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Sundström L, Greasley PJ, Engberg S, Wallander M, Ryberg E. Succinate receptor GPR91, a Gα(i) coupled receptor that increases intracellular calcium concentrations through PLCβ. FEBS Lett 2013; 587:2399-404. [PMID: 23770096 DOI: 10.1016/j.febslet.2013.05.067] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 05/30/2013] [Accepted: 05/30/2013] [Indexed: 11/15/2022]
Abstract
Succinate has been reported as the endogenous ligand for GPR91. In this study, succinate was confirmed to activate GPR91 resulting in both 3'-5'-cyclic adenosine monophosphate (cAMP) inhibition and inositol phosphate formation in a pertussis toxin (PTX)-sensitive manner. GPR91 agonist-mediated effects detected using dynamic mass redistribution (DMR) were inhibited with PTX, edelfosine and U73122 demonstrating the importance of not only the Gαi pathway but also PLCβ. These results show that GPR91 when expressed in HEK293s cells couples exclusively through the Gαi pathway and acts through Gαi not only to inhibit cAMP production but also to increase intracellular Ca(2+) in an inositol phosphate dependent mechanism via PLCβ activation.
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Wang H, Bai J, Chen G, Li W, Xiang R, Su G, Pei Y. A metabolic profiling analysis of the acute hepatotoxicity and nephrotoxicity of Zhusha Anshen Wan compared with cinnabar in rats using (1)H NMR spectroscopy. JOURNAL OF ETHNOPHARMACOLOGY 2013; 146:572-80. [PMID: 23376283 DOI: 10.1016/j.jep.2013.01.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 01/07/2013] [Accepted: 01/21/2013] [Indexed: 05/12/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Zhusha Anshen Wan (ZSASW), a traditional Chinese medicine (TCM) prescription, composed of cinnabar (cinnabaris), Coptidis Rhizoma (Coptis chinensis French.), Angelicae Sinensis Radix (Angelica sinensis (oliv.) Diels), uncooked Rehmanniae Radix (Rehmannia glutinosa Libosch.), honey fried Glycyrrhizae Radix Et Rhizoma (Glycyrrhiza uralensis Fisch.), has been widely used for sedative therapy. Cinnabar, the chief component of ZSASW, has been proved to possess the toxicities. AIM OF THE STUDY In this study, a metabonomics approach based on high-resolution (1)H nuclear magnetic resonance spectroscopy was applied to investigate the protective effects of ZSASW on the toxic effects induced by cinnabar alone. MATERIALS AND METHODS Male Wistar rats were divided into three groups: control group, ZSASW group and cinnabar group. Partial least squares-discriminant analysis (PLS-DA) was performed to identify different metabolic profiles of urine and serum from rats. Liver and kidney histopathology examinations and serum clinical chemistry analysis were also performed. RESULTS The significant difference in metabolic profiling of urine and serum of the rats was observed between cinnabar treated group, control group, and the changes of endogenous metabolites related to the toxicities were identified. The results were also certified by the liver and kidney histopathology examinations and biochemical analysis of blood. CONCLUSION Our results suggested that the four combined herbal medicines of ZSASW had the effects of protecting from the toxicity induced by cinnabar alone. This work showed that the NMR-based metabonomics approach might be a promising approach to study detoxification of Chinese medicines and reasonable combination of TCM prescriptions.
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Affiliation(s)
- Haifeng Wang
- Department of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, PR China
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103
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104
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Antihypoxic and antioxidant effects of exogenous succinic acid and aminothiol succinate-containing antihypoxants. Bull Exp Biol Med 2012; 153:336-9. [PMID: 22866305 DOI: 10.1007/s10517-012-1709-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Pronounced antihypoxic and antioxidant effects of preventive injection of succinic acid, aminothiol antihypoxants gutimine and amtizol, and succinate-containing aminothiol antihypoxants gutimine succinate and amtizol succinate to Wistar rats with acute hypoxic hypoxia have been demonstrated. Exogenous succinic acid was inferior to aminothiol compounds by antihypoxic effect, but superior to them by its effect on the level of LPO products. Succinate in the aminothiol molecule modulated the intensity of their antihypoxic and antioxidant effects. It did not modulate the antihypoxic activity of amtizol, but reduced the antihypoxic effect of gutimine, presumably because of the physicochemical characteristics of aminothiols. Comparison of the intensities of antihypoxic and antioxidant effects of the studied drugs showed no direct relationship between these effects.
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Montez P, Vázquez-Medina JP, Rodríguez R, Thorwald MA, Viscarra JA, Lam L, Peti-Peterdi J, Nakano D, Nishiyama A, Ortiz RM. Angiotensin receptor blockade recovers hepatic UCP2 expression and aconitase and SDH activities and ameliorates hepatic oxidative damage in insulin resistant rats. Endocrinology 2012; 153:5746-59. [PMID: 23087176 PMCID: PMC3512060 DOI: 10.1210/en.2012-1390] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Metabolic syndrome (MetS) is commonly associated with elevated renin-angiotensin system, oxidative stress, and steatohepatitis with down-regulation of uncoupling proteins (UCPs). However, the mechanisms linking renin-angiotensin system, steatosis, and UCP2 to hepatic oxidative damage during insulin resistance are not described. To test the hypothesis that angiotensin receptor activation contributes to decreased hepatic UCP2 expression and aconitase activity and to increased oxidative damage after increased glucose intake in a model of MetS, lean and obese Long Evans rats (n = 10/group) were randomly assigned to the following groups: 1) untreated Long Evans Tokushima Otsuka (lean, strain control), 2) untreated Otsuka Long Evans Tokushima Fatty (OLETF) (MetS model), 3) OLETF + angiotensin receptor blocker (ARB) (10 mg olmesartan/kg·d × 6 wk), 4) OLETF + high glucose (HG) (5% in drinking water × 6 wk), and 5) OLETF + ARB + HG (ARB/HG × 6 wk). HG increased body mass (37%), plasma triglycerides (TGs) (35%), plasma glycerol (87%), plasma free fatty acids (28%), and hepatic nitrotyrosine (74%). ARB treatment in HG decreased body mass (12%), plasma TG (15%), plasma glycerol (23%), plasma free fatty acids (14%), and hepatic TG content (42%), suggesting that angiotensin receptor type 1 (AT1) activation and increased adiposity contribute to the development of obesity-related dyslipidemia. ARB in HG also decreased hepatic nitrotyrosine and increased hepatic UCP2 expression (59%) and aconitase activity (40%), as well as antioxidant enzyme activities (50-120%), suggesting that AT1 activation also contributes to protein oxidation, impaired lipid metabolism, and antioxidant metabolism in the liver. Thus, in addition to promoting obesity-related hypertension, AT1 activation may also impair lipid metabolism and antioxidant capacity, resulting in steatosis via decreased UCP2 and tricarboxylic acid cycle activity.
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Affiliation(s)
- Priscilla Montez
- Department of Molecular and Cellular Biology, University of California, Merced, CA 95343, USA
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106
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Peti-Peterdi J, Gevorgyan H, Lam L, Riquier-Brison A. Metabolic control of renin secretion. Pflugers Arch 2012; 465:53-8. [PMID: 22729752 DOI: 10.1007/s00424-012-1130-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 06/09/2012] [Accepted: 06/11/2012] [Indexed: 01/04/2023]
Abstract
One emerging topic in renin-angiotensin system (RAS) research is the direct local control of renin synthesis and release by endogenous metabolic intermediates. During the past few years, our laboratory has characterized the localization and signaling of the novel metabolic receptor GPR91 in the normal and diabetic kidney and established GPR91 as a new, direct link between high glucose and RAS activation in diabetes. GPR91 (also called SUCNR1) binds tricarboxylic acid (TCA) cycle intermediate succinate which can rapidly accumulate in the local tissue environment when energy supply and demand are out of balance. In a variety of physiological and pathological conditions associated with metabolic stress, succinate signaling via GPR91 appears to be an important mediator or modulator of renin secretion. This review summarizes our current knowledge on the control of renin release by molecules of endogenous metabolic pathways with the main focus on succinate/GPR91.
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Affiliation(s)
- János Peti-Peterdi
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, University of Southern California, 1501 San Pablo Street, ZNI 335, Los Angeles, CA 90033, USA.
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107
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Ariza AC, Deen PMT, Robben JH. The succinate receptor as a novel therapeutic target for oxidative and metabolic stress-related conditions. Front Endocrinol (Lausanne) 2012; 3:22. [PMID: 22649411 PMCID: PMC3355999 DOI: 10.3389/fendo.2012.00022] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 01/29/2012] [Indexed: 11/23/2022] Open
Abstract
The succinate receptor (also known as GPR91) is a G protein-coupled receptor that is closely related to the family of P2Y purinoreceptors. It is expressed in a variety of tissues, including blood cells, adipose tissue, the liver, retina, and kidney. In these tissues, this receptor and its ligand succinate have recently emerged as novel mediators in local stress situations, including ischemia, hypoxia, toxicity, and hyperglycemia. Amongst others, the succinate receptor is involved in recruitment of immune cells to transplanted tissues. Moreover, it was shown to play a key role in the development of diabetic retinopathy. However, most prominently, the role of locally increased succinate levels and succinate receptor activation in the kidney, stimulating the systemic and local renin-angiotensin system, starts to unfold: the succinate receptor is a key mediator in the development of hypertension and possibly fibrosis in diabetes mellitus and metabolic syndrome. This makes the succinate receptor a promising drug target to counteract or prevent cardiovascular and fibrotic defects in these expanding disorders. Recent development of SUCNR1-specific antagonists opens novel possibilities for research in models for these disorders and may eventually provide novel opportunities for the treatment of patients.
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Affiliation(s)
- Ana Carolina Ariza
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical CentreNijmegen, Netherlands
| | - Peter Meinardus T. Deen
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical CentreNijmegen, Netherlands
| | - Joris Hubertus Robben
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical CentreNijmegen, Netherlands
- *Correspondence: Joris Hubertus Robben, Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands. e-mail:
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108
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Abstract
The G protein-coupled succinate and α-ketoglutarate receptors are closely related to the family of P2Y purinoreceptors. Although the α-ketoglutarate receptor is almost exclusively expressed in the kidney, its function is unknown. In contrast, the succinate receptor, SUCRN1, is expressed in a variety of tissues, including blood cells, adipose tissue, liver, retina, and the kidney. Recent evidence suggests SUCRN1 and its succinate ligand are novel detectors of local stress, including ischemia, hypoxia, toxicity, and hyperglycemia. Local levels of succinate in the kidney also activate the renin-angiotensin system and together with SUCRN1 may play a key role in the development of hypertension and the complications of diabetes mellitus, metabolic disease, and liver damage. This makes the succinate receptor a promising drug target to counteract an expanding number of interrelated disorders.
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Affiliation(s)
- Peter M T Deen
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, The Netherlands
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109
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Spath B, Hansen A, Bokemeyer C, Langer F. Succinate reverses in-vitro platelet inhibition by acetylsalicylic acid and P2Y receptor antagonists. Platelets 2011; 23:60-8. [PMID: 21736422 DOI: 10.3109/09537104.2011.590255] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
High on-treatment platelet reactivity has been associated with adverse cardiovascular events in patients receiving anti-platelet agents, but the molecular mechanisms underlying this phenomenon remain incompletely understood. Succinate, a citric acid cycle intermediate, is released into the circulation under conditions of mitochondrial dysfunction due to hypoxic organ damage, including sepsis, stroke, and myocardial infarction. Because the G protein-coupled receptor (GPCR) for succinate, SUCNR1 (GPR91), is present on human platelets, we hypothesized that succinate-mediated platelet stimulation may counteract the pharmacological effects of cyclooxygenase-1 and ADP receptor antagonists. To test this hypothesis in a controlled in-vitro study, washed platelets from healthy donors were treated with acetylsalicylic acid (ASA) or small-molecule P2Y(1) or P2Y(12) inhibitors and subsequently analyzed by light transmittance aggregometry using arachidonic acid (AA), ADP and succinate as platelet agonists. Aggregation in response to succinate alone was highly variable with only 29% of donors showing a (mostly delayed) platelet response. In contrast, succinate reproducibly and concentration-dependently (10-1000 µM) enhanced platelet aggregation in response to low concentrations of exogenous ADP. Furthermore, while succinate alone had no effect in the presence of platelet inhibitors, responsiveness of platelets to ADP after pretreatment with P2Y(1) or P2Y(12) antagonists was fully restored, when platelets were co-stimulated with 100 µM succinate. Similarly, succinate completely (at 1000 µM) or partially (at 100 µM) reversed the inhibitory effect of ASA on AA-induced platelet aggregation. In contrast, succinate failed to restore platelet responsiveness in the presence of both ASA and the P2Y(12) antagonist, suggesting that concomitant signaling via different GPCRs was required. Essentially identical results were obtained, when flow cytometric analysis of surface CD62P expression was used as a different readout for platelet activation. In summary, extracellular succinate may have a co-stimulatory role in platelet aggregation and, by (partially) antagonizing the effects of platelet inhibitors, may contribute to the inter-individual variability frequently observed in platelet function testing.
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Affiliation(s)
- Brigitte Spath
- II. Medizinische Klinik und Poliklinik, Hubertus Wald Tumorzentrum - Universitäres Cancer Center Hamburg (UCCH), Universitätsklinikum Eppendorf, Hamburg, Germany
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110
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Bhuniya D, Umrani D, Dave B, Salunke D, Kukreja G, Gundu J, Naykodi M, Shaikh NS, Shitole P, Kurhade S, De S, Majumdar S, Reddy SB, Tambe S, Shejul Y, Chugh A, Palle VP, Mookhtiar KA, Cully D, Vacca J, Chakravarty PK, Nargund RP, Wright SD, Graziano MP, Singh SB, Roy S, Cai TQ. Discovery of a potent and selective small molecule hGPR91 antagonist. Bioorg Med Chem Lett 2011; 21:3596-602. [PMID: 21571530 DOI: 10.1016/j.bmcl.2011.04.091] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 04/18/2011] [Accepted: 04/22/2011] [Indexed: 01/13/2023]
Abstract
GPR91, a 7TM G-Protein-Coupled Receptor, has been recently deorphanized with succinic acid as its endogenous ligand. Current literature indicates that GPR91 plays role in various pathophysiology including renal hypertension, autoimmune disease and retinal angiogenesis. Starting from a small molecule high-throughput screening hit 1 (hGPR91 IC(50): 0.8 μM)-originally synthesized in Merck for Bradykinin B(1) Receptor (BK(1)R) program, systematic structure-activity relationship study led us to discover potent and selective hGPR91 antagonists e.g. 2c, 4c, and 5 g (IC(50): 7-35 nM; >1000 fold selective against hGPR99, a closest related GPCR; >100 fold selective in Drug Matrix screening). This initial work also led to identification of two structurally distinct and orally bio-available lead compounds: 5g (%F: 26) and 7e (IC(50): 180 nM; >100 fold selective against hGPR99; %F: 87). A rat pharmacodynamic assay was developed to characterize the antagonists in vivo using succinate induced increase in blood pressure. Using two representative antagonists, 2c and 4c, the GPR91 target engagement was subsequently demonstrated using the designed pharmacodynamic assay.
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Affiliation(s)
- Debnath Bhuniya
- Drug Discovery Facility, Advinus Therapeutics, Quantum Towers, Rajiv Gandhi InfoTech Park, Hinjewadi, Pune, India.
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111
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Högberg C, Gidlöf O, Tan C, Svensson S, Nilsson-Öhman J, Erlinge D, Olde B. Succinate independently stimulates full platelet activation via cAMP and phosphoinositide 3-kinase-β signaling. J Thromb Haemost 2011; 9:361-72. [PMID: 21143371 DOI: 10.1111/j.1538-7836.2010.04158.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND The citric cycle intermediate succinate has recently been identified as a ligand for the G-protein-coupled receptor (GPCR) SUCNR1. We have previously found that this receptor is one of the most highly expressed GPCRs in human platelets. OBJECTIVE The aim of this study was to investigate the role of SUCNR1 in platelet aggregation and to explore the signaling pathways of this receptor in platelets. METHODS AND RESULTS Using real-time-PCR, we demonstrated that SUCNR1 is expressed in human platelets at a level corresponding to that of the P2Y(1) receptor. Light transmission aggregation experiments showed dose-dependent aggregation induced by succinate, reaching a maximum response at 0.5 mM. The effect of succinate on platelet aggregation was confirmed with flow cytometry, showing increased surface expression of activated glycoprotein IIb-IIIa and P-selectin. Intracellular SUCNR1 signaling was found to result in decreased cAMP levels, Akt phosphorylation mediated by phosphoinositide 3-kinase-β activation, and receptor desensitization. Furthermore, succinate-induced platelet aggregation was demonstrated to depend on Src, generation of thromboxane A(2), and ATP release. Platelet SUCNR1 is subject to desensitization through both homologous and heterologous mechanisms. In addition, the P2Y(12) receptor inhibitor ticagrelor completely prevented platelet aggregation induced by succinate. CONCLUSIONS Our experiments show that succinate induces full aggregation of human platelets via SUCNR1. Succinate-induced platelet aggregation depends on thromboxane A(2) generation, ATP release, and P2Y(12) activation.
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Affiliation(s)
- C Högberg
- Department of Cardiology, Lund University Hospital, Lund, Sweden
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112
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Abstract
Diabetes mellitus is the most common and rapidly growing cause of end-stage renal disease. A classic hallmark of diabetes pathology is the activation of the intrarenal renin-angiotensin system (RAS), which may lead to hypertension and renal tissue injury, but the mechanism of RAS activation has been elusive. Recently, we described the intrarenal localization of the novel metabolic receptor GPR91 and established some of its functions in diabetes. These include the triggering of renin release in early diabetes via both vascular (endothelial) and tubular (macula densa) sites in the juxtaglomerular apparatus as well as the activation of MAP kinases in the distal nephron-collecting duct, which are important signaling mechanisms in diabetic nephropathy (DN) and renal fibrosis. GPR91 is a cell surface receptor for succinate and during the past few years it has provided a new paradigm for the mechanism of cell stress response in many organs. Beyond its traditional role in the tricarboxylic acid cycle, succinate now has an unexpected hormone-like signaling function, which may provide a feedback between local tissue metabolism, mitochondrial stress, and organ functions. Succinate accumulation in the local tissue environment and GPR91 signaling appear to be important early mechanisms by which cells detect and respond to hyperglycemia and trigger tissue injury in DN. Also, the distal nephron-collecting duct system, which is the major source of (pro)renin in diabetes and has the highest level of GPR91 expression in the kidney, may have an important, active, and early role in the pathogenesis of DN in contrast to the existing glomerulus-centric paradigm.
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Affiliation(s)
- János Peti-Peterdi
- Departments of Physiology and Biophysics, and Medicine, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California, USA.
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113
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Aguiar CJ, Andrade VL, Gomes ERM, Alves MNM, Ladeira MS, Pinheiro ACN, Gomes DA, Almeida AP, Goes AM, Resende RR, Guatimosim S, Leite MF. Succinate modulates Ca(2+) transient and cardiomyocyte viability through PKA-dependent pathway. Cell Calcium 2009; 47:37-46. [PMID: 20018372 DOI: 10.1016/j.ceca.2009.11.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 10/26/2009] [Accepted: 11/04/2009] [Indexed: 10/20/2022]
Abstract
GPR91 is an orphan G-protein-coupled receptor (GPCR) that has been characterized as a receptor for succinate, a citric acid cycle intermediate, in several tissues. In the heart, the role of succinate is unknown. We now report that rat ventricular cardiomyocytes express GPR91. We found that succinate, through GPR91, increases the amplitude and the rate of decline of global Ca(2+) transient, by increasing the phosphorylation levels of ryanodine receptor and phospholamban, two well known Ca(2+) handling proteins. The effects of succinate on Ca(2+) transient were abolished by pre-treatment with adenylyl cyclase and cAMP-dependent protein kinase (PKA) inhibitors. Direct PKA activation by succinate was further confirmed using a FRET-based A-kinase activity reporter. Additionally, succinate decreases cardiomyocyte viability through a caspase-3 activation pathway, effect also prevented by PKA inhibition. Taken together, these observations show that succinate acts as a signaling molecule in cardiomyocytes, modulating global Ca(2+) transient and cell viability through a PKA-dependent pathway.
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Affiliation(s)
- Carla J Aguiar
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte CEP, Brazil
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Vargas SL, Toma I, Kang JJ, Meer EJ, Peti-Peterdi J. Activation of the succinate receptor GPR91 in macula densa cells causes renin release. J Am Soc Nephrol 2009; 20:1002-11. [PMID: 19389848 DOI: 10.1681/asn.2008070740] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Macula densa (MD) cells of the juxtaglomerular apparatus (JGA) are salt sensors and generate paracrine signals that control renal blood flow, glomerular filtration, and release of the prohypertensive hormone renin. We hypothesized that the recently identified succinate receptor GPR91 is present in MD cells and regulates renin release. Using immunohistochemistry, we identified GPR91 in the apical plasma membrane of MD cells. Treatment of MD cells with succinate activated mitogen-activated protein kinases (MAPKs; p38 and extracellular signal-regulated kinases 1/2) and cyclooxygenase 2 (COX-2) and induced the synthesis and release of prostaglandin E(2), a potent vasodilator and classic paracrine mediator of renin release. Using microperfused JGA and real-time confocal fluorescence imaging of quinacrine-labeled renin granules, we detected significant renin release in response to tubular succinate (EC(50) 350 microM). Genetic deletion of GPR91 (GPR91(-/-) mice) or pharmacologic inhibition of MAPK or COX-2 blocked succinate-induced renin release. Streptozotocin-induced diabetes caused GPR91-dependent upregulation of renal cortical phospho-p38, extracellular signal-regulated kinases 1/2, COX-2, and renin content. Salt depletion for 1 wk increased plasma renin activity seven-fold in wild-type mice but only 3.4-fold in GPR91(-/-) mice. In summary, MD cells can sense alterations in local tissue metabolism via accumulation of tubular succinate and GPR91 signaling, which involves the activation of MAPKs, COX-2, and the release of prostaglandin E(2). This mechanism may be integral in the regulation of renin release and activation of the renin-angiotensin system in health and disease.
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Affiliation(s)
- Sarah Laurin Vargas
- Keck School of Medicine, University of Southern California, Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Los Angeles, CA 90033, USA
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116
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Hakak Y, Lehmann-Bruinsma K, Phillips S, Le T, Liaw C, Connolly DT, Behan DP. The role of the GPR91 ligand succinate in hematopoiesis. J Leukoc Biol 2009; 85:837-43. [PMID: 19204147 DOI: 10.1189/jlb.1008618] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Regulation of cellular metabolism by the citric acid cycle occurs in the mitochondria. However, the citric acid cycle intermediate succinate was shown recently to be a ligand for the G-protein-coupled receptor GPR91. Here, we describe a role for succinate and its receptor in the stimulation of hematopoietic progenitor cell (HPC) growth. GPR91 mRNA and protein expression were detected in human bone marrow CD34+ progenitor cells, as well as in erythroid and megakaryocyte cultures and the erythroleukemic cell line TF-1. Treatment of these cell cultures with succinate resulted in increased proliferation rates. The proliferation response of TF-1 cells was pertussis toxin (PTX)-sensitive, suggesting a role for Gi signaling. Proliferation was also blocked when TF-1 cells were transfected with small interfering RNA specific for GPR91. Succinate stimulated activation of the Erk MAPK pathway and inositol phosphate accumulation in a PTX-sensitive manner. Pretreatment of TF-1 cells with the Erk1/2 kinase (MEK) inhibitor PD98059 blocked the proliferation response. Succinate treatment additionally protected TF-1 cells from cell death induced by serum deprivation. Finally, in vivo administration of succinate was found to elevate the levels of hemoglobin, platelets, and neutrophils in a mouse model of chemotherapy-induced myelosuppression. These results suggest that succinate-GPR91 signaling is capable of promoting HPC development.
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Affiliation(s)
- Yaron Hakak
- Arena Pharmaceuticals, Inc., 6166 Nancy Ridge Drive, San Diego, CA 92121, USA.
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117
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Rubic T, Lametschwandtner G, Jost S, Hinteregger S, Kund J, Carballido-Perrig N, Schwärzler C, Junt T, Voshol H, Meingassner JG, Mao X, Werner G, Rot A, Carballido JM. Triggering the succinate receptor GPR91 on dendritic cells enhances immunity. Nat Immunol 2008; 9:1261-9. [PMID: 18820681 DOI: 10.1038/ni.1657] [Citation(s) in RCA: 359] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Accepted: 08/26/2008] [Indexed: 12/18/2022]
Abstract
Succinate acts as an extracellular mediator signaling through the G protein-coupled receptor GPR91. Here we show that dendritic cells had high expression of GPR91. In these cells, succinate triggered intracellular calcium mobilization, induced migratory responses and acted in synergy with Toll-like receptor ligands for the production of proinflammatory cytokines. Succinate also enhanced antigen-specific activation of human and mouse helper T cells. GPR91-deficient mice had less migration of Langerhans cells to draining lymph nodes and impaired tetanus toxoid-specific recall T cell responses. Furthermore, GPR91-deficient allografts elicited weaker transplant rejection than did the corresponding grafts from wild-type mice. Our results suggest that the succinate receptor GPR91 is involved in sensing immunological danger, which establishes a link between immunity and a metabolite of cellular respiration.
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Affiliation(s)
- Tina Rubic
- Novartis Institutes for Biomedical Research, Vienna A-1235, Austria
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118
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Cervera AM, Apostolova N, Crespo FL, Mata M, McCreath KJ. Cells silenced for SDHB expression display characteristic features of the tumor phenotype. Cancer Res 2008; 68:4058-67. [PMID: 18519664 DOI: 10.1158/0008-5472.can-07-5580] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recently, enzymes of the tricarboxylic acid (TCA) cycle have emerged as novel tumor suppressors. In particular, mutations in the nuclear-encoded subunits of succinate dehydrogenase (SDHB, SDHC, and SDHD) cause paragangliomas and pheochromocytomas. Although the mechanism(s) by which disruption of mitochondrial metabolism leads to neoplasia is largely unknown, increasing evidence points to an activation of pseudohypoxia. In this study, we have shown that silencing of SDHB using DNA-based small interfering RNA resulted in major impairments in cellular proliferation, respiration, and a corresponding shift to glycolysis. The levels of reactive oxygen species, however, were unchanged. As expected, hypoxia-inducible factor-1 alpha (HIF-1 alpha) and HIF-2alpha were up-regulated in chronically silenced cells, suggesting that a pseudohypoxic state was attained. In addition, the c-Jun amino-terminal kinase and p38 kinase stress signaling proteins were hyperphosphorylated in SDHB-silenced cells. Microarray analysis showed that >400 genes were influenced (6-fold or more up-regulation or down-regulation) by silencing of SDHB, confirming the importance of the TCA cycle in cellular metabolism. Examples of dysregulated genes included those involved in proliferation, adhesion, and the hypoxia pathway. Of interest, SDHB-silenced cells had a greater capacity to adhere to extracellular matrix components, including fibronectin and laminin, than control cells, thus suggesting a possible mechanism of tumor initiation. Although transient silencing of the HIF-1 alpha transcription factor in SDHB-silenced cells had little effect on the expression of a subset of up-regulated genes, it partially reversed the adhesion phenotype to fibronectin, pointing to a potentially important role for HIF-1 in this process.
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Affiliation(s)
- Ana M Cervera
- Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
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Peti-Peterdi J, Kang JJ, Toma I. Activation of the renal renin-angiotensin system in diabetes--new concepts. Nephrol Dial Transplant 2008; 23:3047-9. [PMID: 18644796 DOI: 10.1093/ndt/gfn377] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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