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Sample records for acid receptors rars

  1. A mollusk retinoic acid receptor (RAR) ortholog sheds light on the evolution of ligand binding.

    Gutierrez-Mazariegos, Juliana; Nadendla, Eswar Kumar; Lima, Daniela; Pierzchalski, Keely; Jones, Jace W; Kane, Maureen; Nishikawa, Jun-Ichi; Hiromori, Youhei; Nakanishi, Tsuyoshi; Santos, Miguel M; Castro, L Filipe C; Bourguet, William; Schubert, Michael; Laudet, Vincent

    2014-11-01

    Nuclear receptors are transcription factors that regulate networks of target genes in response to small molecules. There is a strong bias in our knowledge of these receptors because they were mainly characterized in classical model organisms, mostly vertebrates. Therefore, the evolutionary origins of specific ligand-receptor couples still remain elusive. Here we present the identification and characterization of a retinoic acid receptor (RAR) from the mollusk Nucella lapillus (NlRAR). We show that this receptor specifically binds to DNA response elements organized in direct repeats as a heterodimer with retinoid X receptor. Surprisingly, we also find that NlRAR does not bind all-trans retinoic acid or any other retinoid we tested. Furthermore, NlRAR is unable to activate the transcription of reporter genes in response to stimulation by retinoids and to recruit coactivators in the presence of these compounds. Three-dimensional modeling of the ligand-binding domain of NlRAR reveals an overall structure that is similar to vertebrate RARs. However, in the ligand-binding pocket (LBP) of the mollusk receptor, the alteration of several residues interacting with the ligand has apparently led to an overall decrease in the strength of the interaction with the ligand. Accordingly, mutations of NlRAR at key positions within the LBP generate receptors that are responsive to retinoids. Altogether our data suggest that, in mollusks, RAR has lost its affinity for all-trans retinoic acid, highlighting the evolutionary plasticity of its LBP. When put in an evolutionary context, our results reveal new structural and functional features of nuclear receptors validated by millions of years of evolution that were impossible to reveal in model organisms. PMID:25116705

  2. Improvement in Aqueous Solubility of Retinoic Acid Receptor (RAR) Agonists by Bending the Molecular Structure.

    Hiramatsu, Michiaki; Ichikawa, Yuki; Tomoshige, Shusuke; Makishima, Makoto; Muranaka, Atsuya; Uchiyama, Masanobu; Yamaguchi, Takao; Hashimoto, Yuichi; Ishikawa, Minoru

    2016-08-01

    Aqueous solubility is a key requirement for many functional molecules, e. g., drug candidates. Decrease of the partition coefficient (log P) by chemical modification, i.e., introduction of hydrophilic group(s) into molecules, is a classical strategy for improving aqueous solubility. We have been investigating alternative strategies for improving the aqueous solubility of pharmaceutical compounds by disrupting intermolecular interactions. Here, we show that introducing a bend into the molecular structure of retinoic acid receptor (RAR) agonists by changing the substitution pattern from para to meta or ortho dramatically enhances aqueous solubility by up to 890-fold. We found that meta analogs exhibit similar hydrophobicity to the parent para compound, and have lower melting points, supporting the idea that the increase of aqueous solubility was due to decreased intermolecular interactions in the solid state as a result of the structural changes. PMID:27378357

  3. Expression of a retinoic acid receptor (RAR)-like protein in the embryonic and adult nervous system of a protostome species.

    Carter, Christopher J; Rand, Christopher; Mohammad, Imtiaz; Lepp, Amanda; Vesprini, Nicholas; Wiebe, Olivia; Carlone, Robert; Spencer, Gaynor E

    2015-01-01

    The vitamin A metabolite, retinoic acid, is an important molecule in nervous system development and regeneration in vertebrates. Retinoic acid signaling in vertebrates is mediated by two classes of nuclear receptors, the retinoid X receptors (RXRs) and the retinoic acid receptors (RARs). Recently, evidence has emerged to suggest that many effects of retinoic acid are conserved between vertebrate and invertebrate nervous systems, even though the RARs were previously thought to be a vertebrate innovation and to not exist in non-chordates. We have cloned a full-length putative RAR from the CNS of the mollusc Lymnaea stagnalis (LymRAR). Immunoreactivity for the RAR protein was found in axons of adult neurons in the central nervous system and in growth cones of regenerating neurons in vitro. A vertebrate RAR antagonist blocked growth cone turning induced by exogenous all-trans retinoic acid, possibly suggesting a role for this receptor in axon guidance. We also provide immunostaining evidence for the presence of RAR protein in the developing, embryonic CNS, where it is also found in axonal processes. Using qPCR, we determined that LymRAR mRNA is detectable in the early veliger stage embryo and that mRNA levels increase significantly during embryonic development. Putative disruption of retinoid signaling in Lymnaea embryos using vertebrate RAR antagonists resulted in abnormal eye and shell development and in some instances completely halted development, resembling the effects of all-trans retinoic acid. This study provides evidence for RAR functioning in a protostome species. PMID:25504929

  4. Retinoids induce integrin-independent lymphocyte adhesion through RAR-α nuclear receptor activity

    Highlights: • Transcription and translation are required for retinoid-induced lymphocyte adhesion. • RAR activation is sufficient to induced lymphocyte cell adhesion. • Vitamin D derivatives inhibit RAR-prompted lymphocyte adhesion. • Adhesion occurs through a novel binding site within ADAM disintegrin domains. • RARα is a key nuclear receptor for retinoid-dependent lymphocyte cell adhesion. - Abstract: Oxidative metabolites of vitamin A, in particular all-trans-retinoic acid (atRA), have emerged as key factors in immunity by specifying the localization of immune cells to the gut. Although it is appreciated that isomers of retinoic acid activate the retinoic acid receptor (RAR) and retinoid X receptor (RXR) family of nuclear receptors to elicit cellular changes, the molecular details of retinoic acid action remain poorly defined in immune processes. Here we employ a battery of agonists and antagonists to delineate the specific nuclear receptors utilized by retinoids to evoke lymphocyte cell adhesion to ADAM (adisintegrin and metalloprotease) protein family members. We report that RAR agonism is sufficient to promote immune cell adhesion in both immortal and primary immune cells. Interestingly, adhesion occurs independent of integrin function, and mutant studies demonstrate that atRA-induced adhesion to ADAM members required a distinct binding interface(s) as compared to integrin recognition. Anti-inflammatory corticosteroids as well as 1,25-(OH)2D3, a vitamin D metabolite that prompts immune cell trafficking to the skin, potently inhibited the observed adhesion. Finally, our data establish that induced adhesion was specifically attributable to the RARreceptor isotype. The current study provides novel molecular resolution as to which nuclear receptors transduce retinoid exposure into immune cell adhesion

  5. Retinoids induce integrin-independent lymphocyte adhesion through RAR-α nuclear receptor activity

    Whelan, Jarrett T.; Wang, Lei; Chen, Jianming; Metts, Meagan E.; Nasser, Taj A.; McGoldrick, Liam J. [Department of Biochemistry and Molecular Biology, The Brody School of Medicine at East Carolina University, Greenville, NC 27834 (United States); Bridges, Lance C., E-mail: bridgesl@ecu.edu [Department of Biochemistry and Molecular Biology, The Brody School of Medicine at East Carolina University, Greenville, NC 27834 (United States); East Carolina Diabetes and Obesity Institute, The Brody School of Medicine at East Carolina University, Greenville, NC 27834 (United States)

    2014-11-28

    Highlights: • Transcription and translation are required for retinoid-induced lymphocyte adhesion. • RAR activation is sufficient to induced lymphocyte cell adhesion. • Vitamin D derivatives inhibit RAR-prompted lymphocyte adhesion. • Adhesion occurs through a novel binding site within ADAM disintegrin domains. • RARα is a key nuclear receptor for retinoid-dependent lymphocyte cell adhesion. - Abstract: Oxidative metabolites of vitamin A, in particular all-trans-retinoic acid (atRA), have emerged as key factors in immunity by specifying the localization of immune cells to the gut. Although it is appreciated that isomers of retinoic acid activate the retinoic acid receptor (RAR) and retinoid X receptor (RXR) family of nuclear receptors to elicit cellular changes, the molecular details of retinoic acid action remain poorly defined in immune processes. Here we employ a battery of agonists and antagonists to delineate the specific nuclear receptors utilized by retinoids to evoke lymphocyte cell adhesion to ADAM (adisintegrin and metalloprotease) protein family members. We report that RAR agonism is sufficient to promote immune cell adhesion in both immortal and primary immune cells. Interestingly, adhesion occurs independent of integrin function, and mutant studies demonstrate that atRA-induced adhesion to ADAM members required a distinct binding interface(s) as compared to integrin recognition. Anti-inflammatory corticosteroids as well as 1,25-(OH){sub 2}D{sub 3}, a vitamin D metabolite that prompts immune cell trafficking to the skin, potently inhibited the observed adhesion. Finally, our data establish that induced adhesion was specifically attributable to the RARreceptor isotype. The current study provides novel molecular resolution as to which nuclear receptors transduce retinoid exposure into immune cell adhesion.

  6. Activation of Nuclear Receptors RAR, RXR, and LXR Does Not Reduce Cuprizone-Induced Demyelination in Mice

    Davina Kruczek; Tim Clarner; Cordian Beyer; Markus Kipp; Jörg Mey

    2015-01-01

    Experiments with animal models of multiple sclerosis have shown that the expression of retinoid X receptors (RXR) increases during demyelination and that RXR is involved in the regulation of remyelination. After ligand binding RXRs form heterodimeric transcription factors with other nuclear receptor (NR) families including the retinoic acid receptors (RAR) and liver X receptors (LXR). We tested whether activation of these nuclear receptor complexes reduces pathological demyelination using the...

  7. Activation of Nuclear Receptors RAR, RXR, and LXR Does Not Reduce Cuprizone-Induced Demyelination in Mice

    Davina Kruczek

    2015-06-01

    Full Text Available Experiments with animal models of multiple sclerosis have shown that the expression of retinoid X receptors (RXR increases during demyelination and that RXR is involved in the regulation of remyelination. After ligand binding RXRs form heterodimeric transcription factors with other nuclear receptor (NR families including the retinoic acid receptors (RAR and liver X receptors (LXR. We tested whether activation of these nuclear receptor complexes reduces pathological demyelination using the cuprizone mouse model. Cuprizone, which causes oligodendrocyte degeneration, was given for three weeks as a food additive. For the activation of nuclear receptors mice were treated with daily i.p. injections of agonists for RXR (9-cis RA, RAR (all-trans RA, and LXR (T0901317. Myelin status, oligodendrocyte survival, astrogliosis, microglial activation, and axon density were monitored with immunohistochemistry and evaluated quantitatively. Three weeks of cuprizone feeding caused severe demyelination and significantly raised the number of Iba1 immunoreactive microglia cells in the caudal corpus callosum. This increase of microglia activity was reduced with 9-cis RA treatment but was enhanced with all-trans RA and was not affected by T0901317. Nuclear receptor activation did not influence the degree of demyelination, oligodendrocyte survival, astrogliosis, or axonal preservation. We conclude that RXR activation, although affecting Iba1-positive microglia, does not protect oligodendrocytes from cuprizone toxicity and does not induce compensatory mechanisms in the initial phase of demyelination.

  8. Neofunctionalization in vertebrates: the example of retinoic acid receptors.

    Hector Escriva

    2006-07-01

    Full Text Available Understanding the role of gene duplications in establishing vertebrate innovations is one of the main challenges of Evo-Devo (evolution of development studies. Data on evolutionary changes in gene expression (i.e., evolution of transcription factor-cis-regulatory elements relationships tell only part of the story; protein function, best studied by biochemical and functional assays, can also change. In this study, we have investigated how gene duplication has affected both the expression and the ligand-binding specificity of retinoic acid receptors (RARs, which play a major role in chordate embryonic development. Mammals have three paralogous RAR genes--RAR alpha, beta, and gamma--which resulted from genome duplications at the origin of vertebrates. By using pharmacological ligands selective for specific paralogues, we have studied the ligand-binding capacities of RARs from diverse chordates species. We have found that RAR beta-like binding selectivity is a synapomorphy of all chordate RARs, including a reconstructed synthetic RAR representing the receptor present in the ancestor of chordates. Moreover, comparison of expression patterns of the cephalochordate amphioxus and the vertebrates suggests that, of all the RARs, RAR beta expression has remained most similar to that of the ancestral RAR. On the basis of these results together, we suggest that while RAR beta kept the ancestral RAR role, RAR alpha and RAR gamma diverged both in ligand-binding capacity and in expression patterns. We thus suggest that neofunctionalization occurred at both the expression and the functional levels to shape RAR roles during development in vertebrates.

  9. THE CORRELATIONS OF RETINOIC ACID RECEPTOR-α AND ESTROGEN RECEPTOR EXPRESSION IN HUMAN BREAST CANCER CELL LINES AND TUMORS

    余黎明; 邵志敏; 蔡三军; 韩企夏; 沈镇宙

    1998-01-01

    Retinoic acid receptor-α(RAR α) plays a major role in the growth inhibitory effect of retinoic acid on human breast cancer ceils, may be it could serve as an indicator to guide the treatment and prevent of breast cancer with retinoic acid in ciiinc. All previous researchs were based on observing the changes ofRAR a mRAN expression. In this study, the expression of RAR a in human breast cell lines was studied by Northern Blot, Western Blot and Immunohistochemistry in mRNA level and protein level. Results showed that RAR a protein expression was correlated with RAR a mRNA expression. RAR α mRNA expression was higher in estrogen receptor (ER)-positive human breast cancer cell lines than in ER-negative ones. So was RAR α protein expression. Both RAR α mRNA amd RAR α protein expression were associated with ER status. The expression of RAR α and the relationship between RAR α and ER status were also determined by immunohistochemistry in 58 human primary breast cancer tumors. 37 (63.8%) tumors were ER-positive and of these 28 (75. 7%) were also RAR α -positive. The coexpression of ER and RAR α was statistleally significant (P<0. 01, by X2 contingency analysis), It was reported that RAR α expression in cultured breast cancer ceils was regulated by estrogen acting via the ER. Our study demonstrated that RAR α expression may be modulated in breast cancer in vivo by estrogen via ER.

  10. Structure-dependent activities of polybrominated diphenyl ethers and hydroxylated metabolites on zebrafish retinoic acid receptor.

    Zhao, Jing; Zhu, Xiangwei; Xu, Ting; Yin, Daqiang

    2015-02-01

    Polybrominated diphenyl ethers (PBDEs), a group of potential endocrine-disrupting chemicals (EDCs) have been shown to disrupt retinoid homeostasis in different species in both laboratory and field studies. However, the molecular mechanisms of interactions with the retinoic acid receptor (RAR) are not fully understood. Zebrafish have proven useful for investigating mechanisms of chemical toxicity. In the present study, a reporter gene assay was used to investigate the activities of 11 PBDEs and six OH-PBDEs with different degrees of bromination on zebrafish RAR. All tested OH-PBDEs induced RAR transcriptional activity; however, of the 11 PBDEs examined, only BDE28 and BDE154 affected the RAR transcriptional activity. Homology modeling and molecular docking were employed to simulate the interactions of PBDEs/OH-PBDEs with zebrafish RARs and to identify binding affinities to analyze the specialization of the interaction between RARs and PBDEs/OH-PBDEs. The results showed that although these compounds could bind with RARs, the effects of PBDEs/OH-PBDEs on RAR transcriptional activity did not depend on their RAR-binding abilities. The present study is the first attempt to demonstrate that OH-PBDEs could induce RAR transcriptional activity by binding directly with RAR; these effects are possibly related to the structure of the compounds, especially their hydroxylation and bromination. Most of the PBDEs could not directly interact with the RAR. PMID:25077655

  11. REACTIVITY PROFILE OF LIGANDS OF MAMMALIAN RETINOIC ACID RECEPTORS: A PRELIMINARY COREPA ANALYSIS

    Retinoic acid and associated derivatives comprise a class of endogenous hormones that bind to and activate different families of retinoic acid receptors (RARs, RXRs), and control many aspects of vertebrate development. Identification of potential RAR and RXR ligands is of interes...

  12. TRANSCRIPTIONAL REGULATION OF RETINOIC ACID RECEPTOR-BETA IN RETINOIC ACID-SENSITIVE AND ACID-RESISTANT P19-EMBRYOCARCINOMA CELLS

    KRUYT, FAE; VANDENBRINK, CE; DEFIZE, LHK; DONATH, MJ; KASTNER, P; KRUIJER, W; CHAMBON, P; VANDERSAAG, PT; Kruyt, Frank

    1991-01-01

    As in other embryocarcinoma (EC) cell lines retinoic acid (RA) rapidly induces expression of the nuclear retinoic acid receptor (RAR) beta in murine P19 EC cells, while RAR-alpha is expressed constitutively. In the RA-resistant P19 EC-derived RAC65 cells, however, there is no such induction and an a

  13. Characterization of DNA Binding and Retinoic Acid Binding Properties of Retinoic Acid Receptor

    Yang, Na; Schule, Roland; Mangelsdorf, David J.; Evans, Ronald M.

    1991-05-01

    High-level expression of the full-length human retinoic acid receptor (RAR) α and the DNA binding domain of the RAR in Escherichia coli was achieved by using a T7 RNA polymerase-directed expression system. After induction, full-length RAR protein was produced at an estimated level of 20% of the total bacterial proteins. Both intact RAR molecules and the DNA binding domain bind to the cognate DNA response element with high specificity in the absence of retinoic acid. However, this binding is enhanced to a great extent upon the addition of eukaryotic cell extracts. The factor responsible for this enhancement is heat-sensitive and forms a complex with RAR that binds to DNA and exhibits a distinct migration pattern in the gel-mobility-shift assay. The interaction site of the factor with RAR is localized in the 70-amino acid DNA binding region of RAR. The hormone binding ability of the RARα protein was assayed by a charcoal absorption assay and the RAR protein was found to bind to retinoic acid with a K_d of 2.1 x 10-10 M.

  14. RXR alpha, a promiscuous partner of retinoic acid and thyroid hormone receptors.

    Bugge, T H; Pohl, J.; Lonnoy, O; Stunnenberg, H G

    1992-01-01

    Retinoic acid receptor (RAR), thyroid hormone receptor (T3R) and vitamin D3 receptor (VD3R) differ from steroid hormone receptors in that they bind and transactivate through responsive elements organized as direct rather than inverted repeats. We now show that recombinant RAR and T3R are monomers in solution and cannot form stable homodimeric complexes on their responsive elements. Stable binding of the receptors to their responsive elements requires heterodimerization with a nuclear factor. ...

  15. In silico discovery of novel Retinoic Acid Receptor agonist structures

    Samuels Herbert H; Schapira Matthieu; Raaka Bruce M; Abagyan Ruben

    2001-01-01

    Abstract Background Several Retinoic Acid Receptors (RAR) agonists have therapeutic activity against a variety of cancer types; however, unacceptable toxicity profiles have hindered the development of drugs. RAR agonists presenting novel structural and chemical features could therefore open new avenues for the discovery of leads against breast, lung and prostate cancer or leukemia. Results We have analysed the induced fit of the active site residues upon binding of a known ligand. The derived...

  16. Evolution of retinoic acid receptors and retinoic acid signaling.

    Gutierrez-Mazariegos, Juliana; Schubert, Michael; Laudet, Vincent

    2014-01-01

    Retinoic acid (RA) is a vitamin A-derived morphogen controlling important developmental processes in vertebrates, and more generally in chordates, including axial patterning and tissue formation and differentiation. In the embryo, endogenous RA levels are controlled by RA synthesizing and degrading enzymes and the RA signal is transduced by two retinoid receptors: the retinoic acid receptor (RAR) and the retinoid X receptor (RXR). Both RAR and RXR are members of the nuclear receptor superfamily of ligand-activated transcription factors and mainly act as heterodimers to activate the transcription of target genes in the presence of their ligand, all-trans RA. This signaling pathway was long thought to be a chordate innovation, however, recent findings of gene homologs involved in RA signaling in the genomes of a wide variety of non-chordate animals, including ambulacrarians (sea urchins and acorn worms) and lophotrochozoans (annelids and mollusks), challenged this traditional view and suggested that the RA signaling pathway might have a more ancient evolutionary origin than previously thought. In this chapter, we discuss the evolutionary history of the RA signaling pathway, and more particularly of the RARs, which might have experienced independent gene losses and duplications in different animal lineages. In sum, the available data reveal novel insights into the origin of the RA signaling pathway as well as into the evolutionary history of the RARs. PMID:24962881

  17. Immunohistochemical analysis of retinoic acid receptor-alpha in human breast tumors: retinoic acid receptor-alpha expression correlates with proliferative activity.

    van der Leede, B. M.; Geertzema, J.; Vroom, T. M.; Décimo, D.; Lutz, Y.; van der Saag, P. T.; van der Burg, B.

    1996-01-01

    Retinoids are known to prevent mammary carcinogenesis in rodents and inhibit the growth of human breast cancer cells in vitro. Previously we demonstrated that retinoid inhibition of proliferation of human breast cancer cell lines is largely mediated by retinoic acid receptor (RAR)-alpha. In this study we describe for the first time the histological distribution of RAR-alpha in 33 breast lesion specimens as determined by immunostaining with RAR-alpha antibody. Nuclear staining was observed in tumor tissue and normal portions of the breast samples. Connective tissue exhibited relative uniform staining, whereas a wide range of RAR-alpha expression was found in the epithelial tumor cells. RAR-alpha protein was expressed at significantly higher levels in tumors with greater proliferative activity as determined by immunostaining with Ki-67 antibody. This suggests that RAR-alpha expression may be altered with tumor progression. Although a positive correlation between RAR-alpha mRNA levels and estrogen receptor status of breast tumors has previously been documented, we did not find such a relationship at the protein level. As RAR-alpha plays a major role in retinoid-mediated growth inhibition of human breast cancer cell in vitro, our findings suggest that patients with highly proliferating tumors could be responsive to retinoid independently of their responsiveness to (anti)-estrogens. Images Figure 1 Figure 2 PMID:8669476

  18. ASXL1 Represses Retinoic Acid Receptor-mediated Transcription through Associating with HP1 and LSD1*

    Lee, Sang-Wang; Cho, Yang-Sook; Na, Jung-Min; Park, Ui-Hyun; Kang, Myengmo; Kim, Eun-Joo; Um, Soo-Jong

    2009-01-01

    We previously suggested that ASXL1 (additional sex comb-like 1) functions as either a coactivator or corepressor for the retinoid receptors retinoic acid receptor (RAR) and retinoid X receptor in a cell type-specific manner. Here, we provide clues toward the mechanism underlying ASXL1-mediated repression. Transfection assays in HEK293 or H1299 cells indicated that ASXL1 alone possessing autonomous transcriptional repression activity significantly represses RAR- or retinoid X receptor-dependen...

  19. Methylation and silencing of the retinoic acid receptor-β2 gene in cervical cancer

    Expression of the retinoic acid receptor β2 (RAR-β2), a putative tumor suppressor gene, is reduced in various human cancers, including squamous cell carcinomas (SCC) of the uterine cervix. The mechanism of the inhibition of RAR-β2 expression remains obscure. We examined whether methylation of RAR-β2 gene could be responsible for this silencing in cervical SCC. Expression of RAR-β2 mRNA and methylation status of the 5' region of RAR-β2 gene were examined in 20 matched specimens from patients with cervical SCC and in three cervical cancer cell lines by Northern blot analysis and methylation-specific PCR (MSP) assay or Southern blot analysis respectively. In 8 out 20 cervical SCC (40%) the levels of RAR-β2 mRNA were decreased or undetectable in comparison with non-neoplastic cervix tissues. All 8 tumors with reduced levels of RAR-β2 mRNA expression showed methylation of the promoter and the first exon expressed in the RAR-β2 transcript. The RAR-β2 gene from non-neoplastic cervical tissues was mostly unmethylated and expressed, but methylated alleles of the gene were found in three samples of the morphologically normal tissues adjacent to the tumors. Three cervical cancer cell lines with extremely low level of RAR-β2 mRNA expression, SiHA, HeLA and CaSki, also showed methylation of this region of the RAR-β2 gene. These findings suggest that methylation of the 5' region of RAR-β2 gene may contribute to gene silencing and that methylation of this region may be an important and early event in cervical carcinogenesis. These findings may be useful to make retinoids more effective as preventive and therapeutic agents in combination with inhibitors of DNA methylation

  20. Identification of a Novel Non-retinoid Pan Inverse Agonist of the Retinoic Acid Receptors

    Busby, Scott A.; Kumar, Naresh; Kuruvilla, Dana S.; Istrate, Monica A.; Conkright, Juliana J.; Wang, Yongjun; Kamenecka, Theodore M.; Cameron, Michael D.; Roush, William R.; Burris, Thomas P.; Griffin, Patrick R.

    2011-01-01

    Retinoids are potent forms of vitamin A and are involved in a broad range of physiological processes and the pharmacological effects of retinoids are primarily mediated by the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). Several natural and synthetic RAR modulators have proven to be clinically useful for a number of therapeutic indications including cancer, psoriasis, and diabetes. Unfortunately, these agents lead to a number of significant side effects. Most synthetic ...

  1. Evolution of retinoic acid receptors in chordates: insights from three lamprey species, Lampetra fluviatilis, Petromyzon marinus, and Lethenteron japonicum

    Campo-Paysaa, Florent; Jandzik, David; Takio-Ogawa, Yoko; Cattell, Maria V; Neef, Haley C; Langeland, James A.; Kuratani, Shigeru; Medeiros, Daniel M.; Mazan, Sylvie; Kuraku, Shigehiro; Laudet, Vincent; Schubert, Michael

    2015-01-01

    Background Retinoic acid (RA) signaling controls many developmental processes in chordates, from early axis specification to late organogenesis. The functions of RA are chiefly mediated by a subfamily of nuclear hormone receptors, the retinoic acid receptors (RARs), that act as ligand-activated transcription factors. While RARs have been extensively studied in jawed vertebrates (that is, gnathostomes) and invertebrate chordates, very little is known about the repertoire and developmental role...

  2. Direct Channeling of Retinoic Acid between Cellular Retinoic Acid-Binding Protein II and Retinoic Acid Receptor Sensitizes Mammary Carcinoma Cells to Retinoic Acid-Induced Growth Arrest

    Budhu, Anuradha S.; Noy, Noa

    2002-01-01

    Cellular retinoic acid-binding protein II (CRABP-II) is an intracellular lipid-binding protein that associates with retinoic acid with a subnanomolar affinity. We previously showed that CRABP-II enhances the transcriptional activity of the nuclear receptor with which it shares a common ligand, namely, the retinoic acid receptor (RAR), and we suggested that it may act by delivering retinoic acid to this receptor. Here, the mechanisms underlying the effects of CRABP-II on the transcriptional ac...

  3. Novel retinoic acid receptor ligands in Xenopus embryos.

    Blumberg, B; Bolado, J; Derguini, F; Craig, A G; Moreno, T A; Chakravarti, D; Heyman, R A; Buck, J.; Evans, R M

    1996-01-01

    Retinoids are a large family of natural and synthetic compounds related to vitamin A that have pleiotropic effects on body physiology, reproduction, immunity, and embryonic development. The diverse activities of retinoids are primarily mediated by two families of nuclear retinoic acid receptors, the RARs and RXRs. Retinoic acids are thought to be the only natural ligands for these receptors and are widely assumed to be the active principle of vitamin A. However, during an unbiased, bioactivit...

  4. RAR/RXR binding dynamics distinguish pluripotency from differentiation associated cis-regulatory elements.

    Chatagnon, Amandine; Veber, Philippe; Morin, Valérie; Bedo, Justin; Triqueneaux, Gérard; Sémon, Marie; Laudet, Vincent; d'Alché-Buc, Florence; Benoit, Gérard

    2015-05-26

    In mouse embryonic cells, ligand-activated retinoic acid receptors (RARs) play a key role in inhibiting pluripotency-maintaining genes and activating some major actors of cell differentiation. To investigate the mechanism underlying this dual regulation, we performed joint RAR/RXR ChIP-seq and mRNA-seq time series during the first 48 h of the RA-induced Primitive Endoderm (PrE) differentiation process in F9 embryonal carcinoma (EC) cells. We show here that this dual regulation is associated with RAR/RXR genomic redistribution during the differentiation process. In-depth analysis of RAR/RXR binding sites occupancy dynamics and composition show that in undifferentiated cells, RAR/RXR interact with genomic regions characterized by binding of pluripotency-associated factors and high prevalence of the non-canonical DR0-containing RA response element. By contrast, in differentiated cells, RAR/RXR bound regions are enriched in functional Sox17 binding sites and are characterized with a higher frequency of the canonical DR5 motif. Our data offer an unprecedentedly detailed view on the action of RA in triggering pluripotent cell differentiation and demonstrate that RAR/RXR action is mediated via two different sets of regulatory regions tightly associated with cell differentiation status. PMID:25897113

  5. Retinoic acid receptor subtype-specific transcriptotypes in the early zebrafish embryo.

    Samarut, Eric; Gaudin, Cyril; Hughes, Sandrine; Gillet, Benjamin; de Bernard, Simon; Jouve, Pierre-Emmanuel; Buffat, Laurent; Allot, Alexis; Lecompte, Odile; Berekelya, Liubov; Rochette-Egly, Cécile; Laudet, Vincent

    2014-02-01

    Retinoic acid (RA) controls many aspects of embryonic development by binding to specific receptors (retinoic acid receptors [RARs]) that regulate complex transcriptional networks. Three different RAR subtypes are present in vertebrates and play both common and specific roles in transducing RA signaling. Specific activities of each receptor subtype can be correlated with its exclusive expression pattern, whereas shared activities between different subtypes are generally assimilated to functional redundancy. However, the question remains whether some subtype-specific activity still exists in regions or organs coexpressing multiple RAR subtypes. We tackled this issue at the transcriptional level using early zebrafish embryo as a model. Using morpholino knockdown, we specifically invalidated the zebrafish endogenous RAR subtypes in an in vivo context. After building up a list of RA-responsive genes in the zebrafish gastrula through a whole-transcriptome analysis, we compared this panel of genes with those that still respond to RA in embryos lacking one or another RAR subtype. Our work reveals that RAR subtypes do not have fully redundant functions at the transcriptional level but can transduce RA signal in a subtype-specific fashion. As a result, we define RAR subtype-specific transcriptotypes that correspond to repertoires of genes activated by different RAR subtypes. Finally, we found genes of the RA pathway (cyp26a1, raraa) the regulation of which by RA is highly robust and can even resist the knockdown of all RARs. This suggests that RA-responsive genes are differentially sensitive to alterations in the RA pathway and, in particular, cyp26a1 and raraa are under a high pressure to maintain signaling integrity. PMID:24422634

  6. The molecular physiology of nuclear retinoic acid receptors. From health to disease.

    Duong, Vanessa; Rochette-Egly, Cécile

    2011-08-01

    The nuclear retinoic acid (RA) receptors (RARα, β and γ) are transcriptional transregulators, which control the expression of specific gene subsets subsequently to ligand binding and to strictly controlled phosphorylation processes. Consequently RARs maintain homeostasis through the control of cell proliferation and differentiation. Today, it is admitted that, analogous to the paradigm established by the hematopoietic system, most adult tissues depict a differentiation hierarchy starting from rare stem cells. Here we highlight that the integrity of RARs is absolutely required for homeostasis in adults. Indeed, strictly controlled levels of RARs are necessary for the correct balance between self-renewal and differentiation of tissue stem cells. In addition, loss, accumulation, mutations or aberrant modifications of a specific RAR lead to uncontrolled proliferation and/or to differentiation block and thereby to cancer. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease. PMID:20970498

  7. TRIM32 promotes retinoic acid receptor {alpha}-mediated differentiation in human promyelogenous leukemic cell line HL60

    Sato, Tomonobu [Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638 (Japan); Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo 060-8638 (Japan); Okumura, Fumihiko [Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638 (Japan); Iguchi, Akihiro; Ariga, Tadashi [Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo 060-8638 (Japan); Hatakeyama, Shigetsugu, E-mail: hatas@med.hokudai.ac.jp [Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638 (Japan)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer TRIM32 enhanced RAR{alpha}-mediated transcriptional activity even in the absence of RA. Black-Right-Pointing-Pointer TRIM32 stabilized RAR{alpha} in the human promyelogenous leukemic cell line HL60. Black-Right-Pointing-Pointer Overexpression of TRIM32 in HL60 cells induced granulocytic differentiation. Black-Right-Pointing-Pointer TRIM32 may function as a coactivator for RAR{alpha}-mediated transcription in APL cells. -- Abstract: Ubiquitination, one of the posttranslational modifications, appears to be involved in the transcriptional activity of nuclear receptors including retinoic acid receptor {alpha} (RAR{alpha}). We previously reported that an E3 ubiquitin ligase, TRIM32, interacts with several important proteins including RAR{alpha} and enhances transcriptional activity of RAR{alpha} in mouse neuroblastoma cells and embryonal carcinoma cells. Retinoic acid (RA), which acts as a ligand to nuclear receptors including RAR{alpha}, plays crucial roles in development, differentiation, cell cycles and apoptosis. In this study, we found that TRIM32 enhances RAR{alpha}-mediated transcriptional activity even in the absence of RA and stabilizes RAR{alpha} in the human promyelogenous leukemic cell line HL60. Moreover, we found that overexpression of TRIM32 in HL60 cells suppresses cellular proliferation and induces granulocytic differentiation even in the absence of RA. These findings suggest that TRIM32 functions as one of the coactivators for RAR{alpha}-mediated transcription in acute promyelogenous leukemia (APL) cells, and thus TRIM32 may become a potentially therapeutic target for APL.

  8. Androgen and retinoic acid interaction in LNCaP cells, effects on cell proliferation and expression of retinoic acid receptors and epidermal growth factor receptor

    Irwin Robert J

    2002-06-01

    Full Text Available Abstract Background Modulation of the expression of retinoic acid receptors (RAR α and γ in adult rat prostate by testosterone (T suggests that RAR signaling events might mediate some of the androgen effects on prostate cells. Method In this study, we examined the interactions between T and retinoic acid (RA in cell growth of human prostate carcinoma cells, LNCaP, and their relationship with the expression of RAR and epidermal growth factor receptor (EGF-R. Results Both T and RA, when administered alone, stimulated 3H-thymidine incorporation in LNCaP cells in a dose-dependent manner; the effect of each agent was reciprocally attenuated by the other agent. Testosterone treatment of LNCaP cells also resulted in dose dependent, biphasic increases in RAR α and γ mRNAs; increases paralleled that of 3H-thymidine incorporation and were attenuated by the presence of 100 nM RA. These results suggest a link between RAR signaling and the effect of T on LNCaP cell growth. Gel electrophoretic mobility shift assays revealed the presence of putative androgen responsive element (ARE in the promoter region of RAR α gene, suggesting that a direct AR-DNA interaction might mediate the effects of T on RAR α gene. Furthermore, treatment of LNCaP cells with 20 nM T resulted in an increase in EGF-R. In contrast, EGF-R was suppressed by 100 nM RA that also suppressed the effect of T. Conclusions Current results demonstrate interactions between T and RA in the expression of RARs and cell growth in LNCaP cells. The presence of putative ARE in the promoter of the RAR α gene suggests that AR-DNA interaction might mediate the effects of T on RAR α gene. The opposite effects of T and RA on the expression of RAR and EGF-R suggest that signal events of these receptors might be involved in the interaction between T and RA in the control of LNCaP cell growth.

  9. Androgen and retinoic acid interaction in LNCaP cells, effects on cell proliferation and expression of retinoic acid receptors and epidermal growth factor receptor

    Modulation of the expression of retinoic acid receptors (RAR) α and γ in adult rat prostate by testosterone (T) suggests that RAR signaling events might mediate some of the androgen effects on prostate cells. In this study, we examined the interactions between T and retinoic acid (RA) in cell growth of human prostate carcinoma cells, LNCaP, and their relationship with the expression of RAR and epidermal growth factor receptor (EGF-R). Both T and RA, when administered alone, stimulated 3H-thymidine incorporation in LNCaP cells in a dose-dependent manner; the effect of each agent was reciprocally attenuated by the other agent. Testosterone treatment of LNCaP cells also resulted in dose dependent, biphasic increases in RAR α and γ mRNAs; increases paralleled that of 3H-thymidine incorporation and were attenuated by the presence of 100 nM RA. These results suggest a link between RAR signaling and the effect of T on LNCaP cell growth. Gel electrophoretic mobility shift assays revealed the presence of putative androgen responsive element (ARE) in the promoter region of RAR α gene, suggesting that a direct AR-DNA interaction might mediate the effects of T on RAR α gene. Furthermore, treatment of LNCaP cells with 20 nM T resulted in an increase in EGF-R. In contrast, EGF-R was suppressed by 100 nM RA that also suppressed the effect of T. Current results demonstrate interactions between T and RA in the expression of RARs and cell growth in LNCaP cells. The presence of putative ARE in the promoter of the RAR α gene suggests that AR-DNA interaction might mediate the effects of T on RAR α gene. The opposite effects of T and RA on the expression of RAR and EGF-R suggest that signal events of these receptors might be involved in the interaction between T and RA in the control of LNCaP cell growth

  10. Unbinding of Retinoic Acid from its Receptor Studied by Steered Molecular Dynamics

    Kosztin, D; Schulten, K; Kosztin, Dorina; Izrailev, Sergei; Schulten, Klaus

    1999-01-01

    Retinoic acid receptor (RAR) is a ligand-dependent transcription factor that regulates the expression of genes involved in cell growth, differentiation, and development. Binding of the retinoic acid hormone to RAR is accompanied by conformational changes in the protein which induce transactivation or transrepression of the target genes. In this paper we present a study of the hormone binding/unbinding process in order to clarify the role of some of the amino acid contacts and identify possible pathways of the all-trans retinoic acid binding/unbinding to/from human retinoic acid receptor (hRAR)-g. Three possible pathways were explored using steered molecular dynamics simulations. Unbinding was induced on a time scale of 1 ns by applying external forces to the hormone. The simulations suggest that the hormone may employ one pathway for binding and an alternative "back door" pathway for unbinding.

  11. Evolutionary diversification of retinoic acid receptor ligand-binding pocket structure by molecular tinkering.

    Gutierrez-Mazariegos, Juliana; Nadendla, Eswar Kumar; Studer, Romain A; Alvarez, Susana; de Lera, Angel R; Kuraku, Shigehiro; Bourguet, William; Schubert, Michael; Laudet, Vincent

    2016-03-01

    Whole genome duplications (WGDs) have been classically associated with the origin of evolutionary novelties and the so-called duplication-degeneration-complementation model describes the possible fates of genes after duplication. However, how sequence divergence effectively allows functional changes between gene duplicates is still unclear. In the vertebrate lineage, two rounds of WGDs took place, giving rise to paralogous gene copies observed for many gene families. For the retinoic acid receptors (RARs), for example, which are members of the nuclear hormone receptor (NR) superfamily, a unique ancestral gene has been duplicated resulting in three vertebrate paralogues: RARα, RARβ and RARγ. It has previously been shown that this single ancestral RAR was neofunctionalized to give rise to a larger substrate specificity range in the RARs of extant jawed vertebrates (also called gnathostomes). To understand RAR diversification, the members of the cyclostomes (lamprey and hagfish), jawless vertebrates representing the extant sister group of gnathostomes, provide an intermediate situation and thus allow the characterization of the evolutionary steps that shaped RAR ligand-binding properties following the WGDs. In this study, we assessed the ligand-binding specificity of cyclostome RARs and found that their ligand-binding pockets resemble those of gnathostome RARα and RARβ. In contrast, none of the cyclostome receptors studied showed any RARγ-like specificity. Together, our results suggest that cyclostome RARs cover only a portion of the specificity repertoire of the ancestral gnathostome RARs and indicate that the establishment of ligand-binding specificity was a stepwise event. This iterative process thus provides a rare example for the diversification of receptor-ligand interactions of NRs following WGDs. PMID:27069642

  12. In silico discovery of novel Retinoic Acid Receptor agonist structures

    Samuels Herbert H

    2001-06-01

    Full Text Available Abstract Background Several Retinoic Acid Receptors (RAR agonists have therapeutic activity against a variety of cancer types; however, unacceptable toxicity profiles have hindered the development of drugs. RAR agonists presenting novel structural and chemical features could therefore open new avenues for the discovery of leads against breast, lung and prostate cancer or leukemia. Results We have analysed the induced fit of the active site residues upon binding of a known ligand. The derived binding site models were used to dock over 150,000 molecules in silico (or virtually to the structure of the receptor with the Internal Coordinates Mechanics (ICM program. Thirty ligand candidates were tested in vitro. Conclusions Two novel agonists resulting from the predicted receptor model were active at 50 nM. One of them displays novel structural features which may translate into the development of new ligands for cancer therapy.

  13. Phosphorylation by PKA potentiates retinoic acid receptor α activity by means of increasing interaction with and phosphorylation by cyclin H/cdk7

    Gaillard, Emilie; Bruck, Nathalie; Brelivet, Yann; Bour, Gaétan; Lalevée, Sébastien; Bauer, Annie; Poch, Olivier; Moras, Dino; Rochette-Egly, Cécile

    2006-01-01

    Nuclear retinoic acid receptors (RARs) work as ligand-dependent heterodimeric RAR/retinoid X receptor transcription activators, which are targets for phosphorylations. The N-terminal activation function (AF)-1 domain of RARα is phosphorylated by the cyclin-dependent kinase (cdk) 7/cyclin H complex of the general transcription factor TFIIH and the C-terminal AF-2 domain by the cAMP-dependent protein kinase A (PKA). Here, we report the identification of a molecular pathway by which phosphorylat...

  14. SIGNALLING THROUGH RETINOIC ACID RECEPTORS IN CARDIAC DEVELOPMENT: DOING THE RIGHT THINGS AT THE RIGHT TIMES

    Xavier-Neto, José; Costa, Ângela M. Sousa; Figueira, Ana Carolina M.; Caiaffa, Carlo Donato; do Amaral, Fabio Neves; Peres, Lara Maldanis Cerqueira; da Silva, Bárbara Santos Pires; Santos, Luana Nunes; Moise, Alexander R.; Castillo, Hozana Andrade

    2014-01-01

    Retinoic acid (RA) is a terpenoid that is synthesized from Vitamin A/retinol (ROL) and binds to the nuclear receptors retinoic acid receptor (RAR)/retinoid X receptor (RXR) to control multiple developmental processes in vertebrates. The available clinic and experimental data provide uncontested evidence for the pleiotropic roles of RA signalling in development of multiple embryonic structures and organs such eyes, central nervous system, gonads, lungs and heart. The development of any of thes...

  15. RAR/RXR binding dynamics distinguish pluripotency from differentiation associated cis-regulatory elements

    Chatagnon, Amandine; Veber, Philippe; Morin, Valérie; Bedo, Justin; Triqueneaux, Gérard; Sémon, Marie; Laudet, Vincent; D'Alché-Buc, Florence; Benoit, Gérard

    2015-01-01

    In mouse embryonic cells, ligand-activated retinoic acid receptors (RARs) play a key role in inhibiting pluripotency-maintaining genes and activating some major actors of cell differentiation. To investigate the mechanism underlying this dual regulation, we performed joint RAR/RXR ChIP-seq and mRNA-seq time series during the first 48 h of the RA-induced Primitive Endoderm (PrE) differentiation process in F9 embryonal carcinoma (EC) cells. We show here that this dual regulation is associated w...

  16. The proteosome inhibitor MG132 attenuates Retinoic Acid Receptor trans-activation and enhances trans-repression of Nuclear Factor κB. Potential relevance to chemo-preventive interventions with retinoids

    Rosier Randy N

    2004-03-01

    Full Text Available Abstract Background Nuclear factor kappa B (NFκB is a pro-malignant transcription factor with reciprocal effects on pro-metastatic and anti-metastatic gene expression. Interestingly, NFκB blockade results in the reciprocal induction of retinoic acid receptors (RARs. Given the established property of RARs as negative regulators of malignant progression, we postulated that reciprocal interactions between NFκB and RARs constitute a signaling module in metastatic gene expression and malignant progression. Using Line 1 tumor cells as a model for signal regulation of metastatic gene expression, we investigated the reciprocal interactions between NFκB and RARs in response to the pan-RAR agonist, all-trans retinoic acid (at-RA and the pan-RAR antagonist, AGN193109. Results At-RA [0.1–1 μM] dose-dependently activated RAR and coordinately trans-repressed NFκB, while AGN193109 [1–10 μM] dose-dependently antagonized the effects of at-RA. At-RA and AGN193109 reciprocally regulate pro-metastatic matrix metalloprotease 9 (MMP 9 and its endogenous inhibitor, the tissue inhibitor of metalloprotease 1 (TIMP 1, in a manner consistent with the putative roles of NFκB and RAR in malignant progression. Activation of RAR concurs with its ubiquitination and proteosomal degradation. Accordingly, the proteosome inhibitor, MG132 [5 μM], blocked RAR degradation, quelled RAR trans-activation and enhanced RAR trans-repression of NFκB. Conclusion We conclude that reciprocal interactions between NFκB and RARs constitute a signaling module in metastatic gene expression and malignant progression and propose that the dissociative effect of proteosome inhibitors could be harnessed towards enhancing the anticancer activity of retinoids.

  17. The elongation complex components BRD4 and MLLT3/AF9 are transcriptional coactivators of nuclear retinoid receptors.

    Sébastien Flajollet; Christophe Rachez; Maheul Ploton; Céline Schulz; Rozenn Gallais; Raphaël Métivier; Michal Pawlak; Aymeric Leray; Al Amine Issulahi; Laurent Héliot; Bart Staels; Gilles Salbert; Philippe Lefebvre

    2013-01-01

    International audience Nuclear all-trans retinoic acid receptors (RARs) initiate early transcriptional events which engage pluripotent cells to differentiate into specific lineages. RAR-controlled transactivation depends mostly on agonist-induced structural transitions in RAR C-terminus (AF-2), thus bridging coactivators or corepressors to chromatin, hence controlling preinitiation complex assembly. However, the contribution of other domains of RAR to its overall transcriptional activity r...

  18. The Retinoic Acid Receptor-α mediates human T-cell activation and Th2 cytokine and chemokine production

    Key Michael

    2008-04-01

    Full Text Available Abstract Background We have recently demonstrated that all-trans-retinoic acid (ATRA and 9-cis-retinoic acid (9-cis RA promote IL-4, IL-5 and IL-13 synthesis, while decreasing IFN-γ and TNF-α expression by activated human T cells and reduces the synthesis of IL-12p70 from accessory cells. Here, we have demonstrated that the observed effects using ATRA and 9-cis RA are shared with the clinically useful RAR ligand, 13-cis retinoic acid (13-cis RA, and the retinoic acid receptor-α (RAR-α-selective agonist, AM580 but not with the RAR-β/γ ligand, 4-hydroxyphenylretinamide (4-HPR. Results The increase in type 2 cytokine production by these retinoids correlated with the expression of the T cell activation markers, CD69 and CD38. The RAR-α-selective agonist, AM580 recapitulated all of the T cell activation and type 2 cytokine-inducing effects of ATRA and 9-cis-RA, while the RAR-α-selective antagonist, RO 41–5253, inhibited these effects. Conclusion These results strongly support a role for RAR-α engagement in the regulation of genes and proteins involved with human T cell activation and type 2 cytokine production.

  19. Triphenyl phosphate-induced developmental toxicity in zebrafish: Potential role of the retinoic acid receptor

    Isales, Gregory M.; Hipszer, Rachel A.; Tara D Raftery; Chen, Albert; Stapleton, Heather M.; Volz, David C.

    2015-01-01

    Using zebrafish as a model, we previously reported that developmental exposure to triphenyl phosphate (TPP) – a high-production volume organophosphate-based flame retardant – results in dioxin-like cardiac looping impairments that are independent of the aryl hydrocarbon receptor. Using a pharmacologic approach, the objective of this study was to investigate the potential role of retinoic acid receptor (RAR) – a nuclear receptor that regulates vertebrate heart morphogenesis – in mediating TPP-...

  20. Depletion of retinoic acid receptors initiates a novel positive feedback mechanism that promotes teratogenic increases in retinoic acid.

    Enrico D'Aniello

    Full Text Available Normal embryonic development and tissue homeostasis require precise levels of retinoic acid (RA signaling. Despite the importance of appropriate embryonic RA signaling levels, the mechanisms underlying congenital defects due to perturbations of RA signaling are not completely understood. Here, we report that zebrafish embryos deficient for RA receptor αb1 (RARαb1, a conserved RAR splice variant, have enlarged hearts with increased cardiomyocyte (CM specification, which are surprisingly the consequence of increased RA signaling. Importantly, depletion of RARαb2 or concurrent depletion of RARαb1 and RARαb2 also results in increased RA signaling, suggesting this effect is a broader consequence of RAR depletion. Concurrent depletion of RARαb1 and Cyp26a1, an enzyme that facilitates degradation of RA, and employment of a novel transgenic RA sensor line support the hypothesis that the increases in RA signaling in RAR deficient embryos are the result of increased embryonic RA coupled with compensatory RAR expression. Our results support an intriguing novel mechanism by which depletion of RARs elicits a previously unrecognized positive feedback loop that can result in developmental defects due to teratogenic increases in embryonic RA.

  1. Characterization of a retinoic acid responsive element isolated by whole genome PCR.

    Costa-Giomi, M P; Gaub, M P; Chambon, P; Abarzúa, P

    1992-01-01

    We have used whole PCR in an attempt to isolate novel retinoic acid (RA) responsive genes. We cloned several small genomic fragments from total human DNA containing putative retinoic acid responsive elements (RAREs) selected by direct binding to the retinoic acid receptor alpha (RAR alpha). We report here that an oligonucleotide containing a sequence from one of the cloned human DNA fragments, and referred to as alpha 1, functions as an authentic RARE. It is shown that both RAR alpha and RAR ...

  2. Retinoic acid receptors: from molecular mechanisms to cancer therapy.

    di Masi, Alessandra; Leboffe, Loris; De Marinis, Elisabetta; Pagano, Francesca; Cicconi, Laura; Rochette-Egly, Cécile; Lo-Coco, Francesco; Ascenzi, Paolo; Nervi, Clara

    2015-02-01

    Retinoic acid (RA), the major bioactive metabolite of retinol or vitamin A, induces a spectrum of pleiotropic effects in cell growth and differentiation that are relevant for embryonic development and adult physiology. The RA activity is mediated primarily by members of the retinoic acid receptor (RAR) subfamily, namely RARα, RARβ and RARγ, which belong to the nuclear receptor (NR) superfamily of transcription factors. RARs form heterodimers with members of the retinoid X receptor (RXR) subfamily and act as ligand-regulated transcription factors through binding specific RA response elements (RAREs) located in target genes promoters. RARs also have non-genomic effects and activate kinase signaling pathways, which fine-tune the transcription of the RA target genes. The disruption of RA signaling pathways is thought to underlie the etiology of a number of hematological and non-hematological malignancies, including leukemias, skin cancer, head/neck cancer, lung cancer, breast cancer, ovarian cancer, prostate cancer, renal cell carcinoma, pancreatic cancer, liver cancer, glioblastoma and neuroblastoma. Of note, RA and its derivatives (retinoids) are employed as potential chemotherapeutic or chemopreventive agents because of their differentiation, anti-proliferative, pro-apoptotic, and anti-oxidant effects. In humans, retinoids reverse premalignant epithelial lesions, induce the differentiation of myeloid normal and leukemic cells, and prevent lung, liver, and breast cancer. Here, we provide an overview of the biochemical and molecular mechanisms that regulate the RA and retinoid signaling pathways. Moreover, mechanisms through which deregulation of RA signaling pathways ultimately impact on cancer are examined. Finally, the therapeutic effects of retinoids are reported. PMID:25543955

  3. Retinoic acid receptor-dependent, cell-autonomous, endogenous retinoic acid signaling and its target genes in mouse collecting duct cells.

    Yuen Fei Wong

    Full Text Available BACKGROUND: Vitamin A is necessary for kidney development and has also been linked to regulation of solute and water homeostasis and to protection against kidney stone disease, infection, inflammation, and scarring. Most functions of vitamin A are mediated by its main active form, all-trans retinoic acid (tRA, which binds retinoic acid receptors (RARs to modulate gene expression. We and others have recently reported that renal tRA/RAR activity is confined to the ureteric bud (UB and collecting duct (CD cell lineage, suggesting that endogenous tRA/RARs primarily act through regulating gene expression in these cells in embryonic and adult kidney, respectively. METHODOLOGY/PRINCIPAL FINDINGS: To explore target genes of endogenous tRA/RARs, we employed the mIMCD-3 mouse inner medullary CD cell line, which is a model of CD principal cells and exhibits constitutive tRA/RAR activity as CD principal cells do in vivo. Combining antagonism of RARs, inhibition of tRA synthesis, exposure to exogenous tRA, and gene expression profiling techniques, we have identified 125 genes as candidate targets and validated 20 genes that were highly regulated (Dhrs3, Sprr1a, and Ppbp were the top three. Endogenous tRA/RARs were more important in maintaining, rather than suppressing, constitutive gene expression. Although many identified genes were expressed in UBs and/or CDs, their exact functions in this cell lineage are still poorly defined. Nevertheless, gene ontology analysis suggests that these genes are involved in kidney development, renal functioning, and regulation of tRA signaling. CONCLUSIONS/SIGNIFICANCE: A rigorous approach to defining target genes for endogenous tRA/RARs has been established. At the pan-genomic level, genes regulated by endogenous tRA/RARs in a CD cell line have been catalogued for the first time. Such a catalogue will guide further studies on molecular mediators of endogenous tRA/RARs during kidney development and in relation to renal

  4. Potential role of nuclear receptor ligand all-trans retinoic acids in the treatment of fungal keratitis

    Hong-Yan Zhou

    2015-08-01

    Full Text Available Fungal keratitis (FK is a worldwide visual impairment disease. This infectious fungus initiates the primary innate immune response and, later the adaptive immune response. The inflammatory process is related to a variety of immune cells, including macrophages, helper T cells, neutrophils, dendritic cells, and Treg cells, and is associated with proinflammatory, chemotactic and regulatory cytokines. All-trans retinoic acids (ATRA have diverse immunomodulatory actions in a number of inflammatory and autoimmune conditions. These retinoids regulate the transcriptional levels of target genes through the activation of nuclear receptors. Retinoic acid receptor α (RAR α, retinoic acid receptor γ (RAR γ, and retinoid X receptor α (RXR α are expressed in the cornea and immune cells. This paper summarizes new findings regarding ATRA in immune and inflammatory diseases and analyzes the perspective application of ATRA in FK.

  5. Potential role of nuclear receptor ligand all-trans retinoic acids in the treatment of fungal keratitis

    Hong-Yan; Zhou; Wei; Zhong; Hong; Zhang; Miao-Miao; Bi; Shuang; Wang; Wen-Song; Zhang

    2015-01-01

    ·Fungal keratitis(FK) is a worldwide visual impairment disease. This infectious fungus initiates the primary innate immune response and, later the adaptive immune response. The inflammatory process is related to a variety of immune cells, including macrophages, helper T cells, neutrophils, dendritic cells, and Treg cells, and is associated with proinflammatory, chemotactic and regulatory cytokines. All-trans retinoic acids(ATRA)have diverse immunomodulatory actions in a number of inflammatory and autoimmune conditions. These retinoids regulate the transcriptional levels of target genes through the activation of nuclear receptors.Retinoic acid receptor α(RAR α), retinoic acid receptor γ(RAR γ), and retinoid X receptor α(RXR α) are expressed in the cornea and immune cells. This paper summarizes new findings regarding ATRA in immune and inflammatory diseases and analyzes the perspective application of ATRA in FK.

  6. Triphenyl phosphate-induced developmental toxicity in zebrafish: Potential role of the retinoic acid receptor

    Highlights: • Triphenyl phosphate-induced toxicity in zebrafish embryos is enhanced in the presence of a retinoic acid receptor antagonist. • Triphenyl phosphate uptake or metabolism within zebrafish embryos is not altered in the presence of a retinoic acid receptor antagonist. • Triphenyl phosphate decreases expression of cytochrome P450 26a1 in zebrafish embryos. • Triphenyl phosphate inhibits retinoic acid-induced activation of human retinoic acid receptors. - Abstract: Using zebrafish as a model, we previously reported that developmental exposure to triphenyl phosphate (TPP) – a high-production volume organophosphate-based flame retardant – results in dioxin-like cardiac looping impairments that are independent of the aryl hydrocarbon receptor. Using a pharmacologic approach, the objective of this study was to investigate the potential role of retinoic acid receptor (RAR) – a nuclear receptor that regulates vertebrate heart morphogenesis – in mediating TPP-induced developmental toxicity in zebrafish. We first revealed that static exposure of zebrafish from 5–72 h post-fertilization (hpf) to TPP in the presence of non-toxic concentrations of an RAR antagonist (BMS493) significantly enhanced TPP-induced toxicity (relative to TPP alone), even though identical non-toxic BMS493 concentrations mitigated retinoic acid (RA)-induced toxicity. BMS493-mediated enhancement of TPP toxicity was not a result of differential TPP uptake or metabolism, as internal embryonic doses of TPP and diphenyl phosphate (DPP) – a primary TPP metabolite – were not different in the presence or absence of BMS493. Using real-time PCR, we then quantified the relative change in expression of cytochrome P450 26a1 (cyp26a1) – a major target gene for RA-induced RAR activation in zebrafish – and found that RA and TPP exposure resulted in a ∼5-fold increase and decrease in cyp26a1 expression, respectively, relative to vehicle-exposed embryos. To address whether TPP may

  7. Triphenyl phosphate-induced developmental toxicity in zebrafish: Potential role of the retinoic acid receptor

    Isales, Gregory M.; Hipszer, Rachel A.; Raftery, Tara D. [Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC (United States); Chen, Albert; Stapleton, Heather M. [Division of Environmental Sciences and Policy, Nicholas School of the Environment, Duke University, Durham, NC (United States); Volz, David C., E-mail: volz@mailbox.sc.edu [Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC (United States)

    2015-04-15

    Highlights: • Triphenyl phosphate-induced toxicity in zebrafish embryos is enhanced in the presence of a retinoic acid receptor antagonist. • Triphenyl phosphate uptake or metabolism within zebrafish embryos is not altered in the presence of a retinoic acid receptor antagonist. • Triphenyl phosphate decreases expression of cytochrome P450 26a1 in zebrafish embryos. • Triphenyl phosphate inhibits retinoic acid-induced activation of human retinoic acid receptors. - Abstract: Using zebrafish as a model, we previously reported that developmental exposure to triphenyl phosphate (TPP) – a high-production volume organophosphate-based flame retardant – results in dioxin-like cardiac looping impairments that are independent of the aryl hydrocarbon receptor. Using a pharmacologic approach, the objective of this study was to investigate the potential role of retinoic acid receptor (RAR) – a nuclear receptor that regulates vertebrate heart morphogenesis – in mediating TPP-induced developmental toxicity in zebrafish. We first revealed that static exposure of zebrafish from 5–72 h post-fertilization (hpf) to TPP in the presence of non-toxic concentrations of an RAR antagonist (BMS493) significantly enhanced TPP-induced toxicity (relative to TPP alone), even though identical non-toxic BMS493 concentrations mitigated retinoic acid (RA)-induced toxicity. BMS493-mediated enhancement of TPP toxicity was not a result of differential TPP uptake or metabolism, as internal embryonic doses of TPP and diphenyl phosphate (DPP) – a primary TPP metabolite – were not different in the presence or absence of BMS493. Using real-time PCR, we then quantified the relative change in expression of cytochrome P450 26a1 (cyp26a1) – a major target gene for RA-induced RAR activation in zebrafish – and found that RA and TPP exposure resulted in a ∼5-fold increase and decrease in cyp26a1 expression, respectively, relative to vehicle-exposed embryos. To address whether TPP may

  8. Benzo[a]pyrene diol epoxide suppresses retinoic acid receptor-β2 expression by recruiting DNA (cytosine-5--methyltransferase 3A

    Xu Xiao-Chun

    2010-04-01

    Full Text Available Abstract Tobacco smoke is an important risk factor for various human cancers, including esophageal cancer. How benzo [a]pyrene diol epoxide (BPDE, a carcinogen present in tobacco smoke as well as in environmental pollution, induces esophageal carcinogenesis has yet to be defined. In this study, we investigated the molecular mechanism responsible for BPDE-suppressed expression of retinoic acid receptor-beta2 (RAR-β2 in esophageal cancer cells. We treated esophageal cancer cells with BPDE before performing methylation-specific polymerase chain reaction (MSP to find that BPDE induced methylation of the RAR-β2 gene promoter. We then performed chromatin immunoprecipitation (ChIP assays to find that BPDE recruited genes of the methylation machinery into the RAR-β2 gene promoter. We found that BPDE recruited DNA (cytosine-5--methyltransferase 3 alpha (DNMT3A, but not beta (DNMT3B, in a time-dependent manner to methylate the RAR-β2 gene promoter, which we confirmed by reverse transcription-polymerase chain reaction (RT-PCR analysis of the reduced RAR-β2 expression in these BPDE-treated esophageal cancer cell lines. However, BPDE did not significantly change DNMT3A expression, but it slightly reduced DNMT3B expression. DNA methylase inhibitor 5-aza-2'-deoxycytidine (5-Aza and DNMT3A small hairpin RNA (shRNA vector antagonized the effects of BPDE on RAR-β2 expressions. Transient transfection of the DNMT3A shRNA vector also antagonized BPDE's effects on expression of RAR-β2, c-Jun, phosphorylated extracellular signal-regulated protein kinases 1/2 (ERK1/2, and cyclooxygenase-2 (COX-2, suggesting a possible therapeutic effect. The results of this study form the link between the esophageal cancer risk factor BPDE and the reduced RAR-β2 expression.

  9. Effect of retinoic acid on cell proliferation kinetics and retinoic acid receptor expression of colorectal mucosa

    Hong-Bo Wei; Xiao-Yan Han; Wei Fan; Gui-Hua Chen; Ji-Fu Wang

    2003-01-01

    AIM: To investigate the effect of retinoic acid (RA) on cell proliferation kinetics and retinoic acid receptor (RAR)expression of colorectal mucosa.METHODS:One hundred sixty healthy male Wistar rats were randomly divided into 4 groups. Rats in groups Ⅰ and Ⅱ were subcutaneously injected with dimethylhydrazine (DMH) (20 mg/kg, once a week,) for 7 to 13 weeks, while groups Ⅲ and Ⅳ were injected with normal saline. Rats in groups Ⅱ and Ⅲ were also treated with RA (50 mg/kg,every day, orally) from 7th to 15th week, thus group Ⅳ was used as a control. The rats were killed in different batches.The expressions of proliferating cell nuclear antigen (PCNA),nucleolar organizer region-associated protein (AgNOR) and RAR were detected.RESULTS: The incidence of colorectal carcinoma was different between groupsⅠ(100 %) and Ⅱ (15 %) (P<0.01).The PCNA indices and mean AgNOR count in group Ⅱ were significantly lower than those in group Ⅰ(F=5.418 and 4.243,P<0.01). The PCNA indices and mean AgNOR count in groups Ⅰ and Ⅱ were significantly higher than those in the groups Ⅲ and Ⅳ (in which carcinogen was not used) (F=5.927and 4.348, P<0.01). There was a tendency in group Ⅰ that the longer the induction with DMH the higher PCNA index and AgNOR count expressed (F=7.634 and 6.826, P<0.05).However, there was no such tendency in groups Ⅱ, Ⅲ and Ⅳ(F=1.662 and 1.984, P>0.05). The levels of RAR in normal and cancerous tissues in groups treated with RA were significantly higher than those in groups not treated with RA (F=6.343 and 6.024, P<0.05).CONCLUSION: RA decreases the incidence of colorectal carcinoma induced by DMH. Coiorectal cancer tissue is associated with abnormal expression of PCNA, AgNOR and RAR. RA inhibits the expression of PCNA and AgNOR, and increases RAR concentration in colorectal tissues.

  10. Retinoic acid-mediated repression of human papillomavirus 18 transcription and different ligand regulation of the retinoic acid receptor beta gene in non-tumorigenic and tumorigenic HeLa hybrid cells.

    Bartsch, D; Boye, B; Baust, C; zur Hausen, H; Schwarz, E

    1992-01-01

    Human papillomavirus type 18 (HPV18) belongs to the group of genital papillomaviruses involved in the development of cervical carcinomas. Since retinoic acid (RA) is a key regulator of epithelial cell differentiation and a growth inhibitor in vitro of HPV18-positive HeLa cervical carcinoma cells, we have used HeLa and HeLa hybrid cells in order to analyse the effects of RA on expression of the HPV18 E6 and E7 oncogenes and of the cellular RA receptor genes RAR-beta and -gamma. We show here that RA down-regulates HPV18 mRNA levels apparently due to transcriptional repression. Transient cotransfection assays indicated that RARs negatively regulate the HPV18 upstream regulatory region and that the central enhancer can confer RA-dependent repression on a heterologous promoter. RA treatment resulted in induction of RAR-beta mRNA levels in non-tumorigenic HeLa hybrid cells, but not in tumorigenic hybrid segregants nor in HeLa cells. No alterations of the RAR-beta gene or of the HeLa RAR-beta promoter could be revealed by Southern and DNA sequence analysis, respectively. As determined by transient transfection assays, however, the RAR-beta control region was activated by RA more strongly in non-tumorigenic hybrid cells than in HeLa cells, thus indicating differences in trans-acting regulatory factors. Our data suggest that the RARs are potential negative regulators of HPV18 E6 and E7 gene expression, and that dysregulation of the RAR-beta gene either causatively contributes to or is an indicator of tumorigenicity in HeLa and HeLa hybrid cells. Images PMID:1318198

  11. Retinoic Acid Receptors Control Spermatogonia Cell-Fate and Induce Expression of the SALL4A Transcription Factor.

    Aurore Gely-Pernot

    2015-10-01

    Full Text Available All-trans retinoic acid (ATRA is instrumental to male germ cell differentiation, but its mechanism of action remains elusive. To address this question, we have analyzed the phenotypes of mice lacking, in spermatogonia, all rexinoid receptors (RXRA, RXRB and RXRG or all ATRA receptors (RARA, RARB and RARG. We demonstrate that the combined ablation of RXRA and RXRB in spermatogonia recapitulates the set of defects observed both upon ablation of RAR in spermatogonia. We also show that ATRA activates RAR and RXR bound to a conserved regulatory region to increase expression of the SALL4A transcription factor in spermatogonia. Our results reveal that this major pluripotency gene is a target of ATRA signaling and that RAR/RXR heterodimers are the functional units driving its expression in spermatogonia. They add to the mechanisms through which ATRA promote expression of the KIT tyrosine kinase receptor to trigger a critical step in spermatogonia differentiation. Importantly, they indicate also that meiosis eventually occurs in the absence of a RAR/RXR pathway within germ cells and suggest that instructing this process is either ATRA-independent or requires an ATRA signal originating from Sertoli cells.

  12. 9-cis-Retinoic acid inhibition of lung carcinogenesis in the A/J mouse model is accompanied by increased expression of RAR-beta but no change in cyclooxygenase-2.

    Mernitz, Heather; Smith, Donald E.; Andrew X Zhu; Wang, Xiang-Dong

    2006-01-01

    Dietary modulation of carcinogenesis-related pathwaysDietary item or component studied: 9cRA (9-cis-retinoic acid)Pathways studied: upregulation of RAR-β and suppression of COX-2 at the transcriptional levelStudy type (in vitro, animals, humans): male A/J miceTissue/biological material/sample size: 20mg lung tissueMode of exposure (if in vivo) (acute, chronic, root of exposure): i.p. injectionsImpact on pathway (including dose-response): the group receiving NNK alone had significantly higher...

  13. Mechanisms of all-trans retinoic acid-induced differentiation of acute promyelocytic leukemia cells

    Ji-Wang Zhang; Jian Gu; Zhen-Yi Wang; Sai-Juan Chen; Zhu Chen

    2000-09-01

    Retinoic acids (RA) play a key role in myeloid differentiation through their agonistic nuclear receptors (RAR/RXR) to modulate the expression of target genes. In acute promyelocytic leukemia (APL) cells with rearrangement of retinoic acid receptor (RAR) (including: PML-RAR, PLZF-RAR, NPM-RAR, NuMA-RAR or STAT5b-RAR) as a result of chromosomal translocations, the RA signal pathway is disrupted and myeloid differentiation is arrested at the promyelocytic stage. Pharmacologic dosage of all-trans retinoic acid (ATRA) directly modulates PML-RAR and its interaction with the nuclear receptor co-repressor complex, which restores the wild-type RAR/RXR regulatory pathway and induces the transcriptional expression of downstream genes. Analysing gene expression profiles in APL cells before and after ATRA treatment represents a useful approach to identify genes whose functions are involved in this new cancer treatment. A chronologically well coordinated modulation of ATRA-regulated genes has thus been revealed which seems to constitute a balanced functional network underlying decreased cellular proliferation, initiation and progression of maturation, and maintenance of cell survival before terminal differentiation.

  14. The proliferating cell nuclear antigen regulates retinoic acid receptor transcriptional activity through direct protein–protein interaction

    Martin, Perrine J; Lardeux, Virginie; Lefebvre, Philippe

    2005-01-01

    Retinoic acid receptors (RARs) interact, in a ligand-dependent fashion, with many coregulators that participate in a wide spectrum of biological responses, ranging from embryonic development to cellular growth control. The transactivating function of these ligand-inducible transcription factors reside mainly, but not exclusively, in their ligand-binding domain (AF2), which recruits or dismiss coregulators in a ligand-dependent fashion. However, little is known about AF2-independent function(s...

  15. Signaling through retinoic acid receptors in cardiac development: Doing the right things at the right times.

    Xavier-Neto, José; Sousa Costa, Ângela M; Figueira, Ana Carolina M; Caiaffa, Carlo Donato; Amaral, Fabio Neves do; Peres, Lara Maldanis Cerqueira; da Silva, Bárbara Santos Pires; Santos, Luana Nunes; Moise, Alexander R; Castillo, Hozana Andrade

    2015-02-01

    Retinoic acid (RA) is a terpenoid that is synthesized from vitamin A/retinol (ROL) and binds to the nuclear receptors retinoic acid receptor (RAR)/retinoid X receptor (RXR) to control multiple developmental processes in vertebrates. The available clinical and experimental data provide uncontested evidence for the pleiotropic roles of RA signaling in development of multiple embryonic structures and organs such eyes, central nervous system, gonads, lungs and heart. The development of any of these above-mentioned embryonic organ systems can be effectively utilized to showcase the many strategies utilized by RA signaling. However, it is very likely that the strategies employed to transfer RA signals during cardiac development comprise the majority of the relevant and sophisticated ways through which retinoid signals can be conveyed in a complex biological system. Here, we provide the reader with arguments indicating that RA signaling is exquisitely regulated according to specific phases of cardiac development and that RA signaling itself is one of the major regulators of the timing of cardiac morphogenesis and differentiation. We will focus on the role of signaling by RA receptors (RARs) in early phases of heart development. This article is part of a Special Issue entitled: Nuclear receptors in animal development. PMID:25134739

  16. Computer-aided design of a novel ligand for retinoic acid receptor in cancer chemotherapy

    Silva, Carlos H. T. P.; Leopoldino, Andreia M.; Silva, Eloiza H. T.; Espinoza, V. A. A.; Taft, C. A.

    The isotypes of RAR and RXR are retinoic acid and retinoid X acid receptors, respectively, whose ligand-binding domain contains the ligand-dependent activation function, with distinct pharmacological targets for retinoids, involved in the treatment of various cancers and skin diseases. Due to the major challenge which cancer treatment and cure still imposes after many decades to the international scientific community, there is actually considerable interest in new ligands with increased bioactivity. We have focused on the retinoid acid receptor, which is considered an interesting target for drug design. In this work, we carried out density functional geometry optimizations and different docking procedures. We performed screening in a large database (hundreds of thousands of molecules which we optimized at the AM1 level) yielding a set of potential bioactive ligands. A new ligand was selected and optimized at the B3LYP/6-31G* level. A flexible docking program was used to investigate the interactions between the receptor and the new ligand. The result of this work is compared with several crystallographic ligands of RAR. Our theoretically more bioactive new ligand indicates stronger and more hydrogen bonds as well as hydrophobic interactions with the receptor.

  17. SIGNALLING THROUGH RETINOIC ACID RECEPTORS IN CARDIAC DEVELOPMENT: DOING THE RIGHT THINGS AT THE RIGHT TIMES

    Xavier-Neto, José; Costa, Ângela M. Sousa; Figueira, Ana Carolina M.; Caiaffa, Carlo Donato; do Amaral, Fabio Neves; Peres, Lara Maldanis Cerqueira; da Silva, Bárbara Santos Pires; Santos, Luana Nunes; Moise, Alexander R.; Castillo, Hozana Andrade

    2015-01-01

    Retinoic acid (RA) is a terpenoid that is synthesized from Vitamin A/retinol (ROL) and binds to the nuclear receptors retinoic acid receptor (RAR)/retinoid X receptor (RXR) to control multiple developmental processes in vertebrates. The available clinic and experimental data provide uncontested evidence for the pleiotropic roles of RA signalling in development of multiple embryonic structures and organs such eyes, central nervous system, gonads, lungs and heart. The development of any of these above-mentioned embryonic organ systems can be effectively utilized to showcase the many strategies utilized by RA signalling. However, it is very likely that the strategies employed to transfer RA signals during cardiac development comprise the majority of the relevant and sophisticated ways through which retinoid signals can be conveyed in a complex biological system. Here, we provide the reader with arguments indicating that RA signalling is exquisitely regulated according to specific phases of cardiac development and that RA signalling itself is one of the major regulators of the timing of cardiac morphogenesis and differentiation. We will focus on the role of signalling by RA receptors (RARs) in early phases of heart development. PMID:25134739

  18. Excitatory amino acid receptor antagonists

    Johansen, T N; Frydenvang, Karla Andrea; Ebert, B;

    1997-01-01

    We have previously shown that (RS)-2-amino-2-(5-tert-butyl-3-hydroxyisoxazol-4-yl)acetic acid (ATAA) is an antagonist at N-methyl-D-aspartic acid (NMDA) and (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors. We have now resolved ATAA via diastereomeric salt formation...

  19. Disruption of retinoic acid receptor alpha reveals the growth promoter face of retinoic acid.

    Giulia Somenzi

    Full Text Available BACKGROUND: Retinoic acid (RA, the bioactive derivative of Vitamin A, by epigenetically controlling transcription through the RA-receptors (RARs, exerts a potent antiproliferative effect on human cells. However, a number of studies show that RA can also promote cell survival and growth. In the course of one of our studies we observed that disruption of RA-receptor alpha, RARalpha, abrogates the RA-mediated growth-inhibitory effects and unmasks the growth-promoting face of RA (Ren et al., Mol. Cell. Biol., 2005, 25:10591. The objective of this study was to investigate whether RA can differentially govern cell growth, in the presence and absence of RARalpha, through differential regulation of the "rheostat" comprising ceramide (CER, the sphingolipid with growth-inhibitory activity, and sphingosine-1-phosphate (S1P, the sphingolipid with prosurvival activity. METHODOLOGY/PRINCIPAL FINDINGS: We found that functional inhibition of endogenous RARalpha in breast cancer cells by using either RARalpha specific antagonists or a dominant negative RARalpha mutant hampers on one hand the RA-induced upregulation of neutral sphingomyelinase (nSMase-mediated CER synthesis, and on the other hand the RA-induced downregulation of sphingosine kinase 1, SK1, pivotal for S1P synthesis. In association with RA inability to regulate the sphingolipid rheostat, cells not only survive, but also grow more in response to RA both in vitro and in vivo. By combining genetic, pharmacological and biochemical approaches, we mechanistically demonstrated that RA-induced growth is, at least in part, due to non-RAR-mediated activation of the SK1-S1P signaling. CONCLUSIONS/SIGNIFICANCE: In the presence of functional RARalpha, RA inhibits cell growth by concertedly, and inversely, modulating the CER and S1P synthetic pathways. In the absence of a functional RARalpha, RA-in a non-RAR-mediated fashion-promotes cell growth by activating the prosurvival S1P signaling. These two distinct

  20. Retinoic acid receptor gamma-induced misregulation of chondrogenesis in the murine limb bud in vitro.

    Galdones, Eugene; Hales, Barbara F

    2008-11-01

    Vitamin A derivatives modulate gene expression through retinoic acid and rexinoid receptor (RAR/RXR) heterodimers and are indispensable for limb development. Of particular interest, RARgamma is highly expressed in cartilage, a target affected following retinoid-induced limb insult. The goal of this study was to examine how selective activation of RARgamma affects limb development. Forelimbs from E12.5 CD-1 mice were cultured for 6 days in the presence of all-trans RA (pan-RAR agonist; 0.1 or 1.0 microM) or BMS-189961 (BMS961, RARgamma-selective agonist; 0.01 or 0.1 microM) and limb morphology assessed. Untreated limbs developed normal cartilage elements whereas pan-RAR or RARgamma agonist-treated limbs exhibited reductive effects on chondrogenesis. Retinoid activity was assessed using RAREbeta2 (retinoic acid response element beta2)-lacZ reporter limbs; after 3 h of treatment, both drugs increased retinoid activity proximally. To elucidate the expression profiles of a subset of genes important for development, limbs were cultured for 3 h and cRNA hybridized to osteogenesis-focused microarrays. Two genes, matrix GLA protein (Mgp; chondrogenesis inhibitor) and growth differentiation factor-10 (Gdf10/Bmp3b) were induced by RA and BMS-189961. Real-time PCR was done to validate our results and whole mount in situ hybridizations against Mgp and Gdf10 localized their upregulation to areas of cartilage and programmed cell death, respectively. Thus, our results illustrate the importance of RARgamma in mediating the retinoid-induced upregulation of Mgp and Gdf10; determining their roles in chondrogenesis and cell death will help further unravel mechanisms underlying retinoid teratogenicity. PMID:18703560

  1. Function of retinoic acid receptors during embryonic development.

    Mark, Manuel; Ghyselinck, Norbert; Chambon, Pierre

    2009-01-01

    International audience Retinoids, the active metabolites of vitamin A, regulate complex gene networks involved in vertebrate morphogenesis, growth, cellular differentiation and homeostasis. Studies performed in vitro, using either acellular systems or transfected cells, have shown that retinoid actions are mediated through heterodimers between the RAR and RXR nuclear receptors. However, in vitro studies indicate what is possible, but not necessarily what is actually occurring in vivo, beca...

  2. Design, synthesis, and structure-activity analysis of isoform-selective retinoic acid receptor ß ligands

    Lund, Birgitte W.; Knapp, Anne Eeg; Piu, Fabrice;

    2009-01-01

    We recently discovered the isoform selective RAR beta 2 ligand 4'-octyl-4-biphenylcarboxylic acid (3, AC-55649). Although 3 is highly potent at RAR beta 2 and displays excellent selectivity, solubility issues make it unsuitable for drug development. Herein we describe the exploration of the SAR in...

  3. Teratogenic effects of triphenyltin on embryos of amphibian (Xenopus tropicalis): a phenotypic comparison with the retinoid X and retinoic acid receptor ligands.

    Yu, Lin; Zhang, Xiaoli; Yuan, Jing; Cao, Qinzhen; Liu, Junqi; Zhu, Pan; Shi, Huahong

    2011-09-15

    Triphenyltin (TPT) has high binding affinity with the retinoid X receptor (RXR) in animals. The natural ligand of RXR, 9-cis-retinoic acid (RA), is known to induce featured malformations in vertebrate embryos by disrupting RA signal. Limited information is available on the TPT effects on amphibians. We exposed embryos of amphibian (Xenopus tropicalis) to TPT, 9-cis-RA, all-trans-RA (ligand of retinoic acid receptor, RAR), and LGD1069 (a selective ligand of RXR). The 72h LC50 of TPT was 5.25 μg Sn/L, and 72h EC50 was 0.96 μg Sn/L. TPT induced multiple malformations including enlarged proctodaeum and narrow fins. TPT at 5 μg Sn/L inhibited the differentiation of skins and muscles. The reduced brain, loss of external eyes and bent axis were observed in RXR and RAR ligands treatments. TPT and tributyltin (TBT) inhibited the mRNA expression of RXRα and increased that of TRβ. The phenotypes of malformations induced by TPT were similar to those by TBT and were much different from those by the RXR and RAR ligands. These results indicated that TPT was acute toxic and had high teratogenicity to amphibian embryos, and that TPT induced phenotypes of malformations. TPT and TBT might have a similar teratogenic mechanism, which seems not to be mainly mediated through RA signal. PMID:21820800

  4. The retinoic acid receptor agonist Am80 increases hippocampal ADAM10 in aged SAMP8 mice.

    Kitaoka, Kazuyoshi; Shimizu, Noriyuki; Ono, Koji; Chikahisa, Sachiko; Nakagomi, Madoka; Shudo, Koichi; Ishimura, Kazunori; Séi, Hiroyoshi; Yoshizaki, Kazuo

    2013-09-01

    The retinoic acid (RA, a vitamin A metabolite) receptor (RAR) is a transcription factor. Vitamin A/RA administration improves the Alzheimer's disease (AD)- and age-related attenuation of memory/learning in mouse models. Recently, a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) was identified as a key molecule in RA-mediated anti-AD mechanisms. We investigated the effect of chronic administration of the RAR agonist Am80 (tamibarotene) on ADAM10 expression in senescence-accelerated mice (SAMP8). Moreover, we estimated changes in the expression of the amyloid precursor protein (APP), amyloid beta (Aβ), and hairy/enhancer of split (Hes), which are mediated by ADAM10. Spatial working memory and the levels of a hippocampal proliferation marker (Ki67) were also assessed in these mice. ADAM10 mRNA and protein expression was significantly reduced in the hippocampus of 13-month-old SAMP8 mice; their expression improved significantly after Am80 administration. Further, after Am80 administration, the expression levels of Hes5 and Ki67 were restored and the deterioration of working memory was suppressed, whereas APP and Aβ levels remained unchanged. Our results suggest that Am80 administration effectively improves dementia by activating the hippocampal ADAM10-Notch-Hes5 proliferative pathway. PMID:23624141

  5. Identification of potent and selective retinoic acid receptor gamma (RARγ) antagonists for the treatment of osteoarthritis pain using structure based drug design.

    Hughes, Norman E; Bleisch, Thomas J; Jones, Scott A; Richardson, Timothy I; Doti, Robert A; Wang, Yong; Stout, Stephanie L; Durst, Gregory L; Chambers, Mark G; Oskins, Jennifer L; Lin, Chaohua; Adams, Lisa A; Page, Todd J; Barr, Robert J; Zink, Richard W; Osborne, Harold; Montrose-Rafizadeh, Chahrzad; Norman, Bryan H

    2016-07-15

    A series of triaryl pyrazoles were identified as potent pan antagonists for the retinoic acid receptors (RARs) α, β and γ. X-ray crystallography and structure-based drug design were used to improve selectivity for RARγ by targeting residue differences in the ligand binding pockets of these receptors. This resulted in the discovery of novel antagonists which maintained RARγ potency but were greater than 500-fold selective versus RARα and RARβ. The potent and selective RARγ antagonist LY2955303 demonstrated good pharmacokinetic properties and was efficacious in the MIA model of osteoarthritis-like joint pain. This compound demonstrated an improved margin to RARα-mediated adverse effects. PMID:27261179

  6. Normal HC11 and ras-transformed mouse mammary cells are resistant to the antiproliferative effects of retinoic acid

    Snitcovsky I.

    2003-01-01

    Full Text Available The objective of the present study was to determine the effects of retinoic acid on the growth of the mouse mammary cells HC11 and HC11ras, which are a model for in vitro breast cancer progression. The expression of the two classes (RARs and RXRs of retinoic acid receptor mRNAs was determined by Northern blot analysis. Receptor functional integrity was determined by testing whether RAR ß mRNA could be induced by retinoic acid. The effects of a 72-h exposure to 50 µM 13-cis retinoic acid on HC11 and HC11ras cell proliferation and HC11 cell differentiation were investigated by flow cytometric cell cycle analysis, and by determination of ß-casein mRNA expression, respectively. The possibility that retinoic acid would induce the expression of the vitamin D receptor and synergize with vitamin D, a known inhibitor of HC11 cell growth, was also investigated. HC11 cells expressed higher mRNA levels of both RAR a and RAR g when compared to HC11ras cells. In contrast, RAR ß, as well as RXR a, ß and g expression was low in both HC11 and HC11ras cells. In addition, RAR ß mRNA was induced by retinoic acid treatment in both cells. In spite of these observations, no effects were seen on cell proliferation or differentiation upon exposure to retinoic acid. Neither vitamin D receptor induction nor synergy with vitamin D on growth inhibition was observed. We conclude that the RAR expression profile could be related to the transformed state in HC11ras cells and that the retinoic acid resistance observed merits further investigation.

  7. Retinoic acid disrupts the Golgi apparatus and increases the cytosolic routing of specific protein toxins

    1994-01-01

    All-trans retinoic acid can specifically increase receptor mediated intoxication of ricin A chain immunotoxins more than 10,000 times, whereas fluid phase endocytosis of ricin A chain alone or ricin A chain immunotoxins was not influenced by retinoic acid. The immunotoxin activation by retinoic acid does not require RNA or protein synthesis and is not a consequence of increased receptor binding of the immunotoxin. Vitamin D3 and thyroid hormone T3, that activate retinoic acid receptor (RAR) c...

  8. The effect pathway of retinoic acid through regulation of retinoic acid receptor in gastric cancer cells

    Su Liu; Qiao Wu; Zheng-Ming Chen; Wen-Jin Su

    2001-01-01

    AIM To evaluate the role of RARa gene in mediating the growth inhibitory effect of ail-trans retinoic acid (ATRA)on gastric cancer cells.``METHODS The expression levels of retinoic acid receptors (RARs) in gastric cancer cells were detected by Northern blot. Transient transfection and chlorophenicol acetyl transferase (CAT) assay were used to show the transcriptional activity of β retinoic acid response element (βRARE) and AP-l activity. Cell growth inhibition was determined by MTT assay and anchorage-independent growth assay, respectively. Stable transfection was performed by the method of Lipofectamine, and the cells were screened by G418.``RESULTS ATRA could induce expression level of RARα in MGC80-3, BGCC8823 and SGC-7901 cells obviously,resulting in growth inhibition of these cell lines. After sense RARa gene was transfected into MKN-45 cells that expressed rather Iow level of RARα and could not be induced by ATRA, the cell growth was inhibited by ATRA markedly. In contrast, when antisense RARα gene was transfected into BGC-825 cells, a little inhibitory effect by ATRA was seen, compared with the parallel BGC-823cells. In transient transfection assay, ATRA effectively induced transcriptional activity of βRARE in MGC80-3,BGC.823, SGC-7902 and MKN/RARa cell lines, but not in MKN-45 and BGC/aRARa cell lines. Similar results were observed in measuring anti-AP-l activity by ATRA in these cancer cell lines.``CONCLUSION ATRA inhibits the growth of gastric cancer cells by up-regulating the level of RARa; RARa is the major mediator of ATRA action in gastric cancer cells; and adequate level of RAPa is required for ATRA effect on gastric cancer cells.``

  9. Retinoic acid signalling in thymocytes regulates T cell development

    Wendland, Kerstin; Sitnik, Katarzyna Maria; Kotarsky, Knut;

    The Vitamin A derivative retinoic acid (RA) has emerged as an important regulator of peripheral T cell responses. However, whether there is endogenous retinoic acid receptor (RAR) signaling in developing thymocytes and the potential impact of such signals in thymocyte development remains unclear...

  10. Effect on Retinoic Acid Receptor and Proliferating Cell Nuclear Antigen of Retinoic Acid in Colorectal Carcinoma%肠癌组织维甲酸受体的测定和维甲酸对其表达的影响

    樊卫; 卫洪波; 韩晓燕

    2001-01-01

    Objective To investigate the effect on retinoic acid receptor (RAR) of retinoic acid (RA) in colorectal carcinoma. Methods 160 cases of health male Wistar rats were divided into 4 groups, and each group was of 40 cases.80 rats in group 1 and 2 induced by dimethylhydrazine (DMH) (20mg/kg,once a week,injected subdermally) for 7~13 weeks;after that,rats in group 2 and 3 were treated with RA (50mg/kg,every day,orally) for 8 weeks;others were was control. In 7th\14th\21th week, 8 rats were killed in each group. The others were killed in 28th week.Colorectal tumors in mucosa were examined. The RAR concentration was studied. Results The incidence of colorectal carcinoma induced by DMH between group 1and 2 was different significantly (p<0.05),and higher than group 3 and 4.The content of RAR in cancer groups was lower than normal one (p<0.05).RA may increase RAR concentration of cancer tissue progressively (p<0.05).Conclusions RA could decrease the incidence of colorectal carcinoma induced by DMH. Colorectal cancer tissue existed abnormal expression of RAR,RA could regulate RAR concentrations of intestine cells.%目的用放射配体结合分析法测定肠癌组织细胞内维甲酸受体 (retinoic acid receptor, RAR)含量,探讨维甲酸 (Retinoic acid, RA)对肠癌组织内RAR表达的影响.方法取Wistar大鼠160只,随机分4组,每组40只,其中第1、2组二甲基肼诱癌,第3、4组用生理盐水注射;于第7周开始,第2、3组按50mg/kg体重灌服维甲酸,每日1次,共8周.于7,14, 21周每组处死8只,于28周全部处死大鼠.测定RAR的含量.结果第1组肠癌发生率100%,第2组20%,差异有显著性(p<0.01);结肠组织细胞核内存在丰富的RAR,而肠癌组织RAR含量明显减少,并主要表现为数量的减少; RA对正常组织、肠癌组织内的RAR表达有显著性影响,差别有统计学意义(p<0.05).结论 RA可以减少二甲基肼诱发肠癌的发生;肠癌组织

  11. Retinoic acid synthesis and functions in early embryonic development

    Kam Richard Kin Ting; Deng Yi; Chen Yonglong; Zhao Hui

    2012-01-01

    Abstract Retinoic acid (RA) is a morphogen derived from retinol (vitamin A) that plays important roles in cell growth, differentiation, and organogenesis. The production of RA from retinol requires two consecutive enzymatic reactions catalyzed by different sets of dehydrogenases. The retinol is first oxidized into retinal, which is then oxidized into RA. The RA interacts with retinoic acid receptor (RAR) and retinoic acid X receptor (RXR) which then regulate the target gene expression. In thi...

  12. Subtype selective kainic acid receptor agonists

    Bunch, Lennart; Krogsgaard-Larsen, Povl

    2009-01-01

    (S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the mammalian central nervous system, activating the plethora of glutamate receptors (GluRs). In broad lines, the GluRs are divided into two major classes: the ionotropic Glu receptors (iGluRs) and the metabotropic Glu receptors ....... In total, over 100 compounds are described by means of chemical structure and available pharmacological data. With this perspective review, it is our intention to ignite and stimulate inspiration for future design and synthesis of novel subtype selective KA receptor agonists....

  13. Bile acids and derivatives, their nuclear receptors FXR, PXR and ligands: role in health and disease and their therapeutic potential.

    Zimber, Amazia; Gespach, Christian

    2008-06-01

    Bile acids, their physiology and metabolism, their role in carcinogenesis and other major human diseases are recently undergoing significant progress. Starting in 1999 when the orphan nuclear receptor FXR was shown to be specifically activated by bile acids, these compounds became part of the arsenal of ligands of the steroid hormone superfamily of nuclear receptors, including receptors of Vitamin D3, retinoids (RAR, RXR), and thyroid hormone. Another decisive discovery pointed later that the pregnane X-receptor (PXR) is activated by the endogenous toxic lithocholic acid, as well as several xenobiotics and drugs. Bile acids have recently emerged as key regulators of their own metabolism, and of lipid and carbohydrate metabolism. They have important role as promoters of esophageal and colon cancers, cholangiocarcinoma, as well as new implications in breast cancer development and metastasis. This Review will emphasize novel aspects of bile acids, FXR and PXR as regulators of interfaces at cell proliferation and differentiation, cell death, survival, invasion, and metastasis during normal development and cancer progression. Signaling pathways controlled by bile acids will be presented and discussed in relation to their impact on gene expression. The biological and pharmacological significance of bile acids and their recently developed synthetic derivatives and conjugates, as well as new development in the design of FXR agonists and antagonists for clinical applications in cancer prevention and therapy, will be evaluated. This part includes advances in the utilization of bile acid transporters in drug resistance, therapeutic targeting and delivery of anticancer drugs, as well as therapeutic combinations using new bile acid derivatives, sequestrating agents and reabsorption inhibitors, and their limitations. PMID:18537536

  14. HAL-RAR PROCEDURE IN HEMORRHOIDAL DISEASE MANAGEMENT

    D. Lăzescu; Gabriela Canschi; B. Ţuţuianu; V. Munteanu; Gabriela Prepeliţă; Claudia Luncă; Irina Ristescu

    2010-01-01

    Introduction: HAL-RAR is a new, minimally invasive, safe and efficient tehniques in the treatment of hemorrhoidal disease who combines in one procedure HAL (Hemorrhoidal Artery Ligation) with mucopexy (RAR), prolapsed piles “lifting”. Methods: We performed HAL-RAR procedure on 118 patients (50 females and 68 males) with ages between 21 and 76 years with hemorrhoids grade II-IV (4,23% grade II, 24,57% grade III and 71,18% grade IV). Postoperative follow-up consisted in examination a week after...

  15. Complex Pharmacology of Free Fatty Acid Receptors

    Milligan, Graeme; Shimpukade, Bharat; Ulven, Trond;

    2016-01-01

    G protein-coupled receptors (GPCRs) are historically the most successful family of drug targets. In recent times it has become clear that the pharmacology of these receptors is far more complex than previously imagined. Understanding of the pharmacological regulation of GPCRs now extends beyond...... pharmacology have shaped understanding of the complex pharmacology of receptors that recognize and are activated by nonesterified or "free" fatty acids (FFAs). The FFA family of receptors is a recently deorphanized set of GPCRs, the members of which are now receiving substantial interest as novel targets for...... the treatment of metabolic and inflammatory diseases. Further understanding of the complex pharmacology of these receptors will be critical to unlocking their ultimate therapeutic potential....

  16. Effect of all-trans retinoic acid, 9-cis retinoic acid and their combination on the expression of selected nuclear RARs and RXRs and protein profile in human MCF-7 breast cancer cell line

    Brtko, J.; Macejová, D.; Bialešová, L.; Toporová, L.; Flodrová, Dana; Bobálová, Janette

    Elsevier. 238S, - (2015), S373-S373. ISSN 0378-4274. [Congress of the European Societies of Toxicology (EUROTOX) /51./. 13.09.2015-16.09.2015, Porto] R&D Projects: GA AV ČR SAV-15-01 Institutional support: RVO:68081715 Keywords : proteins * retinoic acid isomers Subject RIV: CB - Analytical Chemistry, Separation

  17. Retinoic acid differentially affects in vitro proliferation, differentiation and mineralization of two fish bone-derived cell lines: different gene expression of nuclear receptors and ECM proteins.

    Fernández, Ignacio; Tiago, Daniel M; Laizé, Vincent; Leonor Cancela, M; Gisbert, Enric

    2014-03-01

    Retinoic acid (RA), the main active metabolite of vitamin A, regulates vertebrate morphogenesis through signaling pathways not yet fully understood. Such process involves the specific activation of retinoic acid and retinoid X receptors (RARs and RXRs), which are nuclear receptors of the steroid/thyroid hormone receptor superfamily. Teleost fish are suitable models to study vertebrate development, such as skeletogenesis. Cell systems capable of in vitro mineralization have been developed for several fish species and may provide new insights into the specific cellular and molecular events related to vitamin A activity in bone, complementary to in vivo studies. This work aims at investigating the in vitro effects of RA (0.5 and 12.5 μM) on proliferation, differentiation and extracellular matrix (ECM) mineralization of two gilthead seabream bone-derived cell lines (VSa13 and VSa16), and at identifying molecular targets of its action through gene expression analysis. RA induced phenotypic changes and cellular proliferation was inhibited in both cell lines in a cell type-dependent manner (36-59% in VSa13 and 17-46% in VSa16 cells). While RA stimulated mineral deposition in VSa13 cell cultures (50-62% stimulation), it inhibited the mineralization of extracellular matrix in VSa16 cells (11-57% inhibition). Expression of hormone receptor genes (rars and rxrs), and extracellular matrix-related genes such as matrix and bone Gla proteins (mgp and bglap), osteopontin (spp1) and type I collagen (col1a1) were differentially regulated upon exposure to RA in proliferating, differentiating and mineralizing cultures of VSa13 and VSa16 cells. Altogether, our results show: (i) RA affects proliferative and mineralogenic activities in two fish skeletal cell types and (ii) that during phenotype transitions, specific RA nuclear receptors and bone-related genes are differentially expressed in a cell type-dependent manner. PMID:24291400

  18. Interactions of methoxyacetic acid with androgen receptor

    Endocrine disruptive compounds (EDC) alter hormone-stimulated, nuclear receptor-dependent physiological and developmental processes by a variety of mechanisms. One recently identified mode of endocrine disruption is through hormone sensitization, where the EDC modulates intracellular signaling pathways that control nuclear receptor function, thereby regulating receptor transcriptional activity indirectly. Methoxyacetic acid (MAA), the primary, active metabolite of the industrial solvent ethylene glycol monomethyl ether and a testicular toxicant, belongs to this EDC class. Modulation of nuclear receptor activity by MAA could contribute to the testicular toxicity associated with MAA exposure. In the present study, we evaluated the impact of MAA on the transcriptional activity of several nuclear receptors including the androgen receptor (AR), which plays a pivotal role in the development and maturation of spermatocytes. AR transcriptional activity is shown to be increased by MAA through a tyrosine kinase signaling pathway that involves PI3-kinase. In a combinatorial setting with AR antagonists, MAA potentiated the AR response without significantly altering the EC50 for androgen responsiveness, partially alleviating the antagonistic effect of the anti-androgens. Finally, MAA treatment of TM3 mouse testicular Leydig cells markedly increased the expression of Cyp17a1 and Shbg while suppressing Igfbp3 expression by ∼ 90%. Deregulation of these genes may alter androgen synthesis and action in a manner that contributes to MAA-induced testicular toxicity.

  19. Isoflurane inhibits embryonic stem cell self-renewal through retinoic acid receptor.

    Liu, Sheng; Zhang, Lei; Liu, Yi; Shen, Xia; Yang, Longqiu

    2015-08-01

    The commonly used inhalation anesthetic isoflurane could permeate rapidly through the placental barrier and induce toxicity to the central nervous system of the developing fetus. However, the effects of isoflurane in utero during early gestation are unknown. We therefore treated pregnant mice with 1.4% isoflurane for 2h per day for three days at day3.5 (E3.5) to day6.5 (E6.5) to investigated the toxicity of isoflurane. Pregnant mice were executed and the fetal mice were weighed and observed. Mouse ESCs (E14) was exposed to 2% isoflurane for 6h. Twenty-four hours later, self-renewal was examined with AP staining. Effects of isoflurane on the expression of RAR-γ were examined using Western blot. As a result, anesthesia with 1.4% isoflurane for 2 hour per day for 3 days reduced fetal growth and development. Isoflurane decreased self-renewal and the expression stemness genes (Nanog, Oct4, Sox2, and Lin28) in mESCs. Vitamin A attenuated the effects of isoflurane inducing self-renewal inhibition. In summary, Anesthesia with 1.4% isoflurane for 2h per day for 3 days reduced fetal growth and development. Moreover, isoflurane inhibits mESCs self-renewal through retinoic acid receptor. PMID:26349971

  20. Homo- and heterodimers of the retinoid X receptor (RXR) activated transcription in yeast.

    Heery, D M; Pierrat, B.; Gronemeyer, H; P. Chambon; Losson, R

    1994-01-01

    The polymorphic nature of sequences which act as retinoic acid response elements (RAREs and RXREs) in transactivation assays in mammalian cells, suggests that elements consisting of a direct repetition of a half site motif, separated by 1 to 5 base pairs (DR1 to DR5), are targets for retinoic acid (RA) signalling. In a previous report we showed that in yeast cells, heterodimers of the retinoic acid receptors RAR alpha and RXR alpha were required for efficient transcription of a reporter gene ...

  1. Characterization of a retinoic acid responsive element isolated by whole genome PCR.

    Costa-Giomi, M P; Gaub, M P; Chambon, P; Abarzúa, P

    1992-01-01

    We have used whole PCR in an attempt to isolate novel retinoic acid (RA) responsive genes. We cloned several small genomic fragments from total human DNA containing putative retinoic acid responsive elements (RAREs) selected by direct binding to the retinoic acid receptor alpha (RAR alpha). We report here that an oligonucleotide containing a sequence from one of the cloned human DNA fragments, and referred to as alpha 1, functions as an authentic RARE. It is shown that both RAR alpha and RAR beta produced in Cos cells as well as in vitro translated RAR alpha bind directly and sequence-specifically to the alpha 1RARE. By mutational analysis it is demonstrated that the alpha 1RARE consists of an imperfect direct repeat of the estrogen- and thyroid hormone-related AGGTCA half-site motif separated by a 5 bp spacer. The orientation and spacing of the half-site repeats are shown to play a critical role in RAR recognition. When cloned upstream of a TK-Luc reporter, the alpha 1RARE is shown to confer responsiveness to RA in an orientation-independent fashion in F9 and CV-1 cells. The magnitude of the RA response mediated by the alpha 1RARE differed in these cell lines. Images PMID:1320257

  2. Regulating Chondrogenesis of Human Mesenchymal Stromal Cells with a Retinoic Acid Receptor-Beta Inhibitor: Differential Sensitivity of Chondral Versus Osteochondral Development

    Solvig Diederichs

    2014-05-01

    Full Text Available Aim: Main objective was to investigate whether the synthetic retinoic acid receptor (RAR-β antagonist LE135 is able to drive in vitro chondrogenesis of human mesenchymal stromal cells (MSCs or improve differentiation by suppressing hypertrophic chondrocyte development. Methods: Chondrogenesis of human bone marrow and adipose tissue-derived MSCs was induced in micromass pellet culture for six weeks. Effects of LE135 alone and in combinatorial treatment with TGF-β on deposition of cartilaginous matrix including collagen type II and glycosaminoglycans, on deposition of non-hyaline cartilage collagens type I and X, and on hypertrophy markers including alkaline phosphatase (ALP, indian hedghehog (IHH and matrix metalloproteinase (MMP-13 were assessed. Results: LE135 was no inducer of chondrogenesis and failed to stimulate deposition of collagen type II and glycosaminoglycans. Moreover, addition of LE135 to TGF-β-treated pellets inhibited cartilaginous matrix deposition and gene expression of COL2A1. In contrast, non-hyaline cartilage collagens were less sensitive to LE135 and hypertrophy markers remained unaffected. Conclusion: This demonstrates a differential sensitivity of chondral versus endochondral differentiation pathways to RARβ signaling; however, opposite to the desired direction. The relevance of trans-activating versus trans-repressing RAR signaling, including effects on activator protein (AP-1 is discussed and implications for overcoming current limits of hMSC chondrogenesis are considered.

  3. Fatty acids activate a chimera of the clofibric acid-activated receptor and the glucocorticoid receptor.

    Göttlicher, M; Widmark, E; Q. Li; Gustafsson, J.A.

    1992-01-01

    Peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643 have been shown to activate PPAR (peroxisome proliferator-activated receptor), a member of the steroid nuclear receptor superfamily. We have cloned the cDNA from the rat that is homologous to that from the mouse [Issemann, I. & Green, S. (1990) Nature (London) 347, 645-650], which encodes a 97% similar protein with a particularly well-conserved putative ligand-binding domain. To search for physiologically occurring acti...

  4. Effects and mechanism of retinoic acid receptors on brain development%视黄酸核受体在脑发育中的作用及机制

    王蓉; 李廷玉

    2004-01-01

    维生素A(vitamin A,VA)是人体必需的重要微量营养素,它在人体的视觉、免疫、生长发育及细胞分化等方面发挥广泛的生理学效应,一直都是营养学界研究的热点。VA的作用主要通过其体内活性代谢产物视黄酸(retinoic acid,RA)介导两大类视黄酸核受体:RARs(retinoic acid receptors)和RXRs (retinoid-X re-

  5. HAL-RAR PROCEDURE IN HEMORRHOIDAL DISEASE MANAGEMENT

    D. Lăzescu

    2010-08-01

    Full Text Available Introduction: HAL-RAR is a new, minimally invasive, safe and efficient tehniques in the treatment of hemorrhoidal disease who combines in one procedure HAL (Hemorrhoidal Artery Ligation with mucopexy (RAR, prolapsed piles “lifting”. Methods: We performed HAL-RAR procedure on 118 patients (50 females and 68 males with ages between 21 and 76 years with hemorrhoids grade II-IV (4,23% grade II, 24,57% grade III and 71,18% grade IV. Postoperative follow-up consisted in examination a week after procedure, then interrogatory and/or examination at 1,6 and 12 months thereafter, postoperative comfort, professional reimbursement and patient satisfaction were the main parameters we checked out. Results: After procedure 80 of 118 patients had pain for 1-3 days, 35 patients between 3 and 7 days and 3 of them for more than 7 days. Most of operated patients (66,10% returned to work in the first 3 days after procedure, 25,42% after 3-7 days and only 8,48% after more than 7 days. HAL-RAR promptly resolved all patients’ complaints; postoperative complications were less and minor, recurrence occurred only in 2 of 118 treated patients and satisfaction level was consistently high. Conclusions: HAL-RAR method is a minimally invasive method, less painful, applicable to ambulatory patient which provides a good alternative to any of the other methods of treatment of symptomatic hemorrhoids. Although the rate of relapse of hemorrhoidal disease requires a longer record and remains a subject assessed, no major complications and, especially, no risk sphincter distance and the possibility to repeat the procedure in case of recurrence.

  6. Fatty acid binding receptors in intestinal physiology and pathophysiology

    Kaemmerer, Elke; Plum, Patrick; Klaus, Christina; Weiskirchen, Ralf; Liedtke, Christian; Adolf, Maximilian; Schippers, Angela; Wagner, Norbert; Reinartz, Andrea; Gassler, Nikolaus

    2010-01-01

    Free fatty acids are essential dietary components and recognized as important molecules in the maintenance of cellular homeostasis. In the last decade, the molecular pathways for free fatty acid sensing in the gastrointestinal tract have been further elucidated by molecular identification and functional characterization of fatty acid binding receptors. These sensing molecules belong to the family of G protein-coupled receptors. In the intestine, four important receptors have been described so...

  7. Pharmacology of bile acid receptors: Evolution of bile acids from simple detergents to complex signaling molecules.

    Copple, Bryan L; Li, Tiangang

    2016-02-01

    For many years, bile acids were thought to only function as detergents which solubilize fats and facilitate the uptake of fat-soluble vitamins in the intestine. Many early observations; however, demonstrated that bile acids regulate more complex processes, such as bile acids synthesis and immune cell function through activation of signal transduction pathways. These studies were the first to suggest that receptors may exist for bile acids. Ultimately, seminal studies by many investigators led to the discovery of several bile acid-activated receptors including the farnesoid X receptor, the vitamin D receptor, the pregnane X receptor, TGR5, α5 β1 integrin, and sphingosine-1-phosphate receptor 2. Several of these receptors are expressed outside of the gastrointestinal system, indicating that bile acids may have diverse functions throughout the body. Characterization of the functions of these receptors over the last two decades has identified many important roles for these receptors in regulation of bile acid synthesis, transport, and detoxification; regulation of glucose utilization; regulation of fatty acid synthesis and oxidation; regulation of immune cell function; regulation of energy expenditure; and regulation of neural processes such as gastric motility. Through these many functions, bile acids regulate many aspects of digestion ranging from uptake of essential vitamins to proper utilization of nutrients. Accordingly, within a short time period, bile acids moved beyond simple detergents and into the realm of complex signaling molecules. Because of the important processes that bile acids regulate through activation of receptors, drugs that target these receptors are under development for the treatment of several diseases, including cholestatic liver disease and metabolic syndrome. In this review, we will describe the various bile acid receptors, the signal transduction pathways activated by these receptors, and briefly discuss the physiological processes that

  8. Expression pattern of the RAR alpha-PML fusion gene in acute promyelocytic leukemia.

    Alcalay, M; Zangrilli, D; Fagioli, M; Pandolfi, P P; Mencarelli, A; Lo Coco, F; Biondi, A; Grignani, F; Pelicci, P G

    1992-06-01

    Two chimeric genes, PML-RAR alpha and RAR alpha-PML, are formed as a consequence of the acute promyelocytic leukemia (APL)-specific reciprocal translocation of chromosomes 15 and 17 [t(15;17)]. PML-RAR alpha is expressed as a fusion protein. We investigated the organization and expression pattern of the RAR alpha-PML gene in a series of APL patients representative of the molecular heterogeneity of the t(15;17) and found (i) two types of RAR alpha-PML mRNA junctions (RAR alpha exon 2/PML exon 4 or RAR alpha exon 2/PML exon 7) that maintain the RAR alpha and PML longest open reading frames aligned and are the result of chromosome 15 breaking at two different sites; and (ii) 10 different RAR alpha-PML fusion transcripts that differ for the assembly of their PML coding exons. A RAR alpha-PML transcript was present in most, but not all, APL patients. PMID:1317574

  9. Ionotropic excitatory amino acid receptor ligands. Synthesis and pharmacology of a new amino acid AMPA antagonist

    Madsen, U; Sløk, F A; Stensbøl, T B;

    2000-01-01

    We have previously described the potent and selective (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor agonist, (RS)-2-amino-3-(3-carboxy-5-methyl-4-isoxazolyl)propionic acid (ACPA), and the AMPA receptor antagonist (RS)-2-amino-3-[3-(carboxymethoxy)-5-methyl-4...... excitatory amino acid (EAA) receptors using receptor binding and electrophysiological techniques, and for activity at metabotropic EAA receptors using second messenger assays. Compounds 1 and 4 were essentially inactive. (RS)-2-Amino-3-[3-(2-carboxyethyl)-5-methyl-4-isoxazolyl]propionic acid (ACMP, 2), on......-isoxazolyl]propionic acid (AMOA). Using these AMPA receptor ligands as leads, a series of compounds have been developed as tools for further elucidation of the structural requirements for activation and blockade of AMPA receptors. The synthesized compounds have been tested for activity at ionotropic...

  10. Transcriptomic Analysis of Murine Embryos Lacking Endogenous Retinoic Acid Signaling

    Marie Paschaki; Carole Schneider; Muriel Rhinn; Christelle Thibault-Carpentier; Doulaye Dembélé; Karen Niederreither; Pascal Dollé

    2013-01-01

    Retinoic acid (RA), an active derivative of the liposoluble vitamin A (retinol), acts as an important signaling molecule during embryonic development, regulating phenomenons as diverse as anterior-posterior axial patterning, forebrain and optic vesicle development, specification of hindbrain rhombomeres, pharyngeal arches and second heart field, somitogenesis, and differentiation of spinal cord neurons. This small molecule directly triggers gene activation by binding to nuclear receptors (RAR...

  11. N-methyl-D-aspartic acid receptor agonists

    Madsen, U; Frydenvang, Karla Andrea; Ebert, B;

    1996-01-01

    (R,S)-2-Amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid [(R,S)-AMAA, 4] is a potent and selective agonist at the N-methyl-D-aspartic acid (NMDA) subtype of excitatory amino acid receptors. Using the Ugi "four-component condensation" method, the two diastereomers (2R)- and (2S)-2-[3-(benzylox...

  12. Retinoic acid synthesis and functions in early embryonic development

    Kam Richard Kin Ting

    2012-03-01

    Full Text Available Abstract Retinoic acid (RA is a morphogen derived from retinol (vitamin A that plays important roles in cell growth, differentiation, and organogenesis. The production of RA from retinol requires two consecutive enzymatic reactions catalyzed by different sets of dehydrogenases. The retinol is first oxidized into retinal, which is then oxidized into RA. The RA interacts with retinoic acid receptor (RAR and retinoic acid X receptor (RXR which then regulate the target gene expression. In this review, we have discussed the metabolism of RA and the important components of RA signaling pathway, and highlighted current understanding of the functions of RA during early embryonic development.

  13. The technical development and application of a recirculating aquaculture respirometer system (RARS) for fish metabolism studies

    Stiller, Kevin Torben

    2016-01-01

    In dieser Arbeit wurde ein Recirculating Aquaculture Respirometre System (RARS) technisch entwickelt und die Einsatzmöglichkeiten in verschiedenen metabolischen Studien an Fischen unter Einbeziehung der Futtermittelverwertung evaluiert. Kapitel 1 stellt das RARS und die eingebauten online Messgeräte vor. Die Funktionalität des RARS wurde durch einige Beispielmessungen an Regenbogenforellen (Oncorhynchus mykiss) und Steinbutt, (Scophthalmus maximus) gezeigt. Im Kapitel 2 wurden über 8 W...

  14. The retinoic acid signaling pathway regulates anterior/posterior patterning in the nerve cord and pharynx of amphioxus, a chordate lacking neural crest

    Escriva, Hector; Holland, Nicholas D.; Gronemeyer, Hinrich; Laudet, Vincent; Holland, Linda Z.

    2002-01-01

    Amphioxus, the closest living invertebrate relative of the vertebrates, has a notochord, segmental axial musculature, pharyngeal gill slits and dorsal hollow nerve cord, but lacks neural crest. In amphioxus, as in vertebrates, exogenous retinoic acid (RA) posteriorizes the embryo. The mouth and gill slits never form, AmphiPax1, which is normally downregulated where gill slits form, remains upregulated and AmphiHox1 expression shifts anteriorly in the nerve cord. To dissect the role of RA signaling in patterning chordate embryos, we have cloned the single retinoic acid receptor (AmphiRAR), retinoid X receptor (AmphiRXR) and an orphan receptor (AmphiTR2/4) from amphioxus. AmphiTR2/4 inhibits AmphiRAR-AmphiRXR-mediated transactivation in the presence of RA by competing for DR5 or IR7 retinoic acid response elements (RAREs). The 5' untranslated region of AmphiTR2/4 contains an IR7 element, suggesting possible auto- and RA-regulation. The patterns of AmphiTR2/4 and AmphiRAR expression during embryogenesis are largely complementary: AmphiTR2/4 is strongly expressed in the cerebral vesicle (homologous to the diencephalon plus anterior midbrain), while AmphiRAR expression is high in the equivalent of the hindbrain and spinal cord. Similarly, while AmphiTR2/4 is expressed most strongly in the anterior and posterior thirds of the endoderm, the highest AmphiRAR expression is in the middle third. Expression of AmphiRAR is upregulated by exogenous RA and completely downregulated by the RA antagonist BMS009. Moreover, BMS009 expands the pharynx posteriorly; the first three gill slit primordia are elongated and shifted posteriorly, but do not penetrate, and additional, non-penetrating gill slit primordia are induced. Thus, in an organism without neural crest, initiation and penetration of gill slits appear to be separate events mediated by distinct levels of RA signaling in the pharyngeal endoderm. Although these compounds have little effect on levels of AmphiTR2/4 expression, RA

  15. Study on the relationship between the RAR-β gene expressive defection and its methylation

    高艳萍; 李敏; 张颖颖; 王翰; 贺小红; 王泽华

    2007-01-01

    Objective To observe the expression of RAR-β gene in SiHa, HeLa,C33A and CasKi cell lines of cervical carcinoma and to investigate the role of methylated RAR-β in its expressive defection. Methods Reverse transcription polymerase chain reaction (RT-PCR) was used to analyze the mRNA expression of RAR-β gene. Immunohistochemistry and Western Blot were used to analyze the protein expression of RAR-β gene in four cervical cancer cell lines as well as the influence of 5-Aza-cdR on gene expressive defection. Meth...

  16. Transcriptional Factors Mediating Retinoic Acid Signals in the Control of Energy Metabolism

    Rui Zhang

    2015-06-01

    Full Text Available Retinoic acid (RA, an active metabolite of vitamin A (VA, is important for many physiological processes including energy metabolism. This is mainly achieved through RA-regulated gene expression in metabolically active cells. RA regulates gene expression mainly through the activation of two subfamilies in the nuclear receptor superfamily, retinoic acid receptors (RARs and retinoid X receptors (RXRs. RAR/RXR heterodimers or RXR/RXR homodimers bind to RA response element in the promoters of RA target genes and regulate their expressions upon ligand binding. The development of metabolic diseases such as obesity and type 2 diabetes is often associated with profound changes in the expressions of genes involved in glucose and lipid metabolism in metabolically active cells. RA regulates some of these gene expressions. Recently, in vivo and in vitro studies have demonstrated that status and metabolism of VA regulate macronutrient metabolism. Some studies have shown that, in addition to RARs and RXRs, hepatocyte nuclear factor 4α, chicken ovalbumin upstream promoter-transcription factor II, and peroxisome proliferator activated receptor β/δ may function as transcriptional factors mediating RA response. Herein, we summarize current progresses regarding the VA metabolism and the role of nuclear receptors in mediating RA signals, with an emphasis on their implication in energy metabolism.

  17. Promiscuous Seven Transmembrane Receptors Sensing L-α-amino Acids

    Smajilovic, Sanela; Wellendorph, Petrine; Bräuner-Osborne, Hans

    2014-01-01

    A number of nutrient sensing seven trans-membrane (7TM) receptors have been identified and characterized over the past few years. While the sensing mechanisms to carbohydrates and free fatty acids are well understood, the molecular basis of amino acid sensing has recently come to the limelight. T...

  18. Bile acid derivatives as ligands of the farnesoid x receptor: molecular determinants for bile acid binding and receptor modulation.

    Gioiello, Antimo; Cerra, Bruno; Mostarda, Serena; Guercini, Chiara; Pellicciari, Roberto; Macchiarulo, Antonio

    2014-01-01

    Bile acids are a peculiar class of steroidal compounds that never cease to amaze. From being simple detergents with a primary role in aiding the absorption of fats and fat-soluble vitamins, bile acids are now widely considered as crucial hormones endowed with genomic and non-genomic functions that are mediated by their interaction with several proteins including the nuclear receptor Farnesoid X Receptor (FXR). Taking advantages of the peculiar properties of bile acids in interacting with the FXR receptor, several biliary derivatives have been synthesized and tested as FXR ligands. The availability of these compounds has contributed to characterize the receptor from a structural, patho-physiological and therapeutic standpoint. Among these, obeticholic acid is a first-in-class FXR agonist that is demonstrating hepatoprotective effects upon FXR activation in patients with liver diseases such as primary biliary cirrhosis and nonalcoholic steatohepatitis. This review provides an historical overview of the rationale behind the discovery of obeticholic acid and chemical tools generated to depict the molecular features and bio-pharmacological relevance of the FXR receptor, as well as to summarize structure-activity relationships of bile acid-based FXR ligands so far reported. PMID:25388535

  19. [Interactions between dopamine receptor and NMDA/type A γ-aminobutyric acid receptors].

    Chen, Hui-Ying; Wei, Ting-Jia; Weng, Jing-Jin; Qin, Jiang-Yuan; Huang, Xi; Su, Ji-Ping

    2016-04-25

    Type A γ-aminobutyric acid receptors (GABAAR) and N-methyl-D-aspartate receptors (NMDAR) are the major inhibitory and excitatory receptors in the central nervous system, respectively. Co-expression of the receptors in the synapse may lead to functional influence between receptors, namely receptor interaction. The interactions between GABAAR and NMDAR can be either positive or negative. However, the mechanisms of interaction between the two receptors remain poorly understood, and potential mechanisms include (1) through a second messenger; (2) by receptors trafficking; (3) by direct interaction; (4) by a third receptor-mediation. Dopamine is the most abundant catecholamine neurotransmitter in the brain, and its receptors, dopamine receptors (DR) can activate multiple signaling pathways. Earlier studies on the interaction between DR and GABAAR/NMDAR have shown some underlying mechanisms, suggesting that DR could mediate the interaction between GABAAR and NMDAR. This paper summarized some recent progresses in the studies of the interaction between DR and NMDAR/GABAAR, providing a further understanding on the interaction between NMDAR and GABAAR mediated by DR. PMID:27108906

  20. Retinoic acid signaling and mouse embryonic stem cell differentiation: Cross talk between genomic and non-genomic effects of RA.

    Rochette-Egly, Cécile

    2015-01-01

    Retinoic acid (RA), the active derivative of vitamin A, a fat-soluble vitamin, plays key roles in cell growth and differentiation by activating nuclear receptors, RARs (α, β and γ), which are ligand dependent regulators of transcription. The past years highlighted several novelties in the field that increased the complexity of RA effects. Indeed, in addition to its classical genomic effects, RA also has extranuclear and non-transcriptional effects. RA induces the rapid and transient activation of kinase cascades, which are integrated in the nucleus via the phosphorylation of RARs at a conserved serine residue located in the N-terminal domain and their coregulators. In order to investigate the relevance of RARs' phosphorylation in cell differentiation, mouse embryonic stem (mES) cells were used as a model. When treated with RA, these pluripotent cells give rise to neuronal cells. Cells invalidated for each RAR were generated as well as stable rescue lines expressing RARs mutated in phosphor acceptor sites. Such a strategy revealed that RA-induced neuronal differentiation involves the RARγ2 subtype and requires RARγ2 phosphorylation. Moreover, in gene expression profiling experiments, the phosphorylated form of RARγ2 was found to regulate a small subset of genes through binding a novel RA response element consisting of two direct repeats with a 7 base pair spacer. These new findings suggest an important role for RAR phosphorylation during cell differentiation, and pave the way for further investigations with other cell types and during embryonic development. This article is part of a Special Issue entitled Linking transcription to physiology in lipodomics. PMID:24768681

  1. Obeticholic acid, a synthetic bile acid agonist of the farnesoid X receptor, attenuates experimental autoimmune encephalomyelitis

    Peggy P. Ho; Steinman, Lawrence

    2016-01-01

    Bile acids bind to the nuclear hormone receptor, farnesoid X receptor (FXR). This bile acid–FXR interaction regulates bile acid synthesis, transport, and cholesterol metabolism. Recently, drugs targeting FXR activation have been reported to treat both liver and intestinal inflammatory diseases in both animal models and human clinical trials. Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system and serves as an animal model for ...

  2. The Expression of Bone Morphogenetic Protein 2 and Matrix Metalloproteinase 2 through Retinoic Acid Receptor Beta Induced by All-Trans Retinoic Acid in Cultured ARPE-19 Cells.

    Zhenya Gao

    Full Text Available All-trans retinoic acid (ATRA plays an important role in ocular development. Previous studies found that retinoic acid could influence the metabolism of scleral remodeling by promoting retinal pigment epithelium (RPE cells to secrete secondary signaling factors. The purpose of this study was to investigate whether retinoic acid affected secretion of bone morphogenetic protein 2 (BMP-2 and matrix metalloproteinase 2 (MMP-2 and to explore the signaling pathway of retinoic acid in cultured acute retinal pigment epithelial 19 (ARPE-19 cells.The effects of ATRA (concentrations from 10-9 to 10-5 mol/l on the expression of retinoic acid receptors (RARs in ARPE-19 cells were examined at the mRNA and protein levels using reverse transcription-polymerase chain reaction (RT-PCR and western blot assay, respectively. The effects of treating ARPE-19 cells with ATRA concentrations ranging from 10-9 to 10-5 mol/l for 24 h and 48 h or with 10-6mol/l ATRA at different times ranging from 6h to 72h were assessed using real-time quantitative PCR (qPCR and enzyme-linked immunosorbent assay (ELISA. The contribution of RARβ-induced activation of ARPE-19 cells was confirmed using LE135, an antagonist of RARβ.RARβ mRNA levels significantly increased in the ARPE-19 cells treated with ATRA for 24h and 48h. These increases in RARβ mRNA levels were dose dependent (at concentrations of 10-9 to 10-5 mol/l with a maximum effect observed at 10-6 mol/l. There were no significant changes in the mRNA levels of RARα and RARγ. Western blot assay revealed that RARβ protein levels were increased significantly in a time-dependent manner in ARPE-19 cells treated with 10-6 mol/l ATRA from 12 h to 72 h, with a marked increase observed at 24 h and 48 h. The upregulation of RARβ and the ATRA-induced secretion in ARPE-19 cells could be inhibited by the RARβ antagonist LE135.ATRA induced upregulation of RARβ in ARPE-19 cells and stimulated these cells to secrete BMP-2 and MMP-2.

  3. The Expression of Bone Morphogenetic Protein 2 and Matrix Metalloproteinase 2 through Retinoic Acid Receptor Beta Induced by All-Trans Retinoic Acid in Cultured ARPE-19 Cells

    Gao, Zhenya; Huo, Lijun; Cui, Dongmei; Yang, Xiao; Zeng, Junwen

    2016-01-01

    Purpose All-trans retinoic acid (ATRA) plays an important role in ocular development. Previous studies found that retinoic acid could influence the metabolism of scleral remodeling by promoting retinal pigment epithelium (RPE) cells to secrete secondary signaling factors. The purpose of this study was to investigate whether retinoic acid affected secretion of bone morphogenetic protein 2 (BMP-2) and matrix metalloproteinase 2 (MMP-2) and to explore the signaling pathway of retinoic acid in cultured acute retinal pigment epithelial 19 (ARPE-19) cells. Methods The effects of ATRA (concentrations from 10−9 to 10−5 mol/l) on the expression of retinoic acid receptors (RARs) in ARPE-19 cells were examined at the mRNA and protein levels using reverse transcription-polymerase chain reaction (RT-PCR) and western blot assay, respectively. The effects of treating ARPE-19 cells with ATRA concentrations ranging from 10−9 to 10−5 mol/l for 24 h and 48 h or with 10-6mol/l ATRA at different times ranging from 6h to 72h were assessed using real-time quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA). The contribution of RARβ-induced activation of ARPE-19 cells was confirmed using LE135, an antagonist of RARβ. Results RARβ mRNA levels significantly increased in the ARPE-19 cells treated with ATRA for 24h and 48h. These increases in RARβ mRNA levels were dose dependent (at concentrations of 10−9 to 10−5 mol/l) with a maximum effect observed at 10−6 mol/l. There were no significant changes in the mRNA levels of RARα and RARγ. Western blot assay revealed that RARβ protein levels were increased significantly in a time-dependent manner in ARPE-19 cells treated with 10−6 mol/l ATRA from 12 h to 72 h, with a marked increase observed at 24 h and 48 h. The upregulation of RARβ and the ATRA-induced secretion in ARPE-19 cells could be inhibited by the RARβ antagonist LE135. Conclusion ATRA induced upregulation of RARβ in ARPE-19 cells and stimulated

  4. Retinoid X Receptor Agonists Upregulate Genes Responsible for the Biosynthesis of All-Trans-Retinoic Acid in Human Epidermis.

    Wu, Lizhi; Chaudhary, Sandeep C; Atigadda, Venkatram R; Belyaeva, Olga V; Harville, Steven R; Elmets, Craig A; Muccio, Donald D; Athar, Mohammad; Kedishvili, Natalia Y

    2016-01-01

    UAB30 is an RXR selective agonist that has been shown to have potential cancer chemopreventive properties. Due to high efficacy and low toxicity, it is currently being evaluated in human Phase I clinical trials by the National Cancer Institute. While UAB30 shows promise as a low toxicity chemopreventive drug, the mechanism of its action is not well understood. In this study, we investigated the effects of UAB30 on gene expression in human organotypic skin raft cultures and mouse epidermis. The results of this study indicate that treatment with UAB30 results in upregulation of genes responsible for the uptake and metabolism of all-trans-retinol to all-trans-retinoic acid (ATRA), the natural agonist of RAR nuclear receptors. Consistent with the increased expression of these genes, the steady-state levels of ATRA are elevated in human skin rafts. In ultraviolet B (UVB) irradiated mouse skin, the expression of ATRA target genes is found to be reduced. A reduced expression of ATRA sensitive genes is also observed in epidermis of mouse models of UVB-induced squamous cell carcinoma and basal cell carcinomas. However, treatment of mouse skin with UAB30 prior to UVB irradiation prevents the UVB-induced decrease in expression of some of the ATRA-responsive genes. Considering its positive effects on ATRA signaling in the epidermis and its low toxicity, UAB30 could be used as a chemoprophylactic agent in the treatment of non-melanoma skin cancer, particularly in organ transplant recipients and other high risk populations. PMID:27078158

  5. Retinoid X Receptor Agonists Upregulate Genes Responsible for the Biosynthesis of All-Trans-Retinoic Acid in Human Epidermis.

    Lizhi Wu

    Full Text Available UAB30 is an RXR selective agonist that has been shown to have potential cancer chemopreventive properties. Due to high efficacy and low toxicity, it is currently being evaluated in human Phase I clinical trials by the National Cancer Institute. While UAB30 shows promise as a low toxicity chemopreventive drug, the mechanism of its action is not well understood. In this study, we investigated the effects of UAB30 on gene expression in human organotypic skin raft cultures and mouse epidermis. The results of this study indicate that treatment with UAB30 results in upregulation of genes responsible for the uptake and metabolism of all-trans-retinol to all-trans-retinoic acid (ATRA, the natural agonist of RAR nuclear receptors. Consistent with the increased expression of these genes, the steady-state levels of ATRA are elevated in human skin rafts. In ultraviolet B (UVB irradiated mouse skin, the expression of ATRA target genes is found to be reduced. A reduced expression of ATRA sensitive genes is also observed in epidermis of mouse models of UVB-induced squamous cell carcinoma and basal cell carcinomas. However, treatment of mouse skin with UAB30 prior to UVB irradiation prevents the UVB-induced decrease in expression of some of the ATRA-responsive genes. Considering its positive effects on ATRA signaling in the epidermis and its low toxicity, UAB30 could be used as a chemoprophylactic agent in the treatment of non-melanoma skin cancer, particularly in organ transplant recipients and other high risk populations.

  6. Retinoic Acid-mediated Nuclear Receptor Activation and Hepatocyte Proliferation

    Bushue, Nathan; Wan, Yu-Jui Yvonne

    2016-01-01

    Due to their well-known differentiation and apoptosis-inducing abilities, retinoic acid (RA) and its analogs have strong anti-cancer efficacy in human cancers. However, in vivo RA is a liver mitogen. While speculation has persisted that RA-mediated signaling is likely involved in hepatocyte proliferation during liver regeneration, direct evidence is still required. Findings in support of this proposition include observations that a release of retinyl palmitate (the precursor of RA) occurs in liver stellate cells following liver injury. Nevertheless, the biological action of this released vitamin A is virtually unknown. More likely is that the released vitamin A is converted to RA, the biological form, and then bound to a specific receptor (retinoid x receptor; RXRα), which is most abundantly expressed in the liver. Considering the mitogenic effects of RA, the RA-activated RXRα would likely then influence hepatocyte proliferation and liver tissue repair. At present, the mechanism by which RA stimulates hepatocyte proliferation is largely unknown. This review summarizes the activation of nuclear receptors (peroxisome proliferator activated receptor-α, pregnane x receptor, constitutive androstane receptor, and farnesoid x receptor) in an RXRα dependent manner to induce hepatocyte proliferation, providing a link between RA and its proliferative role.

  7. Molecular pharmacology of homologues of ibotenic acid at cloned metabotropic glutamic acid receptors

    Bräuner-Osborne, Hans; Nielsen, B; Krogsgaard-Larsen, P

    We have studied the effects of the enantiomers of 2-amino-3-(3-hydroxyisoxazol-5-yl)propionic acid (homoibotenic acid, HIBO) and analogues substituted with a methyl, bromo or butyl group in the four position of the ring at cloned metabotropic glutamate (mGlu) receptors expressed in Chinese hamste...

  8. Bile acid nuclear receptor FXR and digestive system diseases

    Lili Ding

    2015-03-01

    Full Text Available Bile acids (BAs are not only digestive surfactants but also important cell signaling molecules, which stimulate several signaling pathways to regulate some important biological processes. The bile-acid-activated nuclear receptor, farnesoid X receptor (FXR, plays a pivotal role in regulating bile acid, lipid and glucose homeostasis as well as in regulating the inflammatory responses, barrier function and prevention of bacterial translocation in the intestinal tract. As expected, FXR is involved in the pathophysiology of a wide range of diseases of gastrointestinal tract, including inflammatory bowel disease, colorectal cancer and type 2 diabetes. In this review, we discuss current knowledge of the roles of FXR in physiology of the digestive system and the related diseases. Better understanding of the roles of FXR in digestive system will accelerate the development of FXR ligands/modulators for the treatment of digestive system diseases.

  9. Retinoic acid receptor alpha is associated with tamoxifen resistance in breast cancer

    Johansson, Henrik J; Sanchez, Betzabe C.; Mundt, Filip; Forshed, Jenny; Kovacs, Aniko; Panizza, Elena; Hultin-Rosenberg, Lina; Lundgren, Bo; Martens, Ulf; Máthé, Gyöngyvér; Yakhini, Zohar; Helou, Khalil; Krawiec, Kamilla; Kanter, Lena; Hjerpe, Anders

    2013-01-01

    About one-third of oestrogen receptor alpha-positive breast cancer patients treated with tamoxifen relapse. Here we identify the nuclear receptor retinoic acid receptor alpha as a marker of tamoxifen resistance. Using quantitative mass spectrometry-based proteomics, we show that retinoic acid receptor alpha protein networks and levels differ in a tamoxifen-sensitive (MCF7) and a tamoxifen-resistant (LCC2) cell line. High intratumoural retinoic acid receptor alpha protein levels also correlate...

  10. Soman- or kainic acid-induced convulsions decrease muscarinic receptors but not benzodiazepine receptors

    [3H]Quinuclidinyl benzilate (QNB) binding to muscarinic receptors decreased in the rat forebrain after convulsions induced by a single dose of either soman, a potent inhibitor of acetylcholinesterase, or kainic acid, an excitotoxin. A Rosenthal plot revealed that the receptors decreased in number rather than affinity. When the soman-induced convulsions were blocked, the decrease in muscarinic receptors at 3 days was less extensive than when convulsions occurred and at 10 days they approached control levels in most of the brain areas. The most prominent decrements in QNB binding were in the piriform cortex where the decline in QNB binding is probably related to the extensive convulsion-associated neuropathology. The decrements in QNB binding after convulsions suggest that the convulsive state leads to a down-regulation of muscarinic receptors in some brain areas. In contrast to the decrease in QNB binding after convulsions, [3H]flunitrazepam binding to benzodiazepine receptors did not change even in the piriform cortex where the loss in muscarinic receptors was most prominent. Thus, it appears that those neuronal processes that bear muscarinic receptors are more vulnerable to convulsion-induced change than those with benzodiazepine receptors

  11. Activity of L-alpha-amino acids at the promiscuous goldfish odorant receptor 5.24

    Christiansen, Bolette; Wellendorph, Petrine; Bräuner-Osborne, Hans

    The goldfish odorant receptor 5.24 is a member of family C of G protein-coupled receptors and is closely related to the human receptor GPRC6A. Receptor 5.24 has previously been shown to have binding affinity for L-alpha-amino acids, especially the basic amino acids arginine and lysine. Here we re...

  12. Downregulation of retinoic acid receptor-β2expression is linked to aberrant methylation in esophageal squamous cell carcinoma cell lines

    Zhong-Min Liu; Fang Ding; Ming-Zhou Guo; Li-Yong Zhang; Min Wu; Zhi-Hua Liu

    2004-01-01

    AIM: To study the role of hypermethylation in the loss ofretinoic acid receptorβ2(RARβ2) in esophageal squamous cell carcinoma (ESCC).METHODS: The role of hypermethylation in RAR,β2 gene silencing in 6 ESCC cell lines was determined by methylationspecific PCR (MSP), and its methylation status was compared with RARβ2 mRNA expression by RT-PCR. The MSP results were confirmed by bisulfite sequencing of RARβ2promoter regions. RESULTS: Methylation was detected in 4 of the 6 cell lines, and the expression of RARβ2was markedly downregulated in 3 of the 4 methylated cell lines. The expression of RARβ2was restored in one RARβ2-downregulated cell line with the partial demethylation of promoter region of RARβ after 5aza-2'-deoxycytidine (5-aza-dc) treatment.CONCLUSION: The methylation of the 5' region may play an important role in the downregulation of RARβ2 in someESCC cell lines, suggesting that multiple mechanisms contribute to the loss of RARβ2expression in ESCC cell lines. This study may have clinical applications for treatment and prevention of ESCC.

  13. Adrenergic receptors and gastric acid secretion in dogs. The influence of beta 2-receptors

    Gottrup, F; Hovendal, C; Bech, K; Andersen, D

    1984-01-01

    The action of adrenergic subtypes of receptors in gastric acid secretion is still uncertain. The purpose of this study was to establish the influence of beta 2-adrenoceptors in the regulation of gastric secretion in conscious gastric fistula dogs. A dose-related inhibitory effect of beta 2...

  14. Molecular basis for amino acid sensing by family C G-protein-coupled receptors

    Wellendorph, Petrine; Bräuner-Osborne, Hans

    2009-01-01

    -alpha;-amino acid receptor G-protein-coupled receptor family C, group 6, subtype A (GPRC6A) and seven orphan receptors. Aside from the orphan receptors, the family C GPCRs are dimeric receptors characterized by a large extracellular Venus flytrap domain which bind the endogenous agonists. Except from the GABA(B1...

  15. The lactate receptor, G-protein-coupled receptor 81/hydroxycarboxylic acid receptor 1

    Morland, Cecilie; Lauritzen, Knut Huso; Puchades, Maja;

    2015-01-01

    We have proposed that lactate is a “volume transmitter” in the brain and underpinned this by showing that the lactate receptor, G-protein-coupled receptor 81 (GPR81, also known as HCA1 or HCAR1), which promotes lipid storage in adipocytes, is also active in the mammalian brain. This includes the ...

  16. Identification of COUP-TFII Orphan Nuclear Receptor as a Retinoic Acid-Activated Receptor

    Kruse, Schoen W; Suino-Powell, Kelly; Zhou, X Edward; Kretschman, Jennifer E; Reynolds, Ross; Vonrhein, Clemens; Xu, Yong; Wang, Liliang; Tsai, Sophia Y; Tsai, Ming-Jer; Xu, H Eric [Baylor; (Van Andel); (Globel Phasing); (Grand Valley)

    2010-01-12

    The chicken ovalbumin upstream promoter-transcription factors (COUP-TFI and II) make up the most conserved subfamily of nuclear receptors that play key roles in angiogenesis, neuronal development, organogenesis, cell fate determination, and metabolic homeostasis. Although the biological functions of COUP-TFs have been studied extensively, little is known of their structural features or aspects of ligand regulation. Here we report the ligand-free 1.48 {angstrom} crystal structure of the human COUP-TFII ligand-binding domain. The structure reveals an autorepressed conformation of the receptor, where helix {alpha}10 is bent into the ligand-binding pocket and the activation function-2 helix is folded into the cofactor binding site, thus preventing the recruitment of coactivators. In contrast, in multiple cell lines, COUP-TFII exhibits constitutive transcriptional activity, which can be further potentiated by nuclear receptor coactivators. Mutations designed to disrupt cofactor binding, dimerization, and ligand binding, substantially reduce the COUP-TFII transcriptional activity. Importantly, retinoid acids are able to promote COUP-TFII to recruit coactivators and activate a COUP-TF reporter construct. Although the concentration needed is higher than the physiological levels of retinoic acids, these findings demonstrate that COUP-TFII is a ligand-regulated nuclear receptor, in which ligands activate the receptor by releasing it from the autorepressed conformation.

  17. Selective potentiation of alpha 1 glycine receptors by ginkgolic acid

    Galyna Maleeva

    2015-10-01

    Full Text Available Glycine receptors (GlyRs belong to the superfamily of pentameric cys-loop receptor-operated channels and are involved in numerous physiological functions, including movement, vision and pain. In search for compounds performing subunit-specific modulation of GlyRs we studied action of ginkgolic acid, an abundant Ginkgo biloba product. Using patch-clamp recordings, we analysed the effects of ginkgolic acid in concentrations from 30nM to 25µM on α1- α3 and α1/β configurations of GlyR and on GABAARs expressed in cultured CHO-K1 cells and mouse neuroblastoma (N2a cells. Ginkgolic acid caused an increase in the amplitude of currents mediated by homomeric α1 and heteromeric α1/β GlyRs and provoked a left-shift of the concentration-dependent curves for glycine. Even at high concentrations (10-25 µM ginkgolic acid was not able to augment ionic currents mediated by α2 and α3 GlyRs, or by GABAAR consisting of α1/β2/γ2 subunits. Mutation of three residues (T59A/A261G/A303S in the α2 GlyR subunit to the corresponding ones from the α1 converted the action of ginkgolic acid to potentiation with a distinct decrease in EC50 for glycine, suggesting an important role for these residues in modulation by ginkgolic acid. Our results suggest that ginkgolic acid is a novel selective enhancer of α1 GlyRs

  18. Disseminated Exfoliative Dermatitis Associated with All-Transretinoic Acid in the Treatment of Acute Promyelocytic Leukemia

    Yonal Ipek; Dogru Hulya; Aktan Melih

    2012-01-01

    Acute promyelocytic leukemia (APL) is a biologically and clinically separate type of acute myeloid leukemia characterized by a translocation involving the retinoic acid receptor-alpha (RARa) locus on chromosome 17, the great majority of which is t(15; 17)(q24.1; q21.1) (Collins (1998), Melnick and Licht (1999), and Grimwade (1999)). Retinoic acid is a critical ligand in the differentiation pathway of multiple tissues, mediated through binding to an RAR. All-trans retinoic acid (ATRA) is a sub...

  19. The Function of Retinol Dehydrogenase 1 in Retinoic Acid Synthesis and Metabolic Regulation

    Krois, Charles Robert

    2011-01-01

    Retinol dehydrogenases (RDH) convert retinol into retinal, the intermediate in the biosynthesis of retinoic acid. All-trans-retinoic acid (atRA) regulates gene transcription and/or translation through retinoic acid receptors (RARs) and PPARδ (1). To test function of Rdh1, an efficient (Vmax/Km) and widely distributed RDH (2), our lab created Rdh1 knockout (KO) mice (3). Initial study of Rdh1-KO mice determined that when fed a low or vitamin A-deficient (VAD) diet, Rdh1-KO mice gain 33% ...

  20. Thyroid hormone receptor can modulate retinoic acid-mediated axis formation in frog embryogenesis.

    Banker, D E; Eisenman, R N

    1993-01-01

    Thyroid hormone receptor acts as a hormone-dependent transcriptional transactivator and as a transcriptional repressor in the absence of thyroid hormone. Specifically, thyroid hormone receptor can repress retinoic acid-induced gene expression through interactions with retinoic acid receptor. (Retinoic acid is a potent teratogen in the frog Xenopus laevis, acting at early embryonic stages to interfere with the formation of anterior structures. Endogenous retinoic acid is thought to act in norm...

  1. Hyaluronic acid induces activation of the κ-opioid receptor.

    Barbara Zavan

    Full Text Available INTRODUCTION: Nociceptive pain is one of the most common types of pain that originates from an injury involving nociceptors. Approximately 60% of the knee joint innervations are classified as nociceptive. The specific biological mechanism underlying the regulation of nociceptors is relevant for the treatment of symptoms affecting the knee joint. Intra-articular administration of exogenous hyaluronic acid (HA in patients with osteoarthritis (OA appears to be particularly effective in reducing pain and improving patient function. METHODS: We performed an in vitro study conducted in CHO cells that expressed a panel of opioid receptors and in primary rat dorsal root ganglion (DRG neurons to determine if HA induces the activation of opioid peptide receptors (OPr using both aequorin and the fluorescent dye Fura-2/AM. RESULTS: Selective agonists and antagonists for each OPr expressed on CHO cells were used to test the efficacy of our in vitro model followed by stimulation with HA. The results showed that HA induces stimulatory effects on the κ receptor (KOP. These effects of HA were also confirmed in rat DRG neurons, which express endogenously the OPr. CONCLUSIONS: HA activates the KOP receptor in a concentration dependent manner, with a pEC(50 value of 7.57.

  2. Receptor for protons: First observations on Acid Sensing Ion Channels.

    Krishtal, Oleg

    2015-07-01

    The history of ASICs began in 1980 with unexpected observation. The concept of highly selective Na(+) current gated by specific receptors for protons was not easily accepted. It took 16 years to get these receptor/channels cloned and start a new stage in their investigation. "The receptor for protons" became ASIC comprising under this name a family of receptor/channels ubiquitous for mammalian nervous system, both peripheral and central. The role of ASICs as putative nociceptors was suggested almost immediately after their discovery. This role subsequently was proven in many forms of pain-related phenomena. Many other functions of ASICs have been also found or primed for speculations both in physiology and in disease. Despite the width of field and strength of efforts, numerous basic questions are to be answered before we understand how the local changes in pH in the nervous tissue transform into electric and messenger signaling via ASICs as transducers. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'. PMID:25582296

  3. Low Resolution Structure of RAR1-GST-Tag Fusion Protein in Solution

    RAR1 is a protein required for resistance mediated by many R genes and function upstream of signaling pathways leading to H2O2 accumulation. The structure and conformation of RAR1-GST-Tag fusion protein from barley (Hordeum vulgare) in solution was studied by the small angle scattering of synchrotron radiation. It was found that the dimer of RAR1-GST-Tag protein is characterized in solution by radius of gyration RG = 6.19 nm and maximal intramolecular vector Dmax = 23 nm. On the basis of the small angle scattering of synchrotron radiation SAXS data two bead models obtained by ab initio modeling are proposed. Both models show elongated conformations. We also concluded that molecules of fusion protein form: dimers in solution via interaction of GST domains. (authors)

  4. Subdural effusions and lack of early pontocerebellar hypoplasia in siblings with RARS2 mutations.

    Kastrissianakis, Katherina; Anand, Geetha; Quaghebeur, Gerardine; Price, Sue; Prabhakar, Prab; Marinova, Jasmina; Brown, Garry; McShane, Tony

    2013-12-01

    Mutations in the recently described RARS2 gene encoding for mitochondrial arginyl-transfer RNA synthetase give rise to a disorder characterised by early onset seizures, progressive microcephaly and developmental delay. The disorder was named pontocerebellar hypoplasia type 6 (PCH6) based on the corresponding radiological findings observed in the original cases. We report two siblings with the RARS2 mutation who displayed typical clinical features of PCH6, but who had distinct neuroimaging features. Early scans showed marked supratentorial, rather than infratentorial, atrophy, and the pons remained preserved throughout. One sibling also had bilateral subdural effusions at presentation. The deceleration in head growth pointed to an evolving genetic/metabolic process giving rise to cerebral atrophy and secondary subdural effusions. RARS2 mutations should be considered in infants presenting with seizures, subdural effusions, decelerating head growth and evidence of cerebral atrophy even in the absence of pontocerebellar hypoplasia on imaging. PMID:24047924

  5. Bile Acids Trigger GLP-1 Release Predominantly by Accessing Basolaterally Located G Protein–Coupled Bile Acid Receptors

    Brighton, Cheryl A.; Rievaj, Juraj; Kuhre, Rune E; Glass, Leslie L; Schoonjans, Kristina; Holst, Jens J.; Gribble, Fiona M.; Reimann, Frank

    2015-01-01

    Bile acids are well-recognized stimuli of glucagon-like peptide-1 (GLP-1) secretion. This action has been attributed to activation of the G protein–coupled bile acid receptor GPBAR1 (TGR5), although other potential bile acid sensors include the nuclear farnesoid receptor and the apical sodium-coupled bile acid transporter ASBT. The aim of this study was to identify pathways important for GLP-1 release and to determine whether bile acids target their receptors on GLP-1–secreting L-cells from t...

  6. Retinoic acid signalling is activated in the postischemic heart and may influence remodelling.

    Dusan Bilbija

    Full Text Available BACKGROUND: All-trans retinoic acid (atRA, an active derivative of vitamin A, regulates cell differentiation, proliferation and cardiac morphogenesis via transcriptional activation of retinoic acid receptors (RARs acting on retinoic acid response elements (RARE. We hypothesized that the retinoic acid (RA signalling pathway is activated in myocardial ischemia and postischemic remodelling. METHODS AND FINDINGS: Myocardial infarction was induced through ligating the left coronary artery in mice. In vivo cardiac activation of the RARs was measured by imaging RARE-luciferase reporter mice, and analysing expression of RAR target genes and proteins by real time RT-PCR and western blot. Endogenous retinoids in postinfarcted hearts were analysed by triple-stage liquid chromatography/tandem mass spectrometry. Cardiomyocytes (CM and cardiofibroblasts (CF were isolated from infarcted and sham operated RARE luciferase reporter hearts and monitored for RAR activity and expression of target genes. The effect of atRA on CF proliferation was evaluated by EdU incorporation. Myocardial infarction increased thoracic RAR activity in vivo (p<0.001, which was ascribed to the heart through ex vivo imaging (p = 0.002 with the largest signal 1 week postinfarct. This was accompanied by increased cardiac gene and protein expression of the RAR target genes retinol binding protein 1 (p = 0.01 for RNA, p = 0,006 for protein and aldehyde dehydrogenase 1A2 (p = 0.04 for RNA, p = 0,014 for protein, while gene expression of cytochrome P450 26B1 was downregulated (p = 0.007. Concomitantly, retinol accumulated in the infarcted zone (p = 0.02. CM and CF isolated from infarcted hearts had higher luminescence than those from sham operated hearts (p = 0.02 and p = 0.008. AtRA inhibited CF proliferation in vitro (p = 0.02. CONCLUSION: The RA signalling pathway is activated in postischemic hearts and may play a role in regulation of damage and

  7. Mechanism of retinoid receptors in inhibiting proliferation and inducing apoptosis of human melanoma cell line A375

    NIU Xin-wu; PENG Zhen-hui; FENG Jie; MA Hui-qun; LIU Chao; YUAN Jing-yi

    2005-01-01

    @@ Malignant melanoma is a common cancer of skin. Its incidence is growing rapidly in recent years,1 however, there is no effective therapy for this cancer. Retinoids are metabolites or derivatives of vitamin A. They are essential for growth, differentiation, and maintenance of epithelial tissues.2 Previous studies showed that retinoids could inhibit growth of many kinds of malignant tumor cell lines and induce its apoptosis,3,4 including malignant melanoma cell lines.5 Some retinoids have therapeutic action to malignant melanoma, such as all-trans retinoic acid (ATRA) and 13-cis-RA.6,7 Retinoids take effects mainly through two kinds of nuclear receptors, retinoic acid receptor (RAR) and retinoic acid X receptor (RXR). In this study, we have investigated the effects of diverse retinoids and receptor agonists in inhibiting proliferation and inducing apoptosis of human melanoma cell line A375.

  8. RAGE is a nucleic acid receptor that promotes inflammatory responses to DNA

    Sirois, Cherilyn M.; Jin, Tengchuan; Miller, Allison L.; Bertheloot, Damien; Nakamura, Hirotaka; Horvath, Gabor L.; Mian, Abubakar; Jiang, Jiansheng; Schrum, Jacob; Bossaller, Lukas; Pelka, Karin; Garbi, Natalio; Brewah, Yambasu; Tian, Jane; Chang, ChewShun

    2013-01-01

    Recognition of DNA and RNA molecules derived from pathogens or self-antigen is one way the mammalian immune system senses infection and tissue damage. Activation of immune signaling receptors by nucleic acids is controlled by limiting the access of DNA and RNA to intracellular receptors, but the mechanisms by which endosome-resident receptors encounter nucleic acids from the extracellular space are largely undefined. In this study, we show that the receptor for advanced glycation end-products...

  9. Concomitant action of structural elements and receptor phosphorylation determines arrestin-3 interaction with the free fatty acid receptor FFA4

    Butcher, Adrian J; Hudson, Brian D; Shimpukade, Bharat; Alvarez-Curto, Elisa; Prihandoko, Rudi; Ulven, Trond; Milligan, Graeme; Tobin, Andrew B

    2014-01-01

    In addition to being nutrients, free fatty acids act as signaling molecules by activating a family of G protein-coupled receptors. Among these is FFA4, previously called GPR120, which responds to medium and long chain fatty acids, including health-promoting ω-3 fatty acids, which have been...

  10. Interaction of the C-terminal acidic domain of the insulin receptor with histone modulates the receptor kinase activity.

    Baron, V; Kaliman, P; Alengrin, F; Van Obberghen, E

    1995-04-01

    In this study, we investigated the role of the insulin receptor domain 1270-1280, an acid-rich sequence located in the receptor C-terminus. Antipeptide IgG raised against this sequence were obtained and used to analyze their effect on receptor function. Antipeptide IgG inhibited receptor autophosphorylation at Tyr1146, Tyr1150 and Tyr1151. These sites are known to be key modulators of the receptor activity. Autophosphorylation at other sites may also have been inhibited. The antipeptide antibody decreased the receptor kinase activity measured with poly(Glu80Tyr20) and a synthetic peptide corresponding to the proreceptor sequence 1142-1158. We provide evidence that the effect of the antibody on substrate phosphorylation may result from the control of the phosphorylation level of the receptor. Concerning the action of the antipeptide IgG on the receptor kinase activity, histone did not behave similarly to poly(Glu80Tyr20). The antibody recognizing sequence 1270-1280 competed with histone for an overlapping binding site. Histone also modulated insulin receptor autophosphorylation, supporting the idea that interference with domain 1270-1280 alters the receptor kinase. Our data suggest that the acidic region including residues 1270-1280 of the insulin receptor C-terminus is involved in the following events: (a) receptor binding with histone, an exogenous substrate of the receptor kinase, and (b) the regulation of receptor autophosphorylation and kinase activity. Based on these observations, we would like to propose that this insulin receptor domain could interact with cellular proteins modulating the receptor kinase. PMID:7744039

  11. Expression and localization of the omega-3 fatty acid receptor GPR120 in human term placenta

    Lager, Susanne; Ramirez, Vanessa I.; Gaccioli, Francesca; Jansson, Thomas; Powell, Theresa L.

    2014-01-01

    Fatty acids can function as signaling molecules, acting through receptors in the cytosol or on the cell surface. G-Protein Receptor (GPR)120 is a membrane-bound receptor mediating anti-inflammatory and insulin-sensitizing effects of the omega-3 fatty acid docohexaenoic acid (DHA). GPR120 dysfunction is associated with obesity in humans. Cellular localization of GPR120 and the influence of maternal obesity on GPR120 protein expression in the placenta are unknown. Herein we demonstrate that GPR...

  12. Biological roles and therapeutic potential of hydroxy-carboxylic acid receptors

    Kashan eAhmed

    2011-10-01

    Full Text Available In the recent past, deorphanization studies have described intermediates of energy metabolism to activate G protein-coupled receptors (GPCRs and to thereby regulate metabolic functions. GPR81, GPR109A and GPR109B, formerly known as the nicotinic acid receptor family, are encoded by clustered genes and share a high degree of sequence homology. Recently, hydroxy-carboxylic acids were identified as endogenous ligands of GPR81, GPR109A and GPR109B, and therefore these receptors have been placed into a novel receptor family of hydroxy-carboxylic acid (HCA receptors. The HCA1 receptor (GPR81 is activated by the glycolytic metabolite 2-hydroxy-propionic acid (lactate, the HCA2 receptor is activated by the ketone body 3-hydroxy-butyric acid and the HCA3 receptor (GPR109B is a receptor for the β-oxidation intermediate 3-hydroxy-octanoic acid. While HCA1 and HCA2 receptors are present in most mammalian species, the HCA3 receptor is exclusively found in humans and higher primates. HCA receptors are expressed in adipose tissue and mediate anti-lipolytic effects in adipocytes through Gi-type G-protein-dependent inhibition of adenylyl cyclase. HCA2 and HCA3 inhibit lipolysis during conditions of increased β-oxidation such as prolonged fasting, whereas HCA1 mediates the anti-lipolytic effects of insulin in the fed state. As HCA2 is a receptor for the established anti-dyslipidemic drug nicotinic acid, HCA1 and HCA3 also represent promising drug targets and several synthetic ligands for HCA receptors have been developed. In this article, we will summarize the deorphanization and pharmacological characterization of HCA receptors. Moreover, we will discuss recent progress in elucidating the physiological and pathophysiological role to further evaluate the therapeutic potential of the HCA receptor family for the treatment of metabolic disease.

  13. Distinct Phosphorylation Clusters Determine the Signaling Outcome of Free Fatty Acid Receptor 4/G Protein-Coupled Receptor 120

    Prihandoko, Rudi; Alvarez-Curto, Elisa; Hudson, Brian D; Butcher, Adrian J; Ulven, Trond; Miller, Ashley M; Tobin, Andrew B; Milligan, Graeme

    2016-01-01

    phosphoacceptor sites to alanine completely prevented phosphorylation of mFFA4 but did not limit receptor coupling to extracellular signal regulated protein kinase 1 and 2 (ERK1/2) activation. Rather, an inhibitor of Gq/11proteins completely prevented receptor signaling to ERK1/2. By contrast, the recruitment of......It is established that long-chain free fatty acids includingω-3 fatty acids mediate an array of biologic responses through members of the free fatty acid (FFA) receptor family, which includes FFA4. However, the signaling mechanisms and modes of regulation of this receptor class remain unclear. Here...... arrestin 3, receptor internalization, and activation of Akt were regulated by mFFA4 phosphorylation. The analysis of mFFA4 phosphorylation-dependent signaling was extended further by selective mutations of the phosphoacceptor sites. Mutations within cluster 2 did not affect agonist activation of Akt but...

  14. Bile Acid-Activated Receptors, Intestinal Microbiota, and the Treatment of Metabolic Disorders.

    Fiorucci, Stefano; Distrutti, Eleonora

    2015-11-01

    The composition of the bile acid pool is a function of the microbial metabolism of bile acids in the intestine. Perturbations of the microbiota shape the bile acid pool and modulate the activity of bile acid-activated receptors (BARs) even beyond the gastrointestinal tract, triggering various metabolic axes and altering host metabolism. Bile acids, in turn, can also regulate the composition of the gut microbiome at the highest taxonomic levels. Primary bile acids from the host are preferential ligands for the farnesoid X receptor (FXR), while secondary bile acids from the microbiota are ligands for G-protein-coupled bile acid receptor 1 (GPBAR1). In this review, we examine the role of bile acid signaling in the regulation of intestinal microbiota and how changes in bile acid composition affect human metabolism. Bile acids may offer novel therapeutic modalities in inflammation, obesity, and diabetes. PMID:26481828

  15. Nutrigenomic regulation of adipose tissue development - role of retinoic acid: A review.

    Wang, Bo; Yang, Qiyuan; Harris, Corrine L; Nelson, Mark L; Busboom, Jan R; Zhu, Mei-Jun; Du, Min

    2016-10-01

    To improve the efficiency of animal production, livestock have been extensively selected or managed to reduce fat accumulation and increase lean growth, which reduces intramuscular or marbling fat content. To enhance marbling, a better understanding of the mechanisms regulating adipogenesis is needed. Vitamin A has recently been shown to have a profound impact on all stages of adipogenesis. Retinoic acid, an active metabolite of vitamin A, activates both retinoic acid receptors (RAR) and retinoid X receptors (RXR), inducing epigenetic changes in key regulatory genes governing adipogenesis. Additionally, Vitamin D and folates interact with the retinoic acid receptors to regulate adipogenesis. In this review, we discuss nutritional regulation of adipogenesis, focusing on retinoic acid and its impact on epigenetic modifications of key adipogenic genes. PMID:27086067

  16. Obeticholic acid, a synthetic bile acid agonist of the farnesoid X receptor, attenuates experimental autoimmune encephalomyelitis.

    Ho, Peggy P; Steinman, Lawrence

    2016-02-01

    Bile acids are ligands for the nuclear hormone receptor, farnesoid X receptor (FXR). The bile acid-FXR interaction regulates bile acid synthesis, transport, and cholesterol metabolism. Recently, bile acid-FXR regulation has been reported to play an integral role in both hepatic and intestinal inflammation, and in atherosclerosis. In this study, we found that FXR knockout mice had more disease severity in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Obeticholic acid (6α-ethyl-chenodeoxycholic acid, 6-ECDCA), a synthetic FXR agonist, is an orally available drug that is currently in clinical trials for the treatment of inflammatory diseases such as alcoholic hepatitis, nonalcoholic steatohepatitis, and primary biliary cirrhosis. When we treated mice exhibiting established EAE with 6-ECDCA, or the natural FXR ligand chenodeoxycholic acid (CDCA), clinical disease was ameliorated by (i) suppressing lymphocyte activation and proinflammatory cytokine production; (ii) reducing CD4(+) T cells and CD19(+) B cell populations and their expression of negative checkpoint regulators programmed cell death protein 1 (PD1), programmed death-ligand 1 (PD-L1), and B and T lymphocyte attenuator (BTLA); (iii) increasing CD8(+) T cells and PD1, PDl-1, and BTLA expression; and (iv) reducing VLA-4 expression in both the T- and B-cell populations. Moreover, adoptive transfer of 6-ECDCA- or CDCA-treated donor cells failed to transfer disease in naive recipients. Thus, we show that FXR functions as a negative regulator in neuroinflammation and we highlight that FXR agonists represent a potential previously unidentified therapy for MS. PMID:26811456

  17. Regulation of vitamin D receptor expression by retinoic acid receptor alpha in acute myeloid leukemia cells.

    Marchwicka, Aleksandra; Cebrat, Małgorzata; Łaszkiewicz, Agnieszka; Śnieżewski, Łukasz; Brown, Geoffrey; Marcinkowska, Ewa

    2016-05-01

    Acute myeloid leukemia (AML) is the predominant acute leukemia among adults, characterized by an accumulation of malignant immature myeloid precursors. A very promising way to treat AML is differentiation therapy using either all-trans-retinoic acid (ATRA) or 1,25-dihydroxyvitamin D3 (1,25D), or the use of both these differentiation-inducing agents. However, the effect of combination treatment varies in different AML cell lines, and this is due to ATRA either down- or up-regulating transcription of vitamin D receptor (VDR) in the cells examined. The mechanism of transcriptional regulation of VDR in response to ATRA has not been fully elucidated. Here, we show that the retinoic acid receptor α (RARα) is responsible for regulating VDR transcription in AML cells. We have shown that a VDR transcriptional variant, originating in exon 1a, is regulated by RARα agonists in AML cells. Moreover, in cells with a high basal level of RARα protein, the VDR gene is transcriptionally repressed as long as RARα agonist is absent. In these cells down-regulation of the level of RARα leads to increased expression of VDR. We consider that our findings provide a mechanistic background to explain the different outcomes from treating AML cell lines with a combination of ATRA and 1,25D. PMID:26969398

  18. 1,2,3-triazolyl amino acids as AMPA receptor ligands

    Stanley, Nathan J.; Pedersen, Daniel Sejer; Nielsen, Birgitte;

    2010-01-01

    The central nervous system glutamate receptors are an important target for drug discovery. Herein we report initial investigations into the synthesis and glutamate receptor activity of 1,2,3-triazolyl amino acids. Two compounds were found to be selective AMPA receptor ligands, which warrant further...

  19. Antibody against the insulin receptor causes disappearance of insulin receptors in 3T3-L1 cells: a possible explanation of antibody-induced insulin resistance.

    Grunfeld, C.

    1984-01-01

    The effect of a rabbit antibody induced against the rat insulin receptor (RAR) was tested using cultured 3T3-L1 fat cells. As previously seen with antibodies against the insulin receptor from patients with the type B syndrome of insulin resistance and acanthosis nigricans, RAR acutely mimicked the action of insulin by stimulating deoxyglucose uptake. After prolonged exposure of 3T3-L1 cells to RAR, insulinomimetic activity was lost and the cells became resistant to the action of insulin. This...

  20. Tetrazolyl isoxazole amino acids as ionotropic glutamate receptor antagonists: synthesis, modelling and molecular pharmacology

    Frølund, Bente; Greenwood, Jeremy R; Holm, Mai Marie;

    2005-01-01

    and 1b were pharmacologically characterized in receptor binding assays, and electrophysiologically on homomeric AMPA receptors (GluR1-4), homomeric (GluR5 and GluR6) and heteromeric (GluR6/KA2) kainic acid receptors, using two-electrode voltage-clamped Xenopus laevis oocytes expressing these receptors...... kainic acid receptor subtypes (GluR5 and GluR6/KA2), showing sevenfold preference for GluR6/KA2 (Kb=19 microM). Unlike the iGluR antagonist (S)-2-amino-3-[5-tert-butyl-3-(phosphonomethoxy)-4-isoxazolyl]propionic acid [(S)-ATPO], the corresponding tetrazolyl analogue, 1b, lacks kainic acid receptor...

  1. G-Protein-Coupled Lysophosphatidic Acid Receptors and Their Regulation of AKT Signaling

    Anjum Riaz; Ying Huang; Staffan Johansson

    2016-01-01

    A hallmark of G-protein-coupled receptors (GPCRs) is their ability to recognize and respond to chemically diverse ligands. Lysophospholipids constitute a relatively recent addition to these ligands and carry out their biological functions by activating G-proteins coupled to a large family of cell-surface receptors. This review aims to highlight salient features of cell signaling by one class of these receptors, known as lysophosphatidic acid (LPA) receptors, in the context of phosphatidylinos...

  2. Enhancement of arachidonic acid signaling pathway by nicotinic acid receptor HM74A

    HM74A is a G protein-coupled receptor for nicotinic acid (niacin), which has been used clinically to treat dyslipidemia for decades. The molecular mechanisms whereby niacin exerts its pleiotropic effects on lipid metabolism remain largely unknown. In addition, the most common side effect in niacin therapy is skin flushing that is caused by prostaglandin release, suggesting that the phospholipase A2 (PLA2)/arachidonic acid (AA) pathway is involved. Various eicosanoids have been shown to activate peroxisome-proliferator activated receptors (PPAR) that play a diverse array of roles in lipid metabolism. To further elucidate the potential roles of HM74A in mediating the therapeutic effects and/or side effects of niacin, we sought to explore the signaling events upon HM74A activation. Here we demonstrated that HM74A synergistically enhanced UTP- and bradykinin-mediated AA release in a pertussis toxin-sensitive manner in A431 cells. Activation of HM74A also led to Ca2+-mobilization and enhanced bradykinin-promoted Ca2+-mobilization through Gi protein. While HM74A increased ERK1/2 activation by the bradykinin receptor, it had no effects on UTP-promoted ERK1/2 activation.Furthermore, UTP- and bradykinin-mediated AA release was significantly decreased in the presence of both MAPK kinase inhibitor PD 098059 and PKC inhibitor GF 109203X. However, the synergistic effects of HM74A were not dramatically affected by co-treatment with both inhibitors, indicating the cross-talk occurred at the receptor level. Finally, stimulation of A431 cells transiently transfected with PPRE-luciferase with AA significantly induced luciferase activity, mimicking the effects of PPARγ agonist rosiglitazone, suggesting that alteration of AA signaling pathway can regulate gene expression via endogenous PPARs

  3. Direct activation of GABAA receptors by substances in the organic acid fraction of Japanese sake.

    Izu, Hanae; Shigemori, Kensuke; Eguchi, Masaya; Kawane, Shuhei; Fujii, Shouko; Kitamura, Yuji; Aoshima, Hitoshi; Yamada, Yasue

    2017-01-01

    We investigated the effect of substances present in Japanese sake on the response of ionotropic γ-aminobutyric acid (GABA)A receptors expressed in Xenopus oocytes. Sake was fractionated by ion-exchange chromatography. The fraction containing organic acids (OA fraction) showed agonist activities on the GABAA receptor. OA fractions from sake were analyzed by capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). Of the 64 compounds identified, 13 compounds showed GABAA receptor agonist activities. Especially, l-lactic acid showed high agonist activity and its EC50 value was 37μM. Intraperitoneal injections of l-lactic acid, gluconic acid, and pyruvic acid (10, 10, and 5mg/kg BW, respectively), which showed agonistic activity on the GABAA receptor, led to significant anxiolytic effects during an elevated plus-maze test in mice. PMID:27507485

  4. Retinoic Acid Specifically Enhances Embryonic Stem Cell Metastate Marked by Zscan4.

    Tagliaferri, Daniela; De Angelis, Maria Teresa; Russo, Nicola Antonino; Marotta, Maria; Ceccarelli, Michele; Del Vecchio, Luigi; De Felice, Mario; Falco, Geppino

    2016-01-01

    Pluripotency confers Embryonic Stem Cells (ESCs) the ability to differentiate in ectoderm, endoderm, and mesoderm derivatives, producing the majority of cell types. Although the majority of ESCs divide without losing pluripotency, it has become evident that ESCs culture consists of multiple cell populations with different degrees of potency that are spontaneously induced in regular ESC culture conditions. Zscan4, a key pluripotency factor, marks ESC subpopulation that is referred to as high-level of pluripotency metastate. Here, we report that in ESC cultures treated with retinoic acid (RA), Zscan4 ESCs metastate is strongly enhanced. In particular, we found that induction of Zscan4 metastate is mediated via RA receptors (RAR-alpha, RAR-beta, and RAR-gamma), and it is dependent on phosphoinositide-3-kinase (PI3K) signaling. Remarkably, Zscan4 metastate induced by RA lacks canonical pluripotency genes Oct3/4 and Nanog but retained both self-renewal and pluripotency capabilities. Finally we demonstrated that the conditional ablation of Zscan4 subpopulation is dispensable for both endoderm and mesoderm but is required for ectoderm lineage. In conclusion, our research provides new insights about the role of RA signaling during ESCs high pluripotency metastate fluctuation. PMID:26840068

  5. Retinoic Acid Specifically Enhances Embryonic Stem Cell Metastate Marked by Zscan4.

    Daniela Tagliaferri

    Full Text Available Pluripotency confers Embryonic Stem Cells (ESCs the ability to differentiate in ectoderm, endoderm, and mesoderm derivatives, producing the majority of cell types. Although the majority of ESCs divide without losing pluripotency, it has become evident that ESCs culture consists of multiple cell populations with different degrees of potency that are spontaneously induced in regular ESC culture conditions. Zscan4, a key pluripotency factor, marks ESC subpopulation that is referred to as high-level of pluripotency metastate. Here, we report that in ESC cultures treated with retinoic acid (RA, Zscan4 ESCs metastate is strongly enhanced. In particular, we found that induction of Zscan4 metastate is mediated via RA receptors (RAR-alpha, RAR-beta, and RAR-gamma, and it is dependent on phosphoinositide-3-kinase (PI3K signaling. Remarkably, Zscan4 metastate induced by RA lacks canonical pluripotency genes Oct3/4 and Nanog but retained both self-renewal and pluripotency capabilities. Finally we demonstrated that the conditional ablation of Zscan4 subpopulation is dispensable for both endoderm and mesoderm but is required for ectoderm lineage. In conclusion, our research provides new insights about the role of RA signaling during ESCs high pluripotency metastate fluctuation.

  6. Control mechanisms of mutability: Studies on the (radiation-resistant) mutant rar-2 of Drosophila melanogaster

    The author attempts a quantitative description of the resistance factor of the 2nd chromosome (rar-2) on the mutation rate after irradiation, an explanation of the mechanism of action via an analysis of induced numerical aberration, and an analysis of the genetic position of this factor and its delimination with the aid of phenotypically visible markers. A comparison of the two strains ROeI0 and ROeI40 was to help to investigate possible modifications of the resistance factor in the strain ROeI40, obtained by further selection from ROeI0. There was no difference between the two strains as far as the effects of the resistance factor rar-2 were concerned. (orig./MG)

  7. Commercial Application of the RAR Sulfur Recovery and Tail Gas Treating Process

    Guo Hong; Zhang Songping

    2003-01-01

    The 40kt/a sulfur recovery unit for tail gas treating applying the reduction-absorption-recycling (RAR) technology is aimed at regeneration of the rich amine solution and recovery of sulfur to operate in tandem with the 1.2Mt/a diesel hydrofining unit. The process unit calibration data have revealed that the recovery of total sulfur reaches 99.86%, which is 6.65 percentage points higher than that before application of the RAR technology. The SO2 content in vented tail gas is 0.27 t/d, which is much less than the latest emission standard prescribed by the State. The factors that can affect the unit operation have been analyzed and corresponding measures have been suggested including the necessity to improve the control over the reaction temperature in the tail gas hydrogenation unit.

  8. Synthesis and pharmacology of 3-isoxazolol amino acids as selective antagonists at group I metabotropic glutamic acid receptors

    Madsen, U; Bräuner-Osborne, H; Frydenvang, Karla Andrea; Hvene, L; Johansen, T N; Nielsen, B; Sánchez, C; Stensbøl, T B; Bischoff, F; Krogsgaard-Larsen, P

    2001-01-01

    Using ibotenic acid (2) as a lead, two series of 3-isoxazolol amino acid ligands for (S)-glutamic acid (Glu, 1) receptors have been developed. Whereas analogues of (RS)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid [AMPA, (RS)-3] interact selectively with ionotropic Glu receptors (i......GluRs), the few analogues of (RS)-2-amino-3-(3-hydroxy-5-isoxazolyl)propionic acid [HIBO, (RS)-4] so far known typically interact with iGluRs as well as metabotropic Glu receptors (mGluRs). We here report the synthesis and pharmacology of a series of 4-substituted analogues of HIBO. The hexyl analogue 9 was...

  9. Bile Acids Trigger GLP-1 Release Predominantly by Accessing Basolaterally Located G Protein-Coupled Bile Acid Receptors

    Brighton, Cheryl A.; Rievaj, Juraj; Kuhre, Rune E.;

    2015-01-01

    -coupled bile acid transporter ASBT. The aim of this study was to identify pathways important for GLP-1 release and to determine whether bile acids target their receptors on GLP-1-secreting L-cells from the apical or basolateral compartment. Using transgenic mice expressing fluorescent sensors specifically in L......Bile acids are well-recognized stimuli of glucagon-like peptide-1 (GLP-1) secretion. This action has been attributed to activation of the G protein-coupled bile acid receptor GPBAR1 (TGR5), although other potential bile acid sensors include the nuclear farnesoid receptor and the apical sodium......-cells, we observed that taurodeoxycholate (TDCA) and taurolithocholate (TLCA) increased intracellular cAMP and Ca2+. In primary intestinal cultures, TDCA was a more potent GLP-1 secretagogue than taurocholate (TCA) and TLCA, correlating with a stronger Ca2+ response to TDCA. Using small-volume Ussing...

  10. Effects of a n-3 PUFA deficient diet on the expression of retinoid nuclear receptors, neurogranin and neuromodulin in rat brain

    Buaud Benjamin

    2007-05-01

    Full Text Available A lot of studies performed in rodents revealed that n-3 polyunsaturated fatty acid (PUFA deficient diets could induce deficits of learning capacities but the mechanisms involved are not well known. Retinoic acid (RA and its nuclear receptors (RAR and RXR play a central role in the maintenance of cognitive processes and synaptic plasticity via its action on target genes that are neurogranin (RC3 and neuromodulin (GAP43. Given some interferences were described between the retinoid and fatty acid signaling pathways, we investigated the effects of a _α-linolenic acid (18: 3 n-3 deficient diet on retinoic acid nuclear receptors (RAR, and RXR, on GAP43 and RC3, and on blood and brain fatty acid composition in rats at three times of diet: 3, 9 and 18 weeks. In blood and brain of these animals, we observed a severe n-3 PUFA deficit (18:3 n-3, 20:5 n-3 and particularly 22:6 n-3 associated with an increase in the n-6 PUFA content (mainly 22:5 n-6. Real-time PCR and western blot analysis allowed us to note that retinoid signaling, GAP43 and RC3 expression were affected in the striatum of the n-3 PUFA deprived rats.

  11. Retinoids stimulate fibrinogen production both in vitro (hepatocytes) and in vivo. Induction requires activation of the retinoid X receptor.

    Nicodeme, E; Nicaud, M; Issandou, M

    1995-10-01

    The in vitro effects of retinoids on fibrinogen synthesis were investigated in HepG2 cells and primary human hepatocytes. In vivo effects were studied in the rat. In HepG2 cells, maximal stimulation (twofold) of fibrinogen secretion was obtained when cells were incubated in the presence of 1 mumol/L all-trans retinoic acid (T-RA) for 24 hours. A comparable increase was observed for both de novo fibrinogen synthesis and fibrinogen beta chain mRNA level. In primary cultures of human hepatocytes, treatment with 1 mumol/L T-RA for 72 hours also gave a twofold increase in fibrinogen production. Furthermore, rats treated for 6 days with 100 mg.kg-1.d-1 T-RA presented increased fibrinogen plasma levels (110%). A selective retinoic X receptor (RXR) agonist, 4-[1-3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthyl)-ethenyl]benzoi c acid (3-methyl TTNEB), as well as 9-cis retinoic acid, a natural RXR ligand, mimicked the effects of T-RA on fibrinogen synthesis in vitro at lower concentrations. In contrast, a selective retinoic A receptor alpha (RAR alpha) agonist was a poor activator. The ED50 of the different retinoids on fibrinogen secretion by HepG2 cells was 25 nmol/L for T-RA, 4 nmol/L for 9-cis retinoic acid, 11 nmol/L for the synthetic RXR agonist, and > 500 nmol/L for the RAR alpha agonist. However, incubation of HepG2 cells with RXR agonist together with RAR alpha agonist resulted in a further increase in fibrinogen production. The secretion of two other acute-phase proteins, alpha-antichymotrypsin and caeruloplasmin, was also stimulated by retinoids in HepG2 cells but by a different regulatory mechanism.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7583541

  12. Impact of Sorbic Acid on Germinant Receptor-Dependent and -Independent Germination Pathways in Bacillus cereus▿

    Melis,, Rosanna; Nierop Groot, M.N.; Abee, T.

    2011-01-01

    Amino acid- and inosine-induced germination of Bacillus cereus ATCC 14579 spores was reversibly inhibited in the presence of 3 mM undissociated sorbic acid. Exposure to high hydrostatic pressure, Ca-dipicolinic acid (DPA), and bryostatin, an activator of PrkC kinase, negated this inhibition, pointing to specific blockage of signal transduction in germinant receptor-mediated germination.

  13. Hrs recognizes a hydrophobic amino acid cluster in cytokine receptors during ubiquitin-independent endosomal sorting.

    Amano, Yuji; Yamashita, Yuki; Kojima, Katsuhiko; Yoshino, Kazuhisa; Tanaka, Nobuyuki; Sugamura, Kazuo; Takeshita, Toshikazu

    2011-04-29

    Hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) is a component of the ESCRT-0 protein complex that captures ubiquitylated cargo proteins and sorts them to the lysosomal pathway. Although Hrs acts as a key transporter for ubiquitin-dependent endosomal sorting, we previously reported that Hrs is also involved in ubiquitin-independent endosomal sorting of interleukin-2 receptor β (IL-2Rβ). Here, we show direct interactions between bacterially expressed Hrs and interleukin-4 receptor α (IL-4Rα), indicating that their binding is not required for ubiquitylation of the receptors, similar to the case for IL-2Rβ. Examinations of the Hrs binding regions of the receptors reveal that a hydrophobic amino acid cluster in both IL-2Rβ and IL-4Rα is essential for the binding. Whereas the wild-type receptors are delivered to LAMP1-positive late endosomes, mutant receptors lacking the hydrophobic amino acid cluster are sorted to lysobisphosphatidic acid-positive late endosomes rather than LAMP1-positive late endosomes. We also show that the degradation of these mutant receptors is attenuated. Accordingly, Hrs functions during ubiquitin-independent endosomal sorting of the receptors by recognizing the hydrophobic amino acid cluster. These findings suggest the existence of a group of cargo proteins that have this hydrophobic amino acid cluster as a ubiquitin-independent sorting signal. PMID:21362618

  14. Interaction between retinoid acid receptor-related orphan receptor alpha (RORA and neuropeptide S receptor 1 (NPSR1 in asthma.

    Nathalie Acevedo

    Full Text Available Retinoid acid receptor-related Orphan Receptor Alpha (RORA was recently identified as a susceptibility gene for asthma in a genome-wide association study. To investigate the impact of RORA on asthma susceptibility, we performed a genetic association study between RORA single nucleotide polymorphisms (SNPs in the vicinity of the asthma-associated SNP (rs11071559 and asthma-related traits. Because the regulatory region of a previously implicated asthma susceptibility gene, Neuropeptide S receptor 1 (NPSR1, has predicted elements for RORA binding, we hypothesized that RORA may interact biologically and genetically with NPSR1. 37 RORA SNPs and eight NPSR1 SNPs were genotyped in the Swedish birth cohort BAMSE (2033 children and the European cross-sectional PARSIFAL study (1120 children. Seven RORA SNPs confined into a 49 kb region were significantly associated with physician-diagnosed childhood asthma. The most significant association with rs7164773 (T/C was driven by the CC genotype in asthma cases (OR = 2.0, 95%CI 1.36-2.93, p = 0.0003 in BAMSE; and 1.61, 1.18-2.19, p = 0.002 in the combined BAMSE-PARSIFAL datasets, respectively, and strikingly, the risk effect was dependent on the Gln344Arg mutation in NPSR1. In cell models, stimulation of NPSR1 activated a pathway including RORA and other circadian clock genes. Over-expression of RORA decreased NPSR1 promoter activity further suggesting a regulatory loop between these genes. In addition, Rora mRNA expression was lower in the lung tissue of Npsr1 deficient mice compared to wildtype littermates during the early hours of the light period. We conclude that RORA SNPs are associated with childhood asthma and show epistasis with NPSR1, and the interaction between RORA and NPSR1 may be of biological relevance. Combinations of common susceptibility alleles and less common functional polymorphisms may modify the joint risk effects on asthma susceptibility.

  15. Interaction between retinoid acid receptor-related orphan receptor alpha (RORA) and neuropeptide S receptor 1 (NPSR1) in asthma.

    Acevedo, Nathalie; Sääf, Annika; Söderhäll, Cilla; Melén, Erik; Mandelin, Jami; Pietras, Christina Orsmark; Ezer, Sini; Karisola, Piia; Vendelin, Johanna; Gennäs, Gustav Boije af; Yli-Kauhaluoma, Jari; Alenius, Harri; von Mutius, Erika; Doekes, Gert; Braun-Fahrländer, Charlotte; Riedler, Josef; van Hage, Marianne; D'Amato, Mauro; Scheynius, Annika; Pershagen, Göran; Kere, Juha; Pulkkinen, Ville

    2013-01-01

    Retinoid acid receptor-related Orphan Receptor Alpha (RORA) was recently identified as a susceptibility gene for asthma in a genome-wide association study. To investigate the impact of RORA on asthma susceptibility, we performed a genetic association study between RORA single nucleotide polymorphisms (SNPs) in the vicinity of the asthma-associated SNP (rs11071559) and asthma-related traits. Because the regulatory region of a previously implicated asthma susceptibility gene, Neuropeptide S receptor 1 (NPSR1), has predicted elements for RORA binding, we hypothesized that RORA may interact biologically and genetically with NPSR1. 37 RORA SNPs and eight NPSR1 SNPs were genotyped in the Swedish birth cohort BAMSE (2033 children) and the European cross-sectional PARSIFAL study (1120 children). Seven RORA SNPs confined into a 49 kb region were significantly associated with physician-diagnosed childhood asthma. The most significant association with rs7164773 (T/C) was driven by the CC genotype in asthma cases (OR = 2.0, 95%CI 1.36-2.93, p = 0.0003 in BAMSE; and 1.61, 1.18-2.19, p = 0.002 in the combined BAMSE-PARSIFAL datasets, respectively), and strikingly, the risk effect was dependent on the Gln344Arg mutation in NPSR1. In cell models, stimulation of NPSR1 activated a pathway including RORA and other circadian clock genes. Over-expression of RORA decreased NPSR1 promoter activity further suggesting a regulatory loop between these genes. In addition, Rora mRNA expression was lower in the lung tissue of Npsr1 deficient mice compared to wildtype littermates during the early hours of the light period. We conclude that RORA SNPs are associated with childhood asthma and show epistasis with NPSR1, and the interaction between RORA and NPSR1 may be of biological relevance. Combinations of common susceptibility alleles and less common functional polymorphisms may modify the joint risk effects on asthma susceptibility. PMID:23565190

  16. Agonists, antagonists and modulators of excitatory amino acid receptors in the guinea-pig myenteric plexus.

    Luzzi, S; Zilletti, L.; S.Franchi-Micheli; Gori, A M; Moroni, F

    1988-01-01

    1. The receptors for glutamic acid (L-Glu) present in the guinea-pig myenteric plexus-ileal longitudinal muscle preparation have been studied by measuring the muscle contraction induced by numerous putative endogenous agonists acting at these receptors. Furthermore, the actions of different concentrations of antagonists, glycine, Mg2+ and Ca2+ on the ileal contractions induced by L-Glu have been evaluated. 2. The EC50 values of the most common putative endogenous agonists of these receptors w...

  17. Kynurenic acid amides as novel NR2B selective NMDA receptor antagonists.

    Borza, István; Kolok, Sándor; Galgóczy, Kornél; Gere, Anikó; Horváth, Csilla; Farkas, Sándor; Greiner, István; Domány, György

    2007-01-15

    A novel series of kynurenic acid amides, ring-enlarged derivatives of indole-2-carboxamides, was prepared and identified as in vivo active NR2B subtype selective NMDA receptor antagonists. The synthesis and SAR studies are discussed. PMID:17074483

  18. Role of retinoic acid receptors in squamous-cell carcinoma in human esophagus

    Bergheim, I.; Wolfgarten, E.; Bollschweiler, E.;

    2005-01-01

    BACKGROUND: Worldwide, cancer in the esophagus ranks among the 10 most common cancers. Alterations of retinoic acid receptors (e.g. RARalpha, beta, gamma, and RXRalpha, beta, gamma) expression is considered to play an important role in development of squamous-cell carcinoma (SCC), which is the most...... common esophageal cancer. Alcohol consumption and smoking, which can alter retinoic acid receptor levels, have been identified as key risk factors in the development of carcinoma in the aero-digestive tract. Therefore, the aim of the present study was to evaluate protein levels of retinoic acid receptors...... comparing protein levels of retinoic acid receptors between normal tissue of patients with SCC and controls, RARgamma protein levels were found to be significantly higher (approximately 2.7-fold) in normal esophageal tissue of SCC patients than in esophageal tissue obtained from controls. No differences...

  19. Data for amino acid alignment of Japanese stingray melanocortin receptors with other gnathostome melanocortin receptor sequences, and the ligand selectivity of Japanese stingray melanocortin receptors

    Akiyoshi Takahashi

    2016-06-01

    Full Text Available This article contains structure and pharmacological characteristics of melanocortin receptors (MCRs related to research published in “Characterization of melanocortin receptors from stingray Dasyatis akajei, a cartilaginous fish” (Takahashi et al., 2016 [1]. The amino acid sequences of the stingray, D. akajei, MC1R, MC2R, MC3R, MC4R, and MC5R were aligned with the corresponding melanocortin receptor sequences from the elephant shark, Callorhinchus milii, the dogfish, Squalus acanthias, the goldfish, Carassius auratus, and the mouse, Mus musculus. These alignments provide the basis for phylogenetic analysis of these gnathostome melanocortin receptor sequences. In addition, the Japanese stingray melanocortin receptors were separately expressed in Chinese Hamster Ovary cells, and stimulated with stingray ACTH, α-MSH, β-MSH, γ-MSH, δ-MSH, and β-endorphin. The dose response curves reveal the order of ligand selectivity for each stingray MCR.

  20. Nicotinic acid receptor abnormalities in human skin cancer: implications for a role in epidermal differentiation.

    Yira Bermudez

    Full Text Available BACKGROUND: Chronic UV skin exposure leads to epidermal differentiation defects in humans that can be largely restored by pharmacological doses of nicotinic acid. Nicotinic acid has been identified as a ligand for the human G-protein-coupled receptors GPR109A and GPR109B that signal through G(i-mediated inhibition of adenylyl cyclase. We have examined the expression, cellular distribution, and functionality of GPR109A/B in human skin and skin derived epidermal cells. RESULTS: Nicotinic acid increases epidermal differentiation in photodamaged human skin as judged by the terminal differentiation markers caspase 14 and filaggrin. Both GPR109A and GPR109B genes are transcribed in human skin and in epidermal keratinocytes, but expression in dermal fibroblasts is below limits of detection. Receptor transcripts are greatly over-expressed in squamous cell cancers. Receptor protein in normal skin is prominent from the basal through granular layers of the epidermis, with cellular localization more dispersive in the basal layer but predominantly localized at the plasma membrane in more differentiated epidermal layers. In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i-mediated signaling. In contrast, in a squamous cell carcinoma derived cell line, receptor protein shows a more diffuse cellular localization and the receptors are nearly non-functional. CONCLUSIONS: The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s of nicotinic acid receptors in human skin homeostasis.

  1. Interactions between Human Liver Fatty Acid Binding Protein and Peroxisome Proliferator Activated Receptor Selective Drugs

    Tony Velkov

    2013-01-01

    Fatty acid binding proteins (FABPs) act as intracellular shuttles for fatty acids as well as lipophilic xenobiotics to the nucleus, where these ligands are released to a group of nuclear receptors called the peroxisome proliferator activated receptors (PPARs). PPAR mediated gene activation is ultimately involved in maintenance of cellular homeostasis through the transcriptional regulation of metabolic enzymes and transporters that target the activating ligand. Here we show that liver- (L-) FA...

  2. Castor oil induces laxation and uterus contraction via ricinoleic acid activating prostaglandin EP3 receptors

    Tunaru, Sorin; Althoff, Till F.; Nüsing, Rolf M.; Diener, Martin; Offermanns, Stefan

    2012-01-01

    Castor oil is one of the oldest drugs. When given orally, it has a laxative effect and induces labor in pregnant females. The effects of castor oil are mediated by ricinoleic acid, a hydroxylated fatty acid released from castor oil by intestinal lipases. Despite the wide-spread use of castor oil in conventional and folk medicine, the molecular mechanism by which ricinoleic acid acts remains unknown. Here we show that the EP3 prostanoid receptor is specifically activated by ricinoleic acid and...

  3. Potentiation of gamma aminobutyric acid receptors (GABAAR by Ethanol: How are inhibitory receptors affected?

    Benjamin eFörstera

    2016-05-01

    Full Text Available In recent years there has been an increase in the understanding of ethanol actions on the type A -aminobutyric acid chloride channel (GABAAR, a member of the pentameric ligand gated ion channels (pLGICs. However, the mechanism by which ethanol potentiates the complex is still not fully understood and a number of publications have shown contradictory results. Thus many questions still remain unresolved requiring further studies for a better comprehension of this effect. The present review concentrates on the involvement of GABAAR in the acute actions of ethanol and specifically focuses on the immediate, direct or indirect, synaptic and extra-synaptic modulatory effects. To elaborate on the immediate, direct modulation of GABAAR by acute ethanol exposure, electrophysiological studies investigating the importance of different subunits, and data from receptor mutants will be examined. We will also discuss the nature of the putative binding sites for ethanol based on structural data obtained from other members of the pLGICs family. Finally, we will briefly highlight the glycine gated chloride channel (GlyR, another member of the pLGIC family, as a suitable target for the development of new pharmacological tools.

  4. Unnatural agrochemical ligands for engineered abscisic acid receptors.

    Rodriguez, Pedro L; Lozano-Juste, Jorge

    2015-06-01

    Existing agrochemicals can be endowed with new applications through protein engineering of plant receptors. A recent study shows an engineered PYR1 ABA receptor can be activated by mandipropamid. Plants engineered with such PYR1 variant are responsive to this agrochemical, which confers protection against drought through activation of ABA signaling. PMID:25891067

  5. Nuclear receptor-dependent bile acid signaling is required for normal liver regeneration.

    Huang, Wendong; Ma, Ke; Zhang, Jun; Qatanani, Mohammed; Cuvillier, James; Liu, Jun; Dong, Bingning; Huang, Xiongfei; Moore, David D

    2006-04-14

    Liver mass depends on one or more unidentified humoral signals that drive regeneration when liver functional capacity is diminished. Bile acids are important liver products, and their levels are tightly regulated. Here, we identify a role for nuclear receptor-dependent bile acid signaling in normal liver regeneration. Elevated bile acid levels accelerate regeneration, and decreased levels inhibit liver regrowth, as does the absence of the primary nuclear bile acid receptor FXR. We propose that FXR activation by increased bile acid flux is a signal of decreased functional capacity of the liver. FXR, and possibly other nuclear receptors, may promote homeostasis not only by regulating expression of appropriate metabolic target genes but also by driving homeotrophic liver growth. PMID:16614213

  6. Measurements of the counting statistics on RAR-2497 and DEF x-ray film

    X-ray film is commonly used to diagnose high temperature plasmas. Quantitative analysis of the recorded film exposure requires knowledge of the counting statistics inherent to each particular film type. To address this issue, RAR-2497 and DEF film were exposed on a Manson x-ray source for multiple fluence values and photon energies. The fluctuations in the measured intensity were found by determining the statistical distribution of the recorded photon intensity using Henke's calibration tables to relate the net film density to the incident intensity. The resulting measurements of the statistical fluctuations in photon intensity are presented for each film type

  7. Measurements of the counting statistics on RAR-2497 and DEF x-ray film

    Dunham, Greg; Rochau, G. A.; Lake, P.; Nielsen-Weber, L.; Schuster, D.

    2004-10-01

    X-ray film is commonly used to diagnose high temperature plasmas. Quantitative analysis of the recorded film exposure requires knowledge of the counting statistics inherent to each particular film type. To address this issue, RAR-2497 and DEF film were exposed on a Manson x-ray source for multiple fluence values and photon energies. The fluctuations in the measured intensity were found by determining the statistical distribution of the recorded photon intensity using Henke's calibration tables to relate the net film density to the incident intensity. The resulting measurements of the statistical fluctuations in photon intensity are presented for each film type.

  8. La carrera rarámuri como metáfora de resistencia cultural

    Acuña Delgado, Ángel; Acuña Gómez, Guillermo

    2009-01-01

    ¡Quien no aguanta no vale! Dice un viejo principio rarámuri, grupo étnico ubicado en la Sierra Tarahumara, dentro de la Sierra Madre Occidental del Estado Chihuahua en México. Inmerso en un entorno ambiental ecológicamente duro para la supervivencia, se asume la idea de que “para vivir hay que ser resistente”, y así soportar la falta de agua y alimentos provocada por la sequía, el intenso frío nocturno del invierno o las largas travesías por montaña. Desde centenares de años, h...

  9. Expression of somatotropin receptor messenger ribonucleic acid in bovine tissues

    The somatotropin receptor mRNA is controlled by at least two different gene promoters that generate 2 two variants with different exon 1 sequences (1A and 1B). The location of 1A and 1B somatotropin receptor mRNA within cattle tissues and, hence, the tissue specificity of the 1A and 1B promoters are unknown. In addition, the cDNA sequence of the 1B somatotropin receptor has not been determined. Our objective, therefore, was to sequence a cDNA for the 1B somatotropin receptor and to analyze bovine tissues for expression of 1A and 1B somatotropin receptor mRNA. Twenty adult tissues and six fetal tissues were collected at slaughter from each of four cows and two fetuses. Messenger RNA was analyzed using ribonuclease protection assays. The adult liver expressed both 1A and 1B mRNA. All other adult tissues expressed 1B mRNA but not 1A mRNA. The greatest amount of 1B mRNA was detected in liver and adipose (abdominal and subcutaneous) tissues. Other tissues had approximately one-half to one-tenth of the amount of 1B mRNA in the liver or adipose tissue. Fetal tissues (including fetal liver) expressed 1B mRNA and not 1A mRNA. Based on cDNA sequencing, the protein encoded by the 1A and 1B mRNA was nearly identical. We concluded that 1A somatotropin receptor mRNA is specific to adult bovine liver. Other adult and fetal bovine tissues expressed 1B somatotropin receptor mRNA with a predicted protein sequence that was similar to the 1A somatotropin receptor

  10. Biostructural and pharmacological studies of bicyclic analogues of the 3-isoxazolol glutamate receptor agonist ibotenic acid

    Frydenvang, Karla Andrea; Pickering, Darryl S; Greenwood, Jeremy R;

    2010-01-01

    We describe an improved synthesis and detailed pharmacological characterization of the conformationally restricted analogue of the naturally occurring nonselective glutamate receptor agonist ibotenic acid (RS)-3-hydroxy-4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-7-carboxylic acid (7-HPCA, 5) at A...

  11. Herpes simplex virus infection is sensed by both Toll-like receptors and retinoic acid-inducible gene- like receptors, which synergize to induce type I interferon production

    Rasmussen, Simon Brandtoft; Jensen, Søren B; Nielsen, C;

    2009-01-01

    The innate antiviral response is initiated by pattern recognition receptors, which recognize viral pathogen-associated molecular patterns. Here we show that retinoic acid-inducible gene (RIG)-I-like receptors (RLRs) in cooperation with Toll-like receptor (TLR) 9 is required for expression of type I...

  12. The Effect of Genetic Variation of the Retinoic Acid Receptor-Related Orphan Receptor C Gene on Fatness in Cattle

    Barendse, W.; Bunch, R. J.; Kijas, J. W.; M. B. Thomas

    2007-01-01

    Genotypes at the retinoic acid receptor-related orphan receptor C (RORC) gene were associated with fatness in 1750 cattle. Ten SNPs were genotyped in RORC and the adjacent gene leucine-rich repeat neuronal 6D (LRRN6D) to map the QTL, 7 of which are in a 4.2-kb sequence around the ligand-binding domain of the RORC gene. Of the 29 inferred haplotypes for these SNPs, 2 have a combined frequency of 54.6% while the top 5 haplotypes have a combined frequency of 85.3%. The average D′ value of linkag...

  13. Treatment of type 2 diabetes by free Fatty Acid receptor agonists

    Watterson, Kenneth R; Hudson, Brian D; Ulven, Trond;

    2014-01-01

    Dietary free fatty acids (FFAs), such as ω-3 fatty acids, regulate metabolic and anti-inflammatory processes, with many of these effects attributed to FFAs interacting with a family of G protein-coupled receptors. Selective synthetic ligands for free fatty acid receptors (FFA1-4) have consequently...... removed from clinical trials due to potential liver toxicity and determining if this is a target or a ligand-specific feature is now of major importance. Pre-clinical studies also show that FFA4 agonism increases insulin sensitivity, induces weight loss, and reduces inflammation and the metabolic and anti......-inflammatory effects of short chain fatty acids (SCFAs) are linked with FFA2 and FFA3 activation. In this review, we therefore show that FFA receptor agonism is a potential clinical target for T2D treatment and discuss ongoing drug development programs within industry and academia aimed at improving the safety and...

  14. Satellite-based RAR performance simulation for measuring directional ocean wave spectrum based on SAR inversion spectrum

    REN Lin; MAO Zhihua; HUANG Haiqing; GONG Fang

    2010-01-01

    Some missions have been carried out to measure wave directional spectrum by synthetic aperture radar (SAR) and airborne real aperture radar (RAR) at a low incidence. Both them have their own advantages and limitations. Scientists hope that SAR and satellite-based RAR can complement each other for the research on wave properties in the future. For this study, the authors aim to simulate the satellite-based RAR system to validate performance for measuring the directional wave spectrum. The principal measurements are introduced and the simulation methods based on the one developed by Hauser are adopted and slightly modified. To enhance the authenticity of input spectrum and the wave spectrum measuring consistency for SAR and satellite-based RAR, the wave height spectrum inversed from Envisat ASAR data by cross spectrum technology is used as the input spectrum of the simulation system. In the process of simulation, the sea surface, backscattering signal, modulation spectrum and the estimated wave height spectrum are simulated in each look direction. Directional wave spectrum are measured based on the simulated observations from 0° to 360~. From the estimated wave spectrum, it has an 180° ambiguity like SAR, but it has no special high wave number cut off in all the direction. Finally, the estimated spectrum is compared with the input one in terms of the dominant wave wavelength, direction and SWH and the results are promising. The simulation shows that satellite-based RAR should be capable of measuring the directional wave properties. Moreover, it indicates satellite-based RAR basically can measure waves that SAR can measure.

  15. G-protein-coupled receptors for free fatty acids

    Milligan, Graeme; Ulven, Trond; Murdoch, Hannah; Hudson, Brian D

    It is becoming evident that nutrients and metabolic intermediates derived from such nutrients regulate cellular function by activating a number of cell-surface G-protein coupled receptors (GPCRs). Until now, members of the GPCR family have largely been considered as the molecular targets that...... communicate cellular signals initiated by hormones and neurotransmitters. Recently, based on tissue expression patterns of these receptors and the concept that they may elicit the production of a range of appetite- and hunger-regulating peptides, such nutrient sensing GPCRs are attracting considerable...... diseases, major challenges remain to exploit their potential for therapeutic purposes. Mostly, this is due to limited characterisation and validation of these receptors because of paucity of selective and high-potency/affinity pharmacological agents to define the detailed function and regulation of these...

  16. Synthesis, binding affinity at glutamic acid receptors, neuroprotective effects, and molecular modeling investigation of novel dihydroisoxazole amino acids

    Conti, Paola; De Amici, Marco; Grazioso, Giovanni;

    2005-01-01

    The four stereoisomers of 5-(2-amino-2-carboxyethyl)-4,5-dihydroisoxazole-3-carboxylic acid(+)-4, (-)-4, (+)-5, and (-)-5 were prepared by stereoselective synthesis of two pairs of enantiomers, which were subsequently resolved by enzymatic procedures. These four stereoisomers and the four...... stereoisomers of the bicyclic analogue 5-amino-4,5,6,6a-tetrahydro-3aH-cyclopenta[d]isoxazole-3,5-dicarboxylic acid (+)-2, (-)-2, (+)-3, and (-)-3 were tested at ionotropic and metabotropic glutamate receptor subtypes. The most potent NMDA receptor antagonists [(+)-2, (-)-4, and (+)-5] showed a significant...... derivatives showed high antagonist potency with preference for the NR2A and NR2B subtypes, with derivative (-)-4 behaving as the most potent antagonist. The biological data are discussed on the basis of homology models reported in the literature for NMDA receptors and mGluRs....

  17. Modulatory effects of unsaturated fatty acids on the binding of glucocorticoids to rat liver glucocorticoid receptors.

    Vallette, G; Vanet, A; Sumida, C; Nunez, E A

    1991-09-01

    Binding of the synthetic glucocorticoid dexamethasone to the rat liver cytosol glucocorticoid receptor was inhibited by physiological concentrations of nonesterified fatty acids as a function of increasing dose, degree of unsaturation, and chain length of the fatty acid. Polyunsaturated fatty acids were the most potent inhibitors. Scatchard analysis and Line-weaver-Burk plots of the binding data revealed that both the association constants and number of binding sites decreased and that polyunsaturated fatty acids inhibition was of a mixed non-competitive type. The dissociation rate constant of [3H]dexamethasone from glucocorticoid receptors was increased by up to 10 times in the presence of docosahexaenoic acid, whereas a competitive inhibitor like the glucocorticoid antagonist RU 38486 had no effect. Moreover, sucrose density gradient analysis showed that docosahexaenoic acid inhibited the binding of [3H] dexamethasone to both the 8.8S and 4S forms. The results strongly suggest that unsaturated fatty acids are interacting at a site on the receptor different from the hormone binding site and the heat shock protein and that by binding to a second site unsaturated fatty acids greatly change the conformation of the hormone binding site to reduce its affinity for the hormone, either partially or completely depending on the concentration and the class of the fatty acid. PMID:1874175

  18. The Pharmacology and Function of Receptors for Short-Chain Fatty Acids.

    Bolognini, Daniele; Tobin, Andrew B; Milligan, Graeme; Moss, Catherine E

    2016-03-01

    Despite some blockbuster G protein-coupled receptor (GPCR) drugs, only a small fraction (∼ 15%) of the more than 390 nonodorant GPCRs have been successfully targeted by the pharmaceutical industry. One way that this issue might be addressed is via translation of recent deorphanization programs that have opened the prospect of extending the reach of new medicine design to novel receptor types with potential therapeutic value. Prominent among these receptors are those that respond to short-chain free fatty acids of carbon chain length 2-6. These receptors, FFA2 (GPR43) and FFA3 (GPR41), are each predominantly activated by the short-chain fatty acids acetate, propionate, and butyrate, ligands that originate largely as fermentation by-products of anaerobic bacteria in the gut. However, the presence of FFA2 and FFA3 on pancreatic β-cells, FFA3 on neurons, and FFA2 on leukocytes and adipocytes means that the biologic role of these receptors likely extends beyond the widely accepted role of regulating peptide hormone release from enteroendocrine cells in the gut. Here, we review the physiologic roles of FFA2 and FFA3, the recent development and use of receptor-selective pharmacological tool compounds and genetic models available to study these receptors, and present evidence of the potential therapeutic value of targeting this emerging receptor pair. PMID:26719580

  19. 9-cis-retinoic acid inhibits activation-driven T-cell apoptosis: implications for retinoid X receptor involvement in thymocyte development.

    Yang, Y.; Vacchio, M S; Ashwell, J D

    1993-01-01

    Retinoic acid is a morphogenetic signaling molecule derived from vitamin A and involved in vertebrate development. Two groups of receptors, retinoic acid receptors and retinoid X receptors (RXRs), have been identified. All-trans-retinoic acid is the high-affinity ligand for retinoic acid receptors, and 9-cis-retinoic acid additionally binds RXRs with high affinity. Here we report that although retinoic acid has little inhibitory effect on activation-induced T-cell proliferation, it specifical...

  20. Bile Acids Induce Cdx2 Expression Through the Farnesoid X Receptor in Gastric Epithelial Cells

    Xu, Yingji; Watanabe, Toshio; Tanigawa, Tetsuya; Machida, Hirohisa; Okazaki, Hirotoshi; Yamagami, Hirokazu; Watanabe, Kenji; Tominaga, Kazunari; Fujiwara, Yasuhiro; Oshitani, Nobuhide; Arakawa, Tetsuo

    2009-01-01

    Clinical and experimental studies showed that the reflux of bile into the stomach contributes to the induction of intestinal metaplasia of the stomach and gastric carcinogenesis. Caudal-type homeobox 2 (Cdx2) plays a key role in the exhibition of intestinal phenotypes by regulating the expression of intestine-specific genes such as goblet-specific gene mucin 2 (MUC2). We investigated the involvement of the farnesoid X receptor (FXR), a nuclear receptor for bile acids, in the chenodeoxycholic ...

  1. Bile acid-induced arrhythmia is mediated by muscarinic M2 receptors in neonatal rat cardiomyocytes.

    Siti H Sheikh Abdul Kadir

    Full Text Available BACKGROUND: Intrahepatic cholestasis of pregnancy (ICP is a common disease affecting up to 5% of pregnancies and which can cause fetal arrhythmia and sudden intrauterine death. We previously demonstrated that bile acid taurocholate (TC, which is raised in the bloodstream of ICP, can acutely alter the rate and rhythm of contraction and induce abnormal calcium destabilization in cultured neonatal rat cardiomyocytes (NRCM. Apart from their hepatic functions bile acids are ubiquitous signalling molecules with diverse systemic effects mediated by either the nuclear receptor FXR or by a recently discovered G-protein coupled receptor TGR5. We aim to investigate the mechanism of bile-acid induced arrhythmogenic effects in an in-vitro model of the fetal heart. METHODS AND RESULTS: Levels of bile acid transporters and nuclear receptor FXR were studied by quantitative real time PCR, western blot and immunostaining, which showed low levels of expression. We did not observe functional involvement of the canonical receptors FXR and TGR5. Instead, we found that TC binds to the muscarinic M(2 receptor in NRCM and serves as a partial agonist of this receptor in terms of inhibitory effect on intracellular cAMP and negative chronotropic response. Pharmacological inhibition and siRNA-knockdown of the M(2 receptor completely abolished the negative effect of TC on contraction, calcium transient amplitude and synchronisation in NRCM clusters. CONCLUSION: We conclude that in NRCM the TC-induced arrhythmia is mediated by the partial agonism at the M(2 receptor. This mechanism might serve as a promising new therapeutic target for fetal arrhythmia.

  2. Comparison of sigma- and kappa-opiate receptor ligands as excitatory amino acid antagonists.

    Berry, S. C.; Dawkins, S. L.; Lodge, D.

    1984-01-01

    Using the technique of microelectrophoresis in pentobarbitone-anaesthetized cats and rats, the effects of benzomorphans, with known actions at sigma- and kappa- opioid receptors, were tested on responses of spinal neurones to amino acids and acetylcholine. The racemic mixture and both enantiomers of the sigma opiate receptor agonist, N-allylnormetazocine (SKF 10, 047), and the dissociative anaesthetic, ketamine, reduced or abolished excitation evoked by N-methyl-aspartate (NMA) with only smal...

  3. Free fatty acid receptors: emerging targets for treatment of diabetes and its complications

    Vangaveti, Venkat; Shashidhar, Venkatesh; Jarrod, Ghassan; Bernhard T. Baune; Kennedy, R. Lee

    2010-01-01

    Fatty acids (FAs) are important as metabolic substrates and as structural components of biological membranes. However, they also function as signalling molecules. Recently, a series of G protein-coupled receptors (GPRs) for FAs has been described and characterized. These receptors have differing specificities for FAs of differing chain length and degree of saturation, for FA derivatives such as oleoylethanolamide, and for oxidized FAs. They are a critical component of the body's nutrient sens...

  4. Chronic caffeine or theophylline exposure reduces gamma-aminobutyric acid/benzodiazepine receptor site interactions.

    Roca, D J; Schiller, G D; Farb, D H

    1988-05-01

    Methylxanthines, such as caffeine and theophylline, are adenosine receptor antagonists that exert dramatic effects upon the behavior of vertebrate animals by increasing attentiveness, anxiety, and convulsive activity. Benzodiazepines, such as flunitrazepam, generally exert behavioral effects that are opposite to those of methylxanthines. We report the finding that chronic exposure of embryonic brain neurons to caffeine or theophylline reduces the ability of gamma-aminobutyric acid (GABA) to potentiate the binding of [3H]flunitrazepam to the GABA/benzodiazepine receptor. This theophylline-induced "uncoupling" of GABA- and benzodiazepine-binding site allosteric interactions is blocked by chloroadenosine, an adenosine receptor agonist, indicating that the chronic effects of theophylline are mediated by a site that resembles an adenosine receptor. We speculate that adverse central nervous system effects of long-term exposure to methylxanthines such as in caffeine-containing beverages or theophylline-containing medications may be exerted by a cell-mediated modification of the GABAA receptor. PMID:2835648

  5. The synthetic retinoid AGN 193109 but not retinoic acid elevates CYP1A1 levels in mouse embryos and Hepa-1c1c7 cells.

    Soprano, D R; Gambone, C J; Sheikh, S N; Gabriel, J L; Chandraratna, R A; Soprano, K J; Kochhar, D M

    2001-07-15

    The synthetic retinoid AGN 193109 is a potent pan retinoic acid receptor (RAR) antagonist. Treatment of pregnant mice with a single oral 1 mg/kg dose of this antagonist on day 8 postcoitum results in severe craniofacial (median cleft face or frontonasal deficiency) and eye malformations in virtually all exposed fetuses. Using differential display analysis, we have determined that CYP1A1 mRNA levels are elevated in mouse embryos 6 h following treatment with AGN 193109. Similarly, an elevation in CYP1A1 mRNA levels, protein levels, and aryl hydrocarbon hydoxylase activity occurs in Hepa-1c1c7 cells, with the maximal elevation observed when the cells were treated with 10(-5) M AGN 193109 for 4 to 8 h. Elevation in CYP1A1 mRNA levels in mouse embryos and Hepa-1c1c7 cells does not occur upon treatment with the natural retinoid, all-trans-retinoic acid. Finally, elevation in CYP1A1 mRNA levels was not observed when mutant Hepa-1c1c7 cells, which are defective in either the aryl hydrocarbon receptor (AhR) or aryl hydrocarbon receptor nuclear translocator (ARNT), were treated with AGN 193109. This suggests that the AhR/ARNT pathway and not the RAR/RXR pathway is mediating the elevation of CYP1A1 mRNA levels by AGN 193109, at least in the Hepa-1c1c7 cells. This is the first example of a retinoid that displays the abililty to regulate both the RAR/RXR and AhR/ARNT transcriptional regulatory pathways. PMID:11446831

  6. Metabolism meets immunity: the role of free fatty acid receptors in the immune system

    Alvarez-Curto, Elisa; Milligan, Graeme

    2016-01-01

    There are significant numbers of nutrient sensing G protein-coupled receptors (GPCRs) that can be found in cells of the immune system and in tissues that are involved in metabolic function, such as the pancreas or the intestinal epithelium. The family of free fatty acid receptors (FFAR1-4, GPR84), plus a few other metabolite sensing receptors (GPR109A, GPR91, GPR35) have been for this reason the focus of studies linking the effects of nutrients with immunological responses. A number of the be...

  7. N-Hydroxypyrazolyl glycine derivatives as selective N-methyl-D-aspartic acid receptor ligands

    Clausen, Rasmus Prætorius; Christensen, Caspar; Hansen, Kasper Bø;

    2008-01-01

    glycine (NHP5G) derivatives are selectively recognized by N-methyl- d-aspartic acid (NMDA) receptors and that the ( R)-enantiomers are preferred. Moreover, several of the compounds are able to discriminate between individual subtypes among the NMDA receptors, providing new pharmacological tools. For......A series of analogues based on N-hydroxypyrazole as a bioisostere for the distal carboxylate group of aspartate have been designed, synthesized, and pharmacologically characterized. Affinity studies on the major glutamate receptor subgroups show that these 4-substituted N-hydroxypyrazol-5-yl...

  8. Role of Free Fatty Acid Receptor 2 (FFAR2) in the Regulation of Metabolic Homeostasis.

    Mohammad, Sameer

    2015-01-01

    Besides being an important source of fuel and structural components of biological membranes, free fatty acids (FFAs) are known to display a wide variety of roles that include modulation of receptor signaling and regulation of gene expression among many. FFAs play a significant role in maintaining metabolic homeostasis by activating specific G-Protein Coupled Receptors (GPCRs) in pancreatic β cells, immune cells, white adipose tissue, intestine and several other tissues. Free Fatty acid receptor 2 (FFAR2) also known as GPR43 belongs to this group of GPCRs and has been shown to participate in a number of important biological activities. FFAR2 is activated by short-chain fatty acids (SCFAs) such as acetate, propionate and butyrate. SCFAs are formed in the distal gut by bacterial fermentation of macro-fibrous material that escapes digestion in the upper gastrointestinal tract and enters the colon and have been shown to play vital role in the immune regulation and metabolic homeostasis. FFAR2 and other free fatty acid receptors are considered key components of the body's nutrient sensing mechanism and targeting these receptors is assumed to offer novel therapies for the management of diabetes and other metabolic disorders. This review aims to summarize the current state of our understanding of FFAR2 biology with a particular focus on its role in metabolic homeostasis. PMID:25850624

  9. Association between cytoplasmic CRABP2, altered retinoic acid signaling, and poor prognosis in glioblastoma.

    Liu, Rong-Zong; Li, Shuai; Garcia, Elizabeth; Glubrecht, Darryl D; Yin Poon, Ho; Easaw, Jacob C; Godbout, Roseline

    2016-06-01

    Retinoic acid (RA), a metabolite of vitamin A, is required for the regulation of growth and development. Aberrant expression of molecules involved in RA signaling has been reported in various cancer types including glioblastoma multiforme (GBM). Cellular retinoic acid-binding protein 2 (CRABP2) has previously been shown to play a key role in the transport of RA to retinoic acid receptors (RARs) to activate their transcription regulatory activity. Here, we demonstrate that CRABP2 is predominantly located in the cytoplasm of GBM tumors. Cytoplasmic, but not nuclear, CRABP2 levels in GBM tumors are associated with poor patient survival. Treatment of malignant glioma cell lines with RA results in a dose-dependent increase in accumulation of CRABP2 in the cytoplasm. CRABP2 knockdown reduces proliferation rates of malignant glioma cells, and enhances RA-induced RAR activation. Levels of CRYAB, a small heat shock protein with anti-apoptotic activity, and GFAP, an astrocyte-specific intermediate filament protein, are greatly reduced in CRABP2-depleted cells. Restoration of CRYAB expression partially but significantly reversed the effect of CRABP2 depletion on RAR activation. Our combined in vivo and in vitro data indicate that: (i) CRABP2 is an important determinant of clinical outcome in GBM patients, and (ii) the mechanism of action of CRABP2 in GBM involves sequestration of RA in the cytoplasm and activation of an anti-apoptotic pathway, thereby enhancing proliferation and preventing RA-mediated cell death and differentiation. We propose that reducing CRABP2 levels may enhance the therapeutic index of RA in GBM patients. GLIA 2016;64:963-976. PMID:26893190

  10. Acidic leucine-rich nuclear phosphoprotein 32 family member B (ANP32B) contributes to retinoic acid-induced differentiation of leukemic cells

    Yu, Yun; Shen, Shao-Ming; Zhang, Fei-Fei; Wu, Zhao-Xia; Han, Bin [Shanghai Universities E-Institute for Chemical Biology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine (SJTU-SM), Shanghai 200025 (China); Wang, Li-Shun, E-mail: jywangls@shsmu.edu.cn [Shanghai Universities E-Institute for Chemical Biology, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine (SJTU-SM), Shanghai 200025 (China)

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer ANP32B was down-regulated during ATRA-induced leukemic cell differentiation. Black-Right-Pointing-Pointer Knockdown of ANP32B enhanced ATRA-induced leukemic cell differentiation. Black-Right-Pointing-Pointer Ectopic expression of ANP32B inhibited ATRA-induced leukemic cell differentiation. Black-Right-Pointing-Pointer ANP32B inhibited ATRA activated transcriptional activity of RAR{alpha}. -- Abstract: The acidic leucine-rich nuclear phosphoprotein 32B (ANP32B) is a member of a conserved superfamily of nuclear proteins whose functions are largely unknown. In our previous work, ANP32B was identified as a novel direct substrate for caspase-3 and acted as a negative regulator for leukemic cell apoptosis. In this work, we provided the first demonstration that ANP32B expression was down-regulated during differentiation induction of leukemic cells by all-trans retinoic acid (ATRA). Knockdown of ANP32B expression by specific shRNA enhanced ATRA-induced leukemic cell differentiation, while ectopic expression of ANP32B attenuated it, indicating an inhibitory role of ANP32B against leukemic cell differentiation. Furthermore, luciferase reporter assay revealed that ANP32B might exert this role through inhibiting the ATRA dependent transcriptional activity of retinoic acid receptor (RAR{alpha}). These data will shed new insights into understanding the biological functions of ANP32B protein.

  11. Lysophosphatidic Acid Signaling through the Lysophosphatidic Acid-1 Receptor Is Required for Alveolarization.

    Funke, Manuela; Knudsen, Lars; Lagares, David; Ebener, Simone; Probst, Clemens K; Fontaine, Benjamin A; Franklin, Alicia; Kellner, Manuela; Kühnel, Mark; Matthieu, Stephanie; Grothausmann, Roman; Chun, Jerold; Roberts, Jesse D; Ochs, Matthias; Tager, Andrew M

    2016-07-01

    Lysophosphatidic acid (LPA) signaling through one of its receptors, LPA1, contributes to both the development and the pathological remodeling after injury of many organs. Because we found previously that LPA-LPA1 signaling contributes to pulmonary fibrosis, here we investigated whether this pathway is also involved in lung development. Quantitative assessment of lung architecture of LPA1-deficient knock-out (KO) and wild-type (WT) mice at 3, 12, and 24 weeks of age using design-based stereology suggested the presence of an alveolarization defect in LPA1 KO mice at 3 weeks, which persisted as alveolar numbers increased in WT mice into adulthood. Across the ages examined, the lungs of LPA1 KO mice exhibited decreased alveolar numbers, septal tissue volumes, and surface areas, and increased volumes of the distal airspaces. Elastic fibers, critical to the development of alveolar septa, appeared less organized and condensed and more discontinuous in KO alveoli starting at P4. Tropoelastin messenger RNA expression was decreased in KO lungs, whereas expression of matrix metalloproteinases degrading elastic fibers was either decreased or unchanged. These results are consistent with the abnormal lung phenotype of LPA1 KO mice, being attributable to reduced alveolar septal formation during development, rather than to increased septal destruction as occurs in the emphysema of chronic obstructive pulmonary disease. Peripheral septal fibroblasts and myofibroblasts, which direct septation in late alveolarization, demonstrated reduced production of tropoelastin and matrix metalloproteinases, and diminished LPA-induced migration, when isolated from LPA1 KO mice. Taken together, our data suggest that LPA-LPA1 signaling is critically required for septation during alveolarization. PMID:27082727

  12. Characterization and Functional Analysis of Pyrabactin Resistance-Like Abscisic Acid Receptor Family in Rice

    Tian, Xiaojie; Wang, Zhenyu; Li, Xiufeng; Lv, Tianxiao; Liu, Huazhao; Wang, Lizhi; Niu, Hongbin; Bu, Qingyun

    2015-01-01

    Background Abscisic acid (ABA) plays crucial roles in regulating plant growth and development, especially in responding to abiotic stress. The pyrabactin resistance-like (PYL) abscisic acid receptor family has been identified and widely characterized in Arabidopsis. However, PYL families in rice were largely unknown. In the present study, 10 out of 13 PYL orthologs in rice (OsPYL) were isolated and investigated. Results Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) an...

  13. Association analysis of retinoic acid receptor beta (RARβ) gene with high myopia in Chinese subjects

    Ding, Yang; Chen, Xiaoyan; Yan, Dongsheng; Xue, Anquan; Lu, Fan; Qu, Jia; Zhou, Xiangtian

    2010-01-01

    Purpose High myopia or pathological myopia is a common refractive error. Individuals with high myopia are subject to increased risk of serious eye complications. Accumulating evidence has demonstrated the role for heritability in ocular growth and in the development of high myopia. Retinoic acid and retinoic acid receptors play important roles in ocular development and in experimentally induced myopia. The purpose of this study was to determine if high myopia is associated with single nucleot...

  14. Glucose regulates fatty acid binding protein interaction with lipids and peroxisome proliferator-activated receptor α

    Hostetler, Heather A.; Balanarasimha, Madhumitha; Huang, Huan; Kelzer, Matthew S.; Kaliappan, Alagammai; Kier, Ann B.; Schroeder, Friedhelm

    2010-01-01

    Although the pathophysiology of diabetes is characterized by elevated levels of glucose and long-chain fatty acids (LCFA), nuclear mechanisms linking glucose and LCFA metabolism are poorly understood. As the liver fatty acid binding protein (L-FABP) shuttles LCFA to the nucleus, where L-FABP directly interacts with peroxisome proliferator-activated receptor-α (PPARα), the effect of glucose on these processes was examined. In vitro studies showed that L-FABP strongly bound glucose and glucose-...

  15. Molecular pharmacology of 4-substituted glutamic acid analogues at ionotropic and metabotropic excitatory amino acid receptors

    Bräuner-Osborne, Hans; Nielsen, B; Stensbøl, T B; Johansen, T N; Skjaerbaek, N; Krogsgaard-Larsen, P

    The pharmacology of (2S,4R)-4-methylglutamic acid, (2S,4S)-4-methylglutamic acid and (S)- and (R)-4-methyleneglutamic acids (obtained in high chemical and enantiomeric purity from racemic 4-methyleneglutamic acid by chiral HPLC using a Crownpak CR(+) column), was examined in binding experiments u...

  16. Bile Acids Trigger GLP-1 Release Predominantly by Accessing Basolaterally Located G Protein-Coupled Bile Acid Receptors.

    Brighton, Cheryl A; Rievaj, Juraj; Kuhre, Rune E; Glass, Leslie L; Schoonjans, Kristina; Holst, Jens J; Gribble, Fiona M; Reimann, Frank

    2015-11-01

    Bile acids are well-recognized stimuli of glucagon-like peptide-1 (GLP-1) secretion. This action has been attributed to activation of the G protein-coupled bile acid receptor GPBAR1 (TGR5), although other potential bile acid sensors include the nuclear farnesoid receptor and the apical sodium-coupled bile acid transporter ASBT. The aim of this study was to identify pathways important for GLP-1 release and to determine whether bile acids target their receptors on GLP-1-secreting L-cells from the apical or basolateral compartment. Using transgenic mice expressing fluorescent sensors specifically in L-cells, we observed that taurodeoxycholate (TDCA) and taurolithocholate (TLCA) increased intracellular cAMP and Ca(2+). In primary intestinal cultures, TDCA was a more potent GLP-1 secretagogue than taurocholate (TCA) and TLCA, correlating with a stronger Ca(2+) response to TDCA. Using small-volume Ussing chambers optimized for measuring GLP-1 secretion, we found that both a GPBAR1 agonist and TDCA stimulated GLP-1 release better when applied from the basolateral than from the luminal direction and that luminal TDCA was ineffective when intestinal tissue was pretreated with an ASBT inhibitor. ASBT inhibition had no significant effect in nonpolarized primary cultures. Studies in the perfused rat gut confirmed that vascularly administered TDCA was more effective than luminal TDCA. Intestinal primary cultures and Ussing chamber-mounted tissues from GPBAR1-knockout mice did not secrete GLP-1 in response to either TLCA or TDCA. We conclude that the action of bile acids on GLP-1 secretion is predominantly mediated by GPBAR1 located on the basolateral L-cell membrane, suggesting that stimulation of gut hormone secretion may include postabsorptive mechanisms. PMID:26280129

  17. Bile Acids Trigger GLP-1 Release Predominantly by Accessing Basolaterally Located G Protein–Coupled Bile Acid Receptors

    Brighton, Cheryl A.; Rievaj, Juraj; Kuhre, Rune E.; Glass, Leslie L.; Schoonjans, Kristina; Holst, Jens J.

    2015-01-01

    Bile acids are well-recognized stimuli of glucagon-like peptide-1 (GLP-1) secretion. This action has been attributed to activation of the G protein–coupled bile acid receptor GPBAR1 (TGR5), although other potential bile acid sensors include the nuclear farnesoid receptor and the apical sodium-coupled bile acid transporter ASBT. The aim of this study was to identify pathways important for GLP-1 release and to determine whether bile acids target their receptors on GLP-1–secreting L-cells from the apical or basolateral compartment. Using transgenic mice expressing fluorescent sensors specifically in L-cells, we observed that taurodeoxycholate (TDCA) and taurolithocholate (TLCA) increased intracellular cAMP and Ca2+. In primary intestinal cultures, TDCA was a more potent GLP-1 secretagogue than taurocholate (TCA) and TLCA, correlating with a stronger Ca2+ response to TDCA. Using small-volume Ussing chambers optimized for measuring GLP-1 secretion, we found that both a GPBAR1 agonist and TDCA stimulated GLP-1 release better when applied from the basolateral than from the luminal direction and that luminal TDCA was ineffective when intestinal tissue was pretreated with an ASBT inhibitor. ASBT inhibition had no significant effect in nonpolarized primary cultures. Studies in the perfused rat gut confirmed that vascularly administered TDCA was more effective than luminal TDCA. Intestinal primary cultures and Ussing chamber–mounted tissues from GPBAR1-knockout mice did not secrete GLP-1 in response to either TLCA or TDCA. We conclude that the action of bile acids on GLP-1 secretion is predominantly mediated by GPBAR1 located on the basolateral L-cell membrane, suggesting that stimulation of gut hormone secretion may include postabsorptive mechanisms. PMID:26280129

  18. Extracellular loop 2 of the free Fatty Acid receptor 2 mediates allosterism of a phenylacetamide ago-allosteric modulator

    Smith, Nicola J; Ward, Richard J; Stoddart, Leigh A; Hudson, Brian D; Kostenis, Evi; Ulven, Trond; Morris, Joanne C; Tränkle, Christian; Tikhonova, Irina G; Adams, David R; Milligan, Graeme

    2011-01-01

    Allosteric agonists are powerful tools for exploring the pharmacology of closely related G protein-coupled receptors that have nonselective endogenous ligands, such as the short chain fatty acids at free fatty acid receptors 2 and 3 (FFA2/GPR43 and FFA3/GPR41, respectively). We explored the molec...

  19. Bile acids trigger GLP-1 release predominantly by accessing basolaterally-located G-protein coupled bile acid receptors

    Brighton, Cheryl A; Rievaj, Juraj; Kuhre, Rune Ehrenreich; Glass, Leslie L; Schoonjans,, Kristina; Holst, Jens Juul; Gribbe, Fiona M; Reimann, Frank

    2015-01-01

    coupled bile acid transporter ASBT. The aim of this study was to identify pathways important for GLP-1 release, and whether bile acids target their receptors on GLP-1 secreting L-cells from the apical or basolateral compartment. Using transgenic mice expressing fluorescent sensors specifically in L...... significant effect in non-polarised primary cultures. Studies in the perfused rat gut confirmed that vascularly administered TDCA was more effective than luminalTDCA.Intestinal primary culturesandUssingchamber-mounted tissues from GPBAR1-knockout mice did not secrete GLP-1 in response to either TLCA or TDCA...

  20. Mutational Characterization of the Bile Acid Receptor TGR5 in Primary Sclerosing Cholangitis

    Hov, Johannes R.; Keitel, Verena; Laerdahl, Jon K.; Spomer, Lina; Ellinghaus, Eva; ElSharawy, Abdou; Melum, Espen; Boberg, Kirsten M.; Manke, Thomas; Balschun, Tobias; Schramm, Christoph; Bergquist, Annika; Weismueller, Tobias; Gotthardt, Daniel; Rust, Christian; Henckaerts, Liesbet; Onnie, Clive M.; Weersma, Rinse K.; Sterneck, Martina; Teufel, Andreas; Runz, Heiko; Stiehl, Adolf; Ponsioen, Cyriel Y.; Wijmenga, Cisca; Vatn, Morten H.; Stokkers, Pieter C. F.; Vermeire, Severine; Mathew, Christopher G.; Lie, Benedicte A.; Beuers, Ulrich; Manns, Michael P.; Schreiber, Stefan; Schrumpf, Erik; Haeussinger, Dieter; Franke, Andre; Karlsen, Tom H.

    2010-01-01

    Background: TGR5, the G protein-coupled bile acid receptor 1 (GPBAR1), has been linked to inflammatory pathways as well as bile homeostasis, and could therefore be involved in primary sclerosing cholangitis (PSC) a chronic inflammatory bile duct disease. We aimed to extensively investigate TGR5 sequ

  1. Unnatural amino acids as probes of ligand-receptor interactions and their conformational consequences

    Pless, Stephan Alexander; Ahern, Christopher A

    2013-01-01

    -edge synthetic and chemical biological approaches. Here we summarize recent advances in the use of site-directed incorporation of unnatural amino acids and chemical probes to study ligand-receptor interactions, determine the location of binding sites, and examine the downstream conformational consequences of...

  2. Searsia species with affinity to the N-methyl-d-aspartic acid (NMDA) receptor

    Jäger, Anna; Knap, D.M.; Nielsen, Birgitte;

    2012-01-01

    Species of Searsia are used in traditional medicine to treat epilepsy. Previous studies on S. dentata and S. pyroides have shown that this is likely mediated via the N-methyl-d-aspartic acid (NMDA) receptor. Ethanolic extracts of leaves of six Searsia species were tested in a binding assay for...... accessible Searsia species can be used in traditional medicine....

  3. Hyaluronic Acid Induces Activation of the κ-Opioid Receptor

    Zavan, Barbara; Ferroni, Letizia; Giorgi, Carlotta; Calò, Girolamo; Brun, Paola; Cortivo, Roberta; Abatangelo, Giovanni; Pinton, Paolo

    2013-01-01

    Introduction Nociceptive pain is one of the most common types of pain that originates from an injury involving nociceptors. Approximately 60% of the knee joint innervations are classified as nociceptive. The specific biological mechanism underlying the regulation of nociceptors is relevant for the treatment of symptoms affecting the knee joint. Intra-articular administration of exogenous hyaluronic acid (HA) in patients with osteoarthritis (OA) appears to be particularly effective in reducing...

  4. Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes

    Junker, L.H.; Davis, R.A. (Univ. of Colorado Health Sciences Center, Denver (USA))

    1989-12-01

    The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of (14C)cholesterol from (2-14C)acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of (14C)cholesterol from (2-14C)acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis.

  5. Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes

    The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of [14C]cholesterol from [2-14C]acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of [14C]cholesterol from [2-14C]acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis

  6. Reduction of sodium deoxycholic acid-induced scratching behaviour by bradykinin B2 receptor antagonists

    Hayashi, Izumi; Majima, Masataka

    1999-01-01

    Subcutaneous injection of sodium deoxycholic acid into the anterior of the back of male ddY mice elicited dose-dependent scratching of the injected site with the forepaws and hindpaws.Up to 100 μg of sodium deoxycholic acid induced no significant increase in vascular permeability at the injection site as assessed by a dye leakage method.Bradykinin (BK) B2 receptor antagonists, FR173657 and Hoe140, significantly decreased the frequency of scratching induced by sodium deoxycholic acid.Treatment...

  7. The human receptor for urokinase plasminogen activator. NH2-terminal amino acid sequence and glycosylation variants

    Behrendt, N; Rønne, E; Ploug, M; Petri, T; Løber, D; Nielsen, L S; Schleuning, W D; Blasi, F; Appella, E; Danø, K

    1990-01-01

    -PA. The purified protein shows a single 55-60 kDa band after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining. It is a heavily glycosylated protein, the deglycosylated polypeptide chain comprising only 35 kDa. The glycosylated protein contains N-acetyl-D-glucosamine and sialic...... acid, but no N-acetyl-D-galactosamine. Glycosylation is responsible for substantial heterogeneity in the receptor on phorbol ester-stimulated U937 cells, and also for molecular weight variations among various cell lines. The amino acid composition and the NH2-terminal amino acid sequence are reported...

  8. Tetrahydro-iso-alpha Acids Antagonize Estrogen Receptor Alpha Activity in MCF-7 Breast Cancer Cells

    Maëlle Lempereur

    2016-01-01

    Full Text Available Tetrahydro-iso-alpha acids commonly called THIAA or Tetra are modified hop acids extracted from hop (Humulus lupulus L. which are frequently used in brewing industry mainly in order to provide beer bitterness and foam stability. Interestingly, molecular structure of tetrahydro-iso-alpha acids is close to a new type of estrogen receptor alpha (ERα antagonists aimed at disrupting the binding of coactivators containing an LxxLL motif (NR-box. In this work we show that THIAA decreases estradiol-stimulated proliferation of MCF-7 (ERα-positive breast cancer cells. Besides, we show that it inhibits ERα transcriptional activity. Interestingly, this extract fails to compete with estradiol for ERα binding and does not significantly impact the receptor turnover rate in MCF-7 cells, suggesting that it does not act like classical antiestrogens. Hence, we demonstrate that THIAA is able to antagonize ERα estradiol-induced recruitment of the LxxLL binding motif.

  9. Tetrahydro-iso-alpha Acids Antagonize Estrogen Receptor Alpha Activity in MCF-7 Breast Cancer Cells.

    Lempereur, Maëlle; Majewska, Claire; Brunquers, Amandine; Wongpramud, Sumalee; Valet, Bénédicte; Janssens, Philippe; Dillemans, Monique; Van Nedervelde, Laurence; Gallo, Dominique

    2016-01-01

    Tetrahydro-iso-alpha acids commonly called THIAA or Tetra are modified hop acids extracted from hop (Humulus lupulus L.) which are frequently used in brewing industry mainly in order to provide beer bitterness and foam stability. Interestingly, molecular structure of tetrahydro-iso-alpha acids is close to a new type of estrogen receptor alpha (ERα) antagonists aimed at disrupting the binding of coactivators containing an LxxLL motif (NR-box). In this work we show that THIAA decreases estradiol-stimulated proliferation of MCF-7 (ERα-positive breast cancer cells). Besides, we show that it inhibits ERα transcriptional activity. Interestingly, this extract fails to compete with estradiol for ERα binding and does not significantly impact the receptor turnover rate in MCF-7 cells, suggesting that it does not act like classical antiestrogens. Hence, we demonstrate that THIAA is able to antagonize ERα estradiol-induced recruitment of the LxxLL binding motif. PMID:27190515

  10. A new orphan member of the nuclear hormone receptor superfamily that interacts with a subset of retinoic acid response elements.

    Baes, M.; Gulick, T; Choi, H. S.; Martinoli, M G; Simha, D; Moore, D D

    1994-01-01

    We have identified and characterized a new orphan member of the nuclear hormone receptor superfamily, called MB67, which is predominantly expressed in liver. MB67 binds and transactivates the retinoic acid response elements that control expression of the retinoic acid receptor beta 2 and alcohol dehydrogenase 3 genes, both of which consist of a direct repeat hexamers related to the consensus AGGTCA, separated by 5 bp. MB67 binds these elements as a heterodimer with the 9-cis-retinoic acid rec...

  11. Metabolism meets immunity: The role of free fatty acid receptors in the immune system.

    Alvarez-Curto, Elisa; Milligan, Graeme

    2016-08-15

    There are significant numbers of nutrient sensing G protein-coupled receptors (GPCRs) that can be found in cells of the immune system and in tissues that are involved in metabolic function, such as the pancreas or the intestinal epithelium. The family of free fatty acid receptors (FFAR1-4, GPR84), plus a few other metabolite sensing receptors (GPR109A, GPR91, GPR35) have been for this reason the focus of studies linking the effects of nutrients with immunological responses. A number of the beneficial anti-inflammatory effects credited to dietary fats such as omega-3 fatty acids are attributed to their actions on FFAR4.This might play an important protective role in the development of obesity, insulin resistance or asthma. The role of the short-chain fatty acids resulting from fermentation of fibre by the intestinal microbiota in regulating acute inflammatory responses is also discussed. Finally we assess the therapeutic potential of this family of receptors to treat pathologies where inflammation is a major factor such as type 2 diabetes, whether by the use of novel synthetic molecules or by the modulation of the individual's diet. PMID:27002183

  12. Evolution of neurotransmitter gamma-aminobutyric acid,glutamate and their receptors

    Zhiheng GOU; Xiao WANG; Wen WANG

    2012-01-01

    Gamma-aminobutyric acid (GABA) and glutamate are two important amino acid neurotransmitters widely present in the nervous systems of ammals,insects,round worm,and platyhelminths,while their receptors are quite diversified across different animal phyla.However,the evolutionary mechanisms between the two conserved neurotransmitters and their diversified receptors remain elusive,and antagonistic interactions between GABA and glutamate signal transduction systems,in particular,have begun to attract significant attention.In this review,we summarize the extant results on the origin and evolution of GABA and glutamate,as well as their receptors,and analyze possible evolutionary processes and phylogenetic relationships of various GABAs and glutamate receptors.We further discuss the evolutionary history of Excitatory/Neutral Amino Acid Transporter (EAAT),a transport protein,which plays an important role in the GABA-glutamate "yin and yang" balanced regulation.Finally,based on current advances,we propose several potential directions of future research.

  13. Dynamic changes of excitatory amino acid receptors in the rat hippocampus following transient cerebral ischemia

    The changes in excitatory amino acid receptor ligand binding induced by transient cerebral ischemia were studied in the rat hippocampal subfields. Ten minutes of ischemia was induced by common carotid artery occlusion combined with hypotension, and the animals were allowed variable periods of recovery ranging from 1 day to 4 weeks. The binding of 3H-AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) to quisqualate receptors, 3H-kainic acid (KA) to kainate receptors, and 3H-glutamate to N-methyl-D-aspartate (NMDA) receptors as determined by quantitative autoradiography. One week following ischemia the CA1 region of the hippocampus displayed a severe (90%) dendrosomatic lesion with preservation of presynaptic terminals. This was associated with a 60% decrease in AMPA binding and a 25% decrease in glutamate binding to NMDA receptors. At 4 weeks postischemia, both AMPA and NMDA sites were greatly reduced. Although the dentate gyrus granule cells are resistant to an ischemic insult of this magnitude, this region showed marked changes in receptor binding. One week following ischemia, the AMPA and NMDA binding decreased by approximately 40 and 20%, respectively. Following 2 weeks of recovery, the NMDA binding was not significantly different from control level, while the AMPA binding remained depressed up to 4 weeks postischemia. The high density of KA binding sites in the inner molecular layer of the dentate gyrus was unaffected by the ischemic insult, despite an extensive degeneration of cells in the hilus of dentate gyrus which projects glutamatergic afferents to this area

  14. Receptors for short-chain fatty acids in brush cells at the gastric groove

    Julia Anna-Maria Eberle

    2014-04-01

    Full Text Available In the stomach of rodents clusters of brush cells are arranged at the gastric groove, immediately at the transition zone from the non-glandular reservoir compartment to the glandular digestive compartment. Based on their taste cell-like molecular phenotype it has been speculated that the cells may be capable to sense constituents of the ingested food, however, searches for nutrient receptors have not been successful. In this study, it was hypothesized that the cells may express receptors for short-chain fatty acids, metabolites generated by microorganisms during the storage of ingested food in the murine forestomach, which lacks the acidic milieu of more posterior regions of the stomach and is colonized with numerous microbiota. Experimental approaches, including RT-PCR analysis and immunohistochemical studies, revealed that the majority of these brush cells express the G-protein coupled receptor types GPR41 (FFAR3 and GPR43 (FFAR2, which are activated by short-chain fatty acids. Both, the GPR41 receptor proteins as well as an appropriate G-protein, α-gustducin, were found to be segregated at the apical brush border of the cells, indicating a direct contact with the luminal content of this gastric region. The exposure of microvillar processes with appropriate receptors and signaling elements to the gastric lumen suggests that the brush cells may in fact be capable to sense the short-chain fatty acids which originate from fermentation processes during the retention of ingested food in the anterior part of the stomach.

  15. Gamma-aminobutyric acid promotes human hepatocellular carcinoma growth through overexpressed gamma-aminobutyric acid A receptor α3 subunit

    2008-01-01

    AIM: To investigate the expression pattern of gamma-aminobutyric acid A (GABAA) receptors in hepatocellular carcinoma (HCC) and indicate the relationship among gamma-aminobutyric acid (GABA), gamrna-aminobutyric acid A receptor α3 subunit (GABRA3) and HCC.METHODS: HCC cell line Chang, HepG2, normal liver cell line L-02 and 8 samples of HCC tissues and paired non-cancerous tissues were analyzed with semiquantitative polymerase chain reaction (PCR) for the expression of GABAA receptors. HepG2 cells were treated with gamma-aminobutyric acid (GABA) at serial concentrations (0, 1, 10, 20, 40 and 60 μmol/L), and their proliferating abilities were analyzed with the 3-(4, 5-methylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, cell doubling time test, colon formation assay, cell cycle analysis and tumor planted in nude mice. Small interfering RNA was used for knocking down the endogenous GABRA3 in HepG2. oliferating abilities of these cells treated with or without GABA were analyzed.RESULTS: We identified the overexpression of GABRA3 in HCC cells. Knockdown of endogenous GABRA3 expression in HepG2 attenuated HCC cell growth, suggesting its role in HCC cell viability. We determined the in vitro and in vivo effect of GABA in the proliferation of GABRA3-positive cell lines, and found that GABA increased HCC growth in a dose-dependent manner. Notably, the addition of GABA into the cell culture medium promoted the proliferation of GABRA3-expressing HepG2 cells, but not GABRA3-knockdown HepG2 cells. This means that GABA stimulates HepG2 cell growth through GABRA3. CONCLUSION: GABA and GABRA3 play important roles in HCC development and progression and can be a promising molecular target for the development of new diagnostic and therapeutic strategies for HCC.

  16. Positive cooperativity between the thrombin and bradykinin B2 receptors enhances arachidonic acid release

    Hecquet, Claudie; Biyashev, Dauren; Tan, Fulong; Erdös, Ervin G.

    2005-01-01

    Bradykinin (BK) or kallikreins activate B2 receptors (R) which couple Gαi and Gαq proteins to release arachidonic acid (AA) and elevate [Ca2+]i. Thrombin cleaves the protease-activated-receptor-1 (PAR1) that couples Gαi, Gαq and Gα12/13 proteins. In CHO cells stably transfected with human B2R, thrombin liberated little AA, but it significantly potentiated AA release by B2R agonists. We explored mechanisms of cooperativity between constitutively expressed PAR1 and B2R. We also examined human e...

  17. Gamma-aminobutyric-acid-B receptor antibodies in limbic encephalitis with small cell lung cancer

    Ke-Qin Liu

    2015-01-01

    Full Text Available Encephalitis associated with antibodies to gamma-aminobutyric-acid B (GABA-B is a subgroup of autoimmune synaptic encephalitis with typical features of limbic encephalitis and small cell lung cancer (SCLC. We report a case of anti-GABA-B receptor encephalitis in a 57-year-old man who presented with seizures, memory loss, and abnormal behavior. He developed partially neurological responses to immunotherapy, but refused comprehensive tumor screening. The symptoms were aggravated again 4 months later. Workup showed antibodies to GABA-B receptors and tumor screening revealed SCLC. It highlights the importance of early screening of underlying tumor and anti-tumor treatment in paraneoplastic cases.

  18. Nuclear receptors, bile acids and cholesterol homeostasis series - bile acids and pregnancy.

    Abu-Hayyeh, Shadi; Papacleovoulou, Georgia; Williamson, Catherine

    2013-04-10

    Bile acids have been traditionally thought of as having an important role in fat emulsification. It is now emerging that they act as important signalling molecules that not only autoregulate their own synthesis but also influence lipid and glucose metabolism. Although, the mechanisms that underlie the regulation of bile acid homeostasis have been well characterised in normal physiology, the impact of pregnancy on bile acid regulation is still poorly understood. This review summarises the main regulatory mechanisms underlying bile acid homeostasis and discusses how pregnancy, a unique physiological state, can modify them. The fetoplacental adaptations that protect against fetal bile acid toxicity are reviewed. We highlight the importance of bile acid regulation during gestation by discussing the liver disease of pregnancy, intrahepatic cholestasis of pregnancy (ICP) and how genetic, endocrine and environmental factors contribute to the disease aetiology at a cellular and molecular level. PMID:23159988

  19. Identification of a Binding Site for Unsaturated Fatty Acids in the Orphan Nuclear Receptor Nurr1.

    de Vera, Ian Mitchelle S; Giri, Pankaj K; Munoz-Tello, Paola; Brust, Richard; Fuhrmann, Jakob; Matta-Camacho, Edna; Shang, Jinsai; Campbell, Sean; Wilson, Henry D; Granados, Juan; Gardner, William J; Creamer, Trevor P; Solt, Laura A; Kojetin, Douglas J

    2016-07-15

    Nurr1/NR4A2 is an orphan nuclear receptor, and currently there are no known natural ligands that bind Nurr1. A recent metabolomics study identified unsaturated fatty acids, including arachidonic acid and docosahexaenoic acid (DHA), that interact with the ligand-binding domain (LBD) of a related orphan receptor, Nur77/NR4A1. However, the binding location and whether these ligands bind other NR4A receptors were not defined. Here, we show that unsaturated fatty acids also interact with the Nurr1 LBD, and solution NMR spectroscopy reveals the binding epitope of DHA at its putative ligand-binding pocket. Biochemical assays reveal that DHA-bound Nurr1 interacts with high affinity with a peptide derived from PIASγ, a protein that interacts with Nurr1 in cellular extracts, and DHA also affects cellular Nurr1 transactivation. This work is the first structural report of a natural ligand binding to a canonical NR4A ligand-binding pocket and indicates a natural ligand can bind and affect Nurr1 function. PMID:27128111

  20. Role of retinoic acid receptors in squamous-cell carcinoma in human esophagus

    Wolfgarten E

    2005-01-01

    Full Text Available Abstract Background Worldwide, cancer in the esophagus ranks among the 10 most common cancers. Alterations of retinoic acid receptors (e.g. RARα, β, γ, and RXRα, β, γ expression is considered to play an important role in development of squamous-cell carcinoma (SCC, which is the most common esophageal cancer. Alcohol consumption and smoking, which can alter retinoic acid receptor levels, have been identified as key risk factors in the development of carcinoma in the aero-digestive tract. Therefore, the aim of the present study was to evaluate protein levels of retinoic acid receptors (i.e. RARα, β, γ, and RXRβ in esophageal SCC and surrounding normal tissue of patients with untreated SCC and controls. Methods All study participants completed a questionnaire concerning smoking and alcohol drinking habits as well as anthropometrical parameters. Protein levels of RARα, β, γ, and RXRβ were determined by Western Blot in normal esophageal tissue and tissue obtained from SCC of 21 patients with newly diagnosed esophageal SCC and normal esophageal tissue of 10 controls. Results Protein levels of RARγ were significantly lower by ~68% in SCC compared to normal surrounding tissue in patients with SCC that smoked and/or consumed elevated amounts of alcohol. Furthermore, RARα protein levels were significantly lower (~- 45% in SCC in comparison to normal esophageal mucosa in patients with elevated alcohol intake. When comparing protein levels of retinoic acid receptors between normal tissue of patients with SCC and controls, RARγ protein levels were found to be significantly higher (~2.7-fold in normal esophageal tissue of SCC patients than in esophageal tissue obtained from controls. No differences were found for RARα, β, and RXRβ protein levels between normal esophageal tissue of patients and that of controls. Conclusion In conclusion, results of the present study suggest that alterations of retinoic acid receptors protein may contribute

  1. Mercaptoacetate blocks fatty acid-induced GLP-1 secretion in male rats by directly antagonizing GPR40 fatty acid receptors.

    Li, Ai-Jun; Wang, Qing; Dinh, Thu T; Simasko, Steve M; Ritter, Sue

    2016-04-15

    Mercaptoacetate (MA) is an orexigenic agent reported to block fatty acid (FA) oxidation. Recently, however, we reported evidence from isolated nodose ganglion neurons that MA antagonizes the G protein-coupled long- and medium-chain FA receptor GPR40. GPR40 mediates FA-induced secretion of the satietogenic incretin peptide glucagon-like peptide 1 (GLP-1), by enteroendocrine L cells, as well as FA-induced enhancement of glucose-stimulated insulin secretion. Our results in cultured nodose neurons suggest that MA would also block GPR40 in enteroendocrine cells controlling GLP-1 secretion. If so, this would suggest an alternative mechanism by which MA increases food intake. We tested the hypothesis that MA blocks FA-induced GLP-1 secretion in vitro using cultured STC-1 cells (a murine enteroendocrine cell line) and in vivo in adult male rats. In vitro, MA blocked the increase in both cytosolic Ca(2+)and GLP-1 release stimulated by FAs and also reduced (but less effectively) the response of STC-1 cells to grifolic acid, a partial agonist of the GPR120 FA receptor. In vivo, MA reduced GLP-1 secretion following olive oil gavage while also increasing glucose and decreasing insulin levels. The carnitine palmatoyltransferase 1 antagonist etomoxir did not alter these responses. Results indicate that MA's actions, including its orexigenic effect, are mediated by GPR40 (and possibly GPR120) receptor antagonism and not by blockade of fat oxidation, as previously believed. Analysis of MA's interaction with GPR40 may facilitate understanding of the multiple functions of this receptor and the manner in which FAs participate in the control of hunger and satiety. PMID:26791830

  2. Selective antagonists at group I metabotropic glutamate receptors: synthesis and molecular pharmacology of 4-aryl-3-isoxazolol amino acids

    Kromann, Hasse; Sløk, Frank A; Stensbøl, Tine B; Bräuner-Osborne, Hans; Madsen, Ulf; Krogsgaard-Larsen, Povl

    2002-01-01

    Homologation of (S)-glutamic acid (Glu, 1) and Glu analogues has previously provided ligands with activity at metabotropic Glu receptors (mGluRs). The homologue of ibotenic acid (7), 2-amino-3-(3-hydroxy-5-isoxazolyl)propionic acid (HIBO, 8), and the 4-phenyl derivative of 8, compound 9a, are bot...

  3. Appearance and cellular distribution of lectin-like receptors for alpha 1-acid glycoprotein in the developing rat testis

    Andersen, U O; Bøg-Hansen, T C; Kirkeby, S

    1996-01-01

    A histochemical avidin-biotin technique with three different alpha 1-acid glycoprotein glycoforms showed pronounced alterations in the cellular localization of two alpha 1-acid glycoprotein lectin-like receptors during cell differentiation in the developing rat testis. The binding of alpha 1-acid...

  4. Synthesis of novel N1-substituted bicyclic pyrazole amino acids and evaluation of their interaction with glutamate receptors

    Conti, Paola; Grazioso, Giovanni; di Ventimiglia, Samuele Joppolo;

    2005-01-01

    N1-substituted bicyclic pyrazole amino acids (S)-9a-9c and (R)-9a-9c, which are conformationally constrained analogues of glutamic acid, were prepared via a strategy based on a 1,3-dipolar cycloaddition. The new amino acids were tested for activity at ionotropic and metabotropic glutamate receptors...

  5. Ascorbic acid enables reversible dopamine receptor /sup 3/H-agonist binding

    Leff, S.; Sibley, D.R.; Hamblin, M.; Creese, I.

    1981-11-16

    The effects of ascorbic acid on dopaminergic /sup 3/H-agonist receptor binding were studied in membrane homogenates of bovine anterior pituitary and caudate, and rat striatum. In all tissues virtually no stereospecific binding (defined using 1uM (+)butaclamol) of the /sup 3/H-agonists N-propylnorapomorphine (NPA), apomorphine, or dopamine could be demonstrated in the absence of ascorbic acid. Although levels of total /sup 3/H-agonist binding were three to five times greater in the absence than in the presence of 0.1% ascorbic acid, the increased binding was entirely non-stereospecific. Greater amounts of dopamine-inhibitable /sup 3/H-NPA binding could be demonstrated in the absence of 0.1% ascorbic acid, but this measure of ''specific binding'' was demonstrated not to represent dopamine receptor binding since several other catecholamines and catechol were equipotent with dopamine and more potent than the dopamine agonist (+/-)amino-6,7-dihydroxy-1,2,3,4-tetrahydronapthalene (ADTN) in inhibiting this binding. High levels of dopamine-displaceable /sup 3/H-agonist binding were detected in fresh and boiled homogenates of cerebellum, an area of brain which receives no dopaminergic innervation, further demonstrating the non-specific nature of /sup 3/H-agonist binding in the absence of ascorbic acid. These studies emphasize that under typical assay conditions ascorbic acid is required in order to demonstrate reversible and specific /sup 3/H-agonist binding to dopamine receptors.

  6. Effects of Bile Acids and the Bile Acid Receptor FXR Agonist on the Respiratory Rhythm in the In Vitro Brainstem Medulla Slice of Neonatal Sprague-Dawley Rats

    Cong Zhao; Xianbao Wang; Yuling Cong; Yi Deng; Yijun Xu; Aihua Chen; Yanru Yin

    2014-01-01

    Intrahepatic cholestasis of pregnancy is always accompanied by adverse fetal outcomes such as malfunctions of respiration. Farnesoid X receptor (FXR) plays a critical role in the homeostasis of bile acids. Thus, we are determined to explore the effects of farnesoid X receptor (FXR) and five bile acids on respiratory rhythm generation and modulation of neonatal rats. Spontaneous periodic respiratory-related rhythmical discharge activity (RRDA) was recorded from hypoglossal nerves during the pe...

  7. Regulation of antibacterial defense in the small intestine by the nuclear bile acid receptor

    Inagaki, Takeshi; Moschetta, Antonio; Lee, Youn-Kyoung; Peng, Li; Zhao, Guixiang; Downes, Michael; Yu, Ruth T.; Shelton, John M.; Richardson, James A.; Repa, Joyce J.; Mangelsdorf, David J.; Kliewer, Steven A.

    2006-03-01

    Obstruction of bile flow results in bacterial proliferation and mucosal injury in the small intestine that can lead to the translocation of bacteria across the epithelial barrier and systemic infection. These adverse effects of biliary obstruction can be inhibited by administration of bile acids. Here we show that the farnesoid X receptor (FXR), a nuclear receptor for bile acids, induces genes involved in enteroprotection and inhibits bacterial overgrowth and mucosal injury in ileum caused by bile duct ligation. Mice lacking FXR have increased ileal levels of bacteria and a compromised epithelial barrier. These findings reveal a central role for FXR in protecting the distal small intestine from bacterial invasion and suggest that FXR agonists may prevent epithelial deterioration and bacterial translocation in patients with impaired bile flow. bacteria | biliary obstruction | epithelial barrier | ileum

  8. Role of farnesoid X receptor and bile acids in alcoholic liver disease

    Sharon Manley

    2015-03-01

    Full Text Available Alcoholic liver disease (ALD is one of the major causes of liver morbidity and mortality worldwide. Chronic alcohol consumption leads to development of liver pathogenesis encompassing steatosis, inflammation, fibrosis, cirrhosis, and in extreme cases, hepatocellular carcinoma. Moreover, ALD may also associate with cholestasis. Emerging evidence now suggests that farnesoid X receptor (FXR and bile acids also play important roles in ALD. In this review, we discuss the effects of alcohol consumption on FXR, bile acids and gut microbiome as well as their impacts on ALD. Moreover, we summarize the findings on FXR, FoxO3a (forkhead box-containing protein class O3a and PPARα (peroxisome proliferator-activated receptor alpha in regulation of autophagy-related gene transcription program and liver injury in response to alcohol exposure.

  9. Affinity and kinetics study of anthranilic acids as HCA2 receptor agonists.

    van Veldhoven, Jacobus P D; Liu, Rongfang; Thee, Stephanie A; Wouters, Yessica; Verhoork, Sanne J M; Mooiman, Christiaan; Louvel, Julien; IJzerman, Adriaan P

    2015-07-15

    Structure-affinity relationship (SAR) and structure-kinetics relationship (SKR) studies were combined to investigate a series of biphenyl anthranilic acid agonists for the HCA2 receptor. In total, 27 compounds were synthesized and twelve of them showed higher affinity than nicotinic acid. Two compounds, 6g (IC50=75nM) and 6z (IC50=108nM) showed a longer residence time profile compared to nicotinic acid, exemplified by their kinetic rate index (KRI) values of 1.31 and 1.23, respectively. The SAR study resulted in the novel 2-F, 4-OH derivative (6x) with an IC50 value of 23nM as the highest affinity HCA2 agonist of the biphenyl series, although it showed a similar residence time as nicotinic acid. The SAR and SKR data suggest that an early compound selection based on binding kinetics is a promising addition to the lead optimization process. PMID:25737085

  10. Specific interaction of aurintricarboxylic acid with the human immunodeficiency virus/CD4 cell receptor

    The triphenylmethane derivative aurintricarboxylic acid (ATA), but not aurin, selectively prevented the binding of OKT4A/Leu-3a monoclonal antibody (mAb) and, to a lesser extent, OKT4 mAb to the CD4 cell receptor for human immunodeficiency virus type 1 (HIV-1). The effect was seen within 1 min at an ATA concentration of 10 μM in various T4+ cells (MT-4, U-937, peripheral blood lymphocytes, and monocytes). It was dose-dependent and reversible. ATA prevented the attachment of radiolabeled HIV-1 particles to MT-4 cells, which could be expected as the result of its specific binding to the HIV/CD4 receptor. Other HIV inhibitors such as suramin, fuchsin acid, azidothymidine, dextran sulfate, heparin, and pentosan polysulfate did not affect OKT4A/Leu-3a mAb binding to the CD4 receptor, although the sulfated polysaccharides suppressed HIV-1 adsorption to the cells at concentrations required for complete protection against HIV-1 cytopathogenicity. Thus, ATA is a selective marker molecule for the CD4 receptor. ATA also interfered with the staining of membrane-associated HIV-1 glycoprotein gp120 by a mAb against it. These unusual properties of a small molecule of nonimmunological origin may have important implications for the study of CD4/HIV/AIDS pathogenesis and possibly treatment

  11. A Novel Bile Acid-Activated Vitamin D Receptor Signaling in Human Hepatocytes

    Han, Shuxin; Li, Tiangang; Ellis, Ewa; Strom, Stephen; Chiang, John Y. L.

    2010-01-01

    Vitamin D receptor (VDR) is activated by natural ligands, 1α, 25-dihydroxy-vitamin D3 [1α,25(OH)2-D3] and lithocholic acid (LCA). Our previous study shows that VDR is expressed in human hepatocytes, and VDR ligands inhibit bile acid synthesis and transcription of the gene encoding cholesterol 7α-hydroxylase (CYP7A1). Primary human hepatocytes were used to study LCA and 1α,25(OH)2-D3 activation of VDR signaling. Confocal immunofluorescent microscopy imaging and immunoblot analysis showed that ...

  12. The evolution of bat nucleic acid-sensing Toll-like receptors.

    Escalera-Zamudio, Marina; Zepeda-Mendoza, M Lisandra; Loza-Rubio, Elizabeth; Rojas-Anaya, Edith; Méndez-Ojeda, Maria L; Arias, Carlos F; Greenwood, Alex D

    2015-12-01

    We characterized the nucleic acid-sensing Toll-like receptors (TLR) of a New World bat species, the common vampire bat (Desmodus rotundus), and through a comparative molecular evolutionary approach searched for general adaptation patterns among the nucleic acid-sensing TLRs of eight different bats species belonging to three families (Pteropodidae, Vespertilionidae and Phyllostomidae). We found that the bat TLRs are evolving slowly and mostly under purifying selection and that the divergence pattern of such receptors is overall congruent with the species tree, consistent with the evolution of many other mammalian nuclear genes. However, the chiropteran TLRs exhibited unique mutations fixed in ligand-binding sites, some of which involved nonconservative amino acid changes and/or targets of positive selection. Such changes could potentially modify protein function and ligand-binding properties, as some changes were predicted to alter nucleic acid binding motifs in TLR 9. Moreover, evidence for episodic diversifying selection acting specifically upon the bat lineage and sublineages was detected. Thus, the long-term adaptation of chiropterans to a wide variety of environments and ecological niches with different pathogen profiles is likely to have shaped the evolution of the bat TLRs in an order-specific manner. The observed evolutionary patterns provide evidence for potential functional differences between bat and other mammalian TLRs in terms of resistance to specific pathogens or recognition of nucleic acids in general. PMID:26503258

  13. Nuclear receptors for retinoic acid and thyroid hormone regulate transcription of keratin genes.

    Tomic, M; Jiang, C K; Epstein, H S; Freedberg, I M; Samuels, H H; M. Blumenberg

    1990-01-01

    In the epidermis, retinoids regulate the expression of keratins, the intermediate filament proteins of epithelial cells. We have cloned the 5' regulatory regions of four human epidermal keratin genes, K#5, K#6, K#10, and K#14, and engineered constructs in which these regions drive the expression of the CAT reporter gene. By co-transfecting the constructs into epithelial cells along with the vectors expressing nuclear receptors for retinoic acid (RA) and thyroid hormone, we have demonstrated t...

  14. FGFR-4, a novel acidic fibroblast growth factor receptor with a distinct expression pattern.

    Partanen, J. (Joni); Mäkelä, T P; Eerola, E.; Korhonen, J; Hirvonen, H; Claesson-Welsh, L; Alitalo, K

    1991-01-01

    We have previously identified two novel members of the fibroblast growth factor receptor (FGFR) gene family expressed in K562 erythroleukemia cells. Here we report cDNA cloning and analysis of one of these genes, named FGFR-4. The deduced amino acid sequence of FGFR-4 is 55% identical with both previously characterized FGFRs, flg and bek, and has the structural characteristics of a FGFR family member including three immunoglobulin-like domains in its extracellular part. Antibodies raised agai...

  15. Functional Analysis of Free Fatty Acid Receptor GPR120 in Human Eosinophils: Implications in Metabolic Homeostasis

    Yasunori Konno; Shigeharu Ueki; Masahide Takeda; Yoshiki Kobayashi; Mami Tamaki; Yuki Moritoki; Hajime Oyamada; Masamichi Itoga; Hiroyuki Kayaba; Ayumi Omokawa; Makoto Hirokawa

    2015-01-01

    Recent evidence has shown that eosinophils play an important role in metabolic homeostasis through Th2 cytokine production. GPR120 (FFA4) is a G protein-coupled receptor (GPCR) for long-chain fatty acids that functions as a regulator of physiological energy metabolism. In the present study, we aimed to investigate whether human eosinophils express GPR120 and, if present, whether it possesses a functional capacity on eosinophils. Eosinophils isolated from peripheral venous blood expressed GPR1...

  16. Lysophosphatidic Acid Receptor Is a Functional Marker of Adult Hippocampal Precursor Cells

    Tara L. Walker; Rupert W. Overall; Steffen Vogler; Alex M. Sykes; Susann Ruhwald; Daniela Lasse; Muhammad Ichwan; Klaus Fabel; Gerd Kempermann

    2016-01-01

    Summary Here, we show that the lysophosphatidic acid receptor 1 (LPA1) is expressed by a defined population of type 1 stem cells and type 2a precursor cells in the adult mouse dentate gyrus. LPA1, in contrast to Nestin, also marks the quiescent stem cell population. Combining LPA1-GFP with EGFR and prominin-1 expression, we have enabled the prospective separation of both proliferative and non-proliferative precursor cell populations. Transcriptional profiling of the isolated proliferative pre...

  17. Inhibition of Receptor Interacting Protein Kinases Attenuates Cardiomyocyte Hypertrophy Induced by Palmitic Acid

    Mingyue Zhao; Lihui Lu; Song Lei; Hua Chai; Siyuan Wu; Xiaoju Tang; Qinxue Bao; Li Chen; Wenchao Wu; Xiaojing Liu

    2016-01-01

    Palmitic acid (PA) is known to cause cardiomyocyte dysfunction. Cardiac hypertrophy is one of the important pathological features of PA-induced lipotoxicity, but the mechanism by which PA induces cardiomyocyte hypertrophy is still unclear. Therefore, our study was to test whether necroptosis, a receptor interacting protein kinase 1 and 3 (RIPK1 and RIPK3-) dependent programmed necrosis, was involved in the PA-induced cardiomyocyte hypertrophy. We used the PA-treated primary neonatal rat cardi...

  18. A gate-latch-lock mechanism for hormone signalling by abscisic acid receptors

    Melcher, Karsten; Ng, Ley-Moy; Zhou, X Edward; Soon, Fen-Fen; Xu, Yong; Suino-Powell, Kelly M; Park, Sang-Youl; Weiner, Joshua J; Fujii, Hiroaki; Chinnusamy, Viswanathan; Kovach, Amanda; Li, Jun; Wang, Yonghong; Li, Jiayang; Peterson, Francis C; Jensen, Davin R; Yong, Eu-Leong; Volkman, Brian F; Cutler, Sean R; Zhu, Jian-Kang; Xu, H Eric; (NU Sinapore); (Van Andel); (MCW); (UCR); (Chinese Aca. Sci.)

    2010-01-12

    Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2-ABA-PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved β-loops that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Together, our results identify a conserved gate-latch-lock mechanism underlying ABA signalling.

  19. A gate-latch-lock mechanism for hormone signalling by abscisic acid receptors

    Melcher, Karsten

    2009-12-03

    Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2-ABA-PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved ?-loops that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Together, our results identify a conserved gate-latch-lock mechanism underlying ABA signalling. © 2009 Macmillan Publishers Limited. All rights reserved.

  20. Structure-based drug design targeting the cell membrane receptor GPBAR1: exploiting the bile acid scaffold towards selective agonism

    Di Leva, Francesco Saverio; Festa, Carmen; Renga, Barbara; Sepe, Valentina; Novellino, Ettore; Fiorucci, Stefano; Zampella, Angela; Limongelli, Vittorio

    2015-01-01

    Bile acids can regulate nutrient metabolism through the activation of the cell membrane receptor GPBAR1 and the nuclear receptor FXR. Developing an exogenous control over these receptors represents an attractive strategy for the treatment of enterohepatic and metabolic disorders. A number of dual GPBAR1/FXR agonists are known, however their therapeutic use is limited by multiple unwanted effects due to activation of the diverse downstream signals controlled by the two receptors. On the other hand, designing selective GPBAR1 and FXR agonists is challenging since the two proteins share similar structural requisites for ligand binding. Here, taking advantage of our knowledge of the two targets, we have identified through a rational drug design study a series of amine lithocholic acid derivatives as selective GPBAR1 agonists. The presence of the 3α-NH2 group on the steroidal scaffold is responsible for the selectivity over FXR unveiling unprecedented structural insights into bile acid receptors activity modulation. PMID:26567894

  1. Structure-based drug design targeting the cell membrane receptor GPBAR1: exploiting the bile acid scaffold towards selective agonism

    di Leva, Francesco Saverio; Festa, Carmen; Renga, Barbara; Sepe, Valentina; Novellino, Ettore; Fiorucci, Stefano; Zampella, Angela; Limongelli, Vittorio

    2015-11-01

    Bile acids can regulate nutrient metabolism through the activation of the cell membrane receptor GPBAR1 and the nuclear receptor FXR. Developing an exogenous control over these receptors represents an attractive strategy for the treatment of enterohepatic and metabolic disorders. A number of dual GPBAR1/FXR agonists are known, however their therapeutic use is limited by multiple unwanted effects due to activation of the diverse downstream signals controlled by the two receptors. On the other hand, designing selective GPBAR1 and FXR agonists is challenging since the two proteins share similar structural requisites for ligand binding. Here, taking advantage of our knowledge of the two targets, we have identified through a rational drug design study a series of amine lithocholic acid derivatives as selective GPBAR1 agonists. The presence of the 3α-NH2 group on the steroidal scaffold is responsible for the selectivity over FXR unveiling unprecedented structural insights into bile acid receptors activity modulation.

  2. Bile acid promotes liver regeneration via farnesoid X receptor signaling pathways in rats.

    Ding, Long; Yang, Yu; Qu, Yikun; Yang, Ting; Wang, Kaifeng; Liu, Weixin; Xia, Weibin

    2015-06-01

    Bile acids, which are synthesized from cholesterol in the hepatocytes of the liver, are amphipathic molecules with a steroid backbone. Studies have shown that bile acid exhibits important effects on liver regeneration. However, the mechanism underlying these effects remains unclear. The aim of the present study was to investigate the effect of bile acid and the farnesoid X receptor (FXR) on hepatic regeneration and lipid metabolism. Rats were fed with 0.2% bile acid or glucose for 7 days and then subjected to a 50 or 70% hepatectomy. Hepatic regeneration rate, serum and liver levels of bile acid, and expression of FXR and Caveolin‑1, were detected at 24, 48 or 72 h following hepatectomy. The expression of proliferating cell nuclear antigen (PCNA) in the liver was measured using immunohistochemistry at the end of the study. Hepatocytes isolated from rats were treated with bile acid, glucose, FXR agonist and FXR antagonist, separately or in combination. Lipid metabolism, the expression of members of the FXR signaling pathway and energy metabolism‑related factors were measured using ELISA kits or western blotting. Bile acid significantly increased the hepatic regeneration rate and the expression of FXR, Caveolin‑1 and PCNA. Levels of total cholesterol and high density lipoprotein were increased in bile acid‑ or FXR agonist‑treated hepatocytes in vitro. Levels of triglyceride, low density lipoprotein and free fatty acid were decreased. In addition, bile acid and FXR agonists increased the expression of bile salt export pump and small heterodimer partner, and downregulated the expression of apical sodium‑dependent bile acid transporter, Na+/taurocholate cotransporting polypeptide and cholesterol 7α‑hydroxylase. These results suggested that physiological concentrations of bile acid may promote liver regeneration via FXR signaling pathways, and may be associated with energy metabolism. PMID:25634785

  3. PTH1 receptor is involved in mediating cellular response to long-chain polyunsaturated fatty acids.

    Jose Candelario

    Full Text Available The molecular pathways by which long chain polyunsaturated fatty acids (LCPUFA influence skeletal health remain elusive. Both LCPUFA and parathyroid hormone type 1 receptor (PTH1R are known to be involved in bone metabolism while any direct link between the two is yet to be established. Here we report that LCPUFA are capable of direct, PTH1R dependent activation of extracellular ligand-regulated kinases (ERK. From a wide range of fatty acids studied, varying in chain length, saturation, and position of double bonds, eicosapentaenoic (EPA and docosahexaenoic fatty acids (DHA caused the highest ERK phosphorylation. Moreover, EPA potentiated the effect of parathyroid hormone (PTH(1-34 in a superagonistic manner. EPA or DHA dependent ERK phosphorylation was inhibited by the PTH1R antagonist and by knockdown of PTH1R. Inhibition of PTH1R downstream signaling molecules, protein kinases A (PKA and C (PKC, reduced EPA and DHA dependent ERK phosphorylation indicating that fatty acids predominantly activate G-protein pathway and not the β-arrestin pathway. Using picosecond time-resolved fluorescence microscopy and a genetically engineered PTH1R sensor (PTH-CC, we detected conformational responses to EPA similar to those caused by PTH(1-34. PTH1R antagonist blocked the EPA induced conformational response of the PTH-CC. Competitive binding studies using fluorescence anisotropy technique showed that EPA and DHA competitively bind to and alter the affinity of PTH1 receptor to PTH(1-34 leading to a superagonistic response. Finally, we showed that EPA stimulates protein kinase B (Akt phosphorylation in a PTH1R-dependent manner and affects the osteoblast survival pathway, by inhibiting glucocorticoid-induced cell death. Our findings demonstrate for the first time that LCPUFAs, EPA and DHA, can activate PTH1R receptor at nanomolar concentrations and consequently provide a putative molecular mechanism for the action of fatty acids in bone.

  4. Association of Gamma-Aminobutyric Acid A Receptor α2 Gene (GABRA2) with Alcohol Use Disorder

    Li, Dawei.; Sulovari, Arvis; Cheng, Chao; Zhao, Hongyu; Henry R Kranzler; Gelernter, Joel

    2013-01-01

    Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in mammalian brain. GABA receptor are involved in a number of complex disorders, including substance abuse. No variants of the commonly studied GABA receptor genes that have been associated with substance dependence have been determined to be functional or pathogenic. To reconcile the conflicting associations with substance dependence traits, we performed a meta-analysis of variants in the GABAA receptor genes (GABRB2, GABR...

  5. 3-pyrazolone analogues of the 3-isoxazolol metabotropic excitatory amino acid receptor agonist homo-AMPA. Synthesis and pharmacological testing

    Zimmermann, D.; Janin, Y.L.; Brehm, L.;

    1999-01-01

    We have previously shown that the higher homologue of (S)-glutamic acid [(S)-Glu], (S)-a-aminoadipic acid [(S)-a-AA] is selectively recognized by the mGlu and mGlu subtypes of the family of metabotropic glutamic acid (mGlu) receptors. Furthermore, a number of analogues of (S)-a-AA, in which the......-acetylbutyrolactone (4). Neither 1 nor 2 showed significant effects at the different types of ionotropic glutamic acid receptors or at mGlu(1a) (group I), mGlu (group II), and mGlu(4a) and mGlu (group III) receptors, representing the three indicated groups of mGlu receptors....

  6. Dendritic Assembly of Heteromeric γ-Aminobutyric Acid Type B Receptor Subunits in Hippocampal NeuronsS⃞

    Ramírez, Omar A.; Vidal, René L.; Tello, Judith A.; Vargas, Karina J.; Kindler, Stefan; Härtel, Steffen; Couve, Andrés

    2009-01-01

    Understanding the mechanisms that control synaptic efficacy through the availability of neurotransmitter receptors depends on uncovering their specific intracellular trafficking routes. γ-Aminobutyric acid type B (GABAB) receptors (GABABRs) are obligatory heteromers present at dendritic excitatory and inhibitory postsynaptic sites. It is unknown whether synthesis and assembly of GABABRs occur in the somatic endoplasmic reticulum (ER) followed by vesicular transport to ...

  7. Pharmacological characterization of mouse GPRC6A, an L-alpha-amino-acid receptor modulated by divalent cations

    Christiansen, B; Hansen, K B; Wellendorph, P; Bräuner-Osborne, Hans

    2007-01-01

    GPRC6A is a novel member of family C of G protein-coupled receptors with so far unknown function. We have recently described both human and mouse GPRC6A as receptors for L-alpha-amino acids. To date, functional characterization of wild-type GPRC6A has been impaired by the lack of activity in quan...

  8. Fatty Acid Amide Hydrolase (FAAH) Inhibition Enhances Memory Acquisition through Activation of PPAR-alpha Nuclear Receptors

    Mazzola, Carmen; Medalie, Julie; Scherma, Maria; Panlilio, Leigh V.; Solinas, Marcello; Tanda, Gianluigi; Drago, Filippo; Cadet, Jean Lud; Goldberg, Steven R.; Yasar, Sevil

    2009-01-01

    Inhibitors of fatty acid amide hydrolase (FAAH) increase endogenous levels of anandamide (a cannabinoid CB[subscript 1]-receptor ligand) and oleoylethanolamide and palmitoylethanolamide (OEA and PEA, ligands for alpha-type peroxisome proliferator-activated nuclear receptors, PPAR-alpha) when and where they are naturally released in the brain.…

  9. Loss of Nuclear Receptor SHP Impairs but Does Not Eliminate Negative Feedback Regulation of Bile Acid Synthesis

    Kerr, Thomas A.; Saeki, Shigeru; Schneider, Manfred; Schaefer, Karen; Berdy, Sara; Redder, Thadd; Shan, Bei; Russell, David W.; Schwarz, Margrit

    2002-01-01

    The in vivo role of the nuclear receptor SHP in feedback regulation of bile acid synthesis was examined. Loss of SHP in mice caused abnormal accumulation and increased synthesis of bile acids due to derepression of rate-limiting CYP7A1 and CYP8B1 hydroxylase enzymes in the biosynthetic pathway. Dietary bile acids induced liver damage and restored feedback regulation. A synthetic agonist of the nuclear receptor FXR was not hepatotoxic and had no regulatory effects. Reduction of the bile acid p...

  10. Isoflavones enhance interleukin-17 gene expression via retinoic acid receptor-related orphan receptors α and γ

    Highlights: • Nuclear receptors, RORα and RORγ, are key regulators of Th17 cell differentiation. • Isoflavones have RORα/γ agonistic activities. • Isoflavones enhance the interaction of RORα/γ with co-activator. • These compounds enhance the expression of Il17a mRNA in mouse EL4 cells. • Dietary isoflavones can act as modulators of Il17a expression via RORα/γ. - Abstract: The retinoic acid receptor-related orphan receptors α and γ (RORα and RORγ), are key regulators of helper T (Th)17 cell differentiation, which is involved in the innate immune system and autoimmune disorders. In this study, we investigated the effects of isoflavones on RORα/γ activity and the gene expression of interleukin (IL)-17, which mediates the function of Th17 cells. In doxycycline-inducible CHO stable cell lines, we found that four isoflavones, biochanin A (BA), genistein, formononetin, and daidzein, enhanced RORα- or RORγ-mediated transcriptional activity in a dose-dependent manner. In an activation assay of the Il17a promoter using Jurkat cells, these compounds enhanced the RORα- or RORγ-mediated activation of the Il17a promoter at concentrations of 1 × 10−6 M to 1 × 10−5 M. In mammalian two-hybrid assays, the four isoflavones enhanced the interaction between the RORα- or RORγ-ligand binding domain and the co-activator LXXLL peptide in a dose-dependent manner. In addition, these isoflavones potently enhanced Il17a mRNA expression in mouse T lymphoma EL4 cells treated with phorbol myristate acetate and ionomycin, but showed slight enhancement of Il17a gene expression in RORα/γ-knockdown EL4 cells. Immunoprecipitation and immunoblotting assays also revealed that BA enhanced the interaction between RORγt and SRC-1, which is a co-activator for nuclear receptors. Taken together, these results suggest that the isoflavones have the ability to enhance IL-17 gene expression by stabilizing the interactions between RORα/γ and co-activators. This also

  11. Bile acid-activated nuclear receptor FXR suppresses apolipoprotein A-I transcription via a negative FXR response element

    Claudel, Thierry; Sturm, Ekkehard; Duez, Hélène; Torra, Inés Pineda; Sirvent, Audrey; Kosykh, Vladimir; Fruchart, Jean-Charles; Dallongeville, Jean; Hum, Dean W; Kuipers, Folkert; Staels, Bart

    2002-01-01

    Serum levels of HDL are inversely correlated with the risk of coronary heart disease. The anti-atherogenic effect of HDL is partially mediated by its major protein constituent apoA-I. In this study, we identify bile acids that are activators of the nuclear receptor farnesoid X receptor (FXR) as negative regulators of human apoA-I expression. Intrahepatocellular accumulation of bile acids, as seen in patients with progressive familial intrahepatic cholestasis and biliary atresia, was associate...

  12. Expression, protein stability and transcriptional activity of retinoic acid receptors are affected by microtubules interfering agents and all-trans retinoic acid in primary rat hepatocytes

    2007-01-01

    Expression, protein stability and transcriptional activity of retinoic acid receptors are affected by microtubules interfering agents and all-trans retinoic acid in primary rat hepatocytes CZECH REPUBLIC (Dvorak, Zdenek) CZECH REPUBLIC Received: 2006-08-22 Revised: 2006-11-16 Accepted: 2007-01-02

  13. Rapid assessment response (RAR study: drug use and health risk - Pretoria, South Africa

    Trautmann Franz

    2011-06-01

    Full Text Available Abstract Background Within a ten year period South Africa has developed a substantial illicit drug market. Data on HIV risk among drug using populations clearly indicate high levels of HIV risk behaviour due to the sharing of injecting equipment and/or drug-related unprotected sex. While there is international evidence on and experience with adequate responses, limited responses addressing drug use and drug-use-related HIV and other health risks are witnessed in South Africa. This study aimed to explore the emerging problem of drug-related HIV transmission and to stimulate the development of adequate health services for the drug users, by linking international expertise and local research. Methods A Rapid Assessment and Response (RAR methodology was adopted for the study. For individual and focus group interviews a semi-structured questionnaire was utilised that addressed key issues. Interviews were conducted with a total of 84 key informant (KI participants, 63 drug user KI participants (49 males, 14 females and 21 KI service providers (8 male, 13 female. Results and Discussion Adverse living conditions and poor education levels were cited as making access to treatment harder, especially for those living in disadvantaged areas. Heroin was found to be the substance most available and used in a problematic way within the Pretoria area. Participants were not fully aware of the concrete health risks involved in drug use, and the vague ideas held appear not to allow for concrete measures to protect themselves. Knowledge with regards to substance related HIV/AIDS transmission is not yet widespread, with some information sources disseminating incorrect or unspecific information. Conclusions The implementation of pragmatic harm-reduction and other evidence-based public health care policies that are designed to reduce the harmful consequences associated with substance use and HIV/AIDS should be considered. HIV testing and treatment services also need to

  14. Drug discovery opportunities and challenges at G protein coupled receptors for long chain free fatty acids

    Nicholas D Holliday

    2012-01-01

    Full Text Available Discovery of G protein coupled receptors for long chain free fatty acids (FFAs, FFA1 (GPR40 and GPR120, has expanded our understanding of these nutrients as signalling molecules. These receptors have emerged as important sensors for FFA levels in the circulation or the gut lumen, based on evidence from in vitro and rodent models, and an increasing number of human studies. Here we consider their promise as therapeutic targets for metabolic disease, including type 2 diabetes and obesity. FFA1 directly mediates acute FFA-induced glucose-stimulated insulin secretion in pancreatic beta-cells, while GPR120 and FFA1 trigger release of incretins from intestinal endocrine cells, and so indirectly enhance insulin secretion and promote satiety. GPR120 signalling in adipocytes and macrophages also results in insulin sensitizing and beneficial anti-inflammatory effects. Drug discovery has focussed on agonists to replicate acute benefits of FFA receptor signalling, with promising early results for FFA1 agonists in man. Controversy surrounding chronic effects of FFA1 on beta-cells illustrates that long term benefits of antagonists also need exploring. It has proved challenging to generate highly selective potent ligands for FFA1 or GPR120 subtypes, given that both receptors have hydrophobic orthosteric binding sites, which are not completely defined and have modest ligand affinity. Structure activity relationships are also reliant on functional read outs, in the absence of robust binding assays to provide direct affinity estimates. Nevertheless synthetic ligands have already helped dissect specific contributions of FFA1 and GPR120 signalling from the many possible cellular effects of FFAs. Approaches including use of fluorescent ligand binding assays, and targeting allosteric receptor sites, may improve further preclinical ligand development at these receptors, to exploit their unique potential to target multiple facets of diabetes.

  15. Ginseng pharmacology: a new paradigm based on gintonin-lysophosphatidic acid receptor interactions

    Seung-Yeol eNah

    2015-10-01

    Full Text Available Ginseng, the root of Panax ginseng, is used as a traditional medicine. Despite the long history of the use of ginseng, there is no specific scientific or clinical rationale for ginseng pharmacology besides its application as a general tonic. The ambiguous description of ginseng pharmacology might be due to the absence of a predominant active ingredient that represents ginseng pharmacology. Recent studies show that ginseng abundantly contains lysophosphatidic acids (LPAs, which are phospholipid-derived growth factor with diverse biological functions including those claimed to be exhibited by ginseng. LPAs in ginseng form a complex with ginseng proteins, which can bind and deliver LPA to its cognate receptors with a high affinity. As a first messenger, gintonin produces second messenger Ca2+ via G protein-coupled LPA receptors. Ca2+ is an intracellular mediator of gintonin and initiates a cascade of amplifications for further intercellular communications by activation of Ca2+-dependent kinases, receptors, gliotransmitter and neurotransmitter release. Ginsenosides, which have been regarded as primary ingredients of ginseng, cannot elicit intracellular [Ca2+]i transients, since they lack specific cell surface receptor. However, ginsenosides exhibit non-specific ion channel and receptor regulations. This is the key characteristic that distinguishes gintonin from ginsenosides. Although the current discourse on ginseng pharmacology is focused on ginsenosides, gintonin can definitely provide a mode of action for ginseng pharmacology that ginsenosides cannot. This review article introduces a novel concept of ginseng ligand-LPA receptor interaction and proposes to establish a paradigm that shifts the focus from ginsenosides to gintonin as a major ingredient representing ginseng pharmacology.

  16. Activation of transmembrane bile acid receptor TGR5 stimulates insulin secretion in pancreatic β cells

    Highlights: ► G protein coupled receptor TGR5 is expressed in mouse and human islets. ► TGR5 is coupled to activation of Gs and Ca2+ release via cAMP/Epac/PLC-ε pathway. ► Activation of TGR5 by bile salts and selective ligands causes insulin secretion. ► TGR5 could be a potential therapeutic target to treat diabetes. -- Abstract: Bile acids act as signaling molecules and stimulate the G protein coupled receptor, TGR5, in addition to nuclear farnesoid X receptor to regulate lipid, glucose and energy metabolism. Bile acid induced activation of TGR5 in the enteroendocrine cells promotes glucagon like peptide-1 (GLP-1) release, which has insulinotropic effect in the pancreatic β cells. In the present study, we have identified the expression of TGR5 in pancreatic β cell line MIN6 and also in mouse and human pancreatic islets. TGR5 selective ligands, oleanolic acid (OA) and INT-777 selectively activated Gαs and caused an increase in intracellular cAMP and Ca2+. OA and INT-777 also increased phosphoinositide (PI) hydrolysis and the increase was blocked by NF449 (a selective Gαs inhibitor) or (U73122) (PI hydrolysis inhibitor). OA, INT-777 and lithocholic acid increased insulin release in MIN6 and human islets and the increase was inhibited by treatment with NF449, (U73122) or BAPTA-AM (chelator of calcium), but not with myristoylated PKI (PKA inhibitor), suggesting that the release is dependent on Gs/cAMP/Ca2+ pathway. 8-pCPT-2′-O-Me-cAMP, a cAMP analog, which activates Epac, but not PKA also stimulated PI hydrolysis. In conclusion, our study demonstrates that the TGR5 expressed in the pancreatic β cells regulates insulin secretion and highlights the importance of ongoing therapeutic strategies targeting TGR5 in the control of glucose homeostasis.

  17. A novel bile acid-activated vitamin D receptor signaling in human hepatocytes.

    Han, Shuxin; Li, Tiangang; Ellis, Ewa; Strom, Stephen; Chiang, John Y L

    2010-06-01

    Vitamin D receptor (VDR) is activated by natural ligands, 1alpha, 25-dihydroxy-vitamin D(3) [1alpha,25(OH)(2)-D(3)] and lithocholic acid (LCA). Our previous study shows that VDR is expressed in human hepatocytes, and VDR ligands inhibit bile acid synthesis and transcription of the gene encoding cholesterol 7alpha-hydroxylase (CYP7A1). Primary human hepatocytes were used to study LCA and 1alpha,25(OH)(2)-D(3) activation of VDR signaling. Confocal immunofluorescent microscopy imaging and immunoblot analysis showed that LCA and 1alpha, 25(OH)(2)-D(3) induced intracellular translocation of VDR from the cytosol to the nucleus and also plasma membrane where VDR colocalized with caveolin-1. VDR ligands induced tyrosine phosphorylation of c-Src and VDR and their interaction. Inhibition of c-Src abrogated VDR ligand-dependent inhibition of CYP7A1 mRNA expression. Kinase assays showed that VDR ligands specifically activated the c-Raf/MEK1/2/extracellular signal-regulated kinase (ERK) 1/2 pathway, which stimulates serine phosphorylation of VDR and hepatocyte nuclear factor-4alpha, and their interaction. Mammalian two-hybrid assays showed a VDR ligand-dependent interaction of nuclear receptor corepressor-1 and silencing mediator of retinoid and thyroid with VDR/retinoid X receptor-alpha (RXRalpha). Chromatin immunoprecipitation assays revealed that an ERK1/2 inhibitor reversed VDR ligand-induced recruitment of VDR, RXRalpha, and corepressors to human CYP7A1 promoter. In conclusion, VDR ligands activate membrane VDR signaling to activate the MEK1/2/ERK1/2 pathway, which stimulates nuclear VDR/RXRalpha recruitment of corepressors to inhibit CYP7A1 gene transcription in human hepatocytes. This membrane VDR-signaling pathway may be activated by bile acids to inhibit bile acid synthesis as a rapid response to protect hepatocytes from cholestatic liver injury. PMID:20371703

  18. Functional analysis of free fatty acid receptor GPR120 in human eosinophils: implications in metabolic homeostasis.

    Yasunori Konno

    Full Text Available Recent evidence has shown that eosinophils play an important role in metabolic homeostasis through Th2 cytokine production. GPR120 (FFA4 is a G protein-coupled receptor (GPCR for long-chain fatty acids that functions as a regulator of physiological energy metabolism. In the present study, we aimed to investigate whether human eosinophils express GPR120 and, if present, whether it possesses a functional capacity on eosinophils. Eosinophils isolated from peripheral venous blood expressed GPR120 at both the mRNA and protein levels. Stimulation with a synthetic GPR120 agonist, GW9508, induced rapid down-regulation of cell surface expression of GPR120, suggesting ligand-dependent receptor internalization. Although GPR120 activation did not induce eosinophil chemotactic response and degranulation, we found that GW9508 inhibited eosinophil spontaneous apoptosis and Fas receptor expression. The anti-apoptotic effect was attenuated by phosphoinositide 3-kinase (PI3K inhibitors and was associated with inhibition of caspase-3 activity. Eosinophil response investigated using ELISpot assay indicated that stimulation with a GPR120 agonist induced IL-4 secretion. These findings demonstrate the novel functional properties of fatty acid sensor GPR120 on human eosinophils and indicate the previously unrecognized link between nutrient metabolism and the immune system.

  19. Recognition and sequestration of ω-fatty acids by a cavitand receptor.

    Mosca, Simone; Ajami, Dariush; Rebek, Julius

    2015-09-01

    One of the largest driving forces for molecular association in aqueous solution is the hydrophobic effect, and many synthetic receptors with hydrophobic interiors have been devised for molecular recognition studies in water. Attempts to create the longer, narrower cavities appropriate for long-chain fatty acids have been thwarted by solvophobic collapse of the synthetic receptors, giving structures that have no internal spaces. The collapse generally involves the stacking of aromatic panels onto themselves. We describe here the synthesis and application of a deep cavitand receptor featuring "prestacked" aromatic panels at the upper rim of the binding pocket. The cavitand remains open and readily sequesters biologically relevant long-chain molecules-unsaturated ω-3, -6, and -9 fatty acids and derivatives such as anandamide-from aqueous media. The cavitand exists in isomeric forms with different stacking geometries and n-alkanes were used to characterize the binding modes and conformational properties. Long alkyl chains are accommodated in inverted J-shaped conformations. An analogous cavitand with electron-rich aromatic walls was prepared and comparative binding experiments indicated the role of intramolecular stacking in the binding properties of these deep container molecules. PMID:26305974

  20. Comparison of the effects of pelargonic acid vanillylamide and capsaicin on human vanilloid receptors.

    Weiser, Thomas; Roufogalis, Basil; Chrubasik, Sigrun

    2013-07-01

    Pelargonic acid vanillylamide is like capsaicin a natural capsaicinoid from chili peppers and commonly used in food additives to create a hot sensation, even in self-defense pepper sprays and as an alternative to capsaicin in medical products for topical treatment of pain. Although the chemical structures of both compounds are similar, preclinical data suggest that capsaicin is the more potent compound. We therefore performed voltage-clamp recordings using cells transfected with the human vanilloid receptor TRPV1 in order to assess the responses of pelargonic acid vanillylamide and capsaicin at the receptor level. We provide evidence that at the molecular target TRPV1, the concentration-response curves, kinetics of current activation, as well as inhibition by the competitive antagonist capsazepine were not significantly different between the two capsaicinoids. We suggest that the different effects of the two capsaicinoids observed in previous studies may rather be due to different physicochemical or pharmacokinetic properties than to different pharmacological profiles at the receptor level. PMID:22961689

  1. Application of gamma-aminobutyric acid type A-benzodiazepine receptor imaging for study of neuropsychiatric disorders

    Gamma-aminobutyric acid type A-benzodiazepine receptors are heterogeneous polypeptide pentamers widely spread in the central nervous system on the neuron membrane. Different subunit combinations educe various neuro-inhibitory pharmacological effects such as sedative, hypnosis, anticonvulsion and anxiolysis. PET can be utilized to study the binding of the receptors in vivo. PET radioligands of gamma-aminobutyric acid type A-benzodiazepine receptors can be classified into 3 types: antagonists,agonists and reverse agonists, of which antagonist radiotracer 11C-flumazenil is the most commonly applied in epilepsy, anxiety disorders, depression, vegetative state,addiction and other neuro-psychiatric disorders. (authors)

  2. Waking action of ursodeoxycholic acid (UDCA involves histamine and GABAA receptor block.

    Yevgenij Yanovsky

    Full Text Available Since ancient times ursodeoxycholic acid (UDCA, a constituent of bile, is used against gallstone formation and cholestasis. A neuroprotective action of UDCA was demonstrated recently in models of Alzheimer's disease and retinal degeneration. The mechanisms of UDCA action in the nervous system are poorly understood. We show now that UDCA promotes wakefulness during the active period of the day, lacking this activity in histamine-deficient mice. In cultured hypothalamic neurons UDCA did not affect firing rate but synchronized the firing, an effect abolished by the GABA(AR antagonist gabazine. In histaminergic neurons recorded in slices UDCA reduced amplitude and duration of spontaneous and evoked IPSCs. In acutely isolated histaminergic neurons UDCA inhibited GABA-evoked currents and sIPSCs starting at 10 µM (IC(50 = 70 µM and did not affect NMDA- and AMPA-receptor mediated currents at 100 µM. Recombinant GABA(A receptors composed of α1, β1-3 and γ2L subunits expressed in HEK293 cells displayed a sensitivity to UDCA similar to that of native GABA(A receptors. The mutation α1V256S, known to reduce the inhibitory action of pregnenolone sulphate, reduced the potency of UDCA. The mutation α1Q241L, which abolishes GABA(AR potentiation by several neurosteroids, had no effect on GABA(AR inhibition by UDCA. In conclusion, UDCA enhances alertness through disinhibition, at least partially of the histaminergic system via GABA(A receptors.

  3. Upregulation of peroxisome proliferator-activated receptors and liver fatty acid binding protein in hepatic cells of broiler chicken supplemented with conjugated linoleic acids

    Suriya Kumari Ramiah; Goh Y. Meng; Mahdi Ebrahimi

    2015-01-01

    Since conjugated linoleic acid (CLA) has structural and physiological characteristics similar to peroxisome proliferators, it is hypothesized that CLA would upregulate peroxisome proliferator-activated receptor (PPAR) and liver fatty acid binding protein (LFABP) in the liver of broiler chicken. The aim of the present study was to determine fatty acid composition of liver in CLA-fed broiler chickens and the genes associated with hepatic lipid metabolism. A total of 180-day-old broiler chicks w...

  4. Analysis of ileal sodium/bile acid cotransporter and related nuclear receptor genes in a family with multiple cases of idiopathic bile acid malabsorption

    Marco Montagnani; Anna Abrahamsson; Cecilia G(a)lman; G(o)sta Eggertsen; Hanns-Ulrich Marschall; Elisa Ravaioli; Curt Einarsson; Paul A Dawson

    2006-01-01

    The etiology of most cases of idiopathic bile acid malabsorption (TBAM) is unknown. Tn this study, a Swedish family with bile acid malabsorption in three consecutive generations was screened for mutations in the ileal apical sodium-bile acid cotransporter gene (ASBT; gene symbol, SLC10A2) and in the genes for several of the nuclear receptors known to be important for ASBT expression: the farnesoid X receptor (FXR)and peroxisome proliferator activated receptor alpha (PPARα). The patients presented with a clinical history of idiopathic chronic watery diarrhea, which was responsive to cholestyramine treatment and consistent with IBAM. Bile acid absorption was determined using 75Se-homocholic acid taurine(SeHCAT); bile acid synthesis was estimated by measuring the plasma levels of 7α-hydroxy-4-cholesten-3-one (C4). The ASBT,FXR, and PPARα genes in the affected and unaffected family members were analyzed using single stranded conformation polymorphism (SSCP), denaturing HPLC,and direct sequencing. No ASBT mutations were identified and the ASBT gene did not segregate with the bile acid malabsorption phenotype. Similarly, no mutations or polymorphisms were identified in the FXR or PPARα genes associated with the bile acid malabsorption phenotype. These studies indicate that the intestinal bile acid malabsorption in these patients cannot be attributed to defects in ASBT. In the absence of apparent ileal disease, alternative explanations such as accelerated transit through the small intestine may be responsible for the IBAM.

  5. Characterization of influenza virus sialic acid receptors in minor poultry species

    Nieto Gloria

    2010-12-01

    Full Text Available Abstract It is commonly accepted that avian influenza viruses (AIVs bind to terminal α2,3 sialic acid (SA residues whereas human influenza viruses bind to α2,6 SA residues. By a series of amino acid changes on the HA surface protein, AIVs can switch receptor specificity and recognize α2,6 SA positive cells, including human respiratory epithelial cells. Animal species, like pigs and Japanese quail, that contain both α2,3 and α2,6 SA become ideal environments for receptor switching. Here, we describe the SA patterns and distributions in 6 common minor domestic poultry species: Peking duck, Toulouse geese, Chinese ring-neck pheasant, white midget turkey, bobwhite quail, and pearl guinea fowl. Lectins specific to α2,3 and α2,6 SA (Maakia amurensis agglutinin and Sambuca nigra agglutinin, respectively were used to detect SA by an alkaline phosphotase-based method and a fluorescent-based method. Differences in SA moieties and their ability to bind influenza viruses were visualized by fluorescent labeling of 4 different H3N2 influenza viruses known to be specific for one receptor or the other. The geese and ducks showed α2,3 SA throughout the respiratory tract and marginal α2,6 SA only in the colon. The four other avian species showed both α2,3 and α2,6 SA in the respiratory tract and the intestines. Furthermore, the turkey respiratory tract showed a positive correlation between age and α2,6 SA levels. The fact that these birds have both avian and human flu receptors, combined with their common presence in backyard farms and live bird markets worldwide, mark them as potential mixing bowl species and necessitates improved surveillance and additional research about the role of these birds in influenza host switching.

  6. Fatty acid binding sites of serum albumin as membrane receptor analogs for streptococcal lipoteichoic acid.

    Simpson, W A; Ofek, I; Beachey, E H

    1980-01-01

    The ability of bovine serum albumin to inhibit the binding of group A streptococcal lipoteichoic acid (LTA) to human cells was investigated. Albumin blocked the ability of LTA to sensitize erythrocytes to agglutinate in the presence of anti-LTA in a dose-dependent manner. The inhibition of LTA binding to erythrocytes was demonstrated directly with radiolabeled LTA. At an albumin/LTA molar ratio of 1.5:1, albumin binding of the radiolabeled LTA at erythrocytes was inhibited by 45%. Analysis of...

  7. 4-Alkylated homoibotenic acid (HIBO) analogues: versatile pharmacological agents with diverse selectivity profiles towards metabotropic and ionotropic glutamate receptor subtypes

    Madsen, Ulf; Pickering, Darryl S; Nielsen, Birgitte; Bräuner-Osborne, Hans

    4-Alkylated analogues of homoibotenic acid (HIBO) have previously shown high potency and selectivity at ionotropic and metabotropic glutamic acid receptor (iGluR and mGluR) subtypes. Compounds with different selectivity profiles are valuable pharmacological tools for neuropharmacological studies,...

  8. Effect of propofol on the reactivity of acetylcholinesterase, N-methyl-D-aspartate receptors, and gamma-aminobutyric acid receptors in the hippocampus of aged rats after chronic cerebral ischemia

    Gang Chen; Jiangbei Cao; Weidong Mi

    2011-01-01

    We induced ischemic brain injury in aging rats to examine the effects of varying doses of propofol on hippocampal activities of acetylcholinesterase, N-methyl-D-aspartate receptors, and γ-aminobutyric acid receptors. Propofol exhibited no obvious impact on acetylcholinesterase activity, but directly activated the γ-aminobutyric acid receptor. The neuroprotective function of propofol on the hippocampus of aging rats following cerebral ischemic injury may be related to altered activities of γ-aminobutyric acid receptors and N-methyl-D-aspartate receptors.

  9. The short-chain fatty acid receptor, FFA2, contributes to gestational glucose homeostasis.

    Fuller, Miles; Priyadarshini, Medha; Gibbons, Sean M; Angueira, Anthony R; Brodsky, Michael; Hayes, M Geoffrey; Kovatcheva-Datchary, Petia; Bäckhed, Fredrik; Gilbert, Jack A; Lowe, William L; Layden, Brian T

    2015-11-15

    The structure of the human gastrointestinal microbiota can change during pregnancy, which may influence gestational metabolism; however, a mechanism of action remains unclear. Here we observed that in wild-type (WT) mice the relative abundance of Actinobacteria and Bacteroidetes increased during pregnancy. Along with these changes, short-chain fatty acids (SCFAs), which are mainly produced through gut microbiota fermentation, significantly changed in both the cecum and peripheral blood throughout gestation in these mice. SCFAs are recognized by G protein-coupled receptors (GPCRs) such as free fatty acid receptor-2 (FFA2), and we have previously demonstrated that the fatty acid receptor-2 gene (Ffar2) expression is higher in pancreatic islets during pregnancy. Using female Ffar2-/- mice, we explored the physiological relevance of signaling through this GPCR and found that Ffar2-deficient female mice developed fasting hyperglycemia and impaired glucose tolerance in the setting of impaired insulin secretion compared with WT mice during, but not before, pregnancy. Insulin tolerance tests were similar in Ffar2-/- and WT mice before and during pregnancy. Next, we examined the role of FFA2 in gestational β-cell mass, observing that Ffar2-/- mice had diminished gestational expansion of β-cells during pregnancy. Interestingly, mouse genotype had no significant impact on the composition of the gut microbiome, but did affect the observed SCFA profiles, suggesting a functional difference in the microbiota. Together, these results suggest a potential link between increased Ffar2 expression in islets and the alteration of circulating SCFA levels, possibly explaining how changes in the gut microbiome contribute to gestational glucose homeostasis. PMID:26394664

  10. Anthranilic acid derivatives as nuclear receptor modulators--development of novel PPAR selective and dual PPAR/FXR ligands.

    Merk, Daniel; Lamers, Christina; Weber, Julia; Flesch, Daniel; Gabler, Matthias; Proschak, Ewgenij; Schubert-Zsilavecz, Manfred

    2015-02-01

    Nuclear receptors, especially the peroxisome proliferator activated receptors (PPARs) and the farnesoid X receptor (FXR) fulfill crucial roles in metabolic balance. Their activation offers valuable therapeutic potential which has high clinical relevance with the fibrates and glitazones as PPAR agonistic drugs. With growing knowledge about the various functions of nuclear receptors in many disorders, new selective or dual ligands of these pharmaceutical targets are however still required. Here we report the class of anthranilic acid derivatives as novel selective PPAR or dual FXR/PPAR ligands. We identified distinct molecular determinants that govern selectivity for each PPAR subtype or FXR as well as the amplitude of activation of the respective receptors. We thereby discovered several lead compounds for further optimization and developed a highly potent dual PPARα/FXR partial agonist that might have a beneficial synergistic effect on lipid homeostasis by simultaneous activation of two nuclear receptors involved in lipid metabolism. PMID:25583100

  11. A conserved aspartic acid is important for agonist (VUAA1 and odorant/tuning receptor-dependent activation of the insect odorant co-receptor (Orco.

    Brijesh N Kumar

    Full Text Available Insect odorant receptors function as heteromeric odorant-gated cation channels comprising a conventional odorant-sensitive tuning receptor, and a conserved co-receptor (Orco. An Orco agonist, VUAA1, is able to activate both heteromeric and homomeric Orco-containing channels. Very little is known about specific residues in Orco that contribute to cation permeability and gating. We investigated the importance of two conserved Asp residues, one in each of transmembrane domains 5 and 7, for channel function by mutagenesis. Drosophila melanogaster Orco and its substitution mutants were expressed in HEK cells and VUAA1-stimulated channel activity was determined by Ca(2+ influx and whole-cell patch clamp electrophysiology. Substitution of D466 in transmembrane 7 with amino acids other than glutamic acid resulted in a substantial reduction in channel activity. The D466E Orco substitution mutant was ~2 times more sensitive to VUAA1. The permeability of the D466E Orco mutant to cations was unchanged relative to wild-type Orco. When D466E Orco is co-expressed with a conventional tuning odorant receptor, the heteromeric complex also shows increased sensitivity to an odorant. Thus, the effect of the D466E mutation is not specific to VUAA1 agonism or dependent on homomeric Orco assembly. We suggest the gain-of-activation characteristic of the D466E mutant identifies an amino acid that is likely to be important for activation of both heteromeric and homomeric insect odorant receptor channels.

  12. The pharmacokinetics of [11C]methoxy-norchloroprogabidic acid, a potential PET tracer for GABA receptors in the brain

    We have described the kinetic properties of [11C]methoxy-norchloroprogabidic acid, a potential radioligand for the gamma-aminobutyric acid (GABA) receptor. Early metabolism in mice was negligible. Protein binding in human plasma was 89±7%. Distribution volumes were 89.6±29.4 l whereas the elimination half-life was 41.6±14.3 min. Animal and human positron emission tomography (PET) data demonstrate limited uptake of the activity in brain tissue. Displacement studies in mice suggest a nonsignificant fraction of specific receptor binding. [11C] Methoxy-norchloroprogabidic acid is therefore unsuitable for brain PET

  13. A novel hydroxyfuroic acid compound as an insulin receptor activator – structure and activity relationship of a prenylindole moiety to insulin receptor activation

    Tsai Henry J

    2009-07-01

    Full Text Available Abstract Background Diabetes Mellitus is a chronic disease and many patients of which require frequent subcutaneous insulin injection to maintain proper blood glucose levels. Due to the inconvenience of insulin administration, an orally active insulin replacement has long been a prime target for many pharmaceutical companies. Demethylasterriquinone (DMAQ B1, extracted from tropical fungus, Pseudomassaria sp., has been reported to be an orally effective agent at lowering circulating glucose levels in diabetic (db/db mice; however, the cytotoxicity associated with the quinone moiety has not been addressed thus far. Methods A series of hydroxyfuroic acid compounds were synthesized and tested for their efficacies at activating human insulin receptor. Cytotoxicity to Chinese hamster ovary cells, selectivities over insulin-like growth factor-1 (IGF-1, epidermal growth factor (EGF, and fibroblast growth factor (FGF receptors were examined in this study. Result and Conclusion This study reports a new non-quinone DMAQ B1 derivative, a hydroxyfuroic acid compound (D-410639, which is 128 fold less cytotoxic as DMAQ B1 and as potent as compound 2, a DMAQ B1 synthetic derivative from Merck, at activating human insulin receptor. D-410639 has little activation potential on IGF-1 receptor but is a moderate inhibitor to EGF receptor. Structure and activity relationship of the prenylindole moiety to insulin receptor activation is discussed.

  14. Retinoic Acid-Related Orphan Receptors (RORs: Regulatory Functions in Immunity, Development, Circadian Rhythm, and Metabolism

    Donald N. Cook

    2015-12-01

    Full Text Available In this overview, we provide an update on recent progress made in understanding the mechanisms of action, physiological functions, and roles in disease of retinoic acid related orphan receptors (RORs. We are particularly focusing on their roles in the regulation of adaptive and innate immunity, brain function, retinal development, cancer, glucose and lipid metabolism, circadian rhythm, metabolic and inflammatory diseases and neuropsychiatric disorders. We also summarize the current status of ROR agonists and inverse agonists, including their regulation of ROR activity and their therapeutic potential for management of various diseases in which RORs have been implicated.

  15. Chlorogenic Acid Improves Late Diabetes through Adiponectin Receptor Signaling Pathways in db/db Mice

    Shasha Jin; Cuiqing Chang; Lantao Zhang; Yang Liu; Xianren Huang; Zhimin Chen

    2015-01-01

    The aim of this study was to examine the effects of chlorogenic acid (CGA) on glucose and lipid metabolism in late diabetic db/db mice, as well as on adiponectin receptors and their signaling molecules, to provide evidence for CGA in the prevention of type 2 diabetes. We randomly divided 16 female db/db mice into db/db-CGA and db/db-control (CON) groups equally; db/m mice were used as control mice. The mice in both the db/db-CGA and db/m-CGA groups were administered 80 mg/kg/d CGA by lavage f...

  16. A honey bee odorant receptor for the queen substance 9-oxo-2-decenoic acid

    Kevin W Wanner; Nichols, Andrew S.; Walden, Kimberly K. O.; Brockmann, Axel; Luetje, Charles W.; Robertson, Hugh M

    2007-01-01

    By using a functional genomics approach, we have identified a honey bee [Apis mellifera (Am)] odorant receptor (Or) for the queen substance 9-oxo-2-decenoic acid (9-ODA). Honey bees live in large eusocial colonies in which a single queen is responsible for reproduction, several thousand sterile female worker bees complete a myriad of tasks to maintain the colony, and several hundred male drones exist only to mate. The “queen substance” [also termed the queen retinue pheromone (QRP)] is an eig...

  17. Phosphatase inhibitors remove the run-down of γ-aminobutyric acid type A receptors in the human epileptic brain

    Palma, E.; Ragozzino, D. A.; Di Angelantonio, S.; Spinelli, G.; Trettel, F.; Martinez-Torres, A.; Torchia, G.; Arcella, A.; Di Gennaro, G.; Quarato, P. P.; Esposito, V.; Cantore, G.; Miledi, R.; Eusebi, F.

    2004-01-01

    The properties of γ-aminobutyric acid (GABA) type A receptors (GABAA receptors) microtransplanted from the human epileptic brain to the plasma membrane of Xenopus oocytes were compared with those recorded directly from neurons, or glial cells, in human brains slices. Cell membranes isolated from brain specimens, surgically obtained from six patients afflicted with drug-resistant temporal lobe epilepsy (TLE) were injected into frog oocytes. Within a few hours, these oocytes acquired GABAA receptors that generated GABA currents with an unusual run-down, which was inhibited by orthovanadate and okadaic acid. In contrast, receptors derived from membranes of a nonepileptic hippocampal uncus, membranes from mouse brain, or recombinant rat α1β2γ2-GABA receptors exhibited a much less pronounced GABA-current run-down. Moreover, the GABAA receptors of pyramidal neurons in temporal neocortex slices from the same six epileptic patients exhibited a stronger run-down than the receptors of rat pyramidal neurons. Interestingly, the GABAA receptors of neighboring glial cells remained substantially stable after repetitive activation. Therefore, the excessive GABA-current run-down observed in the membrane-injected oocytes recapitulates essentially what occurs in neurons, rather than in glial cells. Quantitative RT-PCR analyses from the same TLE neocortex specimens revealed that GABAA-receptor β1, β2, β3, and γ2 subunit mRNAs were significantly overexpressed (8- to 33-fold) compared with control autopsy tissues. Our results suggest that an abnormal GABA-receptor subunit transcription in the TLE brain leads to the expression of run-down-enhanced GABAA receptors. Blockage of phosphatases stabilizes the TLE GABAA receptors and strengthens GABAergic inhibition. It may be that this process can be targeted to develop new treatments for intractable epilepsy. PMID:15218107

  18. Excitatory amino acid receptor ligands: resolution, absolute stereochemistry, and enantiopharmacology of 2-amino-3-(4-butyl-3-hydroxyisoxazol-5-yl)propionic acid

    Johansen, T N; Ebert, B; Bräuner-Osborne, Hans; Didriksen, M; Christensen, I T; Søby, K K; Madsen, U; Krogsgaard-Larsen, P; Brehm, L

    1998-01-01

    M) were equipotent as inhibitors of CaCl2-dependent [3H]-(S)-glutamic acid binding, neither enantiomer showed significant affinity for the synaptosomal (S)-glutamic acid uptake system(s). AMPA receptor affinity (IC50 = 0.48 microM) and agonism (EC50 = 17 microM) were shown to reside exclusively in the S......(RS)-2-Amino-3-(4-butyl-3-hydroxyisoxazol-5-yl)propionic acid (Bu-HIBO, 6) has previously been shown to be an agonist at (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors and an inhibitor of CaCl2-dependent [3H]-(S)-glutamic acid binding (J. Med. Chem. 1992, 35, 3512...... observations together indicate that the potentiation of the AMPA receptor agonism of 7 by 8 is not mediated by metabotropic (S)-glutamate receptors but rather by the CaCl2-dependent (S)-glutamic acid binding system, which shows the characteristics of a transport mechanism. After intravenous administration in...

  19. Activation of peroxisome proliferator-activated receptor-α enhances fatty acid oxidation in human adipocytes

    Highlights: → PPARα activation increased mRNA expression levels of adipocyte differentiation marker genes and GPDH activity in human adipocytes. → PPARα activation also increased insulin-dependent glucose uptake in human adipocytes. → PPARα activation did not affect lipid accumulation in human adipocytes. → PPARα activation increased fatty acid oxidation through induction of fatty acid oxidation-related genes in human adipocytes. -- Abstract: Peroxisome proliferator-activated receptor-α (PPARα) is a key regulator for maintaining whole-body energy balance. However, the physiological functions of PPARα in adipocytes have been unclarified. We examined the functions of PPARα using human multipotent adipose tissue-derived stem cells as a human adipocyte model. Activation of PPARα by GW7647, a potent PPARα agonist, increased the mRNA expression levels of adipocyte differentiation marker genes such as PPARγ, adipocyte-specific fatty acid-binding protein, and lipoprotein lipase and increased both GPDH activity and insulin-dependent glucose uptake level. The findings indicate that PPARα activation stimulates adipocyte differentiation. However, lipid accumulation was not changed, which is usually observed when PPARγ is activated. On the other hand, PPARα activation by GW7647 treatment induced the mRNA expression of fatty acid oxidation-related genes such as CPT-1B and AOX in a PPARα-dependent manner. Moreover, PPARα activation increased the production of CO2 and acid soluble metabolites, which are products of fatty acid oxidation, and increased oxygen consumption rate in human adipocytes. The data indicate that activation of PPARα stimulates both adipocyte differentiation and fatty acid oxidation in human adipocytes, suggesting that PPARα agonists could improve insulin resistance without lipid accumulation in adipocytes. The expected effects of PPARα activation are very valuable for managing diabetic conditions accompanied by obesity, because PPAR

  20. Enzymatic recycling of ascorbic acid from dehydroascorbic acid by glutathione-like peptides in the extracellular loops of aminergic G-protein coupled receptors.

    Root-Bernstein, Robert; Fewins, Jenna; Rhinesmith, Tyler; Koch, Ariana; Dillon, Patrick F

    2016-07-01

    The intracellular recycling of ascorbic acid from dehydroascorbic acid by the glutathione-glutathione reductase system has been well-characterized. We propose that extracellular recycling of ascorbic acid is performed in a similar manner by cysteine-rich, glutathione-like regions of the first and second extracellular loops of some aminergic receptors including adrenergic, histaminergic, and dopaminergic receptors. Previous research in our laboratory demonstrated that ascorbic acid binds to these receptors at a site on their first or second extracellular loops, significantly enhancing ligand activity, and apparently recycling hundreds of times their own concentration of ascorbate in an enzymatic fashion. In this study, we have synthesized 25 peptides from the first and second extracellular loops of aminergic and insulin receptors and compared them directly to glutathione for their ability to prevent the oxidation of ascorbate and to regenerate ascorbate from dehydroascorbic acid. Peptide sequences that mimic glutathione in containing a cysteine and a glutamic acid-like amino acid also mimic glutathione activity in effects and in kinetics. Some (but not all) peptide sequences that contain one or more methionines instead of cysteine can significantly retard the oxidation of ascorbic acid but do not recycle it from dehydroascorbate into ascorbate. Peptides lacking both cysteines and methionines uniformly failed to alter significantly ascorbate or dehydroascorbate oxidation or reduction. We believe that this is the first proof that receptors may carry out both ligand binding and enzymatic activity extracellularly. Our results suggest the existence of a previously unknown extracellular system for recycling ascorbate. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26749062

  1. Oncogenic conversion of a novel orphan nuclear receptor by chromosome translocation.

    Labelle, Y; Zucman, J; Stenman, G; Kindblom, L G; Knight, J; Turc-Carel, C; Dockhorn-Dworniczak, B; Mandahl, N; Desmaze, C; Peter, M

    1995-12-01

    A recurrent t(9;22) (q22;q12) chromosome translocation has been described in extraskeletal myxoid chondrosarcoma (EMC). Fluorescent in situ hybridization experiments performed on one EMC tumour indicated that the chromosome 22 breakpoint occurred in the EWS gene. Northern blot analysis revealed an aberrant EWS transcript which is cloned by a modified RT-PCR procedure. This transcript consists of an in-frame fusion of the 5' end of EWS to a previously unidentified gene, which was named TEC. This fusion transcript was detected in six of eight EMC studied, and three different junction types between the two genes were found. In all junction types, the putative translation product contained the amino-terminal transactivation domain of EWS linked to the entire TEC protein. Homology analysis showed that the predicted TEC protein contains a DNA-binding domain characteristic of nuclear receptors. The highest identity scores were observed with the NURR1 family of orphan nuclear receptors. These receptors are involved in the control of cell proliferation and differentiation by modulating the response to growth factors and retinoic acid. This work provides, after the PML/RAR alpha gene fusion, the second example of the oncogenic conversion of a nuclear receptor and the first example involving the orphan subfamily. Analysis of the disturbance induced by the EWS/TEc protein in the nuclear receptor network and their target genes may lead to new approaches for EMC treatment. PMID:8634690

  2. Functional Characterization of the Semisynthetic Bile Acid Derivative INT-767, a Dual Farnesoid X Receptor and TGR5 AgonistS⃞

    Rizzo, Giovanni; Passeri, Daniela; Franco, Francesca; Ciaccioli, Gianmario; Donadio, Loredana; Rizzo, Giorgia; Orlandi, Stefano; Sadeghpour, Bahman; Wang, Xiaoxin X.; Jiang, Tao; Levi, Moshe; Pruzanski, Mark; Adorini, Luciano

    2010-01-01

    Two dedicated receptors for bile acids (BAs) have been identified, the nuclear hormone receptor farnesoid X receptor (FXR) and the G protein-coupled receptor TGR5, which represent attractive targets for the treatment of metabolic and chronic liver diseases. Previous work characterized 6α-ethyl-3α,7α-dihydroxy-5β-cholan-24-oic acid (INT-747), a potent and selective FXR agonist, as well as ...

  3. The Arabidopsis NPR1 Protein Is a Receptor for the Plant Defense Hormone Salicylic Acid

    Yue Wu

    2012-06-01

    Full Text Available Salicylic acid (SA is an essential hormone in plant immunity, but its receptor has remained elusive for decades. The transcriptional coregulator NPR1 is central to the activation of SA-dependent defense genes, and we previously found that Cys521 and Cys529 of Arabidopsis NPR1's transactivation domain are critical for coactivator function. Here, we demonstrate that NPR1 directly binds SA, but not inactive structural analogs, with an affinity similar to that of other hormone-receptor interactions and consistent with in vivo Arabidopsis SA concentrations. Binding of SA occurs through Cys521/529 via the transition metal copper. Mechanistically, our results suggest that binding of SA causes a conformational change in NPR1 that is accompanied by the release of the C-terminal transactivation domain from the N-terminal autoinhibitory BTB/POZ domain. While NPR1 is already known as a link between the SA signaling molecule and defense-gene activation, we now show that NPR1 is the receptor for SA.

  4. Effects of bile acids and the bile acid receptor FXR agonist on the respiratory rhythm in the in vitro brainstem medulla slice of neonatal Sprague-Dawley rats.

    Cong Zhao

    Full Text Available Intrahepatic cholestasis of pregnancy is always accompanied by adverse fetal outcomes such as malfunctions of respiration. Farnesoid X receptor (FXR plays a critical role in the homeostasis of bile acids. Thus, we are determined to explore the effects of farnesoid X receptor (FXR and five bile acids on respiratory rhythm generation and modulation of neonatal rats. Spontaneous periodic respiratory-related rhythmical discharge activity (RRDA was recorded from hypoglossal nerves during the perfusion of modified Krebs solution. Group 1-6 was each given GW4064 and five bile acids of chenodeoxycholic acid (CDCA, deoxycholic acid (DCA, lithocholic acid (LCA, cholic acid (CA as well as ursodeoxycholic acid (UDCA at different concentrations to identify their specific functions on respiratory rhythm modulations. Group 7 was applied to receive FXR blocker Z-guggulsterone and Z-guggulsterone with the above bile acids separately to explore the role of FXR in the respiratory rhythm modulation. Group 8 was given dimethyl sulfoxide (DMSO as controls. Apart from UDCA, CDCA, DCA LCA and CA all exerted effects on RRDA recorded from hypoglossal nerves in a concentration-dependent manner. Respiratory cycle (RC, Inspiratory time (TI, Expiratory Time (TE and Integral Amplitude (IA were influenced and such effects could be reversed by Z-guggulsterone. FXR may contribute to the effects on the modulation of respiratory rhythm exerted by bile acids.

  5. Imaging oncogene expression in breast cancer with receptor specific peptides and peptide nucleic acids

    Full text: This year, breast cancer (BC) will attack approximately 210, 000 and will take the lives of 40,000 women in the U.S. Standard screening with breast self-examination and mammography, recommended to minimize BC morbidity, miss 10-20% (up to 40% in young women) of breast cancer. Moreover, if an abnormality is found, an invasive diagnostic procedure is required to determine if the breast contains hyperplasia, atypia, or cancer. Approximately 80% of invasive procedures detect a benign pathology. BC cells express a gene product, cell surface receptor VPAC1, so named because the endogenous growth hormones Vasoctive Intestinal Peptide (VIP) and Pituitary Adenylate Cylcase Activating Peptide (PACAP) bind to VPAC1 receptors with high affinity. VPAC1 receptors are overexpressed on 100% of human breast cancer cells. Cyclin D1 is a key regulator of the cell cycle and overexpressed in 50% to 80% of breast cells, whereas it is low or absent in normal breast tissues. The human breast cancer cell line MCF7 displays elevated levels of CCND1 mRNA, encoding cyclin D1, and an elevated level of IGF1R mRNA, encoding insulin-like growth factor 1 receptor. We hypothesed that 99mTc or 64Cu labeled VIP analogues, or a peptide nucleic acid (PNA) chimera specific for IGFI receptor and CCND1 mRNA, will permit us to early image breast cancer by planar, SPECT or PET imaging. We synthesized, characterized and administered i.v. 99mTc-AcGly-D (Ala)-Gly-Glyaminobutanoyl- VIP (TP3654), 64Cu diaminodithiol-aminobutanoyl-VIP (TP3982), 99mTc- AcGly-D(Ala)-Gly-Gly-PNA-D(Cys-ser-lys-Cys) chimera (WT4185) and Cu-64-DOTAPNA- D(cys-ser-lys-cys) (WT4348). A 12mer, CTGGTGTTCCAT nucleic acid sequence served as the PNA and 3 or 4 mer mismatched PNAs as negative controls. Using 99mTc-TP3654 we have successfully imaged human breast cancers not detectable by current modalities. In athymic, nude mice bearing MCF-7 human breast cancer xenographs, Cu-64-TP3982 tumour uptake was 85 times greater than 99m

  6. Effect of short chain fatty acids on the expression of free fatty acid receptor 2 (Ffar2), Ffar3 and early-stage adipogenesis

    Frost, G; Cai, Z.; Raven, M; Otway, DT; Mushtaq, R; Johnston, JD

    2014-01-01

    Adipose tissue has a major influence on insulin sensitivity. Stimulation of free fatty acid receptor 2 (FFAR2) has been proposed to influence adipocyte differentiation. We hypothesised that exposing preadipocytes to short chain fatty acids would induce earlier expression of nuclear receptors that co-ordinate adipogenesis, triglyceride accumulation and leptin secretion. 3T3-L1 preadipocytes were differentiated in the presence of 1 μM acetate, 0.1–10 μM propionate or vehicle control. In experim...

  7. The nuclear bile acid receptor FXR controls the liver derived tumor suppressor histidine-rich glycoprotein.

    Deuschle, Ulrich; Birkel, Manfred; Hambruch, Eva; Hornberger, Martin; Kinzel, Olaf; Perović-Ottstadt, Sanja; Schulz, Andreas; Hahn, Ulrike; Burnet, Michael; Kremoser, Claus

    2015-06-01

    The nuclear bile acid receptor Farnesoid X receptor (FXR) is strongly expressed in liver and intestine, controls bile acid and lipid homeostasis and exerts tumor-protective functions in liver and intestine. Histidine-rich glycoprotein (HRG) is an abundant plasma protein produced by the liver with the proposed function as a pattern recognition molecule involved in the clearance of immune complexes, necrotic cells and pathogens, the modulation of angiogenesis, the normalization of deranged endothelial vessel structure in tumors and tumor suppression. FXR recognition sequences were identified within a human HRG promoter fragment that mediated FXR/FXR-agonist dependent reporter gene activity in vitro. We show that HRG is a novel transcriptional target gene of FXR in human hepatoma cells, human upcyte® primary hepatocytes and 3D human liver microtissues in vitro and in mouse liver in vivo. Prolonged administration of the potent nonsteroidal FXR agonist PX20606 increases HRG levels in mouse plasma. Finally, daily oral administration of this FXR agonist for seven days resulted in a significant increase of HRG levels in the plasma of healthy human male volunteers during a clinical Phase I safety study. HRG might serve as a surrogate marker indicative of liver-specific FXR activation in future human clinical studies. Furthermore, potent FXR agonists might be beneficial in serious health conditions where HRG is reduced, for example, in hepatocellular carcinoma but also other solid cancers, liver failure, sepsis and pre-eclampsia. PMID:25363753

  8. Interactions between Human Liver Fatty Acid Binding Protein and Peroxisome Proliferator Activated Receptor Selective Drugs

    Tony Velkov

    2013-01-01

    Full Text Available Fatty acid binding proteins (FABPs act as intracellular shuttles for fatty acids as well as lipophilic xenobiotics to the nucleus, where these ligands are released to a group of nuclear receptors called the peroxisome proliferator activated receptors (PPARs. PPAR mediated gene activation is ultimately involved in maintenance of cellular homeostasis through the transcriptional regulation of metabolic enzymes and transporters that target the activating ligand. Here we show that liver- (L- FABP displays a high binding affinity for PPAR subtype selective drugs. NMR chemical shift perturbation mapping and proteolytic protection experiments show that the binding of the PPAR subtype selective drugs produces conformational changes that stabilize the portal region of L-FABP. NMR chemical shift perturbation studies also revealed that L-FABP can form a complex with the PPAR ligand binding domain (LBD of PPARα. This protein-protein interaction may represent a mechanism for facilitating the activation of PPAR transcriptional activity via the direct channeling of ligands between the binding pocket of L-FABP and the PPARαLBD. The role of L-FABP in the delivery of ligands directly to PPARα via this channeling mechanism has important implications for regulatory pathways that mediate xenobiotic responses and host protection in tissues such as the small intestine and the liver where L-FABP is highly expressed.

  9. Mutations of lysophosphatidic acid receptor-1 gene during progression of lung tumors in rats

    Lysophosphatidic acid (LPA) is a bioactive phospholipid that stimulates cell proliferation, migration, and protects cells from apoptosis. It interacts with specific G protein-coupled transmembrane receptors. In this study, mutations of lysophosphatidic acid receptor-1 (LPA1) gene were investigated to clarify the possible molecular mechanisms underlying the development of lung tumors induced by N-nitrosobis(2-hydroxypropyl)amine (BHP) in rats. Male Wistar rats, 6 weeks of age, were given 2000 ppm BHP in their drinking water for 12 weeks and then maintained without further treatment until sacrifice at 25 weeks. Genomic DNAs were extracted from paraffin-embedded tissues and exons 2-4 were examined for mutations, using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis. No LPA1 mutations were detected in 15 hyperplasias, but 2 out of 12 adenomas (16.7%) and 7 out of 17 adenocarcinomas (41.2%). These results suggest that mutations of LPA1 gene may be involved in the acquisition of growth advantage from adenomas to adenocarcinomas in lung carcinogenesis induced in rats by BHP.

  10. Acidic Tumor Microenvironment and pH-Sensing G protein-Coupled Receptors

    Calvin R. Justus

    2013-12-01

    Full Text Available The tumor microenvironment is acidic due to glycolytic cancer cell metabolism, hypoxia, and deficient blood perfusion. It is proposed that acidosis in the tumor microenvironment is an important stress factor and selection force for cancer cell somatic evolution. Acidic pH has pleiotropic effects on the proliferation, migration, invasion, metastasis and therapeutic response of cancer cells and the function of immune cells, vascular cells, and other stromal cells. However, the molecular mechanisms by which cancer cells and stromal cells sense and respond to acidic pH in the tumor microenvironment are poorly understood. In this article the role of a family of pH-sensing G protein-coupled receptors (GPCRs in tumor biology is reviewed. Recent studies show that the pH-sensing GPCRs, including GPR4, GPR65 (TDAG8, GPR68 (OGR1, and GPR132 (G2A, regulate cancer cell metastasis and proliferation, immune cell function, inflammation, and blood vessel formation. Activation of the proton-sensing GPCRs by acidosis transduces multiple downstream G protein signaling pathways. Since GPCRs are major drug targets, small molecule modulators of the pH-sensing GPCRs are being actively developed and evaluated. Research on the pH-sensing GPCRs will continue to provide important insights into the molecular interaction between tumor and its acidic microenvironment and may identify new targets for cancer therapy and chemoprevention.

  11. Acidic tumor microenvironment and pH-sensing G protein-coupled receptors.

    Justus, Calvin R; Dong, Lixue; Yang, Li V

    2013-01-01

    The tumor microenvironment is acidic due to glycolytic cancer cell metabolism, hypoxia, and deficient blood perfusion. It is proposed that acidosis in the tumor microenvironment is an important stress factor and selection force for cancer cell somatic evolution. Acidic pH has pleiotropic effects on the proliferation, migration, invasion, metastasis, and therapeutic response of cancer cells and the function of immune cells, vascular cells, and other stromal cells. However, the molecular mechanisms by which cancer cells and stromal cells sense and respond to acidic pH in the tumor microenvironment are poorly understood. In this article the role of a family of pH-sensing G protein-coupled receptors (GPCRs) in tumor biology is reviewed. Recent studies show that the pH-sensing GPCRs, including GPR4, GPR65 (TDAG8), GPR68 (OGR1), and GPR132 (G2A), regulate cancer cell metastasis and proliferation, immune cell function, inflammation, and blood vessel formation. Activation of the proton-sensing GPCRs by acidosis transduces multiple downstream G protein signaling pathways. Since GPCRs are major drug targets, small molecule modulators of the pH-sensing GPCRs are being actively developed and evaluated. Research on the pH-sensing GPCRs will continue to provide important insights into the molecular interaction between tumor and its acidic microenvironment and may identify new targets for cancer therapy and chemoprevention. PMID:24367336

  12. Retinoic acid receptor beta2 and neurite outgrowth in the adult mouse spinal cord in vitro.

    Corcoran, Jonathan; So, Po-Lin; Barber, Robert D; Vincent, Karen J; Mazarakis, Nicholas D; Mitrophanous, Kyriacos A; Kingsman, Susan M; Maden, Malcolm

    2002-10-01

    Retinoic acid, acting through the nuclear retinoic acid receptor beta2 (RARbeta2), stimulates neurite outgrowth from peripheral nervous system tissue that has the capacity to regenerate neurites, namely, embryonic and adult dorsal root ganglia. Similarly, in central nervous system tissue that can regenerate, namely, embryonic mouse spinal cord, retinoic acid also stimulates neurite outgrowth and RARbeta2 is upregulated. By contrast, in the adult mouse spinal cord, which cannot regenerate, no such upregulation of RARbeta2 by retinoic acid is observed and no neurites are extended in vitro. To test our hypothesis that the upregulation of RARbeta2 is crucial to neurite regeneration, we have transduced adult mouse or rat spinal cord in vitro with a minimal equine infectious anaemia virus vector expressing RARbeta2. After transduction, prolific neurite outgrowth occurs. Outgrowth does not occur when the cord is transduced with a different isoform of RARbeta nor does it occur following treatment with nerve growth factor. These data demonstrate that RARbeta2 is involved in neurite outgrowth, at least in vitro, and that this gene may in the future be of some therapeutic use. PMID:12235288

  13. NR4A orphan nuclear receptors influence retinoic acid and docosahexaenoic acid signaling via up-regulation of fatty acid binding protein 5

    Volakakis, Nikolaos; Joodmardi, Eliza [Ludwig Institute for Cancer Research Ltd., Box 240, S-17177 Stockholm (Sweden); Perlmann, Thomas, E-mail: thomas.perlmann@licr.ki.se [Ludwig Institute for Cancer Research Ltd., Box 240, S-17177 Stockholm (Sweden); The Department of Cell and Molecular Biology, Karolinska Institute, S-17177 Stockholm (Sweden)

    2009-12-25

    The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system and is also induced as an immediate early gene in a variety of cell types. In silico analysis of human promoters identified fatty acid binding protein 5 (FABP5), a protein shown to enhance retinoic acid-mediated PPAR{beta}/{delta} signaling, as a potential Nurr1 target gene. Nurr1 has previously been implicated in retinoid signaling via its heterodimerization partner RXR. Since NRs are commonly involved in cross-regulatory control we decided to further investigate the regulatory relationship between Nurr1 and FABP5. FABP5 expression was up-regulated by Nurr1 and other NR4A NRs in HEK293 cells, and Nurr1 was shown to activate and bind to the FABP5 promoter, supporting that FABP5 is a direct downstream target of NR4A NRs. We also show that the RXR ligand docosahexaenoic acid (DHA) can induce nuclear translocation of FABP5. Moreover, via up-regulation of FABP5 Nurr1 can enhance retinoic acid-induced signaling of PPAR{beta}/{delta} and DHA-induced activation of RXR. We also found that other members of the NR4A orphan NRs can up-regulate FABP5. Thus, our findings suggest that NR4A orphan NRs can influence signaling events of other NRs via control of FABP5 expression levels.

  14. Intramolecular allosteric communication in dopamine D2 receptor revealed by evolutionary amino acid covariation.

    Sung, Yun-Min; Wilkins, Angela D; Rodriguez, Gustavo J; Wensel, Theodore G; Lichtarge, Olivier

    2016-03-29

    The structural basis of allosteric signaling in G protein-coupled receptors (GPCRs) is important in guiding design of therapeutics and understanding phenotypic consequences of genetic variation. The Evolutionary Trace (ET) algorithm previously proved effective in redesigning receptors to mimic the ligand specificities of functionally distinct homologs. We now expand ET to consider mutual information, with validation in GPCR structure and dopamine D2 receptor (D2R) function. The new algorithm, called ET-MIp, identifies evolutionarily relevant patterns of amino acid covariations. The improved predictions of structural proximity and D2R mutagenesis demonstrate that ET-MIp predicts functional interactions between residue pairs, particularly potency and efficacy of activation by dopamine. Remarkably, although most of the residue pairs chosen for mutagenesis are neither in the binding pocket nor in contact with each other, many exhibited functional interactions, implying at-a-distance coupling. The functional interaction between the coupled pairs correlated best with the evolutionary coupling potential derived from dopamine receptor sequences rather than with broader sets of GPCR sequences. These data suggest that the allosteric communication responsible for dopamine responses is resolved by ET-MIp and best discerned within a short evolutionary distance. Most double mutants restored dopamine response to wild-type levels, also suggesting that tight regulation of the response to dopamine drove the coevolution and intramolecular communications between coupled residues. Our approach provides a general tool to identify evolutionary covariation patterns in small sets of close sequence homologs and to translate them into functional linkages between residues. PMID:26979958

  15. N-Methyl D-Aspartic Acid (NMDA Receptors and Depression

    Enver Yusuf Sivrioglu

    2009-06-01

    Full Text Available The monoaminergic hypothesis of depression has provided the basis for extensive research into the pathophysiology of mood disorders and has been of great significance for the development of effective antidepressants. Current antidepressant treatments not only increase serotonin and/or noradrenaline bioavailability but also originate adaptive changes increasing synaptic plasticity. Novel approaches to depression and to antidepressant therapy are now focused on intracellular targets that regulate neuroplasticity and cell survival. Accumulating evidence indicates that there is an anatomical substrate for such a devastating neuropsychiatric disease as major depression. Loss of synaptic plasticity and hippocampal atrophy appear to be prominent features of this highly prevalent disorder. A combination of genetic susceptibility and environmental factors make hippocampal neurons more vulnerable to stress. Abundant experimental evidence indicates that stress causes neuronal damage in brain regions, notably in hippocampal subfields. Stress-induced activation of glutamatergic transmission may induce neuronal cell death through excessive stimulation of N-methyl-D-aspartic acid (NMDA receptors. Recent studies mention that the increase of nitric oxide synthesis and inflammation in major depression may contribute to neurotoxicity through NMDA receptor. Both standard antidepressants and NMDA receptor antagonists are able to prevent stress-induced neuronal damage. NMDA antagonists are effective in widely used animal models of depression and some of them appear to be effective also in the few clinical trials performed to date. We are still far from understanding the complex cellular and molecular events involved in mood disorders. There appears to be an emerging role for glutamate neurotransmission in the search for the pathogenesis of major depression. Attenuation of NMDA receptor function mechanism appears to be a promising target in the search for a more

  16. Fenretinide-induced apoptosis of Huh-7 hepatocellular carcinoma is retinoic acid receptor β dependent

    Wan Yu-Jui

    2007-12-01

    Full Text Available Abstract Background Retinoids are used to treat several types of cancer; however, their effects on liver cancer have not been fully characterized. To investigate the therapeutic potential of retinoids on hepatocellular carcinoma (HCC, the present study evaluates the apoptotic effect of a panel of natural and synthetic retinoids in three human HCC cell lines as well as explores the underlying mechanisms. Methods Apoptosis was determined by caspase-3 cleavage using western blot, DNA double-strand breaks using TUNEL assay, and phosphatidylserine translocation using flow cytometry analysis. Gene expression of nuclear receptors was assessed by real-time PCR. Transactivation assay and chromatin immunoprecipitation (ChIP were conducted to evaluate the activation of RXRα/RARβ pathway by fenretinide. Knockdown of RARβ mRNA expression was achieved by siRNA transfection. Results Our data revealed that fenretinide effectively induces apoptosis in Huh-7 and Hep3B cells. Gene expression analysis of nuclear receptors revealed that the basal and inducibility of retinoic acid receptor β (RARβ expression positively correlate with the susceptibility of HCC cells to fenretinide treatment. Furthermore, fenretinide transactivates the RXRα/RARβ-mediated pathway and directly increases the transcriptional activity of RARβ. Knockdown of RARβ mRNA expression significantly impairs fenretinide-induced apoptosis in Huh-7 cells. Conclusion Our findings reveal that endogenous expression of retinoids receptor RARβ gene determines the susceptibility of HCC cells to fenretinide-induced apoptosis. Our results also demonstrate fenretinide directly activates RARβ and induces apoptosis in Huh-7 cells in a RARβ-dependent manner. These findings suggest a novel role of RARβ as a tumor suppressor by mediating the signals of certain chemotherapeutic agents.

  17. Danza de matachines. Estructura y función entre los rarámuri de la sierra Taraumara

    Ángel Acuña Delgado

    2008-01-01

    Full Text Available Introducida por los misioneros en tiempo de conquista, la danza de matachines posee actualmente mucha vigencia dentro del pueblo Rarámuri, habitante de la Sierra Tarahumara, situada al suroeste del estado Chihuahua en México. Desde su llegada a la región a principios del siglo XVII y hasta el momento presente, ésta modalidad dancística ha experimentado numerosos cambios en sus formas y sus sentidos, pudiéndose apreciar gran diversidad en su desarrollo dentro de las propias comunidades rarámuri. En este ensayo centraremos la atención en el contexto festivo donde los matachines tienen lugar, así como en la estructura y funciones generales que esta danza desempeña en el pueblo que la pone en escena. Todo lo cual nos llevará finalmente a reflexionar sobre los préstamos culturales y la tradición reinventada en la búsqueda de sentidos.

  18. Activation of transmembrane bile acid receptor TGR5 stimulates insulin secretion in pancreatic {beta} cells

    Kumar, Divya P.; Rajagopal, Senthilkumar; Mahavadi, Sunila [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Mirshahi, Faridoddin [Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Grider, John R. [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Murthy, Karnam S., E-mail: skarnam@vcu.edu [Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA (United States); Sanyal, Arun J., E-mail: asanyal@mcvh-vcu.edu [Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA (United States)

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer G protein coupled receptor TGR5 is expressed in mouse and human islets. Black-Right-Pointing-Pointer TGR5 is coupled to activation of Gs and Ca{sup 2+} release via cAMP/Epac/PLC-{epsilon} pathway. Black-Right-Pointing-Pointer Activation of TGR5 by bile salts and selective ligands causes insulin secretion. Black-Right-Pointing-Pointer TGR5 could be a potential therapeutic target to treat diabetes. -- Abstract: Bile acids act as signaling molecules and stimulate the G protein coupled receptor, TGR5, in addition to nuclear farnesoid X receptor to regulate lipid, glucose and energy metabolism. Bile acid induced activation of TGR5 in the enteroendocrine cells promotes glucagon like peptide-1 (GLP-1) release, which has insulinotropic effect in the pancreatic {beta} cells. In the present study, we have identified the expression of TGR5 in pancreatic {beta} cell line MIN6 and also in mouse and human pancreatic islets. TGR5 selective ligands, oleanolic acid (OA) and INT-777 selectively activated G{alpha}{sub s} and caused an increase in intracellular cAMP and Ca{sup 2+}. OA and INT-777 also increased phosphoinositide (PI) hydrolysis and the increase was blocked by NF449 (a selective G{alpha}{sub s} inhibitor) or (U73122) (PI hydrolysis inhibitor). OA, INT-777 and lithocholic acid increased insulin release in MIN6 and human islets and the increase was inhibited by treatment with NF449, (U73122) or BAPTA-AM (chelator of calcium), but not with myristoylated PKI (PKA inhibitor), suggesting that the release is dependent on G{sub s}/cAMP/Ca{sup 2+} pathway. 8-pCPT-2 Prime -O-Me-cAMP, a cAMP analog, which activates Epac, but not PKA also stimulated PI hydrolysis. In conclusion, our study demonstrates that the TGR5 expressed in the pancreatic {beta} cells regulates insulin secretion and highlights the importance of ongoing therapeutic strategies targeting TGR5 in the control of glucose homeostasis.

  19. Regulation of progesterone receptor messenger ribonucleic acid and protein levels in MCF-7 cells by estradiol: analysis of estrogen's effect on progesterone receptor synthesis and degradation

    The human breast cancer cell line MCF-7 responds to estrogens with increased progesterone receptor (PR) levels. In this study, we use dense amino acid density shift analyses to address directly the question of whether estrogen increases PR levels in MCF-7 cells by altering rates of receptor synthesis and/or degradation. Using different concentrations of estradiol (E2), which achieve PR levels that are half-maximal (3 X 10(-11) M F2) or maximal (6 X 10(-11) M E2), we have done sucrose gradient density shift analyses using dense (15N, 13C, 2H) amino acid incorporation to study rates of PR synthesis and degradation. These studies reveal a nonlinear loss of preexisting normal density receptor with time. From kinetic modeling analyses, equivalent rates of degradation are estimated for PR whether maximal or half-maximal levels are maintained, indicating that the major effect of E2 on PR content is to increase the rate of PR synthesis while leaving the degradation rate unaltered. The E2-stimulated increase in PR protein is also associated with increased levels of PR mRNA, as demonstrated by the use of a human PR cDNA probe. These density shift data provide evidence that the increased PR levels after estrogen exposure in MCF-7 cells are the result of an increased rate of receptor synthesis, rather than modulation of the rate of receptor degradation

  20. Negative regulation of gamma-aminobutyric acid type A receptor on free calcium ion levels following facial nerve injury

    Fugao Zhu; Dawei Sun; Yanqing Wang; Rui Zhou; Junfeng Wen; Xiuming Wan; Yanjun Wang; Banghua Liu

    2010-01-01

    Previous studies have demonstrated that muscarinic, and nicotinic receptors increase free Ca2+ levels in the facial nerve nucleus via various channels following facial nerve injury. However, intracellular Ca2+ overload can trigger either necrotic or apoptotic cell death. Gamma-aminobutyric acid (GABA), an important inhibitory neurotransmitter in the central nervous system, exists in the facial nerve nucleus. It is assumed that GABA negatively regulates free Ca2+ levels in the facial nerve nucleus. The present study investigated GABA type A (GABAA) receptor expression in the facial nerve nucleus in a rat model of facial nerve injury using immunohistochemistry and laser confocal microscopy, as well as the regulatory effects of GABAA receptor on nicotinic receptor response following facial nerve injury. Subunits α1, α3, α5, β1, β2, δ, and γ3 of GABAA receptors were expressed in the facial nerve nucleus following facial nerve injury. In addition, GABAA receptor expression significantly inhibited the increase in nicotinic receptor-mediated free Ca2+ levels in the facial nerve nucleus following facial nerve injury in a concentration-dependent fashion. These results suggest that GABAA receptors exhibit negative effects on nicotinic receptor responses following facial nerve injury.

  1. Glucuronic acid and the ethanol metabolite ethyl-glucuronide cause Toll-like receptor 4 activation and enhanced pain

    Lewis, Susannah S.; Hutchinson, Mark R; Zhang, Yingning; Hund, Dana K.; Maier, Steven F.; Rice, Kenner C.; Watkins, Linda R

    2013-01-01

    We have previously observed that the non-opioid morphine metabolite, morphine-3-glucuronide, enhances pain via a toll-like receptor 4 (TLR4) dependent mechanism. The present studies were undertaken to determine whether TLR4-dependent pain enhancement generalizes to other classes of glucuronide metabolites. In silico modeling predicted that glucuronic acid alone and ethyl glucuronide, a minor but long-lasting ethanol metabolite, would dock to the same MD-2 portion of the TLR4 receptor complex ...

  2. The Role of Fatty Acids on Toll-like Receptor 4 Regulation of Substrate Metabolism with Obesity

    McMillan, Ryan P

    2009-01-01

    Growing evidence suggests that obesity and associated metabolic dysregulation occurs in concert with chronic low-grade inflammation. Toll-like receptors (TLR) are transmembrane receptors that play an important role in innate immunity and the induction of inflammatory responses. Our laboratory has observed that TLR4 expression is elevated in the skeletal muscle of obese humans and is associated with reduced fatty acid (FA) oxidation and increased lipid synthesis. Additionally, activation of th...

  3. Reevaluation of Fatty Acid Receptor 1 as a Drug Target for the Stimulation of Insulin Secretion in Humans

    Wagner, Robert; Kaiser, Gabriele; Gerst, Felicia; Christiansen, Elisabeth; Due-Hansen, Maria E.; Grundmann, Manuel; Machicao, Fausto; Peter, Andreas; Kostenis, Evi; Ulven, Trond; Fritsche, Andreas; Häring, Hans-Ulrich; Ullrich, Susanne

    2013-01-01

    The role of free fatty acid receptor 1 (FFAR1/GPR40) in glucose homeostasis is still incompletely understood. Small receptor agonists stimulating insulin secretion are undergoing investigation for the treatment of type 2 diabetes. Surprisingly, genome-wide association studies did not discover diabetes risk variants in FFAR1. We reevaluated the role of FFAR1 in insulin secretion using a specific agonist, FFAR1-knockout mice and human islets. Nondiabetic individuals were metabolically phenotype...

  4. Synaptic and extrasynaptic γ-aminobutyric acid type A receptor clusters in rat hippocampal cultures during development

    Scotti, Alessandra L.; Reuter, Harald

    2001-01-01

    We have simultaneously measured the expression of postsynaptic γ-aminobutyric acid type A (GABAA) receptor clusters and of presynaptic boutons in neonatal rat hippocampal cultures between days 1 and 30. GABAA receptors were labeled with antibodies recognizing the extracellular domains of β2/3 and γ2 subunits. Boutons were visualized by activity-dependent uptake of the styryl dye FM4-64, or by antibodies against the presynaptic vesicular protein SV2 or the GABA-synt...

  5. Fatty acid amide hydrolase (FAAH) inhibition enhances memory acquisition through activation of PPAR-α nuclear receptors

    Mazzola, Carmen; Medalie, Julie; Scherma, Maria; Panlilio, Leigh V; Solinas, Marcello; Tanda, Gianluigi; Drago, Filippo; Cadet, Jean Lud; Goldberg, Steven R.; Yasar, Sevil

    2009-01-01

    Inhibitors of fatty acid amide hydrolase (FAAH) increase endogenous levels of anandamide (a cannabinoid CB1-receptor ligand) and oleoylethanolamide and palmitoylethanolamide (OEA and PEA, ligands for α-type peroxisome proliferator-activated nuclear receptors, PPAR-α) when and where they are naturally released in the brain. Using a passive-avoidance task in rats, we found that memory acquisition was enhanced by the FAAH inhibitor URB597 or by the PPAR-α agonist WY14643, and these enhancements ...

  6. Promoter hypermethylation profile of ER-α, RAR-β, MGMT and P16INK4a genes in oral squamous cell carcinoma%OSCC中ER-α、RAR-β、MGMT及P16INK4a基因启动子甲基化的临床研究

    薛万林; 刘春利

    2012-01-01

    Objective: To explore the status of promoter hypermethylation of several genes in oral squamous cell carcinoma (OSCC). Method: In this study, the hypermethylation profile in the promoter region of P16INK4a,RAR-β. MGMT and ER-α genes was investigated in twenty male patients with primary OSCC and two OSCC cell lines. Result: The incidence of hypermethylation in patients was 10 % (2 of 20) for pl6INK4a, 10 % (2 of 20) for MGMT,40 % (8 of 20) for RAR-p and 55 % (11 of 20) for ER-αgene respectively. Aberrant promoter hypermethylation was found for RAR-β and ER-α genes,but not for P16INK4a and MGMT genes in both GNM and TSCCa cell lines. Conclusion: Our results indicate that epigenetic alteration of RAR-β and ER-α genes in OSCC is a more frequent event than P16INK4a and MGMT genes, suggesting the critical importance of promoter hypermethylation at RAR-β and ER-α genes.%目的:探讨肿瘤相关基因ER-α、RAR-β、MGMT及P16INK4a启动子在口腔鳞状细胞癌(OSCC)组织中的甲基化状态.方法:20例病理确诊为OSCC的组织切片,经酶消化法提取组织DNA后双硫法检测ER-α、RAR-β、MGMT及P16INK4a基因启动子的甲基化状态,比较分析4种基因启动子甲基化状态和临床病理参数的相关性.结果:20例中,P16INK4a、MGMT启动子甲基化发生率均为10%,RAR-β启动子甲基化发生率为40%,ER-α启动子甲基化发生率为55%,两株OSCC细胞系中,ER-α、RAR-β启动子均出现甲基化,而MGMT及P16INK4a启动子均未见甲基化.结论:RAR-β、ER-α基因启动子的甲基化较P16INK4a、MGMTg更为常见,提示前两者可能在OSCC的发生中具有更重要的作用.

  7. Constitutive Androstane Receptor-Mediated Changes in Bile Acid Composition Contributes to Hepatoprotection from Lithocholic Acid-Induced Liver Injury in MiceS⃞

    Beilke, Lisa D.; Aleksunes, Lauren M.; Holland, Ricky D; Besselsen, David G; Beger, Rick D.; Klaassen, Curtis D.; Cherrington, Nathan J.

    2009-01-01

    Pharmacological activation of the constitutive androstane receptor (CAR) protects the liver during cholestasis. The current study evaluates how activation of CAR influences genes involved in bile acid biosynthesis as a mechanism of hepatoprotection during bile acid-induced liver injury. CAR activators phenobarbital (PB) and 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) or corn oil (CO) were administered to C57BL/6 wild-type (WT) and CAR knockout (CAR-null) mice ...

  8. Metabotropic glutamate receptors are involved in the detection of IMP and L-amino acids by mouse taste sensory cells.

    Pal Choudhuri, S; Delay, R J; Delay, E R

    2016-03-01

    G-protein-coupled receptors are thought to be involved in the detection of umami and L-amino acid taste. These include the heterodimer taste receptor type 1 member 1 (T1r1)+taste receptor type 1 member 3 (T1r3), taste and brain variants of mGluR4 and mGluR1, and calcium sensors. While several studies suggest T1r1+T1r3 is a broadly tuned lLamino acid receptor, little is known about the function of metabotropic glutamate receptors (mGluRs) in L-amino acid taste transduction. Calcium imaging of isolated taste sensory cells (TSCs) of T1r3-GFP and T1r3 knock-out (T1r3 KO) mice was performed using the ratiometric dye Fura 2 AM to investigate the role of different mGluRs in detecting various L-amino acids and inosine 5' monophosphate (IMP). Using agonists selective for various mGluRs such as (RS)-3,5-dihydroxyphenylglycine (DHPG) (an mGluR1 agonist) and L-(+)-2-amino-4-phosphonobutyric acid (l-AP4) (an mGluR4 agonist), we evaluated TSCs to determine if they might respond to these agonists, IMP, and three L-amino acids (monopotassium L-glutamate, L-serine and L-arginine). Additionally, we used selective antagonists against different mGluRs such as (RS)-L-aminoindan-1,5-dicarboxylic acid (AIDA) (an mGluR1 antagonist), and (RS)-α-methylserine-O-phosphate (MSOP) (an mGluR4 antagonist) to determine if they can block responses elicited by these L-amino acids and IMP. We found that L-amino acid- and IMP-responsive cells also responded to each agonist. Antagonists for mGluR4 and mGluR1 significantly blocked the responses elicited by IMP and each of the L-amino acids. Collectively, these data provide evidence for the involvement of taste and brain variants of mGluR1 and mGluR4 in L-amino acid and IMP taste responses in mice, and support the concept that multiple receptors contribute to IMP and L-amino acid taste. PMID:26701297

  9. Histamine H(1) and H(3) receptors in the rat thalamus and their modulation after systemic kainic acid administration.

    Jin, Congyu; Lintunen, Minnamaija; Panula, Pertti

    2005-07-01

    In rat thalamus, histamine H(1) receptor and isoforms of H(3) receptor were expressed predominantly in the midline and intralaminar areas. Correspondingly, higher H(1) and H(3) receptor binding was also detected in these areas. All isoforms of H(3) receptor were expressed in several thalamic nuclei, but there were minor differences between their expression patterns. H(1) mRNA expression was high in the ventral thalamus, but the H(1) binding level was low in these areas. Since increased brain histamine appears to have an antiepileptic effect through the H(1) receptor activity, kainic acid (KA)-induced status epilepticus in rat was used to study modulation of H(1) and H(3) receptors in the thalamus following seizures. After systemic KA administration, transient decreases in mRNA expression of H(1) receptor and H(3) receptor isoforms with full-length third intracellular loops were seen in the midline areas and the H(1) receptor mRNA expression also decreased in the ventral thalamus. After 1 week, a robust increase in mRNA expression of H(3) receptor isoforms with a full-length third intracellular loop was found in the ventral posterior, posterior, and geniculate nuclei. The changes indicate a modulatory role of H(3) receptor in the sensory and motor relays, and might be involved in possible neuroprotective and compensatory mechanisms after KA administration. However, short-term increases in the H(3) receptor binding appeared earlier (72 h) than the increases of H(3) mRNA expression (1-4 w). The elevations in H(3) binding were evident in the intralaminar area, laterodorsal, lateral posterior, posterior and geniculate nuclei, and were likely to be related to the cortical and subcortical inputs to thalamus. PMID:15899242

  10. (+)Lysergic acid diethylamide, but not its nonhallucinogenic congeners, is a potent serotonin 5HT1C receptor agonist

    Activation of central serotonin 5HT2 receptors is believed to be the primary mechanism whereby lysergic acid diethylamide (LSD) and other hallucinogens induce psychoactive effects. This hypothesis is based on extensive radioligand binding and electrophysiological and behavioral studies in laboratory animals. However, the pharmacological profiles of 5HT2 and 5HT1C receptors are similar, making it difficult to distinguish between effects due to activation of one or the other receptor. For this reason, it was of interest to investigate the interaction of LSD with 5HT1C receptors. Agonist-stimulated phosphoinositide hydrolysis in rat choroid plexus was used as a direct measure of 5HT1C receptor activation. (+)LSD potently stimulated phosphoinositide hydrolysis in intact choroid plexus and in cultures of choroid plexus epithelial cells, with EC50 values of 9 and 26 nM, respectively. The effect of (+)LSD in both systems was blocked by 5HT receptor antagonists with an order of activity consistent with interaction at 5HT1C receptors. Neither (+)-2-bromo-LSD nor lisuride, two nonhallucinogenic congeners of LSD, were able to stimulate 5HT1C receptors in cultured cells or intact choroid plexus. In contrast, lisuride, like (+)LSD, is a partial agonist at 5HT2 receptors in cerebral cortex slices and in NIH 3T3 cells transfected with 5HT2 receptor cDNA. The present finding that (+)LSD, but not its nonhallucinogenic congeners, is a 5HT1C receptor agonist suggests a possible role for these receptors in mediating the psychoactive effects of LSD

  11. LITHOCHOLIC ACID DECREASES EXPRESSION OF UGT2B7 IN CACO-2 CELLS: A POTENTIAL ROLE FOR A NEGATIVE FARNESOID X RECEPTOR RESPONSE ELEMENT

    Lu, Yuan; Heydel, Jean-Marie; LI, XIN; Bratton, Stacie; Lindblom, Tim; Radominska-Pandya, Anna

    2005-01-01

    Human UDP-glucuronosyltransferase (UGT) 2B7 is the major isoform catalyzing the glucuronidation of a variety of endogenous compounds including bile acids. To determine the role of bile acids in the regulation of UGT2B7 expression, Caco-2 cells were incubated with the natural human farnesoid X receptor (hFXR) ligand, chenodeoxycholic acid, as well as the secondary bile acid, lithocholic acid, derived from chenodeoxycholic acid. Incubation of Caco-2 cells with lithocholic acid in the absence of...

  12. Potentiation of acid-sensing ion channel activity by peripheral group I metabotropic glutamate receptor signaling.

    Gan, Xiong; Wu, Jing; Ren, Cuixia; Qiu, Chun-Yu; Li, Yan-Kun; Hu, Wang-Ping

    2016-05-01

    Glutamate activates peripheral group I metabotropic glutamate receptors (mGluRs) and contributes to inflammatory pain. However, it is still not clear the mechanisms are involved in group I mGluR-mediated peripheral sensitization. Herein, we report that group I mGluRs signaling sensitizes acid-sensing ion channels (ASICs) in dorsal root ganglion (DRG) neurons and contributes to acidosis-evoked pain. DHPG, a selective group I mGluR agonist, can potentiate the functional activity of ASICs, which mediated the proton-induced events. DHPG concentration-dependently increased proton-gated currents in DRG neurons. It shifted the proton concentration-response curve upwards, with a 47.3±7.0% increase of the maximal current response to proton. Group I mGluRs, especially mGluR5, mediated the potentiation of DHPG via an intracellular cascade. DHPG potentiation of proton-gated currents disappeared after inhibition of intracellular Gq/11 proteins, PLCβ, PKC or PICK1 signaling. Moreover, DHPG enhanced proton-evoked membrane excitability of rat DRG neurons and increased the amplitude of the depolarization and the number of spikes induced by acid stimuli. Finally, peripherally administration of DHPG dose-dependently exacerbated nociceptive responses to intraplantar injection of acetic acid in rats. Potentiation of ASIC activity by group I mGluR signaling in rat DRG neurons revealed a novel peripheral mechanism underlying group I mGluRs involvement in hyperalgesia. PMID:26946972

  13. Bile-acid-activated farnesoid X receptor regulates hydrogen sulfide production and hepatic microcirculation

    Barbara Renga; Andrea Mencarelli; Marco Migliorati; Eleonora Distrutti; Stefano Fiorucci

    2009-01-01

    AIM: To investigate whether the farnesoid X receptor (FXR) regulates expression of liver cystathionase (CSE), a gene involved in hydrogen sulfide (H2S) generation. METHODS: The regulation of CSE expression in response to FXR ligands was evaluated in HepG2 cells and in wild-type and FXR null mice treated with 6-ethyl chenodeoxycholic acid (6E-CDCA), a synthetic FXR ligand. The analysis demonstrated an FXR responsive element in the 5'-flanking region of the human CSE gene. The function of this site was investigated by luciferase reporter assays, chromatin immunoprecipitation and electrophoretic mobility shift assays. Livers obtained from rats treated with carbon tetrachloride alone, or in combination with 6-ethyl chenodeoxycholic acid, were studied for hydrogen sulphide generation and portal pressure measurement. RESULTS: Liver expression of CSE is regulated by bile acids by means of an FXR-mediated mechanism. Western blotting, qualitative and quantitative polymerase chain reaction, as well as immunohistochemical analysis, showed that expression of CSE in HepG2 cells and in mice is induced by treatment with an FXR ligand. Administration of 6E-CDCA to carbon tetrachloride treated rats protected against the down-regulation of CSE expression, increased H2S generation, reduced portal pressure and attenuated the endothelial dysfunction of isolated and perfused cirrhotic rat livers. CONCLUSION: These results demonstrate that CSE is an FXR-regulated gene and provide a new molecular explanation for the pathophysiology of portal hypertension.

  14. Histamine-induced end-tidal inspiratory activity and lung receptors in cats.

    Meeseen, N E; van der Grinten, C P; Folgering, H T; Luijendijk, S C

    1995-12-01

    Hyperinflation in acute asthma has been associated with inspiratory muscle activity, which persist during expiration. The main objective of the present study was to evaluate the role of rapidly adapting receptors (RARs), slowly adapting receptors (SARs) and C-fibre endings in generating end-tidal inspiratory activity (ETIA). ETIA was induced by intravenous administration of histamine and continuous negative airway pressure (CNAP) in anaesthetized, spontaneously breathing cats. To differentiate between reflex activities from the three types of lung receptors, both vagus nerves were cooled to eight different temperatures (Tvg) between 4 and 37 degrees C. It is known that CNAP stimulates RARs and inhibits SARs. Histamine was used to stimulate RARs, and this was combined with continuous positive airway pressure (CPAP) to further stimulate SARs. ETIA was evoked in the diaphragm and in parasternal intercostal muscles by both stimuli (histamine and CNAP) in 8 out of 18 cats. After vagotomy, neither histamine nor CNAP evoked ETIA any more. At Tvg = 37 degrees C, CPAP suppressed histamine-induced ETIA; whereas, this suppression was diminished at Tvg between 14 and 8 degrees C. ETIA sharply declined for Tvg between 8 degrees and 4 degrees C, and at Tvg = 4 degrees C ETIA had virtually disappeared. At Tvg = 37 degrees and 22 degrees C values of ETIA during CNAP were larger than those in response to histamine; whereas, at Tvg = 10 degrees C comparable ETIA values were obtained. It was shown that ETIA is a vagal reflex activity in which C-fibre endings are not involved. Histamine-induced ETIA originates from stimulation of RARs, and is inhibited by stimulation of SARs. Mechanical stimulation of RARs is a forceful stimulus to induce ETIA. This suggests that hyperinflation in acute asthma might be due, at least in part, to ETIA resulting from an imbalance between SAR and RAR activity. PMID:8666106

  15. Chlorogenic acid improves late diabetes through adiponectin receptor signaling pathways in db/db mice.

    Shasha Jin

    Full Text Available The aim of this study was to examine the effects of chlorogenic acid (CGA on glucose and lipid metabolism in late diabetic db/db mice, as well as on adiponectin receptors and their signaling molecules, to provide evidence for CGA in the prevention of type 2 diabetes. We randomly divided 16 female db/db mice into db/db-CGA and db/db-control (CON groups equally; db/m mice were used as control mice. The mice in both the db/db-CGA and db/m-CGA groups were administered 80 mg/kg/d CGA by lavage for 12 weeks, whereas the mice in both CON groups were given equal volumes of phosphate-buffered saline (PBS by lavage. At the end of the intervention, we assessed body fat and the parameters of glucose and lipid metabolism in the plasma, liver and skeletal muscle tissues as well as the levels of aldose reductase (AR and transforming growth factor-β1 (TGF-β1 in the kidneys and measured adiponectin receptors and the protein expression of their signaling molecules in liver and muscle tissues. After 12 weeks of intervention, compared with the db/db-CON group, the percentage of body fat, fasting plasma glucose (FPG and glycosylated hemoglobin (HbA1c in the db/db-CGA group were all significantly decreased; TGF-β1 protein expression and AR activity in the kidney were both decreased; and the adiponectin level in visceral adipose was increased. The protein expression of adiponectin receptors (ADPNRs, the phosphorylation of AMP-activated protein kinase (AMPK in the liver and muscle, and the mRNA and protein levels of peroxisome proliferator-activated receptor alpha (PPAR-α in the liver were all significantly greater. CGA could lower the levels of fasting plasma glucose and HbA1c during late diabetes and improve kidney fibrosis to some extent through the modulation of adiponectin receptor signaling pathways in db/db mice.

  16. L-Amino Acids Elicit Diverse Response Patterns in Taste Sensory Cells: A Role for Multiple Receptors.

    Shreoshi Pal Choudhuri

    Full Text Available Umami, the fifth basic taste, is elicited by the L-amino acid, glutamate. A unique characteristic of umami taste is the response potentiation by 5' ribonucleotide monophosphates, which are also capable of eliciting an umami taste. Initial reports using human embryonic kidney (HEK cells suggested that there is one broadly tuned receptor heterodimer, T1r1+T1r3, which detects L-glutamate and all other L-amino acids. However, there is growing evidence that multiple receptors detect glutamate in the oral cavity. While much is understood about glutamate transduction, the mechanisms for detecting the tastes of other L-amino acids are less well understood. We used calcium imaging of isolated taste sensory cells and taste cell clusters from the circumvallate and foliate papillae of C57BL/6J and T1r3 knockout mice to determine if other receptors might also be involved in detection of L-amino acids. Ratiometric imaging with Fura-2 was used to study calcium responses to monopotassium L-glutamate, L-serine, L-arginine, and L-glutamine, with and without inosine 5' monophosphate (IMP. The results of these experiments showed that the response patterns elicited by L-amino acids varied significantly across taste sensory cells. L-amino acids other than glutamate also elicited synergistic responses in a subset of taste sensory cells. Along with its role in synergism, IMP alone elicited a response in a large number of taste sensory cells. Our data indicate that synergistic and non-synergistic responses to L-amino acids and IMP are mediated by multiple receptors or possibly a receptor complex.

  17. Tamoxifen stimulates arachidonic acid release from rat liver cells by an estrogen receptor-independent, non-genomic mechanism

    Tamoxifen is widely prescribed for the treatment of breast cancer. Its success has been attributed to the modulation of the estrogen receptor. I have previously proposed that the release of arachidonic acid from cells may also mediate cancer prevention. Rat liver cells were radiolabelled with arachidonic acid. The release of [3H] arachidonic acid after various times of incubation of the cells with tamoxifen was measured. Tamoxifen, at micromolar concentrations, stimulates arachidonic acid release. The stimulation is rapid and is not affected by pre-incubation of the cells with actinomycin or the estrogen antagonist ICI-182,780. The stimulation of AA release by tamoxifen is not mediated by estrogen receptor occupancy and is non-genomic

  18. Activation of peroxisome proliferator-activated receptor-{alpha} enhances fatty acid oxidation in human adipocytes

    Lee, Joo-Young; Hashizaki, Hikari; Goto, Tsuyoshi; Sakamoto, Tomoya; Takahashi, Nobuyuki [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kawada, Teruo, E-mail: fat@kais.kyoto-u.ac.jp [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    2011-04-22

    Highlights: {yields} PPAR{alpha} activation increased mRNA expression levels of adipocyte differentiation marker genes and GPDH activity in human adipocytes. {yields} PPAR{alpha} activation also increased insulin-dependent glucose uptake in human adipocytes. {yields} PPAR{alpha} activation did not affect lipid accumulation in human adipocytes. {yields} PPAR{alpha} activation increased fatty acid oxidation through induction of fatty acid oxidation-related genes in human adipocytes. -- Abstract: Peroxisome proliferator-activated receptor-{alpha} (PPAR{alpha}) is a key regulator for maintaining whole-body energy balance. However, the physiological functions of PPAR{alpha} in adipocytes have been unclarified. We examined the functions of PPAR{alpha} using human multipotent adipose tissue-derived stem cells as a human adipocyte model. Activation of PPAR{alpha} by GW7647, a potent PPAR{alpha} agonist, increased the mRNA expression levels of adipocyte differentiation marker genes such as PPAR{gamma}, adipocyte-specific fatty acid-binding protein, and lipoprotein lipase and increased both GPDH activity and insulin-dependent glucose uptake level. The findings indicate that PPAR{alpha} activation stimulates adipocyte differentiation. However, lipid accumulation was not changed, which is usually observed when PPAR{gamma} is activated. On the other hand, PPAR{alpha} activation by GW7647 treatment induced the mRNA expression of fatty acid oxidation-related genes such as CPT-1B and AOX in a PPAR{alpha}-dependent manner. Moreover, PPAR{alpha} activation increased the production of CO{sub 2} and acid soluble metabolites, which are products of fatty acid oxidation, and increased oxygen consumption rate in human adipocytes. The data indicate that activation of PPAR{alpha} stimulates both adipocyte differentiation and fatty acid oxidation in human adipocytes, suggesting that PPAR{alpha} agonists could improve insulin resistance without lipid accumulation in adipocytes. The expected

  19. Lysophosphatidic Acid Receptor Is a Functional Marker of Adult Hippocampal Precursor Cells

    Tara L. Walker

    2016-04-01

    Full Text Available Here, we show that the lysophosphatidic acid receptor 1 (LPA1 is expressed by a defined population of type 1 stem cells and type 2a precursor cells in the adult mouse dentate gyrus. LPA1, in contrast to Nestin, also marks the quiescent stem cell population. Combining LPA1-GFP with EGFR and prominin-1 expression, we have enabled the prospective separation of both proliferative and non-proliferative precursor cell populations. Transcriptional profiling of the isolated proliferative precursor cells suggested immune mechanisms and cytokine signaling as molecular regulators of adult hippocampal precursor cell proliferation. In addition to LPA1 being a marker of this important stem cell population, we also show that the corresponding ligand LPA is directly involved in the regulation of adult hippocampal precursor cell proliferation and neurogenesis, an effect that can be attributed to LPA signaling via the AKT and MAPK pathways.

  20. Cartilage Acidic Protein–1B (LOTUS), an Endogenous Nogo Receptor Antagonist for Axon Tract Formation

    Sato, Yasufumi; Iketani, Masumi; Kurihara, Yuji; Yamaguchi, Megumi; Yamashita, Naoya; Nakamura, Fumio; Arie, Yuko; Kawasaki, Takahiko; Hirata, Tatsumi; Abe, Takaya; Kiyonari, Hiroshi; Strittmatter, Stephen M.; Goshima, Yoshio; Takei, Kohtaro

    2011-01-01

    Neural circuitry formation depends on the molecular control of axonal projection during development. By screening with fluorophore-assisted light inactivation in the developing mouse brain, we identified cartilage acidic protein–1B as a key molecule for lateral olfactory tract (LOT) formation and named it LOT usher substance (LOTUS). We further identified Nogo receptor–1 (NgR1) as a LOTUS-binding protein. NgR1 is a receptor of myelin-derived axon growth inhibitors, such as Nogo, which prevent neural regeneration in the adult. LOTUS suppressed Nogo-NgR1 binding and Nogo-induced growth cone collapse. A defasciculated LOT was present in lotus-deficient mice but not in mice lacking both lotus- and ngr1. These findings suggest that endogenous antagonism of NgR1 by LOTUS is crucial for normal LOT formation. PMID:21817055

  1. Retinoic acid receptor beta2 promotes functional regeneration of sensory axons in the spinal cord.

    Wong, Liang-Fong; Yip, Ping K; Battaglia, Anna; Grist, John; Corcoran, Jonathan; Maden, Malcolm; Azzouz, Mimoun; Kingsman, Susan M; Kingsman, Alan J; Mazarakis, Nicholas D; McMahon, Stephen B

    2006-02-01

    The embryonic CNS readily undergoes regeneration, unlike the adult CNS, which has limited axonal repair after injury. Here we tested the hypothesis that retinoic acid receptor beta2 (RARbeta2), critical in development for neuronal growth, may enable adult neurons to grow in an inhibitory environment. Overexpression of RARbeta2 in adult rat dorsal root ganglion cultures increased intracellular levels of cyclic AMP and stimulated neurite outgrowth. Stable RARbeta2 expression in DRG neurons in vitro and in vivo enabled their axons to regenerate across the inhibitory dorsal root entry zone and project into the gray matter of the spinal cord. The regenerated neurons enhanced second-order neuronal activity in the spinal cord, and RARbeta2-treated rats showed highly significant improvement in sensorimotor tasks. These findings show that RARbeta2 induces axonal regeneration programs within injured neurons and may thus offer new therapeutic opportunities for CNS regeneration. PMID:16388307

  2. Extending the structure-activity relationship of anthranilic acid derivatives as farnesoid X receptor modulators: development of a highly potent partial farnesoid X receptor agonist.

    Merk, Daniel; Lamers, Christina; Ahmad, Khalil; Carrasco Gomez, Roberto; Schneider, Gisbert; Steinhilber, Dieter; Schubert-Zsilavecz, Manfred

    2014-10-01

    The ligand activated transcription factor nuclear farnesoid X receptor (FXR) is involved as a regulator in many metabolic pathways including bile acid and glucose homeostasis. Therefore, pharmacological activation of FXR seems a valuable therapeutic approach for several conditions including metabolic diseases linked to insulin resistance, liver disorders such as primary biliary cirrhosis or nonalcoholic steatohepatitis, and certain forms of cancer. The available FXR agonists, however, activate the receptor to the full extent which might be disadvantageous over a longer time period. Hence, partial FXR activators are required for long-term treatment of metabolic disorders. We here report the SAR of anthranilic acid derivatives as FXR modulators and development, synthesis, and characterization of compound 51, which is a highly potent partial FXR agonist in a reporter gene assay with an EC50 value of 8 ± 3 nM and on mRNA level in liver cells. PMID:25255039

  3. Effect of Eicosapentaenoic Acid on E-type Prostaglandin Synthesis and EP4 Receptor Signaling Human Colorectal Cancer Cells

    Gillian Hawcroft

    2010-08-01

    Full Text Available The ω-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA, in the free fatty acid (FFA form, has been demonstrated to reduce adenoma number and size in patients with familial adenomatous polyposis. However, the mechanistic basis of the antineoplastic activity of EPA in the colorectum remains unclear. We tested the hypothesis that EPAFFA negatively modulates synthesis of and signaling by prostaglandin (PG E2 in human colorectal cancer (CRC cells. EPA-FFA induced apoptosis of cyclooxygenase (COX-2-positive human HCA-7 CRC cells in vitro. EPA-FFA in cell culture medium was incorporated rapidly into phospholipid membranes of HCA-7 human CRC cells and acted as a substrate for COX-2, leading to reduced synthesis of PGE2 and generation of PGE3. Alone, PGE3 bound and activated the PGE2 EP4 receptor but with reduced affinity and efficacy compared with its “natural” ligand PGE2. However, in the presence of PGE2, PGE3 acted as an antagonist of EP4 receptor-dependent 3’,5’ cyclic adenosine monophosphate induction in naturally EP4 receptor-positive LoVo human CRC cells and of resistance to apoptosis in HT-29-EP4 human CRC cells overexpressing the EP4 receptor. We conclude that EPA-FFA drives a COX-2dependent “PGE2-to-PGE3 switch” in human CRC cells and that PGE3 acts as a partial agonistat the PGE2 EP4 receptor.

  4. Free-fatty acid receptor-4 (GPR120): Cellular and molecular function and its role in metabolic disorders.

    Moniri, Nader H

    2016-06-15

    Over the last decade, a subfamily of G protein-coupled receptors that are agonized by endogenous and dietary free-fatty acids (FFA) has been discovered. These free-fatty acid receptors include FFA2 and FFA3, which are agonized by short-chained FFA, as well as FFA1 and FFA4, which are agonized by medium-to-long chained FFA. Ligands for FFA1 and FFA4 comprise the family of long chain polyunsaturated omega-3 fatty acids including α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), suggesting that many of the long-known beneficial effects of these fats may be receptor mediated. In this regard, FFA4 has gathered considerable interest due to its role in ameliorating inflammation, promoting insulin sensitization, and regulating energy metabolism in response to FFA ligands. The goal of this review is to summarize the body of evidence in regard to FFA4 signal transduction, its mechanisms of regulation, and its functional role in a variety of tissues. In addition, recent endeavors toward discovery of small molecules that modulate FFA4 activity are also presented. PMID:26827942

  5. Membrane omega-3 fatty acids modulate the oligomerisation kinetics of adenosine A2A and dopamine D2 receptors

    Guixà-González, Ramon; Javanainen, Matti; Gómez-Soler, Maricel; Cordobilla, Begoña; Domingo, Joan Carles; Sanz, Ferran; Pastor, Manuel; Ciruela, Francisco; Martinez-Seara, Hector; Selent, Jana

    2016-01-01

    Membrane levels of docosahexaenoic acid (DHA), an essential omega-3 polyunsaturated fatty acid (ω-3 PUFA), are decreased in common neuropsychiatric disorders. DHA modulates key cell membrane properties like fluidity, thereby affecting the behaviour of transmembrane proteins like G protein-coupled receptors (GPCRs). These receptors, which have special relevance for major neuropsychiatric disorders have recently been shown to form dimers or higher order oligomers, and evidence suggests that DHA levels affect GPCR function by modulating oligomerisation. In this study, we assessed the effect of membrane DHA content on the formation of a class of protein complexes with particular relevance for brain disease: adenosine A2A and dopamine D2 receptor oligomers. Using extensive multiscale computer modelling, we find a marked propensity of DHA for interaction with both A2A and D2 receptors, which leads to an increased rate of receptor oligomerisation. Bioluminescence resonance energy transfer (BRET) experiments performed on living cells suggest that this DHA effect on the oligomerisation of A2A and D2 receptors is purely kinetic. This work reveals for the first time that membrane ω-3 PUFAs play a key role in GPCR oligomerisation kinetics, which may have important implications for neuropsychiatric conditions like schizophrenia or Parkinson’s disease.

  6. Dual orexin receptor antagonists show distinct effects on locomotor performance, ethanol interaction and sleep architecture relative to gamma-aminobutyric acid-A receptor modulators

    Andres D. Ramirez

    2013-12-01

    Full Text Available Dual orexin receptor antagonists (DORAs are a potential treatment for insomnia that function by blocking both the orexin 1 and orexin 2 receptors. The objective of the current study was to further confirm the impact of therapeutic mechanisms targeting insomnia on locomotor coordination and ethanol interaction using DORAs and gamma-aminobutyric acid (GABA-A receptor modulators of distinct chemical structure and pharmacologic properties in the context of sleep-promoting potential. The current study compared rat motor co-ordination after administration of DORAs, DORA-12 and almorexant, and GABA-A receptor modulators, zolpidem, eszopiclone and diazepam, alone or each in combination with ethanol. Motor performance was assessed by measuring time spent walking on a rotarod apparatus. Zolpidem, eszopiclone and diazepam (0.3–30 mg/kg administered orally [PO] impaired rotarod performance in a dose-dependent manner. Furthermore, all three GABA-A receptor modulators potentiated ethanol- (0.25–1.25 g/kg induced impairment on the rotarod. By contrast, neither DORA-12 (10–100 mg/kg, PO nor almorexant (30–300 mg/kg, PO impaired motor performance alone or in combination with ethanol. In addition, distinct differences in sleep architecture were observed between ethanol, GABA-A receptor modulators (zolpidem, eszopiclone and diazepam and DORA-12 in electroencephalogram studies in rats. These findings provide further evidence that orexin receptor antagonists have an improved motor side-effect profile compared with currently available sleep-promoting agents based on preclinical data and strengthen the rationale for further evaluation of these agents in clinical development.

  7. Microfacies of the Triassic limestones in the Izvorul Malului klippe (Rarău Syncline, Transylvanian Nappes, Eastern Carpathians, Romania

    Daniela Alexandra POPESCU

    2008-06-01

    Full Text Available The Transylvanian Nappes belongs to the Central – East – Carpathian Nappes System (the Dacides Medianes which forms. The Transylvanian Nappes have a superior position in the Carpahian tectonic system that favored their fragmentation in the obduction process and slow gravitational decollement. This process makes difficult to establish the exclusively Mesozoic Transylvaniansedimentary series, especially because the majority of the litostratigraphic members occur only as isolated klippe in the Hauterivian-Aptian wildflysh filling (the superior formationbelonging to the Bucovinian Nappe of the Rarău Syncline.The allochtonous sedimentary succesion of the Transylvanian Nappes is almost exclusively represented by pelagic carbonate deposits. The amazing fossil diversity offeredmainly by the klippes of the Rarău Syncline facilitated the reconstruction of the Triassic lithological column which contains all stratigraphical terms confirmed by a rich paleontological material. The Upper Triassic carbonate deposits cropp out in few metric (Piatra Zimbrului, Popii Rarăului or submetric blocks (the klippes on the Cailor, Măceş, Izvorul Malului brooks,on the springs of the Timon brook etc. occuring in the Rarău Syncline. The studied limestone klippe is located on the left side of the Izvorul Malului brook, about 2,5 – 3 km up from his confluence with the Moldova river. The klippe which is almosttotally exploited consists of few white and gray limestone submetric blocks with Halobia. Microcrystalline carbonates are represented by muddy sediments accumulated in lowenergyquiet waters on the sea floor. The sediment consists of skeletal debris and unattachedprecipitates or of attached non-sketetal precipitates. The last two cases corespond to theautochthonous organomicrites and are characterized by common peloidal fabric. Theformation of peloids requires low or moderate rates of sediment input.Tethyan Carnian, Norian and Rhaetian carbonate

  8. The Vitamin A Derivative All-Trans Retinoic Acid Repairs Amyloid-β-Induced Double-Strand Breaks in Neural Cells and in the Murine Neocortex

    Emmanuelle Gruz-Gibelli

    2016-01-01

    Full Text Available The amyloid-β peptide or Aβ is the key player in the amyloid-cascade hypothesis of Alzheimer’s disease. Aβ appears to trigger cell death but also production of double-strand breaks (DSBs in aging and Alzheimer’s disease. All-trans retinoic acid (RA, a derivative of vitamin A, was already known for its neuroprotective effects against the amyloid cascade. It diminishes, for instance, the production of Aβ peptides and their oligomerisation. In the present work we investigated the possible implication of RA receptor (RAR in repair of Aβ-induced DSBs. We demonstrated that RA, as well as RAR agonist Am80, but not AGN 193109 antagonist, repair Aβ-induced DSBs in SH-SY5Y cells and an astrocytic cell line as well as in the murine cortical tissue of young and aged mice. The nonhomologous end joining pathway and the Ataxia Telangiectasia Mutated kinase were shown to be involved in RA-mediated DSBs repair in the SH-SY5Y cells. Our data suggest that RA, besides increasing cell viability in the cortex of young and even of aged mice, might also result in targeted DNA repair of genes important for cell or synaptic maintenance. This phenomenon would remain functional up to a point when Aβ increase and RA decrease probably lead to a pathological state.

  9. Expression of the short chain fatty acid receptor GPR41/FFAR3 in autonomic and somatic sensory ganglia

    Nøhr, Mark Klitgaard; Egerod, K L; Christiansen, S H;

    2015-01-01

    G-protein-coupled receptor 41 (GPR41) also called free fatty acid receptor 3 (FFAR3) is a Gαi-coupled receptor activated by short-chain fatty acids (SCFAs) mainly produced from dietary complex carbohydrate fibers in the large intestine as products of fermentation by microbiota. FFAR3 is expressed...... in enteroendocrine cells, but has recently also been shown to be present in sympathetic neurons of the superior cervical ganglion. The aim of this study was to investigate whether the FFAR3 is present in other autonomic and sensory ganglia possibly influencing gut physiology. Cryostat sections were...... ganglia such as the vagal ganglion, the spinal dorsal root ganglion and the trigeminal ganglion. No expression was observed in the brain or spinal cord. By use of radioactive-labeled antisense DNA probes, mRNA encoding the FFAR3 was found to be present in cells of the same ganglia. Further, the expression...

  10. Hyaluronic Acid Immobilized Polyacrylamide Nanoparticle Sensors for CD44 Receptor Targeting and pH Measurement in Cells

    Sun, Honghao; Benjaminsen, Rikke Vicki; Almdal, Kristoffer;

    2012-01-01

    the CD44 receptor, which is overexpressed on the surface of a broad variety of cancer cells, we have synthesized an NP pH sensor system that targets CD44. We used a polyacrylamide nanoparticle matrix bearing hyaluronic acid (HA) on the surface as a CD44 targeting ligand. The HA-coated NPs were...

  11. Non-covalent conjugates of single-walled carbon nanotubes and folic acid for interaction with cells overexpressing folate receptors

    Castillo, John J.; Rindzevicius, Tomas; Novoa, Leidy V.;

    2013-01-01

    We here present amethod to form a noncovalent conjugate of single-walled carbon nanotubes and folic acid aimed to interact with cells over-expressing folate receptors. The bonding was obtained without covalent chemical functionalization using a simple, rapid “one pot” synthesis method. The zeta p...

  12. Distribution of sialic acid receptors and influenza A viruses of avian and swine origin and in experimentally infected pigs

    Trebbien, Ramona; Larsen, Lars Erik; Viuff, Birgitte M.

    2011-01-01

    Background: Pigs are considered susceptible to influenza A virus infections from different host origins because earlier studies have shown that they have receptors for both avian (sialic acid-alpha-2,3-terminal saccharides (SAalpha- 2,3)) and swine/human (SA-alpha-2,6) influenza viruses in the...

  13. Establishing an Ion Pair Interaction in the Homomeric {rho}1 {gamma}-Aminobutyric Acid Type A Receptor That Contributes to the Gating Pathway

    Wang, Jinti; Lester, Henry A.; Dougherty, Dennis A.

    2007-01-01

    {gamma}-Aminobutyric acid type A (GABAA) receptors are members of the Cys-loop superfamily of ligand-gated ion channels. Upon agonist binding, the receptor undergoes a structural transition from the closed to the open state, but the mechanism of gating is not well understood. Here we utilized a combination of conventional mutagenesis and the high precision methodology of unnatural amino acid incorporation to study the gating interface of the human homopentameric {rho}1 GABAA receptor. We have...

  14. Ondansetron and Granisetron Binding Orientation in the 5-HT3 Receptor Determined by Unnatural Amino Acid Mutagenesis

    Duffy, Noah H.; Lester, Henry A.; Dougherty, Dennis A.

    2012-01-01

    The serotonin type 3 receptor (5-HT3R) is a ligand-gated ion channel that mediates fast synaptic transmission in the central and peripheral nervous systems. The 5-HT3R is a therapeutic target, and the clinically available drugs ondansetron and granisetron inhibit receptor activity. Their inhibitory action is through competitive binding to the native ligand binding site, although the binding orientation of the drugs at the receptor has been a matter of debate. Here we heterologously express mouse 5-HT3A receptors in Xenopus oocytes and use unnatural amino acid mutagenesis to establish a cation-π interaction for both ondansetron and granisetron to tryptophan 183 in the ligand binding pocket. This cation-π interaction establishes a binding orientation for both ondansetron and granisetron within the binding pocket. PMID:22873819

  15. Hyaluronic acid receptor Stabilin-2 regulates Erk phosphorylation and arterial--venous differentiation in zebrafish.

    Megan S Rost

    Full Text Available The hyaluronic acid receptor for endocytosis Stabilin-2/HARE mediates systemic clearance of multiple glycosaminoglycans from the vascular and lymphatic circulations. In addition, recent in vitro studies indicate that Stab2 can participate in signal transduction by interacting with hyaluronic acid (HA, which results in Erk phosphorylation. However, it is not known whether Stab2 function or HA-Stab2 signaling play any role in embryonic development. Here we show that Stab2 functions in a signal transduction pathway regulating arterial-venous differentiation during zebrafish embryogenesis. Stab2 morpholino knockdown embryos (morphants display an absence of intersegmental vessels and defects in the axial vessel formation. In addition, Stab2 morphants show defects in arterial-venous differentiation including the expansion of venous marker expression. Simultaneous knockdown of Stabilin-2 and Has2, an HA synthetase, results in a synergistic effect, arguing that HA and Stab2 interact during vasculature formation. Stab2 morphants display reduced Erk phosphorylation in the arterial progenitors, which is a known transducer of VEGF signaling, previously associated with arterial-venous differentiation. In addition, VEGF signaling acts as a negative feedback loop to repress stab2 expression. These results argue that Stab2 is involved in a novel signaling pathway that plays an important role in regulating Erk phosphorylation and establishing arterial-venous identity.

  16. Sgt1, but not Rar1, is essential for the RB-mediated broad-spectrum resistance to potato late blight

    Wielgus Susan M

    2008-01-01

    Full Text Available Abstract Background Late blight is the most serious potato disease world-wide. The most effective and environmentally sound way for controlling late blight is to incorporate natural resistance into potato cultivars. Several late blight resistance genes have been cloned recently. However, there is almost no information available about the resistance pathways mediated by any of those genes. Results We previously cloned a late blight resistance gene, RB, from a diploid wild potato species Solanum bulbocastanum. Transgenic potato lines containing a single RB gene showed a rate-limiting resistance against all known races of Phytophthora infestans, the late blight pathogen. To better understand the RB-mediated resistance we silenced the potato Rar1 and Sgt1 genes that have been implicated in mediating disease resistance responses against various plant pathogens and pests. The Rar1 and Sgt1 genes of a RB-containing potato clone were silenced using a RNA interference (RNAi-based approach. All of the silenced potato plants displayed phenotypically normal growth. The late blight resistance of the Rar1 and Sgt1 silenced lines were evaluated by a traditional greenhouse inoculation method and quantified using a GFP-tagged P. infestans strain. The resistance of the Rar1-silenced plants was not affected. However, silencing of the Sgt1 gene abolished the RB-mediated resistance. Conclusion Our study shows that silencing of the Sgt1 gene in potato does not result in lethality. However, the Sgt1 gene is essential for the RB-mediated late blight resistance. In contrast, the Rar1 gene is not required for RB-mediated resistance. These results provide additional evidence for the universal role of the Sgt1 gene in various R gene-mediated plant defense responses.

  17. Type 1 cannabinoid receptor mapping with [18F]MK-9470 PET in the rat brain after quinolinic acid lesion: a comparison to dopamine receptors and glucose metabolism

    Several lines of evidence imply early alterations in metabolic, dopaminergic and endocannabinoid neurotransmission in Huntington's disease (HD). Using [18F]MK-9470 and small animal PET, we investigated cerebral changes in type 1 cannabinoid (CB1) receptor binding in the quinolinic acid (QA) rat model of HD in relation to glucose metabolism, dopamine D2 receptor availability and amphetamine-induced turning behaviour. Twenty-one Wistar rats (11 QA and 10 shams) were investigated. Small animal PET acquisitions were conducted on a Focus 220 with approximately 18 MBq of [18F]MK-9470, [18F]FDG and [11C]raclopride. Relative glucose metabolism and parametric CB1 receptor and D2 binding images were anatomically standardized to Paxinos space and analysed voxel-wise using Statistical Parametric Mapping (SPM2). In the QA model, [18F]MK-9470 uptake, glucose metabolism and D2 receptor binding were reduced in the ipsilateral caudate-putamen by 7, 35 and 77%, respectively (all p -5), while an increase for these markers was observed on the contralateral side (>5%, all p -4). [18F]MK-9470 binding was also increased in the cerebellum (p = 2.10-5), where it was inversely correlated to the number of ipsiversive turnings (p = 7.10-6), suggesting that CB1 receptor upregulation in the cerebellum is related to a better functional outcome. Additionally, glucose metabolism was relatively increased in the contralateral hippocampus, thalamus and sensorimotor cortex (p = 1.10-6). These data point to in vivo changes in endocannabinoid transmission, specifically for CB1 receptors in the QA model, with involvement of the caudate-putamen, but also distant regions of the motor circuitry, including the cerebellum. These data also indicate the occurrence of functional plasticity on metabolism, D2 and CB1 neurotransmission in the contralateral hemisphere. (orig.)

  18. Deletion of GPR40 fatty acid receptor gene in mice blocks mercaptoacetate-induced feeding.

    Li, Ai-Jun; Wiater, Michael F; Wang, Qing; Wank, Stephen; Ritter, Sue

    2016-05-15

    Both increased and decreased fatty acid (FA) availability contribute to control of food intake. For example, it is well documented that intestinal FA reduces feeding by triggering enterondocrine secretion of satietogenic peptides, such as cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1). In contrast, mechanisms by which decreased FA availability increase feeding are not well understood. Over the past three decades substantial research related to FA availability and increased feeding has involved use of the orexigenic compound mercaptoacetate (MA). Because MA reportedly inhibits FA oxidation, it has been assumed that reduced FA oxidation accounts for the orexigenic action of MA. Recently, however, we demonstrated that MA antagonizes G protein-coupled receptor 40 (GPR40), a membrane receptor for long and medium chain FA. We also demonstrated that, by antagonizing GPR40, MA inhibits GLP-1 secretion and attenuates vagal afferent activation by FA. Because both vagal afferent activation and GLP-1 inhibit food intake, we postulated that inhibition of GPR40 by MA might underlie the orexigenic action of MA. We tested this hypothesis using male and female GPR40 knockout (KO) and wild-type (WT) mice. Using several testing protocols, we found that MA increased feeding in WT, but not GPR40 KO mice, and that GPR40 KO mice gained more weight than WT on a high-fat diet. Metabolic monitoring after MA or saline injection in the absence of food did not reveal significant differences in respiratory quotient or energy expenditure between treatment groups or genotypes. These results support the hypothesis that MA stimulates food intake by blocking FA effects on GPR40. PMID:26984894

  19. Analysis of β-Subunit-dependent GABAA Receptor Modulation and Behavioral Effects of Valerenic Acid Derivatives.

    Khom, S; Hintersteiner, J; Luger, D; Haider, M; Pototschnig, G; Mihovilovic, M D; Schwarzer, C; Hering, S

    2016-06-01

    Valerenic acid (VA)-a β2/3-selective GABA type A (GABAA) receptor modulator-displays anxiolytic and anticonvulsive effects in mice devoid of sedation, making VA an interesting drug candidate. Here we analyzed β-subunit-dependent enhancement of GABA-induced chloride currents (IGABA) by a library of VA derivatives and studied their effects on pentylenetetrazole (PTZ)-induced seizure threshold and locomotion. Compound-induced IGABA enhancement was determined in oocytes expressing α1β1γ2S, α1β2γ2S, or α1β3γ2S receptors. Effects on seizure threshold and locomotion were studied using C57BL/6N mice and compared with saline-treated controls. β2/3-selective VA derivatives such as VA-amide (VA-A) modulating α1β3γ2S (VA-A: Emax = 972 ± 69%, n = 6, P tetrazole (α1β3γ2S: VA-TET: EC50 = 6.0 ± 1.0 μM, P < 0.05; VA-TET: 0.3 mg/kg: 47.3 ± 0.5 mg/kg PTZ versus VA: 10 mg/kg: 49.0 ± 1.8 mg/kg PTZ, P < 0.05). At higher doses (≥10 mg/kg), VA-A, VA-MA, and VA-TET reduced locomotion. In contrast, unselective VA derivatives induced anticonvulsive effects only at high doses (30 mg/kg) or did not display any behavioral effects. Our data indicate that the β2/3-selective compounds VA-A, VA-MA, and VA-TET induce anticonvulsive effects at low doses (≤10 mg/kg), whereas impairment of locomotion was observed at doses ≥10 mg/kg. PMID:27190170

  20. Mutational characterization of the bile acid receptor TGR5 in primary sclerosing cholangitis.

    Johannes R Hov

    Full Text Available BACKGROUND: TGR5, the G protein-coupled bile acid receptor 1 (GPBAR1, has been linked to inflammatory pathways as well as bile homeostasis, and could therefore be involved in primary sclerosing cholangitis (PSC a chronic inflammatory bile duct disease. We aimed to extensively investigate TGR5 sequence variation in PSC, as well as functionally characterize detected variants. METHODOLOGY/PRINCIPAL FINDINGS: Complete resequencing of TGR5 was performed in 267 PSC patients and 274 healthy controls. Six nonsynonymous mutations were identified in addition to 16 other novel single-nucleotide polymorphisms. To investigate the impact from the nonsynonymous variants on TGR5, we created a receptor model, and introduced mutated TGR5 constructs into human epithelial cell lines. By using confocal microscopy, flow cytometry and a cAMP-sensitive luciferase assay, five of the nonsynonymous mutations (W83R, V178M, A217P, S272G and Q296X were found to reduce or abolish TGR5 function. Fine-mapping of the previously reported PSC and UC associated locus at chromosome 2q35 in large patient panels revealed an overall association between the TGR5 single-nucleotide polymorphism rs11554825 and PSC (odds ratio = 1.14, 95% confidence interval: 1.03-1.26, p = 0.010 and UC (odds ratio = 1.19, 95% confidence interval 1.11-1.27, p = 8.5 x 10(-7, but strong linkage disequilibrium precluded demarcation of TGR5 from neighboring genes. CONCLUSIONS/SIGNIFICANCE: Resequencing of TGR5 along with functional investigations of novel variants provided unique insight into an important candidate gene for several inflammatory and metabolic conditions. While significant TGR5 associations were detected in both UC and PSC, further studies are needed to conclusively define the role of TGR5 variation in these diseases.

  1. Mutational Characterization of the Bile Acid Receptor TGR5 in Primary Sclerosing Cholangitis

    Hov, Johannes R.; Keitel, Verena; Laerdahl, Jon K.; Spomer, Lina; Ellinghaus, Eva; ElSharawy, Abdou; Melum, Espen; Boberg, Kirsten M.; Manke, Thomas; Balschun, Tobias; Schramm, Christoph; Bergquist, Annika; Weismüller, Tobias; Gotthardt, Daniel; Rust, Christian; Henckaerts, Liesbet; Onnie, Clive M.; Weersma, Rinse K.; Sterneck, Martina; Teufel, Andreas; Runz, Heiko; Stiehl, Adolf; Ponsioen, Cyriel Y.; Wijmenga, Cisca; Vatn, Morten H.; Stokkers, Pieter C. F.; Vermeire, Severine; Mathew, Christopher G.; Lie, Benedicte A.; Beuers, Ulrich; Manns, Michael P.; Schreiber, Stefan; Schrumpf, Erik; Häussinger, Dieter; Franke, Andre; Karlsen, Tom H.

    2010-01-01

    Background TGR5, the G protein-coupled bile acid receptor 1 (GPBAR1), has been linked to inflammatory pathways as well as bile homeostasis, and could therefore be involved in primary sclerosing cholangitis (PSC) a chronic inflammatory bile duct disease. We aimed to extensively investigate TGR5 sequence variation in PSC, as well as functionally characterize detected variants. Methodology/Principal Findings Complete resequencing of TGR5 was performed in 267 PSC patients and 274 healthy controls. Six nonsynonymous mutations were identified in addition to 16 other novel single-nucleotide polymorphisms. To investigate the impact from the nonsynonymous variants on TGR5, we created a receptor model, and introduced mutated TGR5 constructs into human epithelial cell lines. By using confocal microscopy, flow cytometry and a cAMP-sensitive luciferase assay, five of the nonsynonymous mutations (W83R, V178M, A217P, S272G and Q296X) were found to reduce or abolish TGR5 function. Fine-mapping of the previously reported PSC and UC associated locus at chromosome 2q35 in large patient panels revealed an overall association between the TGR5 single-nucleotide polymorphism rs11554825 and PSC (odds ratio  = 1.14, 95% confidence interval: 1.03–1.26, p = 0.010) and UC (odds ratio  = 1.19, 95% confidence interval 1.11–1.27, p = 8.5×10−7), but strong linkage disequilibrium precluded demarcation of TGR5 from neighboring genes. Conclusions/Significance Resequencing of TGR5 along with functional investigations of novel variants provided unique insight into an important candidate gene for several inflammatory and metabolic conditions. While significant TGR5 associations were detected in both UC and PSC, further studies are needed to conclusively define the role of TGR5 variation in these diseases. PMID:20811628

  2. Positive cooperativity between the thrombin and bradykinin B2 receptors enhances arachidonic acid release.

    Hecquet, Claudie; Biyashev, Dauren; Tan, Fulong; Erdös, Ervin G

    2006-03-01

    Bradykinin (BK) or kallikreins activate B2 receptors (R) that couple Galpha(i) and Galpha(q) proteins to release arachidonic acid (AA) and elevate intracellular Ca2+ concentration ([Ca2+]i). Thrombin cleaves the protease-activated-receptor-1 (PAR1) that couples Galpha(i), Galpha(q), and Galpha(12/13) proteins. In Chinese hamster ovary cells stably transfected with human B2R, thrombin liberated little AA, but it significantly potentiated AA release by B2R agonists. We explored mechanisms of cooperativity between constitutively expressed PAR1 and B2R. We also examined human endothelial cells expressing both Rs constitutively. The PAR1 agonist hexapeptide (TRAP) was as effective as thrombin. Inhibitors of components of Galpha(i), Galpha(q), and Galpha(12/13) signaling pathways, and a protein kinase C (PKC)-alpha inhibitor, Gö-6976, blocked potentiation, while phorbol, an activator, enhanced it. Several inhibitors, including a RhoA kinase inhibitor, a [Ca2+]i antagonist, and an inositol-(1,3,4)-trisphosphate R antagonist, reduced mobilization of [Ca2+]i by thrombin and blocked potentiation of AA release by B2R agonists. Because either a nonselective inhibitor (isotetrandrine) of phospholipase A2 (PLA2) or a Ca2+-dependent PLA2 inhibitor abolished potentiation of AA release by thrombin, while a Ca2+-independent PLA2 inhibitor did not, we concluded that the mechanism involves Ca2+-dependent PLA2 activation. Both thrombin and TRAP modified activation and phosphorylation of the B2R induced by BK. In lower concentrations they enhanced it, while higher concentrations inhibited phosphorylation and diminished B2R activation. Protection of the NH2-terminal Ser1-Phe2 bond of TRAP by an aminopeptidase inhibitor made this peptide much more active than the unprotected agonist. Thus PAR1 activation enhances AA release by B2R agonists through signal transduction pathway. PMID:16183725

  3. Positive cooperativity between the thrombin and bradykinin B2 receptors enhances arachidonic acid release

    Hecquet, Claudie; Biyashev, Dauren; Tan, Fulong; Erdös, Ervin G.

    2006-01-01

    Bradykinin (BK) or kallikreins activate B2 receptors (R) which couple Gαi and Gαq proteins to release arachidonic acid (AA) and elevate [Ca2+]i. Thrombin cleaves the protease-activated-receptor-1 (PAR1) that couples Gαi, Gαq and Gα12/13 proteins. In CHO cells stably transfected with human B2R, thrombin liberated little AA, but it significantly potentiated AA release by B2R agonists. We explored mechanisms of cooperativity between constitutively expressed PAR1 and B2R. We also examined human endothelial cells expressing both Rs constitutively. The PAR1 agonist hexapeptide (TRAP) was as effective as thrombin. Inhibitors of components of Gαi, Gαq and Gα12/13 signaling pathways, and a PKCα inhibitor, Gö6976 blocked potentiation while phorbol, an activator, enhanced it. Several inhibitors, including a RhoA kinase inhibitor, a [Ca2+]i antagonist, and an inositol-(1,3,4)-trisphosphate R antagonist, reduced mobilization of [Ca2+]i by thrombin and blocked potentiation of AA release by B2R agonists. Because either a non-selective inhibitor (isotetrandrine) of phospholipase A2 (PLA2) or a Ca2+-dependent PLA2 inhibitor abolished potentiation of AA release by thrombin, while a Ca2+-independent PLA2 inhibitor did not, we concluded that the mechanism involves Ca2+-dependent PLA2 activation. Both thrombin and TRAP modified activation and phosphorylation of the B2R induced by BK. In lower concentrations they enhanced it, while higher concentrations inhibited phosphorylation and diminished B2R activation. Protection of the N-terminal Ser1-Phe2 bond of TRAP by an aminopeptidase inhibitor made this peptide much more active than the unprotected agonist. Thus, PAR1 activation enhances AA release by B2R agonists through signal transduction pathway. PMID:16183725

  4. Colorimetric detection of fluoride ion by 5-arylidenebarbituric acids: dual interaction mode for fluoride ion with single receptor.

    Saravanan, Chinnusamy; Easwaramoorthi, Shanmugam; Wang, Leeyih

    2014-04-01

    Two 5-arylidenebarbituric acid derivatives (IH and IM) have been synthesized by the Knoevenagel condensation of barbituric acid with 4-N,N-dimethylamino benzaldehyde and studied for anion sensing activities. Both receptors sense fluoride ion with high selectivity and sensitivity and the sensing action has been demonstrated by naked eye detection, UV-visible absorption, and fluorescence spectral changes in the presence of F(-). Indeed, the F(-) sensing mechanism for receptor IH depends on F(-) ion concentration. While at higher concentrations F(-) forms strong hydrogen bonding interaction with the N-H proton of the receptor, at lower concentrations sensing is influenced by the deprotonation of the methylene proton, followed by the chemical reaction, which is also confirmed by the (1)H-NMR technique. On the other hand, when replacing the N-H proton with a methyl group, IM does not show any concentration dependent behaviour with F(-). The F(-) concentration dependent sensing is attributed to the changes in the receptor-anion interaction equilibrium, where at higher F(-) concentrations, F(-) interacts with the receptor through hydrogen bonding and at lower concentrations it induces a chemical reaction. PMID:24500374

  5. Short-chain free fatty acid receptors FFA2/GPR43 and FFA3/GPR41 as new potential therapeutic targets

    Ulven, Trond

    2012-01-01

    The deorphanization of the free fatty acid (FFA) receptors FFA1 (GPR40), FFA2 (GPR43), FFA3 (GPR41), GPR84, and GPR120 has made clear that the body is capable of recognizing and responding directly to nonesterified fatty acid of virtually any chain length. Colonic fermentation of dietary fiber produces high concentrations of the short-chain fatty acids (SCFAs) acetate, propionate and butyrate, a process which is important to health. The phylogenetically related 7-transmembrane (7TM) receptors...

  6. Short-chain free fatty acid receptors FFA2/GPR43 and FFA3/GPR41 as new potential therapeutic targets

    Trond eUlven

    2012-01-01

    The deorphanization of the free fatty acid (FFA) receptors FFA1 (GPR40), FFA2 (GPR43), FFA3 (GPR41), GPR84 and GPR120 made clear that the body is capable of recognizing and responding directly to nonesterified fatty acid of virtually any chain length. Colonic fermentation of dietary fiber produces high concentrations of the short-chain fatty acids (SCFAs) acetate, propionate and butyrate, a process which is important to health. The phylogenetically related 7-transmembrane receptors free fatty...

  7. Retinoid receptor signaling and autophagy in acute promyelocytic leukemia

    Orfali, Nina [Cork Cancer Research Center, University College Cork, Cork (Ireland); Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA. (United States); McKenna, Sharon L. [Cork Cancer Research Center, University College Cork, Cork (Ireland); Cahill, Mary R. [Department of Hematology, Cork University Hospital, Cork (Ireland); Gudas, Lorraine J., E-mail: ljgudas@med.cornell.edu [Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA. (United States); Mongan, Nigel P., E-mail: nigel.mongan@nottingham.ac.uk [Faculty of Medicine and Health Science, School of Veterinary Medicine and Science, University of Nottingham, LE12 5RD (United Kingdom); Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA. (United States)

    2014-05-15

    Retinoids are a family of signaling molecules derived from vitamin A with well established roles in cellular differentiation. Physiologically active retinoids mediate transcriptional effects on cells through interactions with retinoic acid (RARs) and retinoid-X (RXR) receptors. Chromosomal translocations involving the RARα gene, which lead to impaired retinoid signaling, are implicated in acute promyelocytic leukemia (APL). All-trans-retinoic acid (ATRA), alone and in combination with arsenic trioxide (ATO), restores differentiation in APL cells and promotes degradation of the abnormal oncogenic fusion protein through several proteolytic mechanisms. RARα fusion-protein elimination is emerging as critical to obtaining sustained remission and long-term cure in APL. Autophagy is a degradative cellular pathway involved in protein turnover. Both ATRA and ATO also induce autophagy in APL cells. Enhancing autophagy may therefore be of therapeutic benefit in resistant APL and could broaden the application of differentiation therapy to other cancers. Here we discuss retinoid signaling in hematopoiesis, leukemogenesis, and APL treatment. We highlight autophagy as a potential important regulator in anti-leukemic strategies. - Highlights: • Normal and aberrant retinoid signaling in hematopoiesis and leukemia is reviewed. • We suggest a novel role for RARα in the development of X-RARα gene fusions in APL. • ATRA therapy in APL activates transcription and promotes onco-protein degradation. • Autophagy may be involved in both onco-protein degradation and differentiation. • Pharmacologic autophagy induction may potentiate ATRA's therapeutic effects.

  8. Retinoid receptor signaling and autophagy in acute promyelocytic leukemia

    Retinoids are a family of signaling molecules derived from vitamin A with well established roles in cellular differentiation. Physiologically active retinoids mediate transcriptional effects on cells through interactions with retinoic acid (RARs) and retinoid-X (RXR) receptors. Chromosomal translocations involving the RARα gene, which lead to impaired retinoid signaling, are implicated in acute promyelocytic leukemia (APL). All-trans-retinoic acid (ATRA), alone and in combination with arsenic trioxide (ATO), restores differentiation in APL cells and promotes degradation of the abnormal oncogenic fusion protein through several proteolytic mechanisms. RARα fusion-protein elimination is emerging as critical to obtaining sustained remission and long-term cure in APL. Autophagy is a degradative cellular pathway involved in protein turnover. Both ATRA and ATO also induce autophagy in APL cells. Enhancing autophagy may therefore be of therapeutic benefit in resistant APL and could broaden the application of differentiation therapy to other cancers. Here we discuss retinoid signaling in hematopoiesis, leukemogenesis, and APL treatment. We highlight autophagy as a potential important regulator in anti-leukemic strategies. - Highlights: • Normal and aberrant retinoid signaling in hematopoiesis and leukemia is reviewed. • We suggest a novel role for RARα in the development of X-RARα gene fusions in APL. • ATRA therapy in APL activates transcription and promotes onco-protein degradation. • Autophagy may be involved in both onco-protein degradation and differentiation. • Pharmacologic autophagy induction may potentiate ATRA's therapeutic effects

  9. Retinoid receptor signaling and autophagy in acute promyelocytic leukemia.

    Orfali, Nina

    2014-05-15

    Retinoids are a family of signaling molecules derived from vitamin A with well established roles in cellular differentiation. Physiologically active retinoids mediate transcriptional effects on cells through interactions with retinoic acid (RARs) and retinoid-X (RXR) receptors. Chromosomal translocations involving the RARα gene, which lead to impaired retinoid signaling, are implicated in acute promyelocytic leukemia (APL). All-trans-retinoic acid (ATRA), alone and in combination with arsenic trioxide (ATO), restores differentiation in APL cells and promotes degradation of the abnormal oncogenic fusion protein through several proteolytic mechanisms. RARα fusion-protein elimination is emerging as critical to obtaining sustained remission and long-term cure in APL. Autophagy is a degradative cellular pathway involved in protein turnover. Both ATRA and ATO also induce autophagy in APL cells. Enhancing autophagy may therefore be of therapeutic benefit in resistant APL and could broaden the application of differentiation therapy to other cancers. Here we discuss retinoid signaling in hematopoiesis, leukemogenesis, and APL treatment. We highlight autophagy as a potential important regulator in anti-leukemic strategies.

  10. Blockade of lysophosphatidic acid receptors LPAR1/3 ameliorates lung fibrosis induced by irradiation

    Highlights: → Lysophosphatidic acid (LPA) levels and its receptors LPAR1/3 transcripts were elevated during the development of radiation-induced lung fibrosis. → Lung fibrosis was obviously alleviated in mice treated with the dual LPAR1/3 antagonist, VPC12249. → VPC12249 administration effectively inhibited radiation-induced fibroblast accumulation in vivo, and suppressed LPA-induced fibroblast proliferation in vitro. → LPA-LPAR1/3 signaling regulated TGFβ1 and CTGF expressions in radiation-challenged lungs, but only influenced CTGF expression in cultured fibroblasts. → LPA-LPAR1/3 signaling induced fibroblast proliferation through a CTGF-dependent pathway, rather than through TGFβ1 activation. -- Abstract: Lung fibrosis is a common and serious complication of radiation therapy for lung cancer, for which there are no efficient treatments. Emerging evidence indicates that lysophosphatidic acid (LPA) and its receptors (LPARs) are involved in the pathogenesis of fibrosis. Here, we reported that thoracic radiation with 16 Gy in mice induced development of radiation lung fibrosis (RLF) accompanied by obvious increases in LPA release and LPAR1 and LPAR3 (LPAR1/3) transcripts. RLF was significantly alleviated in mice treated with the dual LPAR1/3 antagonist, VPC12249. VPC12249 administration effectively prolonged animal survival, restored lung structure, inhibited fibroblast accumulation and reduced collagen deposition. Moreover, profibrotic cytokines in radiation-challenged lungs obviously decreased following administration of VPC12249, including transforming growth factor β1 (TGFβ1) and connective tissue growth factor (CTGF). In vitro, LPA induced both fibroblast proliferation and CTGF expression in a dose-dependent manner, and both were suppressed by blockade of LPAR1/3. The pro-proliferative activity of LPA on fibroblasts was inhibited by siRNA directed against CTGF. Together, our data suggest that the LPA-LPAR1/3 signaling system is involved in the

  11. Blockade of lysophosphatidic acid receptors LPAR1/3 ameliorates lung fibrosis induced by irradiation

    Gan, Lu [State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu (China); Xue, Jian-Xin [Department of Thoracic Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu (China); Laboratory of Stem Cell Biology, West China Hospital, Sichuan University, Chengdu (China); Li, Xin [Department of Thoracic Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu (China); Liu, De-Song [Department of Pediatrics, Sichuan Provincial Hospital of Women and Children, Chengdu (China); Ge, Yan; Ni, Pei-Yan; Deng, Lin [State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu (China); Lu, You, E-mail: radyoulu@hotmail.com [State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu (China); Department of Thoracic Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu (China); Jiang, Wei, E-mail: wcumsjw72@hotmail.com [State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu (China); Molecular Medicine Research Center, West China Hospital, Sichuan University, Chengdu (China)

    2011-05-27

    Highlights: {yields} Lysophosphatidic acid (LPA) levels and its receptors LPAR1/3 transcripts were elevated during the development of radiation-induced lung fibrosis. {yields} Lung fibrosis was obviously alleviated in mice treated with the dual LPAR1/3 antagonist, VPC12249. {yields} VPC12249 administration effectively inhibited radiation-induced fibroblast accumulation in vivo, and suppressed LPA-induced fibroblast proliferation in vitro. {yields} LPA-LPAR1/3 signaling regulated TGF{beta}1 and CTGF expressions in radiation-challenged lungs, but only influenced CTGF expression in cultured fibroblasts. {yields} LPA-LPAR1/3 signaling induced fibroblast proliferation through a CTGF-dependent pathway, rather than through TGF{beta}1 activation. -- Abstract: Lung fibrosis is a common and serious complication of radiation therapy for lung cancer, for which there are no efficient treatments. Emerging evidence indicates that lysophosphatidic acid (LPA) and its receptors (LPARs) are involved in the pathogenesis of fibrosis. Here, we reported that thoracic radiation with 16 Gy in mice induced development of radiation lung fibrosis (RLF) accompanied by obvious increases in LPA release and LPAR1 and LPAR3 (LPAR1/3) transcripts. RLF was significantly alleviated in mice treated with the dual LPAR1/3 antagonist, VPC12249. VPC12249 administration effectively prolonged animal survival, restored lung structure, inhibited fibroblast accumulation and reduced collagen deposition. Moreover, profibrotic cytokines in radiation-challenged lungs obviously decreased following administration of VPC12249, including transforming growth factor {beta}1 (TGF{beta}1) and connective tissue growth factor (CTGF). In vitro, LPA induced both fibroblast proliferation and CTGF expression in a dose-dependent manner, and both were suppressed by blockade of LPAR1/3. The pro-proliferative activity of LPA on fibroblasts was inhibited by siRNA directed against CTGF. Together, our data suggest that the LPA-LPAR1

  12. Effects of Alpha-Lipoic Acid on Oxidative Stress and Kinin Receptor Expression in Obese Zucker Diabetic Fatty Rats

    Midaoui, Adil El; Talbot, Sébastien; Lahjouji, Karim; Dias, Jenny Pena; Fantus, I. George; Couture, Réjean

    2015-01-01

    Objective To investigate the impact of alpha-lipoic acid on superoxide anion production and NADPH oxidase activity as well as on the expression of kinin B1 and B2 receptors in key organs of obese Zucker Diabetic Fatty rats. Methods Superoxide anion production was measured by lucigenin chemiluminescence. Kinin B1 and B2 receptors expression was measured at protein and mRNA levels by western blot and qRT-PCR in key organs of Zucker Diabetic Fatty and Zucker lean control rats treated for a perio...

  13. Constitutive androstane receptor-mediated changes in bile acid composition contributes to hepatoprotection from lithocholic acid-induced liver injury in mice.

    Beilke, Lisa D; Aleksunes, Lauren M; Holland, Ricky D; Besselsen, David G; Beger, Rick D; Klaassen, Curtis D; Cherrington, Nathan J

    2009-05-01

    Pharmacological activation of the constitutive androstane receptor (CAR) protects the liver during cholestasis. The current study evaluates how activation of CAR influences genes involved in bile acid biosynthesis as a mechanism of hepatoprotection during bile acid-induced liver injury. CAR activators phenobarbital (PB) and 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) or corn oil (CO) were administered to C57BL/6 wild-type (WT) and CAR knockout (CAR-null) mice before and during induction of intrahepatic cholestasis using the secondary bile acid, lithocholic acid (LCA). In LCA-treated WT and all the CAR-null groups (excluding controls), histology revealed severe multifocal necrosis. This pathology was absent in WT mice pretreated with PB and TCPOBOP, indicating CAR-dependent hepatoprotection. Decreases in total hepatic bile acids and hepatic monohydroxy, dihydroxy, and trihydroxy bile acids in PB- and TCPOBOP-pretreated WT mice correlated with hepatoprotection. In comparison, concentrations of monohydroxylated and dihydroxylated bile acids were increased in all the treated CAR-null mice compared with CO controls. Along with several other enzymes (Cyp7b1, Cyp27a1, Cyp39a1), Cyp8b1 expression was increased in hepatoprotected mice, which could be suggestive of a shift in the bile acid biosynthesis pathway toward the formation of less toxic bile acids. In CAR-null mice, these changes in gene expression were not different among treatment groups. These results suggest CAR mediates a shift in bile acid biosynthesis toward the formation of less toxic bile acids, as well as a decrease in hepatic bile acid concentrations. We propose that these combined CAR-mediated effects may contribute to the hepatoprotection observed during LCA-induced liver injury. PMID:19196849

  14. Dietary hyodeoxycholic acid exerts hypolipidemic effects by reducing farnesoid X receptor antagonist bile acids in mouse enterohepatic tissues.

    Watanabe, Shiro; Fujita, Kyosuke

    2014-10-01

    Mice were fed a control diet or a diet supplemented with hyodeoxycholic acid, the most abundant bile acid contained in pig bile, for 4 weeks, after which their serum and livers were collected. The contents of total fatty acids of serum and liver cholesteryl esters, and of liver triglycerides, were reduced following the administration of the hyodeoxycholic acid-supplemented diet, which was mainly due to the reductions in the contents of monounsaturated fatty acids. Free cholesterol contents in the serum and liver were not changed by hyodeoxycholic acid administration. Hyodeoxycholic acid administration reduced the gene expression levels of sterol regulatory element binding protein 1c, acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase-1. Hyodeoxycholic acid administration markedly changes the ratio of FXR-antagonist/FXR-agonist bile acids in the enterohepatic tissues of the mice (1.13 and 7.60 in hyodeoxycholic acid and control diet groups, respectively). Our findings demonstrate that hyodeoxycholic acid administration exerts the hypolipidemic effect in mice, in which downregulations of de novo lipogenesis and desaturation of saturated fatty acids are suggested to play important roles. In addition, regulation of FXR activation through the selective modification of the enterohepatic bile acid pool may be involved in the hypolipidemic effect of hyodeoxycholic acid administration. PMID:25189147

  15. New ligands of the Cellular Retinoic Acid-Binding Protein 2 (CRABP2 suggest a role for this protein in chromatin remodeling

    Daniella de Barros Rossetto

    2014-08-01

    Full Text Available Retinoic acid (RA regulates the transcription of a series of genes involved in cell proliferation, differentiation and apoptosis by binding to the RA Receptor (RAR and Retinoid X Receptor (RXR heterodimers. The cellular retinoic acid-binding protein 2 (CRABP2 is involved in the transport of RA from the cytosol to specific RA receptors in the nucleus, acting as a coactivator of nuclear retinoid receptors. In order to have a better understanding of the role of CRABP2 in RA signaling, we used the yeast two-hybrid system as a tool for the identification of physical protein-protein interactions. Twenty-three putative CRABP2-interacting proteins were identified by screening in the presence of RA, five of which are related to transcription regulation or, more specifically, to the process of chromatin remodeling: t-complex 1 (TCP1; H3 histone, family 3A (H3F3A; H3 histone, family 3B (H3F3B; β-tubulin (TUBB and SR-related CTD-associated factor 1 (SCAF1. These results suggest a more direct role for CRABP2 in chromatin remodeling and may be a starting point for the elucidation of the fine-tuning control of transcription by RA receptors.

  16. Characterizing pharmacological ligands to study the long-chain fatty acid receptors GPR40/FFA1 and GPR120/FFA4.

    Milligan, G; Alvarez-Curto, E; Watterson, K R; Ulven, T; Hudson, B D

    2015-07-01

    The free fatty acid receptors (FFA) 1 (previously designated GPR40) and FFA4 (previously GPR120) are two GPCRs activated by saturated and unsaturated longer-chain free fatty acids. With expression patterns and functions anticipated to directly or indirectly promote insulin secretion, provide homeostatic control of blood glucose and improve tissue insulin sensitivity, both receptors are being studied as potential therapeutic targets for the control of type 2 diabetes. Furthermore, genetic and systems biology studies in both humans and mouse models link FFA4 receptors to diabetes and obesity. Although activated by the same group of free fatty acids, FFA1 and FFA4 receptors are not closely related and, while the basis of recognition of fatty acids by FFA1 receptors is similar to that of the short-chain fatty acid receptors FFA2 and FFA3, the amino acid residues involved in endogenous ligand recognition by FFA4 receptors are more akin to those of the sphingosine 1 phosphate receptor S1P1 . Screening and subsequent medicinal chemistry programmes have developed a number of FFA1 receptor selective agonists that are effective in promoting insulin secretion in a glucose concentration-dependent manner, and in lowering blood glucose levels. However, the recent termination of Phase III clinical trials employing TAK-875/fasiglifam has caused a setback and raises important questions over the exact nature and mechanistic causes of the problems. Progress in the identification and development of highly FFA4 receptor-selective pharmacological tools has been less rapid and several issues remain to be clarified to fully validate this receptor as a therapeutic target. Despite this, the ongoing development of a range of novel ligands offers great opportunities to further unravel the contributions of these receptors. PMID:25131623

  17. Excitatory amino acid neurotoxicity and modulation of glutamate receptor expression in organotypic brain slice cultures

    Zimmer, J; Kristensen, Bjarne Winther; Jakobsen, B; Noraberg, J

    2000-01-01

    -induced excitotoxicity and KA-glutamate receptor subunit mRNA expression after long-term exposure to low, non-toxic doses of KA and NBQX. We conclude that organotypic brain slice cultures, combined with standardized procedures for quantitation of cell damage and receptor subunit changes is of great potential use for...... studies of excitotoxic, glutamate receptor-induced neuronal cell death, receptor modulation and related neuroprotection....

  18. Optical spectroscopic approach as a rapid tool to characterize the interactions of retinoids with human nuclear receptors

    Morjani, Hamid; Sockalingum, Ganesh D.; Beljebbar, Abdelilah; Manfait, Michel

    1998-04-01

    Retinoids are potent molecules that can affect a variety of fundamental biological processes including cell differentiation and proliferation and apoptosis. These molecules elicit their biological effects by activating a family of nuclear receptors which act as ligand-inducible transcription factors belonging to the steroid/thyroid receptor superfamily. Retinoic acid receptors form heterodimers in which response to ligand binding, both partners contribute to transactivation and/or DNA binding in vivo. Surface-enhanced Raman scattering (SERS), Fourier transform-SERS (FT-SERS), fluorescence and circular dichroism are proposed to rapidly give information on the interaction of the different RARs and RXRs with their specific ligands at physiological concentrations. FT-SERS data reveal a significant attenuation in intensity of the bands originating from the retinoic polyenic chain upon complexation. The spectrum is dominantly of the (Beta) - ionone ring. Fluorescence measurements supported the hydrophobic character of the ligand binding pocket and the circular dichroic data indicate that the protein helices extend upon ligand binding. These novel spectroscopic information are fully consistent with published x-ray crystallographic results and suggest that these techniques may be valuable additional tools to characterize the interactions of agonists and antagonists with residues of the ligand binding pocket retinoid receptor homo- and hetero-dimers.

  19. Involvement of the G-protein-coupled receptor 4 in RANKL expression by osteoblasts in an acidic environment.

    Okito, Asuka; Nakahama, Ken-Ichi; Akiyama, Masako; Ono, Takashi; Morita, Ikuo

    2015-03-01

    Osteoclast activity is enhanced in acidic environments following systemic or local inflammation. However, the regulatory mechanism of receptor activator of NF-κB ligand (RANKL) expression in osteoblasts under acidic conditions is not fully understood. In the present paper, we detected the mRNA expression of the G-protein-coupled receptor (GPR) proton sensors GPR4 and GPR65 (T-cell death-associated gene 8, TDAG8), in osteoblasts. RANKL expression and the cyclic AMP (cAMP) level in osteoblasts were up-regulated under acidic culture conditions. Acidosis-induced up-regulation of RANKL was abolished by the protein kinase A inhibitor H89. To clarify the role of GPR4 in RANKL expression, GPR4 gain and loss of function experiments were performed. Gene knockdown and forced expression of GPR4 caused reduction and induction of RANKL expression, respectively. These results suggested that, at least in part, RANKL expression by osteoblasts in an acidic environment was mediated by cAMP/PKA signaling resulting from GPR4 activation. A comprehensive microarray analysis of gene expression of osteoblasts revealed that, under acidic conditions, the phenotype of osteoblasts was that of an osteoclast supporting cell rather than that of a mineralizing cell. These findings will contribute to a molecular understanding of bone disruption in an acidic environment. PMID:25668130

  20. NR4A nuclear receptors mediate carnitine palmitoyltransferase 1A gene expression by the rexinoid HX600.

    Ishizawa, Michiyasu; Kagechika, Hiroyuki; Makishima, Makoto

    2012-02-24

    Retinoid X receptors (RXRs) are members of the nuclear receptor superfamily and can be activated by 9-cis retinoic acid (9CRA). RXRs form homodimers and heterodimers with other nuclear receptors such as the retinoic acid receptor and NR4 subfamily nuclear receptors, Nur77 and NURR1. Potential physiological roles of the Nur77-RXR and NURR1-RXR heterodimers have not been elucidated. In this study, we identified a gene regulated by these heterodimers utilizing HX600, a selective RXR agonist for Nur77-RXR and NURR1-RXR. While 9CRA induced many genes, including RAR-target genes, HX600 effectively induced only carnitine palmitoyltransferase 1A (CPT1A) in human teratocarcinoma NT2/D1 cells, which express RXRα, Nur77 and NURR1. HX600 also increased CPT1A expression in human embryonic kidney (HEK) 293 cells and hepatocyte-derived HepG2 cells. Although HX600 induced CPT1A less effectively than 9CRA, overexpression of Nur77 or NURR1 increased the HX600 response to levels similar to 9CRA in NT2/D1 and HEK293 cells. A dominant-negative form of Nur77 or NURR1 repressed the induction of CPT1A by HX600. A protein synthesis inhibitor did not alter HX600-dependent CPT1A induction. Thus, the rexinoid HX600 directly induces expression of CPT1A through a Nur77 or NURR1-mediated mechanism. CPT1A, a gene involved in fatty acid β-oxidation, could be a target of RXR-NR4 receptor heterodimers. PMID:22310716

  1. Benefits of short-chain fatty acids and their receptors in inflammation and carcinogenesis.

    Sivaprakasam, Sathish; Prasad, Puttur D; Singh, Nagendra

    2016-08-01

    Epidemiological studies have linked increased incidence of inflammatory diseases and intestinal cancers in the developed parts of the world to the consumption of diets poor in dietary fibers and rich in refined carbohydrates. Gut bacteria residing in the intestinal lumen exclusively metabolize dietary fibers. Butyrate, propionate and acetate, which are collectively called short-chain fatty acids (SCFAs), are generated by fermentation of dietary fibers by gut microbiota. Evidences indicate that SCFAs are key players in regulating beneficial effect of dietary fibers and gut microbiota on our health. SCFAs interact with metabolite-sensing G protein-coupled receptors GPR41, GPR43 and GPR109A expressed in gut epithelium and immune cells. These interactions induce mechanisms that play a key role in maintaining homeostasis in gut and other organs. This review summarizes the protective roles of GPR41, GPR43 and GPR109A in dietary fibers-, gut microbiota- and SCFAs-mediated suppression of inflammation and carcinogenesis in gut and other organs. PMID:27113407

  2. The ionotropic γ-aminobutyric acid receptor gene family of the silkworm, Bombyx mori.

    Yu, Lin-Lin; Cui, Ying-Jun; Lang, Guo-Jun; Zhang, Ming-Yan; Zhang, Chuan-Xi

    2010-09-01

    γ-Aminobutyric acid (GABA) is a very important inhibitory neurotransmitter in both vertebrate and invertebrate nervous systems. GABA receptors (GABARs) are known to be the molecular targets of a class of insecticides. Members of the GABAR gene family of the silkworm, Bombyx mori, a model insect of Lepidoptera, have been identified and characterized in this study. All putative silkworm GABAR cDNAs were cloned using the reverse transcriptase polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). Bombyx mori appears to have the largest insect GABAR gene family known to date, including three RDL, one LCCH3, and one GRD subunit. The silkworm RDL1 gene has RNA-editing sites, and the RDL1 and RDL3 genes possess alternative splicing. These mRNA modifications enhance the diversity of the silkworm's GABAR gene family. In addition, truncated transcripts were found for the RDL1 and LCCH3 genes. In particular, the three RDL subunits may have arisen from two duplication events. PMID:20924418

  3. The Arabidopsis Vacuolar Sorting Receptor1 Is Required for Osmotic Stress-Induced Abscisic Acid Biosynthesis

    Wang, Zhen-Yu

    2014-11-21

    Osmotic stress activates the biosynthesis of the phytohormone abscisic acid (ABA) through a pathway that is rate limited by the carotenoid cleavage enzyme 9-cis-epoxycarotenoid dioxygenase (NCED). To understand the signal transduction mechanism underlying the activation of ABA biosynthesis, we performed a forward genetic screen to isolate mutants defective in osmotic stress regulation of the NCED3 gene. Here, we identified the Arabidopsis (Arabidopsis thaliana) Vacuolar Sorting Receptor1 (VSR1) as a unique regulator of ABA biosynthesis. The vsr1 mutant not only shows increased sensitivity to osmotic stress, but also is defective in the feedback regulation of ABA biosynthesis by ABA. Further analysis revealed that vacuolar trafficking mediated by VSR1 is required for osmotic stress-responsive ABA biosynthesis and osmotic stress tolerance. Moreover, under osmotic stress conditions, the membrane potential, calcium flux, and vacuolar pH changes in the vsr1 mutant differ from those in the wild type. Given that manipulation of the intracellular pH is sufficient to modulate the expression of ABA biosynthesis genes, including NCED3, and ABA accumulation, we propose that intracellular pH changes caused by osmotic stress may play a signaling role in regulating ABA biosynthesis and that this regulation is dependent on functional VSR1.

  4. Effects of Rhizoma Acori Tatarinowii extracts on gamma-aminobutyric acid type A receptor alpha 1 subunit brain expression during development in a recurrent seizure rat model

    Liqun Liu; Ding'an Mao; Keqiang Chi; Xingfang Li; Tao Bo; Jinming Guo; Zhuwen Yi

    2011-01-01

    Extracts from Rhizoma Acori Tatarinowii (Grassleaf Sweetflag Rhizome, Shichangpu) have been shown to improve learning and memory, reduce anxiety, allay excitement, and suppress seizures. Rhizoma Acori Tatarinowii extracts interact with γ-aminobutyric acid and activate the γ-aminobutyric acid type A receptor, although few studies have addressed the precise effects of γ-aminobutyric acid type A receptor α1 subunit. In the present study, γ-aminobutyric acid type A receptor α1 subunit protein expression in the cerebral cortex and hippocampus, and pathological scores of brain injury, were significantly greater following recurrent seizures, but significantly decreased following treatment with Rhizoma Acori Tatarinowii extracts. These results indicated that Rhizoma Acori Tatarinowii extracts down-regulated γ-aminobutyric acid type A receptor α1 subunit protein expression in the cerebral cortex and hippocampus and protected seizure-induced brain injury during development.

  5. The Nuclear Transcription Factor RAR Associates with Neuronal RNA Granules and Suppresses Translation

    All-trans-retinoic acid stimulates dendritic growth in hippocampal neurons within minutes by activating mitogen-activated protein kinase and mTOR and increasing dendritic translation of calcium calmodulin-dependent protein kinase II alpha and the alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionat...

  6. Characterising pharmacological ligands to study the long chain fatty acid receptors GPR40/FFA1 and GPR120/FFA4

    Milligan, G; Alvarez-Curto, E; Watterson, K R;

    2015-01-01

    control of blood glucose and improve tissue insulin sensitivity, both receptors are being studied as potential therapeutic targets for the control of type II diabetes. Furthermore, genetic and systems biology studies in both humans and mouse models link FFA4 to diabetes and obesity. Although activated by......The G protein-coupled receptors FFA1 (previously designated GPR40) and FFA4 (previously GPR120) are both activated by saturated and unsaturated longer-chain free fatty acids. With expression patterns and functions anticipated to directly or indirectly promote insulin secretion, provide homeostatic...... the sphingosine 1 phosphate receptor S1P1 . Screening and subsequent medicinal chemistry programmes have developed a number of FFA1 selective agonists that are effective in promoting insulin secretion in a glucose concentration-dependent manner, and in lowering blood glucose levels. However, the...

  7. Receptor research on xenohormone effects of human serum extracts containing the actual mixture of perfluorinated alkyl acids: a short review

    Bjerregaard-Olesen, Christian; Bonefeld-Jørgensen, Eva Cecilie

    2015-01-01

    Perfluorinated alkyl acids (PFAAs) are used in many household products including food contact materials. Hence, humans are continuously exposed, and the PFAAs are accumulated in human serum with half-lives up to 8.8 years. In humans, high PFAA serum levels have been associated with an increased...... risk of breast cancer and other adverse health effects such as lower birth weight and longer time to pregnancy which might be related to disruptions of various hormonal systems. For instance, direct cell exposure studies in vitro suggest that some PFAAs can transactivate the estrogen receptor (ER......), antagonize the androgen receptor (AR) and has the potential to interfere with Thyroid Hormone and Aryl-hydrocarbon Receptor functions. Moreover, the PFAAs also showed cellular oxidative stress potential. Humans are exposed to an array of PFAAs, and the quantity and combination of these PFAAs in human serum...

  8. Selective orthosteric free fatty acid receptor 2 (FFA2) agonists: identification of the structural and chemical requirements for selective activation of FFA2 versus FFA3

    Schmidt, Johannes; Smith, Nicola J; Christiansen, Elisabeth; Tikhonova, Irina G; Grundmann, Manuel; Hudson, Brian D; Ward, Richard J; Drewke, Christel; Milligan, Graeme; Kostenis, Evi; Ulven, Trond

    2011-01-01

    Free fatty acid receptor 2 (FFA2, GPR43) is a G protein-coupled 7-transmembrane receptor for short chain fatty acids (SCFAs) that is implicated in inflammatory and metabolic disorders. The SCFA propionate has close to optimal ligand efficiency for FFA2, and can hence be considered as highly potent...... given its size. Propionate, however, does not discriminate between FFA2 and the closely related receptor FFA3 (GPR41). To identify FFA2 selective ligands and understand the molecular basis for FFA2 selectivity, a targeted library of small carboxylic acids (SCAs) was examined using holistic, label...

  9. ZAPA, (Z)-3-[(aminoiminomethyl)thio]-2-propenoic acid hydrochloride, a potent agonist at GABA-receptors on the Ascaris muscle cell.

    Holden-Dye, L.; Walker, R. J.

    1988-01-01

    This study is the first report of a compound which is equal in efficacy to gamma-aminobutyric acid (GABA) at the nematode Ascaris muscle GABA-receptor. The GABA-receptor at the Ascaris muscle cell which mediates a membrane hyperpolarization and muscle relaxation has eluded classification. The structure-activity profile of this receptor is not typical of GABAA or GABAB-receptors. Here we report that the isothiouronium compound ZAPA is as potent as GABA at this receptor. This finding has import...

  10. Expression of lysophosphatidic acid and its receptor in human pancreatic cancer and its clinical evaluation of diagnosis and therapy

    WANG Shao-kai; TAO Chen-jie; WANG Wei-dong; L(U)Guang-mei; GONG Yong-ling

    2011-01-01

    Lysophosphatidic acid(LPA) is a naturally occurring phospholipid with diverse effects in various cells, ranging from immediate morphological alteration to long lasting cellular function changes, such as induction of stimulation of cell proliferation, survival, drug resistance and motility. Like many other biomediators, LPA interacts with cells through specific cell surface receptors(G protein-coupled receptors). LPA1/Edg-2,LPA2/Edg-4 and LPA3/Edg-7, named as Edg/LP subfamily, are the three most common lysophosphatidic acid receptors. LPA plays a critical role as a general growth, survival and pro-angiogenic factor in the regulation of pathophysiological processes in vivo and in vitro. Recent literatures suggest that abnormalities in LPA metabolism and function in pancreatic cancer patients may contribute to the initiation and progression of the disease. Thus, LPA might be a potential target for clinical pancreatic cancer diagnosis and therapy. Herein we review the expression of LPA and its receptors in the carcinogenesis of human malignancies, with focus on human pancreatic cancer, and also clinical diagnosis and treatment has been evaluated.

  11. Lithocholic acid down-regulation of NF-κB activity through vitamin D receptor in colonic cancer cells

    Sun, Jun; Mustafi, Reba; Cerda, Sonia; Chumsangsri, Anusara; Xia, Yinglin Rick; Li, Yan Chun; Bissonnette, Marc

    2008-01-01

    Lithocholic acid (LCA), a secondary bile acid, is a vitamin D receptor (VDR) ligand. 1,25-Dihydroxyvitamin D3 (1,25(OH)2D3), the hormonal form of vitamin D, is involved in the anti-inflammatory action through VDR. Therefore, we hypothesize that LCA acts like 1,25(OH)2D3 to drive anti-inflammatory signals. In present study, we used human colonic cancer cells to assess the role of LCA in regulation of the pro-inflammatory NF-κB pathway. We found that LCA treatment increased VDR levels, mimickin...

  12. 20-Hydroxyeicosatetraenoic Acid (20-HETE) Is a Novel Activator of Transient Receptor Potential Vanilloid 1 (TRPV1) Channel*

    Wen, Hairuo; Östman, Johan; Bubb, Kristen J; Panayiotou, Catherine; Priestley, John V; Baker, Mark D.; Ahluwalia, Amrita

    2012-01-01

    TRPV1 is a member of the transient receptor potential ion channel family and is gated by capsaicin, the pungent component of chili pepper. It is expressed predominantly in small diameter peripheral nerve fibers and is activated by noxious temperatures >42 °C. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a cytochrome P-450 4A/4F-derived metabolite of the membrane phospholipid arachidonic acid. It is a powerful vasoconstrictor and has structural similarities with other TRPV1 agonists, e.g. the ...

  13. Bile Acids Acutely Stimulate Insulin Secretion of Mouse β-Cells via Farnesoid X Receptor Activation and KATP Channel Inhibition

    Düfer, Martina; Hörth, Katrin; Wagner, Rebecca; Schittenhelm, Björn; Prowald, Susanne; Wagner, Thomas F. J.; Oberwinkler, Johannes; Lukowski, Robert; Gonzalez, Frank J.; Krippeit-Drews, Peter; Drews, Gisela

    2012-01-01

    Type 2 diabetes mellitus is associated with alterations in bile acid (BA) signaling. The aim of our study was to test whether pancreatic β-cells contribute to BA-dependent regulation of glucose homeostasis. Experiments were performed with islets from wild-type, farnesoid X receptor (FXR) knockout (KO), and β-cell ATP-dependent K+ (KATP) channel gene SUR1 (ABCC8) KO mice, respectively. Sodium taurochenodeoxycholate (TCDC) increased glucose-induced insulin secretion. This effect was mimicked by...

  14. Suppression of NMDA receptor function in mice prenatally exposed to valproic acid improves social deficits and repetitive behaviors

    Jaeseung eKang; Eunjoon eKim

    2015-01-01

    Animals prenatally exposed to valproic acid (VPA), an antiepileptic agent, have been used as a model for autism spectrum disorders (ASDs). Previous studies have identified enhanced NMDA receptor (NMDAR) function in the brain of VPA rats, and demonstrated that pharmacological suppression of NMDAR function normalizes social deficits in these animals. However, whether repetitive behavior, another key feature of ASDs, can be rescued by NMDAR inhibition remains unknown. We report here that memanti...

  15. Trans Fatty Acid Derived Phospholipids Show Increased Membrane Cholesterol and Reduced Receptor Activation as Compared to Their Cis Analogs

    Niu, Shui-Lin; Mitchell, Drake C.; Litman, Burton J.

    2005-01-01

    The consumption of trans fatty acid (TFA) is linked to the elevation of LDL cholesterol and is considered to be a major health risk factor for coronary heart disease. Despite several decades of extensive research on this subject, the underlying mechanism of how TFA modulates serum cholesterol levels remains elusive. In this study, we examined the molecular interaction of TFA-derived phospholipid with cholesterol and the membrane receptor rhodopsin in model membranes. Rhodopsin is a prototypic...

  16. Novel Inhibitory Effects of Glycyrrhizic Acid on the Accumulation of Advanced Glycation End Product and Its Receptor Expression

    Cheng, Hong Sheng; Kong, Joana Magdelene Xiao Fang; Ng, Athena Xin Hui; Chan, Weng Keong; Ton, So Ha; Abdul Kadir, Khalid

    2014-01-01

    Abstract Beneficial effects of glycyrrhizic acid (GA), a bioactive extract of licorice root, in the prevention of metabolic syndrome have been consistently reported while advanced glycation end products (AGE) and receptor for advanced glycation end product (RAGE) are the leading factors in the development of diabetes mellitus. The aim of this study was to investigate the effects of GA on the AGE-RAGE axis using high-fat/high-sucrose (HF/HS) diet-induced metabolic syndrome rat models. Twenty f...

  17. Synthesis of pregnane 3-carboxylic acids via Pd-catalyzed alkoxycarbonylation and their effect on NMDA receptor activity

    Šťastná, Eva; Chodounská, Hana; Pouzar, Vladimír; Borovská, Jiřina; Vyklický ml., Ladislav

    2011-01-01

    Roč. 76, č. 9 (2011), s. 1141-1161. ISSN 0010-0765 R&D Projects: GA ČR(CZ) GA203/08/1498; GA ČR(CZ) GA309/07/0271 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50110509 Keywords : neurosteroids * carboxylic acid * alkoxycarbonylation * steroids * NMDA receptor activity Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011

  18. Nicotinic acetylcholine receptor induces lateral segregation of phosphatidic acid and phosphatidylcholine in reconstituted membranes.

    Wenz, Jorge J; Barrantes, Francisco J

    2005-01-11

    Purified nicotinic acetylcholine receptor (AChR) protein was reconstituted into synthetic lipid membranes having known effects on receptor function in the presence and absence of cholesterol (Chol). The phase behavior of a lipid system (DPPC/DOPC) possessing a known lipid phase profile and favoring nonfunctional, desensitized AChR was compared with that of a lipid system (POPA/POPC) containing the anionic phospholipid phosphatidic acid (PA), which stabilizes the functional resting form of the AChR. Fluorescence quenching of diphenylhexatriene (DPH) extrinsic fluorescence and AChR intrinsic fluorescence by a nitroxide spin-labeled phospholipid showed that the AChR diminishes the degree of DPH quenching and promotes DPPC lateral segregation into an ordered lipid domain, an effect that was potentiated by Chol. Fluorescence anisotropy of the probe DPH increased in the presence of AChR or Chol and also made apparent shifts to higher values in the transition temperature of the lipid system in the presence of Chol and/or AChR. The values were highest when both Chol and AChR were present, further reinforcing the view that their effect on lipid segregation is additive. These results can be accounted for by the increase in the size of quencher-free, ordered lipid domains induced by AChR and/or Chol. Pyrene phosphatidylcholine (PyPC) excimer (E) formation was strongly reduced owing to the restricted diffusion of the probe induced by the AChR protein. The analysis of Forster energy transfer (FRET) from the protein to DPH further indicates that AChR partitions preferentially into these ordered lipid microdomains, enriched in saturated lipid (DPPC or POPA), which segregate from liquid phase-enriched DOPC or POPC domains. Taken together, the results suggest that the AChR organizes its immediate microenvironment in the form of microdomains with higher lateral packing density and rigidity. The relative size of such microdomains depends not only on the phospholipid polar headgroup

  19. Crystallization and preliminary X-ray diffraction studies of the abscisic acid receptor PYL3 and its complex with pyrabactin

    Crystals of the abscisic acid receptor PYL3 and of the PYL3–pyrabactin complex were obtained and optimized in order to obtain high-quality diffraction data. Diffraction data sets were collected and processed to 2.5 and 1.83 Å resolution, respectively. Abscisic acid (ABA) modulates many developmental processes and responses to environmental stress. Recently, a family of pyrabactin resistance-like proteins (PYLs) in Arabidopsis thaliana were identified to be abscisic acid receptors. Although the 14 PYLs members share a similar sequence identity, they exhibit different responses toward pyrabactin. Apo-PYL3 is a dimer; however, its oligomeric state changes greatly on the addition of pyrabactin. Moreover, pyrabactin binds dimeric PYL3 in a nonproductive mode which prevents receptor activation and inhibition of PP2Cs. Here, the expression, purification and crystallization of apo-PYL3 and of PYL3 complexed with pyrabactin are reported. Diffraction data were optimized to 2.5 Å resolution for apo-PYL3 and to 1.83 Å resolution for PYL3–pyrabactin. The crystals of apo-PYL3 and PYL3–pyrabactin belonged to space groups P41212 and P212121, respectively

  20. Adenosine-to-inosine RNA editing affects trafficking of the gamma-aminobutyric acid type A (GABA(A)) receptor.

    Daniel, Chammiran; Wahlstedt, Helene; Ohlson, Johan; Björk, Petra; Ohman, Marie

    2011-01-21

    Recoding by adenosine-to-inosine RNA editing plays an important role in diversifying proteins involved in neurotransmission. We have previously shown that the Gabra-3 transcript, coding for the α3 subunit of the GABA(A) receptor is edited in mouse, causing an isoleucine to methionine (I/M) change. Here we show that this editing event is evolutionarily conserved from human to chicken. Analyzing recombinant GABA(A) receptor subunits expressed in HEK293 cells, our results suggest that editing at the I/M site in α3 has functional consequences on receptor expression. We demonstrate that I/M editing reduces the cell surface and the total number of α3 subunits. The reduction in cell surface levels is independent of the subunit combination as it is observed for α3 in combination with either the β2 or the β3 subunit. Further, an amino acid substitution at the corresponding I/M site in the α1 subunit has a similar effect on cell surface presentation, indicating the importance of this site for receptor trafficking. We show that the I/M editing during brain development is inversely related to the α3 protein abundance. Our results suggest that editing controls trafficking of α3-containing receptors and may therefore facilitate the switch of subunit compositions during development as well as the subcellular distribution of α subunits in the adult brain. PMID:21030585

  1. Adenosine-to-Inosine RNA Editing Affects Trafficking of the γ-Aminobutyric Acid Type A (GABAA) Receptor*

    Daniel, Chammiran; Wahlstedt, Helene; Ohlson, Johan; Björk, Petra; Öhman, Marie

    2011-01-01

    Recoding by adenosine-to-inosine RNA editing plays an important role in diversifying proteins involved in neurotransmission. We have previously shown that the Gabra-3 transcript, coding for the α3 subunit of the GABAA receptor is edited in mouse, causing an isoleucine to methionine (I/M) change. Here we show that this editing event is evolutionarily conserved from human to chicken. Analyzing recombinant GABAA receptor subunits expressed in HEK293 cells, our results suggest that editing at the I/M site in α3 has functional consequences on receptor expression. We demonstrate that I/M editing reduces the cell surface and the total number of α3 subunits. The reduction in cell surface levels is independent of the subunit combination as it is observed for α3 in combination with either the β2 or the β3 subunit. Further, an amino acid substitution at the corresponding I/M site in the α1 subunit has a similar effect on cell surface presentation, indicating the importance of this site for receptor trafficking. We show that the I/M editing during brain development is inversely related to the α3 protein abundance. Our results suggest that editing controls trafficking of α3-containing receptors and may therefore facilitate the switch of subunit compositions during development as well as the subcellular distribution of α subunits in the adult brain. PMID:21030585

  2. Predictors of survival in refractory anemia with ring sideroblasts and thrombocytosis (RARS-T) and the role of next-generation sequencing.

    Patnaik, Mrinal M; Lasho, Terra L; Finke, Christy M; Hanson, Curtis A; King, Rebecca L; Ketterling, Rhett P; Gangat, Naseema; Tefferi, Ayalew

    2016-05-01

    Refractory anemia with ring sideroblasts and thrombocytosis (RARS-T) shares overlapping features of myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN). RARS-T is characterized by SF3B1 and JAK2 mutations and prognosis is considered to be better than MDS but not as good as MPN. The objective of the study was to identify predictors of survival in RARS-T. We analyzed clinical and laboratory variables in 82 patients and applied a 27-gene NGS assay to 48 marrow samples obtained at diagnosis. 94% of patients had ≥1 mutations; common mutations being: SF3B1 85%, JAK2V617F 33%, ASXL1 29%, DNMT3A 13%, SETBP1 13% and TET2 10%. In a multivariable survival analysis (n = 82), anemia (P = 0.02) [HBNGS information (n = 48), univariate analysis showed association between poor survival and presence of SETBP1 (P = 0.04) or ASXL1 (P = 0.08) mutations whereas the absence of these mutations (ASXL1wt/SETBP1wt) was favorable (P = 0.04); the number of concurrent mutations did not provide additional prognostication (P = 0.3). We developed a HR-weighted prognostic model, with 2 points for an abnormal karyotype, 1 point for either ASXL1 and/or SETBP1 mutations, and 1 point for a HB level < 10 gm/dl, which effectively stratified patients into three risk categories; low (0 points), intermediate (1 point) and high (≥2 points), with median survivals of 80, 42 and 11 months respectively (P = 0.01). In summary, we confirm the unique mutational landscape in RARS-T and provide a novel mutation-enhanced prognostic model. Am. J. Hematol. 91:492-498, 2016. © 2016 Wiley Periodicals, Inc. PMID:26874914

  3. Dual activation of the bile acid nuclear receptor FXR and G-protein-coupled receptor TGR5 protects mice against atherosclerosis.

    Shinobu Miyazaki-Anzai

    Full Text Available Bile acid signaling is a critical regulator of glucose and energy metabolism, mainly through the nuclear receptor FXR and the G protein-coupled receptor TGR. The purpose of the present study was to investigate whether dual activation of FXR and TGR5 plays a significant role in the prevention of atherosclerosis progression. To evaluate the effects of bile acid signaling in atherogenesis, ApoE-/- mice and LDLR-/- mice were treated with an FXR/TGR5 dual agonist (INT-767. INT-767 treatment drastically reduced serum cholesterol levels. INT-767 treatment significantly reduced atherosclerotic plaque formation in both ApoE-/- and LDLR-/- mice. INT-767 decreased the expression of pro-inflammatory cytokines and chemokines in the aortas of ApoE-/- mice through the inactivation of NF-κB. In addition, J774 macrophages treated with INT-767 had significantly lower levels of active NF-κB, resulting in cytokine production in response to LPS through a PKA dependent mechanism. This study demonstrates that concurrent activation of FXR and TGR5 attenuates atherosclerosis by reducing both circulating lipids and inflammation.

  4. Synthesis and Structure-Activity Relationships of Amino Acid Conjugates of Cholanic Acid as Antagonists of the EphA2 Receptor

    Alessio Lodola

    2013-10-01

    Full Text Available The Eph–ephrin system plays a critical role in tumor growth and vascular functions during carcinogenesis. We had previously identified cholanic acid as a competitive and reversible EphA2 antagonist able to disrupt EphA2-ephrinA1 interaction and to inhibit EphA2 activation in prostate cancer cells. Herein, we report the synthesis and biological evaluation of a set of cholanic acid derivatives obtained by conjugation of its carboxyl group with a panel of naturally occurring amino acids with the aim to improve EphA2 receptor inhibition. Structure-activity relationships indicate that conjugation of cholanic acid with linear amino acids of small size leads to effective EphA2 antagonists whereas the introduction of aromatic amino acids reduces the potency in displacement studies. The b-alanine derivative 4 was able to disrupt EphA2-ephrinA1 interaction in the micromolar range and to dose-dependently inhibit EphA2 activation on PC3 cells. These findings may help the design of novel EphA2 antagonists active on cancer cell lines.

  5. Nuclear hormone receptors involved in neoplasia: erb A exhibits a novel DNA sequence specificity determined by amino acids outside of the zinc-finger domain.

    Chen, H.; Smit-McBride, Z; Lewis, S; Sharif, M; Privalsky, M L

    1993-01-01

    The erb A oncogene is a dominant negative allele of a thyroid hormone receptor gene and acts in the cancer cell by encoding a transcriptional repressor. We demonstrate here that the DNA sequence recognition properties of the oncogenic form of the erb A protein are significantly altered from those of the normal thyroid hormone receptors and more closely resemble those of the retinoic acid receptors; this alteration appears to play an important role in defining the targets of erb A action in ne...

  6. receptores

    Salete Regina Daronco Benetti

    2006-01-01

    Full Text Available Se trata de un estudio etnográfico, que tuvo lo objetivo de interpretar el sistema de conocimiento y del significado atribuidos a la sangre referente a la transfusión sanguínea por los donadores y receptores de un banco de sangre. Para la colecta de las informaciones se observaron los participantes y la entrevista etnográfica se realizó el análisis de dominio, taxonómicos y temáticos. Los dominios culturales fueron: la sangre es vida: fuente de vida y alimento valioso; creencias religiosas: fuentes simbólicas de apoyos; donación sanguínea: un gesto colaborador que exige cuidarse, gratifica y trae felicidad; donación sanguínea: fuente simbólica de inseguridad; estar enfermo es una condición para realizar transfusión sanguínea; transfusión sanguínea: esperanza de vida; Creencias populares: transfusión sanguínea como riesgo para la salud; donadores de sangre: personas benditas; donar y recibir sangre: como significado de felicidad. Temática: “líquido precioso que origina, sostiene, modifica la vida, provoca miedo e inseguridad”.

  7. Multiple roles of the extracellular vestibule amino acid residues in the function of the rat P2X4 receptor.

    Milos B Rokic

    Full Text Available The binding of ATP to trimeric P2X receptors (P2XR causes an enlargement of the receptor extracellular vestibule, leading to opening of the cation-selective transmembrane pore, but specific roles of vestibule amino acid residues in receptor activation have not been evaluated systematically. In this study, alanine or cysteine scanning mutagenesis of V47-V61 and F324-N338 sequences of rat P2X4R revealed that V49, Y54, Q55, F324, and G325 mutants were poorly responsive to ATP and trafficking was only affected by the V49 mutation. The Y54F and Y54W mutations, but not the Y54L mutation, rescued receptor function, suggesting that an aromatic residue is important at this position. Furthermore, the Y54A and Y54C receptor function was partially rescued by ivermectin, a positive allosteric modulator of P2X4R, suggesting a rightward shift in the potency of ATP to activate P2X4R. The Q55T, Q55N, Q55E, and Q55K mutations resulted in non-responsive receptors and only the Q55E mutant was ivermectin-sensitive. The F324L, F324Y, and F324W mutations also rescued receptor function partially or completely, ivermectin action on channel gating was preserved in all mutants, and changes in ATP responsiveness correlated with the hydrophobicity and side chain volume of the substituent. The G325P mutant had a normal response to ATP, suggesting that G325 is a flexible hinge. A topological analysis revealed that the G325 and F324 residues disrupt a β-sheet upon ATP binding. These results indicate multiple roles of the extracellular vestibule amino acid residues in the P2X4R function: the V49 residue is important for receptor trafficking to plasma membrane, the Y54 and Q55 residues play a critical role in channel gating and the F324 and G325 residues are critical for vestibule widening.

  8. Involvement of the G-protein-coupled receptor 4 in RANKL expression by osteoblasts in an acidic environment

    Osteoclast activity is enhanced in acidic environments following systemic or local inflammation. However, the regulatory mechanism of receptor activator of NF-κB ligand (RANKL) expression in osteoblasts under acidic conditions is not fully understood. In the present paper, we detected the mRNA expression of the G-protein-coupled receptor (GPR) proton sensors GPR4 and GPR65 (T-cell death-associated gene 8, TDAG8), in osteoblasts. RANKL expression and the cyclic AMP (cAMP) level in osteoblasts were up-regulated under acidic culture conditions. Acidosis-induced up-regulation of RANKL was abolished by the protein kinase A inhibitor H89. To clarify the role of GPR4 in RANKL expression, GPR4 gain and loss of function experiments were performed. Gene knockdown and forced expression of GPR4 caused reduction and induction of RANKL expression, respectively. These results suggested that, at least in part, RANKL expression by osteoblasts in an acidic environment was mediated by cAMP/PKA signaling resulting from GPR4 activation. A comprehensive microarray analysis of gene expression of osteoblasts revealed that, under acidic conditions, the phenotype of osteoblasts was that of an osteoclast supporting cell rather than that of a mineralizing cell. These findings will contribute to a molecular understanding of bone disruption in an acidic environment. - Highlights: • RANKL expression was increased in osteoblasts under acidosis via cAMP/PKA pathway. • GRP4 knockdown resulted in decrease of RANKL expression. • GRP4 overexpression resulted in increase of RANKL expression. • Osteoblast mineralization was reduced under acidic condition

  9. Bile acids override steatosis in farnesoid X receptor deficient mice in a model of non-alcoholic steatohepatitis

    Wu, Weibin; Liu, Xijun; Peng, Xiaomin [Gene Research Center, Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Xue, Ruyi [Department of Gastroenterology and Hepatology, Zhongshan Hospital, Shanghai Institute of Liver Disease, Fudan University, Shanghai 200032 (China); Ji, Lingling [Gene Research Center, Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Shen, Xizhong [Department of Gastroenterology and Hepatology, Zhongshan Hospital, Shanghai Institute of Liver Disease, Fudan University, Shanghai 200032 (China); Chen, She, E-mail: shechen@fudan.edu.cn [Gene Research Center, Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Gu, Jianxin [Gene Research Center, Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Zhang, Si, E-mail: zhangsi@fudan.edu.cn [Gene Research Center, Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032 (China)

    2014-05-23

    Highlights: • FXR deficiency enhanced MCD diet-induced hepatic fibrosis. • FXR deficiency attenuated MCD diet-induced hepatic steatosis. • FXR deficiency repressed genes involved in fatty acid uptake and triglyceride accumulation. - Abstract: Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, and the pathogenesis is still not well known. The farnesoid X receptor (FXR) is a member of the nuclear hormone receptor superfamily and plays an essential role in maintaining bile acid and lipid homeostasis. In this study, we study the role of FXR in the pathogenesis of NFALD. We found that FXR deficient (FXR{sup −/−}) mice fed methionine- and choline-deficient (MCD) diet had higher serum ALT and AST activities and lower hepatic triglyceride levels than wild-type (WT) mice fed MCD diet. Expression of genes involved in inflammation (VCAM-1) and fibrosis (α-SMA) was increased in FXR{sup −/−} mice fed MCD diet (FXR{sup −/−}/MCD) compared to WT mice fed MCD diet (WT/MCD). Although MCD diet significantly induced hepatic fibrosis in terms of liver histology, FXR{sup −/−}/MCD mice showed less degree of hepatic steatosis than WT/MCD mice. Moreover, FXR deficiency synergistically potentiated the elevation effects of MCD diet on serum and hepatic bile acids levels. The super-physiological concentrations of hepatic bile acids in FXR{sup −/−}/MCD mice inhibited the expression of genes involved in fatty acid uptake and triglyceride accumulation, which may be an explanation for less steatosis in FXR{sup −/−}/MCD mice in contrast to WT/MCD mice. These results suggest that hepatic bile acids accumulation could override simple steatosis in hepatic injury during the progression of NAFLD and further emphasize the role of FXR in maintaining hepatic bile acid homeostasis in liver disorders and in hepatic protection.

  10. Involvement of the G-protein-coupled receptor 4 in RANKL expression by osteoblasts in an acidic environment

    Okito, Asuka [Department of Cellular Physiological Chemistry, Tokyo Medical and Dental University, Tokyo (Japan); Department of Orthodontic Science, Tokyo Medical and Dental University, Tokyo (Japan); Nakahama, Ken-ichi, E-mail: nakacell@tmd.ac.jp [Department of Cellular Physiological Chemistry, Tokyo Medical and Dental University, Tokyo (Japan); Akiyama, Masako [Department of Cellular Physiological Chemistry, Tokyo Medical and Dental University, Tokyo (Japan); Ono, Takashi [Department of Orthodontic Science, Tokyo Medical and Dental University, Tokyo (Japan); Morita, Ikuo [Department of Cellular Physiological Chemistry, Tokyo Medical and Dental University, Tokyo (Japan)

    2015-03-06

    Osteoclast activity is enhanced in acidic environments following systemic or local inflammation. However, the regulatory mechanism of receptor activator of NF-κB ligand (RANKL) expression in osteoblasts under acidic conditions is not fully understood. In the present paper, we detected the mRNA expression of the G-protein-coupled receptor (GPR) proton sensors GPR4 and GPR65 (T-cell death-associated gene 8, TDAG8), in osteoblasts. RANKL expression and the cyclic AMP (cAMP) level in osteoblasts were up-regulated under acidic culture conditions. Acidosis-induced up-regulation of RANKL was abolished by the protein kinase A inhibitor H89. To clarify the role of GPR4 in RANKL expression, GPR4 gain and loss of function experiments were performed. Gene knockdown and forced expression of GPR4 caused reduction and induction of RANKL expression, respectively. These results suggested that, at least in part, RANKL expression by osteoblasts in an acidic environment was mediated by cAMP/PKA signaling resulting from GPR4 activation. A comprehensive microarray analysis of gene expression of osteoblasts revealed that, under acidic conditions, the phenotype of osteoblasts was that of an osteoclast supporting cell rather than that of a mineralizing cell. These findings will contribute to a molecular understanding of bone disruption in an acidic environment. - Highlights: • RANKL expression was increased in osteoblasts under acidosis via cAMP/PKA pathway. • GRP4 knockdown resulted in decrease of RANKL expression. • GRP4 overexpression resulted in increase of RANKL expression. • Osteoblast mineralization was reduced under acidic condition.

  11. Bile acids override steatosis in farnesoid X receptor deficient mice in a model of non-alcoholic steatohepatitis

    Highlights: • FXR deficiency enhanced MCD diet-induced hepatic fibrosis. • FXR deficiency attenuated MCD diet-induced hepatic steatosis. • FXR deficiency repressed genes involved in fatty acid uptake and triglyceride accumulation. - Abstract: Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, and the pathogenesis is still not well known. The farnesoid X receptor (FXR) is a member of the nuclear hormone receptor superfamily and plays an essential role in maintaining bile acid and lipid homeostasis. In this study, we study the role of FXR in the pathogenesis of NFALD. We found that FXR deficient (FXR−/−) mice fed methionine- and choline-deficient (MCD) diet had higher serum ALT and AST activities and lower hepatic triglyceride levels than wild-type (WT) mice fed MCD diet. Expression of genes involved in inflammation (VCAM-1) and fibrosis (α-SMA) was increased in FXR−/− mice fed MCD diet (FXR−/−/MCD) compared to WT mice fed MCD diet (WT/MCD). Although MCD diet significantly induced hepatic fibrosis in terms of liver histology, FXR−/−/MCD mice showed less degree of hepatic steatosis than WT/MCD mice. Moreover, FXR deficiency synergistically potentiated the elevation effects of MCD diet on serum and hepatic bile acids levels. The super-physiological concentrations of hepatic bile acids in FXR−/−/MCD mice inhibited the expression of genes involved in fatty acid uptake and triglyceride accumulation, which may be an explanation for less steatosis in FXR−/−/MCD mice in contrast to WT/MCD mice. These results suggest that hepatic bile acids accumulation could override simple steatosis in hepatic injury during the progression of NAFLD and further emphasize the role of FXR in maintaining hepatic bile acid homeostasis in liver disorders and in hepatic protection

  12. Discovery of a New Class of Ionotropic Glutamate Receptor Antagonists by the Rational Design of (2S,3R)-3-(3-Carboxyphenyl)-pyrrolidine-2-carboxylic Acid

    Larsen, Ann Møller; Venskutonyte, Raminta; Valadés, Elena Antón;

    2011-01-01

    The kainic acid (KA) receptors belong to the class of glutamate (Glu) receptors in the brain and constitute a promising target for the treatment of neurological and/ or psychiatric diseases such as schizophrenia, major depression, and epilepsy. Five KA subtypes have been identified and named GluK1...

  13. Inhibitory effects of omega-3 fatty acids on injury-induced epidermal growth factor receptor transactivation contribute to delayed wound healing

    Turk, Harmony F.; Monk, Jennifer M.; Fan, Yang-Yi; Callaway, Evelyn S.; Weeks, Brad; Chapkin, Robert S.

    2013-01-01

    Epidermal growth factor receptor (EGFR)-mediated signaling is required for optimal intestinal wound healing. Since n-3 polyunsaturated fatty acids (PUFA), specifically docosahexaenoic acid (DHA), alter EGFR signaling and suppress downstream activation of key signaling pathways, we hypothesized that DHA would be detrimental to the process of intestinal wound healing. Using a mouse immortalized colonocyte model, DHA uniquely reduced EGFR ligand-induced receptor activation, whereas DHA and its m...

  14. Differential regulation of bile acid and cholesterol metabolism by the farnesoid X receptor in Ldlr −/− mice versus hamsters[S

    Gardès, Christophe; Chaput, Evelyne; Staempfli, Andreas; Blum, Denise; Richter, Hans; Benson, G. Martin

    2013-01-01

    Modulating bile acid synthesis has long been considered a good strategy by which to improve cholesterol homeostasis in humans. The farnesoid X receptor (FXR), the key regulator of bile acid synthesis, was, therefore, identified as an interesting target for drug discovery. We compared the effect of four, structurally unrelated, synthetic FXR agonists in two fat-fed rodent species and observed that the three most potent and selective agonists decreased plasma cholesterol in LDL receptor-deficie...

  15. Activation of γ-aminobutyric Acid (A) Receptor Protects Hippocampus from Intense Exercise-induced Synapses Damage and Apoptosis in Rats

    Yi Ding; Lan Xie; Cun-Qing Chang; Zhi-Min Chen; Hua Ai

    2015-01-01

    Background: Our previous study has confirmed that one bout of exhaustion (Ex) can cause hippocampus neurocyte damage, excessive apoptosis, and dysfunction. Its initial reason is intracellular calcium overload in hippocampus triggered by N-methyl-D-aspartic acid receptor (NMDAR) over-activation. NMDAR activation can be suppressed by γ-aminobutyric acid (A) receptor (GABAAR). Whether GABAAR can prevent intense exercise-induced hippocampus apoptosis, damage, or dysfunction will be studied in thi...

  16. Receptor binding proteins of Listeria monocytogenes bacteriophages A118 and P35 recognize serovar-specific teichoic acids

    Adsorption of a bacteriophage to the host requires recognition of a cell wall-associated receptor by a receptor binding protein (RBP). This recognition is specific, and high affinity binding is essential for efficient virus attachment. The molecular details of phage adsorption to the Gram-positive cell are poorly understood. We present the first description of receptor binding proteins and a tail tip structure for the siphovirus group infecting Listeria monocytogenes. The host-range determining factors in two phages, A118 and P35 specific for L. monocytogenes serovar 1/2 have been determined. Two proteins were identified as RBPs in phage A118. Rhamnose residues in wall teichoic acids represent the binding ligands for both proteins. In phage P35, protein gp16 could be identified as RBP and the role of both rhamnose and N-acetylglucosamine in phage adsorption was confirmed. Immunogold-labeling and transmission electron microscopy allowed the creation of a topological model of the A118 phage tail. - Highlights: • We present the first description of receptor binding proteins and a tail tip structure for the Siphovirus group infecting Listeria monocytogenes. • The host-range determining factors in two phages, A118 and P35 specific for L. monocytogenes serovar 1/2 have been determined. • Rhamnose residues in wall teichoic acids represent the binding ligands for both receptor binding proteins in phage A118. • Rhamnose and N-acetylglucosamine are required for adsorption of phage P35. • We preset a topological model of the A118 phage tail

  17. Receptor binding proteins of Listeria monocytogenes bacteriophages A118 and P35 recognize serovar-specific teichoic acids

    Bielmann, Regula; Habann, Matthias; Eugster, Marcel R. [Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich (Switzerland); Lurz, Rudi [Max-Planck Institute for Molecular Genetics, 14195 Berlin (Germany); Calendar, Richard [Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202 (United States); Klumpp, Jochen, E-mail: jochen.klumpp@hest.ethz.ch [Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich (Switzerland); Loessner, Martin J. [Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich (Switzerland)

    2015-03-15

    Adsorption of a bacteriophage to the host requires recognition of a cell wall-associated receptor by a receptor binding protein (RBP). This recognition is specific, and high affinity binding is essential for efficient virus attachment. The molecular details of phage adsorption to the Gram-positive cell are poorly understood. We present the first description of receptor binding proteins and a tail tip structure for the siphovirus group infecting Listeria monocytogenes. The host-range determining factors in two phages, A118 and P35 specific for L. monocytogenes serovar 1/2 have been determined. Two proteins were identified as RBPs in phage A118. Rhamnose residues in wall teichoic acids represent the binding ligands for both proteins. In phage P35, protein gp16 could be identified as RBP and the role of both rhamnose and N-acetylglucosamine in phage adsorption was confirmed. Immunogold-labeling and transmission electron microscopy allowed the creation of a topological model of the A118 phage tail. - Highlights: • We present the first description of receptor binding proteins and a tail tip structure for the Siphovirus group infecting Listeria monocytogenes. • The host-range determining factors in two phages, A118 and P35 specific for L. monocytogenes serovar 1/2 have been determined. • Rhamnose residues in wall teichoic acids represent the binding ligands for both receptor binding proteins in phage A118. • Rhamnose and N-acetylglucosamine are required for adsorption of phage P35. • We preset a topological model of the A118 phage tail.

  18. Glucuronic acid and the ethanol metabolite ethyl-glucuronide cause toll-like receptor 4 activation and enhanced pain.

    Lewis, Susannah S; Hutchinson, Mark R; Zhang, Yingning; Hund, Dana K; Maier, Steven F; Rice, Kenner C; Watkins, Linda R

    2013-05-01

    We have previously observed that the non-opioid morphine metabolite, morphine-3-glucuronide, enhances pain via a toll-like receptor 4 (TLR4) dependent mechanism. The present studies were undertaken to determine whether TLR4-dependent pain enhancement generalizes to other classes of glucuronide metabolites. In silico modeling predicted that glucuronic acid alone and ethyl glucuronide, a minor but long-lasting ethanol metabolite, would dock to the same MD-2 portion of the TLR4 receptor complex previously characterized as the docking site for morphine-3-glucuronide. Glucuronic acid, ethyl glucuronide and ethanol all caused an increase in TLR4-dependent reporter protein expression in a cell line transfected with TLR4 and associated co-signaling molecules. Glucuronic acid-, ethyl glucuronide-, and ethanol-induced increases in TLR4 signaling were blocked by the TLR4 antagonists LPS-RS and (+)-naloxone. Glucuronic acid and ethyl glucuronide both caused allodynia following intrathecal injection in rats, which was blocked by intrathecal co-administration of the TLR4 antagonist LPS-RS. The finding that ethyl glucuronide can cause TLR4-dependent pain could have implications for human conditions such as hangover headache and alcohol withdrawal hyperalgesia, as well as suggesting that other classes of glucuronide metabolites could have similar effects. PMID:23348028

  19. Optimization of time-resolved fluorescence assay for detection of europium-tetraazacyclododecyltetraacetic acid-labeled ligand-receptor interactions.

    De Silva, Channa R; Vagner, Josef; Lynch, Ronald; Gillies, Robert J; Hruby, Victor J

    2010-03-01

    Lanthanide-based luminescent ligand binding assays are superior to traditional radiolabel assays due to improving sensitivity and affordability in high-throughput screening while eliminating the use of radioactivity. Despite significant progress using lanthanide(III)-coordinated chelators such as diethylenetriaminepentaacetic acid (DTPA) derivatives, dissociation-enhanced lanthanide fluoroimmunoassays (DELFIAs) have not yet been successfully used with more stable chelators (e.g., tetraazacyclododecyltetraacetic acid [DOTA] derivatives) due to the incomplete release of lanthanide(III) ions from the complex. Here a modified and optimized DELFIA procedure incorporating an acid treatment protocol is introduced for use with Eu(III)-DOTA-labeled peptides. Complete release of Eu(III) ions from DOTA-labeled ligands was observed using hydrochloric acid (2.0M) prior to the luminescent enhancement step. [Nle(4),d-Phe(7)]-alpha-melanocyte-stimulating hormone (NDP-alpha-MSH) labeled with Eu(III)-DOTA was synthesized, and the binding affinity to cells overexpressing the human melanocortin-4 (hMC4) receptor was evaluated using the modified protocol. Binding data indicate that the Eu(III)-DOTA-linked peptide bound to these cells with an affinity similar to its DTPA analogue. The modified DELFIA procedure was further used to monitor the binding of an Eu(III)-DOTA-labeled heterobivalent peptide to the cells expressing both hMC4 and cholecystokinin-2 (CCK-2) receptors. The modified assay provides superior results and is appropriate for high-throughput screening of ligand libraries. PMID:19852924

  20. Development of betulinic acid as an agonist of TGR5 receptor using a new in vitro assay

    Lo, Shih-Hsiang; Cheng, Kai-Chung; Li, Ying-Xiao; Chang, Chin-Hong; Cheng, Juei-Tang; Lee, Kung-Shing

    2016-01-01

    Background G-protein-coupled bile acid receptor 1, also known as TGR5 is known to be involved in glucose homeostasis. In animal models, treatment with a TGR5 agonist induces incretin secretion to reduce hyperglycemia. Betulinic acid, a triterpenoid present in the leaves of white birch, has been introduced as a selective TGR5 agonist. However, direct activation of TGR5 by betulinic acid has not yet been reported. Methods Transfection of TGR5 into cultured Chinese hamster ovary (CHO-K1) cells was performed to establish the presence of TGR5. Additionally, TGR5-specific small interfering RNA was employed to silence TGR5 in cells (NCI-H716 cells) that secreted incretins. Uptake of glucose by CHO-K1 cells was evaluated using a fluorescent indicator. Amounts of cyclic adenosine monophosphate and glucagon-like peptide were quantified using enzyme-linked immunosorbent assay kits. Results Betulinic acid dose-dependently increases glucose uptake by CHO-K1 cells transfected with TGR5 only, which can be considered an alternative method instead of radioligand binding assay. Additionally, signals coupled to TGR5 activation are also increased by betulinic acid in cells transfected with TGR5. In NCI-H716 cells, which endogenously express TGR5, betulinic acid induces glucagon-like peptide secretion via increasing calcium levels. However, the actions of betulinic acid were markedly reduced in NCI-H716 cells that received TGR5-silencing treatment. Therefore, the present study demonstrates the activation of TGR5 by betulinic acid for the first time. Conclusion Similar to the positive control lithocholic acid, which is the established agonist of TGR5, betulinic acid has been characterized as a useful agonist of TGR5 and can be used to activate TGR5 in the future.

  1. Cultured neurons as model systems for biochemical and pharmacological studies on receptors for neurotransmitter amino acids

    Schousboe, A; Drejer, J; Hansen, Gert Helge;

    1985-01-01

    action of GABA on evoked release of glutamate, which is the neurotransmitter in cerebellar granule cells. Also glutamate receptors have been studied with regard to the 2 types of neurons. Both cerebral cortex neurons (GABAergic) and cerebellar granule cells (glutamatergic) possess glutamate receptors...

  2. Multi-functionalized hyaluronic acid nanogels crosslinked with carbon dots as dual receptor-mediated targeting tumor theranostics.

    Jia, Xu; Han, Yu; Pei, Mingliang; Zhao, Xubo; Tian, Kun; Zhou, Tingting; Liu, Peng

    2016-11-01

    Hyaluronic acid (HA)-based theranostic nanogels were designed for the tumor diagnosis and chemotherapy, by crosslinking the folate-terminated poly(ethylene glycol) modified hyaluronic acid (FA-PEG-HA) with carbon dots (CDs) for the first time. Due to the extraordinary fluorescence property of the integrated CDs, the theranostic nanogels could be used for the real-time and noninvasive location tracking to cancer cells. HA could load Doxorubicin (DOX) via electrostatic interaction with a drug-loading capacity (DLC) of 32.5%. The nanogels possessed an ideal release of DOX in the weak acid environment, while it was restrained in the neutral media, demonstrating the pH-responsive controlled release behavior. The cytotoxicity and cellular uptake results clearly illustrated that most DOX was released and accumulated in the cell nuclei and killed the cancer cells efficaciously, due to their dual receptor-mediated targeting characteristics. PMID:27516286

  3. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a novel activator of transient receptor potential vanilloid 1 (TRPV1) channel.

    Wen, Hairuo; Östman, Johan; Bubb, Kristen J; Panayiotou, Catherine; Priestley, John V; Baker, Mark D; Ahluwalia, Amrita

    2012-04-20

    TRPV1 is a member of the transient receptor potential ion channel family and is gated by capsaicin, the pungent component of chili pepper. It is expressed predominantly in small diameter peripheral nerve fibers and is activated by noxious temperatures >42 °C. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a cytochrome P-450 4A/4F-derived metabolite of the membrane phospholipid arachidonic acid. It is a powerful vasoconstrictor and has structural similarities with other TRPV1 agonists, e.g. the hydroperoxyeicosatetraenoic acid 12-HPETE, and we hypothesized that it may be an endogenous ligand for TRPV1 in sensory neurons innervating the vasculature. Here, we demonstrate that 20-HETE both activates and sensitizes mouse and human TRPV1, in a kinase-dependent manner, involving the residue Ser(502) in heterologously expressed hTRPV1, at physiologically relevant concentrations. PMID:22389490

  4. Adolescent social defeat alters N-methyl-d-aspartic acid receptor expression and impairs fear learning in adulthood.

    Novick, Andrew M; Mears, Mackenzie; Forster, Gina L; Lei, Yanlin; Tejani-Butt, Shanaz M; Watt, Michael J

    2016-05-01

    Repeated social defeat of adolescent male rats results in adult mesocortical dopamine hypofunction, impaired working memory, and increased contextual anxiety-like behavior. Given the role of glutamate in dopamine regulation, cognition, and fear and anxiety, we investigated potential changes to N-methyl-d-aspartic acid (NMDA) receptors following adolescent social defeat. As both NMDA receptors and mesocortical dopamine are implicated in the expression and extinction of conditioned fear, a separate cohort of rats was challenged with a classical fear conditioning paradigm to investigate whether fear learning is altered by adolescent defeat. Quantitative autoradiography was used to measure 3H-MK-801 binding to NMDA receptors in regions of the medial prefrontal cortex, caudate putamen, nucleus accumbens, amygdala and hippocampus. Assessment of fear learning was achieved using an auditory fear conditioning paradigm, with freezing toward the auditory tone used as a measure of conditioned fear. Compared to controls, adolescent social defeat decreased adult NMDA receptor expression in the infralimbic region of the prefrontal cortex and central amygdala, while increasing expression in the CA3 region of the hippocampus. Previously defeated rats also displayed decreased conditioned freezing during the recall and first extinction periods, which may be related to the observed decreases and increases in NMDA receptors within the central amygdala and CA3, respectively. The alteration in NMDA receptors seen following adolescent social defeat suggests that dysfunction of glutamatergic systems, combined with mesocortical dopamine deficits, likely plays a role in the some of the long-term behavioral consequences of social stressors in adolescence seen in both preclinical and clinical studies. PMID:26876136

  5. Transient Receptor Potential Vanilloid 4 Inhibits γ-Aminobutyric Acid-Activated Current in Hippocampal Pyramidal Neurons

    Hong, Zhiwen; Tian, Yujing; Qi, Mengwen; Li, Yingchun; Du, Yimei; Chen, Lei; Liu, Wentao; Chen, Ling

    2016-01-01

    The balance between excitatory and inhibitory neurotransmitter systems is crucial for the modulation of neuronal excitability in the central nervous system (CNS). The activation of transient receptor potential vanilloid 4 (TRPV4) is reported to enhance the response of hippocampal glutamate receptors, but whether the inhibitory neurotransmitter system can be regulated by TRPV4 remains unknown. γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the CNS. Here, we show that application of transient receptor potential vanilloid 4 (TRPV4) synthetic (GSK1016790A or 4α-PDD) or endogenous agonist (5,6-EET) inhibited GABA-activated current (IGABA) in hippocampal CA1 pyramidal neurons, which was blocked by specific antagonists of TRPV4 and of GABAA receptors. GSK1016790A increased the phosphorylated AMP-activated protein kinase (p-AMPK) and decreased the phosphorylated protein kinase B (p-Akt) protein levels, which was attenuated by removing extracellular calcium or by a calcium/calmodulin-dependent protein kinase kinase-β antagonist. GSK1016790A-induced decrease of p-Akt protein level was sensitive to an AMPK antagonist. GSK1016790A-inhibited IGABA was blocked by an AMPK antagonist or a phosphatidyl inositol 3 kinase (PI3K) agonist. GSK1016790A-induced inhibition of IGABA was also significantly attenuated by a protein kinase C (PKC) antagonist but was unaffected by protein kinase A or calcium/calmodulin-dependent protein kinase II antagonist. We conclude that activation of TRPV4 inhibits GABAA receptor, which may be mediated by activation of AMPK and subsequent down-regulation of PI3K/Akt signaling and activation of PKC signaling. Inhibition of GABAA receptors may account for the neuronal hyperexcitability caused by TRPV4 activation.

  6. Fatty acids and hypolipidemic drugs regulate peroxisome proliferator-activated receptors α- and γ-mediated gene expression via liver fatty acid binding protein: A signaling path to the nucleus

    Wolfrum, Christian; Borrmann, Carola M.; Börchers, Torsten; Spener, Friedrich

    2001-01-01

    Peroxisome proliferator-activated receptor α (PPARα) is a key regulator of lipid homeostasis in hepatocytes and target for fatty acids and hypolipidemic drugs. How these signaling molecules reach the nuclear receptor is not known; however, similarities in ligand specificity suggest the liver fatty acid binding protein (L-FABP) as a possible candidate. In localization studies using laser-scanning microscopy, we show that L-FABP and PPARα colocalize in the nucleus of...

  7. TRIM32 promotes retinoic acid receptor α-mediated differentiation in human promyelogenous leukemic cell line HL60

    Highlights: ► TRIM32 enhanced RARα-mediated transcriptional activity even in the absence of RA. ► TRIM32 stabilized RARα in the human promyelogenous leukemic cell line HL60. ► Overexpression of TRIM32 in HL60 cells induced granulocytic differentiation. ► TRIM32 may function as a coactivator for RARα-mediated transcription in APL cells. -- Abstract: Ubiquitination, one of the posttranslational modifications, appears to be involved in the transcriptional activity of nuclear receptors including retinoic acid receptor α (RARα). We previously reported that an E3 ubiquitin ligase, TRIM32, interacts with several important proteins including RARα and enhances transcriptional activity of RARα in mouse neuroblastoma cells and embryonal carcinoma cells. Retinoic acid (RA), which acts as a ligand to nuclear receptors including RARα, plays crucial roles in development, differentiation, cell cycles and apoptosis. In this study, we found that TRIM32 enhances RARα-mediated transcriptional activity even in the absence of RA and stabilizes RARα in the human promyelogenous leukemic cell line HL60. Moreover, we found that overexpression of TRIM32 in HL60 cells suppresses cellular proliferation and induces granulocytic differentiation even in the absence of RA. These findings suggest that TRIM32 functions as one of the coactivators for RARα-mediated transcription in acute promyelogenous leukemia (APL) cells, and thus TRIM32 may become a potentially therapeutic target for APL.

  8. Insulin binding and stimulation of hexose and amino acid transport by normal and receptor-defective human fibroblasts

    The authors analyzed insulin receptors in cells cultured from a sibship of related parents who had two offspring with severe insulin resistance (Leprechaunism). 124I-Insulin (1 ng/ml) binding to skin fibroblasts from the proband, mother, and father was 9, 60 and 62% of control cells, respectively, at equilibrium, Non-linear regression analysis, utilizing a two receptors model, of curvilinear Scatchard plots indicated a reduced number of high-affinity binding sites in both parents. Influx of L-Proline (System A), L-Serine (ASC) and L-Leucine (L) was similar in control and mutant cells. Similarly, during the depletion of intracellular amino acid pools, there was a release from transinhibition for System A and a decrease of transstimulation of Systems ASC and L in both cell lines. Surprisingly, insulin augmented, normally, A system influx with an ED50 = 70 ng/ml at 240C and 7 ng/ml at 370C. By contrast insulin failed to simulated 3-0-methyl-D-glucose influx into the proband's cells, while normal cells were stimulated 30% with an ED50 of 6 ng/ml. These results indicate that defective high-affinity insulin binding is inherited as an autosomal recessive trait; that general membrane functions are intact; that insulin regulates A system amino acid and hexose transport by two different mechanisms; and, that the latter mechanism is impaired by this family's receptor mutation

  9. Oleic acid enhances G protein coupled receptor 43 expression in bovine intramuscular adipocytes but not in subcutaneous adipocytes.

    Chung, K Y; Smith, S B; Choi, S H; Johnson, B J

    2016-05-01

    We hypothesized that fatty acids would differentially affect G protein coupled receptor (GPR) 43 mRNA expression and GPR43 protein concentrations in bovine intramuscular (IM) and subcutaneous (SC) adipocytes. The GPR43 protein was detected in bovine liver, pancreas, and semimembranosus (MUS) muscle in samples taken at slaughter. Similarly, GPR43 protein levels were similar in IM adipose tissue and SM muscle but was barely detectable in SC adipose tissue. Primary cultures of IM and SC stromal vascular cells were isolated from bovine adipose tissues. Oleic acid (100 μ) stimulated PPARγ gene expression and decreased stearoyl-CoA desaturase (SCD) gene expression but had no effect on GPR43 gene expression, which was readily detectable in both IM and SC adipocytes. Differentiation cocktail (Diff; 10 μ insulin, 4 μ dexamethasone, and 10 μ ciglitizone) stimulated CCAAT/enhancer-binding protein β (C/EBPβ) and PPARγ gene expression in SC but not IM adipocytes, but Diff increased SCD gene expression in both cell types. Linoleic acid (10 µ) increased PPARγ gene expression relative to Diff cocktail in SC adipocytes, whereas linoleic acid and α-linolenic decreased SCD gene expression relative to control adipocytes and adipocytes incubated with Diff ( < 0.05). Increasing concentrations of oleic acid (1, 10, 100, and 500 μM) increased GPR43 protein and mRNA expression in IM but not SC adipocytes. These data indicated that oleic acid alters mRNA and protein concentrations of GPR43 in bovine IM adipocytes. PMID:27285685

  10. Lysine and pipecolic acid and some of their derivatives show anticonvulsant activity, and stimulation of benzodiazepine receptor activity

    Benzodiazepines are one of the most widely prescribed drugs in the treatment of anxiety, epilepsy and muscle tension. The natural products lysine and pipecolic acid known to be present in the animal, plant and microorganism, have been shown to be anticonvulsant against pentetrazol (PTZ)-induced seizures in mice. Methyl and ethyl esters of L-lysine and the N-isopropanol derivative of pipecolic acid appear to increase the anticonvulsant potency of the parent compounds, presumably due to their increase in hydrophobicity. Lysine and pipecolic acid showed significant stimulation of specific [3H]flunitrazepam (FZ) binding to mouse brain membranes. This stimulation was enhanced by chloride ions and stereospecific with L-isomer having higher effect. The dose-dependent anticonvulsant activity of lysine and pipecolic acid, and their stimulation of [3H]FZ binding appear to be correlated. The antiepileptic activity lysine, pipecolic acid and their derivatives therefore may be mediated through the γ-aminobutyric acid-benzodiazepine receptor complex

  11. Identification of three adjacent amino acids of interleukin-2 receptor beta chain which control the affinity and the specificity of the interaction with interleukin-2.

    Imler, J L; Miyajima, A; Zurawski, G

    1992-01-01

    The beta chain of the interleukin-2 (IL-2) receptor (IL-2R beta) and the interleukin-3 (IL-3) binding protein AIC2A are members of the family of cytokine receptors, which also includes the receptors for growth hormone (GHR) and prolactin. A four amino acid sequence of AIC2A has recently been shown to be critical for IL-3 binding. We analyze here the function of the analogous sequence of human IL-2R beta and identify three amino acids, Ser132, His133 and Tyr134, which play a critical role in I...

  12. Progress in studies on the role of gamma-aminobutyric acid type A receptor in convulsion: a short review

    LI Xing-fang; LIU Li-qun

    2012-01-01

    Convulsion is the medical condition where body muscles contract and relax rapidly and repeatedly,resulting in an uncontrolled shaking of the body.The impaired inhibition of electrical activity in the brain is one of leading causes of convulsion.y-aminobutyric acid (GABA) is the chief inhibitory neurotransmitter in the mammalian central nervous system (CNS).GABA acts at inhibitory synapses in the brain by binding to specific transmembrane receptors in the plasma membrane of both pre- and post-synaptic neuronal processes.GABAA receptor (GABAAR) is the most important inhibitory receptor,and is the target receptor of anticonvulsant drugs in the clinic.In this review,we describe GABAergic signaling mediated by GABAAR,the mechanisms of GABAAR and their expression,and the progress being made on understanding the role of GABAAR in convulsion with emphasis on the association between GABAAR mutations or GABAAR subunit expression and convulsion.We also describe progress of anticonvulsant drugs based on the GABAAR.

  13. Expression of lipases and lipid receptors in sperm storage tubules and possible role of fatty acids in sperm survival in the hen oviduct.

    Huang, A; Isobe, N; Obitsu, T; Yoshimura, Y

    2016-04-15

    The aim of this study was to determine the role of fatty acids for sperm survival in the sperm storage tubules (SSTs) of the hen oviduct. The mucosa tissues of uterovaginal junction (UVJ) of White Leghorn laying hens with or without artificial insemination using semen from Barred Plymouth Rock roosters were collected. The lipid density in the epithelium of UVJ and SST was analyzed by Sudan black B staining. The expressions of genes encoding lipid receptors and lipases were assayed by polymerase chain reaction in UVJ mucosa and SST cells isolated by laser microdissection. Fatty acid composition was analyzed by gas chromatography, and sperm were cultured with or without the identified predominant fatty acids for 24 hours to examine their effect on sperm viability. The lipid droplets were localized in the epithelium of UVJ mucosa and SSTs. The expression of genes encoding very low-density lipoprotein receptor(VLDLR), low-density lipoprotein receptor (LDLR), and fatty acid translocase (FAT/CD36) were found in SST cells. Expression of genes encoding endothelial lipase (EL), lipase H (LIPH), adipose triglyceride lipase (ATGL), and lipoprotein lipase (LPL) were found in UVJ. In contrast, only ATGL was found in SST cells, and its expression was significantly upregulated after artificial insemination. In UVJ mucosal tissues, five fatty acids, namely myristic acid (C14), palmitic acid (C16), stearic acid (C18), oleic acid (C18:1n9), and linoleic acid (C18:2n6), were identified as predominant fatty acids. The viability of sperm cultured with 1 mM oleic acid or linoleic acid was significantly higher than the sperm in the control culture without fatty acids. These results suggest that lipids in the SST cells may be degraded by ATGL, and fatty acids including oleic acid and linoleic acid may be released into the SST lumen to support sperm survival. PMID:26777559

  14. Lysophosphatidic acid receptor-5 negatively regulates cellular responses in mouse fibroblast 3T3 cells

    Highlights: • LPA5 inhibits the cell growth and motile activities of 3T3 cells. • LPA5 suppresses the cell motile activities stimulated by hydrogen peroxide in 3T3 cells. • Enhancement of LPA5 on the cell motile activities inhibited by LPA1 in 3T3 cells. • The expression and activation of Mmp-9 were inhibited by LPA5 in 3T3 cells. • LPA signaling via LPA5 acts as a negative regulator of cellular responses in 3T3 cells. - Abstract: Lysophosphatidic acid (LPA) signaling via G protein-coupled LPA receptors (LPA1–LPA6) mediates a variety of biological functions, including cell migration. Recently, we have reported that LPA1 inhibited the cell motile activities of mouse fibroblast 3T3 cells. In the present study, to evaluate a role of LPA5 in cellular responses, Lpar5 knockdown (3T3-L5) cells were generated from 3T3 cells. In cell proliferation assays, LPA markedly stimulated the cell proliferation activities of 3T3-L5 cells, compared with control cells. In cell motility assays with Cell Culture Inserts, the cell motile activities of 3T3-L5 cells were significantly higher than those of control cells. The activity levels of matrix metalloproteinases (MMPs) were measured by gelatin zymography. 3T3-L5 cells stimulated the activation of Mmp-2, correlating with the expression levels of Mmp-2 gene. Moreover, to assess the co-effects of LPA1 and LPA5 on cell motile activities, Lpar5 knockdown (3T3a1-L5) cells were also established from Lpar1 over-expressing (3T3a1) cells. 3T3a1-L5 cells increased the cell motile activities of 3T3a1 cells, while the cell motile activities of 3T3a1 cells were significantly lower than those of control cells. These results suggest that LPA5 may act as a negative regulator of cellular responses in mouse fibroblast 3T3 cells, similar to the case for LPA1

  15. Lysophosphatidic acid receptor-5 negatively regulates cellular responses in mouse fibroblast 3T3 cells

    Dong, Yan; Hirane, Miku; Araki, Mutsumi [Division of Cancer Biology and Bioinformatics, Department of Life Science, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Fukushima, Nobuyuki [Division of Molecular Neurobiology, Department of Life Science, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Tsujiuchi, Toshifumi, E-mail: ttujiuch@life.kindai.ac.jp [Division of Cancer Biology and Bioinformatics, Department of Life Science, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502 (Japan)

    2014-04-04

    Highlights: • LPA{sub 5} inhibits the cell growth and motile activities of 3T3 cells. • LPA{sub 5} suppresses the cell motile activities stimulated by hydrogen peroxide in 3T3 cells. • Enhancement of LPA{sub 5} on the cell motile activities inhibited by LPA{sub 1} in 3T3 cells. • The expression and activation of Mmp-9 were inhibited by LPA{sub 5} in 3T3 cells. • LPA signaling via LPA{sub 5} acts as a negative regulator of cellular responses in 3T3 cells. - Abstract: Lysophosphatidic acid (LPA) signaling via G protein-coupled LPA receptors (LPA{sub 1}–LPA{sub 6}) mediates a variety of biological functions, including cell migration. Recently, we have reported that LPA{sub 1} inhibited the cell motile activities of mouse fibroblast 3T3 cells. In the present study, to evaluate a role of LPA{sub 5} in cellular responses, Lpar5 knockdown (3T3-L5) cells were generated from 3T3 cells. In cell proliferation assays, LPA markedly stimulated the cell proliferation activities of 3T3-L5 cells, compared with control cells. In cell motility assays with Cell Culture Inserts, the cell motile activities of 3T3-L5 cells were significantly higher than those of control cells. The activity levels of matrix metalloproteinases (MMPs) were measured by gelatin zymography. 3T3-L5 cells stimulated the activation of Mmp-2, correlating with the expression levels of Mmp-2 gene. Moreover, to assess the co-effects of LPA{sub 1} and LPA{sub 5} on cell motile activities, Lpar5 knockdown (3T3a1-L5) cells were also established from Lpar1 over-expressing (3T3a1) cells. 3T3a1-L5 cells increased the cell motile activities of 3T3a1 cells, while the cell motile activities of 3T3a1 cells were significantly lower than those of control cells. These results suggest that LPA{sub 5} may act as a negative regulator of cellular responses in mouse fibroblast 3T3 cells, similar to the case for LPA{sub 1}.

  16. Effect of amphetamine on extracellular concentrations of amino acids in striatum in neurotensin subtype 1 and 2 receptor null mice: a possible interaction between neurotensin receptors and amino acid systems for study of schizophrenia

    Li, Zhimin; Liang, Yanqi; Boules, Mona; Gordillo, Andres; Richelson, Elliott

    2010-01-01

    Neurotensin (NT) is a tridecapeptide that acts as a neuromodulator in the central nervous system mainly through two NT receptors: NTS1 and NTS2. The present study was done to determine the roles of NTS1 and NTS2 on amino acid release in striatum with the use of NTS1 or NTS2 knock-out (-/-) mice given d-amphetamine. Both NTS1-/- and NTS2-/- mice had lower extracellular concentrations of D-serine in striatum than did wild type (WT) mice. NTS2-/- but not NTS1-/- mice also had significantly lower...

  17. 视黄酸受体抑动剂对正常人体T淋巴细胞增殖的影响%THE EFFECT OF RETINOIC ACID RECEPTOR ANTAGONIST ON REGULAR HUMAN T CELLS

    吴凡凡; 李云; 赵品楠; 廖晓澄; 胡佳哲

    2011-01-01

    [目的]评价视黄酸受体RARs特异性抑动剂BIBn和视黄酸受体RXRs特异性抑动剂HX603对正常成年人体T淋巴细胞的增殖的影响,确定剂量水平,建立一套通过受体途径研究维生素A功能的实验方法. [方法]用密度梯度分离法和磁性细胞分选法从健康人的外周血分离T淋巴细胞,进行体外培养.采用MTT法.绘制人T淋巴细胞的体外生长曲线,并测定在10-4 mol/L、10-5 inoL/L、10-6 11101"1L、10-7 mot"/L 4个不同浓度时的OD值,用方差检验分析各剂量对细胞的影响. [结果]在培养24 h时1×10-4mol/L、1×10-5 mol/L、1×10-6mol/L、1×10-7 mol/L浓度的BIBn剂量组结果OD值分别为0.538±0.128、0.692±0.068、0.627±0.136、0.730±0.157(P<0.05). [结论]在培养24h时BIBn对T淋巴细胞增殖有抑制作用.HX603对T淋巴细胞增殖可能有抑制作用.%[Objective] To evaluate the effects of BIBn (the RARs specific antagonist) and HX603 ( the RXRs specific antagonist) on proliferation of T-Lymphocytes of human, identify the dose status, and establish a method which is dependent on retinoic acid receptor pathway to study the functions of vitamin A. [Methods] T-Lymphocytes were separated from the blood of healthy people by the way of the density gradlient separation and MACS, then cultured in vitro. MTT method was used to draw the growth curve and measure the OD value at different concentrations of 10-4 mol/L, 10-5 mol/L, 10-6 mol/L and 10-7 mol/L Then use One-Way-ANOVA to analyze the effect of different concentrations on cells. [ Results] The concentration at 10-4 moL/ L, 10-5 mol/L, 10-6 mol/L and 10-7 mol/L of BIBn made OD value 0.538±0.128, 0.692±0.068, 0.627±0.136 and 0.730±0.157 of T-Lymphocytes which cultured for 24 hours (P < 0.05) , respectively. [Conclusion] BIBn significantly inhibited the prolifer ation of T-Lymphocytes which cultured for 24 hours. HX603 might inhibit the proliferation of T-Lymphocytes.

  18. Alpha-lipoic acid-mediated activation of muscarinic receptors improves hippocampus- and amygdala-dependent memory.

    Mahboob, Aamra; Farhat, Syeda Mehpara; Iqbal, Ghazala; Babar, Mustafeez Mujtaba; Zaidi, Najam-us-Sahar Sadaf; Nabavi, Seyed Mohammad; Ahmed, Touqeer

    2016-04-01

    Aluminum (Al) is a neurotoxic agent which readily crosses the blood-brain-barrier (BBB) and accumulates in the brain leading to neurodegenerative disorders, characterised by cognitive impairment. Alpha-lipoic acid (ALA) is an antioxidant and has a potential to improve cognitive functions. This study aimed to evaluate the neuroprotective effect of ALA in AlCl3-induced neurotoxicity mouse model. Effect of ALA (25mg/kg/day) was evaluated in the AlCl3-induced neurotoxicity (AlCl3 150 mg/kg/day) mouse model on learning and memory using behaviour tests and on the expression of muscarinic receptor genes (using RT-PCR), in hippocampus and amygdala. Following ALA treatment, the expression of muscarinic receptor genes M1, M2 and choline acetyltransferase (ChaT) were significantly improved (penhanced fear memory (pmemory was remarkably restored (penhancement thus presenting it an enviable therapeutic candidate for the treatment of neurodegenerative disorders. PMID:26912408

  19. Could antagonists of excitatory amino acid receptors be used as antiepileptics in pediatric epileptology?

    Mareš, Pavel

    2006. s. 76-76. [Eilat conference on new antiepileptic drugs /8./. 10.09.2006-14.09.2006, Sitges] Institutional research plan: CEZ:AV0Z50110509 Keywords : anticonvulsive effect * antagonists * glutamate receptors Subject RIV: ED - Physiology

  20. Modulation of the retinoic acid-induced cell apoptosis and differentiation by the human TR4 orphan nuclear receptor

    In our previous studies, the TR4 orphan nuclear receptor (TR4) has been demonstrated to suppress retinoic acid (RA)-induced transactivation via a negative feedback control mechanism and in situ analysis showed that TR4 is extensively expressed in mouse brain, especially in regions where the cells are proliferating. To further study the potential roles of TR4 during cell differentiation, a tetracycline-inducible system with anti-sense TR4 in teratocarcinoma P19 cell lines was generated to analyze the retinoic acid-induced differentiation of these cells. The results indicated that the expression of TR4 reduced by doxycycline anti-sense TR4 would alter the retinoic acid-induced differentiation pathway that results in the changes of cell morphology and cell cycle profile. Unexpectedly, our data further indicated that the RA-induced apoptosis, judging by DNA fragmentation, could also be altered by the induction of anti-sense TR4. Together, these findings provide the first in vivo evidence that an orphan nuclear receptor, such as TR4, may play major roles in the RA-mediated apoptosis or differentiation in P19 cells

  1. Beneficial effects of kinin B1 receptor antagonism on plasma fatty acid alterations and obesity in Zucker diabetic fatty rats.

    Talbot, Sébastien; Dias, Jenny Pena; El Midaoui, Adil; Couture, Réjean

    2016-07-01

    Kinins are the endogenous ligands of the constitutive B2 receptor (B2R) and the inducible B1 receptor (B1R). Whereas B2R prevents insulin resistance, B1R is involved in insulin resistance and metabolic syndrome. However, the contribution of B1R in type 2 diabetes associated with obesity remains uncertain. The aim of the present study was to examine the impact of 1-week treatment with a selective B1R antagonist (SSR240612, 10 mg/kg per day, by gavage) on hyperglycemia, hyperinsulinemia, leptinemia, body mass gain, and abnormal plasma fatty acids in obese Zucker diabetic fatty (ZDF) rats. Treatment with SSR240612 abolished the body mass gain and reduced polyphagia, polydipsia, and plasma fatty acid alterations in ZDF rats without affecting hyperglycemia, hyperinsulinemia, and hyperleptinemia. The present study suggests that the upregulated B1R plays a role in body mass gain and circulating fatty acid alterations in ZDF rats. However, mechanisms other than B1R induction would be implicated in glucose metabolism disorder in ZDF rats, based on the finding that SSR240612 did not reverse hyperglycemia and hyperinsulinemia. PMID:27172260

  2. Folic acid derivatives for PET imaging and therapy addressing folate receptor positive tumors

    Folic acid, also known as vitamin B9, is the oxidized form of 5,6,7,8-tetrahydrofolate, which serves as methyl- or methylene donor (C1-building blocks) during DNA synthesis. Under physiological conditions the required amount of 5,6,7,8-tetrahydrofolate for survival of the cell is accomplished through the reduced folate carrier (RFC). In contrast, the supply of 5,6,7,8-tetrahydrofolate is insufficient under pathophysiological conditions of tumors due to an increased proliferation rate. Consequently, many tumor cells exhibit an (over)expression of the folate receptor. This phenomenon has been applied to diagnostics (PET, SPECT, MR) to image FR-positive tumors and on the other hand to treat malignancies related to a FR (over)expression. Based on this concept, a new 18F-labeled folate for PET imaging has been developed and was evaluated in vivo using tumor-bearing mice. The incorporation of oligoethylene spacers into the molecular structure led to a significant enhancement of the pharmacokinetics in comparison to previously developed 18F-folates. The liver uptake could be reduced by one sixth by remaining a tumor uptake of 3%ID/g leading to better contrast ratios. Encouraged by these results, a clickable 18F-labeled serine-based prosthetic group has been synthesized, again with the idea to improve the metabolic and pharmacokinetic profile of hydrophilic radiotracers. Therefore, an alkyne-carrying azido-functionalized serine derivative for coupling to biomolecules was synthesized and a chlorine leaving group for 18F-labeling, which could be accomplished using a microwave-assisted synthesis, a [K is contained in 2.2.2]+/carbonate system in DMSO. Radiochemical yields of 77±6% could be achieved. The promising results obtained from the FR-targeting concept in the diagnostic field have been transferred to the boron neutron capture therapy. Therefore, a folate derivative was coupled to different boron clusters and cell uptake studies were conducted. The synthesis of the

  3. Folic acid derivatives for PET imaging and therapy addressing folate receptor positive tumors

    Schieferstein, Hanno

    2013-07-01

    Folic acid, also known as vitamin B9, is the oxidized form of 5,6,7,8-tetrahydrofolate, which serves as methyl- or methylene donor (C1-building blocks) during DNA synthesis. Under physiological conditions the required amount of 5,6,7,8-tetrahydrofolate for survival of the cell is accomplished through the reduced folate carrier (RFC). In contrast, the supply of 5,6,7,8-tetrahydrofolate is insufficient under pathophysiological conditions of tumors due to an increased proliferation rate. Consequently, many tumor cells exhibit an (over)expression of the folate receptor. This phenomenon has been applied to diagnostics (PET, SPECT, MR) to image FR-positive tumors and on the other hand to treat malignancies related to a FR (over)expression. Based on this concept, a new {sup 18}F-labeled folate for PET imaging has been developed and was evaluated in vivo using tumor-bearing mice. The incorporation of oligoethylene spacers into the molecular structure led to a significant enhancement of the pharmacokinetics in comparison to previously developed {sup 18}F-folates. The liver uptake could be reduced by one sixth by remaining a tumor uptake of 3%ID/g leading to better contrast ratios. Encouraged by these results, a clickable {sup 18}F-labeled serine-based prosthetic group has been synthesized, again with the idea to improve the metabolic and pharmacokinetic profile of hydrophilic radiotracers. Therefore, an alkyne-carrying azido-functionalized serine derivative for coupling to biomolecules was synthesized and a chlorine leaving group for {sup 18}F-labeling, which could be accomplished using a microwave-assisted synthesis, a [K is contained in 2.2.2]{sup +}/carbonate system in DMSO. Radiochemical yields of 77±6% could be achieved. The promising results obtained from the FR-targeting concept in the diagnostic field have been transferred to the boron neutron capture therapy. Therefore, a folate derivative was coupled to different boron clusters and cell uptake studies were

  4. Regenerating Rat Liver: Correlations Between Estrogen Receptor Localization and Deoxyribonucleic Acid Synthesis

    Francavilla, Antonio; Di Leo, Alfredo; Eagon, Patricia K.; Wu, Shi-Quin; Ove, Peter; Van Thiel, David H.; Starzl, Thomas E.

    1984-01-01

    Estrogen receptor activity was quantitated in the cytosol and nucleus of normal rat liver and in regenerating rat liver at several time intervals after 75% hepatectomy. Cytosolic estradiol binding in regenerating liver decreases at 12, 24, and 48 h after hepatectomy and at 48 h is 30% of that in normal rat liver. Nuclear estrogen binding 48 h after surgery is elevated fivefold over normal values. No alterations in affiriity of the receptor for estrogen have been observed. Specificity studies ...

  5. Identification of amino acids involved in histamine potentiation of GABA A receptors

    Thiel, Ulrike; Platt, Sarah J.; Wolf, Steffen; Hatt, Hanns; Gisselmann, Günter

    2015-01-01

    Histamine is a neurotransmitter involved in a number of physiological and neuronal functions. In mammals, such as humans, and rodents, the histaminergic neurons found in the tuberomamillary nucleus project widely throughout the central nervous system. Histamine acts as positive modulator of GABAA receptors (GABAARs) and, in high concentrations (10 mM), as negative modulator of the strychnine-sensitive glycine receptor. However, the exact molecular mechanisms by which histamine acts on GABAARs...

  6. Postprandial fatty acid uptake and adipocyte remodeling in angiotensin type 2 receptor-deficient mice fed a high-fat/high-fructose diet.

    Noll, Christophe; Labbé, Sébastien M; Pinard, Sandra; Shum, Michael; Bilodeau, Lyne; Chouinard, Lucie; Phoenix, Serge; Lecomte, Roger; Carpentier, André C; Gallo-Payet, Nicole

    2016-01-01

    The role of the angiotensin type-2 receptor in adipose physiology remains controversial. The aim of the present study was to demonstrate whether genetic angiotensin type-2 receptor-deficiency prevents or worsens metabolic and adipose tissue morphometric changes observed following a 6-week high-fat/high-fructose diet with injection of a small dose of streptozotocin. We compared tissue uptake of nonesterified fatty acid and dietary fatty acid in wild-type and angiotensin type-2 receptor-deficient mice by using the radiotracer 14(R,S)-[(1) (8)F]-fluoro-6-thia-heptadecanoic acid in mice fed a standard or high-fat diet. Postprandial fatty acid uptake in the heart, liver, skeletal muscle, kidney and adipose tissue was increased in wild-type mice after a high-fat diet and in angiotensin type-2 receptor-deficient mice on both standard and high-fat diets. Compared to the wild-type mice, angiotensin type-2 receptor-deficient mice had a lower body weight, an increase in fasting blood glucose and a decrease in plasma insulin and leptin levels. Mice fed a high-fat diet exhibited increased adipocyte size that was prevented by angiotensin type-2 receptor-deficiency. Angiotensin type-2 receptor-deficiency abolished the early hypertrophic adipocyte remodeling induced by a high-fat diet. The small size of adipocytes in the angiotensin type-2 receptor-deficient mice reflects their inability to store lipids and explains the increase in fatty acid uptake in non-adipose tissues. In conclusion, a genetic deletion of the angiotensin type-2 receptor is associated with metabolic dysfunction of white adipose depots, and indicates that adipocyte remodeling occurs before the onset of insulin resistance in the high-fat fed mouse model. PMID:27144096

  7. Long chain polyunsaturated fatty acids alter oxytocin signaling and receptor density in cultured pregnant human myometrial smooth muscle cells.

    Kim, Paul Y; Zhong, Miao; Kim, Yoon-Sun; Sanborn, Barbara M; Allen, Kenneth G D

    2012-01-01

    Epidemiological studies and interventional clinical trials indicate that consumption of long chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) such as docosahexaenoic acid (DHA) lengthen gestational duration. Although the mechanisms are not well understood, prostaglandins (PG) of the 2-series are known to play a role in the initiation and progress of labor. In animal studies, modest DHA provision has been shown to reduce placental and uterine PGE(2) and PGF(2α), matrix metalloproteinase (MMP)-2 and MMP-9 expression, and placental collagenase activity. However, modulation of PG biosynthesis may not account for all the effects of LC n-3 PUFAs in labor. We investigated one potential PG-independent mechanism of LC PUFA action using cultured pregnant human myometrial smooth muscle cells. Our goal was to characterize the effect of LC PUFA treatment on oxytocin signaling, a potent uterotonic hormone involved in labor. The addition of 10 µM-100 µM DHA or arachidonic acid (AA) to the culture media for 48 h resulted in dose dependent enrichment of these fatty acids in membrane lipid. DHA and AA significantly inhibited phosphatidylinositol turnover and [Ca(2+)](i) mobilization with oxytocin stimulation compared to bovine serum albumin control and equimolar oleic acid. DHA and AA significantly reduced oxytocin receptor membrane concentration without altering binding affinity or rate of receptor internalization. These findings demonstrate a role for LC n-3 PUFAs in regulation of oxytocin signaling and provide new insight into additional mechanisms pertaining to reports of dietary fish and fish oil consumption prolonging gestation. PMID:22848573

  8. Phosphoenolpyruvate Carboxykinase, a Key Enzyme That Controls Blood Glucose, Is a Target of Retinoic Acid Receptor-Related Orphan Receptor α.

    Hiroshi Matsuoka

    Full Text Available Phosphoenolpyruvate carboxykinase (PEPCK catalyzes a committed and rate-limiting step in hepatic gluconeogenesis, and its activity is tightly regulated to maintain blood glucose levels within normal limits. PEPCK activity is primarily regulated through hormonal control of gene transcription. Transcription is additionally regulated via a cAMP response unit, which includes a cAMP response element and four binding sites for CCAAT/enhancer-binding protein (C/EBP. Notably, the cAMP response unit also contains a putative response element for retinoic acid receptor-related orphan receptor α (RORα. In this paper, we characterize the effect of the RORα response element on cAMP-induced transcription. Electrophoresis mobility shift assay indicates that RORα binds this response element in a sequence-specific manner. Furthermore, luciferase reporter assays indicate that RORα interacts with C/EBP at the PEPCK promoter to synergistically enhance transcription. We also found that cAMP-induced transcription depends in part on RORα and its response element. In addition, we show that suppression of RORα by siRNA significantly decreased PEPCK transcription. Finally, we found that a RORα antagonist inhibits hepatic gluconeogenesis in an in vitro glucose production assay. Taken together, the data strongly suggest that PEPCK is a direct RORα target. These results define possible new roles for RORα in hepatic gluconeogenesis.

  9. Genetic Variants of Retinoic Acid Receptor-Related Orphan Receptor Alpha Determine Susceptibility to Type 2 Diabetes Mellitus in Han Chinese

    Zhang, Yuwei; Liu, Yulan; Liu, Yin; Zhang, Yanjie; Su, Zhiguang

    2016-01-01

    Retinoic acid receptor-related orphan receptor alpha (RORA) plays a key role in the regulation of lipid and glucose metabolism and insulin expression that are implicated in the development of type 2 diabetes mellitus (T2DM). However, the effects of genetic variants in the RORA gene on the susceptibility to T2DM remain unknown. Nine tagging single-nucleotide polymorphisms (SNPs) were screened by using the SNaPshot method in 427 patients with T2DM and 408 normal controls. Association between genotypes and haplotypes derived from these SNPs with T2DM was analyzed using different genetic models. Allele and genotype frequencies at rs10851685 were significantly different between T2DM patients and control subjects (allele: p = 0.009, Odds ratios (OR) = 1.36 [95% Confidence intervals (CI) = 1.08–1.72]; genotype: p = 0.029). The minor allele T, at rs10851685, was potentially associated with an increased risk of T2DM in the dominant model, displaying OR of 1.38 (95% CI: 1.04–1.82, p = 0.025) in subjects with genotypes TA+TT vs. AA. In haplotype analysis, we observed that haplotypes GGTGTAACT, GGTGTAACC, and GATATAACT were significantly associated with increased risk of T2DM, while haplotypes GATGAAGTT, AGTGAAGTT, and AATGAAATT were protective against T2DM. These data suggest that the genetic variation in RORA might determine a Chinese Han individual’s susceptibility to T2DM. PMID:27556492

  10. Genetic Variants of Retinoic Acid Receptor-Related Orphan Receptor Alpha Determine Susceptibility to Type 2 Diabetes Mellitus in Han Chinese.

    Zhang, Yuwei; Liu, Yulan; Liu, Yin; Zhang, Yanjie; Su, Zhiguang

    2016-01-01

    Retinoic acid receptor-related orphan receptor alpha (RORA) plays a key role in the regulation of lipid and glucose metabolism and insulin expression that are implicated in the development of type 2 diabetes mellitus (T2DM). However, the effects of genetic variants in the RORA gene on the susceptibility to T2DM remain unknown. Nine tagging single-nucleotide polymorphisms (SNPs) were screened by using the SNaPshot method in 427 patients with T2DM and 408 normal controls. Association between genotypes and haplotypes derived from these SNPs with T2DM was analyzed using different genetic models. Allele and genotype frequencies at rs10851685 were significantly different between T2DM patients and control subjects (allele: p = 0.009, Odds ratios (OR) = 1.36 [95% Confidence intervals (CI) = 1.08-1.72]; genotype: p = 0.029). The minor allele T, at rs10851685, was potentially associated with an increased risk of T2DM in the dominant model, displaying OR of 1.38 (95% CI: 1.04-1.82, p = 0.025) in subjects with genotypes TA+TT vs. AA. In haplotype analysis, we observed that haplotypes GGTGTAACT, GGTGTAACC, and GATATAACT were significantly associated with increased risk of T2DM, while haplotypes GATGAAGTT, AGTGAAGTT, and AATGAAATT were protective against T2DM. These data suggest that the genetic variation in RORA might determine a Chinese Han individual's susceptibility to T2DM. PMID:27556492

  11. Discovery of Potent and Selective Agonists for the Free Fatty Acid Receptor 1 (FFA1/GPR40), a Potential Target for the Treatment of Type II Diabetes

    Christiansen, Elisabeth; Urban, Christian; Merten, Nicole;

    2008-01-01

    A series of 4-phenethynyldihydrocinnamic acid agonists of the free fatty acid receptor 1 (FFA 1) has been discovered and explored. The preferred compound 20 (TUG-424, EC 50 = 32 nM) significantly increased glucose-stimulated insulin secretion at 100 nM and may serve to explore the role of FFA 1 in...

  12. Effect of brain-derived neurotropic factor released from hypoxic astrocytes on gamma-aminobutyric acid type A receptor function in normal hippocampal neurons

    Hongliang Liu; Tijun Dai

    2011-01-01

    Astrocytes can release increased levels of brain-derived neurotrophic factor during cerebral ischemia, but it is unclear whether brain-derived neurotrophic factor affects γ-aminobutyric acid type A receptor function in normal neurons. Results from this study demonstrated that γ-aminobutyric acid at 100 μmol/L concentration raised the intracellular calcium level in neurons treated with medium from cultured hypoxic astrocytes, and the rise in calcium level could be inhibited by γ-aminobutyric acid type A receptor antagonist bicuculline or brain-derived neurotrophic factor receptor antagonist k252a. Γ-aminobutyric acid type A-gated current induced by 100 μmol/L γ-aminobutyric acid was in an inward direction in physiological conditions, but shifted to the outward direction in neurons when treated with the medium from cultured hypoxic astrocytes, and this effect could be inhibited by k252a. The reverse potential was shifted leftward to -93 Mv, which could be inhibited by k252a and Na+-K+-Cl- cotransporter inhibitor bumetanide. Brain-derived neurotrophic factor was released from hypoxic astrocytes at a high level. It shifted the reverse potential of γ-aminobutyric acid type A-gated currents leftward in normal neurons by enhancing the function of Na+-K+-Cl- cotransporter, and caused γ-aminobutyric acid to exert an excitatory effect by activating γ-aminobutyric acid type A receptor.

  13. Upregulation of peroxisome proliferator-activated receptors and liver fatty acid binding protein in hepatic cells of broiler chicken supplemented with conjugated linoleic acids

    Suriya Kumari Ramiah

    2015-09-01

    Full Text Available Since conjugated linoleic acid (CLA has structural and physiological characteristics similar to peroxisome proliferators, it is hypothesized that CLA would upregulate peroxisome proliferator-activated receptor (PPAR and liver fatty acid binding protein (LFABP in the liver of broiler chicken. The aim of the present study was to determine fatty acid composition of liver in CLA-fed broiler chickens and the genes associated with hepatic lipid metabolism. A total of 180-day-old broiler chicks were randomly assigned to two diets containing 0 and 2.5% CLA and fed for 6 weeks. Fatty acid (FA composition of liver and PPAR α and γ and L-FABP were analyzed. It has been demonstrated that CLA was found in the liver of CLA-feed chicken compared to control group. Hepatic PPAR α and γ mRNA levels were upregulated 1.2 and 3-fold in CLA-fed chickens compared to chickens fed diet without CLA respectively. A similar response of upregulation was observed for L-FABP mRNA expression. Our data highlights the role of PPARs as a core regulator in the regulation of lipid metabolism in chicken liver.

  14. The mouse lp(A3)/Edg7 lysophosphatidic acid receptor gene: genomic structure, chromosomal localization, and expression pattern.

    Contos, J J; Chun, J

    2001-04-18

    The extracellular signaling molecule, lysophosphatidic acid (LPA), mediates proliferative and morphological effects on cells and has been proposed to be involved in several biological processes including neuronal development, wound healing, and cancer progression. Three mammalian G protein-coupled receptors, encoded by genes designated lp (lysophospholipid) receptor or edg (endothelial differentiation gene), mediate the effects of LPA, activating similar (e.g. Ca(2+) release) as well as distinct (neurite retraction) responses. To understand the evolution and function of LPA receptor genes, we characterized lp(A3)/Edg7 in mouse and human and compared the expression pattern with the other two known LPA receptor genes (lp(A1)/Edg2 and lp(A2)/Edg4non-mutant). We found mouse and human lp(A3) to have nearly identical three-exon genomic structures, with introns upstream of the coding region for transmembrane domain (TMD) I and within the coding region for TMD VI. This structure is similar to lp(A1) and lp(A2), indicating a common ancestral gene with two introns. We localized mouse lp(A3) to distal Chromosome 3 near the varitint waddler (Va) gene, in a region syntenic with the human lp(A3) chromosomal location (1p22.3-31.1). We found highest expression levels of each of the three LPA receptor genes in adult mouse testes, relatively high expression levels of lp(A2) and lp(A3) in kidney, and moderate expression of lp(A2) and lp(A3) in lung. All lp(A) transcripts were expressed during brain development, with lp(A1) and lp(A2) transcripts expressed during the embryonic neurogenic period, and lp(A3) transcript during the early postnatal period. Our results indicate both overlapping as well as distinct functions of lp(A1), lp(A2), and lp(A3). PMID:11313151

  15. Loss of cation-independent mannose 6-phosphate receptor expression promotes the accumulation of lysobisphosphatidic acid in multilamellar bodies.

    Reaves, B J; Row, P E; Bright, N A; Luzio, J P; Davidson, H W

    2000-11-01

    A number of recent studies have highlighted the importance of lipid domains within endocytic organelles in the sorting and movement of integral membrane proteins. In particular, considerable attention has become focussed upon the role of the unusual phospholipid lysobisphosphatidic acid (LBPA). This lipid appears to be directly involved in the trafficking of cholesterol and glycosphingolipids, and accumulates in a number of lysosomal storage disorders. Antibody-mediated disruption of LBPA function also leads to mis-sorting of cation-independent mannose 6-phosphate receptors. We now report that the converse is also true, and that spontaneous loss of cation-independent mannose 6-phosphate receptors from a rat fibroblast cell line led to the formation of aberrant late endocytic structures enriched in LBPA. Accumulation of LBPA was directly dependent upon the loss of the receptors, and could be reversed by expression of bovine cation-independent mannose 6-phosphate receptors in the mutant cell line. Ultrastructural analysis indicated that the abnormal organelles were electron-dense, had a multi-lamellar structure, accumulated endocytosed probes, and were distinct from dense-core lysosomes present within the same cells. The late endocytic structures present at steady state within any particular cell likely reflect the balance of membrane traffic through the endocytic pathway of that cell, and the rate of maturation of individual endocytic organelles. Moreover, there is considerable evidence which suggests that cargo receptors also play a direct mechanistic role in membrane trafficking events. Therefore, loss of such a protein may disturb the overall equilibrium of the pathway, and hence cause the accumulation of aberrant organelles. We propose that this mechanism underlies the phenotype of the mutant cell line, and that the formation of inclusion bodies in many lysosomal storage diseases is also due to an imbalance in membrane trafficking within the endocytic pathway

  16. 9-Oxo-10(E),12(Z),15(Z)-Octadecatrienoic Acid Activates Peroxisome Proliferator-Activated Receptor α in Hepatocytes.

    Takahashi, Haruya; Kamakari, Kosuke; Goto, Tsuyoshi; Hara, Hideyuki; Mohri, Shinsuke; Suzuki, Hideyuki; Shibata, Daisuke; Nakata, Rieko; Inoue, Hiroyasu; Takahashi, Nobuyuki; Kawada, Teruo

    2015-11-01

    The peroxisome proliferator-activated receptor (PPAR)α is mainly expressed in the liver and plays an important role in the regulation of lipid metabolism. It has been reported that PPARα activation enhances fatty acid oxidation and reduces fat storage. Therefore, PPARα agonists are used to treat dyslipidemia. In the present study, we found that 9-oxo-10(E),12(Z),15(Z)-octadecatrienoic acid (9-oxo-OTA), which is a α-linolenic acid (ALA) derivative, is present in tomato (Solanum lycopersicum) extract. We showed that 9-oxo-OTA activated PPARα and induced the mRNA expression of PPARα target genes in murine primary hepatocytes. These effects promoted fatty acid uptake and the secretion of β-hydroxybutyrate, which is one of the endogenous ketone bodies. We also demonstrated that these effects of 9-oxo-OTA were not observed in PPARα-knockout (KO) primary hepatocytes. To our knowledge, this is the first study to report that 9-oxo-OTA promotes fatty acid metabolism via PPARα activation and discuss its potential as a valuable food-derived compound for use in the management of dyslipidemia. PMID:26387026

  17. Identification and characterization of a functional zebrafish smrt corepressor (ncor2)

    Linney, Elwood; Perz-Edwards, Alyssa; Kelley, Betty

    2011-01-01

    The retinoic acid receptors (RARs or rars) and the thyroid hormone receptors are members of the steroid receptor superfamily that interact with their DNA response elements (for RARs: retinoic acid response elements or RAREs) in the regulatory regions of promoters in the absence of their ligand. In this ligand minus configuration, it has been suggested that the RAR provides a binding site for a corepressor (SMRT or N-CoR) that also brings in other proteins to repress the gene. In the presence ...

  18. Discovery of a potent and selective free fatty acid receptor 1 agonist with low lipophilicity and high oral bioavailability

    Christiansen, Elisabeth; Due-Hansen, Maria E; Urban, Christian;

    2013-01-01

    The free fatty acid receptor 1 (FFA1, also known as GPR40) mediates enhancement of glucose-stimulated insulin secretion and is emerging as a new target for the treatment of type 2 diabetes. Several FFA1 agonists are known, but the majority of these suffer from high lipophilicity. We have previously...... reported the FFA1 agonist 3 (TUG-424). We here describe the continued structure-activity exploration and optimization of this compound series, leading to the discovery of the more potent agonist 40, a compound with low lipophilicity, excellent in vitro metabolic stability and permeability, complete oral...

  19. Discovery of a potent and selective free fatty acid receptor 1 agonist with low lipophilicity and high oral bioavailability.

    Christiansen, Elisabeth; Due-Hansen, Maria E; Urban, Christian; Grundmann, Manuel; Schmidt, Johannes; Hansen, Steffen V F; Hudson, Brian D; Zaibi, Mohamed; Markussen, Stine B; Hagesaether, Ellen; Milligan, Graeme; Cawthorne, Michael A; Kostenis, Evi; Kassack, Matthias U; Ulven, Trond

    2013-02-14

    The free fatty acid receptor 1 (FFA1, also known as GPR40) mediates enhancement of glucose-stimulated insulin secretion and is emerging as a new target for the treatment of type 2 diabetes. Several FFA1 agonists are known, but the majority of these suffer from high lipophilicity. We have previously reported the FFA1 agonist 3 (TUG-424). We here describe the continued structure-activity exploration and optimization of this compound series, leading to the discovery of the more potent agonist 40, a compound with low lipophilicity, excellent in vitro metabolic stability and permeability, complete oral bioavailability, and appreciable efficacy on glucose tolerance in mice. PMID:23294321

  20. Integrating data on the Arabidopsis NPR1/NPR3/NPR4 salicylic acid receptors; a differentiating argument

    Kuai, Xiahezi; MacLeod, Brandon J.; Després, Charles

    2015-01-01

    Salicylic acid (SA) is a mandatory plant metabolite in the deployment of systemic acquired resistance (SAR), a broad-spectrum systemic immune response induced by local inoculation with avirulent pathogens. The NPR1 transcription co-activator is the central node positively regulating SAR. SA was the last of the major hormones to be without a known receptor. Recently, NPR1 was shown to be the direct link between SA and gene activation. This discovery seems to be controversial. NPR1 being an SA-...

  1. The respective N-hydroxypyrazole analogues of the classical glutamate receptor ligands ibotenic acid and (RS)-2-amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid

    Clausen, Rasmus P; Hansen, Kasper B; Calí, Patrizia; Nielsen, Birgitte; Greenwood, Jeremy R; Begtrup, Mikael; Egebjerg, Jan; Bräuner-Osborne, Hans

    We have determined the pharmacological activity of N-hydroxypyrazole analogues (3a and 4a) of the classical glutamate receptor ligands ibotenic acid and (RS)-2-amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid (AMAA), as well as substituted derivatives of these two compounds. The pharmacologic...

  2. Inhibitory effects of azole-type fungicides on interleukin-17 gene expression via retinoic acid receptor-related orphan receptors α and γ

    The retinoic acid receptor-related orphan receptors α and γ (RORα and RORγ), are key regulators of helper T (Th)17 cell differentiation, which is involved in the innate immune system and autoimmune disorders. However, it remains unclear whether environmental chemicals, including pesticides, have agonistic and/or antagonistic activity against RORα/γ. In this study, we investigated the RORα/γ activity of several azole-type fungicides, and the effects of these fungicides on the gene expression of interleukin (IL)-17, which mediates the function of Th17 cells. In the ROR-reporter gene assays, five azole-type fungicides (imibenconazole, triflumizole, hexaconazole, tetraconazole and imazalil) suppressed RORα- and/or RORγ-mediated transcriptional activity as did benzenesulphonamide T0901317, a ROR inverse agonist and a liver X receptor (LXR) agonist. In particular, imibenconazole, triflumizole and hexaconazole showed RORγ inverse agonistic activity at concentrations of 10−6 M. However, unlike T0901317, these fungicides failed to show any LXRα/β agonistic activity. Next, five azole-type fungicides, showing ROR inverse agonist activity, were tested on IL-17 mRNA expression in mouse T lymphoma EL4 cells treated with phorbol myristate acetate and ionomycin. The quantitative RT-PCR analysis revealed that these fungicides suppressed the expression of IL-17 mRNA without effecting RORα and RORγ mRNA levels. In addition, the inhibitory effect of imibenconazole as well as that of T0901317 was absorbed in RORα/γ-knocked down EL4 cells. Taken together, these results suggest that some azole-type fungicides inhibit IL-17 production via RORα/γ. This also provides the first evidence that environmental chemicals can act as modulators of IL-17 expression in immune cells. -- Highlights: ► Nuclear receptors, RORα and RORγ, are key regulators of Th17 cell differentiation. ► Five azole-type fungicides act as RORα/γ inverse agonists. ► These fungicides suppress

  3. Inhibitory effects of azole-type fungicides on interleukin-17 gene expression via retinoic acid receptor-related orphan receptors α and γ

    Kojima, Hiroyuki, E-mail: kojima@iph.pref.hokkaido.jp [Hokkaido Institute of Public Health, Kita-19, Nishi-12, Kita-ku, Sapporo 060-0819 (Japan); Muromoto, Ryuta; Takahashi, Miki [Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812 (Japan); Takeuchi, Shinji [Hokkaido Institute of Public Health, Kita-19, Nishi-12, Kita-ku, Sapporo 060-0819 (Japan); Takeda, Yukimasa; Jetten, Anton M. [National Institute of Environmental Health Sciences, National Institutes of Health, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709 (United States); Matsuda, Tadashi [Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812 (Japan)

    2012-03-15

    The retinoic acid receptor-related orphan receptors α and γ (RORα and RORγ), are key regulators of helper T (Th)17 cell differentiation, which is involved in the innate immune system and autoimmune disorders. However, it remains unclear whether environmental chemicals, including pesticides, have agonistic and/or antagonistic activity against RORα/γ. In this study, we investigated the RORα/γ activity of several azole-type fungicides, and the effects of these fungicides on the gene expression of interleukin (IL)-17, which mediates the function of Th17 cells. In the ROR-reporter gene assays, five azole-type fungicides (imibenconazole, triflumizole, hexaconazole, tetraconazole and imazalil) suppressed RORα- and/or RORγ-mediated transcriptional activity as did benzenesulphonamide T0901317, a ROR inverse agonist and a liver X receptor (LXR) agonist. In particular, imibenconazole, triflumizole and hexaconazole showed RORγ inverse agonistic activity at concentrations of 10{sup −6} M. However, unlike T0901317, these fungicides failed to show any LXRα/β agonistic activity. Next, five azole-type fungicides, showing ROR inverse agonist activity, were tested on IL-17 mRNA expression in mouse T lymphoma EL4 cells treated with phorbol myristate acetate and ionomycin. The quantitative RT-PCR analysis revealed that these fungicides suppressed the expression of IL-17 mRNA without effecting RORα and RORγ mRNA levels. In addition, the inhibitory effect of imibenconazole as well as that of T0901317 was absorbed in RORα/γ-knocked down EL4 cells. Taken together, these results suggest that some azole-type fungicides inhibit IL-17 production via RORα/γ. This also provides the first evidence that environmental chemicals can act as modulators of IL-17 expression in immune cells. -- Highlights: ► Nuclear receptors, RORα and RORγ, are key regulators of Th17 cell differentiation. ► Five azole-type fungicides act as RORα/γ inverse agonists. ► These fungicides

  4. Modification on ursodeoxycholic acid (UDCA) scaffold. discovery of bile acid derivatives as selective agonists of cell-surface G-protein coupled bile acid receptor 1 (GP-BAR1).

    Sepe, Valentina; Renga, Barbara; Festa, Carmen; D'Amore, Claudio; Masullo, Dario; Cipriani, Sabrina; Di Leva, Francesco Saverio; Monti, Maria Chiara; Novellino, Ettore; Limongelli, Vittorio; Zampella, Angela; Fiorucci, Stefano

    2014-09-25

    Bile acids are signaling molecules interacting with the nuclear receptor FXR and the G-protein coupled receptor 1 (GP-BAR1/TGR5). GP-BAR1 is a promising pharmacological target for the treatment of steatohepatitis, type 2 diabetes, and obesity. Endogenous bile acids and currently available semisynthetic bile acids are poorly selective toward GP-BAR1 and FXR. Thus, in the present study we have investigated around the structure of UDCA, a clinically used bile acid devoid of FXR agonist activity, to develop a large family of side chain modified 3α,7β-dihydroxyl cholanoids that selectively activate GP-BAR1. In vivo and in vitro pharmacological evaluation demonstrated that administration of compound 16 selectively increases the expression of pro-glucagon 1, a GP-BAR1 target, in the small intestine, while it had no effect on FXR target genes in the liver. Further, compound 16 results in a significant reshaping of bile acid pool in a rodent model of cholestasis. These data demonstrate that UDCA is a useful scaffold to generate novel and selective steroidal ligands for GP-BAR1. PMID:25162837

  5. All-trans retinoic acid modulates mitogen-activated protein kinase pathway activation in human scleral fibroblasts through retinoic acid receptor beta

    Huo, Lijun; Cui, Dongmei; Yang, Xiao; Gao, Zhenya; Trier, Klaus

    2013-01-01

    Purpose All-trans retinoic acid (ATRA) is known to inhibit the proliferation of human scleral fibroblasts (HSFs) and to modulate the scleral intercellular matrix composition, and may therefore serve as a mediator for controlling eye growth. Cell proliferation is regulated by the mitogen-activated protein kinase (MAPK) pathway. The aim of the current study was to investigate whether changed activation of the MAPK pathway could be involved in the response of HSFs exposed to ATRA. Methods HSFs were cultured in Dulbecco Modified Eagle's Medium/F12 (DMEM/F12) and exposed to 1 μmol/l ATRA for 10 min, 30 min, 1 h, 8 h, or 24 h. The activation of extracellular signal-regulated kinase (ERK 1/2), p38, and c-Jun N-terminal kinase (JNK) in HSFs was assessed with western blot analysis and immunocytofluorescence. Results After exposure to ATRA for 24 h, the HSFs appeared shrunken and thinner than the control cells. The intercellular spaces were wider, and the HSFs appeared less numerous than in the control culture. Western blot showed decreased activation of ERK 1/2 in the HSFs from 30 min (p=0.01) to 24 h (p<0.01) after the start of exposure to ATRA, and increased activation of the JNK protein from 10 to 30 min (p<0.01) after the start of exposure to ATRA. Indirect immunofluorescence confirmed changes in activation of ERK 1/2 and JNK in HSFs exposed to ATRA. No change in activation of p38 in HSFs was observed after exposure to ATRA. Pretreatment of the HSFs with LE135, an antagonist of retinoic acid receptor beta (RARβ), abolished the ATRA-induced changes inactivation of ERK 1/2 and JNK. Conclusions ATRA inhibits HSF proliferation by a mechanism associated with modulation of ERK 1/2 and JNK activation and depends on stimulation of retinoic acid receptor beta. PMID:23946634

  6. Molecular Basis of the Receptor Interactions of Polysialic Acid (polySia), polySia Mimetics, and Sulfated Polysaccharides.

    Zhang, Ruiyan; Loers, Gabriele; Schachner, Melitta; Boelens, Rolf; Wienk, Hans; Siebert, Simone; Eckert, Thomas; Kraan, Stefan; Rojas-Macias, Miguel A; Lütteke, Thomas; Galuska, Sebastian P; Scheidig, Axel; Petridis, Athanasios K; Liang, Songping; Billeter, Martin; Schauer, Roland; Steinmeyer, Jürgen; Schröder, Jens-Michael; Siebert, Hans-Christian

    2016-05-01

    Polysialic acid (polySia) and polySia glycomimetic molecules support nerve cell regeneration, differentiation, and neuronal plasticity. With a combination of biophysical and biochemical methods, as well as data mining and molecular modeling techniques, it is possible to correlate specific ligand-receptor interactions with biochemical processes and in vivo studies that focus on the potential therapeutic impact of polySia, polySia glycomimetics, and sulfated polysaccharides in neuronal diseases. With this strategy, the receptor interactions of polySia and polySia mimetics can be understood on a submolecular level. As the HNK-1 glycan also enhances neuronal functions, we tested whether similar sulfated oligo- and polysaccharides from seaweed could be suitable, in addition to polySia, for finding potential new routes into patient care focusing on an improved cure for various neuronal diseases. The knowledge obtained here on the structural interplay between polySia or sulfated polysaccharides and their receptors can be exploited to develop new drugs and application routes for the treatment of neurological diseases and dysfunctions. PMID:27136597

  7. Involvement of aberrant DNA methylation on reduced expression of lysophosphatidic acid receptor-1 gene in rat tumor cell lines

    Lysophosphatidic acid (LPA) is a bioactive phospholipid that stimulates cell proliferation, migration, and protects cells from apoptosis. It interacts with specific G protein-coupled transmembrane receptors. Recently, it has been reported that alterations of LPA receptor expression might be important in the malignant transformation of tumor cells. Therefore, to assess an involvement of DNA methylation in reduced expression of the LPA receptor-1 (lpa1) gene, we investigated the expression of the lpa1 gene and its DNA methylation patterns in rat tumor cell lines. Both rat brain-derived neuroblastoma B103 and liver-derived hepatoma RH7777 cells used in this study indicated no expression of lpa1. For the analysis of methylation status, bisulfite sequencing was performed with B103 and RH7777 cells, comparing with other lpa1 expressed cells and normal tissues of brain and liver. The lpa1 expressed cells and tissues were all unmethylated in this region of lpa1. In contrast, both B103 and RH7777 cells were highly methylated, correlating with reduced expression of the lpa1. Treatment with 5-aza 2'-deoxycytidine induced expression of lpa1 gene in B103 and RH7777 cells after 24 h. In RH7777 cells treated with 5-aza 2'-deoxycytidine, stress fiber formation was also observed in response to LPA in RH7777 cells, but not in untreated RH7777 cells. These results suggest that aberrant DNA methylation of the lpa1 gene may be involved in its reduced expression in rat tumor cells

  8. Depletion of Retinoic Acid Receptors Initiates a Novel Positive Feedback Mechanism that Promotes Teratogenic Increases in Retinoic Acid

    Enrico D'Aniello; Rydeen, Ariel B.; Jane L Anderson; Amrita Mandal; Waxman, Joshua S.

    2013-01-01

    Author Summary Retinoic acid (RA) is the most active metabolic product of Vitamin A. Appropriate levels of RA are required for proper embryonic development and tissue maintenance in all vertebrates. Inappropriate levels of RA in human embryos can cause congenital defects that affect many organs, including the heart and limbs, and lead to numerous types of cancers. Understanding how animals maintain appropriate RA levels and the consequences of inappropriate RA signaling will therefore provide...

  9. La t??cnica del parto y la obstetricia en la sociedad rar??muri de la sierra Tarahumara (M??xico)

    G??mez Molina, Estrella; Acu??a Delgado, ??ngel

    2010-01-01

    Dentro del proyecto de investigaci??n sobre la construcci??n social y cultural del cuerpo rar??muri (pueblo amerindio del norte de M??xico adaptado a zona monta??osa), llevado a cabo entre 2001 y 2005, ofrecemos aqu?? los resultados, desde un punto de vista descriptivo, sobre los rasgos m??s caracter??sticos del proceso que rodea el embarazo y nacimiento de un nuevo ser. Apoyados en una metodolog??a estrictamente etnogr??fica, basada en el intenso y sistem??tico trabajo de campo, responderemo...

  10. The conjugated linoleic acid isomer trans-9,trans-11 is a dietary occurring agonist of liver X receptor α

    Conjugated linoleic acid (CLA) isomers are dietary fatty acids that modulate gene expression in many cell types. We have previously reported that specifically trans-9,trans-11 (t9,t11)-CLA induces expression of genes involved in lipid metabolism of human macrophages. To elucidate the molecular mechanism underlying this transcriptional activation, we asked whether t9,t11-CLA affects activity of liver X receptor (LXR) α, a major regulator of macrophage lipid metabolism. Here we show that t9,t11-CLA is a regulator of LXRα. We further demonstrate that the CLA isomer induces expression of direct LXRα target genes in human primary macrophages. Knockdown of LXRα with RNA interference in THP-1 cells inhibited t9,t11-CLA mediated activation of LXRα including its target genes. To evaluate the effective concentration range of t9,t11-CLA, human primary macrophages were treated with various doses of CLA and well known natural and synthetic LXR agonists and mRNA expression of ABCA1 and ABCG1 was analyzed. Incubation of human macrophages with 10 μM t9,t11-CLA led to a significant modulation of ABCA1 and ABCG1 transcription and caused enhanced cholesterol efflux to high density lipoproteins and apolipoprotein AI. In summary, these data show that t9,t11-CLA is an agonist of LXRα in human macrophages and that its effects on macrophage lipid metabolism can be attributed to transcriptional regulations associated with this nuclear receptor.

  11. Farnesoid X receptor signal is involved in deoxycholic acid-induced intestinal metaplasia of normal human gastric epithelial cells.

    Li, Shu; Chen, Xin; Zhou, Lu; Wang, Bang-Mao

    2015-11-01

    The farnesoid X receptor (FXR) signaling pathway is known to be involved in the metabolism of bile acid, glucose and lipid. In the present study, we demonstrated that 400 µmol/l deoxycholic acid (DCA) stimulation promotes the proliferation of normal human gastric epithelial cells (GES-1). In addition, DCA activated FXR and increased the expression of intestinal metaplasia genes, including caudal-related homeobox transcription factor 2 (Cdx2) and mucin 2 (MUC2). The treatment of FXR agonist GW4064/antagonist guggulsterone (Gug.) significantly increased/decreased the expression levels of FXR, Cdx2 and MUC2 protein in DCA-induced GES-1 cells. GW4064/Gug. also enhanced/reduced the nuclear factor-κB (NF-κB) activity and binding of the Cdx2 promoter region and NF-κB, the most common subunit p50 protein. Taken together, the results indicated that DCA is capable of modulating the expression of Cdx2 and the downstream MUC2 via the nuclear receptor FXR-NF-κB activity in normal gastric epithelial cells. FXR signaling pathway may therefore be involved in the intestinal metaplasia of human gastric mucosa. PMID:26324224

  12. γ-Aminobutyric Acid Type A Receptor Subunit α-6 (GABRA6 Gene Polymorphism and Anxiety Disorder

    Melisa I. Barliana

    2016-06-01

    Full Text Available Anxiety disorder caused by environmental factor and individual genetic variations. Gamma-aminobutyric acid type A receptors Subunit α-6 (GABRA6 is γ-aminobutyric acid type A (GABA receptor. Single Nucleotide Polymorphism (SNP of GABRA6 gene at rs3219151 (T1521C affected individual response of stress. The aim of present study was to identify GABRA6 genotype variations in Bandung city population and its correlation with stress condition. Samples were collected from 112 respondents who filled The Kessler Psychological Distress Scale (K10 questionnaire for stress condition. Blood samples were collected and identification of GABRA6 gene was analyzed using Polymerase Chain Reaction‑Refractory Fragment Length Polymorphism (PCR-RFLP by AlwN1 restriction enzyme digestion. The result of present study showed that 84 respondents (75% have CC genotype, 14 respondents (12.5% have CT genotype, and other 14 respondents (12.5% have TT genotype. Most of respondents have CC genotype but the data did not meet the Hardy-Weinberg equilibrium and showed no correlation between GABRA6 gene variations and stress condition using bivariate analysis (Chi-Square.

  13. Reevaluation of fatty acid receptor 1 as a drug target for the stimulation of insulin secretion in humans.

    Wagner, Robert; Kaiser, Gabriele; Gerst, Felicia; Christiansen, Elisabeth; Due-Hansen, Maria E; Grundmann, Manuel; Machicao, Fausto; Peter, Andreas; Kostenis, Evi; Ulven, Trond; Fritsche, Andreas; Häring, Hans-Ulrich; Ullrich, Susanne

    2013-06-01

    The role of free fatty acid receptor 1 (FFAR1/GPR40) in glucose homeostasis is still incompletely understood. Small receptor agonists stimulating insulin secretion are undergoing investigation for the treatment of type 2 diabetes. Surprisingly, genome-wide association studies did not discover diabetes risk variants in FFAR1. We reevaluated the role of FFAR1 in insulin secretion using a specific agonist, FFAR1-knockout mice and human islets. Nondiabetic individuals were metabolically phenotyped and genotyped. In vitro experiments indicated that palmitate and a specific FFAR1 agonist, TUG-469, stimulate glucose-induced insulin secretion through FFAR1. The proapoptotic effect of chronic exposure of β-cells to palmitate was independent of FFAR1. TUG-469 was protective, whereas inhibition of FFAR1 promoted apoptosis. In accordance with the proapoptotic effect of palmitate, in vivo cross-sectional observations demonstrated a negative association between fasting free fatty acids (NEFAs) and insulin secretion. Because NEFAs stimulate secretion through FFAR1, we examined the interaction of genetic variation in FFAR1 with NEFA and insulin secretion. The inverse association of NEFA and secretion was modulated by rs1573611 and became steeper for carriers of the minor allele. In conclusion, FFAR1 agonists support β-cell function, but variation in FFAR1 influences NEFA effects on insulin secretion and therefore could affect therapeutic efficacy of FFAR1 agonists. PMID:23378609

  14. An amino acid residue in the second extracellular loop determines the agonist-dependent tolerance property of the human D3 dopamine receptor.

    Gil-Mast, Sara; Kortagere, Sandhya; Kota, Kokila; Kuzhikandathil, Eldo V

    2013-06-19

    The D3 dopamine receptor is a therapeutic target for treating various nervous system disorders such as schizophrenia, Parkinson's disease, depression, and addictive behaviors. The crystal structure of the D3 receptor bound to an antagonist was recently described; however, the structural features that contribute to agonist-induced conformational changes and signaling properties are not well understood. We have previously described the conformation-dependent tolerance and slow response termination (SRT) signaling properties of the D3 receptor and identified the C147 residue in the second intracellular loop (IL2) of the D3 receptor as important for the tolerance property. Interestingly, while IL2 and the C147 residue, in particular, were important for dopamine- and quinpirole-induced tolerance, this residue did not affect the severe tolerance induced by the high affinity, D3 receptor-selective agonist, PD128907. Here, we used D2/D3 receptor chimeras and site-specific D3 receptor mutants to identify another residue, D187, in the second extracellular loop (EC2) of the human D3 receptor that mediates the tolerance property induced by PD128907, quinpirole, pramipexole, and dopamine. Molecular dynamics simulations confirmed the distinct conformation adopted by D3 receptor during tolerance and suggested that in the tolerant D3 receptor the D187 residue in EC2 forms a salt bridge with the H354 residue in EC3. Indeed, site-directed mutation of the H354 residue resulted in loss of PD1287907-induced tolerance. The mapping of specific amino acid residues that contribute to agonist-dependent conformation changes and D3 receptor signaling properties refines the agonist-bound D3 receptor pharmacophore model which will help develop novel D3 receptor agonists. PMID:23477444

  15. Stereoselective synthesis, biological evaluation, and modeling of novel bile acid-derived G-protein coupled bile acid receptor 1 (GP-BAR1, TGR5) agonists.

    Yu, Donna D; Sousa, Kyle M; Mattern, Daniell L; Wagner, Jeffrey; Fu, Xianghui; Vaidehi, Nagarajan; Forman, Barry M; Huang, Wendong

    2015-04-01

    GP-BAR1 (also known as TGR5), a novel G-protein coupled receptor regulating various non-genomic functions via bile acid signaling, has emerged as a promising target for metabolic disorders, including obesity and type II diabetes. However, given that many bile acids (BAs) are poorly tolerated for systemic therapeutic use, there is significant need to develop GP-BAR1 agonists with improved potency and specificity and there also is significant impetus to develop a stereoselective synthetic methodology for GP-BAR1 agonists. Here, we report the development of highly stereo-controlled strategies to investigate a series of naturally occurring bile acid derivatives with markedly enhanced GP-BAR1 activity. These novel GP-BAR1 agonists are evaluated in vitro using luciferase-based reporter and cAMP assays to elucidate their biological properties. In vivo studies revealed that the GP-BAR1 agonist 23(S)-m-LCA increased intestinal GLP-1 transcripts by 26-fold. Additionally, computational modeling studies of selected ligands that exhibit enhanced potency and specificity for GP-BAR1 provide information on potential binding sites for these ligands in GP-BAR1. PMID:25735208

  16. Induction of CYP26A1 by Metabolites of Retinoic Acid: Evidence That CYP26A1 Is an Important Enzyme in the Elimination of Active Retinoids

    Topletz, Ariel R.; Tripathy, Sasmita; Foti, Robert S.; Shimshoni, Jakob A.; Nelson, Wendel L.

    2015-01-01

    All-trans-retinoic acid (atRA), the active metabolite of vitamin A, induces gene transcription via binding to nuclear retinoic acid receptors (RARs). The primary hydroxylated metabolites formed from atRA by CYP26A1, and the subsequent metabolite 4-oxo-atRA, bind to RARs and potentially have biologic activity. Hence, CYP26A1, the main atRA hydroxylase, may function either to deplete bioactive retinoids or to form active metabolites. This study aimed to determine the role of CYP26A1 in modulating RAR activation via formation and elimination of active retinoids. After treatment of HepG2 cells with atRA, (4S)-OH-atRA, (4R)-OH-atRA, 4-oxo-atRA, and 18-OH-atRA, mRNAs of CYP26A1 and RARβ were increased 300- to 3000-fold, with 4-oxo-atRA and atRA being the most potent inducers. However, >60% of the 4-OH-atRA enantiomers were converted to 4-oxo-atRA in the first 12 hours of treatment, suggesting that the activity of the 4-OH-atRA was due to 4-oxo-atRA. In human hepatocytes, atRA, 4-OH-atRA, and 4-oxo-atRA induced CYP26A1 and 4-oxo-atRA formation was observed from 4-OH-atRA. In HepG2 cells, 4-oxo-atRA formation was observed even in the absence of CYP26A1 activity and this formation was not inhibited by ketoconazole. In human liver microsomes, 4-oxo-atRA formation was supported by NAD+, suggesting that 4-oxo-atRA formation is mediated by a microsomal alcohol dehydrogenase. Although 4-oxo-atRA was not formed by CYP26A1, it was depleted by CYP26A1 (Km = 63 nM and intrinsic clearance = 90 μl/min per pmol). Similarly, CYP26A1 depleted 18-OH-atRA and the 4-OH-atRA enantiomers. These data support the role of CYP26A1 to clear bioactive retinoids, and suggest that the enzyme forming active 4-oxo-atRA may be important in modulating retinoid action. PMID:25492813

  17. Addictive evaluation of cholic acid-verticinone ester, a potential cough therapeutic agent with agonist action of opioid receptor

    Jiu-liang ZHANG; Hui WANG; Chang CHEN; Hui-fang PI; Han-li RUAN; Peng ZHANG; Ji-zhou WU

    2009-01-01

    Aim: The purpose of this work was to search for potential drugs with potent antitussive and expectorant activities as well as a low toxicity, but without addictive properties. Cholic acid-verticinone ester (CA-Ver) was synthesized based on the clearly elucidated antitussive and expectorant activities of verticinone in bulbs of Fritillaria and different bile acids in Snake Bile. In our previous study, CA-Vet showed a much more potent activity than codeine phosphate. This study was carried out to investigate the central antitussive mechanism and the addictive evaluation of CA-Ver.Methods: Testing on a capsaicin-induced cough model of mice pretreated with naloxone, a non-selective opioid receptor antagonist, was performed for the observation of CA-Ver's central antitussive mechanism. We then took naloxone-induced withdrawal tests of mice for the judgment of CA-Ver's addiction. Lastly, we determined the opioid dependence of CA-Ver in the guinea pig ileum. Results: The test on the capsaicin-induced cough model showed that naloxone could block the antitussive effect of CA-Ver,suggesting the antitussive mechanism of CA-Ver was related to the central opioid receptors. The naloxone-urged withdrawal tests of the mice showed that CA-Ver was not addictive, and the test of the opioid dependence in the guinea pig ileum showed that CA-Ver had no withdrawal response.Conclusion: These findings suggested that CA-Ver deserved attention for its potent antitussive effects related to the central opioid receptors, but without addiction, and had a good development perspective.

  18. The anticonvulsant gabapentin (neurontin) does not act through gamma-aminobutyric acid-B receptors

    Jensen, Anders A.; Mosbacher, Johannes; Elg, Susanne;

    2002-01-01

    (B) receptor agonist baclofen, gabapentin was unable to inhibit transient lower esophageal sphincter relaxations in dogs. Because of high levels of GABA(B(1a)) in the canine nodose ganglion, this finding indirectly supports the inactivity of gabapentin on the GABA(B(1a,2)) heterodimer demonstrated in various...

  19. The human receptor for urokinase plasminogen activator. NH2-terminal amino acid sequence and glycosylation variants

    Behrendt, N; Rønne, E; Ploug, M;

    1990-01-01

    The receptor for human urokinase-type plasminogen activator (u-PA) was purified from phorbol 12-myristate 13-acetate-stimulated U937 cells by temperature-induced phase separation of detergent extracts, followed by affinity chromatography with immobilized diisopropyl fluorophosphate-treated u-PA. ...

  20. Mutation-induced quisqualic acid and ibotenic acid affinity at the metabotropic glutamate receptor subtype 4: ligand selectivity results from a synergy of several amino acid residues

    Hermit, Mette B; Greenwood, Jeremy R; Bräuner-Osborne, Hans

    2004-01-01

    The metabotropic glutamate receptors (mGluRs) are key modulators of excitatory neurotransmission in the central nervous system. The eight mGluR subtypes are seven trans-membrane-spanning proteins that possess a large extracellular amino-terminal domain in which the endogenous ligand binding pocke...

  1. Altered mRNA editing and expression of ionotropic glutamate receptors after kainic acid exposure in cyclooxygenase-2 deficient mice.

    Luca Caracciolo

    Full Text Available Kainic acid (KA binds to the AMPA/KA receptors and induces seizures that result in inflammation, oxidative damage and neuronal death. We previously showed that cyclooxygenase-2 deficient (COX-2(-/- mice are more vulnerable to KA-induced excitotoxicity. Here, we investigated whether the increased susceptibility of COX-2(-/- mice to KA is associated with altered mRNA expression and editing of glutamate receptors. The expression of AMPA GluR2, GluR3 and KA GluR6 was increased in vehicle-injected COX-2(-/- mice compared to wild type (WT mice in hippocampus and cortex, whereas gene expression of NMDA receptors was decreased. KA treatment decreased the expression of AMPA, KA and NMDA receptors in the hippocampus, with a significant effect in COX-2(-/- mice. Furthermore, we analyzed RNA editing levels and found that the level of GluR3 R/G editing site was selectively increased in the hippocampus and decreased in the cortex in COX-2(-/- compared with WT mice. After KA, GluR4 R/G editing site, flip form, was increased in the hippocampus of COX-2(-/- mice. Treatment of WT mice with the COX-2 inhibitor celecoxib for two weeks decreased the expression of AMPA/KA and NMDAR subunits after KA, as observed in COX-2(-/- mice. After KA exposure, COX-2(-/- mice showed increased mRNA expression of markers of inflammation and oxidative stress, such as cytokines (TNF-α, IL-1β and IL-6, inducible nitric oxide synthase (iNOS, microglia (CD11b and astrocyte (GFAP. Thus, COX-2 gene deletion can exacerbate the inflammatory response to KA. We suggest that COX-2 plays a role in attenuating glutamate excitotoxicity by modulating RNA editing of AMPA/KA and mRNA expression of all ionotropic glutamate receptor subunits and, in turn, neuronal excitability. These changes may contribute to the increased vulnerability of COX-2(-/- mice to KA. The overstimulation of glutamate receptors as a consequence of COX-2 gene deletion suggests a functional coupling between COX-2 and the

  2. Lysophosphatidic acid receptor 1 antagonist ki16425 blunts abdominal and systemic inflammation in a mouse model of peritoneal sepsis.

    Zhao, Jing; Wei, Jianxin; Weathington, Nathaniel; Jacko, Anastasia M; Huang, Hai; Tsung, Allan; Zhao, Yutong

    2015-07-01

    Lysophosphatidic acid (LPA) is a bioactive lipid mediator of inflammation via the LPA receptors 1-6. We and others have previously described proinflammatory and profibrotic activities of LPA signaling in bleomycin- or lipopolysaccharide (LPS)-induced pulmonary fibrosis or lung injury models. In this study, we investigated if LPA signaling plays a role in the pathogenesis of systemic sepsis from an abdominal source. We report here that antagonism of the LPA receptor LPA1 with the small molecule ki16425 reduces the severity of abdominal inflammation and organ damage in the setting of peritoneal endotoxin exposure. Pretreatment of mice with intraperitoneal ki16425 eliminates LPS-induced peritoneal neutrophil chemokine and cytokine production, liver oxidative stress, liver injury, and cellular apoptosis in visceral organs. Mice pretreated with ki16425 are also protected from LPS-induced mortality. Tissue myeloperoxidase activity is not affected by LPA1 antagonism. We have shown that LPA1 is associated with LPS coreceptor CD14 and the association is suppressed by ki16425. LPS-induced phosphorylation of protein kinase C δ (PKCδ) and p38 mitogen-activated protein kinase (p38 MAPK) in liver cells and interleukin 6 production in Raw264 cells are likewise blunted by LPA1 antagonism. These studies indicate that the small molecule inhibitor of LPA1, ki16425, suppresses cytokine responses and inflammation in a peritoneal sepsis model by blunting downstream signaling through the LPA1-CD14-toll-like receptor 4 receptor complex. This anti-inflammatory effect may represent a therapeutic strategy for the treatment of systemic inflammatory responses to infection of the abdominal cavity. PMID:25701366

  3. Effect of cannabidiol on sepsis-induced motility disturbances in mice: involvement of CB receptors and fatty acid amide hydrolase.

    de Filippis, D; Iuvone, T; d'amico, A; Esposito, G; Steardo, L; Herman, A G; Pelckmans, P A; de Winter, B Y; de Man, J G

    2008-08-01

    Sepsis is an inflammatory condition that is associated with reduced propulsive gastrointestinal motility (ileus). A therapeutic option to treat sepsis is to promote intestinal propulsion preventing bacterial stasis, overgrowth and translocation. Recent evidence suggests that anti-oxidants improve sepsis-induced ileus. Cannabidiol, a non-psychotropic component of Cannabis sativa, exerts strong anti-oxidant and anti-inflammatory effects without binding to cannabinoid CB(1) or CB(2) receptors. Cannabidiol also regulates the activity of fatty acid amide hydrolase (FAAH) which is the main enzyme involved in endocannabinoid breakdown and which modulates gastrointestinal motility. Because of the therapeutic potential of cannabidiol in several pathologies, we investigated its effect on sepsis-induced ileus and on cannabinoid receptor and FAAH expression in the mouse intestine. Sepsis was induced by treating mice with lipopolysaccharides for 18 h. Sepsis led to a decrease in gastric emptying and intestinal transit. Cannabidiol further reduced gastrointestinal motility in septic mice but did not affect gastrointestinal motility in control mice. A low concentration of the CB(1) antagonist AM251 did not affect gastrointestinal motility in control mice but reversed the effect of cannabidiol in septic mice. Sepsis was associated with a selective upregulation of intestinal CB(1) receptors without affecting CB(2) receptor expression and with increased FAAH expression. The increase in FAAH expression was completely reversed by cannabidiol but not affected by AM251. Our results show that sepsis leads to an imbalance of the endocannabinoid system in the mouse intestine. Despite its proven anti-oxidant and anti-inflammatory properties, cannabidiol may be of limited use for the treatment of sepsis-induced ileus. PMID:18373655

  4. Drug: D04636 [KEGG MEDICUS

    Full Text Available D04636 Drug Isotretinoin anisatil (USAN) C29H36O4 448.2614 448.5937 D04636.gif Anti-acne, Keratolyti...6] [KO:K08527 K08528 K08529] map07223 Retinoic acid receptor (RAR) and retinoid X receptor (RXR) agonists/ant...c ATC code: D10AD04 D10BA01 Target: retinoic acid receptor (RAR) agonist [HSA:5914 5915 591...noic acid receptor (RAR) retinoic acid receptor [HSA:5914 5915...s for treatment of acne D10BA01 Isotretinoin D04636 Isotretinoin anisati

  5. Post-endocytotic Deubiquitination and Degradation of the Metabotropic γ-Aminobutyric Acid Receptor by the Ubiquitin-specific Protease 14.

    Lahaie, Nicolas; Kralikova, Michaela; Prézeau, Laurent; Blahos, Jaroslav; Bouvier, Michel

    2016-03-25

    Mechanisms controlling the metabotropic γ-aminobutyric acid receptor (GABAB) cell surface stability are still poorly understood. In contrast with many other G protein-coupled receptors (GPCR), it is not subject to agonist-promoted internalization, but is constitutively internalized and rapidly down-regulated. In search of novel interacting proteins regulating receptor fate, we report that the ubiquitin-specific protease 14 (USP14) interacts with the GABAB(1b)subunit's second intracellular loop. Probing the receptor for ubiquitination using bioluminescence resonance energy transfer (BRET), we detected a constitutive and phorbol 12-myristate 13-acetate (PMA)-induced ubiquitination of the receptor at the cell surface. PMA also increased internalization and accelerated receptor degradation. Overexpression of USP14 decreased ubiquitination while treatment with a small molecule inhibitor of the deubiquitinase (IU1) increased receptor ubiquitination. Treatment with the internalization inhibitor Dynasore blunted both USP14 and IU1 effects on the receptor ubiquitination state, suggesting a post-endocytic site of action. Overexpression of USP14 also led to an accelerated degradation of GABABin a catalytically independent fashion. We thus propose a model whereby cell surface ubiquitination precedes endocytosis, after which USP14 acts as an ubiquitin-binding protein that targets the ubiquitinated receptor to lysosomal degradation and promotes its deubiquitination. PMID:26817839

  6. Transplantation of Nogo-66 receptor gene-silenced cells in a poly(D,L-lactic-co-glycolic acid) scaffold for the treatment of spinal cord injury★

    Wang, Dong; Fan, Yuhong; Zhang, Jianjun

    2013-01-01

    Inhibition of neurite growth, which is in large part mediated by the Nogo-66 receptor, affects neural regeneration following bone marrow mesenchymal stem cell transplantation. The tissue engineering scaffold poly(D,L-lactide-co-glycolic acid) has good histocompatibility and can promote the growth of regenerating nerve fibers. The present study used small interfering RNA to silence Nogo-66 receptor gene expression in bone marrow mesenchymal stem cells and Schwann cells, which were subsequently...

  7. The autotaxin-lysophosphatidic acid–lysophosphatidic acid receptor cascade: proposal of a novel potential therapeutic target for treating glioblastoma multiforme

    Tabuchi, Sadaharu

    2015-01-01

    Glioblastoma multiforme (GBM) is the most malignant tumor of the central nervous system (CNS). Its prognosis is one of the worst among all cancer types, and it is considered a fatal malignancy, incurable with conventional therapeutic strategies. As the bioactive multifunctional lipid mediator lysophosphatidic acid (LPA) is well recognized to be involved in the tumorigenesis of cancers by acting on G-protein-coupled receptors, LPA receptor (LPAR) antagonists and LPA synthesis inhibitors have b...

  8. Caffeic Acid Phenethyl Ester Increases Radiosensitivity of Estrogen Receptor-Positive and -Negative Breast Cancer Cells by Prolonging Radiation-Induced DNA Damage

    Khoram, Nastaran Masoudi; Bigdeli, Bahareh; Nikoofar, Alireza; Goliaei, Bahram

    2016-01-01

    Purpose Breast cancer is an important cause of death among women. The development of radioresistance in breast cancer leads to recurrence after radiotherapy. Caffeic acid phenethyl ester (CAPE), a polyphenolic compound of honeybee propolis, is known to have anticancer properties. In this study, we examined whether CAPE enhanced the radiation sensitivity of MDA-MB-231 (estrogen receptor-negative) and T47D (estrogen receptor-positive) cell lines. Methods The cytotoxic effect of CAPE on MDA-MB-2...

  9. Neuronal gamma-aminobutyric acid (GABA) type A receptors undergo cognate ligand chaperoning in the endoplasmic reticulum by endogenous GABA

    Wang, Ping; Eshaq, Randa S.; Meshul, Charles K.; Moore, Cynthia; Hood, Rebecca L; Leidenheimer, Nancy J.

    2015-01-01

    GABAA receptors mediate fast inhibitory neurotransmission in the brain. Dysfunction of these receptors is associated with various psychiatric/neurological disorders and drugs targeting this receptor are widely used therapeutic agents. Both the efficacy and plasticity of GABAA receptor-mediated neurotransmission depends on the number of surface GABAA receptors. An understudied aspect of receptor cell surface expression is the post-translational regulation of receptor biogenesis within the endo...

  10. Covalent modification of mutant rat P2X2 receptors with a thiol-reactive fluorophore allows channel activation by zinc or acidic pH without ATP.

    Shlomo S Dellal

    Full Text Available Rat P2X2 receptors open at an undetectably low rate in the absence of ATP. Furthermore, two allosteric modulators, zinc and acidic pH, cannot by themselves open these channels. We describe here the properties of a mutant receptor, K69C, before and after treatment with the thiol-reactive fluorophore Alexa Fluor 546 C(5-maleimide (AM546. Xenopus oocytes expressing unmodified K69C were not activated under basal conditions nor by 1,000 µM ATP. AM546 treatment caused a small increase in the inward holding current which persisted on washout and control experiments demonstrated this current was due to ATP independent opening of the channels. Following AM546 treatment, zinc (100 µM or acidic external solution (pH 6.5 elicited inward currents when applied without any exogenous ATP. In the double mutant K69C/H319K, zinc elicited much larger inward currents, while acidic pH generated outward currents. Suramin, which is an antagonist of wild type receptors, behaved as an agonist at AM546-treated K69C receptors. Several other cysteine-reactive fluorophores tested on K69C did not cause these changes. These modified receptors show promise as a tool for studying the mechanisms of P2X receptor activation.

  11. Disseminated Exfoliative Dermatitis Associated with All-Transretinoic Acid in the Treatment of Acute Promyelocytic Leukemia

    Yonal Ipek

    2012-01-01

    Full Text Available Acute promyelocytic leukemia (APL is a biologically and clinically separate type of acute myeloid leukemia characterized by a translocation involving the retinoic acid receptor-alpha (RARa locus on chromosome 17, the great majority of which is t(15; 17(q24.1; q21.1 (Collins (1998, Melnick and Licht (1999, and Grimwade (1999. Retinoic acid is a critical ligand in the differentiation pathway of multiple tissues, mediated through binding to an RAR. All-trans retinoic acid (ATRA is a subgroup of the retinoid family, which induces complete remission (CR in APL by causing differentiation and apoptosis in immature malignant promyelocytes rather than inducing cell death by cytotoxicity (Warrell et al. (1993, Liu et al. (2000, and Cassinat et al. (2001. ATRA-associated toxicity consisting of headache, fever, weakness, fatigue, dry skin, dermatitis, gastrointestinal disorders, and hypertriglyceridemia has been shown to be mild (Kurzrock et al. (1993. Herein, we describe a patient with APL that developed an erythematous reaction of the whole body followed by desquamation and exfoliation during ATRA therapy.

  12. Fabrication of folic acid-sensitive gold nanoclusters for turn-on fluorescent imaging of overexpression of folate receptor in tumor cells.

    Li, Hongchang; Cheng, Yuqing; Liu, Yong; Chen, Bo

    2016-09-01

    Based on the fluorescence quenching of folic acid-sensitive bovine serum albumin-directed gold nanoclusters (BSA-AuNCs) via folic acid-induced the change of environment around BSA-AuNCs, we have constructed a turn on fluorescence imaging of folate receptor overexpressed tumor cells. In this paper, the primary fluorescence intensity of BSA-AuNCs was quenched via self-assembly of folic acid onto BSA-AuNCs to produce negligible fluorescence background, the linear range of the method was 0.1-100μg/mL with the limit of detection (LOD) of 30ng/mL (S/N=3); In the presence of overexpression of folate receptor on the surface of tumor cells, the primary fluorescence intensity of BSA-AuNCs turned on by folic acid desorbing from BSA-AuNCs, the linear range of method was 0.12-2μg/mL with the LOD of 20ng/mL (S/N=3). Additionally, due to specific and high affinity of folic acid and folate receptor, the probe had high selectivity for folate receptor, other interferences hardly changed the fluorescence intensity of the probe. Moreover, the text for cytotoxicity implied that the probe had no toxicity for tumor cells. Consequently, using the fluorescence probe, satisfactory results for the turn on imaging of folate receptor overexpressed tumor cells were obtained. A novel turn-on and red fluorescent probe for folate receptor overexpressed tumor cells was developed based on the recovery of fluorescence intensity of folic acid-sensitive BSA-AuNCs. PMID:27343585

  13. Gustducin couples fatty acid receptors to GLP-1 release in colon

    LI Yan; Kokrashvili, Zaza; Mosinger, Bedrich; Margolskee, Robert F.

    2013-01-01

    Sweet taste receptor subunits and α-gustducin found in enteroendocrine cells of the small intestine have been implicated in release of the incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) in response to glucose and noncaloric sweeteners. α-Gustducin has also been found in colon, although its function there is unclear. We examined expression of α-gustducin, GLP-1, and GIP throughout the intestine. The number of α-gustducin-expressing cell...

  14. Hrs Recognizes a Hydrophobic Amino Acid Cluster in Cytokine Receptors during Ubiquitin-independent Endosomal Sorting*

    Amano, Yuji; Yamashita, Yuki; Kojima, Katsuhiko; Yoshino, Kazuhisa; Tanaka, Nobuyuki; Sugamura, Kazuo; Takeshita, Toshikazu

    2011-01-01

    Hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) is a component of the ESCRT-0 protein complex that captures ubiquitylated cargo proteins and sorts them to the lysosomal pathway. Although Hrs acts as a key transporter for ubiquitin-dependent endosomal sorting, we previously reported that Hrs is also involved in ubiquitin-independent endosomal sorting of interleukin-2 receptor β (IL-2Rβ). Here, we show direct interactions between bacterially expressed Hrs and interleukin-4 re...

  15. Expression of the short chain fatty acid receptor GPR41/FFAR3 in autonomic and somatic sensory ganglia.

    Nøhr, M K; Egerod, K L; Christiansen, S H; Gille, A; Offermanns, S; Schwartz, T W; Møller, M

    2015-04-01

    G-protein-coupled receptor 41 (GPR41) also called free fatty acid receptor 3 (FFAR3) is a Gαi-coupled receptor activated by short-chain fatty acids (SCFAs) mainly produced from dietary complex carbohydrate fibers in the large intestine as products of fermentation by microbiota. FFAR3 is expressed in enteroendocrine cells, but has recently also been shown to be present in sympathetic neurons of the superior cervical ganglion. The aim of this study was to investigate whether the FFAR3 is present in other autonomic and sensory ganglia possibly influencing gut physiology. Cryostat sections were cut of autonomic and sensory ganglia of a transgenic reporter mouse expressing the monomeric red fluorescent protein (mRFP) gene under the control of the FFAR3 promoter. Control for specific expression was also done by immunohistochemistry with an antibody against the reporter protein. mRFP expression was as expected found not only in neurons of the superior cervical ganglion, but also in sympathetic ganglia of the thoracic and lumbar sympathetic trunk. Further, neurons in prevertebral ganglia expressed the mRFP reporter. FFAR3-mRFP-expressing neurons were also present in both autonomic and sensory ganglia such as the vagal ganglion, the spinal dorsal root ganglion and the trigeminal ganglion. No expression was observed in the brain or spinal cord. By use of radioactive-labeled antisense DNA probes, mRNA encoding the FFAR3 was found to be present in cells of the same ganglia. Further, the expression of the FFAR3 in the ganglia of the transgenic mice was confirmed by immunohistochemistry using an antibody directed against the receptor protein, and double labeling colocalized mRFP and the FFAR3-protein in the same neurons. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) on extracts from the ganglia supported the presence mRNA encoding the FFAR3 in most of the investigated tissues. These data indicate that FFAR3 is expressed on postganglionic sympathetic and

  16. Bile Acid-Induced Arrhythmia Is Mediated by Muscarinic M2 Receptors in Neonatal Rat Cardiomyocytes

    Sheikh Abdul Kadir, Siti H; Michele Miragoli; Shadi Abu-Hayyeh; Moshkov, Alexey V.; Qilian Xie; Verena Keitel; Viacheslav O. Nikolaev; Catherine Williamson; Julia Gorelik

    2010-01-01

    BACKGROUND: Intrahepatic cholestasis of pregnancy (ICP) is a common disease affecting up to 5% of pregnancies and which can cause fetal arrhythmia and sudden intrauterine death. We previously demonstrated that bile acid taurocholate (TC), which is raised in the bloodstream of ICP, can acutely alter the rate and rhythm of contraction and induce abnormal calcium destabilization in cultured neonatal rat cardiomyocytes (NRCM). Apart from their hepatic functions bile acids are ubiquitous signallin...

  17. Probing the orthosteric binding site of GABAA receptors with heterocyclic GABA carboxylic acid bioisosteres

    Petersen, Jette G; Bergmann, Rikke; Krogsgaard-Larsen, Povl; Balle, Thomas; Frølund, Bente

    2013-01-01

    selective and potent GABAAR agonists. This review investigates the use of heterocyclic carboxylic acid bioisosteres within the GABAAR area. Several heterocycles including 3-hydroxyisoxazole, 3-hydroxyisoxazoline, 3-hydroxyisothiazole, and the 1- and 3-hydroxypyrazole rings have been employed in order to map...... the orthosteric binding site. The physicochemical properties of the heterocyclic moieties making them suitable for bioisosteric replacement of the carboxylic acid in the molecule of GABA are discussed. A variety of synthetic strategies for synthesis of the heterocyclic scaffolds are available...

  18. Acidic Tumor Microenvironment and pH-Sensing G protein-Coupled Receptors

    Justus, Calvin R.; Lixue eDong; Yang, Li V.

    2013-01-01

    The tumor microenvironment is acidic due to glycolytic cancer cell metabolism, hypoxia, and deficient blood perfusion. It is proposed that acidosis in the tumor microenvironment is an important stress factor and selection force for cancer cell somatic evolution. Acidic pH has pleiotropic effects on the proliferation, migration, invasion, metastasis and therapeutic response of cancer cells and the function of immune cells, vascular cells, and other stromal cells. However, the molecular mechani...

  19. Acidic tumor microenvironment and pH-sensing G protein-coupled receptors

    Justus, Calvin R.; Dong, Lixue; Yang, Li V.

    2013-01-01

    The tumor microenvironment is acidic due to glycolytic cancer cell metabolism, hypoxia, and deficient blood perfusion. It is proposed that acidosis in the tumor microenvironment is an important stress factor and selection force for cancer cell somatic evolution. Acidic pH has pleiotropic effects on the proliferation, migration, invasion, metastasis, and therapeutic response of cancer cells and the function of immune cells, vascular cells, and other stromal cells. However, the molecular mechan...

  20. Conjugated bile acids promote cholangiocarcinoma cell invasive growth through activation of sphingosine 1-phosphate receptor 2

    Liu, Runping; Zhao, Renping; Zhou, Xiqiao; Liang, Xiuyin; Campbell, Deanna JW; Zhang, Xiaoxuan; ZHANG, LUYONG; Shi, Ruihua; Wang, Guangji; Pandak, William M.; Sirica, Alphonse E.; Hylemon, Phillip B.; Zhou, Huiping

    2014-01-01

    Cholangiocarcinoma (CCA) is an often fatal primary malignancy of the intra- and extrahepatic biliary tract that is commonly associated with chronic cholestasis and significantly elevated levels of primary and conjugated bile acids (CBAs), which are correlated with bile duct obstruction (BDO). BDO has also recently been shown to promote CCA progression. However, whereas there is increasing evidence linking chronic cholestasis and abnormal bile acid profiles to CCA development and progression, ...

  1. Taurolithocholic acid promotes intrahepatic cholangiocarcinoma cell growth via muscarinic acetylcholine receptor and EGFR/ERK1/2 signaling pathway

    AMONYINGCHAROEN, SUMET; SURIYO, TAWIT; THIANTANAWAT, APINYA; WATCHARASIT, PIYAJIT; SATAYAVIVAD, JUTAMAAD

    2015-01-01

    Cholangiocarcinoma (CCA) is a malignant cancer of the biliary tract and its occurrence is associated with chronic cholestasis which causes an elevation of bile acids in the liver and bile duct. The present study aimed to investigate the role and mechanistic effect of bile acids on the CCA cell growth. Intrahepatic CCA cell lines, RMCCA-1 and HuCCA-1, were treated with bile acids and their metabolites to determine the growth promoting effect. Cell viability, cell cycle analysis, EdU incorporation assays were conducted. Intracellular signaling proteins were detected by western immunoblotting. Among eleven forms of bile acids and their metabolites, only taurolithocholic acid (TLCA) concentration dependently (1–40 μM) increased the cell viability of RMCCA-1, but not HuCCA-1 cells. The cell cycle analysis showed induction of cells in the S phase and the EdU incorporation assay revealed induction of DNA synthesis in the TLCA-treated RMCCA-1 cells. Moreover, TLCA increased the phosphorylation of EGFR, ERK 1/2 and also increased the expression of cyclin D1 in RMCCA-1 cells. Furthermore, TLCA-induced RMCCA-1 cell growth could be inhibited by atropine, a non-selective muscarinic acetylcholine receptor (mAChR) antagonist, AG 1478, a specific EGFR inhibitor, or U 0126, a specific MEK 1/2 inhibitor. These results suggest that TLCA induces CCA cell growth via mAChR and EGFR/EKR1/2 signaling pathway. Moreover, the functional presence of cholinergic system plays a certain role in TLCA-induced CCA cell growth. PMID:25815516

  2. G Protein-Coupled Bile Acid Receptor TGR5 Activation Inhibits Kidney Disease in Obesity and Diabetes.

    Wang, Xiaoxin X; Edelstein, Michal Herman; Gafter, Uzi; Qiu, Liru; Luo, Yuhuan; Dobrinskikh, Evgenia; Lucia, Scott; Adorini, Luciano; D'Agati, Vivette D; Levi, Jonathan; Rosenberg, Avi; Kopp, Jeffrey B; Gius, David R; Saleem, Moin A; Levi, Moshe

    2016-05-01

    Obesity and diabetes mellitus are the leading causes of renal disease. In this study, we determined the regulation and role of the G protein-coupled bile acid receptor TGR5, previously shown to be regulated by high glucose and/or fatty acids, in obesity-related glomerulopathy (ORG) and diabetic nephropathy (DN). Treatment of diabetic db/db mice with the selective TGR5 agonist INT-777 decreased proteinuria, podocyte injury, mesangial expansion, fibrosis, and CD68 macrophage infiltration in the kidney. INT-777 also induced renal expression of master regulators of mitochondrial biogenesis, inhibitors of oxidative stress, and inducers of fatty acid β-oxidation, including sirtuin 1 (SIRT1), sirtuin 3 (SIRT3), and Nrf-1. Increased activity of SIRT3 was evidenced by normalization of the increased acetylation of mitochondrial superoxide dismutase 2 (SOD2) and isocitrate dehydrogenase 2 (IDH2) observed in untreated db/db mice. Accordingly, INT-777 decreased mitochondrial H2O2 generation and increased the activity of SOD2, which associated with decreased urinary levels of H2O2 and thiobarbituric acid reactive substances. Furthermore, INT-777 decreased renal lipid accumulation. INT-777 also prevented kidney disease in mice with diet-induced obesity. In human podocytes cultured with high glucose, INT-777 induced mitochondrial biogenesis, decreased oxidative stress, and increased fatty acid β-oxidation. Compared with normal kidney biopsy specimens, kidney specimens from patients with established ORG or DN expressed significantly less TGR5 mRNA, and levels inversely correlated with disease progression. Our results indicate that TGR5 activation induces mitochondrial biogenesis and prevents renal oxidative stress and lipid accumulation, establishing a role for TGR5 in inhibiting kidney disease in obesity and diabetes. PMID:26424786

  3. Subcellular distribution of N-methyl-D-aspartic acid receptor subunit 1 in neural stem cells within subventricular zone of adult rats

    Zhining Li; Wenlong Lü; Hongyan Dong; Hongbin Fan; Ruiguo Dong; Tiejun Xu

    2011-01-01

    The subcellular localization of N-methyl-D-aspartic acid receptor subunit 1 in neural stem cells of the subventricular zone of adult rats was detected using electron microscopy, following immunohistochemistry and immunogold-silver double staining. Results confirmed the presence of neural stem cells in the subventricular zone, which is a key neurogenic region in the central nervous system of adult mammals. The expression of N-methyl-D-aspartic acid receptor subunit 1 was higher than that of nestin and mainly distributed in the cell membrane, cytoplasm, rough endoplasmic reticulum and Golgi complex of neural stem cells.

  4. Altered expression of metabotropic glutamate receptor 1 alpha after acute diffuse brain injury Effect of the competitive antagonist 1-aminoindan-1, 5-dicarboxylic acid

    Fei Cao; Mantao Chen; Gu Li; Ke Ye; Xin Huang; Xiujue Zheng

    2012-01-01

    The diffuse brain injury model was conducted in Sprague-Dawley rats, according to Marmarou's free-fall attack. The water content in brain tissue, expression of metabotropic glutamate receptor 1α mRNA and protein were significantly increased after injury, reached a peak at 24 hours, and then gradually decreased. After treatment with the competitive antagonist of metabotropic glutamate receptor 1α, (RS)-1-aminoindan-1, 5-dicarboxylic acid, the water content of brain tissues decreased between 12-72 hours after injury, and neurological behaviors improved at 2 weeks. These experimental findings suggest that the 1-aminoindan-1, 5-dicarboxylic acid may result in marked neuroprotection against diffuse brain injury.

  5. Synthesis and evaluation of fatty acid amides on the N-oleoylethanolamide-like activation of peroxisome proliferator activated receptor α.

    Takao, Koichi; Noguchi, Kaori; Hashimoto, Yosuke; Shirahata, Akira; Sugita, Yoshiaki

    2015-01-01

    A series of fatty acid amides were synthesized and their peroxisome proliferator-activated receptor α (PPAR-α) agonistic activities were evaluated in a normal rat liver cell line, clone 9. The mRNAs of the PPAR-α downstream genes, carnitine-palmitoyltransferase-1 and mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase, were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR) as PPAR-α agonistic activities. We prepared nine oleic acid amides. Their PPAR-α agonistic activities were, in decreasing order, N-oleoylhistamine (OLHA), N-oleoylglycine, Oleamide, N-oleoyltyramine, N-oleoylsertonin, and Olvanil. The highest activity was found with OLHA. We prepared and evaluated nine N-acylhistamines (N-acyl-HAs). Of these, OLHA, C16:0-HA, and C18:1Δ(9)-trans-HA showed similar activity. Activity due to the different chain length of the saturated fatty acid peaked at C16:0-HA. The PPAR-α antagonist, GW6471, inhibited the induction of the PPAR-α downstream genes by OLHA and N-oleoylethanolamide (OEA). These data suggest that N-acyl-HAs could be considered new PPAR-α agonists. PMID:25832022

  6. Receptor-mediated radionuclide therapy with 90Y-DOTATOC in association with amino acid infusion: a phase I study

    The aim of this study was to determine the maximum tolerated dose of 90Y-DOTATOC per cycle administered in association with amino acid solution as kidney protection in patients with somatostatin receptor-positive tumours. Forty patients in eight groups received two cycles of 90Y-DOTATOC, with activity increased by 0.37 GBq per group, starting at 2.96 and terminating at 5.55 GBq. All patients received lysine ± arginine infusion immediately before and after therapy. Forty-eight percent developed acute grade I-II gastrointestinal toxicity (nausea and vomiting) after amino acid infusion whereas no acute adverse reactions occurred after 90Y-DOTATOC injection up to 5.55 GBq/cycle. Grade III haematological toxicity occurred in three of seven (43%) patients receiving 5.18 GBq, which was defined as the maximum tolerable activity per cycle. Objective therapeutic responses occurred. Five GBq per cycle is the recommended dosage of 90Y-DOTATOC when amino acids are given to protect the kidneys. Although no patients developed acute kidney toxicity, delayed kidney toxicity remains a major concern, limiting the cumulative dose to 25 Gy. The way forward with this treatment would seem to be to identify more effective renal protective agents, in order to be able to increase the cumulative injectable activity and hence tumour dose. (orig.)

  7. Characterization of duodenal expression and localization of fatty acid-sensing receptors in humans: relationships with body mass index.

    Little, Tanya J; Isaacs, Nicole J; Young, Richard L; Ott, Raffael; Nguyen, Nam Q; Rayner, Christopher K; Horowitz, Michael; Feinle-Bisset, Christine

    2014-11-15

    Fatty acids (FAs) stimulate the secretion of gastrointestinal hormones, including cholecystokinin (CCK) and glucagon like peptide-1 (GLP-1), which suppress energy intake. In obesity, gastrointestinal responses to FAs are attenuated. Recent studies have identified a key role for the FA-sensing receptors cluster of differentiation (CD)36, G protein-coupled receptor (GPR)40, GPR120, and GPR119 in mediating gastrointestinal hormone secretion. This study aimed to determine the expression and localization of these receptors in the duodenum of humans and to examine relationships with obesity. Duodenal mucosal biopsies were collected from nine lean [body mass index (BMI): 22 ± 1 kg/m2], six overweight (BMI: 28 ± 1 kg/m2), and seven obese (BMI: 49 ± 5 kg/m2) participants. Absolute levels of receptor transcripts were quantified using RT-PCR, while immunohistochemistry was used for localization. Transcripts were expressed in the duodenum of lean, overweight, and obese individuals with abundance of CD36>GPR40>GPR120>GPR119. Expression levels of GPR120 (r = 0.46, P = 0.03) and CD36 (r = 0.69, P = 0.0004) were directly correlated with BMI. There was an inverse correlation between expression of GPR119 with BMI (r2 = 0.26, P = 0.016). Immunolabeling studies localized CD36 to the brush border membrane of the duodenal mucosa and GPR40, GPR120, and GPR119 to enteroendocrine cells. The number of cells immunolabeled with CCK (r = -0.54, P = 0.03) and GLP-1 (r = -0.49, P = 0.045) was inversely correlated with BMI, such that duodenal CCK and GLP-1 cell density decreased with increasing BMI. In conclusion, CD36, GPR40, GPR120, and GPR119 are expressed in the human duodenum. Transcript levels of duodenal FA receptors and enteroendocrine cell density are altered with increasing BMI, suggesting that these changes may underlie decreased gastrointestinal hormone responses to fat and impaired energy intake regulation in obesity. PMID:25258406

  8. Short-chain free fatty acid receptors FFA2/GPR43 and FFA3/GPR41 as new potential therapeutic targets

    Trond eUlven

    2012-10-01

    Full Text Available The deorphanization of the free fatty acid (FFA receptors FFA1 (GPR40, FFA2 (GPR43, FFA3 (GPR41, GPR84 and GPR120 made clear that the body is capable of recognizing and responding directly to nonesterified fatty acid of virtually any chain length. Colonic fermentation of dietary fiber produces high concentrations of the short-chain fatty acids (SCFAs acetate, propionate and butyrate, a process which is important to health. The phylogenetically related 7-transmembrane receptors free fatty acid receptor 2 (FFA2 and FFA3 are activated by these SCFAs, and several lines of evidence indicate that FFA2 and FFA3 mediate beneficial effects associated with a fiber-rich diet, and that they may be of interest as targets for treatment of inflammatory and metabolic diseases. FFA2 is highly expressed on immune cells, in particular neutrophils, and several studies suggest that the receptor plays a role in diseases involving a dysfunctional neutrophil response, such as inflammatory bowel disease (IBD. Both FFA2 and FFA3 have been implicated in metabolic diseases such as type 2 diabetes and regulation of appetite. More research is however required to clarify potential of the receptors as drug targets and establish if activation or inhibition would be the preferred mode of action. The availability of potent and selective receptor modulators is a prerequisite for these studies. The few modulators of FFA2 or FFA3 that have been published hitherto in the peer-reviewed literature in general have properties that make them less than ideal as such tools, but published patent applications indicate that the situation may soon improve, and that proper tool compounds will enable studies critical to validate the receptors as new drug targets.

  9. Shape-complementarity in the recognition of tricarboxylic acids by a [3+3] polyazacyclophane receptor

    Hodačová, Jana; Chadim, Martin; Závada, Jiří; Aguilar, J.; García-Espaňa, E.; Luis, S. V.; Miravet, J. F.

    2005-01-01

    Roč. 70, č. 6 (2005), s. 2042-2047. ISSN 0022-3263 R&D Projects: GA ČR(CZ) GA203/01/0067 Grant ostatní: DGES(ES) BQ2003-0215-CO3; DGES(ES) GV-Grupos-03/196; DGES(ES) GV04B-225 Institutional research plan: CEZ:AV0Z4055905 Keywords : anion recognition * polyazacyclophane receptor Subject RIV: CC - Organic Chemistry Impact factor: 3.675, year: 2005

  10. Autotaxin and lysophosphatidic acid1 receptor-mediated demyelination of dorsal root fibers by sciatic nerve injury and intrathecal lysophosphatidylcholine

    Aoki Junken

    2010-11-01

    Full Text Available Abstract Background Although neuropathic pain is frequently observed in demyelinating diseases such as Guillain-Barré syndrome and multiple sclerosis, the molecular basis for the relationship between demyelination and neuropathic pain behaviors is poorly understood. Previously, we found that lysophosphatidic acid receptor (LPA1 signaling initiates sciatic nerve injury-induced neuropathic pain and demyelination. Results In the present study, we have demonstrated that sciatic nerve injury induces marked demyelination accompanied by myelin-associated glycoprotein (MAG down-regulation and damage of Schwann cell partitioning of C-fiber-containing Remak bundles in the sciatic nerve and dorsal root, but not in the spinal nerve. Demyelination, MAG down-regulation and Remak bundle damage in the dorsal root were abolished in LPA1 receptor-deficient (Lpar1-/- mice, but these alterations were not observed in sciatic nerve. However, LPA-induced demyelination in ex vivo experiments was observed in the sciatic nerve, spinal nerve and dorsal root, all which express LPA1 transcript and protein. Nerve injury-induced dorsal root demyelination was markedly attenuated in mice heterozygous for autotaxin (atx+/-, which converts lysophosphatidylcholine (LPC to LPA. Although the addition of LPC to ex vivo cultures of dorsal root fibers in the presence of recombinant ATX caused potent demyelination, it had no significant effect in the absence of ATX. On the other hand, intrathecal injection of LPC caused potent dorsal root demyelination, which was markedly attenuated or abolished in atx+/- or Lpar1-/- mice. Conclusions These results suggest that LPA, which is converted from LPC by ATX, activates LPA1 receptors and induces dorsal root demyelination following nerve injury, which causes neuropathic pain.

  11. Retinoic acid induces nuclear accumulation of Raf1 during differentiation of HL-60 cells

    Smith, James; Bunaciu, Rodica P.; Reiterer, Gudrun [Department of Biomedical Sciences, T4-008 VRT, Cornell University, Ithaca, NY 14853 (United States); Coder, David; George, Thaddeus [Amnis Corporation, Seattle, Washington (United States); Asaly, Michael [Department of Biomedical Sciences, T4-008 VRT, Cornell University, Ithaca, NY 14853 (United States); Yen, Andrew, E-mail: ay13@cornell.edu [Department of Biomedical Sciences, T4-008 VRT, Cornell University, Ithaca, NY 14853 (United States)

    2009-08-01

    All trans-retinoic acid (RA) is a standard therapeutic agent used in differentiation induction therapy treatment of acute promyelocytic leukemia (APL). RA and its metabolites use a diverse set of signal transduction pathways during the differentiation program. In addition to the direct transcriptional targets of the nuclear RAR and RXR receptors, signals derived from membrane receptors and the Raf-MEK-ERK pathway are required. Raf1 phosphorylation and the prolonged activation of Raf1 persisting during the entire differentiation process are required for RA-dependent differentiation of HL-60 cells. Here we identify a nuclear redistribution of Raf1 during the RA-induced differentiation of HL-60 cells. In addition, the nuclear accumulation of Raf1 correlates with an increase in Raf1 phosphorylated at serine 621. The serine 621 phosphorylated Raf1 is predominantly localized in the nucleus. The RA-dependent nuclear accumulation of Raf1 suggests a novel nuclear role for Raf1 during the differentiation process.

  12. Gamma-aminobutyric acid and GABAA receptors are involved in directional selectivity of pretectal neurons in pigeons

    2000-01-01

    The present study describes the effects of gamma-aminobutyric acid (GABA) and itsantagonists, bicuculline and 2-hydroxysaclofen, on visual responses of neurons in the pigeon nucleuslentiformis mesencephali (nLM). The results indicate that GABA significantly reduces bothspontaneous activity and visual responsiveness, and GABAA antagonist bicuculline but not GABABantagonist 2-hydroxysaclofen enhances visual responses of nLM cells examined. Furthermore,inhibition produced by motion in the null-direction of pretectal neurons is diminished by bicucullinebut not by 2-hydroxysaclofen. It is therefore concluded that the null-direction inhibition of directionalcells in the pigeon nLM is predominantly mediated by GABA and GABAA receptors. This inhibitionmay at least in part underlie directional asymmetry of optokinetic responses.

  13. Gamma-aminobutyric acid and GABA_A receptors are involved in directional selectivity of pretectal neurons in pigeons

    肖泉; 付煜西; 胡婧; 高洪峰; 王书荣

    2000-01-01

    The present study describes the effects of gamma-aminobutyric acid (GABA) and its antagonists, bicuculline and 2-hydroxysaclofen, on visual responses of neurons in the pigeon nucleus lentiformis mesencephali (nLM). The results indicate that GABA significantly reduces both spontaneous activity and visual responsiveness, and GABAA antagonist bicuculline but not GABAB antagonist 2-hydroxysaclofen enhances visual responses of nLM cells examined. Furthermore, inhibition produced by motion in the null-direction of pretectal neurons is diminished by bicuculline but not by 2-hydroxysaclofen. It is therefore concluded that the null-direction inhibition of directional cells in the pigeon nLM is predominantly mediated by GABA and GABAA receptors. This inhibition may at least in part underlie directional asymmetry of optokinetic responses.

  14. Mapping Substance P Binding Sites on the Neurokinin-1 Receptor Using Genetic Incorporation of a Photoreactive Amino Acid

    Valentin-Hansen, Louise; Park, Minyoung; Huber, Thomas;

    2014-01-01

    binding site for SP includes multiple domains in the N-terminal (Nt) segment and the second extracellular loop (ECLII) of NK1. To map precisely the NK1 residues that interact with SP, we applied a novel receptor-based targeted photocross-linking approach. We used amber codon suppression to introduce the...... photoreactive unnatural amino acid p-benzoyl-l-phenylalanine (BzF) at 11 selected individual positions in the Nt tail (residues 11-21) and 23 positions in the ECLII (residues 170(C-10)-193(C+13)) of NK1. The 34 NK1 variants were expressed in mammalian HEK293 cells and retained the ability to interact with a...

  15. Suppression of NMDA receptor function in mice prenatally exposed to valproic acid improves social deficits and repetitive behaviors

    Jaeseung eKang

    2015-05-01

    Full Text Available Animals prenatally exposed to valproic acid (VPA, an antiepileptic agent, have been used as a model for autism spectrum disorders (ASDs. Previous studies have identified enhanced NMDA receptor (NMDAR function in the brain of VPA rats, and demonstrated that pharmacological suppression of NMDAR function normalizes social deficits in these animals. However, whether repetitive behavior, another key feature of ASDs, can be rescued by NMDAR inhibition remains unknown. We report here that memantine, an NMDAR antagonist, administered to VPA mice rescues both social deficits and repetitive behaviors such as self-grooming and jumping. These results suggest that suppression of elevated NMDAR function in VPA animals normalizes repetitive behaviors in addition to social deficits.

  16. Silencing gamma-aminobutyric acid A receptor alpha 1 subunit expression and outward potassium current in developing cortical neurons

    Tao Bo; Jiang Li; Jian Li; Xingfang Li; Kaihui Xing

    2011-01-01

    We used RNA interference (RNAi) to disrupt synthesis of the cortical neuronal γ-aminobutyric acid A receptor (GABAAR) α1 in rats during development, and measured outward K+ currents during neuronal electrical activity using whole-cell patch-clamp techniques. Three pairs of small interfering RNA (siRNA) for GABAAR α1 subunit were designed using OligoEngine RNAi software. This siRNA was found to effectively inhibited GABAAR α1 mRNA expression in cortical neuronal culture in vitro, but did not significantly affect neuronal survival. Outward K+ currents were decreased, indicating that GABAAR α1 subunits in developing neurons participate in neuronal function by regulating outward K+ current.

  17. First molecular genotyping of A302S mutation in the gamma aminobutyric acid (GABA) receptor in Aedes albopictus from Malaysia.

    Low, V L; Vinnie-Siow, W Y; Lim Y, A L; Tan, T K; Leong, C S; Chen, C D; Azidah, A A; Sofian-Azirun, M

    2015-09-01

    Given the lack of molecular evidence in altered target-site insecticide resistance mechanism in Aedes albopictus (Skuse) worldwide, the present study aims to detect the presence of A302S mutation in the gene encoding the gamma aminobutyric acid receptor resistant to dieldrin (Rdl) in Ae. albopictus for the first time from its native range of South East Asia, namely Malaysia. World Health Organization (WHO) adult susceptibility bioassay indicated a relatively low level of dieldrin resistance (two-fold) in Ae. albopictus from Petaling Jaya, Selangor. However, PCR-RFLP and direct sequencing methods revealed the presence of the A302S mutation with the predomination of heterozygous genotype (40 out of 82 individuals), followed by the resistant genotype with 11 individuals. This study represents the first field evolved instance of A302S mutation in Malaysian insect species. PMID:26695218

  18. In vitro and mouse in vivo characterization of the potent free fatty acid 1 receptor agonist TUG-469

    Urban, C; Hamacher, A; Partke, H J;

    2013-01-01

    Activation of the G protein-coupled free fatty acid receptor 1 (FFA1; formerly known as GPR40) leads to an enhancement of glucose-stimulated insulin secretion from pancreatic β-cells. TUG-469 has previously been reported as a potent FFA1 agonist. This study was performed to confirm the higher in......120 (FFA4) expressing 1321N1 cells and the rat insulinoma cell line INS-1. Furthermore, we investigated the systemic effect of TUG-469 on glucose tolerance in pre-diabetic New Zealand obese (NZO) mice performing a glucose tolerance test after intraperitoneal administration of 5 mg/kg TUG-469. In...... significantly improved glucose tolerance in pre-diabetic NZO mice. TUG-469 turned out as a promising candidate for further drug development of FFA1 agonists for treatment of type 2 diabetes mellitus....

  19. Nucleic acid sequences encoding D1 and D1/D2 domains of human coxsackievirus and adenovirus receptor (CAR)

    Freimuth, Paul I.

    2010-04-06

    The invention provides recombinant human CAR (coxsackievirus and adenovirus receptor) polypeptides which bind adenovirus. Specifically, polypeptides corresponding to adenovirus binding domain D1 and the entire extracellular domain of human CAR protein comprising D1 and D2 are provided. In another aspect, the invention provides nucleic acid sequences encoding these domains and expression vectors for producing the domains and bacterial cells containing such vectors. The invention also includes an isolated fusion protein comprised of the D1 polypeptide fused to a polypeptide which facilitates folding of D1 when expressed in bacteria. The functional D1 domain finds application in a therapeutic method for treating a patient infected with a CAR D1-binding virus, and also in a method for identifying an antiviral compound which interferes with viral attachment. The invention also provides a method for specifically targeting a cell for infection by a virus which binds to D1.

  20. The excitatory amino acid receptor antagonist MK-801 prevents the hypersensitivity induced by spinal cord ischemia in the rat

    Protection by the NMDA receptor antagonist MK-801 against transient spinal cord ischemia-induced hypersensitivity was studied in rats. The spinal ischemia was initiated by vascular occlusion resulting from the interaction between the photosensitizing dye Erythrosin B and an argon laser beam. The hypersensitivity, termed allodynia, where the animals reacted by vocalization to nonnoxious mechanical stimuli in the flank area, was consistently observed during several days after induction of the ischemia. Pretreatment with MK-801 (0.1-0.5 mg/kg, iv) 10 min before laser irradiation dose dependently prevented the occurrence of allodynia. The neuroprotective effect of MK-801 was not reduced by maintaining normal body temperature during and after irradiation. There was a significant negative correlation between the delay in the administration of MK-801 after irradiation and the protective effect of the drug. Histological examination revealed slight morphological damage in the spinal cord in 38% of control rats after 1 min of laser irradiation without pretreatment with MK-801. No morphological abnormalities were observed in rats after pretreatment with MK-801 (0.5 mg/kg). The present results provide further evidence for the involvement of excitatory amino acids, through activation of the NMDA receptor, in the development of dysfunction following ischemic trauma to the spinal cord