1
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Wolf P, Beck-Sickinger AG. The ring size of monocyclic ET-1 controls selectivity and signaling efficiency at both endothelin receptor subtypes. J Pept Sci 2021; 27:e3325. [PMID: 33939217 DOI: 10.1002/psc.3325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/12/2021] [Accepted: 03/15/2021] [Indexed: 12/13/2022]
Abstract
Cardiovascular diseases (CVDs) like hypertension are a major cause for death worldwide. In the cardiovascular tissue, the endothelin system-consisting of the receptor subtypes A (ETA R) and B (ETB R) and the mixed agonist endothelin 1 (ET-1)-is a major key player in the regulation of vascular tone and blood pressure. Tight control of this system is required to maintain homeostasis; otherwise, the endothelin system can cause severe CVDs like pulmonary artery hypertension. The high sequence homology between both receptor subtypes limits the development of novel and selective ligands. Identification of small differences in receptor-ligand interactions and determination of selectivity constraints are crucial to fine-tune ligand properties and subsequent signaling events. Here, we report on novel ET-1 analogs and their detailed pharmacological characterization. We generated simplified ET-1-derived monocyclic peptides to provide an accessible synthesis route. By detailed in vitro characterization, we demonstrated that both G protein signaling and the subsequent arrestin recruitment of activated ETB R remain intact, whereas activation of the ETA R depends on the intramolecular ring size. Increasing of the intramolecular ring structure reduces activity at the ETA R and shifts the peptide toward ETB R selectivity. All ET-1 analogs displayed efficient ETB R-mediated signaling by G protein activation and arrestin 3 recruitment. Our study provides in-depth characterization of the ET-1/ETA R and ET-1/ETB R interactions, which has the potential for future development of endothelin-based drugs for CVD treatment. By identification of Lys9 for selective labeling, novel analogs for peptide-mediated shuttling by ET-1 are proposed.
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Affiliation(s)
- Philipp Wolf
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Leipzig, Germany
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2
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Moody TW, Ramos-Alvarez I, Jensen RT. Bombesin, endothelin, neurotensin and pituitary adenylate cyclase activating polypeptide cause tyrosine phosphorylation of receptor tyrosine kinases. Peptides 2021; 137:170480. [PMID: 33385499 DOI: 10.1016/j.peptides.2020.170480] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/17/2020] [Accepted: 12/17/2020] [Indexed: 12/12/2022]
Abstract
Numerous peptides including bombesin (BB), endothelin (ET), neurotensin (NTS) and pituitary adenylate cyclase-activating polypeptide (PACAP) are growth factors for lung cancer cells. The peptides bind to G protein-coupled receptors (GPCRs) resulting in elevated cAMP and/or phosphatidylinositol (PI) turnover. In contrast, growth factors such as epidermal growth factor (EGF) or neuregulin (NRG)-1 bind to receptor tyrosine kinases (RTKs) such as the EGFR or HER3, increasing tyrosine kinase activity, resulting in the phosphorylation of protein substrates such as PI3K or phospholipase (PL)C. Peptide GPCRs can transactivate numerous RTKs, especially members of the EGFR/HER family resulting in increased phosphorylation of ERK, leading to cellular proliferation or increased phosphorylation of AKT, leading to cellular survival. GRCR antagonists and tyrosine kinase inhibitors are useful agents to prevent RTK transactivation and inhibit proliferation of cancer cells.
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Affiliation(s)
- Terry W Moody
- Department of Health and Human Services, National Institutes of Health, National Cancer Institute, Center for Cancer Training, Bethesda, MD, 20892, USA.
| | - Irene Ramos-Alvarez
- National Institute of Diabetes, Digestive and Kidney Disease, Digestive Diseases Branch, 9000 Rockville Pike, Bethesda, MD, 20892 USA
| | - Robert T Jensen
- National Institute of Diabetes, Digestive and Kidney Disease, Digestive Diseases Branch, 9000 Rockville Pike, Bethesda, MD, 20892 USA
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3
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Yang Y, Li M, Zou X, Chen C, Zheng S, Fu C, Chen K, Jose PA, Lan C, Liu Y. Role of GRK4 in the regulation of the renal ETB receptor in hypertension. FASEB J 2020; 34:11594-11604. [PMID: 32687659 DOI: 10.1096/fj.201902552r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 06/07/2020] [Accepted: 06/15/2020] [Indexed: 01/11/2023]
Abstract
The endothelin receptor type B (ETBR) regulates water and electrolyte balance and blood pressure, in part, by inhibiting renal sodium transport. Our preliminary study found that the ETBR-mediated diuresis and natriuresis are impaired in hypertension with unknown mechanism. Persistently increased activity of G protein-coupled receptor kinase 4 (GRK4), caused by increased expression or genetic variants (eg, GRKγ142V), impairs the ability of the kidney to excrete a sodium load, in part, by impairing renal dopamine D1 receptor function through persistent phosphorylation. Our present study found that although renal ETBR expression was not different between Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHRs), renal ETBR phosphorylation was higher in SHRs. The role of hyper-phosphorylation in impaired ETBR-function was supported by results in human (h) GRK4γ transgenic mice. Stimulation of ETBR by BQ3020-induced natriuresis in human (h) GRK4γ wild-type (WT) mice. However, in hGRK4γ 142V transgenic mice, the renal ETBR was hyperphosphorylated and ETBR-mediated natriuresis and diuresis were not evident. There were co-localization and co-immunoprecipitation of ETBR and GRK4 in renal proximal tubule (RPT) cells from both WKY and SHRs but was greater in the latter than the former group. SiRNA-mediated downregulation of GRK4 expression, recovered the impaired inhibitory effect of ETBR on Na+ -K+ -ATPase activity in RPT cells from SHR. In vivo downregulation of renal GRK4 expression, via ultrasound-targeted microbubble destruction, decreased ETBR phosphorylation and restored ETBR-mediated natriuresis and diuresis in SHRs. This study provides a mechanism by which GRK4, via regulation of renal ETBR function, participates in the pathogenesis of hypertension.
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Affiliation(s)
- Yang Yang
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China
| | - Meixiang Li
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China.,The First People's Hospital of Liangjiang New District, Chongqing, P.R. China
| | - Xue Zou
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China
| | - Caiyu Chen
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China
| | - Shuo Zheng
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China
| | - Chunjiang Fu
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China
| | - Ken Chen
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China
| | - Pedro A Jose
- Division of Renal Diseases & Hypertension, Department of Medicine and Pharmacology/Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Cong Lan
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China
| | - Yukai Liu
- Department of Cardiology, Daping Hospital, Third Military Medical University, Chongqing, P.R. China.,Chongqing Institute of Cardiology, Chongqing, P.R. China.,Chongqing Cardiovascular Clinical Research Center, Chongqing, P.R. China.,The First People's Hospital of Liangjiang New District, Chongqing, P.R. China
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4
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Abstract
Endothelial cell nitric oxide (NO) synthase (eNOS), the enzyme responsible for synthesis of NO in endothelial cells, is regulated by complex posttranslational mechanisms. Sinusoidal portal hypertension, a disorder characterized by liver sinusoidal endothelial cell (SEC) injury with resultant reduced eNOS activity and NO production within the liver, has been associated with defects in eNOS protein-protein interactions and posttranslational modifications. We and others have previously identified novel eNOS interactors, including G protein-coupled receptor (GPCR) kinase interactor 1 (GIT1), which we found to play an unexpected stimulatory role in GPCR-mediated eNOS signaling. Here we report that β-arrestin 2 (β-Arr2), a canonical GPCR signaling partner, localizes in SECs with eNOS in a GIT1/eNOS/NO signaling module. Most importantly, we show that β-Arr2 stimulates eNOS activity, and that β-Arr2 expression is reduced and formation of the GIT1/eNOS/NO signaling module is interrupted during liver injury. In β-Arr2-deficient mice, bile duct ligation injury (BDL) led to significantly reduced eNOS activity and to a dramatic increase in portal hypertension compared to BDL in wild-type mice. Overexpression of β-Arr2 in injured or β-Arr2-deficient SECs rescued eNOS function by increasing eNOS complex formation and NO production. We also found that β-Arr2-mediated GIT1/eNOS complex formation is dependent on Erk1/2 and Src, two kinases known to interact with and be activated by β-Arr2 in response to GCPR activation. Our data emphasize that β-Arr2 is an integral component of the GIT1/eNOS/NO signaling pathway and have implications for the pathogenesis of sinusoidal portal hypertension.
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5
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Mazaki Y, Higashi T, Onodera Y, Nam JM, Hashimoto A, Hashimoto S, Horinouchi T, Miwa S. Endothelin type B receptor interacts with the 78-kDa glucose-regulated protein. FEBS Lett 2019; 593:644-651. [PMID: 30801683 DOI: 10.1002/1873-3468.13347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/13/2019] [Accepted: 02/19/2019] [Indexed: 12/21/2022]
Abstract
Endothelin (ET)-1 is involved in the vascular system, cell proliferation and apoptosis. ET receptors consist of ET type A receptor (ETA R) and ET type B receptor (ETB R). ETA R and ETB R generally exhibit opposite responses, although many exceptions exist. In the present study, we attempted to identify ETA R- or ETB R-specific binding proteins to understand the differences in ETA R- and ETB R-mediated responses after ET-1 stimulation. The 78-kDa glucose-regulated protein (GRP78) showed a stronger binding affinity towards ETB R than towards ETA R. Moreover, GRP78 overexpression promoted ETB R-mediated ERK activation and GRP78 silencing suppressed ETB R-mediated ERK activation. Furthermore, ETB R can localize GRP78 to the cell periphery. These results suggest that the interaction of ETB R with GRP78 affects ERK activation and GRP78 localization.
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Affiliation(s)
- Yuichi Mazaki
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Tsunehito Higashi
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yasuhito Onodera
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Jin-Min Nam
- GSQ, GI-CoRE, Hokkaido University, Sapporo, Japan
| | - Ari Hashimoto
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Shigeru Hashimoto
- Laboratory of Immune Regulation, Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Takahiro Horinouchi
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Soichi Miwa
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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6
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Zhang Z, Li Z, Chen W. Down-regulated G protein-coupled receptor kinase 6 leads to apoptosis in multiple myeloma MM1R cells. Exp Ther Med 2018; 16:4253-4259. [PMID: 30402162 DOI: 10.3892/etm.2018.6722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 08/31/2018] [Indexed: 12/14/2022] Open
Abstract
G protein-coupled receptor kinase 6 (GRK6) is highly expressed in multiple myeloma (MM) cell lines, but absent or only weakly expressed in most primary human somatic cells. In the present study, GRK6 expression was assessed in MM patients and healthy individuals by quantitative polymerase chain reaction. Flow cytometry were performed to measure the apoptosis of lentivial-transfected MM1R cells. Western blot analysis was performed to assess the apoptosis and signal transducer and activator of transcription 3 pathway-related factors. The results demonstrated that GRK6 was differentially expressed in individuals who suffered from MM and healthy individuals. Previous studies have shown that downregulating GRK6 has anti-cancer effects in the MM cell line, MM1R. The present study demonstrated that RNA interference-mediated GRK6 knockdown promoted apoptosis in the MM1R cell line. Therefore, we hypothesized that GRK6 plays a significant role in determining the course of MM.
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Affiliation(s)
- Zhiyao Zhang
- Department of Hematology, Beijing Chao Yang Hospital, Capital Medical University, Beijing 100020, P.R. China
| | - Zhenyu Li
- Department of Hematology, The Affiliated Hospital of Xuzhou Medical College, Xuzhou, Jiangsu 221002, P.R. China
| | - Wenming Chen
- Department of Hematology, Beijing Chao Yang Hospital, Capital Medical University, Beijing 100020, P.R. China
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7
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Lutz SZ, Falcenberg M, Machicao F, Peter A, Kächele M, Randrianarisoa E, Lehn-Stefan A, Wagner R, Machann J, Schick F, Heni M, Ullrich A, Fritsche A, Stefan N, Häring HU, Staiger H, Kantartzis K. Single Nucleotide Polymorphisms in the G-Protein Coupled Receptor Kinase 5 (GRK5) Gene are associated with Plasma LDL-Cholesterol Levels in Humans. Sci Rep 2018; 8:7745. [PMID: 29773828 PMCID: PMC5958094 DOI: 10.1038/s41598-018-26055-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 05/02/2018] [Indexed: 12/11/2022] Open
Abstract
Genetically modified mice models suggest an important role for G-protein-coupled receptor kinase 5 (GRK5) in the pathophysiology of obesity and related disorders. We investigated whether single nucleotide polymorphisms (SNPs) in the gene encoding GRK5 affect cardiometabolic traits in humans. We genotyped 3 common SNPs in intron 1 (rs1980030, rs10466210, rs9325562) and one SNP in intron 3 (rs10886471) of GRK5 in 2332 subjects at risk for type 2 diabetes. Total- and visceral fat mass were measured by magnetic resonance (MR) tomography and liver fat content by 1H-MR spectroscopy. Insulin secretion and sensitivity were estimated during an OGTT and measured during the euglycemic, hyperinsulinemic clamp (n = 498). Carriers of the minor allele of rs10466210 and rs1980030 had higher total- and LDL-cholesterol levels (p = 0.0018 and p = 0.0031, respectively, for rs10466210; p = 0.0035 and p = 0.0081, respectively, for rs1980030), independently of gender, age, BMI and lipid-lowering drugs. The effects of rs10466210 withstood Bonferroni correction. Similar associations were observed with apolipoprotein B levels (p = 0.0034 and p = 0.0122, respectively). Carriers of the minor allele of rs10466210 additionally displayed a trend for higher intima-media thickness of the carotid artery (p = 0.075). GRK5 may represent a novel target for strategies aiming at lowering LDL-cholesterol levels and at modifying cardiovascular risk.
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Affiliation(s)
- Stefan Z Lutz
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Mathias Falcenberg
- Department of Molecular Biology, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Fausto Machicao
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Andreas Peter
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Martin Kächele
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Elko Randrianarisoa
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Angela Lehn-Stefan
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Robert Wagner
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Jürgen Machann
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany.,Department of Radiology, Section on Experimental Radiology, University of Tübingen, Tübingen, Germany
| | - Fritz Schick
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany.,Department of Radiology, Section on Experimental Radiology, University of Tübingen, Tübingen, Germany
| | - Martin Heni
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Axel Ullrich
- Department of Molecular Biology, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Andreas Fritsche
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Norbert Stefan
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Hans-Ulrich Häring
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Harald Staiger
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research (DZD), Tübingen, Germany.,Institute of Pharmaceutical Sciences, Department of Pharmacy and Biochemistry, University of Tübingen, Tübingen, Germany
| | - Konstantinos Kantartzis
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany. .,Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the Eberhard-Karls-University of Tübingen, Tübingen, Germany. .,German Center for Diabetes Research (DZD), Tübingen, Germany.
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8
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A new inhibitor of the β-arrestin/AP2 endocytic complex reveals interplay between GPCR internalization and signalling. Nat Commun 2017; 8:15054. [PMID: 28416805 PMCID: PMC5399295 DOI: 10.1038/ncomms15054] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 02/23/2017] [Indexed: 02/08/2023] Open
Abstract
In addition to G protein-coupled receptor (GPCR) desensitization and endocytosis, β-arrestin recruitment to ligand-stimulated GPCRs promotes non-canonical signalling cascades. Distinguishing the respective contributions of β-arrestin recruitment to the receptor and β-arrestin-promoted endocytosis in propagating receptor signalling has been limited by the lack of selective analytical tools. Here, using a combination of virtual screening and cell-based assays, we have identified a small molecule that selectively inhibits the interaction between β-arrestin and the β2-adaptin subunit of the clathrin adaptor protein AP2 without interfering with the formation of receptor/β-arrestin complexes. This selective β-arrestin/β2-adaptin inhibitor (Barbadin) blocks agonist-promoted endocytosis of the prototypical β2-adrenergic (β2AR), V2-vasopressin (V2R) and angiotensin-II type-1 (AT1R) receptors, but does not affect β-arrestin-independent (transferrin) or AP2-independent (endothelin-A) receptor internalization. Interestingly, Barbadin fully blocks V2R-stimulated ERK1/2 activation and blunts cAMP accumulation promoted by both V2R and β2AR, supporting the concept of β-arrestin/AP2-dependent signalling for both G protein-dependent and -independent pathways. Beta-arrestins play central roles in the mechanisms regulating GPCR signalling and trafficking. Here the authors identify a selective inhibitor of the interaction between β-arrestin and the β2-adaptin subunit of the clathrin adaptor protein AP-2, which they use to dissect the role of the β-arrestin/β2-adaptin interaction in GPCR signalling.
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9
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Liu S, Premont RT, Singh S, Rockey DC. Caveolin 1 and G-Protein-Coupled Receptor Kinase-2 Coregulate Endothelial Nitric Oxide Synthase Activity in Sinusoidal Endothelial Cells. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:896-907. [PMID: 28162981 DOI: 10.1016/j.ajpath.2016.11.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 11/23/2016] [Accepted: 11/28/2016] [Indexed: 12/14/2022]
Abstract
Liver injury leads to a vasculopathy in which post-translational modifications of endothelial nitric oxide synthase (eNOS) lead to impaired nitric oxide synthesis. We hypothesized that caveolin 1 (CAV1), a well-known eNOS interactor, regulates eNOS activity in sinusoidal endothelial cells (SECs) via its interaction with G-protein-coupled receptor kinase-2 (GRK2) that also post-translationally modifies eNOS. Liver injury with portal hypertension was established using bile duct ligation in rats. CAV1 function was modified using a CAV1 scaffolding domain construct and cDNAs encoding wild-type CAV1, and CAV1 phosphorylation was increased in injured SECs, resulting in increased GRK2-CAV1 interaction and decreased eNOS activity. In injured SECs, endothelin-1 blocked CAV1 phosphorylation induced by CAV1 scaffolding domain, indicating that CAV1 interaction with GRK2 is inversely regulated by endothelin-1 and CAV1 scaffolding domain after liver injury. In addition, after transduction with DNA encoding wild-type CAV1 into SECs isolated from Cav1-deficient mice, GRK2 association with CAV1 was evident, whereas transduction with a dominant negative CAV1 mutated at tyrosine 14 reduced the interaction. Finally, isoproterenol-induced GRK2 phosphorylation enhanced CAV1-GRK2 interaction and reduced eNOS activity. Our data suggest a novel mechanism and model in which CAV1 phosphorylation facilitates CAV1 scaffolding and GRK2-CAV1 interaction, thus clustering eNOS within a complex that inhibits eNOS activity. This process takes place in injured, but not in normal, SECs.
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Affiliation(s)
- Songling Liu
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Richard T Premont
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Shweta Singh
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Don C Rockey
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina.
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10
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Kung JE, Jura N. Structural Basis for the Non-catalytic Functions of Protein Kinases. Structure 2016; 24:7-24. [PMID: 26745528 DOI: 10.1016/j.str.2015.10.020] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 09/18/2015] [Accepted: 10/04/2015] [Indexed: 01/07/2023]
Abstract
Protein kinases are known primarily for their ability to phosphorylate protein substrates, which constitutes an essential biological process. Recently, compelling evidence has accumulated that the functions of many protein kinases extend beyond phosphorylation and include an impressive spectrum of non-catalytic roles, such as scaffolding, allosteric regulation, or even protein-DNA interactions. How the conserved kinase fold shared by all metazoan protein kinases can accomplish these diverse tasks in a specific and regulated manner is poorly understood. In this review, we analyze the molecular mechanisms supporting phosphorylation-independent signaling by kinases and attempt to identify common and unique structural characteristics that enable kinases to perform non-catalytic functions. We also discuss how post-translational modifications, protein-protein interactions, and small molecules modulate these non-canonical kinase functions. Finally, we highlight current efforts in the targeted design of small-molecule modulators of non-catalytic kinase functions, a new pharmacological challenge for which structural considerations are more important than ever.
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Affiliation(s)
- Jennifer E Kung
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Natalia Jura
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
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11
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The pathophysiological role of astrocytic endothelin-1. Prog Neurobiol 2016; 144:88-102. [DOI: 10.1016/j.pneurobio.2016.04.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/23/2016] [Accepted: 04/25/2016] [Indexed: 12/13/2022]
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12
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Endothelin-1 (ET-1) induces resistance to bortezomib in human multiple myeloma cells via a pathway involving the ETB receptor and upregulation of proteasomal activity. J Cancer Res Clin Oncol 2016; 142:2141-58. [PMID: 27530445 DOI: 10.1007/s00432-016-2216-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 08/04/2016] [Indexed: 01/24/2023]
Abstract
PURPOSE Bortezomib (BTZ) is used for the treatment of multiple myeloma (MM). However, a significant proportion of patients may be refractory to the drug. This study aimed to investigate whether the endothelin (ET-1) axis may act as an escape mechanism to treatment with bortezomib in MM cells. METHODS NCI-H929 and RPMI-8226 (human MM cell lines) were cultured with or without ET-1, BTZ, and inhibitors of the endothelin receptors. ET-1 levels were determined by ELISA, while the protein levels of its receptors and of the PI3K and MAPK pathways' components by western blot. Effects of ET-1 on cell proliferation were studied by MTT and on the ubiquitin proteasome pathway by assessing the chymotryptic activity of the 20S proteasome in cell lysates. RESULTS Endothelin receptors A and B (ETAR and ETBR, respectively) were found to be expressed in both cell lines, with the RPMI-8226 cells that are considered resistant to BTZ, expressing higher levels of ETBR and in addition secreting ET-1. Treatment of the NCI-H929 cells with ET-1 increased proliferation, while co-incubation of these cells with ET-1 and BTZ decreased BTZ efficacy with concomitant upregulation of 20S proteasomal activity. Si-RNA silencing or chemical blockade of ETBR abrogated the protective effects of ET-1. Finally, data suggest that the predominant signaling pathway involved in ET-1/ETBR-induced BTZ resistance in MM cells may be the MAPK pathway. CONCLUSION Our data suggest a possible role of the ET-1/ETBR axis in regulating the sensitivity of MM cells to BTZ. Thus, combining bortezomib with strategies to target the ET-1 axis could prove to be a novel promising therapeutic approach in MM.
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“Barcode” and Differential Effects of GPCR Phosphorylation by Different GRKs. METHODS IN PHARMACOLOGY AND TOXICOLOGY 2016. [DOI: 10.1007/978-1-4939-3798-1_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Skovsted GF, Kilic S, Edvinsson L. Endothelin-1 and Endothelin-3 Regulate Endothelin Receptor Expression in Rat Coronary Arteries. Basic Clin Pharmacol Toxicol 2015; 117:297-305. [PMID: 25891848 DOI: 10.1111/bcpt.12407] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 04/07/2015] [Indexed: 11/30/2022]
Abstract
In ischaemic hearts, endothelin (ET) levels are increased, and vasoconstrictor responses to ET-1 are greatly enhanced. We previously reported that ETB receptors are up-regulated in the smooth muscle layer of coronary arteries after myocardial ischaemia-reperfusion and that the MEK-ERK1/2 signalling pathway is involved in ETB receptor up-regulation. Whether ETs are directly involved in receptor regulation has not been determined. We suggest that ET-1 and ET-3 alter the expression/activity of ET receptors in coronary vascular smooth muscle cells. Vasoconstrictor responses were studied in endothelium-denuded coronary artery segments from rats that were subjected to experimental ischaemia-reperfusion or in organ-cultured segments. Post-ischaemic and cultured coronary arteries exhibited similar increased sensitivity to ET-3. ETA receptor-mediated vasoconstriction was dominant in fresh and non-ischaemic arteries. Organ culture significantly up-regulated ETB receptors and down-regulated ETA receptor expression. Co-incubation with ET-1 (1 nM) or ET-3 (100 nM) induced further down-regulation of the ETA receptor mRNA, while the function and protein level of ETA remained unchanged. ET-3 (100 nM) further up-regulated ETB receptor mRNA and proteins but abolished ETB receptor-mediated vasoconstriction, suggesting a desensitization of ETB receptors that was not observed with ET-3 (1 nM). In conclusion, ET-1, which is the most prevalent isoform in the cardiovascular system, induces down-regulation of ETA receptor expression without changing ETA or ETB receptor function or protein levels. Intermediate concentrations of ET-3 had an effect that was similar to that of ET-1, such that high concentrations of ET-3 (100 nM) up-regulated the ETB receptor at the gene and protein levels but switched off the function of the ETB receptors via desensitization.
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Affiliation(s)
- Gry Freja Skovsted
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup Hospital, Copenhagen, Denmark
| | - Semsi Kilic
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup Hospital, Copenhagen, Denmark
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup Hospital, Copenhagen, Denmark.,Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University, Lund, Sweden
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Szteyn K, Gomez R, Berg KA, Jeske NA. Divergence in endothelin-1- and bradykinin-activated store-operated calcium entry in afferent sensory neurons. ASN Neuro 2015; 7:7/2/1759091415578714. [PMID: 25873305 PMCID: PMC4397213 DOI: 10.1177/1759091415578714] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Endothelin-1 (ET-1) and bradykinin (BK) are endogenous peptides that signal through Gαq/11-protein coupled receptors (GPCRs) to produce nociceptor sensitization and pain. Both peptides activate phospholipase C to stimulate Ca2+ accumulation, diacylglycerol production, and protein kinase C activation and are rapidly desensitized via a G-protein receptor kinase 2-dependent mechanism. However, ET-1 produces a greater response and longer lasting nocifensive behavior than BK in multiple models, indicating a potentially divergent signaling mechanism in primary afferent sensory neurons. Using cultured sensory neurons, we demonstrate significant differences in both Ca2+ influx and Ca2+ release from intracellular stores following ET-1 and BK treatments. As intracellular store depletion may contribute to the regulation of other signaling cascades downstream of GPCRs, we concentrated our investigation on store-operated Ca2+ channels. Using pharmacological approaches, we identified transient receptor potential canonical channel 3 (TRPC3) as a dominant contributor to Ca2+ influx subsequent to ET-1 treatment. On the other hand, BK treatment stimulated Orai1 activation, with only minor input from TRPC3. Taken together, data presented here suggest that ET-1 signaling targets TRPC3, generating a prolonged Ca2+ signal that perpetuates nocifensive responses. In contrast, Orai1 dominates as the downstream target of BK receptor activation and results in transient intracellular Ca2+ increases and abridged nocifensive responses.
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Affiliation(s)
- Kalina Szteyn
- Department of Oral and Maxillofacial Surgery, University of Texas Health Science Center at San Antonio, TX, USA
| | - Ruben Gomez
- Department of Oral and Maxillofacial Surgery, University of Texas Health Science Center at San Antonio, TX, USA
| | - Kelly A Berg
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, TX, USA
| | - Nathaniel A Jeske
- Department of Oral and Maxillofacial Surgery, University of Texas Health Science Center at San Antonio, TX, USA Department of Pharmacology, University of Texas Health Science Center at San Antonio, TX, USA Department of Physiology, University of Texas Health Science Center at San Antonio, TX, USA
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Du QH, Han L, Jiang JJ, Xu Y, Li WH, Li PT, Wang XY, Jia X. Glytan decreases portal pressure via mesentery vasoconstriction in portal hypertensive rats. World J Gastroenterol 2014; 20:16674-16682. [PMID: 25469036 PMCID: PMC4248211 DOI: 10.3748/wjg.v20.i44.16674] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 04/28/2014] [Accepted: 05/26/2014] [Indexed: 02/07/2023] Open
Abstract
AIM: To investigate the effects of Glytan on splanchnic hemodynamics and its reduction of portal pressure in portal hypertensive rats.
METHODS: Glytan (Ganluotong in Chinese), is composed of salvianolic acid B and diammonium glycyrrhizinate. Portal hypertension (PHT) was induced in the rats by common bile duct ligation (BDL). Hemodynamic studies were performed using the colored microsphere method. Radioimmunoassay (RIA) was used to determine endothelin (ET)-1 levels in the mesenteric circulation. Western blotting methods were used to investigate the effect of Glytan on ET A receptor (ETAR), ET B receptor (ETBR), endothelial NO synthase (eNOS), G-protein-coupled receptor kinase (GRK)2, and β-arrestin 2 expression in the mesentery. The mRNA of ETAR and ETBR was determined using real-time polymerase chain reaction.
RESULTS: Treatment with Glytan reduced portal pressure (PP) and portal territory blood flow (PTBF) and increased both mean arterial pressure (MAP) and splanchnic vascular resistance (SVR). Especially at 4 wk, PP decreased by about 40%, while MAP increased by 13%, SVR increased by 12%, and PTBF decreased by about 21%. The effect of blood flow reduction was greatest in the mesentery (about 33%) at 4 wk. The mesenteric circulation ET-1 levels of BDL rats were lower and negatively correlated with PP at 4 wk. Glytan can increase mesenteric ET-1 content and inhibit ETBR, eNOS, GRK2, and β-arrestin 2 expression in the mesentery. Moreover, Glytan showed no effect on the expression of ETAR protein and mRNA.
CONCLUSION: The decreased PP and PTBF observed after Glytan treatment were related to increased mesenteric vasoconstriction and increased receptor sensitivity to vasoconstrictor.
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Le Bourhis M, Rimbaud S, Grebert D, Congar P, Meunier N. Endothelin uncouples gap junctions in sustentacular cells and olfactory ensheathing cells of the olfactory mucosa. Eur J Neurosci 2014; 40:2878-87. [PMID: 24995882 DOI: 10.1111/ejn.12665] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 05/28/2014] [Accepted: 06/02/2014] [Indexed: 11/30/2022]
Abstract
Several factors modulate the first step of odour detection in the rat olfactory mucosa (OM). Among others, vasoactive peptides such as endothelin might play multifaceted roles in the different OM cells. Like their counterparts in the central nervous system, the olfactory sensory neurons are encompassed by different glial-like non-neuronal OM cells; sustentacular cells (SCs) surround their cell bodies, whereas olfactory ensheathing cells (OECs) wrap their axons. Whereas SCs maintain both the structural and ionic integrity of the OM, OECs assure protection, local blood flow control and guiding of olfactory sensory neuron axons toward the olfactory bulb. We previously showed that these non-neuronal OM cells are particularly responsive to endothelin in vitro. Here, we confirmed that the endothelin system is strongly expressed in the OM using in situ hybridization. We then further explored the effects of endothelin on SCs and OECs using electrophysiological recordings and calcium imaging approaches on both in vitro and ex vivo OM preparations. Endothelin induced both robust calcium signals and gap junction uncoupling in both types of cells. This latter effect was mimicked by carbenoxolone, a known gap junction uncoupling agent. However, although endothelin is known for its antiapoptotic effect in the OM, the uncoupling of gap junctions by carbenoxolone was not sufficient to limit the cellular death induced by serum deprivation in OM primary culture. The functional consequence of the endothelin 1-induced reduction of the gap junctional communication between OM non-neuronal cells thus remains to be elucidated.
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Affiliation(s)
- Mikaël Le Bourhis
- Université d'Evry Val d'Essone, Evry, France; Domaine de Vilvert, INRA, UR1197 Neurobiologie de l'Olfaction et Modélisation en Imagerie, Biologie de l'Olfaction et Biosenseurs, Jouy en Josas, France; Neuro-Sud, IFR 144, Paris, France
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18
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Xia Z, Yang T, Wang Z, Dong J, Liang C. GRK5 intronic (CA)n polymorphisms associated with type 2 diabetes in Chinese Hainan Island. PLoS One 2014; 9:e90597. [PMID: 24594703 PMCID: PMC3940906 DOI: 10.1371/journal.pone.0090597] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Accepted: 02/01/2014] [Indexed: 12/19/2022] Open
Abstract
A genome-wide association study had showed G-protein-coupled receptor kinase 5 (GRK5) rs10886471 was related to the risk of type 2 diabetes mellitus (T2DM) through upregulated GRK5 mRNA expression. Rs10886471 is located in the intron region of GRK5. However, the mechanism by which intronic SNP affects gene expression remains unclear, whether the effect on gene expression depends on the intronic short tandem repeat (STR) (CA)n splicing regulator or not. Here we investigated the STR (CA)n polymorphism in rs10886471 and further discussed its role in the T2DM risk of Chinese Hainan Island individuals. A total of 1164 subjects were recruited and classified into a normal fasting glucose (NFG) group, an impaired fasting glucose (IFG) group, an impaired glucose tolerance (IGT) group, and a T2DM group. STR (CA)n polymorphisms were detected through polymerase chain reaction and sequencing. Five intronic (CA)n alleles, (CA)15 to (CA)19, were identified in GRK5 rs10886471. Only the (CA)16 allele was significantly associated with increased prediabetes and T2DM risk [odds ratio (OR)>1, P<0.05]. Conversely, multiple alleles without any (CA)16 protected against prediabetes and T2DM (0<OR<1, P<0.05). In summary, rs10886471 acts as both an SNP and an STR. The rs10886471 intronic SNP causes GRK5 overexpression the subsequent risk of T2DM may be due to the rs10886471 intronic STR (CA)n splicing enhancer. Further studies should focus on verifying these finding using a large sample size and analyzing the splicing mechanism of intronic (CA)n in rs10886471.
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Affiliation(s)
- Zhenfang Xia
- Division of Health Statistics, School of Public Health, Central South University, City of Changsha, Province Hunan, China
| | - Tubao Yang
- Division of Health Statistics, School of Public Health, Central South University, City of Changsha, Province Hunan, China
- * E-mail:
| | - Zhuansuo Wang
- Department of Endocrinology, the Affiliated Hospital of Hainan Medical College, City of Haikou, Province Hainan, China
| | - Jianping Dong
- Transgenic Laboratory, Hainan Medical College, City of Haikou, Province Hainan, China
| | - Chunyan Liang
- Outpatients Department, Community Health Service Center of Xiuying, City of Haikou, Province Hainan, China
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19
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Gärtner F, Seidel T, Schulz U, Gummert J, Milting H. Desensitization and internalization of endothelin receptor A: impact of G protein-coupled receptor kinase 2 (GRK2)-mediated phosphorylation. J Biol Chem 2013; 288:32138-32148. [PMID: 24064210 DOI: 10.1074/jbc.m113.461566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endothelin receptor A (ETA), a G protein-coupled receptor, mediates endothelin signaling, which is regulated by GRK2. Three Ser and seven Thr residues recently proven to be phosphoacceptor sites are located in the C-terminal extremity (CTE) of the receptor following its palmitoylation site. We created various phosphorylation-deficient ETA mutants. The phospholipase C activity of mutant receptors in HEK-293 cells was analyzed during continuous endothelin stimulation to investigate the impact of phosphorylation sites on ETA desensitization. Total deletion of phosphoacceptor sites in the CTE affected proper receptor regulation. However, proximal and distal phosphoacceptor sites both turned out to be sufficient to induce WT-like desensitization. Overexpression of the Gαq coupling-deficient mutant GRK2-D110A suppressed ETA-WT signaling but failed to decrease phospholipase C activity mediated by the phosphorylation-deficient mutant ETA-6PD. In contrast, GRK2-WT acted on both receptors, whereas the kinase-inactive mutant GRK2-D110A/K220R failed to inhibit signaling of ETA-WT and ETA-6PD. This demonstrates that ETA desensitization involves at least two autonomous GRK2-mediated components: 1) a phosphorylation-independent signal decrease mediated by blocking of Gαq and 2) a mechanism involving phosphorylation of Ser and Thr residues in the CTE of the receptor in a redundant fashion, able to incorporate either proximal or distal phosphoacceptor sites. High level transfection of GRK2 variants influenced signaling of ETA-WT and ETA-6PD and hints at an additional phosphorylation-independent regulatory mechanism. Furthermore, internalization of mRuby-tagged receptors was observed with ETA-WT and the phosphorylation-deficient mutant ETA-14PD (lacking 14 phosphoacceptor sites) and turned out to be based on a phosphorylation-independent mechanism.
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Affiliation(s)
- Florian Gärtner
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Thorsten Seidel
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld University, D-33501 Bielefeld, Germany
| | - Uwe Schulz
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Jan Gummert
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Hendrik Milting
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen.
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Drawnel FM, Archer CR, Roderick HL. The role of the paracrine/autocrine mediator endothelin-1 in regulation of cardiac contractility and growth. Br J Pharmacol 2013; 168:296-317. [PMID: 22946456 DOI: 10.1111/j.1476-5381.2012.02195.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 08/23/2012] [Accepted: 08/28/2012] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Endothelin-1 (ET-1) is a critical autocrine and paracrine regulator of cardiac physiology and pathology. Produced locally within the myocardium in response to diverse mechanical and neurohormonal stimuli, ET-1 acutely modulates cardiac contractility. During pathological cardiovascular conditions such as ischaemia, left ventricular hypertrophy and heart failure, myocyte expression and activity of the entire ET-1 system is enhanced, allowing the peptide to both initiate and maintain maladaptive cellular responses. Both the acute and chronic effects of ET-1 are dependent on the activation of intracellular signalling pathways, regulated by the inositol-trisphosphate and diacylglycerol produced upon activation of the ET(A) receptor. Subsequent stimulation of protein kinases C and D, calmodulin-dependent kinase II, calcineurin and MAPKs modifies the systolic calcium transient, myofibril function and the activity of transcription factors that coordinate cellular remodelling. The precise nature of the cellular response to ET-1 is governed by the timing, localization and context of such signals, allowing the peptide to regulate both cardiomyocyte physiology and instigate disease. LINKED ARTICLES This article is part of a themed section on Endothelin. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.168.issue-1.
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Affiliation(s)
- Faye M Drawnel
- Babraham Research Campus, Babraham Institute, Cambridge, UK
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21
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Du QH, Han L, Jiang JJ, Li PT, Wang XY, Jia X. Increased endothelin receptor B and G protein coupled kinase-2 in the mesentery of portal hypertensive rats. World J Gastroenterol 2013; 19:2065-2072. [PMID: 23599626 PMCID: PMC3623984 DOI: 10.3748/wjg.v19.i13.2065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 02/06/2013] [Indexed: 02/06/2023] Open
Abstract
AIM: To elucidate the mechanisms of mesenteric vasodilation in portal hypertension (PHT), with a focus on endothelin signaling.
METHODS: PHT was induced in rats by common bile duct ligation (CBDL). Portal pressure (PP) was measured directly via catheters placed in the portal vein tract. The level of endothelin-1 (ET-1) in the mesenteric circulation was determined by radioimmunoassay, and the expression of the endothelin A receptor (ETAR) and endothelin B receptor (ETBR) was assessed by immunofluorescence and Western blot. Additionally, expression of G protein coupled kinase-2 (GRK2) and β-arrestin 2, which influence endothelin receptor sensitivity, were also studied by Western blot.
RESULTS: PP of CBDL rats increased significantly (11.89 ± 1.38 mmHg vs 16.34 ± 1.63 mmHg). ET-1 expression decreased in the mesenteric circulation 2 and 4 wk after CBDL. ET-1 levels in the systemic circulation of CBDL rats were increased at 2 wk and decreased at 4 wk. There was no change in ETAR expression in response to CBDL; however, increased expression of ETBR in the endothelial cells of mesenteric arterioles and capillaries was observed. In sham-operated rats, ETBR was mainly expressed in the CD31+ endothelial cells of the arterioles. With development of PHT, in addition to the endothelial cells, ETBR expression was noticeably detectable in the SMA+ smooth muscle cells of arterioles and in the CD31+ capillaries. Following CBDL, increased expression of GRK2 was also found in mesenteric tissue, though there was no change in the level of β-arrestin 2.
CONCLUSION: Decreased levels of ET-1 and increased ETBR expression in the mesenteric circulation following CBDL in rats may underlie mesenteric vasodilation in individuals with PHT. Mechanistically, increased GRK2 expression may lead to desensitization of ETAR, as well as other vasoconstrictors, promoting this vasodilatory effect.
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Choisy SCM, James AF, Hancox JC. Acute desensitization of acetylcholine and endothelin-1 activated inward rectifier K+ current in myocytes from the cardiac atrioventricular node. Biochem Biophys Res Commun 2012; 423:496-502. [PMID: 22683635 PMCID: PMC3400056 DOI: 10.1016/j.bbrc.2012.05.148] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 05/26/2012] [Indexed: 01/30/2023]
Abstract
The atrioventricular node (AVN) is a vital component of the pacemaker-conduction system of the heart, co-ordinating conduction of electrical excitation from cardiac atria to ventricles and acting as a secondary pacemaker. The electrical behaviour of the AVN is modulated by vagal activity via activation of muscarinic potassium current, IKACh. However, it is not yet known if this response exhibits ‘fade’ or desensitization in the AVN, as established for the heart’s primary pacemaker – the sinoatrial node. In this study, acute activation of IKACh in rabbit single AVN cells was investigated using whole-cell patch clamp at 37 °C. 0.1–1 μM acetylcholine (ACh) rapidly activated a robust IKACh in AVN myocytes during a descending voltage-ramp protocol. This response was inhibited by tertiapin-Q (TQ; 300 nM) and by the M2 muscarinic ACh receptor antagonist AFDX-116 (1 μM). During sustained ACh exposure the elicited IKACh exhibited bi-exponential fade (τf of 2.0 s and τs 76.9 s at −120 mV; 1 μM ACh). 10 nM ET-1 elicited a current similar to IKACh, which faded with a mono-exponential time-course (τ of 52.6 s at −120 mV). When ET-1 was applied following ACh, the ET-1 activated response was greatly attenuated, demonstrating that ACh could desensitize the response to ET-1. For neither ACh nor ET-1 was the rate of current fade dependent upon the initial response magnitude, which is inconsistent with K+ flux mediated changes in electrochemical driving force as the underlying mechanism. Collectively, these findings demonstrate that TQ sensitive inwardly rectifying K+ current in cardiac AVN cells, elicited by M2 muscarinic receptor or ET-1 receptor activation, exhibits fade due to rapid desensitization.
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Affiliation(s)
- Stéphanie C M Choisy
- School of Physiology & Pharmacology and Cardiovascular Research Laboratories, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
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Caballero-George C, Sorkalla T, Jakobs D, Bolaños J, Raja H, Shearer C, Bermingham E, Häberlein H. Fluorescence correlation spectroscopy in drug discovery: study of Alexa532-endothelin 1 binding to the endothelin ETA receptor to describe the pharmacological profile of natural products. ScientificWorldJournal 2012; 2012:524169. [PMID: 22623909 PMCID: PMC3353486 DOI: 10.1100/2012/524169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 12/12/2011] [Indexed: 11/17/2022] Open
Abstract
Fluorescence correlation spectroscopy and the newly synthesized Alexa532-ET1 were used to study the dynamics of the endothelin ETA receptor-ligand complex alone and under the influence of a semisynthetic selective antagonist and a fungal extract on living A10 cells. Dose-dependent increase of inositol phosphate production was seen for Alexa532-ET1, and its binding was reduced to 8% by the selective endothelin ETA antagonist BQ-123, confirming the specific binding of Alexa532-ET1 to the endothelin ETA receptor. Two different lateral mobilities of the receptor-ligand complexes within the cell membrane were found allowing the discrimination of different states for this complex. BQ-123 showed a strong binding affinity to the “inactive” receptor state characterized by the slow diffusion time constant. A similar effect was observed for the fungal extract, which completely displaced Alexa532-ET1 from its binding to the “inactive” receptor state. These findings suggest that both BQ-123 and the fungal extract act as inverse agonists.
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Affiliation(s)
- Catherina Caballero-George
- Department of Molecular Pharmacology and Pharmacognosy, Drug Discovery Center, Institute for Scientific Research and High Technology Services, Panama City, Panama.
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The connection between GRKs and various signaling pathways involved in diabetic nephropathy. Mol Biol Rep 2012; 39:7717-26. [PMID: 22350265 DOI: 10.1007/s11033-012-1608-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 01/24/2012] [Indexed: 01/11/2023]
Abstract
Diabetic nephropathy (DN) is a known microvascular complication in patients with diabetes mellitus. DN has become one of the main causes of death in diabetic patients. The occurrence and development of DN results from the comprehensive action of multi-factors, though the exact mechanism is not very clear. Recently, a study found that numerous pathways are activated during the course of the disease, including the PGE2-EP-G protein system, the renin-angiotensin system, protein kinase C, MAPK and oxidative stress, and transforming growth factor-β. G protein-coupled receptor kinases (GRKs), specifically recognize and phosphorylate agonist-activated G protein-coupled receptors, which play a major role in the above-mentioned pathways. The purpose of this paper is to review current information concerning the connection between GRKs and various signaling pathways involved in DN.
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25
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Liu S, Premont RT, Rockey DC. G-protein-coupled receptor kinase interactor-1 (GIT1) is a new endothelial nitric-oxide synthase (eNOS) interactor with functional effects on vascular homeostasis. J Biol Chem 2012; 287:12309-20. [PMID: 22294688 DOI: 10.1074/jbc.m111.320465] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Endothelial cell nitric-oxide (NO) synthase (eNOS), the enzyme responsible for synthesis of NO in the vasculature, undergoes extensive post-translational modifications that modulate its activity. Here we have identified a novel eNOS interactor, G-protein-coupled receptor (GPCR) kinase interactor-1 (GIT1), which plays an unexpected role in GPCR stimulated NO signaling. GIT1 interacted with eNOS in the endothelial cell cytoplasm, and this robust association was associated with stimulatory eNOS phosphorylation (Ser(1177)), enzyme activation, and NO synthesis. GIT1 knockdown had the opposite effect. Additionally, GIT1 expression was reduced in sinusoidal endothelial cells after liver injury, consistent with previously described endothelial dysfunction in this disease. Re-expression of GIT1 after liver injury rescued the endothelial phenotype. These data emphasize the role of GPCR signaling partners in eNOS function and have fundamental implications for vascular disorders involving dysregulated eNOS.
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Affiliation(s)
- Songling Liu
- University of Texas Southwestern Medical Center, Division of Digestive and Liver Diseases, Dallas, Texas 75390, USA
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Hauger RL, Olivares-Reyes JA, Dautzenberg FM, Lohr JB, Braun S, Oakley RH. Molecular and cell signaling targets for PTSD pathophysiology and pharmacotherapy. Neuropharmacology 2011; 62:705-14. [PMID: 22122881 DOI: 10.1016/j.neuropharm.2011.11.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 11/01/2011] [Accepted: 11/14/2011] [Indexed: 12/20/2022]
Abstract
The reasons for differences in vulnerability or resilience to the development of posttraumatic stress disorder (PTSD) are unclear. Here we review key genetic diatheses and molecular targets especially signaling pathways that mediate responses to trauma and severe stress and their potential contribution to the etiology of PTSD. Sensitization of glucocorticoid receptor (GR) signaling and dysregulation of GR modulators FKBP5, STAT5B, Bcl-2, and Bax have been implicated in PTSD pathophysiology. Furthermore, Akt, NFκB, MKP-1, and p11, which are G protein-coupled receptor (GPCR) pathway molecules, can promote or prevent sustained high anxiety- and depressive-like behavior following severe stress. Agonist-induced activation of the corticotropin releasing factor CRF(1) receptor is crucial for survival in the context of serious danger or trauma, but persistent CRF(1) receptor hypersignaling when a threatening or traumatic situation is no longer present is maladaptive. CRF(1) receptor single nucleotide polymorphisms (SNPs) can confer susceptibility or resilience to childhood trauma while a SNP for the PAC1 receptor, another class B1 GPCR, has been linked genetically to PTSD. GRK3 phosphorylation of the CRF(1) receptor protein and subsequent binding of βarrestin2 rapidly terminate Gs-coupled CRF(1) receptor signaling by homologous desensitization. A deficient GRK-βarrestin2 mechanism would result in excessive CRF(1) receptor signaling thereby contributing to PTSD and co-morbid posttraumatic depression. Clinical trials are needed to assess if small molecule CRF(1) receptor antagonists are effective prophylactic agents when administered immediately after trauma. βarrestin2-biased agonists for CRF receptors and possibly other GPCRs implicated in PTSD, however, may prove to be novel pharmacotherapy with greater selectivity and therapeutic efficacy. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
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Affiliation(s)
- Richard L Hauger
- Center of Excellence for Stress and Mental Health, VA Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, USA.
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Abstract
There is immunohistochemical evidence for endothelin (ET) receptors in satellite glial cells in sensory ganglia, but there is no information on the function of these receptors. We used calcium imaging to study this question in isolated mouse trigeminal ganglia and found that satellite glial cells are highly sensitive to ET-1, with threshold at 0.05 nM. Responses displayed strong desensitization at ET-1 concentrations of more than 1 nM. A large component of the response persisted when Ca was deleted from the external medium, consistent with Ca release from internal stores. The use of receptor selective agents showed that the responses were mediated by ETB receptors. We conclude that satellite glial cells display endothelin receptors, which may participate in neuron-glia communications in the trigeminal ganglia.
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Krilov L, Nguyen A, Miyazaki T, Unson CG, Williams R, Lee NH, Ceryak S, Bouscarel B. Dual mode of glucagon receptor internalization: role of PKCα, GRKs and β-arrestins. Exp Cell Res 2011; 317:2981-94. [PMID: 22001118 DOI: 10.1016/j.yexcr.2011.10.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 09/29/2011] [Accepted: 10/01/2011] [Indexed: 10/17/2022]
Abstract
Glucagon levels are elevated in diabetes and some liver diseases. Increased glucagon secretion leads to abnormal stimulation of glucagon receptors (GRs) and consequent elevated glucose production in the liver. Blocking glucagon receptor signaling has been proposed as a potential treatment option for diabetes and other conditions associated with hyperglycemia. Elucidating mechanisms of GR desensitization and downregulation may help identify new drug targets besides GR itself. The present study explores the mechanisms of GR internalization and the role of PKCα, GPCR kinases (GRKs) and β-arrestins therein. We have reported previously that PKCα mediates GR phosphorylation and desensitization. While the PKC agonist, PMA, did not affect GR internalization when tested alone, it increased glucagon-mediated GR internalization by 25-40% in GR-expressing HEK-293 cells (HEK-GR cells). In both primary hepatocytes and HEK-GR cells, glucagon treatment recruited PKCα to the plasma membrane where it colocalized with GR. We also observed that overexpression of GRK2, GRK3, or GRK5 enhanced GR internalization. In addition, we found that GR utilizes both clathrin- and caveolin-mediated endocytosis in HEK-GR cells. Glucagon triggered translocation of both β-arrestin1 and β-arrestin2 from the cytosol to the perimembrane region, and overexpression of β-arrestin1 and β-arrestin2 increased GR internalization. Furthermore, both β-arrestin1 and β-arrestin2 colocalized with GR and with Cav-1, suggesting the possible involvement of these arrestins in GR internalization.
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Affiliation(s)
- Lada Krilov
- Gastroenterology Research Laboratory, Digestive Diseases Center, Department of Biochemistry and Molecular Biology, The George Washington University, Washington, DC, USA
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Abstract
G protein-coupled receptors (GPCRs) represent the largest family of membrane receptors and are responsible for regulating a wide variety of physiological processes. This is accomplished via ligand binding to GPCRs, activating associated heterotrimeric G proteins and intracellular signaling pathways. G protein-coupled receptor kinases (GRKs), in concert with β-arrestins, classically desensitize receptor signal transduction, thus preventing hyperactivation of GPCR second-messenger cascades. As changes in GRK expression have featured prominently in many cardiovascular pathologies, including heart failure, myocardial infarction, hypertension, and cardiac hypertrophy, GRKs have been intensively studied as potential diagnostic or therapeutic targets. Herein, we review our evolving understanding of the role of GRKs in cardiovascular pathophysiology.
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Affiliation(s)
- Stephen L Belmonte
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
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Rapoport RM, Zuccarello M. Endothelin(A)-endothelin(B) receptor cross-talk and endothelin receptor binding. J Pharm Pharmacol 2011; 63:1373-7. [PMID: 21988418 DOI: 10.1111/j.2042-7158.2011.01334.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND OBJECTIVE The magnitude of inhibition of an endothelin (ET)-1 response by selective blockade of the ET(A) or ET(B) receptors can be limited by apparent compensation mediated by the unblocked receptor. While the mechanism underlying this functionally defined interaction, or 'cross-talk', is not clear, binding studies suggest an interaction between the ET receptor subtypes. KEY FINDINGS These binding studies are reviewed and suggest that, in general, they support the hypothesis that ET(A) and ET(B) receptor activation of intracellular signalling pathways influence ET-1 binding to these receptor subtypes. SUMMARY However, the relationship of these binding studies to functional effects and, thus, functional ET(A)-ET(B) receptor cross-talk, remains largely untested.
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Affiliation(s)
- Robert M Rapoport
- Research Service, Veterans Affairs Medical Center, Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0575, USA.
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31
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Fernandez N, Gottardo FL, Alonso MN, Monczor F, Shayo C, Davio C. Roles of phosphorylation-dependent and -independent mechanisms in the regulation of histamine H2 receptor by G protein-coupled receptor kinase 2. J Biol Chem 2011; 286:28697-28706. [PMID: 21705320 DOI: 10.1074/jbc.m111.269613] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
It is widely assumed that G protein-coupled receptor kinase 2 (GRK2)-mediated specific inhibition of G protein-coupled receptors (GPCRs) response involves GRK-mediated receptor phosphorylation followed by β-arrestin binding and subsequent uncoupling from the heterotrimeric G protein. It has recently become evident that GRK2-mediated GPCRs regulation also involves phosphorylation-independent mechanisms. In the present study we investigated whether the histamine H2 receptor (H2R), a Gα(s)-coupled GPCR known to be desensitized by GRK2, needs to be phosphorylated for its desensitization and/or internalization and resensitization. For this purpose we evaluated the effect of the phosphorylating-deficient GRK2K220R mutant on H2R signaling in U937, COS7, and HEK293T cells. We found that although this mutant functioned as dominant negative concerning receptor internalization and resensitization, it desensitized H2R signaling in the same degree as the GRK2 wild type. To identify the domains responsible for the kinase-independent receptor desensitization, we co-transfected the receptor with constructions encoding the GRK2 RGS-homology domain (RH) and the RH or the kinase domain fused to the pleckstrin-homology domain. Results demonstrated that the RH domain of GRK2 was sufficient to desensitize the H2R. Moreover, disruption of RGS functions by the use of GRK2D110A/K220R double mutant, although coimmunoprecipitating with the H2R, reversed GRK2K220R-mediated H2R desensitization. Overall, these results indicate that GRK2 induces desensitization of H2R through a phosphorylation-independent and RGS-dependent mechanism and extends the GRK2 RH domain-mediated regulation of GPCRs beyond Gα(q)-coupled receptors. On the other hand, GRK2 kinase activity proved to be necessary for receptor internalization and the resulting resensitization.
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Affiliation(s)
- Natalia Fernandez
- Laboratorio de Farmacología de Receptores, Cátedra de Química Medicinal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, 1113 Buenos Aires, Argentina,; Consejo Nacional de Investigaciones Científicas y Técnicas, 1033 Buenos Aires, Argentina.
| | - Federico L Gottardo
- Laboratorio de Farmacología de Receptores, Cátedra de Química Medicinal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, 1113 Buenos Aires, Argentina
| | - Maria N Alonso
- Consejo Nacional de Investigaciones Científicas y Técnicas, 1033 Buenos Aires, Argentina; Laboratorio de Farmacología y Patología Molecular, Instituto de Biología y Medicina Experimental, 1426 Buenos Aires, Argentina, and
| | - Federico Monczor
- Laboratorio de Farmacología de Receptores, Cátedra de Química Medicinal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, 1113 Buenos Aires, Argentina,; Consejo Nacional de Investigaciones Científicas y Técnicas, 1033 Buenos Aires, Argentina
| | - Carina Shayo
- Consejo Nacional de Investigaciones Científicas y Técnicas, 1033 Buenos Aires, Argentina; Laboratorio de Farmacología y Patología Molecular, Instituto de Biología y Medicina Experimental, 1426 Buenos Aires, Argentina, and
| | - Carlos Davio
- Laboratorio de Farmacología de Receptores, Cátedra de Química Medicinal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, 1113 Buenos Aires, Argentina,; Consejo Nacional de Investigaciones Científicas y Técnicas, 1033 Buenos Aires, Argentina
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Kittikulsuth W, Pollock JS, Pollock DM. Sex differences in renal medullary endothelin receptor function in angiotensin II hypertensive rats. Hypertension 2011; 58:212-8. [PMID: 21646601 DOI: 10.1161/hypertensionaha.111.172734] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We hypothesized that angiotensin (Ang) II hypertensive rats have impaired natriuresis after renal medullary endothelin (ET) B receptor stimulation that would be more evident in male versus female rats. Acute intramedullary infusion of the ET(B) agonist sarafotoxin 6c in normotensive male rats increased sodium excretion from 0.51±0.11 μmol/min during baseline to 1.64±0.19 μmol/min (P<0.05) after S6c. After 2 weeks of Ang II infusion (260 ng/kg per minute SC), male rats had an attenuated natriuretic response to S6c of 0.62±0.16 μmol/min during baseline versus 0.95±0.07 μmol/min after S6c. In contrast, ET(B)-dependent natriuresis was similar in female hypertensive rats (0.48±0.07 versus 1.5±0.18 μmol/min; P<0.05) compared with normotensive controls (1.05±0.07 versus 2.14±0.24 μmol/min; P<0.05). Because ET(A) receptors also mediate natriuresis in normotensive female rats, we examined ET(A) receptor function in female Ang II hypertensive rats. Intramedullary infusion of ET-1 increased sodium excretion in both hypertensive and normotensive female rats, which was partially blocked by the ET(A) antagonist BQ-123. Maximum ET(B) receptor binding in inner medullary membrane preparations was comparable between vehicle and Ang II hypertensive females; however, maximum ET(B) binding was significantly lower in male hypertensive rats (1952±251 versus 985±176 fmol/mg; P<0.05). These results indicate that renal ET(B) function is impaired in male Ang II hypertension attributed, at least in part, to a reduced number of ET(B) binding sites. Furthermore, renal ET receptor function is preserved in female rats during chronic Ang II infusion, suggesting that renal ET receptor function could serve to limit hypertension in females compared with males.
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Affiliation(s)
- Wararat Kittikulsuth
- Georgia Health Sciences University, 1459 Laney Walker Blvd, Augusta, GA 30912, USA
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33
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De Mey JG, Compeer MG, Lemkens P, Meens MJ. ETA-receptor antagonists or allosteric modulators? Trends Pharmacol Sci 2011; 32:345-51. [DOI: 10.1016/j.tips.2011.02.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 02/27/2011] [Accepted: 02/28/2011] [Indexed: 01/14/2023]
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Lee IH, Song SH, Campbell CR, Kumar S, Cook DI, Dinudom A. Regulation of the epithelial Na+ channel by the RH domain of G protein-coupled receptor kinase, GRK2, and Galphaq/11. J Biol Chem 2011; 286:19259-69. [PMID: 21464134 DOI: 10.1074/jbc.m111.239772] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The G protein-coupled receptor kinase (GRK2) belongs to a family of protein kinases that phosphorylates agonist-activated G protein-coupled receptors, leading to G protein-receptor uncoupling and termination of G protein signaling. GRK2 also contains a regulator of G protein signaling homology (RH) domain, which selectively interacts with α-subunits of the Gq/11 family that are released during G protein-coupled receptor activation. We have previously reported that kinase activity of GRK2 up-regulates activity of the epithelial sodium channel (ENaC) in a Na(+) absorptive epithelium by blocking Nedd4-2-dependent inhibition of ENaC. In the present study, we report that GRK2 also regulates ENaC by a mechanism that does not depend on its kinase activity. We show that a wild-type GRK2 (wtGRK2) and a kinase-dead GRK2 mutant ((K220R)GRK2), but not a GRK2 mutant that lacks the C-terminal RH domain (ΔRH-GRK2) or a GRK2 mutant that cannot interact with Gαq/11/14 ((D110A)GRK2), increase activity of ENaC. GRK2 up-regulates the basal activity of the channel as a consequence of its RH domain binding the α-subunits of Gq/11. We further found that expression of constitutively active Gαq/11 mutants significantly inhibits activity of ENaC. Conversely, co-expression of siRNA against Gαq/11 increases ENaC activity. The effect of Gαq on ENaC activity is not due to change in ENaC membrane expression and is independent of Nedd4-2. These findings reveal a novel mechanism by which GRK2 and Gq/11 α-subunits regulate the activity ENaC.
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Affiliation(s)
- Il-Ha Lee
- Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, NSW 2006, Australia
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35
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Breton B, Lagacé M, Bouvier M. Combining resonance energy transfer methods reveals a complex between the α 2A‐adrenergic receptor, Gα i1β 1γ 2, and GRK2. FASEB J 2010. [DOI: 10.1096/fj.10.164061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Billy Breton
- Department of BiochemistryInstitute for Research in Immunology and CancerGroupe de Recherche Universitaire sur le MédicamentUniversité de Montréal Montréal Québec Canada
| | - Monique Lagacé
- Department of BiochemistryInstitute for Research in Immunology and CancerGroupe de Recherche Universitaire sur le MédicamentUniversité de Montréal Montréal Québec Canada
| | - Michel Bouvier
- Department of BiochemistryInstitute for Research in Immunology and CancerGroupe de Recherche Universitaire sur le MédicamentUniversité de Montréal Montréal Québec Canada
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36
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Kikkawa Y, Kameda K, Hirano M, Sasaki T, Hirano K. Impaired feedback regulation of the receptor activity and the myofilament Ca2+ sensitivity contributes to increased vascular reactiveness after subarachnoid hemorrhage. J Cereb Blood Flow Metab 2010; 30:1637-50. [PMID: 20234381 PMCID: PMC2949258 DOI: 10.1038/jcbfm.2010.35] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cerebral vasospasm determines the prognosis of subarachnoid hemorrhage (SAH). The increased vascular reactiveness has an important role in the development of cerebral vasospasm. This study analyzed the roles of the receptor-mediated signaling and the myofilament Ca(2+) sensitivity in the increased vascular reactiveness in SAH, using the basilar artery of a rabbit SAH model. Endothelin-1, thrombin, and phenylephrine induced transient increases in [Ca(2+)](i), myosin light chain phosphorylation, and contraction in the controls. All these responses were not only enhanced but also became sustained in SAH. In the sequential stimulation of thrombin receptor or alpha(1)-adrenoceptor, the second response was substantially attenuated in the controls, whereas it was maintained in SAH. The thrombin-induced contraction in SAH irreversibly persisted even after terminating the thrombin stimulation. This contraction was completely reversed by trypsin and a Galpha(q) inhibitor YM254890, thus suggesting the sustained receptor activity during the sustained contraction. YM254890 also inhibited the endothelin-1- and phenylephrine-induced sustained contraction. Furthermore, the GTPgammaS-induced transient contraction in the control alpha-toxin-permeabilized strips was converted to a sustained contraction in SAH. The results provide the first evidence that the feedback inactivation of the receptor activity and the myofilament Ca(2+) sensitivity was impaired in SAH, thus contributing to the increased vascular reactiveness.
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Affiliation(s)
- Yuichiro Kikkawa
- Division of Molecular Cardiology, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan
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37
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Breton B, Lagacé M, Bouvier M. Combining resonance energy transfer methods reveals a complex between the alpha2A-adrenergic receptor, Galphai1beta1gamma2, and GRK2. FASEB J 2010; 24:4733-43. [PMID: 20696855 DOI: 10.1096/fj.10-164061] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Traditionally, G-protein-coupled receptor (GPCR) interactions with their G proteins and regulatory proteins, GPCR kinases (GRKs) and arrestins, are described as sequential events involving rapid assemblies/disassemblies. To directly monitor the dynamics of these interactions in living cells, we combined two spectrally resolved bioluminescence and one fluorescence resonance energy transfer (RET) methods. The RET combination analysis revealed that stimulation of the α(2A)-adrenergic receptor (α(2A)AR) leads to the recruitment of GRK2 at a receptor still associated with the Gα(i1)β(1)γ(2) complex. The interaction kinetics of GRKs with Gγ(2) (2.8 ± 0.4 s) and α(2A)AR (5.2 ± 0.5 s) were similar to that of the receptor-promoted change in RET between Gα(i1) and Gγ(2) (5.2 ± 1.2 s), and persisted until the translocation of βarrestin2 to the receptor, indicating that GRK2 remains associated to the receptor/G-protein complex for longer periods than anticipated. Moreover, GRK2 or a kinase-deficient GRK2 mutant, but not GRK5, potentiated the receptor-promoted changes in RET between Gα(i1) and Gγ(2) and abrogated the α(2A)AR-stimulated calcium response, suggesting that the recruitment of GRK2 to the complex contributes to the structural rearrangement and functional regulation of the signaling unit, independently of the kinase activity. RET combination analysis revealed unanticipated dynamics in GPCR signaling and will be applicable to many biological systems.
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Affiliation(s)
- Billy Breton
- Department of Biochemistry, Institute for Research in Immunology and Cancer, and Groupe de Recherche Universitaire sur le Médicament, Université de Montréal, Montréal, Québec, Canada
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The GRK2 Overexpression Is a Primary Hallmark of Mitochondrial Lesions during Early Alzheimer Disease. Cardiovasc Psychiatry Neurol 2010; 2009:327360. [PMID: 20204079 PMCID: PMC2832107 DOI: 10.1155/2009/327360] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 11/16/2009] [Indexed: 12/25/2022] Open
Abstract
Increasing evidence points to vascular damage as an early contributor to the development of two leading causes of age-associated dementia, namely Alzheimer disease (AD) and AD-like pathology such as stroke. This review focuses on the role of G protein-coupled receptor kinases (GRKs) as they relate to dementia and how the cardio and cerebrovasculature is involved in AD pathogenesis. The exploration of GRKs in AD pathogenesis may help bridge gaps in our understanding of the heart-brain connection in relation to neurovisceral damage and vascular complications of AD. The a priori basis for this inquiry stems from the fact that kinases of this family regulate numerous receptor functions in the brain, myocardium and elsewhere. The aim of this review is to discuss the finding of GRK2 overexpression in the context of early AD pathogenesis. Also, we consider the consequences for this overexpression as a loss of G-protein coupled receptor (GPCR) regulation, as well as suggest a potential role for GPCRs and GRKs in a unifying theory of AD pathogenesis through the cerebrovasculature. Finally, we synthesize this newer information in an attempt to put it into context with GRKs as regulators of cellular function, which makes these proteins potential diagnostic and therapeutic targets for future pharmacological intervention.
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39
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Brinks HL, Eckhart AD. Regulation of GPCR signaling in hypertension. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1268-75. [PMID: 20060896 DOI: 10.1016/j.bbadis.2010.01.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/18/2009] [Accepted: 01/04/2010] [Indexed: 01/08/2023]
Abstract
Hypertension represents a complex, multifactorial disease and contributes to the major causes of morbidity and mortality in industrialized countries: ischemic and hypertensive heart disease, stroke, peripheral atherosclerosis and renal failure. Current pharmacological therapy of essential hypertension focuses on the regulation of vascular resistance by inhibition of hormones such as catecholamines and angiotensin II, blocking them from receptor activation. Interaction of G-protein coupled receptor kinases (GRKs) and regulator of G-protein signaling (RGS) proteins with activated G-protein coupled receptors (GPCRs) effect the phosphorylation state of the receptor leading to desensitization and can profoundly impair signaling. Defects in GPCR regulation via these modulators have severe consequences affecting GPCR-stimulated biological responses in pathological situations such as hypertension, since they fine-tune and balance the major transmitters of vessel constriction versus dilatation, thus representing valuable new targets for anti-hypertensive therapeutic strategies. Elevated levels of GRKs are associated with human hypertensive disease and are relevant modulators of blood pressure in animal models of hypertension. This implies therapeutic perspective in a disease that has a prevalence of 65million in the United States while being directly correlated with occurrence of major adverse cardiac and vascular events. Therefore, therapeutic approaches using the inhibition of GRKs to regulate GPCRs are intriguing novel targets for treatment of hypertension and heart failure.
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Affiliation(s)
- Henriette L Brinks
- Center for Translational Medicine, Thomas Jefferson University, Philadelphia, PA, USA
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40
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Gao YJ. Desensitization of vascular endothelin receptors by G protein-coupled receptor kinase 2. Cardiovasc Res 2009; 85:405-6. [PMID: 20007311 DOI: 10.1093/cvr/cvp392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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Kinome-wide RNAi studies in human multiple myeloma identify vulnerable kinase targets, including a lymphoid-restricted kinase, GRK6. Blood 2009; 115:1594-604. [PMID: 19996089 DOI: 10.1182/blood-2009-09-243980] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A paucity of validated kinase targets in human multiple myeloma has delayed clinical deployment of kinase inhibitors in treatment strategies. We therefore conducted a kinome-wide small interfering RNA (siRNA) lethality study in myeloma tumor lines bearing common t(4;14), t(14;16), and t(11;14) translocations to identify critically vulnerable kinases in myeloma tumor cells without regard to preconceived mechanistic notions. Fifteen kinases were repeatedly vulnerable in myeloma cells, including AKT1, AK3L1, AURKA, AURKB, CDC2L1, CDK5R2, FES, FLT4, GAK, GRK6, HK1, PKN1, PLK1, SMG1, and TNK2. Whereas several kinases (PLK1, HK1) were equally vulnerable in epithelial cells, others and particularly G protein-coupled receptor kinase, GRK6, appeared selectively vulnerable in myeloma. GRK6 inhibition was lethal to 6 of 7 myeloma tumor lines but was tolerated in 7 of 7 human cell lines. GRK6 exhibits lymphoid-restricted expression, and from coimmunoprecipitation studies we demonstrate that expression in myeloma cells is regulated via direct association with the heat shock protein 90 (HSP90) chaperone. GRK6 silencing causes suppression of signal transducer and activator of transcription 3 (STAT3) phosphorylation associated with reduction in MCL1 levels and phosphorylation, illustrating a potent mechanism for the cytotoxicity of GRK6 inhibition in multiple myeloma (MM) tumor cells. As mice that lack GRK6 are healthy, inhibition of GRK6 represents a uniquely targeted novel therapeutic strategy in human multiple myeloma.
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Morris GE, Nelson CP, Standen NB, Challiss RAJ, Willets JM. Endothelin signalling in arterial smooth muscle is tightly regulated by G protein-coupled receptor kinase 2. Cardiovasc Res 2009; 85:424-33. [PMID: 19748906 PMCID: PMC2802200 DOI: 10.1093/cvr/cvp310] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
AIMS Prolonged endothelin (ET) receptor signalling causes vasoconstriction and can lead to hypertension, vascular smooth muscle hypertrophy, and hyperplasia. Usually, G protein-coupled receptor signalling is negatively regulated by G protein-coupled receptor kinases (GRKs), preventing prolonged or inappropriate signalling. This study investigated whether GRKs regulate ET receptor contractile signalling in adult Wistar rat mesenteric arterial smooth muscle cells (MSMCs). METHODS AND RESULTS ET-1-stimulated phospholipase C (PLC) activity and changes in [Ca2+]i were assessed using confocal microscopy in rat MSMCs transfected with the pleckstrin-homology domain of PLCdelta1 (eGFP-PH) and loaded with Fura-Red. ET-1 applications (30 s) stimulated transient concentration-dependent eGFP-PH translocations from plasma membrane to cytoplasm and graded [Ca2+]i increases. ET-1-mediated PLC signalling was blocked by the type A endothelin receptor (ET(A)R) antagonist, BQ123. To characterize ET(A)R desensitization, cells were stimulated with a maximally effective concentration of ET-1 (50 nM, 30 s) followed by a variable washout period and a second identical application of ET-1. This brief exposure to ET-1 markedly decreased ET(A)R responsiveness to re-challenge, and reversal was incomplete even after increasing the time period between agonist challenges to 60 min. To assess GRK involvement in ET(A)R desensitization, MSMCs were co-transfected with eGFP-PH and catalytically inactive (D110A,K220R)GRK2, (D110A,K220R)GRK3, (K215R)GRK5, or (K215R)GRK6 constructs. (D110A,K220R)GRK2 expression significantly attenuated ET(A)R desensitization, whereas other constructs were ineffective. Small interfering RNA-targeted GRK2 depletion equally attenuated ET(A)R desensitization. Finally, immunocyotchemical data showed that ET(A)R activation recruited endogenous GRK2 from cytoplasm to membrane. CONCLUSION These studies identify GRK2 as a key regulator of ET(A)R responsiveness in resistance arteries, highlighting the potential importance of this GRK isoenzyme in regulating vasoconstrictor signalling pathways implicated in vascular disease.
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Affiliation(s)
- Gavin E Morris
- Reproductive Sciences Section, Department of Cancer Studies and Molecular Medicine, Clinical Sciences Building, Leicester Royal Infirmary, Leicester LE2 7LX, UK
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Shrestha S, Gracias NG, Mujenda F, Khodorova A, Vasko MR, Strichartz GR. Local antinociception induced by endothelin-1 in the hairy skin of the rat's back. THE JOURNAL OF PAIN 2009; 10:702-14. [PMID: 19559389 PMCID: PMC2720057 DOI: 10.1016/j.jpain.2008.12.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 12/09/2008] [Accepted: 12/17/2008] [Indexed: 10/20/2022]
Abstract
UNLABELLED Subcutaneous injection of endothelin-1 (ET-1) into the glabrous skin of the rat's hind paw is known to produce impulses in nociceptors and acute nocifensive behavioral responses, such as hind paw flinching, and to sensitize the skin to mechanical and thermal stimulation. In this report, we show that in contrast to the responses in glabrous skin, ET-1 injected subcutaneously into rat hairy skin causes transient antinociception. Concentrations of 1 to 50 microM ET-1 (in 0.05 mL) depress the local nocifensive response to noxious tactile probing at the injection site with von Frey filaments for 30 to 180 minutes; distant injections have no effect at this site, showing that the response is local. Selective inhibition of ET(A) but not of ET(B) receptors inhibits this antinociception, as does coinjection with nimodipine (40 muM), a blocker of L-type Ca(2+) channels. Local subcutaneous injection of epinephrine (45 microM) also causes antinociception through alpha-1 adrenoreceptors, but such receptors are not involved in the ET-1-induced effect. Both epinephrine and ET-1, at antinociceptive concentrations, reduce blood flow in the skin; the effect from ET-1 is largely prevented by subcutaneous nimodipine. These data suggest that ET-1-induced antinociception in the hairy skin of the rat involves cutaneous vasoconstriction, presumably through neural ischemia, resulting in conduction block. PERSPECTIVE The pain-inducing effects of ET-1 have been well documented in glabrous skin of the rat, a frequently used test site. The opposite behavioral effect, antinociception, occurs from ET-1 in hairy skin and is correlated with a reduction in blood flow. Vasoactive effects are important in assessing mechanisms of peripherally acting agents.
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Affiliation(s)
- Saurav Shrestha
- Pain Research Center, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Cohn HI, Xi Y, Pesant S, Harris DM, Hyslop T, Falkner B, Eckhart AD. G protein-coupled receptor kinase 2 expression and activity are associated with blood pressure in black Americans. Hypertension 2009; 54:71-6. [PMID: 19487588 DOI: 10.1161/hypertensionaha.108.125955] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypertension occurs with higher prevalence and morbidity in black Americans compared with other groups. Alterations in the signal transduction pathways of 7-transmembrane spanning receptors are found in hypertensive patients. G protein-coupled receptor kinases (GRKs) play an important role in regulating this receptor signaling. The 2 most abundantly expressed GRKs in the cardiovascular system are GRK2 and GRK5, and each has unique substrates. Understanding changes in expression may give us insight into activated receptors in the pathophysiological progression of hypertension. In heart failure and white hypertensives, increased GRK2 expression arises because of neurohormonal stimulation of particular receptors. GRK2 subsequently desensitizes specific receptors, including beta-adrenergic receptors. In blood pressure control, beta-adrenergic receptor desensitization could lead to increased blood pressure. GRK2 and GRK5 mRNA were evaluated in lymphocytes of black Americans via quantitative real-time PCR. GRK2 mRNA expression directly correlated with systolic blood pressure and norepinephrine levels. GRK2 was elevated >30% among those with systolic blood pressure > or =130 mm Hg. No significant correlation between GRK5 mRNA expression and blood pressure or catecholamines was observed. Diabetic status, age, sex, and body mass index were also compared with GRK2 expression using univariate and multivariate analyses. GRK2 protein expression was elevated 2-fold in subjects with higher blood pressure, and GRK activity was increased >40%. Our data suggest that GRK2, but not GRK5, is correlated with increasing blood pressure in black Americans. Understanding the receptors stimulated by increased neurohormonal activation may give insight into the pathophysiology of hypertension in this at-risk population.
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Affiliation(s)
- Heather I Cohn
- Center for Translational Medicine, Thomas Jefferson Hospital, Philadelphia, PA, USA
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Khodorova A, Montmayeur JP, Strichartz G. Endothelin receptors and pain. THE JOURNAL OF PAIN 2009; 10:4-28. [PMID: 19111868 DOI: 10.1016/j.jpain.2008.09.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 09/08/2008] [Accepted: 09/30/2008] [Indexed: 12/11/2022]
Abstract
UNLABELLED The endogenous endothelin (ET) peptides participate in a remarkable variety of pain-relatedprocesses. Pain that is elevated by inflammation, by skin incision, by cancer, during a Sickle Cell Disease crisis and by treatments that mimic neuropathic and inflammatory pain and are all reduced by local administration of antagonists of endothelin receptors. Many effects of endogenously released endothelin are simulated by acute, local subcutaneous administration of endothelin, which at very high concentrations causes pain and at lower concentrations sensitizes the nocifensive reactions to mechanical, thermal and chemical stimuli. PERSPECTIVE In this paper we review the biochemistry, second messenger pathways and hetero-receptor coupling that are activated by ET receptors, the cellular physiological responses to ET receptor activation, and the contribution to pain of such mechanisms occurring in the periphery and the CNS. Our goal is to frame the subject of endothelin and pain for a broad readership, and to present the generally accepted as well as the disputed concepts, including important unanswered questions.
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Affiliation(s)
- Alla Khodorova
- Department of Anesthesiology, Perioperative and Pain Medicine, Pain Research Center, Brigham & Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115-6110, USA
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Obrenovich ME, Morales LA, Cobb CJ, Shenk JC, Méndez GM, Fischbach K, Smith MA, Qasimov EK, Perry G, Aliev G. Insights into cerebrovascular complications and Alzheimer disease through the selective loss of GRK2 regulation. J Cell Mol Med 2008; 13:853-65. [PMID: 19292735 PMCID: PMC2919803 DOI: 10.1111/j.1582-4934.2008.00512.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Alzheimer disease (AD) and stroke are two leading causes of age-associated dementia. Increasing evidence points to vascular damage as an early contributor to the development of AD and AD-like pathology. In this review, we discuss the role of G protein-coupled receptor kinase 2 (GRK2) as it relates to individuals affected by AD and how the cardiovasculature plays a role in AD pathogenesis. The possible involvement of GRKs in AD pathogenesis is an interesting notion, which may help bridge the gap in our understanding of the heart–brain connection in relation to neurovisceral damage and vascular complications in AD, since kinases of this family are known to regulate numerous receptor functions both in the brain, myocardium, and elsewhere. The aim of this review is to discuss our findings of overexpression of GRK2 in the context of the early pathogenesis of AD, because increased levels of GRK2 immunoreactivity were found in vulnerable neurons of AD patients as well as in a two-vessel occlusion (2-VO) mammalian model of ischaemia. Also, we consider the consequences for this overexpression as a loss of G-protein coupled receptor (GPCR) regulation, as well as suggest a potential role for GPCRs and GRKs in a unifying theory of AD pathogenesis, particularly in the context of cerebrovascular disease. We synthesize this newer information and attempt to put it into context with GRKs as regulators of diverse physiological cellular functions that could be appropriate targets for future pharmacological intervention.
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Affiliation(s)
- Mark E Obrenovich
- Department of Pathology, Case Western Reserve University, Cleveland, OH, USA
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Miedlich SU, Abou-Samra AB. Eliminating phosphorylation sites of the parathyroid hormone receptor type 1 differentially affects stimulation of phospholipase C and receptor internalization. Am J Physiol Endocrinol Metab 2008; 295:E665-71. [PMID: 18577695 PMCID: PMC2536737 DOI: 10.1152/ajpendo.00036.2008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The parathyroid hormone (PTH)/PTH-related peptide (PTHrP) receptor (PTH1R) belongs to family B of seven-transmembrane-spanning receptors and is activated by PTH and PTHrP. Upon PTH stimulation, the rat PTH1R becomes phosphorylated at seven serine residues. Elimination of all PTH1R phosphorylation sites results in prolonged cAMP accumulation and impaired internalization in stably transfected LLC-PK1 cells. The present study explores the role of individual PTH1R phosphorylation sites in PTH1R signaling through phospholipase C, agonist-dependent receptor internalization, and regulation by G protein-coupled receptor kinases. By means of transiently transfected COS-7 cells, we demonstrate that the phosphorylation-deficient (pd) PTH1R confers dramatically enhanced coupling to G(q/11) proteins upon PTH stimulation predominantly caused by elimination of Ser(491/492/493), Ser(501), or Ser(504). Reportedly, impaired internalization of the pd PTH1R, however, is not dependent on a specific phosphorylation site. In addition, we show that G protein-coupled receptor kinase 2 interferes with pd PTH1R signaling to G(q/11) proteins at least partially by direct binding to G(q/11) proteins.
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Affiliation(s)
- Susanne U Miedlich
- Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, USA.
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Neerhof MG, Jilling T, Synowiec S, Khan S, Thaete LG. Altered endothelin receptor binding in response to nitric oxide synthase inhibition in the pregnant rat. Reprod Sci 2008; 15:366-73. [PMID: 18325929 DOI: 10.1177/1933719107312627] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The authors evaluate the expression of endothelin-1 (ET-1) and its receptors in the uterus and placenta during maternal nitric oxide synthase (NOS) inhibition. Timed-pregnant rats received L-NAME (2.5 mg/kg/h) or saline from day 14 to 21 of gestation. Uterine and placental tissues collected on day 21 were assayed for preproET-1, ET( A), and ET(B) mRNA expression; localization and expression of ET-1 and receptor proteins; and receptor activity. NOS inhibition did not affect preproET-1 mRNA expression in the placenta or uterus. ET(A) expression decreased in the uterine free wall, but no other changes in receptor mRNA expression were observed in the uterus or placenta. ET-1 and receptor proteins were unchanged. Placental ET(A) and ET(B) receptor binding decreased. Uterine ET(A) receptor binding decreased in the placental bed. ET-1, a prominent mediator during NOS inhibition, is not of uterine or placental origin. Reduced receptor binding activity is the primary means by which these tissues regulate their response to ET-1 in the setting of NOS inhibition.
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Affiliation(s)
- Mark G Neerhof
- Department of Obstetrics, Evanston Northwestern Healthcare, Evanston, Illinois, USA
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Abstract
Cardiac hypertrophy is a known risk factor for heart disease, and at the cellular level is caused by a complex interaction of signal transduction pathways. The IP3-calcineurin pathway plays an important role in stimulating the transcription factor NFAT which binds to DNA cooperatively with other hypertrophic transcription factors. Using available kinetic data, we construct a mathematical model of the IP3 signal production system after stimulation by a hypertrophic alpha-adrenergic agonist (endothelin-1) in the mouse atrial cardiac myocyte. We use a global sensitivity analysis to identify key controlling parameters with respect to the resultant IP3 transient, including the phosphorylation of cell-membrane receptors, the ligand strength and binding kinetics to precoupled (with G(alpha)GDP) receptor, and the kinetics associated with precoupling the receptors. We show that the kinetics associated with the receptor system contribute to the behavior of the system to a great extent, with precoupled receptors driving the response to extracellular ligand. Finally, by reparameterizing for a second hypertrophic alpha-adrenergic agonist, angiotensin-II, we show that differences in key receptor kinetic and membrane density parameters are sufficient to explain different observed IP3 transients in essentially the same pathway.
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Affiliation(s)
- Michael Cooling
- Auckland Bioengineering Institute, Department of Engineering Science, University of Auckland, New Zealand.
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Hamdan FF, Rochdi MD, Breton B, Fessart D, Michaud DE, Charest PG, Laporte SA, Bouvier M. Unraveling G protein-coupled receptor endocytosis pathways using real-time monitoring of agonist-promoted interaction between beta-arrestins and AP-2. J Biol Chem 2007; 282:29089-100. [PMID: 17675294 DOI: 10.1074/jbc.m700577200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The most widely studied pathway underlying agonist-promoted internalization of G protein-coupled receptors (GPCRs) involves beta-arrestin and clathrin-coated pits. However, both beta-arrestin- and clathrin-independent processes have also been reported. Classically, the endocytic routes are characterized using pharmacological inhibitors and various dominant negative mutants, resulting sometimes in conflicting results and interpretational difficulties. Here, taking advantage of the fact that beta-arrestin binding to the beta2 subunit of the clathrin adaptor AP-2 (beta2-adaptin) is needed for the beta-arrestin-mediated targeting of GPCRs to clathrin-coated pits, we developed a bioluminescence resonance energy transfer-based approach directly assessing the molecular steps involved in the endocytosis of GPCRs in living cells. For 10 of the 12 receptors tested, including some that were previously suggested to internalize via clathrin-independent pathways, agonist stimulation promoted beta-arrestin 1 and 2 interaction with beta2-adaptin, indicating a beta-arrestin- and clathrin-dependent endocytic process. Detailed analyses of beta-arrestin interactions with both the receptor and beta2-adaptin also allowed us to demonstrate that recruitment of beta-arrestins to the receptor and the ensuing conformational changes are the leading events preceding AP-2 engagement and subsequent clathrin-mediated endocytosis. Among the receptors tested, only the endothelin A and B receptors failed to promote interaction between beta-arrestins and beta2-adaptin. However, both receptors recruited beta-arrestins upon agonist stimulation, suggesting a beta-arrestin-dependent but clathrin-independent route of internalization for these two receptors. In addition to providing a new tool to dissect the molecular events involved in GPCR endocytosis, the bioluminescence resonance energy transfer-based beta-arrestin/beta2-adaptin interaction assay represents a novel biosensor to assess receptor activation.
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Affiliation(s)
- Fadi F Hamdan
- Department of Biochemistry, Groupe de Recherche Universitaire sur le Médicament, Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec, Canada
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