1
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Imenez Silva PH, Câmara NO, Wagner CA. Role of proton-activated G protein-coupled receptors in pathophysiology. Am J Physiol Cell Physiol 2022; 323:C400-C414. [PMID: 35759438 DOI: 10.1152/ajpcell.00114.2022] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Local acidification is a common feature of many disease processes such as inflammation, infarction, or solid tumor growth. Acidic pH is not merely a sequelae of disease but contributes to recruitment and regulation of immune cells, modifies metabolism of parenchymal, immune and tumor cells, modulates fibrosis, vascular permeability, oxygen availability and consumption, invasiveness of tumor cells, and impacts on cell survival. Thus, multiple pH-sensing mechanisms must exist in cells involved in these processes. These pH-sensors play important roles in normal physiology and pathophysiology, and hence might be attractive targets for pharmacological interventions. Among the pH-sensing mechanisms, OGR1 (GPR68), GPR4 (GPR4), and TDAG8 (GPR65) have emerged as important molecules. These G protein-coupled receptors are widely expressed, are upregulated in inflammation and tumors, sense changes in extracellular pH in the range between pH 8 and 6, and are involved in modulating key processes in inflammation, tumor biology, and fibrosis. This review discusses key features of these receptors and highlights important disease states and pathways affected by their activity.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Niels Olsen Câmara
- Department of Immunology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
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2
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Imenez Silva PH, Wagner CA. Physiological relevance of proton-activated GPCRs. Pflugers Arch 2022; 474:487-504. [PMID: 35247105 PMCID: PMC8993716 DOI: 10.1007/s00424-022-02671-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022]
Abstract
The detection of H+ concentration variations in the extracellular milieu is accomplished by a series of specialized and non-specialized pH-sensing mechanisms. The proton-activated G protein–coupled receptors (GPCRs) GPR4 (Gpr4), TDAG8 (Gpr65), and OGR1 (Gpr68) form a subfamily of proteins capable of triggering intracellular signaling in response to alterations in extracellular pH around physiological values, i.e., in the range between pH 7.5 and 6.5. Expression of these receptors is widespread for GPR4 and OGR1 with particularly high levels in endothelial cells and vascular smooth muscle cells, respectively, while expression of TDAG8 appears to be more restricted to the immune compartment. These receptors have been linked to several well-studied pH-dependent physiological activities including central control of respiration, renal adaption to changes in acid–base status, secretion of insulin and peripheral responsiveness to insulin, mechanosensation, and cellular chemotaxis. Their role in pathological processes such as the genesis and progression of several inflammatory diseases (asthma, inflammatory bowel disease), and tumor cell metabolism and invasiveness, is increasingly receiving more attention and makes these receptors novel and interesting targets for therapy. In this review, we cover the role of these receptors in physiological processes and will briefly discuss some implications for disease processes.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland. .,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland. .,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
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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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Sisignano M, Fischer MJM, Geisslinger G. Proton-Sensing GPCRs in Health and Disease. Cells 2021; 10:cells10082050. [PMID: 34440817 PMCID: PMC8392051 DOI: 10.3390/cells10082050] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/05/2021] [Accepted: 08/06/2021] [Indexed: 12/17/2022] Open
Abstract
The group of proton-sensing G-protein coupled receptors (GPCRs) consists of the four receptors GPR4, TDAG8 (GPR65), OGR1 (GPR68), and G2A (GPR132). These receptors are cellular sensors of acidification, a property that has been attributed to the presence of crucial histidine residues. However, the pH detection varies considerably among the group of proton-sensing GPCRs and ranges from pH of 5.5 to 7.8. While the proton-sensing GPCRs were initially considered to detect acidic cellular environments in the context of inflammation, recent observations have expanded our knowledge about their physiological and pathophysiological functions and many additional individual and unique features have been discovered that suggest a more differentiated role of these receptors in health and disease. It is known that all four receptors contribute to different aspects of tumor biology, cardiovascular physiology, and asthma. However, apart from their overlapping functions, they seem to have individual properties, and recent publications identify potential roles of individual GPCRs in mechanosensation, intestinal inflammation, oncoimmunological interactions, hematopoiesis, as well as inflammatory and neuropathic pain. Here, we put together the knowledge about the biological functions and structural features of the four proton-sensing GPCRs and discuss the biological role of each of the four receptors individually. We explore all currently known pharmacological modulators of the four receptors and highlight potential use. Finally, we point out knowledge gaps in the biological and pharmacological context of proton-sensing GPCRs that should be addressed by future studies.
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Affiliation(s)
- Marco Sisignano
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, University Hospital of Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany;
- Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany
- Correspondence:
| | - Michael J. M. Fischer
- Center for Physiology and Pharmacology, Institute of Physiology, Medical University of Vienna, Schwarzspanierstrasse 17, 1090 Vienna, Austria;
| | - Gerd Geisslinger
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, University Hospital of Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany;
- Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany
- Fraunhofer Cluster of Excellence for Immune-Mediated Diseases (CIMD), Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany
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5
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Sato K, Tobo A, Mogi C, Tobo M, Yamane N, Tosaka M, Tomura H, Im DS, Okajima F. The protective role of proton-sensing TDAG8 in the brain injury in a mouse ischemia reperfusion model. Sci Rep 2020; 10:17193. [PMID: 33057165 PMCID: PMC7566628 DOI: 10.1038/s41598-020-74372-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 09/30/2020] [Indexed: 01/09/2023] Open
Abstract
Extracellular acidification in the brain has been observed in ischemia; however, the physiological and pathophysiological implications of the pH reduction remain largely unknown. Here, we analyzed the roles of proton-sensing G protein-coupled receptors, including T-cell death-associated gene 8 (TDAG8), ovarian cancer G protein-coupled receptor 1 (OGR1), and G protein-coupled receptor 4 (GPR4) in a mouse ischemia reperfusion model. Cerebral infarction and dysfunctional behavior with transient middle cerebral artery occlusion (tMCAO) and subsequent reperfusion were exacerbated by the deficiency of TDAG8, whereas no significant effect was observed with the deficiency of OGR1 or GPR4. We confirmed that the pH of the predicted infarction region was 6.5. TDAG8 mRNA was observed in Iba1-positive microglia in the mouse brain. The tMCAO increased the mRNA expression of tumor necrosis factor-α in the ipsilateral cerebral hemisphere and evoked morphological changes in microglia in an evolving cerebral injury. These tMCAO-induced actions were significantly enhanced by the TDAG8 deficiency. Administration of minocycline, which is known to inhibit microglial activation, improved the cerebral infarction and dysfunctional behavior induced by tMCAO in the TDAG8-deficient mouse. Thus, acidic pH/TDAG8 protects against cerebral infarction caused by tMCAO, at least due to the mechanism involving the inhibition of microglial functions.
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Affiliation(s)
- Koichi Sato
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, 371-8512, Japan.
| | - Ayaka Tobo
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, 371-8512, Japan
| | - Chihiro Mogi
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, 371-8512, Japan
| | - Masayuki Tobo
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, 371-8512, Japan
| | - Nobuhiro Yamane
- Department of Neurosurgery, Gunma University Graduate School of Medicine, Maebashi, 371-8511, Japan
| | - Masahiko Tosaka
- Department of Neurosurgery, Gunma University Graduate School of Medicine, Maebashi, 371-8511, Japan
| | - Hideaki Tomura
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, 214-8571, Japan
| | - Dong-Soon Im
- College of Pharmacy, Kyung Hee University, Seoul, 02447, Republic of Korea
| | - Fumikazu Okajima
- Laboratory of Signal Transduction, Faculty of Pharmaceutical Sciences, Aomori University, Aomori, 030-0943, Japan
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6
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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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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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Comprehensive Assessment of GPR68 Expression in Normal and Neoplastic Human Tissues Using a Novel Rabbit Monoclonal Antibody. Int J Mol Sci 2019; 20:ijms20215261. [PMID: 31652823 PMCID: PMC6862545 DOI: 10.3390/ijms20215261] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 10/17/2019] [Accepted: 10/22/2019] [Indexed: 02/07/2023] Open
Abstract
GPR68 (OGR1) belongs to the proton-sensing G protein-coupled receptors that are involved in cellular adaptations to pH changes during tumour development. Although expression of GPR68 has been described in many tumour cell lines, little is known about its presence in human tumour entities. We characterised the novel rabbit monoclonal anti-human GPR68 antibody 16H23L16 using various cell lines and tissue specimens. The antibody was then applied to a large series of formalin-fixed, paraffin-embedded normal and neoplastic human tissue samples. Antibody specificity was demonstrated in a Western blot analysis of GPR68-expressing cells using specific siRNAs. Immunocytochemical experiments revealed pH-dependent changes in subcellular localisation of the receptor and internalisation after stimulation with lorazepam. In normal tissue, GPR68 was present in glucagon-producing islet cells, neuroendocrine cells of the intestinal tract, gastric glands, granulocytes, macrophages, muscle layers of arteries and arterioles, and capillaries. GPR68 was also expressed in neuroendocrine tumours, where it may be a positive prognostic factor, in pheochromocytomas, cervical adenocarcinomas, and endometrial cancer, as well as in paragangliomas, medullary thyroid carcinomas, gastrointestinal stromal tumours, and pancreatic adenocarcinomas. Often, tumour capillaries were also strongly GPR68-positive. The novel antibody 16H23L16 will be a valuable tool for basic research and for identifying GPR68-expressing tumours during histopathological examinations.
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9
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Kojima R, Horiguchi K, Mochimaru Y, Musha S, Murakami S, Deai M, Mogi C, Sato K, Okajima F, Tomura H. Characterization of molecular mechanisms of extracellular acidification-induced intracellular Ca 2+ increase in LβT2 cells. Biochem Biophys Res Commun 2019; 517:636-641. [PMID: 31400852 DOI: 10.1016/j.bbrc.2019.07.083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 07/22/2019] [Indexed: 12/30/2022]
Abstract
Extracellular acidification regulates endocrine cell functions. Ovarian cancer G protein-coupled receptor 1 (OGR1), also known as GPR68, is a proton-sensing G protein-coupled receptor and is activated by extracellular acidification, resulting in the activation of multiple intracellular signaling pathways. In the present study, we found that OGR1 was expressed in some gonadotropic cells in rat anterior pituitary and in LβΤ2 cells, which are used as a model of gonadotropic cells. When we reduced extracellular pH, a transient intracellular Ca2+ increase was detected in LβT2 cells. The Ca2+ increase was inhibited by a Gq/11 inhibitor and Cu2+, which is known as an OGR1 antagonist. We also found that extracellular acidification enhanced GnRH-induced Gaussia luciferase secretion from LβT2 cells. These results suggest that OGR1 may play a role in the regulation of gonadotropic cell function such as its hormone secretion.
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Affiliation(s)
- Ryotaro Kojima
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, 214-8571, Japan
| | - Kotaro Horiguchi
- Laboratory of Anatomy and Cell Biology, Department of Health Sciences, Kyorin University, Tokyo, 192-8503, Japan
| | - Yuta Mochimaru
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, 214-8571, Japan
| | - Shiori Musha
- Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, 214-8571, Japan
| | - Syo Murakami
- 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
| | - 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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10
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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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11
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Mochimaru Y, Negishi J, Murakami S, Musha S, Sato K, Okajima F, Tomura H. Metals Differentially Activate Ovarian Cancer G Protein-Coupled Receptor 1 in Various Species. Zoolog Sci 2019; 35:109-114. [PMID: 29623784 DOI: 10.2108/zs170145] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Human, mouse, and zebrafish ovarian cancer G protein-coupled receptors (OGR1s) are activated by both metals and extracellular protons. In the present study, we examined whether pig, rat, chicken, and Xenopus OGR1 homologs could sense and be activated by protons and metals. We found that all homologs stimulated serum response element (SRE)-driven promoter activities when they are stimulated by protons. On the other hand, metals differentially activated the homologs. The results using chimeric receptors of human and zebrafish OGR1s indicate that the specificity of the metal-induced activation lies in the extracellular region. These results suggest that protons are an evolutionally conserved agonist of OGR1. However, the types of metals that activated the receptor differed among the homologs.
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Affiliation(s)
- Yuta Mochimaru
- 1 Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Jun Negishi
- 1 Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Syo Murakami
- 1 Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Shiori Musha
- 1 Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan
| | - Koichi Sato
- 2 Laboratory of Medical Neuroscience, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Fumikazu Okajima
- 3 Laboratory of Pathophysiology, Faculty of Pharmacy, Aomori University, Aomori 030-0943, Japan
| | - Hideaki Tomura
- 1 Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan.,4 Institute of Endocrinology, Meiji University, Kawasaki 214-8571, Japan
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12
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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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ATAT1 is essential for regulation of homeostasis-retaining cellular responses in corticotrophs along hypothalamic-pituitary-adrenal axis. Cell Tissue Res 2017; 370:169-178. [PMID: 28687926 DOI: 10.1007/s00441-017-2654-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 05/30/2017] [Indexed: 12/22/2022]
Abstract
The production and secretion of adrenocorticotropin, a proopiomelanocortin (POMC)-derived hormone, by corticotrophs in the anterior pituitary, is regulated by corticotrophin-releasing hormone (CRH) and glucocorticoids. We have previously demonstrated that adrenalectomy induces α-tubulin N-acetyltransferase 1 (ATAT1) expression and α-tubulin acetylation in corticotrophs. However, the regulatory mechanism of ATAT1 expression and the function of acetylated microtubules in corticotrophs are unclear. Here, we analyze the effect of CRH or dexamethasone on Atat1 expression in the mouse corticotroph AtT20 cell line. The expression of Atat1 was increased by CRH and decreased by dexamethasone in AtT20 cells. We examined the effect of Atat1 knockdown on the expression of POMC-associated genes and the dexamethasone-induced nuclear translocation of glucocorticoid receptor (GR) by real-time polymerase chain reaction and Western blot analysis, respectively. Atat1 knockdown resulted in a significant increase in the expression of ACTH-producing genes and decreased the dexamethasone-induced nuclear translocation of GR accompanied with a reduction in α-tubulin acetylation. Atat1 overexpression resulted in a significant increase in α-tubulin acetylation and the dexamethasone-induced nuclear translocation of GR. These results suggest that the acetylated microtubules function as the rail-line for the transportation of GR into the nucleus. We conclude that ATAT1 finely tunes the cellular responses of corticotrophs to hormonal stimulation through an intracellular feedback circuit.
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14
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Negishi J, Omori Y, Shindo M, Takanashi H, Musha S, Nagayama S, Hirayama J, Nishina H, Nakakura T, Mogi C, Sato K, Okajima F, Mochimaru Y, Tomura H. Manganese and cobalt activate zebrafish ovarian cancer G-protein-coupled receptor 1 but not GPR4. J Recept Signal Transduct Res 2017; 37:401-408. [PMID: 28270026 DOI: 10.1080/10799893.2017.1298130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mammalian ovarian G-protein-coupled receptor 1 (OGR1) is activated by some metals in addition to extracellular protons and coupling to multiple intracellular signaling pathways. In the present study, we examined whether zebrafish OGR1, zebrafish GPR4, and human GPR4 (zOGR1, zGPR4, and hGPR4, respectively) could sense the metals and activate the intracellular signaling pathways. On one hand, we found that only manganese and cobalt of the tested metals stimulated SRE-promoter activities in zOGR1-overexpressed HEK293T cells. On the other hand, none of the metals tested stimulated the promoter activities in zGPR4- and hGPR4-overexpressed cells. The OGR1 mutant (H4F), which is lost to activation by extracellular protons, did not stimulate metal-induced SRE-promoter activities. These results suggest that zOGR1, but not GPR4, is also a metal-sensing G-protein-coupled receptor in addition to a proton-sensing G-protein-coupled receptor, although not all metals that activate hOGR1 activated zOGR1.
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Affiliation(s)
- Jun Negishi
- a Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture , Meiji University , Kawasaki , Japan
| | - Yuka Omori
- a Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture , Meiji University , Kawasaki , Japan
| | - Mami Shindo
- a Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture , Meiji University , Kawasaki , Japan
| | - Hayate Takanashi
- a Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture , Meiji University , Kawasaki , Japan
| | - Shiori Musha
- a Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture , Meiji University , Kawasaki , Japan
| | - Suminori Nagayama
- a Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture , Meiji University , Kawasaki , Japan
| | - Jun Hirayama
- b Department of Developmental and Regenerative Biology , Medical Research Institute, Tokyo Medical and Dental University , Tokyo , Japan
| | - Hiroshi Nishina
- b Department of Developmental and Regenerative Biology , Medical Research Institute, Tokyo Medical and Dental University , Tokyo , Japan
| | - Takashi Nakakura
- c Department of Anatomy, Graduate School of Medicine , Teikyo University , Tokyo , Japan
| | - Chihiro Mogi
- d Laboratory of Signal Transduction, Department of Molecular Medicine , Institute for Molecular and Cellular Regulation, Gunma University , Maebashi , Japan
| | - Koichi Sato
- d Laboratory of Signal Transduction, Department of Molecular Medicine , Institute for Molecular and Cellular Regulation, Gunma University , Maebashi , Japan
| | - Fumikazu Okajima
- e Laboratory of Pathophysiology, Department of Pharmacy, Faculty of Pharmaceutical Sciences , Aomori University , Aomori , Japan
| | - Yuta Mochimaru
- a Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture , Meiji University , Kawasaki , Japan
| | - Hideaki Tomura
- a Laboratory of Cell Signaling Regulation, Department of Life Sciences, School of Agriculture , Meiji University , Kawasaki , Japan.,f Institute of Endocrinology, Meiji University , Kawasaki , Japan
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15
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Parry DA, Smith CE, El-Sayed W, Poulter JA, Shore RC, Logan CV, Mogi C, Sato K, Okajima F, Harada A, Zhang H, Koruyucu M, Seymen F, Hu JCC, Simmer JP, Ahmed M, Jafri H, Johnson CA, Inglehearn CF, Mighell AJ. Mutations in the pH-Sensing G-protein-Coupled Receptor GPR68 Cause Amelogenesis Imperfecta. Am J Hum Genet 2016; 99:984-990. [PMID: 27693231 PMCID: PMC5065684 DOI: 10.1016/j.ajhg.2016.08.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/17/2016] [Indexed: 01/11/2023] Open
Abstract
Amelogenesis is the process of dental enamel formation, leading to the deposition of the hardest tissue in the human body. This process requires the intricate regulation of ion transport and controlled changes to the pH of the developing enamel matrix. The means by which the enamel organ regulates pH during amelogenesis is largely unknown. We identified rare homozygous variants in GPR68 in three families with amelogenesis imperfecta, a genetically and phenotypically heterogeneous group of inherited conditions associated with abnormal enamel formation. Each of these homozygous variants (a large in-frame deletion, a frameshift deletion, and a missense variant) were predicted to result in loss of function. GPR68 encodes a proton-sensing G-protein-coupled receptor with sensitivity in the pH range that occurs in the developing enamel matrix during amelogenesis. Immunohistochemistry of rat mandibles confirmed localization of GPR68 in the enamel organ at all stages of amelogenesis. Our data identify a role for GPR68 as a proton sensor that is required for proper enamel formation.
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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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17
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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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18
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Kamide Y, Ishizuka T, Tobo M, Tsurumaki H, Aoki H, Mogi C, Nakakura T, Yatomi M, Ono A, Koga Y, Sato K, Hisada T, Dobashi K, Yamada M, Okajima F. Acidic environment augments FcεRI-mediated production of IL-6 and IL-13 in mast cells. Biochem Biophys Res Commun 2015. [PMID: 26196745 DOI: 10.1016/j.bbrc.2015.07.077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Although blood pH is maintained in a narrow range of around pH 7.4 in living organisms, inflammatory loci are characterized by acidic conditions. Mast cells tend to reside close to the surface of the body in areas such as the mucosa and skin where they may be exposed to exogenous acids, and they play an important role in immune responses. However, little is known about the effects of extracellular acidification on the functions of mast cell. Here, we found that extracellular acidification increased the dinitrophenyl-conjugated human serum albumin (DNP-HSA)-induced production of interleukin (IL)-6 and IL-13 in MC/9 cells or bone marrow-derived mouse mast cells sensitized with anti-DNP IgE. Extracellular acidification also inhibited migration of MC/9 cells toward DNP-HSA. In addition, acidic pH stimulated antigen-induced activation of p38 mitogen-activated protein kinase (MAPK) and protein kinase B (Akt). These findings suggest that extracellular acidification augmented antigen/IgE-induced and FcεRI-mediated production of IL-6 and IL-13 in mast cells, and that this was associated with the enhancement of p38 MAPK and Akt activation.
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Affiliation(s)
- Yosuke Kamide
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan; Clinical Research Center for Allergy and Rheumatology, Sagamihara National Hospital, Sagamihara, Japan.
| | - Tamotsu Ishizuka
- Third Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Masayuki Tobo
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Hiroaki Tsurumaki
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan; Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Haruka Aoki
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Chihiro Mogi
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Takashi Nakakura
- Department of Anatomy, Graduate School of Medicine, Teikyo University, Tokyo, Japan
| | - Masakiyo Yatomi
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Akihiro Ono
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Yasuhiko Koga
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Koichi Sato
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Takeshi Hisada
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Kunio Dobashi
- Gunma University Graduate School of Health Sciences, Maebashi, Japan
| | - Masanobu Yamada
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Fumikazu Okajima
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
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Hamano K, Nakagawa Y, Ohtsu Y, Li L, Medina J, Tanaka Y, Masuda K, Komatsu M, Kojima I. Lactisole inhibits the glucose-sensing receptor T1R3 expressed in mouse pancreatic β-cells. J Endocrinol 2015; 226:57-66. [PMID: 25994004 DOI: 10.1530/joe-15-0102] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/20/2015] [Indexed: 11/08/2022]
Abstract
Glucose activates the glucose-sensing receptor T1R3 and facilitates its own metabolism in pancreatic β-cells. An inhibitor of this receptor would be helpful in elucidating the physiological function of the glucose-sensing receptor. The present study was conducted to examine whether or not lactisole can be used as an inhibitor of the glucose-sensing receptor. In MIN6 cells, in a dose-dependent manner, lactisole inhibited insulin secretion induced by sweeteners, acesulfame-K, sucralose and glycyrrhizin. The IC50 was ∼4 mmol/l. Lactisole attenuated the elevation of cytoplasmic Ca2+ concentration ([Ca2+]c) evoked by sucralose and acesulfame-K but did not affect the elevation of intracellular cAMP concentration ([cAMP]c) induced by these sweeteners. Lactisole also inhibited the action of glucose in MIN6 cells. Thus, lactisole significantly reduced elevations of intracellular [NADH] and intracellular [ATP] induced by glucose, and also inhibited glucose-induced insulin secretion. To further examine the effect of lactisole on T1R3, we prepared HEK293 cells stably expressing mouse T1R3. In these cells, sucralose elevated both [Ca2+]c and [cAMP]c. Lactisole attenuated the sucralose-induced increase in [Ca2+]c but did not affect the elevation of [cAMP]c. Finally, lactisole inhibited insulin secretion induced by a high concentration of glucose in mouse islets. These results indicate that the mouse glucose-sensing receptor was inhibited by lactisole. Lactisole may be useful in assessing the role of the glucose-sensing receptor in mouse pancreatic β-cells.
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Affiliation(s)
- Kunihisa Hamano
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
| | - Yuko Nakagawa
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
| | - Yoshiaki Ohtsu
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
| | - Longfei Li
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
| | - Johan Medina
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
| | - Yuji Tanaka
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
| | - Katsuyoshi Masuda
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
| | - Mitsuhisa Komatsu
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
| | - Itaru Kojima
- Institute for Molecular and Cellular RegulationGunma University, Maebashi 371-8512, JapanDepartment of General MedicineNational Defense Medical College, Tokorozawa, JapanSuntory Institute for Bioorganic ResearchOsaka, JapanDepartment of Internal MedicineShinshu University School of Medicine, Matsumoto, Japan
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20
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Abe-Ohya R, Ishikawa T, Shiozawa H, Suda K, Nara F. Identification of metals from osteoblastic ST-2 cell supernatants as novel OGR1 agonists. J Recept Signal Transduct Res 2015; 35:485-92. [DOI: 10.3109/10799893.2015.1015736] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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21
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Extracellular acidification synergizes with PDGF to stimulate migration of mouse embryo fibroblasts through activation of p38MAPK with a PTX-sensitive manner. Biochem Biophys Res Commun 2015; 460:191-7. [DOI: 10.1016/j.bbrc.2015.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 03/02/2015] [Indexed: 11/19/2022]
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22
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Justus CR, Yang LV. GPR4 decreases B16F10 melanoma cell spreading and regulates focal adhesion dynamics through the G13/Rho signaling pathway. Exp Cell Res 2015; 334:100-13. [PMID: 25845498 DOI: 10.1016/j.yexcr.2015.03.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 03/02/2015] [Accepted: 03/26/2015] [Indexed: 12/15/2022]
Abstract
The effect of acidosis, a biochemical hallmark of the tumor microenvironment, on cancer progression and metastasis is complex. Both pro- and anti-tumorigenic effects of acidosis have been reported and the acidic microenvironment has been exploited for specific delivery of drugs, imaging agents, and genetic constructs into tumors. In this study we investigate the spreading and focal adhesion of B16F10 melanoma cells that are genetically engineered to overexpress the pH-sensing G protein-coupled receptor GPR4. By using cell attachment assays we found that GPR4 overexpression delayed cell spreading and altered the spatial localization of dynamic focal adhesion complex, such as the localization of phosphorylated focal adhesion kinase (FAK) and paxillin, at acidic pH. The potential G-protein and downstream signaling pathways that are responsible for these effects were also investigated. By using the Rho inhibitor CT04 (C3 transferase), the Rho-associated kinase (ROCK) inhibitors Y27632 and thiazovivin, the myosin light chain kinase (MLCK) inhibitor staurosporine or a G12/13 inhibitory construct, cell spreading was restored whereas the inhibition and activation of the Gq and Gs pathways had little or no effect. Altogether our results indicate that through the G12/13/Rho signaling pathway GPR4 modulates focal adhesion dynamics and reduces cell spreading and membrane ruffling.
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Affiliation(s)
- Calvin R Justus
- Department of Internal Medicine, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Li V Yang
- Department of Internal Medicine, Brody School of Medicine, East Carolina University, Greenville, NC, USA; Department of Oncology, Brody School of Medicine, East Carolina University, Greenville, NC, USA; Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, NC, USA.
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23
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Mochimaru Y, Azuma M, Oshima N, Ichijo Y, Satou K, Matsuda K, Asaoka Y, Nishina H, Nakakura T, Mogi C, Sato K, Okajima F, Tomura H. Extracellular acidification activates ovarian cancer G-protein-coupled receptor 1 and GPR4 homologs of zebra fish. Biochem Biophys Res Commun 2015; 457:493-9. [DOI: 10.1016/j.bbrc.2014.12.105] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 12/24/2014] [Indexed: 02/02/2023]
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24
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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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25
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The elongation of primary cilia via the acetylation of α-tubulin by the treatment with lithium chloride in human fibroblast KD cells. Med Mol Morphol 2014; 48:44-53. [PMID: 24760594 DOI: 10.1007/s00795-014-0076-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 03/24/2014] [Indexed: 12/11/2022]
Abstract
Primary cilium, an organelle found on nearly every cell in the human body, typically serves as the mechanical sensor of the cell. Lithium ion is known to promote the elongation of primary cilia in a variety of cell types, but it is unknown whether lithium is involved in the acetylation of α-tubulin which is essential for the assembly of primary cilia. In order to reveal the relationship between the elongation of primary cilia with lithium and the acetylation of α-tubulin, we first observed the formation and structure of primary cilia in KD cells, a cell line deriving fibroblasts in human labium. Subsequently, by immunohistochemical and western blot analysis we elucidated that the length of primary cilia and acetylation of α-tubulin are regulated by lithium chloride (LiCl) in the medium in a time- and concentration-dependent manner. We next performed the RT-PCR, RNAi-based experiments and biochemical study using an inhibitor of glycogen synthase kinase-3βGSK-3β). We found that LiCl mobilizes the α-tubulin N-acetyltransferase 1 (αTAT1) in the signaling pathway mediating GSK-3β and adenylate cyclase III. In conclusion, our results suggested that LiCl treatments activate αTAT1 by the inhibition of GSK-3β and promote the α-tubulin acetylation, and then elongate the primary cilia.
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Mogi C, Nakakura T, Okajima F. Role of extracellular proton-sensing OGR1 in regulation of insulin secretion and pancreatic β-cell functions. Endocr J 2014; 61:101-10. [PMID: 24088601 DOI: 10.1507/endocrj.ej13-0380] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Insulin secretion with respect to pH environments has been investigated for a long time but its mechanism remains largely unknown. Extracellular pH is usually maintained at around 7.4 and, its change has been thought to occur in non-physiological situations. Acidification takes place under ischemic and inflammatory microenvironments, where stimulation of anaerobic glycolysis results in the production of lactic acid. In addition to ionotropic ion channels, such as transient receptor potential V1 (TRPV1) and acid-sensing ion channels (ASICs), metabotropic proton-sensing G protein-coupled receptors (GPCRs) have also been identified recently as proton-sensing machineries. While ionotropic ion channels usually sense strong acidic pH, proton-sensing GPCRs sense pH of 7.6 to 6.0 and have been shown to mediate a variety of biological actions in neutral and mildly acidic pH environments. Studies with receptor knockout mice have revealed that proton-sensing receptors, including ovarian cancer G protein-coupled receptor 1 (OGR1), a proton-sensing GPCRs, play a role in the regulation of insulin secretion and glucose metabolism under physiological conditions. Small molecule 3,5-disubstituted isoxazoles have recently been identified as OGR1 agonists working at neutral pH and have been shown to stimulate pancreatic β-cell differentiation and insulin synthesis. Thus, proton-sensing OGR1 may be an important player for insulin secretion and a potential target for improving β-cell function.
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Affiliation(s)
- Chihiro Mogi
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
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Yuan FL, Wang HR, Zhao MD, Yuan W, Cao L, Duan PG, Jiang YQ, Li XL, Dong J. Ovarian cancer G protein-coupled receptor 1 is involved in acid-induced apoptosis of endplate chondrocytes in intervertebral discs. J Bone Miner Res 2014; 29:67-77. [PMID: 23821474 DOI: 10.1002/jbmr.2030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/12/2013] [Accepted: 06/25/2013] [Indexed: 11/06/2022]
Abstract
Ovarian cancer G protein-coupled receptor 1 (OGR1) has been shown to be a receptor for protons. We investigated the role of proton-sensing G protein-coupled receptors in the apoptosis of endplate chondrocytes induced by extracellular acid. The expression of proton-sensing G protein-coupled receptors was examined in rat lumbar endplate chondrocytes. Knockdown of OGR1 was achieved by transfecting chondrocytes with specific short hairpin RNA (shRNA) for OGR1. Apoptotic changes were evaluated by DNA fragmentation ELISA, electron microscopy, and flow cytometry. Intracellular calcium ([Ca(2+) ]i) was analyzed with laser scanning confocal microscopy. The mechanism of OGR1 in acid-induced apoptosis of endplate chondrocytes was also investigated. We found that OGR1 was predominantly expressed in rat endplate chondrocytes, and its expression was highly upregulated in response to acidosis. Knocking down OGR1 with shRNAs effectively attenuated acid-induced apoptosis of endplate chondrocytes and increased [Ca(2+) ]i. Blocking OGR1-mediated [Ca(2+) ]i elevation inhibited acid-induced calcium-sensitive proteases such as calpain and calcineurin, and also inhibited the activation of Bid, Bad, and Caspase 3 and cleavage of poly (ADP-ribose) polymerase (PARP). OGR1-mediated [Ca(2+) ]i elevation has a crucial role in apoptosis of endplate chondrocytes by regulating activation of calcium-sensitive proteases and their downstream signaling.
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Affiliation(s)
- Feng-Lai Yuan
- Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
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28
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Aoki H, Mogi C, Hisada T, Nakakura T, Kamide Y, Ichimonji I, Tomura H, Tobo M, Sato K, Tsurumaki H, Dobashi K, Mori T, Harada A, Yamada M, Mori M, Ishizuka T, Okajima F. Proton-sensing ovarian cancer G protein-coupled receptor 1 on dendritic cells is required for airway responses in a murine asthma model. PLoS One 2013; 8:e79985. [PMID: 24244587 PMCID: PMC3823589 DOI: 10.1371/journal.pone.0079985] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 10/07/2013] [Indexed: 01/17/2023] Open
Abstract
Ovarian cancer G protein-coupled receptor 1 (OGR1) stimulation by extracellular protons causes the activation of G proteins and subsequent cellular functions. However, the physiological and pathophysiological roles of OGR1 in airway responses remain largely unknown. In the present study, we show that OGR1-deficient mice are resistant to the cardinal features of asthma, including airway eosinophilia, airway hyperresponsiveness (AHR), and goblet cell metaplasia, in association with a remarkable inhibition of Th2 cytokine and IgE production, in an ovalbumin (OVA)-induced asthma model. Intratracheal transfer to wild-type mice of OVA-primed bone marrow-derived dendritic cells (DCs) from OGR1-deficient mice developed lower AHR and eosinophilia after OVA inhalation compared with the transfer of those from wild-type mice. Migration of OVA-pulsed DCs to peribronchial lymph nodes was also inhibited by OGR1 deficiency in the adoption experiments. The presence of functional OGR1 in DCs was confirmed by the expression of OGR1 mRNA and the OGR1-sensitive Ca2+ response. OVA-induced expression of CCR7, a mature DC chemokine receptor, and migration response to CCR7 ligands in an in vitro Transwell assay were attenuated by OGR1 deficiency. We conclude that OGR1 on DCs is critical for migration to draining lymph nodes, which, in turn, stimulates Th2 phenotype change and subsequent induction of airway inflammation and AHR.
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Affiliation(s)
- Haruka Aoki
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Chihiro Mogi
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Takeshi Hisada
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Takashi Nakakura
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Yosuke Kamide
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Isao Ichimonji
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Hideaki Tomura
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Masayuki Tobo
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Koichi Sato
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Hiroaki Tsurumaki
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Kunio Dobashi
- Gunma University School of Health Sciences, Maebashi, Japan
| | - Tetsuya Mori
- Laboratory of Allergy and Immunology, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Akihiro Harada
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Masanobu Yamada
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Masatomo Mori
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Tamotsu Ishizuka
- Third Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
- * E-mail: (FO); (TI)
| | - Fumikazu Okajima
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- * E-mail: (FO); (TI)
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Amisten S, Salehi A, Rorsman P, Jones PM, Persaud SJ. An atlas and functional analysis of G-protein coupled receptors in human islets of Langerhans. Pharmacol Ther 2013; 139:359-91. [DOI: 10.1016/j.pharmthera.2013.05.004] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 05/03/2013] [Indexed: 12/17/2022]
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30
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Regulation of inflammation by extracellular acidification and proton-sensing GPCRs. Cell Signal 2013; 25:2263-71. [PMID: 23917207 DOI: 10.1016/j.cellsig.2013.07.022] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Accepted: 07/26/2013] [Indexed: 12/14/2022]
Abstract
Under ischemic and inflammatory circumstances, such as allergic airway asthma, rheumatoid arthritis, atherosclerosis, and tumors, extracellular acidification occurs due to the stimulation of anaerobic glycolysis. An acidic microenvironment has been shown to modulate pro-inflammatory or anti-inflammatory responses, including cyclooxygenase-2 (COX-2) expression, prostaglandin synthesis, and cytokine expression, in a variety of cell types, and thereby to exacerbate or ameliorate inflammation. However, molecular mechanisms underlying extracellular acidic pH-induced actions have not been fully understood. Recent studies have shown that ovarian cancer G protein-coupled receptor 1 (OGR1)-family G protein-coupled receptors (GPCRs) can sense extracellular pH or protons, which in turn stimulates intracellular signaling pathways and subsequent diverse cellular responses. In the present review, I discuss extracellular acidic pH-induced inflammatory responses and related responses in inflammatory cells, such as macrophages and neutrophils, and non-inflammatory cells, such as smooth muscle cells and endothelial cells, focusing especially on proton-sensing GPCRs.
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