Unexpected role of the copper transporter ATP7A in PDGF-induced vascular smooth

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Ashino, T.; Varadarajan, S.; Urao, N.; Oshikawa, J.; Chen, G. -F.; Wang, H.; Huo, Y.; Finney, L.; Vogt, S.; McKinney, R. D.; Maryon, E. B.; Kaplan, J. H.; Ushio-Fukai, M.; Fukai, T. (Biosciences Division); ( XSD); ( PSC-USR); (Univ. of Illinois at Chicago); (Univ. of Minnesota)

2010-09-09

Copper, an essential nutrient, has been implicated in vascular remodeling and atherosclerosis with unknown mechanism. Bioavailability of intracellular copper is regulated not only by the copper importer CTR1 (copper transporter 1) but also by the copper exporter ATP7A (Menkes ATPase), whose function is achieved through copper-dependent translocation from trans-Golgi network (TGN). Platelet-derived growth factor (PDGF) promotes vascular smooth muscle cell (VSMC) migration, a key component of neointimal formation. To determine the role of copper transporter ATP7A in PDGF-induced VSMC migration. Depletion of ATP7A inhibited VSMC migration in response to PDGF or wound scratch in a CTR1/copper-dependent manner. PDGF stimulation promoted ATP7A translocation from the TGN to lipid rafts, which localized at the leading edge, where it colocalized with PDGF receptor and Rac1, in migrating VSMCs. Mechanistically, ATP7A small interfering RNA or CTR small interfering RNA prevented PDGF-induced Rac1 translocation to the leading edge, thereby inhibiting lamellipodia formation. In addition, ATP7A depletion prevented a PDGF-induced decrease in copper level and secretory copper enzyme precursor prolysyl oxidase (Pro-LOX) in lipid raft fraction, as well as PDGF-induced increase in LOX activity. In vivo, ATP7A expression was markedly increased and copper accumulation was observed by synchrotron-based x-ray fluorescence microscopy at neointimal VSMCs in wire injury model. These findings suggest that ATP7A plays an important role in copper-dependent PDGF-stimulated VSMC migration via recruiting Rac1 to lipid rafts at the leading edge, as well as regulating LOX activity. This may contribute to neointimal formation after vascular injury. Our findings provide insight into ATP7A as a novel therapeutic target for vascular remodeling and atherosclerosis.

Synergistic augmentation of ATP-induced interleukin-6 production by arsenite in HaCaT cells.

Science.gov (United States)

Sumi, Daigo; Asao, Masashi; Okada, Hideta; Yogi, Kuniko; Miyataka, Hideki; Himeno, Seiichiro

2016-06-01

Chronic arsenic exposure causes cutaneous diseases such as hyperkeratosis and skin cancer. However, little information has been available regarding the molecular mechanisms underlying these symptoms. Because extracellular ATP and interleukin-6 (IL-6) are involved in pathological aspects of cutaneous diseases, we examined whether sodium arsenite (As(III)) affects ATP-induced IL-6 production in human epidermal keratinocyte HaCaT cells. The results showed that the addition of As(III) into the medium of HaCaT cells dose dependently increased the production of IL-6 induced by extracellular ATP, although As(III) alone had no effect on IL-6 production. To elucidate the mechanism of the synergistic effect of As(III) on IL-6 production by extracellular ATP, we next examined the phosphorylation of p38, ERK and epidermal growth factor receptor (EGFR), since we found that these signaling molecules were stimulated by exposure to extracellular ATP. The results indicated that ATP-induced phosphorylation of p38, ERK and EGFR was synergistically enhanced by co-exposure to As(III). To clarify the mechanisms underlying the enhanced phosphorylation of p38, ERK and EGFR by As(III), we explored two possible mechanisms: the inhibition of extracellular ATP degradation and the inhibition of protein tyrosine phosphatases (PTPs) activity by As(III). The degradation of extracellular ATP was not changed by As(III), whereas the activity of PTPs was significantly inhibited by As(III). Our results suggest that As(III) augments ATP-induced IL-6 production in HaCaT cells through enhanced phosphorylation of the EGFR and p38/ERK pathways, which is associated with the inhibition of PTPs activity.

Ca2+ Entry is Required for Mechanical Stimulation-induced ATP Release from Astrocyte

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Lee, Jaekwang; Chun, Ye-Eun; Han, Kyung-Seok; Lee, Jungmoo; Woo, Dong Ho

2015-01-01

Astrocytes and neurons are inseparable partners in the brain. Neurotransmitters released from neurons activate corresponding G protein-coupled receptors (GPCR) expressed in astrocytes, resulting in release of gliotransmitters such as glutamate, D-serine, and ATP. These gliotransmitters in turn influence neuronal excitability and synaptic activities. Among these gliotransmitters, ATP regulates the level of network excitability and is critically involved in sleep homeostasis and astrocytic Ca2+ oscillations. ATP is known to be released from astrocytes by Ca2+-dependent manner. However, the precise source of Ca2+, whether it is Ca2+ entry from outside of cell or from the intracellular store, is still not clear yet. Here, we performed sniffer patch to detect ATP release from astrocyte by using various stimulation. We found that ATP was not released from astrocyte when Ca2+ was released from intracellular stores by activation of Gαq-coupled GPCR including PAR1, P2YR, and B2R. More importantly, mechanical stimulation (MS)-induced ATP release from astrocyte was eliminated when external Ca2+ was omitted. Our results suggest that Ca2+ entry, but not release from intracellular Ca2+ store, is critical for MS-induced ATP release from astrocyte. PMID:25792866

Oxygen sensing and conducted vasomotor responses in mouse cremaster arterioles in situ

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Ngo, Thuc Anh; Jensen, Lars Jørn; Riemann, Mads Achen

2010-01-01

.0 +/- 4.9 mum) when changing from high (PO(2) = 242.5 +/- 13.3 mm Hg) to low (PO(2) = 22.5 +/- 4.8 mm Hg) oxygen tension as seen in the intact cremaster circulation (DeltaD = 18.7 +/- 1.0 mum). Blockade of NO synthases by L: -NAME and adenosine receptors by DPCPX had no effects on vasomotor responses...... to low or high oxygen. Induction of localized low (PO(2) = 23.3 +/- 5.7 mmHg) or high (PO(2) = 300.0 +/- 25.7 mm Hg) oxygen tension caused vasodilatation or -constriction locally and at a site 1,000 mum upstream (distantly). Glibenclamide blocker of ATP-sensitive K(+) channels inhibited vasodilatation...... and -constriction to low (PO(2) = 16.0 +/- 6.4 mm Hg) and high (PO(2) = 337.4 +/- 12.8 mm Hg) oxygen tension. 1) ATP-sensitive K(+) channels seem to mediate, at least in part, vasodilatation and vasoconstriction to low and high oxygen tension; 2) Red blood cells are not necessary for inducing vasodilatation...

Age-associated impairments in contraction-induced rapid-onset vasodilatation within the forearm are independent of mechanical factors.

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Hughes, William E; Kruse, Nicholas T; Casey, Darren P

2018-05-01

What is the central question of this study? We examined whether the mechanical contribution to contraction-induced rapid-onset vasodilatation (ROV) differed with age and whether ROV is associated with peripheral artery stiffness. Furthermore, we examined how manipulation of perfusion pressure modulates ROV in young and older adults. What is the main finding and its importance? The mechanical contribution to ROV is similar in young and older adults. Conversely, peripheral arterial stiffness is not associated with ROV. Enhancing perfusion pressure augments ROV to a similar extent in young and older adults. These results suggest that age-related attenuations in ROV are not attributable to a mechanical component and that ROV responses are independent of peripheral artery stiffness. Contraction-induced rapid-onset vasodilatation (ROV) is modulated by perfusion and transmural pressure in young adults; however, this effect remains unknown in older adults. The present study examined the mechanical contribution to ROV in young versus older adults, the influence of perfusion pressure and whether these responses are associated with arterial stiffness. Forearm vascular conductance (in millilitres per minute per 100 mmHg) was measured in 12 healthy young (24 ± 4 years old) and 12 older (67 ± 3 years old) adults during: (i) single dynamic contractions at 20% of maximal voluntary contraction; and (ii) single external mechanical compression of the forearm (200 mmHg) positioned above, at and below heart level. Carotid-radial pulse-wave velocity characterized upper limb arterial stiffness. Total ROV responses to single muscle contractions and single external mechanical compressions were attenuated in older adults at heart level (P mechanical contribution to contraction-induced peak (46 ± 14 versus 40 ± 18%; P = 0.21) and total (37 ± 21 versus 32 ± 18%; P = 0.27) responses were not different between young and older adults. Reducing or enhancing perfusion

CO2-Induced ATP-Dependent Release of Acetylcholine on the Ventral Surface of the Medulla Oblongata.

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Huckstepp, Robert T R; Llaudet, Enrique; Gourine, Alexander V

2016-01-01

Complex mechanisms that detect changes in brainstem parenchymal PCO2/[H+] and trigger adaptive changes in lung ventilation are responsible for central respiratory CO2 chemosensitivity. Previous studies of chemosensory signalling pathways suggest that at the level of the ventral surface of the medulla oblongata (VMS), CO2-induced changes in ventilation are (at least in part) mediated by the release and actions of ATP and/or acetylcholine (ACh). Here we performed simultaneous real-time biosensor recordings of CO2-induced ATP and ACh release from the VMS in vivo and in vitro, to test the hypothesis that central respiratory CO2 chemosensory transduction involves simultaneous recruitment of purinergic and cholinergic signalling pathways. In anaesthetised and artificially ventilated rats, an increase in inspired CO2 triggered ACh release on the VMS with a peak amplitude of ~5 μM. Release of ACh was only detected after the onset of CO2-induced activation of the respiratory activity and was markedly reduced (by ~70%) by ATP receptor blockade. In horizontal slices of the VMS, CO2-induced release of ATP was reliably detected, whereas CO2 or bath application of ATP (100 μM) failed to trigger release of ACh. These results suggest that during hypercapnia locally produced ATP induces or potentiates the release of ACh (likely from the medullary projections of distal groups of cholinergic neurones), which may also contribute to the development and/or maintenance of the ventilatory response to CO2.

Chronic hypoxia increases arterial blood pressure and reduces adenosine and ATP induced vasodilatation in skeletal muscle in healthy humans

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Calbet, J A L; Boushel, Robert Christopher; Robach, P

2014-01-01

into the femoral artery at sea level and then after 8-12 days of residence at 4559 m above sea level. At sea level, the infusions were carried out while the subjects breathed room air, acute hypoxia (FI O2 = 0.11) and hyperoxia (FI O2 = 1); and at altitude (FI O2 = 0.21 and 1). Skeletal muscle P2Y2 receptor...... protein expression was determined in muscle biopsies after 4 weeks at 3454 m by Western blot. RESULTS: At altitude, mean arterial blood pressure was 13% higher (91 ± 2 vs. 102 ± 3 mmHg, P sea level and was unaltered by hyperoxic breathing. Baseline leg vascular conductance was 25% lower...... at altitude than at sea level (P sea level by 24 and 38%, during the low and high ATP doses...

The relationship of vascular endothelial marker and endothelium-dependent vasodilatation in patients with essential hypertension

International Nuclear Information System (INIS)

Chen Yongjian; Zhou Yonglie; Hu Qingfeng; Qiu Liannv

2009-01-01

Objective: To explore the relationship of vascular endothelial marker and endothelium-dependent vasodilatation in patients with essential hypertension (EH). Methods: Plasma endothlium (ET-1) (with RIA) and von Willber factor (vWF)(with ELISA) levels were measured both before and after 12 wks' treatment in 56 patients with essential hypertension and 32 controls. The brachial artery endothelium-dependent vasodilatation function was examined with high resolving color doppler ultra-sonography. The 56 patients with EH were of two groups A. high and very high risk, n=26 B. low and moderate risk, n=30. Results: Plasma levels of ET-1, vWF in patients with EH as a whole were significantly higher than those in controls group [(53.3±16.2)pg/ml vs(42.5±8.5)pg/ml, (158.2±28.6)% vs(130.6±35.2)%], endothelium-dependent vasodilatation function wasmuch reduced in patients with EH(7.5±4.2)% vs controls(12.3±4.3)%. Among the patients, values in Group A were significantly different from those in Group B. After treatment for 12 weeks, plasma ET-1 and vWF and endothelium-dependent vasodilatation function were significantly improved. There was negative correlation between vascular endothelial marker levels and endothelium-dependent vasodilatation function. Conclusion: The endothelium-dependent vasodilatation function was impaired and plasma ET-1 and vWF levels were increased in patients with EH, the endothelial dysfunction was closely associated with the risk level of EH. Vascular endothelial markers were useful indicators for evaluation of the endothelium-dependent vasodilatation function. (authors)

Vildagliptin Improves Endothelium-Dependent Vasodilatation in Type 2 Diabetes

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van Poppel, Pleun C.M.; Netea, Mihai G.; Smits, Paul; Tack, Cees J.

2011-01-01

OBJECTIVE To investigate whether the dipeptidyl peptidase-4 inhibitor vildagliptin improves endothelium-dependent vasodilatation in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS Sixteen subjects with type 2 diabetes (age 59.8 ± 6.8 years, BMI 29.1 ± 4.8 kg/m2, HbA1c 6.97 ± 0.61) on oral blood glucose–lowering treatment were included. Participants received vildagliptin 50 mg b.i.d. or acarbose 100 mg t.i.d. for four consecutive weeks in a randomized, double-blind, cross-over design. At the end of each treatment period, we measured forearm vasodilator responses to intra-arterially administered acetylcholine (endothelium-dependent vasodilator) and sodium nitroprusside (endothelium-independent vasodilator). RESULTS Infusion of acetylcholine induced a dose-dependent increase in forearm blood flow in the experimental arm, which was higher during vildagliptin (3.1 ± 0.7, 7.9 ± 1.1, and 12.6 ± 1.4 mL ⋅ dL−1 ⋅ min−1 in response to three increasing dosages of acetylcholine) than during acarbose (2.0 ± 0.7, 5.0 ± 1.2, and 11.7 ± 1.6 mL ⋅ dL−1 ⋅ min−1, respectively; P = 0.01 by two-way ANOVA). Treatment with vildagliptin did not significantly change the vascular responses to sodium nitroprusside. CONCLUSIONS Four weeks’ treatment with vildagliptin improves endothelium-dependent vasodilatation in subjects with type 2 diabetes. This observation might have favorable cardiovascular implications. PMID:21788633

Characterization of P2Y receptors mediating ATP induced relaxation in guinea pig airway smooth muscle: involvement of prostaglandins and K+ channels.

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Montaño, Luis M; Cruz-Valderrama, José E; Figueroa, Alejandra; Flores-Soto, Edgar; García-Hernández, Luz M; Carbajal, Verónica; Segura, Patricia; Méndez, Carmen; Díaz, Verónica; Barajas-López, Carlos

2011-10-01

In airway smooth muscle (ASM), adenosine 5'-triphosphate (ATP) induces a relaxation associated with prostaglandin production. We explored the role of K(+) currents (I (K)) in this relaxation. ATP relaxed the ASM, and this effect was abolished by indomethacin. Removal of airway epithelium slightly diminished the ATP-induced relaxation at lower concentration without modifying the responses to ATP at higher concentrations. ATPγS and UTP induced a concentration-dependent relaxation similar to ATP; α,β-methylene-ATP was inactive from 1 to 100 μM. Suramin or reactive blue 2 (RB2), P2Y receptor antagonists, did not modify the relaxation, but their combination significantly reduced this effect of ATP. The relaxation was also inhibited by N-ethylmaleimide (NEM; which uncouples G proteins). In myocytes, the ATP-induced I (K) increment was not modified by suramin or RB2 but the combination of both drugs abolished it. This increment in the I (K) was also completely nullified by NEM and SQ 22,536. 4-Amynopyridine or iberiotoxin diminished the ATP-induced I (K) increment, and the combination of both substances diminished ATP-induced relaxation. The presence of P2Y(2) and P2Y(4) receptors in smooth muscle was corroborated by Western blot and confocal images. In conclusion, ATP: (1) produces relaxation by inducing the production of bronchodilator prostaglandins in airway smooth muscle, most likely by acting on P2Y(4) and P2Y(2) receptors; (2) induces I (K) increment through activation of the delayed rectifier K(+) channels and the high-conductance Ca(2+)-dependent K(+) channels, therefore both channels are implicated in the ATP-induced relaxation; and (3) this I (K) increment is mediated by prostaglandin production which in turns increase cAMP signaling pathway.

Activation of retinal glial (Müller cells by extracellular ATP induces pronounced increases in extracellular H+ flux.

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Boriana K Tchernookova

Full Text Available Small alterations in extracellular acidity are potentially important modulators of neuronal signaling within the vertebrate retina. Here we report a novel extracellular acidification mechanism mediated by glial cells in the retina. Using self-referencing H+-selective microelectrodes to measure extracellular H+ fluxes, we show that activation of retinal Müller (glial cells of the tiger salamander by micromolar concentrations of extracellular ATP induces a pronounced extracellular H+ flux independent of bicarbonate transport. ADP, UTP and the non-hydrolyzable analog ATPγs at micromolar concentrations were also potent stimulators of extracellular H+ fluxes, but adenosine was not. The extracellular H+ fluxes induced by ATP were mimicked by the P2Y1 agonist MRS 2365 and were significantly reduced by the P2 receptor blockers suramin and PPADS, suggesting activation of P2Y receptors. Bath-applied ATP induced an intracellular rise in calcium in Müller cells; both the calcium rise and the extracellular H+ fluxes were significantly attenuated when calcium re-loading into the endoplasmic reticulum was inhibited by thapsigargin and when the PLC-IP3 signaling pathway was disrupted with 2-APB and U73122. The anion transport inhibitor DIDS also markedly reduced the ATP-induced increase in H+ flux while SITS had no effect. ATP-induced H+ fluxes were also observed from Müller cells isolated from human, rat, monkey, skate and lamprey retinae, suggesting a highly evolutionarily conserved mechanism of potential general importance. Extracellular ATP also induced significant increases in extracellular H+ flux at the level of both the outer and inner plexiform layers in retinal slices of tiger salamander which was significantly reduced by suramin and PPADS. We suggest that the novel H+ flux mediated by ATP-activation of Müller cells and of other glia as well may be a key mechanism modulating neuronal signaling in the vertebrate retina and throughout the brain.

Acidic pH facilitates peripheral αβmeATP-mediated nociception in rats: differential roles of P2X, P2Y, ASIC and TRPV1 receptors in ATP-induced mechanical allodynia and thermal hyperalgesia.

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Seo, Hyoung-Sig; Roh, Dae-Hyun; Kwon, Soon-Gu; Yoon, Seo-Yeon; Kang, Suk-Yun; Moon, Ji-Young; Choi, Sheu-Ran; Beitz, Alvin J; Lee, Jang-Hern

2011-03-01

Peripheral ischemia is commonly associated with an increase in tissue ATP concentration and a decrease in tissue pH. Although in vitro data suggest that low tissue pH can affect ATP-binding affinities to P2 receptors, the mechanistic relationship between ATP and low pH on peripheral nociception has not been fully examined. This study was designed to investigate the potential role of an acidified environment on intraplantar αβmeATP-induced peripheral pain responses in rats. The mechanical allodynia (MA) produced by injection of αβmeATP was significantly increased in animals that received the drug diluted in pH 4.0 saline compared to those that received the drug diluted in pH 7.0 saline. Moreover, animals injected with αβmeATP (100 nmol) in pH 4.0 saline developed thermal hyperalgesia (TH), which did not occur in animals treated with αβmeATP diluted in pH 7.0 saline. To elucidate which receptors were involved in this pH-related facilitation of αβmeATP-induced MA and TH, rats were pretreated with PPADS (P2 antagonist), TNP-ATP (P2X antagonist), MRS2179 (P2Y1 antagonist), AMG9810 (TRPV1 antagonist) or amiloride (ASIC blocker). Both PPADS and TNP-ATP dose-dependently blocked pH-facilitated MA, while TH was significantly reduced by pre-treatment with MRS2179 or AMG9810. Moreover, amiloride injection significantly reduced low pH-induced facilitation of αβmeATP-mediated MA, but not TH. These results demonstrate that low tissue pH facilitates ATP-mediated MA via the activation of P2X receptors and ASICs, whereas TH induced by ATP under low pH conditions is mediated by the P2Y1 receptor and TRPV1, but not ASIC. Thus distinct mechanisms are responsible for the development of MA and TH under conditions of tissue acidosis and increased ATP. Copyright © 2010 Elsevier Ltd. All rights reserved.

Vacquinol-1 inducible cell death in glioblastoma multiforme is counter regulated by TRPM7 activity induced by exogenous ATP.

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Sander, Philip; Mostafa, Haouraa; Soboh, Ayman; Schneider, Julian M; Pala, Andrej; Baron, Ann-Kathrin; Moepps, Barbara; Wirtz, C Rainer; Georgieff, Michael; Schneider, Marion

2017-05-23

Glioblastomas (GBM) are the most malignant brain tumors in humans and have a very poor prognosis. New therapeutic options are urgently needed. A novel drug, Vacquinol-1 (Vac), a quinolone derivative, displays promising properties by inducing rapid cell death in GBM but not in non-transformed tissues. Features of this type of cell death are compatible with a process termed methuosis. Here we tested Vac on a highly malignant glioma cell line observed by long-term video microscopy. Human dental-pulp stem cells (DPSCs) served as controls. A major finding was that an exogenous ATP concentration of as little as 1 μM counter regulated the Vac-induced cell death. Studies using carvacrol, an inhibitor of transient receptor potential cation channel, subfamily M, member 7 (TRPM7), demonstrated that the ATP-inducible inhibitory effect is likely to be via TRPM7. Exogenous ATP is of relevance in GBM with large necrotic areas. Our results support the use of GBM cultures with different grades of malignancy to address their sensitivity to methuosis. The video-microscopy approach presented here allows decoding of signaling pathways as well as mechanisms of chemotherapeutic resistance by long-term observation. Before implementing Vac as a novel therapeutic drug in GBM, cells from each individual patient need to be assessed for their ATP sensitivity. In summary, the current investigation supports the concept of methuosis, described as non-apoptotic cell death and a promising approach for GBM treatment. Tissue-resident ATP/necrosis may interfere with this cell-death pathway but can be overcome by a natural compound, carvacrol that even penetrates the blood-brain barrier.

Biotin enhances ATP synthesis in pancreatic islets of the rat, resulting in reinforcement of glucose-induced insulin secretion.

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Sone, Hideyuki; Sasaki, Yuka; Komai, Michio; Toyomizu, Masaaki; Kagawa, Yasuo; Furukawa, Yuji

2004-02-13

Previous studies showed that biotin enhanced glucose-induced insulin secretion. Changes in the cytosolic ATP/ADP ratio in the pancreatic islets participate in the regulation of insulin secretion by glucose. In the present study we investigated whether biotin regulates the cytosolic ATP/ADP ratio in glucose-stimulated islets. When islets were stimulated with glucose plus biotin, the ATP/ADP ratio increased to approximately 160% of the ATP/ADP ratio in islets stimulated with glucose alone. The rate of glucose oxidation, assessed by CO(2) production, was also about 2-fold higher in islets treated with biotin. These increasing effects of biotin were proportional to the effects seen in insulin secretion. There are no previous reports of vitamins, such as biotin, directly affecting ATP synthesis. Our data indicate that biotin enhances ATP synthesis in islets following the increased rate of substrate oxidation in mitochondria and that, as a consequence of these events, glucose-induced insulin release is reinforced by biotin.

The pathophysiology of arterial vasodilatation and hyperdynamic circulation in cirrhosis

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Møller, Søren; Bendtsen, Flemming

2018-01-01

transplantation and point to the pathophysiological significance of portal hypertension. In this paper we aimed to review current knowledge on the pathophysiology of arterial vasodilatation and the hyperdynamic circulation in cirrhosis. This article is protected by copyright. All rights reserved.......Patients with cirrhosis and portal hypertension often develop complications from a variety of organ systems leading to a multiple organ failure. The combination of liver failure and portal hypertension result in a hyperdynamic circulatory state partly owing to simultaneous splanchnic and peripheral...... arterial vasodilatation. Increases in circulatory vasodilators are believed to be due to portosystemic shunting and bacterial translocation leading to redistribution of the blood volume with central hypovolemia. Portal hypertension per se and increased splanchnic blood flow are mainly responsible...

Resveratrol induces autophagy by directly inhibiting mTOR through ATP competition

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Park, Dohyun; Jeong, Heeyoon; Lee, Mi Nam; Koh, Ara; Kwon, Ohman; Yang, Yong Ryoul; Noh, Jungeun; Suh, Pann-Ghill; Park, Hwangseo; Ryu, Sung Ho

2016-01-01

Resveratrol (RSV) is a natural polyphenol that has a beneficial effect on health, and resveratrol-induced autophagy has been suggested to be a key process in mediating many beneficial effects of resveratrol, such as reduction of inflammation and induction of cancer cell death. Although various resveratrol targets have been suggested, the molecule that mediates resveratrol-induced autophagy remains unknown. Here, we demonstrate that resveratrol induces autophagy by directly inhibiting the mTOR-ULK1 pathway. We found that inhibition of mTOR activity and presence of ULK1 are required for autophagy induction by resveratrol. In line with this mTOR dependency, we found that resveratrol suppresses the viability of MCF7 cells but not of SW620 cells, which are mTOR inhibitor sensitive and insensitive cancer cells, respectively. We also found that resveratrol-induced cancer cell suppression occurred ULK1 dependently. For the mechanism of action of resveratrol on mTOR inhibition, we demonstrate that resveratrol directly inhibits mTOR. We found that resveratrol inhibits mTOR by docking onto the ATP-binding pocket of mTOR (i.e., it competes with ATP). We propose mTOR as a novel direct target of resveratrol, and inhibition of mTOR is necessary for autophagy induction. PMID:26902888

Reproducibility of skeletal muscle vasodilatation responses to Stroop mental challenge over repeated sessions.

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Hamer, Mark; Boutcher, Yati N; Park, Young; Boutcher, Stephen H

2006-08-01

Skeletal muscle blood flow responses to stress have implications for psychobiological disease pathways. An important assumption underlying psychophysiological studies relating stress reactivity with disease risk is that individuals are characterized by stable response profiles that can be reliably assessed using acute psychophysiological stress testing. We examined the reproducibility of forearm vasodilatation, blood pressure, and cardiac responses to a 2 min Stroop mental challenge over two repeated stress sessions that were on average 3.6 months apart. Participants were 21 healthy men and women (aged 21.8+/-3.7 years). Vasodilatation, blood pressure and heart rate responses displayed no habituation between sessions, although there was significantly greater cardiac parasympathetic involvement during the second testing session. Significant test-retest correlations between the sessions were observed for both forearm blood flow and heart rate reactivity. These findings demonstrate skeletal muscle vasodilatation responses to repeated stress are robust, so may be a useful psychophysiological indicator in studies of stress reactivity and disease risk.

Histamine, carbachol, and serotonin induce hyperresponsiveness to ATP in guinea pig tracheas: involvement of COX-2 pathway.

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Montaño, Luis M; Carbajal, Verónica; Vargas, Mario H; García-Hernández, Luz M; Díaz-Hernández, Verónica; Checa, Marco; Barajas-López, Carlos

2013-08-01

Extracellular ATP promotes an indirect contraction of airway smooth muscle via the secondary release of thromboxane A2 (TXA2) from airway epithelium. Our aim was to evaluate if common contractile agonists modify this response to ATP. Tracheas from sensitized guinea pigs were used to evaluate ATP-induced contractions before and after a transient contraction produced by histamine, carbachol, or serotonin. Epithelial mRNA for COX-1 and COX-2 was measured by RT-PCR and their expression assessed by immunohistochemistry. Compared with the initial response, ATP-induced contraction was potentiated by pretreatment with histamine, carbachol, or serotonin. Either suramin (antagonist of P2X and P2Y receptors) plus RB2 (antagonist of P2Y receptors) or indomethacin (inhibitor of COX-1 and COX-2) annulled the ATP-induced contraction, suggesting that it was mediated by P2Y receptor stimulation and TXA2 production. When COX-2 was inhibited by SC-58125 or thromboxane receptors were antagonized by SQ-29548, just the potentiation was abolished, leaving the basal response intact. Airway epithelial cells showed increased COX-2 mRNA after stimulation with histamine or carbachol, but not serotonin, while COX-1 mRNA was unaffected. Immunochemistry corroborated this upregulation of COX-2. In conclusion, we showed for the first time that histamine and carbachol cause hyperresponsiveness to ATP by upregulating COX-2 in airway epithelium, which likely increases TXA2 production. Serotonin-mediated hyperresponsiveness seems to be independent of COX-2 upregulation, but nonetheless is TXA2 dependent. Because acetylcholine, histamine, and serotonin can be present during asthmatic exacerbations, their potential interactions with ATP might be relevant in its pathophysiology.

α-Synuclein-induced dopaminergic neurodegeneration in a rat model of Parkinson's disease occurs independent of ATP13A2 (PARK9).

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Daniel, Guillaume; Musso, Alessandra; Tsika, Elpida; Fiser, Aris; Glauser, Liliane; Pletnikova, Olga; Schneider, Bernard L; Moore, Darren J

2015-01-01

Mutations in the ATP13A2 (PARK9) gene cause early-onset, autosomal recessive Parkinson's disease (PD) and Kufor-Rakeb syndrome. ATP13A2 mRNA is spliced into three distinct isoforms encoding a P5-type ATPase involved in regulating heavy metal transport across vesicular membranes. Here, we demonstrate that three ATP13A2 mRNA isoforms are expressed in the normal human brain and are modestly increased in the cingulate cortex of PD cases. ATP13A2 can mediate protection toward a number of stressors in mammalian cells and can protect against α-synuclein-induced toxicity in cellular and invertebrate models of PD. Using a primary cortical neuronal model combined with lentiviral-mediated gene transfer, we demonstrate that human ATP13A2 isoforms 1 and 2 display selective neuroprotective effects toward toxicity induced by manganese and hydrogen peroxide exposure through an ATPase-independent mechanism. The familial PD mutations, F182L and G504R, abolish the neuroprotective effects of ATP13A2 consistent with a loss-of-function mechanism. We further demonstrate that the AAV-mediated overexpression of human ATP13A2 is not sufficient to attenuate dopaminergic neurodegeneration, neuropathology, and striatal dopamine and motoric deficits induced by human α-synuclein expression in a rat model of PD. Intriguingly, the delivery of an ATPase-deficient form of ATP13A2 (D513N) to the substantia nigra is sufficient to induce dopaminergic neuronal degeneration and motor deficits in rats, potentially suggesting a dominant-negative mechanism of action. Collectively, our data demonstrate a distinct lack of ATP13A2-mediated protection against α-synuclein-induced neurotoxicity in the rat nigrostriatal dopaminergic pathway, and limited neuroprotective capacity overall, and raise doubts about the potential of ATP13A2 as a therapeutic target for PD. Copyright © 2015 Elsevier Inc. All rights reserved.

A study of atriphos (ATP) action on muscular circulation in progressive muscular dystrophy by the radioactive xenon clearance technique

International Nuclear Information System (INIS)

Chakyrov, B.; Samardzhiev, A.

1977-01-01

The effect of intramuscularly and intravenously adminostered atriphos on the muscular circulation was studied with radioactive xenon in 12 children with progressive muscular dystrophy. After combined local intramuscular injection of ATP (atriphos) with the radioactive marker a 12-fold increment of muscular circulation ensues, lasting about 15 minutes. No vasodilatating effect on the muscular flow was oberved after intravenous injection of 20-40 mg of atriphos. It is believed that intramuscular administration of atriphos produced dilatation of capillaries and of the venous part of the muscular circulation. (author)

Peripheral vasodilatation determines cardiac output in exercising humans

DEFF Research Database (Denmark)

Bada, A A; Svendsen, J H; Secher, N H

2012-01-01

In dogs, manipulation of heart rate has no effect on the exercise-induced increase in cardiac output. Whether these findings apply to humans remain uncertain, because of the large differences in cardiovascular anatomy and regulation. To investigate the role of heart rate and peripheral...... arterial ATP infusion at rest. Exercise and ATP infusion increased cardiac output, leg blood flow and vascular conductance (P heart rate by up to 54 beats min(−1), cardiac output did not change in any of the three...... demonstrate that the elevated cardiac output during steady-state exercise is regulated by the increase in skeletal muscle blood flow and venous return to the heart, whereas the increase in heart rate appears to be secondary to the regulation of cardiac output....

Extracellular ATP in the Exocrine Pancreas – ATP Release, Signalling and Metabolism

DEFF Research Database (Denmark)

Kowal, Justyna Magdalena

release. So far, the contribution of duct cells in purinergic signalling has never been studied. This work presents that both acinar and duct cells are sources of extracellular ATP in the exocrine pancreas. Here we show that duct cells release ATP in response to several physiological......ATP plays an important role as an autocrine/paracrine signalling molecule, being released from a number of tissues, in response to physiological and pathophysiological stimuli. Released ATP induces Ca2+ - and/or cAMP - dependent cellular responses via activation of ubiquitously expressed P2X and P2......, particularly during Ca2+ stress conditions. In conclusion, these studies demonstrate a complex regulation of purinergic signalling in exocrine pancreas. A crucial role for duct cells in mediating extracellular nucleotides homeostasis, involving ATP release, subsequent hydrolysis and conversion via...

Vildagliptin improves endothelium-dependent vasodilatation in type 2 diabetes

NARCIS (Netherlands)

van Poppel, P.C.; Netea, M.G.; Smits, P.; Tack, C.J.J.

2011-01-01

OBJECTIVE: To investigate whether the dipeptidyl peptidase-4 inhibitor vildagliptin improves endothelium-dependent vasodilatation in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: Sixteen subjects with type 2 diabetes (age 59.8 +/- 6.8 years, BMI 29.1 +/- 4.8 kg/m(2), HbA(1c) 6.97 +/-

Sildenafil protects neuronal cells from mitochondrial toxicity induced by β-amyloid peptide via ATP-sensitive K+ channels.

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Son, Yonghae; Kim, Koanhoi; Cho, Hyok-Rae

2018-06-02

To understand the molecular mechanisms underlying the beneficial effects of sildenafil in animal models of neurological disorders, we investigated the effects of sildenafil on the mitochondrial toxicity induced by β-amyloid (Aβ) peptide. Treatment of HT-22 hippocampal neuronal cells with Aβ 25∼35 results in increased mitochondrial Ca 2+ load, which is subsequently suppressed by sildenafil as well as by diazoxide, a selective opener of the ATP-sensitive K + channels (K ATP ). However, the suppressive effects of sildenafil and diazoxide are significantly attenuated by 5-hydroxydecanoic acid (5-HD), a K ATP inhibitor. The increased mitochondrial Ca 2+ overload is accompanied by decrease in the intracellular ATP concentration, increase in intracellular ROS generation, occurrence of mitochondrial permeability transition, and activation of caspase-9 and cell death. Exposure to sildenafil inhibited the mitochondria-associated changes and cell death induced by Aβ. However, the inhibitory effects of sildenafil are abolished or weakened in the presence of 5-HD, suggesting that opening of the mitochondrial K ATP is required for sildenafil to exert these effects. Taken together, these results indicate that at the mitochondrial levels, sildenafil plays a protective role towards neuronal cell in an environment rich in Aβ, and exerts its effects via the mitochondrial K ATP channels-dependent mechanisms. Copyright © 2018 Elsevier Inc. All rights reserved.

SIRT3 deacetylates ATP synthase F1 complex proteins in response to nutrient- and exercise-induced stress.

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Vassilopoulos, Athanassios; Pennington, J Daniel; Andresson, Thorkell; Rees, David M; Bosley, Allen D; Fearnley, Ian M; Ham, Amy; Flynn, Charles Robb; Hill, Salisha; Rose, Kristie Lindsey; Kim, Hyun-Seok; Deng, Chu-Xia; Walker, John E; Gius, David

2014-08-01

Adenosine triphosphate (ATP) synthase uses chemiosmotic energy across the inner mitochondrial membrane to convert adenosine diphosphate and orthophosphate into ATP, whereas genetic deletion of Sirt3 decreases mitochondrial ATP levels. Here, we investigate the mechanistic connection between SIRT3 and energy homeostasis. By using both in vitro and in vivo experiments, we demonstrate that ATP synthase F1 proteins alpha, beta, gamma, and Oligomycin sensitivity-conferring protein (OSCP) contain SIRT3-specific reversible acetyl-lysines that are evolutionarily conserved and bind to SIRT3. OSCP was further investigated and lysine 139 is a nutrient-sensitive SIRT3-dependent deacetylation target. Site directed mutants demonstrate that OSCP(K139) directs, at least in part, mitochondrial ATP production and mice lacking Sirt3 exhibit decreased ATP muscle levels, increased ATP synthase protein acetylation, and an exercise-induced stress-deficient phenotype. This work connects the aging and nutrient response, via SIRT3 direction of the mitochondrial acetylome, to the regulation of mitochondrial energy homeostasis under nutrient-stress conditions by deacetylating ATP synthase proteins. Our data suggest that acetylome signaling contributes to mitochondrial energy homeostasis by SIRT3-mediated deacetylation of ATP synthase proteins.

Effect of tributyltin (TBT) on ATP levels in human natural killer (NK) cells: relationship to TBT-induced decreases in NK function.

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Dudimah, Fred D; Odman-Ghazi, Sabah O; Hatcher, Frank; Whalen, Margaret M

2007-01-01

The purpose of this study was to investigate the role that tributyltin (TBT)-induced decreases in ATP levels may play in TBT-induced decreases in the tumor lysing (lytic) function of natural killer (NK) cells. NK cells are a subset of lymphocytes that act as an initial immune defense against tumor cells and virally infected cells. TBT is an environmental contaminant that has been detected in human blood, which has been shown to interfere with ATP synthesis. Previous studies have shown that TBT is able to decrease very significantly the lytic function of NK cells. In this study NK cells were exposed to various concentrations of TBT and to two other compounds that interfere with ATP synthesis (rotenone a complex I inhibitor and oligomycin an ATP synthase inhibitor) for various lengths of time before determining the levels of ATP and lytic function. Exposures of NK cells to 10, 25, 50 and 100 nm TBT did not significantly reduce ATP levels after 24 h. However, these same exposures caused significant decreases in cytotoxic function. Studies of brief 1 h exposures to a range of TBT, rotenone and oligomycin concentrations followed by 24 h, 48 h and 6 day periods in compound-free media prior to assaying for ATP levels or cytotoxic function showed that each of the compounds caused persistent decreases in ATP levels and lytic function of NK cells. Exposures to 0.05-5 microm rotenone or oligomycin for 1 h reduced ATP levels by 20-25% but did not have any measurable effect on the ability of NK cells to lyse tumor cells. ATP levels were also decreased by about 20-25% after 24 h or 48 h exposures to rotenone or oligomycin (0.5 microm ), and the lytic function was decreased by about 50%. The results suggest that TBT-induced decreases in ATP levels were not responsible for the loss of cytotoxic function seen at 1 h and 24 h. However, TBT-induced decreases of NK-ATP levels may be at least in part responsible for losses of NK-cytotoxic function seen after 48 h and 6 day exposures

Apixaban Enhances Vasodilatation Mediated by Protease-Activated Receptor 2 in Isolated Rat Arteries

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Ambra Villari

2017-07-01

Full Text Available Apixaban (APX is a direct inhibitor of factor X (FXa approved for prophylaxis and treatment of deep venous thrombosis and atrial fibrillation. Because FXa activates protease-activated receptor 2 (PAR-2 in endothelium and vascular smooth muscle, inhibition of FXa by APX may affect vasomotor function. The effect of APX was assessed in vitro, by wire myography, in rat mesenteric resistance arteries (MRAs and basilar arteries challenged with vasoconstrictors [phenylephrine (PE; 5-hydroxytryptamine (5-HT], vasodilators [acetylcholine (ACh; sodium nitroprusside (SNP] or with the PAR-2 peptide agonist SLIGRL. APX (10 μM reduced the vasoconstriction to PE and 5-HT while did not change the vasodilatation to ACh or SNP. SLIGRL induced concentration-dependent vasodilation in pre-constricted arteries, that was reduced by incubation with the NO inhibitor NG-nitro-L-arginine (L-NNA and abolished by endothelium removal. APX enhanced vasodilation to SLIGRL either in the presence or in the absence of L-NNA, but was ineffective in endothelium-denuded vessels. In preparations from heparin-treated rats (to inhibit FXa APX did not change the vasodilation to SLIGRL. FXa enzymatic activity, detected in mesentery homogenates from controls, was inhibited by APX, whereas APX-sensitive enzymatic activity was undetectable in homogenates from heparin-treated rats. Immunoblot analysis showed that incubation of MRA or aorta with APX increased the abundance of PAR-2, an effect not seen in MRA from heparin-treated rats or in endothelium-denuded aortas. In conclusion, inhibition of FXa by APX increases vasodilatation mediated by PAR-2. APX may act by inhibiting PAR-2 desensitization induced by endogenous FXa. This effect could be useful in the context of endothelial dysfunction associated to cardiovascular diseases.

ATP-induced changes in rat skeletal muscle contractility.

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Gabdrakhmanov, A I; Khayrullin, A E; Grishin, C H; Ziganshin, A U

2015-01-01

Extracellular purine compounds, adenosine triphosphate (ATP) and adenosine, are involved in regulation of many cell functions, engaging in rapid and long-term cellular processes. The nucleotides, including ATP, exert their extracellular effects by influencing membrane P2 receptors. ATP outside of the cell rapidly is metabolized by the ecto-enzyme system to produce adenosine, which acts on separate adenosine (P1) receptors. Since adenosine and ATP often are functional antagonists, ATP degradation not only limits its effect, but also brings new ligand with different, often opposing, properties. Great variety and widespread of P2 and adenosine receptors in the body emphasize the important physiological and pathophysiological significance of these receptors, and make them very attractive as targets for potential drug action.The existence of several subtypes of P2 and adenosine receptors has been shown in the skeletal muscles. ATP as a co-transmitter is densely packed together with classical neurotransmitters in the presynaptic vesicles of vertebral motor units but until recently ATP was refused to have its own functional role there and was recognized only as a source of adenosine. However, on the eve of the third millennium there appeared data that ATP, released from the nerve ending and acting on presynaptic P2 receptors, suppresses subsequent quantum release of acetylcholine. The final product of its degradation, adenosine, performs a similar inhibitory effect acting on presynaptic adenosine receptors.Despite the fact that the mechanisms of presynaptic inhibitory action of ATP and other purines were studied earlier, the object of those studies was usually neuromuscular synapse of cold-blooded animals. The few studies, in which experiments were carried out on preparations of warm-blooded animals, described the basic effects of purines. These often were guided by the convenience of preparation of the synapses of the diaphragm. We think that those results cannot be

PAR-2 activation enhances weak acid-induced ATP release through TRPV1 and ASIC sensitization in human esophageal epithelial cells.

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Wu, Liping; Oshima, Tadayuki; Shan, Jing; Sei, Hiroo; Tomita, Toshihiko; Ohda, Yoshio; Fukui, Hirokazu; Watari, Jiro; Miwa, Hiroto

2015-10-15

Esophageal visceral hypersensitivity has been proposed to be the pathogenesis of heartburn sensation in nonerosive reflux disease. Protease-activated receptor-2 (PAR-2) is expressed in human esophageal epithelial cells and is believed to play a role in inflammation and sensation. PAR-2 activation may modulate these responses through adenosine triphosphate (ATP) release, which is involved in transduction of sensation and pain. The transient receptor potential vanilloid receptor 1 (TRPV1) and acid-sensing ion channels (ASICs) are both acid-sensitive nociceptors. However, the interaction among these molecules and the mechanisms of heartburn sensation are still not clear. We therefore examined whether ATP release in human esophageal epithelial cells in response to acid is modulated by TRPV1 and ASICs and whether PAR-2 activation influences the sensitivity of TRPV1 and ASICs. Weak acid (pH 5) stimulated the release of ATP from primary human esophageal epithelial cells (HEECs). This effect was significantly reduced after pretreatment with 5-iodoresiniferatoxin (IRTX), a TRPV1-specific antagonist, or with amiloride, a nonselective ASIC blocker. TRPV1 and ASIC3 small interfering RNA (siRNA) transfection also decreased weak acid-induced ATP release. Pretreatment of HEECs with trypsin, tryptase, or a PAR-2 agonist enhanced weak acid-induced ATP release. Trypsin treatment led to the phosphorylation of TRPV1. Acid-induced ATP release enhancement by trypsin was partially blocked by IRTX, amiloride, or a PAR-2 antagonist. Conversely, acid-induced ATP release was augmented by PAR-2 activation through TRPV1 and ASICs. These findings suggested that the pathophysiology of heartburn sensation or esophageal hypersensitivity may be associated with the activation of PAR-2, TRPV1, and ASICs. Copyright © 2015 the American Physiological Society.

ATP depletion during mitotic arrest induces mitotic slippage and APC/CCdh1-dependent cyclin B1 degradation.

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Park, Yun Yeon; Ahn, Ju-Hyun; Cho, Min-Guk; Lee, Jae-Ho

2018-04-27

ATP depletion inhibits cell cycle progression, especially during the G1 phase and the G2 to M transition. However, the effect of ATP depletion on mitotic progression remains unclear. We observed that the reduction of ATP after prometaphase by simultaneous treatment with 2-deoxyglucose and NaN 3 did not arrest mitotic progression. Interestingly, ATP depletion during nocodazole-induced prometaphase arrest resulted in mitotic slippage, as indicated by a reduction in mitotic cells, APC/C-dependent degradation of cyclin B1, increased cell attachment, and increased nuclear membrane reassembly. Additionally, cells successfully progressed through the cell cycle after mitotic slippage, as indicated by EdU incorporation and time-lapse imaging. Although degradation of cyclin B during normal mitotic progression is primarily regulated by APC/C Cdc20 , we observed an unexpected decrease in Cdc20 prior to degradation of cyclin B during mitotic slippage. This decrease in Cdc20 was followed by a change in the binding partner preference of APC/C from Cdc20 to Cdh1; consequently, APC/C Cdh1 , but not APC/C Cdc20 , facilitated cyclin B degradation following ATP depletion. Pulse-chase analysis revealed that ATP depletion significantly abrogated global translation, including the translation of Cdc20 and Cdh1. Additionally, the half-life of Cdh1 was much longer than that of Cdc20. These data suggest that ATP depletion during mitotic arrest induces mitotic slippage facilitated by APC/C Cdh1 -dependent cyclin B degradation, which follows a decrease in Cdc20 resulting from reduced global translation and the differences in the half-lives of the Cdc20 and Cdh1 proteins.

The Role of ATP in the Regulation of NCAM Function

DEFF Research Database (Denmark)

Hübschmann, Martin; Skladchikova, Galina

2008-01-01

overlaps with the site of NCAM-FGFR interaction, and ATP is capable of disrupting NCAM-FGFR binding. This implies that NCAM signaling through FGFR can be regulated by ATP, which is supported by the observation that ATP can abrogate NCAM-induced neurite outgrowth. Finally, ATP can induce NCAM ectodomain...... shedding, possibly affecting the structural plasticity associated with learning and memory....

Decipher the mechanisms of protein conformational changes induced by nucleotide binding through free-energy landscape analysis: ATP binding to Hsp70.

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Adrien Nicolaï

Full Text Available ATP regulates the function of many proteins in the cell by transducing its binding and hydrolysis energies into protein conformational changes by mechanisms which are challenging to identify at the atomic scale. Based on molecular dynamics (MD simulations, a method is proposed to analyze the structural changes induced by ATP binding to a protein by computing the effective free-energy landscape (FEL of a subset of its coordinates along its amino-acid sequence. The method is applied to characterize the mechanism by which the binding of ATP to the nucleotide-binding domain (NBD of Hsp70 propagates a signal to its substrate-binding domain (SBD. Unbiased MD simulations were performed for Hsp70-DnaK chaperone in nucleotide-free, ADP-bound and ATP-bound states. The simulations revealed that the SBD does not interact with the NBD for DnaK in its nucleotide-free and ADP-bound states whereas the docking of the SBD was found in the ATP-bound state. The docked state induced by ATP binding found in MD is an intermediate state between the initial nucleotide-free and final ATP-bound states of Hsp70. The analysis of the FEL projected along the amino-acid sequence permitted to identify a subset of 27 protein internal coordinates corresponding to a network of 91 key residues involved in the conformational change induced by ATP binding. Among the 91 residues, 26 are identified for the first time, whereas the others were shown relevant for the allosteric communication of Hsp70 s in several experiments and bioinformatics analysis. The FEL analysis revealed also the origin of the ATP-induced structural modifications of the SBD recently measured by Electron Paramagnetic Resonance. The pathway between the nucleotide-free and the intermediate state of DnaK was extracted by applying principal component analysis to the subset of internal coordinates describing the transition. The methodology proposed is general and could be applied to analyze allosteric communication in

ATP induces NO production in hippocampal neurons by P2X(7 receptor activation independent of glutamate signaling.

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Juan Francisco Codocedo

Full Text Available To assess the putative role of adenosine triphosphate (ATP upon nitric oxide (NO production in the hippocampus, we used as a model both rat hippocampal slices and isolated hippocampal neurons in culture, lacking glial cells. In hippocampal slices, additions of exogenous ATP or 2'(3'-O-(4-Benzoylbenzoyl ATP (Bz-ATP elicited concentration-dependent NO production, which increased linearly within the first 15 min and plateaued thereafter; agonist EC50 values were 50 and 15 µM, respectively. The NO increase evoked by ATP was antagonized in a concentration-dependent manner by Coomassie brilliant blue G (BBG or by N(ω-propyl-L-arginine, suggesting the involvement of P2X7Rs and neuronal NOS, respectively. The ATP induced NO production was independent of N-methyl-D-aspartic acid (NMDA receptor activity as effects were not alleviated by DL-2-Amino-5-phosphonopentanoic acid (APV, but antagonized by BBG. In sum, exogenous ATP elicited NO production in hippocampal neurons independently of NMDA receptor activity.

Dynamic Changes in Cytosolic ATP Levels in Cultured Glutamatergic Neurons During NMDA-Induced Synaptic Activity Supported by Glucose or Lactate.

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Lange, Sofie C; Winkler, Ulrike; Andresen, Lars; Byhrø, Mathilde; Waagepetersen, Helle S; Hirrlinger, Johannes; Bak, Lasse K

2015-12-01

We have previously shown that synaptic transmission fails in cultured neurons in the presence of lactate as the sole substrate. Thus, to test the hypothesis that the failure of synaptic transmission is a consequence of insufficient energy supply, ATP levels were monitored employing the ATP biosensor Ateam1.03YEMK. While inducing synaptic activity by subjecting cultured neurons to two 30 s pulses of NMDA (30 µM) with a 4 min interval, changes in relative ATP levels were measured in the presence of lactate (1 mM), glucose (2.5 mM) or the combination of the two. ATP levels reversibly declined following NMDA-induced neurotransmission activity, as indicated by a reversible 10-20 % decrease in the response of the biosensor. The responses were absent when the NMDA receptor antagonist memantine was present. In the presence of lactate alone, the ATP response dropped significantly more than in the presence of glucose following the 2nd pulse of NMDA (approx. 10 vs. 20 %). Further, cytosolic Ca(2+) homeostasis during NMDA-induced synaptic transmission is partially inhibited by verapamil indicating that voltage-gated Ca(2+) channels are activated. Lastly, we showed that cytosolic Ca(2+) homeostasis is supported equally well by both glucose and lactate, and that a pulse of NMDA causes accumulation of Ca(2+) in the mitochondrial matrix. In summary, we have shown that ATP homeostasis during neurotransmission activity in cultured neurons is supported by both glucose and lactate. However, ATP homeostasis seems to be negatively affected by the presence of lactate alone, suggesting that glucose is needed to support neuronal energy metabolism during activation.

Maitotoxin-induced liver cell death involving loss of cell ATP following influx of calcium

International Nuclear Information System (INIS)

Kutty, R.K.; Singh, Y.; Santostasi, G.; Krishna, G.

1989-01-01

Maitotoxin, one of the most potent marine toxins known, produced cell death in cultures of rat hepatocytes with a TD50 of 80 pM at 24 hr. The cell death, as indicated by a dose- and time-dependent leakage of lactate dehydrogenase (LDH), was also associated with the leakage of [14C]adenine nucleotides from hepatocytes prelabeled with [14C]-adenine. The toxic effect of maitotoxin was completely abolished by the omission of calcium from the culture medium. The cell death induced by maitotoxin increased with increasing concentrations of calcium in the medium. Treatment of hepatocytes with low concentrations of the toxin (less than 0.5 ng/ml) resulted in increases in 45Ca influx into the cells. At higher concentrations of maitotoxin (greater than 1ng/ml), the initial increase in 45Ca influx was followed by the release of the 45Ca from the cells into the medium. Since the 45Ca release paralleled the LDH leakage, the release of calcium was due to cell death. The 45Ca influx, [14C]adenine nucleotide leakage, and LDH leakage were effectively inhibited by verapamil, a calcium channel blocker. Maitotoxin also induced a time- and dose-dependent loss of ATP from hepatocytes, which preceded the [14C]adenine nucleotide and LDH leakage. Thus, it appears that the cell death resulting from maitotoxin treatment is caused by the elevated intracellular calcium, which in turn inhibits mitochondrial oxidative phosphorylation causing depletion of cell ATP. Loss of cell ATP may be the causative event in the maitotoxin-induced cell death

L-cysteine reversibly inhibits glucose-induced biphasic insulin secretion and ATP production by inactivating PKM2.

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Nakatsu, Daiki; Horiuchi, Yuta; Kano, Fumi; Noguchi, Yoshiyuki; Sugawara, Taichi; Takamoto, Iseki; Kubota, Naoto; Kadowaki, Takashi; Murata, Masayuki

2015-03-10

Increase in the concentration of plasma L-cysteine is closely associated with defective insulin secretion from pancreatic β-cells, which results in type 2 diabetes (T2D). In this study, we investigated the effects of prolonged L-cysteine treatment on glucose-stimulated insulin secretion (GSIS) from mouse insulinoma 6 (MIN6) cells and from mouse pancreatic islets, and found that the treatment reversibly inhibited glucose-induced ATP production and resulting GSIS without affecting proinsulin and insulin synthesis. Comprehensive metabolic analyses using capillary electrophoresis time-of-flight mass spectrometry showed that prolonged L-cysteine treatment decreased the levels of pyruvate and its downstream metabolites. In addition, methyl pyruvate, a membrane-permeable form of pyruvate, rescued L-cysteine-induced inhibition of GSIS. Based on these results, we found that both in vitro and in MIN6 cells, L-cysteine specifically inhibited the activity of pyruvate kinase muscle isoform 2 (PKM2), an isoform of pyruvate kinases that catalyze the conversion of phosphoenolpyruvate to pyruvate. L-cysteine also induced PKM2 subunit dissociation (tetramers to dimers/monomers) in cells, which resulted in impaired glucose-induced ATP production for GSIS. DASA-10 (NCGC00181061, a substituted N,N'-diarylsulfonamide), a specific activator for PKM2, restored the tetramer formation and the activity of PKM2, glucose-induced ATP production, and biphasic insulin secretion in L-cysteine-treated cells. Collectively, our results demonstrate that impaired insulin secretion due to exposure to L-cysteine resulted from its direct binding and inactivation of PKM2 and suggest that PKM2 is a potential therapeutic target for T2D.

Glucose is required to maintain high ATP-levels for the energy utilizing steps during PDT-induced apoptosis

International Nuclear Information System (INIS)

Oberdanner, C.; Plaetzer, K.; Kiesslich, T.; Krammer, B.

2003-01-01

Full text: Photodynamic therapy (PDT) may trigger apoptosis or necrosis in cancer cells. Several steps in the induction and execution of apoptosis require high amounts of adenosine-5'-triphosphate (ATP). Since the mitochondrial membrane potential (ΔΨ) decreases early in apoptosis, we raised the question about the mechanisms of maintaining a sufficiently high ATP-level. We therefore monitored ΔΨ and the intracellular ATP-level of apoptotic human epidermoid carcinoma cells (A431) after photodynamic treatment with aluminium (III) phthalocyanine tetrasulfonate chloride. A maximum of caspase-3 activation and nuclear fragmentation was found at fluences of about 4 J.cm -2 . Under these conditions apoptotic cells reduced ΔΨ rapidly, while the ATP-level remained high for 4 to 6 hours after treatment for cells supplied with glucose. To analyze the contribution of glycolysis to the energy supply during apoptosis experiments were carried out with cells deprivated of glucose. These cells showed a rapid drop of ATP-content and neither caspase-activation nor nuclear fragmentation could be detected. We conclude that the use of glucose as a source of ATP is obligatory for the execution of PDT-induced apoptosis. (author)

A label-free electrochemiluminescent sensor for ATP detection based on ATP-dependent ligation.

Science.gov (United States)

Zhao, Tingting; Lin, Chunshui; Yao, Qiuhong; Chen, Xi

2016-07-01

In this work, we describe a new label-free, sensitive and highly selective strategy for the electrochemiluminescent (ECL) detection of ATP at the picomolar level via ATP-induced ligation. The molecular-beacon like DNA probes (P12 complex) are self-assembled on a gold electrode. The presence of ATP leads to the ligation of P12 complex which blocks the digestion by Exonuclease III (Exo III). The protected P12 complex causes the intercalation of numerous ECL indicators (Ru(phen)3(2+)) into the duplex DNA grooves, resulting in significantly amplified ECL signal output. Since the ligating site of T4 DNA ligase and the nicking site of Exo III are the same, it involves no long time of incubation for conformation change. The proposed strategy combines the amplification power of enzyme and the inherent high sensitivity of the ECL technique and enables picomolar detection of ATP. The developed strategy also shows high selectivity against ATP analogs, which makes our new label-free and highly sensitive ligation-based method a useful addition to the amplified ATP detection arena. Copyright © 2016 Elsevier B.V. All rights reserved.

Dynamic changes in cytosolic ATP levels in cultured glutamatergic neurons during NMDA-induced synaptic activity supported by glucose or lactate

DEFF Research Database (Denmark)

Lange, Sofie Cecilie; Winkler, Ulrike; Andresen, Lars

2015-01-01

is supported equally well by both glucose and lactate, and that a pulse of NMDA causes accumulation of Ca(2+) in the mitochondrial matrix. In summary, we have shown that ATP homeostasis during neurotransmission activity in cultured neurons is supported by both glucose and lactate. However, ATP homeostasis...... biosensor Ateam1.03YEMK. While inducing synaptic activity by subjecting cultured neurons to two 30 s pulses of NMDA (30 µM) with a 4 min interval, changes in relative ATP levels were measured in the presence of lactate (1 mM), glucose (2.5 mM) or the combination of the two. ATP levels reversibly declined...... in the presence of glucose following the 2nd pulse of NMDA (approx. 10 vs. 20 %). Further, cytosolic Ca(2+) homeostasis during NMDA-induced synaptic transmission is partially inhibited by verapamil indicating that voltage-gated Ca(2+) channels are activated. Lastly, we showed that cytosolic Ca(2+) homeostasis...

Sildenafil citrate (Viagra) enhances vasodilatation in fetal growth restriction.

Science.gov (United States)

Wareing, Mark; Myers, Jenny E; O'Hara, Maureen; Baker, Philip N

2005-05-01

Fetal growth restriction (FGR) affects up to 8% of all pregnancies and has massive short-term (increased fetal morbidity and mortality) and long-term (increased incidence of cardiovascular disease in adulthood) health implications. Doppler waveform analysis of pregnancies complicated by FGR suggests compromised uteroplacental circulation and placental hypoperfusion. Our aim was to determine whether myometrial small artery function was aberrant in FGR and to assess whether sildenafil citrate could improve vasodilatation in FGR pregnancies. Small arteries dissected from myometrial biopsies obtained at cesarean section from normal pregnant women (n = 27) or women whose pregnancies were complicated by FGR (n = 12) were mounted on wire myographs. Vessels were constricted (with arginine vasopressin or U46619) and relaxed (with bradykinin) before and after incubation with a phosphodiesterase-5 inhibitor, sildenafil citrate. We demonstrated increased myometrial small artery vasoconstriction and decreased endothelium-dependent vasodilatation in vessels from women whose pregnancies were complicated by FGR. Sildenafil citrate significantly reduced vasoconstriction and significantly improved relaxation of FGR small arteries. We conclude that sildenafil citrate improves endothelial function of myometrial vessels from women whose pregnancies are complicated by intrauterine growth restriction. Sildenafil citrate may offer a potential therapeutic strategy to improve uteroplacental blood flow in FGR pregnancies.

Autocrine Regulation of UVA-Induced IL-6 Production via Release of ATP and Activation of P2Y Receptors

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Kawano, Ayumi; Kadomatsu, Remi; Ono, Miyu; Kojima, Shuji; Tsukimoto, Mitsutoshi; Sakamoto, Hikaru

2015-01-01

Extracellular nucleotides, such as ATP, are released from cells in response to various stimuli and act as intercellular signaling molecules through activation of P2 receptors. Exposure to the ultraviolet radiation A (UVA) component of sunlight causes molecular and cellular damage, and in this study, we investigated the involvement of extracellular nucleotides and P2 receptors in the UVA-induced cellular response. Human keratinocyte-derived HaCaT cells were irradiated with a single dose of UVA (2.5 J/cm2), and ATP release and interleukin (IL)-6 production were measured. ATP was released from cells in response to UVA irradiation, and the release was blocked by pretreatment with inhibitors of gap junction hemichannels or P2X7 receptor antagonist. IL-6 production was increased after UVA irradiation, and this increase was inhibited by ecto-nucleotidase or by antagonists of P2Y11 or P2Y13 receptor. These results suggest that UVA-induced IL-6 production is mediated by release of ATP through hemichannels and P2X7 receptor, followed by activation of P2Y11 and P2Y13 receptors. Interestingly, P2Y11 and P2Y13 were associated with the same pattern of IL-6 production, though they trigger different intracellular signaling cascades: Ca2+-dependent and PI3K-dependent, respectively. Thus, IL-6 production in response to UVA-induced ATP release involves at least two distinct pathways, mediated by activation of P2Y11 and P2Y13 receptors. PMID:26030257

Distinct cell stress responses induced by ATP restriction in quiescent human fibroblasts

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Nirupama Yalamanchili

2016-10-01

Full Text Available Quiescence is the prevailing state of many cell types under homeostatic conditions. Yet, surprisingly little is known about how quiescent cells respond to energetic and metabolic challenges. To better understand compensatory responses of quiescent cells to metabolic stress, we established, in human primary dermal fibroblasts, an experimental ‘energy restriction’ model. Quiescence was achieved by short-term culture in serum-deprived media and ATP supply restricted using a combination of glucose transport inhibitors and mitochondrial uncouplers. In aggregate, these measures led to markedly reduced intracellular ATP levels while not compromising cell viability over the observation period of 48 h. Analysis of the transcription factor landscape induced by this treatment revealed alterations in several signal transduction nodes beyond the expected biosynthetic adaptations. These included increased abundance of NF-κB regulated transcription factors and altered transcription factor subsets regulated by Akt and p53. The observed changes in gene regulation and corresponding alterations in key signaling nodes are likely to contribute to cell survival at intracellular ATP concentrations substantially below those achieved by growth factor deprivation alone. This experimental model provides a benchmark for the investigation of cell survival pathways and related molecular targets that are associated with restricted energy supply associated with biological aging and metabolic diseases.

Evaluation of hemodynamic effects of extracranial carotid stenoses by adenosine-induced vasodilatation in combination with 99mTc-HMPAO SPECT

International Nuclear Information System (INIS)

Ussov, V.Yu.; Plotnikov, M.P.; Yaroshevsky, S.P.; Shipulin, V.M.; Sokolov, AA.

1999-01-01

Methods: Adenosine was evaluated in combination with 99mTc-HMPAO SPECT as an intravenous agent for the pharmacological stress-test of the regional cerebral blood flow (rCBF) in 12 patients with internal carotid artery (ICA) stenosis without neurologic deficit (8 subjects) or with minimal deficit (4 subjects). Also, the adenosine-induced effects on rCBF were correlated with the anatomic severity of ICA stenosis. Six normal age-matched volunteers served as control. Results: The rest 99mTc-HMPAO SPECT data did not reveal any significant interhemispheric asymmetry of perfusion either in ICA stenosis patients or in control subjects. No interhemispheric asymmetry was observed in control subjects during adenosine infusion either. In ICA stenosis the adenosine test did induce interhemispheric asymmetry of perfusion, which ranged between 0.73 and 0.96 when quantified as an interhemispheric ratio of 99mTc-HMPAO uptake. In 5 of the 12 patients with ICA stenosis, adenosine also elicited a short - term muscular weakness and/or skin paresthesia consistent with cerebral location of the related cortical zones in the stenosis - dependent hemisphere. No correlation was noted between the interhemispheric anatomic planimetric asymmetry of stenosis (as ratio of patent ICA vessel lumen areas) and perfusion asymmetry at rest. The planimetric asymmetry of stenosis correlated significantly with the adenosine-induced asymmetry of rCBF in ICA - dependent areas (r = 0.78, p < 0.02). The correlation could be observed beginning from the magnitude of 70-75% relatively to the cross-sectional area of the contralateral intact vessel, equivalent to 45-50% decrease in the arterial diameter as compared to the intact artery. Conclusion: Therefore, the conclusion can be drawn that adenosine as a potent cerebral vasodilatator may be employed as a challenging agent for functional tests of rCBF and that the adenosine test facilitates detection of the hemodynamic effects of ''minor'' stenoses. (author)

Relationship of tightly bound ADP and ATP to control and catalysis by chloroplast ATP synthase

Energy Technology Data Exchange (ETDEWEB)

Zhou, J.; Xue, Z.; Du, Z.; Melese, T.; Boyer, P.D.

1988-07-12

Whether the tightly bound ADP that can cause a pronounced inhibition of ATP hydrolysis by the chloroplast ATP synthase and F/sub 1/ ATPase (CF/sub 1/) is bound at catalytic sites or at noncatalytic regulatory sites or both has been uncertain. The authors have used photolabeling by 2-azido-ATP and 2-azido-ADP to ascertain the location, with Mg/sup 2 +/ activation, of tightly bound ADP (a) that inhibits the hydrolysis of ATP by chloroplast ATP synthase, (b) that can result in an inhibited form of CF/sub 1/ that slowly regains activity during ATP hydrolysis, and (c) that arises when low concentrations of ADP markedly inhibit the hydrolysis of GTP by CF/sub 1/. The data show that in all instances the inhibition is associated with ADP binding without inorganic phosphate (P/sub i/) at catalytic sites. After photophosphorylation of ADP or 2-azido-ADP with (/sup 32/P)P/sub i/, similar amounts of the corresponding triphosphates are present on washed thylakoid membranes. Trials with appropriately labeled substrates show that a small portion of the tightly bound 2-azido-ATP gives rise to covalent labeling with an ATP moiety at noncatalytic sites but that most of the bound 2-azido-ATP gives rise to covalent labeling with an ATP moiety at noncatalytic sites but that most of the bound 2-azido-ATP gives rise to covalent labeling by an ADP moiety at a catalytic site. They also report the occurrence of a 1-2-min delay in the onset of the Mg/sup 2 +/-induced inhibition after addition of CF/sub 1/ to solutions containing Mg/sup 2 +/ and ATP, and that this delay is not associated with the filling of noncatalytic sites. A rapid burst of P/sub i/ formation is followed by a much lower, constant steady-state rate. The burst is not observed with GTP as a substrate or with Ca/sup 2 +/ as the activating cation.

Role of ATP-sensitive potassium channels in the piracetam induced blockade of opioid effects.

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Rehni, Ashish K; Singh, Nirmal; Jindal, Seema

2007-12-01

The present study has been designed to investigate the effect of piracetam on morphine/ buprenorphine-induced antinociception in rats and effect of piracetam on morphine or minoxidil induced relaxation in KCl-precontracted isolated rat aortic ring preparation. Nociceptive threshold was measured by the tail flick test in rats. The cumulative dose responses of morphine or minoxidil were recorded in KCl-precontracted isolated rat aortic ring preparation. Piracetam attenuated buprenorphine-induced antinociception in rats. Piracetam significantly reduced the morphine and minoxidil induced relaxation in KCl precontracted isolated rat aortic ring preparation suggesting that piracetam interferes with opioid receptor and ATP-sensitive potassium channel (KATP) opener mediated responses in vitro. Thus, it may be suggested that piracetam attenuates opioid effects by an opioid receptor-KATP channel linked mechanism.

Activation of eNOS by D-pinitol Induces an Endothelium-Dependent Vasodilatation in Mouse Mesenteric Artery

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Luciana N. Moreira

2018-05-01

Full Text Available D-pinitol is a cyclitol present in several edible plant species and extensively investigated for the treatment of metabolic diseases in humans, as food supplement, and demonstrated protective effects in the cardiovascular system. For these reasons, the present work aimed at investigating the mechanisms involved in the vascular effects of D-pinitol in mouse mesenteric artery. Mesenteric arteries from male C57BL/6 mice were mounted in a wire myograph. Nitrite was measured by the 2,3-diaminonaphthalene (DAN method. Protein expression and phosphorylation were measured by Western blot. The systolic blood pressure (SBP was measured by tail-cuff plethysmography. D-pinitol induced a concentration-dependent vasodilatation in endothelium-intact, but not in endothelium-denuded arteries. Nω-Nitro-L-arginine methyl ester (300 μM abolished the effect of D-pinitol, while 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μM shifted the concentration-response curve to the right. KN-93 (1 μM blunted the vasodilator effect of D-pinitol, but H-89 (0.1 μM did not change it. 1-[2-(Trifluoromethyl phenyl]imidazole (300 μM, indomethacin (10 μM, celecoxib (5 μM, wortmannin (1 μM, ruthenium red (10 μM, tiron (10 μM, MnTMPyP (30 μM, MPP (0.1 μM, PHTPP (0.1 μM, and atropine (1 μM did not change the effect of D-pinitol. D-pinitol increased the concentration of nitrite, which was inhibited by L-NAME and calmidazolium (10 μM. D-pinitol increased the phosphorylation level of eNOS activation site at Ser1177 and reduced the phosphorylation level of its inactivation site at Thr495. In normotensive mice, the intraperitoneal administration of D-pinitol (10 mg/kg induced a significant reduction of the SBP after 30 min. The present results led us to conclude that D-pinitol has an endothelium- and NO-dependent vasodilator effect in mouse mesenteric artery through a mechanism dependent on the activation of eNOS by the calcium-calmodulin complex, which can explain its

Renal epithelial cells can release ATP by vesicular fusion

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Randi G Bjaelde

2013-09-01

Full Text Available Renal epithelial cells have the ability to release nucleotides as paracrine factors. In the intercalated cells of the collecting duct, ATP is released by connexin30 (cx30, which is selectively expressed in this cell type. However, ATP is released by virtually all renal epithelia and the aim of the present study was to identify possible alternative nucleotide release pathways in a renal epithelial cell model. We used MDCK (type1 cells to screen for various potential ATP release pathways. In these cells, inhibition of the vesicular H+-ATPases (bafilomycin reduced both the spontaneous and hypotonically (80%-induced nucleotide release. Interference with vesicular fusion using N-ethylamide markedly reduced the spontaneous nucleotide release, as did interference with trafficking from the endoplasmic reticulum to the Golgi apparatus (brefeldin A1 and vesicular transport (nocodazole. These findings were substantiated using a siRNA directed against SNAP-23, which significantly reduced spontaneous ATP release. Inhibition of pannexin and connexins did not affect the spontaneous ATP release in this cell type, which consists of ∼90% principal cells. TIRF-microscopy of either fluorescently-labeled ATP (MANT-ATP or quinacrine-loaded vesicles, revealed that spontaneous release of single vesicles could be promoted by either hypoosmolality (50% or ionomycin. This vesicular release decreased the overall cellular fluorescence by 5.8% and 7.6% respectively. In summary, this study supports the notion that spontaneous and induced ATP release can occur via exocytosis in renal epithelial cells.

Bioanalytical Applications of Real-Time ATP Imaging Via Bioluminescence

Energy Technology Data Exchange (ETDEWEB)

Gruenhagen, Jason Alan [Iowa State Univ., Ames, IA (United States)

2003-01-01

The research discussed within involves the development of novel applications of real-time imaging of adenosine 5'-triphosphate (ATP). ATP was detected via bioluminescence and the firefly luciferase-catalyzed reaction of ATP and luciferin. The use of a microscope and an imaging detector allowed for spatially resolved quantitation of ATP release. Employing this method, applications in both biological and chemical systems were developed. First, the mechanism by which the compound 48/80 induces release of ATP from human umbilical vein endothelial cells (HUVECs) was investigated. Numerous enzyme activators and inhibitors were utilized to probe the second messenger systems involved in release. Compound 48/80 activated a G{sub q}-type protein to initiate ATP release from HUVECs. Ca²⁺ imaging along with ATP imaging revealed that activation of phospholipase C and induction of intracellular Ca²⁺ signaling were necessary for release of ATP. Furthermore, activation of protein kinase C inhibited the activity of phospholipase C and thus decreased the magnitude of ATP release. This novel release mechanism was compared to the existing theories of extracellular release of ATP. Bioluminescence imaging was also employed to examine the role of ATP in the field of neuroscience. The central nervous system (CNS) was dissected from the freshwater snail Lymnaea stagnalis. Electrophysiological experiments demonstrated that the neurons of the Lymnaea were not damaged by any of the components of the imaging solution. ATP was continuously released by the ganglia of the CNS for over eight hours and varied from ganglion to ganglion and within individual ganglia. Addition of the neurotransmitters K⁺ and serotonin increased release of ATP in certain regions of the Lymnaea CNS. Finally, the ATP imaging technique was investigated for the study of drug release systems. MCM-41-type mesoporous nanospheres were loaded with ATP and end-capped with mercaptoethanol

Inflammatory responses are not sufficient to cause delayed neuronal death in ATP-induced acute brain injury.

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Hey-Kyeong Jeong

Full Text Available BACKGROUND: Brain inflammation is accompanied by brain injury. However, it is controversial whether inflammatory responses are harmful or beneficial to neurons. Because many studies have been performed using cultured microglia and neurons, it has not been possible to assess the influence of multiple cell types and diverse factors that dynamically and continuously change in vivo. Furthermore, behavior of microglia and other inflammatory cells could have been overlooked since most studies have focused on neuronal death. Therefore, it is essential to analyze the precise roles of microglia and brain inflammation in the injured brain, and determine their contribution to neuronal damage in vivo from the onset of injury. METHODS AND FINDINGS: Acute neuronal damage was induced by stereotaxic injection of ATP into the substantia nigra pars compacta (SNpc and the cortex of the rat brain. Inflammatory responses and their effects on neuronal damage were investigated by immunohistochemistry, electron microscopy, quantitative RT-PCR, and stereological counting, etc. ATP acutely caused death of microglia as well as neurons in a similar area within 3 h. We defined as the core region the area where both TH(+ and Iba-1(+ cells acutely died, and as the penumbra the area surrounding the core where Iba-1(+ cells showed activated morphology. In the penumbra region, morphologically activated microglia arranged around the injury sites. Monocytes filled the damaged core after neurons and microglia died. Interestingly, neither activated microglia nor monocytes expressed iNOS, a major neurotoxic inflammatory mediator. Monocytes rather expressed CD68, a marker of phagocytic activity. Importantly, the total number of dopaminergic neurons in the SNpc at 3 h (∼80% of that in the contralateral side did not decrease further at 7 d. Similarly, in the cortex, ATP-induced neuron-damage area detected at 3 h did not increase for up to 7 d. CONCLUSIONS: Different cellular

Antihypertrophic Effects of Small Molecules that Maintain Mitochondrial ATP Levels Under Hypoxia

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Hiroaki Nagai

2017-10-01

Full Text Available Since impaired mitochondrial ATP production in cardiomyocytes is thought to lead to heart failure, a drug that protects mitochondria and improves ATP production under disease conditions would be an attractive treatment option. In this study, we identified small-molecule drugs, including the anti-parasitic agent, ivermectin, that maintain mitochondrial ATP levels under hypoxia in cardiomyocytes. Mechanistically, transcriptomic analysis and gene silencing experiments revealed that ivermectin increased mitochondrial ATP production by inducing Cox6a2, a subunit of the mitochondrial respiratory chain. Furthermore, ivermectin inhibited the hypertrophic response of human induced pluripotent stem cell-derived cardiomyocytes. Pharmacological inhibition of importin β, one of the targets of ivermectin, exhibited protection against mitochondrial ATP decline and cardiomyocyte hypertrophy. These findings indicate that maintaining mitochondrial ATP under hypoxia may prevent hypertrophy and improve cardiac function, providing therapeutic options for mitochondrial dysfunction.

Synergistic binding of glucose and aluminium ATP to hexokinase from Saccharomyces cerevisiae.

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Woolfitt, A R; Kellett, G L; Hoggett, J G

1988-08-10

The binding of glucose, AlATP and AlADP to the monomeric and dimeric forms of the native yeast hexokinase PII isoenzyme and to the proteolytically modified SII monomeric form was monitored at pH 6.7 by the concomitant quenching of intrinsic protein fluorescence. No fluorescence changes were observed when free enzyme was mixed with AlATP at concentrations up to 7500 microM. In the presence of saturating concentrations of glucose, the maximal quenching of fluorescence induced by AlATP was between 1.5 and 3.5% depending on species, and the average value of [L]0.5, the concentration of ligand at half-saturation, over all monomeric species was 0.9 +/- 0.4 microM. The presence of saturating concentrations of AlATP diminished [L]0.5 for glucose binding by between 260- and 670-fold for hexokinase PII and SII monomers, respectively (dependent on the ionic strength), and by almost 4000-fold for PII dimer. The data demonstrate extremely strong synergistic interactions in the binding of glucose and AlATP to yeast hexokinase, arising as a consequence of conformational changes in the free enzyme induced by glucose and in enzyme-glucose complex induced by AlATP. The synergistic interactions of glucose and AlATP are related to their kinetic synergism and to the ability of AlATP to act as a powerful inhibitor of the hexokinase reaction.

ATP7B detoxifies silver in ciliated airway epithelial cells

International Nuclear Information System (INIS)

Ibricevic, Aida; Brody, Steven L.; Youngs, Wiley J.; Cannon, Carolyn L.

2010-01-01

Silver is a centuries-old antibiotic agent currently used to treat infected burns. The sensitivity of a wide range of drug-resistant microorganisms to silver killing suggests that it may be useful for treating refractory lung infections. Toward this goal, we previously developed a methylated caffeine silver acetate compound, SCC1, that exhibits broad-spectrum antimicrobial activity against clinical strains of bacteria in vitro and when nebulized to lungs in mouse infection models. Preclinical testing of high concentrations of SCC1 in primary culture mouse tracheal epithelial cells (mTEC) showed selective ciliated cell death. Ciliated cell death was induced by both silver- and copper-containing compounds but not by the methylated caffeine portion of SCC1. We hypothesized that copper transporting P-type ATPases, ATP7A and ATP7B, play a role in silver detoxification in the airway. In mTEC, ATP7A was expressed in non-ciliated cells, whereas ATP7B was expressed only in ciliated cells. The exposure of mTEC to SCC1 induced the trafficking of ATP7B, but not ATP7A, suggesting the presence of a cell-specific silver uptake and detoxification mechanisms. Indeed, the expression of the copper uptake protein CTR1 was also restricted to ciliated cells. A role of ATP7B in silver detoxification was further substantiated when treatment of SCC1 significantly increased cell death in ATP7B shRNA-treated HepG2 cells. In addition, mTEC from ATP7B -/- mice showed enhanced loss of ciliated cells compared to wild type. These studies are the first to demonstrate a cell type-specific expression of the Ag + /Cu + transporters ATP7A, ATP7B, and CTR1 in airway epithelial cells and a role for ATP7B in detoxification of these metals in the lung.

Piezo1 regulates mechanotransductive release of ATP from human RBCs.

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Cinar, Eyup; Zhou, Sitong; DeCourcey, James; Wang, Yixuan; Waugh, Richard E; Wan, Jiandi

2015-09-22

Piezo proteins (Piezo1 and Piezo2) are recently identified mechanically activated cation channels in eukaryotic cells and associated with physiological responses to touch, pressure, and stretch. In particular, human RBCs express Piezo1 on their membranes, and mutations of Piezo1 have been linked to hereditary xerocytosis. To date, however, physiological functions of Piezo1 on normal RBCs remain poorly understood. Here, we show that Piezo1 regulates mechanotransductive release of ATP from human RBCs by controlling the shear-induced calcium (Ca(2+)) influx. We find that, in human RBCs treated with Piezo1 inhibitors or having mutant Piezo1 channels, the amounts of shear-induced ATP release and Ca(2+) influx decrease significantly. Remarkably, a critical extracellular Ca(2+) concentration is required to trigger significant ATP release, but membrane-associated ATP pools in RBCs also contribute to the release of ATP. Our results show how Piezo1 channels are likely to function in normal RBCs and suggest a previously unidentified mechanotransductive pathway in ATP release. Thus, we anticipate that the study will impact broadly on the research of red cells, cellular mechanosensing, and clinical studies related to red cell disorders and vascular disease.

The Methanolic Extract from Murraya koenigii L. Inhibits Glutamate-Induced Pain and Involves ATP-Sensitive K+ Channel as Antinociceptive Mechanism

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Nushrat Sharmin Ani

2016-01-01

Full Text Available Murraya koenigii L. is a perennial shrub, belonging to the family Rutaceae. Traditionally, the leaves of this plant are extensively used in treatment of a wide range of diseases and disorders including pain and inflammation. Although researchers have revealed the antinociceptive effects of this plant’s leaves during past few years, the mechanisms underlying these effects are still unknown. Therefore, the present study evaluated some antinociceptive mechanisms of the methanolic extract of M. koenigii (MEMK leaves along with its antinociceptive potential using several animal models. The antinociceptive effects of MEMK were evaluated using formalin-induced licking and acetic acid-induced writhing tests at the doses of 50, 100, and 200 mg/kg. In addition, we also justified the possible participations of glutamatergic system and ATP-sensitive potassium channels in the observed activities. Our results demonstrated that MEMK significantly (p<0.01 inhibited the pain thresholds induced by formalin and acetic acid in a dose-dependent manner. MEMK also significantly (p<0.01 suppressed glutamate-induced pain. Moreover, pretreatment with glibenclamide (an ATP-sensitive potassium channel blocker at 10 mg/kg significantly (p<0.05 reversed the MEMK-mediated antinociception. These revealed that MEMK might have the potential to interact with glutamatergic system and the ATP-sensitive potassium channels to exhibit its antinociceptive activities. Therefore, our results strongly support the antinociceptive effects of M. koenigii leaves and provide scientific basis of their analgesic uses in the traditional medicine.

Vasodilatation of afferent arterioles and paradoxical increase of renal vascular resistance by furosemide in mice

DEFF Research Database (Denmark)

Oppermann, Mona; Hansen, Pernille B; Castrop, Hayo

2007-01-01

Loop diuretics like furosemide have been shown to cause renal vasodilatation in dogs and humans, an effect thought to result from both a direct vascular dilator effect and from inhibition of tubuloglomerular feedback. In isolated perfused afferent arterioles preconstricted with angiotensin II or ...

N114S mutation causes loss of ATP-induced aggregation of human phosphoribosylpyrophosphate synthetase 1

International Nuclear Information System (INIS)

Liu Honglin; Peng, Xiaohui; Zhao Fang; Zhang Guobin; Tao Ye; Luo Zhaofeng; Li Yang; Teng Maikun; Li Xu; Wei Shiqiang

2009-01-01

This study examined recombinant wild-type human phosphoribosylpyrophosphate synthetase 1 (wt-PRS1, EC 2.7.6.1) and the point mutant Asn114Ser PRS1 (N114S-Mutant) in cells of a patient with primary gout. Dynamic light-scattering and sedimentation velocity experiments indicated that the monomeric wt-PRS1 in solution was assembled into hexamers after adding the substrate ATP. However, this ATP-induced aggregation effect was not observed with N114S-Mutant, which has a 50% higher enzymatic activity than that of wt-PRS1. Synchrotron radiation circular dichroism spectroscopy revealed that the point mutation causes an increase of α-helix content and a decrease of turn content. Examination of the crystal structure of wt-PRS1 indicated that 12 hydrogen bonds formed by 6 pairs of N114 and D139 have an important role in stabilizing the hexamer. We suggest that the substitution of S114 for N114 in N114S-Mutant leads to the rupture of 12 hydrogen bonds and breakage of the PO 4 3- allosteric site where PO 4 3- functions as a fixer of the ATP-binding loop. Therefore, we consider that formation of the hexamer as the structural basis of the ADP allosteric inhibition is greatly weakened by the N114S mutation, and that alteration of the ATP-binding loop conformation is the key factor in the increased activity of N114S-Mutant. These two factors could be responsible for the high level of activity of N114S-Mutant in this patient.

An ATP synthase harboring an atypical γ-subunit is involved in ATP synthesis in tomato fruit chromoplasts.

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Pateraki, Irini; Renato, Marta; Azcón-Bieto, Joaquín; Boronat, Albert

2013-04-01

Chromoplasts are non-photosynthetic plastids specialized in the synthesis and accumulation of carotenoids. During fruit ripening, chloroplasts differentiate into photosynthetically inactive chromoplasts in a process characterized by the degradation of the thylakoid membranes, and by the active synthesis and accumulation of carotenoids. This transition renders chromoplasts unable to photochemically synthesize ATP, and therefore these organelles need to obtain the ATP required for anabolic processes through alternative sources. It is widely accepted that the ATP used for biosynthetic processes in non-photosynthetic plastids is imported from the cytosol or is obtained through glycolysis. In this work, however, we show that isolated tomato (Solanum lycopersicum) fruit chromoplasts are able to synthesize ATP de novo through a respiratory pathway using NADPH as an electron donor. We also report the involvement of a plastidial ATP synthase harboring an atypical γ-subunit induced during ripening, which lacks the regulatory dithiol domain present in plant and algae chloroplast γ-subunits. Silencing of this atypical γ-subunit during fruit ripening impairs the capacity of isolated chromoplast to synthesize ATP de novo. We propose that the replacement of the γ-subunit present in tomato leaf and green fruit chloroplasts by the atypical γ-subunit lacking the dithiol domain during fruit ripening reflects evolutionary changes, which allow the operation of chromoplast ATP synthase under the particular physiological conditions found in this organelle. © 2013 The Authors The Plant Journal © 2013 Blackwell Publishing Ltd.

Effect of extraluminal ATP application on vascular tone and blood flow in skeletal muscle

DEFF Research Database (Denmark)

Nyberg, Michael Permin; Al-Khazraji, Baraa K; Mortensen, Stefan P

2013-01-01

During skeletal muscle contractions, the concentration of ATP increases in muscle interstitial fluid as measured by microdialysis probes. This increase is associated with the magnitude of blood flow, suggesting that interstitial ATP may be important for contraction-induced vasodilation. However...... studied. The rat gluteus maximus skeletal muscle model was used to study changes in local skeletal muscle hemodynamics. Superfused ATP at concentrations found during muscle contractions (1-10 µM) increased blood flow by up to 400%. In this model, the underlying mechanism was also examined by inhibition...... in interstitial ATP concentrations increases muscle blood flow, indicating that the contraction-induced increase in skeletal muscle interstitial [ATP] is important for exercise hyperemia. The vasodilator effect of ATP application is mediated by NO and prostanoid formation....

Mitochondrial ADP/ATP exchange inhibition: a novel off-target mechanism underlying ibipinabant-induced myotoxicity.

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Schirris, Tom J J; Ritschel, Tina; Herma Renkema, G; Willems, Peter H G M; Smeitink, Jan A M; Russel, Frans G M

2015-09-29

Cannabinoid receptor 1 (CB1R) antagonists appear to be promising drugs for the treatment of obesity, however, serious side effects have hampered their clinical application. Rimonabant, the first in class CB1R antagonist, was withdrawn from the market because of psychiatric side effects. This has led to the search for more peripherally restricted CB1R antagonists, one of which is ibipinabant. However, this 3,4-diarylpyrazoline derivative showed muscle toxicity in a pre-clinical dog study with mitochondrial dysfunction. Here, we studied the molecular mechanism by which ibipinabant induces mitochondrial toxicity. We observed a strong cytotoxic potency of ibipinabant in C2C12 myoblasts. Functional characterization of mitochondria revealed increased cellular reactive oxygen species generation and a decreased ATP production capacity, without effects on the catalytic activities of mitochondrial enzyme complexes I-V or the complex specific-driven oxygen consumption. Using in silico off-target prediction modelling, combined with in vitro validation in isolated mitochondria and mitoplasts, we identified adenine nucleotide translocase (ANT)-dependent mitochondrial ADP/ATP exchange as a novel molecular mechanism underlying ibipinabant-induced toxicity. Minor structural modification of ibipinabant could abolish ANT inhibition leading to a decreased cytotoxic potency, as observed with the ibipinabant derivative CB23. Our results will be instrumental in the development of new types of safer CB1R antagonists.

Glycine Receptor Activation Impairs ATP-Induced Calcium Transients in Cultured Cortical Astrocytes

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Tatiana P. Morais

2018-01-01

Full Text Available In central nervous system, glycine receptor (GlyR is mostly expressed in the spinal cord and brainstem, but glycinergic transmission related elements have also been identified in the brain. Astrocytes are active elements at the tripartite synapse, being responsible for the maintenance of brain homeostasis and for the fine-tuning of synaptic activity. These cells communicate, spontaneously or in response to a stimulus, by elevations in their cytosolic calcium (calcium transients, Ca2+T that can be propagated to other cells. How these Ca2+T are negatively modulated is yet poorly understood. In this work, we evaluated GlyR expression and its role on calcium signaling modulation in rat brain astrocytes. We first proved that GlyR, predominantly subunits α2 and β, was expressed in brain astrocytes and its localization was confirmed in the cytoplasm and astrocytic processes by immunohistochemistry assays. Calcium imaging experiments in cultured astrocytes showed that glycine (500 μM, a GlyR agonist, caused a concentration-dependent reduction in ATP-induced Ca2+T, an effect abolished by the GlyR antagonist, strychnine (0.8 μM, as well as by nocodazole (1 μM, known to impair GlyR anchorage to the plasma membrane. This effect was mimicked by activation of GABAAR, another Cl--permeable channel. In summary, we demonstrated that GlyR activation in astrocytes mediates an inhibitory effect upon ATP induced Ca2+T, which most probably involves changes in membrane permeability to Cl- and requires GlyR anchorage at the plasma membrane. GlyR in astrocytes may thus be part of a mechanism to modulate astrocyte-to-neuron communication.

Quantal release of ATP from clusters of PC12 cells.

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Fabbro, Alessandra; Skorinkin, Andrei; Grandolfo, Micaela; Nistri, Andrea; Giniatullin, Rashid

2004-10-15

Although ATP is important for intercellular communication, little is known about the mechanism of endogenous ATP release due to a dearth of suitable models. Using PC12 cells known to express the P2X2 subtype of ATP receptors and to store ATP with catecholamines inside dense-core vesicles, we found that clusters of PC12 cells cultured for 3-7 days generated small transient inward currents (STICs) after an inward current elicited by exogenous ATP. The amplitude of STICs in individual cells correlated with the peak amplitude of ATP-induced currents. STICs appeared as asynchronous responses (approximately 20 pA average amplitude) for 1-20 s and were investigated with a combination of patch clamping, Ca2+ imaging, biochemistry and electron microscopy. Comparable STICs were produced by focal KCl pulses and were dependent on extracellular Ca2+. STICs were abolished by the P2X antagonist PPADS and potentiated by Zn2+, suggesting they were mediated by P2X2 receptor activation. The highest probability of observing STICs was after the peak of intracellular Ca2+ increase caused by KCl. Biochemical measurements indicated that KCl application induced a significant release of ATP from PC12 cells. Electron microscopy studies showed narrow clefts without 'synaptic-like' densities between clustered cells. Our data suggest that STICs were caused by quantal release of endogenous ATP by depolarized PC12 cells in close juxtaposition to the recorded cell. Thus, STICs may be a new experimental model to characterize the physiology of vesicular release of ATP and to study the kinetics and pharmacology of P2X2 receptor-mediated quantal currents.

Inhibition of chemokine expression in rat inflamed paws by systemic use of the antihyperalgesic oxidized ATP

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Ticozzi Paolo

2005-07-01

Full Text Available Abstract Background We previously showed that local use of periodate oxidized ATP (oATP, a selective inhibitor of P2X7 receptors for ATP in rat paw treated with Freund's adjuvant induced a significant reduction of hyperalgesia Herein we investigate the role of oATP, in the rat paws inflamed by carrageenan, which mimics acute inflammation in humans. Results Local, oral or intravenous administration of a single dose of oATP significantly reduced thermal hyperalgesia in hind paws of rats for 24 hours, and such effect was greater than that induced by diclofenac or indomethacin. Following oATP treatment, the expression of the pro-inflammatory chemokines interferon-gamma-inducible protein-10 (IP-10, mon ocyte chemoattractant protein-1 (MCP-1 and interleukin-8 (IL-8 within the inflamed tissues markedly decreased on vessels and infiltrated cells. In parallel, the immunohistochemical findings showed an impairment, with respect to the untreated rats, in P2X7 expression, mainly on nerves and vessels close to the site of inflammation. Finally, oATP treatment significantly reduced the presence of infiltrating inflammatory macrophages in the paw tissue. Conclusion Taken together these results clearly show that oATP reduces carrageenan-induced inflammation in rats.

How the nucleus and mitochondria communicate in energy production during stress: nuclear MtATP6, an early-stress responsive gene, regulates the mitochondrial F₁F₀-ATP synthase complex.

Science.gov (United States)

Moghadam, Ali Asghar; Ebrahimie, Eemaeil; Taghavi, Seyed Mohsen; Niazi, Ali; Babgohari, Mahbobeh Zamani; Deihimi, Tahereh; Djavaheri, Mohammad; Ramezani, Amin

2013-07-01

A small number of stress-responsive genes, such as those of the mitochondrial F1F0-ATP synthase complex, are encoded by both the nucleus and mitochondria. The regulatory mechanism of these joint products is mysterious. The expression of 6-kDa subunit (MtATP6), a relatively uncharacterized nucleus-encoded subunit of F0 part, was measured during salinity stress in salt-tolerant and salt-sensitive cultivated wheat genotypes, as well as in the wild wheat genotypes, Triticum and Aegilops using qRT-PCR. The MtATP6 expression was suddenly induced 3 h after NaCl treatment in all genotypes, indicating an early inducible stress-responsive behavior. Promoter analysis showed that the MtATP6 promoter includes cis-acting elements such as ABRE, MYC, MYB, GTLs, and W-boxes, suggesting a role for this gene in abscisic acid-mediated signaling, energy metabolism, and stress response. It seems that 6-kDa subunit, as an early response gene and nuclear regulatory factor, translocates to mitochondria and completes the F1F0-ATP synthase complex to enhance ATP production and maintain ion homeostasis under stress conditions. These communications between nucleus and mitochondria are required for inducing mitochondrial responses to stress pathways. Dual targeting of 6-kDa subunit may comprise as a mean of inter-organelle communication and save energy for the cell. Interestingly, MtATP6 showed higher and longer expression in the salt-tolerant wheat and the wild genotypes compared to the salt-sensitive genotype. Apparently, salt-sensitive genotypes have lower ATP production efficiency and weaker energy management than wild genotypes; a stress tolerance mechanism that has not been transferred to cultivated genotypes.

ATP-induced conformational changes of nucleotide-binding domains in an ABC transporter. Importance of the water-mediated entropic force.

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Hayashi, Tomohiko; Chiba, Shuntaro; Kaneta, Yusuke; Furuta, Tadaomi; Sakurai, Minoru

2014-11-06

ATP binding cassette (ABC) proteins belong to a superfamily of active transporters. Recent experimental and computational studies have shown that binding of ATP to the nucleotide binding domains (NBDs) of ABC proteins drives the dimerization of NBDs, which, in turn, causes large conformational changes within the transmembrane domains (TMDs). To elucidate the active substrate transport mechanism of ABC proteins, it is first necessary to understand how the NBD dimerization is driven by ATP binding. In this study, we selected MalKs (NBDs of a maltose transporter) as a representative NBD and calculated the free-energy change upon dimerization using molecular mechanics calculations combined with a statistical thermodynamic theory of liquids, as well as a method to calculate the translational, rotational, and vibrational entropy change. This combined method is applied to a large number of snapshot structures obtained from molecular dynamics simulations containing explicit water molecules. The results suggest that the NBD dimerization proceeds with a large gain of water entropy when ATP molecules bind to the NBDs. The energetic gain arising from direct NBD-NBD interactions is canceled by the dehydration penalty and the configurational-entropy loss. ATP hydrolysis induces a loss of the shape complementarity between the NBDs, which leads to the dissociation of the dimer, due to a decrease in the water-entropy gain and an increase in the configurational-entropy loss. This interpretation of the NBD dimerization mechanism in concert with ATP, especially focused on the water-mediated entropy force, is potentially applicable to a wide variety of the ABC transporters.

Differential expression of ATP7A, ATP7B and CTR1 in adult rat dorsal root ganglion tissue

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Ip Virginia

2010-09-01

Full Text Available Abstract Background ATP7A, ATP7B and CTR1 are metal transporting proteins that control the cellular disposition of copper and platinum drugs, but their expression in dorsal root ganglion (DRG tissue and their role in platinum-induced neurotoxicity are unknown. To investigate the DRG expression of ATP7A, ATP7B and CTR1, lumbar DRG and reference tissues were collected for real time quantitative PCR, RT-PCR, immunohistochemistry and Western blot analysis from healthy control adult rats or from animals treated with intraperitoneal oxaliplatin (1.85 mg/kg or drug vehicle twice weekly for 8 weeks. Results In DRG tissue from healthy control animals, ATP7A mRNA was clearly detectable at levels similar to those found in the brain and spinal cord, and intense ATP7A immunoreactivity was localised to the cytoplasm of cell bodies of smaller DRG neurons without staining of satellite cells, nerve fibres or co-localisation with phosphorylated heavy neurofilament subunit (pNF-H. High levels of CTR1 mRNA were detected in all tissues from healthy control animals, and strong CTR1 immunoreactivity was associated with plasma membranes and vesicular cytoplasmic structures of the cell bodies of larger-sized DRG neurons without co-localization with ATP7A. DRG neurons with strong expression of ATP7A or CTR1 had distinct cell body size profiles with minimal overlap between them. Oxaliplatin treatment did not alter the size profile of strongly ATP7A-immunoreactive neurons but significantly reduced the size profile of strongly CTR1-immunoreactive neurons. ATP7B mRNA was barely detectable, and no specific immunoreactivity for ATP7B was found, in DRG tissue from healthy control animals. Conclusions In conclusion, adult rat DRG tissue exhibits a specific pattern of expression of copper transporters with distinct subsets of peripheral sensory neurons intensely expressing either ATP7A or CTR1, but not both or ATP7B. The neuron subtype-specific and largely non

N-Acetylcysteine-induced vasodilatation is modulated by KATP channels, Na+/K+-ATPase activity and intracellular calcium concentration: An in vitro study.

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Vezir, Özden; Çömelekoğlu, Ülkü; Sucu, Nehir; Yalın, Ali Erdinç; Yılmaz, Şakir Necat; Yalın, Serap; Söğüt, Fatma; Yaman, Selma; Kibar, Kezban; Akkapulu, Merih; Koç, Meryem İlkay; Seçer, Didem

2017-08-01

In this study, we aimed to investigate the role of ATP-sensitive potassium (K ATP ) channel, Na + /K + -ATPase activity, and intracellular calcium levels on the vasodilatory effect of N-acetylcysteine (NAC) in thoracic aorta by using electrophysiological and molecular techniques. Rat thoracic aorta ring preparations and cultured thoracic aorta cells were divided into four groups as control, 2mM NAC, 5mM NAC, and 10mM NAC. Thoracic aorta rings were isolated from rats for measurements of relaxation responses and Na + /K + -ATPase activity. In the cultured thoracic aorta cells, we measured the currents of K ATP channel, the concentration of intracellular calcium and mRNA expression level of K ATP channel subunits (KCNJ8, KCNJ11, ABCC8 and ABCC9). The relaxation rate significantly increased in all NAC groups compared to control. Similarly, Na + /K + - ATPase activity also significantly decreased in NAC groups. Outward K ATP channel current significantly increased in all NAC groups compared to the control group. Intracellular calcium concentration decreased significantly in all groups with compared control. mRNA expression level of ABCC8 subunit significantly increased in all NAC groups compared to the control group. Pearson correlation analysis showed that relaxation rate was significantly associated with K ATP current, intracellular calcium concentration, Na + /K + -ATPase activity and mRNA expression level of ABCC8 subunit. Our findings suggest that NAC relaxes vascular smooth muscle cells through a direct effect on K ATP channels, by increasing outward K+ flux, partly by increasing mRNA expression of K ATP subunit ABCC8, by decreasing in intracellular calcium and by decreasing in Na + /K + -ATPase activity. Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Excessive Extracellular ATP Desensitizes P2Y2 and P2X4 ATP Receptors Provoking Surfactant Impairment Ending in Ventilation-Induced Lung Injury

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Djo Hasan

2018-04-01

Full Text Available Stretching the alveolar epithelial type I (AT I cells controls the intercellular signaling for the exocytosis of surfactant by the AT II cells through the extracellular release of adenosine triphosphate (ATP (purinergic signaling. Extracellular ATP is cleared by extracellular ATPases, maintaining its homeostasis and enabling the lung to adapt the exocytosis of surfactant to the demand. Vigorous deformation of the AT I cells by high mechanical power ventilation causes a massive release of extracellular ATP beyond the clearance capacity of the extracellular ATPases. When extracellular ATP reaches levels >100 μM, the ATP receptors of the AT II cells become desensitized and surfactant impairment is initiated. The resulting alteration in viscoelastic properties and in alveolar opening and collapse time-constants leads to alveolar collapse and the redistribution of inspired air from the alveoli to the alveolar ducts, which become pathologically dilated. The collapsed alveoli connected to these dilated alveolar ducts are subject to a massive strain, exacerbating the ATP release. After reaching concentrations >300 μM extracellular ATP acts as a danger-associated molecular pattern, causing capillary leakage, alveolar space edema, and further deactivation of surfactant by serum proteins. Decreasing the tidal volume to 6 mL/kg or less at this stage cannot prevent further lung injury.

Vasomotor response to cold stimulation in human capsaicin-induced hyperalgesic area.

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Pud, Dorit; Andersen, Ole Kaeseler; Arendt-Nielsen, Lars; Eisenberg, Elon; Yarnitsky, David

2005-07-01

Cooling the skin induces sympathetically driven vasoconstriction, with some vasoparalytic dilatation at the lowest temperatures. Neurogenic inflammation, on the other hand, entails vasodilatation. In this study we investigated the balance between vasoconstriction and vasodilatation in an area of experimentally induced secondary hyperalgesia (2 degrees HA), in response to low-temperature stimulations. Fourteen healthy volunteers were exposed to three 30-s long cold stimuli (20, 10, and 0 degrees C) applied, at three adjacent sites, before (baseline) and 8 min after intradermal injection of 50 microg capsaicin to the volar forearm. The cold stimuli were applied distally to the injection site within the 2 degrees HA. Blood flux (BF) and skin temperatures were measured at four different regions (proximally, and distally to the capsaicin injection and at the 0, 10, and 20 degrees C thermode sites) all within the 2 degrees HA. The vascular measurements were conducted five times. Results showed a marked increase in BF after baseline cold stimulation (Peffect (elevated BF) was found following the capsaicin injection compared with baseline for all regions (Pcooled area was dilated by 450+/-5.1%; The vasoconstrictive effect for the 10 and 20 degrees C did not overcome the capsaicin vasodilatation, but did reduce it, with dilatation of 364+/-7.0% and 329+/-7.3%, respectively. For 0 degrees C, a dilatation of 407+/-6.5% was seen. It is concluded that in this experimental model, and potentially in the equivalent clinical syndromes, vasodilatation induced by the inflammation is only slightly reduced by cold stimulation such that it is still dominant, despite some cold-induced vasoconstriction.

Release of ATP from Marginal Cells in the Cochlea of Neonatal Rats Can Be Induced by Changes in Extracellular and Intracellular Ion Concentrations

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Peng, Yating; Chen, Jie; He, Shan; Yang, Jun; Wu, Hao

2012-01-01

Background Adenosine triphosphate (ATP) plays an important role in the cochlea. However, the source of ATP and the mechanism by which it is released remain unclear. This study investigates the presence and release mechanism of ATP in vitro cultured marginal cells isolated from the stria vascularis of the cochlea in neonatal rats. Methods Sprague-Dawley rats aged 1–3 days old were used for isolation, in vitro culture, and purification of marginal cells. Cultured marginal cells were verified by flow cytometry. Vesicles containing ATP in these cells were identified by fluorescence staining. The bioluminescence assay was used for determination of ATP concentration in the extracellular fluid released by marginal cells. Assays for ATP concentration were performed when the ATP metabolism of cells was influenced, and ionic concentrations in intracellular and extracellular fluid were found to change. Results Evaluation of cultured marginal cells with flow cytometry revealed the percentage of fluorescently-labeled cells as 92.9% and 81.9%, for cytokeratin and vimentin, respectively. Quinacrine staining under fluorescence microscopy revealed numerous green, star-like spots in the cytoplasm of these cells. The release of ATP from marginal cells was influenced by changes in the concentration of intracellular and extracellular ions, namely extracellular K+ and intra- and extracellular Ca2+. Furthermore, changes in the concentration of intracellular Ca2+ induced by the inhibition of the phospholipase signaling pathway also influence the release of ATP from marginal cells. Conclusion We confirmed the presence and release of ATP from marginal cells of the stria vascularis. This is the first study to demonstrate that the release of ATP from such cells is associated with the state of the calcium pump, K+ channel, and activity of enzymes related to the phosphoinositide signaling pathway, such as adenylate cyclase, phospholipase C, and phospholipase A2. PMID:23071731

Ca2+ influx and ATP release mediated by mechanical stretch in human lung fibroblasts

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Murata, Naohiko; Ito, Satoru; Furuya, Kishio; Takahara, Norihiro; Naruse, Keiji; Aso, Hiromichi; Kondo, Masashi; Sokabe, Masahiro; Hasegawa, Yoshinori

2014-01-01

Highlights: • Uniaxial stretching activates Ca 2+ signaling in human lung fibroblasts. • Stretch-induced intracellular Ca 2+ elevation is mainly via Ca 2+ influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca 2+ influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca 2+ concentration ([Ca 2+ ] i ) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca 2+ ] i transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca 2+ ] i . The stretch-induced [Ca 2+ ] i elevation was attenuated in Ca 2+ -free solution. In contrast, the increase of [Ca 2+ ] i by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd 3+ , ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca 2+ ] i elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca 2+ influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP

Mechanisms of constitutive and ATP-evoked ATP release in neonatal mouse olfactory epithelium

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Hayoz Sébastien

2012-05-01

Full Text Available Abstract Background ATP is an extracellular signaling molecule with many ascribed functions in sensory systems, including the olfactory epithelium. The mechanism(s by which ATP is released in the olfactory epithelium has not been investigated. Quantitative luciferin-luciferase assays were used to monitor ATP release, and confocal imaging of the fluorescent ATP marker quinacrine was used to monitor ATP release via exocytosis in Swiss Webster mouse neonatal olfactory epithelial slices. Results Under control conditions, constitutive release of ATP occurs via exocytosis, hemichannels and ABC transporters and is inhibited by vesicular fusion inhibitor Clostridium difficile toxin A and hemichannel and ABC transporter inhibitor probenecid. Constitutive ATP release is negatively regulated by the ATP breakdown product ADP through activation of P2Y receptors, likely via the cAMP/PKA pathway. In vivo studies indicate that constitutive ATP may play a role in neuronal homeostasis as inhibition of exocytosis inhibited normal proliferation in the OE. ATP-evoked ATP release is also present in mouse neonatal OE, triggered by several ionotropic P2X purinergic receptor agonists (ATP, αβMeATP and Bz-ATP and a G protein-coupled P2Y receptor agonist (UTP. Calcium imaging of P2X2-transfected HEK293 “biosensor” cells confirmed the presence of evoked ATP release. Following purinergic receptor stimulation, ATP is released via calcium-dependent exocytosis, activated P2X1,7 receptors, activated P2X7 receptors that form a complex with pannexin channels, or ABC transporters. The ATP-evoked ATP release is inhibited by the purinergic receptor inhibitor PPADS, Clostridium difficile toxin A and two inhibitors of pannexin channels: probenecid and carbenoxolone. Conclusions The constitutive release of ATP might be involved in normal cell turn-over or modulation of odorant sensitivity in physiological conditions. Given the growth-promoting effects of ATP, ATP-evoked ATP

Interaction of ATP with acid-denatured cytochrome c via coupled folding-binding mechanism

International Nuclear Information System (INIS)

Ahluwalia, Unnati; Deep, Shashank

2012-01-01

Highlights: ► Interaction between ATP and cyt c takes place via coupled binding–folding mechanism. ► Binding of ATP to cyt c is endothermic. ► GTP and CTP induce similar level of helicity in acid-denatured cyt c as with ATP. ► Compactness induced by ATP is far greater than ADP or AMP. - Abstract: The non-native conformations of the cytochrome c (cyt c) are believed to play key roles in a number of physiological processes. Nucleotides are supposed to act as allosteric effectors in these processes by regulating structural transitions among different conformations of cyt c. To understand the interaction between acid denatured cytochrome c and nucleotides, spectroscopic and calorimetric techniques were utilized to observe the structural features of the induced conformation and the energetics of interaction of acid denatured cyt c with different nucleotides. Structure induction in the acid denatured cyt c was observed on the addition of the ∼1 mM nucleotide tri-phosphates (ATP/GTP/CTP) at 25 °C, however, not in the presence of 1 mM nucleotide mono and diphosphates. ATP-bound cyt c at pH 2.0 is likely to have a conformation that has intact α-helical domain. However, Met80-Fe(III) axial bond is still ruptured. Observed thermodynamics reflect interaction between nucleotide and cyt c via coupled binding–folding mechanism. DSC data suggest the preferential binding of the ATP to the folded conformation with respect to the acid denatured cyt c. ITC data indicate that the exothermic folding of cyt c was accompanied by endothermic binding of ATP to cyt c.

Elevated levels of mitochonrial respiratory complexes activities and ATP production in 17-β-estradiol-induced prolactin-secretory tumor cells in male rats are inhibited by melatonin in vivo and in vitro.

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Wang, Bao-Qiang; Yang, Quan-Hui; Xu, Rong-Kun; Xu, Jian-Ning

2013-01-01

Our earlier studies indicate that melatonin inhibits the proliferation of prolactinoma and induces apoptosis of pituitary prolactin-secreting tumor in rats. Melatonin has also been shown to induce apoptosis and to reduce the production of ATP in breast tumor cells. This study analyzed the levels of the four mitochondrial respiratory complexes and the production of ATP and also the effects of melatonin treatment of prolactinoma. In the in vivo study, mitochondria were harvested from control pituitaries or prolactinoma collected from the pituitaries of melatonin- and 17-β-estradiol (E2)-treated male rats. In the in vitro study, prolactinoma cells mitochondria were harvested. Activities of the four mitochondrial respiratory complexes were assayed using fluorometer. ATP production of prolactinoma cells was estimated using bioluminescent methods. Elevated levels of four mitochondrial respiratory complexes activities and ATP production were recorded in prolactinoma cells. Moreover, in both in vivo and in vitro studies, melatonin inhibited the activities of mitochondrial respiratory complexes and the production of ATP in prolactinoma cells. There is a link between mitochondrial function increase and tumorigenesis. Melatonin induces apoptosis of pituitary prolactin-secreting tumor of rats via the induction of mitochondrial dysfunction and inhibition of energy metabolism.

ATP Release Channels

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Akiyuki Taruno

2018-03-01

Full Text Available Adenosine triphosphate (ATP has been well established as an important extracellular ligand of autocrine signaling, intercellular communication, and neurotransmission with numerous physiological and pathophysiological roles. In addition to the classical exocytosis, non-vesicular mechanisms of cellular ATP release have been demonstrated in many cell types. Although large and negatively charged ATP molecules cannot diffuse across the lipid bilayer of the plasma membrane, conductive ATP release from the cytosol into the extracellular space is possible through ATP-permeable channels. Such channels must possess two minimum qualifications for ATP permeation: anion permeability and a large ion-conducting pore. Currently, five groups of channels are acknowledged as ATP-release channels: connexin hemichannels, pannexin 1, calcium homeostasis modulator 1 (CALHM1, volume-regulated anion channels (VRACs, also known as volume-sensitive outwardly rectifying (VSOR anion channels, and maxi-anion channels (MACs. Recently, major breakthroughs have been made in the field by molecular identification of CALHM1 as the action potential-dependent ATP-release channel in taste bud cells, LRRC8s as components of VRACs, and SLCO2A1 as a core subunit of MACs. Here, the function and physiological roles of these five groups of ATP-release channels are summarized, along with a discussion on the future implications of understanding these channels.

Rapid tissue regeneration induced by intracellular ATP delivery-A preliminary mechanistic study.

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Harshini Sarojini

Full Text Available We have reported a new phenomenon in acute wound healing following the use of intracellular ATP delivery-extremely rapid tissue regeneration, which starts less than 24 h after surgery, and is accompanied by massive macrophage trafficking, in situ proliferation, and direct collagen production. This unusual process bypasses the formation of the traditional provisional extracellular matrix and significantly shortens the wound healing process. Although macrophages/monocytes are known to play a critical role in the initiation and progression of wound healing, their in situ proliferation and direct collagen production in wound healing have never been reported previously. We have explored these two very specific pathways during wound healing, while excluding confounding factors in the in vivo environment by analyzing wound samples and performing in vitro studies. The use of immunohistochemical studies enabled the detection of in situ macrophage proliferation in ATP-vesicle treated wounds. Primary human macrophages and Raw 264.7 cells were used for an in vitro study involving treatment with ATP vesicles, free Mg-ATP alone, lipid vesicles alone, Regranex, or culture medium. Collagen type 1α 1, MCP-1, IL-6, and IL-10 levels were determined by ELISA of the culture supernatant. The intracellular collagen type 1α1 localization was determined with immunocytochemistry. ATP-vesicle treated wounds showed high immunoreactivity towards BrdU and PCNA antigens, indicating in situ proliferation. Most of the cultured macrophages treated with ATP-vesicles maintained their classic phenotype and expressed high levels of collagen type 1α1 for a longer duration than was observed with cells treated with Regranex. These studies provide the first clear evidence of in situ macrophage proliferation and direct collagen production during wound healing. These findings provide part of the explanation for the extremely rapid tissue regeneration, and this treatment may hold

ATP stimulates calcium influx in primary astrocyte cultures

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Neary, J.T.; van Breemen, C.; Forster, E.; Norenberg, L.O.; Norenberg, M.D.

1988-01-01

The effect of ATP and other purines on 45 Ca uptake was studied in primary cultures of rat astrocytes. Treatment of the cells with ATP for 1 to 30 min brought about an increase in cellular 45 Ca. Stimulation of calcium influx by ATP was investigated using a 90 sec exposure to 45 Ca and over a concentration range of 0.1 nM to 3 mM; a biphasic dose-response curve was obtained with EC50 values of 0.3 nM and 9 uM, indicating the presence of low and high affinity purinergic binding sites. Similar levels of 45 Ca influx at 90 sec were observed with ATP, ADP and adenosine (all at 100 uM). Prior treatment of the cultures with LaCl3 blocked the purine-induced 45 Ca influx. These findings indicate that one pathway for calcium entry in astrocytes involves purinergic receptor-operated, calcium channels

Mutations in the Atp1p and Atp3p subunits of yeast ATP synthase differentially affect respiration and fermentation in Saccharomyces cerevisiae.

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Francis, Brian R; White, Karen H; Thorsness, Peter E

2007-04-01

ATP1-111, a suppressor of the slow-growth phenotype of yme1Delta lacking mitochondrial DNA is due to the substitution of phenylalanine for valine at position 111 of the alpha-subunit of mitochondrial ATP synthase (Atp1p in yeast). The suppressing activity of ATP1-111 requires intact beta (Atp2p) and gamma (Atp3p) subunits of mitochondrial ATP synthase, but not the stator stalk subunits b (Atp4p) and OSCP (Atp5p). ATP1-111 and other similarly suppressing mutations in ATP1 and ATP3 increase the growth rate of wild-type strains lacking mitochondrial DNA. These suppressing mutations decrease the growth rate of yeast containing an intact mitochondrial chromosome on media requiring oxidative phosphorylation, but not when grown on fermentable media. Measurement of chronological aging of yeast in culture reveals that ATP1 and ATP3 suppressor alleles in strains that contain mitochondrial DNA are longer lived than the isogenic wild-type strain. In contrast, the chronological life span of yeast cells lacking mitochondrial DNA and containing these mutations is shorter than that of the isogenic wild-type strain. Spore viability of strains bearing ATP1-111 is reduced compared to wild type, although ATP1-111 enhances the survival of spores that lacked mitochondrial DNA.

Extracellular ATP inhibits Schwann cell dedifferentiation and proliferation in an ex vivo model of Wallerian degeneration

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Shin, Youn Ho; Lee, Seo Jin; Jung, Junyang

2013-01-01

Highlights: ► ATP-treated sciatic explants shows the decreased expression of p75NGFR. ► Extracellular ATP inhibits the expression of phospho-ERK1/2. ► Lysosomal exocytosis is involved in Schwann cell dedifferentiation. ► Extracellular ATP blocks Schwann cell proliferation in sciatic explants. -- Abstract: After nerve injury, Schwann cells proliferate and revert to a phenotype that supports nerve regeneration. This phenotype-changing process can be viewed as Schwann cell dedifferentiation. Here, we investigated the role of extracellular ATP in Schwann cell dedifferentiation and proliferation during Wallerian degeneration. Using several markers of Schwann cell dedifferentiation and proliferation in sciatic explants, we found that extracellular ATP inhibits Schwann cell dedifferentiation and proliferation during Wallerian degeneration. Furthermore, the blockage of lysosomal exocytosis in ATP-treated sciatic explants is sufficient to induce Schwann cell dedifferentiation. Together, these findings suggest that ATP-induced lysosomal exocytosis may be involved in Schwann cell dedifferentiation.

Participation of the NO/cGMP/K+ATP pathway in the antinociception induced by Walker tumor bearing in rats

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Barbosa, A.L.R.; Pinheiro, C.A.; Oliveira, G.J.; Torres, J.N.L.; Moraes, M.O.; Ribeiro, R.A.; Vale, M.L.; Souza, M.H.L.P.

2012-01-01

Implantation of Walker 256 tumor decreases acute systemic inflammation in rats. Inflammatory hyperalgesia is one of the most important events of acute inflammation. The L-arginine/NO/cGMP/K + ATP pathway has been proposed as the mechanism of peripheral antinociception mediated by several drugs and physical exercise. The objective of this study was to investigate a possible involvement of the NO/cGMP/K + ATP pathway in antinociception induced in Walker 256 tumor-bearing male Wistar rats (180-220 g). The groups consisted of 5-6 animals. Mechanical inflammatory hypernociception was evaluated using an electronic version of the von Frey test. Walker tumor (4th and 7th day post-implantation) reduced prostaglandin E 2 - (PGE 2 , 400 ng/paw; 50 µL; intraplantar injection) and carrageenan-induced hypernociception (500 µg/paw; 100 µL; intraplantar injection). Walker tumor-induced analgesia was reversed (99.3% for carrageenan and 77.2% for PGE 2 ) by a selective inhibitor of nitric oxide synthase (L-NAME; 90 mg/kg, ip) and L-arginine (200 mg/kg, ip), which prevented (80% for carrageenan and 65% for PGE 2 ) the effect of L-NAME. Treatment with the soluble guanylyl cyclase inhibitor ODQ (100% for carrageenan and 95% for PGE 2 ; 8 µg/paw) and the ATP-sensitive K + channel (KATP) blocker glibenclamide (87.5% for carrageenan and 100% for PGE 2 ; 160 µg/paw) reversed the antinociceptive effect of tumor bearing in a statistically significant manner (P < 0.05). The present study confirmed an intrinsic peripheral antinociceptive effect of Walker tumor bearing in rats. This antinociceptive effect seemed to be mediated by activation of the NO/cGMP pathway followed by the opening of KATP channels

Air-Stimulated ATP Release from Keratinocytes Occurs through Connexin Hemichannels

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Barr, Travis P.; Albrecht, Phillip J.; Hou, Quanzhi; Mongin, Alexander A.; Strichartz, Gary R.; Rice, Frank L.

2013-01-01

Cutaneous ATP release plays an important role in both epidermal stratification and chronic pain, but little is known about ATP release mechanisms in keratinocytes that comprise the epidermis. In this study, we analyzed ATP release from cultured human neonatal keratinocytes briefly exposed to air, a process previously demonstrated to trigger ATP release from these cells. We show that exposing keratinocytes to air by removing media for 15 seconds causes a robust, long-lasting ATP release. This air-stimulated ATP release was increased in calcium differentiated cultures which showed a corresponding increase in connexin 43 mRNA, a major component of keratinocyte hemichannels. The known connexin hemichannel inhibitors 1-octanol and carbenoxolone both significantly reduced air-stimulated ATP release, as did two drugs traditionally used as ABC transporter inhibitors (glibenclamide and verapamil). These same 4 inhibitors also prevented an increase in the uptake of a connexin permeable dye induced by air exposure, confirming that connexin hemichannels are open during air-stimulated ATP release. In contrast, activity of the MDR1 ABC transporter was reduced by air exposure and the drugs that inhibited air-stimulated ATP release had differential effects on this transporter. These results indicate that air exposure elicits non-vesicular release of ATP from keratinocytes through connexin hemichannels and that drugs used to target connexin hemichannels and ABC transporters may cross-inhibit. Connexins represent a novel, peripheral target for the treatment of chronic pain and dermatological disease. PMID:23457608

Ca{sup 2+} influx and ATP release mediated by mechanical stretch in human lung fibroblasts

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Murata, Naohiko [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Ito, Satoru, E-mail: itori@med.nagoya-u.ac.jp [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Furuya, Kishio [Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Takahara, Norihiro [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Naruse, Keiji [Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Okayama 700-8558 (Japan); Aso, Hiromichi; Kondo, Masashi [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Sokabe, Masahiro [Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan); Hasegawa, Yoshinori [Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550 (Japan)

2014-10-10

Highlights: • Uniaxial stretching activates Ca{sup 2+} signaling in human lung fibroblasts. • Stretch-induced intracellular Ca{sup 2+} elevation is mainly via Ca{sup 2+} influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca{sup 2+} influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca{sup 2+} concentration ([Ca{sup 2+}]{sub i}) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca{sup 2+}]{sub i} transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca{sup 2+}]{sub i}. The stretch-induced [Ca{sup 2+}]{sub i} elevation was attenuated in Ca{sup 2+}-free solution. In contrast, the increase of [Ca{sup 2+}]{sub i} by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd{sup 3+}, ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca{sup 2+}]{sub i} elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca{sup 2+} influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP.

Excessive extracellular ATP desensitizes P2Y2 and P2X4 ATP receptors provoking surfactant impairment ending in ventilation-induced lung injury

NARCIS (Netherlands)

D. Hasan (Djo); Satalin, J. (Joshua); van der Zee, P. (Philip); Kollisch-Singule, M. (Michaela); P. Blankman (Paul); Shono, A. (Atsuko); P. Somhorst (Peter); C.A. den Uil (Corstiaan); H.J. Meeder (Han); Kotani, T. (Toru); G.F. Nieman (Gary F.)

2018-01-01

textabstractStretching the alveolar epithelial type I (AT I) cells controls the intercellular signaling for the exocytosis of surfactant by the AT II cells through the extracellular release of adenosine triphosphate (ATP) (purinergic signaling). Extracellular ATP is cleared by extracellular ATPases,

ATP Induces IL-1β Secretion in Neisseria gonorrhoeae-Infected Human Macrophages by a Mechanism Not Related to the NLRP3/ASC/Caspase-1 Axis

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Killen García

2016-01-01

Full Text Available Neisseria gonorrhoeae (Ngo has developed multiple immune evasion mechanisms involving the innate and adaptive immune responses. Recent findings have reported that Ngo reduces the IL-1β secretion of infected human monocyte-derived macrophages (MDM. Here, we investigate the role of adenosine triphosphate (ATP in production and release of IL-1β in Ngo-infected MDM. We found that the exposure of Ngo-infected MDM to ATP increases IL-1β levels about ten times compared with unexposed Ngo-infected MDM (P0.05 and caspase-1 (CASP1, P>0.05. In addition, ATP was not able to modify caspase-1 activity in Ngo-infected MDM but was able to increase pyroptosis (P>0.01. Notably ATP treatment defined an increase of positive staining for IL-1β with a distinctive intracellular pattern of distribution. Collectively, these data demonstrate that ATP induces IL-1β secretion by a mechanism not related to the NLRP3/ASC/caspase-1 axis and likely is acting at the level of vesicle trafficking or pore formation.

Liver ischemia and ischemia-reperfusion induces and trafficks the multi-specific metal transporter Atp7b to bile duct canaliculi: possible preferential transport of iron into bile.

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Goss, John A; Barshes, Neal R; Karpen, Saul J; Gao, Feng-Qin; Wyllie, Samuel

2008-04-01

Both Atp7b (Wilson disease gene) and Atp7a (Menkes disease gene) have been reported to be trafficked by copper. Atp7b is trafficked to the bile duct canaliculi and Atp7a to the plasma membrane. Whether or not liver ischemia or ischemia-reperfusion modulates Atp7b expression and trafficking has not been reported. In this study, we report for the first time that the multi-specific metal transporter Atp7b is significantly induced and trafficked by both liver ischemia alone and liver ischemia-reperfusion, as judged by immunohistochemistry and Western blot analyses. Although hepatocytes also stained for Atp7b, localized intense staining of Atp7b was found on bile duct canaliculi. Inductive coupled plasma-mass spectrometry analysis of bile copper, iron, zinc, and manganese found a corresponding significant increase in biliary iron. In our attempt to determine if the increased biliary iron transport observed may be a result of altered bile flow, lysosomal trafficking, or glutathione biliary transport, we measured bile flow, bile acid phosphatase activity, and glutathione content. No significant difference was found in bile flow, bile acid phosphatase activity, and glutathione, between control livers and livers subjected to ischemia-reperfusion. Thus, we conclude that liver ischemia and ischemia-reperfusion induction and trafficking Atp7b to the bile duct canaliculi may contribute to preferential iron transport into bile.

Bcl-2 protects against apoptosis induced by antimycin A and bongkrekic acid without restoring cellular ATP levels.

NARCIS (Netherlands)

Graaf, A.O. de; Meijerink, J.P.P.; Heuvel, L.P.W.J. van den; Abreu, R.A. de; Witte, T.J.M. de; Jansen, J.H.; Smeitink, J.A.M.

2002-01-01

Several studies indicate that mitochondrial ATP production as well as ADP/ATP exchange across mitochondrial membranes are impaired during apoptosis. We investigated whether Bcl-2 could protect against cell death under conditions in which ATP metabolism is inhibited. Inhibition of ATP production

A feasibility study of a new approach to clinical radiosensitisation: hypothermia and hyperbaric oxygen in combination with pharmacological vasodilatation

International Nuclear Information System (INIS)

Sealy, R.; Harrison, G.G.; Morrell, D.; Cape Town Univ.

1986-01-01

It is proposed that hyperbaric oxygen fails in the clinical situation due to a high proportion (greater than 33%) of hypoxic cells in human tumours. The means of overcoming this problem are reviewed. Additional to hyperbaric oxygenation, moderate hypothermia (30 0 C) to allow redistribution of oxygen in the tumour is proposed. A system of externally controlled intravenous anaesthesia has been developed for the single-subject hypervaric cylinder. Pharmacological vasodilatation is induced in the anaesthetised patient who is then fluid loaded and cooled. Initial single-sensitising treatments are advocated. Twenty-nine patients with advanced mouth cancer have completed a course of this treatment, of whom five of nine were free of disease after 2 years and 10 of 21 at 1 year, with three intercurrent deaths. Fifteen have experienced local failure. This approach would appear to be practical, safe and promising. (author)

ATP signals

DEFF Research Database (Denmark)

Novak, Ivana

2016-01-01

The Department of Biology at the University of Copenhagen explains the function of ATP signalling in the pancreas......The Department of Biology at the University of Copenhagen explains the function of ATP signalling in the pancreas...

Effect of hydrogen peroxide on the main kinetic parameters of ATP hydrolysis by ouabain sensitive Na+, K+-ATP-ase in spermatozoa of infertile men

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Р. В. Фафула

2017-12-01

Full Text Available Background: It is known that Na+,K+-ATP-ase plays important role in physiology of spermatozoa including their motility. Na+,K+-ATP-ase is one of the targets for reactive oxygen species. Hyperproduction of reactive oxygen species can damage sperm cells and it is considered to be as one of the mechanisms of male infertility. Objectives: To evaluate the H2O2 effect on the main kinetic parameters of ATP hydrolysis by ouabain-sensitive Na+,K+-ATPase of spermatozoa of fertile (normozoospermia and infertility men (asthenozoospermia. Materials and methods: Na+, K+-ATP-ase activity was determined spectrophotometrically by production of Pi. Concentration dependencies ware linearized in Lineweaver-Burk plot. Results: Effective inhibitory effect of H2O2 on ouabain-sensitive Na+,K+-ATP-ase activity of sperm cells of fertile and infertile men was demonstrated. The effects of H2O2 on the main kinetic parameters of the ATP hydrolysis with the involvement of Na+, K+-ATP-ase was studied. In the whole range of studied concentrations of ATP the Na+, K+-ATP-ase activity of spermatozoa of fertile and infertile men was reduced in the presence of H2O2 in the incubation medium. However, the optimal activity of the Na+, K+-ATP-ase activity of sperm cells in both normozoospermic and asthenozoospermic men was observed in the presence of 5 mM ATP in the incubation medium. By linearization of concentration curves in Lineweaver-Burk plot the main kinetic parameters of Na+, K+-activated, Mg2+-dependent ATP hydrolysis in the sperm cells of fertile and infertile men were determined. Under the effect of H2O2, the affinity constant of enzyme to ATP in normozoospermic and asthenozoospermic men increases several times. The initial maximum rate of ATP hydrolysis was significantly reduced only in the spermatozoa of fertile men with normozoospermia. Conclusions: Under conditions of H2O2-induced oxidative stress the inhibition of ouabain-sensitive Na+,K+-ATP-ase activity in sperm cells

Endothelium-dependent vasodilatation, plasma markers of endothelial function, and adrenergic vasoconstrictor responses in type 1 diabetes under near-normoglycemic conditions

NARCIS (Netherlands)

Huvers, F C; De Leeuw, P W; Houben, A J; De Haan, C H; Hamulyak, K; Schouten, H; Wolffenbuttel, B H; Schaper, N C

It is unknown whether and to what extent changes in various endothelial functions and adrenergic responsiveness are related to the development of microvascular complications in type 1 diabetes. Therefore, endothelium-dependent and endothelium-independent vasodilatation, endothelium-dependent

Up-regulated Ectonucleotidases in Fas-Associated Death Domain Protein- and Receptor-Interacting Protein Kinase 1-Deficient Jurkat Leukemia Cells Counteract Extracellular ATP/AMP Accumulation via Pannexin-1 Channels during Chemotherapeutic Drug-Induced Apoptosis.

Science.gov (United States)

Boyd-Tressler, Andrea M; Lane, Graham S; Dubyak, George R

2017-07-01

Pannexin-1 (Panx1) channels mediate the efflux of ATP and AMP from cancer cells in response to induction of extrinsic apoptosis by death receptors or intrinsic apoptosis by chemotherapeutic agents. We previously described the accumulation of extracellular ATP /AMP during chemotherapy-induced apoptosis in Jurkat human leukemia cells. In this study, we compared how different signaling pathways determine extracellular nucleotide pools in control Jurkat cells versus Jurkat lines that lack the Fas-associated death domain (FADD) or receptor-interacting protein kinase 1 (RIP1) cell death regulatory proteins. Tumor necrosis factor- α induced extrinsic apoptosis in control Jurkat cells and necroptosis in FADD-deficient cells; treatment of both lines with chemotherapeutic drugs elicited similar intrinsic apoptosis. Robust extracellular ATP/AMP accumulation was observed in the FADD-deficient cells during necroptosis, but not during apoptotic activation of Panx1 channels. Accumulation of extracellular ATP/AMP was similarly absent in RIP1-deficient Jurkat cells during apoptotic responses to chemotherapeutic agents. Apoptotic activation triggered equivalent proteolytic gating of Panx1 channels in all three Jurkat cell lines. The differences in extracellular ATP/AMP accumulation correlated with cell-line-specific expression of ectonucleotidases that metabolized the released ATP/AMP. CD73 mRNA, and α β -methylene-ADP-inhibitable ecto-AMPase activity were elevated in the FADD-deficient cells. In contrast, the RIP1-deficient cells were defined by increased expression of tartrate-sensitive prostatic acid phosphatase as a broadly acting ectonucleotidase. Thus, extracellular nucleotide accumulation during regulated tumor cell death involves interplay between ATP/AMP efflux pathways and different cell-autonomous ectonucleotidases. Differential expression of particular ectonucleotidases in tumor cell variants will determine whether chemotherapy-induced activation of Panx1 channels

ATP Release from Human Airway Epithelial Cells Exposed to Staphylococcus aureus Alpha-Toxin

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Romina Baaske

2016-12-01

Full Text Available Airway epithelial cells reduce cytosolic ATP content in response to treatment with S. aureus alpha-toxin (hemolysin A, Hla. This study was undertaken to investigate whether this is due to attenuated ATP generation or to release of ATP from the cytosol and extracellular ATP degradation by ecto-enzymes. Exposure of cells to rHla did result in mitochondrial calcium uptake and a moderate decline in mitochondrial membrane potential, indicating that ATP regeneration may have been attenuated. In addition, ATP may have left the cells through transmembrane pores formed by the toxin or through endogenous release channels (e.g., pannexins activated by cellular stress imposed on the cells by toxin exposure. Exposure of cells to an alpha-toxin mutant (H35L, which attaches to the host cell membrane but does not form transmembrane pores, did not induce ATP release from the cells. The Hla-mediated ATP-release was completely blocked by IB201, a cyclodextrin-inhibitor of the alpha-toxin pore, but was not at all affected by inhibitors of pannexin channels. These results indicate that, while exposure of cells to rHla may somewhat reduce ATP production and cellular ATP content, a portion of the remaining ATP is released to the extracellular space and degraded by ecto-enzymes. The release of ATP from the cells may occur directly through the transmembrane pores formed by alpha-toxin.

Light- induced electron transfer and ATP synthesis in a carotene synthesizing insect

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Valmalette, Jean Christophe; Dombrovsky, Aviv; Brat, Pierre; Mertz, Christian; Capovilla, Maria; Robichon, Alain

2012-08-01

A singular adaptive phenotype of a parthenogenetic insect species (Acyrthosiphon pisum) was selected in cold conditions and is characterized by a remarkable apparition of a greenish colour. The aphid pigments involve carotenoid genes well defined in chloroplasts and cyanobacteria and amazingly present in the aphid genome, likely by lateral transfer during evolution. The abundant carotenoid synthesis in aphids suggests strongly that a major and unknown physiological role is related to these compounds beyond their canonical anti-oxidant properties. We report here that the capture of light energy in living aphids results in the photo induced electron transfer from excited chromophores to acceptor molecules. The redox potentials of molecules involved in this process would be compatible with the reduction of the NAD+ coenzyme. This appears as an archaic photosynthetic system consisting of photo-emitted electrons that are in fine funnelled into the mitochondrial reducing power in order to synthesize ATP molecules.

Dioxin-induced acute cardiac mitochondrial oxidative damage and increased activity of ATP-sensitive potassium channels in Wistar rats

International Nuclear Information System (INIS)

Pereira, Susana P.; Pereira, Gonçalo C.; Pereira, Cláudia V.; Carvalho, Filipa S.; Cordeiro, Marília H.; Mota, Paula C.; Ramalho-Santos, João; Moreno, António J.; Oliveira, Paulo J.

2013-01-01

The environmental dioxin 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is classified as a Group 1 human carcinogen and teratogenic agent. We hypothesize that TCDD-induced oxidative stress may also interfere with mitochondrial ATP-sensitive potassium channels (mitoKATP), which are known to regulate and to be regulated by mitochondrial redox state. We investigated the effects of an acute treatment of male Wistar rats with TCDD (50 μg/kg i.p.) and measured the regulation of cardiac mitoKATP. While the function of cardiac mitochondria was slightly depressed, mitoKATP activity was 52% higher in animals treated with TCDD. The same effects were not observed in liver mitochondria isolated from the same animals. Our data also shows that regulation of mitochondrial ROS production by mitoKATP activity is different in both groups. To our knowledge, this is the first report to show that TCDD increases mitoKATP activity in the heart, which may counteract the increased oxidative stress caused by the dioxin during acute exposure. -- Highlights: •Acute TCDD treatment of Wistar rats causes cardiac oxidative stress. •Acute TCDD treatment causes cardiac mitochondrial alterations. •Mitochondrial liver vs. heart alterations are distinct. •TCDD treatment resulted in altered activity of cardiac mitochondrial K-ATP channels. -- Dioxin alters the regulation of cardiac mitochondrial ATP-sensitive potassium channels and disturbs mitochondrial physiology

Metal-dependent regulation of ATP7A and ATP7B in fibroblast cultures

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Lenartowicz Malgorzata

2016-08-01

Full Text Available Deficiency of one of the copper transporters ATP7A and ATP7B leads to the rare X-linked disorder Menkes Disease (MD or the rare autosomal disorder Wilson disease (WD, respectively. In order to investigate whether the ATP7A and the ATP7B genes may be transcriptionally regulated, we measured the expression level of the two genes at various concentrations of iron, copper and insulin. Treating fibroblasts from controls or from individuals with MD or WD for 3 and10 days with iron chelators revealed that iron deficiency led to increased transcript levels of both ATP7A and ATP7B. Copper deficiency obtained by treatment with the copper chelator led to a downregulation of ATP7A in the control fibroblasts, but surprisingly not in the WD fibroblasts. In contrast, the addition of copper led to an increased expression of ATP7A, but a decreased expression of ATP7B. Thus, whereas similar regulation patterns for the two genes were observed in response to iron deficiency, different responses were observed after changes in the access to copper. Mosaic fibroblast cultures from female carriers of MD treated with copper or copper chelator for 6-8 weeks led to clonal selection. Cells that express the normal ATP7A allele had a selective growth advantage at high copper concentrations, whereas more surprisingly, cells that express the mutant ATP7A allele had a selective growth advantage at low copper concentrations. Thus, although the transcription of ATP7A is regulated by copper, clonal growth selection in mosaic cell cultures is affected by the level of copper. Female carriers of MD are rarely affected probably due to a skewed inactivation of the X-chromosome bearing the ATP7A mutation.

In vivo inhibition of the mitochondrial H+-ATP synthase in neurons promotes metabolic preconditioning.

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Formentini, Laura; Pereira, Marta P; Sánchez-Cenizo, Laura; Santacatterina, Fulvio; Lucas, José J; Navarro, Carmen; Martínez-Serrano, Alberto; Cuezva, José M

2014-04-01

A key transducer in energy conservation and signaling cell death is the mitochondrial H(+)-ATP synthase. The expression of the ATPase inhibitory factor 1 (IF1) is a strategy used by cancer cells to inhibit the activity of the H(+)-ATP synthase to generate a ROS signal that switches on cellular programs of survival. We have generated a mouse model expressing a mutant of human IF1 in brain neurons to assess the role of the H(+)-ATP synthase in cell death in vivo. The expression of hIF1 inhibits the activity of oxidative phosphorylation and mediates the shift of neurons to an enhanced aerobic glycolysis. Metabolic reprogramming induces brain preconditioning affording protection against quinolinic acid-induced excitotoxicity. Mechanistically, preconditioning involves the activation of the Akt/p70S6K and PARP repair pathways and Bcl-xL protection from cell death. Overall, our findings provide the first in vivo evidence highlighting the H(+)-ATP synthase as a target to prevent neuronal cell death.

Roles of conserved arginines in ATP-binding domains of AAA+ chaperone ClpB from Thermus thermophilus.

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Yamasaki, Takashi; Nakazaki, Yosuke; Yoshida, Masasuke; Watanabe, Yo-hei

2011-07-01

ClpB, a member of the expanded superfamily of ATPases associated with diverse cellular activities (AAA+), forms a ring-shaped hexamer and cooperates with the DnaK chaperone system to reactivate aggregated proteins in an ATP-dependent manner. The ClpB protomer consists of an N-terminal domain, an AAA+ module (AAA-1), a middle domain, and a second AAA+ module (AAA-2). Each AAA+ module contains highly conserved WalkerA and WalkerB motifs, and two arginines (AAA-1) or one arginine (AAA-2). Here, we investigated the roles of these arginines (Arg322, Arg323, and Arg747) of ClpB from Thermus thermophilus in the ATPase cycle and chaperone function by alanine substitution. These mutations did not affect nucleotide binding, but did inhibit the hydrolysis of the bound ATP and slow the threading of the denatured protein through the central pore of the T. thermophilus ClpB ring, which severely impaired the chaperone functions. Previously, it was demonstrated that ATP binding to the AAA-1 module induced motion of the middle domain and stabilized the ClpB hexamer. However, the arginine mutations of the AAA-1 module destabilized the ClpB hexamer, even though ATP-induced motion of the middle domain was not affected. These results indicated that the three arginines are crucial for ATP hydrolysis and chaperone activity, but not for ATP binding. In addition, the two arginines in AAA-1 and the ATP-induced motion of the middle domain independently contribute to the stabilization of the hexamer. © 2011 The Authors Journal compilation © 2011 FEBS.

Role of hemolysis in red cell adenosine triphosphate release in simulated exercise conditions in vitro.

Science.gov (United States)

Mairbäurl, Heimo; Ruppe, Florian A; Bärtsch, Peter

2013-10-01

Specific adenosine triphosphate (ATP) release from red blood cells has been discussed as a possible mediator controlling microcirculation in states of decreased tissue oxygen. Because intravascular hemolysis might also contribute to plasma ATP, we tested in vitro which portion of ATP release is due to hemolysis in typical exercise-induced strains to the red blood cells (shear stress, deoxygenation, and lactic acidosis). Human erythrocytes were suspended in dextran-containing media (hematocrit 10%) and were exposed to shear stress in a rotating Couette viscometer at 37°C. Desaturation (oxygen saturation of hemoglobin ∼20%) was achieved by tonometry with N2 before shear stress exposure. Cells not exposed to shear stress were used as controls. Na lactate (15 mM), lactic acid (15 mM, pH 7.0), and HCl (pH 7.0) were added to simulate exercise-induced lactic acidosis. After incubation, extracellular hemoglobin was measured to quantify hemolysis. ATP was measured with the luciferase assay. Shear stress increased extracellular ATP in a stress-related and time-dependent manner. Hypoxia induced a ∼10-fold increase in extracellular ATP in nonsheared cells and shear stress-exposed cells. Lactic acid had no significant effect on ATP release and hemolysis. In normoxic cells, approximately 20%-50% of extracellular ATP was due to hemolysis. This proportion decreased to less than 10% in hypoxic cells. Our results indicate that when exposing red blood cells to typical strains they encounter when passing through capillaries of exercising skeletal muscle, ATP release from red blood cells is caused mainly by deoxygenation and shear stress, whereas lactic acidosis had only a minor effect. Hemolysis effects were decreased when hemoglobin was deoxygenated. Together, by specific release and hemolysis, extracellular ATP reaches values that have been shown to cause local vasodilatation.

Inhibition of myeloperoxidase decreases vascular oxidative stress and increases vasodilatation in sickle cell disease mice.

Science.gov (United States)

Zhang, Hao; Xu, Hao; Weihrauch, Dorothee; Jones, Deron W; Jing, Xigang; Shi, Yang; Gourlay, David; Oldham, Keith T; Hillery, Cheryl A; Pritchard, Kirkwood A

2013-11-01

Activated leukocytes and polymorphonuclear neutrophils (PMN) release myeloperoxidase (MPO), which binds to endothelial cells (EC), is translocated, and generates oxidants that scavenge nitric oxide (NO) and impair EC function. To determine whether MPO impairs EC function in sickle cell disease (SCD), control (AA) and SCD mice were treated with N-acetyl-lysyltyrosylcysteine-amide (KYC). SCD humans and mice have high plasma MPO and soluble L-selectin (sL-selectin). KYC had no effect on MPO but decreased plasma sL-selectin and malondialdehyde in SCD mice. MPO and 3-chlorotyrosine (3-ClTyr) were increased in SCD aortas. KYC decreased MPO and 3-ClTyr in SCD aortas to the levels in AA aortas. Vasodilatation in SCD mice was impaired. KYC increased vasodilatation in SCD mice more than 2-fold, to ∼60% of levels in AA mice. KYC inhibited MPO-dependent 3-ClTyr formation in EC proteins. SCD mice had high plasma alanine transaminase (ALT), which tended to decrease in KYC-treated SCD mice (P = 0.07). KYC increased MPO and XO/XDH and decreased 3-ClTyr and 3-nitrotyrosine (3-NO₂Tyr) in SCD livers. These data support the hypothesis that SCD increases release of MPO, which generates oxidants that impair EC function and injure livers. Inhibiting MPO is an effective strategy for decreasing oxidative stress and liver injury and restoring EC function in SCD.

Towards a multiscale description of microvascular flow regulation: O2-dependent release of ATP from human erythrocytes and the distribution of ATP in capillary networks

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Daniel eGoldman

2012-07-01

Full Text Available Integration of the numerous mechanisms that have been suggested to contribute to optimization of O2 supply to meet O2 need in skeletal muscle requires a systems biology approach which permits quantification of these physiological processes over a wide range of length scales. Here we describe two individual computational models based on in vivo and in vitro studies which, when incorporated into a single robust multiscale model, will provide information on the role of erythrocyte-released ATP in perfusion distribution in skeletal muscle under both physiological and pathophysiological conditions. Healthy human erythrocytes exposed to low O2 tension release ATP via a well characterized signaling pathway requiring activation of the G-protein, Gi, and adenylyl cyclase leading to increases in cAMP. This cAMP then activates PKA and subsequently CFTR culminating in ATP release via pannexin 1. A critical control point in this pathway is the level of cAMP which is regulated by pathway-specific phosphodiesterases. Using time constants (~100ms that are consistent with measured erythrocyte ATP release, we have constructed a dynamic model of this pathway. The model predicts levels of ATP release consistent with measurements obtained over a wide range of hemoglobin O2 saturations (sO2. The model further predicts how insulin, at concentrations found in prediabetes, enhances the activity of PDE3 and reduces intracellular cAMP levels leading to decreased low O2-induced ATP release from erythrocytes. The second model, which couples O2 and ATP transport in capillary networks, shows how intravascular ATP and the resulting conducted vasodilation are affected by local sO2, convection and ATP degradation. This model also predicts network-level effects of decreased ATP release resulting from elevated insulin levels. Taken together, these models lay the groundwork for investigating the systems biology of the regulation of microvascular perfusion distribution by

ATP-dependent human RISC assembly pathways.

Science.gov (United States)

Yoda, Mayuko; Kawamata, Tomoko; Paroo, Zain; Ye, Xuecheng; Iwasaki, Shintaro; Liu, Qinghua; Tomari, Yukihide

2010-01-01

The assembly of RNA-induced silencing complex (RISC) is a key process in small RNA-mediated gene silencing. In humans, small interfering RNAs (siRNAs) and microRNAs (miRNAs) are incorporated into RISCs containing the Argonaute (AGO) subfamily proteins Ago1-4. Previous studies have proposed that, unlike Drosophila melanogaster RISC assembly pathways, human RISC assembly is coupled with dicing and is independent of ATP. Here we show by careful reexamination that, in humans, RISC assembly and dicing are uncoupled, and ATP greatly facilitates RISC loading of small-RNA duplexes. Moreover, all four human AGO proteins show remarkably similar structural preferences for small-RNA duplexes: central mismatches promote RISC loading, and seed or 3'-mid (guide position 12-15) mismatches facilitate unwinding. All these features of human AGO proteins are highly reminiscent of fly Ago1 but not fly Ago2.

Effect of acute moderate exercise on induced inflammation and arterial function in older adults.

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Ranadive, Sushant Mohan; Kappus, Rebecca Marie; Cook, Marc D; Yan, Huimin; Lane, Abbi Danielle; Woods, Jeffrey A; Wilund, Kenneth R; Iwamoto, Gary; Vanar, Vishwas; Tandon, Rudhir; Fernhall, Bo

2014-04-01

Acute inflammation reduces flow-mediated vasodilatation and increases arterial stiffness in young healthy individuals. However, this response has not been studied in older adults. The aim of this study, therefore, was to evaluate the effect of acute induced systemic inflammation on endothelial function and wave reflection in older adults. Furthermore, an acute bout of moderate-intensity aerobic exercise can be anti-inflammatory. Taken together, we tested the hypothesis that acute moderate-intensity endurance exercise, immediately preceding induced inflammation, would be protective against the negative effects of acute systemic inflammation on vascular function. Fifty-nine healthy volunteers between 55 and 75 years of age were randomized to an exercise or a control group. Both groups received a vaccine (induced inflammation) and sham (saline) injection in a counterbalanced crossover design. Inflammatory markers, endothelial function (flow-mediated vasodilatation) and measures of wave reflection and arterial stiffness were evaluated at baseline and at 24 and 48 h after injections. There were no significant differences in endothelial function and arterial stiffness between the exercise and control group after induced inflammation. The groups were then analysed together, and we found significant differences in the inflammatory markers 24 and 48 h after induction of acute inflammation compared with sham injection. However, flow-mediated vasodilatation, augmentation index normalized for heart rate (AIx75) and β-stiffness did not change significantly. Our results suggest that acute inflammation induced by influenza vaccination did not affect endothelial function in older adults.

Conformational dynamics of ATP/Mg:ATP in motor proteins via data mining and molecular simulation

Science.gov (United States)

Bojovschi, A.; Liu, Ming S.; Sadus, Richard J.

2012-08-01

The conformational diversity of ATP/Mg:ATP in motor proteins was investigated using molecular dynamics and data mining. Adenosine triphosphate (ATP) conformations were found to be constrained mostly by inter cavity motifs in the motor proteins. It is demonstrated that ATP favors extended conformations in the tight pockets of motor proteins such as F1-ATPase and actin whereas compact structures are favored in motor proteins such as RNA polymerase and DNA helicase. The incorporation of Mg2+ leads to increased flexibility of ATP molecules. The differences in the conformational dynamics of ATP/Mg:ATP in various motor proteins was quantified by the radius of gyration. The relationship between the simulation results and those obtained by data mining of motor proteins available in the protein data bank is analyzed. The data mining analysis of motor proteins supports the conformational diversity of the phosphate group of ATP obtained computationally.

Extracellular ATP4- promotes cation fluxes in the J774 mouse macrophage cell line

International Nuclear Information System (INIS)

Steinberg, T.H.; Silverstein, S.C.

1987-01-01

Extracellular ATP stimulates transmembrane ion fluxes in the mouse macrophage cell line J774. In the presence of Mg2+, nonhydrolyzable ATP analogs and other purine and pyrimidine nucleotides do not elicit this response, suggesting the presence of a specific receptor for ATP on the macrophage plasma membrane. One candidate for such a receptor is the ecto-ATPase expressed on these cells. We, therefore, investigated the role of this enzyme in ATP-induced 86 Rb+ efflux in J774 cells. The ecto-ATPase had a broad nucleotide specificity and did not hydrolyze extracellular ATP in the absence of divalent cations. 86 Rb+ efflux was not blocked by inhibition of the ecto-ATPase and did not require Ca2+ or Mg2+. In fact, ATP-stimulated 86 Rb+ efflux was inhibited by Mg2+ and correlated with the availability of ATP4- in the medium. In the absence of divalent cations, the slowly hydrolyzable ATP analogs adenosine 5'-(beta, gamma-imido)triphosphate (AMP-PNP) and adenosine 5'-O-(3-thio)triphosphate (ATP-gamma-S) also stimulated 86 Rb+ efflux, albeit at higher concentrations than that required for ATP4-. Exposure of J774 cells to 10 mM ATP for 45 min caused death of 95% of cells. By this means we selected variant J774 cells that did not exhibit 86 Rb+ efflux in the presence of extracellular ATP but retained ecto-ATPase activity. These results show that the ecto-ATPase of J774 cells does not mediate the effects of ATP on these cells; that ATP4- and not MgATP2- promotes 86 Rb+ efflux from these cells; and that hydrolysis of ATP is not required to effect this change in membrane permeability. These findings suggest that J774 cells possess a plasma membrane receptor which binds ATP4-, AMP-PNP, and ATP-gamma-S, and that the ecto-ATPase limits the effects of ATP on these cells by hydrolyzing Mg-ATP2-

Disruption of Intracellular ATP Generation and Tight Junction Protein Expression during the Course of Brain Edema Induced by Subacute Poisoning of 1,2-Dichloroethane

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Gaoyang Wang

2018-01-01

Full Text Available The aim of this study was to explore changes in intracellular ATP generation and tight junction protein expression during the course of brain edema induced by subacute poisoning of 1,2-dichloroethane (1,2-DCE. Mice were exposed to 1.2 g/m3 1,2-DCE for 3.5 h per day for 1, 2, or 3 days, namely group A, B, and C. Na+-K+-ATPase and Ca2+-ATPase activity, ATP and lactic acid content, intracellular free Ca2+ concentration and ZO-1 and occludin expression in the brain were measured. Results of present study disclosed that Ca2+-ATPase activities in group B and C, and Na+/K+-ATPase activity in group C decreased, whereas intracellular free Ca2+ concentrations in group B and C increased significantly compared with control. Moreover, ATP content decreased, whereas lactic acid content increased significantly in group C compared with control. On the other hand, expressions of ZO-1 and occludin at both the protein and gene levels in group B and C decreased significantly compared with control. In conclusion, findings from this study suggest that calcium overload and depressed expression of tight junction associated proteins, such as ZO-1 and occludin might play an important role in the early phase of brain edema formation induced by subacute poisoning of 1,2-DCE.

Flow- and acetylcholine-induced dilation in small arteries from rats with renovascular hypertension - effect of tempol treatment

DEFF Research Database (Denmark)

Christensen, Frank Holden; Stankevicius, Edgaras; Hansen, Thomas

2007-01-01

-treated animals, while only the relaxation was improved by the NO donor, S-nitroso-N-acetylpenicillamine (SNAP). In conclusion renovascular hypertension selectively inhibits flow-induced NO-mediated vasodilatation, while EDHF-type vasodilatation remains unaffected, suggesting that high blood pressure leads...... blood pressure and tempol treatment. Simultaneous measurements of NO-concentration and relaxation were performed in isolated coronary arteries from the same animals. As compared to vehicle-treated rats, both acetylcholine-induced relaxation and NO-concentration increased in arteries from tempol......-induced dilatation remained normal. Measured by dihydroethidium staining there was an increased amount of superoxide in arteries from vehicle-treated rats, but not from tempol-treated rats. Expression by immunoblotting of endothelial NO synthase and the NAD(P)H oxidase subunit p47phox remained unaffected by high...

Muscle interstitial ATP and norepinephrine concentrations in the human leg during exercise and ATP infusion

DEFF Research Database (Denmark)

Mortensen, Stefan P.; Gonzalez-Alonso, Jose; Nielsen, Jens Jung

2009-01-01

ATP and NE concentrations to gain insight into the interstitial and intravascular mechanisms by which ATP causes muscle vasodilation and sympatholysis. Leg hemodynamics and muscle interstitial nucleotide and norepinephrine (NE) concentrations were measured during: 1) femoral arterial ATP infusion (0......, respectively (Pcontracting muscle (Pmuscle, whereas interstitial NE concentrations increased similarly in both active...... and inactive muscles. These results suggest that the vasodilatory and sympatholytic effects of intraluminal ATP are mainly mediated via endothelial prinergic receptors. Intraluminal ATP and muscle contractions appear to modulate sympathetic nerve activity by inhibiting the effect of NE rather than blunting its...

A label-free luminescent switch-on assay for ATP using a G-quadruplex-selective iridium(III) complex.

Science.gov (United States)

Leung, Ka-Ho; Lu, Lihua; Wang, Modi; Mak, Tsun-Yin; Chan, Daniel Shiu-Hin; Tang, Fung-Kit; Leung, Chung-Hang; Kwan, Hiu-Yee; Yu, Zhiling; Ma, Dik-Lung

2013-01-01

We report herein the G-quadruplex-selective property of a luminescent cyclometallated iridium(III) complex for the detection of adenosine-5'-triphosphate (ATP) in aqueous solution. The ATP-binding aptamer was employed as the ATP recognition unit, while the iridium(III) complex was used to monitor the formation of the G-quadruplex structure induced by ATP. The sensitivity and fold enhancement of the assay were higher than those of the previously reported assay using the organic dye crystal violet as a fluorescent probe. This label-free luminescent switch-on assay exhibits high sensitivity and selectivity towards ATP with a limit of detection of 2.5 µM.

A label-free luminescent switch-on assay for ATP using a G-quadruplex-selective iridium(III complex.

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Ka-Ho Leung

Full Text Available We report herein the G-quadruplex-selective property of a luminescent cyclometallated iridium(III complex for the detection of adenosine-5'-triphosphate (ATP in aqueous solution. The ATP-binding aptamer was employed as the ATP recognition unit, while the iridium(III complex was used to monitor the formation of the G-quadruplex structure induced by ATP. The sensitivity and fold enhancement of the assay were higher than those of the previously reported assay using the organic dye crystal violet as a fluorescent probe. This label-free luminescent switch-on assay exhibits high sensitivity and selectivity towards ATP with a limit of detection of 2.5 µM.

Extracellular ATP acts as a damage associated molecular pattern (DAMP signal in plants

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Kiwamu eTanaka

2014-09-01

Full Text Available As sessile organisms, plants have evolved effective mechanisms to protect themselves from environmental stresses. Damaged (i.e., wounded plants recognize a variety of endogenous molecules as danger signals, referred to as damage-associated molecular patterns (DAMPs. ATP is among the molecules that are released by cell damage, and recent evidence suggests that ATP can serve as a DAMP. Although little studied in plants, extracellular ATP is well known for its signaling role in animals, including acting as a DAMP during the inflammatory response and wound healing. If ATP acts outside the cell, then it is reasonable to expect that it is recognized by a plasma membrane-localized receptor. Recently, DORN1, a lectin receptor kinase, was shown to recognize extracellular ATP in Arabidopsis. DORN1 is the founding member of a new purinoceptor subfamily, P2K (P2 receptor Kinase, which is plant-specific. P2K1 (DORN1 is required for ATP-induced cellular responses (e.g., cytosolic Ca2+ elevation, MAPK phosphorylation, and gene expression. Genetic analysis of loss-of-function mutants and overexpression lines showed that P2K1 participates in the plant wound response, consistent with the role of ATP as a DAMP. In this review, we summarize past research on the roles and mechanisms of extracellular ATP signaling in plants, and discuss the direction of the future research of extracellular ATP as a DAMP signal.

ATP-modulated K+ channels sensitive to antidiabetic sulfonylureas are present in adenohypophysis and are involved in growth hormone release.

OpenAIRE

Bernardi, H; De Weille, J R; Epelbaum, J; Mourre, C; Amoroso, S; Slama, A; Fosset, M; Lazdunski, M

1993-01-01

The adenohypophysis contains high-affinity binding sites for antidiabetic sulfonylureas that are specific blockers of ATP-sensitive K+ channels. The binding protein has a M(r) of 145,000 +/- 5000. The presence of ATP-sensitive K+ channels (26 pS) has been demonstrated by electrophysiological techniques. Intracellular perfusion of adenohypophysis cells with an ATP-free medium to activate ATP-sensitive K+ channels induces a large hyperpolarization (approximately 30 mV) that is antagonized by an...

The ATP/DNA Ratio Is a Better Indicator of Islet Cell Viability Than the ADP/ATP Ratio

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Suszynski, T.M.; Wildey, G.M.; Falde, E.J.; Cline, G.W.; Maynard, K. Stewart; Ko, N.; Sotiris, J.; Naji, A.; Hering, B.J.; Papas, K.K.

2009-01-01

Real-time, accurate assessment of islet viability is critical for avoiding transplantation of nontherapeutic preparations. Measurements of the intracellular ADP/ATP ratio have been recently proposed as useful prospective estimates of islet cell viability and potency. However, dead cells may be rapidly depleted of both ATP and ADP, which would render the ratio incapable of accounting for dead cells. Since the DNA of dead cells is expected to remain stable over prolonged periods of time (days), we hypothesized that use of the ATP/DNA ratio would take into account dead cells and may be a better indicator of islet cell viability than the ADP/ATP ratio. We tested this hypothesis using mixtures of healthy and lethally heat-treated (HT) rat insulinoma cells and human islets. Measurements of ATP/DNA and ADP/ATP from the known mixtures of healthy and HT cells and islets were used to evaluate how well these parameters correlated with viability. The results indicated that ATP and ADP were rapidly (within 1 hour) depleted in HT cells. The fraction of HT cells in a mixture correlated linearly with the ATP/DNA ratio, whereas the ADP/ADP ratio was highly scattered, remaining effectively unchanged. Despite similar limitations in both ADP/ADP and ATP/DNA ratios, in that ATP levels may fluctuate significantly and reversibly with metabolic stress, the results indicated that ATP/DNA was a better measure of islet viability than the ADP/ATP ratio. PMID:18374063

Diltiazem Reduces Mortality and Breakdown of ATP in Red Blood Cell Induced by Isoproterenol in a Freely Moving Rat Model in Vivo

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Pollen K.F. Yeung

2014-09-01

Full Text Available The benefit of calcium channel blockers for cardiovascular prevention against heart attack and stroke has not been firmly supported. We investigated the possible cardiovascular protective effect of diltiazem (DTZ against injury induced by isoproterenol using a freely moving rat model in vivo. Sprague Dawley rats were injected subcutaneously (sc with either 5 or 10 mg/kg of DTZ, or saline as control, twice daily for five doses. One hour after the last injection, a single dose of isoproterenol (30 mg/kg was injected sc to each rat. Blood samples were collected serially for 6 h for measurement of adenine nucleotides (ATP, ADP and AMP in red blood cell (RBC by a validated HPLC. The study has shown isoproterenol induced 50% mortality and also increased RBC concentrations of AMP from 0.04 ± 0.02 to 0.29 ± 0.21 mM at the end of the experiment (p < 0.05. Treatment with 10 mg/kg of DTZ reduced mortality from 50% to <20% and attenuated the increase of RBC concentrations of AMP from +0.25 ± 0.22 in the control rats to +0.072 ± 0.092 mM (p < 0.05. The study concluded that 10 mg/kg of DTZ reduced mortality and breakdown of ATP induced by isoproterenol in rats.

ATP Modifies the Proteome of Extracellular Vesicles Released by Microglia and Influences Their Action on Astrocytes

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Francesco Drago

2017-12-01

Full Text Available Extracellular ATP is among molecules promoting microglia activation and inducing the release of extracellular vesicles (EVs, which are potent mediators of intercellular communication between microglia and the microenvironment. We previously showed that EVs produced under ATP stimulation (ATP-EVs propagate a robust inflammatory reaction among astrocytes and microglia in vitro and in mice with subclinical neuroinflammation (Verderio et al., 2012. However, the proteome of EVs released upon ATP stimulation has not yet been elucidated. In this study we applied a label free proteomic approach to characterize the proteome of EVs released constitutively and during microglia activation with ATP. We show that ATP drives sorting in EVs of a set of proteins implicated in cell adhesion/extracellular matrix organization, autophagy-lysosomal pathway and cellular metabolism, that may influence the response of recipient astrocytes to EVs. These data provide new clues to molecular mechanisms involved in microglia response to ATP and in microglia signaling to the environment via EVs.

Analysis of an ATP-induced conformational transition of ABC transporter MsbA using a coarse-grained model.

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Arai, Naoki; Furuta, Tadaomi; Sakurai, Minoru

2017-01-01

Upon the binding of ATP molecules to nucleotide binding domains (NBDs), ATP-binding cassette (ABC) exporters undergo a conformational transition from an inward-facing (IF) to an outward-facing (OF) state. This molecular event is a typical example of chemo-mechanical coupling. However, the underlying mechanism remains unclear. In this study, we analyzed the IF→OF transition of a representative ABC exporter, MsbA, by solving the equation of motion under an elastic network model (ENM). ATP was represented as a single node in ENM or replaced by external forces. When two ATP nodes were added to the ENM of the IF state protein, the two NBDs dimerized; subsequently, the two transmembrane domains opened toward the extracellular side, resulting in the formation of the OF structure. Such a conformational transition was also reproduced by applying external forces, which caused the rotational motion of the NBDs instead of the addition of ATP nodes. The process of the conformational transition was analyzed in detail using cross-correlation maps for node-node interactions. More importantly, it was revealed that the ATP binding energy is converted into distortion energy of several transmembrane helices. These results are useful for understanding the chemo-mechanical coupling in ABC transporters.

NFE2 Induces miR-423-5p to Promote Gluconeogenesis and Hyperglycemia by Repressing the Hepatic FAM3A-ATP-Akt Pathway.

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Yang, Weili; Wang, Junpei; Chen, Zhenzhen; Chen, Ji; Meng, Yuhong; Chen, Liming; Chang, Yongsheng; Geng, Bin; Sun, Libo; Dou, Lin; Li, Jian; Guan, Youfei; Cui, Qinghua; Yang, Jichun

2017-07-01

Hepatic FAM3A expression is repressed under obese conditions, but the underlying mechanism remains unknown. This study determined the role and mechanism of miR-423-5p in hepatic glucose and lipid metabolism by repressing FAM3A expression. miR-423-5p expression was increased in the livers of obese diabetic mice and in patients with nonalcoholic fatty liver disease (NAFLD) with decreased FAM3A expression. miR-423-5p directly targeted FAM3A mRNA to repress its expression and the FAM3A-ATP-Akt pathway in cultured hepatocytes. Hepatic miR-423-5p inhibition suppressed gluconeogenesis and improved insulin resistance, hyperglycemia, and fatty liver in obese diabetic mice. In contrast, hepatic miR-423-5p overexpression promoted gluconeogenesis and hyperglycemia and increased lipid deposition in normal mice. miR-423-5p inhibition activated the FAM3A-ATP-Akt pathway and repressed gluconeogenic and lipogenic gene expression in diabetic mouse livers. The miR-423 precursor gene was further shown to be a target gene of NFE2, which induced miR-423-5p expression to repress the FAM3A-ATP-Akt pathway in cultured hepatocytes. Hepatic NFE2 overexpression upregulated miR-423-5p to repress the FAM3A-ATP-Akt pathway, promoting gluconeogenesis and lipid deposition and causing hyperglycemia in normal mice. In conclusion, under the obese condition, activation of the hepatic NFE2/miR-423-5p axis plays important roles in the progression of type 2 diabetes and NAFLD by repressing the FAM3A-ATP-Akt signaling pathway. © 2017 by the American Diabetes Association.

Mitochondrial toxicity of diclofenac and its metabolites via inhibition of oxidative phosphorylation (ATP synthesis) in rat liver mitochondria: Possible role in drug induced liver injury (DILI).

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Syed, Muzeeb; Skonberg, Christian; Hansen, Steen Honoré

2016-03-01

Diclofenac is a widely prescribed NSAID, which by itself and its reactive metabolites (Phase-I and Phase-II) may be involved in serious idiosyncratic hepatotoxicity. Mitochondrial injury is one of the mechanisms of drug induced liver injury (DILI). In the present work, an investigation of the inhibitory effects of diclofenac (Dic) and its phase I [4-hydroxy diclofenac (4'-OH-Dic) and 5-hydroxy diclofenac (5-OH-dic)] and Phase-II [diclofenac acyl glucuronide (DicGluA) and diclofenac glutathione thioester (DicSG)] metabolites, on ATP synthesis in rat liver mitochondria was carried out. A mechanism based inhibition of ATP synthesis is exerted by diclofenac and its metabolites. Phase-I metabolite (4'-OH-Dic) and Phase-II metabolites (DicGluA and DicSG) showed potent inhibition (2-5 fold) of ATP synthesis, where as 5-OH-Dic, one of the Phase-I metabolite, was a less potent inhibitor as compared to Dic. The calculated kinetic constants of mechanism based inhibition of ATP synthesis by Dic showed maximal rate of inactivation (Kinact) of 2.64 ± 0.15 min(-1) and half maximal rate of inactivation (KI) of 7.69 ± 2.48 μM with Kinact/KI ratio of 0.343 min(-1) μM(-1). Co-incubation of mitochondria with Dic and reduced GSH exhibited a protective effect on Dic mediated inhibition of ATP synthesis. Our data from this study strongly indicate that Dic as well as its metabolites could be involved in the hepato-toxic action through inhibition of ATP synthesis. Copyright © 2015 Elsevier Ltd. All rights reserved.

ATP Maintenance via Two Types of ATP Regulators Mitigates Pathological Phenotypes in Mouse Models of Parkinson's Disease.

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Nakano, Masaki; Imamura, Hiromi; Sasaoka, Norio; Yamamoto, Masamichi; Uemura, Norihito; Shudo, Toshiyuki; Fuchigami, Tomohiro; Takahashi, Ryosuke; Kakizuka, Akira

2017-08-01

Parkinson's disease is assumed to be caused by mitochondrial dysfunction in the affected dopaminergic neurons in the brain. We have recently created small chemicals, KUSs (Kyoto University Substances), which can reduce cellular ATP consumption. By contrast, agonistic ligands of ERRs (estrogen receptor-related receptors) are expected to raise cellular ATP levels via enhancing ATP production. Here, we show that esculetin functions as an ERR agonist, and its addition to culture media enhances glycolysis and mitochondrial respiration, leading to elevated cellular ATP levels. Subsequently, we show the neuroprotective efficacies of KUSs, esculetin, and GSK4716 (an ERRγ agonist) against cell death in Parkinson's disease models. In the surviving neurons, ATP levels and expression levels of α-synuclein and CHOP (an ER stress-mediated cell death executor) were all rectified. We propose that maintenance of ATP levels, by inhibiting ATP consumption or enhancing ATP production, or both, would be a promising therapeutic strategy for Parkinson's disease. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

ATP Maintenance via Two Types of ATP Regulators Mitigates Pathological Phenotypes in Mouse Models of Parkinson's Disease

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Masaki Nakano

2017-08-01

Full Text Available Parkinson's disease is assumed to be caused by mitochondrial dysfunction in the affected dopaminergic neurons in the brain. We have recently created small chemicals, KUSs (Kyoto University Substances, which can reduce cellular ATP consumption. By contrast, agonistic ligands of ERRs (estrogen receptor-related receptors are expected to raise cellular ATP levels via enhancing ATP production. Here, we show that esculetin functions as an ERR agonist, and its addition to culture media enhances glycolysis and mitochondrial respiration, leading to elevated cellular ATP levels. Subsequently, we show the neuroprotective efficacies of KUSs, esculetin, and GSK4716 (an ERRγ agonist against cell death in Parkinson's disease models. In the surviving neurons, ATP levels and expression levels of α-synuclein and CHOP (an ER stress-mediated cell death executor were all rectified. We propose that maintenance of ATP levels, by inhibiting ATP consumption or enhancing ATP production, or both, would be a promising therapeutic strategy for Parkinson's disease.

Resistance of Akt kinases to dephosphorylation through ATP-dependent conformational plasticity.

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Chan, Tung O; Zhang, Jin; Rodeck, Ulrich; Pascal, John M; Armen, Roger S; Spring, Maureen; Dumitru, Calin D; Myers, Valerie; Li, Xue; Cheung, Joseph Y; Feldman, Arthur M

2011-11-15

Phosphorylation of a threonine residue (T308 in Akt1) in the activation loop of Akt kinases is a prerequisite for deregulated Akt activity frequently observed in neoplasia. Akt phosphorylation in vivo is balanced by the opposite activities of kinases and phosphatases. Here we describe that targeting Akt kinase to the cell membrane markedly reduced sensitivity of phosphorylated Akt to dephosphorylation by protein phosphatase 2A. This effect was amplified by occupancy of the ATP binding pocket by either ATP or ATP-competitive inhibitors. Mutational analysis revealed that R273 in Akt1 and the corresponding R274 in Akt2 are essential for shielding T308 in the activation loop against dephosphorylation. Thus, occupancy of the nucleotide binding pocket of Akt kinases enables intramolecular interactions that restrict phosphatase access and sustain Akt phosphorylation. This mechanism provides an explanation for the "paradoxical" Akt hyperphosphorylation induced by ATP-competitive inhibitor, A-443654. The lack of phosphatase resistance further contributes insight into the mechanism by which the human Akt2 R274H missense mutation may cause autosomal-dominant diabetes mellitus.

ATP Release from Chemotherapy-Treated Dying Leukemia Cells Elicits an Immune Suppressive Effect by Increasing Regulatory T Cells and Tolerogenic Dendritic Cells.

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Lecciso, Mariangela; Ocadlikova, Darina; Sangaletti, Sabina; Trabanelli, Sara; De Marchi, Elena; Orioli, Elisa; Pegoraro, Anna; Portararo, Paola; Jandus, Camilla; Bontadini, Andrea; Redavid, Annarita; Salvestrini, Valentina; Romero, Pedro; Colombo, Mario P; Di Virgilio, Francesco; Cavo, Michele; Adinolfi, Elena; Curti, Antonio

2017-01-01

Chemotherapy-induced immunogenic cell death can favor dendritic cell (DC) cross-priming of tumor-associated antigens for T cell activation thanks to the release of damage-associated molecular patterns, including ATP. Here, we tested the hypothesis that in acute myeloid leukemia (AML), ATP release, along with its well-known immune stimulatory effect, may also contribute to the generation of an immune suppressive microenvironment. In a cohort of AML patients, undergoing combined daunorubicin and cytarabine chemotherapy, a population of T regulatory cells (Tregs) with suppressive phenotype, expressing the immune checkpoint programmed cell death protein 1 (PD-1), was significantly increased. Moving from these results, initial in vitro data showed that daunorubicin was more effective than cytarabine in modulating DC function toward Tregs induction and such difference was correlated with the higher capacity of daunorubicin to induce ATP release from treated AML cells. DCs cultured with daunorubicin-treated AML cells upregulated indoleamine 2,3-dioxygenase 1 (IDO1), which induced anti-leukemia Tregs. These data were confirmed in vivo as daunorubicin-treated mice show an increase in extracellular ATP levels with increased number of Tregs, expressing PD-1 and IDO1 + CD39 + DCs. Notably, daunorubicin failed to induce Tregs and tolerogenic DCs in mice lacking the ATP receptor P2X7. Our data indicate that ATP release from chemotherapy-treated dying cells contributes to create an immune suppressive microenvironment in AML.

H+/ATP ratio during ATP hydrolysis by mitochondria: modification of the chemiosmotic theory.

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Brand, M D; Lehninger, A L

1977-01-01

The stoichiometry of H+ ejection by mitochondria during hydrolysis of a small pulse of ATP (the H+/ATP ratio) has been reexamined in the light of our recent observation that the stoichiometry of H+ ejection during mitochondrial electron transport (the H+/site ratio) was previously underestimated. We show that earlier estimates of the H+/ATP ratio in intact mitochondria were based upon an invalid correction for scaler H+ production and describe a modified method for determination of this ratio which utilizes mersalyl or N-ethylmaleimide to prevent complicating transmembrane movements of phosphate and H+. This method gives a value for the H+/ATP ratio of 2.0 without the need for questionable corrections, compared with a value of 3.0 for the H+/site ratio also obtained by pulse methods. A modified version of the chemiosmotic theory is presented, in which 3 H+ are ejected per pair of electrons traversing each energy-conserving site of the respiratory chain. Of these, 2 H+ return to the matrix through the ATPase to form ATP from ADP and phosphate, and 1 H+ returns through the combined action of the phosphate and adenine nucleotide exchange carriers of the inner membrane to allow the energy-requiring influx of Pi and ADP3- and efflux of ATP4-. Thus, up to one-third of the energy input into synthesis of extramitochondrial ATP may be required for transport work. Since other methods suggest that the H+/site significantly exceeds 3.0, an alternative possibility is that 4 h+ are ejected per site, followed by return of 3 H+ through the ATPase and 1 H+ through the operation of the proton-coupled membrane transport systems. PMID:17116

HBCDD-induced sustained reduction in mitochondrial membrane potential, ATP and steroidogenesis in peripubertal rat Leydig cells

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Fa, Svetlana; Pogrmic-Majkic, Kristina; Samardzija, Dragana; Hrubik, Jelena; Glisic, Branka; Kovacevic, Radmila; Andric, Nebojsa, E-mail: nebojsa.andric@dbe.uns.ac.rs

2015-01-01

Hexabromocyclododecane (HBCDD), a brominated flame retardant added to various consumer products, is a ubiquitous environmental contaminant. We have previously shown that 6-hour exposure to HBCDD disturbs basal and human chorionic gonadotropin (hCG)-induced steroidogenesis in rat Leydig cells. Reduction in mitochondrial membrane potential (ΔΨm) and cAMP production was also observed. Here, we further expanded research on the effect of HBCDD on Leydig cells by using a prolonged exposure scenario. Cells were incubated in the presence of HBCDD during 24 h and then treated with HBCDD + hCG for additional 2 h. Results showed that HBCDD caused a sustained reduction in ATP level after 24 h of exposure, which persisted after additional 2-hour treatment with HBCDD + hCG. cAMP and androgen accumulations measured after 2 h of HBCDD + hCG treatment were also inhibited. Real-time PCR analysis showed significant inhibition in the expression of genes for steroidogenic enzymes, luteinizing hormone receptor, regulatory and transport proteins, and several transcription factors under both treatment conditions. Western blot analysis revealed a decreased level of 30 kDa steroidogenic acute regulatory protein (StAR) after HBCDD + hCG treatment. In addition, HBCDD decreased the conversion of 22-OH cholesterol to pregnenolone and androstenedione to testosterone, indicating loss of the activity of cytochrome P450C11A1 (CYP11A1) and 17β-hydroxysteroid dehydrogenase (HSD17β). Cell survival was not affected, as confirmed by cytotoxicity and trypan blue tests or DNA fragmentation analysis. In summary, our data showed that HBCDD inhibits ATP supply, most likely through a decrease in ΔΨm, and targets multiple sites in the steroidogenic pathway in Leydig cells. - Highlights: • HBCDD causes a sustained reduction in ΔΨm and ATP level in Leydig cells. • Prolonged HBCDD exposure decreases hCG-supported steroidogenesis in Leydig cells. • HBCDD targets StAR, HSD17β and CYP11A1 in Leydig

HBCDD-induced sustained reduction in mitochondrial membrane potential, ATP and steroidogenesis in peripubertal rat Leydig cells

International Nuclear Information System (INIS)

Fa, Svetlana; Pogrmic-Majkic, Kristina; Samardzija, Dragana; Hrubik, Jelena; Glisic, Branka; Kovacevic, Radmila; Andric, Nebojsa

2015-01-01

Hexabromocyclododecane (HBCDD), a brominated flame retardant added to various consumer products, is a ubiquitous environmental contaminant. We have previously shown that 6-hour exposure to HBCDD disturbs basal and human chorionic gonadotropin (hCG)-induced steroidogenesis in rat Leydig cells. Reduction in mitochondrial membrane potential (ΔΨm) and cAMP production was also observed. Here, we further expanded research on the effect of HBCDD on Leydig cells by using a prolonged exposure scenario. Cells were incubated in the presence of HBCDD during 24 h and then treated with HBCDD + hCG for additional 2 h. Results showed that HBCDD caused a sustained reduction in ATP level after 24 h of exposure, which persisted after additional 2-hour treatment with HBCDD + hCG. cAMP and androgen accumulations measured after 2 h of HBCDD + hCG treatment were also inhibited. Real-time PCR analysis showed significant inhibition in the expression of genes for steroidogenic enzymes, luteinizing hormone receptor, regulatory and transport proteins, and several transcription factors under both treatment conditions. Western blot analysis revealed a decreased level of 30 kDa steroidogenic acute regulatory protein (StAR) after HBCDD + hCG treatment. In addition, HBCDD decreased the conversion of 22-OH cholesterol to pregnenolone and androstenedione to testosterone, indicating loss of the activity of cytochrome P450C11A1 (CYP11A1) and 17β-hydroxysteroid dehydrogenase (HSD17β). Cell survival was not affected, as confirmed by cytotoxicity and trypan blue tests or DNA fragmentation analysis. In summary, our data showed that HBCDD inhibits ATP supply, most likely through a decrease in ΔΨm, and targets multiple sites in the steroidogenic pathway in Leydig cells. - Highlights: • HBCDD causes a sustained reduction in ΔΨm and ATP level in Leydig cells. • Prolonged HBCDD exposure decreases hCG-supported steroidogenesis in Leydig cells. • HBCDD targets StAR, HSD17β and CYP11A1 in Leydig

Journey in guidelines for lipid management: From adult treatment panel (ATP-I to ATP-III and what to expect in ATP-IV

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P G Talwalkar

2013-01-01

Full Text Available Adult Treatment Panel (ATP, an expert panel to supervise cholesterol management was set up under the aegis of National Cholesterol Education Program (NCEP in 1985. Since then NCEP-ATP has been revising and framing guidelines to enable clinician to deliver better treatment to cardiovascular patients and to educate general people. As a result, considerable reduction in cardiovascular related deaths has been observed in recent times. All three ATP guidelines viz. ATP-I, ATP-II and ATP-III have targeted low density lipoprotein as their primary goal. The ATP-III guideline was updated in the light of evidences from 5-major clinical trials and was released in 2004. It added therapeutic lifestyle changes, concept of risk equivalents, Framingham CHD-risk score non-high density lipoprotein cholesterol (non-HDL-C as secondary target and gave strong emphasis on metabolic risk factors. The earlier treat-to-target paradigm faced fierce criticism from clinicians across the globe because of insufficient proof of safety and benefits of treating patients with respect to an individual′s low density lipoprotein (LDL level. Further, demonstration of non-HDL-C and total cholesterol/HDL-C ratio as strong predictors of overall cardiovascular risk foresees new guidelines. A tailored-treatment approach was suggested instead of LDL-C target based treatment approach which was soundly based on direct clinical trials evidences and proposes treatment based on individual′s overall 5- to 10-year cardiovascular risk irrespective of LDL-C level, leading to lower number of people on high dose/s of statins. Recent report of the Cholesterol Treatment Trialist′s Collaborators meta-analysis strongly supported primary prevention of LDL with statins in low risk individuals and showed that its benefits completely outweighed its known hazards. Markers other than LDL-C like apolipoprotein B, non-HDL-C and total cholesterol/HDL-C ratio would take precedence in the risk assessment and

The ATP required for potentiation of skeletal muscle contraction is released via pannexin hemichannels.

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Riquelme, Manuel A; Cea, Luis A; Vega, José L; Boric, Mauricio P; Monyer, Hannah; Bennett, Michael V L; Frank, Marina; Willecke, Klaus; Sáez, Juan C

2013-12-01

During repetitive stimulation of skeletal muscle, extracellular ATP levels raise, activating purinergic receptors, increasing Ca2+ influx, and enhancing contractile force, a response called potentiation. We found that ATP appears to be released through pannexin1 hemichannels (Panx1 HCs). Immunocytochemical analyses and function were consistent with pannexin1 localization to T-tubules intercalated with dihydropyridine and ryanodine receptors in slow (soleus) and fast (extensor digitorum longus, EDL) muscles. Isolated myofibers took up ethidium (Etd+) and released small molecules (as ATP) during electrical stimulation. Consistent with two glucose uptake pathways, induced uptake of 2-NBDG, a fluorescent glucose derivative, was decreased by inhibition of HCs or glucose transporter (GLUT4), and blocked by dual blockade. Adult skeletal muscles apparently do not express connexins, making it unlikely that connexin hemichannels contribute to the uptake and release of small molecules. ATP release, Etd+ uptake, and potentiation induced by repetitive electrical stimulation were blocked by HC blockers and did not occur in muscles of pannexin1 knockout mice. MRS2179, a P2Y1R blocker, prevented potentiation in EDL, but not soleus muscles, suggesting that in fast muscles ATP activates P2Y1 but not P2X receptors. Phosphorylation on Ser and Thr residues of pannexin1 was increased during potentiation, possibly mediating HC opening. Opening of Panx1 HCs during repetitive activation allows efflux of ATP, influx of glucose and possibly Ca2+ too, which are required for potentiation of contraction. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'. Copyright © 2013 Elsevier Ltd. All rights reserved.

An autocrine ATP release mechanism regulates basal ciliary activity in airway epithelium.

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Droguett, Karla; Rios, Mariana; Carreño, Daniela V; Navarrete, Camilo; Fuentes, Christian; Villalón, Manuel; Barrera, Nelson P

2017-07-15

Extracellular ATP, in association with [Ca 2+ ] i regulation, is required to maintain basal ciliary beat frequency. Increasing extracellular ATP levels increases ciliary beating in airway epithelial cells, maintaining a sustained response by inducing the release of additional ATP. Extracellular ATP levels in the millimolar range, previously associated with pathophysiological conditions of the airway epithelium, produce a transient arrest of ciliary activity. The regulation of ciliary beat frequency is dependent on ATP release by hemichannels (connexin/pannexin) and P2X receptor activation, the blockage of which may even stop ciliary movement. The force exerted by cilia, measured by atomic force microscopy, is reduced following extracellular ATP hydrolysis. This result complements the current understanding of the ciliary beating regulatory mechanism, with special relevance to inflammatory diseases of the airway epithelium that affect mucociliary clearance. Extracellular nucleotides, including ATP, are locally released by the airway epithelium and stimulate ciliary activity in a [Ca 2+ ] i -dependent manner after mechanical stimulation of ciliated cells. However, it is unclear whether the ATP released is involved in regulating basal ciliary activity and mediating changes in ciliary activity in response to chemical stimulation. In the present study, we evaluated ciliary beat frequency (CBF) and ciliary beating forces in primary cultures from mouse tracheal epithelium, using videomicroscopy and atomic force microscopy (AFM), respectively. Extracellular ATP levels and [Ca 2+ ] i were measured by luminometric and fluorimetric assays, respectively. Uptake of ethidium bromide was measured to evaluate hemichannel functionality. We show that hydrolysis of constitutive extracellular ATP levels with apyrase (50 U ml -1 ) reduced basal CBF by 45% and ciliary force by 67%. The apyrase effect on CBF was potentiated by carbenoxolone, a hemichannel inhibitor, and oxidized ATP, an

Downregulation of hepatic and intestinal ATP-binding-cassette transporters abcg5 and abcg8 expression associated with altered sterol fluxes in rats with streptozotocin-induced diabetes

NARCIS (Netherlands)

Bloks, VW; Bakker-van Waarde, WW; Verkade, HJ; Kema, IP; Havinga, R; Wolters, H; Schaap, FG; Sauer, PJJ; Vink, E; Groen, AK; Kuipers, F

ABSTRACT: P234 Downregulation of Hepatic and Intestinal ATP-Binding-Cassette Transporters Abcg5 and Abcg8 Expression Associated with Altered Sterol Fluxes in Rats with Streptozotocin-Induced Diabetes Vincent W. Bloks, Willie W. Bakker-van Waarde, Henkjan J. Verkade, Ido P. Kema, Rick Havinga, Henk

Direct ATP photolabeling of Escherichia coli recA proteins: identification of regions required for ATP binding

International Nuclear Information System (INIS)

Banks, G.R.; Sedgwick, S.G.

1986-01-01

When the Escherichia coli RecA protein is UV irradiated in the presence of [alpha- 32 P]ATP, a labeled protein--ATP adduct is formed. All the experimental evidence indicates that, in forming such an adduct, the ATP becomes specifically immobilized in the catalytically relevant ATP binding site. The adduct can also be identified after irradiation of E. coli cell lysates in a similar manner. This direct ATP photolabeling of RecA proteins has been used to identify regions of the polypeptide chain involved in the binding of ATP. The photolabeling of a RecA protein that lacks wild-type carboxy-terminal amino acids is not detectable. A RecA protein in which the amino-terminal sequence NH2-Ala-Ile-Asp-Glu-Asn- is replaced by NH2-Thr-Met-Ile-Thr-Asn-Ser-Ser-Ser- is only about 5% as efficiently photolabeled as the wild-type protein. Both of these RecA protein constructions, however, contain all the elements previously implicated, directly or indirectly, in the binding of ATP. ATP-photolabeled RecA protein has also been chemically cleaved at specific amino acids in order to identify regions of the polypeptide chain to which the nucleotide becomes covalently photolinked. The evidence is consistent with a region comprising amino acids 116-170. Thus, this work and that of others suggest that several disparate regions of the unfolded polypeptide chain may combine to form the ATP binding site upon protein folding or may influence binding through long-range effects

ATP Release from Chemotherapy-Treated Dying Leukemia Cells Elicits an Immune Suppressive Effect by Increasing Regulatory T Cells and Tolerogenic Dendritic Cells

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Mariangela Lecciso

2017-12-01

Full Text Available Chemotherapy-induced immunogenic cell death can favor dendritic cell (DC cross-priming of tumor-associated antigens for T cell activation thanks to the release of damage-associated molecular patterns, including ATP. Here, we tested the hypothesis that in acute myeloid leukemia (AML, ATP release, along with its well-known immune stimulatory effect, may also contribute to the generation of an immune suppressive microenvironment. In a cohort of AML patients, undergoing combined daunorubicin and cytarabine chemotherapy, a population of T regulatory cells (Tregs with suppressive phenotype, expressing the immune checkpoint programmed cell death protein 1 (PD-1, was significantly increased. Moving from these results, initial in vitro data showed that daunorubicin was more effective than cytarabine in modulating DC function toward Tregs induction and such difference was correlated with the higher capacity of daunorubicin to induce ATP release from treated AML cells. DCs cultured with daunorubicin-treated AML cells upregulated indoleamine 2,3-dioxygenase 1 (IDO1, which induced anti-leukemia Tregs. These data were confirmed in vivo as daunorubicin-treated mice show an increase in extracellular ATP levels with increased number of Tregs, expressing PD-1 and IDO1+CD39+ DCs. Notably, daunorubicin failed to induce Tregs and tolerogenic DCs in mice lacking the ATP receptor P2X7. Our data indicate that ATP release from chemotherapy-treated dying cells contributes to create an immune suppressive microenvironment in AML.

ATP-gamma-S shifts the operating point of outer hair cell transduction towards scala tympani.

Science.gov (United States)

Bobbin, Richard P; Salt, Alec N

2005-07-01

ATP receptor agonists and antagonists alter cochlear mechanics as measured by changes in distortion product otoacoustic emissions (DPOAE). Some of the effects on DPOAEs are consistent with the hypothesis that ATP affects mechano-electrical transduction and the operating point of the outer hair cells (OHCs). This hypothesis was tested by monitoring the effect of ATP-gamma-S on the operating point of the OHCs. Guinea pigs anesthetized with urethane and with sectioned middle ear muscles were used. The cochlear microphonic (CM) was recorded differentially (scala vestibuli referenced to scala tympani) across the basal turn before and after perfusion (20 min) of the perilymph compartment with artificial perilymph (AP) and ATP-gamma-S dissolved in AP. The operating point was derived from the cochlear microphonics (CM) recorded in response low frequency (200 Hz) tones at high level (106, 112 and 118 dB SPL). The analysis procedure used a Boltzmann function to simulate the CM waveform and the Boltzmann parameters were adjusted to best-fit the calculated waveform to the CM. Compared to the initial perfusion with AP, ATP-gamma-S (333 microM) enhanced peak clipping of the positive peak of the CM (that occurs during organ of Corti displacements towards scala tympani), which was in keeping with ATP-induced displacement of the transducer towards scala tympani. CM waveform analysis quantified the degree of displacement and showed that the changes were consistent with the stimulus being centered on a different region of the transducer curve. The change of operating point meant that the stimulus was applied to a region of the transducer curve where there was greater saturation of the output on excursions towards scala tympani and less saturation towards scala vestibuli. A significant degree of recovery of the operating point was observed after washing with AP. Dose response curves generated by perfusing ATP-gamma-S (333 microM) in a cumulative manner yielded an EC(50) of 19.8 micro

Attenuation of hypoxic current by intracellular applications of ATP regenerating agents in hippocampal CA1 neurons of rat brain slices.

Science.gov (United States)

Chung, I; Zhang, Y; Eubanks, J H; Zhang, L

1998-10-01

Hypoxia-induced outward currents (hyperpolarization) were examined in hippocampal CA1 neurons of rat brain slices, using the whole-cell recording technique. Hypoxic episodes were induced by perfusing slices with an artificial cerebrospinal fluid aerated with 5% CO2/95% N2 rather than 5% CO2/95% O2, for about 3 min. The hypoxic current was consistently and reproducibly induced in CA1 neurons dialysed with an ATP-free patch pipette solution. This current manifested as an outward shift in the holding current in association with increased conductance, and it reversed at -78 +/- 2.5 mV, with a linear I-V relation in the range of -100 to -40 mV. To provide extra energy resources to individual neurons recorded, agents were added to the patch pipette solution, including MgATP alone, MgATP + phosphocreatine + creatine kinase, or MgATP + creatine. In CA1 neurons dialysed with patch solutions including these agents, hypoxia produced small outward currents in comparison with those observed in CA1 neurons dialysed with the ATP-free solution. Among the above agents examined, whole-cell dialysis with MgATP + creatine was the most effective at decreasing the hypoxic outward currents. We suggest that the hypoxic hyperpolarization is closely related to energy metabolism in individual CA1 neurons, and that the energy supply provided by phosphocreatine metabolism may play a critical role during transient metabolic stress.

Inhibition of myeloperoxidase decreases vascular oxidative stress and increases vasodilatation in sickle cell disease mice1[S

Science.gov (United States)

Zhang, Hao; Xu, Hao; Weihrauch, Dorothee; Jones, Deron W.; Jing, Xigang; Shi, Yang; Gourlay, David; Oldham, Keith T.; Hillery, Cheryl A.; Pritchard, Kirkwood A.

2013-01-01

Activated leukocytes and polymorphonuclear neutrophils (PMN) release myeloperoxidase (MPO), which binds to endothelial cells (EC), is translocated, and generates oxidants that scavenge nitric oxide (NO) and impair EC function. To determine whether MPO impairs EC function in sickle cell disease (SCD), control (AA) and SCD mice were treated with N-acetyl-lysyltyrosylcysteine-amide (KYC). SCD humans and mice have high plasma MPO and soluble L-selectin (sL-selectin). KYC had no effect on MPO but decreased plasma sL-selectin and malondialdehyde in SCD mice. MPO and 3-chlorotyrosine (3-ClTyr) were increased in SCD aortas. KYC decreased MPO and 3-ClTyr in SCD aortas to the levels in AA aortas. Vasodilatation in SCD mice was impaired. KYC increased vasodilatation in SCD mice more than 2-fold, to ∼60% of levels in AA mice. KYC inhibited MPO-dependent 3-ClTyr formation in EC proteins. SCD mice had high plasma alanine transaminase (ALT), which tended to decrease in KYC-treated SCD mice (P = 0.07). KYC increased MPO and XO/XDH and decreased 3-ClTyr and 3-nitrotyrosine (3-NO2Tyr) in SCD livers. These data support the hypothesis that SCD increases release of MPO, which generates oxidants that impair EC function and injure livers. Inhibiting MPO is an effective strategy for decreasing oxidative stress and liver injury and restoring EC function in SCD. PMID:23956444

ATP Release and Effects in Pancreas

DEFF Research Database (Denmark)

Novak, Ivana; Amstrup, Jan; Henriksen, Katrine Lütken

2003-01-01

ATP and other nucleotides are released from various cells, but the pathway and physiological stimulus for ATP release are often unclear. The focus of our studies is the understanding of ATP release and signaling in rat exocrine pancreas. In acinar suspension mechanical stimulation, hypotonic shock...

ATP7A is a novel target of retinoic acid receptor β2 in neuroblastoma cells

Science.gov (United States)

Bohlken, A; Cheung, B B; Bell, J L; Koach, J; Smith, S; Sekyere, E; Thomas, W; Norris, M; Haber, M; Lovejoy, D B; Richardson, D R; Marshall, G M

2009-01-01

Increased retinoic acid receptor β (RARβ2) gene expression is a hallmark of cancer cell responsiveness to retinoid anticancer effects. Moreover, low basal or induced RARβ2 expression is a common feature of many human cancers, suggesting that RARβ2 may act as a tumour suppressor gene in the absence of supplemented retinoid. We have previously shown that low RARβ2 expression is a feature of advanced neuroblastoma. Here, we demonstrate that the ABC domain of the RARβ2 protein alone was sufficient for the growth inhibitory effects of RARβ2 on neuroblastoma cells. ATP7A, the copper efflux pump, is a retinoid-responsive gene, was upregulated by ectopic overexpression of RARβ2. The ectopic overexpression of the RARβ2 ABC domain was sufficient to induce ATP7A expression, whereas, RARβ2 siRNA blocked the induction of ATP7A expression in retinoid-treated neuroblastoma cells. Forced downregulation of ATP7A reduced copper efflux and increased viability of retinoid-treated neuroblastoma cells. Copper supplementation enhanced cell growth and reduced retinoid-responsiveness, whereas copper chelation reduced the viability and proliferative capacity. Taken together, our data demonstrates ATP7A expression is regulated by retinoic acid receptor β and it has effects on intracellular copper levels, revealing a link between the anticancer action of retinoids and copper metabolism. PMID:19127267

Calcium Co-regulates Oxidative Metabolism and ATP Synthase-dependent Respiration in Pancreatic Beta Cells

Science.gov (United States)

De Marchi, Umberto; Thevenet, Jonathan; Hermant, Aurelie; Dioum, Elhadji; Wiederkehr, Andreas

2014-01-01

Mitochondrial energy metabolism is essential for glucose-induced calcium signaling and, therefore, insulin granule exocytosis in pancreatic beta cells. Calcium signals are sensed by mitochondria acting in concert with mitochondrial substrates for the full activation of the organelle. Here we have studied glucose-induced calcium signaling and energy metabolism in INS-1E insulinoma cells and human islet beta cells. In insulin secreting cells a surprisingly large fraction of total respiration under resting conditions is ATP synthase-independent. We observe that ATP synthase-dependent respiration is markedly increased after glucose stimulation. Glucose also causes a very rapid elevation of oxidative metabolism as was followed by NAD(P)H autofluorescence. However, neither the rate of the glucose-induced increase nor the new steady-state NAD(P)H levels are significantly affected by calcium. Our findings challenge the current view, which has focused mainly on calcium-sensitive dehydrogenases as the target for the activation of mitochondrial energy metabolism. We propose a model of tight calcium-dependent regulation of oxidative metabolism and ATP synthase-dependent respiration in beta cell mitochondria. Coordinated activation of matrix dehydrogenases and respiratory chain activity by calcium allows the respiratory rate to change severalfold with only small or no alterations of the NAD(P)H/NAD(P)+ ratio. PMID:24554722

Hypo-and hyperthyroidism affect the ATP, ADP and AMP hydrolysis in rat hippocampal and cortical slices.

Science.gov (United States)

Bruno, Alessandra Nejar; Diniz, Gabriela Placoná; Ricachenevsky, Felipe Klein; Pochmann, Daniela; Bonan, Carla Denise; Barreto-Chaves, Maria Luiza M; Sarkis, João José Freitas

2005-05-01

The presence of severe neurological symptoms in thyroid diseases has highlighted the importance of thyroid hormones in the normal functioning of the mature brain. Since, ATP is an important excitatory neurotransmitter and adenosine acts as a neuromodulatory structure inhibiting neurotransmitters release in the central nervous system (CNS), the ectonucleotidase cascade that hydrolyzes ATP to adenosine, is also involved in the control of brain functions. Thus, we investigated the influence of hyper-and hypothyroidism on the ATP, ADP and AMP hydrolysis in hippocampal and cortical slices from adult rats. Hyperthyroidism was induced by daily injections of l-thyroxine (T4) 25 microg/100 g body weight, for 14 days. Hypothyroidism was induced by thyroidectomy and methimazole (0.05%) added to their drinking water for 14 days. Hypothyroid rats were hormonally replaced by daily injections of T4 (5 microg/100 g body weight, i.p.) for 5 days. Hyperthyroidism significantly inhibited the ATP, ADP and AMP hydrolysis in hippocampal slices. In brain cortical slices, hyperthyroidism inhibited the AMP hydrolysis. In contrast, hypothyroidism increased the ATP, ADP and AMP hydrolysis in both hippocampal and cortical slices and these effects were reverted by T4 replacement. Furthermore, hypothyroidism increased the expression of NTPDase1 and 5'-nucleotidase, whereas hyperthyroidism decreased the expression of 5'-nucleotidase in hippocampus of adult rats. These findings demonstrate that thyroid disorders may influence the enzymes involved in the complete degradation of ATP to adenosine and possibly affects the responses mediated by adenine nucleotides in the CNS of adult rats.

Functional K(ATP) channels in the rat retinal microvasculature: topographical distribution, redox regulation, spermine modulation and diabetic alteration.

Science.gov (United States)

Ishizaki, Eisuke; Fukumoto, Masanori; Puro, Donald G

2009-05-15

The essential task of the circulatory system is to match blood flow to local metabolic demand. However, much remains to be learned about this process. To better understand how local perfusion is regulated, we focused on the functional organization of the retinal microvasculature, which is particularly well adapted for the local control of perfusion. Here, we assessed the distribution and regulation of functional K(ATP) channels whose activation mediates the hyperpolarization induced by adenosine. Using microvascular complexes freshly isolated from the rat retina, we found a topographical heterogeneity in the distribution of functional K(ATP) channels; capillaries generate most of the K(ATP) current. The initiation of K(ATP)-induced responses in the capillaries supports the concept that the regulation of retinal perfusion is highly decentralized. Additional study revealed that microvascular K(ATP) channels are redox sensitive, with oxidants increasing their activity. Furthermore, the oxidant-mediated activation of these channels is driven by the polyamine spermine, whose catabolism produces oxidants. In addition, our observation that spermine-dependent oxidation occurs predominately in the capillaries accounts for why they generate most of the K(ATP) current detected in retinal microvascular complexes. Here, we also analysed retinal microvessels of streptozotocin-injected rats. We found that soon after the onset of diabetes, an increase in spermine-dependent oxidation at proximal microvascular sites boosts their K(ATP) current and thereby virtually eliminates the topographical heterogeneity of functional K(ATP) channels. We conclude that spermine-dependent oxidation is a previously unrecognized mechanism by which this polyamine modulates ion channels; in addition to a physiological role, spermine-dependent oxidation may also contribute to microvascular dysfunction in the diabetic retina.

A sensitive electrochemical aptasensor for ATP detection based on exonuclease III-assisted signal amplification strategy.

Science.gov (United States)

Bao, Ting; Shu, Huawei; Wen, Wei; Zhang, Xiuhua; Wang, Shengfu

2015-03-03

A target-induced structure-switching electrochemical aptasensor for sensitive detection of ATP was successfully constructed which was based on exonuclease III-catalyzed target recycling for signal amplification. With the existence of ATP, methylene blue (MB) labeled hairpin DNA formed G-quadruplex with ATP, which led to conformational changes of the hairpin DNA and created catalytic cleavage sites for exonuclease III (Exo III). Then the structure-switching DNA hybridized with capture DNA which made MB close to electrode surface. Meanwhile, Exo III selectively digested aptamer from its 3'-end, thus G-quadruplex structure was destroyed and ATP was released for target recycling. The Exo III-assisted target recycling amplified electrochemical signal significantly. Fluorescence experiment was performed to confirm the structure-switching process of the hairpin DNA. In fluorescence experiment, AuNPs-aptamer conjugates were synthesized, AuNPs quenched fluorescence of MB, the target-induced structure-switching made Exo III digested aptamer, which restored fluorescence. Under optimized conditions, the proposed aptasensor showed a linear range of 0.1-20 nM with a detection limit of 34 pM. In addition, the proposed aptasensor had good stability and selectivity, offered promising choice for the detection of other small molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Hypercapnic vasodilatation in isolated rat basilar arteries is exerted via low pH and does not involve nitric oxide synthase stimulation or cyclic GMP production

DEFF Research Database (Denmark)

You, J P; Wang, Qian; Zhang, W

1994-01-01

this relaxation by 54% and 70%, respectively. The effect of L-NOARG was completely reversed by L-arginine. Blockade of nerve excitation with tetrodotoxin (TTX) had no affect on the 15% CO2 elicited vasodilatation. Measurements of cGMP in vessel segments showed no significant increase in cGMP content in response...... to hypercapnia. L-NOARG and MB, but not TTX, significantly reduced the basal cGMP content in cerebral vessels. Adding 1.5% halothane to the incubation medium did not result in a significant increase in cGMP content. Lowering the pH by cumulative application of 0.12 M HCl resulted in relaxation identical...... elicits vasodilatation of isolated rat basilar arteries by a mechanism independent of nitric oxide synthase (NOS) activity. The markedly reduced basal cGMP levels in cerebral vessels by L-NOARG and MB suggest that there exists a basal NO formation in the cerebral vessel wall....

Structural models of the human copper P-type ATPases ATP7A and ATP7B

DEFF Research Database (Denmark)

Gourdon, P.; Sitsel, Oleg; Karlsen, J.L.

2012-01-01

The human copper exporters ATP7A and ATP7B contain domains common to all P-type ATPases as well as class-specific features such as six sequential heavy-metal binding domains (HMBD1-HMBD6) and a type-specific constellation of transmembrane helices. Despite the medical significance of ATP7A and ATP7B......, allowing protein-specific properties to be addressed. Furthermore, the mapping of known disease-causing missense mutations indicates that among the heavy-metal binding domains, HMBD5 and HMBD6 are the most crucial for function, thus mimicking the single or dual HMBDs found in most copper-specific P-type...

The role of tissue oxygen tension in the control of local blood flow in the microcirculation of skeletal muscles

DEFF Research Database (Denmark)

Ngo, Thuc Anh

2010-01-01

In the microcirculation blood flow is highly regulated dependent on the metabolic activity of the tissues. Among several mechanisms, mechanisms involved in the coupling of changes in tissue oxygen tension due to changes in the metabolic activity of the tissue play an important role. In the systemic...... (inhibitor of KATP channels) in the superfusate abolished both vasodilatation and constriction to low and high oxygen superfusate, indicating that KATP channels are involved in both hypoxic vasodilatation and hyperoxic vasoconstriction. Red blood cells (RBCs) have been proposed to release ATP and...... as in the intact blood-perfused arteriole. This indicates that RBCs are not essential for hypoxic vasodilatation. In addition several potential pathways were evaluated. Application of DPCPX (inhibitor of adenosine A1 and A2 receptors) and L-NAME (inhibitor of NO-synthase) did not affect vasomotor responses to low...

Coordination of substrate binding and ATP hydrolysis in Vps4-mediated ESCRT-III disassembly.

Science.gov (United States)

Davies, Brian A; Azmi, Ishara F; Payne, Johanna; Shestakova, Anna; Horazdovsky, Bruce F; Babst, Markus; Katzmann, David J

2010-10-01

ESCRT-III undergoes dynamic assembly and disassembly to facilitate membrane exvagination processes including multivesicular body (MVB) formation, enveloped virus budding, and membrane abscission during cytokinesis. The AAA-ATPase Vps4 is required for ESCRT-III disassembly, however the coordination of Vps4 ATP hydrolysis with ESCRT-III binding and disassembly is not understood. Vps4 ATP hydrolysis has been proposed to execute ESCRT-III disassembly as either a stable oligomer or an unstable oligomer whose dissociation drives ESCRT-III disassembly. An in vitro ESCRT-III disassembly assay was developed to analyze Vps4 function during this process. The studies presented here support a model in which Vps4 acts as a stable oligomer during ATP hydrolysis and ESCRT-III disassembly. Moreover, Vps4 oligomer binding to ESCRT-III induces coordination of ATP hydrolysis at the level of individual Vps4 subunits. These results suggest that Vps4 functions as a stable oligomer that acts upon individual ESCRT-III subunits to facilitate ESCRT-III disassembly.

Evidence for the Synthesis of ATP by an F0F1 ATP Synthase in Membrane Vesicles from Halorubrum Saccharovorum

Science.gov (United States)

Faguy, David; Lawson, Darion; Hochstein, Lawrence I.; Chang, Sherwood (Technical Monitor)

1996-01-01

Vesicles prepared in a buffer containing ADP, Mg(2+) and Pi synthesized ATP at an initial rate of 2 nmols/min/mg protein after acidification of the bulk medium (pH 8 (right arrow) 4). The intravesicular ATP concentration reached a steady state after about 30 seconds and slowly declined thereafter. ATP synthesis was inhibited by low concentrations of dicyclohexylcarbodiimide and m-chlorophenylhydrazone indicating that synthesis took place in response to the proton gradient. NEM and PCMS, which inhibit vacuolar ATPases and the vacuolar-like ATPases of extreme halophiles, did not affect ATP synthesis, and, in fact, produced higher steady state levels of ATP. This suggested that two ATPase activities were present, one which catalyzed ATP synthesis and one that caused its hydrolysis. Azide, a specific inhibitor of F0F1 ATP Synthases, inhibited halobacterial ATP synthesis. The distribution of acridine orange as imposed by a delta pH demonstrated that azide inhibition was not due to the collapse of the proton gradient due to azide acting as a protonophore. Such an effect was observed, but only at azide concentrations higher than those that inhibited ATP synthesis. These results confirm the earler observations with cells of H. saccharovorum and other extreme halophiles that ATP synthesis is inconsistent with the operation of a vacuolar-like ATPase. Therefore, the observation that a vacuolar-like enzyme is responsible for ATP synthesis (and which serves as the basis for imputing ATP synthesis to the vacuolar-like ATPases of the extreme halophiles, and the Archaea in general) should be taken with some degree of caution.

Ca2+-mobilizing agonists increase mitochondrial ATP production to accelerate cytosolic Ca2+ removal: aberrations in human complex I deficiency.

NARCIS (Netherlands)

Visch, H.J.; Koopman, W.J.H.; Zeegers, D.; Emst-de Vries, S.E. van; Kuppeveld, F.J.M. van; Heuvel, L.W. van den; Smeitink, J.A.M.; Willems, P.H.G.M.

2006-01-01

Previously, we reported that both the bradykinin (Bk)-induced increase in mitochondrial ATP concentration ([ATP]M) and the rate of cytosolic Ca2+ removal are significantly decreased in skin fibroblasts from a patient with an isolated complex I deficiency. Here we demonstrate that the mitochondrial

L-Lactate protects neurons against excitotoxicity: implication of an ATP-mediated signaling cascade

KAUST Repository

Jourdain, P.

2016-02-19

Converging experimental data indicate a neuroprotective action of L-Lactate. Using Digital Holographic Microscopy, we observe that transient application of glutamate (100 μM; 2 min) elicits a NMDA-dependent death in 65% of mouse cortical neurons in culture. In the presence of L-Lactate (or Pyruvate), the percentage of neuronal death decreases to 32%. UK5099, a blocker of the Mitochondrial Pyruvate Carrier, fully prevents L-Lactate-mediated neuroprotection. In addition, L-Lactate-induced neuroprotection is not only inhibited by probenicid and carbenoxolone, two blockers of ATP channel pannexins, but also abolished by apyrase, an enzyme degrading ATP, suggesting that ATP produced by the Lactate/Pyruvate pathway is released to act on purinergic receptors in an autocrine/paracrine manner. Finally, pharmacological approaches support the involvement of the P2Y receptors associated to the PI3-kinase pathway, leading to activation of KATP channels. This set of results indicates that L-Lactate acts as a signalling molecule for neuroprotection against excitotoxicity through coordinated cellular pathways involving ATP production, release and activation of a P2Y/KATP cascade.

L-Lactate protects neurons against excitotoxicity: implication of an ATP-mediated signaling cascade

KAUST Repository

Jourdain, P.; Allaman, I.; Rothenfusser, K.; Fiumelli, Hubert; Marquet, P.; Magistretti, Pierre J.

2016-01-01

Converging experimental data indicate a neuroprotective action of L-Lactate. Using Digital Holographic Microscopy, we observe that transient application of glutamate (100 μM; 2 min) elicits a NMDA-dependent death in 65% of mouse cortical neurons in culture. In the presence of L-Lactate (or Pyruvate), the percentage of neuronal death decreases to 32%. UK5099, a blocker of the Mitochondrial Pyruvate Carrier, fully prevents L-Lactate-mediated neuroprotection. In addition, L-Lactate-induced neuroprotection is not only inhibited by probenicid and carbenoxolone, two blockers of ATP channel pannexins, but also abolished by apyrase, an enzyme degrading ATP, suggesting that ATP produced by the Lactate/Pyruvate pathway is released to act on purinergic receptors in an autocrine/paracrine manner. Finally, pharmacological approaches support the involvement of the P2Y receptors associated to the PI3-kinase pathway, leading to activation of KATP channels. This set of results indicates that L-Lactate acts as a signalling molecule for neuroprotection against excitotoxicity through coordinated cellular pathways involving ATP production, release and activation of a P2Y/KATP cascade.

Nanomechanics of the substrate binding domain of Hsp70 determine its allosteric ATP-induced conformational change.

Science.gov (United States)

Mandal, Soumit Sankar; Merz, Dale R; Buchsteiner, Maximilian; Dima, Ruxandra I; Rief, Matthias; Žoldák, Gabriel

2017-06-06

Owing to the cooperativity of protein structures, it is often almost impossible to identify independent subunits, flexible regions, or hinges simply by visual inspection of static snapshots. Here, we use single-molecule force experiments and simulations to apply tension across the substrate binding domain (SBD) of heat shock protein 70 (Hsp70) to pinpoint mechanical units and flexible hinges. The SBD consists of two nanomechanical units matching 3D structural parts, called the α- and β-subdomain. We identified a flexible region within the rigid β-subdomain that gives way under load, thus opening up the α/β interface. In exactly this region, structural changes occur in the ATP-induced opening of Hsp70 to allow substrate exchange. Our results show that the SBD's ability to undergo large conformational changes is already encoded by passive mechanics of the individual elements.

Vascular ATP-sensitive potassium channels are over-expressed and partially regulated by nitric oxide in experimental septic shock.

Science.gov (United States)

Collin, Solène; Sennoun, Nacira; Dron, Anne-Gaëlle; de la Bourdonnaye, Mathilde; Montemont, Chantal; Asfar, Pierre; Lacolley, Patrick; Meziani, Ferhat; Levy, Bruno

2011-05-01

To study the activation and expression of vascular (aorta and small mesenteric arteries) potassium channels during septic shock with or without modulation of the NO pathway. Septic shock was induced in rats by peritonitis. Selective inhibitors of vascular K(ATP) (PNU-37883A) or BK(Ca) [iberiotoxin (IbTX)] channels were used to demonstrate their involvement in vascular hyporeactivity. Vascular response to phenylephrine was measured on aorta and small mesenteric arteries mounted on a wire myograph. Vascular expression of potassium channels was studied by PCR and Western blot, in the presence or absence of 1400W, an inducible NO synthase (iNOS) inhibitor. Aortic activation of the transcriptional factor nuclear factor-kappaB (NF-κB) was assessed by electrophoretic mobility shift assay. Arterial pressure as well as in vivo and ex vivo vascular reactivity were reduced by sepsis and improved by PNU-37883A but not by IbTX. Sepsis was associated with an up-regulation of mRNA and protein expression of vascular K(ATP) channels, while expression of vascular BK(Ca) channels remained unchanged. Selective iNOS inhibition blunted the sepsis-induced increase in aortic NO, decreased NF-κB activation, and down-regulated vascular K(ATP) channel expression. Vascular K(ATP) but not BK(Ca) channels are activated, over-expressed, and partially regulated by NO via NF-κB activation during septic shock. Their selective inhibition restores arterial pressure and vascular reactivity and decreases lactate concentration. The present data suggest that selective vascular K(ATP) channel inhibitors offer potential therapeutic perspectives for septic shock.

Keragaman Genetik Sekuen Gen ATP Synthase FO Subunit 6 (ATP6 Monyet Hantu (Tarsius Indonesia (GENETIC DIVERSITY STUDY OF ATP6 GENE SEQUENCES OF TARSIERS FROM INDONESIA

Directory of Open Access Journals (Sweden)

Rini Widayanti

2013-07-01

Full Text Available In a conservation effort, the identification of Tarsier species, on the bases of the morphological andmolecular characteristic is necessary. Up to now, the identification of the animals were based on themorphology and vocalizations, which is extremely difficult to identify each, tarsier species. The objective ofthis research was to study the genetic diversity on ATP6 gene of Tarsius sp. Based on sequencing of PCRproduct using primer ATP6F and ATP6R with 681 nts. PCR product. The sequence of ATP6 fragmentswere aligned with other primates from Gene bank with aid of software Clustal W, and were analyzed usingMEGA program version 4.0. Three different nucleotide sites were found (nucleotide no. 288, 321 and 367.The genetic distance based on nucleotide ATP6 sequence calculated using Kimura 2-parameter modelindicated that the smallest genetic distance 0%, biggest 0.8% and average 0, 2%. The phylogenetic treeusing neighbor joining method based on the sequence of nucleotide ATP6 gene could not be used todifferentiate among T. Dianae (from Central Sulawesi, T. Spectrum (from North Sulawesi, T. bancanus(from lampung, South Sumatera and T.bancanus from West Kalimantan.

Inhibition of ATP synthesis by fenbufen and its conjugated metabolites in rat liver mitochondria

DEFF Research Database (Denmark)

Syed, Muzeeb; Skonberg, Christian; Hansen, Steen Honoré

2016-01-01

in the drug induced liver injury (DILI) by fenbufen, the inhibitory effect of fenbufen and its conjugated metabolites on oxidative phosphorylation (ATP synthesis) in rat liver mitochondria was investigated. Fenbufen glucuronide (F-GlcA), fenbufen-N-acetyl cysteine-thioester (F-NAC) and fenbufen...... and fenbufen show any protective effect on fenbufen mediated inhibition of oxidative phosphorylation. Inclusion of NADPH in mitochondrial preparations with fenbufen did not modulate the inhibitory effects, suggesting no role of CYP mediated oxidative metabolites on the ATP synthesis in isolated mitochondria...

Benfotiamine counteracts smoking-induced vascular dysfunction in healthy smokers.

Science.gov (United States)

Stirban, Alin; Nandrean, Simona; Kirana, Stanley; Götting, Christian; Veresiu, Ioan Andrei; Tschoepe, Diethelm

2012-01-01

Background. Smoking induces endothelial dysfunction (ED) mainly by exacerbating oxidative stress (OS) and inflammation. Benfotiamine, a thiamine prodrug with high bioavailability, prevents nicotine-induced vascular dysfunction in rats. It remained unknown whether this effect also occurs in humans. Methods. Therefore, 20 healthy volunteers (mean age: 38 years) were investigated twice, 7-10 days apart in a randomized, cross-over, and investigator-blinded design. Vascular function was assessed by flow-mediated vasodilatation (FMD) of the brachial artery and by measurements of the soluble vascular cell adhesion molecule (sVCAM)-1. Investigations were performed after an overnight fast as well as 20 minutes after one cigarette smoking. On another day, the same procedure was applied following a 3-day oral therapy with benfotiamine (1050 mg/day). Ten patients were randomized to start with smoking alone, and ten started with benfotiamine. Results. Results are expressed as (mean ± SEM). Smoking acutely induced a decrease in FMD by 50% ((∗∗)P benfotiamine treatment to 25%(∗§) ((∗)P benfotiamine. The endothelium-independent vasodilatation remained unaltered between days. Conclusion. In healthy volunteers, smoking blunts vascular function mirrored by a decrease in FMD and an increase in sVCAM-1. Short-term treatment with benfotiamine significantly reduces these effects, showing protective vascular properties.

Duchenne muscular dystrophy: normal ATP turnover in cultured cells

International Nuclear Information System (INIS)

Fox, I.H.; Bertorini, T.; Palmieri, G.M.A.; Shefner, R.

1986-01-01

This paper examines ATP metabolism in cultured muscle cells and fibroblasts from patients with Duchenne dystrophy. ATP and ADP levels were the same in cultured cells from normal subjects and patients and there was no difference in ATP synthesis or degradation. The ATP synthesis was measured by the incorporation of C 14-U-adenine into aTP and ADP. although there was a significant decrease in radioactively labelled ATP after incubation with deoxyglucose in Duchenne muscle cells, there was no difference in ATP concentration of ADP metabolism

Deformation-induced release of ATP from erythrocytes in a poly(dimethylsiloxane)-based microchip with channels that mimic resistance vessels.

Science.gov (United States)

Price, Alexander K; Fischer, David J; Martin, R Scott; Spence, Dana M

2004-08-15

The ability of nitric oxide to relax smooth muscle cells surrounding resistance vessels in vivo is well documented. Here, we describe a series of studies designed to quantify amounts of adenosine triphosphate (ATP), a known stimulus of NO production in endothelial cells, released from erythrocytes that are mechanically deformed as these cells traverse microbore channels in lithographically patterned microchips. Results indicate that micromolar amounts of ATP are released from erythrocytes flowing through channels having cross sectional dimensions of 60 x 38 micron (2.22 +/- 0.50 microM ATP). Microscopic images indicate that erythrocytes, when being pumped through the microchip channels, migrate toward the center of the channels, leaving a cell-free or skimming layer at the walls of the channel, a profile known to exist in circulatory vessels in vivo. A comparison of the amounts of ATP released from RBCs mechanically deformed in microbore tubing (2.54 +/- 0.15 microM) vs a microchip (2.59 +/- 0.32 microM) suggests that channels in microchips may serve as functional biomimics of the microvasculature. Control studies involving diamide, a membrane-stiffening agent, suggest that the RBC-derived ATP is not due to cell lysis but rather physical deformation.

A taste for ATP: neurotransmission in taste buds

Science.gov (United States)

Kinnamon, Sue C.; Finger, Thomas E.

2013-01-01

Not only is ATP a ubiquitous source of energy but it is also used widely as an intercellular signal. For example, keratinocytes release ATP in response to numerous external stimuli including pressure, heat, and chemical insult. The released ATP activates purinergic receptors on nerve fibers to generate nociceptive signals. The importance of an ATP signal in epithelial-to-neuronal signaling is nowhere more evident than in the taste system. The receptor cells of taste buds release ATP in response to appropriate stimulation by tastants and the released ATP then activates P2X2 and P2X3 receptors on the taste nerves. Genetic ablation of the relevant P2X receptors leaves an animal without the ability to taste any primary taste quality. Of interest is that release of ATP by taste receptor cells occurs in a non-vesicular fashion, apparently via gated membrane channels. Further, in keeping with the crucial role of ATP as a neurotransmitter in this system, a subset of taste cells expresses a specific ectoATPase, NTPDase2, necessary to clear extracellular ATP which otherwise will desensitize the P2X receptors on the taste nerves. The unique utilization of ATP as a key neurotransmitter in the taste system may reflect the epithelial rather than neuronal origins of the receptor cells. PMID:24385952

A taste for ATP: neurotransmission in taste buds

Directory of Open Access Journals (Sweden)

Thomas E. Finger

2013-12-01

Full Text Available Not only is ATP a ubiquitous source of energy but it is also used widely as an intercellular signal. For example, keratinocytes release ATP in response to numerous external stimuli including pressure, heat and chemical insult. The released ATP activates purinergic receptors on nerve fibers to generate nociceptive signals. The importance of an ATP signal in epithelial-to-neuronal signaling is nowhere more evident than in the taste system. The receptor cells of taste buds release ATP in response to appropriate stimulation by tastants and the released ATP then activates P2X2 and P2X3 receptors on the taste nerves. Genetic ablation of the relevant P2X receptors leaves an animal without the ability to taste any primary taste quality. Of interest is that release of ATP by taste receptor cells occurs in a non-vesicular fashion, apparently via gated membrane channels. Further, in keeping with the crucial role of ATP as a neurotransmitter in this system, a subset of taste cells expresses a specific ectoATPase, NTPDase2, necessary to clear extracellular ATP which otherwise will desensitize the P2X receptors on the taste nerves. The unique utilization of ATP as a key neurotransmitter in the taste system may reflect the epithelial rather than neuronal origins of the receptor cells.

Mechanical Control of ATP Synthase Function: Activation Energy Difference between Tight and Loose Binding Sites

KAUST Repository

Beke-Somfai, Tamás

2010-01-26

Despite exhaustive chemical and crystal structure studies, the mechanistic details of how FoF1-ATP synthase can convert mechanical energy to chemical, producing ATP, are still not fully understood. On the basis of quantum mechanical calculations using a recent highresolution X-ray structure, we conclude that formation of the P-O bond may be achieved through a transition state (TS) with a planar PO3 - ion. Surprisingly, there is a more than 40 kJ/mol difference between barrier heights of the loose and tight binding sites of the enzyme. This indicates that even a relatively small change in active site conformation, induced by the γ-subunit rotation, may effectively block the back reaction in βTP and, thus, promote ATP. © 2009 American Chemical Society.

Optimisation of ATP determination in drinking water

DEFF Research Database (Denmark)

Corfitzen, Charlotte B.; Albrechtsen, Hans-Jørgen

Adenosine Triphosphate (ATP) can be used as a relative measure of cell activity, and is measured by the light output from the reaction between luciferin and ATP catalyzed by firefly luciferase. The measurement has potential as a monitoring and surveillance tool within drinking water distribution,...... be separated from the water phase by filtration.......Adenosine Triphosphate (ATP) can be used as a relative measure of cell activity, and is measured by the light output from the reaction between luciferin and ATP catalyzed by firefly luciferase. The measurement has potential as a monitoring and surveillance tool within drinking water distribution...... and an Advance Coupe luminometer. The investigations showed a 60 times higher response of the PCP-kit, making it more suitable for measurement of samples with low ATP content. ATP-standard dilutions prepared in tap water were stable for at least 15 months when stored frozen at -80ºC, and storage of large...

Structural and biochemical studies on ATP binding and hydrolysis by the Escherichia coli RNA chaperone Hfq.

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Hermann Hämmerle

Full Text Available In Escherichia coli the RNA chaperone Hfq is involved in riboregulation by assisting base-pairing between small regulatory RNAs (sRNAs and mRNA targets. Several structural and biochemical studies revealed RNA binding sites on either surface of the donut shaped Hfq-hexamer. Whereas sRNAs are believed to contact preferentially the YKH motifs present on the proximal site, poly(A(15 and ADP were shown to bind to tripartite binding motifs (ARE circularly positioned on the distal site. Hfq has been reported to bind and to hydrolyze ATP. Here, we present the crystal structure of a C-terminally truncated variant of E. coli Hfq (Hfq(65 in complex with ATP, showing that it binds to the distal R-sites. In addition, we revisited the reported ATPase activity of full length Hfq purified to homogeneity. At variance with previous reports, no ATPase activity was observed for Hfq. In addition, FRET assays neither indicated an impact of ATP on annealing of two model oligoribonucleotides nor did the presence of ATP induce strand displacement. Moreover, ATP did not lead to destabilization of binary and ternary Hfq-RNA complexes, unless a vast stoichiometric excess of ATP was used. Taken together, these studies strongly suggest that ATP is dispensable for and does not interfere with Hfq-mediated RNA transactions.

A polycystin-type transient receptor potential (Trp channel that is activated by ATP

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David Traynor

2017-02-01

Full Text Available ATP and ADP are ancient extra-cellular signalling molecules that in Dictyostelium amoebae cause rapid, transient increases in cytosolic calcium due to an influx through the plasma membrane. This response is independent of hetero-trimeric G-proteins, the putative IP3 receptor IplA and all P2X channels. We show, unexpectedly, that it is abolished in mutants of the polycystin-type transient receptor potential channel, TrpP. Responses to the chemoattractants cyclic-AMP and folic acid are unaffected in TrpP mutants. We report that the DIF morphogens, cyclic-di-GMP, GABA, glutamate and adenosine all induce strong cytoplasmic calcium responses, likewise independently of TrpP. Thus, TrpP is dedicated to purinergic signalling. ATP treatment causes cell blebbing within seconds but this does not require TrpP, implicating a separate purinergic receptor. We could detect no effect of ATP on chemotaxis and TrpP mutants grow, chemotax and develop almost normally in standard conditions. No gating ligand is known for the human homologue of TrpP, polycystin-2, which causes polycystic kidney disease. Our results now show that TrpP mediates purinergic signalling in Dictyostelium and is directly or indirectly gated by ATP.

Electron transfer precedes ATP hydrolysis during nitrogenase catalysis.

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Duval, Simon; Danyal, Karamatullah; Shaw, Sudipta; Lytle, Anna K; Dean, Dennis R; Hoffman, Brian M; Antony, Edwin; Seefeldt, Lance C

2013-10-08

The biological reduction of N2 to NH3 catalyzed by Mo-dependent nitrogenase requires at least eight rounds of a complex cycle of events associated with ATP-driven electron transfer (ET) from the Fe protein to the catalytic MoFe protein, with each ET coupled to the hydrolysis of two ATP molecules. Although steps within this cycle have been studied for decades, the nature of the coupling between ATP hydrolysis and ET, in particular the order of ET and ATP hydrolysis, has been elusive. Here, we have measured first-order rate constants for each key step in the reaction sequence, including direct measurement of the ATP hydrolysis rate constant: kATP = 70 s(-1), 25 °C. Comparison of the rate constants establishes that the reaction sequence involves four sequential steps: (i) conformationally gated ET (kET = 140 s(-1), 25 °C), (ii) ATP hydrolysis (kATP = 70 s(-1), 25 °C), (iii) Phosphate release (kPi = 16 s(-1), 25 °C), and (iv) Fe protein dissociation from the MoFe protein (kdiss = 6 s(-1), 25 °C). These findings allow completion of the thermodynamic cycle undergone by the Fe protein, showing that the energy of ATP binding and protein-protein association drive ET, with subsequent ATP hydrolysis and Pi release causing dissociation of the complex between the Fe(ox)(ADP)2 protein and the reduced MoFe protein.

Electron transfer precedes ATP hydrolysis during nitrogenase catalysis

Science.gov (United States)

Duval, Simon; Danyal, Karamatullah; Shaw, Sudipta; Lytle, Anna K.; Dean, Dennis R.; Hoffman, Brian M.; Antony, Edwin; Seefeldt, Lance C.

2013-01-01

The biological reduction of N2 to NH3 catalyzed by Mo-dependent nitrogenase requires at least eight rounds of a complex cycle of events associated with ATP-driven electron transfer (ET) from the Fe protein to the catalytic MoFe protein, with each ET coupled to the hydrolysis of two ATP molecules. Although steps within this cycle have been studied for decades, the nature of the coupling between ATP hydrolysis and ET, in particular the order of ET and ATP hydrolysis, has been elusive. Here, we have measured first-order rate constants for each key step in the reaction sequence, including direct measurement of the ATP hydrolysis rate constant: kATP = 70 s−1, 25 °C. Comparison of the rate constants establishes that the reaction sequence involves four sequential steps: (i) conformationally gated ET (kET = 140 s−1, 25 °C), (ii) ATP hydrolysis (kATP = 70 s−1, 25 °C), (iii) Phosphate release (kPi = 16 s−1, 25 °C), and (iv) Fe protein dissociation from the MoFe protein (kdiss = 6 s−1, 25 °C). These findings allow completion of the thermodynamic cycle undergone by the Fe protein, showing that the energy of ATP binding and protein–protein association drive ET, with subsequent ATP hydrolysis and Pi release causing dissociation of the complex between the Feox(ADP)2 protein and the reduced MoFe protein. PMID:24062462

ATP-Driven Contraction of Phage T3 Capsids with DNA Incompletely Packaged In Vivo

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Philip Serwer

2017-05-01

Full Text Available Adenosine triphosphate (ATP cleavage powers packaging of a double-stranded DNA (dsDNA molecule in a pre-assembled capsid of phages that include T3. Several observations constitute a challenge to the conventional view that the shell of the capsid is energetically inert during packaging. Here, we test this challenge by analyzing the in vitro effects of ATP on the shells of capsids generated by DNA packaging in vivo. These capsids retain incompletely packaged DNA (ipDNA and are called ipDNA-capsids; the ipDNA-capsids are assumed to be products of premature genome maturation-cleavage. They were isolated via preparative Nycodenz buoyant density centrifugation. For some ipDNA-capsids, Nycodenz impermeability increases hydration and generates density so low that shell hyper-expansion must exist to accommodate associated water. Electron microscopy (EM confirmed hyper-expansion and low permeability and revealed that 3.0 mM magnesium ATP (physiological concentration causes contraction of hyper-expanded, lowpermeability ipDNA-capsids to less than mature size; 5.0 mM magnesium ATP (border of supraphysiological concentration or more disrupts them. Additionally, excess sodium ADP reverses 3.0 mM magnesium ATP-induced contraction and re-generates hyper-expansion. The Nycodenz impermeability implies assembly perfection that suggests selection for function in DNA packaging. These findings support the above challenge and can be explained via the assumption that T3 DNA packaging includes a back-up cycle of ATP-driven capsid contraction and hyper-expansion.

Effect of ATP sulfurylase overexpression in bright yellow 2 tobacco cells: regulation of ATP sulfurylase and SO4(-2) transport activities

International Nuclear Information System (INIS)

Hatzfeld, Y.; Cathala, N.; Grignon, C.; Davidian, J.C.

1998-01-01

To determine if the ATP sulfurylase reaction is a regulatory step for the SO4(2-)-assimilation pathway in plants, an Arabidopsis thaliana ATP sulfurylase cDNA, APS2, was fused to the 355 promoter of the cauliflower mosaic virus and introduced by Agrobacterium tumefaciens-mediated transformation into isolated Bright Yellow 2 tobacco (Nicotiana tabacum) cells. The ATP sulfurylase activity in transgenic cells was 8-fold that in control cells, and was correlated with the expression of a specific polypeptide revealed by western analysis using an anti-ATP sulfurylase antibody. The molecular mass of this polypeptide agreed with that for the overexpressed mature protein. ATP sulfurylase overexpression had no effect on [35S]SO4(2-) influx or ATP sulfurylase activity regulation by S availability, except that ATP sulfurylase activity variations in response to S starvation in transgenic cells were 8 times higher than in the wild type. There were also no differences in cell growth or sensitivity to SeO4(2-) (a toxic SO4(2-) analog) between transgenic and wild-type cells. We propose that in Bright Yellow 2 tobacco cells, the ATP sulfurylase derepression by S deficiency may involve a posttranscriptional mechanism, and that the ATP sulfurylase abundance is not limiting for cell metabolism

Extracellular ATP reduces HIV-1 transfer from immature dendritic cells to CD4+ T lymphocytes

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Barat Corinne

2008-03-01

Full Text Available Abstract Background Dendritic cells (DCs are considered as key mediators of the early events in human immunodeficiency virus type 1 (HIV-1 infection at mucosal sites. Previous studies have shown that surface-bound virions and/or internalized viruses found in endocytic vacuoles of DCs are efficiently transferred to CD4+ T cells. Extracellular adenosine triphosphate (ATP either secreted or released from necrotic cells induces a distorted maturation of DCs, transiently increases their endocytic capacity and affects their migratory capacity. Knowing that high extracellular ATP concentrations are present in situations of tissue injury and inflammation, we investigated the effect of ATP on HIV-1 transmission from DCs to CD4+ T lymphocytes. Results In this study, we show that extracellular ATP reduces HIV-1 transfer from immature monocyte-derived DCs (iDCs to autologous CD4+ T cells. This observed decrease in viral replication was related to a lower proportion of infected CD4+ T cells following transfer, and was seen with both X4- and R5-tropic isolates of HIV-1. Extracellular ATP had no effect on direct CD4+ T cell infection as well as on productive HIV-1 infection of iDCs. These observations indicate that extracellular ATP affects HIV-1 infection of CD4+ T cells in trans with no effect on de novo virus production by iDCs. Additional experiments suggest that extracellular ATP might modulate the trafficking pathway of internalized virions within iDCs leading to an increased lysosomal degradation, which could be partly responsible for the decreased HIV-1 transmission. Conclusion These results suggest that extracellular ATP can act as a factor controlling HIV-1 propagation.

Paracrine stimulation of P2X7 receptor by ATP activates a proliferative pathway in ovarian carcinoma cells.

Science.gov (United States)

Vázquez-Cuevas, Francisco G; Martínez-Ramírez, Angélica S; Robles-Martínez, Leticia; Garay, Edith; García-Carrancá, Alejandro; Pérez-Montiel, Delia; Castañeda-García, Carolina; Arellano, Rogelio O

2014-11-01

P2X7 is a purinergic receptor-channel; its activation by ATP elicits a broad set of cellular actions, from apoptosis to signals for survival. Here, P2X7 expression and function was studied in human ovarian carcinoma (OCA) cells, and biopsies from non-cancerous and cancer patients were analyzed by immunohistochemistry. Ovarian surface epithelium in healthy tissue expressed P2X7 at a high level that was maintained throughout the cancer. The cell lines SKOV-3 and CAOV-3 were used to investigate P2X7 functions in OCA. In SKOV-3 cells, selective stimulation of P2X7 by 2'(3')-O-(4-benzoylbenzoyl) adenosine-5'-triphosphate (BzATP) induced a dose-dependent increase of intracellular Ca(2+) concentration ([Ca(2+)](i)) but not cell death. Instead, BzATP increased the levels of phosphorylated ERK and AKT (pERK and pAKT), with an EC(50) of 44 ± 2 and 1.27 ± 0.5 μM, respectively; 10 μM BzATP evoked a maximum effect within 15 min that lasted for 120 min. Interestingly, basal levels of pERK and pAKT were decreased in the presence of apyrase in the medium, strongly suggesting an endogenous, ATP-mediated phenomenon. Accordingly: (i) mechanically stimulated cells generated a [Ca(2+)](i) increase that was abolished by apyrase; (ii) apyrase induced a decrease in culture viability, as measured by the MTS assay for mitochondrial activity; and (iii) incubation with 10 μM AZ10606120, a specific P2X7 antagonist and transfection with the dominant negative P2X7 mutant E496A, both reduced cell viability to 70.1 ± 8.9% and to 76.5 ± 5%, respectively, of control cultures. These observations suggested that P2X7 activity was auto-induced through ATP efflux; this increased pERK and pAKT levels that generated a positive feedback on cell viability. © 2014 Wiley Periodicals, Inc.

An ATP synthase harboring an atypical γ-subunit is involved in ATP synthesis in tomato fruit chromoplasts

DEFF Research Database (Denmark)

Pateraki, Irini; Renato, Marta; Azcõn-Bieto, Joaquín

2013-01-01

Chromoplasts are non-photosynthetic plastids specialized in the synthesis and accumulation of carotenoids. During fruit ripening, chloroplasts differentiate into photosynthetically inactive chromoplasts in a process characterized by the degradation of the thylakoid membranes, and by the active...... synthesis and accumulation of carotenoids. This transition renders chromoplasts unable to photochemically synthesize ATP, and therefore these organelles need to obtain the ATP required for anabolic processes through alternative sources. It is widely accepted that the ATP used for biosynthetic processes...... in non-photosynthetic plastids is imported from the cytosol or is obtained through glycolysis. In this work, however, we show that isolated tomato (Solanum lycopersicum) fruit chromoplasts are able to synthesize ATP de novo through a respiratory pathway using NADPH as an electron donor. We also report...

Control of ATP hydrolysis by ADP bound at the catalytic site of chloroplast ATP synthase as related to protonmotive force and Mg2+

International Nuclear Information System (INIS)

Du, Z.; Boyer, P.D.

1989-01-01

The activation of the ATP synthesis and hydrolysis capacity of isolated chloroplast membranes by protonmotive force is known to be associated with the release of tightly bound ADP from the ATP synthase. The data support the view that the activation requires only those structural changes occurring in the steady-state reaction mechanism. The trapping of ADP released during light activation or the chelation of Mg 2+ with EDTA effectively reduces the rate of decay of the ATPase activity. When the release of tightly bound ADP and Mg 2+ is promoted by light activation, followed by immediate dilution and washing to retard the rebinding of the ADP and Mg 2+ released, the ATPase activity remains high in the dark long after the protonmotive force has disappeared. After the addition of ADP and Mg 2+ the decay of the ATPase activity has the same characteristics as those of the unwashed chloroplast membrane. The results are interpreted as indicating that both Mg 2+ and ADP must be present prior to exposure to MgATP for the ATPase to be inhibited. However, in contrast to the isolated chloroplast ATPase, the steady-state activity of the membrane-bound ATPase is not inhibited by excess Mg 2+ . The replacement of [ 3 H]ADP from catalytic sites during hydrolysis of unlabeled ATP or during photophosphorylation with unlabeled ADP occurs as anticipated if Mg 2+ and ADP bound at one catalytic site without P i block catalysis by all three enzyme sites. The inhibited form induced by Mg 2+ and ADP may occur only under laboratory conditions and not have an in vivo role

Copper-induced apical trafficking of ATP7B in polarized hepatoma cells provides a mechanism for biliary copper excretion

NARCIS (Netherlands)

Roelofsen, H; Wolters, H; Van Luyn, MJA; Miura, N; Kuipers, F; Vonk, RJ

Background & Aims: Mutations in the ATP7B gene, encoding a copper-transporting P-type adenosine triphosphatase, lead to excessive hepatic copper accumulation because of impaired biliary copper excretion in Wilson's disease. In human liver, ATP7B is predominantly localized to the trans-Golgi network,

ATP1A3 Mutation in Adult Rapid-Onset Ataxia.

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Kathleen J Sweadner

Full Text Available A 21-year old male presented with ataxia and dysarthria that had appeared over a period of months. Exome sequencing identified a de novo missense variant in ATP1A3, the gene encoding the α3 subunit of Na,K-ATPase. Several lines of evidence suggest that the variant is causative. ATP1A3 mutations can cause rapid-onset dystonia-parkinsonism (RDP with a similar age and speed of onset, as well as severe diseases of infancy. The patient's ATP1A3 p.Gly316Ser mutation was validated in the laboratory by the impaired ability of the expressed protein to support the growth of cultured cells. In a crystal structure of Na,K-ATPase, the mutated amino acid was directly apposed to a different amino acid mutated in RDP. Clinical evaluation showed that the patient had many characteristics of RDP, however he had minimal fixed dystonia, a defining symptom of RDP. Successive magnetic resonance imaging (MRI revealed progressive cerebellar atrophy, explaining the ataxia. The absence of dystonia in the presence of other RDP symptoms corroborates other evidence that the cerebellum contributes importantly to dystonia pathophysiology. We discuss the possibility that a second de novo variant, in ubiquilin 4 (UBQLN4, a ubiquitin pathway component, contributed to the cerebellar neurodegenerative phenotype and differentiated the disease from other manifestations of ATP1A3 mutations. We also show that a homozygous variant in GPRIN1 (G protein-regulated inducer of neurite outgrowth 1 deletes a motif with multiple copies and is unlikely to be causative.

Sequential Action of MalE and Maltose Allows Coupling ATP Hydrolysis to Translocation in the MalFGK2 Transporter.

Science.gov (United States)

Bao, Huan; Dalal, Kush; Cytrynbaum, Eric; Duong, Franck

2015-10-16

ATP-binding cassette (ABC) transporters have evolved an ATP-dependent alternating-access mechanism to transport substrates across membranes. Despite important progress, especially in their structural analysis, it is still unknown how the substrate stimulates ATP hydrolysis, the hallmark of ABC transporters. In this study, we measure the ATP turnover cycle of MalFGK2 in steady and pre-steady state conditions. We show that (i) the basal ATPase activity of MalFGK2 is very low because the cleavage of ATP is rate-limiting, (ii) the binding of open-state MalE to the transporter induces ATP cleavage but leaves release of Pi limiting, and (iii) the additional presence of maltose stimulates release of Pi, and therefore increases the overall ATP turnover cycle. We conclude that open-state MalE stabilizes MalFGK2 in the outward-facing conformation until maltose triggers return to the inward-facing state for substrate and Pi release. This concerted action explains why ATPase activity of MalFGK2 depends on maltose, and why MalE is essential for transport. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Benfotiamine Counteracts Smoking-Induced Vascular Dysfunction in Healthy Smokers

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Alin Stirban

2012-01-01

Full Text Available Background. Smoking induces endothelial dysfunction (ED mainly by exacerbating oxidative stress (OS and inflammation. Benfotiamine, a thiamine prodrug with high bioavailability, prevents nicotine-induced vascular dysfunction in rats. It remained unknown whether this effect also occurs in humans. Methods. Therefore, 20 healthy volunteers (mean age: 38 years were investigated twice, 7–10 days apart in a randomized, cross-over, and investigator-blinded design. Vascular function was assessed by flow-mediated vasodilatation (FMD of the brachial artery and by measurements of the soluble vascular cell adhesion molecule (sVCAM-1. Investigations were performed after an overnight fast as well as 20 minutes after one cigarette smoking. On another day, the same procedure was applied following a 3-day oral therapy with benfotiamine (1050 mg/day. Ten patients were randomized to start with smoking alone, and ten started with benfotiamine. Results. Results are expressed as (mean ± SEM. Smoking acutely induced a decrease in FMD by 50% (∗∗P<0.001 versus baseline an effect significantly reduced by benfotiamine treatment to 25%∗§ (∗P<0.05 versus baseline, §P<0.05 versus smoking alone. Smoking-induced elevation in sVCAM-1 was also prevented by benfotiamine. The endothelium-independent vasodilatation remained unaltered between days. Conclusion. In healthy volunteers, smoking blunts vascular function mirrored by a decrease in FMD and an increase in sVCAM-1. Short-term treatment with benfotiamine significantly reduces these effects, showing protective vascular properties.

ATP-consuming and ATP-generating enzymes secreted by pancreas

DEFF Research Database (Denmark)

Yegutkin, Gennady G; Samburski, Sergei S; Jalkanen, Sirpa

2006-01-01

-generating enzymes in pancreatic juice, adenylate kinase, and NDP kinase, capable of sequentially phosphorylating AMP via ADP to ATP. Activities of nonspecific phosphatases, nucleotide pyrophosphatase/phosphodiesterases, and adenosine deaminase were negligible. Taken together, CCK-8 stimulation of pancreas causes...

Red Wine Inhibits Aggregation and Increases ATP-diphosphohydrolase (CD39) Activity of Rat Platelets in Vitro.

Science.gov (United States)

Caiazzo, Elisabetta; Tedesco, Idolo; Spagnuolo, Carmela; Russo, Gian Luigi; Ialenti, Armando; Cicala, Carla

2016-06-01

Moderate consumption of red wine has been shown to exert a peculiar cardioprotective effect compared with other alcoholic beverages; inhibition of platelet aggregation seems to be one of the mechanisms underlying this beneficial effect. CD39/ATP-diphosphohydrolase is an integral membrane glycoprotein metabolizing ATP and ADP to AMP; in concert with CD73/ecto-5'-nucleotidase, it contributes to extracellular adenosine accumulation. CD39 is considered a key modulator of thrombus formation; it inhibits platelet aggregation by promoting ADP hydrolysis. There is evidence that red wine consumption increases CD39 activity in platelets from streptozotocin-induced diabetic rats. Here we show that two kinds of Aglianico red wines inhibit aggregation and increase ATP--and ADPase activity in rat platelets.

Target-induced structure switching of hairpin aptamers for label-free and sensitive fluorescent detection of ATP via exonuclease-catalyzed target recycling amplification.

Science.gov (United States)

Xu, Yunying; Xu, Jin; Xiang, Yun; Yuan, Ruo; Chai, Yaqin

2014-01-15

In this work, we described the development of a new label-free, simple and sensitive fluorescent ATP sensing platform based on exonuclease III (Exo III)-catalyzed target recycling (ECTR) amplification and SYBR Green I indicator. The hairpin aptamer probes underwent conformational structure switching and re-configuration in the presence of ATP, which led to catalytic cleavage of the re-configured aptamers by Exo III to release ATP and to initiate the ECTR process. Such ECTR process resulted in the digestion of a significant number of the hairpin aptamer probes, leading to much less intercalation of SYBR Green I to the hairpin stems and drastic suppression of the fluorescence emission for sensitive ATP detection down to the low nanomolar level. Due to the highly specific affinity bindings between aptamers and ATP, the developed method exhibited excellent selectivity toward ATP against other analogous molecules. Besides, our ATP sensing approach used un-modified aptamer probes and could be performed in a "mix-and-detect" fashion in homogenous solutions. All these distinct advantages of the developed method thus made it hold great potential for the development of simple and robust sensing strategies for the detection of other small molecules. © 2013 Elsevier B.V. All rights reserved.

Interaction of ATP with a small heat shock protein from Mycobacterium leprae: effect on its structure and function.

Science.gov (United States)

Nandi, Sandip Kumar; Chakraborty, Ayon; Panda, Alok Kumar; Ray, Sougata Sinha; Kar, Rajiv Kumar; Bhunia, Anirban; Biswas, Ashis

2015-03-01

Adenosine-5'-triphosphate (ATP) is an important phosphate metabolite abundantly found in Mycobacterium leprae bacilli. This pathogen does not derive ATP from its host but has its own mechanism for the generation of ATP. Interestingly, this molecule as well as several antigenic proteins act as bio-markers for the detection of leprosy. One such bio-marker is the 18 kDa antigen. This 18 kDa antigen is a small heat shock protein (HSP18) whose molecular chaperone function is believed to help in the growth and survival of the pathogen. But, no evidences of interaction of ATP with HSP18 and its effect on the structure and chaperone function of HSP18 are available in the literature. Here, we report for the first time evidences of "HSP18-ATP" interaction and its consequences on the structure and chaperone function of HSP18. TNP-ATP binding experiment and surface plasmon resonance measurement showed that HSP18 interacts with ATP with a sub-micromolar binding affinity. Comparative sequence alignment between M. leprae HSP18 and αB-crystallin identified the sequence 49KADSLDIDIE58 of HSP18 as the Walker-B ATP binding motif. Molecular docking studies revealed that β4-β8 groove/strands as an ATP interactive region in M. leprae HSP18. ATP perturbs the tertiary structure of HSP18 mildly and makes it less susceptible towards tryptic cleavage. ATP triggers exposure of additional hydrophobic patches at the surface of HSP18 and induces more stability against chemical and thermal denaturation. In vitro aggregation and thermal inactivation assays clearly revealed that ATP enhances the chaperone function of HSP18. Our studies also revealed that the alteration in the chaperone function of HSP18 is reversible and is independent of ATP hydrolysis. As the availability and binding of ATP to HSP18 regulates its chaperone function, this functional inflection may play an important role in the survival of M. leprae in hosts.

Exposure to high glutamate concentration activates aerobic glycolysis but inhibits ATP-linked respiration in cultured cortical astrocytes.

Science.gov (United States)

Shen, Yao; Tian, Yueyang; Shi, Xiaojie; Yang, Jianbo; Ouyang, Li; Gao, Jieqiong; Lu, Jianxin

2014-08-01

Astrocytes play a key role in removing the synaptically released glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. However, high concentration of glutamate leads to toxicity in astrocytes, and the underlying mechanisms are unclear. The purpose of this study was to investigate whether energy metabolism disorder, especially impairment of mitochondrial respiration, is involved in the glutamate-induced gliotoxicity. Exposure to 10-mM glutamate for 48 h stimulated glycolysis and respiration in astrocytes. However, the increased oxygen consumption was used for proton leak and non-mitochondrial respiration, but not for oxidative phosphorylation and ATP generation. When the exposure time extended to 72 h, glycolysis was still activated for ATP generation, but the mitochondrial ATP-linked respiration of astrocytes was reduced. The glutamate-induced astrocyte damage can be mimicked by the non-metabolized substrate d-aspartate but reversed by the non-selective glutamate transporter inhibitor TBOA. In addition, the glutamate toxicity can be partially reversed by vitamin E. These findings demonstrate that changes of bioenergetic profile occur in cultured cortical astrocytes exposed to high concentration of glutamate and highlight the role of mitochondria respiration in glutamate-induced gliotoxicity in cortical astrocytes. Copyright © 2014 John Wiley & Sons, Ltd.

Increased level of extracellular ATP at tumor sites: in vivo imaging with plasma membrane luciferase.

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Patrizia Pellegatti

2008-07-01

Full Text Available There is growing awareness that tumour cells build up a "self-advantageous" microenvironment that reduces effectiveness of anti-tumour immune response. While many different immunosuppressive mechanisms are likely to come into play, recent evidence suggests that extracellular adenosine acting at A2A receptors may have a major role in down-modulating the immune response as cancerous tissues contain elevated levels of adenosine and adenosine break-down products. While there is no doubt that all cells possess plasma membrane adenosine transporters that mediate adenosine uptake and may also allow its release, it is now clear that most of extracellularly-generated adenosine originates from the catabolism of extracellular ATP.Measurement of extracellular ATP is generally performed in cell supernatants by HPLC or soluble luciferin-luciferase assay, thus it generally turns out to be laborious and inaccurate. We have engineered a chimeric plasma membrane-targeted luciferase that allows in vivo real-time imaging of extracellular ATP. With this novel probe we have measured the ATP concentration within the tumour microenvironment of several experimentally-induced tumours.Our results show that ATP in the tumour interstitium is in the hundreds micromolar range, while it is basically undetectable in healthy tissues. Here we show that a chimeric plasma membrane-targeted luciferase allows in vivo detection of high extracellular ATP concentration at tumour sites. On the contrary, tumour-free tissues show undetectable extracellular ATP levels. Extracellular ATP may be crucial for the tumour not only as a stimulus for growth but also as a source of an immunosuppressive agent such as adenosine. Our approach offers a new tool for the investigation of the biochemical composition of tumour milieu and for development of novel therapies based on the modulation of extracellular purine-based signalling.

Age-dependent impact of Ca_V3.2 T-type calcium channel deletion on myogenic tone and flow-mediated vasodilatation in small arteries

DEFF Research Database (Denmark)

Mikkelsen, Miriam F.; Björling, Karl; Jensen, Lars Jørn

2016-01-01

, structural remodeling, and mRNA + protein expression in small mesenteric arteries from CaV3.2 knock-out vs. wild-type mice at young vs. mature adult age. In young mice, only, deletion of CaV3.2 led to enhanced myogenic response and ∼50 % reduction of flow-mediated vasodilatation. Ni(2+) had both CaV3...

Control of ATP hydrolysis by ADP bound at the catalytic site of chloroplast ATP synthase as related to protonmotive force and Mg sup 2+

Energy Technology Data Exchange (ETDEWEB)

Du, Z.; Boyer, P.D. (Univ. of California, Los Angeles (USA))

1989-01-24

The activation of the ATP synthesis and hydrolysis capacity of isolated chloroplast membranes by protonmotive force is known to be associated with the release of tightly bound ADP from the ATP synthase. The data support the view that the activation requires only those structural changes occurring in the steady-state reaction mechanism. The trapping of ADP released during light activation or the chelation of Mg{sup 2+} with EDTA effectively reduces the rate of decay of the ATPase activity. When the release of tightly bound ADP and Mg{sup 2+} is promoted by light activation, followed by immediate dilution and washing to retard the rebinding of the ADP and Mg{sup 2+} released, the ATPase activity remains high in the dark long after the protonmotive force has disappeared. After the addition of ADP and Mg{sup 2+} the decay of the ATPase activity has the same characteristics as those of the unwashed chloroplast membrane. The results are interpreted as indicating that both Mg{sup 2+} and ADP must be present prior to exposure to MgATP for the ATPase to be inhibited. However, in contrast to the isolated chloroplast ATPase, the steady-state activity of the membrane-bound ATPase is not inhibited by excess Mg{sup 2+}. The replacement of ({sup 3}H)ADP from catalytic sites during hydrolysis of unlabeled ATP or during photophosphorylation with unlabeled ADP occurs as anticipated if Mg{sup 2+} and ADP bound at one catalytic site without P{sub i} block catalysis by all three enzyme sites. The inhibited form induced by Mg{sup 2+} and ADP may occur only under laboratory conditions and not have an in vivo role.

Acetone and Butanone Metabolism of the Denitrifying Bacterium “Aromatoleum aromaticum” Demonstrates Novel Biochemical Properties of an ATP-Dependent Aliphatic Ketone Carboxylase

Science.gov (United States)

Schühle, Karola

2012-01-01

The anaerobic and aerobic metabolism of acetone and butanone in the betaproteobacterium “Aromatoleum aromaticum” is initiated by their ATP-dependent carboxylation to acetoacetate and 3-oxopentanoic acid, respectively. Both reactions are catalyzed by the same enzyme, acetone carboxylase, which was purified and characterized. Acetone carboxylase is highly induced under growth on acetone or butanone and accounts for at least 5.5% of total cell protein. The enzyme consists of three subunits of 85, 75, and 20 kDa, respectively, in a (αβγ)2 composition and contains 1 Zn and 2 Fe per heterohexamer but no organic cofactors. Chromatographic analysis of the ATP hydrolysis products indicated that ATP was exclusively cleaved to AMP and 2 Pi. The stoichiometry was determined to be 2 ATP consumed per acetone carboxylated. Purified acetone carboxylase from A. aromaticum catalyzes the carboxylation of acetone and butanone as the only substrates. However, the enzyme shows induced (uncoupled) ATPase activity with many other substrates that were not carboxylated. Acetone carboxylase is a member of a protein family that also contains acetone carboxylases of various other organisms, acetophenone carboxylase of A. aromaticum, and ATP-dependent hydantoinases/oxoprolinases. While the members of this family share several characteristic features, they differ with respect to the products of ATP hydrolysis, subunit composition, and metal content. PMID:22020645

Activation of ATP-sensitive potassium channel by iptakalim normalizes stress-induced HPA axis disorder and depressive behaviour by alleviating inflammation and oxidative stress in mouse hypothalamus.

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Zhao, Xiao-Jie; Zhao, Zhan; Yang, Dan-Dan; Cao, Lu-Lu; Zhang, Ling; Ji, Juan; Gu, Jun; Huang, Ji-Ye; Sun, Xiu-Lan

2017-04-01

Stress-induced disturbance of the hypothalamic-pituitary-adrenal (HPA) axis is strongly implicated in incidence of mood disorders. A heightened neuroinflammatory response and oxidative stress play a fundamental role in the dysfunction of the HPA axis. We have previously demonstrated that iptakalim (Ipt), a new ATP-sensitive potassium (K-ATP) channel opener, could prevent oxidative injury and neuroinflammation against multiple stimuli-induced brain injury. The present study was to demonstrate the impacts of Ipt in stress-induced HPA axis disorder and depressive behavior. We employed 2 stress paradigms: 8 weeks of continuous restraint stress (chronic restraint stress, CRS) and 2h of restraint stress (acute restraint stress, ARS), to mimic both chronic stress and severe acute stress. Prolonged (4 weeks) and short-term (a single injection) Ipt treatment was administered 30min before each stress paradigm. We found that HPA axis was altered after stress, with different responses to CRS (lower ACTH and CORT, higher AVP, but normal CRH) and ARS (higher CRH, ACTH and CORT, but normal AVP). Both prolonged and short-term Ipt treatment normalized stress-induced HPA axis disorders and abnormal behaviors in mice. CRS and ARS up-regulated mRNA levels of inflammation-related molecules (TNFα, IL-1β, IL-6 and TLR4) and oxidative stress molecules (gp91phox, iNOS and Nrf2) in the mouse hypothalamus. Double immunofluorescence showed CRS and ARS increased microglia activation (CD11b and TNFα) and oxidative stress in neurons (NeuN and gp91phox), which were alleviated by Ipt. Therefore, the present study reveals that Ipt could prevent against stress-induced HPA axis disorders and depressive behavior by alleviating inflammation and oxidative stress in the hypothalamus. Copyright © 2017 Elsevier Inc. All rights reserved.

Mutations in valosin-containing protein (VCP) decrease ADP/ATP translocation across the mitochondrial membrane and impair energy metabolism in human neurons.

Science.gov (United States)

Ludtmann, Marthe H R; Arber, Charles; Bartolome, Fernando; de Vicente, Macarena; Preza, Elisavet; Carro, Eva; Houlden, Henry; Gandhi, Sonia; Wray, Selina; Abramov, Andrey Y

2017-05-26

Mutations in the gene encoding valosin-containing protein (VCP) lead to multisystem proteinopathies including frontotemporal dementia. We have previously shown that patient-derived VCP mutant fibroblasts exhibit lower mitochondrial membrane potential, uncoupled respiration, and reduced ATP levels. This study addresses the underlying basis for mitochondrial uncoupling using VCP knockdown neuroblastoma cell lines, induced pluripotent stem cells (iPSCs), and iPSC-derived cortical neurons from patients with pathogenic mutations in VCP Using fluorescent live cell imaging and respiration analysis we demonstrate a VCP mutation/knockdown-induced dysregulation in the adenine nucleotide translocase, which results in a slower rate of ADP or ATP translocation across the mitochondrial membranes. This deregulation can explain the mitochondrial uncoupling and lower ATP levels in VCP mutation-bearing neurons via reduced ADP availability for ATP synthesis. This study provides evidence for a role of adenine nucleotide translocase in the mechanism underlying altered mitochondrial function in VCP-related degeneration, and this new insight may inform efforts to better understand and manage neurodegenerative disease and other proteinopathies. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Rate of hydrolysis in ATP synthase is fine-tuned by  -subunit motif controlling active site conformation

KAUST Repository

Beke-Somfai, T.; Lincoln, P.; Norden, B.

2013-01-01

Computer-designed artificial enzymes will require precise understanding of how conformation of active sites may control barrier heights of key transition states, including dependence on structure and dynamics at larger molecular scale. F(o)F(1) ATP synthase is interesting as a model system: a delicate molecular machine synthesizing or hydrolyzing ATP using a rotary motor. Isolated F(1) performs hydrolysis with a rate very sensitive to ATP concentration. Experimental and theoretical results show that, at low ATP concentrations, ATP is slowly hydrolyzed in the so-called tight binding site, whereas at higher concentrations, the binding of additional ATP molecules induces rotation of the central γ-subunit, thereby forcing the site to transform through subtle conformational changes into a loose binding site in which hydrolysis occurs faster. How the 1-Å-scale rearrangements are controlled is not yet fully understood. By a combination of theoretical approaches, we address how large macromolecular rearrangements may manipulate the active site and how the reaction rate changes with active site conformation. Simulations reveal that, in response to γ-subunit position, the active site conformation is fine-tuned mainly by small α-subunit changes. Quantum mechanics-based results confirm that the sub-Ångström gradual changes between tight and loose binding site structures dramatically alter the hydrolysis rate.

Rate of hydrolysis in ATP synthase is fine-tuned by  -subunit motif controlling active site conformation

KAUST Repository

Beke-Somfai, T.

2013-01-23

Computer-designed artificial enzymes will require precise understanding of how conformation of active sites may control barrier heights of key transition states, including dependence on structure and dynamics at larger molecular scale. F(o)F(1) ATP synthase is interesting as a model system: a delicate molecular machine synthesizing or hydrolyzing ATP using a rotary motor. Isolated F(1) performs hydrolysis with a rate very sensitive to ATP concentration. Experimental and theoretical results show that, at low ATP concentrations, ATP is slowly hydrolyzed in the so-called tight binding site, whereas at higher concentrations, the binding of additional ATP molecules induces rotation of the central γ-subunit, thereby forcing the site to transform through subtle conformational changes into a loose binding site in which hydrolysis occurs faster. How the 1-Å-scale rearrangements are controlled is not yet fully understood. By a combination of theoretical approaches, we address how large macromolecular rearrangements may manipulate the active site and how the reaction rate changes with active site conformation. Simulations reveal that, in response to γ-subunit position, the active site conformation is fine-tuned mainly by small α-subunit changes. Quantum mechanics-based results confirm that the sub-Ångström gradual changes between tight and loose binding site structures dramatically alter the hydrolysis rate.

Protection against Mitochondrial and Metal Toxicity Depends on Functional Lipid Binding Sites in ATP13A2

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Shaun Martin

2016-01-01

Full Text Available The late endo-/lysosomal P-type ATPase ATP13A2 (PARK9 is implicated in Parkinson’s disease (PD and Kufor-Rakeb syndrome, early-onset atypical Parkinsonism. ATP13A2 interacts at the N-terminus with the signaling lipids phosphatidic acid (PA and phosphatidylinositol (3,5 bisphosphate (PI(3,5P2, which modulate ATP13A2 activity under cellular stress conditions. Here, we analyzed stable human SHSY5Y cell lines overexpressing wild-type (WT or ATP13A2 mutants in which three N-terminal lipid binding sites (LBS1–3 were mutated. We explored the regulatory role of LBS1–3 in the cellular protection by ATP13A2 against mitochondrial stress induced by rotenone and found that the LBS2-3 mutants displayed an abrogated protective effect. Moreover, in contrast to WT, the LBS2 and LBS3 mutants responded poorly to pharmacological inhibition of, respectively, PI(3,5P2 and PA formation. We further demonstrate that PA and PI(3,5P2 are also required for the ATP13A2-mediated protection against the toxic metals Mn2+, Zn2+, and Fe3+, suggesting a general lipid-dependent activation mechanism of ATP13A2 in various PD-related stress conditions. Our results indicate that the ATP13A2-mediated protection requires binding of PI(3,5P2 to LBS2 and PA to LBS3. Thus, targeting the N-terminal lipid binding sites of ATP13A2 might offer a therapeutic approach to reduce cellular toxicity of various PD insults including mitochondrial stress.

UTP-induced ATP release is a fine-tuned signalling pathway in osteocytes

DEFF Research Database (Denmark)

Kringelbach, Tina M.; Aslan, Derya; Novak, Ivana

2014-01-01

Osteocytes reside as a cellular network throughout the mineralised matrix of bone and are considered the primary mechanosensors of this tissue. They sense mechanical stimulation such as fluid flow and are able to regulate osteoblast and osteoclast functions on the bone surface. Previously, we fou...... signals may be propagated by P2 receptor activation and further ATP release in the osteocyte network and implicate purinergic signalling as a central signalling pathway in osteocyte mechanotransduction....

CdTe amplification nanoplatforms capped with thioglycolic acid for electrochemical aptasensing of ultra-traces of ATP

Energy Technology Data Exchange (ETDEWEB)

Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, P.O. Box 67149-67346, Kermanshah (Iran, Islamic Republic of); Farzin, Leila [Department of Analytical Chemistry, School of Chemistry, College of Science, University of Tehran, P.O. Box 14174-66191, Tehran (Iran, Islamic Republic of); Tabrizi, Mahmoud Amouzadeh [Research Center for Science and Technology in Medicine,Tehran University of Medical Sciences, P.O. Box 14197-33131, Tehran (Iran, Islamic Republic of); Shanehsaz, Maryam [Analytical Chemistry Research Laboratory, Mobin Shimi Azma Company, P.O. Box 14768-44949, Tehran (Iran, Islamic Republic of)

2016-12-01

A “signal off” voltammetric aptasensor was developed for the sensitive and selective detection of ultra-low levels of adenosine triphosphate (ATP). For this purpose, a new strategy based on the principle of recognition-induced switching of aptamers from DNA/DNA duplex to DNA/target complex was designed using thioglycolic acid (TGA)-capped CdTe quantum dots (QDs) as the signal amplifying nano-platforms. Owing to the small size, high surface-to-volume ratio and good conductivity, quantum dots were immobilized on the electrode surface for signal amplification. In this work, methylene blue (MB) adsorbed to DNA was used as a sensitive redox reporter. The intensity of voltammetric signal of MB was found to decrease linearly upon ATP addition over a concentration range of 0.1 nM to 1.6 μM with a correlation coefficient of 0.9924. Under optimized conditions, the aptasensor was able to selectively detect ATP with a limit of detection of 45 pM at 3σ. The results also demonstrated that the QDs-based amplification strategy could be feasible for ATP assay and presented a potential universal method for other small biomolecular aptasensors. - Highlights: • A “signal off” voltammetric aptasensor has been reported. • The DPV technique was used for the determination of ATP. • The determination of ATP up to 1.6 μM with a detection limit 45 pM, respectively.

Sarcolemmal cardiac K(ATP) channels as a target for the cardioprotective effects of the fluorine-containing pinacidil analogue, flocalin.

Science.gov (United States)

Voitychuk, Oleg I; Strutynskyi, Ruslan B; Yagupolskii, Lev M; Tinker, Andrew; Moibenko, Olexiy O; Shuba, Yaroslav M

2011-02-01

A class of drugs known as K(ATP) -channel openers induce cardioprotection. This study examined the effects of the novel K(ATP) -channel opener, the fluorine-containing pinacidil derivative, flocalin, on cardiac-specific K(ATP) -channels, excitability of native cardiac myocytes and on the ischaemic heart. The action of flocalin was investigated on: (i) membrane currents through cardiac-specific K(ATP) -channels (I(KATP) ) formed by K(IR) 6.2/SUR2A heterologously expressed in HEK-293 cells (HEK-293(₆.₂/₂A) ); (ii) excitability and intracellular Ca²(+) ([Ca²(+) ](i) ) transients of cultured rat neonatal cardiac myocytes; and (iii) functional and ultrastructural characteristics of isolated guinea-pig hearts subjected to ischaemia-reperfusion. Flocalin concentration-dependently activated a glibenclamide-sensitive I(KATP) in HEK-293(₆.₂/₂A) cells with an EC₅₀= 8.1 ± 0.4 µM. In cardiac myocytes, flocalin (5 µM) hyperpolarized resting potential by 3-5 mV, markedly shortened action potential duration, reduced the amplitude of [Ca²(+) ](i) transients by 2-3-fold and suppressed contraction. The magnitude and extent of reversibility of these effects depended on the type of cardiac myocytes. In isolated hearts, perfusion with 5 µmol·L⁻¹ flocalin, before inducing ischaemia, facilitated restoration of contraction during reperfusion, decreased the number of extrasystoles, prevented the appearance of coronary vasoconstriction and reduced damage to the cardiac tissue at the ultrastructural level (state of myofibrils, membrane integrity, mitochondrial cristae structure). Flocalin induced potent cardioprotection by activating cardiac-type K(ATP) -channels with all the benefits of the presence of fluorine group in the drug structure: higher lipophilicity, decreased toxicity, resistance to oxidation and thermal degradation, decreased metabolism in the organism and prolonged therapeutic action. © 2011 The Authors. British Journal of Pharmacology © 2011 The

P2X receptor-mediated ATP purinergic signaling in health and disease

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Jiang LH

2012-09-01

Full Text Available Lin-Hua JiangSchool of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United KingdomAbstract: Purinergic P2X receptors are plasma membrane proteins present in a wide range of mammalian cells where they act as a cellular sensor, enabling cells to detect and respond to extracellular adenosine triphosphate (ATP, an important signaling molecule. P2X receptors function as ligand-gated Ca2+-permeable cationic channels that open upon ATP binding to elevate intracellular Ca2+ concentrations and cause membrane depolarization. In response to sustained activation, P2X receptors induce formation of a pore permeable to large molecules. P2X receptors also interact with distinct functional proteins and membrane lipids to form specialized signaling complexes. Studies have provided compelling evidence to show that such P2X receptor-mediated ATP-signaling mechanisms determine and regulate a growing number and diversity of important physiological processes, including neurotransmission, muscle contraction, and cytokine release. There is accumulating evidence to support strong causative relationships of altered receptor expression and function with chronic pain, inflammatory diseases, cancers, and other pathologies or diseases. Numerous high throughput screening drug discovery programs and preclinical studies have thus far demonstrated the proof of concepts that the P2X receptors are druggable targets and selective receptor antagonism is a promising therapeutics approach. This review will discuss the recent progress in understanding the mammalian P2X receptors with respect to the ATP-signaling mechanisms, physiological and pathophysiological roles, and development and preclinical studies of receptor antagonists.Keywords: extracellular ATP, ion channel, large pore, signaling complex, chronic pain, inflammatory diseases

ATP-independent DNA synthesis in Vaccinia-infected L cells

International Nuclear Information System (INIS)

Berger, N.A.; Kauff, R.A.; Sikorski, G.W.

1978-01-01

Mouse L cells can be made permeable to exogenous nucleotides by a cold shock in 0.01 M Tris . HCl pH 7.8, 0.25 M sucrose, 1 mM EDTA, 30 mM 2-mercaptoethanol and 4 mM MgCl 2 . DNA synthesis in permeabilized L cells requires ATP whereas DNA synthesis in permeabilized L cells that are infected with Vaccinia virus is ATP-independent. Permeabilized L cells that are infected with ultraviolet-irradiated virus show a marked suppression of DNA synthesis which is not corrected by an excess of deoxynucleoside triphosphates and ATP. The ATP-dependent and ATP-independent processes of DNA synthesis are inhibited to the same extent by Mal-Net, pHMB, ara CTP and phosphonoacetate. Concentrations of daunorubicin and cytembena, which cause marked inhibition of the ATP-dependent enzymes, only cause partial inhibition of the ATP-independent enzymes. (Auth.)

X-ray effects on the activity of a Mg2+-dependent, Na+- and K+-activable microsomal membrane ATP-ase system

International Nuclear Information System (INIS)

Froehlich, D.

1978-01-01

The bahviour of a Mg 2+ -dependent, Na + - and K + -activable ATP-ase sytem on irradiation was investigated using a microsome fraction of guinea pig myocardial cells prepared by fractionated centrifugation. The Na + - and K + -activable component, transport-ATPase, was particularly radiation-sensitive. Three stages of development were observed for a 1,500 R radiation damage until 24 h p.r.. In the first stage, until 30 minutes p.r., the activity of transport-ATP-ase was inhibited. This was followed by repair processes which had reached a peak value clearly higher than the control values at 4 hours p.r.. In the third stage, the activity was reduced again; 15 and 24 hours after termination of exposure, values again were nearly the same as after 30 minutes where a maximum was observed for this radiation dose. Radiation-induced electrolyte displacements, active transport, and radiation-induced inhibition of transport-ATP-ase were correlated and discussed; the assumption was that changes in, the electrolyte conditions in the membranes on irradiation are at least partly due to the described inhibition of transport-ATP-ase. (orig./AJ) [de

Determination of glucose deficiency-induced cell death by mitochondrial ATP generation-driven proton homeostasis

Institute of Scientific and Technical Information of China (English)

Yanfen Cui; Yuanyuan Wang; Miao Liu; Li Qiu; Pan Xing; Xin Wang; Guoguang Ying; Binghui Li

2017-01-01

Glucose is one of major nutrients and its catabolism provides energy and/or building bricks for cell proliferation.Glucose deficiency results in cell death.However,the underlying mechanism still remains elusive.By using our recently developed method to monitor real-time cellular apoptosis and necrosis,we show that glucose deprivation can directly elicit necrosis,which is promoted by mitochondrial impairment,depending on mitochondrial adenosine triphosphate (ATP) generation instead of ATP depletion.We demonstrate that glucose metabolism is the major source to produce protons.Glucose deficiency leads to lack of proton provision while mitochondrial electron transfer chain continues consuming protons to generate energy,which provokes a compensatory iysosomal proton effiux and resultant increased lysosomal pH.This lysosomal alkalinization can trigger apoptosis or necrosis depending on the extent of alkalinization.Taken together,our results build up a metabolic connection between glycolysis,mitochondrion,and lysosome,and reveal an essential role of glucose metabolism in maintaining proton homeostasis to support cell survival.

Influence exerted by new pyrimidine derivatives on cerebral circulation auto-regulation and vasodilatating function of vessels endothelium in rats' brains under chronic hemic hypoxia

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A.V. Voronkov

2018-03-01

Full Text Available Our research goal was to examine influences exerted by new pyrimidine derivatives coded as BL0 and BL2 on cerebral hemodynamics auto-regulation parameters and vasodilatating function of vessels endothelium as risk factors causing ischemic and hemorrhagic strokes under chronic hemic hypoxia. We performed an experiment on white Wistar rats to prove that endothelial dysfunction which evolves under chronic hemic hypoxia leads to disorders in endothelium-mediated mechanisms for cerebral circulation auto-regulation in rats. We modeled hypoxia in animals via granting them free access to 0.2 % sodium nitrite solution instead of ordinary drinking water. Endothelial dysfunction was confirmed as per disorders in vasodilatation and vasoconstriction reactions at intravenous introduction of acetyl choline (0.1 mg/kg and methyl ether hydrochloride nitro-L-arginine (10 mg/kg. Cerebral blood flow speed was measured with MM-D-K-Minimax v.2.1. ultrasound Doppler. We assessed cerebral circulation auto-regulation as per compression test results which allowed us to calculate overshoot coefficient and auto-regulation power. Examined pyrimidine derivatives and comparison preparations were introduced orally 60 minutes prior to taking readings. Mexidol doses were calculated on the basis of interspecific recalculation of a maximum daily dose for a man. Nicergoline dose was taken as a most effective one as per literature data. When new pyrimidine derivatives BL0 and BL2 are applied under chronic hemic hypoxia, it causes overshoot coefficient to grow authentically higher than in a negative control group but it doesn't exert any positive influence on collateral reserve parameter, namely auto-regulation power. BL0 and BL2 improve endothelium vasodilatating function at intravenous acetylcholine introduction (0.1 mg/kg and don't exert any influence on vasoconstricting function at L-NAME intravenous introduction (10 mg/kg. The examined substance BL0 has more apparent

Lysosomal Storage of Subunit c of Mitochondrial ATP Synthase in Brain-Specific Atp13a2-Deficient Mice.

Science.gov (United States)

Sato, Shigeto; Koike, Masato; Funayama, Manabu; Ezaki, Junji; Fukuda, Takahiro; Ueno, Takashi; Uchiyama, Yasuo; Hattori, Nobutaka

2016-12-01

Kufor-Rakeb syndrome (KRS) is an autosomal recessive form of early-onset parkinsonism linked to the PARK9 locus. The causative gene for KRS is Atp13a2, which encodes a lysosomal type 5 P-type ATPase. We recently showed that KRS/PARK9-linked mutations lead to several lysosomal alterations, including reduced proteolytic processing of cathepsin D in vitro. However, it remains unknown how deficiency of Atp13a2 is connected to lysosomal impairments. To address this issue, we analyzed brain tissues of Atp13a2 conditional-knockout mice, which exhibited characteristic features of neuronal ceroid lipofuscinosis, including accumulation of lipofuscin positive for subunit c of mitochondrial ATP synthase, suggesting that a common pathogenic mechanism underlies both neuronal ceroid lipofuscinosis and Parkinson disease. Copyright © 2016 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Genetic variation in ATP5O is associated with skeletal muscle ATP50 mRNA expression and glucose uptake in young twins.

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Tina Rönn

Full Text Available BACKGROUND: Impaired oxidative capacity of skeletal muscle mitochondria contribute to insulin resistance and type 2 diabetes (T2D. Furthermore, mRNA expression of genes involved in oxidative phosphorylation, including ATP5O, is reduced in skeletal muscle from T2D patients. Our aims were to investigate mechanisms regulating ATP5O expression in skeletal muscle and association with glucose metabolism, and the relationship between ATP5O single nucleotide polymorphisms (SNPs and risk of T2D. METHODOLOGY/PRINCIPAL FINDINGS: ATP5O mRNA expression was analyzed in skeletal muscle from young (n = 86 and elderly (n = 68 non-diabetic twins before and after a hyperinsulinemic euglycemic clamp. 11 SNPs from the ATP5O locus were genotyped in the twins and a T2D case-control cohort (n = 1466. DNA methylation of the ATP5O promoter was analyzed in twins (n = 22 using bisulfite sequencing. The mRNA level of ATP5O in skeletal muscle was reduced in elderly compared with young twins, both during basal and insulin-stimulated conditions (p<0.0005. The degree of DNA methylation around the transcription start of ATP5O was <1% in both young and elderly twins and not associated with mRNA expression (p = 0.32. The mRNA level of ATP5O in skeletal muscle was positively related to insulin-stimulated glucose uptake (regression coefficient = 6.6; p = 0.02. Furthermore, two SNPs were associated with both ATP5O mRNA expression (rs12482697: T/T versus T/G; p = 0.02 and rs11088262: A/A versus A/G; p = 0.004 and glucose uptake (rs11088262: A/A versus A/G; p = 0.002 and rs12482697: T/T versus T/G; p = 0.005 in the young twins. However, we could not detect any genetic association with T2D. CONCLUSIONS/SIGNIFICANCE: Genetic variation and age are associated with skeletal muscle ATP5O mRNA expression and glucose disposal rate, suggesting that combinations of genetic and non-genetic factors may cause the reduced expression of ATP5O in T2D muscle. These findings propose a role for ATP5O, in

Curcumin attenuates Cr(VI)-induced ascites and changes in the activity of aconitase and F(1)F(0) ATPase and the ATP content in rat liver mitochondria.

Science.gov (United States)

García-Niño, Wylly Ramsés; Zazueta, Cecilia; Tapia, Edilia; Pedraza-Chaverri, José

2014-11-01

Occupational and environmental exposure to potassium dichromate (K2Cr2O7), a hexavalent chromium compound, can result in liver damage associated with oxidative stress and mitochondrial dysfunction. The purpose of this study was to evaluate the effect of the antioxidant curcumin (400 mg/kg b.w.) on the K2Cr2O7-induced injury, with special emphasis on ascitic fluid accumulation and oxidative phosphorylation mitochondrial enzymes and the adenosine triphosphate (ATP) levels in isolated mitochondria from livers of rats treated with K2Cr2O7 (15 mg/kg b.w.). Thus, curcumin attenuated the ascites generation, prevented the decrease in the activities of aconitase and F1F0 ATPase, and maintained the ATP levels. The activity of complex II was not completely reestablished by curcumin, whereas complexes III and IV activities were unchanged. © 2014 Wiley Periodicals, Inc.

Identification of a new Mpl-interacting protein, Atp5d.

Science.gov (United States)

Liu, Hongyan; Zhao, Zhenhu; Zhong, Yuxu; Shan, Yajun; Sun, Xiaohong; Mao, Bingzhi; Cong, Yuwen

2014-06-01

Thrombopoietin (TPO) can regulate hematopoiesis and megakaryopoiesis via activation of its receptor, c-Mpl, and multiple downstream signal transduction pathways. Using the cytoplasmic domain of Mpl as bait, we performed yeast two-hybrid screening, and found that the protein Atp5d might associate with Mpl. Atp5d is known as the δ subunit of mitochondrial ATP synthase, but little is known about the function of dissociative Atp5d. The interaction between Mpl and Atp5d was confirmed by the yeast two-hybrid system, mammalian two-hybrid assay, pull-down experiment, and co-immunoprecipitation study in vivo and in vitro. An additional immunofluorescence assay showed that the two proteins can colocalize along the plasma membrane in the cytoplasm. Using the yeast two-hybrid system, we tested a series of cytoplasmic truncated mutations for their ability to bind Atp5d and found an association between Atp5d and the Aa98-113 domain of Mpl. The dissociation of Atp5d from Mpl after TPO stimulation suggests that Atp5d may be a new component of TPO signaling.

Binding of ATP by pertussis toxin and isolated toxin subunits

International Nuclear Information System (INIS)

Hausman, S.Z.; Manclark, C.R.; Burns, D.L.

1990-01-01

The binding of ATP to pertussis toxin and its components, the A subunit and B oligomer, was investigated. Whereas, radiolabeled ATP bound to the B oligomer and pertussis toxin, no binding to the A subunit was observed. The binding of [ 3 H]ATP to pertussis toxin and the B oligomer was inhibited by nucleotides. The relative effectiveness of the nucleotides was shown to be ATP > GTP > CTP > TTP for pertussis toxin and ATP > GTP > TTP > CTP for the B oligomer. Phosphate ions inhibited the binding of [ 3 H]ATP to pertussis toxin in a competitive manner; however, the presence of phosphate ions was essential for binding of ATP to the B oligomer. The toxin substrate, NAD, did not affect the binding of [ 3 H]ATP to pertussis toxin, although the glycoprotein fetuin significantly decreased binding. These results suggest that the binding site for ATP is located on the B oligomer and is distinct from the enzymatically active site but may be located near the eukaryotic receptor binding site

Binding of ATP by pertussis toxin and isolated toxin subunits

Energy Technology Data Exchange (ETDEWEB)

Hausman, S.Z.; Manclark, C.R.; Burns, D.L. (Center for Biologics Evaluation and Research, Bethesda, MD (USA))

1990-07-03

The binding of ATP to pertussis toxin and its components, the A subunit and B oligomer, was investigated. Whereas, radiolabeled ATP bound to the B oligomer and pertussis toxin, no binding to the A subunit was observed. The binding of ({sup 3}H)ATP to pertussis toxin and the B oligomer was inhibited by nucleotides. The relative effectiveness of the nucleotides was shown to be ATP > GTP > CTP > TTP for pertussis toxin and ATP > GTP > TTP > CTP for the B oligomer. Phosphate ions inhibited the binding of ({sup 3}H)ATP to pertussis toxin in a competitive manner; however, the presence of phosphate ions was essential for binding of ATP to the B oligomer. The toxin substrate, NAD, did not affect the binding of ({sup 3}H)ATP to pertussis toxin, although the glycoprotein fetuin significantly decreased binding. These results suggest that the binding site for ATP is located on the B oligomer and is distinct from the enzymatically active site but may be located near the eukaryotic receptor binding site.

Evidence that Na+/H+ exchanger 1 is an ATP-binding protein.

Science.gov (United States)

Shimada-Shimizu, Naoko; Hisamitsu, Takashi; Nakamura, Tomoe Y; Wakabayashi, Shigeo

2013-03-01

Na(+)/H(+) exchanger (NHE) 1 is a member of the solute carrier superfamily, which regulates intracellular ionic homeostasis. NHE1 is known to require cellular ATP for its activity, despite there being no requirement for energy input from ATP hydrolysis. In this study, we investigated whether NHE1 is an ATP-binding protein. We designed a baculovirus vector carrying both epitope-tagged NHE1 and its cytosolic subunit CHP1, and expressed the functional NHE1-CHP1 complex on the surface of Sf9 insect cells. Using the purified complex protein consisting of NHE1 and CHP1 from Sf9 cells, we examined a photoaffinity labeling reaction with 8-azido-ATP-biotin. UV irradiation promoted the incorporation of 8-azido-ATP into NHE1, but not into CHP1, with an apparent Kd of 29.1 µM in the presence of Mg(2+). The nonlabeled nucleotides ATP, GTP, TTP and CTP all inhibited this crosslinking. However, ATP had the strongest inhibitory effect, with an apparent inhibition constant (IC50) for ATP of 2.2 mM, close to the ATP concentration giving the half-maximal activation of NHE1 activity. Importantly, crosslinking was more strongly inhibited by ATP than by ADP, suggesting that ATP is dissociated from NHE1 upon ATP hydrolysis. Limited proteolysis with thrombin and deletion mutant analysis revealed that the 8-azido-ATP-binding site is within the C-terminal cytoplasmic domain of NHE1. Equilibrium dialysis with NHE1-derived peptides provided evidence that ATP directly binds to the proximal cytoplasmic region (Gly542-Pro598), which is critical for ATP-dependent regulation of NHE1. These findings suggest that NHE1 is an ATP-binding transporter. Thus, ATP may serve as a direct activator of NHE1. © 2013 The Authors Journal compilation © 2013 FEBS.

Carbon and energy metabolism of atp mutants of Escherichia coli

DEFF Research Database (Denmark)

Jensen, Peter Ruhdal; Michelsen, Ole

1992-01-01

strain is not able to utilize the resulting proton motive force for ATP synthesis. Indeed, the ratio of ATP concentration to ADP concentration was decreased from 19 in the wild type to 7 in the atp mutant, and the membrane potential of the atp deletion strain was increased by 20%, confirming......The membrane-bound H+-ATPase plays a key role in free-energy transduction of biological systems. We report how the carbon and energy metabolism of Escherichia coli changes in response to deletion of the atp operon that encodes this enzyme. Compared with the isogenic wild-type strain, the growth...... rate and growth yield were decreased less than expected for a shift from oxidative phosphorylation to glycolysis alone as a source of ATP. Moreover, the respiration rate of a atp deletion strain was increased by 40% compared with the wild-type strain. This result is surprising, since the atp deletion...

Mevalonate 5-diphosphate mediates ATP binding to the mevalonate diphosphate decarboxylase from the bacterial pathogen Enterococcus faecalis

Energy Technology Data Exchange (ETDEWEB)

Chen, Chun-Liang; Mermoud, James C.; Paul, Lake N.; Steussy, Calvin Nicklaus; Stauffacher, Cynthia V. (Purdue)

2017-10-12

The mevalonate pathway produces isopentenyl diphosphate (IPP), a building block for polyisoprenoid synthesis, and is a crucial pathway for growth of the human bacterial pathogen Enterococcus faecalis. The final enzyme in this pathway, mevalonate diphosphate decarboxylase (MDD), acts on mevalonate diphosphate (MVAPP) to produce IPP while consuming ATP. This essential enzyme has been suggested as a therapeutic target for the treatment of drug-resistant bacterial infections. Here, we report functional and structural studies on the mevalonate diphosphate decarboxylase from E. faecalis (MDDEF). The MDDEF crystal structure in complex with ATP (MDDEF–ATP) revealed that the phosphate-binding loop (amino acids 97–105) is not involved in ATP binding and that the phosphate tail of ATP in this structure is in an outward-facing position pointing away from the active site. This suggested that binding of MDDEF to MVAPP is necessary to guide ATP into a catalytically favorable position. Enzymology experiments show that the MDDEF performs a sequential ordered bi-substrate reaction with MVAPP as the first substrate, consistent with the isothermal titration calorimetry (ITC) experiments. On the basis of ITC results, we propose that this initial prerequisite binding of MVAPP enhances ATP binding. In summary, our findings reveal a substrate-induced substrate-binding event that occurs during the MDDEF-catalyzed reaction. The disengagement of the phosphate-binding loop concomitant with the alternative ATP-binding configuration may provide the structural basis for antimicrobial design against these pathogenic enterococci.

Ecto-ATPase inhibition: ATP and adenosine release under physiological and ischemic in vivo conditions in the rat striatum.

Science.gov (United States)

Melani, Alessia; Corti, Francesca; Stephan, Holger; Müller, Christa E; Donati, Chiara; Bruni, Paola; Vannucchi, Maria Giuliana; Pedata, Felicita

2012-01-01

In the central nervous system (CNS) ATP and adenosine act as transmitters and neuromodulators on their own receptors but it is still unknown which part of extracellular adenosine derives per se from cells and which part is formed from the hydrolysis of released ATP. In this study extracellular concentrations of adenosine and ATP from the rat striatum were estimated by the microdialysis technique under in vivo physiological conditions and after focal ischemia induced by medial cerebral artery occlusion. Under physiological conditions, adenosine and ATP concentrations were in the range of 130 nmol/L and 40 nmol/L, respectively. In the presence of the novel ecto-ATPase inhibitor, PV4 (100 nmol/L), the extracellular concentration of ATP increased 12-fold to ~360 nmol/L but the adenosine concentration was not altered. This demonstrates that, under physiological conditions, adenosine is not a product of extracellular ATP. In the first 4h after ischemia, adenosine increased to ~690 nmol/L and ATP to ~50 nmol/L. In the presence of PV4 the extracellular concentration of ATP was in the range of 450 nmol/L and a significant decrease in extracellular adenosine (to ~270 nmol/L) was measured. The contribution of extracellular ATP to extracellular adenosine was maximal in the first 20 min after ischemia onset. Furthermore we demonstrated, by immunoelectron microscopy, the presence of the concentrative nucleoside transporter CNT2 on plasma and vesicle membranes isolated from the rat striatum. These results are in favor that adenosine is transported in vesicles and is released in an excitation-secretion manner under in vivo physiological conditions. Early after ischemia, extracellular ATP is hydrolyzed by ecto-nucleotidases which significantly contribute to the increase in extracellular adenosine. To establish the contribution of extracellular ATP to adenosine might constitute the basis for devising a correct putative purinergic strategy aimed at protection from ischemic damage

Endothelial ATP-binding cassette G1 in mouse endothelium protects against hemodynamic-induced atherosclerosis

Energy Technology Data Exchange (ETDEWEB)

Xue, Shanshan [Department of Physiology and Pathophysiology, Tianjin Medical University, Tianjin, 300070 (China); Department of Pediatrics, Baodi District People’s Hospital of Tianjin City, Tianjin, 301800 (China); Wang, Jiaxing [Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, 100191 (China); Zhang, Xu; Shi, Ying; Li, Bochuan; Bao, Qiankun [Department of Physiology and Pathophysiology, Tianjin Medical University, Tianjin, 300070 (China); Pang, Wei [Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, 100191 (China); Ai, Ding [Department of Physiology and Pathophysiology, Tianjin Medical University, Tianjin, 300070 (China); Zhu, Yi [Department of Physiology and Pathophysiology, Tianjin Medical University, Tianjin, 300070 (China); Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, 100191 (China); He, Jinlong, E-mail: hejinlong@tmu.edu.cn [Department of Physiology and Pathophysiology, Tianjin Medical University, Tianjin, 300070 (China)

2016-08-19

Activated vascular endothelium inflammation under persistent hyperlipidemia is the initial step of atherogenesis. ATP-binding cassette G1 (ABCG1) is a crucial factor maintaining sterol and lipid homeostasis by transporting cholesterol efflux to high-density lipoprotein. In this study, we investigated the protective effects of ABCG1 in endothelial inflammation activation during early-stage atherogenesis in mice and the underlying mechanisms. Endothelial cell (EC)-specific ABCG1 transgenic (EC-ABCG1-Tg) mice were generated and cross-bred with low-density lipoprotein receptor–deficient (Ldlr{sup −/−}) mice. After a 4-week Western-type diet, the mice were sacrificed for assessing atherosclerosis. Human umbilical vein ECs were treated with different flows, and ABCG1 was adenovirally overexpressed to investigate the mechanism in vitro. Compared with Ldlr{sup −/−} mouse aortas, EC-ABCG1-Tg/Ldlr{sup −/−} aortas showed decreased early-stage lesions. Furthermore, the lesion area in the EC-ABCG1-Tg/Ldlr{sup −/−} mouse aortic arch but not thoracic aorta was significantly reduced, which suggests a protective role of ABCG1 under atheroprone flow. In vitro, overexpression of ABCG1 attenuated EC activation caused by oscillatory shear stress. Overexpression of ABCG1 blunted cholesterol-activated ECs in vitro. In exploring the mechanisms of ABCG1 attenuating endothelial inflammation, we found that ABCG1 inhibited oscillatory flow-activated nuclear factor kappa B and NLRP3 inflammasome in ECs. ABCG1 may play a protective role in early-stage atherosclerosis by reducing endothelial activation induced by oscillatory shear stress via suppressing the inflammatory response. - Highlights: • EC-ABCG1-Tg mice in a Ldlr{sup −/−} background showed decreased atherosclerosis. • Overexpression of ABCG1 in ECs decreased OSS-induced EC activation. • NLRP3 and NF-κB might be an underlying mechanism of ABCG1 protective role.

The Role of ATP in Sleep Regulation

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Sachiko eChikahisa

2011-12-01

Full Text Available One of the functions of sleep is to maintain energy balance in the brain. There are a variety of hypotheses related to how metabolic pathways interact with sleep/wake regulation. A major finding that demonstrates an interaction between sleep and metabolic homeostasis is the involvement of adenosine in sleep homeostasis. An accumulation of adenosine is supplied from ATP, which can act as an energy currency in the cell. Extracellularly, ATP can act as an activity-dependent signaling molecule, especially in regard to communication between neurons and glia, including astrocytes. Furthermore, the intracellular AMP/ATP ratio controls the activity of AMP-activated protein kinase (AMPK, which is a potent energy regulator and is recently reported to play a role in the regulation of sleep homeostasis. Brain ATP may support multiple functions in the regulation of the sleep/wake cycle and sleep homeostasis.

Agrobacterium VirB10, an ATP energy sensor required for type IV secretion.

Science.gov (United States)

Cascales, Eric; Christie, Peter J

2004-12-07

Bacteria use type IV secretion systems (T4SS) to translocate DNA and protein substrates to target cells of phylogenetically diverse taxa. Recently, by use of an assay termed transfer DNA immunoprecipitation (TrIP), we described the translocation route for a DNA substrate [T-DNA, portion of the Ti (tumor-inducing) plasmid that is transferred to plant cells] of the Agrobacterium tumefaciens VirB/D4 T4SS in terms of a series of temporally and spatially ordered substrate contacts with subunits of the secretion channel. Here, we report that the bitopic inner membrane protein VirB10 undergoes a structural transition in response to ATP utilization by the VirD4 and VirB11 ATP-binding subunits, as monitored by protease susceptibility. VirB10 interacts with inner membrane VirD4 independently of cellular energetic status, whereas the energy-induced conformational change is required for VirB10 complex formation with an outer membrane-associated heterodimer of VirB7 lipoprotein and VirB9, as shown by coimmunoprecipitation. Under these conditions, the T-DNA substrate is delivered from the inner membrane channel components VirB6 and VirB8 to periplasmic and outer membrane-associated VirB2 pilin and VirB9. We propose that VirD4 and VirB11 coordinate the ATP-dependent formation of a VirB10 "bridge" between inner and outer membrane subassemblies of the VirB/D4 T4SS, and that this morphogenetic event is required for T-DNA translocation across the A. tumefaciens cell envelope.

Modification of synthesis nucleotides [γ-32P] ATP

International Nuclear Information System (INIS)

Wira Y Rahman; Endang Sarmini; Herlina; Triyanto; Hambali; Abdul Mutalib; Santi Nurbaiti

2013-01-01

In molecular biology, radionuclides in the form of radiolabeled compounds have been widely used as deoxyribonucleic acid (DNA) / ribonucleic acid (RNA) tracer in order to explore a wide range of physiological and pathological processes. One of such compounds is [γ- 32 P]-adenosine triphosphate {[γ- 32 P]-ATP} [γ- 32 P]-ATP which has been widely used in the biotechnology research. In order to support the biotechnology research in Indonesia in this project, [γ- 32 P]- ATP had been synthesized by enzymatic reactions with modifying the method of synthesis using the precursor DL-glyceraldehyde 3-phosphate, nucleotides Adenosine Diphosphate (ADP) and H 3 32 PO 4 and enzymes glyceraldehyde 3-phosphate dehydrogenase, 3-phosphoroglyceric phosphokinase and lactate dehydrogenase. The purification of the synthesized [γ- 32 P]-ATP, by using DEAE Sephadex column chromatography. The synthesis and purification process that had been performed were able in producing of [γ- 32 P]-ATP with radioactivity of 1,175 mCi and radiochemical purity of 99,49%.. Having successfully prepared the [γ- 32 P]-ATP and application, in the near future the Radioisotopes and Radiopharmaceuticals Centre is expected to be able in providing the above-mentioned radiolabeled nucleotide for biotechnology research in Indonesia. (author)

NCEP ATP III dan Framingham score

OpenAIRE

Hasan, Refli; Fahila, Reny

2016-01-01

Laporan ini merupakan Program Pendidikan Kolesterol National yang diperbaharui yaitu pedoman klinis untuk melakukan pengujian kolesterol dan manajemen. ATP III dibuat berdasarkan bukti dan laporan ekstensif yang akan menjadi referensi dan rekomendasi ilmiah. Laporan ATP III dapat dijadikan pedoman untuk pemberian terapi penurun kolesterol yang intensif dalam praktek. Pedoman ini hanya sebagai informasi , tidak dapat mempengaruhi secara mutlak dalam penilaian klinis dokter yang akhirnya menent...

Electron Microscopic Recording of the Power and Recovery Strokes of Individual Myosin Heads Coupled with ATP Hydrolysis: Facts and Implications

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Haruo Sugi

2018-05-01

Full Text Available The most straightforward way to get information on the performance of individual myosin heads producing muscle contraction may be to record their movement, coupled with ATP hydrolysis, electron-microscopically using the gas environmental chamber (EC. The EC enables us to visualize and record ATP-induced myosin head movement in hydrated skeletal muscle myosin filaments. When actin filaments are absent, myosin heads fluctuate around a definite neutral position, so that their time-averaged mean position remains unchanged. On application of ATP, myosin heads are found to move away from, but not towards, the bare region, indicating that myosin heads perform a recovery stroke (average amplitude, 6 nm. After exhaustion of ATP, myosin heads return to their neutral position. In the actin–myosin filament mixture, myosin heads form rigor actin myosin linkages, and on application of ATP, they perform a power stroke by stretching adjacent elastic structures because of a limited amount of applied ATP ≤ 10 µM. The average amplitude of the power stroke is 3.3 nm and 2.5 nm at the distal and the proximal regions of the myosin head catalytic domain (CAD, respectively. The power stroke amplitude increases appreciably at low ionic strength, which is known to enhance Ca2+-activated force in muscle. In both the power and recovery strokes, myosin heads return to their neutral position after exhaustion of ATP.

Fluorescence and chemiluminescence behavior of distyrylbenzene bearing two arms of dipicolylaminomethyl groups: Interactions with zinc ion and ATP

Science.gov (United States)

Motoyoshiya, Jiro; Wada, Jun-ya; Itoh, Keiko; Wakabayashi, Kazuaki; Maruyama, Takayuki; Ono, Kazuki; Fukasawa, Kota; Fujimoto, Tetsuya; Akaiwa, Yuji; Nonaka, Eiji

2018-04-01

The absorption and fluorescence spectral study of the distyrylbenzene bearing two arms of the dipicolylaminomethyl groups, the effective ligands for Zn2+, was studied in the presence of Zn2+ and ATP. Upon complexation of the distyrylbenzene with zinc ions in acetonitrile, enhancement of the fluorescence intensity was observed due to inhibition of intramolecular PET (photo-induced electron transfer) quenching, but no effect was found in aqueous media because the equilibrium laid to the free form of the ligands. In contrast, the addition of ATP disodium salt was effective to enhance the fluorescence intensity of the combination of the distyrylbenzne and Zn2+ in aqueous media. This assembly was applied to the peroxyoxalate chemiluminescence system and a significant increase in the intensity was observed, which provides a potential detection for ATP by chemiluminescence.

Highly Divergent Mitochondrial ATP Synthase Complexes in Tetrahymena thermophila

NARCIS (Netherlands)

Nina, Praveen Balabaskaran; Dudkina, Natalya V.; Kane, Lesley A.; van Eyk, Jennifer E.; Boekema, Egbert J.; Mather, Michael W.; Vaidya, Akhil B.; Eisen, Jonathan A.

The F-type ATP synthase complex is a rotary nano-motor driven by proton motive force to synthesize ATP. Its F(1) sector catalyzes ATP synthesis, whereas the F(o) sector conducts the protons and provides a stator for the rotary action of the complex. Components of both F(1) and F(o) sectors are

Altered localisation of the copper efflux transporters ATP7A and ATP7B associated with cisplatin resistance in human ovarian carcinoma cells

International Nuclear Information System (INIS)

Kalayda, Ganna V; Wagner, Christina H; Buß, Irina; Reedijk, Jan; Jaehde, Ulrich

2008-01-01

Copper homeostasis proteins ATP7A and ATP7B are assumed to be involved in the intracellular transport of cisplatin. The aim of the present study was to assess the relevance of sub cellular localisation of these transporters for acquired cisplatin resistance in vitro. For this purpose, localisation of ATP7A and ATP7B in A2780 human ovarian carcinoma cells and their cisplatin-resistant variant, A2780cis, was investigated. Sub cellular localisation of ATP7A and ATP7B in sensitive and resistant cells was investigated using confocal fluorescence microscopy after immunohistochemical staining. Co-localisation experiments with a cisplatin analogue modified with a carboxyfluorescein-diacetate residue were performed. Cytotoxicity of the fluorescent cisplatin analogue in A2780 and A2780cis cells was determined using an MTT-based assay. The significance of differences was analysed using Student's t test or Mann-Whitney test as appropriate, p values of < 0.05 were considered significant. In the sensitive cells, both transporters are mainly localised in the trans-Golgi network, whereas they are sequestrated in more peripherally located vesicles in the resistant cells. Altered localisation of ATP7A and ATP7B in A2780cis cells is likely to be a consequence of major abnormalities in intracellular protein trafficking related to a reduced lysosomal compartment in this cell line. Changes in sub cellular localisation of ATP7A and ATP7B may facilitate sequestration of cisplatin in the vesicular structures of A2780cis cells, which may prevent drug binding to genomic DNA and thereby contribute to cisplatin resistance. Our results indicate that alterations in sub cellular localisation of transport proteins may contribute to cisplatin resistance in vitro. Investigation of intracellular protein localisation in primary tumour cell cultures and tumour tissues may help to develop markers of clinically relevant cisplatin resistance. Detection of resistant tumours in patients may in turn

Altered localisation of the copper efflux transporters ATP7A and ATP7B associated with cisplatin resistance in human ovarian carcinoma cells

Directory of Open Access Journals (Sweden)

Reedijk Jan

2008-06-01

Full Text Available Abstract Background Copper homeostasis proteins ATP7A and ATP7B are assumed to be involved in the intracellular transport of cisplatin. The aim of the present study was to assess the relevance of sub cellular localisation of these transporters for acquired cisplatin resistance in vitro. For this purpose, localisation of ATP7A and ATP7B in A2780 human ovarian carcinoma cells and their cisplatin-resistant variant, A2780cis, was investigated. Methods Sub cellular localisation of ATP7A and ATP7B in sensitive and resistant cells was investigated using confocal fluorescence microscopy after immunohistochemical staining. Co-localisation experiments with a cisplatin analogue modified with a carboxyfluorescein-diacetate residue were performed. Cytotoxicity of the fluorescent cisplatin analogue in A2780 and A2780cis cells was determined using an MTT-based assay. The significance of differences was analysed using Student's t test or Mann-Whitney test as appropriate, p values of Results In the sensitive cells, both transporters are mainly localised in the trans-Golgi network, whereas they are sequestrated in more peripherally located vesicles in the resistant cells. Altered localisation of ATP7A and ATP7B in A2780cis cells is likely to be a consequence of major abnormalities in intracellular protein trafficking related to a reduced lysosomal compartment in this cell line. Changes in sub cellular localisation of ATP7A and ATP7B may facilitate sequestration of cisplatin in the vesicular structures of A2780cis cells, which may prevent drug binding to genomic DNA and thereby contribute to cisplatin resistance. Conclusion Our results indicate that alterations in sub cellular localisation of transport proteins may contribute to cisplatin resistance in vitro. Investigation of intracellular protein localisation in primary tumour cell cultures and tumour tissues may help to develop markers of clinically relevant cisplatin resistance. Detection of resistant tumours

Red blood cell dynamics: from cell deformation to ATP release.

Science.gov (United States)

Wan, Jiandi; Forsyth, Alison M; Stone, Howard A

2011-10-01

The mechanisms of red blood cell (RBC) deformation under both static and dynamic, i.e., flow, conditions have been studied extensively since the mid 1960s. Deformation-induced biochemical reactions and possible signaling in RBCs, however, were proposed only fifteen years ago. Therefore, the fundamental relationship between RBC deformation and cellular signaling dynamics i.e., mechanotransduction, remains incompletely understood. Quantitative understanding of the mechanotransductive pathways in RBCs requires integrative studies of physical models of RBC deformation and cellular biochemical reactions. In this article we review the physical models of RBC deformation, spanning from continuum membrane mechanics to cellular skeleton dynamics under both static and flow conditions, and elaborate the mechanistic links involved in deformation-induced ATP release. This journal is © The Royal Society of Chemistry 2011

Structure of the oxalate-ATP complex with pyruvate kinase: ATP as a bridging ligand for the two divalent cations

International Nuclear Information System (INIS)

Lodato, D.T.; Reed, G.H.

1987-01-01

The 2 equiv of divalent cation that are required cofactors for pyruvate kinase reside in sites of different affinities for different species of cation. The intrinsic selectivity of the protein-based site for Mn(II) and of the nucleotide-based site for Mg(II) has been exploited in electron paramagnetic resonance (EOR) investigations of ligands for Mn(II) at the protein-based site. Oxalate, a structural analogue of the enolate of pyruvate, has been used as a surrogate for the reactive form of pyruvate in complexes with enzyme, Mn(II), Mg(II), and ATP. Superhyperfine coupling between the unpaired electron spin of Mn(II) and the nuclear spin of 17 O, specifically incorporated into oxalate, shows that oxalate is bound at the active site as a bidentate chelate with Mn(II). Coordination of the γ-phosphate of ATP to this same Mn(II) center is revealed by observation of superhyperfine coupling from 17 O regiospecifically incorporated into the γ-phosphate group of ATP. By contrast, 17 O in the α-phosphate or in the β-phosphate groups of ATP does not influence the spectrum. Experiments in 17 O-enriched water show that there is also a single water ligand bound to the Mn(II). These data indicate that ATP bridges Mn(II) and Mg(II) at the active site. A close spacing of the two divalent cations is also evident from the occurrence of magnetic interactions for complexes in which 2 equiv of Mn(II) are present at the active site. The structure for the enzyme-Mn(II)-oxalate-Mg(II)-ATP complex suggests a scheme for the normal reverse reaction of pyruvate kinase in which the divalent cation at the protein-based site activates the keto acid substrate through chelation and promotes phospho transfer by simultaneous coordination to the enolate oxygen and to a pendant oxygen from the γ-phosphate of ATP

ATP-dependent Conformational Changes Trigger Substrate Capture and Release by an ECF-type Biotin Transporter.

Science.gov (United States)

Finkenwirth, Friedrich; Sippach, Michael; Landmesser, Heidi; Kirsch, Franziska; Ogienko, Anastasia; Grunzel, Miriam; Kiesler, Cornelia; Steinhoff, Heinz-Jürgen; Schneider, Erwin; Eitinger, Thomas

2015-07-03

Energy-coupling factor (ECF) transporters for vitamins and metal ions in prokaryotes consist of two ATP-binding cassette-type ATPases, a substrate-specific transmembrane protein (S component) and a transmembrane protein (T component) that physically interacts with the ATPases and the S component. The mechanism of ECF transporters was analyzed upon reconstitution of a bacterial biotin transporter into phospholipid bilayer nanodiscs. ATPase activity was not stimulated by biotin and was only moderately reduced by vanadate. A non-hydrolyzable ATP analog was a competitive inhibitor. As evidenced by cross-linking of monocysteine variants and by site-specific spin labeling of the Q-helix followed by EPR-based interspin distance analyses, closure and reopening of the ATPase dimer (BioM2) was a consequence of ATP binding and hydrolysis, respectively. A previously suggested role of a stretch of small hydrophobic amino acid residues within the first transmembrane segment of the S units for S unit/T unit interactions was structurally and functionally confirmed for the biotin transporter. Cross-linking of this segment in BioY (S) using homobifunctional thiol-reactive reagents to a coupling helix of BioN (T) indicated a reorientation rather than a disruption of the BioY/BioN interface during catalysis. Fluorescence emission of BioY labeled with an environmentally sensitive fluorophore was compatible with an ATP-induced reorientation and consistent with a hypothesized toppling mechanism. As demonstrated by [(3)H]biotin capture assays, ATP binding stimulated substrate capture by the transporter, and subsequent ATP hydrolysis led to substrate release. Our study represents the first experimental insight into the individual steps during the catalytic cycle of an ECF transporter in a lipid environment. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Bedaquiline Inhibits the ATP Synthase in Mycobacterium abscessus and Is Effective in Infected Zebrafish.

Science.gov (United States)

Dupont, Christian; Viljoen, Albertus; Thomas, Sangeeta; Roquet-Banères, Françoise; Herrmann, Jean-Louis; Pethe, Kevin; Kremer, Laurent

2017-11-01

Pulmonary infections caused by Mycobacterium abscessus are emerging as a global threat, especially in cystic fibrosis patients. Further intensifying the concern of M. abscessus infection is the recent evidence of human-to-human transmission of the infection. M. abscessus is a naturally multidrug-resistant fast-growing pathogen for which pharmacological options are limited. Repurposing antitubercular drugs represents an attractive option for the development of chemotherapeutic alternatives against M. abscessus infections. Bedaquiline (BDQ), an ATP synthase inhibitor, has recently been approved for the treatment of multidrug-resistant tuberculosis. Herein, we show that BDQ has a very low MIC against a vast panel of clinical isolates. Despite being bacteriostatic in vitro , BDQ was highly efficacious in a zebrafish model of M. abscessus infection. Remarkably, a very short period of treatment was sufficient to protect the infected larvae from M. abscessus -induced killing. This was corroborated with reduced numbers of abscesses and cords, considered to be major pathophysiological signs in infected zebrafish. Mode-of-action studies revealed that BDQ triggered a rapid depletion of ATP in M. abscessus in vitro , consistent with the drug targeting the F o F 1 ATP synthase. Importantly, despite a failure to select in vitro for spontaneous mutants that are highly resistant to BDQ, the transfer of single nucleotide polymorphisms leading to D29V or A64P substitutions in atpE conferred high resistance, thus resolving the target of BDQ in M. abscessus Overall, this study indicates that BDQ is active against M. abscessus in vitro and in vivo and should be considered for clinical use against the difficult-to-manage M. abscessus pulmonary infections. Copyright © 2017 American Society for Microbiology.

Highly divergent mitochondrial ATP synthase complexes in Tetrahymena thermophila.

Directory of Open Access Journals (Sweden)

Praveen Balabaskaran Nina

2010-07-01

Full Text Available The F-type ATP synthase complex is a rotary nano-motor driven by proton motive force to synthesize ATP. Its F(1 sector catalyzes ATP synthesis, whereas the F(o sector conducts the protons and provides a stator for the rotary action of the complex. Components of both F(1 and F(o sectors are highly conserved across prokaryotes and eukaryotes. Therefore, it was a surprise that genes encoding the a and b subunits as well as other components of the F(o sector were undetectable in the sequenced genomes of a variety of apicomplexan parasites. While the parasitic existence of these organisms could explain the apparent incomplete nature of ATP synthase in Apicomplexa, genes for these essential components were absent even in Tetrahymena thermophila, a free-living ciliate belonging to a sister clade of Apicomplexa, which demonstrates robust oxidative phosphorylation. This observation raises the possibility that the entire clade of Alveolata may have invented novel means to operate ATP synthase complexes. To assess this remarkable possibility, we have carried out an investigation of the ATP synthase from T. thermophila. Blue native polyacrylamide gel electrophoresis (BN-PAGE revealed the ATP synthase to be present as a large complex. Structural study based on single particle electron microscopy analysis suggested the complex to be a dimer with several unique structures including an unusually large domain on the intermembrane side of the ATP synthase and novel domains flanking the c subunit rings. The two monomers were in a parallel configuration rather than the angled configuration previously observed in other organisms. Proteomic analyses of well-resolved ATP synthase complexes from 2-D BN/BN-PAGE identified orthologs of seven canonical ATP synthase subunits, and at least 13 novel proteins that constitute subunits apparently limited to the ciliate lineage. A mitochondrially encoded protein, Ymf66, with predicted eight transmembrane domains could be a

The collagen type I segment long spacing (SLS) and fibrillar forms: Formation by ATP and sulphonated diazo dyes.

Science.gov (United States)

Harris, J Robin; Lewis, Richard J

2016-07-01

The collagen type I segment long spacing (SLS) crystallite is a well-ordered rod-like molecular aggregate, ∼300nm in length, which is produced in vitro under mildly acidic conditions (pH 2.5-3.5) in the presence of 1mM ATP. The formation of the SLS crystallite amplifies the inherent linear structural features of individual collagen heterotrimers, due to the punctate linear distribution and summation of the bulkier amino acid side chains along the length of individual collagen heterotrimers. This can be correlated structurally with the 67nm D-banded collagen fibril that is found in vivo, and formed in vitro. Although first described many years ago, the range of conditions required for ATP-induced SLS crystallite formation from acid-soluble collagen have not been explored extensively. Consequently, we have addressed biochemical parameters such as the ATP concentration, pH, speed of formation and stability so as to provide a more complete structural understanding of the SLS crystallite. Treatment of collagen type I with 1mM ATP at neutral and higher pH (6.0-9.0) also induced the formation of D-banded fibrils. Contrary to previous studies, we have shown that the polysulphonated diazo dyes Direct red (Sirius red) and Evans blue, but not Congo red and Methyl blue, can also induce the formation of SLS-like aggregates of collagen, but under markedly different ionic conditions to those employed in the presence of ATP. Specifically, pre-formed D-banded collagen fibrils, prepared in a higher than the usual physiological NaCl concentration (e.g. 500mM NaCl, 20mM Tris-HCl pH7.4 or x3 PBS), readily form SLS aggregates when treated with 0.1mM Direct red and Evans blue, but this did not occur at lower NaCl concentrations. These new data are discussed in relation to the anion (Cl(-)) and polyanion (phosphate and sulphonate) binding by the collagen heterotrimer and their likely role in collagen fibrillogenesis and SLS formation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of ionotropic glutamate receptor antagonists on rat dural artery diameter in an intravital microscopy model

DEFF Research Database (Denmark)

Chan, K Y; Gupta, S; de Vries, R

2010-01-01

During migraine, trigeminal nerves may release calcitonin gene-related peptide (CGRP), inducing cranial vasodilatation and central nociception; hence, trigeminal inhibition or blockade of craniovascular CGRP receptors may prevent this vasodilatation and abort migraine headache. Several preclinical...

Long-Range Effects of Na(+) Binding in Na,K-ATPase Reported by ATP.

Science.gov (United States)

Middleton, David A; Fedosova, Natalya U; Esmann, Mikael

2015-12-01

This paper addresses the question of long-range interactions between the intramembranous cation binding sites and the cytoplasmic nucleotide binding site of the ubiquitous ion-transporting Na,K-ATPase using (13)C cross-polarization magic-angle spinning (CP-MAS) solid-state nuclear magnetic resonance. High-affinity ATP binding is induced by the presence of Na(+) as well as of Na-like substances such as Tris(+), and these ions are equally efficient promoters of nucleotide binding. CP-MAS analysis of bound ATP with Na,K-ATPase purified from pig kidney membranes reveals subtle differences in the nucleotide interactions within the nucleotide site depending on whether Na(+) or Tris(+) is used to induce binding. Differences in chemical shifts for ATP atoms C1' and C5' observed in the presence of Na(+) or Tris(+) suggest alterations in the residues surrounding the bound nucleotide, hydrogen bonding, and/or conformation of the ribose ring. This is taken as evidence of a long-distance communication between the Na(+)-filled ion sites in the membrane interior and the nucleotide binding site in the cytoplasmic domain and reflects the first conformational change ultimately leading to phosphorylation of the enzyme. Stopped-flow fluorescence measurements with the nucleotide analogue eosin show that the dissociation rate constant for eosin is larger in Tris(+) than in Na(+), giving kinetic evidence of the difference in structural effects of Na(+) and Tris(+). According to the recent crystal structure of the E1·AlF4(-)·ADP·3Na(+) form, the coupling between the ion binding sites and the nucleotide side is mediated by, among others, the M5 helix.

Conditional depletion of intellectual disability and Parkinsonism candidate gene ATP6AP2 in fly and mouse induces cognitive impairment and neurodegeneration

NARCIS (Netherlands)

Dubos, A.; Castells-Nobau, A.; Meziane, H.; Oortveld, M.A.; Houbaert, X.; Iacono, G.; Martin, C.; Mittelhaeuser, C.; Lalanne, V.; Kramer, J.M.; Bhukel, A.; Quentin, C.; Slabbert, J.; Verstreken, P.; Sigrist, S.J.; Messaddeq, N.; Birling, M.C.; Selloum, M.; Stunnenberg, H.G.; Humeau, Y.; Schenck, A.; Herault, Y.

2015-01-01

ATP6AP2, an essential accessory component of the vacuolar H+ ATPase (V-ATPase), has been associated with intellectual disability (ID) and Parkinsonism. ATP6AP2 has been implicated in several signalling pathways; however, little is known regarding its role in the nervous system. To decipher its

Determination of ATP as a fluorescence probe with europium(III)-doxycycline.

Science.gov (United States)

Hou, Faju; Wang, Xiaolei; Jiang, Chongqiu

2005-03-01

A new spectrofluorimetric method has been developed for the determination of adenosine disodium triphosphate (ATP). We studied the interactions between the doxycycline (DC)-Eu3+ complex and adenosine disodium triphosphate (ATP) by using UV-visible absorption and fluorescence spectra. Using doxycycline (DC)-Eu3+ as a fluorescence probe, under the optimum conditions, ATP could remarkably enhance the fluorescence intensity of the DC-Eu3+ complex at lambda = 612 nm. The enhanced fluorescence intensity of the Eu3+ ion was in proportion to the concentration of ATP. The optimum conditions for the determination of ATP were also investigated. The linear ranges for ATP were 1.00 x 10(-7) - 2.00 x 10(-6) mol L(-1) with detection limits of 4.07 x 10(-8) mol L(-1). This method is simple, practical and relatively free of interference from coexisting substances, and can be successfully applied to the determination of ATP in samples. The mechanism of fluorescence enhancement between the doxycycline (DC)-Eu3+ complex and ATP was also studied.

Loss of the gene for the alpha subunit of ATP synthase (ATP5A1) from the W chromosome in the African grey parrot (Psittacus erithacus).

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de Kloet, S R

2001-08-01

This study describes the results of an analysis using Southern blotting, the polymerase chain reaction, and sequencing which shows that the African grey parrot (Psittacus erithacus) lacks the W-chromosomal gene for the alpha subunit of mitochondrial ATP synthase (ATP5A1W). Additional evidence shows that in other psittacines a fragment of the ATP5A1W gene contains five times as many nonsynonymous nucleotide replacements as the homologous fragment of the Z gene. Therefore, whereas in these other psittacines the corresponding ATP5A1Z protein fragment is highly conserved and varies by only a few, moderately conservative amino acid substitutions, the homologous ATP5A1W fragments contain a considerable number of, sometimes highly nonconservative, amino acid replacements. In one of these species, the ringneck parakeet (Psittacula krameri), the ATP5A1W gene is present in an inactive form because of the presence of a nonsense codon. Other changes, possibly leading to an inactive ATP5A1W gene product, involve the substitution of arginine residues by cysteine in the ATP5A1W protein of the mitred conure (Aratinga mitrata) and the blue and gold macaw (Ara ararauna). The data suggest also that although the divergence of the psittacine ATP5A1W and ATP5A1Z genes preceded the origin of the psittacidae, this divergence occurred independently of a similar process in the myna (Gracula religiosa), the outgroup used in this study.

The role of the C8 proton of ATP in the catalysis of shikimate kinase and adenylate kinase

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Kenyon Colin P

2012-08-01

Full Text Available Abstract Background It has been demonstrated that the adenyl moiety of ATP plays a direct role in the regulation of ATP binding and/or phosphoryl transfer within a range of kinase and synthetase enzymes. The role of the C8-H of ATP in the binding and/or phosphoryl transfer on the enzyme activity of a number of kinase and synthetase enzymes has been elucidated. The intrinsic catalysis rate mediated by each kinase enzyme is complex, yielding apparent KM values ranging from less than 0.4 μM to more than 1 mM for ATP in the various kinases. Using a combination of ATP deuterated at the C8 position (C8D-ATP as a molecular probe with site directed mutagenesis (SDM of conserved amino acid residues in shikimate kinase and adenylate kinase active sites, we have elucidated a mechanism by which the ATP C8-H is induced to be labile in the broader kinase family. We have demonstrated the direct role of the C8-H in the rate of ATP consumption, and the direct role played by conserved Thr residues interacting with the C8-H. The mechanism by which the vast range in KM might be achieved is also suggested by these findings. Results We have demonstrated the mechanism by which the enzyme activities of Group 2 kinases, shikimate kinase (SK and adenylate kinase 1 (AK1, are controlled by the C8-H of ATP. Mutations of the conserved threonine residues associated with the labile C8-H cause the enzymes to lose their saturation kinetics over the concentration range tested. The relationship between the role C8-H of ATP in the reaction mechanism and the ATP concentration as they influence the saturation kinetics of the enzyme activity is also shown. The SDM clearly identified the amino acid residues involved in both the catalysis and regulation of phosphoryl transfer in SK and AK1 as mediated by C8H-ATP. Conclusions The data outlined serves to demonstrate the “push” mechanism associated with the control of the saturation kinetics of Group 2 kinases mediated by ATP C8-H. It

The dynamic equilibrium between ATP synthesis and ATP consumption is lower in isolated mitochondria from myotubes established from type 2 diabetic subjects compared to lean control

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Minet, Ariane D; Gaster, Michael

2011-01-01

compared to lean control. The ATP synthesis rate without ATP consumption was not different between groups and there were no significant gender differences. The mitochondrial dysfunction in type 2 diabetes in vivo is partly based on a primarily impaired ATP synthesis....... or not in the mitochondria of diabetic skeletal muscle from subjects with type 2 diabetes. ATP synthesis was measured on mitochondria isolated from cultured myotubes established from lean (11/9), obese (9/11) and subjects with type 2 diabetes (9/11) (female/male, n=20 in each group), precultured under normophysiological...... selects the mitochondria based on an antibody recognizing the mitochondrial outer membrane and not by size through gradient centrifugation. The dynamic equilibrium between ATP synthesis and ATP consumption is 35% lower in isolated mitochondria from myotubes established from type 2 diabetic subjects...

Common pathogenic effects of missense mutations in the P-type ATPase ATP13A2 (PARK9) associated with early-onset parkinsonism.

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Podhajska, Agata; Musso, Alessandra; Trancikova, Alzbeta; Stafa, Klodjan; Moser, Roger; Sonnay, Sarah; Glauser, Liliane; Moore, Darren J

2012-01-01

Mutations in the ATP13A2 gene (PARK9) cause autosomal recessive, juvenile-onset Kufor-Rakeb syndrome (KRS), a neurodegenerative disease characterized by parkinsonism. KRS mutations produce truncated forms of ATP13A2 with impaired protein stability resulting in a loss-of-function. Recently, homozygous and heterozygous missense mutations in ATP13A2 have been identified in subjects with early-onset parkinsonism. The mechanism(s) by which missense mutations potentially cause parkinsonism are not understood at present. Here, we demonstrate that homozygous F182L, G504R and G877R missense mutations commonly impair the protein stability of ATP13A2 leading to its enhanced degradation by the proteasome. ATP13A2 normally localizes to endosomal and lysosomal membranes in neurons and the F182L and G504R mutations disrupt this vesicular localization and promote the mislocalization of ATP13A2 to the endoplasmic reticulum. Heterozygous T12M, G533R and A746T mutations do not obviously alter protein stability or subcellular localization but instead impair the ATPase activity of microsomal ATP13A2 whereas homozygous missense mutations disrupt the microsomal localization of ATP13A2. The overexpression of ATP13A2 missense mutants in SH-SY5Y neural cells does not compromise cellular viability suggesting that these mutant proteins lack intrinsic toxicity. However, the overexpression of wild-type ATP13A2 may impair neuronal integrity as it causes a trend of reduced neurite outgrowth of primary cortical neurons, whereas the majority of disease-associated missense mutations lack this ability. Finally, ATP13A2 overexpression sensitizes cortical neurons to neurite shortening induced by exposure to cadmium or nickel ions, supporting a functional interaction between ATP13A2 and heavy metals in post-mitotic neurons, whereas missense mutations influence this sensitizing effect. Collectively, our study provides support for common loss-of-function effects of homozygous and heterozygous missense

Effects of Irradiation on bacterial atp luminous intensity of cooled pork and chicken

International Nuclear Information System (INIS)

Ju Hua

2010-01-01

The effect of irradiation on cooled pork and chicken was detected with ATP luminous intensity method. The influences of other factors to ATP luminous intensity were also discussed. There was positive correlation between ATP standard concentration and ATP luminous intensity, and negative correlation between irradiation dosage and ATP luminous intensity. The trend of ATP luminous intensity of cooled pork and chicken after irradiation was inverse S, and the maximum ATP luminous intensity appeared at 6.0 kGy, and minimum at 4.0 and 8.0 kGy. Sterilized water and sterilized pork had no interference to ATP luminous intensity of the samples. There was significant positive correlation between E. coli 10003 concentration and ATP luminous intensity, the coefficient correlation was 0.9437. (authors)

Effects of spermine NONOate and ATP on the thermal stability of hemoglobin

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Bassam Rasha

2012-08-01

Full Text Available Abstract Background Minor changes in protein structure induced by small organic and inorganic molecules can result in significant metabolic effects. The effects can be even more profound if the molecular players are chemically active and present in the cell in considerable amounts. The aim of our study was to investigate effects of a nitric oxide donor (spermine NONOate, ATP and sodium/potassium environment on the dynamics of thermal unfolding of human hemoglobin (Hb. The effect of these molecules was examined by means of circular dichroism spectrometry (CD in the temperature range between 25°C and 70°C. The alpha-helical content of buffered hemoglobin samples (0.1 mg/ml was estimated via ellipticity change measurements at a heating rate of 1°C/min. Results Major results were: 1 spermine NONOate persistently decreased the hemoglobin unfolding temperature Tuirrespectively of the Na + /K + environment, 2 ATP instead increased the unfolding temperature by 3°C in both sodium-based and potassium-based buffers and 3 mutual effects of ATP and NO were strongly influenced by particular buffer ionic compositions. Moreover, the presence of potassium facilitated a partial unfolding of alpha-helical structures even at room temperature. Conclusion The obtained data might shed more light on molecular mechanisms and biophysics involved in the regulation of protein activity by small solutes in the cell.

Metabolomic Analysis of Differential Changes in Metabolites during ATP Oscillations in Chondrogenesis

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Hyuck Joon Kwon

2013-01-01

Full Text Available Prechondrogenic condensation is a critical step for skeletal pattern formation. Recent studies reported that ATP oscillations play an essential role in prechondrogenic condensation. However, the molecular mechanism to underlie ATP oscillations remains poorly understood. In the present study, it was investigated how changes in metabolites are implicated in ATP oscillations during chondrogenesis by using capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS. CE-TOF-MS detected 93 cationic and 109 anionic compounds derived from known metabolic pathways. 15 cationic and 18 anionic compounds revealed significant change between peak and trough of ATP oscillations. These results implicate that glycolysis, mitochondrial respiration and uronic acid pathway oscillate in phase with ATP oscillations, while PPRP and nucleotides synthesis pathways oscillate in antiphase with ATP oscillations. This suggests that the ATP-producing glycolysis and mitochondrial respiration oscillate in antiphase with the ATP-consuming PPRP/nucleotide synthesis pathway during chondrogenesis.

RNS60, a charge-stabilized nanostructure saline alters Xenopus Laevis oocyte biophysical membrane properties by enhancing mitochondrial ATP production

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Choi, Soonwook; Yu, Eunah; Kim, Duk-Soo; Sugimori, Mutsuyuki; Llinás, Rodolfo R

2015-01-01

We have examined the effects of RNS60, a 0.9% saline containing charge-stabilized oxygen nanobubble-based structures. RNS60 is generated by subjecting normal saline to Taylor–Couette–Poiseuille (TCP) flow under elevated oxygen pressure. This study, implemented in Xenopus laevis oocytes, addresses both the electrophysiological membrane properties and parallel biological processes in the cytoplasm. Intracellular recordings from defolliculated X. laevis oocytes were implemented in: (1) air oxygenated standard Ringer's solution, (2) RNS60-based Ringer's solution, (3) RNS10.3 (TCP-modified saline without excess oxygen)-based Ringer's, and (4) ONS60 (saline containing high pressure oxygen without TCP modification)-based Ringer's. RNS60-based Ringer's solution induced membrane hyperpolarization from the resting membrane potential. This effect was prevented by: (1) ouabain (a blocker of the sodium/potassium ATPase), (2) rotenone (a mitochondrial electron transfer chain inhibitor preventing usable ATP synthesis), and (3) oligomycin A (an inhibitor of ATP synthase) indicating that RNS60 effects intracellular ATP levels. Increased intracellular ATP levels following RNS60 treatment were directly demonstrated using luciferin/luciferase photon emission. These results indicate that RNS60 alters intrinsic the electrophysiological properties of the X. laevis oocyte membrane by increasing mitochondrial-based ATP synthesis. Ultrastructural analysis of the oocyte cytoplasm demonstrated increased mitochondrial length in the presence of RNS60-based Ringer's solution. It is concluded that the biological properties of RNS60 relate to its ability to optimize ATP synthesis. PMID:25742953

Methodological problems of direct bioluminescent ATP assay in platelets and erythrocytes.

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Girotti, S; Ferri, E; Cascione, M L; Comuzio, S; Mazzuca, A; Orlandini, A; Breccia, A

1989-07-01

Direct bioluminescent ATP determination in platelets and erythrocytes involves the study of different parameters which are discussed here. Some parameters are linked to the bioluminescent reaction and to the analyte (ATP); others have regard to the biological matrix. The composition of bioluminescent reagents and the preparation and conservation of the ATP standard, also in the presence of excipients, are among the first given. Matrix problems involve cell characteristics related to age and form, lysis resistance and the possible formation of aggregates (platelets) that may inhibit the complete release of ATP. For these reasons we used the most efficient ATP release agent with the lowest inhibitory effect on luciferase. The data obtained correlate well with a bioluminescent method requiring extraction with ethanol/EDTA, and therefore more time, for ATP determination in platelets and erythrocytes.

ATP economy of force maintenance in human tibialis anterior muscle

DEFF Research Database (Denmark)

Nakagawa, Yoshinao; Ratkevicius, Aivaras; Mizuno, Masao

2005-01-01

PURPOSE: The aim of this study was investigate ATP economy of force maintenance in the human tibialis anterior muscle during 60 s of anaerobic voluntary contraction at 50% of maximum voluntary contraction (MVC). METHODS: ATP turnover rate was evaluated using P magnetic resonance spectroscopy (P...... contraction. It averaged at 4.81 +/- 0.42 N.s.micromol-1, and correlated with the relative cross-sectional area of the muscle occupied by Type I fiber (r = 0.73, P contraction, subjects dropping in force showed lower ATP economy compared with those maintaining the force (3.......7 +/- 0.6 vs 5.3 +/- 0.6 N.s.micromol-1; P contraction could be due to an increase in the ATP economy of contracting muscle fibers offsetting the effects of increased temperature and low ATP economy...

Non-bilayer structures in mitochondrial membranes regulate ATP synthase activity.

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Gasanov, Sardar E; Kim, Aleksandr A; Yaguzhinsky, Lev S; Dagda, Ruben K

2018-02-01

Cardiolipin (CL) is an anionic phospholipid at the inner mitochondrial membrane (IMM) that facilitates the formation of transient non-bilayer (non-lamellar) structures to maintain mitochondrial integrity. CL modulates mitochondrial functions including ATP synthesis. However, the biophysical mechanisms by which CL generates non-lamellar structures and the extent to which these structures contribute to ATP synthesis remain unknown. We hypothesized that CL and ATP synthase facilitate the formation of non-bilayer structures at the IMM to stimulate ATP synthesis. By using 1 H NMR and 31 P NMR techniques, we observed that increasing the temperature (8°C to 37°C), lowering the pH (3.0), or incubating intact mitochondria with CTII - an IMM-targeted toxin that increases the formation of immobilized non-bilayer structures - elevated the formation of non-bilayer structures to stimulate ATP synthesis. The F 0 sector of the ATP synthase complex can facilitate the formation of non-bilayer structures as incubating model membranes enriched with IMM-specific phospholipids with exogenous DCCD-binding protein of the F 0 sector (DCCD-BPF) elevated the formation of immobilized non-bilayer structures to a similar manner as CTII. Native PAGE assays revealed that CL, but not other anionic phospholipids, specifically binds to DCCD-BPF to promote the formation of stable lipid-protein complexes. Mechanistically, molecular docking studies identified two lipid binding sites for CL in DCCD-BPF. We propose a new model of ATP synthase regulation in which CL mediates the formation of non-bilayer structures that serve to cluster protons and ATP synthase complexes as a mechanism to enhance proton translocation to the F 0 sector, and thereby increase ATP synthesis. Copyright © 2017 Elsevier B.V. All rights reserved.

Astrocytes protect neurons against methylmercury via ATP/P2Y(1) receptor-mediated pathways in astrocytes.

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Noguchi, Yusuke; Shinozaki, Youichi; Fujishita, Kayoko; Shibata, Keisuke; Imura, Yoshio; Morizawa, Yosuke; Gachet, Christian; Koizumi, Schuichi

2013-01-01

Methylmercury (MeHg) is a well known environmental pollutant that induces serious neuronal damage. Although MeHg readily crosses the blood-brain barrier, and should affect both neurons and glial cells, how it affects glia or neuron-to-glia interactions has received only limited attention. Here, we report that MeHg triggers ATP/P2Y1 receptor signals in astrocytes, thereby protecting neurons against MeHg via interleukin-6 (IL-6)-mediated pathways. MeHg increased several mRNAs in astrocytes, among which IL-6 was the highest. For this, ATP/P2Y1 receptor-mediated mechanisms were required because the IL-6 production was (i) inhibited by a P2Y1 receptor antagonist, MRS2179, (ii) abolished in astrocytes obtained from P2Y1 receptor-knockout mice, and (iii) mimicked by exogenously applied ATP. In addition, (iv) MeHg released ATP by exocytosis from astrocytes. As for the intracellular mechanisms responsible for IL-6 production, p38 MAP kinase was involved. MeHg-treated astrocyte-conditioned medium (ACM) showed neuro-protective effects against MeHg, which was blocked by anti-IL-6 antibody and was mimicked by the application of recombinant IL-6. As for the mechanism of neuro-protection by IL-6, an adenosine A1 receptor-mediated pathway in neurons seems to be involved. Taken together, when astrocytes sense MeHg, they release ATP that autostimulates P2Y1 receptors to upregulate IL-6, thereby leading to A1 receptor-mediated neuro-protection against MeHg.

Aptasensor for ATP based on analyte-induced dissociation of ferrocene-aptamer conjugates from manganese dioxide nanosheets on a screen-printed carbon electrode

International Nuclear Information System (INIS)

Tang, Dianping; Hou, Li

2016-01-01

The authors report on a new electrochemical aptasensing strategy for the determination of adenosine - 5’-triphosphate (ATP) at picomolar levels. First, manganese dioxide (MnO 2 ) nanosheets with an average size of ∼70 nm were synthesized via a hot-injection method on the basis of reaction between potassium permanganate and the cationic detergent cetyltrimethylammonium bromide. The resulting MnO 2 nanosheets were then immobilized onto a pretreated screen-printed carbon electrode which readily binds the ferrocene-labeled ATP aptamer through the van der Waals force between the nucleobases and the basal plane of the nanoflakes. The immobilized ferrocene-aptamer conjugates activates the electrical contact with the electrode and produces a strong signal in the potentials scanned (0.0 to 1.0 V vs. Ag/AgCl). Upon addition of ATP, it will react with the aptamer and cause the dissociation of the ferrocene-aptamer from the nanosheets, this resulting in a decrease in the electrical signal. Under optimal conditions, this platform exhibits a detection limit as low as 0.32 nM of ATP. The repeatability and intermediate precision is below 10.7 % at a 10 nM concentration level. The method was applied to analyze blank fetal calf serum spiked with ATP, and the recoveries (at 3 concentration levels) ranged between 91.3 and 118 %. This detection scheme is rapid, simple, cost-effective, and does not require extensive sample preparation or multiple washing steps. (author)

Inhibition of the Fe(III)-catalyzed dopamine oxidation by ATP and its relevance to oxidative stress in Parkinson's disease.

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Jiang, Dianlu; Shi, Shuyun; Zhang, Lin; Liu, Lin; Ding, Bingrong; Zhao, Bingqing; Yagnik, Gargey; Zhou, Feimeng

2013-09-18

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic cells, which implicates a role of dopamine (DA) in the etiology of PD. A possible DA degradation pathway is the Fe(III)-catalyzed oxidation of DA by oxygen, which produces neuronal toxins as side products. We investigated how ATP, an abundant and ubiquitous molecule in cellular milieu, affects the catalytic oxidation reaction of dopamine. For the first time, a unique, highly stable DA-Fe(III)-ATP ternary complex was formed and characterized in vitro. ATP as a ligand shifts the catecholate-Fe(III) ligand metal charge transfer (LMCT) band to a longer wavelength and the redox potentials of both DA and the Fe(III) center in the ternary complex. Remarkably, the additional ligation by ATP was found to significantly reverse the catalytic effect of the Fe(III) center on the DA oxidation. The reversal is attributed to the full occupation of the Fe(III) coordination sites by ATP and DA, which blocks O2 from accessing the Fe(III) center and its further reaction with DA. The biological relevance of this complex is strongly implicated by the identification of the ternary complex in the substantia nigra of rat brain and its attenuation of cytotoxicity of the Fe(III)-DA complex. Since ATP deficiency accompanies PD and neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)) induced PD, deficiency of ATP and the resultant impairment toward the inhibition of the Fe(III)-catalyzed DA oxidation may contribute to the pathogenesis of PD. Our finding provides new insight into the pathways of DA oxidation and its relationship with synaptic activity.

Small amounts of functional ATP7A protein permit mild phenotype

DEFF Research Database (Denmark)

Møller, Lisbeth Birk

2015-01-01

concentrations, ATP7A shifts to the post-Golgi compartments or to the plasma membrane to export copper out of the cell. Impaired copper-regulation trafficking has been observed for ATP7A mutants, but its impact on the clinical outcome is not clear. The major problem in patients with MD seems to be insufficient...... of missense mutations on structural models of the ATP7A protein suggests that affected conserved residues generally lead to a severe phenotype. The ATP7A protein traffics within the cells. At low copper levels, ATP7A locates to the Trans-Golgi Network (TGN) to load cuproenzymes with copper, whereas at higher...

ATP release, generation and hydrolysis in exocrine pancreatic duct cells

DEFF Research Database (Denmark)

Kowal, Justyna Magdalena; Yegutkin, G.G.; Novak, Ivana

2015-01-01

Extracellular adenosine triphosphate (ATP) regulates pancreatic duct function via P2Y and P2X receptors. It is well known that ATP is released from upstream pancreatic acinar cells. The ATP homeostasis in pancreatic ducts, which secrete bicarbonate-rich fluid, has not yet been examined. First, ou...... may be important in pancreas physiology and potentially in pancreas pathophysiology....... aim was to reveal whether pancreatic duct cells release ATP locally and whether they enzymatically modify extracellular nucleotides/sides. Second, we wished to explore which physiological and pathophysiological factors may be important in these processes. Using a human pancreatic duct cell line, Capan...

Modeling steady state SO2-dependent changes in capillary ATP concentration using novel O2 micro-delivery methods

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Ghonaim, Nour W.; Fraser, Graham M.; Ellis, Christopher G.; Yang, Jun; Goldman, Daniel

2013-01-01

Adenosine triphosphate (ATP) is known to be released from the erythrocyte in an oxygen (O2) dependent manner. Since ATP is a potent vasodilator, it is proposed to be a key regulator in the pathway that mediates micro-vascular response to varying tissue O2 demand. We propose that ATP signaling mainly originates in the capillaries due to the relatively long erythrocyte transit times in the capillary and the short ATP diffusion distance to the electrically coupled endothelium. We have developed a computational model to investigate the effect of delivering or removing O2 to limited areas at the surface of a tissue with an idealized parallel capillary array on total ATP concentration. Simulations were conducted when exposing full surface to perturbations in tissue O2 tension (PO2) or locally using a circular micro-outlet (~100 μm in diameter), a square micro-slit (200 × 200 μm), or a rectangular micro-slit (1000 μm wide × 200 μm long). Results indicated the rectangular micro-slit has the optimal dimensions for altering hemoglobin saturations (SO2) in sufficient number capillaries to generate effective changes in total [ATP]. This suggests a threshold for the minimum number of capillaries that need to be stimulated in vivo by imposed tissue hypoxia to induce a conducted micro-vascular response. SO2 and corresponding [ATP] changes were also modeled in a terminal arteriole (9 μm in diameter) that replaces 4 surface capillaries in the idealized network geometry. Based on the results, the contribution of terminal arterioles to the net change in [ATP] in the micro-vascular network is minimal although they would participate as O2 sources thus influencing the O2 distribution. The modeling data presented here provide important insights into designing a novel micro-delivery device for studying micro-vascular O2 regulation in the capillaries in vivo. PMID:24069001

Membrane-associated proteolytic activity in Escherichia coli that is stimulated by ATP

International Nuclear Information System (INIS)

Klemes, Y.; Voellmy, R.W.; Goldberg, A.L.

1986-01-01

The degradation of proteins in bacteria requires metabolism energy. One important enzyme in this process is protease La, a soluble ATP-dependent protease encoded by the lon gene. However, lon mutants that lack a functional protease La still show some ATP-dependent protein breakdown. The authors have reported an ATP-stimulated endoproteolytic activity associated with the inner membrane of E. coli. This ATP-stimulated activity is found in normal levels in membranes derived from lon mutants, including strains carrying insertions in the lon gene. The membrane-bound activity hydrolyzes 14 C-methylglobin at a linear rate for up to 3 hours. These fractions also contain appreciable proteolytic activity that is not affected by ATP. The stimulation by ATP requires the presence of Mg 2+ . Nonhydrolyzable ATP analogs (e.g. AMPPNP or ATP-γ-S) and ADP do not enhance proteolysis. Unlike protease La, the membrane-associated enzyme does not degrade the fluorometric substrate, Glt-Ala-Ala-Phe-MNA, in an ATP-stimulated fashion, and its level is not influenced by high temperature of by the gene which regulates the heat-shock response. The enzyme is inhibited by dichloroisocoumarin and certain peptide chloromethyl ketones. They conclude that E. coli contain at least two ATP-dependent proteases with distinct specificities: one is soluble and the other is membrane-associated

A new function for ATP: activating cardiac sympathetic afferents during myocardial ischemia.

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Fu, Liang-Wu; Longhurst, John C

2010-12-01

Myocardial ischemia activates cardiac sympathetic afferents leading to chest pain and reflex cardiovascular responses. Brief myocardial ischemia leads to ATP release in the interstitial space. Furthermore, exogenous ATP and α,β-methylene ATP (α,β-meATP), a P2X receptor agonist, stimulate cutaneous group III and IV sensory nerve fibers. The present study tested the hypothesis that endogenous ATP excites cardiac afferents during ischemia through activation of P2 receptors. Nerve activity of single unit cardiac sympathetic afferents was recorded from the left sympathetic chain or rami communicates (T(2)-T(5)) in anesthetized cats. Single fields of 45 afferents (conduction velocities = 0.25-4.92 m/s) were identified in the left ventricle with a stimulating electrode. Five minutes of myocardial ischemia stimulated 39 of 45 cardiac afferents (8 Aδ, 37 C fibers). Epicardial application of ATP (1-4 μmol) stimulated six ischemically sensitive cardiac afferents in a dose-dependent manner. Additionally, epicardial ATP (2 μmol), ADP (2 μmol), a P2Y agonist, and α,β-meATP (0.5 μmol) significantly activated eight other ischemically sensitive afferents. Third, pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid, a P2 receptor antagonist, abolished the responses of six afferents to epicardial ATP (2 μmol) and attenuated the ischemia-related increase in activity of seven other afferents by 37%. In the absence of P2 receptor blockade, cardiac afferents responded consistently to repeated application of ATP (n = 6) and to recurrent myocardial ischemia (n = 6). Finally, six ischemia-insensitive cardiac spinal afferents did not respond to epicardial ATP (2-4 μmol), although these afferents did respond to epicardial bradykinin. Taken together, these data indicate that, during ischemia, endogenously released ATP activates ischemia-sensitive, but not ischemia-insensitive, cardiac spinal afferents through stimulation of P2 receptors likely located on the cardiac sensory

The ATP hydrolysis and phosphate release steps control the time course of force development in rabbit skeletal muscle.

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Sleep, John; Irving, Malcolm; Burton, Kevin

2005-03-15

The time course of isometric force development following photolytic release of ATP in the presence of Ca(2+) was characterized in single skinned fibres from rabbit psoas muscle. Pre-photolysis force was minimized using apyrase to remove contaminating ATP and ADP. After the initial force rise induced by ATP release, a rapid shortening ramp terminated by a step stretch to the original length was imposed, and the time course of the subsequent force redevelopment was again characterized. Force development after ATP release was accurately described by a lag phase followed by one or two exponential components. At 20 degrees C, the lag was 5.6 +/- 0.4 ms (s.e.m., n = 11), and the force rise was well fitted by a single exponential with rate constant 71 +/- 4 s(-1). Force redevelopment after shortening-restretch began from about half the plateau force level, and its single-exponential rate constant was 68 +/- 3 s(-1), very similar to that following ATP release. When fibres were activated by the addition of Ca(2+) in ATP-containing solution, force developed more slowly, and the rate constant for force redevelopment following shortening-restretch reached a maximum value of 38 +/- 4 s(-1) (n = 6) after about 6 s of activation. This lower value may be associated with progressive sarcomere disorder at elevated temperature. Force development following ATP release was much slower at 5 degrees C than at 20 degrees C. The rate constant of a single-exponential fit to the force rise was 4.3 +/- 0.4 s(-1) (n = 22), and this was again similar to that after shortening-restretch in the same activation at this temperature, 3.8 +/- 0.2 s(-1). We conclude that force development after ATP release and shortening-restretch are controlled by the same steps in the actin-myosin ATPase cycle. The present results and much previous work on mechanical-chemical coupling in muscle can be explained by a kinetic scheme in which force is generated by a rapid conformational change bracketed by two

Synthesis and purification of [γP32]-ATP

International Nuclear Information System (INIS)

Kukuh, Ratnawati; Santoso, Daniel; Basri, T. Hasan; Natalia Adventini

1995-01-01

The synthesis of [γP 3 2]-ATP has been carried out using an enzymes procedure. The compound was formed by the phosphorylation of ADP during the enzymatic conversion of L-α-glycerol-phosphate to 3-phosphoglycerate. In the present study, lactatedehydrogenase and sodium pyruvat were used in order to maintain β-NAD + concentration and to push the reaction of glyceralaldehyde-3-phosphate dehydrogenase towards the formation of 1,3-diphosphoglycerate. L-α-glycerolphosphate was used as primary substrate, as it is more stable than DL-glyceraldehyde-3-phosphate. The enzymatic reaction was stopped by immersing the reaction vessel in boiling water for about 10 minutes. The labelled [γP 3 2]-ATP formed was separated by thin layer chromatography using PEI-cellulose and the spots of [γP 3 2]-ATP and inorganic P 3 2 residue located by autoradiography using X-ray film. The optimum time for the reaction at room temperature was 90 minutes with a labeling efficiency of 94.9 %. Purification of the [γP 3 2]-ATP by anion exchange chromatography using DEAE sephadex yielded a purity of more than 95%. The results showed that the labeled compound [γP 3 2]-ATP can be synthesized via an enzymatic process with a satisfactory yield. (author), 4 refs, 2 tabs, 2 figs

New control method of on-board ATP system of Shinkansen trains

Energy Technology Data Exchange (ETDEWEB)

Fukuda, N.; Watanabe, T. [Railway Technical Research Inst. (Japan)

2000-07-01

We studied a new control method of the on-board automatic train protection (ATP) system for Shinkansen trains to shorten the operation time and not to degrade ride comfort at changes in deceleration of the train, while maintaining the safety and reliability of the present ATP signal system. We propose a new on-board pattern brake control system based on the present ATP data without changing the wayside equipment. By simulating the ATP braking of the proposed control method, we succeeded in shortening the operation time by 48 seconds per one station in comparison with the present ATP brake control system. This paper reports the concept of the system and simulation results of the on-board pattern. (orig.)

ATP as a Multi-target Danger Signal in the Brain

Directory of Open Access Journals (Sweden)

Ricardo J Rodrigues

2015-04-01

Full Text Available ATP is released in an activity-dependent manner from different cell types in the brain, fulfilling different roles as a neurotransmitter, neuromodulator, astrocyte-to-neuron communication, propagating astrocytic responses and formatting microglia responses. This involves the activation of different ATP P2 receptors (P2R as well as adenosine receptors upon extracellular ATP catabolism by ecto-nucleotidases. Notably, brain noxious stimuli trigger a sustained increase of extracellular ATP, which plays a key role as danger signal in the brain. This involves a combined action of extracellular ATP in different cell types, namely increasing the susceptibility of neurons to damage, promoting astrogliosis and recruiting and formatting microglia to mount neuroinflammatory responses. Such actions involve the activation of different receptors, as heralded by neuroprotective effects resulting from blockade mainly of P2X7R, P2Y1R and adenosine A2A receptors (A2AR, which hierarchy, cooperation and/or redundancy is still not resolved. These pleiotropic functions of ATP as a danger signal in brain damage prompt a therapeutic interest to multi-target different purinergic receptors to provide maximal opportunities for neuroprotection.

Mitochondrial toxicity of selective COX-2 inhibitors via inhibition of oxidative phosphorylation (ATP synthesis) in rat liver mitochondria

DEFF Research Database (Denmark)

Syed, Muzeeb; Skonberg, Christian; Hansen, Steen Honoré

2016-01-01

Cyclooxygenase-2 (COX-2) inhibitors (coxibs) are non-steroidal anti-inflammatory drugs (NSAIDs) designed to selectively inhibit COX-2. However, drugs of this therapeutic class are associated with drug induced liver injury (DILI) and mitochondrial injury is likely to play a role. The effects...... of selective COX-2 inhibitors on inhibition of oxidative phosphorylation (ATP synthesis) in rat liver mitochondria were investigated. The order of potency of inhibition of ATP synthesis was: lumiracoxib (IC50: 6.48 ± 2.74 μM)>celecoxib (IC50: 14.92 ± 6.40 μM)>valdecoxib (IC50: 161.4 ± 28.6 μM)>rofecoxib (IC50...... correlation (with r(2)=0.921) was observed between the potency of inhibition of ATP synthesis and the log P values. The in vitro metabolism of coxibs in rat liver mitochondria yielded for each drug substance a major single metabolite and identified a hydroxy metabolite with each of the coxibs...

Application of luciferase assay for ATP to antimicrobial drug susceptibility

Science.gov (United States)

Chappelle, E. W.; Picciolo, G. L.; Vellend, H.; Tuttle, S. A.; Barza, M. J.; Weinstein, L. (Inventor)

1977-01-01

The susceptibility of bacteria, particularly those derived from body fluids, to antimicrobial agents is determined in terms of an ATP index measured by culturing a bacterium in a growth medium. The amount of ATP is assayed in a sample of the cultured bacterium by measuring the amount of luminescent light emitted when the bacterial ATP is reacted with a luciferase-luciferin mixture. The sample of the cultured bacterium is subjected to an antibiotic agent. The amount of bacterial adenosine triphosphate is assayed after treatment with the antibiotic by measuring the luminescent light resulting from the reaction. The ATP index is determined from the values obtained from the assay procedures.

Protein kinase C-mediated ATP stimulation of Na(+)-ATPase activity in LLC-PK1 cells involves a P2Y2 and/or P2Y4 receptor.

Science.gov (United States)

Wengert, M; Ribeiro, M C; Abreu, T P; Coutinho-Silva, R; Leão-Ferreira, L R; Pinheiro, A A S; Caruso-Neves, C

2013-07-15

ATP-activated P2Y receptors play an important role in renal sodium excretion. The aim of this study was to evaluate the modulation of ATPase-driven sodium reabsorption in the proximal tubule by ATP or adenosine (Ado). LLC-PK1 cells, a model of porcine proximal tubule cells, were used. ATP (10(-6)M) or Ado (10(-6)M) specifically stimulated Na(+)-ATPase activity without any changes in (Na(+)+K(+))-ATPase activity. Our results show that the Ado effect is mediated by its conversion to ATP. Furthermore, it was observed that the effect of ATP was mimicked by UTP, ATPγS and 2-thio-UTP, an agonist of P2Y2 and P2Y4 receptors. In addition, ATP-stimulated Na(+)-ATPase activity involves protein kinase C (PKC). Our results indicate that ATP-induced stimulation of proximal tubule Na(+)-ATPase activity is mediated by a PKC-dependent P2Y2 and/or P2Y4 pathway. These findings provide new perspectives on the role of the effect of P2Y-mediated extracellular ATP on renal sodium handling. Copyright © 2013 Elsevier Inc. All rights reserved.

ATP secretion from nerve trunks and Schwann cells mediated by glutamate.

Science.gov (United States)

Liu, Guo Jun; Bennett, Max R

2003-11-14

ATP release from rat sciatic nerves and from cultured Schwann cells isolated from the nerves was investigated using an online bioluminescence technique. ATP was released in relatively large amounts from rat sciatic nerve trunks during electrical stimulation. This release was blocked by the sodium channel inhibitor tetrodotoxin and the non-NMDA glutamate receptor blocker 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Schwann cells isolated from the nerve trunks did not release ATP when electrically stimulated but did in response to glutamate in a concentration-dependent manner. Glutamate-stimulated ATP release was inhibited by specific non-competitive AMPA receptor antagonist GYKI 52466 and competitive non-NMDA receptor antagonist CNQX. Glutamate-stimulated ATP release was decreased by inhibition of anion transporter inhibitors by furosemide, cystic fibrosis transmembrane conductance regulator by glibenclamide and exocytosis by botulinum toxin A, indicating that anion transporters and exocytosis provide the main secretion mechanisms for ATP release from the Schwann cells.

Protective effects of exercise training on endothelial dysfunction induced by total sleep deprivation in healthy subjects.

Science.gov (United States)

Sauvet, Fabien; Arnal, Pierrick J; Tardo-Dino, Pierre Emmanuel; Drogou, Catherine; Van Beers, Pascal; Bougard, Clément; Rabat, Arnaud; Dispersyn, Garance; Malgoyre, Alexandra; Leger, Damien; Gomez-Merino, Danielle; Chennaoui, Mounir

2017-04-01

Sleep loss is a risk factor for cardiovascular events mediated through endothelial dysfunction. To determine if 7weeks of exercise training can limit cardiovascular dysfunction induced by total sleep deprivation (TSD) in healthy young men. 16 subjects were examined during 40-h TSD, both before and after 7weeks of interval exercise training. Vasodilatation induced by ACh, insulin and heat (42°C) and pulse wave velocity (PWV), blood pressure and heart rate (HR) were assessed before TSD (controlday), during TSD, and after one night of sleep recovery. Biomarkers of endothelial activation, inflammation, and hormones were measured from morning blood samples. Before training, ACh-, insulin- and heat-induced vasodilatations were significantly decreased during TSD and recovery as compared with the control day, with no difference after training. Training prevented the decrease of ACh-induced vasodilation related to TSD after sleep recovery, as well as the PWV increase after TSD. A global lowering effect of training was found on HR values during TSD, but not on blood pressure. Training induces the decrease of TNF-α concentration after TSD and prevents the increase of MCP-1 after sleep recovery. Before training, IL-6 concentrations increased. Cortisol and testosterone decreased after TSD as compared with the control day, while insulin and E-selectin increased after sleep recovery. No effect of TSD or training was found on CRP and sICAM-1. In healthy young men, a moderate to high-intensity interval training is effective at improving aerobic fitness and limiting vascular dysfunction induced by TSD, possibly through pro-inflammatory cytokine responses.(ClinicalTrial:NCT02820649). Copyright © 2017 Elsevier B.V. All rights reserved.

atpE gene as a new useful specific molecular target to quantify Mycobacterium in environmental samples

Science.gov (United States)

2013-01-01

Background The environment is the likely source of many pathogenic mycobacterial species but detection of mycobacteria by bacteriological tools is generally difficult and time-consuming. Consequently, several molecular targets based on the sequences of housekeeping genes, non-functional RNA and structural ribosomal RNAs have been proposed for the detection and identification of mycobacteria in clinical or environmental samples. While certain of these targets were proposed as specific for this genus, most are prone to false positive results in complex environmental samples that include related, but distinct, bacterial genera. Nowadays the increased number of sequenced genomes and the availability of software for genomic comparison provide tools to develop novel, mycobacteria-specific targets, and the associated molecular probes and primers. Consequently, we conducted an in silico search for proteins exclusive to Mycobacterium spp. genomes in order to design sensitive and specific molecular targets. Results Among the 3989 predicted proteins from M. tuberculosis H37Rv, only 11 proteins showed 80% to 100% of similarity with Mycobacterium spp. genomes, and less than 50% of similarity with genomes of closely related Corynebacterium, Nocardia and Rhodococcus genera. Based on DNA sequence alignments, we designed primer pairs and a probe that specifically detect the atpE gene of mycobacteria, as verified by quantitative real-time PCR on a collection of mycobacteria and non-mycobacterial species. The real-time PCR method we developed was successfully used to detect mycobacteria in tap water and lake samples. Conclusions The results indicate that this real-time PCR method targeting the atpE gene can serve for highly specific detection and precise quantification of Mycobacterium spp. in environmental samples. PMID:24299240

Statins and ATP regulate nuclear pAkt via the P2X7 purinergic receptor in epithelial cells

International Nuclear Information System (INIS)

Mistafa, Oras; Hoegberg, Johan; Stenius, Ulla

2008-01-01

Many studies have documented P2X7 receptor functions in cells of mesenchymal origin. P2X7 is also expressed in epithelial cells and its role in these cells remains largely unknown. Our data indicate that P2X7 regulate nuclear pAkt in epithelial cells. We show that low concentration of atorvastatin, a drug inhibiting HMG-CoA reductase and cholesterol metabolism, or the natural agonist extracellular ATP rapidly decreased the level of insulin-induced phosphorylated Akt in the nucleus. This effect was seen within minutes and was inhibited by P2X7 inhibitors. Experiments employing P2X7 siRNA and HEK293 cells heterologously expressing P2X7 and in vivo experiments further supported an involvement of P2X7. These data indicate that extracellular ATP and statins via the P2X7 receptor modulate insulin-induced Akt signaling in epithelial cells

Statins and ATP regulate nuclear pAkt via the P2X7 purinergic receptor in epithelial cells

Energy Technology Data Exchange (ETDEWEB)

Mistafa, Oras; Hoegberg, Johan [Institute of Environmental Medicine, Karolinska Institutet, Box 210, 17177 Stockholm (Sweden); Stenius, Ulla [Institute of Environmental Medicine, Karolinska Institutet, Box 210, 17177 Stockholm (Sweden)

2008-01-04

Many studies have documented P2X7 receptor functions in cells of mesenchymal origin. P2X7 is also expressed in epithelial cells and its role in these cells remains largely unknown. Our data indicate that P2X7 regulate nuclear pAkt in epithelial cells. We show that low concentration of atorvastatin, a drug inhibiting HMG-CoA reductase and cholesterol metabolism, or the natural agonist extracellular ATP rapidly decreased the level of insulin-induced phosphorylated Akt in the nucleus. This effect was seen within minutes and was inhibited by P2X7 inhibitors. Experiments employing P2X7 siRNA and HEK293 cells heterologously expressing P2X7 and in vivo experiments further supported an involvement of P2X7. These data indicate that extracellular ATP and statins via the P2X7 receptor modulate insulin-induced Akt signaling in epithelial cells.

Electrical stimuli are anti-apoptotic in skeletal muscle via extracellular ATP. Alteration of this signal in Mdx mice is a likely cause of dystrophy.

Science.gov (United States)

Valladares, Denisse; Almarza, Gonzalo; Contreras, Ariel; Pavez, Mario; Buvinic, Sonja; Jaimovich, Enrique; Casas, Mariana

2013-01-01

ATP signaling has been shown to regulate gene expression in skeletal muscle and to be altered in models of muscular dystrophy. We have previously shown that in normal muscle fibers, ATP released through Pannexin1 (Panx1) channels after electrical stimulation plays a role in activating some signaling pathways related to gene expression. We searched for a possible role of ATP signaling in the dystrophy phenotype. We used muscle fibers from flexor digitorum brevis isolated from normal and mdx mice. We demonstrated that low frequency electrical stimulation has an anti-apoptotic effect in normal muscle fibers repressing the expression of Bax, Bim and PUMA. Addition of exogenous ATP to the medium has a similar effect. In dystrophic fibers, the basal levels of extracellular ATP were higher compared to normal fibers, but unlike control fibers, they do not present any ATP release after low frequency electrical stimulation, suggesting an uncoupling between electrical stimulation and ATP release in this condition. Elevated levels of Panx1 and decreased levels of Cav1.1 (dihydropyridine receptors) were found in triads fractions prepared from mdx muscles. Moreover, decreased immunoprecipitation of Cav1.1 and Panx1, suggest uncoupling of the signaling machinery. Importantly, in dystrophic fibers, exogenous ATP was pro-apoptotic, inducing the transcription of Bax, Bim and PUMA and increasing the levels of activated Bax and cytosolic cytochrome c. These evidence points to an involvement of the ATP pathway in the activation of mechanisms related with cell death in muscular dystrophy, opening new perspectives towards possible targets for pharmacological therapies.

ATP Synthase, a Target for Dementia and Aging?

Science.gov (United States)

Larrick, James W; Larrick, Jasmine W; Mendelsohn, Andrew R

2018-02-01

Advancing age is the biggest risk factor for development for the major life-threatening diseases in industrialized nations accounting for >90% of deaths. Alzheimer's dementia (AD) is among the most devastating. Currently approved therapies fail to slow progression of the disease, providing only modest improvements in memory. Recently reported work describes mechanistic studies of J147, a promising therapeutic molecule previously shown to rescue the severe cognitive deficits exhibited by aged, transgenic AD mice. Apparently, J147 targets the mitochondrial alpha-F1-ATP synthase (ATP5A). Modest inhibition of the ATP synthase modulates intracellular calcium to activate AMP-activated protein kinase to inhibit mammalian target of rapamycin, a known mechanism of lifespan extension from worms to mammals.

Mycobacterium tuberculosis Universal Stress Protein Rv2623 Regulates Bacillary Growth by ATP Binding: Requirement for Establishing Chronic Persistent Infection

Energy Technology Data Exchange (ETDEWEB)

Drumm, J.; Mi, K; Bilder, P; Sun, M; Lim, J; Bielefeldt-Ohmann, H; Basaraba, R; So, M; Zhu, G; et. al.

2009-01-01

Tuberculous latency and reactivation play a significant role in the pathogenesis of tuberculosis, yet the mechanisms that regulate these processes remain unclear. The Mycobacterium tuberculosisuniversal stress protein (USP) homolog, rv2623, is among the most highly induced genes when the tubercle bacillus is subjected to hypoxia and nitrosative stress, conditions thought to promote latency. Induction of rv2623 also occurs when M. tuberculosis encounters conditions associated with growth arrest, such as the intracellular milieu of macrophages and in the lungs of mice with chronic tuberculosis. Therefore, we tested the hypothesis that Rv2623 regulates tuberculosis latency. We observed that an Rv2623-deficient mutant fails to establish chronic tuberculous infection in guinea pigs and mice, exhibiting a hypervirulence phenotype associated with increased bacterial burden and mortality. Consistent with this in vivo growth-regulatory role, constitutive overexpression of rv2623 attenuates mycobacterial growth in vitro. Biochemical analysis of purified Rv2623 suggested that this mycobacterial USP binds ATP, and the 2.9-A-resolution crystal structure revealed that Rv2623 engages ATP in a novel nucleotide-binding pocket. Structure-guided mutagenesis yielded Rv2623 mutants with reduced ATP-binding capacity. Analysis of mycobacteria overexpressing these mutants revealed that the in vitro growth-inhibitory property of Rv2623 correlates with its ability to bind ATP. Together, the results indicate that i M. tuberculosis Rv2623 regulates mycobacterial growth in vitro and in vivo, and ii Rv2623 is required for the entry of the tubercle bacillus into the chronic phase of infection in the host; in addition, iii Rv2623 binds ATP; and iv the growth-regulatory attribute of this USP is dependent on its ATP-binding activity. We propose that Rv2623 may function as an ATP-dependent signaling intermediate in a pathway that promotes persistent infection.

P2X1 receptors localized in lipid rafts mediate ATP motor responses in the human vas deferens longitudinal muscles.

Science.gov (United States)

Donoso, María Verónica; Norambuena, Andrés; Navarrete, Camilo; Poblete, Inés; Velasco, Alfredo; Huidobro-Toro, Juan Pablo

2014-02-01

To assess the role of the P2X1 receptors (P2X1R) in the longitudinal and circular layers of the human vas deferens, ex vivo-isolated strips or rings were prepared from tissue biopsies to record isometric contractions. To ascertain its membrane distribution, tissue extracts were analyzed by immunoblotting following sucrose gradient ultracentrifugation. ATP, alpha,beta-methylene ATP, or electrical field stimulation elicited robust contractions of the longitudinal layer but not of the circular layer which demonstrated inconsistent responses. Alpha,beta-methylene ATP generated stronger and more robust contractions than ATP. In parallel, prostatic segments of the rat vas deferens were examined. The motor responses in both species were not sustained but decayed within the first minute, showing desensitization to additional applications. Cross-desensitization was established between alpha,beta-methylene ATP or ATP-evoked contractions and electrical field stimulation-induced contractions. Full recovery of the desensitized motor responses required more than 30 min and showed a similar pattern in human and rat tissues. Immunoblot analysis of the human vas deferens extracts revealed a P2X1R oligomer of approximately 200 kDa under nonreducing conditions, whereas dithiothreitol-treated extracts showed a single band of approximately 70 kDa. The P2X1R was identified in ultracentrifugation fractions containing 15%-29% sucrose; the receptor localized in the same fractions as flotillin-1, indicating that it regionalized into smooth muscle lipid rafts. In conclusion, ATP plays a key role in human vas deferens contractile responses of the longitudinal smooth muscle layer, an effect mediated through P2X1Rs.

Assembly of the membrane domain of ATP synthase in human mitochondria.

Science.gov (United States)

He, Jiuya; Ford, Holly C; Carroll, Joe; Douglas, Corsten; Gonzales, Evvia; Ding, Shujing; Fearnley, Ian M; Walker, John E

2018-03-20

The ATP synthase in human mitochondria is a membrane-bound assembly of 29 proteins of 18 kinds. All but two membrane components are encoded in nuclear genes, synthesized on cytoplasmic ribosomes, and imported into the matrix of the organelle, where they are assembled into the complex with ATP6 and ATP8, the products of overlapping genes in mitochondrial DNA. Disruption of individual human genes for the nuclear-encoded subunits in the membrane portion of the enzyme leads to the formation of intermediate vestigial ATPase complexes that provide a description of the pathway of assembly of the membrane domain. The key intermediate complex consists of the F 1 -c 8 complex inhibited by the ATPase inhibitor protein IF 1 and attached to the peripheral stalk, with subunits e, f, and g associated with the membrane domain of the peripheral stalk. This intermediate provides the template for insertion of ATP6 and ATP8, which are synthesized on mitochondrial ribosomes. Their association with the complex is stabilized by addition of the 6.8 proteolipid, and the complex is coupled to ATP synthesis at this point. A structure of the dimeric yeast F o membrane domain is consistent with this model of assembly. The human 6.8 proteolipid (yeast j subunit) locks ATP6 and ATP8 into the membrane assembly, and the monomeric complexes then dimerize via interactions between ATP6 subunits and between 6.8 proteolipids (j subunits). The dimers are linked together back-to-face by DAPIT (diabetes-associated protein in insulin-sensitive tissue; yeast subunit k), forming long oligomers along the edges of the cristae.

Nuclear genetic defects of mitochondrial ATP synthase

Czech Academy of Sciences Publication Activity Database

Hejzlarová, Kateřina; Mráček, Tomáš; Vrbacký, Marek; Kaplanová, Vilma; Karbanová, Vendula; Nůsková, Hana; Pecina, Petr; Houštěk, Josef

2014-01-01

Roč. 63, Suppl.1 (2014), S57-S71 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GAP303/11/0970; GA ČR GAP303/12/1363; GA MZd(CZ) NT12370; GA MZd(CZ) NT14050 Grant - others:Univerzita Karlova(CZ) 370411 Institutional support: RVO:67985823 Keywords : mitochondrial diseases * TMEM70 * ATPAF1 * ATP5A1 * ATP5E Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.293, year: 2014

Genetic dysfunction of MT-ATP6 causes axonal Charcot-Marie-Tooth disease.

LENUS (Irish Health Repository)

Pitceathly, Robert D S

2012-09-11

Charcot-Marie-Tooth (CMT) disease is the most common inherited neuromuscular disorder, affecting 1 in 2,500 individuals. Mitochondrial DNA (mtDNA) mutations are not generally considered within the differential diagnosis of patients with uncomplicated inherited neuropathy, despite the essential requirement of ATP for axonal function. We identified the mtDNA mutation m.9185T>C in MT-ATP6, encoding the ATP6 subunit of the mitochondrial ATP synthase (OXPHOS complex V), at homoplasmic levels in a family with mitochondrial disease in whom a severe motor axonal neuropathy was a striking feature. This led us to hypothesize that mutations in the 2 mtDNA complex V subunit encoding genes, MT-ATP6 and MT-ATP8, might be an unrecognized cause of isolated axonal CMT and distal hereditary motor neuropathy (dHMN).

ATP-Binding Cassette Proteins: Towards a Computational View of Mechanism

Science.gov (United States)

Liao, Jielou

2004-03-01

Many large machine proteins can generate mechanical force and undergo large-scale conformational changes (LSCC) to perform varying biological tasks in living cells by utilizing ATP. Important examples include ATP-binding cassette (ABC) transporters. They are membrane proteins that couple ATP binding and hydrolysis to the translocation of substrates across membranes [1]. To interpret how the mechanical force generated by ATP binding and hydrolysis is propagated, a coarse-grained ATP-dependent harmonic network model (HNM) [2,3] is applied to the ABC protein, BtuCD. This protein machine transports vitamin B12 across membranes. The analysis shows that subunits of the protein move against each other in a concerted manner. The lowest-frequency modes of the BtuCD protein are found to link the functionally critical domains, and are suggested to be responsible for large-scale ATP-coupled conformational changes. [1] K. P. Locher, A. T. Lee and D. C. Rees. Science 296, 1091-1098 (2002). [2] Atilgan, A. R., S. R. Durell, R. L. Jernigan, M. C. Demirel, O. Keskin, and I. Bahar. Biophys. J. 80, 505-515(2002); M. M Tirion, Phys. Rev. Lett. 77, 1905-1908 (1996). [3] J. -L. Liao and D. N. Beratan, 2003, to be published.

Processing mechanics of alternate twist ply (ATP) yarn technology

Science.gov (United States)

Elkhamy, Donia Said

Ply yarns are important in many textile manufacturing processes and various applications. The primary process used for producing ply yarns is cabling. The speed of cabling is limited to about 35m/min. With the world's increasing demands of ply yarn supply, cabling is incompatible with today's demand activated manufacturing strategies. The Alternate Twist Ply (ATP) yarn technology is a relatively new process for producing ply yarns with improved productivity and flexibility. This technology involves self plying of twisted singles yarn to produce ply yarn. The ATP process can run more than ten times faster than cabling. To implement the ATP process to produce ply yarns there are major quality issues; uniform Twist Profile and yarn Twist Efficiency. The goal of this thesis is to improve these issues through process modeling based on understanding the physics and processing mechanics of the ATP yarn system. In our study we determine the main parameters that control the yarn twist profile. Process modeling of the yarn twist across different process zones was done. A computational model was designed to predict the process parameters required to achieve a square wave twist profile. Twist efficiency, a measure of yarn torsional stability and bulk, is determined by the ratio of ply yarn twist to singles yarn twist. Response Surface Methodology was used to develop the processing window that can reproduce ATP yarns with high twist efficiency. Equilibrium conditions of tensions and torques acting on the yarns at the self ply point were analyzed and determined the pathway for achieving higher twist efficiency. Mechanistic modeling relating equilibrium conditions to the twist efficiency was developed. A static tester was designed to zoom into the self ply zone of the ATP yarn. A computer controlled, prototypic ATP machine was constructed and confirmed the mechanistic model results. Optimum parameters achieving maximum twist efficiency were determined in this study. The

Gamma-radiation effect of the ATP-ASE-activity in various parts of cotton sprouts

International Nuclear Information System (INIS)

Kazimov, A.K.

1975-01-01

ATP-ase is a thiol enzyme whose sulfhydryl group plays an important role. The transport of substances through biological membranes is the result of the action of the sodium-potassium pump of the cell, which functions with ATP energy. The action of this transport mechanism depends on the activity of ATP-ase. It may be postulated, therefore, that the suppression of the active transport of Na + and K + ions in cells under irradiation is partially the result of a disturbance of the activity of the ATP enzyme system. The author studied the effect of gamma radiation on ATP-ase activity in various parts of seven-day-old seedlings of type 108-F cotton, which were irradiated using Co 60 gamma radiation. The results of the experiment showed that the ATP-ase activity of the cotton seedling rootlets depends on the dose and the time elapsed after irradiation (a table is given). Small radiation doses (0.2 and 0.5 krad) significantly increased ATP-ase activity in the rootlets, while heavy doses inhibited it significantly. Similar results were obtained for the stems and leaves (tables are given). It was estblished that the ATP-ase of cotton seedlings has varying sensitivity to irradiation. The most sensitive ATP-ases were those of the rootlets. The activity of background ATP-ase is less subject to change than Na + and K + activated ATP-ases. For example, while the activity of ATP-ase (without ions) was inhibited by 25% when a 25 krad irradiation dose was administered, the retardation of Na + and K + activated ATP-ases reached 41%. The author suggests that the inhibition of ATP-ase activity under irradiation is mainly the result of a disturbance of the structure of the membrane functions. It is also possible that ATP-ase activity decreases because of a lack of the enzyme substrate - ATP, which is formed during the process of oxydative phosphorylization. A table is also provided showing the effect of irradiation on the activity of ATP-ase activated by various ions in the roots of

31P magnetization transfer measurements of Pi→ATP flux in exercising human muscle.

Science.gov (United States)

Sleigh, Alison; Savage, David B; Williams, Guy B; Porter, David; Carpenter, T Adrian; Brindle, Kevin M; Kemp, Graham J

2016-03-15

Fundamental criticisms have been made over the use of (31)P magnetic resonance spectroscopy (MRS) magnetization transfer estimates of inorganic phosphate (Pi)→ATP flux (VPi-ATP) in human resting skeletal muscle for assessing mitochondrial function. Although the discrepancy in the magnitude of VPi-ATP is now acknowledged, little is known about its metabolic determinants. Here we use a novel protocol to measure VPi-ATP in human exercising muscle for the first time. Steady-state VPi-ATP was measured at rest and over a range of exercise intensities and compared with suprabasal oxidative ATP synthesis rates estimated from the initial rates of postexercise phosphocreatine resynthesis (VATP). We define a surplus Pi→ATP flux as the difference between VPi-ATP and VATP. The coupled reactions catalyzed by the glycolytic enzymes GAPDH and phosphoglycerate kinase (PGK) have been shown to catalyze measurable exchange between ATP and Pi in some systems and have been suggested to be responsible for this surplus flux. Surplus VPi-ATP did not change between rest and exercise, even though the concentrations of Pi and ADP, which are substrates for GAPDH and PGK, respectively, increased as expected. However, involvement of these enzymes is suggested by correlations between absolute and surplus Pi→ATP flux, both at rest and during exercise, and the intensity of the phosphomonoester peak in the (31)P NMR spectrum. This peak includes contributions from sugar phosphates in the glycolytic pathway, and changes in its intensity may indicate changes in downstream glycolytic intermediates, including 3-phosphoglycerate, which has been shown to influence the exchange between ATP and Pi catalyzed by GAPDH and PGK. Copyright © 2016 the American Physiological Society.

Nitric oxide-induced headache may arise from extracerebral arteries as judged from tolerance to isosorbide-5-mononitrate3

DEFF Research Database (Denmark)

Christiansen, I.; Iversen, H.K.; Olesen, Jes

2008-01-01

Long-term exposure to organic nitrates influences different sections of the vascular bed heterogeneously. Continuous dosage of nitrates leads to the development of tolerance both to the vascular effects and to the unwanted adverse effect, headache. Human data on the development of tolerance...... the important differences in the time profiles of appearance of nitrate tolerance in arteries of different vascular beds in man. If vasodilatation is the cause of NO-induced headache the results point to extracerebral arteries as the locus of nociception. Due to a variety of other possible pain-inducing effects...

Facile conversion of ATP-binding RNA aptamer to quencher-free molecular aptamer beacon.

Science.gov (United States)

Park, Yoojin; Nim-Anussornkul, Duangrat; Vilaivan, Tirayut; Morii, Takashi; Kim, Byeang Hyean

2018-01-15

We have developed RNA-based quencher-free molecular aptamer beacons (RNA-based QF-MABs) for the detection of ATP, taking advantage of the conformational changes associated with ATP binding to the ATP-binding RNA aptamer. The RNA aptamer, with its well-defined structure, was readily converted to the fluorescence sensors by incorporating a fluorophore into the loop region of the hairpin structure. These RNA-based QF-MABs exhibited fluorescence signals in the presence of ATP relative to their low background signals in the absence of ATP. The fluorescence emission intensity increased upon formation of a RNA-based QF-MAB·ATP complex. Copyright © 2017 Elsevier Ltd. All rights reserved.

Direct measurement of newly synthesized ATP dissociation kinetics in sarcoplasmic reticulum ATPase

International Nuclear Information System (INIS)

Teruel-Puche, J.; Kurzmack, M.; Inesi, G.

1987-01-01

Incubation of SR vesicles with Ca 2+ and ( 32 P)acetylphosphate, yields steady state levels of ( 32 P)phosphorylated enzyme (ATPase) intermediate and high concentrations of Ca 2+ in the lumen of the vesicles. At this time, addition of ADP (and EGTA to lower the Ca 2+ concentration in the medium outside the vesicles) results in single cycle formation of (γ- 32 P)ATP by transfer of ( 32 P)phosphate from the enzyme intermediate to ADP. The phosphoenzyme decay and ATP formation exhibit a fast component within the first 20 msec following addition of ADP, and a slower component reaching an asymptote in approximately 100 msec. They have now measured by a rapid filtration method the fraction of newly synthesized ATP which is bound to the enzyme, as opposed to the fraction dissociated into the medium. They find that nearly all the ATP formed during the initial burst is still bound to the enzyme within the initial 20 msec of reaction. Dissociation of newly synthesized ATP occurs then with approximately 13 sec -1 rate constant, permitting reequilibration of the system and further formation of ATP. The rate limiting effect of ATP dissociation and other partial reactions on the slow component of single cycle ATP synthesis is evaluated by appropriate kinetic simulations

How Native and Alien Metal Cations Bind ATP: Implications for Lithium as a Therapeutic Agent

Science.gov (United States)

Dudev, Todor; Grauffel, Cédric; Lim, Carmay

2017-02-01

Adenosine triphosphate (ATP), the major energy currency of the cell, exists in solution mostly as ATP-Mg. Recent experiments suggest that Mg2+ interacts with the highly charged ATP triphosphate group and Li+ can co-bind with the native Mg2+ to form ATP-Mg-Li and modulate the neuronal purine receptor response. However, it is unclear how the negatively charged ATP triphosphate group binds Mg2+ and Li+ (i.e. which phosphate group(s) bind Mg2+/Li+) and how the ATP solution conformation depends on the type of metal cation and the metal-binding mode. Here, we reveal the preferred ATP-binding mode of Mg2+/Li+ alone and combined: Mg2+ prefers to bind ATP tridentately to each of the three phosphate groups, but Li+ prefers to bind bidentately to the terminal two phosphates. We show that the solution ATP conformation depends on the cation and its binding site/mode, but it does not change significantly when Li+ binds to Mg2+-loaded ATP. Hence, ATP-Mg-Li, like Mg2+-ATP, can fit in the ATP-binding site of the host enzyme/receptor, activating specific signaling pathways.

A comparative study of ATPase subunit 9 (Atp9) gene between ...

African Journals Online (AJOL)

ATPase subunit 9 gene (Atp9) is an important functional gene in mitochondria, and is closely related with energy supply. RNA editing of atp9 gene was associated with male sterility in plants. In this study, the atp9 gene in soybeans was cloned from a soybean cytoplasmic male sterile line NJCMS2A and its maintainer line ...

Prevention of phosphine-induced cytotoxicity by nutrients in HepG2 cells

Directory of Open Access Journals (Sweden)

Marzieh Rashedinia

2016-01-01

Interpretation & conclusions: The results supported the hypothesis that phosphine-induced cytotoxicity was due to decrease of ATP levels. ATP suppliers could prevent its toxicity by generating ATP through glycolysis. α-keto compounds such as dihydroxyacetone and α-ketoglutarate may bind to phosphine and restore mitochondrial respiration.

ATP-induced temperature independence of hemoglobin-O2 affinity in heterothermic billfish

DEFF Research Database (Denmark)

Weber, Roy E.; Campbell, Kevin L.; Fago, Angela

2010-01-01

heterotherms, where it may hamper unloading (e.g. in cold extremities of arctic mammals) or increase the diffusive arterio-venous short-circuiting of O2 (e.g. in counter-current heat exchangers of warm swimming muscles of tuna). We hypothesized analogous blood specializations in heterothermic billfish, whose......The inverse relationship between temperature and hemoglobin-O2 affinity resulting from the exothermic nature of heme oxygenation favors O2 unloading from blood to warm, metabolically active tissues. However, this temperature sensitivity is maladaptive, and commonly countered in regional...... to allosterically modulating hemoglobin-O2 affinity, ATP diminishes its temperature sensitivity, reducing deleterious arterio-venous short-circuiting of oxygen in the cranial billfish heat exchangers. The mechanism underlying this reduction in oxygenation enthalpy differs fundamentally from that in tuna, supporting...

Quantitative proteomic analysis of human lung tumor xenografts treated with the ectopic ATP synthase inhibitor citreoviridin.

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Yi-Hsuan Wu

Full Text Available ATP synthase is present on the plasma membrane of several types of cancer cells. Citreoviridin, an ATP synthase inhibitor, selectively suppresses the proliferation and growth of lung cancer without affecting normal cells. However, the global effects of targeting ectopic ATP synthase in vivo have not been well defined. In this study, we performed quantitative proteomic analysis using isobaric tags for relative and absolute quantitation (iTRAQ and provided a comprehensive insight into the complicated regulation by citreoviridin in a lung cancer xenograft model. With high reproducibility of the quantitation, we obtained quantitative proteomic profiling with 2,659 proteins identified. Bioinformatics analysis of the 141 differentially expressed proteins selected by their relative abundance revealed that citreoviridin induces alterations in the expression of glucose metabolism-related enzymes in lung cancer. The up-regulation of enzymes involved in gluconeogenesis and storage of glucose indicated that citreoviridin may reduce the glycolytic intermediates for macromolecule synthesis and inhibit cell proliferation. Using comprehensive proteomics, the results identify metabolic aspects that help explain the antitumorigenic effect of citreoviridin in lung cancer, which may lead to a better understanding of the links between metabolism and tumorigenesis in cancer therapy.

Luminescent Immunoprecipitation System (LIPS) for Detection of Autoantibodies Against ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase in Atrophic Body Gastritis Patients

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Lahner, Edith; Brigatti, Cristina; Marzinotto, Ilaria; Carabotti, Marilia; Scalese, Giulia; Davidson, Howard W; Wenzlau, Janet M; Bosi, Emanuele; Piemonti, Lorenzo; Annibale, Bruno; Lampasona, Vito

2017-01-01

Objectives: Circulating autoantibodies targeting the H+/K+-ATPase proton pump of gastric parietal cells are considered markers of autoimmune gastritis, whose diagnostic accuracy in atrophic body gastritis, the pathological lesion of autoimmune gastritis, remains unknown. This study aimed to assess autoantibodies against ATP4A and ATP4B subunits of parietal cells H+, K+-ATPase in atrophic body gastritis patients and controls. Methods: One-hundred and four cases with atrophic body gastritis and 205 controls were assessed for serological autoantibodies specific for ATP4A or ATP4B subunits using luminescent immunoprecipitation system (LIPS). Recombinant luciferase-reporter-fused-antigens were expressed by in vitro transcription-translation (ATP4A) or after transfection in Expi293F cells (ATP4B), incubated with test sera, and immune complexes recovered using protein-A-sepharose. LIPS assays were compared with a commercial enzyme immunoassay (EIA) for parietal cell autoantibodies. Results: ATP4A and ATP4B autoantibody titers were higher in cases compared to controls (Pgastritis. Both assays had the highest sensitivity, at the cost of diagnostic accuracy (89 and 90% specificity), outperforming traditional EIA. Once validated, these LIPS assays should be valuable screening tools for detecting biomarkers of damaged atrophic oxyntic mucosa. PMID:28102858

'Domino' systems biology and the 'A' of ATP.

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Verma, Malkhey; Zakhartsev, Maksim; Reuss, Matthias; Westerhoff, Hans V

2013-01-01

We develop a strategic 'domino' approach that starts with one key feature of cell function and the main process providing for it, and then adds additional processes and components only as necessary to explain provoked experimental observations. The approach is here applied to the energy metabolism of yeast in a glucose limited chemostat, subjected to a sudden increase in glucose. The puzzles addressed include (i) the lack of increase in adenosine triphosphate (ATP) upon glucose addition, (ii) the lack of increase in adenosine diphosphate (ADP) when ATP is hydrolyzed, and (iii) the rapid disappearance of the 'A' (adenine) moiety of ATP. Neither the incorporation of nucleotides into new biomass, nor steady de novo synthesis of adenosine monophosphate (AMP) explains. Cycling of the 'A' moiety accelerates when the cell's energy state is endangered, another essential domino among the seven required for understanding of the experimental observations. This new domino analysis shows how strategic experimental design and observations in tandem with theory and modeling may identify and resolve important paradoxes. It also highlights the hitherto unexpected role of the 'A' component of ATP. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

St36 electroacupuncture activates nNOS, iNOS and ATP-sensitive potassium channels to promote orofacial antinociception in rats.

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Almeida, R T; Galdino, G; Perez, A C; Silva, G; Romero, T R; Duarte, I D

2017-02-01

Orofacial pain is pain perceived in the face and/or oral cavity, generally caused by diseases or disorders of regional structures, by dysfunction of the nervous system, or through referral from distant sources. Treatment of orofacial pain is mainly pharmacological, but it has increased the number of reports demonstrating great clinical results with the use of non-pharmacological therapies, among them electroacupuncture. However, the mechanisms involved in the electroacupuncture are not well elucidated. Thus, the present study investigate the involvement of the nitric oxide synthase (NOS) and ATP sensitive K + channels (KATP) in the antinociception induced by electroacupuncture (EA) at acupoint St36. Thermal nociception was applied in the vibrissae region of rats, and latency time for face withdrawal was measured. Electrical stimulation of acupoint St36 for 20 minutes reversed the thermal withdrawal latency and this effect was maintained for 150 min. Intraperitoneal administration of specific inhibitors of neuronal nitric oxide synthase (nNOS), inducible nitric oxide synthase (iNOS) and a KATP channels blocker reversed the antinociception induced by EA. Furthermore, nitrite concentration in cerebrospinal fluid (CSF) and plasma, increased 4 and 3-fold higher, respectively, after EA. This study suggests that NO participates of antinociception induced by EA by nNOS, iNOS and ATP-sensitive K + channels activation.

ATP storage and uptake by isolated pancreatic zymogen granules

DEFF Research Database (Denmark)

Haanes, Kristian Agmund; Novak, Ivana

2010-01-01

ATP is released from pancreatic acini in response to cholinergic and hormonal stimulation. The same stimuli cause exocytosis of ZG (zymogen granules) and release of digestive enzymes. The aim of the present study was to determine whether ZG stored ATP and to characterize the uptake mechanism for ...

Acid and stretch, but not capsaicin, are effective stimuli for ATP release in the porcine bladder mucosa: Are ASIC and TRPV1 receptors involved?

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Sadananda, Prajni; Kao, Felicity C L; Liu, Lu; Mansfield, Kylie J; Burcher, Elizabeth

2012-05-15

Stretch-evoked ATP release from the bladder mucosa is a key event in signaling bladder fullness. Our aim was to examine whether acid and capsaicin can also release ATP and to determine the receptors involved, using agonists and antagonists at TRPV1 and acid-sensing ion channels (ASICs). Strips of porcine bladder mucosa were exposed to acid, capsaicin or stretch. Strip tension was monitored. Bath fluid was collected for ATP measurement. Gene expression of ASICs and TRPV1 in porcine bladders was quantified using quantitative real-time PCR (qRT-PCR). Stretch stimulus (150% of original length) repeatedly and significantly increased ATP release to approximately 45 times basal release. Acid (pH 6.5, 6.0, 5.6) contracted mucosal strips and also increased ATP release up to 30-fold, without evidence of desensitization. Amiloride (0.3 μM) reduced the acid-evoked ATP release by approximately 70%, while capsazepine (10 μM) reduced acid-evoked ATP release at pH 6.0 and pH 5.6 (by 68% and 61%, respectively). Capsaicin (0.1-10 μM) was ineffective in causing ATP release, and also failed to contract porcine mucosal or detrusor strips. Gene expression for ASIC1, ASIC2, ASIC3 and TRPV1 was seen in the lateral wall, dome, trigone and neck of both detrusor and mucosa. In conclusion, stretch and acid induce ATP release in the porcine bladder mucosa, but capsaicin is ineffective. The pig bladder is a well-known model for the human bladder, however these data suggest that it should be used with caution, particularly for TRPV1 related studies. Copyright © 2012 Elsevier B.V. All rights reserved.

Removal of urothelium affects bladder contractility and release of ATP but not release of NO in rat urinary bladder

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Boone Timothy B

2010-05-01

Full Text Available Abstract Background The objective of our work was to investigate both the contractile function and the release of ATP and NO from strips of bladder tissue after removal of the urothelium. Methods The method of removal was a gentle swabbing motion rather than a sharp surgical cutting to separate the urothelium from the smooth muscle. The contractile response and ATP and NO release were measured in intact as well as on swabbed preparations. The removal of the urothelial layer was affirmed microscopically. Results After the swabbing, the smaller contractions were evoked by electrical as well as by chemical stimulation (50 μM carbachol or 50 μM α, β meATP. Electrical stimulation, carbachol and substance P (5 μM evoked lower release of ATP in the swabbed strips than in intact strips. Although release of NO evoked by electrical stimulation or substance P was not changed, release of NO evoked by carbachol was significantly less in the swabbed preparations. Conclusion Since swabbing removes only the urothelium, the presence of the suburothelial layer may explain the difference between our findings and those of others who found an increase in contractility. Evoked release of ATP is reduced in swabbed strips, indicating that ATP derives solely from the urothelium. On the other hand, electrical stimulation and substance P evoke identical degrees of NO release in both intact and swabbed preparations, suggesting that NO can be released from the suburothelium. Conversely, carbachol-induced release of NO is lower in swabbed strips, implying that the cholinergic receptors (muscarinic or nicotinic are located in the upper layer of the urothelium.

Blood flow in skin, subcutaneous adipose tissue and skeletal muscle in the forearm of normal man during an oral glucose load

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Bülow, J; Astrup, A; Christensen, N J

1987-01-01

Blood flow to the forearm, and the subcutaneous tissue and skin in the forearm were measured by strain gauge plethysmography, 133Xe-elimination and Laser Doppler flowmetry during an oral glucose load (I g glucose kg-1 lean body mass) and during control conditions. The forearm blood flow remained...... constant during both experiments. Glucose induced a two-fold vasodilatation in subcutaneous tissue. In skin, glucose induced a relative vasodilatation and later a relative vasoconstriction compared with control experiments. When estimated from forearm blood flow and subcutaneous and skin blood flows......, muscle blood flow decreased about 20-30% during both experiments. Proximal nervous blockade did not abolish the glucose-induced vasodilatation in subcutaneous tissue. In the glucose experiment, arterial glucose concentration increased to 7.8 +/- 1.17 mmol l-1 30 min after the load was given...

Stimulation by ATP of proinsulin to insulin conversion in isolated rat pancreatic islet secretory granules. Association with the ATP-dependent proton pump

International Nuclear Information System (INIS)

Rhodes, C.J.; Lucas, C.A.; Mutkoski, R.L.; Orci, L.; Halban, P.A.

1987-01-01

Isolated rat pancreatic islets were pulse-labeled for 5 min with [ 3 H]leucine then chased for 25 min, during which time endogenously labeled [ 3 H]proinsulin becomes predominantly compartmented in immature secretory granules. The islets were then homogenized in isotonic sucrose (pH 7.4) and a beta-granule preparation obtained by differential centrifugation and discontinuous sucrose gradient ultracentrifugation. This preparation was enriched 8-fold in beta-granules. Aside from contamination with mitochondria and a limited number of lysosomes, the beta-granule preparation was essentially free of any other organelles involved in proinsulin synthesis and packaging (i.e. microsomal elements and, more particularly, Golgi complex). Conversion of endogenously labeled [ 3 H]proinsulin was followed in this beta-granule fraction for up to 2 h at 37 degrees C in a buffer (pH 7.3) that mimicked the cationic constituents of B-cell cytosol, during which time 92% of the beta-granules remained intact. Proinsulin conversion was analyzed by high performance liquid chromatography. The rate of proinsulin conversion to insulin was stimulated by 2.2 +/- 0.1-fold (n = 6) (at a 60-min incubation) in the presence of ATP (2 mM) and an ATP regenerating system compared to beta-granule preparations incubated without ATP. This ATP stimulation was abolished in the presence of beta-granule proton pump ATPase inhibitors (tributyltin, 2.5 microM, or 1,3-dicyclohexylcarbodiimide, 50 microM). Inhibitors of mitochondrial proton pump ATPases had no effect on the ATP stimulation of proinsulin conversion. When granules were incubated in a more acidic buffer, proinsulin conversion was increased relative to that at pH 7.3. At pH 5.5, ATP no longer stimulated conversion, and tributyltin and 1,3-dicyclohexylcarbodiimide had no effect

The scaffold protein calcium/calmodulin-dependent serine protein kinase controls ATP release in sensory ganglia upon P2X3 receptor activation and is part of an ATP keeper complex.

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Bele, Tanja; Fabbretti, Elsa

2016-08-01

P2X3 receptors, gated by extracellular ATP, are expressed by sensory neurons and are involved in peripheral nociception and pain sensitization. The ability of P2X3 receptors to transduce extracellular stimuli into neuronal signals critically depends on the dynamic molecular partnership with the calcium/calmodulin-dependent serine protein kinase (CASK). The present work used trigeminal sensory neurons to study the impact that activation of P2X3 receptors (evoked by the agonist α,β-meATP) has on the release of endogenous ATP and how CASK modulates this phenomenon. P2X3 receptor function was followed by ATP efflux via Pannexin1 (Panx1) hemichannels, a mechanism that was blocked by the P2X3 receptor antagonist A-317491, and by P2X3 silencing. ATP efflux was enhanced by nerve growth factor, a treatment known to potentiate P2X3 receptor function. Basal ATP efflux was not controlled by CASK, and carbenoxolone or Pannexin silencing reduced ATP release upon P2X3 receptor function. CASK-controlled ATP efflux followed P2X3 receptor activity, but not depolarization-evoked ATP release. Molecular biology experiments showed that CASK was essential for the transactivation of Panx1 upon P2X3 receptor activation. These data suggest that P2X3 receptor function controls a new type of feed-forward purinergic signaling on surrounding cells, with consequences at peripheral and spinal cord level. Thus, P2X3 receptor-mediated ATP efflux may be considered for the future development of pharmacological strategies aimed at containing neuronal sensitization. P2X3 receptors are involved in sensory transduction and associate to CASK. We have studied in primary sensory neurons the molecular mechanisms downstream P2X3 receptor activation, namely ATP release and partnership with CASK or Panx1. Our data suggest that CASK and P2X3 receptors are part of an ATP keeper complex, with important feed-forward consequences at peripheral and central level. © 2016 International Society for Neurochemistry.

Effects and mechanism of acid rain on plant chloroplast ATP synthase.

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Sun, Jingwen; Hu, Huiqing; Li, Yueli; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

2016-09-01

Acid rain can directly or indirectly affect plant physiological functions, especially photosynthesis. The enzyme ATP synthase is the key in photosynthetic energy conversion, and thus, it affects plant photosynthesis. To clarify the mechanism by which acid rain affects photosynthesis, we studied the effects of acid rain on plant growth, photosynthesis, chloroplast ATP synthase activity and gene expression, chloroplast ultrastructure, intracellular H(+) level, and water content of rice seedlings. Acid rain at pH 4.5 remained the chloroplast structure unchanged but increased the expression of six chloroplast ATP synthase subunits, promoted chloroplast ATP synthase activity, and increased photosynthesis and plant growth. Acid rain at pH 4.0 or less decreased leaf water content, destroyed chloroplast structure, inhibited the expression of six chloroplast ATP synthase subunits, decreased chloroplast ATP synthase activity, and reduced photosynthesis and plant growth. In conclusion, acid rain affected the chloroplast ultrastructure, chloroplast ATPase transcription and activity, and P n by changing the acidity in the cells, and thus influencing the plant growth and development. Finally, the effects of simulated acid rain on the test indices were found to be dose-dependent.

Spectrographic study of neodymium complexing with ATP and ADP

International Nuclear Information System (INIS)

Svetlova, I.E.; Dobrynina, N.A.; Martynenko, L.N.

1989-01-01

By spectrographic method neodymium complexing with ATP and ADP in aqueous solutions at different pH values has been studied. The composition of the complexes was determined by the method of isomolar series. On the basis of analysis of absorption spectra it has been ascertained that at equimolar ratio of Nd 3+ and ATP absorption band of L278A corresponds to monocomplex, and the band of 4290 A - to biscomplex. For the complexes with ADP the absorption band of 4288 A is referred to bicomplexes. The character of ATP and ADP coordination by Nd 3+ ion is considered. Stability constants of the complexes are calculated

ATP synthase--a marvellous rotary engine of the cell.

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Yoshida, M; Muneyuki, E; Hisabori, T

2001-09-01

ATP synthase can be thought of as a complex of two motors--the ATP-driven F1 motor and the proton-driven Fo motor--that rotate in opposite directions. The mechanisms by which rotation and catalysis are coupled in the working enzyme are now being unravelled on a molecular scale.

The Putative Role of the Non-Gastric H+/K+-ATPase ATP12A (ATP1AL1 as Anti-Apoptotic Ion Transporter: Effect of the H+/K+ ATPase Inhibitor SCH28080 on Butyrate-Stimulated Myelomonocytic HL-60 Cells

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Martin Jakab

2014-10-01

Full Text Available Background/Aims: The ATP12A gene codes for a non-gastric H+/K+ ATPase, which is expressed in a wide variety of tissues. The aim of this study was to test for the molecular and functional expression of the non-gastric H+/K+ ATPase ATP12A/ATP1AL1 in unstimulated and butyrate-stimulated (1 and 10 mM human myelomonocytic HL-60 cells, to unravel its potential role as putative apoptosis-counteracting ion transporter as well as to test for the effect of the H+/K+ ATPase inhibitor SCH28080 in apoptosis. Methods: Real-time reverse-transcription PCR (qRT-PCR was used for amplification and cloning of ATP12A transcripts and to assess transcriptional regulation. BCECF microfluorimetry was used to assess changes of intracellular pH (pHi after acute intracellular acid load (NH4Cl prepulsing. Mean cell volumes (MCV and MCV-recovery after osmotic cell shrinkage (Regulatory Volume Increase, RVI were assessed by Coulter counting. Flow-cytometry was used to measure MCV (Coulter principle, to assess apoptosis (phosphatidylserine exposure to the outer leaflet of the cell membrane, caspase activity, 7AAD staining and differentiation (CD86 expression. Results: We found by RT-PCR, intracellular pH measurements, MCV measurements and flow cytometry that ATP12A is expressed in human myelomonocytic HL-60 cells. Treatment of HL-60 cells with 1 mM butyrate leads to monocyte-directed differentiation whereas higher concentrations (10 mM induce apoptosis as assessed by flow-cytometric determination of CD86 expression, caspase activity, phosphatidylserine exposure on the outer leaflet of the cell membrane and MCV measurements. Transcriptional up-regulation of ATP12A and CD86 is evident in 1 mM butyrate-treated HL-60 cells. The H+/K+ ATPase inhibitor SCH28080 (100 µM diminishes K+-dependent pHi recovery after intracellular acid load and blocks RVI after osmotic cell shrinkage. After seeding, HL-60 cells increase their MCV within the first 24 h in culture, and subsequently

Origin Licensing Requires ATP Binding and Hydrolysis by the MCM Replicative Helicase

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Coster, Gideon; Frigola, Jordi; Beuron, Fabienne; Morris, Edward P.; Diffley, John F.X.

2014-01-01

Summary Loading of the six related Minichromosome Maintenance (MCM) proteins as head-to-head double hexamers during DNA replication origin licensing is crucial for ensuring once-per-cell-cycle DNA replication in eukaryotic cells. Assembly of these prereplicative complexes (pre-RCs) requires the Origin Recognition Complex (ORC), Cdc6, and Cdt1. ORC, Cdc6, and MCM are members of the AAA+ family of ATPases, and pre-RC assembly requires ATP hydrolysis. Here we show that ORC and Cdc6 mutants defective in ATP hydrolysis are competent for origin licensing. However, ATP hydrolysis by Cdc6 is required to release nonproductive licensing intermediates. We show that ATP binding stabilizes the wild-type MCM hexamer. Moreover, by analyzing MCM containing mutant subunits, we show that ATP binding and hydrolysis by MCM are required for Cdt1 release and double hexamer formation. This work alters our view of how ATP is used by licensing factors to assemble pre-RCs. PMID:25087873

[Stabilization of Cadmium Contaminated Soils by Ferric Ion Modified Attapulgite (Fe/ATP)--Characterizations and Stabilization Mechanism].

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Rong, Yang; Li, Rong-bo; Zhou, Yong-li; Chen, Jing; Wang, Lin-ling; Lu, Xiao-hua

2015-08-01

Ferric ion modified attapulgite (Fe/ATP) was prepared by impregnation and its structure and morphology were characterized. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effect of Cadmium( Cd) stabilization in soil with the addition of attapulgite (ATP) and Fe/ATP. The stabilization mechanism of Cd was further elucidated by comparing the morphologies and structure of ATP and Fe/ATP before and after Cd adsorption. Fe/ATP exhibited much better adsorption capacity than ATP, suggesting different adsorption mechanisms occurred between ATP and Fe/ATP. The leaching concentrations of Cd in soil decreased by 45% and 91% respectively, with the addition of wt. 20% ATP and Fe/ATP. The former was attributed to the interaction between Cd2 and --OH groups by chemical binding to form inner-sphere complexes in ATP and the attachment between Cd2+ and the defect sites in ATP framework. Whereas Cd stabilization with Fe/ATP was resulted from the fact that the active centers (--OH bonds or O- sites) on ATP could react with Fe3+ giving Fe--O--Cd-- bridges, which helped stabilize Cd in surface soil. What'more, the ferric oxides and metal hydroxides on the surface of ATP could interact with Cd, probably by the formation of cadmium ferrite. In conclusion, Fe/ATP, which can be easily prepared, holds promise as a potential low-cost and environmental friendly stabilizing agent for remediation of soil contaminated with heavy metals.

Conserved phosphoryl transfer mechanisms within kinase families and the role of the C8 proton of ATP in the activation of phosphoryl transfer

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Kenyon Colin P

2012-03-01

Full Text Available Abstract Background The kinome is made up of a large number of functionally diverse enzymes, with the classification indicating very little about the extent of the conserved kinetic mechanisms associated with phosphoryl transfer. It has been demonstrated that C8-H of ATP plays a critical role in the activity of a range of kinase and synthetase enzymes. Results A number of conserved mechanisms within the prescribed kinase fold families have been identified directly utilizing the C8-H of ATP in the initiation of phosphoryl transfer. These mechanisms are based on structurally conserved amino acid residues that are within hydrogen bonding distance of a co-crystallized nucleotide. On the basis of these conserved mechanisms, the role of the nucleotide C8-H in initiating the formation of a pentavalent intermediate between the γ-phosphate of the ATP and the substrate nucleophile is defined. All reactions can be clustered into two mechanisms by which the C8-H is induced to be labile via the coordination of a backbone carbonyl to C6-NH2 of the adenyl moiety, namely a "push" mechanism, and a "pull" mechanism, based on the protonation of N7. Associated with the "push" mechanism and "pull" mechanisms are a series of proton transfer cascades, initiated from C8-H, via the tri-phosphate backbone, culminating in the formation of the pentavalent transition state between the γ-phosphate of the ATP and the substrate nucleophile. Conclusions The "push" mechanism and a "pull" mechanism are responsible for inducing the C8-H of adenyl moiety to become more labile. These mechanisms and the associated proton transfer cascades achieve the proton transfer via different family-specific conserved sets of amino acids. Each of these mechanisms would allow for the regulation of the rate of formation of the pentavalent intermediate between the ATP and the substrate nucleophile. Phosphoryl transfer within kinases is therefore a specific event mediated and regulated via the

The P2X7 ATP receptor modulates renal cyst development in vitro

International Nuclear Information System (INIS)

Hillman, Kate A.; Woolf, Adrian S.; Johnson, Tanya M.; Wade, Angela; Unwin, Robert J.; Winyard, Paul J.D.

2004-01-01

P2X 7 , a piercing receptor, is expressed in renal collecting ducts as they undergo fulminant cysto genesis in the cpk/cpk mouse model of autosomal recessive polycystic kidney disease (ARPKD). Dissociated cpk/cpk kidneys generate cysts from cell aggregates within 24 h of suspension culture and we demonstrate that BzATP, a P2X 7 agonist, reduces cystogenesis. This effect is P2X 7 -specific, because: (i) equimolar concentrations of other purinergic agonists, ATP and UTP, had lesser effects and (ii) the P2X 7 inhibitor, oxidized ATP, abrogated the BzATP-mediated reduction in cystogenesis. BzATP did not significantly affect total cell number, proliferation, LDH release or caspase 3 activity, and zVAD-fmk, a caspase blocker, failed to modulate BzATP effects. In addition, this P2X 7 agonist did not significantly alter cyst size, probably excluding altered vectorial transport. In vivo, ATP was detected in cyst fluid from cpk/cpk kidneys; moreover, P2X 7 protein was also upregulated in human fetal ARPKD epithelia versus normal fetal collecting ducts. Thus, ATP may inhibit pathological renal cyst growth through P2X 7 signaling

Utilization of adenosine triphosphate in rat mast cells during histamine release induced by the ionophore A23187

DEFF Research Database (Denmark)

Johansen, Torben

1979-01-01

The role of endogenous adenosine triphosphate (ATP) in histamine release from rat mast cells induced by the ionophore A23187 in vitro has been studied. 2 The amount of histamine released by calcium from rat mast cells primed with the ionophore A23187 was dependent on the ATP content of the mast...... cells. 3 In aerobic experiments a drastic reduction in mast cell ATP content was found during the time when histamine release induced by A23187 takes place. 4 Anaerobic experiments were performed with metabolic inhibitors (antimycin A, oligomycin, and carbonyl cyanide p......-trifluorometroxyphenylnydrazone), which are known to block the energy-dependent calcium uptake by isolated mitochondria. The mast cell ATP content was reduced during A23187-induced histamine release under anaerobic conditions in the presence of glucose. This indicates an increased utilization of ATP during the release process. 5...

Role of connexin 32 hemichannels in the release of ATP from peripheral nerves.

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Nualart-Marti, Anna; del Molino, Ezequiel Mas; Grandes, Xènia; Bahima, Laia; Martin-Satué, Mireia; Puchal, Rafel; Fasciani, Ilaria; González-Nieto, Daniel; Ziganshin, Bulat; Llobet, Artur; Barrio, Luis C; Solsona, Carles

2013-12-01

Extracellular purines elicit strong signals in the nervous system. Adenosine-5'-triphosphate (ATP) does not spontaneously cross the plasma membrane, and nervous cells secrete ATP by exocytosis or through plasma membrane proteins such as connexin hemichannels. Using a combination of imaging, luminescence and electrophysiological techniques, we explored the possibility that Connexin 32 (Cx32), expressed in Schwann cells (SCs) myelinating the peripheral nervous system could be an important source of ATP in peripheral nerves. We triggered the release of ATP in vivo from mice sciatic nerves by electrical stimulation and from cultured SCs by high extracellular potassium concentration-evoked depolarization. No ATP was detected in the extracellular media after treatment of the sciatic nerve with Octanol or Carbenoxolone, and ATP release was significantly inhibited after silencing Cx32 from SCs cultures. We investigated the permeability of Cx32 to ATP by expressing Cx32 hemichannels in Xenopus laevis oocytes. We found that ATP release is coupled to the inward tail current generated after the activation of Cx32 hemichannels by depolarization pulses, and it is sensitive to low extracellular calcium concentrations. Moreover, we found altered ATP release in mutated Cx32 hemichannels related to the X-linked form of Charcot-Marie-Tooth disease, suggesting that purinergic-mediated signaling in peripheral nerves could underlie the physiopathology of this neuropathy. Copyright © 2013 Wiley Periodicals, Inc.

Multiscale approach to link red blood cell dynamics, shear viscosity, and ATP release.

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Forsyth, Alison M; Wan, Jiandi; Owrutsky, Philip D; Abkarian, Manouk; Stone, Howard A

2011-07-05

RBCs are known to release ATP, which acts as a signaling molecule to cause dilation of blood vessels. A reduction in the release of ATP from RBCs has been linked to diseases such as type II diabetes and cystic fibrosis. Furthermore, reduced deformation of RBCs has been correlated with myocardial infarction and coronary heart disease. Because ATP release has been linked to cell deformation, we undertook a multiscale approach to understand the links between single RBC dynamics, ATP release, and macroscopic viscosity all at physiological shear rates. Our experimental approach included microfluidics, ATP measurements using a bioluminescent reaction, and rheology. Using microfluidics technology with high-speed imaging, we visualize the deformation and dynamics of single cells, which are known to undergo motions such as tumbling, swinging, tanktreading, and deformation. We report that shear thinning is not due to cellular deformation as previously believed, but rather it is due to the tumbling-to-tanktreading transition. In addition, our results indicate that ATP release is constant at shear stresses below a threshold (3 Pa), whereas above the threshold ATP release is increased and accompanied by large cellular deformations. Finally, performing experiments with well-known inhibitors, we show that the Pannexin 1 hemichannel is the main avenue for ATP release both above and below the threshold, whereas, the cystic fibrosis transmembrane conductance regulator only contributes to deformation-dependent ATP release above the stress threshold.

Hsc70/Hsp90 chaperone machinery mediates ATP-dependent RISC loading of small RNA duplexes.

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Iwasaki, Shintaro; Kobayashi, Maki; Yoda, Mayuko; Sakaguchi, Yuriko; Katsuma, Susumu; Suzuki, Tsutomu; Tomari, Yukihide

2010-07-30

Small silencing RNAs--small interfering RNAs (siRNAs) or microRNAs (miRNAs)--direct posttranscriptional gene silencing of their mRNA targets as guides for the RNA-induced silencing complex (RISC). Both siRNAs and miRNAs are born double stranded. Surprisingly, loading these small RNA duplexes into Argonaute proteins, the core components of RISC, requires ATP, whereas separating the two small RNA strands within Argonaute does not. Here we show that the Hsc70/Hsp90 chaperone machinery is required to load small RNA duplexes into Argonaute proteins, but not for subsequent strand separation or target cleavage. We envision that the chaperone machinery uses ATP and mediates a conformational opening of Ago proteins so that they can receive bulky small RNA duplexes. Our data suggest that the chaperone machinery may serve as the driving force for the RISC assembly pathway. Copyright 2010 Elsevier Inc. All rights reserved.

The molecular motor F-ATP synthase is targeted by the tumoricidal protein HAMLET.

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Ho, James; Sielaff, Hendrik; Nadeem, Aftab; Svanborg, Catharina; Grüber, Gerhard

2015-05-22

HAMLET (human alpha-lactalbumin made lethal to tumor cells) interacts with multiple tumor cell compartments, affecting cell morphology, metabolism, proteasome function, chromatin structure and viability. This study investigated if these diverse effects of HAMLET might be caused, in part, by a direct effect on the ATP synthase and a resulting reduction in cellular ATP levels. A dose-dependent reduction in cellular ATP levels was detected in A549 lung carcinoma cells, and by confocal microscopy, co-localization of HAMLET with the nucleotide-binding subunits α (non-catalytic) and β (catalytic) of the energy converting F1F0 ATP synthase was detected. As shown by fluorescence correlation spectroscopy, HAMLET binds to the F1 domain of the F1F0 ATP synthase with a dissociation constant (KD) of 20.5μM. Increasing concentrations of the tumoricidal protein HAMLET added to the enzymatically active α3β3γ complex of the F-ATP synthase lowered its ATPase activity, demonstrating that HAMLET binding to the F-ATP synthase effects the catalysis of this molecular motor. Single-molecule analysis was applied to study HAMLET-α3β3γ complex interaction. Whereas the α3β3γ complex of the F-ATP synthase rotated in a counterclockwise direction with a mean rotational rate of 3.8±0.7s(-1), no rotation could be observed in the presence of bound HAMLET. Our findings suggest that direct effects of HAMLET on the F-ATP synthase may inhibit ATP-dependent cellular processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Insulin induces a positive relationship between the rates of ATP and glycogen changes in isolated rat liver in presence of glucose; a 31P and 13C NMR study.

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Baillet-Blanco, Laurence; Beauvieux, Marie-Christine; Gin, Henri; Rigalleau, Vincent; Gallis, Jean-Louis

2005-11-21

There is an emerging theory suggesting that insulin, which is known to be the predominant postprandial anabolic hormone, is also a major regulator of mitochondrial oxidative phosphorylation in human skeletal muscle. However, little is known about its effects in the liver. Since there is a theoretical relationship between glycogen metabolism and energy status, a simultaneous and continuous investigation of hepatic ATP and glycogen content was performed in intact and isolated perfused liver by 31P and 13C nuclear magnetic resonance (NMR) The hepatic rates of ATP and glycogen changes were evaluated with different concentrations of insulin and glucose during continuous and short-term supply. Liver from rats fed ad libitum were perfused with Krebs-Henseleit Buffer (KHB)(controls) or KHB containing 6 mM glucose, 30 mM glucose, insulin alone, insulin + 6 mM glucose, insulin + 30 mM glucose. In the control, glycogenolysis occurred at a rate of -0.53 +/- 0.021 % x min(-1) and ATP content decreased at a rate of -0.28 +/- 0.029 % x min(-1). In the absence of insulin, there was a close proportional relationship between the glycogen flux and the glucose concentration, whereas ATP rates never varied. With insulin + glucose, both glycogen and ATP rates were strongly related to the glucose concentration; the magnitude of net glycogen flux was linearly correlated to the magnitude of net ATP flux: flux(glycogen) = 72.543(fluxATP) + 172.08, R2 = 0.98. Only the co-infusion of 30 mM glucose and insulin led to (i) a net glycogen synthesis, (ii) the maintenance of the hepatic ATP content, and a strong positive correlation between their net fluxes. This has never previously been reported. The specific effect of insulin on ATP change is likely related to a rapid stimulation of the hepatic mitochondrial oxidative phosphorylation. We propose that variations in the correlation between rates of ATP and glycogen changes could be a probe for insulin resistance due to the action of substrates

Insulin induces a positive relationship between the rates of ATP and glycogen changes in isolated rat liver in presence of glucose; a 31P and 13C NMR study

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Gin Henri

2005-11-01

Full Text Available Abstract Background There is an emerging theory suggesting that insulin, which is known to be the predominant postprandial anabolic hormone, is also a major regulator of mitochondrial oxidative phosphorylation in human skeletal muscle. However, little is known about its effects in the liver. Since there is a theoretical relationship between glycogen metabolism and energy status, a simultaneous and continuous investigation of hepatic ATP and glycogen content was performed in intact and isolated perfused liver by 31P and 13C nuclear magnetic resonance (NMR The hepatic rates of ATP and glycogen changes were evaluated with different concentrations of insulin and glucose during continuous and short-term supply. Results Liver from rats fed ad libitum were perfused with Krebs-Henseleit Buffer (KHB(controls or KHB containing 6 mM glucose, 30 mM glucose, insulin alone, insulin + 6 mM glucose, insulin + 30 mM glucose. In the control, glycogenolysis occurred at a rate of -0.53 ± 0.021 %·min-1 and ATP content decreased at a rate of -0.28 ± 0.029 %·min-1. In the absence of insulin, there was a close proportional relationship between the glycogen flux and the glucose concentration, whereas ATP rates never varied. With insulin + glucose, both glycogen and ATP rates were strongly related to the glucose concentration; the magnitude of net glycogen flux was linearly correlated to the magnitude of net ATP flux: fluxglycogen = 72.543(fluxATP + 172.08, R2 = 0.98. Conclusion Only the co-infusion of 30 mM glucose and insulin led to (i a net glycogen synthesis, (ii the maintenance of the hepatic ATP content, and a strong positive correlation between their net fluxes. This has never previously been reported. The specific effect of insulin on ATP change is likely related to a rapid stimulation of the hepatic mitochondrial oxidative phosphorylation. We propose that variations in the correlation between rates of ATP and glycogen changes could be a probe for insulin

De novo mutations in ATP1A3 cause alternating hemiplegia of childhood

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Heinzen, Erin L; Swoboda, Kathryn J; Hitomi, Yuki

2012-01-01

and their unaffected parents to identify de novo nonsynonymous mutations in ATP1A3 in all seven individuals. In a subsequent sequence analysis of ATP1A3 in 98 other patients with AHC, we found that ATP1A3 mutations were likely to be responsible for at least 74% of the cases; we also identified one inherited mutation...... affecting the level of protein expression. This work identifies de novo ATP1A3 mutations as the primary cause of AHC and offers insight into disease pathophysiology by expanding the spectrum of phenotypes associated with mutations in ATP1A3....

Motor pathway excitability in ATP13A2 mutation carriers

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Zittel, S; Kroeger, J; van der Vegt, J P M

2012-01-01

OBJECTIVE: To describe excitability of motor pathways in Kufor-Rakeb syndrome (PARK9), an autosomal recessive nigro-striatal-pallidal-pyramidal neurodegeneration caused by a mutation in the ATP13A2 gene, using transcranial magnetic stimulation (TMS). METHODS: Five members of a Chilean family...... with an ATP13A2 mutation (one affected mutation carrier (MC) with a compound heterozygous mutation, 4 asymptomatic MC with a single heterozygous mutation) and 11 healthy subjects without mutations were studied. We measured motor evoked potentials (MEP), the contralateral silent period (cSP), short interval....... RESULTS: CSP duration was increased in the symptomatic ATP13A2 MC. The iSP measurements revealed increased interhemispheric inhibition in both the compound heterozygous and the heterozygous MC. CONCLUSION: A compound heterozygous mutation in the ATP13A2 gene is associated with increased intracortical...

Kinetic properties of ATP sulfurylase and APS kinase from Thiobacillus denitrificans.

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Gay, Sean C; Fribourgh, Jennifer L; Donohoue, Paul D; Segel, Irwin H; Fisher, Andrew J

2009-09-01

The Thiobacillus denitrificans genome contains two sequences corresponding to ATP sulfurylase (Tbd_0210 and Tbd_0874). Both genes were cloned and expressed protein characterized. The larger protein (Tbd_0210; 544 residues) possesses an N-terminal ATP sulfurylase domain and a C-terminal APS kinase domain and was therefore annotated as a bifunctional enzyme. But, the protein was not bifunctional because it lacked ATP sulfurylase activity. However, the enzyme did possess APS kinase activity and displayed substrate inhibition by APS. Truncated protein missing the N-terminal domain had APS kinase activity suggesting the function of the inactive sulfurylase domain is to promote the oligomerization of the APS kinase domains. The smaller gene product (Tbd_0874; 402 residues) possessed strong ATP sulfurylase activity with kinetic properties that appear to be kinetically optimized for the direction of APS utilization and ATP+sulfate production, which is consistent with an enzyme that functions physiologically to produce inorganic sulfate.

Local release of ATP into the arterial inflow and venous drainage of human skeletal muscle: insight from ATP determination with the intravascular microdialysis technique

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Mortensen, Stefan; Thaning, Pia; Nyberg, Michael Permin

2011-01-01

is released into plasma, we measured plasma [ATP] with the intravascular microdialysis technique at rest and during dynamic exercise (normoxia and hypoxia), passive exercise, thigh compressions and arterial ATP, tyramine and ACh infusion in a total of 16 healthy young men. Femoral arterial and venous...

ATP measurements for monitoring microbial drinking water quality

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Vang, Óluva Karin

Current standard methods for surveillance of microbial drinking water quality are culture based, which are laborious and time-consuming, where results not are available before one to three days after sampling. This means that the water may have been consumed before results on deteriorated water....... The overall aim of this PhD study was to investigate various methodological features of the ATP assay for a potential implementation on a sensor platform as a real-time parameter for continuous on-line monitoring of microbial drinking water quality. Commercial reagents are commonly used to determine ATP......, microbial quality in distributed water, detection of aftergrowth, biofilm formation etc. This PhD project demonstrated that ATP levels are relatively low and fairly stable in drinking water without chlorine residual despite different sampling locations, different drinking water systems and time of year...

Electrochemical Investigation of the Interaction between Catecholamines and ATP.

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Taleat, Zahra; Estévez-Herrera, Judith; Machado, José D; Dunevall, Johan; Ewing, Andrew G; Borges, Ricardo

2018-02-06

The study of the colligative properties of adenosine 5'-triphosphate (ATP) and catecholamines has received the attention of scientists for decades, as they could explain the capabilities of secretory vesicles (SVs) to accumulate neurotransmitters. In this Article, we have applied electrochemical methods to detect such interactions in vitro, at the acidic pH of SVs (pH 5.5) and examined the effect of compounds having structural similarities that correlate with functional groups of ATP (adenosine, phosphoric acid and sodium phosphate salts) and catecholamines (catechol). Chronoamperometry and fast scan cyclic voltammetry (FSCV) provide evidence compatible with an interaction of the catechol and adenine rings. This interaction is also reinforced by an electrostatic interaction between the phosphate group of ATP and the protonated ammonium group of catecholamines. Furthermore, chronoamperometry data suggest that the presence of ATP subtlety reduces the apparent diffusion coefficient of epinephrine in aqueous media that adds an additional factor leading to a slower rate of catecholamine exocytosis. This adds another plausible mechanism to regulate individual exocytosis events to alter communication.

An ATP sensitive light addressable biosensor for extracellular monitoring of single taste receptor cell.

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Wu, Chunsheng; Du, Liping; Zou, Ling; Zhao, Luhang; Wang, Ping

2012-12-01

Adenosine triphosphate (ATP) is considered as the key neurotransmitter in taste buds for taste signal transmission and processing. Measurements of ATP secreted from single taste receptor cell (TRC) with high sensitivity and specificity are essential for investigating mechanisms underlying taste cell-to-cell communications. In this study, we presented an aptamer-based biosensor for the detection of ATP locally secreted from single TRC. ATP sensitive DNA aptamer was used as recognition element and its DNA competitor was served as signal transduction element that was covalently immobilized on the surface of light addressable potentiometric sensor (LAPS). Due to the light addressable capability of LAPS, local ATP secretion from single TRC can be detected by monitoring the working potential shifts of LAPS. The results show this biosensor can detect ATP with high sensitivity and specificity. It is demonstrated this biosensor can effectively detect the local ATP secretion from single TRC responding to tastant mixture. This biosensor could provide a promising new tool for the research of taste cell-to-cell communications as well as for the detection of local ATP secretion from other types of ATP secreting individual cells.

Silencing of Atp2b1 increases blood pressure through vasoconstriction.

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Shin, Young-Bin; Lim, Ji Eun; Ji, Su-Min; Lee, Hyeon-Ju; Park, So-Yon; Hong, Kyung-Won; Lim, Mihwa; McCarthy, Mark I; Lee, Young-Ho; Oh, Bermseok

2013-08-01

Recent genome-wide association studies (GWASs) have identified 30 genetic loci that regulate blood pressure, increasing our understanding of the cause of hypertension. However, it has been difficult to define the causative genes at these loci due to a lack of functional analyses. In this study, we aimed to validate the candidate gene ATP2B1 in 12q21, variants near which have the strongest association with blood pressure in Asians and Europeans. ATP2B1 functions as a calcium pump to fine-tune calcium concentrations - necessary for repolarization following muscular contractions. We silenced Atp2b1 using an siRNA complex, injected into mouse tail veins. In treated mice, blood pressure rose and the mesenteric arteries increased in wall : lumen ratio. Moreover, the arteries showed enhanced myogenic responses to pressure, and contractile responses to phenylephrine increased compared with the control, suggesting that blood pressure is regulated by ATP2B1 through the contraction and dilation of the vessel, likely by controlling calcium concentrations in the resting state. These results support that ATP2B1 is the causative gene in the blood pressure-associated 12q21 locus and demonstrate that ATP2B1 expression in the vessel influences blood pressure.

Modulation of nucleotide sensitivity of ATP-sensitive potassium channels by phosphatidylinositol-4-phosphate 5-kinase.

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Shyng, S L; Barbieri, A; Gumusboga, A; Cukras, C; Pike, L; Davis, J N; Stahl, P D; Nichols, C G

2000-01-18

ATP-sensitive potassium channels (K(ATP) channels) regulate cell excitability in response to metabolic changes. K(ATP) channels are formed as a complex of a sulfonylurea receptor (SURx), a member of the ATP-binding cassette protein family, and an inward rectifier K(+) channel subunit (Kir6.x). Membrane phospholipids, in particular phosphatidylinositol (PI) 4,5-bisphosphate (PIP(2)), activate K(ATP) channels and antagonize ATP inhibition of K(ATP) channels when applied to inside-out membrane patches. To examine the physiological relevance of this regulatory mechanism, we manipulated membrane PIP(2) levels by expressing either the wild-type or an inactive form of PI-4-phosphate 5-kinase (PIP5K) in COSm6 cells and examined the ATP sensitivity of coexpressed K(ATP) channels. Channels from cells expressing the wild-type PIP5K have a 6-fold lower ATP sensitivity (K(1/2), the half maximal inhibitory concentration, approximately 60 microM) than the sensitivities from control cells (K(1/2) approximately 10 microM). An inactive form of the PIP5K had little effect on the K(1/2) of wild-type channels but increased the ATP-sensitivity of a mutant K(ATP) channel that has an intrinsically lower ATP sensitivity (from K(1/2) approximately 450 microM to K(1/2) approximately 100 microM), suggesting a decrease in membrane PIP(2) levels as a consequence of a dominant-negative effect of the inactive PIP5K. These results show that PIP5K activity, which regulates PIP(2) and PI-3,4,5-P(3) levels, is a significant determinant of the physiological nucleotide sensitivity of K(ATP) channels.

ATP-sensitive K(+-channels in muscle cells: features and physiological role

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O. B. Vadzyuk

2014-08-01

Full Text Available ATP-sensitive K+-channels of plasma membranes belong to the inward rectifier potassium channels type. They are involved in coupling of electrical activity of muscle cell with its metabolic­ state. These channels are heterooctameric and consist of two types of subunits: four poreforming (Kir 6.х and four regulatory (SUR, sulfonylurea receptor. The Kir subunits contain highly selective K+ filter and provide for high-velocity K+ currents. The SUR subunits contain binding sites for activators and blockers and have metabolic sensor, which enables channel activation under conditions of metabolic stress. ATP blocks K+ currents through the ATP-sensitive K+-channels in the most types of muscle cells. However, functional activity of these channels does not depend on absolute concentration of ATP but on the АТР/ADP ratio and presence of Mg2+. Physiologically active substances, such as phosphatidylinositol bisphosphate and fatty acid esters can regulate the activity of these structures in muscle cells. Activation of these channels under ischemic conditions underlies their cytoprotective action, which results in prevention of Ca2+ overload in cytosol. In contrast to ATP-sensitive K+-channels of plasma membranes, the data regarding the structure and function of ATP-sensitive K+-channels of mitochondrial membrane are contradictory. Pore-forming subunits of this channel have not been firmly identified yet. ATP-sensitive K+ transport through the mitochondrial­ membrane is easily tested by different methods, which are briefly reviewed in this paper. Interaction of mitoKATP with physiological and pharmacological ligands is discussed as well.

Effect of irradiation on detection of bacteria in dehydrated vegetables with ATP bioluminescence assay

International Nuclear Information System (INIS)

Xiao Huan; Luo Shishi; Wang Zegang; Feng Min; Zhu Jiating; Chen Xiulan; Zhai Jianqing

2011-01-01

ATP bioluminescence intensity of 4 kinds of irradiated dehydrated vegetables was inconsistent with the bacteria number, the reasons were investigated in this paper. Results showed that irradiation had little effect on background luminescence, and there was no effect on luciferase-luminous system. When irradiation killed the bacteria, the ATPase activity also decreased. As a result, the ATP content in bacteria didn't decreased with the killed of bacteria, which contributed to the increase of free ATP in ATP extract and finally led to the disagreement between the bioluminescence intensity and the actual number of bacteria. When the free ATP in the dehydrated vegetable was removed, the bioluminescence intensity of ATP extract was consistent with the actual number of bacteria in irradiated dehydrated vegetable and ATP bioluminescence technology could be used in bacteria detection of irradiated samples. (authors)

Tomatidine Is a Lead Antibiotic Molecule That Targets Staphylococcus aureus ATP Synthase Subunit C.

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Lamontagne Boulet, Maxime; Isabelle, Charles; Guay, Isabelle; Brouillette, Eric; Langlois, Jean-Philippe; Jacques, Pierre-Étienne; Rodrigue, Sébastien; Brzezinski, Ryszard; Beauregard, Pascale B; Bouarab, Kamal; Boyapelly, Kumaraswamy; Boudreault, Pierre-Luc; Marsault, Éric; Malouin, François

2018-06-01

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of deadly hospital-acquired infections. The discovery of anti- Staphylococcus antibiotics and new classes of drugs not susceptible to the mechanisms of resistance shared among bacteria is imperative. We recently showed that tomatidine (TO), a steroidal alkaloid from solanaceous plants, possesses potent antibacterial activity against S. aureus small-colony variants (SCVs), the notoriously persistent form of this bacterium that has been associated with recurrence of infections. Here, using genomic analysis of in vitro -generated TO-resistant S. aureus strains to identify mutations in genes involved in resistance, we identified the bacterial ATP synthase as the cellular target. Sequence alignments were performed to highlight the modified sequences, and the structural consequences of the mutations were evaluated in structural models. Overexpression of the atpE gene in S. aureus SCVs or introducing the mutation found in the atpE gene of one of the high-level TO-resistant S. aureus mutants into the Bacillus subtilis atpE gene provided resistance to TO and further validated the identity of the cellular target. FC04-100, a TO derivative which also possesses activity against non-SCV strains, prevents high-level resistance development in prototypic strains and limits the level of resistance observed in SCVs. An ATP synthesis assay allowed the observation of a correlation between antibiotic potency and ATP synthase inhibition. The selectivity index (inhibition of ATP production by mitochondria versus that of bacterial ATP synthase) is estimated to be >10 5 -fold for FC04-100. Copyright © 2018 American Society for Microbiology.

Low-level light therapy potentiates NPe6-mediated photodynamic therapy in a human osteosarcoma cell line via increased ATP.

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Tsai, Shang-Ru; Yin, Rui; Huang, Ying-Ying; Sheu, Bor-Ching; Lee, Si-Chen; Hamblin, Michael R

2015-03-01

Low-level light therapy (LLLT) is used to stimulate healing, reduce pain and inflammation, and preserve tissue from dying. LLLT has been shown to protect cells in culture from dying after various cytotoxic insults, and LLLT is known to increase the cellular ATP content. Previous studies have demonstrated that maintaining a sufficiently high ATP level is necessary for the efficient induction and execution of apoptosis steps after photodynamic therapy (PDT). We asked whether LLLT would protect cells from cytotoxicity due to PDT, or conversely whether LLLT would enhance the efficacy of PDT mediated by mono-l-aspartyl chlorin(e6) (NPe6). Increased ATP could lead to enhanced cell uptake of NPe6 by the energy dependent process of endocytosis, and also to more efficient apoptosis. In this study, human osteosarcoma cell line MG-63 was subjected to 1.5J/cm(2) of 810nm near infrared radiation (NIR) followed by addition of 10μM NPe6 and after 2h incubation by 1.5J/cm(2) of 652nm red light for PDT. PDT combined with LLLT led to higher cell death and increased intracellular reactive oxygen species compared to PDT alone. The uptake of NPe6 was moderately increased by LLLT, and cellular ATP was increased. The mitochondrial respiratory chain inhibitor antimycin A abrogated the LLLT-induced increase in cytotoxicity. Taken together, these results demonstrate that LLLT potentiates NPe6-mediated PDT via increased ATP synthesis and is a potentially promising strategy that could be applied in clinical PDT. Copyright © 2014 Elsevier B.V. All rights reserved.

Structure of the N-terminal Gyrase B fragment in complex with ADP⋅Pi reveals rigid-body motion induced by ATP hydrolysis.

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Frédéric V Stanger

Full Text Available Type II DNA topoisomerases are essential enzymes that catalyze topological rearrangement of double-stranded DNA using the free energy generated by ATP hydrolysis. Bacterial DNA gyrase is a prototype of this family and is composed of two subunits (GyrA, GyrB that form a GyrA2GyrB2 heterotetramer. The N-terminal 43-kDa fragment of GyrB (GyrB43 from E. coli comprising the ATPase and the transducer domains has been studied extensively. The dimeric fragment is competent for ATP hydrolysis and its structure in complex with the substrate analog AMPPNP is known. Here, we have determined the remaining conformational states of the enzyme along the ATP hydrolysis reaction path by solving crystal structures of GyrB43 in complex with ADP⋅BeF3, ADP⋅Pi, and ADP. Upon hydrolysis, the enzyme undergoes an obligatory 12° domain rearrangement to accommodate the 1.5 Å increase in distance between the γ- and β-phosphate of the nucleotide within the sealed binding site at the domain interface. Conserved residues from the QTK loop of the transducer domain (also part of the domain interface couple the small structural change within the binding site with the rigid body motion. The domain reorientation is reflected in a significant 7 Å increase in the separation of the two transducer domains of the dimer that would embrace one of the DNA segments in full-length gyrase. The observed conformational change is likely to be relevant for the allosteric coordination of ATP hydrolysis with DNA binding, cleavage/re-ligation and/or strand passage.

Diverse Functional Properties of Wilson Disease ATP7B Variants

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Huster, Dominik; Kühne, Angelika; Bhattacharjee, Ashima; Raines, Lily; Jantsch, Vanessa; Noe, Johannes; Schirrmeister, Wiebke; Sommerer, Ines; Sabri, Osama; Berr, Frieder; Mössner, Joachim; Stieger, Bruno; Caca, Karel; Lutsenko, Svetlana

2012-01-01

BACKGROUND & AIMS Wilson disease is a severe disorder of copper metabolism caused by mutations in ATP7B, which encodes a copper-transporting adenosine triphosphatase. The disease presents with a variable phenotype that complicates the diagnostic process and treatment. Little is known about the mechanisms that contribute to the different phenotypes of the disease. METHODS We analyzed 28 variants of ATP7B from patients with Wilson disease that affected different functional domains; the gene products were expressed using the baculovirus expression system in Sf9 cells. Protein function was analyzed by measuring catalytic activity and copper (64Cu) transport into vesicles. We studied intracellular localization of variants of ATP7B that had measurable transport activities and were tagged with green fluorescent protein in mammalian cells using confocal laser scanning microscopy. RESULTS Properties of ATP7B variants with pathogenic amino-acid substitution varied greatly even if substitutions were in the same functional domain. Some variants had complete loss of catalytic and transport activity, whereas others lost transport activity but retained phosphor-intermediate formation or had partial losses of activity. In mammalian cells, transport-competent variants differed in stability and subcellular localization. CONCLUSIONS Variants in ATP7B associated with Wilson disease disrupt the protein’s transport activity, result in its mislocalization, and reduce its stability. Single assays are insufficient to accurately predict the effects of ATP7B variants the function of its product and development of Wilson disease. These findings will contribute to our understanding of genotype–phenotype correlation and mechanisms of disease pathogenesis. PMID:22240481

Plasma ATP concentration and venous oxygen content in the forearm during dynamic handgrip exercise

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Askew Christopher D

2009-12-01

Full Text Available Abstract Background It has been proposed that adenosine triphosphate (ATP released from red blood cells (RBCs may contribute to the tight coupling between blood flow and oxygen demand in contracting skeletal muscle. To determine whether ATP may contribute to the vasodilatory response to exercise in the forearm, we measured arterialised and venous plasma ATP concentration and venous oxygen content in 10 healthy young males at rest, and at 30 and 180 seconds during dynamic handgrip exercise at 45% of maximum voluntary contraction (MVC. Results Venous plasma ATP concentration was elevated above rest after 30 seconds of exercise (P Conclusions Collectively these results indicate that ATP in the plasma originated from the muscle microcirculation, and are consistent with the notion that deoxygenation of the blood perfusing the muscle acts as a stimulus for ATP release. That ATP concentration was elevated just 30 seconds after the onset of exercise also suggests that ATP may be a contributing factor to the blood flow response in the transition from rest to steady state exercise.

MgATP-concentration dependence of protection of yeast vacuolar V-ATPase from inactivation by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole supports a bi-site catalytic mechanism of ATP hydrolysis

International Nuclear Information System (INIS)

Milgrom, Elena M.; Milgrom, Yakov M.

2012-01-01

Highlights: ► MgATP protects V-ATPase from inactivation by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole. ► V-ATPase activity saturation with MgATP is not sufficient for complete protection. ► The results support a bi-site catalytic mechanism for V-ATPase. -- Abstract: Catalytic site occupancy of the yeast vacuolar V-ATPase during ATP hydrolysis in the presence of an ATP-regenerating system was probed using sensitivity of the enzyme to inhibition by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl). The results show that, regardless of the presence or absence of the proton-motive force across the vacuolar membrane, saturation of V-ATPase activity at increasing MgATP concentrations is accompanied by only partial protection of the enzyme from inhibition by NBD-Cl. Both in the presence and absence of an uncoupler, complete protection of V-ATPase from inhibition by NBD-Cl requires MgATP concentrations that are significantly higher than those expected from the K m values for MgATP. The results are inconsistent with a tri-site model and support a bi-site model for a mechanism of ATP hydrolysis by V-ATPase.

Prostatic relaxation induced by agmatine is decreased in spontaneously hypertensive rats.

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Lee, Liang-Ming; Tsai, Tsung-Chin; Chung, Hsien-Hui; Tong, Yat-Ching; Cheng, Juei-Tang

2012-09-01

What's known on the subject? and What does the study add? Neurotransmitters are known to control prostate contractility. Agmatine is one of them and induces relaxation through imidazoline receptors. The paper shows that the action of agmatine is reduced in hypertensive rats, and that this change is related to the decrease of ATP-sensitive potassium channels in the prostate. The findings can increase our understanding of the possible underlying mechanism for the development of clinical benign prostatic hyperplasia. To compare agmatine-induced prostatic relaxation in hypertensive and control rats. To investigate the responsible mechanism(s) and the role of the ATP-sensitive potassium channel. Prostate strips were isolated from male spontaneously hypertensive (SH) rats and normal Wistar-Kyoto (WKY) rats for measurement of isometric tension. The strips were precontracted with 1 µmol/L phenylephrine or 50 mmol/L KCl. Dose-dependent relaxation of the prostatic strips was studied by cumulative administration of agmatine, 1 to 100 µmol/L, into the organ bath. Effects of specific antagonists on agmatine-induced relaxation were studied. Western blotting analysis was used to measure the gene expression of the ATP-sensitive potassium channel in the rat prostate. Prostatic relaxation induced by agmatine was markedly reduced in SH rats compared with WKY rats. The relaxation caused by agmatine was abolished by BU224, a selective imidazoline I(2)-receptor antagonist, but was not modified by efaroxan at a dose sufficient to block imidazoline I(1)-receptors. The relaxation induced by diazoxide at a concentration sufficient to activate ATP-sensitive potassium channels was markedly reduced in the SH rat prostate. Expressions of ATP-sensitive potassium channel sulphonylurea receptor and inwardly rectifying potassium channel (Kir) 6.2 subunits were both decreased in the prostate of SH rats. The decrease of agmatine-induced prostatic relaxation in SH rats is related to the change in

Training-induced adaptation of oxidative phosphorylation in skeletal muscles.

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Korzeniewski, Bernard; Zoladz, Jerzy A

2003-08-15

Muscle training/conditioning improves the adaptation of oxidative phosphorylation in skeletal muscles to physical exercise. However, the mechanisms underlying this adaptation are still not understood fully. By quantitative analysis of the existing experimental results, we show that training-induced acceleration of oxygen-uptake kinetics at the onset of exercise and improvement of ATP/ADP stability due to physical training are mainly caused by an increase in the amount of mitochondrial proteins and by an intensification of the parallel activation of ATP usage and ATP supply (increase in direct stimulation of oxidative phosphorylation complexes accompanying stimulation of ATP consumption) during exercise.

Gossypol induces pyroptosis in mouse macrophages via a non-canonical inflammasome pathway

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Lin, Qiu-Ru; Li, Chen-Guang; Zha, Qing-Bing; Xu, Li-Hui; Pan, Hao; Zhao, Gao-Xiang; Ouyang, Dong-Yun; He, Xian-Hui

2016-01-01

Gossypol, a polyphenolic compound isolated from cottonseeds, has been reported to possess many pharmacological activities, but whether it can influence inflammasome activation remains unclear. In this study, we found that in mouse macrophages, gossypol induced cell death characterized by rapid membrane rupture and robust release of HMGB1 and pro-caspase-11 comparable to ATP treatment, suggesting an induction of pyroptotic cell death. Unlike ATP, gossypol induced much low levels of mature interleukin-1β (IL-1β) secretion from mouse peritoneal macrophages primed with LPS, although it caused pro-IL-1β release similar to that of ATP. Consistent with this, activated caspase-1 responsible for pro-IL-1β maturation was undetectable in gossypol-treated peritoneal macrophages. Besides, RAW 264.7 cells lacking ASC expression and caspase-1 activation also underwent pyroptotic cell death upon gossypol treatment. In further support of pyroptosis induction, both pan-caspase inhibitor and caspase-1 subfamily inhibitor, but not caspase-3 inhibitor, could sharply suppress gossypol-induced cell death. Other canonical pyroptotic inhibitors, including potassium chloride and N-acetyl-L-cysteine, could suppress ATP-induced pyroptosis but failed to inhibit or even enhanced gossypol-induced cell death, whereas nonspecific pore-formation inhibitor glycine could attenuate this process, suggesting involvement of a non-canonical pathway. Of note, gossypol treatment eliminated thioglycollate-induced macrophages in the peritoneal cavity with recruitment of other leukocytes. Moreover, gossypol administration markedly decreased the survival of mice in a bacterial sepsis model. Collectively, these results suggested that gossypol induced pyroptosis in mouse macrophages via a non-canonical inflammasome pathway, which raises a concern for its in vivo cytotoxicity to macrophages. - Highlights: • Gossypol induces pyroptosis in mouse peritoneal and RAW 264.7 macrophages. • In LPS

Gossypol induces pyroptosis in mouse macrophages via a non-canonical inflammasome pathway

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Lin, Qiu-Ru; Li, Chen-Guang [Department of Immunobiology, College of Life Science and Technology, Jinan University, Guangzhou 510632 (China); Zha, Qing-Bing [Department of Fetal Medicine, The First Affiliated Hospital of Jinan University, Guangzhou 510632 (China); Xu, Li-Hui [Department of Cell Biology, College of Life Science and Technology, Jinan University, Guangzhou 510632 (China); Pan, Hao; Zhao, Gao-Xiang [Department of Immunobiology, College of Life Science and Technology, Jinan University, Guangzhou 510632 (China); Ouyang, Dong-Yun, E-mail: dongyun1967@aliyun.com [Department of Immunobiology, College of Life Science and Technology, Jinan University, Guangzhou 510632 (China); He, Xian-Hui, E-mail: thexh@jnu.edu.cn [Department of Immunobiology, College of Life Science and Technology, Jinan University, Guangzhou 510632 (China)

2016-02-01

Gossypol, a polyphenolic compound isolated from cottonseeds, has been reported to possess many pharmacological activities, but whether it can influence inflammasome activation remains unclear. In this study, we found that in mouse macrophages, gossypol induced cell death characterized by rapid membrane rupture and robust release of HMGB1 and pro-caspase-11 comparable to ATP treatment, suggesting an induction of pyroptotic cell death. Unlike ATP, gossypol induced much low levels of mature interleukin-1β (IL-1β) secretion from mouse peritoneal macrophages primed with LPS, although it caused pro-IL-1β release similar to that of ATP. Consistent with this, activated caspase-1 responsible for pro-IL-1β maturation was undetectable in gossypol-treated peritoneal macrophages. Besides, RAW 264.7 cells lacking ASC expression and caspase-1 activation also underwent pyroptotic cell death upon gossypol treatment. In further support of pyroptosis induction, both pan-caspase inhibitor and caspase-1 subfamily inhibitor, but not caspase-3 inhibitor, could sharply suppress gossypol-induced cell death. Other canonical pyroptotic inhibitors, including potassium chloride and N-acetyl-L-cysteine, could suppress ATP-induced pyroptosis but failed to inhibit or even enhanced gossypol-induced cell death, whereas nonspecific pore-formation inhibitor glycine could attenuate this process, suggesting involvement of a non-canonical pathway. Of note, gossypol treatment eliminated thioglycollate-induced macrophages in the peritoneal cavity with recruitment of other leukocytes. Moreover, gossypol administration markedly decreased the survival of mice in a bacterial sepsis model. Collectively, these results suggested that gossypol induced pyroptosis in mouse macrophages via a non-canonical inflammasome pathway, which raises a concern for its in vivo cytotoxicity to macrophages. - Highlights: • Gossypol induces pyroptosis in mouse peritoneal and RAW 264.7 macrophages. • In LPS

Molecular structure of human KATP in complex with ATP and ADP.

Science.gov (United States)

Lee, Kenneth Pak Kin; Chen, Jue; MacKinnon, Roderick

2017-12-29

In many excitable cells, KATP channels respond to intracellular adenosine nucleotides: ATP inhibits while ADP activates. We present two structures of the human pancreatic KATP channel, containing the ABC transporter SUR1 and the inward-rectifier K + channel Kir6.2, in the presence of Mg 2+ and nucleotides. These structures, referred to as quatrefoil and propeller forms, were determined by single-particle cryo-EM at 3.9 Å and 5.6 Å, respectively. In both forms, ATP occupies the inhibitory site in Kir6.2. The nucleotide-binding domains of SUR1 are dimerized with Mg 2+ -ATP in the degenerate site and Mg 2+ -ADP in the consensus site. A lasso extension forms an interface between SUR1 and Kir6.2 adjacent to the ATP site in the propeller form and is disrupted in the quatrefoil form. These structures support the role of SUR1 as an ADP sensor and highlight the lasso extension as a key regulatory element in ADP's ability to override ATP inhibition. © 2017, Lee et al.

Visualization and measurement of ATP levels in living cells replicating hepatitis C virus genome RNA.

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Tomomi Ando

Full Text Available Adenosine 5'-triphosphate (ATP is the primary energy currency of all living organisms and participates in a variety of cellular processes. Although ATP requirements during viral lifecycles have been examined in a number of studies, a method by which ATP production can be monitored in real-time, and by which ATP can be quantified in individual cells and subcellular compartments, is lacking, thereby hindering studies aimed at elucidating the precise mechanisms by which viral replication energized by ATP is controlled. In this study, we investigated the fluctuation and distribution of ATP in cells during RNA replication of the hepatitis C virus (HCV, a member of the Flaviviridae family. We demonstrated that cells involved in viral RNA replication actively consumed ATP, thereby reducing cytoplasmic ATP levels. Subsequently, a method to measure ATP levels at putative subcellular sites of HCV RNA replication in living cells was developed by introducing a recently-established Förster resonance energy transfer (FRET-based ATP indicator, called ATeam, into the NS5A coding region of the HCV replicon. Using this method, we were able to observe the formation of ATP-enriched dot-like structures, which co-localize with non-structural viral proteins, within the cytoplasm of HCV-replicating cells but not in non-replicating cells. The obtained FRET signals allowed us to estimate ATP concentrations within HCV replicating cells as ∼5 mM at possible replicating sites and ∼1 mM at peripheral sites that did not appear to be involved in HCV replication. In contrast, cytoplasmic ATP levels in non-replicating Huh-7 cells were estimated as ∼2 mM. To our knowledge, this is the first study to demonstrate changes in ATP concentration within cells during replication of the HCV genome and increased ATP levels at distinct sites within replicating cells. ATeam may be a powerful tool for the study of energy metabolism during replication of the viral genome.

Gravity loading induces adenosine triphosphate release and phosphorylation of extracellular signal-regulated kinases in human periodontal ligament cells.

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Ito, Mai; Arakawa, Toshiya; Okayama, Miki; Shitara, Akiko; Mizoguchi, Itaru; Takuma, Taishin

2014-11-01

The periodontal ligament (PDL) receives mechanical stress (MS) from dental occlusion or orthodontic tooth movement. Mechanical stress is thought to be a trigger for remodeling of the PDL and alveolar bone, although its signaling mechanism is still unclear. So we investigated the effect of MS on adenosine triphosphate (ATP) release and extracellular signal-regulated kinases (ERK) phosphorylation in PDL cells. Mechanical stress was applied to human PDL cells as centrifugation-mediated gravity loading. Apyrase, Ca(2+)-free medium and purinergic receptor agonists and antagonists were utilized to analyze the contribution of purinergic receptors to ERK phosphorylation. Gravity loading and ATP increased ERK phosphorylation by 5 and 2.5 times, respectively. Gravity loading induced ATP release from PDL cells by tenfold. Apyrase and suramin diminished ERK phosphorylation induced by both gravity loading and ATP. Under Ca(2+)-free conditions the phosphorylation by gravity loading was partially decreased, whereas ATP-induced phosphorylation was unaffected. Receptors P2Y4 and P2Y6 were prominently expressed in the PDL cells. Gravity loading induced ATP release and ERK phosphorylation in PDL fibroblasts, and ATP signaling via P2Y receptors was partially involved in this phosphorylation, which in turn would enhance gene expression for the remodeling of PDL tissue during orthodontic tooth movement. © 2013 Wiley Publishing Asia Pty Ltd.

Changes in dermal interstitial ATP levels during local heating of human skin.

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Gifford, Jayson R; Heal, Cory; Bridges, Jarom; Goldthorpe, Scott; Mack, Gary W

2012-12-15

Heating skin is believed to activate vanilloid type III and IV transient receptor potential ion channels (TRPV3, TRPV4, respectively), resulting in the release of ATP into the interstitial fluid. We examined the hypothesis that local skin heating would result in an accumulation of ATP in the interstitial fluid that would be related with a rise in skin blood flow (SkBF) and temperature sensation. Two microdialysis probes were inserted into the dermis on the dorsal aspect of the forearm in 15 young, healthy subjects. The probed skin was maintained at 31°C, 35°C, 39°C and 43°C for 8 min periods, during which SkBF was monitored as cutaneous vascular conductance (CVC). Dialysate was collected and analysed for ATP ([ATP](d)) using a luciferase-based assay, and ratings of perceived warmth were taken at each temperature. At a skin temperature of 31°C, [ATP](d) averaged 18.93 ± 4.06 nm and CVC averaged 12.57 ± 1.59% peak. Heating skin to 35°C resulted in an increase in CVC (17.63 ± 1.27% peak; P ATP](d). Heating skin to 39°C and 43°C resulted in a decreased [ATP](d) (5.88 ± 1.68 nm and 8.75 ± 3.44 nm, respectively; P ATP does not occur during local heating, and therefore does not have a role in temperature sensation or the dilator response in human skin. Nevertheless, the low threshold of dilatation (35°C) indicates a possible role for the TRPV3, TRPV4 channels or the sensitization of other ion channels in mediating the dilator response.

ATP-loading 201Tl myocardial SPECT for the detection of ischemic heart disease

International Nuclear Information System (INIS)

Fujinaga, Tsuyoshi; Yamazaki, Sayaka; Hara, Masatada; Umezawa, Chiaki; Okamura, Tetsuo; Murata, Hajime; Maruno, Hirotaka; Onoguchi, Masahisa.

1993-01-01

To evaluate the usefulness for the detection of ischemic heart disease, ATP myocrdial SPECT was performed in 35 patients (mean; 59±9.4 years) with angina pectoris or old myocardial infarction. Coronary angiography (CAG) was performed in all patients. The ultra-short half-life of ATP required a continuous infusion for its use. ATP was infused intravenously at a rate of 0.16 mg/kg/min for 5 min, with 201 Tl injection taking place at 3 min. Myocardial SPECT imaging was begun 5 min and 4 hr later after the end of ATP infusion. ATP caused a significant decrease in arterial blood pressure (p 201 Tl myocardial SPECT for the detection of coronary artery disease (CAD) was evaluated using CAG as a golden standard. The sensitivity and specificity for CAD detection were 82% and 90%, respectively. ATP myocardial SPECT is a promising new test for the detection of ischemic heart disease. (author)

Optimization of ATP synthase function in mitochondria and chloroplasts via the adenylate kinase equilibrium

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Abir U Igamberdiev

2015-01-01

Full Text Available The bulk of ATP synthesis in plants is performed by ATP synthase, the main bioenergetics engine of cells, operating both in mitochondria and in chloroplasts. The reaction mechanism of ATP synthase has been studied in detail for over half a century; however, its optimal performance depends also on the steady delivery of ATP synthase substrates and the removal of its products. For mitochondrial ATP synthase, we analyze here the provision of stable conditions for (i the supply of ADP and Mg2+, supported by adenylate kinase (AK equilibrium in the intermembrane space, (ii the supply of phosphate via membrane transporter in symport with H+, and (iii the conditions of outflow of ATP by adenylate transporter carrying out the exchange of free adenylates. We also show that, in chloroplasts, AK equilibrates adenylates and governs Mg2+ contents in the stroma, optimizing ATP synthase and Calvin cycle operation, and affecting the import of inorganic phosphate in exchange with triose phosphates. It is argued that chemiosmosis is not the sole component of ATP synthase performance, which also depends on AK-mediated equilibrium of adenylates and Mg2+, adenylate transport and phosphate release and supply.

Hypotonic stress promotes ATP release, reactive oxygen species production and cell proliferation via TRPV4 activation in rheumatoid arthritis rat synovial fibroblasts

International Nuclear Information System (INIS)

Hu, Fen; Hui, Zhenhai; Wei, Wei; Yang, Jianyu; Chen, Ziyuan; Guo, Bu; Xing, Fulin; Zhang, Xinzheng; Pan, Leiting; Xu, Jingjun

2017-01-01

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune-disease with complex and unclear etiology. Hypotonicity of synovial fluid is a typical characteristic of RA, which may play pivotal roles in RA pathogenesis. In this work, we studied the responses of RA synovial fibroblasts to hypotonic stress in vitro and further explored the underlying mechanisms. Data showed that hyposmotic solutions significantly triggered increases in cytosolic calcium concentration ([Ca 2+ ] c ) of synoviocytes. Subsequently, it caused rapid release of ATP, as well as remarkable production of intracellular reactive oxygen species (ROS). Meanwhile, hypotonic stimulus promoted the proliferation of synovial fibroblasts. These effects were almost abolished by calcium-free buffer and significantly inhibited by gadolinium (III) chloride (a mechanosensitive Ca 2+ channel blocker) and ruthenium red (a transient receptor potential vanilloid 4 (TRPV4) blocker). 4α-phorbol 12,13-didecanoate, a specific agonist of TRPV4, also mimicked hypotonic shock-induced responses shown above. In contrast, voltage-gated channel inhibitors verapamil and nifedipine had little influences on these responses. Furthermore, RT-PCR and western blotting evidently detected TRPV4 expression at mRNA and protein level in isolated synoviocytes. Taken together, our results indicated that hypotonic stimulus resulted in ATP release, ROS production, and cell proliferation depending on Ca 2+ entry through activation of TRPV4 channel in synoviocytes. - Highlights: • Hypotonic stress evokes Ca 2+ entry in rheumatoid arthritis synovial fibroblasts. • Hypotonic stress induces rapid ATP release and ROS production in synoviocytes. • Hypotonic stimulation promotes the proliferation of synovial fibroblasts. • TRPV4 controls hypotonic-induced responses in synoviocytes.

Stimulation of acetoin production in metabolically engineered Lactococcus lactis by increasing ATP demand

DEFF Research Database (Denmark)

Liu, Jianming; Kandasamy, Vijayalakshmi; Würtz, Anders

2016-01-01

Having a sufficient supply of energy, usually in the form of ATP, is essential for all living organisms. In this study, however, we demonstrate that it can be beneficial to reduce ATP availability when the objective is microbial production. By introducing the ATP hydrolyzing F1-ATPase into a Lact...

Novel phosphate-activated macrophages prevent ectopic calcification by increasing extracellular ATP and pyrophosphate

Science.gov (United States)

Villa-Bellosta, Ricardo; Hamczyk, Magda R.; Andrés, Vicente

2017-01-01

Purpose Phosphorus is an essential nutrient involved in many pathobiological processes. Less than 1% of phosphorus is found in extracellular fluids as inorganic phosphate ion (Pi) in solution. High serum Pi level promotes ectopic calcification in many tissues, including blood vessels. Here, we studied the effect of elevated Pi concentration on macrophage polarization and calcification. Macrophages, present in virtually all tissues, play key roles in health and disease and display remarkable plasticity, being able to change their physiology in response to environmental cues. Methods and results High-throughput transcriptomic analysis and functional studies demonstrated that Pi induces unpolarized macrophages to adopt a phenotype closely resembling that of alternatively-activated M2 macrophages, as revealed by arginine hydrolysis and energetic and antioxidant profiles. Pi-induced macrophages showed an anti-calcifying action mediated by increased availability of extracellular ATP and pyrophosphate. Conclusion We conclude that the ability of Pi-activated macrophages to prevent calcium-phosphate deposition is a compensatory mechanism protecting tissues from hyperphosphatemia-induced pathologic calcification. PMID:28362852

Effect of Intramuscular Protons, Lactate, and ATP on Muscle Hyperalgesia in Rats.

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Nicholas S Gregory

Full Text Available Chronic muscle pain is a significant health problem leading to disability[1]. Muscle fatigue can exacerbate muscle pain. Metabolites, including ATP, lactate, and protons, are released during fatiguing exercise and produce pain in humans. These substances directly activate purinergic (P2X and acid sensing ion channels (ASICs on muscle nociceptors, and when combined, produce a greater increase in neuron firing than when given alone. Whether the enhanced effect of combining protons, lactate, and ATP is the sum of individual effects (additive or more than the sum of individual effects (synergistic is unknown. Using a rat model of muscle nociceptive behavior, we tested each of these compounds individually over a range of physiologic and supra-physiologic concentrations. Further, we combined all three compounds in a series of dilutions and tested their effect on muscle nociceptive behavior. We also tested a non-hydrolyzable form of ATP (α,β-meATP alone and in combination with lactate and acidic pH. Surprisingly, we found no dose-dependent effect on muscle nociceptive behavior for protons, lactate, or ATP when given alone. We similarly found no effect after application of each two-metabolite combination. Only pH 4 saline and α,β-meATP produced hyperalgesia when given alone. When all 3 substances were combined, however, ATP (2.4μm, lactate (10mM, and acidic pH (pH 6.0 produced an enhanced effect greater than the sum of the effects of the individual components, i.e. synergism. α,β me ATP (3nmol, on the other hand, showed no enhanced effects when combined with lactate (10mM or acidic pH (pH 6.0, i.e. additive. These data suggest that combining fatigue metabolites in muscle produces a synergistic effect on muscle nociception.

Wilson Disease Protein ATP7B Utilizes Lysosomal Exocytosis to Maintain Copper Homeostasis

NARCIS (Netherlands)

Polishchuk, Elena V.; Concilli, Mafalda; Iacobacci, Simona; Chesi, Giancarlo; Pastore, Nunzia; Piccolo, Pasquale; Paladino, Simona; Baldantoni, Daniela; van IJzendoorn, Sven C. D.; Chan, Jefferson; Chang, Christopher J.; Amoresano, Angela; Pane, Francesca; Pucci, Piero; Tarallo, Antonietta; Parenti, Giancarlo; Brunetti-Pierri, Nicola; Settembre, Carmine; Ballabio, Andrea; Polishchuk, Roman S.

2014-01-01

Copper is an essential yet toxic metal and its overload causes Wilson disease, a disorder due to mutations in copper transporter ATP7B. To remove excess copper into the bile, ATP7B traffics toward canalicular area of hepatocytes. However, the trafficking mechanisms of ATP7B remain elusive. Here, we

Use of luciferase probes to measure ATP in living cells and animals.

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Morciano, Giampaolo; Sarti, Alba Clara; Marchi, Saverio; Missiroli, Sonia; Falzoni, Simonetta; Raffaghello, Lizzia; Pistoia, Vito; Giorgi, Carlotta; Di Virgilio, Francesco; Pinton, Paolo

2017-08-01

ATP, the energy exchange factor that connects anabolism and catabolism, is required for major reactions and processes that occur in living cells, such as muscle contraction, phosphorylation and active transport. ATP is also the key molecule in extracellular purinergic signaling mechanisms, with an established crucial role in inflammation and several additional disease conditions. Here, we describe detailed protocols to measure the ATP concentration in isolated living cells and animals using luminescence techniques based on targeted luciferase probes. In the presence of magnesium, oxygen and ATP, the protein luciferase catalyzes oxidation of the substrate luciferin, which is associated with light emission. Recombinantly expressed wild-type luciferase is exclusively cytosolic; however, adding specific targeting sequences can modify its cellular localization. Using this strategy, we have constructed luciferase chimeras targeted to the mitochondrial matrix and the outer surface of the plasma membrane. Here, we describe optimized protocols for monitoring ATP concentrations in the cytosol, mitochondrial matrix and pericellular space in living cells via an overall procedure that requires an average of 3 d. In addition, we present a detailed protocol for the in vivo detection of extracellular ATP in mice using luciferase-transfected reporter cells. This latter procedure may require up to 25 d to complete.

Label free luminescence strategy for sensitive detection of ATP using aptamer-Ru(II) complexes

Energy Technology Data Exchange (ETDEWEB)

Babu, Eththilu [Department of Physical Che mistry, School of Chemistry, Madurai Kamaraj University, Madurai 625021, Tamil Nadu (India); Muthu Mareeswaran, Paulpandian [Department of Physical Che mistry, School of Chemistry, Madurai Kamaraj University, Madurai 625021, Tamil Nadu (India); Department of Industrial Chemistry, Alagappa Univesity, Karaikudi 630003, Tamil Nadu (India); Ramdass, Arumugam [Department of Physical Che mistry, School of Chemistry, Madurai Kamaraj University, Madurai 625021, Tamil Nadu (India); Research Department of Chemistry, Aditanar College of Arts and Science, Tiruchendur 628216, Tamil Nadu (India); Ramesh, Pandian [UCIBIO-REQUIMTE, Departmento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica (Portugal); Rajagopal, Seenivasan, E-mail: rajagopalseenivasan@yahoo.com [Department of Physical Che mistry, School of Chemistry, Madurai Kamaraj University, Madurai 625021, Tamil Nadu (India)

2016-07-15

A simple and sensitive aptamer-based luminescence strategy for ATP detection is developed using Ru(II) complexes as probe molecule. It is based on the fact that Ru(II)-dppz complexes show the light switching behavior with DNA aptamers and found to show significant luminescence spectral change on the addition of ATP molecules. The binding efficiencies of aptamer with ATP, ADP and AMP are calculated and compared. The structural change of aptamer is also studied using circular dichroism (CD) spectral techniques. Moreover, the binding nature of aptamer with ATP, ADP and AMP is demonstrated by computational techniques. The proposed strategy was successfully applied to the detection of ATP.

Label free luminescence strategy for sensitive detection of ATP using aptamer-Ru(II) complexes

International Nuclear Information System (INIS)

Babu, Eththilu; Muthu Mareeswaran, Paulpandian; Ramdass, Arumugam; Ramesh, Pandian; Rajagopal, Seenivasan

2016-01-01

A simple and sensitive aptamer-based luminescence strategy for ATP detection is developed using Ru(II) complexes as probe molecule. It is based on the fact that Ru(II)-dppz complexes show the light switching behavior with DNA aptamers and found to show significant luminescence spectral change on the addition of ATP molecules. The binding efficiencies of aptamer with ATP, ADP and AMP are calculated and compared. The structural change of aptamer is also studied using circular dichroism (CD) spectral techniques. Moreover, the binding nature of aptamer with ATP, ADP and AMP is demonstrated by computational techniques. The proposed strategy was successfully applied to the detection of ATP.

Glycolysis-related gene induction and ATP reduction during fractionated irradiation. Markers for radiation responsiveness of human tumor xenografts

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Goetze, K.; Meyer, S.S.; Mueller-Klieser, W. [University Medical Center Mainz Univ. (Germany). Inst. of Physiology and Pathophysiology; Yaromina, A. [Technical Univ. Dresden (Germany). OncoRay - National Center for Radiation Research in Oncology; Zips, D. [University Hospital Tuebingen (Germany). Dept. of Radiation Oncology; Baumann, M. [Technical Univ. Dresden (Germany). OncoRay - National Center for Radiation Research in Oncology; University Hospital Dresden Technical Univ. Dresden (Germany). Dept. of Radiation Oncology

2013-09-15

Background and purpose: Lactate was previously shown to be a prognostic but not a predictive pre-therapeutic marker for radiation response of tumor xenografts. We hypothesize that metabolic changes during fractionated irradiation may restrict the predictiveness of lactate regarding tumor radiosensitivity. Materials and methods: Tumor xenografts were generated in nude mice by implanting 4 head and neck squamous cell carcinoma lines with different sensitivities to fractionated irradiation. Tumors were irradiated with up to 15 fractions of 2 Gy over a period of 3 weeks, and ATP and lactate levels were measured in vital tumor areas with induced metabolic bioluminescence imaging. Corresponding changes in mRNA expression of glycolysis-related genes were determined by quantitative RT-PCR. Results: Lactate content decreased significantly in 3 out of 4 cell lines in the course of irradiation showing no correlation with cell line-specific radiosensitivity. Radiation-induced changes in ATP levels and glycolysis-related mRNA expression, however, only occurred in radiosensitive or intermediately radioresistant xenografts, whereas these parameters remained unchanged in radioresistant tumors. Conclusion: Sensitivity-related differences in the transcriptional response of tumors to radiotherapy may be exploited in the clinic for better individualization of tumor treatment. (orig.)

PKA activity exacerbates hypoxia-induced ROS formation and hypoxic injury in PC-12 cells.

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Gozal, Evelyne; Metz, Cynthia J; Dematteis, Maurice; Sachleben, Leroy R; Schurr, Avital; Rane, Madhavi J

2017-09-05

Hypoxia is a primary factor in many pathological conditions. Hypoxic cell death is commonly attributed to metabolic failure and oxidative injury. cAMP-dependent protein kinase A (PKA) is activated in hypoxia and regulates multiple enzymes of the mitochondrial electron transport chain, thus may be implicated in cellular energy depletion and hypoxia-induced cell death. Wild type (WT) PC-12 cells and PKA activity-deficient 123.7 PC-12 cells were exposed to 3, 6, 12 and 24h hypoxia (0.1% or 5% O 2 ). Hypoxia, at 24h 0.1% O 2 , induced cell death and increased reactive oxygen species (ROS) in WT PC-12 cells. Despite lower ATP levels in normoxic 123.7 cells than in WT cells, hypoxia only decreased ATP levels in WT cells. However, menadione-induced oxidative stress similarly affected both cell types. While mitochondrial COX IV expression remained consistently higher in 123.7 cells, hypoxia decreased COX IV expression in both cell types. N-acetyl cysteine antioxidant treatment blocked hypoxia-induced WT cell death without preventing ATP depletion. Transient PKA catα expression in 123.7 cells partially restored hypoxia-induced ROS but did not alter ATP levels or COX IV expression. We conclude that PKA signaling contributes to hypoxic injury, by regulating oxidative stress rather than by depleting ATP levels. Therapeutic strategies targeting PKA signaling may improve cellular adaptation and recovery in hypoxic pathologies. Copyright © 2017 Elsevier B.V. All rights reserved.

De novo mutations in ATP1A3 cause alternating hemiplegia of childhood

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Heinzen, Erin L.; Swoboda, Kathryn J.; Hitomi, Yuki; Gurrieri, Fiorella; Nicole, Sophie; de Vries, Boukje; Tiziano, F. Danilo; Fontaine, Bertrand; Walley, Nicole M.; Heavin, Sinéad; Panagiotakaki, Eleni; Fiori, Stefania; Abiusi, Emanuela; Di Pietro, Lorena; Sweney, Matthew T.; Newcomb, Tara M.; Viollet, Louis; Huff, Chad; Jorde, Lynn B.; Reyna, Sandra P.; Murphy, Kelley J.; Shianna, Kevin V.; Gumbs, Curtis E.; Little, Latasha; Silver, Kenneth; Ptác̆ek, Louis J.; Haan, Joost; Ferrari, Michel D.; Bye, Ann M.; Herkes, Geoffrey K.; Whitelaw, Charlotte M.; Webb, David; Lynch, Bryan J.; Uldall, Peter; King, Mary D.; Scheffer, Ingrid E.; Neri, Giovanni; Arzimanoglou, Alexis; van den Maagdenberg, Arn M.J.M.; Sisodiya, Sanjay M.; Mikati, Mohamad A.; Goldstein, David B.; Nicole, Sophie; Gurrieri, Fiorella; Neri, Giovanni; de Vries, Boukje; Koelewijn, Stephany; Kamphorst, Jessica; Geilenkirchen, Marije; Pelzer, Nadine; Laan, Laura; Haan, Joost; Ferrari, Michel; van den Maagdenberg, Arn; Zucca, Claudio; Bassi, Maria Teresa; Franchini, Filippo; Vavassori, Rosaria; Giannotta, Melania; Gobbi, Giuseppe; Granata, Tiziana; Nardocci, Nardo; De Grandis, Elisa; Veneselli, Edvige; Stagnaro, Michela; Gurrieri, Fiorella; Neri, Giovanni; Vigevano, Federico; Panagiotakaki, Eleni; Oechsler, Claudia; Arzimanoglou, Alexis; Nicole, Sophie; Giannotta, Melania; Gobbi, Giuseppe; Ninan, Miriam; Neville, Brian; Ebinger, Friedrich; Fons, Carmen; Campistol, Jaume; Kemlink, David; Nevsimalova, Sona; Laan, Laura; Peeters-Scholte, Cacha; van den Maagdenberg, Arn; Casaer, Paul; Casari, Giorgio; Sange, Guenter; Spiel, Georg; Boneschi, Filippo Martinelli; Zucca, Claudio; Bassi, Maria Teresa; Schyns, Tsveta; Crawley, Francis; Poncelin, Dominique; Vavassori, Rosaria

2012-01-01

Alternating hemiplegia of childhood (AHC) is a rare, severe neurodevelopmental syndrome characterized by recurrent hemiplegic episodes and distinct neurologic manifestations. AHC is usually a sporadic disorder with unknown etiology. Using exome sequencing of seven patients with AHC, and their unaffected parents, we identified de novo nonsynonymous mutations in ATP1A3 in all seven AHC patients. Subsequent sequence analysis of ATP1A3 in 98 additional patients revealed that 78% of AHC cases have a likely causal ATP1A3 mutation, including one inherited mutation in a familial case of AHC. Remarkably, six ATP1A3 mutations explain the majority of patients, including one observed in 36 patients. Unlike ATP1A3 mutations that cause rapid-onset-dystonia-parkinsonism, AHC-causing mutations revealed consistent reductions in ATPase activity without effects on protein expression. This work identifies de novo ATP1A3 mutations as the primary cause of AHC, and offers insight into disease pathophysiology by expanding the spectrum of phenotypes associated with mutations in this gene. PMID:22842232

Ca2+-regulated-cAMP/PKA signaling in cardiac pacemaker cells links ATP supply to demand.

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Yaniv, Yael; Juhaszova, Magdalena; Lyashkov, Alexey E; Spurgeon, Harold A; Sollott, Steven J; Lakatta, Edward G

2011-11-01

In sinoatrial node cells (SANC), Ca(2+) activates adenylate cyclase (AC) to generate a high basal level of cAMP-mediated/protein kinase A (PKA)-dependent phosphorylation of Ca(2+) cycling proteins. These result in spontaneous sarcoplasmic-reticulum (SR) generated rhythmic Ca(2+) oscillations during diastolic depolarization, that not only trigger the surface membrane to generate rhythmic action potentials (APs), but, in a feed-forward manner, also activate AC/PKA signaling. ATP is consumed to pump Ca(2+) to the SR, to produce cAMP, to support contraction and to maintain cell ionic homeostasis. Since feedback mechanisms link ATP-demand to ATP production, we hypothesized that (1) both basal ATP supply and demand in SANC would be Ca(2+)-cAMP/PKA dependent; and (2) due to its feed-forward nature, a decrease in flux through the Ca(2+)-cAMP/PKA signaling axis will reduce the basal ATP production rate. O(2) consumption in spontaneous beating SANC was comparable to ventricular myocytes (VM) stimulated at 3 Hz. Graded reduction of basal Ca(2+)-cAMP/PKA signaling to reduce ATP demand in rabbit SANC produced graded ATP depletion (r(2)=0.96), and reduced O(2) consumption and flavoprotein fluorescence. Neither inhibition of glycolysis, selectively blocking contraction nor specific inhibition of mitochondrial Ca(2+) flux reduced the ATP level. Feed-forward basal Ca(2+)-cAMP/PKA signaling both consumes ATP to drive spontaneous APs in SANC and is tightly linked to mitochondrial ATP production. Interfering with Ca(2+)-cAMP/PKA signaling not only slows the firing rate and reduces ATP consumption, but also appears to reduce ATP production so that ATP levels fall. This distinctly differs from VM, which lack this feed-forward basal cAMP/PKA signaling, and in which ATP level remains constant when the demand changes. Published by Elsevier Ltd.

Evaluation of ATP measurements to detect microbial ingress by wastewater and surface water in drinking water.

Science.gov (United States)

Vang, Óluva K; Corfitzen, Charlotte B; Smith, Christian; Albrechtsen, Hans-Jørgen

2014-11-01

Fast and reliable methods are required for monitoring of microbial drinking water quality in order to protect public health. Adenosine triphosphate (ATP) was investigated as a potential real-time parameter for detecting microbial ingress in drinking water contaminated with wastewater or surface water. To investigate the ability of the ATP assay in detecting different contamination types, the contaminant was diluted with non-chlorinated drinking water. Wastewater, diluted at 10(4) in drinking water, was detected with the ATP assay, as well as 10(2) to 10(3) times diluted surface water. To improve the performance of the ATP assay in detecting microbial ingress in drinking water, different approaches were investigated, i.e. quantifying microbial ATP or applying reagents of different sensitivities to reduce measurement variations; however, none of these approaches contributed significantly in this respect. Compared to traditional microbiological methods, the ATP assay could detect wastewater and surface water in drinking water to a higher degree than total direct counts (TDCs), while both heterotrophic plate counts (HPC 22 °C and HPC 37 °C) and Colilert-18 (Escherichia coli and coliforms) were more sensitive than the ATP measurements, though with much longer response times. Continuous sampling combined with ATP measurements displays definite monitoring potential for microbial drinking water quality, since microbial ingress in drinking water can be detected in real-time with ATP measurements. The ability of the ATP assay to detect microbial ingress is influenced by both the ATP load from the contaminant itself and the ATP concentration in the specific drinking water. Consequently, a low ATP concentration of the specific drinking water facilitates a better detection of a potential contamination of the water supply with the ATP assay. Copyright © 2014 Elsevier Ltd. All rights reserved.

Persistence of the mitochondrial permeability transition in the absence of subunit c of human ATP synthase.

Science.gov (United States)

He, Jiuya; Ford, Holly C; Carroll, Joe; Ding, Shujing; Fearnley, Ian M; Walker, John E

2017-03-28

The permeability transition in human mitochondria refers to the opening of a nonspecific channel, known as the permeability transition pore (PTP), in the inner membrane. Opening can be triggered by calcium ions, leading to swelling of the organelle, disruption of the inner membrane, and ATP synthesis, followed by cell death. Recent proposals suggest that the pore is associated with the ATP synthase complex and specifically with the ring of c-subunits that constitute the membrane domain of the enzyme's rotor. The c-subunit is produced from three nuclear genes, ATP5G1 , ATP5G2 , and ATP5G3 , encoding identical copies of the mature protein with different mitochondrial-targeting sequences that are removed during their import into the organelle. To investigate the involvement of the c-subunit in the PTP, we generated a clonal cell, HAP1-A12, from near-haploid human cells, in which ATP5G1 , ATP5G2 , and ATP5G3 were disrupted. The HAP1-A12 cells are incapable of producing the c-subunit, but they preserve the characteristic properties of the PTP. Therefore, the c-subunit does not provide the PTP. The mitochondria in HAP1-A12 cells assemble a vestigial ATP synthase, with intact F 1 -catalytic and peripheral stalk domains and the supernumerary subunits e, f, and g, but lacking membrane subunits ATP6 and ATP8. The same vestigial complex plus associated c-subunits was characterized from human 143B ρ 0 cells, which cannot make the subunits ATP6 and ATP8, but retain the PTP. Therefore, none of the membrane subunits of the ATP synthase that are involved directly in transmembrane proton translocation is involved in forming the PTP.

Nisin depletes ATP and proton motive force in mycobacteria.

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Chung, H J; Montville, T J; Chikindas, M L

2000-12-01

This study examined the inhibitory effect of nisin and its mode of action against Mycobacterium smegmatis, a non-pathogenic species of mycobacteria, and M. bovis-Bacill Carmette Guerin (BCG), a vaccine strain of pathogenic M. bovis. In agar diffusion assays, 2.5 mg ml(-1) nisin was required to inhibit M. bovis-BCG. Nisin caused a slow, gradual, time- and concentration-dependent decrease in internal ATP levels in M. bovis-BCG, but no ATP efflux was detected. In mycobacteria, nisin decreased both components of proton motive force (membrane potential, Delta Psi and Delta pH) in a time- and concentration-dependent manner. However, mycobacteria maintained their intracellular ATP levels during the initial time period of Delta Psi and Delta pH dissipation. These data suggest that the mechanism of nisin in mycobacteria is similar to that in food-borne pathogens.

Mitochondria and lipid raft-located FOF1-ATP synthase as major therapeutic targets in the antileishmanial and anticancer activities of ether lipid edelfosine.

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Janny A Villa-Pulgarín

2017-08-01

Full Text Available Leishmaniasis is the world's second deadliest parasitic disease after malaria, and current treatment of the different forms of this disease is far from satisfactory. Alkylphospholipid analogs (APLs are a family of anticancer drugs that show antileishmanial activity, including the first oral drug (miltefosine for leishmaniasis and drugs in preclinical/clinical oncology trials, but their precise mechanism of action remains to be elucidated.Here we show that the tumor cell apoptosis-inducer edelfosine was the most effective APL, as compared to miltefosine, perifosine and erucylphosphocholine, in killing Leishmania spp. promastigotes and amastigotes as well as tumor cells, as assessed by DNA breakdown determined by flow cytometry. In studies using animal models, we found that orally-administered edelfosine showed a potent in vivo antileishmanial activity and diminished macrophage pro-inflammatory responses. Edelfosine was also able to kill Leishmania axenic amastigotes. Edelfosine was taken up by host macrophages and killed intracellular Leishmania amastigotes in infected macrophages. Edelfosine accumulated in tumor cell mitochondria and Leishmania kinetoplast-mitochondrion, and led to mitochondrial transmembrane potential disruption, and to the successive breakdown of parasite mitochondrial and nuclear DNA. Ectopic expression of Bcl-XL inhibited edelfosine-induced cell death in both Leishmania parasites and tumor cells. We found that the cytotoxic activity of edelfosine against Leishmania parasites and tumor cells was associated with a dramatic recruitment of FOF1-ATP synthase into lipid rafts following edelfosine treatment in both parasites and cancer cells. Raft disruption and specific FOF1-ATP synthase inhibition hindered edelfosine-induced cell death in both Leishmania parasites and tumor cells. Genetic deletion of FOF1-ATP synthase led to edelfosine drug resistance in Saccharomyces cerevisiae yeast.The present study shows that the

Adenosine triphosphate-guided pulmonary vein isolation for atrial fibrillation: the UNmasking Dormant Electrical Reconduction by Adenosine TriPhosphate (UNDER-ATP) trial.

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Kobori, Atsushi; Shizuta, Satoshi; Inoue, Koichi; Kaitani, Kazuaki; Morimoto, Takeshi; Nakazawa, Yuko; Ozawa, Tomoya; Kurotobi, Toshiya; Morishima, Itsuro; Miura, Fumiharu; Watanabe, Tetsuya; Masuda, Masaharu; Naito, Masaki; Fujimoto, Hajime; Nishida, Taku; Furukawa, Yoshio; Shirayama, Takeshi; Tanaka, Mariko; Okajima, Katsunori; Yao, Takenori; Egami, Yasuyuki; Satomi, Kazuhiro; Noda, Takashi; Miyamoto, Koji; Haruna, Tetsuya; Kawaji, Tetsuma; Yoshizawa, Takashi; Toyota, Toshiaki; Yahata, Mitsuhiko; Nakai, Kentaro; Sugiyama, Hiroaki; Higashi, Yukei; Ito, Makoto; Horie, Minoru; Kusano, Kengo F; Shimizu, Wataru; Kamakura, Shiro; Kimura, Takeshi

2015-12-07

Most of recurrent atrial tachyarrhythmias after pulmonary vein isolation (PVI) for atrial fibrillation (AF) are due to reconnection of PVs. The aim of the present study was to evaluate whether elimination of adenosine triphosphate (ATP)-induced dormant PV conduction by additional energy applications during the first ablation procedure could reduce the incidence of recurrent atrial tachyarrhythmias. We randomly assigned 2113 patients with paroxysmal, persistent, or long-lasting AF to either ATP-guided PVI (1112 patients) or conventional PVI (1001 patients). The primary endpoint was recurrent atrial tachyarrhythmias lasting for >30 s or those requiring repeat ablation, hospital admission, or usage of Vaughan Williams class I or III antiarrhythmic drugs at 1 year with the blanking period of 90 days post ablation. Among patients assigned to ATP-guided PVI, 0.4 mg/kg body weight of ATP provoked dormant PV conduction in 307 patients (27.6%). Additional radiofrequency energy applications successfully eliminated dormant conduction in 302 patients (98.4%). At 1 year, 68.7% of patients in the ATP-guided PVI group and 67.1% of patients in the conventional PVI group were free from the primary endpoint, with no significant difference (adjusted hazard ratio [HR] 0.89; 95% confidence interval [CI] 0.74-1.09; P = 0.25). The results were consistent across all the prespecified subgroups. Also, there was no significant difference in the 1-year event-free rates from repeat ablation for any atrial tachyarrhythmia between the groups (adjusted HR 0.83; 95% CI 0.65-1.08; P = 0.16). In the catheter ablation for AF, we found no significant reduction in the 1-year incidence of recurrent atrial tachyarrhythmias by ATP-guided PVI compared with conventional PVI. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Motility, ATP levels and metabolic enzyme activity of sperm from bluegill (Lepomis macrochirus).

Science.gov (United States)

Burness, Gary; Moyes, Christopher D; Montgomerie, Robert

2005-01-01

Male bluegill displays one of two life history tactics. Some males (termed "parentals") delay reproduction until ca. 7 years of age, at which time they build nests and actively courts females. Others mature precociously (sneakers) and obtain fertilizations by cuckolding parental males. In the current study, we studied the relations among sperm motility, ATP levels, and metabolic enzyme activity in parental and sneaker bluegill. In both reproductive tactics, sperm swimming speed and ATP levels declined in parallel over the first 60 s of motility. Although sneaker sperm initially had higher ATP levels than parental sperm, by approximately 30 s postactivation, no differences existed between tactics. No differences were noted between tactics in swimming speed, percent motility, or the activities of key metabolic enzymes, although sperm from parentals had a higher ratio of creatine phosphokinase (CPK) to citrate synthase (CS). In both tactics, with increasing CPK and CS activity, sperm ATP levels increased at 20 s postactivation, suggesting that capacities for phosphocreatine hydrolysis and aerobic metabolism may influence interindividual variation in rates of ATP depletion. Nonetheless, there was no relation between sperm ATP levels and either swimming speed or percent of sperm that were motile. This suggests that interindividual variation in ATP levels may not be the primary determinant of variation in sperm swimming performance in bluegill.

Mice Lacking Pannexin 1 Release ATP and Respond Normally to All Taste Qualities.

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Vandenbeuch, Aurelie; Anderson, Catherine B; Kinnamon, Sue C

2015-09-01

Adenosine triphosphate (ATP) is required for the transmission of all taste qualities from taste cells to afferent nerve fibers. ATP is released from Type II taste cells by a nonvesicular mechanism and activates purinergic receptors containing P2X2 and P2X3 on nerve fibers. Several ATP release channels are expressed in taste cells including CALHM1, Pannexin 1, Connexin 30, and Connexin 43, but whether all are involved in ATP release is not clear. We have used a global Pannexin 1 knock out (Panx1 KO) mouse in a series of in vitro and in vivo experiments. Our results confirm that Panx1 channels are absent in taste buds of the knockout mice and that other known ATP release channels are not upregulated. Using a luciferin/luciferase assay, we show that circumvallate taste buds from Panx1 KO mice normally release ATP upon taste stimulation compared with wild type (WT) mice. Gustatory nerve recordings in response to various tastants applied to the tongue and brief-access behavioral testing with SC45647 also show no difference between Panx1 KO and WT. These results confirm that Panx1 is not required for the taste evoked release of ATP or for neural and behavioral responses to taste stimuli. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Mesurements of intracellular ATP provide new insight into the regulation of glycolysis in the yeast Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Ytting, Cecilie Karkov; Fuglsang, Anja Thoe; Hiltunen, J. Kalervo

2012-01-01

Glycolysis in the yeast Saccharomyces cerevisiae exhibits temporal oscillation under anaerobic or semianaerobic conditions. Previous evidence indicated that at least two membrane-bound ATPases, the mitochondrial F0F1 ATPase and the plasma membrane P-type ATPase (Pma1p), were important in regulating...... of the temporal behaviour of intracellular ATP in a yeast strain with oscillating glycolysis showed that, in addition to oscillation in intracellular ATP, there is an overall slow decrease in intracellular ATP because the ATP consumption rate exceeds the ATP production in glycolysis. Measurements of the temporal...... activity is under strict control. In the absence of glucose ATPase activity is switched off, and the intracellular ATP concentration is high. When glucose is added to the cells the ATP concentration starts to decrease, because ATP consumption exceeds ATP production by glycolysis. Finally, when glucose...

The Contribution of Red Blood Cell Dynamics to Intrinsic Viscosity and Functional ATP Release

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Forsyth, Alison; Abkarian, Manouk; Wan, Jiandi; Stone, Howard

2010-11-01

In shear flow, red blood cells (RBCs) exhibit a variety of behaviors such as rouleaux formation, tumbling, swinging, and tank-treading. The physiological consequences of these dynamic behaviors are not understood. In vivo, ATP is known to signal vasodilation; however, to our knowledge, no one has deciphered the relevance of RBC microrheology to the functional release of ATP. Previously, we correlated RBC deformation and ATP release in microfluidic constrictions (Wan et al., 2008). In this work, a cone-plate rheometer is used to shear a low hematocrit solution of RBCs at varying viscosity ratios (λ) between the inner cytoplasmic hemoglobin and the outer medium, to determine the intrinsic viscosity of the suspension. Further, using a luciferin-luciferase enzymatic reaction, we report the relative ATP release at varying shear rates. Results indicate that for λ = 1.6, 3.8 and 11.1, ATP release is constant up to 500 s-1, which suggests that the tumbling-tanktreading transition does not alter ATP release in pure shear. For lower viscosity ratios, λ = 1.6 and 3.8, at 500 s-1 a change in slope occurs in the intrinsic viscosity data and is marked by an increase in ATP release. Based on microfluidic observations, this simultaneous change in viscosity and ATP release occurs within the tank-treading regime.

Mitochondria from rat uterine smooth muscle possess ATP-sensitive potassium channel

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Olga B. Vadzyuk

2018-03-01

Full Text Available The objective of this study was to detect ATP-sensitive K+ uptake in rat uterine smooth muscle mitochondria and to determine possible effects of its activation on mitochondrial physiology. By means of fluorescent technique with usage of K+-sensitive fluorescent probe PBFI (potassium-binding benzofuran isophthalate we showed that accumulation of K ions in isolated mitochondria from rat myometrium is sensitive to effectors of KATP-channel (ATP-sensitive K+-channel – ATP, diazoxide, glibenclamide and 5HD (5-hydroxydecanoate. Our data demonstrates that K+ uptake in isolated myometrium mitochondria results in a slight decrease in membrane potential, enhancement of generation of ROS (reactive oxygen species and mitochondrial swelling. Particularly, the addition of ATP into incubation medium led to a decrease in mitochondrial swelling and ROS production, and an increase in membrane potential. These effects were eliminated by diazoxide. If blockers of KATP-channel were added along with diazoxide, the effects of diazoxide were removed. So, we postulate the existence of KATP-channels in rat uterus mitochondria and assume that their functioning may regulate physiological conditions of mitochondria, such as matrix volume, ROS generation and polarization of mitochondrial membrane. Keywords: ATP-sensitive potassium channel, Diazoxide, 5-hydroxydecanoate, Myometrium, Mitochondria, Mitochondrial swelling, Mitochondrial membrane potential, ROS

Rapid granulation tissue regeneration by intracellular ATP delivery--a comparison with Regranex.

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Jeffrey D Howard

Full Text Available This study tests a new intracellular ATP delivery technique for tissue regeneration and compares its efficacy with that of Regranex. Twenty-seven adult New Zealand white rabbits each underwent minimally invasive surgery to render one ear ischemic. Eight wounds were then created: four on the ischemic and four on the normal ear. Two wounds on one side of each ear were treated with Mg-ATP encapsulated lipid vesicles (ATP-vesicles while the two wounds on the other side were treated with Regranex. Wound healing time was shorter when ATP-vesicles were used. The most striking finding was that new tissue growth started to appear in less than 1 day when ATP-vesicles were used. The growth continued and covered the wound area within a few days, without the formation of a provisional matrix. Regranex-treated wounds did not have this growth pattern. In wounds treated by ATP-vesicles, histologic studies revealed extremely rich macrophage accumulation, along with active proliferating cell nuclear antigen (PCNA and positive BrdU staining, indicating in situ macrophage proliferation. Human macrophage culture suggested direct collagen production. These results support an entirely new healing process, which seems to have combined the conventional hemostasis, inflammation, and proliferation phases into a single one, thereby eliminating the lag time usually seen during healing process.

Role of ATP in the regulation of cholesterol biogenesis

International Nuclear Information System (INIS)

Subba Rao, G.; Ramasarma, T.

1974-01-01

Intraperitoneal administration of glucose (4oomg/rat) stimulated the biogenesis of sterols in starved rats while citrate or pyruvate (20mg/rat) did not have any effect. ATP (10mg/ rat) administered intraperitoneally stimulated the incorporation of acetate-1- 14 C into sterols but not of mevalonate-2- 14 C into sterols in starved rats. The results indicate that ATP may play a role in regulating cholesterol biogenesis and it is not acting merely as an energy source. (author)

ATP-containing vesicles in stria vascular marginal cell cytoplasms in neonatal rat cochlea are lysosomes.

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Liu, Jun; Liu, Wenjing; Yang, Jun

2016-02-11

We confirmed that ATP is released from cochlear marginal cells in the stria vascular but the cell organelle in which ATP stores was not identified until now. Thus, we studied the ATP-containing cell organelles and suggest that these are lysosomes. Primary cultures of marginal cells of Sprague-Dawley rats aged 1-3 days was established. Vesicles within marginal cells stained with markers were identified under confocal laser scanning microscope and transmission electron microscope (TEM). Then ATP release from marginal cells was measured after glycyl-L-phenylalanine-ß- naphthylamide (GPN) treatment using a bioluminescent assay. Quinacrine-stained granules within marginal cells were labeled with LysoTracker, a lysosome tracer, and lysosomal-associated membrane protein 1(LAMP1), but not labeled with the mitochondrial tracer MitoTracker. Furthermore, LysoTracker-labelled puncta showed accumulation of Mant-ATP, an ATP analog. Treatment with 200 μM GPN quenched fluorescently labeled puncta after incubation with LysoTracker or quinacrine, but not MitoTracker. Quinacrine-labeled organelles observed by TEM were lysosomes, and an average 27.7 percent increase in ATP luminescence was observed in marginal cells extracellular fluid after GPN treatment. ATP-containing vesicles in cochlear marginal cells of the stria vascular from neonatal rats are likely lysosomes. ATP release from marginal cells may be via Ca(2+)-dependent lysosomal exocytosis.

Dynamic inhibition of excitatory synaptic transmission by astrocyte-derived ATP in hippocampal cultures

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Koizumi, Schuichi; Fujishita, Kayoko; Tsuda, Makoto; Shigemoto-Mogami, Yukari; Inoue, Kazuhide

2003-09-01

Originally ascribed passive roles in the CNS, astrocytes are now known to have an active role in the regulation of synaptic transmission. Neuronal activity can evoke Ca2+ transients in astrocytes, and Ca2+ transients in astrocytes can evoke changes in neuronal activity. The excitatory neurotransmitter glutamate has been shown to mediate such bidirectional communication between astrocytes and neurons. We demonstrate here that ATP, a primary mediator of intercellular Ca2+ signaling among astrocytes, also mediates intercellular signaling between astrocytes and neurons in hippocampal cultures. Mechanical stimulation of astrocytes evoked Ca2+ waves mediated by the release of ATP and the activation of P2 receptors. Mechanically evoked Ca2+ waves led to decreased excitatory glutamatergic synaptic transmission in an ATP-dependent manner. Exogenous application of ATP does not affect postsynaptic glutamatergic responses but decreased presynaptic exocytotic events. Finally, we show that astrocytes exhibit spontaneous Ca2+ waves mediated by extracellular ATP and that inhibition of these Ca2+ responses enhanced excitatory glutamatergic transmission. We therefore conclude that ATP released from astrocytes exerts tonic and activity-dependent down-regulation of synaptic transmission via presynaptic mechanisms.

A mutation within the extended X loop abolished substrate-induced ATPase activity of the human liver ATP-binding cassette (ABC) transporter MDR3.

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Kluth, Marianne; Stindt, Jan; Dröge, Carola; Linnemann, Doris; Kubitz, Ralf; Schmitt, Lutz

2015-02-20

The human multidrug resistance protein 3 (MDR3/ABCB4) belongs to the ubiquitous family of ATP-binding cassette (ABC) transporters and is located in the canalicular membrane of hepatocytes. There it flops the phospholipids of the phosphatidylcholine (PC) family from the inner to the outer leaflet. Here, we report the characterization of wild type MDR3 and the Q1174E mutant, which was identified previously in a patient with progressive familial intrahepatic cholestasis type 3 (PFIC-3). We expressed different variants of MDR3 in the yeast Pichia pastoris, purified the proteins via tandem affinity chromatography, and determined MDR3-specific ATPase activity in the presence or absence of phospholipids. The ATPase activity of wild type MDR3 was stimulated 2-fold by liver PC or 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine lipids. Furthermore, the cross-linking of MDR3 with a thiol-reactive fluorophore blocked ATP hydrolysis and exhibited no PC stimulation. Similarly, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin lipids did not induce an increase of wild type MDR3 ATPase activity. The phosphate analogues beryllium fluoride and aluminum fluoride led to complete inhibition of ATPase activity, whereas orthovanadate inhibited exclusively the PC-stimulated ATPase activity of MDR3. The Q1174E mutation is located in the nucleotide-binding domain in direct proximity of the leucine of the ABC signature motif and extended the X loop, which is found in ABC exporters. Our data on the Q1174E mutant demonstrated basal ATPase activity, but PC lipids were incapable of stimulating ATPase activity highlighting the role of the extended X loop in the cross-talk of the nucleotide-binding domain and the transmembrane domain. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

ATP synthesis is impaired in isolated mitochondria from myotubes established from type 2 diabetic subjects

DEFF Research Database (Denmark)

Minet, Ariane D; Gaster, Michael

2010-01-01

To date, it is unknown whether mitochondrial dysfunction in skeletal muscle from subjects with type 2 diabetes is based on primarily reduced mitochondrial mass and/or a primarily decreased mitochondrial ATP synthesis. Mitochondrial mass were determined in myotubes established from eight lean, eight...... mass and the ATP synthesis rate, neither at baseline nor during acute insulin stimulation, were not different between groups. The ratio of ATP synthesis rate at hexokinase versus ATP synthesis rate at baseline was lower in diabetic mitochondria compared to lean mitochondria. Thus the lower content...... obese and eight subjects with type 2 diabetes precultured under normophysiological conditions. Furthermore, mitochondria were isolated and ATP production was measured by luminescence at baseline and during acute insulin stimulation with or without concomitant ATP utilization by hexokinase. Mitochondrial...

A functional 12T-insertion polymorphism in the ATP1A1 promoter confers decreased susceptibility to hypertension in a male Sardinian population.

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Herrera, Victoria L; Pasion, Khristine A; Moran, Ann Marie; Zaninello, Roberta; Ortu, Maria Francesca; Fresu, Giovanni; Piras, Daniela Antonella; Argiolas, Giuseppe; Troffa, Chiara; Glorioso, Valeria; Masala, Wanda; Glorioso, Nicola; Ruiz-Opazo, Nelson

2015-01-01

kidney thereby decreasing sodium-associated risk for hypertension and sodium-induced endothelial stiffness and dysfunction. Altogether, data support ATP1A1 as a hypertension susceptibility gene in a male Sardinian population, and mandate further investigation of its involvement in hypertension in the general population.

A functional 12T-insertion polymorphism in the ATP1A1 promoter confers decreased susceptibility to hypertension in a male Sardinian population.

Directory of Open Access Journals (Sweden)

Victoria L Herrera

-reabsorption in the kidney thereby decreasing sodium-associated risk for hypertension and sodium-induced endothelial stiffness and dysfunction. Altogether, data support ATP1A1 as a hypertension susceptibility gene in a male Sardinian population, and mandate further investigation of its involvement in hypertension in the general population.

NpPDR1, a pleiotropic drug resistance-type ATP-binding cassette transporter from Nicotiana plumbaginifolia, plays a major role in plant pathogen defense.

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Stukkens, Yvan; Bultreys, Alain; Grec, Sébastien; Trombik, Tomasz; Vanham, Delphine; Boutry, Marc

2005-09-01

Nicotiana plumbaginifolia NpPDR1, a plasma membrane pleiotropic drug resistance-type ATP-binding cassette transporter formerly named NpABC1, has been suggested to transport the diterpene sclareol, an antifungal compound. However, direct evidence for a role of pleiotropic drug resistance transporters in the plant defense is still lacking. In situ immunolocalization and histochemical analysis using the gusA reporter gene showed that NpPDR1 was constitutively expressed in the whole root, in the leaf glandular trichomes, and in the flower petals. However, NpPDR1 expression was induced in the whole leaf following infection with the fungus Botrytis cinerea, and the bacteria Pseudomonas syringae pv tabaci, Pseudomonas fluorescens, and Pseudomonas marginalis pv marginalis, which do not induce a hypersensitive response in N. plumbaginifolia, whereas a weaker response was observed using P. syringae pv syringae, which does induce a hypersensitive response. Induced NpPDR1 expression was more associated with the jasmonic acid than the salicylic acid signaling pathway. These data suggest that NpPDR1 is involved in both constitutive and jasmonic acid-dependent induced defense. Transgenic plants in which NpPDR1 expression was prevented by RNA interference showed increased sensitivity to sclareol and reduced resistance to B. cinerea. These data show that NpPDR1 is involved in pathogen resistance and thus demonstrate a new role for the ATP-binding cassette transporter family.

Tolbutamide attenuates diazoxide-induced aggravation of hypoxic cell injury.

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Pissarek, M; Reichelt, C; Krauss, G J; Illes, P

1998-11-23

ATP-dependent potassium (KATP) channels of neurons are closed in the presence of physiological levels of intracellular ATP and open when ATP is depleted during hypoxia or metabolic damage. The present study investigates hypoxic alterations of purine and pyrimidine nucleotide levels supposed to intracellularly modulate KATP channels. In addition, the effects of the KATP channel activator diazoxide and its antagonist tolbutamide were investigated on ATP, GTP, CTP and UTP levels in slices of the parietal cortex. Hypoxia was evoked by saturation of the medium with 95% N2-5% CO2 instead of 95% O2-5% CO2 for 5 min. Nucleotide contents were measured by anion-exchange HPLC in neutralized perchloric acid extracts obtained from slices frozen immediately at the end of incubation. Hypoxia per se decreased purine and pyrimidine nucleoside triphosphate contents. Thus, ATP and GTP contents were reduced to 69.9 and 77.6% of the respective normoxic levels. UTP and CTP contents were even more decreased (to 60.9 and 41.6%),, probably because the salvage pathway of these pyrimidine nucleotides is less effective than that of the purine nucleotides ATP and GTP. While tolbutamide (30 microM) had no effect on the hypoxia-induced decrease of nucleotides, diazoxide at 300, but not 30 microM aggravated the decline of ATP, UTP and CTP to 51.8, 37.5 and 28.5% of the contents observed at normoxia; GTP levels also showed a tendency to decrease after diazoxide application. Tolbutamide (300 microM) antagonized the effects of diazoxide (300 but not 30 microM aggravated the decline of ATP, UTP and CTP to 51.8, 37.5 and 28.5% of the contents observed at normoxia; GTP levels also showed a tendency to decrease after diazoxide application. Tolbutamide (300 microM) antagonized the effects of diazoxide (300 MicroM). Nucleoside diphosphate (ADP, GDP and UDP) levels were uniformly increased by hypoxia. There was no hypoxia-induced increase of ADP contents in the presence of tolbutamide (300 microM). The ATP

Maternal protein restriction induces alterations in insulin signaling and ATP sensitive potassium channel protein in hypothalami of intrauterine growth restriction fetal rats.

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Liu, Xiaomei; Qi, Ying; Gao, Hong; Jiao, Yisheng; Gu, Hui; Miao, Jianing; Yuan, Zhengwei

2013-01-01

It is well recognized that intrauterine growth restriction leads to the development of insulin resistance and type 2 diabetes mellitus in adulthood. To investigate the mechanisms behind this "metabolic imprinting" phenomenon, we examined the impact of maternal undernutrition on insulin signaling pathway and the ATP sensitive potassium channel expression in the hypothalamus of intrauterine growth restriction fetus. Intrauterine growth restriction rat model was developed through maternal low protein diet. The expression and activated levels of insulin signaling molecules and K(ATP) protein in the hypothalami which were dissected at 20 days of gestation, were analyzed by western blot and real time PCR. The tyrosine phosphorylation levels of the insulin receptor substrate 2 and phosphatidylinositol 3'-kinase p85α in the hypothalami of intrauterine growth restriction fetus were markedly reduced. There was also a downregulation of the hypothalamic ATP sensitive potassium channel subunit, sulfonylurea receptor 1, which conveys the insulin signaling. Moreover, the abundances of gluconeogenesis enzymes were increased in the intrauterine growth restriction livers, though no correlation was observed between sulfonylurea receptor 1 and gluconeogenesis enzymes. Our data suggested that aberrant intrauterine milieu impaired insulin signaling in the hypothalamus, and these alterations early in life might contribute to the predisposition of the intrauterine growth restriction fetus toward the adult metabolic disorders.

Mitochondria Targeted Nanoscale Zeolitic Imidazole Framework-90 for ATP Imaging in Live Cells.

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Deng, Jingjing; Wang, Kai; Wang, Ming; Yu, Ping; Mao, Lanqun

2017-04-26

Zeolitic imidazole frameworks (ZIFs) are an emerging class of functional porous materials with promising biomedical applications such as molecular sensing and intracellular drug delivery. We report herein the first example of using nanoscale ZIFs (i.e., ZIF-90), self-assembled from Zn 2+ and imidazole-2-carboxyaldehyde, to target subcellular mitochondria and image dynamics of mitochondrial ATP in live cells. Encapsulation of fluorescent Rhodamine B (RhB) into ZIF-90 suppresses the emission of RhB, while the competitive coordination between ATP and the metal node of ZIF-90 dissembles ZIFs, resulting in the release of RhB for ATP sensing. With this method, we are able to image mitochondrial ATP in live cells and study the ATP level fluctuation in cellular glycolysis and apoptosis processes. The strategy reported here could be further extended to tune nanoscale ZIFs inside live cells for targeted delivery of therapeutics to subcellular organelles for advanced biomedical applications.

A futile cycle, formed between two ATP-dependant γ-glutamyl cycle ...

Indian Academy of Sciences (India)

Cystinosis, an inherited disease caused by a defect in the lysosomal cystine transporter (CTNS), is characterized by renal proximal tubular dysfunction. Adenosine triphosphate (ATP) depletion appears to be a key event in the pathophysiology of the disease, even though the manner in which ATP depletion occurs is still a ...

High-altitude adaptation of Tibetan chicken from MT-COI and ATP-6 perspective.

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Zhao, Xiaoling; Wu, Nan; Zhu, Qing; Gaur, Uma; Gu, Ting; Li, Diyan

2016-09-01

The problem of hypoxia adaptation in high altitudes is an unsolved brainteaser in the field of life sciences. As one of the best chicken breeds with adaptability to highland environment, the Tibetan chicken, is genetically different from lowland chicken breeds. In order to gain a better understanding of the mechanism of hypoxic adaptability in high altitude, in the present study, we focused on the MT-COI together with ATP-6 gene to explore the regulatory mechanisms for hypoxia adaptability in Tibet chicken. Here, we sequenced MT-COI of 29 Tibetan chickens and 30 Chinese domestic chickens and ATP-6 gene of 28 Tibetan chickens and 29 Chinese domestic chickens. In MT-COI gene, 9 single nucleotide polymorphisms (SNPs) were detected though none of these was a missense mutation, confirming the fact that MT-COI gene is a largely conservative sequence. In ATP-6 gene, 6 single nucleotide polymorphisms (SNPs) were detected and we found a missense mutation (m.9441G > A) in the ATP-6 gene of Tibetan chicken resulting in an amino acid substitution. Due to the critical role of ATP-6 gene in the proton translocation and energy metabolism, we speculated the possibility of this mutation playing an important role in easier energy conversion and metabolism in Tibetan chickens than Chinese domestic chickens so as to better adapt to the harsh environment of the high-altitude areas. The Median-joining profile also suggested that haplotype Ha2 has the ancestral position to the other haplotypes and has significant relationship with high-altitude adaptation in ATP-6 gene. Therefore, we considered that the polymorphism (m.9441G > A) in the ATP-6 gene may affect the specific functions of ATP-6 enzyme relating to high-altitude adaptation of Tibetan chicken and MT-COI gene is a largely conservative sequence.

Atp1a3-deficient heterozygous mice show lower rank in the hierarchy and altered social behavior.

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Sugimoto, H; Ikeda, K; Kawakami, K

2017-10-23

Atp1a3 is the Na-pump alpha3 subunit gene expressed mainly in neurons of the brain. Atp1a3-deficient heterozygous mice (Atp1a3 +/- ) show altered neurotransmission and deficits of motor function after stress loading. To understand the function of Atp1a3 in a social hierarchy, we evaluated social behaviors (social interaction, aggression, social approach and social dominance) of Atp1a3 +/- and compared the rank and hierarchy structure between Atp1a3 +/- and wild-type mice within a housing cage using the round-robin tube test and barbering observations. Formation of a hierarchy decreases social conflict and promote social stability within the group. The hierarchical rank is a reflection of social dominance within a cage, which is heritable and can be regulated by specific genes in mice. Here we report: (1) The degree of social interaction but not aggression was lower in Atp1a3 +/- than wild-type mice, and Atp1a3 +/- approached Atp1a3 +/- mice more frequently than wild type. (2) The frequency of barbering was lower in the Atp1a3 +/- group than in the wild-type group, while no difference was observed in the mixed-genotype housing condition. (3) Hierarchy formation was not different between Atp1a3 +/- and wild type. (4) Atp1a3 +/- showed a lower rank in the mixed-genotype housing condition than that in the wild type, indicating that Atp1a3 regulates social dominance. In sum, Atp1a3 +/- showed unique social behavior characteristics of lower social interaction and preference to approach the same genotype mice and a lower ranking in the hierarchy. © 2017 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

A two-hour antibiotic susceptibility test by ATP-bioluminescence.

Science.gov (United States)

March Rosselló, Gabriel Alberto; García-Loygorri Jordán de Urries, María Cristina; Gutiérrez Rodríguez, María Purificación; Simarro Grande, María; Orduña Domingo, Antonio; Bratos Pérez, Miguel Ángel

2016-01-01

The antibiotic susceptibility test (AST) in Clinical Microbiology laboratories is still time-consuming, and most procedures take 24h to yield results. In this study, a rapid antimicrobial susceptibility test using ATP-bioluminescence has been developed. The design of method was performed using five ATCC collection strains of known susceptibility. This procedure was then validated against standard commercial methods on 10 strains of enterococci, 10 staphylococci, 10 non-fermenting gram negative bacilli, and 13 Enterobacteriaceae from patients. The agreement obtained in the sensitivity between the ATP-bioluminescence method and commercial methods (E-test, MicroScan and VITEK2) was 100%. In summary, the preliminary results obtained in this work show that the ATP-bioluminescence method could provide a fast and reliable AST in two hours. Copyright © 2015 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Inhibition of the cardiac ATP-dependent potassium current by KB-R7943.

Science.gov (United States)

Abramochkin, Denis V; Vornanen, Matti

2014-09-01

KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea) was developed as a specific inhibitor of the sarcolemmal sodium-calcium exchanger (NCX) with potential experimental and therapeutic use. However, in cardiomyocytes KB-R7943 also effectively blocks several K(+) currents including the delayed rectifier, IKr, and background inward rectifier, IK1. In the present study we analyze the effects of KB-R7943 on the ATP-dependent potassium current (IKATP) recorded by whole-cell patch-clamp in ventricular cardiomyocytes from a mammal (mouse) and a fish (crucian carp). IKATP was induced by external application of a mitochondrial uncoupler CCCP (3×10(-7) M) and internal perfusion of the cell with ATP-free pipette solution. A weakly inwardly rectifying current with a large outward component, recorded in the presence of CCCP, was blocked with 10(-5) M glibenclamide by 56.1±4.6% and 56.9±3.6% in crucian carp and mouse ventricular myocytes, respectively. In fish cardiomyocytes IKATP was blocked by KB-R7943 with an IC50 value of 3.14×10(-7) M, while in mammalian cells IC50 was 2.8×10(-6) M (PKB-R7943 inhibited CCCP-induced IKATP by 99.9±0.13% and 97.5±1.2% in crucian carp and mouse ventricular myocytes, respectively. In crucian carp the IKATP is about an order of magnitude more sensitive to KB-R7943 than the background IK1, but in mammals IKATP and IK1 are almost equally sensitive to KB-R7943. Therefore, the ability of KB-R7943 to block IKATP should be taken into account together with INCX inhibition when investigating possible cardioprotective effects of this compound. Copyright © 2014 Elsevier Inc. All rights reserved.

Cloning and characterization of ATP synthase CF1 α gene from ...

African Journals Online (AJOL)

ATP synthase CF1 α subunit protein is a key enzyme for energy metabolism in plant kingdom, and plays an important role in multiple cell processes. In this study, the complete atpA gene (accession no. JN247444) was cloned from sweet potato (Ipomoea batatas L. Lam) by reverse transcriptasepolymerase chain reaction ...

Single K ATP channel opening in response to action potential firing in mouse dentate granule neurons.

Science.gov (United States)

Tanner, Geoffrey R; Lutas, Andrew; Martínez-François, Juan Ramón; Yellen, Gary

2011-06-08

ATP-sensitive potassium channels (K(ATP) channels) are important sensors of cellular metabolic state that link metabolism and excitability in neuroendocrine cells, but their role in nonglucosensing central neurons is less well understood. To examine a possible role for K(ATP) channels in modulating excitability in hippocampal circuits, we recorded the activity of single K(ATP) channels in cell-attached patches of granule cells in the mouse dentate gyrus during bursts of action potentials generated by antidromic stimulation of the mossy fibers. Ensemble averages of the open probability (p(open)) of single K(ATP) channels over repeated trials of stimulated spike activity showed a transient increase in p(open) in response to action potential firing. Channel currents were identified as K(ATP) channels through blockade with glibenclamide and by comparison with recordings from Kir6.2 knock-out mice. The transient elevation in K(ATP) p(open) may arise from submembrane ATP depletion by the Na(+)-K(+) ATPase, as the pump blocker strophanthidin reduced the magnitude of the elevation. Both the steady-state and stimulus-elevated p(open) of the recorded channels were higher in the presence of the ketone body R-β-hydroxybutyrate, consistent with earlier findings that ketone bodies can affect K(ATP) activity. Using perforated-patch recording, we also found that K(ATP) channels contribute to the slow afterhyperpolarization following an evoked burst of action potentials. We propose that activity-dependent opening of K(ATP) channels may help granule cells act as a seizure gate in the hippocampus and that ketone-body-mediated augmentation of the activity-dependent opening could in part explain the effect of the ketogenic diet in reducing epileptic seizures.

ATP forms a stable complex with the essential histidine kinase WalK (YycG) domain

Energy Technology Data Exchange (ETDEWEB)

Celikel, Reha; Veldore, Vidya Harini [University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205 (United States); Mathews, Irimpan [Stanford Synchrotron Radiation Lightsource, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Devine, Kevin M., E-mail: kdevine@tcd.ie [Trinity College Dublin, Dublin 2 (Ireland); Varughese, Kottayil I., E-mail: kdevine@tcd.ie [University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205 (United States)

2012-07-01

The histidine WalK (YycG) plays a crucial role in coordinating murein synthesis with cell division and the crystal structure of its ATP binding domain has been determined. Interestingly the bound ATP was not hydrolyzed during crystallization and remains intact in the crystal lattice. In Bacillus subtilis, the WalRK (YycFG) two-component system coordinates murein synthesis with cell division. It regulates the expression of autolysins that function in cell-wall remodeling and of proteins that modulate autolysin activity. The transcription factor WalR is activated upon phosphorylation by the histidine kinase WalK, a multi-domain homodimer. It autophosphorylates one of its histidine residues by transferring the γ-phosphate from ATP bound to its ATP-binding domain. Here, the high-resolution crystal structure of the ATP-binding domain of WalK in complex with ATP is presented at 1.61 Å resolution. The bound ATP remains intact in the crystal lattice. It appears that the strong binding interactions and the nature of the binding pocket contribute to its stability. The triphosphate moiety of ATP wraps around an Mg{sup 2+} ion, providing three O atoms for coordination in a near-ideal octahedral geometry. The ATP molecule also makes strong interactions with the protein. In addition, there is a short contact between the exocyclic O3′ of the sugar ring and O2B of the β-phosphate, implying an internal hydrogen bond. The stability of the WalK–ATP complex in the crystal lattice suggests that such a complex may exist in vivo poised for initiation of signal transmission. This feature may therefore be part of the sensing mechanism by which the WalRK two-component system is so rapidly activated when cells encounter conditions conducive for growth.

Redox regulation of ATP sulfurylase in microalgae

Czech Academy of Sciences Publication Activity Database

Prioretti, L.; Lebrun, R.; Gontero, B.; Giordano, Mario

2016-01-01

Roč. 478, č. 4 (2016), s. 1555-1562 ISSN 0006-291X Institutional support: RVO:61388971 Keywords : ATP sulfurylase * cysteine * Sulfur metabolism Subject RIV: EE - Microbiology, Virology Impact factor: 2.466, year: 2016

Intestinal bile salt absorption in Atp8b1 deficient mice

NARCIS (Netherlands)

Groen, Annemiek; Kunne, Cindy; Paulusma, Coen C.; Kramer, Werner; Agellon, Luis B.; Bull, Laura N.; Elferink, Ronald P. J. Oude

2007-01-01

BACKGROUND/AIMS: Mutations in the ATP8B1 gene can cause Progressive Familial Intrahepatic Cholestasis type 1. We have previously reported that Atp8b1(G308V/G308V) mice, a model for PFIC1, have slightly, but significantly, higher baseline serum bile salt (BS) concentrations compared to wt mice. Upon

The Yeast Plasma Membrane ATP Binding Cassette (ABC) Transporter Aus1

Science.gov (United States)

Marek, Magdalena; Milles, Sigrid; Schreiber, Gabriele; Daleke, David L.; Dittmar, Gunnar; Herrmann, Andreas; Müller, Peter; Pomorski, Thomas Günther

2011-01-01

The ATP binding cassette (ABC) transporter Aus1 is expressed under anaerobic growth conditions at the plasma membrane of the yeast Saccharomyces cerevisiae and is required for sterol uptake. These observations suggest that Aus1 promotes the translocation of sterols across membranes, but the precise transport mechanism has yet to be identified. In this study, an extraction and purification procedure was developed to characterize the Aus1 transporter. The detergent-solubilized protein was able to bind and hydrolyze ATP. Mutagenesis of the conserved lysine to methionine in the Walker A motif abolished ATP hydrolysis. Likewise, ATP hydrolysis was inhibited by classical inhibitors of ABC transporters. Upon reconstitution into proteoliposomes, the ATPase activity of Aus1 was specifically stimulated by phosphatidylserine (PS) in a stereoselective manner. We also found that Aus1-dependent sterol uptake, but not Aus1 expression and trafficking to the plasma membrane, was affected by changes in cellular PS levels. These results suggest a direct interaction between Aus1 and PS that is critical for the activity of the transporter. PMID:21521689

Nucleotide transmitters ATP and ADP mediate intercellular calcium wave communication via P2Y12/13 receptors among BV-2 microglia.

Directory of Open Access Journals (Sweden)

Pengchong Jiang

Full Text Available Nerve injury is accompanied by a liberation of diverse nucleotides, some of which act as 'find/eat-me' signals in mediating neuron-glial interplay. Intercellular Ca2+ wave (ICW communication is the main approach by which glial cells interact and coordinate with each other to execute immune defense. However, the detailed mechanisms on how these nucleotides participate in ICW communication remain largely unclear. In the present work, we employed a mechanical stimulus to an individual BV-2 microglia to simulate localized injury. Remarkable ICW propagation was observed no matter whether calcium was in the environment or not. Apyrase (ATP/ADP-hydrolyzing enzyme, suramin (broad-spectrum P2 receptor antagonist, 2-APB (IP3 receptor blocker and thapsigargin (endoplasmic reticulum calcium pump inhibitor potently inhibited these ICWs, respectively, indicating the dependence of nucleotide signals and P2Y receptors. Then, we detected the involvement of five naturally occurring nucleotides (ATP, ADP, UTP, UDP and UDP-glucose by desensitizing receptors. Results showed that desensitization with ATP and ADP could block ICW propagation in a dose-dependent manner, whereas other nucleotides had little effect. Meanwhile, the expression of P2Y receptors in BV-2 microglia was identified and their contributions were analyzed, from which we suggested P2Y12/13 receptors activation mostly contributed to ICWs. Besides, we estimated that extracellular ATP and ADP concentration sensed by BV-2 microglia was about 0.3 μM during ICWs by analyzing calcium dynamic characteristics. Taken together, these results demonstrated that the nucleotides ATP and ADP were predominant signal transmitters in mechanical stimulation-induced ICW communication through acting on P2Y12/13 receptors in BV-2 microglia.

NpPDR1, a Pleiotropic Drug Resistance-Type ATP-Binding Cassette Transporter from Nicotiana plumbaginifolia, Plays a Major Role in Plant Pathogen Defense1

Science.gov (United States)

Stukkens, Yvan; Bultreys, Alain; Grec, Sébastien; Trombik, Tomasz; Vanham, Delphine; Boutry, Marc

2005-01-01

Nicotiana plumbaginifolia NpPDR1, a plasma membrane pleiotropic drug resistance-type ATP-binding cassette transporter formerly named NpABC1, has been suggested to transport the diterpene sclareol, an antifungal compound. However, direct evidence for a role of pleiotropic drug resistance transporters in the plant defense is still lacking. In situ immunolocalization and histochemical analysis using the gusA reporter gene showed that NpPDR1 was constitutively expressed in the whole root, in the leaf glandular trichomes, and in the flower petals. However, NpPDR1 expression was induced in the whole leaf following infection with the fungus Botrytis cinerea, and the bacteria Pseudomonas syringae pv tabaci, Pseudomonas fluorescens, and Pseudomonas marginalis pv marginalis, which do not induce a hypersensitive response in N. plumbaginifolia, whereas a weaker response was observed using P. syringae pv syringae, which does induce a hypersensitive response. Induced NpPDR1 expression was more associated with the jasmonic acid than the salicylic acid signaling pathway. These data suggest that NpPDR1 is involved in both constitutive and jasmonic acid-dependent induced defense. Transgenic plants in which NpPDR1 expression was prevented by RNA interference showed increased sensitivity to sclareol and reduced resistance to B. cinerea. These data show that NpPDR1 is involved in pathogen resistance and thus demonstrate a new role for the ATP-binding cassette transporter family. PMID:16126865

Energy-dependent dissociation of ATP from high affinity catalytic sites of beef heart mitochondrial adenosine triphosphatase

International Nuclear Information System (INIS)

Penefsky, H.S.

1985-01-01

Incubation of [gamma- 32 P]ATP with a molar excess of the membrane-bound form of mitochondrial ATPase (F1) results in binding of the bulk of the radioactive nucleotide in high affinity catalytic sites (Ka = 10(12) M-1). Subsequent initiation of respiration by addition of succinate or NADH is accompanied by a profound decrease in the affinity for ATP. About one-third of the bound radioactive ATP appears to dissociate, that is, the [gamma- 32 P]ATP becomes accessible to hexokinase. The NADH-stimulated dissociation of [gamma- 32 P]ATP is energy-dependent since the stimulation is inhibited by uncouplers of oxidative phosphorylation and is prevented by respiratory chain inhibitors. The rate of the energy-dependent dissociation of ATP that occurs in the presence of NADH, ADP, and Pi is commensurate with the measured initial rate of ATP synthesis in NADH-supported oxidative phosphorylation catalyzed by the same submitochondrial particles. Thus, the rate of dissociation of ATP from the high affinity catalytic site of submitochondrial particles meets the criterion of kinetic competency under the conditions of oxidative phosphorylation. These experiments provide evidence in support of the argument that energy conserved during the oxidation of substrates by the respiratory chain can be utilized to reduce the very tight binding of product ATP in high affinity catalytic sites and to promote dissociation of the nucleotide

Functional mitochondrial ATP synthase proteolipid gene produced by recombination of parental genes in a petunia somatic hybrid

International Nuclear Information System (INIS)

Rothenberg, M.; Hanson, M.R.

1988-01-01

A novel ATP synthase subunit 9 gene (atp9) was identified in the mitochondrial genome of a Petunia somatic hybrid line (13-133) which was produced from a fusion between Petunia lines 3688 and 3704. The novel gene was generated by intergenomic recombination between atp9 genes from the two parental plant lines. The entire atp9 coding region is represented on the recombinant gene. Comparison of gene sequences using electrophoresis and autoradiography, indicate that the 5' transcribed region is contributed by an atp9 gene from 3704 and the 3' transcribed region is contributed by an atp9 gene from 3688. The recombinant atp9 gene is transcriptionally active. The location of the 5' and 3' transcript termini are conserved with respect to the parental genes, resulting in the production of hybrid transcripts

Estimation of PMI depends on the changes in ATP and its degradation products.

Science.gov (United States)

Mao, Shiwei; Fu, Gaowen; Seese, Ronald R; Wang, Zhen-Yuan

2013-09-01

Estimating the time since death, or postmortem interval (PMI), has been one of the biggest difficulties in modern forensic investigation. This study tests if the concentrations of breakdown products of adenosine triphosphate (ATP) correlate with PMI in multiple organs from rat. Brains, spleens, and kidneys of rats were harvested at different time points in carcasses maintained at 4°C or 20°C. High Performance Liquid Chromatography (HPLC) was used to quantify concentrations of metabolites related to ATP degradation. A K value (Kv=100×(Hx+HxR)/(ATP+ADP+AMP+IMP+HxR+Hx)) was calculated and correlated with PMI for each organ and temperature. The results indicate that the K value is a robust index for the estimation of PMI based on highly significant linear correlations between PMI and concentrations of ATP breakdown products. Compared with other current research methods, the changing tendency of ATP and its degradation products may be potentially a better way for the estimation of PMI in medico-legal practice. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Degradation of ATP and glycogen in cod ( Gadus morhua ) muscle during freezing

DEFF Research Database (Denmark)

Cappeln, Gertrud; Jessen, Flemming

2001-01-01

Changes in ATP, IMP, lactate and glycogen contents in the muscle of cod were followed during freezing at temperatures of -20C and -45C. ATP degradation was accompanied by a corresponding increase in IMP content. Simultaneous measurement of temperature showed that at both freezing rates......, the greatest decrease in ATP content was observed when the temperature reached -0.8C. Glycolysis occurred during freezing of cod as indicated by an increase in lactate content. The changes found in all measured metabolites were more pronounced when freezing was performed at a slow rate compared to a fast rate...

Escherichia coli contains a soluble ATP-dependent protease (Ti) distinct from protease La

Energy Technology Data Exchange (ETDEWEB)

Hwang, B.J.; Park, W.J.; Chung, C.H.; Goldberg, A.L.

1987-08-01

The energy requirement for protein breakdown in Escherichia coli has generally been attributed to the ATP-dependence of protease La, the lon gene product. The authors have partially purified another ATP-dependent protease from lon/sup -/ cells that lack protease La (as shown by immunoblotting). This enzyme hydrolyzes (/sup 3/H)methyl-casein to acid-soluble products in the presence of ATP and Mg/sup 2 +/. ATP hydrolysis appears necessary for proteolytic activity. Since this enzyme is inhibited by diisopropyl fluorophosphate, it appears to be a serine protease, but it also contains essential thiol residues. They propose to name this enzyme protease Ti. It differs from protease La in nucleotide specificity, inhibitor sensitivity, and subunit composition. On gel filtration, protease Ti has an apparent molecular weight of 370,000. It can be fractionated by phosphocellulose chromatography or by DEAE chromatography into two components with apparent molecular weights of 260,000 and 140,000. When separated, they do not show preteolytic activity. One of these components, by itself, has ATPase activity and is labile in the absence of ATP. The other contains the diisopropyl fluorophosphate-sensitive proteolytic site. These results and the similar findings of Katayama-Fujimura et al. indicate that E. coli contains two ATP-hydrolyzing proteases, which differ in many biochemical features and probably in their physiological roles.

Escherichia coli contains a soluble ATP-dependent protease (Ti) distinct from protease La

International Nuclear Information System (INIS)

Hwang, B.J.; Park, W.J.; Chung, C.H.; Goldberg, A.L.

1987-01-01

The energy requirement for protein breakdown in Escherichia coli has generally been attributed to the ATP-dependence of protease La, the lon gene product. The authors have partially purified another ATP-dependent protease from lon - cells that lack protease La (as shown by immunoblotting). This enzyme hydrolyzes [ 3 H]methyl-casein to acid-soluble products in the presence of ATP and Mg 2+ . ATP hydrolysis appears necessary for proteolytic activity. Since this enzyme is inhibited by diisopropyl fluorophosphate, it appears to be a serine protease, but it also contains essential thiol residues. They propose to name this enzyme protease Ti. It differs from protease La in nucleotide specificity, inhibitor sensitivity, and subunit composition. On gel filtration, protease Ti has an apparent molecular weight of 370,000. It can be fractionated by phosphocellulose chromatography or by DEAE chromatography into two components with apparent molecular weights of 260,000 and 140,000. When separated, they do not show preteolytic activity. One of these components, by itself, has ATPase activity and is labile in the absence of ATP. The other contains the diisopropyl fluorophosphate-sensitive proteolytic site. These results and the similar findings of Katayama-Fujimura et al. indicate that E. coli contains two ATP-hydrolyzing proteases, which differ in many biochemical features and probably in their physiological roles

Pharmacological and molecular comparison of K(ATP) channels in rat basilar and middle cerebral arteries

DEFF Research Database (Denmark)

Ploug, Kenneth Beri; Edvinsson, Lars; Olesen, Jes

2006-01-01

, we studied the possible involvement of endothelial K(ATP) channels by pressurized arteriography after luminal administration of synthetic K(ATP) channel openers to rat basilar and middle cerebral arteries. Furthermore, we examined the mRNA and protein expression profile of K(ATP) channels to rat...... basilar and middle cerebral arteries using quantitative real-time PCR (Polymerase Chain Reaction) and Western blotting, respectively. In the perfusion system, we found no significant responses after luminal application of three K(ATP) channel openers to rat basilar and middle cerebral arteries...

A self-referencing biosensor for real-time monitoring of physiological ATP transport in plant systems.

Science.gov (United States)

Vanegas, Diana C; Clark, Greg; Cannon, Ashley E; Roux, Stanley; Chaturvedi, Prachee; McLamore, Eric S

2015-12-15

The objective of this study was to develop a self-referencing electrochemical biosensor for the direct measurement of ATP flux into the extracellular matrix by living cells/organisms. The working mechanism of the developed biosensor is based on the activity of glycerol kinase and glycerol-3-phosphate oxidase. A stratified bi-enzyme nanocomposite was created using a protein-templated silica sol gel encapsulation technique on top of graphene-modified platinum electrodes. The biosensor exhibited excellent electrochemical performance with a sensitivity of 2.4±1.8 nA/µM, a response time of 20±13 s and a lower detection limit of 1.3±0.7 nM. The self-referencing biosensor was used to measure exogenous ATP efflux by (i) germinating Ceratopteris spores and (ii) growing Zea mays L. roots. This manuscript demonstrates the first development of a non-invasive ATP micro-biosensor for the direct measurement of eATP transport in living tissues. Before this work, assays of eATP have not been able to record the temporally transient movement of ATP at physiological levels (nM and sub-nM). The method demonstrated here accurately measured [eATP] flux in the immediate vicinity of plant cells. Although these proof of concept experiments focus on plant tissues, the technique developed herein is applicable to any living tissue, where nanomolar concentrations of ATP play a critical role in signaling and development. This tool will be invaluable for conducting hypothesis-driven life science research aimed at understanding the role of ATP in the extracellular environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Timely binding of IHF and Fis to DARS2 regulates ATP-DnaA production and replication initiation.

Science.gov (United States)

Kasho, Kazutoshi; Fujimitsu, Kazuyuki; Matoba, Toshihiro; Oshima, Taku; Katayama, Tsutomu

2014-12-01

In Escherichia coli, the ATP-bound form of DnaA (ATP-DnaA) promotes replication initiation. During replication, the bound ATP is hydrolyzed to ADP to yield the ADP-bound form (ADP-DnaA), which is inactive for initiation. The chromosomal site DARS2 facilitates the regeneration of ATP-DnaA by catalyzing nucleotide exchange between free ATP and ADP bound to DnaA. However, the regulatory mechanisms governing this exchange reaction are unclear. Here, using in vitro reconstituted experiments, we show that two nucleoid-associated proteins, IHF and Fis, bind site-specifically to DARS2 to activate coordinately the exchange reaction. The regenerated ATP-DnaA was fully active in replication initiation and underwent DnaA-ATP hydrolysis. ADP-DnaA formed heteromultimeric complexes with IHF and Fis on DARS2, and underwent nucleotide dissociation more efficiently than ATP-DnaA. Consistently, mutant analyses demonstrated that specific binding of IHF and Fis to DARS2 stimulates the formation of ATP-DnaA production, thereby promoting timely initiation. Moreover, we show that IHF-DARS2 binding is temporally regulated during the cell cycle, whereas Fis only binds to DARS2 in exponentially growing cells. These results elucidate the regulation of ATP-DnaA and replication initiation in coordination with the cell cycle and growth phase. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Regulation of ATP-sensitive K+ channels in insulinoma cells: Activation by somatostatin and protein kinase C and the role of cAMP

International Nuclear Information System (INIS)

De Weille, J.R.; Schmid-Antomarchi, H.; Fosset, M.; Lazdunski, M.

1989-01-01

The actions of somatostatin and of the phorbol ester 4β-phorbol 12-myristate 13-acetate (PMA) were studied in rat insulinoma (RINm5F) cells by electrophysiological and 86 Rb + flux techniques. Both PMA and somatostatin hyperpolarize insulinoma cells by activating ATP-sensitive K + channels. The presence of intracellular GTP is required for the somatostatin effects. PMA- and somatostatin-induced hyperpolarization and channel activity are inhibited by the sulfonylurea glibenclamide. Glibenclamide-sensitive 86 Rb + efflux from insulinoma cells is stimulated by somatostatin in a dose-dependent manner (half maximal effect at 0.7 nM) and abolished by pertussis toxin pretreatment. Mutual roles of a GTP-binding protein, of protein kinase C, and of cAMP in the regulation of ATP-sensitive K + channels are discussed

Decline of Phosphotransfer and Substrate Supply Metabolic Circuits Hinders ATP Cycling in Aging Myocardium.

Directory of Open Access Journals (Sweden)

Emirhan Nemutlu

Full Text Available Integration of mitochondria with cytosolic ATP-consuming/ATP-sensing and substrate supply processes is critical for muscle bioenergetics and electrical activity. Whether age-dependent muscle weakness and increased electrical instability depends on perturbations in cellular energetic circuits is unknown. To define energetic remodeling of aged atrial myocardium we tracked dynamics of ATP synthesis-utilization, substrate supply, and phosphotransfer circuits through adenylate kinase (AK, creatine kinase (CK, and glycolytic/glycogenolytic pathways using 18O stable isotope-based phosphometabolomic technology. Samples of intact atrial myocardium from adult and aged rats were subjected to 18O-labeling procedure at resting basal state, and analyzed using the 18O-assisted HPLC-GC/MS technique. Characteristics for aging atria were lower inorganic phosphate Pi[18O], γ-ATP[18O], β-ADP[18O], and creatine phosphate CrP[18O] 18O-labeling rates indicating diminished ATP utilization-synthesis and AK and CK phosphotransfer fluxes. Shift in dynamics of glycolytic phosphotransfer was reflected in the diminished G6P[18O] turnover with relatively constant glycogenolytic flux or G1P[18O] 18O-labeling. Labeling of G3P[18O], an indicator of G3P-shuttle activity and substrate supply to mitochondria, was depressed in aged myocardium. Aged atrial myocardium displayed reduced incorporation of 18O into second (18O2, third (18O3, and fourth (18O4 positions of Pi[18O] and a lower Pi[18O]/γ-ATP[18 O]-labeling ratio, indicating delayed energetic communication and ATP cycling between mitochondria and cellular ATPases. Adrenergic stress alleviated diminished CK flux, AK catalyzed β-ATP turnover and energetic communication in aging atria. Thus, 18O-assisted phosphometabolomics uncovered simultaneous phosphotransfer through AK, CK, and glycolytic pathways and G3P substrate shuttle deficits hindering energetic communication and ATP cycling, which may underlie energetic

7-ketocholesteryl-9-carboxynonanoate enhances ATP binding cassette transporter A1 expression mediated by PPARγ in THP-1 macrophages.

Science.gov (United States)

Chi, Yan; Wang, Le; Liu, Yuanyuan; Ma, Yanhua; Wang, Renjun; Han, Xiaofei; Qiao, Hui; Lin, Jiabin; Matsuura, Eiji; Liu, Shuqian; Liu, Qingping

2014-06-01

ATP binding cassette transporter A1 (ABCA1) is a member of the ATP-binding cassette transporter family. It plays an essential role in mediating the efflux of excess cholesterol. It is known that peroxisome proliferator-activated receptor gamma (PPARγ) promoted ABCA1 expression. We previously found 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) upregulated ABCA1 partially through CD36 mediated signals. In the present study, we intended to test if PPARγ signally is involved in the upregulation mediated by oxLig-1. First, we docked oxLig-1 and the ligand-binding domain (LBD) of PPARγ by using AutoDock 3.05 and subsequently confirmed the binding by ELISA assay. Western blotting analyses showed that oxLig-1 induces liver X receptor alpha (LXRα), PPARγ and consequently ABCA1 expression. Furthermore, oxLig-1 significantly enhanced ApoA-I-mediated cholesterol efflux. Pretreatment with an inhibitor for PPARγ (GW9662) or/and LXRα (GGPP) attenuated oxLig-1-induced ABCA1 expression. Under PPARγ knockdown by using PPARγ-shRNA, oxLig-1-induced ABCA1 expression and cholesterol efflux in THP-1 macrophages was blocked by 62% and 25% respectively. These observations suggest that oxLig-1 is a novel PPARγ agonist, promoting ApoA-I-mediated cholesterol efflux from THP-1 macrophages by increasing ABCA1 expression via induction of PPARγ. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Optimization time synthesis of nucleotide labelled [γ-32P]-ATP

International Nuclear Information System (INIS)

Rahman, Wira Y; Sarmini, Endang; Herlina; Lubis, Hotman; Triyanto; Hambali

2013-01-01

Adenosine triphosphate-labelled with γ- 32 P([γ- 32 p]-ATP) has been widely used in the biotechnology research, usually as a tracer to study aspects of physiological and pathological processes. In order to support biotechnology research in Indonesia, a process for production of [γ- 32 P]-ATP with enzymatic reaction was used as precursors DL-glyceraldehydde 3-phosphate, Adenosine Diphosphate (ADP) and H 3 32 PO 4 , and enzyme glyceraldehid 3-phosphate dehydrogenase, 3-phosphoglyceryc phosphokinase and lactate dehydrogenase. Optimization of incubation time labeled nucleotide synthesis process is performed to find the optimum conditions, in terms of the most advantageous time in the synthesis process. With the success of the synthesis and optimization is done incubation time of synthesis labeled nucleotide, the result suggested can be used for producing [γ- 32 P] -ATP to support the provision of radiolabeled nucleotide for biotechnology research in Indonesia. (author)

Stoichiometry of ATP hydrolysis and chlorophyllide formation of dark-operative protochlorophyllide oxidoreductase from Rhodobacter capsulatus

Energy Technology Data Exchange (ETDEWEB)

Nomata, Jiro [Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan); Terauchi, Kazuki [Department of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577 (Japan); Fujita, Yuichi, E-mail: fujita@agr.nagoya-u.ac.jp [Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan)

2016-02-12

Dark-operative protochlorophyllide (Pchlide) oxidoreductase (DPOR) is a nitrogenase-like enzyme catalyzing a reduction of the C17 = C18 double bond of Pchlide to form chlorophyllide a (Chlide) in bacteriochlorophyll biosynthesis. DPOR consists of an ATP-dependent reductase component, L-protein (a BchL dimer), and a catalytic component, NB-protein (a BchN–BchB heterotetramer). The L-protein transfers electrons to the NB-protein to reduce Pchlide, which is coupled with ATP hydrolysis. Here we determined the stoichiometry of ATP hydrolysis and the Chlide formation of DPOR. The minimal ratio of ATP to Chlide (ATP/2e{sup –}) was 4, which coincides with that of nitrogenase. The ratio increases with increasing molar ratio of L-protein to NB-protein. This profile differs from that of nitrogenase. These results suggest that DPOR has a specific intrinsic property, while retaining the common features shared with nitrogenase. - Highlights: • The stoichiometry of nitrogenase-like protochlorophyllide reductase was determined. • The minimal ATP/2e{sup –} ratio was 4, which coincides with that of nitrogenase. • The ATP/2e{sup –} ratio increases with increasing L-protein/NB-protein molar ratio. • DPOR has an intrinsic property, but retains features shared with nitrogenase.

The thermodynamic efficiency of ATP synthesis in oxidative phosphorylation.

Science.gov (United States)

Nath, Sunil

2016-12-01

As the chief energy source of eukaryotic cells, it is important to determine the thermodynamic efficiency of ATP synthesis in oxidative phosphorylation (OX PHOS). Previous estimates of the thermodynamic efficiency of this vital process have ranged from Lehninger's original back-of-the-envelope calculation of 38% to the often quoted value of 55-60% in current textbooks of biochemistry, to high values of 90% from recent information theoretic considerations, and reports of realizations of close to ideal 100% efficiencies by single molecule experiments. Hence this problem has been reinvestigated from first principles. The overall thermodynamic efficiency of ATP synthesis in the mitochondrial energy transduction OX PHOS process has been found to lie between 40 and 41% from four different approaches based on a) estimation using structural and biochemical data, b) fundamental nonequilibrium thermodynamic analysis, c) novel insights arising from Nath's torsional mechanism of energy transduction and ATP synthesis, and d) the overall balance of cellular energetics. The torsional mechanism also offers an explanation for the observation of a thermodynamic efficiency approaching 100% in some experiments. Applications of the unique, molecular machine mode of functioning of F 1 F O -ATP synthase involving direct inter-conversion of chemical and mechanical energies in the design and fabrication of novel, man-made mechanochemical devices have been envisaged, and some new ways to exorcise Maxwell's demon have been proposed. It is hoped that analysis of the fundamental problem of energy transduction in OX PHOS from a fresh perspective will catalyze new avenues of research in this interdisciplinary field. Copyright © 2016 Elsevier B.V. All rights reserved.

Ballast water compliance monitoring: A new application for ATP

Science.gov (United States)

Lo Curto, A.; Stehouwer, P.; Gianoli, C.; Schneider, G.; Raymond, M.; Bonamin, V.

2018-03-01

The coming into force of the USCG ballast water regulations and the IMO ballast water management convention resulted in the development of several technologies approved for the treatment of ballast water. To ensure compliance of these technologies, the development of rapid and robust analysis methods was necessary. In collaboration with the SGS Group (Switzerland) and LuminUltra (Canada), Aqua-tools (France) has developed an innovative Ballast Water Treatment Monitoring (BWTM) kit for rapid onboard testing. The affordable kit provides results in less than 1 h, is easy to use and durable ensuring that the ballast water treatment system on the ship is fully compliant with the discharge standards upon arrival in port. The core of this method is a combination of high-quality reagents (lysis solution and ATP 2G Luminase™ enzyme) not inhibited by salinity and a patented fast homogenizing method for ATP extraction developed for a higher ATP recovery from zooplankton and phytoplankton. Compared to traditional analysis methods, the BWTM Kit provides fast and accurate results for all three fractions of microorganisms (≥ 50 μm, ≥ 10 ÷ < 50 μm and bacteria). Preliminary tests carried out in cooperation with SGS showed that the proposed method was able to detect onboard the efficiency of the treatment systems used. Compliance limits were established for all size fractions and a correlation between the standard methods (microscopy, plate count, MPN) and ATP was evaluated. The BWTM kit can provide a fast indication of compliance or gross exceedance. The rare borderline cases, when encountered, of course require additional confirmation.

Diversity and regulation of ATP sulfurylase in photosynthetic organisms

Directory of Open Access Journals (Sweden)

Laura ePrioretti

2014-11-01

Full Text Available ATP sulfurylase (ATPS catalyzes the first committed step in the sulfate assimilation pathway, the activation of sulfate prior to its reduction. ATPS has been studied in only a few model organisms and even in these cases to a much smaller extent than the sulfate reduction and cysteine synthesis enzymes. This is possibly because the latter were considered of greater regulatory importance for sulfate assimilation. Recent evidences (reported in this paper challenge this view and suggest that ATPSes may have a crucial regulatory role in sulfate assimilation, at least in algae.In the ensuing text, we summarize the current knowledge on ATPS, with special attention to the processes that control its activity and gene(s expression. Special attention is given to algae ATPSes. The focus on algae is the consequence of the fact that a comprehensive investigation of ATPSes revealed that the algal enzymes, especially those that are most likely involved in the pathway of sulfate reduction to cysteine, possess features that are not present in other organisms. For instance, algae ATPSes show a great diversity of isoforms and a high content of cysteine residues, whose positions are often conserved. It is interesting that, at least with respect to the number of cysteines, the ATPSes of eukaryotic algae are closer to the marine cyanobacteria of the genera Synechococcus and Prochlorococcus and are more distant from freshwater cyanobacteria. These characteristics might have evolved in parallel with the radiation of algae in the oceans and the increase of sulfate concentration in seawater.

Coupling of kinesin ATP turnover to translocation and microtubule regulation: one engine, many machines.

Science.gov (United States)

Friel, Claire T; Howard, Jonathon

2012-12-01

The cycle of ATP turnover is integral to the action of motor proteins. Here we discuss how variation in this cycle leads to variation of function observed amongst members of the kinesin superfamily of microtubule associated motor proteins. Variation in the ATP turnover cycle among superfamily members can tune the characteristic kinesin motor to one of the range of microtubule-based functions performed by kinesins. The speed at which ATP is hydrolysed affects the speed of translocation. The ratio of rate constants of ATP turnover in relation to association and dissociation from the microtubule influence the processivity of translocation. Variation in the rate-limiting step of the cycle can reverse the way in which the motor domain interacts with the microtubule producing non-motile kinesins. Because the ATP turnover cycle is not fully understood for the majority of kinesins, much work remains to show how the kinesin engine functions in such a wide variety of molecular machines.

Application of firefly luciferase assay for adenosine triphosphate (ATP) to antimicrobial drug sensitivity testing

Science.gov (United States)

Picciolo, G. L.; Tuttle, S. A.; Schrock, C. G.; Deming, J. W.; Barza, M. J.; Wienstein, L.; Chappelle, E. W.

1977-01-01

The development of a rapid method for determining microbial susceptibilities to antibiotics using the firefly luciferase assay for adenosine triphosphate (ATP) is documented. The reduction of bacterial ATP by an antimicrobial agent was determined to be a valid measure of drug effect in most cases. The effect of 12 antibiotics on 8 different bacterial species gave a 94 percent correlation with the standard Kirby-Buer-Agar disc diffusion method. A 93 percent correlation was obtained when the ATP assay method was applied directly to 50 urine specimens from patients with urinary tract infections. Urine samples were centrifuged first to that bacterial pellets could be suspended in broth. No primary isolation or subculturing was required. Mixed cultures in which one species was predominant gave accurate results for the most abundant organism. Since the method is based on an increase in bacterial ATP with time, the presence of leukocytes did not interfere with the interpretation of results. Both the incubation procedure and the ATP assays are compatible with automation.

Interlaboratory comparison of red-cell ATP, 2,3-diphosphoglycerate and haemolysis measurements.

Science.gov (United States)

Hess, J R; Kagen, L R; van der Meer, P F; Simon, T; Cardigan, R; Greenwalt, T J; AuBuchon, J P; Brand, A; Lockwood, W; Zanella, A; Adamson, J; Snyder, E; Taylor, H L; Moroff, G; Hogman, C

2005-07-01

Red blood cell (RBC) storage systems are licensed based on their ability to prevent haemolysis and maintain RBC 24-h in vivo recovery. Preclinical testing includes measurement of RBC ATP as a surrogate for recovery, 2,3-diphosphoglycerate (DPG) as a surrogate for oxygen affinity, and free haemoglobin, which is indicative of red cell lysis. The reproducibility of RBC ATP, DPG and haemolysis measurements between centres was investigated. Five, 4-day-old leucoreduced AS-1 RBC units were pooled, aliquotted and shipped on ice to 14 laboratories in the USA and European Union (EU). Each laboratory was to sample the bag twice on day 7 and measure RBC ATP, DPG, haemoglobin and haemolysis levels in triplicate on each sample. The variability of results was assessed by using coefficients of variation (CV) and analysis of variance. Measurements were highly reproducible at the individual sites. Between sites, the CV was 16% for ATP, 35% for DPG, 2% for total haemoglobin and 54% for haemolysis. For ATP and total haemoglobin, 94 and 80% of the variance in measurements was contributed by differences between sites, and more than 80% of the variance for DPG and haemolysis measurements came from markedly discordant results from three sites and one site, respectively. In descending order, mathematical errors, unvalidated analytical methods, a lack of shared standards and fluid handling errors contributed to the variability in measurements from different sites. While the methods used by laboratories engaged in RBC storage system clinical trials demonstrated good precision, differences in results between laboratories may hinder comparative analysis. Efforts to improve performance should focus on developing robust methods, especially for measuring RBC ATP.

Optimum ratio of AET, ATP and serotonin applied in combinations determined with a reference to their toxicity

International Nuclear Information System (INIS)

Benova, D.K.; P''tev, I.Kh.

1985-01-01

In experiments on mice, a study was made of the quantitative dependence of toxicity of AET, ATP and serotonin applied in combinations. The toxicity decreased when ATP was combined with AET and increased when ATP of AET were combined with serotonin. The toxicity of a combination of all three substances was reduced by introducing high doses of ATP

Radioprotective effectiveness and toxicity of ATP, AET and serotonin applied individually or simultaneously to mice. Pt. 4

International Nuclear Information System (INIS)

Benova, D.K.; Putev, I.K.

1979-01-01

Interactions occuring between three drugs - AET, serotonin, and ATP - in simultaneous administration were studied quantitatively. Using isobologram techniques, paired drug combination were examined for synergism in protective action against radiation. For ATP+AET pairs, increase in ATP fraction enhanced protection. For ATP+serotonin pairs, peak effect was observed at 360 mg/kg b.w. of ATP and 12 mg/kg b.w. of serotonin. Higher ATP fractions lowered the effectiveness. The highest degree of synergism was found for AET+serotonin, with peak effect at 17 to 33 mg/kg of AET plus 11 to 7 mg/kg of serotonin. By applying a method specially elaborated to enable prediction of interactions between three drugs administered simultaneously and by making use of three-dimensional diagrams, the parts played by individual components of triple combinations in total effect were estimated and the component dose ratio providing maximum protection identified. The determining components in protection were found to be AET and serotonin, the latter being of greater importance. The rhole of ATP in total effect is small and enhancement may be noted only up to ATP doses of no more than 156 mg/kg. The maximum effectiveness dose ratio of serotonin:AET:ATP was identified as 1:2:7.5-9. (orig.) [de

The utilization of adenosine triphosphate in rat mast cells during histamine release induced by anaphylactic reaction and compound 48/80

DEFF Research Database (Denmark)

Johansen, Torben; Chakravarty, N

1975-01-01

of ATP synthesis while a large part of the histamine release remained unaffected-a decrease in the ATP content could be demonstrated in close time relation to both anaphylactic and compound 48/80-induced histamine release. The observations indicate an increased utilization of ATP in mast cells during...

Gene knockout of the KCNJ8-encoded Kir6.1 K(ATP) channel imparts fatal susceptibility to endotoxemia.

Science.gov (United States)

Kane, Garvan C; Lam, Chen-Fuh; O'Cochlain, Fearghas; Hodgson, Denice M; Reyes, Santiago; Liu, Xiao-Ke; Miki, Takashi; Seino, Susumu; Katusic, Zvonimir S; Terzic, Andre

2006-11-01

Sepsis, the systemic inflammatory response to infection, imposes a high demand for bodily adaptation, with the cardiovascular response a key determinant of outcome. The homeostatic elements that secure cardiac tolerance in the setting of the sepsis syndrome are poorly understood. Here, in a model of acute septic shock induced by endotoxin challenge with Escherichia coli lipopolysaccharide (LPS), knockout of the KCNJ8 gene encoding the vascular Kir6.1 K(ATP) channel pore predisposed to an early and profound survival disadvantage. The exaggerated susceptibility provoked by disruption of this stress-responsive sensor of cellular metabolism was linked to progressive deterioration in cardiac activity, ischemic myocardial damage, and contractile dysfunction. Deletion of KCNJ8 blunted the responsiveness of coronary vessels to cytokine- or metabolic-mediated vasodilation necessary to support myocardial perfusion in the wild-type (WT), creating a deficit in adaptive response in the Kir6.1 knockout. Application of a K(ATP) channel opener drug improved survival in the endotoxic WT but had no effect in the Kir6.1 knockout. Restoration of the dilatory capacity of coronary vessels was required to rescue the Kir6.1 knockout phenotype and reverse survival disadvantage in lethal endotoxemia. Thus, the Kir6.1-containing K(ATP) channel, by coupling vasoreactivity with metabolic demand, provides a vital feedback element for cardiovascular tolerance in endotoxic shock.

Real time imaging of live cell ATP leaking or release events by chemiluminescence microscopy

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yun [Iowa State Univ., Ames, IA (United States)

2008-12-18

The purpose of this research was to expand the chemiluminescence microscopy applications in live bacterial/mammalian cell imaging and to improve the detection sensitivity for ATP leaking or release events. We first demonstrated that chemiluminescence (CL) imaging can be used to interrogate single bacterial cells. While using a luminometer allows detecting ATP from cell lysate extracted from at least 10 bacterial cells, all previous cell CL detection never reached this sensitivity of single bacteria level. We approached this goal with a different strategy from before: instead of breaking bacterial cell membrane and trying to capture the transiently diluted ATP with the firefly luciferase CL assay, we introduced the firefly luciferase enzyme into bacteria using the modern genetic techniques and placed the CL reaction substrate D-luciferin outside the cells. By damaging the cell membrane with various antibacterial drugs including antibiotics such as Penicillins and bacteriophages, the D-luciferin molecules diffused inside the cell and initiated the reaction that produces CL light. As firefly luciferases are large protein molecules which are retained within the cells before the total rupture and intracellular ATP concentration is high at the millmolar level, the CL reaction of firefly luciferase, ATP and D-luciferin can be kept for a relatively long time within the cells acting as a reaction container to generate enough photons for detection by the extremely sensitive intensified charge coupled device (ICCD) camera. The result was inspiring as various single bacterium lysis and leakage events were monitored with 10-s temporal resolution movies. We also found a new way of enhancing diffusion D-luciferin into cells by dehydrating the bacteria. Then we started with this novel single bacterial CL imaging technique, and applied it for quantifying gene expression levels from individual bacterial cells. Previous published result in single cell gene expression quantification

Acid phosphates response in murine rhabdomyosarcoma for various tumour volumes and after different doses of neutron irradiation, alone or combined with exogenous ATP

International Nuclear Information System (INIS)

Szeinfeld, D.; De Villiers, N.

1991-01-01

Acid phosphatase activity measured in a methylocholanthrene-induced murine rhabdomyosarcoma showed a monotonically increasing relation between enzyme activity and tumour volume. This could be related to the lytic activity of the enzyme in large tumours which become more hypoxic and necrotic, and hence enhance degradation and turnover of damaged tumour cells. The tumours were also subjected to irradiation using doses of 2.0, 3.8 and 6.0 Gy from a neutron therapy facility p(66 MeV)/Be. The correlation between different doses and response of acid phosphatase activity could reflect the relation of magnitude of damage from metabolic disturbances, with dose. Furthermore exogenous ATP was shown to provide radioprotective action against neutron irradiation in two different experiments. The ATP reduced the activity of this lytic enzyme in irradiated tumours and also decreased tumour growth delay. This radioprotective role of exogenous ATP in a murine tumour could be related to physiological regulatory processes during defence mechanisms to maintain self-organisation in response to the radiation damage. (orig.) [de

Opposite effect of ATP on contraction force of tonic and phasic skeletal muscles in frogs.

Science.gov (United States)

Grishin, S N; Kamaliev, R R; Teplov, A Yu; Ziganshin, A U

2011-07-01

Experiments in vitro showed that ATP and adenosine equally suppressed contractions of frog m. sartorius, which belongs to the phasic type muscles. Adenosine receptors antagonist 8-SPT abolished the effect of adenosine, but did not change the effect of ATP. This fact proves the independence of signaling pathways of these purines. ATP produced an opposite effect on the tonic muscle m. cruralis and increased the force of its contraction. Adenosine produced an inhibitory effect on the force of m. cruralis contration. In this case, 8-SPT also eliminated the effect of adenosine, but did not change the effect of ATP. The potentiating effect of ATP was blocked by suramin, a nonselective antagonist of P2 receptors, which attests to their involvement into the effects of this purine. The opposite effects of purinergic regulation reflect fundamental differences in functional organization of phasic and tonic muscular systems. It was hypothesized that the increase in contraction force under the effect of ATP is a mechanism providing maitenance of the contracted state of tonic muscle without appreciable metabolic costs.