for CO 2 /HCO 3 - conversion. However, abundantly expressed aquaporin 1 (AQP1) in erythrocytes is thought not to be part of band 3 complexes or the CO 2 transport metabolon. To solve this conundrum, we used Förster resonance energy transfer (FRET) measured by fluorescence lifetime imaging (FLIM-FRET) and identified interaction between aquaporin-1 and band 3 at a distance of 8 nm, within the range of dipole-dipole interaction. Notably, their interaction was adaptable to membrane tonicity changes. This suggests that the function of AQP1 in tonicity response could be coupled or correlated to its function in band 3-mediated CO 2 /HCO 3 - exchange. By demonstrating AQP1 as a mobile component of the CO 2 transport metabolon, our results uncover a potential role of water channel in blood CO 2 transport and respiration.-Hsu, K., Lee, T.-Y., Periasamy, A., Kao, F.-J., Li, L.-T., Lin, C.-Y., Lin, H.-J., Lin, M. Adaptable interaction between aquaporin-1 and band 3 reveals a potential role of water channel in blood CO 2 transport. © FASEB.

  20. Localization of a Drosophila DRIP-like aquaporin in the Malpighian tubules of the house cricket, Acheta domesticus.

    Science.gov (United States)

    Spring, Jeffrey H; Robichaux, S Renee; Kaufmann, Nancy; Brodsky, Jeffrey L

    2007-09-01

    Malpighian tubules (Mt) are the primary excretory and osmoregulatory organs of insects, capable of rapidly transporting extraordinary volumes of fluid when stimulated by diuretic factors. In the house cricket, Acheta domesticus, the Mt are composed of three morphologically distinct regions (proximal, mid, and distal). Unlike the dipteran Mt, which have both primary and stellate cells, each region of the Acheta Mt consists of a morphologically uniform cell type. The mid and distal regions are both secretory in function and increase secretion rate in response to dibutyryl cAMP (cAMP). Achetakinin-2, while acting synergistically with cAMP on the mid-Mt, inhibits secretion by the distal Mt, and the effects can be reversed by cAMP. Using an antibody to the water-specific Drosophila aquaporin (DRIP), we demonstrated that DRIP-like immunoreactivity was found in both the distal and mid-Mt. The distribution of the aquaporin altered in response to stimulation and was consistent with the secretory data. The regulation of secretion in Acheta Mt is quite different from that of Drosophila, with both cation and anion/water transport occurring in the same cells. This is the first demonstration of the presence of an insect aquaporin, namely DRIP, in the Mt of an order other than the Diptera.

  1. MRI characteristics of the glia limitans externa: A 7T study.

    Science.gov (United States)

    Suzuki, Kiyotaka; Yamada, Kenichi; Nakada, Kazunori; Suzuki, Yuji; Watanabe, Masaki; Kwee, Ingrid L; Nakada, Tsutomu

    2017-12-01

    To perform a systematic analysis of the intrinsic contrast parameters of the FLAIR hyperintense rim (FHR), a thin layer of high intensity covering the entire surface of the cerebral cortex detected on fluid-attenuated inversion recovery (FLAIR) sequence T2 weighted imaging performed on a 7T system, in an attempt to identify its anatomical correlate. Fast spin echo inversion recovery (FSE-IR) and cardiac-gated fast spin echo (FSE) images were obtained with defined parameters in eight normal volunteers on a 7 T MRI system to determine T2 and proton density, T1 characteristics. K-means clustering analysis of parameter sets was performed using MATLAB version R2015b for the purpose of identifying the cluster reflecting FHR. The results were subsequently confirmed by independent component analysis (ICA) based on T1 behavior on FSE-IR using a MATLAB script of FastICA algorithm. The structure giving rise to FHR was found to have a unique combination of intrinsic contrast parameters of low proton density, long T2, and disproportionally short T1. The findings are in strong agreement with the functional and structural specifics of the glia limitans externa (GLE), a structure composed of snuggled endfeet of astrocytes containing abundant aquaporin-4 (AQP-4), the main water channel of the brain. Intrinsic contrast parameters of FHR reflect structural and functional specifics of the GLE, and their values are highly dependent on the physiologic functionality of AQP-4. Microscopic imaging on a 7T system and analysis of GLE contrast parameters can be developed into a method for evaluating AQP-4 functionality. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Overlapping demyelinating syndromes and anti-NMDA receptor encephalitis

    Science.gov (United States)

    Titulaer, Maarten J.; Höftberger, Romana; Iizuka, Takahiro; Leypoldt, Frank; McCracken, Lindsey; Cellucci, Tania; Benson, Leslie A.; Shu, Huidy; Irioka, Takashi; Hirano, Makito; Singh, Gagandeep; Calvo, Alvaro Cobo; Kaida, Kenichi; Morales, Pamela S.; Wirtz, Paul W.; Yamamoto, Tomotaka; Reindl, Markus; Rosenfeld, Myrna R.; Graus, Francesc; Saiz, Albert; Dalmau, Josep

    2014-01-01

    Objective To report the clinical, radiological, and immunological association of demyelinating disorders with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Methods Clinical and radiological analysis of a cohort of 691 patients with anti-NMDAR encephalitis. Determination of antibodies to NMDAR, aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) was performed using brain immunohistochemistry and cell-based assays. Results Twenty-three of 691 patients with anti-NMDAR encephalitis had prominent MRI and/or clinical features of demyelination. Group 1 included 12 patients in whom anti-NMDAR encephalitis was preceded or followed by independent episodes of NMO-spectrum disorder (5 cases, 4 anti-AQP4-positive), or brainstem or multifocal demyelinating syndromes (7 cases, all anti-MOG-positive). Group 2 included 11 patients in whom anti-NMDAR encephalitis occurred simultaneously with MRI and symptoms compatible with demyelination (5 AQ4-positive, 2 MOG-positive). Group 3 (136 controls) included 50 randomly selected patients with typical anti-NMDAR encephalitis, 56 with NMO, and 30 with multiple sclerosis: NMDAR-antibodies were detected only in the 50 anti-NMDAR patients, MOG-antibodies in 3/50 anti-NMDAR and 1/56 NMO patients, and AQP4-antibodies in 48/56 NMO and 1/50 anti-NMDAR patients (pdemyelinating episodes required more intensive therapy and resulted in more residual deficits. Only 1/23 NMDAR patients with signs of demyelination had ovarian teratoma compared with 18/50 anti-NMDAR controls (p=0.011) Interpretation Patients with anti-NMDAR encephalitis may develop concurrent or separate episodes of demyelinating disorders, and conversely patients with NMO or demyelinating disorders with atypical symptoms (e.g., dyskinesias, psychosis) may have anti-NMDAR encephalitis. PMID:24700511

  3. Overlapping demyelinating syndromes and anti–N-methyl-D-aspartate receptor encephalitis.

    Science.gov (United States)

    Titulaer, Maarten J; Höftberger, Romana; Iizuka, Takahiro; Leypoldt, Frank; McCracken, Lindsey; Cellucci, Tania; Benson, Leslie A; Shu, Huidy; Irioka, Takashi; Hirano, Makito; Singh, Gagandeep; Cobo Calvo, Alvaro; Kaida, Kenichi; Morales, Pamela S; Wirtz, Paul W; Yamamoto, Tomotaka; Reindl, Markus; Rosenfeld, Myrna R; Graus, Francesc; Saiz, Albert; Dalmau, Josep

    2014-03-01

    To report the clinical, radiological, and immunological association of demyelinating disorders with anti–Nmethyl- D-aspartate receptor (NMDAR) encephalitis. Clinical and radiological analysis was done of a cohort of 691 patients with anti-NMDAR encephalitis. Determination of antibodies to NMDAR, aquaporin-4 (AQP4), and myelin oligodendrocyte glycoprotein (MOG) was performed using brain immunohistochemistry and cell-based assays. Twenty-three of 691 patients with anti-NMDAR encephalitis had prominent magnetic resonance imaging (MRI) and/or clinical features of demyelination. Group 1 included 12 patients in whom anti-NMDAR encephalitis was preceded or followed by independent episodes of neuromyelitis optica (NMO) spectrum disorder (5 cases, 4 anti-AQP4 positive) or brainstem or multifocal demyelinating syndromes (7 cases, all anti-MOG positive). Group 2 included 11 patients in whom anti-NMDAR encephalitis occurred simultaneously with MRI and symptoms compatible with demyelination (5 AQ4 positive, 2 MOG positive). Group 3 (136 controls) included 50 randomly selected patients with typical anti-NMDAR encephalitis, 56 with NMO, and 30 with multiple sclerosis; NMDAR antibodies were detected only in the 50 anti-NMDAR patients, MOG antibodies in 3 of 50 anti-NMDAR and 1 of 56 NMO patients, and AQP4 antibodies in 48 of 56 NMO and 1 of 50 anti-NMDAR patients (pdemyelinating episodes required more intensive therapy and resulted in more residual deficits. Only 1 of 23 NMDAR patients with signs of demyelination had ovarian teratoma compared with 18 of 50 anti-NMDAR controls (p50.011). Patients with anti-NMDAR encephalitis may develop concurrent or separate episodes of demyelinating disorders, and conversely patients with NMO or demyelinating disorders with atypical symptoms (eg, dyskinesias, psychosis) may have anti-NMDAR encephalitis.

  4. Time-course of glial changes in the hyperhomocysteinemia model of vascular cognitive impairment and dementia (VCID).

    Science.gov (United States)

    Sudduth, Tiffany L; Weekman, Erica M; Price, Brittani R; Gooch, Jennifer L; Woolums, Abigail; Norris, Christopher M; Wilcock, Donna M

    2017-01-26

    Vascular cognitive impairment and dementia (VCID) is the second leading cause of dementia behind Alzheimer's disease (AD) and is a frequent co-morbidity with AD. Despite its prevalence, little is known about the molecular mechanisms underlying the cognitive dysfunction resulting from cerebrovascular disease. Astrocytic end-feet almost completely surround intraparenchymal blood vessels in the brain and express a variety of channels and markers indicative of their specialized functions in the maintenance of ionic and osmotic homeostasis and gliovascular signaling. These functions are mediated by end-foot enrichment of the aquaporin 4 water channel (AQP4), the inward rectifying potassium channel Kir4.1 and the calcium-dependent potassium channel MaxiK. Using our hyperhomocysteinemia (HHcy) model of VCID we examined the time-course of astrocytic end-foot changes along with cognitive and neuroinflammatory outcomes. We found that there were significant astrocytic end-foot disruptions in the HHcy model. AQP4 becomes dislocalized from the end-feet, there is a loss of Kir4.1 and MaxiK protein expression, as well as a loss of the Dp71 protein known to anchor the Kir4.1, MaxiK and AQP4 channels to the end-foot membrane. Neuroinflammation occurs prior to the astrocytic changes, while cognitive impairment continues to decline with the exacerbation of the astrocytic changes. We have previously reported similar astrocytic changes in models of cerebral amyloid angiopathy (CAA) and therefore, we believe astrocytic end-foot disruption could represent a common cellular mechanism of VCID and may be a target for therapeutic development. Copyright © 2016. Published by Elsevier Ltd.

  5. Neuro-ophthalmic manifestation of neuromyelitis optica spectrum disorders

    Directory of Open Access Journals (Sweden)

    Xiao-jun ZHANG

    2014-10-01

    Full Text Available Neuromyelitis optica spectrum disorders (NMOSDs include classic neuromyelitis optica (NMO, opticospinal multiple sclerosis (OSMS, limited form of NMO and isolated optic neuritis or myelitis accompanied by either systemic autoimmune diseases or typical MRI findings of NMO. The common neuro-ophthalmic features of NMOSDs include simultaneous or consecutive bilateral optic neuritis, more commonly seen optic disk edema and surrounding exudate, poor visual recovery, steroid responsiveness and dependency. Combined with serum aquaporin 4 (AQP4 antibody and brain MRI examination, these clinical features can be helpful to the early differential diagnosis between NMOSDs and MS. Some types of eye movement abnormalities have been reported in patients with NMOSDs, but further investigation needs to be done before the specificity of these features are confirmed. doi: 10.3969/j.issn.1672-6731.2014.10.003

  6. Diagnostic value of NMO-IgG in demyelinating diseases of central nervous system

    Directory of Open Access Journals (Sweden)

    Xiao-min XU

    2016-09-01

    Full Text Available The aquaporin 4 (AQP4 plays an important role in the maintenance of transmembrane water transfer, blood-brain barrier (BBB integrity and homeostasis of central nervous system, and its highly specific autoantibody NMO-IgG has been used as a specific biomarker of neuromyelitis optica. However, in recent years, several studies have found that the positive rate in patients with neuromyelitis optica is not 100%, and it even can be detected in some other demyelinating diseases of central nervous system. This paper aims to make a review of the diagnostic value of NMO-IgG in demyelinating diseases of central nervous system, in order to deepen the understanding of this antibody and guide the clinical diagnosis and differential diagnosis on demyelinating diseases of central nervous system. DOI: 10.3969/j.issn.1672-6731.2016.09.006

  7. Aquaporin-mediated long-distance polyphosphate translocation directed towards the host in arbuscular mycorrhizal symbiosis: application of virus-induced gene silencing.

    Science.gov (United States)

    Kikuchi, Yusuke; Hijikata, Nowaki; Ohtomo, Ryo; Handa, Yoshihiro; Kawaguchi, Masayoshi; Saito, Katsuharu; Masuta, Chikara; Ezawa, Tatsuhiro

    2016-09-01

    Arbuscular mycorrhizal fungi translocate polyphosphate through hyphae over a long distance to deliver to the host. More than three decades ago, suppression of host transpiration was found to decelerate phosphate delivery of the fungal symbiont, leading us to hypothesize that transpiration provides a primary driving force for polyphosphate translocation, probably via creating hyphal water flow in which fungal aquaporin(s) may be involved. The impact of transpiration suppression on polyphosphate translocation through hyphae of Rhizophagus clarus was evaluated. An aquaporin gene expressed in intraradical mycelia was characterized and knocked down by virus-induced gene silencing to investigate the involvement of the gene in polyphosphate translocation. Rhizophagus clarus aquaporin 3 (RcAQP3) that was most highly expressed in intraradical mycelia encodes an aquaglyceroporin responsible for water transport across the plasma membrane. Knockdown of RcAQP3 as well as the suppression of host transpiration decelerated polyphosphate translocation in proportion to the levels of knockdown and suppression, respectively. These results provide the first insight into the mechanism underlying long-distance polyphosphate translocation in mycorrhizal associations at the molecular level, in which host transpiration and the fungal aquaporin play key roles. A hypothetical model of the translocation is proposed for further elucidation of the mechanism. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  8. Ischemic postconditioning alleviates lung injury and maintains a better expression of aquaporin-1 during cardiopulmonary bypass.

    Science.gov (United States)

    Cheng, Chi; Li, Shanshan; Wang, Yong; Chen, Song; You, Lu; Zhang, Hong

    2014-01-01

    It has found that ischemic postconditioning (IPO) might decrease pulmonary ischemia/reperfusion (I/R) injury, which is one of the main reasons of lung injury caused by cardiopulmonary bypass (CPB). It was found that aquaporins (AQPs) play a role in the maintenance of fluid homeostasis. But it is still unclear whether IPO influences the expression of aquaporin-1 (AQP1). This study was designed to investigate whether IPO can reduce CPB-related lung injury and affect the expression of AQP1 of lungs. Twelve healthy dogs were divided into control group (C group) and ischemia postconditioning group (IPO group). CPB procedures were implemented. Ten minutes later, the left pulmonary artery was separated and blocked. Postconditioning consisted of two cycles of 5-minute pulmonary artery reperfusion/5-minute reocclusion starting at the beginning of reperfusion. The 2×4 cm tissues of both sides of pulmonary apex, superior, middle and inferior lobe were taken before CPB (T1), before occlusion and reopening of left pulmonary artery (T2, T3), and 2 hours after CPB (T4). Samples were used to evaluate lung injury degrees and to detect the expression of AQP1. At T1 and T4, blood was collected from femoral artery to calculate pulmonary function. At T4, each pulmonary function showed significant deterioration compared with T1. Lung injury could be found at the onset of CPB. However, the expression of AQP1 decreased and wet to dry weight ratio (W/D) increased after T2. In the left lung of C group, the worst pulmonary function and structures were detected. The slightest changes were discovered in the right lung of C group. A close relationship between W/D and lung injury score was found. The lung injury score was negatively related with the expression of AQP1. It was found that the expression of AQP1 was negatively connected with W/D. In dog CPB models, lung injury induced by CPB was related with down regulated expression of AQP1. AQP1 is believed to be involved in the mechanisms of

  9. Seronegative Neuromyelitis Optica: A Case Report of a Hispanic Male

    Directory of Open Access Journals (Sweden)

    Nabeel Badri

    2016-05-01

    Full Text Available Neuromyelitis optica (NMO is a rare disease, common in white females and rarely reported in Hispanic males. It is usually associated with recurrent demyelinating spectrum that is autoimmune in nature. The diagnosis is usually confirmed by antibody biomarkers; however, they can be negative and lead to more dilemma in diagnosis. Furthermore, the course of disease and prognosis are different in seronegative as compared to seropositive NMO. Treatment is similar in both subgroups with new approaches under investigation for seronegative NMO patients. We present an interesting case of a 37-year-old Hispanic male who presented with sudden onset of lower extremity weakness, numbness, blurry vision, and urinary retention. Magnetic resonance imaging (MRI of the thoracic spine showed multiphasic demyelinating process involving the thoracic spinal cord. His brain MRI also revealed changes suggesting optic neuritis. The patient met the criteria for diagnosis of NMO by having optic neuritis and myelitis by imaging studies despite having negative aquaporin-4 antibodies (AQP4-Ab. His condition improved after plasma exchange. NMO can be difficult to distinguish from acute multiple sclerosis in the early stages of the disease. Having AQP4-Ab testing is important for diagnosis with imaging studies; however, negative antibody results cannot exclude the diagnosis, but rather group it in seronegative subtype. Ongoing studies and research suggest that seronegative NMO might have a different pathophysiology, manifestation, and prognosis.

  10. Brain Basics

    Medline Plus

    Full Text Available ... Brain Research Glossary Brain Basics (PDF, 10 pages) Introduction Watch the Brain Basics video Welcome. Brain Basics provides information on how the brain works, how mental illnesses ...

  11. Brain Basics

    Science.gov (United States)

    ... Events About Us Home > Health & Education > Educational Resources Brain Basics Introduction The Growing Brain The Working Brain ... to mental disorders, such as depression. The Growing Brain Inside the Brain: Neurons & Neural Circuits Neurons are ...

  12. Brain Basics

    Medline Plus

    Full Text Available ... Events About Us Home > Health & Education > Educational Resources Brain Basics Introduction The Growing Brain The Working Brain ... to mental disorders, such as depression. The Growing Brain Inside the Brain: Neurons & Neural Circuits Neurons are ...

  13. Brain Basics

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    Full Text Available ... Brain Basics provides information on how the brain works, how mental illnesses are disorders of the brain, ... learning more about how the brain grows and works in healthy people, and how normal brain development ...

  14. Gβγ Signaling Regulates Aquaporin-2 Trafficking and Urinary Concentration

    DEFF Research Database (Denmark)

    Olesen, Emma Tina Bisgaard; Poulsen, Søren Brandt; MacAulay, Nanna

    2016-01-01

    Whole body water homeostasis is regulated by signaling cascades activated following stimulation of a range of 7-transmembrane receptors in the kidney. These receptors signal through heterotrimeric G proteins, and include the type 2 vasopressin receptor (V2R) and prostaglandin receptors EP2 and EP4.......The G protein α-subunit mediates cAMP signaling, which is thought to play a major role in increasing water transport by increasing aquaporin-2 (AQP2) apical membrane accumulation in the collecting duct. The role of other G protein subunits, namely of βγ subunits, for AQP2 regulation is unknown...... µM) and/or the adenylyl cyclase inhibitor SQ22536 (500 µM) followed by stimulation with agonists for EP2 (butaprost 50 nM), EP4 (CAY10598 1.3 µM) or V2R (dDAVP 1 nM). In MDCK cells, gallein abolished AQP2 apical membrane accumulation induced by CAY10598, but had no significant effect on butaprost...

  15. Dexamethasone increases aquaporin-2 protein expression in ex vivo inner medullary collecting duct suspensions

    Directory of Open Access Journals (Sweden)

    Minguang eChen

    2015-11-01

    Full Text Available Aquaporin-2 (AQP2 is the vasopressin-regulated water channel that controls renal water reabsorption and plays an important role in the maintenance of body water homeostasis. However, whether and how glucocorticoid regulates AQP2 remains unclear. In this study, we examined the direct effect of dexamethasone on AQP2 protein expression and activity. Dexamethasone increased AQP2 protein abundance in rat inner medullary collecting duct suspensions. This was confirmed in HEK293 cells transfected with AQP2 cDNA. Cell surface protein biotinylation showed an increase of dexamethasone-induced cell membrane AQP2 expression and this effect was blocked by glucocorticoid receptor antagonist RU486. Functionally, dexamethasone treatment of oocytes injected with an AQP2 cRNA increased water transport activity as judged by cell rupture time in a hypo-osmotic solution (66 ± 13s in dexamethasone vs 101 ± 11s in control, n=15. We further found that dexamethasone treatment reduced AQP2 degradation, which could result in an increase of AQP2 protein. Interestingly, dexamethasone promoted cell membrane AQP2 moving to less buoyant lipid raft submicrodomains. Taken together, our data demonstrate that dexamethasone promotes AQP2 protein expression and increases water permeability mainly via inhibition of AQP2 protein degradation. The increase in AQP2 activity promotes water reabsorption, which may contribute to glucocorticoid-induced water retention and hypertension.

  16. Hydrogen peroxide effects on root hydraulic properties and plasma membrane aquaporin regulation in Phaseolus vulgaris.

    Science.gov (United States)

    Benabdellah, Karim; Ruiz-Lozano, Juan Manuel; Aroca, Ricardo

    2009-08-01

    In the last few years, the role of reactive oxygen species as signaling molecules has emerged, and not only as damage-related roles. Here, we analyzed how root hydraulic properties were modified by different hydrogen peroxide (H2O2) concentrations applied exogenously to the root medium. Two different experimental setups were employed: Phaseolus vulgaris plants growing in hydroponic or in potted soils. In both experimental setups, we found an increase of root hydraulic conductance (L) in response to H2O2 application for the first time. Twenty millimolar was the threshold concentration of H2O2 for observing an effect on L in the soil experiment, while in the hydroponic experiment, a positive effect on L was observed at 0.25 mM H2O2. In the hydroponic experiment, a correlation between increased L and plasma membrane aquaporin amount and their root localization was observed. These findings provide new insights to study how several environmental factors modify L.

  17. Role of Aquaporins in a Composite Model of Water Transport in the Leaf

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    Adi Yaaran

    2016-06-01

    Full Text Available Water-transport pathways through the leaf are complex and include several checkpoints. Some of these checkpoints exhibit dynamic behavior that may be regulated by aquaporins (AQPs. To date, neither the relative weight of the different water pathways nor their molecular mechanisms are well understood. Here, we have collected evidence to support a putative composite model of water pathways in the leaf and the distribution of water across those pathways. We describe how water moves along a single transcellular path through the parenchyma and continues toward the mesophyll and stomata along transcellular, symplastic and apoplastic paths. We present evidence that points to a role for AQPs in regulating the relative weight of each path in the overall leaf water-transport system and the movement of water between these paths as a result of the integration of multiple signals, including transpiration demand, water potential and turgor. We also present a new theory, the hydraulic fuse theory, to explain effects of the leaf turgor-loss-point on water paths alternation and the subsequent reduction in leaf hydraulic conductivity. An improved understating of leaf water-balance management may lead to the development of crops that use water more efficiently, and responds better to environmental changes.

  18. Relationship between hexokinase and the aquaporin PIP1 in the regulation of photosynthesis and plant growth.

    Directory of Open Access Journals (Sweden)

    Gilor Kelly

    Full Text Available Increased expression of the aquaporin NtAQP1, which is known to function as a plasmalemma channel for CO₂ and water, increases the rate of both photosynthesis and transpiration. In contrast, increased expression of Arabidopsis hexokinase1 (AtHXK1, a dual-function enzyme that mediates sugar sensing, decreases the expression of photosynthetic genes and the rate of transpiration and inhibits growth. Here, we show that AtHXK1 also decreases root and stem hydraulic conductivity and leaf mesophyll CO₂ conductance (g(m. Due to their opposite effects on plant development and physiology, we examined the relationship between NtAQP1 and AtHXK1 at the whole-plant level using transgenic tomato plants expressing both genes simultaneously. NtAQP1 significantly improved growth and increased the transpiration rates of AtHXK1-expressing plants. Reciprocal grafting experiments indicated that this complementation occurs when both genes are expressed simultaneously in the shoot. Yet, NtAQP1 had only a marginal effect on the hydraulic conductivity of the double-transgenic plants, suggesting that the complementary effect of NtAQP1 is unrelated to shoot water transport. Rather, NtAQP1 significantly increased leaf mesophyll CO₂ conductance and enhanced the rate of photosynthesis, suggesting that NtAQP1 facilitated the growth of the double-transgenic plants by enhancing mesophyll conductance of CO₂.

  19. 24-hour rhythm of aquaporin-3 function in the epidermis is regulated by molecular clocks.

    Science.gov (United States)

    Matsunaga, Naoya; Itcho, Kazufumi; Hamamura, Kengo; Ikeda, Eriko; Ikeyama, Hisako; Furuichi, Yoko; Watanabe, Miyako; Koyanagi, Satoru; Ohdo, Shigehiro

    2014-06-01

    Aquaporin 3 (AQP3) is located in the basal layer of the epidermis and regulates biological functions of skin such as water content and trans-epidermal water loss. A recent study showed that the biological function of skin exhibits a 24-hour rhythm, but the molecular mechanism of the variation remains poorly understood. Here we show that mice mutated in the core clock component CLOCK (Clk/Clk) show decreased stratum corneum hydration. An extensive search for the underlying cause led us to identify AQP3 as a new regulator to control the 24-hour variation in biological functions of skin. In mouse epidermis of wild-type mice, mAqp3 exhibits circadian rhythms; however, these are significantly decreased in Clk/Clk. Luciferase reporter gene analysis revealed that transcription of mAqp3 is activated by D-site-binding protein, a clock gene. A human homolog, hAQP3, also exhibited significant oscillation in human keratinocyte (HaCaT) cells synchronized with medium containing 50% serum, and this rhythm was regulated by the endogenous CLOCK/BMAL1 heterodimer. These data indicate that although the molecular mechanisms underlying the rhythmic expression of mAqp3 and hAQP3 are different, clock genes are involved in time-dependent skin hydration. Our current findings provide a molecular link between the circadian clock and AQP3 function in mouse dorsal skin and HaCaT cells.

  20. Overexpression of the wheat aquaporin gene, TaAQP7, enhances drought tolerance in transgenic tobacco.

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    Shiyi Zhou

    Full Text Available Aquaporin (AQP proteins have been shown to transport water and other small molecules through biological membranes, which is crucial for plants to combat stress caused by drought. However, the precise role of AQPs in drought stress response is not completely understood in plants. In this study, a PIP2 subgroup gene AQP, designated as TaAQP7, was cloned and characterized from wheat. Expression of TaAQP7-GFP fusion protein revealed its localization in the plasma membrane. TaAQP7 exhibited high water channel activity in Xenopus laevis oocytes and TaAQP7 transcript was induced by dehydration, and treatments with polyethylene glycol (PEG, abscisic acid (ABA and H(2O(2. Further, TaAQP7 was upregulated after PEG treatment and was blocked by inhibitors of ABA biosynthesis, implying that ABA signaling was involved in the upregulation of TaAQP7 after PEG treatment. Overexpression of TaAQP7 increased drought tolerance in tobacco. The transgenic tobacco lines had lower levels of malondialdehyde (MDA and H(2O(2, and less ion leakage (IL, but higher relative water content (RWC and superoxide dismutase (SOD and catalase (CAT activities when compared with the wild type (WT under drought stress. Taken together, our results show that TaAQP7 confers drought stress tolerance in transgenic tobacco by increasing the ability to retain water, reduce ROS accumulation and membrane damage, and enhance the activities of antioxidants.

  1. Heterologous Expression of Tulip Petal Plasma Membrane Aquaporins in Pichia pastoris for Water Channel Analysis▿

    Science.gov (United States)

    Azad, Abul Kalam; Sawa, Yoshihiro; Ishikawa, Takahiro; Shibata, Hitoshi

    2009-01-01

    Water channels formed by aquaporins (AQPs) play an important role in the control of water homeostasis in individual cells and in multicellular organisms. Plasma membrane intrinsic proteins (PIPs) constitute a subclass of plant AQPs. TgPIP2;1 and TgPIP2;2 from tulip petals are members of the PIP family. In this study, we overexpressed TgPIP2;1 and TgPIP2;2 in Pichia pastoris and monitored their water channel activity (WCA) either by an in vivo spheroplast-bursting assay performed after hypo-osmotic shock or by growth assay. Osmolarity, pH, and inhibitors of AQPs, protein kinases (PKs), and protein phosphatases (PPs) affect the WCA of heterologous AQPs in this expression system. The WCA of TgPIP2;2-expressing spheroplasts was affected by inhibitors of PKs and PPs, which indicates that the water channel of this homologue is regulated by phosphorylation in P. pastoris. From the results reported herein, we suggest that P. pastoris can be employed as a heterologous expression system to assay the WCA of PIPs and to monitor the AQP-mediated channel gating mechanism, and it can be developed to screen inhibitors/effectors of PIPs. PMID:19251885

  2. Heterologous expression of tulip petal plasma membrane aquaporins in Pichia pastoris for water channel analysis.

    Science.gov (United States)

    Azad, Abul Kalam; Sawa, Yoshihiro; Ishikawa, Takahiro; Shibata, Hitoshi

    2009-05-01

    Water channels formed by aquaporins (AQPs) play an important role in the control of water homeostasis in individual cells and in multicellular organisms. Plasma membrane intrinsic proteins (PIPs) constitute a subclass of plant AQPs. TgPIP2;1 and TgPIP2;2 from tulip petals are members of the PIP family. In this study, we overexpressed TgPIP2;1 and TgPIP2;2 in Pichia pastoris and monitored their water channel activity (WCA) either by an in vivo spheroplast-bursting assay performed after hypo-osmotic shock or by growth assay. Osmolarity, pH, and inhibitors of AQPs, protein kinases (PKs), and protein phosphatases (PPs) affect the WCA of heterologous AQPs in this expression system. The WCA of TgPIP2;2-expressing spheroplasts was affected by inhibitors of PKs and PPs, which indicates that the water channel of this homologue is regulated by phosphorylation in P. pastoris. From the results reported herein, we suggest that P. pastoris can be employed as a heterologous expression system to assay the WCA of PIPs and to monitor the AQP-mediated channel gating mechanism, and it can be developed to screen inhibitors/effectors of PIPs.

  3. Phosphorylation of plasma membrane aquaporin regulates temperature-dependent opening of tulip petals.

    Science.gov (United States)

    Azad, Abul Kalam; Sawa, Yoshihiro; Ishikawa, Takahiro; Shibata, Hitoshi

    2004-05-01

    The opening and closing of tulip petals was reproduced in the dark by changing the temperature from 5 degrees C to 20 degrees C for opening and 20 degrees C to 5 degrees C for closing. The opening process was accompanied by (3)H(2)O transport through the stem from the incubation medium to the petals. A Ca(2+)-channel blocker and a Ca(2+)-chelator inhibited petal opening and (3)H(2)O transport. Several proteins in the isolated plasma membrane fraction were phosphorylated in the presence of 25 micro M Ca(2+) at 20 degrees C. The 31-kDa protein that was phosphorylated, was suggested immunologically as the putative plasma membrane aquaporin (PM-AQP). This phosphorylated PM-AQP clearly reacted with the anti-phospho-Ser. In-gel assay revealed the presence of a 45-kDa Ca(2+)-dependent protein kinase in the isolated plasma membrane. Phosphorylation of the putative PM-AQP was thought to activate the water channel composed of PM-AQP. Dephosphorylation of the phosphorylated PM-AQP was also observed during petal closing at 5 degrees C, suggesting the inactivation of the water channel.

  4. Role of Aquaporins in Determining Carbon and Nitrogen Status in Higher Plants

    Directory of Open Access Journals (Sweden)

    Limin Gao

    2018-01-01

    Full Text Available Aquaporins (AQPs are integral membrane proteins facilitating the transport of water and some small neutral molecules across cell membranes. In past years, much effort has been made to reveal the location of AQPs as well as their function in water transport, photosynthetic processes, and stress responses in higher plants. In the present review, we paid attention to the character of AQPs in determining carbon and nitrogen status. The role of AQPs during photosynthesis is characterized as its function in transporting water and CO2 across the membrane of chloroplast and thylakoid; recalculated results from published studies showed that over-expression of AQPs contributed to 25% and 50% increases in stomatal conductance (gs and mesophyll conductance (gm, respectively. The nitrogen status in plants is regulated by AQPs through their effect on water flow as well as urea and NH4+ uptake, and the potential role of AQPs in alleviating ammonium toxicity is discussed. At the same time, root and/or shoot AQP expression is quite dependent on both N supply amounts and forms. Future research directions concerning the function of AQPs in regulating plant carbon and nitrogen status as well as C/N balance are also highlighted.

  5. Relationship between hexokinase and the aquaporin PIP1 in the regulation of photosynthesis and plant growth.

    Science.gov (United States)

    Kelly, Gilor; Sade, Nir; Attia, Ziv; Secchi, Francesca; Zwieniecki, Maciej; Holbrook, N Michele; Levi, Asher; Alchanatis, Victor; Moshelion, Menachem; Granot, David

    2014-01-01

    Increased expression of the aquaporin NtAQP1, which is known to function as a plasmalemma channel for CO₂ and water, increases the rate of both photosynthesis and transpiration. In contrast, increased expression of Arabidopsis hexokinase1 (AtHXK1), a dual-function enzyme that mediates sugar sensing, decreases the expression of photosynthetic genes and the rate of transpiration and inhibits growth. Here, we show that AtHXK1 also decreases root and stem hydraulic conductivity and leaf mesophyll CO₂ conductance (g(m)). Due to their opposite effects on plant development and physiology, we examined the relationship between NtAQP1 and AtHXK1 at the whole-plant level using transgenic tomato plants expressing both genes simultaneously. NtAQP1 significantly improved growth and increased the transpiration rates of AtHXK1-expressing plants. Reciprocal grafting experiments indicated that this complementation occurs when both genes are expressed simultaneously in the shoot. Yet, NtAQP1 had only a marginal effect on the hydraulic conductivity of the double-transgenic plants, suggesting that the complementary effect of NtAQP1 is unrelated to shoot water transport. Rather, NtAQP1 significantly increased leaf mesophyll CO₂ conductance and enhanced the rate of photosynthesis, suggesting that NtAQP1 facilitated the growth of the double-transgenic plants by enhancing mesophyll conductance of CO₂.

  6. Regulation of aquaporin-2 in the kidney: A molecular mechanism of body-water homeostasis

    Directory of Open Access Journals (Sweden)

    Tae-Hwan Kwon

    2013-09-01

    Full Text Available The kidneys play a key role in the homeostasis of body water and electrolyte balance. Aquaporin-2 (AQP2 is the vasopressin-regulated water-channel protein expressed at the connecting tubule and collecting duct, and plays a key role in urine concentration and body-water homeostasis through short-term and long-term regulation of collecting duct water permeability. The signaling transduction pathways resulting in the AQP2 trafficking to the apical plasma membrane of the collecting duct principal cells, including AQP2 phosphorylation, RhoA phosphorylation, actin depolymerization, and calcium mobilization, and the changes of AQP2 abundance in water-balance disorders have been extensively studied. Dysregulation of AQP2 has been shown to be importantly associated with a number of clinical conditions characterized by body-water balance disturbances, including hereditary nephrogenic diabetes insipidus (NDI, lithium-induced NDI, electrolytes disturbance, acute and chronic renal failure, ureteral obstruction, nephrotic syndrome, congestive heart failure, and hepatic cirrhosis. Recent studies exploiting omics technology further demonstrated the comprehensive vasopressin signaling pathways in the collecting ducts. Taken together, these studies elucidate the underlying molecular mechanisms of body-water homeostasis and provide the basis for the treatment of body-water balance disorders.

  7. Expression, localization and possible functions of aquaporins 3 and 8 in rat digestive system.

    Science.gov (United States)

    Zhao, G X; Dong, P P; Peng, R; Li, J; Zhang, D Y; Wang, J Y; Shen, X Z; Dong, L; Sun, J Y

    2016-01-01

    Although aquaporins (AQPs) play important roles in transcellular water movement, their precise quantification and localization remains controversial. We investigated expression levels and localizations of AQP3 and AQP8 and their possible functions in the rat digestive system using real-time polymerase chain reactions, western blot analysis and immunohistochemistry. We investigated the expression levels and localizations of AQP3 and AQP8 in esophagus, forestomach, glandular stomach, duodenum, jejunum, ileum, proximal and distal colon, and liver. AQP3 was expressed in the basolateral membranes of stratified epithelia (esophagus and forestomach) and simple columnar epithelia (glandular stomach, ileum, and proximal and distal colon). Expression was particularly abundant in the esophagus, and proximal and distal colon. AQP8 was found in the subapical compartment of columnar epithelial cells of the jejunum, ileum, proximal colon and liver; the most intense staining occurred in the jejunum. Our results suggest that AQP3 and AQP8 play significant roles in intestinal function and/or fluid homeostasis and may be an important subject for future investigation of disorders that involve disruption of intestinal fluid homeostasis, such as inflammatory bowel disease and irritable bowel syndrome.

  8. Spreading of porous vesicles subjected to osmotic shocks: the role of aquaporins.

    Science.gov (United States)

    Berthaud, Alice; Quemeneur, François; Deforet, Maxime; Bassereau, Patricia; Brochard-Wyart, Françoise; Mangenot, Stéphanie

    2016-02-07

    Aquaporin 0 (AQP0) is a transmembrane protein specific to the eye lens, involved as a water carrier across the lipid membranes. During eye lens maturation, AQP0s are truncated by proteolytic cleavage. We investigate in this work the capability of truncated AQP0 to conduct water across membranes. We developed a method to accurately determine water permeability across lipid membranes and across proteins from the deflation under osmotic pressure of giant unilamellar vesicles (GUVs) deposited on an adhesive substrate. Using reflection interference contrast microscopy (RICM), we measure the spreading area of GUVs during deswelling. We interpret these results using a model based on hydrodynamic, binder diffusion towards the contact zone, and Helfrich's law for the membrane tension, which allows us to relate the spread area to the vesicle internal volume. We first study the specific adhesion of vesicles coated with biotin spreading on a streptavidin substrate. We then determine the permeability of a single functional AQP0 and demonstrate that truncated AQP0 is no more a water channel.

  9. Modeling detergent organization around aquaporin-0 using small-angle X-ray scattering.

    Science.gov (United States)

    Berthaud, Alice; Manzi, John; Pérez, Javier; Mangenot, Stéphanie

    2012-06-20

    Solubilization of integral membrane proteins in aqueous solutions requires the presence of amphiphilic molecules like detergents. The transmembrane region of the proteins is then surrounded by a corona formed by these molecules, ensuring a hydrophilic outer surface. The presence of this corona has strongly hampered structural studies of solubilized membrane proteins by small-angle X-ray scattering (SAXS), a technique frequently used to monitor conformational changes of soluble proteins. Through the online combination of size exclusion chromatography, SAXS, and refractometry, we have determined a precise geometrical model of the n-dodecyl β-d-maltopyranoside corona surrounding aquaporin-0, the most abundant membrane protein of the eye lens. The SAXS data were well-fitted by a detergent corona shaped in an elliptical toroid around the crystal structure of the protein, similar to the elliptical shape recently reported for nanodiscs (Skar-Gislinge et al. J. Am. Chem. Soc. 2010, 132, 13713-13722). The torus thickness determined from the curve-fitting protocol is in excellent agreement with the thickness of a lipid bilayer, while the number of detergent molecules deduced from the volume of the torus compares well with those obtained on the same sample from refractometry and mass analysis based on SAXS forward scattering. For the first time, the partial specific volume of the detergent surrounding a protein was measured. The present protocol is a crucial step toward future conformational studies of membrane proteins in solution.

  10. Comparative functional analysis of aquaporins/glyceroporins in mammals and anurans.

    Science.gov (United States)

    Krane, Carissa M; Goldstein, David L

    2007-07-01

    Maintenance of fluid homeostasis is critical to establishing and maintaining normal physiology. The landmark discovery of membrane water channels (aquaporins; AQPs) ushered in a new area in osmoregulatory biology that has drawn from and contributed to diverse branches of biology, from molecular biology and genomics to systems biology and evolution, and from microbial and plant biology to animal and translational physiology. As a result, the study of AQPs provides a unique and integrated backdrop for exploring the relationships between genes and genome systems, the regulation of gene expression, and the physiologic consequences of genetic variation. The wide species distribution of AQP family members and the evolutionary conservation of the family indicate that the control of membrane water flux is a critical biological process. AQP function and regulation is proving to be central to many of the pathways involved in individual physiologic systems in both mammals and anurans. In mammals, AQPs are essential to normal secretory and absorptive functions of the eye, lung, salivary gland, sweat glands, gastrointestinal tract, and kidney. In urinary, respiratory, and gastrointestinal systems, AQPs are required for proper urine concentration, fluid reabsorption, and glandular secretions. In anurans, AQPs are important in mediating physiologic responses to changes in the external environment, including those that occur during metamorphosis and adaptation from an aquatic to terrestrial environment and thermal acclimation in anticipation of freezing. Therefore, an understanding of AQP function and regulation is an important aspect of an integrated approach to basic biological research.

  11. Changes in free water fraction and aquaporin function with dwell time during continuous ambulatory peritoneal dialysis.

    Science.gov (United States)

    Stachowska-Pietka, Joanna; Waniewski, Jacek; Vonesh, Edward; Lindholm, Bengt

    2010-12-01

    Diffusive (K(BD), A₀/Δx(t)) transport parameters and sieving coefficients (S) for small solutes and free water fraction (FWF), that is, the fraction of total water flow that is transported through aquaporins, were assessed as functions of dwell time t for 35 continuous ambulatory peritoneal dialysis patients using glucose 3.86% dialysis fluid.The individual values of the unrestricted pore area over diffusion distance, A₀/Δx(t), were estimated using the mixed effects nonlinear regression and applied for evaluation of S(t) for sodium and FWF(t). FWF decreased on average from the initial 51% of the total transcapillary water flow to 36% at 120 min, whereas the small pore water fraction and sodium sieving coefficient increased. Our results were consistent with the three-pore model if the contribution of the transcellular pores (α(TP)) at the beginning of dwell study was doubled and later decreased to the standard value of 0.02.We conclude that transport characteristics of fluid and small solutes should be considered as time-dependent variables during the peritoneal dialysis.

  12. Cholesterol can modulate mitochondrial aquaporin-8 expression in human hepatic cells.

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    Danielli, Mauro; Capiglioni, Alejo M; Marrone, Julieta; Calamita, Giuseppe; Marinelli, Raúl A

    2017-05-01

    Hepatocyte mitochondrial aquaporin-8 (mtAQP8) works as a multifunctional membrane channel protein that facilitates the uptake of ammonia for its detoxification to urea as well as the mitochondrial release of hydrogen peroxide. Since early oligonucleotide microarray studies in liver of cholesterol-fed mice showed an AQP8 downregulation, we tested whether alterations of cholesterol content per se modulate mtAQP8 expression in human hepatocyte-derived Huh-7 cells. Cholesterol loading with methyl-β-cyclodextrin (mβCD):cholesterol complexes downregulated the proteolytic activation of cholesterol-responsive sterol regulatory element-binding protein (SREBP) transcriptions factors 1 and 2, and the expression of the target gene 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Under such conditions, mtAQP8 mRNA and protein expressions were significantly reduced. In contrast, cholesterol depletion using mβCD alone increased SREBP-1 and 2 activation and upregulated HMGCR and mtAQP8 mRNA and protein expressions. The results suggest that cholesterol can regulate transcriptionally human hepatocyte mtAQP8 expression likely via SREBPs. The functional implications of our findings are discussed. © 2017 IUBMB Life, 69(5):341-346, 2017. © 2017 International Union of Biochemistry and Molecular Biology.

  13. Basolateral cholesterol depletion alters Aquaporin-2 post-translational modifications and disrupts apical plasma membrane targeting.

    Science.gov (United States)

    Moeller, Hanne B; Fuglsang, Cecilia Hvitfeldt; Pedersen, Cecilie Nøhr; Fenton, Robert A

    2018-01-01

    Apical plasma membrane accumulation of the water channel Aquaporin-2 (AQP2) in kidney collecting duct principal cells is critical for body water homeostasis. Posttranslational modification (PTM) of AQP2 is important for regulating AQP2 trafficking. The aim of this study was to determine the role of cholesterol in regulation of AQP2 PTM and in apical plasma membrane targeting of AQP2. Cholesterol depletion from the basolateral plasma membrane of a collecting duct cell line (mpkCCD14) using methyl-beta-cyclodextrin (MBCD) increased AQP2 ubiquitylation. Forskolin, cAMP or dDAVP-mediated AQP2 phosphorylation at Ser269 (pS269-AQP2) was prevented by cholesterol depletion from the basolateral membrane. None of these effects on pS269-AQP2 were observed when cholesterol was depleted from the apical side of cells, or when MBCD was applied subsequent to dDAVP stimulation. Basolateral, but not apical, MBCD application prevented cAMP-induced apical plasma membrane accumulation of AQP2. These studies indicate that manipulation of the cholesterol content of the basolateral plasma membrane interferes with AQP2 PTM and subsequently regulated apical plasma membrane targeting of AQP2. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Functional interactome of Aquaporin 1 sub-family reveals new physiological functions in Arabidopsis Thaliana

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    Mohamed Ragab Abdel Gawwad

    2013-09-01

    Full Text Available Aquaporins are channel proteins found in plasma membranes and intercellular membranes of different cellular compartments, facilitate the water flux, solutes and gases across the cellular plasma membranes. The present study highlights the sub-family plasma membrane intrinsic protein (PIP predicting the 3-D structure and analyzing the functional interactome of it homologs. PIP1 homologs integrate with many proteins with different plant physiological roles in Arabidopsis thaliana including; PIP1A and PIP1B: facilitate the transport of water, diffusion of amino acids and/or peptides from the vacuolar compartment to the cytoplasm, play a role in the control of cell turgor and cell expansion and involved in root water uptake respectively. In addition we found that PIP1B plays a defensive role against Pseudomonas syringae infection through the interaction with the plasma membrane Rps2 protein. Another substantial function of PIP1C via the interaction with PIP2E is the response to nematode infection. Generally, PIP1 sub-family interactome controlling many physiological processes in plant cell like; osmoregulation in plants under high osmotic stress such as under a high salt, response to nematode, facilitate the transport of water across cell membrane and regulation of floral initiation in Arabidopsis thaliana.

  15. Molecular imaging of aquaglycero-aquaporins: its potential for cancer characterization.

    Science.gov (United States)

    Saito, Yuriko; Furukawa, Takako; Obata, Takayuki; Saga, Tsuneo

    2013-01-01

    Aquaglycero-aquaporins (agAQPs) are one of the water channel proteins located in the cell membrane that transport not only water but also some small solutes such as glycerol. Since agAQPs are involved in cancer proliferation and malignancy, it might be possible to utilize them as new targets for cancer molecular imaging. In this study, we investigated whether agAQPs can be specifically targeted by using [(14)C]-labeled glycerol ([(14)C]glycerol), which passes through agAQPs. In the in vitro experiments, comparing the cancer cell lines with different expression levels of AQP3 and AQP9, major agAQPs known to be expressed in cancers, and examining the effect of their inhibitors on these cells, the expression of AQP3 and AQP9 in cell lines was shown to be closely related to [(14)C]glycerol uptake. When [(14)C]glycerol was injected into tumor-bearing mice, Spearman's rank coefficient analysis revealed that radioactivity levels in tumor and in plasma were mutually correlated only in tumors expressing agAQPs at a high level. These results indicate the possibility of using agAQPs as new targets to characterize cancer using radiolabeled glycerol as a molecular probe.

  16. [Peritoneal dialysis adequacy in pediatrics. From the peritoneal equilibration test to the aquaporins].

    Science.gov (United States)

    Bolte, Lillian; Cano, Francisco

    2015-01-01

    An evaluation of the characteristics of peritoneal solute and water transport is essential to assess the suitability of prescribing dialysis in patients suffering from chronic renal disease. There are currently a series of models to perform this evaluation. The peritoneal equilibration test (PET) evaluates the peritoneal transport capacity, classifying the patients into four transport categories: high, high-average, low-average, and low. The short PET enables the same evaluation to be made in only 2hours, and has been validated in paediatric patients. On the other hand, the MiniPET provides additional information by evaluating the free water transport capacity by the ultra-small pores, and the Accelerated Peritoneal Examination Time (APEX) evaluates the time when the glucose and urea equilibration curves cross, and has been proposed as the optimum dwell time to achieve adequate ultrafiltration. An analysis is presented on the current information on these diagnostic methods as regards free water transport via aquaporins, which could be an important tool in optimising solute and water transport in patients on chronic peritoneal dialysis, particularly as regards the cardiovascular prognosis. Copyright © 2015 Sociedad Chilena de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

  17. Molecular Mechanisms of How Mercury Inhibits Water Permeation through Aquaporin-1: Understanding by Molecular Dynamics Simulation

    Science.gov (United States)

    Hirano, Yoshinori; Okimoto, Noriaki; Kadohira, Ikuko; Suematsu, Makoto; Yasuoka, Kenji; Yasui, Masato

    2010-01-01

    Abstract Aquaporin (AQP) functions as a water-conducting pore. Mercury inhibits the water permeation through AQP. Although site-directed mutagenesis has shown that mercury binds to Cys189 during the inhibition process, it is not fully understood how this inhibits the water permeation through AQP1. We carried out 40 ns molecular dynamics simulations of bovine AQP1 tetramer with mercury (Hg-AQP1) or without mercury (Free AQP1). In Hg-AQP1, Cys191 (Cys189 in human AQP1) is converted to Cys-SHg+ in each monomer. During each last 10 ns, we observed water permeation events occurred 23 times in Free AQP1 and never in Hg-AQP1. Mercury binding did not influence the whole structure, but did induce a collapse in the orientation of several residues at the ar/R region. In Free AQP1, backbone oxygen atoms of Gly190, Cys191, and Gly192 lined, and were oriented to, the surface of the water pore channel. In Hg-AQP1, however, the SHg+ of Cys191-SHg+ was oriented toward the outside of the water pore. As a result, the backbone oxygen atoms of Gly190, Cys191, and Gly192 became disorganized and the ar/R region collapsed, thereby obstructing the permeation of water. We suggest that mercury disrupts the water pore of AQP1 through local conformational changes in the ar/R region. PMID:20409470

  18. Negative feedback from CaSR signaling to aquaporin-2 sensitizes vasopressin to extracellular Ca2.

    Science.gov (United States)

    Ranieri, Marianna; Tamma, Grazia; Di Mise, Annarita; Russo, Annamaria; Centrone, Mariangela; Svelto, Maria; Calamita, Giuseppe; Valenti, Giovanna

    2015-07-01

    We previously described that high luminal Ca(2+) in the renal collecting duct attenuates short-term vasopressin-induced aquaporin-2 (AQP2) trafficking through activation of the Ca(2+)-sensing receptor (CaSR). Here, we evaluated AQP2 phosphorylation and permeability, in both renal HEK-293 cells and in the dissected inner medullary collecting duct, in response to specific activation of CaSR with NPS-R568. In CaSR-transfected cells, CaSR activation drastically reduced the basal levels of AQP2 phosphorylation at S256 (AQP2-pS256), thus having an opposite effect to vasopressin action. When forskolin stimulation was performed in the presence of NPS-R568, the increase in AQP2-pS256 and in the osmotic water permeability were prevented. In the freshly isolated inner mouse medullar collecting duct, stimulation with forskolin in the presence of NPS-R568 prevented the increase in AQP2-pS256 and osmotic water permeability. Our data demonstrate that the activation of CaSR in the collecting duct prevents the cAMP-dependent increase in AQP2-pS256 and water permeability, counteracting the short-term vasopressin response. By extension, our results suggest the attractive concept that CaSR expressed in distinct nephron segments exerts a negative feedback on hormones acting through cAMP, conferring high sensitivity of hormone to extracellular Ca(2+). © 2015. Published by The Company of Biologists Ltd.

  19. Aquaporin-3 mediates hydrogen peroxide-dependent responses to environmental stress in colonic epithelia.

    Science.gov (United States)

    Thiagarajah, Jay R; Chang, Jeffrey; Goettel, Jeremy A; Verkman, Alan S; Lencer, Wayne I

    2017-01-17

    The colonic epithelium provides an essential barrier against the environment that is critical for protecting the body and controlling inflammation. In response to injury or gut microbes, colonic epithelial cells produce extracellular hydrogen peroxide (H2O2), which acts as a potent signaling molecule affecting barrier function and host defense. In humans, impaired regulation of H2O2 in the intestine has been associated with early-onset inflammatory bowel disease and colon cancer. Here, we show that signal transduction by H2O2 depends on entry into the cell by transit through aquaporin-3 (AQP3), a plasma membrane H2O2-conducting channel. In response to injury, AQP3-depleted colonic epithelial cells showed defective lamellipodia, focal adhesions, and repair after wounding, along with impaired H2O2 responses after exposure to the intestinal pathogen Citrobacter rodentium Correspondingly, AQP3-/- mice showed impaired healing of superficial wounds in the colon and impaired mucosal innate immune responses against C. rodentium infection, manifested by reduced crypt hyperplasia, reduced epithelial expression of IL-6 and TNF-α, and impaired bacterial clearance. These results elucidate the signaling mechanism of extracellular H2O2 in the colonic epithelium and implicate AQP3 in innate immunity at mucosal surfaces.

  20. Functional Expression of Aquaporin-2 Tagged with Photoconvertible Fluorescent Protein in mpkCCD Cells

    Directory of Open Access Journals (Sweden)

    Kay-Pong Yip

    2015-05-01

    Full Text Available Background: Vasopressin induced trafficking of aquaporin-2 (AQP2 containing vesicles has been studied in kidney cell lines using conventional fluorescent proteins as tags. However, trafficking of fluorescent tagged AQP2, which resembles the vectorial translocation of native AQP2 from cytoplasm to apical membrane has not been demonstrated at real time. Using a photoconvertible fluorescent protein tag on AQP2 might allow the simultaneous tracking of two separate populations of AQP2 vesicle after subcellular local photoconversion. Methods: A spacer was used to link a photoconvertible fluorescent protein (mEos2 to the amino-terminus of AQP2. The DNA constructs were expressed in mpkCCD cells. The trafficking of chimeric protein was visualized with high speed confocal microscopy in 4 dimensions. Results: Chimeric AQP2 expressed in mpkCCD cell conferred osmotic water permeability to the cells. Subcellular photoconversion with a 405 nm laser pulse converted green chimeras to red chimeras locally. Forskolin stimulation triggered chimeric AQP2 to translocate from acidic organelles to apical plasma membrane. By serendipity, the rate of apical accumulation was found to increase when mEos2 was tagged to the carboxyl-terminus in at least one of the AQP2 molecules within the tetramer. Conclusion: Functional photoconvertible chimeric AQP2 was successfully expressed in mpkCCD cells, in which forskolin induced apical trafficking and accumulation of chimeric AQP2. The proof-of-concept to monitor two populations of AQP2 vesicle simultaneously was demonstrated.

  1. Day/night regulation of aquaporins during the CAM cycle in Mesembryanthemum crystallinum.

    Science.gov (United States)

    Vera-Estrella, Rosario; Barkla, Bronwyn J; Amezcua-Romero, Julio C; Pantoja, Omar

    2012-03-01

    Mesembryanthemum crystallinum exhibits induction of Crassulacean acid metabolism (CAM) after a threshold stage of development, by exposure to long days with high light intensities or by water and salt stress. During the CAM cycle, fluctuations in carbon partitioning within the cell lead to transient drops in osmotic potential, which are likely stabilized/balanced by passive movement of water via aquaporins (AQPs). Protoplast swelling assays were used to detect changes in water permeability during the day/night cycle of CAM. To assess the role of AQPs during the same period, we followed transcript accumulation and protein abundance of four plasma membrane intrinsic proteins (PIPs) and one tonoplast intrinsic protein (TIP). CAM plants showed a persistent rhythm of specific AQP protein abundance changes throughout the day/night cycle, including changes in amount of McPIP2;1, McTIP1;2, McPIP1;4 and McPIP1;5, while the abundance of McPIP1;2 was unchanged. These protein changes did not appear to be coordinated with transcript levels for any of the AQPs analysed; however, they did occur in parrallel to alterations in water permeability, as well as variations in cell osmolarity, pinitol, glucose, fructose and phosphoenolpyruvate carboxylase (PEPc) levels measured throughout the day/night CAM cycle. Results suggest a role for AQPs in maintaining water balance during CAM and highlight the complexity of protein expression during the CAM cycle. © 2011 Blackwell Publishing Ltd.

  2. The expression of an aquaporin promoter from Mesembryanthemum crystallinum in tobacco.

    Science.gov (United States)

    Yamada, S; Nelson, D E; Ley, E; Marquez, S; Bohnert, H J

    1997-12-01

    The promoter region of the MipB gene encoding an aquaporin from Mesembryanthemum crystallinum was isolated and used in a transcriptional fusion to control uidA expression in tobacco. The sequence of the promoter was determined for 2 kb upstream of the translation initiation site. Three start sites were utilized with approximately equal frequency, located 176, 170, and 161 bases, respectively, upstream of the translation initiation site. As judged by analysis of GUS expression, promoter MipB retains its specificity in transgenic tobacco. In germinating seedlings, all cells showed GUS expression of different intensities with the strongest signals in root meristems. In older seedlings, GUS staining was observed in rapidly expanding cells--root and apical meristem, and lateral root primordia. In mature plants, strong GUS activity was located to glandular trichomes, subepidermal cells of the stem and petioles, to cells surrounding vascular tissues as well as in xylem parenchyma cells. In immature floral organs, GUS expression was strong in sepals, petals, stamen, and pistil. The intensity declined as they matured. In general, this promoter was active in rapidly expanding cells and cells with high water flux capacity, especially in the xylem parenchyma.

  3. Aquaporins in the antarctic midge, an extremophile that relies on dehydration for cold survival.

    Science.gov (United States)

    Goto, Shin G; Lee, Richard E; Denlinger, David L

    2015-08-01

    The terrestrial midge Belgica antarctica relies extensively on dehydration to survive the low temperatures and desiccation stress that prevail in its Antarctic habitat. The loss of body water is thus a critical adaptive mechanism employed at the onset of winter to prevent injury from internal ice formation; a rapid mechanism for rehydration is equally essential when summer returns and the larva resumes the brief active phase of its life. This important role for water movement suggests a critical role for aquaporins (AQPs). Recent completion of the genome project on this species revealed the presence of AQPs in B. antarctica representing the DRIP, PRIP, BIB, RPIP, and LHIP families. Treatment with mercuric chloride to block AQPs also blocks water loss, thereby decreasing cell survival at low temperatures. Antibodies directed against mammalian or Drosophila AQPs suggest a wide tissue distribution of AQPs in the midge and changes in protein abundance in response to dehydration, rehydration, and freezing. Thus far, functional studies have been completed only for PRIP1. It appears to be a water-specific AQP, but expression levels are not altered by dehydration or rehydration. Functional assays remain to be completed for the additional AQPs. © 2015 Marine Biological Laboratory.

  4. Effects of estrogen deprivation on expression of aquaporins in rat vagina.

    Science.gov (United States)

    Zhu, Jiyin; Xia, Jiyi; Jiang, Jun; Jiang, Rui; He, Yanzheng; Lin, Haocheng

    2015-08-01

    This study aims to investigate the expression of aquaporin (AQP) 0, AQP3, AQP5, AQP6, AQP10, AQP11, and AQP12 in the vaginal tissue of ovariectomized rats. Eight-week-old female Sprague-Dawley rats (n = 18) were randomly divided into three groups: control group (n = 6), ovariectomy group (n = 6), and ovariectomy/estrogen therapy group (n = 6). After 4 weeks, vaginal lubrication level and expression of AQP0, AQP3, AQP5, AQP6, AQP10, AQP11, and AQP12 in vaginal tissue were examined. Serum estrogen level was significantly lower in the ovariectomy group than in the control and ovariectomy/estrogen therapy groups (P < 0.05). Vaginal lubrication was significantly lower in the ovariectomy group (mean [SD], 1.62 [0.30]) than in the control group (mean [SD], 2.37 [0.70]) and ovariectomy/estrogen therapy group (mean [SD], 2.38 [0.73]; P < 0.05). Protein expression of AQP0, AQP3, AQP5, AQP6, AQP10, AQP11, and AQP12 was significantly lower in the ovariectomy group than in the control and ovariectomy/estrogen therapy groups (P < 0.05). Decreased vaginal lubrication in ovariectomized rats after electrostimulation may be partly caused by decreased AQPs in vaginal tissue.

  5. Evaluation of Urinary Aquaporin 2 and Plasma Copeptin as Biomarkers of Effectiveness of Desmopressin Acetate for the Treatment of Monosymptomatic Nocturnal Enuresis.

    Science.gov (United States)

    Hara, Taichi; Ohtomo, Yoshiyuki; Endo, Amane; Niijima, Shinichi; Yasui, Masato; Shimizu, Toshiaki

    2017-10-01

    Desmopressin is a synthetic V2 specific analogue of antidiuretic hormone (arginine vasopressin) that is widely used as first line treatment for monosymptomatic nocturnal enuresis. However, no biomarkers to predict desmopressin effectiveness have yet been established. Because arginine vasopressin is unstable, we prospectively measured the major urine concentration factor aquaporin 2 and serum copeptin (as a surrogate marker for vasopressin) in patients with monosymptomatic nocturnal enuresis, and evaluated whether they are useful for predicting desmopressin treatment outcome. The study included 32 children 6 to 11 years old with monosymptomatic nocturnal enuresis and nocturnal polyuria. Exclusion criteria were daytime urinary symptoms and underlying diseases causing nocturnal enuresis. Subjects were treated with 120 μg or 240 μg desmopressin oral disintegrating tablet and were divided into responders (at 120 or 240 μg) and nonresponders (at 240 μg). Day/night ratios of plasma copeptin and urinary aquaporin 2 were measured during desmopressin treatment. There was no significant difference in baseline day/night ratio of urinary aquaporin 2 between desmopressin responders and nonresponders. After 8 weeks of treatment there was a significant correlation between day/night ratio of aquaporin 2 and percentage of wet nights. In responders (but not nonresponders) there was a significant difference in the change in aquaporin 2 day/night ratio from before treatment to complete remission (p = 0.0004). For plasma copeptin the baseline day/night ratio for responders at 120 μg was significantly lower than in the 240 μg nonresponder group (p = 0.02). Urinary aquaporin 2 appears to be a biomarker of desmopressin treatment effectiveness during therapy, while plasma copeptin levels before treatment are predictive of desmopressin response. Copyright © 2017 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  6. Lentil seed aquaporins form a hetero-oligomer which is phosphorylated by a Mg(2+)-dependent and Ca(2+)-regulated kinase.

    OpenAIRE

    Harvengt, P; Vlerick, A; Fuks, B.; Wattiez, R.; Ruysschaert, J M; Homble, F.

    2000-01-01

    In plants, aquaporins regulate the water flow through membranes during growth, development and stress responses. We have isolated two isoforms of the aquaporin family from the protein-storage vacuoles of lentil (Lens culinaris Med.) seeds. Chemical cross-linking experiments showed that both isoforms belong to the same oligomer in the membrane and are phosphorylated by a membrane-bound protein kinase. We assigned the kinase activity to a 52 kDa protein that is magnesium-dependent and calcium-r...

  7. Behavioral and pathophysiological outcomes associated with caffeine consumption and repetitive mild traumatic brain injury (RmTBI in adolescent rats.

    Directory of Open Access Journals (Sweden)

    Glenn R Yamakawa

    Full Text Available Given that caffeine consumption is exponentially rising in adolescents and they are at increased risk for repetitive mild traumatic brain injury (RmTBI, we sought to examine the pathophysiological outcomes associated with early life caffeine consumption and RmTBI. Adolescent male and female Sprague Dawley rats received either caffeine in the drinking water or normal water and were then randomly assigned to 3 mild injuries using our lateral impact device or 3 sham procedures. Following injury induction, behavioral outcomes were measured with a test battery designed to examine symptoms consistent with clinical manifestation of PCS (balance and motor coordination, anxiety, short-term working memory, and depressive-like behaviours. In addition, pathophysiological outcomes were examined with histological measures of volume and cellular proliferation in the dentate gyrus, as well as microglia activation in the ventromedial hypothalamus. Finally, modifications to expression of 12 genes (Adora2a, App, Aqp4, Bdnf, Bmal1, Clock, Cry, Gfap, Orx1, Orx2, Per, Tau, in the prefrontal cortex, hippocampus, and/or the hypothalamus were assessed. We found that chronic caffeine consumption in adolescence altered normal developmental trajectories, as well as recovery from RmTBI. Of particular importance, many of the outcomes exhibited sex-dependent responses whereby the sex of the animal modified response to caffeine, RmTBI, and the combination of the two. These results suggest that caffeine consumption in adolescents at high risk for RmTBI should be monitored.

  8. Behavioral and pathophysiological outcomes associated with caffeine consumption and repetitive mild traumatic brain injury (RmTBI) in adolescent rats.

    Science.gov (United States)

    Yamakawa, Glenn R; Lengkeek, Connor; Salberg, Sabrina; Spanswick, Simon C; Mychasiuk, Richelle

    2017-01-01

    Given that caffeine consumption is exponentially rising in adolescents and they are at increased risk for repetitive mild traumatic brain injury (RmTBI), we sought to examine the pathophysiological outcomes associated with early life caffeine consumption and RmTBI. Adolescent male and female Sprague Dawley rats received either caffeine in the drinking water or normal water and were then randomly assigned to 3 mild injuries using our lateral impact device or 3 sham procedures. Following injury induction, behavioral outcomes were measured with a test battery designed to examine symptoms consistent with clinical manifestation of PCS (balance and motor coordination, anxiety, short-term working memory, and depressive-like behaviours). In addition, pathophysiological outcomes were examined with histological measures of volume and cellular proliferation in the dentate gyrus, as well as microglia activation in the ventromedial hypothalamus. Finally, modifications to expression of 12 genes (Adora2a, App, Aqp4, Bdnf, Bmal1, Clock, Cry, Gfap, Orx1, Orx2, Per, Tau), in the prefrontal cortex, hippocampus, and/or the hypothalamus were assessed. We found that chronic caffeine consumption in adolescence altered normal developmental trajectories, as well as recovery from RmTBI. Of particular importance, many of the outcomes exhibited sex-dependent responses whereby the sex of the animal modified response to caffeine, RmTBI, and the combination of the two. These results suggest that caffeine consumption in adolescents at high risk for RmTBI should be monitored.

  9. Brain herniation

    Science.gov (United States)

    ... herniation; Uncal herniation; Subfalcine herniation; Tonsillar herniation; Herniation - brain ... Brain herniation occurs when something inside the skull produces pressure that moves brain tissues. This is most ...

  10. Aquaporins are critical for provision of water during lactation and intrauterine progeny hydration to maintain tsetse fly reproductive success.

    Directory of Open Access Journals (Sweden)

    Joshua B Benoit

    2014-04-01

    Full Text Available Tsetse flies undergo drastic fluctuations in their water content throughout their adult life history due to events such as blood feeding, dehydration and lactation, an essential feature of the viviparous reproductive biology of tsetse. Aquaporins (AQPs are transmembrane proteins that allow water and other solutes to permeate through cellular membranes. Here we identify tsetse aquaporin (AQP genes, examine their expression patterns under different physiological conditions (blood feeding, lactation and stress response and perform functional analysis of three specific genes utilizing RNA interference (RNAi gene silencing. Ten putative aquaporins were identified in the Glossina morsitans morsitans (Gmm genome, two more than has been previously documented in any other insect. All organs, tissues, and body parts examined had distinct AQP expression patterns. Two AQP genes, gmmdripa and gmmdripb ( = gmmaqp1a and gmmaqp1b are highly expressed in the milk gland/fat body tissues. The whole-body transcript levels of these two genes vary over the course of pregnancy. A set of three AQPs (gmmaqp5, gmmaqp2a, and gmmaqp4b are expressed highly in the Malpighian tubules. Knockdown of gmmdripa and gmmdripb reduced the efficiency of water loss following a blood meal, increased dehydration tolerance and reduced heat tolerance of adult females. Knockdown of gmmdripa extended pregnancy length, and gmmdripb knockdown resulted in extended pregnancy duration and reduced progeny production. We found that knockdown of AQPs increased tsetse milk osmolality and reduced the water content in developing larva. Combined knockdown of gmmdripa, gmmdripb and gmmaqp5 extended pregnancy by 4-6 d, reduced pupal production by nearly 50%, increased milk osmolality by 20-25% and led to dehydration of feeding larvae. Based on these results, we conclude that gmmDripA and gmmDripB are critical for diuresis, stress tolerance and intrauterine lactation through the regulation of water and

  11. A systematic analysis of the complement pathways in patients with neuromyelitis optica indicates alteration but no activation during remission

    DEFF Research Database (Denmark)

    Veszeli, Nóra; Füst, György; Csuka, Dorottya

    2014-01-01

    Neuromyelitis optica (NMO) is an autoimmune demyelinating inflammatory disorder, mediated by pathogenic autoantibodies against aquaporin 4 (AQP4), the main water channel of the central nervous system (CNS). NMO is characterized by local IgG deposition and complement activation within the CNS, but...

  12. Measuring localization and diffusion coefficients of basolateral proteins in lateral versus basal membranes using functionalized substrates and kICS analysis

    DEFF Research Database (Denmark)

    Marlar, Saw; Christensen, Eva Arnspang; Pedersen, Gitte Albinus

    2014-01-01

    Micropatterning enabled semiquantitation of basolateral proteins in lateral and basal membranes of the same cell. Lateral diffusion coefficients of basolateral aquaporin-3 (AQP3-EGFP) and EGFP-AQP4 were extracted from “lateral” and “basal” membranes using identical live-cell imaging and k-space I...

  13. Regulation of the Water Channel Aquaporin-2 via 14-3-3 Theta (θ) and Zeta (ζ)

    DEFF Research Database (Denmark)

    Møller, Hanne B; Slengerik-Hansen, Joachim Enevoldsen; Aroankins, Takwa

    2016-01-01

    The 14-3-3 family of proteins are multifunctional proteins that interact with many of their cellular targets in a phosphorylation-dependent manner. Here, we determined that 14-3-3 proteins interact with phosphorylated forms of the water channel aquaporin-2 (AQP2) and modulate its function...... levels. In conclusion, this study demonstrates phosphorylation-dependent interactions of AQP2 with 14-3-3 θ and ζ. These interactions play divergent roles in modulating AQP2 trafficking, phosphorylation, ubiquitylation and degradation....

  14. Reduced expression of aquaporins in human intestinal mucosa in early stage inflammatory bowel disease

    Directory of Open Access Journals (Sweden)

    Ricanek P

    2015-01-01

    Full Text Available Petr Ricanek,1,2 Lisa K Lunde,3 Stephan A Frye,1 Mari Støen,1 Ståle Nygård,4 Jens P Morth,5,6 Andreas Rydning,2 Morten H Vatn,7,8 Mahmood Amiry-Moghaddam,3 Tone Tønjum,1,9 1Department of Microbiology, Oslo University Hospital, Rikshospitalet, Oslo, 2Department of Gastroenterology, Akershus University Hospital, Lørenskog and Campus Ahus, Institute of Clinical Medicine, University of Oslo, Lørenskog, 3Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 4Bioinformatics Core Facility, Institute for Medical Informatics, Oslo University Hospital and University of Oslo, 5Centre for Molecular Medicine, Nordic EMBL Partnership, University of Oslo, 6Institute for Experimental Research, Oslo University Hospital (Ullevaal, Oslo, 7EpiGen Institute, Campus Ahus, Institute of Clinical Medicine, University of Oslo, Lørenskog, 8Section of Gastroenterology, Oslo University Hospital, Rikshospitalet, Oslo, 9Department of Microbiology, University of Oslo, Oslo, Norway Objectives: The aim of this study was to investigate the relationship between aquaporin (AQP water channel expression and the pathological features of early untreated inflammatory bowel disease (IBD in humans. Methods: Patients suspected to have IBD on the basis of predefined symptoms, including abdominal pain, diarrhea, and/or blood in stool for more than 10 days, were examined at the local hospital. Colonoscopy with biopsies was performed and blood samples were taken. Patients who did not meet the diagnostic criteria for IBD and who displayed no evidence of infection or other pathology in the gut were included as symptomatic non-IBD controls. AQP1, 3, 4, 5, 7, 8, and 9 messenger RNA (mRNA levels were quantified in biopsies from the distal ileum and colon by quantitative real-time polymerase chain reaction. Protein expression of selected AQPs was assessed by confocal microscopy. Through multiple alignments of the deduced amino acid sequences, the putative three

  15. Brain Basics

    Medline Plus

    Full Text Available ... PDF, 10 pages) Introduction Watch the Brain Basics video Welcome. Brain Basics provides information on how the brain works, how mental illnesses are disorders of the brain, and ongoing research that helps ...

  16. Brain Basics

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    Full Text Available ... Brain Research Glossary Brain Basics (PDF, 10 pages) Introduction Watch the Brain Basics video Welcome. Brain Basics ... depression experience when starting treatment. Gene Studies ... medication. This information may someday make it possible to predict who ...

  17. Brain Basics

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    Full Text Available ... Brain Research Glossary Brain Basics (PDF, 10 pages) Introduction Watch the Brain Basics video Welcome. Brain Basics ... fear hub," which activates our natural "fight-or-flight" response to confront or escape from a dangerous ...

  18. Brain Lesions

    Science.gov (United States)

    Symptoms Brain lesions By Mayo Clinic Staff A brain lesion is an abnormality seen on a brain-imaging test, such as ... tomography (CT). On CT or MRI scans, brain lesions appear as dark or light spots that don' ...

  19. Brain Basics

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    Full Text Available ... Life Brain Basics in Real Life—How Depression affects the Brain Meet Sarah Sarah is a middle- ... than ever before. Brain Imaging Using brain imaging technologies such as magnetic resonance imaging (MRI), which uses ...

  20. Identification and Expression Analysis of the Barley (Hordeum vulgare L. Aquaporin Gene Family.

    Directory of Open Access Journals (Sweden)

    Runyararo M Hove

    Full Text Available Aquaporins (AQPs are major intrinsic proteins (MIPs that mediate bidirectional flux of water and other substrates across cell membranes, and play critical roles in plant-water relations, dehydration stress responses and crop productivity. However, limited data are available as yet on the contributions of these proteins to the physiology of the major crop barley (Hordeum vulgare. The present work reports the identification and expression analysis of the barley MIP family. A comprehensive search of publicly available leaf mRNA-seq data, draft barley genome data, GenBank transcripts and sixteen new annotations together revealed that the barley MIP family is comprised of at least forty AQPs. Alternative splicing events were likely in two plasma membrane intrinsic protein (PIP AQPs. Analyses of the AQP signature sequences and specificity determining positions indicated a potential of several putative AQP isoforms to transport non-aqua substrates including physiological important substrates, and respond to abiotic stresses. Analysis of our publicly available leaf mRNA-seq data identified notable differential expression of HvPIP1;2 and HvTIP4;1 under salt stress. Analyses of other gene expression resources also confirmed isoform-specific responses in different tissues and/or in response to salinity, as well as some potentially inter-cultivar differences. The work reports systematic and comprehensive analysis of most, if not all, barley AQP genes, their sequences, expression patterns in different tissues, potential transport and stress response functions, and a strong framework for selection and/or development of stress tolerant barley varieties. In addition, the barley data would be highly valuable for genetic studies of the evolutionarily closely related wheat (Triticum aestivum L..

  1. Correlation of Aquaporin 3 Expression with the Clinicopathologic Characteristics of Non-small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Bailing LI

    2012-07-01

    Full Text Available Background and objective Lung cancer is a major health problem worldwide. The aim of this study is to investigate aquaporin 3 (AQP3 expression and its relationship with the clinicopathologic characteristics of non-small cell lung cancer (NSCLC. Methods AQP3 expression and the microvascular density (MVD of tissue samples from 180 cases with NSCLC were detected by immunohistochemistry. Results AQP3 expression was negative in 25 (13.9%, positive in 67 (37.2%, and strongly positive in 88 (48.9% of the 180 cases, which was significantly higher than that in the normal tissue (P<0.01. A significant correlation was found between AQP3 expression and MVD (P<0.01, whereas a high MVD was found among patients with strongly positive AQP3 expression. Male patients with positive or strongly positive AQP3 expression had significantly higher expression than female patients did (P=0.003. AQP3 expression was more significantly enhanced in adenocarcinoma than that in squamous cell carcinoma (P<0.001. Statistical analysis indicated that the positive rate of AQP3 expression in well-differentiated carcinoma was significantly higher than that in poorly differentiated tumors (P<0.001. Lymph node metastasis was positively correlated with high AQP3 expression (P=0.026. Conclusion AQP3 expression was closely correlated with MVD in NSCLC, whereas high MVD was frequently found in tumors with high AQP3 expression. AQP3, as a therapeutic target for inhibiting high AQP3 expression in NSCLC tissues, may weaken cancer cell proliferation, invasion, and metastasis.

  2. Layer-by-layer assembly of aquaporin Z-incorporated biomimetic membranes for water purification.

    Science.gov (United States)

    Wang, Miaoqi; Wang, Zhining; Wang, Xida; Wang, Shuzheng; Ding, Wande; Gao, Congjie

    2015-03-17

    We fabricated a biomimetic nanofiltration (NF) membrane by immobilizing an Aquaporin Z (AqpZ)-incorporated supported lipid bilayer (SLB) on a layer-by-layer (LbL) complex polyelectrolyte membrane to achieve excellent permeability and salt rejection with a high stability. The polyelectrolyte membranes were prepared by LbL assembly of poly(ethylenimine) (PEI) with positive charges and poly(sodium 4-styrenesulfonate) (PSS) with negative charges alternately on a porous hydrolyzed polyacrylonitrile (H-PAN) substrate. AqpZ-incorporated 1,2-dioleloyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dioleoyl-3-trimethylammo-nium-propane (chloride salt) (DOTAP) vesicles with positive charges were deposited on the H-PAN/PEI/PSS polyelectrolytes membrane surface. The resulting biomimetic membrane exhibited a high flux of 22 L·m(-2)·h(-1) (LMH), excellent MgCl2 rejection of ∼97% and NaCl rejection of ∼75% under an operation pressure of 0.4 MPa. Due to the attractive electrostatic interaction between SLB and the polyelectrolyte membrane, the biomimetic membrane showed satisfactory stability and durability as well as stable NF flux and rejection for at least 36 h. In addition, the AqpZ-containing biomimetic membrane was immersed in a 0.24 mM (critical micellar concentration, CMC) Triton X-100 solution for 5 min. The flux and rejection were slightly influenced by the Triton X-100 treatment. The current investigation demonstrated that the AqpZ-incorporated biomimetic membranes fabricated by the LbL method led to excellent separation performances and robust structures that withstand a high operation pressure for a relatively long time.

  3. Aquaporin 1a expression in gill, intestine and kidney of the euryhaline silver sea bream

    Directory of Open Access Journals (Sweden)

    Eddie E Deane

    2011-07-01

    Full Text Available This study aimed to investigate the effects of chronic salinity acclimation, abrupt salinity transfer and cortisol administration on aquaporin 1 (AQP1 expression in gill, intestine and kidney of silver sea bream (Sparus sarba. An AQP1a cDNA was cloned and found to share 83 – 96 % amino acid sequence identity with AQP1 genes from several fish species. Tissue distribution studies of AQP1a mRNA demonstrated that it was expressed in gill, liver, intestine, rectum, kidney, heart, urinary bladder and whole blood. Semi-quantitative RT-PCR analysis was used to measure AQP1a transcript abundance in sea bream that were acclimated to salinity conditions of 0, 6, 12, 33, 50 and 70ppt for 1 month. The abundance of gill AQP1a transcript was highest in sea bream acclimated to 0ppt whereas no differences were found among 0 – 50ppt groups. For intestine, the highest AQP1a transcript amounts were found in sea bream acclimated to 12 and 70ppt whereas the transcript abundance of kidney AQP1a was found to be unchanged amongst the different salinity groups. To investigate the effects of acute salinity alterations on AQP1a expression, sea bream were abruptly transferred from 33ppt to 6ppt. For intestine AQP1a levels were altered at different times, post transfer, but remained unchanged in gill and kidney. To study the effects of cortisol on AQP1a expression, sea bream were administered a single dose of cortisol followed by a 3 day acclimation to either 33ppt or 6ppt. The findings from this experiment demonstrated that cortisol administration resulted in alterations of AQP1a transcript in gill and intestine but not in kidney.

  4. [Effects of electroacupuncture on cochlea morphology and expression of aquaporins in guinea pigs with endolymphatic hydrops].

    Science.gov (United States)

    Jiang, Liyuan; Wang, Canjun; Ni, Fangying; Chen, Huade

    2015-06-01

    To observe the effects of electroacupuncture (EA) on cochlea morphology and expression of aquaporin 1 (AQP1) in guinea pigs with endolymphatic hydrops, so as to explore the possible mechanism of EA on endolymphatic hydrops. Forty guinea pigs were randomly divided into a blank group, a model group, a medication group and an EA group, 10 guinea pigs in each one. Model of endolymphatic hydrops was established by using intraperitoneal injection of aldosterone. Guinea pigs in the blank group and model group were treated with identical immobilization as EA group but no treatment was given; guinea pigs in the medication group were treated with intragastric administration of hydrochlorothiazide at a dose of 5 mg/kg, once a day for consecutive 10 days; guinea pigs in the EA group were treated with' EA at "Baihui" (GV 20) and "Tinggong"(SI 19), once a day for consecutive 10 days. The serum ionic concentration in each group was tested by turbidimetric method; hematoxylin-eosin staining was used to measure the severity of cochlea hydrops; immunohistochemical method was used to observe the expression of AQP1 in the cochlea. (1) There was no endolymphatic hydrops in the blank group, moderate-severe endolymphatic hydrops in the model group and slight endolymphatic hydrops in the EA group and medication group. (2) The concentration of K+ and Ca2+ in the EA group was higher than that in the model group and medication group (all P0. 05). (3) The ratio of expression area of AQP1 in the model group was lower than that in the blank group (P0. 05). EA could relieve the endolymphatic hydrops in guinea pigs; the mechanism is likely to be related with up-regulating the expression of AQP1 in cochlea and ion concentration might be an important factor involved.

  5. Artificial Induction of Native Aquaporin-1 Expression in Human Salivary Cells.

    Science.gov (United States)

    Wang, Z; Pradhan-Bhatt, S; Farach-Carson, M C; Passineau, M J

    2017-04-01

    Gene therapy for dry mouth disorders has transitioned in recent years from theoretical to clinical proof of principle with the publication of a first-in-man phase I/II dose escalation clinical trial in patients with radiation-induced xerostomia. This trial used a prototype adenoviral vector to express aquaporin-1 (AQP1), presumably in the ductal cell layer and/or in surviving acinar cells, to drive transcellular flux of interstitial fluid into the labyrinth of the salivary duct. As the development of this promising gene therapy continues, safety considerations are a high priority, particularly those that remove nonhuman agents (i.e., viral vectors and genetic sequences of bacterial origin). In this study, we applied 2 emerging technologies, artificial transcriptional complexes and epigenetic editing, to explore whether AQP1 expression could be achieved by activating the native gene locus in a human salivary ductal cell line and primary salivary human stem/progenitor cells (hS/PCs), as opposed to the conventional approach of cytomegalovirus promoter-driven expression from an episomal vector. In our first study, we used a cotransfection strategy to express the components of the dCas9-SAM system to create an artificial transcriptional complex at the AQP1 locus in A253 and hS/PCs. We found that AQP1 expression was induced at a magnitude comparable to adenoviral infection, suggesting that AQP1 is primarily silenced through pretranscriptional mechanisms. Because earlier literature suggested that pretranscriptional silencing of AQP1 in salivary glands is mediated by methylation of the promoter, in our second study, we performed global, chemical demethylation of A253 cells and found that demethylation alone induced robust AQP1 expression. These results suggest the potential for success by inducing AQP1 expression in human salivary ductal cells through epigenetic editing of the native promoter.

  6. Analysis of aquaporin 9 expression in human epidermis and cultured keratinocytes

    Science.gov (United States)

    Sugiyama, Yoshinori; Yamazaki, Kohei; Kusaka-Kikushima, Ayumi; Nakahigashi, Kyoko; Hagiwara, Hiromi; Miyachi, Yoshiki

    2014-01-01

    Aquaporin 9 (AQP9) is a member of the aquaglyceroporin family that transports glycerol, urea and other small solutes as well as water. Compared to the expression and function in epidermal keratinocytes of AQP3, another aquaglyceroporin, our knowledge of epidermal AQP9 remains elusive. In this study, we investigated the expression of AQP9 in the human epidermis and cultured keratinocytes. Immunofluorescence studies revealed that AQP9 expression is highly restricted to the stratum granulosum of the human epidermis, where occludin is also expressed at the tight junctions. Interestingly, the AQP3 staining decreased sharply below the cell layers in which AQP9 is expressed. In cultured normal human epidermal keratinocytes (NHEK), knock-down of AQP9 expression in the differentiated cells induced by RNA interference reduced glycerol uptake, which was not as pronounced as was the case with AQP3 knock-down cells. In contrast, similar reduction of urea uptake was detected in AQP9 and AQP3 knock-down cells. These findings suggested that AQP9 expression in NHEK facilitates at least the transport of glycerol and urea. Finally, we analyzed the effect of retinoic acid (RA), a potent stimulator of keratinocyte proliferation, on AQP3 and AQP9 mRNA expression in differentiated NHEK. Stimulation with RA at 1 μM for 24 h augmented AQP3 expression and down-regulated AQP9 expression. Collectively, these results indicate that AQP9 expression in epidermal keratinocytes is regulated in a different manner from that of AQP3. PMID:25161869

  7. Aquaporin 1 contributes to chondrocyte apoptosis in a rat model of osteoarthritis.

    Science.gov (United States)

    Gao, Hangfei; Gui, Jiancao; Wang, Liming; Xu, Yan; Jiang, Yiqiu; Xiong, Mingyue; Cui, Yongguang

    2016-12-01

    Aquaporins (AQPs) have been found to be associated with a number of diseases. However, the role of AQP‑1 in the pathogenesis of osteoarthritis remains unclear. We previously found that AQP‑1 expression was upregulated in osteoarthritic cartilage and strongly correlated with caspase‑3 expression and activity. The aim of this study was to further investigate the association of AQP‑1 expression with chondrocyte apoptosis in a rat model of osteoarthritis, using RNA interference to knock down AQP‑1. For this purspose, 72 male Sprague‑Dawley rats were randomly assigned to 3 groups as follows: the control group not treated surgically (n=24), the sham‑operated group (n=24), and the osteoarthritis group (n=24). Osteoarthritis was induced by amputating the anterior cruciate ligament and medial collateral ligament and partially excising the medial meniscus. Chondrocytes from the rats with osteoarthritis were isolated and cultured. shRNAs were used to knock down AQP‑1 expression in the cultured chondrocytes. The expression of AQP‑1 and caspase‑3 was determined by reverse transcription-quantitative polymerase chain reaction. Caspase‑3 activity was measured using a caspase‑3 colorimetric assay. The rats in our model of osteoarthritis exhibited severe cartilage damage. The knockdown of AQP‑1 decreased caspase‑3 expression and activity in the cultured chondrocytes. In addition, the expression of AQP‑1 positively correlated with caspase‑3 expression and activity. Thus, the findings of our study, suggest that AQP‑1 promotes caspase‑3 activation and thereby contributes to chondrocyte apoptosis and to the development of osteoarthritis.

  8. Aquaporin-2 Ser-261 phosphorylation is regulated in combination with Ser-256 and Ser-269 phosphorylation.

    Science.gov (United States)

    Yui, Naofumi; Sasaki, Sei; Uchida, Shinichi

    2017-01-22

    Aquaporin-2 (AQP2) is a water channel in collecting duct principal cells in the kidney. Vasopressin catalyzes AQP2 phosphorylation at several serine sites in its C-terminus: Ser-256, Ser-261, and Ser-269. Upon stimulation by vasopressin, Ser-269 phosphorylation increases and Ser-261 phosphorylation decreases. Ser-256 phosphorylation is relatively constant. However, whether these types of phospho-regulation occur independently in distinct AQP2 populations or sequentially in the same AQP2 population is unclear. Especially, the manner of vasopressin-mediated Ser-261 phospho-regulation has been in controversy. In this study, we established phospho-specific AQP2 immunoprecipitation assays and investigated how pS256-positive AQP2 and pS269-positive AQP2 are catalyzed by forskolin or vasopressin, focusing on their Ser-261 phosphorylation status in polarized Madin-Darby canine kidney (MDCK) cells and in mice. In forskolin-treated MDCK cells, Ser-269 phosphorylation preceded Ser-261 dephosphorylation and Ser-256 phosphorylation was constant. In both MDCK cells and mouse kidney, phospho-specific immunoprecipitation revealed that the regulated Ser-269 phosphorylation occurred in the pS256-positive AQP2 population. Importantly, basal-state Ser-261 phosphorylation and its regulated dephosphorylation occurred in the pS256- and pS269-positive AQP2 population. These results provide the direct evidence that the Ser-261 dephosphorylation is involved in the pS256- and pS269-related AQP2 regulation. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Ovine aquaporin-2: cDNA cloning, ontogeny and control of renal gene expression.

    Science.gov (United States)

    Butkus, A; Earnest, L; Jeyaseelan, K; Moritz, K; Johnston, H; Tenis, N; Wintour, E M

    1999-06-01

    The aim of this study was to test the hypothesis that the relative insensitivity of the ovine fetal kidney to arginine vasopressin (AVP) is due to low levels of expression of the gene for aquaporin-2 (AQP2) which encodes the AVP-regulated water channel. We report the cloning of the cDNA for the ovine AQP2 which has a major transcript at 4.2 kilobases (kb) and a minor transcript at 1.5 kb, resembling the human gene transcripts. At 40-60 days' (term = 145-150 days'), mRNA levels are very low, detectable only by reverse transcription-polymerase chain reaction (RT-PCR). By Northern blot analysis AQP2 mRNA is detectable at 75 days'. The ratio of AQP2/glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA increases approximately 2.4-fold between 100 and 140 days' when it is about 41% of adult values. Both glucocorticoids and the renin-angiotensin system are involved in maturation of renal function. When fetuses at 75 or 85 days of gestation were exposed to high levels of dexamethasone for 2-3 days, mRNAs for both GAPDH and AQP2 doubled, but the ratio was unchanged. Angiotensin I, infused for 3 days at 115-120 days' gestation, increased the AQP2/GAPDH mRNA ratios by twofold (major transcript) and sixfold (minor transcript), which were highly significant (P<0.001). The increasing sensitivity of the ovine fetal kidney to AVP, from 100-140 days of gestation, is largely due to increasing AQP2 gene expression over this period.

  10. Unique and analogous functions of aquaporin O for fiber cell architecture and ocular lens transparency

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, S.S.; Eswaramoorthy, S.; Mathias, R. T.; Varadaraj, K.

    2011-09-01

    Aquaporin (AQP) 1 and AQP0 water channels are expressed in lens epithelial and fiber cells, respectively, facilitating fluid circulation for nourishing the avascular lens to maintain transparency. Even though AQP0 water permeability is 40-fold less than AQP1, AQP0 is selectively expressed in the fibers. Delimited AQP0 fiber expression is attributed to a unique structural role as an adhesion protein. To validate this notion, we determined if wild type (WT) lens ultrastructure and fibercell adhesion are different in AQP0{sup -/-}, and TgAQP1{sup +/+}/AQP0{sup -/-} mice that transgenically express AQP1 (TgAQP1) in fibercells without AQP0 (AQP0{sup -/-}). In WT, lenses were transparent with 'Y' sutures. Fibers contained opposite end curvature, lateral interdigitations, hexagonal shape, and were arranged as concentric growth shells. AQP0{sup -/-}lenses were cataractous, lacked 'Y' sutures, ordered packing and well-defined lateral interdigitations. TgAQP1{sup +/+}/AQP0{sup -/-} lenses showed improvement in transparency and lateral interdigitations in the outer cortex while inner cortex and nuclear fibers were severely disintegrated. Transmission electron micrographs exhibited tightly packed fibercells in WT whereas AQP0{sup -/-} and TgAQP1{sup +/+}/AQP0{sup -/-}lenses had wide extracellular spaces. Fibers were easily separable by teasing in AQP0{sup -/-} and TgAQP1{sup +/+}/AQP0{sup -/-}lenses compared to WT. Our data suggest that the increased water permeability through AQP1 does not compensate for loss of AQP0 expression in TgAQP1{sup +/+}/AQP0{sup -/-} mice. Fibercell AQP0 expression is required to maintain their organization, which is a requisite for lenstransparency. AQP0 appears necessary for cell-to-cell adhesion and thereby to minimize light scattering since in the AQP0{sup -/-} and TgAQP1{sup +/+}/AQP0{sup -/-} lenses, fiber cell disorganization was evident.

  11. Roles of morphology, anatomy, and aquaporins in determining contrasting hydraulic behavior of roots.

    Science.gov (United States)

    Bramley, Helen; Turner, Neil C; Turner, David W; Tyerman, Stephen D

    2009-05-01

    The contrasting hydraulic properties of wheat (Triticum aestivum), narrow-leafed lupin (Lupinus angustifolius), and yellow lupin (Lupinus luteus) roots were identified by integrating measurements of water flow across different structural levels of organization with anatomy and modeling. Anatomy played a major role in root hydraulics, influencing axial conductance (L(ax)) and the distribution of water uptake along the root, with a more localized role for aquaporins (AQPs). Lupin roots had greater L(ax) than wheat roots, due to greater xylem development. L(ax) and root hydraulic conductance (L(r)) were related to each other, such that both variables increased with distance from the root tip in lupin roots. L(ax) and L(r) were constant with distance from the tip in wheat roots. Despite these contrasting behaviors, the hydraulic conductivity of root cells (Lp(c)) was similar for all species and increased from the root surface toward the endodermis. Lp(c) was largely controlled by AQPs, as demonstrated by dramatic reductions in Lp(c) by the AQP blocker mercury. Modeling the root as a series of concentric, cylindrical membranes, and the inhibition of AQP activity at the root level, indicated that water flow in lupin roots occurred primarily through the apoplast, without crossing membranes and without the involvement of AQPs. In contrast, water flow across wheat roots crossed mercury-sensitive AQPs in the endodermis, which significantly influenced L(r). This study demonstrates the importance of examining root morphology and anatomy in assessing the role of AQPs in root hydraulics.

  12. Expression and significance of aquaporin-2 in human ectocervical-vaginal epithelial cells.

    Science.gov (United States)

    Zhao, Yurong; Lai, Ailuan; Dong, Wenbing

    2014-01-01

    To observe the expression of aquaporin-2 (AQP2) in human ectocervical-vaginal epithelial cells (hECEs). The study included 75 females who underwent hysterectomy for benign pelvic lesions. They were divided into three groups according to menstrual states: 28 cases in the normal menstrual group, 24 cases in the perimenopausal group, and 23 cases in the postmenopausal group. Specimens were obtained from the posterior vaginal wall. AQP2 mRNA and protein expression were detected using quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. Estrogen (E2), follicle-stimulating hormone (FSH) and plasma osmolality were assayed by blood routine test. Linear regression analysis was used for data analysis. AQP2 mRNA and protein expression were detected in all hECE tissues. AQP2 mRNA and protein expression in the normal menstrual group were significantly higher than those in the peri- and menopausal groups (p < 0.05). AQP2 mRNA was negatively correlated with FSH level (R = -0.537, p < 0.05), age (R = -0.508, p < 0.05) and plasma osmolality (R = -0.214, p < 0.05), but positively correlated with E2 (R = 0.511, p < 0.05). AQP2 protein expression was negatively correlated with FSH (R = -0.419, p < 0.05) and age (R = -0.034, p < 0.05), but positively correlated with E2 (R = 0.367, p < 0.05). The downregulation of AQP2 might be a causative factor for decreased vaginal secretions during the menopausal period. © 2014 S. Karger AG, Basel.

  13. Aquaporin 5 polymorphisms and rate of lung function decline in chronic obstructive pulmonary disease.

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    Nadia N Hansel

    Full Text Available RATIONALE: Aquaporin-5 (AQP5 can cause mucus overproduction and lower lung function. Genetic variants in the AQP5 gene might be associated with rate of lung function decline in chronic obstructive pulmonary disease (COPD. METHODS: Five single nucleotide polymorphisms (SNPs in AQP5 were genotyped in 429 European American individuals with COPD randomly selected from the NHLBI Lung Health Study. Mean annual decline in FEV(1 % predicted, assessed over five years, was calculated as a linear regression slope, adjusting for potential covariates and stratified by smoking status. Constructs containing the wildtype allele and risk allele of the coding SNP N228K were generated using site-directed mutagenesis, and transfected into HBE-16 (human bronchial epithelial cell line. AQP5 abundance and localization were assessed by immunoblots and confocal immunofluorescence under control, shear stress and cigarette smoke extract (CSE 10% exposed conditions to test for differential expression or localization. RESULTS: Among continuous smokers, three of the five SNPs tested showed significant associations (0.02>P>0.004 with rate of lung function decline; no associations were observed among the group of intermittent or former smokers. Haplotype tests revealed multiple association signals (0.012>P>0.0008 consistent with the single-SNP results. In HBE16 cells, shear stress and CSE led to a decrease in AQP5 abundance in the wild-type, but not in the N228K AQP5 plasmid. CONCLUSIONS: Polymorphisms in AQP5 were associated with rate of lung function decline in continuous smokers with COPD. A missense mutation modulates AQP-5 expression in response to cigarette smoke extract and shear stress. These results suggest that AQP5 may be an important candidate gene for COPD.

  14. New insights of aquaporin 5 in the pathogenesis of high altitude pulmonary edema.

    Science.gov (United States)

    She, Jun; Bi, Jing; Tong, Lin; Song, Yuanlin; Bai, Chunxue

    2013-11-25

    High altitude pulmonary edema (HAPE) affects individuals and is characterized by alveolar flooding with protein-rich edema as a consequence of blood-gas barrier disruption. In this study, we hypothesized that aquaporin 5 (AQP5) which is one kind of water channels may play a role in preservation of alveolar epithelial barrier integrity in high altitude pulmonary edema (HAPE). Therefore, we established a model in Wildtype mice and AQP5 -/- mice were assingned to normoxic rest (NR), hypoxic rest (HR) and hypoxic exercise (HE) group. Mice were produced by training to walk at treadmill for exercising and chamber pressure was reduced to simulate climbing an altitude of 5000 m for 48 hours. Studies using BAL in HAPE mice to demonstrated that edema is caused leakage of albumin proteins and red cells across the alveolarcapillary barrier in the absence of any evidence of inflammation. In this study, the Lung wet/dry weight ratio and broncholalveolar lavage protein concentrations were slightly increased in HE AQP5 -/- mice compared to wildtype mice. And histologic evidence of hemorrhagic pulmonary edema was distinctly shown in HE group. The lung Evan's blue permeability of HE group was showed slightly increased compare to the wildtype groups, and HR group was showed a medium situation from normal to HAPE development compared with NR and HE group. Deletion of AQP5 slightly increased lung edema and lung injury compared to wildtype mice during HAPE development, which suggested that the AQP5 plays an important role in HAPE formation induced by high altitude simulation.

  15. Plant and animal aquaporins crosstalk: what can be revealed from distinct perspectives.

    Science.gov (United States)

    Sutka, Moira; Amodeo, Gabriela; Ozu, Marcelo

    2017-10-01

    Aquaporins (AQPs) can be revisited from a distinct and complementary perspective: the outcome from analyzing them from both plant and animal studies. (1) The approach in the study. Diversity found in both kingdoms contrasts with the limited number of crystal structures determined within each group. While the structure of almost half of mammal AQPs was resolved, only a few were resolved in plants. Strikingly, the animal structures resolved are mainly derived from the AQP2-lineage, due to their important roles in water homeostasis regulation in humans. The difference could be attributed to the approach: relevance in animal research is emphasized on pathology and in consequence drug screening that can lead to potential inhibitors, enhancers and/or regulators. By contrast, studies on plants have been mainly focused on the physiological role that AQPs play in growth, development and stress tolerance. (2) The transport capacity. Besides the well-described AQPs with high water transport capacity, large amount of evidence confirms that certain plant AQPs can carry a large list of small solutes. So far, animal AQP list is more restricted. In both kingdoms, there is a great amount of evidence on gas transport, although there is still an unsolved controversy around gas translocation as well as the role of the central pore of the tetramer. (3) More roles than expected. We found it remarkable that the view of AQPs as specific channels has evolved first toward simple transporters to molecules that can experience conformational changes triggered by biochemical and/or mechanical signals, turning them also into signaling components and/or behave as osmosensor molecules.

  16. Regulation of Aquaporin Functional Properties Mediated by the Antioxidant Effects of Natural Compounds

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    Giorgia Pellavio

    2017-12-01

    Full Text Available Some aquaporins (AQPs have been recently demonstrated to facilitate the diffusion of hydrogen peroxide (H2O2 from the producing cells to the extracellular fluid, and their reactive oxygen species scavenging properties have been defined. Nevertheless, the identification of different AQPs acting as peroxiporins, their functional role in eustress and distress, and the identification of antioxidant compounds able to regulate AQP gating, remain unsolved. This study aims to investigate, in HeLa cells: (1 the expression of different AQPs; (2 the evaluation of naringenin, quercetin, (R-aloesaponol III 8-methyl ether, marrubiin, and curcumin antioxidant profiles, via α,α-diphenyl-β-picrylhydrazyl assay; (3 the effect of the compounds on the water permeability in the presence and in the absence of oxidative stress; and (4 the effect of pre- and post-treatment with the compounds on the H2O2 content in heat-stressed cells. Results showed that HeLa cells expressed AQP1, 3, 8, and 11 proteins. The oxidative stress reduced the water transport, and both pre- and post-treatment with the natural compounds recovering the water permeability, with the exception of curcumin. Moreover, the pre- and post-treatment with all the compounds reduced the H2O2 content of heat-stressed cells. This study confirms that oxidative stress reduced water AQP-mediated permeability, reversed by some chemical antioxidant compounds. Moreover, curcumin was shown to regulate AQP gating. This suggests a novel mechanism to regulate cell signaling and survival during stress, and to manipulate key signaling pathways in cancer and degenerative diseases.

  17. Comparative expression analysis of aquaporin-5 (AQP5) in keratoconic and healthy corneas.

    Science.gov (United States)

    Garfias, Yonathan; Navas, Alejandro; Pérez-Cano, Hector J; Quevedo, Jonathan; Villalvazo, Leonardo; Zenteno, Juan Carlos

    2008-04-25

    Keratoconus (KC) is a common progressive corneal disease characterized by excessive stromal thinning, central or paracentral conical protrusion, and disruptions in Bowman's layer. The etiology of KC is largely unknown, and a combination of genetic and environmental factors is believed to play a role in the origin of the disease. Recently, the absence of transcripts of the water channel, aquaporin-5 (AQP5), was demonstrated by reverse-transcription polymerase chain reaction (RT-PCR) in KC tissues and was proposed as a possible marker for KC. In this study, we sought to evaluate AQP5 mRNA and protein expression in KC and non-KC corneal tissues using a combination of techniques. A total of 69 samples of corneal tissue were analyzed including 39 corneal buttons from patients with advanced KC, 16 samples of non-KC corneal epithelium belonging to patients who underwent surface refractive surgery, 12 sclerocorneal rims obtained from healthy donor subjects, and two healthy corneal buttons. Determination of AQP5 transcript and protein expression patterns was performed by means of real time RT-PCR, immunohistochemistry, immunocytochemistry, and flow cytometry methods. Cell culture was performed to identify AQP5 protein expression in KC epithelial cells. AQP5 mRNA was expressed with no significant differences between KC and non-KC tissues. Moreover, AQP5 protein expression analysis did not reveal differences in protein levels and/or cell location among KC and non-KC tissues. Interestingly, AQP5 expression continues for up to 21 days in the isolated KC corneal epithelial cells. Our results do not support a role for AQP5 in KC etiopathogeny or as a disease marker. Genetic background differences or a distinct pathogenetic KC cascade specific to the analyzed population could account for the dissimilarities observed in KC-related AQP5 expression.

  18. Glucocorticoids stimulate endolymphatic water reabsorption in inner ear through aquaporin 3 regulation.

    Science.gov (United States)

    Nevoux, Jérôme; Viengchareun, Say; Lema, Ingrid; Lecoq, Anne-Lise; Ferrary, Evelyne; Lombès, Marc

    2015-09-01

    Menière's disease, clinically characterized by fluctuating, recurrent, and invalidating vertigo, hearing loss, and tinnitus, is linked to an increase in endolymph volume, the so-called endolymphatic hydrops. Since dysregulation of water transport could account for the generation of this hydrops, we investigated the role of aquaporin 3 (AQP3) in water transport into endolymph, the K-rich, hyperosmotic fluid that bathes the apical ciliated membrane of sensory cells, and we studied the regulatory effect of dexamethasone upon AQP3 expression and water fluxes. The different AQP subtypes were identified in inner ear by RT-PCR. AQP3 was localized in human utricle and mouse inner ear by immunohistochemistry and confocal microscopy. Unidirectional transepithelial water fluxes were studied by means of (3)H2O transport in murine EC5v vestibular cells cultured on filters, treated or not with dexamethasone (10(-7) M). The stimulatory effect of dexamethasone upon AQP3 expression was assessed in EC5v cells and in vivo in mice. AQP3 was unambiguously detected in human utricle and was highly expressed in both endolymph secretory structures of the mouse inner ear, and EC5v cells. We demonstrated that water reabsorption, from the apical (endolymphatic) to the basolateral (perilymphatic) compartments, was stimulated by dexamethasone in EC5v cells. This was accompanied by a glucocorticoid-dependent increase in AQP3 expression at both messenger RNA (mRNA) and protein level, presumably through glucocorticoid receptor-mediated AQP3 transcriptional activation. We show that glucocorticoids enhance AQP3 expression in human inner ear and stimulate endolymphatic water reabsorption. These findings should encourage further clinical trials evaluating glucocorticoids efficacy in Menière's disease.

  19. Expression and Localization of Aquaporin Water Channels in Human Middle Ear Epithelium.

    Science.gov (United States)

    Seo, Young Joon; Choi, Jae Young

    2015-08-01

    Although aquaporins (AQPs) are known to play critical roles as the basis for water and solute transport in water homeostasis, AQPs in normal human middle ear epithelium (NHMEE) has not previously been investigated. To investigate the expressions of AQP water channels in NHMEE in situ, in proliferating epithelial cell cultures in vitro. AQP 0-12 expressions by cultured NHMEE cells in situ were assessed by reverse transcriptase-polymerase chain reaction. Normal middle ear epithelial tissue was harvested and investigated for expressions of AQPs (1, 3, 4, and 5) by immunohistochemistry. Expression screening was also carried out on the differentiated NHMEE cells. Transcripts for AQP 1, 2, 3, 4, 5, 6, 8, 10, and 11 were expressed consistently in cultured NHMEE cells; however, AQP 0, 7, 9, and 12 subtypes were not expressed. Immunochemistry confirmed the expressions of AQP 1, 3, and 5 at the protein level. AQP 1 was localized at capillary endothelial cells and fibroblasts in lamina propria mucosae; AQP 3 was present solely at the basolateral membrane of ciliated cells, whereas AQP 5 was on the apical surface of ciliated cells. AQP 3 and 5 were intensely expressed in both cultured NHMEE cells in situ and NHMEE tissue in vitro. This is the first study to demonstrate that AQPs are expressed by human middle ear epithelium in situ and in vitro, suggesting a potential role in otitis media with effusion. Our study suggests that the presence of AQP 1, 3, and 5 in the middle ear cavity may be to have an important role for water transportation.

  20. Quantitative Analysis of Aquaporin Expression Levels during the Development and Maturation of the Inner Ear.

    Science.gov (United States)

    Miyoshi, Takushi; Yamaguchi, Taro; Ogita, Kiyokazu; Tanaka, Yasuko; Ishibashi, Ken-Ichi; Ito, Hiroaki; Kobayashi, Taisuke; Nakagawa, Takayuki; Ito, Juichi; Omori, Koichi; Yamamoto, Norio

    2017-04-01

    Aquaporins (AQPs) are a family of small membrane proteins that transport water molecules across the plasma membrane along the osmotic gradient. Mammals express 13 subtypes of AQPs, including the recently reported "subcellular AQPs", AQP11 and 12. Each organ expresses specific subsets of AQP subtypes, and in the inner ear, AQPs are essential for the establishment and maintenance of two distinct fluids, endolymph and perilymph. To evaluate the contribution of AQPs during the establishment of inner ear function, we used quantitative reverse transcription polymerase chain reaction to quantify the expression levels of all known AQPs during the entire development and maturation of the inner ear. Using systematic and longitudinal quantification, we found that AQP11 was majorly and constantly expressed in the inner ear, and that the expression levels of several AQPs follow characteristic longitudinal patterns: increasing (Aqp0, 1, and 9), decreasing (Aqp6, 8, and 12), and peak of expression on E18 (Aqp2, 5, and 7). In particular, the expression level of Aqp9 increased by 70-fold during P3-P21. We also performed in situ hybridization of Aqp11, and determined the unique localization of Aqp11 in the outer hair cells. Immunohistochemistry of AQP9 revealed its localization in the supporting cells inside the organ of Corti, and in the root cells. The emergence of AQP9 expression in these cells was during P3-P21, which was coincident with the marked increase of its expression level. Combining these quantification and localization data, we discuss the possible contributions of these AQPs to inner ear function.

  1. [Expression of aquaporin 8 in human fetal membrane and placenta of idiopathic polyhydramnios].

    Science.gov (United States)

    Huang, Jin; Qi, Hong-bo

    2009-01-01

    To determine the expression of Aquaporin 8(AQP8) in the fetal membrane and placenta of idiopathic polyhydramnios. The amnion, chorion and placenta were collected from 12 term pregnancies with idiopathic polyhydramnios( polyhydramnios group) and 12 term pregnancies who were normal (control group). The expression of AQP8 mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). The expression of AQP8 protein was detected by immunohistochemistry. The expression of AQP8 mRNA in amnion, chorion and placenta of polyhydramnios group was (0.78 +/- 0.13), (0.58 +/- 0.10), and (0.86 +/- 0.15) respectively, and that of control group was (0. 39 0.07), (0.45 +/- 0.09), and (0.34 +/- 0.09) respectively. The expression of AQP8 protein in amnion, chorion and placenta of polyhydramnios group was (0.195 +/- 0.024), (0.170 +/- 0.028), and (0.193 +/- 0.024) respectively, and that of control group was (0.151 +/- 0.018), (0.156 +/- 0.024), and (0.152 +/- 0.023) respectively. In all 3 types of tissues the expression of AQP8 mRNA of polyhydramnios group was higher than that of control group (P polyhydramnios group was also increased compared to that of control group (P 0.05). The expression of AQP8 mRNA and protein is significantly increased in the amnion and placenta of polyhydramnios, suggesting that AQP8 may play an important role in the regulation of amniotic fluid volume.

  2. Steady-state levels of aquaporin 1 mRNA expression are increased in idiopathic polyhydramnios.

    Science.gov (United States)

    Mann, Stephanie E; Dvorak, Natalia; Gilbert, Heather; Taylor, Robert N

    2006-03-01

    Polyhydramnios is a condition associated with significant perinatal morbidity. While the exact pathophysiology of this condition is unknown in the absence of obvious anatomic or organic etiologies, impaired intramembranous water transport has been shown. Previous studies from our laboratory have shown that the water channel aquaporin 1 (AQP1) is expressed in human fetal membranes from term pregnancies with normal amniotic fluid (AF) volume. Therefore, we hypothesized that in pregnancies with idiopathic polyhydramnios, AQP1 expression might be reduced in fetal membranes from pregnancies with this AF volume disorder. Placentas were collected from women at term (37-40 weeks) who presented with either polyhydramnios (amniotic fluid index [AFI] >24.0 cm) or normal AF volume (AFI 5.0-23.9 cm). Immediately after delivery, the membranes (amnion and chorion) directly overlying the placenta and the free-floating reflected membranes were sampled (total of 4 samples from each placenta). RNA was isolated from each sample and expression was quantified using real-time reverse transcriptase polymerase chain reaction (PCR) and relative quantification of gene expression. Relative to pregnancies with normal AF volume, there was an increase in expression of the water channel AQP1 in all regions of the fetal membranes. The greatest increase (33-fold) was seen in the reflected amnion. AQP1 expression is increased in polyhydramnios. This finding suggests that alterations in AQP1 expression may be a compensatory response to and not a cause of idiopathic polyhydramnios. We speculate that therapies focused on regulating AQP1 expression may be useful for treating this condition.

  3. Identification and Expression Analysis of the Barley (Hordeum vulgare L.) Aquaporin Gene Family.

    Science.gov (United States)

    Hove, Runyararo M; Ziemann, Mark; Bhave, Mrinal

    2015-01-01

    Aquaporins (AQPs) are major intrinsic proteins (MIPs) that mediate bidirectional flux of water and other substrates across cell membranes, and play critical roles in plant-water relations, dehydration stress responses and crop productivity. However, limited data are available as yet on the contributions of these proteins to the physiology of the major crop barley (Hordeum vulgare). The present work reports the identification and expression analysis of the barley MIP family. A comprehensive search of publicly available leaf mRNA-seq data, draft barley genome data, GenBank transcripts and sixteen new annotations together revealed that the barley MIP family is comprised of at least forty AQPs. Alternative splicing events were likely in two plasma membrane intrinsic protein (PIP) AQPs. Analyses of the AQP signature sequences and specificity determining positions indicated a potential of several putative AQP isoforms to transport non-aqua substrates including physiological important substrates, and respond to abiotic stresses. Analysis of our publicly available leaf mRNA-seq data identified notable differential expression of HvPIP1;2 and HvTIP4;1 under salt stress. Analyses of other gene expression resources also confirmed isoform-specific responses in different tissues and/or in response to salinity, as well as some potentially inter-cultivar differences. The work reports systematic and comprehensive analysis of most, if not all, barley AQP genes, their sequences, expression patterns in different tissues, potential transport and stress response functions, and a strong framework for selection and/or development of stress tolerant barley varieties. In addition, the barley data would be highly valuable for genetic studies of the evolutionarily closely related wheat (Triticum aestivum L.).

  4. Differential expression of aquaporin 7 in adipose tissue of lean and obese high fat consumers.

    Science.gov (United States)

    Marrades, M Pilar; Milagro, Fermin I; Martínez, J Alfredo; Moreno-Aliaga, Maria J

    2006-01-20

    Aquaporin 7 (AQP7) is an aquaglyceroprotein responsible for the secretion and uptake of glycerol from the adipocyte. The modulation of the expression of this membrane transport protein might play an important role in the susceptibility to the development of obesity. The aim of the present study was to compare the AQP7 gene expression in subcutaneous abdominal fat in lean vs. obese high fat intakers with a similar daily physical activity pattern. Twelve young men, 6 lean (BMI=23.2+/-0.4kg/m(2)) and 6 obese (35.0+/-1.1kg/m(2)) with a similar habitual dietary intake of fat (45.5+/-2.5 vs. 43.5+/-1.7% daily energy from fat for lean and obese, respectively) and physical activity (16.0+/-5.7 vs. 17.2+/-5.1 METsh/week for lean and obese, respectively), were recruited. Subcutaneous abdominal fat biopsies were obtained and total RNA was extracted and purified. Pools of RNA from lean and obese individuals were probed into Affymetrix GeneChip Human U133A. The microarray analysis revealed that AQP7 gene was down-regulated in obese compared to lean subjects. The results of the microarray analysis were confirmed by real-time PCR studies. In summary, our data show that the AQP7 gene is differentially expressed in adipose tissue of lean and obese individuals. The down-regulation of the AQP7 gene could be implicated in the susceptibility to obesity by reducing glycerol release and promoting the accumulation of lipids in the adipose tissue.

  5. Intestinal fluid absorption in anadromous salmonids: importance of tight junctions and aquaporins

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    Kristina eSundell

    2012-09-01

    Full Text Available The anadromous salmonid life cycle includes both fresh water (FW and seawater (SW stages. The parr-smolt transformation (smoltification pre–adapt the fish to SW while still in FW. The osmoregulatory organs change their mode of action from a role of preventing water inflow in FW, to absorb ions to replace water lost by osmosis in SW. During smoltification, the drinking rate increases, in the intestine the ion and fluid transport increases and is further elevated after SW entry. In SW, the intestine absorbs ions to create an inwardly directed water flow which is accomplished by increased Na+,K+-ATPase (NKA activity in the basolateral membrane, driving ion absorption via ion channels and/or co-transporters. This review will aim at discussing the expression patterns of the ion transporting proteins involved in intestinal fluid absorption in the FW stage, during smoltification and after SW entry. Of equal importance for intestinal fluid absorption as the active absorption of ions, is the permeability of the epithelium to ions and water. During the smoltification the increase in NKA activity and water uptake in SW is accompanied by decreased paracellular permeability suggesting a redirection of the fluid movement from a paracellular route in FW, to a transcellular route in SW. Increased transcellular fluid absorption could be achieved by incorporation of aquaporins (AQPs into the enterocyte membranes and/or by a change in fatty acid profile of the enterocyte lipid bilayer. An increased incorporation of unsaturated fatty acids into the membrane phospholipids will increase water permeability by enhancing the fluidity of the membrane. A second aim of the present review is therefore to discuss the presence and regulation of expression of AQPs in the enterocyte membrane as well as to discuss the profile of fatty acids present in the membrane phospholipids during different stages of the salmonid lifecycle.

  6. Tolvaptan regulates aquaporin-2 and fecal water in cirrhotic rats with ascites.

    Science.gov (United States)

    Chen, Chao; Chen, Ren-Pin; Lin, Hai-Hua; Zhang, Wen-You; Huang, Xie-Lin; Huang, Zhi-Ming

    2016-03-28

    To investigate the role of tolvaptan in regulating aquaporin (AQP)-2 expression and fecal water content in cirrhotic rats with ascites. Cirrhosis with ascites was induced in rats by repetitive dorsal injection of CCl4 for 14 wk. In total, 84 cirrhotic rats with ascites divided into three groups (vehicle, 3 mg/kg and 5 mg/kg tolvaptan), and then further divided into five subgroups (days 1, 2, 3, 4, and 5). Blood samples were obtained to measure vasopressin and sodium concentrations. Rats were killed and colonic mucosa was scraped for analysis of protein expression and AQP-2 transcriptional level. The whole layer was fixed for hematoxylin&eosin (HE) staining and feces were collected for determination of fecal water content. Compared with vehicle, vasopressin decreased significantly in the tolvaptan groups from day 2 to a similar level in each treatment group. AQP-2 showed significant upregulation in cirrhotic rats with ascites compared with an untreated control group (100% ± 22.9% vs 22.2% ± 10.23%, P tolvaptan, AQP-2 expression began to decrease significantly from day 2 in each treatment group, but no significant difference was finally found between the treatment groups. Fecal water content in the distal colon was increased by 5 mg/kg tolvaptan on day 1 (66.8% ± 9.3% vs 41.4% ± 6.3%, in the vehicle group, P tolvaptan. Upregulation of AQP-2 in the distal colon is found in cirrhotic rats with ascites. Tolvaptan inhibits its expression and may decrease water reabsorption and induce diarrhea.

  7. Understanding Aquaporin Transport System in Eelgrass (Zostera marina L., an Aquatic Plant Species

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    S. M. Shivaraj

    2017-08-01

    Full Text Available Aquaporins (AQPs are a class of integral membrane proteins involved in the transport of water and many other small solutes. The AQPs have been extensively studied in many land species obtaining water and nutrients from the soil, but their distribution and evolution have never been investigated in aquatic plant species, where solute assimilation is mostly through the leaves. In this regard, identification of AQPs in the genome of Zostera marina L. (eelgrass, an aquatic ecological model species could reveal important differences underlying solute uptake between land and aquatic species. In the present study, genome-wide analysis led to the identification of 25 AQPs belonging to four subfamilies, plasma membrane intrinsic proteins (PIPs, tonoplast intrinsic proteins (TIPs, nodulin 26-like intrinsic proteins (NIPs, small basic intrinsic proteins (SIPs in eelgrass. As in other monocots, the XIP subfamily was found to be absent from the eelgrass genome. Further classification of subfamilies revealed a unique distribution pattern, namely the loss of the NIP2 (NIP-III subgroup, which is known for silicon (Si transport activity and ubiquitously present in monocot species. This finding has great importance, since the eelgrass population stability in natural niche is reported to be associated with Si concentrations in water. In addition, analysis of available RNA-seq data showed evidence of expression in 24 out of the 25 AQPs across four different tissues such as root, vegetative tissue, male flower and female flower. In contrast to land plants, higher expression of PIPs was observed in shoot compared to root tissues. This is likely explained by the unique plant architecture of eelgrass where most of the nutrients and water are absorbed by shoot rather than root tissues. Similarly, higher expression of the TIP1 and TIP5 families was observed specifically in male flowers suggesting a role in pollen maturation. This genome-wide analysis of AQP distribution

  8. A decrease in aquaporin 2 excretion is associated with bed rest induced high calciuria.

    Science.gov (United States)

    Tamma, Grazia; Di Mise, Annarita; Ranieri, Marianna; Svelto, Maria; Pisot, Rado; Bilancio, Giancarlo; Cavallo, Pierpaolo; De Santo, Natale G; Cirillo, Massimo; Valenti, Giovanna

    2014-05-19

    Exposure to microgravity or immobilization results in alterations of renal function, fluid redistribution and bone loss, which couples to a rise of urinary calcium excretion. We recently demonstrated that high calcium delivery to the collecting duct reduces local Aquaporin-2 (AQP2) mediated water reabsorption under vasopressin action, thus limiting the maximal urinary concentration and reducing calcium saturation. To investigate renal water balance adaptation during bed rest, a model to mimic the effects of microgravity on earth, the effect of changes in urinary calcium on urinary AQP2 excretion were assessed. Ten healthy men (aged 21-28 years) participated in the experiment. Study design included 7 days of adaptation and 35 days of continuous bed rest (days -6 to 0 and 1 to 35, respectively) under controlled diet. Food records and 24-hour urine samples were collected daily from day -3 to 35. Changes in blood hematocrit were used as an indirect index of plasma volume changes. AQP2 excretion was measured by ELISA. Bed rest induced bone demineralization and a transient increase in urinary calcium followed by transient decrease in AQP2 excretion, which can reduce the urine concentrating ability causing plasma volume reduction. The return of calciuria to baseline was followed by a recovery of AQP2 excretion, which allows for a partial restoration of plasma volume. These results further support the view that urinary calcium can modulate the vasopressin-dependent urine concentration through a down-regulation of AQP2 expression/trafficking. This mechanism could have a key role in the prevention of urine super-saturation due to hypercalciuria.

  9. Aquaporin-Mediated Water and Hydrogen Peroxide Transport Is Involved in Normal Human Spermatozoa Functioning

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    Umberto Laforenza

    2016-12-01

    Full Text Available Different aquaporins (AQPs are expressed in human sperm cells and with a different localization. Their function has been related to cell volume control in response to the osmotic changes encountered passing from the epididymal fluid to the cervical mucus or involved in the end stage of cytoplasm removal during sperm maturation. Recently, AQPs have also shown hydrogen peroxide (H2O2 permeability properties. Here, we investigate the expression, localization and functioning of AQPs in human sperm cells with particular attention to their role as peroxiporins in reactive oxygen species (ROS scavenging in both normospermic and sub-fertile human subjects. Western blotting and immunocytochemistry were used to confirm and clarify the AQPs expression and localization. Water and H2O2 permeability was tested by stopped flow light scattering method and by the CM-H2DCFDA (5-(and-6-chloromethyl-2′,7′-dichlorodihydro-fluorescein diacetate, acetyl ester H2O2 fluorescence probe, respectively. AQP3, -7, -8, and -11 proteins were found in human sperm cells and localized in the head (AQP7, in the middle piece (AQP8 and in the tail (AQP3 and -11 in both the plasma membrane and in intracellular structures. Sperm cells showed water and H2O2 permeability which was reversibly inhibited by H2O2, heat stress and the AQP inhibitor HgCl2. Reduced functionality was observed in patients with compromised basal semen parameters. Present findings suggest that AQPs are involved in both volume regulation and ROS elimination. The relationship between sperm number and motility and AQP functioning was also demonstrated.

  10. Expression and localization of Aquaporin 1a in the sea-bass (Dicentrarchus labrax during ontogeny

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    Ivone eGiffard-Mena

    2011-07-01

    Full Text Available The successful establishment of a species in a given habitat depends on the ability of each of its developing stages to adapt to the environment. In order to understand this process we have studied the adaptation of a euryhaline fish, the sea-bass Dicentrarchus labrax, to various salinities during its ontogeny. The expression and localization of Aquaporin 1a (AQP1a mRNA and protein were determined in different osmoregulatory tissues. In larvae, the sites of AQP1a expression are variable and they shift according to age, implying functional changes. In juveniles after metamorphosis (D32-48 post hatch, 15 - 25 mm and in pre-adults, an increase in AQP1a transcript abundance was noted in the digestive tract, and the AQP1a location was observed in the intestine. In juveniles (D87-100 post hatch, 38 - 48 mm, the transcript levels of AQP1a in the digestive tract and in the kidney were higher in sea water than at lower salinity. These observations, in agreement with existing models, suggest that in sea water-acclimated fish, the imbibed water is absorbed via AQP1a through the digestive tract, particularly the intestine and the rectum. In addition, AQP1a may play a role in water reabsorption in the kidney. These mechanisms compensate dehydratation in sea water, and they contribute to the adaptation of juveniles to salinity changes during sea-lagoon migrations. These results contribute to the interpretation of the adaptation of populations to habitats where salinity varies.

  11. Brain Basics

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    Full Text Available ... Mental Illnesses Clinical Trials Outreach Research Priorities Funding Labs at NIMH News & Events About Us Home > Health & Education > Educational Resources Brain Basics Introduction The Growing Brain The Working Brain Brain Basics in Real Life Brain Research Glossary Brain Basics (PDF, 10 pages) ...

  12. Rhubarb Tannins Extract Inhibits the Expression of Aquaporins 2 and 3 in Magnesium Sulphate-Induced Diarrhoea Model

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    Chunfang Liu

    2014-01-01

    Full Text Available Tannins, a group of major active components of Chinese rhubarb and widely distributed in nature, have a significant antidiarrhoeal activity. Aquaporins (AQPs 2 and 3 play important roles in regulating water transfer during diarrhoea. The present study aims to determine the effect of the total tannins extract of rhubarb on aquaporins (AQPs 2 and 3 in diarrhoea mice and HT-29 cells both induced by magnesium sulphate (MgSO4. Our results showed that rhubarb tannins extract (RTE significantly decreased the faecal water content in colon and evaluation index of defecation of diarrhoea mice. Interestingly, RTE could markedly reduce the mRNA and protein expression levels of AQPs 2 and 3 in apical and lateral mucosal epithelial cells in the colons of diarrhoea mice and HT-29 cells both induced by MgSO4 in a dose-dependent manner. Furthermore, RTE suppressed the production of cyclic monophosphate- (cAMP- dependent protein kinase A catalytic subunits α (PKA C-α and phosphorylated cAMP response element-binding protein (p-CREB, Ser133 in MgSO4-induced HT-29 cells. Our data showed for the first time that RTE inhibit AQPs 2 and 3 expression in vivo and in vitro via downregulating PKA/p-CREB signal pathway, which accounts for the antidiarrhoeal effect of RTE.

  13. Population Shift between the Open and Closed States Changes the Water Permeability of an Aquaporin Z Mutant

    DEFF Research Database (Denmark)

    Xin, Lin; Helix Nielsen, Claus; Su, Haibin

    2012-01-01

    Aquaporins are tetrameric transmembrane channels permeable to water and other small solutes. Wild-type (WT) and mutant Aquaporin Z (AqpZ) have been widely studied and multiple factors have been found to affect their water permeability. In this study, molecular dynamics simulations have been...... performed for the tetrameric AqpZ F43W/H174G/T183F mutant. It displayed similar to 10% average water permeability compared to WT AqpZ, which had been attributed to the increased channel lumen hydrophobicity. Our simulations, however, show a ring stacking between W43 and F183 acting as a secondary steric...... gate in the triple mutant with R189 as the primary steric gate in both mutant and WT AqpZ. The double gates (R189 and W43-F183) result in a high population of the closed conformation in the mutant. Occasionally an open state, with diffusive water permeability very close to that of WT AqpZ, was observed...

  14. Increased Permeability of the Aquaporin SoPIP2;1 by Mercury and Mutations in Loop A

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    Andreas Kirscht

    2016-08-01

    Full Text Available Aquaporins (AQPs also referred to as Major intrinsic proteins, regulate permeability of biological membranes for water and other uncharged small polar molecules. Plants encode more AQPs than other organisms and just one of the four AQP subfamilies in Arabidopsis thaliana, the water specific plasma membrane intrinsic proteins (PIPs, has 13 isoforms, the same number as the total AQPs encoded by the entire human genome. The PIPs are more conserved than other plant AQPs and here we demonstrate that a cysteine residue, in loop A of SoPIP2;1 from Spinacia oleracea, is forming disulfide bridges. This is in agreement with studies on maize PIPs, but in contrast we also show an increased permeability of mutants with a substitution at this position. In accordance with earlier findings, we confirm that mercury increase water permeability of both wild type and mutant proteins. We report on the slow kinetics and reversibility of the activation, and on quenching of intrinsic tryptophan fluorescence as a potential reporter of conformational changes associated with activation. Hence, previous studies in plants based on the assumption of mercury as a general aquaporin blocker have to be reevaluated, whereas mercury and fluorescence studies of isolated PIPs provide new means to follow structural changes dynamically.

  15. Expression of Aquaporins in Human Embryos and Potential Role of AQP3 and AQP7 in Preimplantation Mouse Embryo Development

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    Yun Xiong

    2013-05-01

    Full Text Available Background/Aims: Water channels, also named aquaporins (AQPs, play crucial roles in cellular water homeostasis. Methods: RT-PCR indicated the mRNA expression of AQPs 1-5, 7, 9, and 11-12, but not AQPs 0, 6, 8, and 10 in the 2∼8-cell stage human embryos. AQP3 and AQP7 were further analyzed for their mRNA expression and protein expression in the oocyte, zygote, 2-cell embryo, 4-cell embryo, 8-cell embryo, morula, and blastocyst from both human and mouse using RT-PCR and immunofluorescence, respectively. Results: AQP3 and AQP7 were detected in all these stages. Knockdown of either AQP3 or AQP7 by targeted siRNA injection into 2-cell mouse embryos significantly inhibited preimplantation embryo development. However, knockdown of AQP3 in JAr spheroid did not affect its attachment to Ishikawa cells. Conclusion: These data demonstrate that multiple aquaporins are expressed in the early stage human embryos and that AQP3 and AQP7 may play a role in preimplantation mouse embryo development.

  16. Hydraulic conductivity and aquaporin transcription in roots of trembling aspen (Populus tremuloides) seedlings colonized by Laccaria bicolor.

    Science.gov (United States)

    Xu, Hao; Cooke, Janice E K; Kemppainen, Minna; Pardo, Alejandro G; Zwiazek, Janusz J

    2016-07-01

    Ectomycorrhizal fungi have been reported to increase root hydraulic conductivity (L pr) by altering apoplastic and plasma membrane intrinsic protein (PIP)-mediated cell-to-cell water transport pathways in associated roots, or to have little effect on root water transport, depending on the interacting species and imposed stresses. In this study, we investigated the water transport properties and PIP transcription in roots of aspen (Populus tremuloides) seedlings colonized by the wild-type strain of Laccaria bicolor and by strains overexpressing a major fungal water-transporting aquaporin JQ585595. Inoculation of aspen seedlings with L. bicolor resulted in about 30 % colonization rate of root tips, which developed dense mantle and the Hartig net that was restricted in the modified root epidermis. Transcript abundance of the aspen aquaporins PIP1;2, PIP2;1, and PIP2;2 decreased in colonized root tips. Root colonization by JQ585595-overexpressing strains had no significant impact on seedling shoot water potentials, gas exchange, or dry mass; however, it led to further decrease in transcript abundance of PIP1;2 and PIP2;3 and the significantly lower L pr than in non-inoculated roots. These results, taken together with our previous study that showed enhanced root water hydraulics of L. bicolor-colonized white spruce (Picea glauca), suggest that the impact of L. bicolor on root hydraulics varies by the ectomycorrhiza-associated tree species.

  17. Ab initio and all-atom modeling of detergent organization around Aquaporin-0 based on SAXS data.

    Science.gov (United States)

    Koutsioubas, Alexandros; Berthaud, Alice; Mangenot, Stéphanie; Pérez, Javier

    2013-10-31

    A necessary initial step for the application of small angle X-ray scattering (SAXS) as an analytical probe for structural investigations of membrane proteins in solution is the precise knowledge of the structure of spontaneously formed detergent assemblies around the protein. Following our recent article (Berthaud et al. J. Am. Chem. Soc. 2012, 134, 10080-10088) on the study of the n-dodecyl β-D-maltopyranoside (dDM) corona surrounding Aquaporin-0 tetramers in solution, we aimed at the development of more elaborate models, exploiting the information content of the scattering data. Two additional approaches are developed here for the fit of SAXS experimental data, one based on a generalized ab initio algorithm for the construction of a coarse-grained representation of the detergent assemblies, and a second based on atomistic molecular dynamics. Accordingly, we are able to fit the SAXS experimental data and obtain a better insight concerning the structure of the detergent corona around the hydrophobic part of the Aquaporin-0 surface. The present analysis scheme represents an additional step toward future conformational studies of transmembrane proteins in solution.

  18. Boron toxicity tolerance in barley through reduced expression of the multifunctional aquaporin HvNIP2;1.

    Science.gov (United States)

    Schnurbusch, Thorsten; Hayes, Julie; Hrmova, Maria; Baumann, Ute; Ramesh, Sunita A; Tyerman, Stephen D; Langridge, Peter; Sutton, Tim

    2010-08-01

    Boron (B) toxicity is a significant limitation to cereal crop production in a number of regions worldwide. Here we describe the cloning of a gene from barley (Hordeum vulgare), underlying the chromosome 6H B toxicity tolerance quantitative trait locus. It is the second B toxicity tolerance gene identified in barley. Previously, we identified the gene Bot1 that functions as an efflux transporter in B toxicity-tolerant barley to move B out of the plant. The gene identified in this work encodes HvNIP2;1, an aquaporin from the nodulin-26-like intrinsic protein (NIP) subfamily that was recently described as a silicon influx transporter in barley and rice (Oryza sativa). Here we show that a rice mutant for this gene also shows reduced B accumulation in leaf blades compared to wild type and that the mutant protein alters growth of yeast (Saccharomyces cerevisiae) under high B. HvNIP2;1 facilitates significant transport of B when expressed in Xenopus oocytes compared to controls and to another NIP (NOD26), and also in yeast plasma membranes that appear to have relatively high B permeability. We propose that tolerance to high soil B is mediated by reduced expression of HvNIP2;1 to limit B uptake, as well as by increased expression of Bot1 to remove B from roots and sensitive tissues. Together with Bot1, the multifunctional aquaporin HvNIP2;1 is an important determinant of B toxicity tolerance in barley.

  19. Regulation of Arabidopsis Leaf Hydraulics Involves Light-Dependent Phosphorylation of Aquaporins in Veins[C][W

    Science.gov (United States)

    Prado, Karine; Boursiac, Yann; Tournaire-Roux, Colette; Monneuse, Jean-Marc; Postaire, Olivier; Da Ines, Olivier; Schäffner, Anton R.; Hem, Sonia; Santoni, Véronique; Maurel, Christophe

    2013-01-01

    The water status of plant leaves depends on the efficiency of the water supply, from the vasculature to inner tissues. This process is under hormonal and environmental regulation and involves aquaporin water channels. In Arabidopsis thaliana, the rosette hydraulic conductivity (Kros) is higher in darkness than it is during the day. Knockout plants showed that three plasma membrane intrinsic proteins (PIPs) sharing expression in veins (PIP1;2, PIP2;1, and PIP2;6) contribute to rosette water transport, and PIP2;1 can fully account for Kros responsiveness to darkness. Directed expression of PIP2;1 in veins of a pip2;1 mutant was sufficient to restore Kros. In addition, a positive correlation, in both wild-type and PIP2;1-overexpressing plants, was found between Kros and the osmotic water permeability of protoplasts from the veins but not from the mesophyll. Thus, living cells in veins form a major hydraulic resistance in leaves. Quantitative proteomic analyses showed that light-dependent regulation of Kros is linked to diphosphorylation of PIP2;1 at Ser-280 and Ser-283. Expression in pip2;1 of phosphomimetic and phosphorylation-deficient forms of PIP2;1 demonstrated that phosphorylation at these two sites is necessary for Kros enhancement under darkness. These findings establish how regulation of a single aquaporin isoform in leaf veins critically determines leaf hydraulics. PMID:23532070

  20. Human Aquaporin 4 Gating Dynamics under Perpendicularly-Oriented Electric-Field Impulses: A Molecular Dynamics Study

    Directory of Open Access Journals (Sweden)

    Paolo Marracino

    2016-07-01

    Full Text Available Human aquaporin 4 has been studied using molecular dynamics (MD simulations in the absence and presence of pulses of external static electric fields. The pulses were 10 ns in duration and 0.012–0.065 V/Å in intensity acting along both directions perpendicular to the pores. Water permeability and the dipolar response of all residues of interest (including the selectivity filter within the pores have been studied. Results showed decreased levels of water osmotic permeability within aquaporin channels during orthogonally-oriented field impulses, although care must be taken with regard to statistical certainty. This can be explained observing enhanced “dipolar flipping” of certain key residues, especially serine 211, histidine 201, arginine 216, histidine 95 and cysteine 178. These residues are placed at the extracellular end of the pore (serine 211, histidine 201, and arginine 216 and at the cytoplasm end (histidine 95 and cysteine 178, with the key role in gating mechanism, hence influencing water permeability.

  1. Differential down-regulation of aquaporin-2 in rat kidney zones by peripheral nociceptin/orphanin FQ receptor agonism and vasopressin type-2 receptor antagonism

    DEFF Research Database (Denmark)

    Hadrup, Niels; Petersen, Jørgen S; Windfeld, Søren

    2007-01-01

    We previously showed that aquaresis induced by the peripherally acting nociceptin/orphanin FQ receptor agonist ZP120 is associated with a decreased protein level of aquaporin-2 (AQP2) in whole-kidney homogenates. We now examined the effects of Ac-RYYRWKKKKKKK-NH(2) (ZP120) (1 nmol/kg/min i.v. for...

  2. A novel mechanism in recessive nephrogenic diabetes insipidus: wild-type aquaporin-2 rescues the apical membrane expression of intracellularly retained AQP2-P262L.

    NARCIS (Netherlands)

    Mattia, F.P. de; Savelkoul, P.J.M.; Bichet, D.G.; Kamsteeg, E.J.; Konings, I.B.M.; Marr, N.; Arthus, M.F.; Lonergan, M.; Os, C.H. van; Sluijs, P. van der; Robertson, G.; Deen, P.M.T.

    2004-01-01

    Vasopressin regulates water homeostasis through insertion of homotetrameric aquaporin-2 (AQP2) water channels in the apical plasma membrane of renal cells. AQP2 mutations cause recessive and dominant nephrogenic diabetes insipidus (NDI), a disease in which the kidney is unable to concentrate urine

  3. Lack of arginine vasopressin-induced phosphorylation of aquaporin-2 mutant AQP2-R254L explains dominant nephrogenic diabetes insipidus.

    NARCIS (Netherlands)

    Mattia, F.P. de; Savelkoul, P.J.M.; Kamsteeg, E.J.; Konings, I.B.M.; Sluijs, P. van der; Mallmann, R.; Oksche, A.; Deen, P.M.T.

    2005-01-01

    Water homeostasis in humans is regulated by vasopressin, which induces the translocation of homotetrameric aquaporin-2 (AQP2) water channels from intracellular vesicles to the apical membrane of renal principal cells. For this process, phosphorylation of AQP2 at S256 by cAMP-dependent protein kinase

  4. Overexpression of angiotensinogen downregulates aquaporin 1 expression via modulation of Nrf2–HO-1 pathway in renal proximal tubular cells of transgenic mice

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    Shiao-Ying Chang

    2016-09-01

    Full Text Available Introduction: We aimed to examine the regulation of aquaporin 1 expression in an angiotensinogen transgenic mouse model, focusing on underlying mechanisms. Methods: Male transgenic mice overexpressing rat angiotensinogen in their renal proximal tubular cells (RPTCs and rat immortalised RPTCs stably transfected with rat angiotensinogen cDNA were used. Results: Angiotensinogen-transgenic mice developed hypertension and nephropathy, changes that were either partially or completely attenuated by treatment with losartan or dual renin–angiotensin system blockade (losartan and perindopril, respectively, while hydralazine prevented hypertension but not nephropathy. Decreased expression of aquaporin 1 and heme oxygenase-1 and increased expression of nuclear factor erythroid 2-related factor 2 (Nrf2 and sodium–hydrogen exchanger 3 were observed in RPTCs of angiotensinogen-transgenic mice and in angiotensinogen-transfected immortalised RPTCs. These parameters were normalised by dual renin–angiotensin system blockade. Both in vivo and in vitro studies identified a novel mechanism in which angiotensinogen overexpression in RPTCs enhances the cytosolic accumulation of Nrf2 via the phosphorylation of pGSK3β Y216. Consequently, lower intranuclear Nrf2 levels are less efficient to trigger heme oxygenase-1 expression as a defence mechanism, which subsequently diminishes aquaporin 1 expression in RPTCs. Conclusions: Angiotensinogen-mediated downregulation of aquaporin 1 and Nrf2 signalling may play an important role in intrarenal renin–angiotensin system-induced hypertension and kidney injury.

  5. Opposing effects of cAMP and T259 phosphorylation on plasma membrane diffusion of the water channel aquaporin-5 in Madin-Darby canine kidney cells

    DEFF Research Database (Denmark)

    Koffman, Jennifer Skaarup; Christensen, Eva Arnspang; Marlar, Saw

    2015-01-01

    Aquaporin-5 (AQP5) facilitates passive water transport in glandular epithelia in response to secretory stimuli via intracellular pathways involving calcium release, cAMP and protein kinase A (PKA). In epithelial plasma membranes, AQP5 may be acutely regulated to facilitate water transport in resp...

  6. Thiazide-induced hyponatraemia is associated with increased water intake and impaired urea-mediated water excretion at low plasma antidiuretic hormone and urine aquaporin-2

    NARCIS (Netherlands)

    Frenkel, Nanne J.; Vogt, Liffert; de Rooij, Sophia E.; Trimpert, Christiane; Levi, Marcel M.; Deen, Peter M. T.; van den Born, Bert-Jan H.

    2015-01-01

    Hyponatraemia is a common, potentially life-threatening, complication of thiazide diuretics. The mechanism of thiazide-induced hyponatraemia is incompletely understood. Previous experiments have suggested a direct effect of thiazide diuretics on the plasma membrane expression of aquaporin (AQP)2. We

  7. Cold induced changes in the water balance affect immunocytolocalization pattern of one of the aquaporins in the vascular system in the leaves of maize (Zea mays L.).

    Science.gov (United States)

    Bilska-Kos, Anna; Szczepanik, Jarosław; Sowiński, Paweł

    2016-10-20

    Chilling stress is known to affect the water balance in plants, which often manifests itself in the decrease of the water potential in different organs. Relationships between chilling, assimilate transport and water balance are far from being understood. Although aquaporins play a key role in regulating water balance in plants, especially under stress conditions, the role of individual aquaporins in stress response remains unclear. In this report we show the specific localization within plasma membranes of one of the aquaporins (PIP2;3) in the leaves of two maize inbred lines differing in their chilling-sensitivity. This form of aquaporin has been also observed in thick-walled sieve elements - an additional type of sieve tubes of unclear function found only in monocotyledons. Moderate chilling (about 15°C) caused significant reduction of labelling in these cells accompanied by a steep decrease in the water potential in leaves of chilling-sensitive maize line. Our results suggest that both PIP2;3 and thick-walled sieve tubes may be an unknown element of the mechanism of the response of maize to cold stress. Copyright © 2016 Elsevier GmbH. All rights reserved.

  8. Assignment of the human gene for the water channel of renal collecting duct Aquaporin 2 (AQP2) to chromosome 12 region q12-->q13

    NARCIS (Netherlands)

    Deen, P M; Weghuis, D O; Sinke, R J; Geurts van Kessel, A; Wieringa, B; van Os, C H

    1994-01-01

    The chromosomal localization of the gene encoding Aquaporin 2 (previously called WCH-CD), which acts as a water channel in the collecting tubules of the kidney, was determined. Southern blot hybridizations of chromosomal DNA from a panel of 25 different human-rodent hybrid cell lines assigned AQP2

  9. Changes in Air CO2 Concentration Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves

    Directory of Open Access Journals (Sweden)

    Francesca Secchi

    2016-04-01

    Full Text Available The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling gas exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1 and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1 gene expression varies in tobacco leaves subjected to treatments with different CO2 concentrations (ranging from 0 to 800 ppm, inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in air CO2 concentration ([CO2] affected net photosynthesis (Pn and leaf substomatal [CO2] (Ci. Pn was slightly negative at 0 ppm air CO2; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO2] showed one-third reduced stomatal conductance (gs and transpiration (E, and their gs was in turn slightly lower than in 200 ppm– and in 0 ppm–treated leaves. The 800 ppm air [CO2] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm air [CO2], a concentration below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO2 transport, positively responds to CO2 scarcity in the air in the whole range 0–800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO2 transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure.

  10. Changes in Air CO2 Concentration Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves

    Science.gov (United States)

    Secchi, Francesca; Schubert, Andrea; Lovisolo, Claudio

    2016-01-01

    The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling gas exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1) and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1) gene expression varies in tobacco leaves subjected to treatments with different CO2 concentrations (ranging from 0 to 800 ppm), inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in air CO2 concentration ([CO2]) affected net photosynthesis (Pn) and leaf substomatal [CO2] (Ci). Pn was slightly negative at 0 ppm air CO2; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO2] showed one-third reduced stomatal conductance (gs) and transpiration (E), and their gs was in turn slightly lower than in 200 ppm– and in 0 ppm–treated leaves. The 800 ppm air [CO2] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm air [CO2], a concentration below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO2 transport, positively responds to CO2 scarcity in the air in the whole range 0–800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO2 transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure. PMID:27089333

  11. Characterization of four plasma membrane aquaporins in tulip petals: a putative homolog is regulated by phosphorylation.

    Science.gov (United States)

    Azad, Abul Kalam; Katsuhara, Maki; Sawa, Yoshihiro; Ishikawa, Takahiro; Shibata, Hitoshi

    2008-08-01

    We suggested previously that temperature-dependent tulip (Tulipa gesneriana) petal movement that is concomitant with water transport is regulated by reversible phosphorylation of an unidentified plasma membrane intrinsic protein (PIP). In this study, four full-length cDNAs of PIPs from tulip petals were identified and cloned. Two PIPs, namely TgPIP1;1 and TgPIP1;2, are members of the PIP1 subfamily, and the remaining two PIPs, namely TgPIP2;1 and TgPIP2;2, belong to the PIP2 subfamily of aquaporins and were named according to the nomenclature of PIP genes in plants. Of these four homologs, only TgPIP2;2 displayed significant water channel activity in the heterologous expression assay using Xenopus laevis oocytes. The water channel activity of this functional isoform was abolished by mercury and was affected by inhibitors of protein kinase and protein phosphatase. Using a site-directed mutagenesis approach to substitute several serine residues with alanine, and assessing water channel activity using the methylotrophic yeast Pichia pastoris expression assay, we showed that Ser35, Ser116 and Ser274 are the putative phosphorylation sites of TgPIP2;2. Real-time reverse transcription-PCR analysis revealed that the transcript levels of TgPIP1;1 and TgPIP1;2 in tulip petals, stems, leaves, bulbs and roots are very low when compared with those of TgPIP2;1 and TgPIP2;2. The transcript level of TgPIP2;1 is negligible in roots, and TgPIP2;2 is ubiquitously expressed in all organs with significant transcript levels. From the data reported herein, we suggest that TgPIP2;2 might be modulated by phosphorylation and dephosphorylation for regulating water channel activity, and may play a role in transcellular water transport in all tulip organs.

  12. Genome-Wide Analysis of the Aquaporin Gene Family in chickpea (Cicer arietinum L.

    Directory of Open Access Journals (Sweden)

    Amit Deokar

    2016-11-01

    Full Text Available Aquaporins (AQPs are essential membrane proteins that play critical role in the transport of water and many other solutes across cell membranes. In this study, a comprehensive genome-wide analysis identified 40 AQP genes in chickpea (Cicer arietinum L.. A complete overview of the chickpea AQP (CaAQP gene family is presented, including their chromosomal locations, gene structure, phylogeny, gene duplication, conserved functional motifs, gene expression, and conserved promoter motifs. To understand AQP's evolution, a comparative analysis of chickpea AQPs with AQP orthologs from soybean, Medicago, common bean and Arabidopsis was performed. The chickpea AQP genes were found on all of the chickpea chromosomes, except chromosome 7, with a maximum of six genes on chromosome 6 and a minimum of one gene on chromosome 5. Gene duplication analysis indicated that the expansion of chickpea AQP gene family might have been due to segmental and tandem duplications. CaAQPs were grouped into four subfamilies including 15 NOD26-like intrinsic proteins (NIPs, 13 tonoplast intrinsic proteins (TIPs, eight plasma membrane intrinsic proteins (PIPs and four small basic intrinsic proteins (SIPs based on sequence similarities and phylogenetic position. Gene structure analysis revealed a highly conserved exon-intron pattern within CaAQP subfamilies supporting the CaAQP family classification. Functional prediction based on conserved Ar/R selectivity filters, Froger's residues and specificity-determining positions suggested wide differences in substrate specificity among the subfamilies of CaAQPs. Expression analysis of the AQP genes indicated that some of the genes are tissue-specific, whereas few other AQP genes showed differential expression in response to biotic and abiotic stresses. Promoter profiling of CaAQP genes for conserved cis-acting regulatory elements revealed enrichment of cis-elements involved in circadian control, light response, defense and stress

  13. Molecular and cellular regulation of water homeostasis in anuran amphibians by aquaporins.

    Science.gov (United States)

    Suzuki, Masakazu; Tanaka, Shigeyasu

    2009-07-01

    Aquaporins (AQPs) are water channel proteins important for transcellular water transport. Anuran AQP family consists of at least AQP0-AQP5, AQP7-AQP10, and two anuran-specific types, designated as AQPa1 and AQPa2. In Hyla japonica, AQP2 (AQP-h2K) and two forms of AQPa2 (AQP-h2 and AQP-h3) reside in the tight-junctioned epithelial cells of three major osmoregulatory organs, i.e. AQP-h2K in the kidney, AQP-h2 in the urinary bladder, and both AQP-h2 and AQP-h3 in the ventral pelvic skin. They show translocation from the cytoplasmic pool to the apical plasma membrane in response to arginine vasotocin (AVT), thereby regulating water transport across the apical membrane. Tissue distribution of AQPa2 in five anuran species, from aquatic to arboreal habitats, suggests that AQP-h2 is a urinary bladder-type AQP, while AQP-h3 is a ventral pelvic skin-type AQP. Further, AQP-h2K seems to be specific to the kidney. On the other hand, Hyla AQP3 (AQPh3BL)is located in the basolateral plasma membrane of the tight epithelial cells, irrespective of AVT stimulation. These findings suggest that anuran AVT-dependent osmoregulatory organs utilize AQP3 at