1
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Matsingos C, Howell LA, McCormick PJ, Fornili A. Elucidating the Activation Mechanism of the Proton-sensing GPR68 Receptor. J Mol Biol 2024; 436:168688. [PMID: 38936694 DOI: 10.1016/j.jmb.2024.168688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 06/08/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024]
Abstract
GPR68 is a proton-sensing G-protein Coupled Receptor (GPCR) involved in a variety of physiological processes and disorders including neoplastic pathologies. While GPR68 and few other GPCRs have been shown to be activated by a decrease in the extracellular pH, the molecular mechanism of their activation remains largely unknown. In this work, we used a combined computational and in vitro approach to provide new insight into the activation mechanism of the receptor. Molecular Dynamics simulations of GPR68 were used to model the changes in residue interactions and motions triggered by pH. Global and local rearrangements consistent with partial activation were observed upon protonation of the inactive state. Selected extracellular histidine and transmembrane acidic residues were found to have significantly upshifted pKa values during the simulations, consistently with their previously hypothesised role in activation through changes in protonation state. Moreover, a novel pairing between histidine and acidic residues in the extracellular region was highlighted by both sequence analyses and simulation data and tested through site-directed mutagenesis. At last, we identified a previously unknown hydrophobic lock in the extracellular region that might stabilise the inactive conformation and regulate the transition to the active state.
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Affiliation(s)
- Christos Matsingos
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
| | - Lesley A Howell
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, United Kingdom
| | - Peter J McCormick
- Centre for Endocrinology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, United Kingdom; Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool L69 7BE, United Kingdom
| | - Arianna Fornili
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
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2
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Zhang Z, Chen M, Zhan W, Chen Y, Wang T, Chen Z, Fu Y, Zhao G, Mao D, Ruan J, Yuan FL. Acid-sensing ion channel 1a modulation of apoptosis in acidosis-related diseases: implications for therapeutic intervention. Cell Death Discov 2023; 9:330. [PMID: 37666823 PMCID: PMC10477349 DOI: 10.1038/s41420-023-01624-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/28/2023] [Accepted: 08/22/2023] [Indexed: 09/06/2023] Open
Abstract
Acid-sensing ion channel 1a (ASIC1a), a prominent member of the acid-sensing ion channel (ASIC) superfamily activated by extracellular protons, is ubiquitously expressed throughout the human body, including the nervous system and peripheral tissues. Excessive accumulation of Ca2+ ions via ASIC1a activation may occur in the acidified microenvironment of blood or local tissues. ASIC1a-mediated Ca2+‑induced apoptosis has been implicated in numerous pathologies, including neurological disorders, cancer, and rheumatoid arthritis. This review summarizes the role of ASIC1a in the modulation of apoptosis via various signaling pathways across different disease states to provide insights for future studies on the underlying mechanisms and development of therapeutic strategies.
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Affiliation(s)
- Zhenyu Zhang
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Minnan Chen
- Nantong First People's Hospital, Nantong, 226001, China
| | - Wenjing Zhan
- The Key Laboratory of Anti-Inflammatory and Immune Medicine, Anhui Medical University, Hefei, 230032, China
| | - Yuechun Chen
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Tongtong Wang
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Zhonghua Chen
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Yifei Fu
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Gang Zhao
- Orthopaedic Institute, Wuxi 9th People's Hospital Affiliated to Soochow University, Wuxi, 214062, China
| | - Dong Mao
- Orthopaedic Institute, Wuxi 9th People's Hospital Affiliated to Soochow University, Wuxi, 214062, China.
| | - Jingjing Ruan
- Nantong First People's Hospital, Nantong, 226001, China.
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, People's Republic of China.
| | - Feng-Lai Yuan
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China.
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3
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Postić S, Gosak M, Tsai WH, Pfabe J, Sarikas S, Stožer A, Korošak D, Yang SB, Slak Rupnik M. pH-Dependence of Glucose-Dependent Activity of Beta Cell Networks in Acute Mouse Pancreatic Tissue Slice. Front Endocrinol (Lausanne) 2022; 13:916688. [PMID: 35837307 PMCID: PMC9273738 DOI: 10.3389/fendo.2022.916688] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 05/24/2022] [Indexed: 12/01/2022] Open
Abstract
Extracellular pH has the potential to affect various aspects of the pancreatic beta cell function. To explain this effect, a number of mechanisms was proposed involving both extracellular and intracellular targets and pathways. Here, we focus on reassessing the influence of extracellular pH on glucose-dependent beta cell activation and collective activity in physiological conditions. To this end we employed mouse pancreatic tissue slices to perform high-temporally resolved functional imaging of cytosolic Ca2+ oscillations. We investigated the effect of either physiological H+ excess or depletion on the activation properties as well as on the collective activity of beta cell in an islet. Our results indicate that lowered pH invokes activation of a subset of beta cells in substimulatory glucose concentrations, enhances the average activity of beta cells, and alters the beta cell network properties in an islet. The enhanced average activity of beta cells was determined indirectly utilizing cytosolic Ca2+ imaging, while direct measuring of insulin secretion confirmed that this enhanced activity is accompanied by a higher insulin release. Furthermore, reduced functional connectivity and higher functional segregation at lower pH, both signs of a reduced intercellular communication, do not necessary result in an impaired insulin release.
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Affiliation(s)
- Sandra Postić
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- *Correspondence: Sandra Postić,
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Wen-Hao Tsai
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Johannes Pfabe
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Srdjan Sarikas
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Dean Korošak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Shi-Bing Yang
- Taiwan International Graduate Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Marjan Slak Rupnik
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea – European Center Maribor, Maribor, Slovenia
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4
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Rowe JB, Kapolka NJ, Taghon GJ, Morgan WM, Isom DG. The evolution and mechanism of GPCR proton sensing. J Biol Chem 2021; 296:100167. [PMID: 33478938 PMCID: PMC7948426 DOI: 10.1074/jbc.ra120.016352] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/02/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022] Open
Abstract
Of the 800 G protein-coupled receptors (GPCRs) in humans, only three (GPR4, GPR65, and GPR68) regulate signaling in acidified microenvironments by sensing protons (H+). How these receptors have uniquely obtained this ability is unknown. Here, we show these receptors evolved the capability to sense H+ signals by acquiring buried acidic residues. Using our informatics platform pHinder, we identified a triad of buried acidic residues shared by all three receptors, a feature distinct from all other human GPCRs. Phylogenetic analysis shows the triad emerged in GPR65, the immediate ancestor of GPR4 and GPR68. To understand the evolutionary and mechanistic importance of these triad residues, we developed deep variant profiling, a yeast-based technology that utilizes high-throughput CRISPR to build and profile large libraries of GPCR variants. Using deep variant profiling and GPCR assays in HEK293 cells, we assessed the pH-sensing contributions of each triad residue in all three receptors. As predicted by our calculations, most triad mutations had profound effects consistent with direct regulation of receptor pH sensing. In addition, we found that an allosteric modulator of many class A GPCRs, Na+, synergistically regulated pH sensing by maintaining the pKa values of triad residues within the physiologically relevant pH range. As such, we show that all three receptors function as coincidence detectors of H+ and Na+. Taken together, these findings elucidate the molecular evolution and long-sought mechanism of GPR4, GPR65, and GPR68 pH sensing and provide pH-insensitive variants that should be valuable for assessing the therapeutic potential and (patho)physiological importance of GPCR pH sensing.
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Affiliation(s)
- Jacob B Rowe
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Nicholas J Kapolka
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Geoffrey J Taghon
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - William M Morgan
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Daniel G Isom
- The Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA; The Department of Tumor Biology, University of Miami Sylvester Comprehensive Cancer Center, Miami, Florida, USA; The Institute for Data Science Computing, University of Miami, Coral Gables, Florida, USA.
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5
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Huang XP, Kenakin TP, Gu S, Shoichet BK, Roth BL. Differential Roles of Extracellular Histidine Residues of GPR68 for Proton-Sensing and Allosteric Modulation by Divalent Metal Ions. Biochemistry 2020; 59:3594-3614. [PMID: 32865988 DOI: 10.1021/acs.biochem.0c00576] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
GPR68, an orphan G-protein coupled receptor, senses protons, couples to multiple G-proteins, and is also activated or inhibited by divalent metal ions. It has seven extracellular histidine residues, although it is not clear how these histidine residues play a role in both proton-sensing and metal ion modulation. Here we demonstrate that divalent metal ions are allosteric modulators that can activate or inhibit proton activity in a concentration- and pH-dependent manner. We then show that single histidine mutants have differential and varying degrees of effects on proton-sensing and metal ion modulation. Some histidine residues play dual roles in proton-sensing and metal ion modulation, while others are important in one or the other but not both. Two extracellular disulfide bonds are predicted to constrain histidine residues to be spatially close to each other. Combining histidine mutations leads to reduced proton activity and resistance to metal ion modulation, while breaking the less conserved disulfide bond results in a more severe reduction in proton-sensing over metal modulation. The small-molecule positive allosteric modulators (PAMs) ogerin and lorazepam are not affected by these mutations and remain active at mutants with severely reduced proton activity or are resistant to metal ion modulation. These results suggest GPR68 possesses two independent allosteric modulation systems, one through interaction with divalent metal ions at the extracellular surface and another through small-molecule PAMs in the transmembrane domains. A new GPR68 model is developed to accommodate the findings which could serve as a template for further studies and ligand discovery by virtual ligand docking.
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Affiliation(s)
| | | | - Shuo Gu
- Department of Pharmaceutical Science, University of California, San Francisco, California 94158, United States
| | - Brian K Shoichet
- Department of Pharmaceutical Science, University of California, San Francisco, California 94158, United States
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6
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He X, Hawkins C, Lawley L, Freeman K, Phan TM, Zhang J, Xu Y, Fang J. Whole body deletion of Gpr68 does not change hematopoietic stem cell function. Stem Cell Res 2020; 47:101869. [PMID: 32592951 PMCID: PMC7749853 DOI: 10.1016/j.scr.2020.101869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 05/21/2020] [Accepted: 05/29/2020] [Indexed: 11/17/2022] Open
Abstract
G protein-coupled receptor 68 (GPR68) responds to extracellular protons, thus called the proton-sensing G protein-coupled receptor (GPCR), leading to activation of the phospholipase C-β (PLCβ)/calcium (Ca2+) pathway or the adenylyl cyclase (AC)/cyclic AMP (cAMP) pathway. We recently found that whole body deletion of Gpr68 (Gpr68-/- mice) reduced the number of B lymphocytes with age and during hematopoietic regeneration, such as in response to fluorouracil (5-FU) administration. This prompted us to characterize the hematopoietic stem cell (HSC) phenotype in Gpr68-/- mice. Despite high level of Gpr68 protein expression on HSC in bone marrow (BM), the pool size of HSC was unaltered in Gpr68-/- mice either under steady state or upon stress, including aging and 5-FU treatment. HSC from Gpr68-/- mice exhibited comparable cellular features, such as cell cycle quiescence and cell survival. HSC from Gpr68-/- mice also exhibited comparable competitiveness after serial transplantation. Surprisingly, cytosolic Ca2+ accumulation was increased in HSC from Gpr68-/- mice. In contrast, cAMP levels were reduced in hematopoietic stem and progenitor cells (HSPC) from Gpr68-/- mice. Intriguingly, we found high level of Gpr68 protein expression on non-hematopoietic cells in BM, especially endothelial cells that function as HSC niche. In addition, expression of other proton-sensing GPCR was upregulated in HSPC from Gpr68-/- mice. Our studies suggest that Gpr68-/- mice display insignificant phenotype on HSC biology, possibly due to the function of Gpr68 in non-hematopoietic cells and/or the compensatory effects from other proton-sensing GPCR.
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Affiliation(s)
- Xiaofei He
- Department of Drug Discovery and Biomedical Sciences, University of South Carolina College of Pharmacy, Columbia, SC, USA
| | - Caleb Hawkins
- Department of Drug Discovery and Biomedical Sciences, University of South Carolina College of Pharmacy, Columbia, SC, USA
| | - Lauren Lawley
- Department of Drug Discovery and Biomedical Sciences, University of South Carolina College of Pharmacy, Columbia, SC, USA
| | - Kennedy Freeman
- Department of Drug Discovery and Biomedical Sciences, University of South Carolina College of Pharmacy, Columbia, SC, USA
| | - Tra Mi Phan
- Department of Drug Discovery and Biomedical Sciences, University of South Carolina College of Pharmacy, Columbia, SC, USA
| | - Jiajia Zhang
- Department of Epidemiology and Biostatistics, University of South Carolina Arnold School of Public Health, Columbia, SC, USA
| | - Yan Xu
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jing Fang
- Department of Drug Discovery and Biomedical Sciences, University of South Carolina College of Pharmacy, Columbia, SC, USA.
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7
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Musha S, Yoshida S, Murakami S, Kojima R, Deai M, Saso N, Mogi C, Sato K, Okajima F, Tomura H. Involvement of GPR4 in increased growth hormone and prolactin expressions by extracellular acidification in MtT/S cells. J Reprod Dev 2020; 66:175-180. [PMID: 31956173 PMCID: PMC7175386 DOI: 10.1262/jrd.2019-159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hormone-secreting pituitary adenomas show unregulated hormonal hypersecretion and cause hyperpituitarism. However, the mechanism of the unregulated hormone production and secretion has not
yet been fully elucidated. Solid tumors show reduced extracellular pH, partly due to lactate secretion from anaerobic glycolysis. It is known that extracellular acidification affects hormone
secretion. However, whether and how the extracellular acidification influences the unregulated hormone production and secretion remain unknown. In the present study, we found that
GPR4, a proton-sensing G protein-coupled receptor, was highly expressed in MtT/S cells, a growth hormone-producing and prolactin-producing pituitary tumor cell line. When
we reduced the extracellular pH, growth hormone and prolactin mRNA expressions increased in the cells. Both increased expressions were partially suppressed
by a GPR4 antagonist. We also found that extracellular acidification enhanced growth hormone-releasing factor-induced growth hormone secretion from MtT/S cells. These results suggest that
GPR4 may play a role in hypersecretion of the hormone from hormone-producing pituitary tumors. A GPR4 antagonist will be a useful tool for preventing the hypersecretion.
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Affiliation(s)
- Shiori Musha
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Saishu Yoshida
- Department of Biochemistry, Jikei University School of Medicine, Tokyo 105-8461, Japan
| | - Syo Murakami
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Ryotaro Kojima
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Masahito Deai
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Naoshi Saso
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Chihiro Mogi
- Laboratory of Integrated Signaling Systems, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Koichi Sato
- Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Fumikazu Okajima
- Laboratory of Pathophysiology, Faculty of Pharmacy, Aomori University, Aomori 030-0943, Japan
| | - Hideaki Tomura
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan.,Institute of Endocrinology, Meiji University, Kawasaki 214-8571, Japan
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8
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Yu X, Huang XP, Kenakin TP, Slocum ST, Chen X, Martini ML, Liu J, Jin J. Design, Synthesis, and Characterization of Ogerin-Based Positive Allosteric Modulators for G Protein-Coupled Receptor 68 (GPR68). J Med Chem 2019; 62:7557-7574. [PMID: 31298539 DOI: 10.1021/acs.jmedchem.9b00869] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
G protein-coupled receptor 68 (GPR68) is an understudied orphan G protein-coupled receptor (GPCR). It is expressed most abundantly in the brain, potentially playing important roles in learning and memory. Pharmacological studies with GPR68 have been hindered by lack of chemical tools that can selectively modulate its activity. We previously reported the first small-molecule positive allosteric modulator (PAM), ogerin (1), and showed that 1 can potentiate proton activity at the GPR68-Gs pathway. Here, we report the first comprehensive structure-activity relationship (SAR) study on the scaffold of 1. Our lead compound resulted from this study, MS48107 (71), displayed 33-fold increased allosteric activity compared to 1. Compound 71 demonstrated high selectivity over closely related proton GPCRs and 48 common drug targets, and was bioavailable and brain-penetrant in mice. Thus, our SAR study has resulted in an improved GPR68 PAM for investigating the physiological and pathophysiological roles of GPR68 in vitro and in vivo.
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Affiliation(s)
- Xufen Yu
- Mount Sinai Center for Therapeutics Discovery, Departments of Pharmacological Sciences and Oncological Sciences, Tisch Cancer Institute , Icahn School of Medicine at Mount Sinai , New York , New York 10029 , United States
| | | | | | | | - Xin Chen
- Mount Sinai Center for Therapeutics Discovery, Departments of Pharmacological Sciences and Oncological Sciences, Tisch Cancer Institute , Icahn School of Medicine at Mount Sinai , New York , New York 10029 , United States
| | - Michael L Martini
- Mount Sinai Center for Therapeutics Discovery, Departments of Pharmacological Sciences and Oncological Sciences, Tisch Cancer Institute , Icahn School of Medicine at Mount Sinai , New York , New York 10029 , United States
| | - Jing Liu
- Mount Sinai Center for Therapeutics Discovery, Departments of Pharmacological Sciences and Oncological Sciences, Tisch Cancer Institute , Icahn School of Medicine at Mount Sinai , New York , New York 10029 , United States
| | - Jian Jin
- Mount Sinai Center for Therapeutics Discovery, Departments of Pharmacological Sciences and Oncological Sciences, Tisch Cancer Institute , Icahn School of Medicine at Mount Sinai , New York , New York 10029 , United States
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9
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Wiley SZ, Sriram K, Salmerón C, Insel PA. GPR68: An Emerging Drug Target in Cancer. Int J Mol Sci 2019; 20:E559. [PMID: 30696114 PMCID: PMC6386835 DOI: 10.3390/ijms20030559] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/19/2022] Open
Abstract
GPR68 (or ovarian cancer G protein-coupled receptor 1, OGR1) is a proton-sensing G-protein-coupled receptor (GPCR) that responds to extracellular acidity and regulates a variety of cellular functions. Acidosis is considered a defining hallmark of the tumor microenvironment (TME). GPR68 expression is highly upregulated in numerous types of cancer. Emerging evidence has revealed that GPR68 may play crucial roles in tumor biology, including tumorigenesis, tumor growth, and metastasis. This review summarizes current knowledge regarding GPR68-its expression, regulation, signaling pathways, physiological roles, and functions it regulates in human cancers (including prostate, colon and pancreatic cancer, melanoma, medulloblastoma, and myelodysplastic syndrome). The findings provide evidence for GPR68 as a potentially novel therapeutic target but in addition, we note challenges in developing drugs that target GPR68.
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Affiliation(s)
- Shu Z Wiley
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Krishna Sriram
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Cristina Salmerón
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Paul A Insel
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093, USA.
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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10
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Tcymbarevich IV, Eloranta JJ, Rossel JB, Obialo N, Spalinger M, Cosin-Roger J, Lang S, Kullak-Ublick GA, Wagner CA, Scharl M, Seuwen K, Ruiz PA, Rogler G, de Vallière C, Misselwitz B. The impact of the rs8005161 polymorphism on G protein-coupled receptor GPR65 (TDAG8) pH-associated activation in intestinal inflammation. BMC Gastroenterol 2019; 19:2. [PMID: 30616622 PMCID: PMC6323805 DOI: 10.1186/s12876-018-0922-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 12/20/2018] [Indexed: 12/15/2022] Open
Abstract
Background Tissue inflammation in inflammatory bowel diseases (IBD) is associated with a decrease in local pH. The gene encoding G-protein-coupled receptor 65 (GPR65) has recently been reported to be a genetic risk factor for IBD. In response to extracellular acidification, proton activation of GPR65 stimulates cAMP and Rho signalling pathways. We aimed to analyse the clinical and functional relevance of the GPR65 associated single nucleotide polymorphism (SNP) rs8005161. Methods 1138 individuals from a mixed cohort of IBD patients and healthy volunteers were genotyped for SNPs associated with GPR65 (rs8005161, rs3742704) and galactosylceramidase (rs1805078) by Taqman SNP assays. 2300 patients from the Swiss IBD Cohort Study (SIBDC) were genotyped for rs8005161 by mass spectrometry based SNP genotyping. IBD patients from the SIBDC carrying rs8005161 TT, CT, CC and non-IBD controls (CC) were recruited for functional studies. Human CD14+ cells were isolated from blood samples and subjected to an extracellular acidic pH shift, cAMP accumulation and RhoA activation were measured. Results In our mixed cohort, but not in SIBDC patients, the minor variant rs8005161 was significantly associated with UC. In SIBDC patients, we observed a consistent trend in increased disease severity in patients carrying the rs8005161-TT and rs8005161-CT alleles. No significant differences were observed in the pH associated activation of cAMP production between IBD (TT, CT, WT/CC) and non-IBD (WT/CC) genotype carriers upon an acidic extracellular pH shift. However, we observed significantly impaired RhoA activation after an extracellular acidic pH shift in IBD patients, irrespective of the rs8005161 allele. Conclusions The T allele of rs8005161 might confer a more severe disease course in IBD patients. Human monocytes from IBD patients showed impaired pH associated RhoA activation upon an acidic pH shift. Electronic supplementary material The online version of this article (10.1186/s12876-018-0922-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Irina V Tcymbarevich
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Jyrki J Eloranta
- Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | | | - Nicole Obialo
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Marianne Spalinger
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Jesus Cosin-Roger
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Silvia Lang
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Gerd A Kullak-Ublick
- Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Michael Scharl
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Klaus Seuwen
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Pedro A Ruiz
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Gerhard Rogler
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Cheryl de Vallière
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
| | - Benjamin Misselwitz
- Department of Gastroenterology and Hepatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland. .,Present address: Department of Viceral Surgery and Medicine, Inselspital Bern and University of Bern, Freiburgstr. 18, 3010, Bern, Switzerland.
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11
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Baldini N, Avnet S. The Effects of Systemic and Local Acidosis on Insulin Resistance and Signaling. Int J Mol Sci 2018; 20:ijms20010126. [PMID: 30598026 PMCID: PMC6337415 DOI: 10.3390/ijms20010126] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 12/12/2018] [Accepted: 12/23/2018] [Indexed: 12/14/2022] Open
Abstract
Most pathological conditions that cause local or systemic acidosis by overcoming the buffering activities of body fluids overlap with those diseases that are characterized by glucose metabolic disorders, including diabetes mellitus, inflammation, and cancer. This simple observation suggests the existence of a strong relationship between acidosis and insulin metabolism or insulin receptor signaling. In this review, we summarized the current knowledge on the activity of insulin on the induction of acidosis and, vice versa, on the effects of changes of extracellular and intracellular pH on insulin resistance. Insulin influences acidosis by promoting glycolysis. Although with an unclear mechanism, the lowering of pH, in turn, inhibits insulin sensitivity or activity. In addition to ketoacidosis that is frequently associated with diabetes, other important and more complex factors are involved in this delicate feedback mechanism. Among these, in this review we discussed the acid-mediated inhibiting effects on insulin binding affinity to its receptor, on glycolysis, on the recycling of glucose transporters, and on insulin secretion via transforming growth factor β (TGF-β) activity by pancreatic β-cells. Finally, we revised current data available on the mutual interaction between insulin signaling and the activity of ion/proton transporters and pH sensors, and on how acidosis may enhance insulin resistance through the Nuclear Factor kappa B (NF-κB) inflammatory pathway.
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Affiliation(s)
- Nicola Baldini
- Orthopaedic Pathophysiology and Regenerative Medicine Unit, Istituto Ortopedico Rizzoli IRCCS, 40136 Bologna, Italy.
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 401223 Bologna, Italy.
| | - Sofia Avnet
- Orthopaedic Pathophysiology and Regenerative Medicine Unit, Istituto Ortopedico Rizzoli IRCCS, 40136 Bologna, Italy.
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12
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Tao SC, Gao YS, Zhu HY, Yin JH, Chen YX, Zhang YL, Guo SC, Zhang CQ. Decreased extracellular pH inhibits osteogenesis through proton-sensing GPR4-mediated suppression of yes-associated protein. Sci Rep 2016; 6:26835. [PMID: 27256071 PMCID: PMC4891712 DOI: 10.1038/srep26835] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 05/09/2016] [Indexed: 12/27/2022] Open
Abstract
The pH of extracellular fluids is a basic property of the tissue microenvironment and is normally maintained at 7.40 ± 0.05 in humans. Many pathological circumstances, such as ischemia, inflammation, and tumorigenesis, result in the reduction of extracellular pH in the affected tissues. In this study, we reported that the osteogenic differentiation of BMSCs was significantly inhibited by decreases in the extracellular pH. Moreover, we demonstrated that proton-sensing GPR4 signaling mediated the proton-induced inhibitory effects on the osteogenesis of BMSCs. Additionally, we found that YAP was the downstream effector of GPR4 signaling. Our findings revealed that the extracellular pH modulates the osteogenic responses of BMSCs by regulating the proton-sensing GPR4-YAP pathway.
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Affiliation(s)
- Shi-Cong Tao
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - You-Shui Gao
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Hong-Yi Zhu
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Jun-Hui Yin
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Yi-Xuan Chen
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Yue-Lei Zhang
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Shang-Chun Guo
- Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Chang-Qing Zhang
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China.,Institute of Microsurgery on Extremities, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
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13
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Chandra V, Karamitri A, Richards P, Cormier F, Ramond C, Jockers R, Armanet M, Albagli-Curiel O, Scharfmann R. Extracellular acidification stimulates GPR68 mediated IL-8 production in human pancreatic β cells. Sci Rep 2016; 6:25765. [PMID: 27166427 PMCID: PMC4863151 DOI: 10.1038/srep25765] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/22/2016] [Indexed: 02/07/2023] Open
Abstract
Acute or chronic metabolic complications such as diabetic ketoacidosis are often associated with extracellular acidification and pancreatic β-cell dysfunction. However, the mechanisms by which human β-cells sense and respond to acidic pH remain elusive. In this study, using the recently developed human β-cell line EndoC-βH2, we demonstrate that β-cells respond to extracellular acidification through GPR68, which is the predominant proton sensing receptor of human β-cells. Using gain- and loss-of-function studies, we provide evidence that the β-cell enriched transcription factor RFX6 is a major regulator of GPR68. Further, we show that acidic pH stimulates the production and secretion of the chemokine IL-8 by β-cells through NF-кB activation. Blocking of GPR68 or NF-кB activity severely attenuated acidification induced IL-8 production. Thus, we provide mechanistic insights into GPR68 mediated β-cell response to acidic microenvironment, which could be a new target to protect β-cell against acidosis induced inflammation.
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Affiliation(s)
- Vikash Chandra
- INSERM, U1016, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, 75014, France
| | - Angeliki Karamitri
- INSERM, U1016, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, 75014, France
| | - Paul Richards
- INSERM, U1016, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, 75014, France
| | - Françoise Cormier
- INSERM, U1016, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, 75014, France
| | - Cyrille Ramond
- INSERM, U1016, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, 75014, France
| | - Ralf Jockers
- INSERM, U1016, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, 75014, France
| | - Mathieu Armanet
- Cell Therapy Unit, Hôpital Saint Louis, AP-HP, and University Paris-Diderot, Paris, 75010, France
| | - Olivier Albagli-Curiel
- INSERM, U1016, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, 75014, France
| | - Raphael Scharfmann
- INSERM, U1016, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, 75014, France
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14
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Zhu H, Guo S, Zhang Y, Yin J, Yin W, Tao S, Wang Y, Zhang C. Proton-sensing GPCR-YAP Signalling Promotes Cancer-associated Fibroblast Activation of Mesenchymal Stem Cells. Int J Biol Sci 2016; 12:389-96. [PMID: 27019624 PMCID: PMC4807159 DOI: 10.7150/ijbs.13688] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Accepted: 12/22/2015] [Indexed: 02/03/2023] Open
Abstract
The pHs of extracellular fluids (ECFs) in normal tissues are commonly maintained at 7.35 to 7.45. The acidification of the ECF is one of the major characteristics of tumour microenvironment. In this study, we report that decreased extracellular pH promotes the transformation of mesenchymal stem cells (MSCs) into cancer-associated fibroblasts (CAFs), termed CAF activation. Furthermore, we demonstrate that GPR68, a proton-sensing G-protein-coupled receptor (GPCR), is required for the pH-dependent regulation of the differentiation of MSCs into CAFs. We then identify Yes-associated protein 1 (YAP) as a downstream effector of GPR68 for CAF activation. Finally, we show that knockdown of GPR68 in MSCs can prevent the CAF activation under cancer microenvironment. Systemic transplantation of GPR68-silenced MSCs suppresses in-situ tumour growth and prolong life span after cancer graft.
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Affiliation(s)
- Hongyi Zhu
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Shangchun Guo
- 2. Institute of Microsurgery on Extremities, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Yuelei Zhang
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Junhui Yin
- 2. Institute of Microsurgery on Extremities, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Wenjing Yin
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Shicong Tao
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Yang Wang
- 2. Institute of Microsurgery on Extremities, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Changqing Zhang
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China;; 2. Institute of Microsurgery on Extremities, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
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15
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Huang XP, Karpiak J, Kroeze WK, Zhu H, Chen X, Moy SS, Saddoris KA, Nikolova VD, Farrell MS, Wang S, Mangano TJ, Deshpande DA, Jiang A, Penn RB, Jin J, Koller BH, Kenakin T, Shoichet BK, Roth BL. Allosteric ligands for the pharmacologically dark receptors GPR68 and GPR65. Nature 2015; 527:477-83. [PMID: 26550826 DOI: 10.1038/nature15699] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 09/04/2015] [Indexed: 01/15/2023]
Abstract
At least 120 non-olfactory G-protein-coupled receptors in the human genome are 'orphans' for which endogenous ligands are unknown, and many have no selective ligands, hindering the determination of their biological functions and clinical relevance. Among these is GPR68, a proton receptor that lacks small molecule modulators for probing its biology. Using yeast-based screens against GPR68, here we identify the benzodiazepine drug lorazepam as a non-selective GPR68 positive allosteric modulator. More than 3,000 GPR68 homology models were refined to recognize lorazepam in a putative allosteric site. Docking 3.1 million molecules predicted new GPR68 modulators, many of which were confirmed in functional assays. One potent GPR68 modulator, ogerin, suppressed recall in fear conditioning in wild-type but not in GPR68-knockout mice. The same approach led to the discovery of allosteric agonists and negative allosteric modulators for GPR65. Combining physical and structure-based screening may be broadly useful for ligand discovery for understudied and orphan GPCRs.
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Affiliation(s)
- Xi-Ping Huang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA.,National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA
| | - Joel Karpiak
- Department of Pharmaceutical Chemistry, University of California at San Francisco, Byers Hall, 1700 4th Street, San Francisco, California 94158-2550, USA
| | - Wesley K Kroeze
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Hu Zhu
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Xin Chen
- Center for Integrative Chemical Biology and Drug Discovery (CICBDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7363, USA.,Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, USA
| | - Sheryl S Moy
- Department of Psychiatry and Carolina Institute for Developmental Disabilities (CIDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7146, USA
| | - Kara A Saddoris
- Department of Psychiatry and Carolina Institute for Developmental Disabilities (CIDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7146, USA
| | - Viktoriya D Nikolova
- Department of Psychiatry and Carolina Institute for Developmental Disabilities (CIDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7146, USA
| | - Martilias S Farrell
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Sheng Wang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Thomas J Mangano
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA.,National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA
| | - Deepak A Deshpande
- Center for Translational Medicine and Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Alice Jiang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA.,National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA
| | - Raymond B Penn
- Center for Translational Medicine and Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Jian Jin
- Center for Integrative Chemical Biology and Drug Discovery (CICBDD), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7363, USA.,Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, USA
| | - Beverly H Koller
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7264, USA
| | - Terry Kenakin
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA
| | - Brian K Shoichet
- Department of Pharmaceutical Chemistry, University of California at San Francisco, Byers Hall, 1700 4th Street, San Francisco, California 94158-2550, USA
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7365, USA.,National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7365, USA.,Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, USA
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16
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Zhu H, Cheng X, Niu X, Zhang Y, Guan J, Liu X, Tao S, Wang Y, Zhang C. Proton-sensing GPCR-YAP Signalling Promotes Cell Proliferation and Survival. Int J Biol Sci 2015; 11:1181-9. [PMID: 26327812 PMCID: PMC4551754 DOI: 10.7150/ijbs.12500] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 07/01/2015] [Indexed: 12/14/2022] Open
Abstract
The pHs of extracellular fluids (ECFs) in humans are consistently maintained at 7.35 to 7.45 in physiological conditions. Pathological changes, including infarction, tumourigenesis and inflammation, commonly result in decreases in the ECF pH in the affected tissues. In this study, we report that proliferation is promoted and apoptosis is inhibited by decreases in extracellular pH. Furthermore, we demonstrated that proton-sensing G-protein-coupled receptors (GPCRs) are required for the pH-dependent regulation of proliferation and apoptosis through the G protein α subunit 12/13 (G12/13) and Rho GTPases. Next, we identified Yes-associated protein 1 (YAP) as a downstream effector of Rho signalling. Together, the results from our study demonstrate that extracellular pH can modulate cell proliferation and apoptosis by regulating the proton-sensing GPCR-YAP pathway.
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Affiliation(s)
- Hongyi Zhu
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Xiangguo Cheng
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China. ; 2. Institute of Microsurgery on Extremities, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Xin Niu
- 2. Institute of Microsurgery on Extremities, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Yuelei Zhang
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Junjie Guan
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Xiaolin Liu
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Shicong Tao
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Yang Wang
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China. ; 2. Institute of Microsurgery on Extremities, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
| | - Changqing Zhang
- 1. Department of Orthopaedic Surgery, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China. ; 2. Institute of Microsurgery on Extremities, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai 200233, China
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17
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Horiguchi K, Higuchi M, Yoshida S, Nakakura T, Tateno K, Hasegawa R, Takigami S, Ohsako S, Kato T, Kato Y. Proton receptor GPR68 expression in dendritic-cell-like S100β-positive cells of rat anterior pituitary gland: GPR68 induces interleukin-6 gene expression in extracellular acidification. Cell Tissue Res 2014; 358:515-25. [PMID: 25129106 DOI: 10.1007/s00441-014-1958-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/24/2014] [Indexed: 01/04/2023]
Abstract
S100β-positive cells, which do not express the classical pituitary hormones, appear to possess multifunctional properties and are assumed to be heterogeneous in the anterior pituitary gland. The presence of several protein markers has shown that S100β-positive cells are composed of populations such as stem/progenitor cells, epithelial cells, astrocytes and dendritic cells. Recently, we succeeded in separating S100β-positive cells into round-cell (dendritic-cell-like) and process-cell types. We also found the characteristic expression of anti-inflammatory factors (interleukin-6, Il-6) and membrane receptors (integrin β-6) in the round type. Here, we further investigate the function of the subpopulation of S100β-positive cells. Since IL-6 is also a paracrine factor that regulates hormone producing-cells, we examine whether a correlation exists among extracellular acid stress, IL-6 and hormone production by using primary cultures of anterior pituitary cells. Dendritic-cell-like S100β-positive cells notably expressed Gpr68 (proton receptor) and Il-6. Furthermore, the expression of Il-6 and proopiomelanocortin (Pomc) was up-regulated by extracellular acidification. The functional role of IL-6 and GPR68 in the gene expression of Pomc during extracellular acidification was also examined. Small interfering RNA for Il-6 up-regulated Pomc expression and that for Gpr68 reversed the down-regulation of Il-6 and up-regulated Pomc expression by extracellular acidification. Thus, S100β-positive dendritic-like cells can sense an increase in extracellular protons via GPR68 and respond by the production of IL-6 in order to suppress the up-regulation of Pomc expression.
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Affiliation(s)
- Kotaro Horiguchi
- Laboratory of Anatomy and Cell Biology, Department of Health Sciences, Kyorin University, 476 Miyashita-cho, Hachioji, Tokyo, 192-8508, Japan,
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18
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Role for the TRPV1 channel in insulin secretion from pancreatic beta cells. J Membr Biol 2014; 247:479-91. [PMID: 24676478 DOI: 10.1007/s00232-014-9658-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 03/10/2014] [Indexed: 02/04/2023]
Abstract
Transient receptor potential channels have been put forward as regulators of insulin secretion. A role for the TRPV1 ion channel in insulin secretion has been suggested in pancreatic beta cell lines. We explored whether TRPV1 is functionally expressed in RINm5F and primary beta cells from neonate and adult rats. We examined if capsaicin could activate cationic non-selective currents. Our results show that TRPV1 channels are not functional in insulin-secreting cells, since capsaicin did not produce current activation, not even under culture conditions known to induce the expression of other ion channels in these cells. Although TRPV1 channels seem to be irrelevant for the physiology of isolated beta cells, they may play a role in glucose homeostasis acting through the nerve fibers that regulate islet function. At the physiological level, we observed that Trpv1 (-/-) mice presented lower fasting insulin levels than their wild-type littermates, however, we did not find differences between these experimental groups nor in the glucose tolerance test or in the insulin secretion. However, we did find that the Trpv1 (-/-) mice exhibited a higher insulin sensitivity compared to their wild-type counterparts. Our results demonstrate that TRPV1 does not contribute to glucose-induced insulin secretion in beta cells as was previously thought, but it is possible that it may control insulin sensitivity.
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19
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Jin Y, Sato K, Tobo A, Mogi C, Tobo M, Murata N, Ishii S, Im DS, Okajima F. Inhibition of interleukin-1β production by extracellular acidification through the TDAG8/cAMP pathway in mouse microglia. J Neurochem 2014; 129:683-95. [PMID: 24447140 DOI: 10.1111/jnc.12661] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 01/16/2014] [Indexed: 12/23/2022]
Abstract
Interleukin-1β (IL-1β) is released from activated microglia and involved in the neurodegeneration of acute and chronic brain disorders, such as stroke and Alzheimer's disease, in which extracellular acidification has been shown to occur. Here, we examined the extracellular acidic pH regulation of IL-1β production, especially focusing on TDAG8, a major proton-sensing G-protein-coupled receptor, in mouse microglia. Extracellular acidification inhibited lipopolysaccharide -induced IL-1β production, which was associated with the inhibition of IL-1β cytoplasmic precursor and mRNA expression. The IL-1β mRNA and protein responses were significantly, though not completely, attenuated in microglia derived from TDAG8-deficient mice compared with those from wild-type mice. The acidic pH also stimulated cellular cAMP accumulation, which was completely inhibited by TDAG8 deficiency. Forskolin and a cAMP derivative, which specifically stimulates protein kinase A (PKA), mimicked the proton actions, and PKA inhibitors reversed the acidic pH-induced IL-1β mRNA expression. The acidic pH-induced inhibitory IL-1β responses were accompanied by the inhibition of extracellular signal-related kinase and c-Jun N-terminal kinase activities. The inhibitory enzyme activities in response to acidic pH were reversed by the PKA inhibitor and TDAG8 deficiency. We conclude that extracellular acidic pH inhibits lipopolysaccharide-induced IL-1β production, at least partly, through the TDAG8/cAMP/PKA pathway, by inhibiting extracellular signal-related kinase and c-Jun N-terminal kinase activities, in mouse microglia.
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Affiliation(s)
- Ye Jin
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
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