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He L, Du J, Chen Y, Liu C, Zhou M, Adhikari S, Rubin DT, Pekow J, Li YC. Renin-angiotensin system promotes colonic inflammation by inducing T H17 activation via JAK2/STAT pathway. Am J Physiol Gastrointest Liver Physiol 2019; 316:G774-G784. [PMID: 30995068 PMCID: PMC6620584 DOI: 10.1152/ajpgi.00053.2019] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Previous studies suggest that the renin-angiotensin system (RAS) is a pathogenic factor for colitis. The goal of this study was to elucidate the molecular mechanism whereby angiotensin II (ANG II) promotes colonic inflammation. We found that renin was highly induced in colonic biopsies from patients with ulcerative colitis or Crohn's disease, and colonic renin and ANG II levels were markedly increased in a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model, indicating that the colonic RAS is activated in colitis. Renin transgenic (RenTg) mice exhibited increased phosphorylation in Janus kinase-2 (JAK2) and signal transducer and activator of transcription1/3 (STAT1/3) within colonic mucosa at baseline and following TNBS induction, suggesting that ANG II promotes colonic inflammation via the JAK2/STAT1/3 pathway. Treatment with pan-JAK inhibitor tofacitinib blocked JAK2 and STAT1/3 phosphorylation, attenuated T helper (TH)1 and TH17 responses, alleviated colitis, and prevented death of RenTg mice in TNBS model. ANG II stimulated JAK2/STAT1/3 phosphorylation in both Jurkat T lymphocytes and HCT116 epithelial cells. In vitro polarization assays demonstrated that ANG II directly promoted TH17 polarization, but not TH1 polarization, via JAK2/STAT1/3. ANG II stimulation of transforming growth factor-β1 (TGFβ1), IL-6, myosin light chain kinase, and p53 upregulated modulator of apoptosis in HCT116 cells was also mediated by JAK2/STAT1/3. These observations suggest that ANG II promotes TH17 polarization directly as well as indirectly by inducing production of TH17-polarizing cytokines (e.g., TGFβ1 and IL-6) from colonic epithelial cells, both via the JAK2/STAT pathway. Therefore, colonic RAS promotes colonic inflammation, at least in part, by stimulating TH17 activation. NEW & NOTEWORTHY This study demonstrates that the local renin-angiotensin system in the colon is activated in colitis development, which promotes mucosal T helper cell activation through the JAK2/STAT pathway. These observations provide molecular evidence that the renin-angiotensin system is a pathogenic factor for the development of inflammatory bowel diseases.
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Affiliation(s)
- Lei He
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois
| | - Jie Du
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois,2Institute of Biomedical Research, Shanxi Medical University, Taiyuan, Shanxi, China
| | - Yinyin Chen
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois,3Department of Nephrology, Hunan Provincial People’s Hospital, Hunan Normal University, Changsha, Hunan, China
| | - Chunyan Liu
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois,4Department of Pathology, Hunan University of Chinese Medicine, Changsha, Hunan, China
| | - Min Zhou
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois,5Division of Gastroenterology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Sarbani Adhikari
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois
| | - David T. Rubin
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois
| | - Joel Pekow
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois
| | - Yan Chun Li
- 1Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois
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Xu Z, Zou C, Yu W, Xu S, Huang L, Khan Z, Wang J, Liang G, Wang Y. Inhibition of STAT3 activation mediated by toll-like receptor 4 attenuates angiotensin II-induced renal fibrosis and dysfunction. Br J Pharmacol 2019; 176:2627-2641. [PMID: 30958891 DOI: 10.1111/bph.14686] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 03/10/2019] [Accepted: 03/16/2019] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE Hypertension adversely affects the kidney and is the second leading cause of kidney failure. Overproduction of angiotensin II greatly contributes to the progression of hypertensive kidney disease. Angiotensin II has recently been shown to activate STAT3 in cardiovascular cells. However, the underlying mechanisms of STAT3 activation by angiotensin II and downstream functional consequences in the kidneys are not fully understood. EXPERIMENTAL APPROACH C57BL/6 mice were treated with angiotensin II by subcutaneous infusion for 1 month to develop nephropathy. Mice were treated with either adeno-associated virus expressing STAT3 shRNA or STAT3 inhibitor, S3I-201. Human archival kidney samples from five patients with hypertension and five individuals without hypertension were also examined. In vitro, STAT3 was blocked using siRNA or STAT3 inhibitor S3I-201 in the renal proximal tubular cell line, NRK52E, after exposure to angiotensin II. KEY RESULTS Angiotensin II activated STAT3 in kidney epithelial cells through engaging toll-like receptor 4 (TLR4) and JAK2, which was independent of IL-6/gp130 and angiotensin AT1 receptors. Angiotensin II-mediated STAT3 activation increased fibrotic proteins and resulted in renal dysfunction. Both STAT3 inhibition by the low MW compound S3I-201 and TLR4 deficiency normalized renal fibrosis and dysfunction caused by Ang II in mice, without affecting hypertension. CONCLUSIONS AND IMPLICATIONS Our study reveals a novel mechanism of STAT3 activation, induced by angiotensin II, in kidney tissues and highlights a translational significance of a STAT3 inhibitor as potential therapeutic agent for hypertensive kidney disease.
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Affiliation(s)
- Zheng Xu
- Chemical Biology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Chunpeng Zou
- Department of Ultrasonography, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Weihui Yu
- Department of Endocrinology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Sujing Xu
- Chemical Biology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Lan Huang
- Chemical Biology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zia Khan
- Chemical Biology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jingying Wang
- Chemical Biology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Guang Liang
- Chemical Biology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yi Wang
- Chemical Biology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
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Singh KD, Unal H, Desnoyer R, Karnik SS. Mechanism of Hormone Peptide Activation of a GPCR: Angiotensin II Activated State of AT 1R Initiated by van der Waals Attraction. J Chem Inf Model 2019; 59:373-385. [PMID: 30608150 DOI: 10.1021/acs.jcim.8b00583] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We present a succession of structural changes involved in hormone peptide activation of a prototypical GPCR. Microsecond molecular dynamics simulation generated conformational ensembles reveal propagation of structural changes through key "microswitches" within human AT1R bound to native hormone. The endocrine octa-peptide angiotensin II (AngII) activates AT1R signaling in our bodies which maintains physiological blood pressure, electrolyte balance, and cardiovascular homeostasis. Excessive AT1R activation is associated with pathogenesis of hypertension and cardiovascular diseases which are treated by sartan drugs. The mechanism of AT1R inhibition by sartans has been elucidated by 2.8 Å X-ray structures, mutagenesis, and computational analyses. Yet, the mechanism of AT1R activation by AngII is unclear. The current study delineates an activation scheme initiated by AngII binding. A van der Waals "grasp" interaction between Phe8AngII with Ile2887.39 in AT1R induced mechanical strain pulling Tyr2927.43 and breakage of critical interhelical H-bonds, first between Tyr2927.43 and Val1083.32 and second between Asn1113.35 and Asn2957.46. Subsequently changes are observed in conserved microswitches DRYTM3, Yx7K(R)TM5, CWxPTM6, and NPxxYTM7 in AT1R. Activating the microswitches in the intracellular region of AT1R may trigger formation of the G-protein binding pocket as well as exposure of helix-8 to cytoplasm. Thus, the active-like conformation of AT1R is initiated by the van der Waals interaction of Phe8AngII with Ile2887.39, followed by systematic reorganization of critical interhelical H-bonds and activation of microswitches.
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Affiliation(s)
- Khuraijam Dhanachandra Singh
- Department of Molecular Cardiology, Lerner Research Institute , Cleveland Clinic Foundation , Cleveland , Ohio 44195 , United States
| | - Hamiyet Unal
- Department of Molecular Cardiology, Lerner Research Institute , Cleveland Clinic Foundation , Cleveland , Ohio 44195 , United States
| | - Russell Desnoyer
- Department of Molecular Cardiology, Lerner Research Institute , Cleveland Clinic Foundation , Cleveland , Ohio 44195 , United States
| | - Sadashiva S Karnik
- Department of Molecular Cardiology, Lerner Research Institute , Cleveland Clinic Foundation , Cleveland , Ohio 44195 , United States
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Itcho K, Oki K, Kobuke K, Ohno H, Yoneda M, Hattori N. Angiotensin 1-7 suppresses angiotensin II mediated aldosterone production via JAK/STAT signaling inhibition. J Steroid Biochem Mol Biol 2019; 185:137-141. [PMID: 30125658 DOI: 10.1016/j.jsbmb.2018.08.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 08/03/2018] [Accepted: 08/12/2018] [Indexed: 01/27/2023]
Abstract
Angiotensin 1-7 (Ang 1-7), which is a protein cleaved from angiotensin II (A-II), binds to the MAS receptor. Ang 1-7 has been demonstrated to exert protective effects against A-II-mediated cardiac, atherosclerotic, and renal damages. The aims of our study were to demonstrate the inhibitory role of Ang 1-7 in A-II-mediated aldosterone production by interacting with the MAS receptor in human adrenocortical carcinoma (HAC15) cells, and clarify the intracellular signaling mechanisms underlying the inhibition of aldosterone production by Ang 1-7. Ang 1-7 significantly suppressed A-II-stimulated aldosterone production, and partially abrogated A-II-induced upregulation of CYP11B2 expression. Treatment with a selective Ang 1-7 antagonist abrogated Ang 1-7-mediated inhibition of aldosterone production in HAC15 cells. Incubation of A-II-treated HAC15 cells with conditioned medium containing Ang 1-7 was demonstrated to suppress A-II-mediated aldosterone production and CYP11B2 expression. Proteomic analysis showed that Ang 1-7 predominantly inhibited the phosphorylation of JAK-STAT proteins in A-II stimulated HAC15 cells. Treatment of HAC15 cells with a STAT3 inhibitor partially but significantly repressed A-II-mediated aldosterone production by 63.2%. Similarly, treatment with a STAT5 inhibitor significantly abrogated A-II-stimulated aldosterone production in HAC15 cells by 60.7%. In conclusion, we demonstrated that Ang 1-7 negatively regulates A-II-mediated aldosterone production, and the observed inhibition of aldosterone production was associated with JAK/STAT signaling in human adrenal cells. Therefore, activation of Ang 1-7 or stimulation of the MAS receptor, which inhibits aldosterone production, is a promising therapeutic approach for the prevention of cardiovascular events that can directly affect the target organs.
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Affiliation(s)
- Kiyotaka Itcho
- Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan
| | - Kenji Oki
- Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan.
| | - Kazuhiro Kobuke
- Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan
| | - Haruya Ohno
- Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan
| | - Masayasu Yoneda
- Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan
| | - Noboru Hattori
- Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan
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Karnik SS, Unal H, Kemp JR, Tirupula KC, Eguchi S, Vanderheyden PML, Thomas WG. International Union of Basic and Clinical Pharmacology. XCIX. Angiotensin Receptors: Interpreters of Pathophysiological Angiotensinergic Stimuli [corrected]. Pharmacol Rev 2015; 67:754-819. [PMID: 26315714 PMCID: PMC4630565 DOI: 10.1124/pr.114.010454] [Citation(s) in RCA: 207] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The renin angiotensin system (RAS) produced hormone peptides regulate many vital body functions. Dysfunctional signaling by receptors for RAS peptides leads to pathologic states. Nearly half of humanity today would likely benefit from modern drugs targeting these receptors. The receptors for RAS peptides consist of three G-protein-coupled receptors—the angiotensin II type 1 receptor (AT1 receptor), the angiotensin II type 2 receptor (AT2 receptor), the MAS receptor—and a type II trans-membrane zinc protein—the candidate angiotensin IV receptor (AngIV binding site). The prorenin receptor is a relatively new contender for consideration, but is not included here because the role of prorenin receptor as an independent endocrine mediator is presently unclear. The full spectrum of biologic characteristics of these receptors is still evolving, but there is evidence establishing unique roles of each receptor in cardiovascular, hemodynamic, neurologic, renal, and endothelial functions, as well as in cell proliferation, survival, matrix-cell interaction, and inflammation. Therapeutic agents targeted to these receptors are either in active use in clinical intervention of major common diseases or under evaluation for repurposing in many other disorders. Broad-spectrum influence these receptors produce in complex pathophysiological context in our body highlights their role as precise interpreters of distinctive angiotensinergic peptide cues. This review article summarizes findings published in the last 15 years on the structure, pharmacology, signaling, physiology, and disease states related to angiotensin receptors. We also discuss the challenges the pharmacologist presently faces in formally accepting newer members as established angiotensin receptors and emphasize necessary future developments.
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Affiliation(s)
- Sadashiva S Karnik
- Department of Molecular Cardiology, Lerner Research Institute of Cleveland Clinic, Cleveland, Ohio (S.S.K., H.U., J.R.K., K.C.T.); Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania (S.E.); Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium (P.M.L.V.); and Department of General Physiology, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia (W.G.T.)
| | - Hamiyet Unal
- Department of Molecular Cardiology, Lerner Research Institute of Cleveland Clinic, Cleveland, Ohio (S.S.K., H.U., J.R.K., K.C.T.); Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania (S.E.); Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium (P.M.L.V.); and Department of General Physiology, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia (W.G.T.)
| | - Jacqueline R Kemp
- Department of Molecular Cardiology, Lerner Research Institute of Cleveland Clinic, Cleveland, Ohio (S.S.K., H.U., J.R.K., K.C.T.); Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania (S.E.); Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium (P.M.L.V.); and Department of General Physiology, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia (W.G.T.)
| | - Kalyan C Tirupula
- Department of Molecular Cardiology, Lerner Research Institute of Cleveland Clinic, Cleveland, Ohio (S.S.K., H.U., J.R.K., K.C.T.); Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania (S.E.); Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium (P.M.L.V.); and Department of General Physiology, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia (W.G.T.)
| | - Satoru Eguchi
- Department of Molecular Cardiology, Lerner Research Institute of Cleveland Clinic, Cleveland, Ohio (S.S.K., H.U., J.R.K., K.C.T.); Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania (S.E.); Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium (P.M.L.V.); and Department of General Physiology, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia (W.G.T.)
| | - Patrick M L Vanderheyden
- Department of Molecular Cardiology, Lerner Research Institute of Cleveland Clinic, Cleveland, Ohio (S.S.K., H.U., J.R.K., K.C.T.); Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania (S.E.); Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium (P.M.L.V.); and Department of General Physiology, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia (W.G.T.)
| | - Walter G Thomas
- Department of Molecular Cardiology, Lerner Research Institute of Cleveland Clinic, Cleveland, Ohio (S.S.K., H.U., J.R.K., K.C.T.); Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania (S.E.); Faculty of Sciences and Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium (P.M.L.V.); and Department of General Physiology, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia (W.G.T.)
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Balakumar P, Jagadeesh G. Structural determinants for binding, activation, and functional selectivity of the angiotensin AT1 receptor. J Mol Endocrinol 2014; 53:R71-92. [PMID: 25013233 DOI: 10.1530/jme-14-0125] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The renin-angiotensin system (RAS) plays an important role in the pathophysiology of cardiovascular disorders. Pharmacologic interventions targeting the RAS cascade have led to the discovery of renin inhibitors, angiotensin-converting enzyme inhibitors, and AT(1) receptor blockers (ARBs) to treat hypertension and some cardiovascular and renal disorders. Mutagenesis and modeling studies have revealed that differential functional outcomes are the results of multiple active states conformed by the AT(1) receptor upon interaction with angiotensin II (Ang II). The binding of agonist is dependent on both extracellular and intramembrane regions of the receptor molecule, and as a consequence occupies more extensive area of the receptor than a non-peptide antagonist. Both agonist and antagonist bind to the same intramembrane regions to interfere with each other's binding to exhibit competitive, surmountable interaction. The nature of interactions with the amino acids in the receptor is different for each of the ARBs given the small differences in the molecular structure between drugs. AT(1) receptors attain different conformation states after binding various Ang II analogues, resulting in variable responses through activation of multiple signaling pathways. These include both classical and non-classical pathways mediated through growth factor receptor transactivations, and provide cross-communication between downstream signaling molecules. The structural requirements for AT(1) receptors to activate extracellular signal-regulated kinases 1 and 2 through G proteins, or G protein-independently through β-arrestin, are different. We review the structural and functional characteristics of Ang II and its analogs and antagonists, and their interaction with amino acid residues in the AT(1) receptor.
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Affiliation(s)
- Pitchai Balakumar
- Pharmacology UnitFaculty of Pharmacy, AIMST University, Semeling, 08100 Bedong, Kedah Darul Aman, MalaysiaDivision of Cardiovascular and Renal ProductsCenter for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland 20993, USA
| | - Gowraganahalli Jagadeesh
- Pharmacology UnitFaculty of Pharmacy, AIMST University, Semeling, 08100 Bedong, Kedah Darul Aman, MalaysiaDivision of Cardiovascular and Renal ProductsCenter for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland 20993, USA
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Balakumar P, Jagadeesh G. A century old renin-angiotensin system still grows with endless possibilities: AT1 receptor signaling cascades in cardiovascular physiopathology. Cell Signal 2014; 26:2147-60. [PMID: 25007996 DOI: 10.1016/j.cellsig.2014.06.011] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 06/27/2014] [Indexed: 12/25/2022]
Abstract
Ang II, the primary effector pleiotropic hormone of the renin-angiotensin system (RAS) cascade, mediates physiological control of blood pressure and electrolyte balance through its action on vascular tone, aldosterone secretion, renal sodium absorption, water intake, sympathetic activity and vasopressin release. It affects the function of most of the organs far beyond blood pressure control including heart, blood vessels, kidney and brain, thus, causing both beneficial and deleterious effects. However, the protective axis of the RAS composed of ACE2, Ang (1-7), alamandine, and Mas and MargD receptors might oppose some harmful effects of Ang II and might promote beneficial cardiovascular effects. Newly identified RAS family peptides, Ang A and angioprotectin, further extend the complexities in understanding the cardiovascular physiopathology of RAS. Most of the diverse actions of Ang II are mediated by AT1 receptors, which couple to classical Gq/11 protein and activate multiple downstream signals, including PKC, ERK1/2, Raf, tyrosine kinases, receptor tyrosine kinases (EGFR, PDGF, insulin receptor), nuclear factor κB and reactive oxygen species (ROS). Receptor activation via G12/13 stimulates Rho-kinase, which causes vascular contraction and hypertrophy. The AT1 receptor activation also stimulates G protein-independent signaling pathways such as β-arrestin-mediated MAPK activation and Src-JAK/STAT. AT1 receptor-mediated activation of NADPH oxidase releases ROS, resulting in the activation of pro-inflammatory transcription factors and stimulation of small G proteins such as Ras, Rac and RhoA. The components of the RAS and the major Ang II-induced signaling cascades of AT1 receptors are reviewed.
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Affiliation(s)
- Pitchai Balakumar
- Pharmacology Unit, Faculty of Pharmacy, AIMST University, Semeling, 08100 Bedong, Kedah Darul Aman, Malaysia.
| | - Gowraganahalli Jagadeesh
- Division of Cardiovascular and Renal Products, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD 20993, USA.
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Satou R, Gonzalez-Villalobos RA. JAK-STAT and the renin-angiotensin system: The role of the JAK-STAT pathway in blood pressure and intrarenal renin-angiotensin system regulation. JAKSTAT 2014; 1:250-6. [PMID: 24058780 PMCID: PMC3670281 DOI: 10.4161/jkst.22729] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The renin-angiotensin system (RAS) plays important roles in blood pressure control and tissue disease. An inappropriate local angiotensin II elevation in the kidneys leads to the development of hypertension, tissue damage and chronic injury. Studies have demonstrated that the JAK-STAT pathway mediates angiotensin II-triggered gene transcription. The JAK-STAT pathway in turn, acting as an amplifying system, contributes to further intrarenal RAS activation. These observations prompt the suggestion that the JAK-STAT pathway may be of importance in elucidating the mechanisms RAS-associated tissue injury. Accordingly, this review provides a brief overview of the interactions between the JAK-STAT pathway and the RAS, specifically the RAS expressed in the kidneys.
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Affiliation(s)
- Ryousuke Satou
- Department of Physiology and Hypertension and Renal Center of Excellence; Tulane University Health Sciences Center; New Orleans, LA USA
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Kim YC, Mungunsukh O, McCart EA, Roehrich PJ, Yee DK, Day RM. Mechanism of erythropoietin regulation by angiotensin II. Mol Pharmacol 2014; 85:898-908. [PMID: 24695083 DOI: 10.1124/mol.113.091157] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Erythropoietin (EPO) is the primary regulator of red blood cell development. Although hypoxic regulation of EPO has been extensively studied, the mechanism(s) for basal regulation of EPO are not well understood. In vivo studies in healthy human volunteers and animal models indicated that angiotensin II (Ang II) and angiotensin converting enzyme inhibitors regulated blood EPO levels. In the current study, we found that Ang II induced EPO expression in situ in murine kidney slices and in 786-O kidney cells in culture as determined by reverse transcription polymerase chain reaction. We further investigated the signaling mechanism of Ang II regulation of EPO in 786-O cells. Pharmacological inhibitors of Ang II type 1 receptor (AT1R) and extracellular signal-regulated kinase 1/2 (ERK1/2) suppressed Ang II transcriptional activation of EPO. Inhibitors of AT2R or Src homology 2 domain-containing tyrosine phosphatase had no effect. Coimmunoprecipiation experiments demonstrated that p21Ras was constitutively bound to the AT1R; this association was increased by Ang II but was reduced by the AT1R inhibitor telmisartan. Transmembrane domain (TM) 2 of AT1R is important for G protein-dependent ERK1/2 activation, and mutant D74E in TM2 blocked Ang II activation of ERK1/2. Ang II signaling induced the nuclear translocation of the Egr-1 transcription factor, and overexpression of dominant-negative Egr-1 blocked EPO promoter activation by Ang II. These data identify a novel pathway for basal regulation of EPO via AT1R-mediated Egr-1 activation by p21Ras-mitogen-activated protein kinase/ERK kinase-ERK1/2. Our current data suggest that Ang II, in addition to regulating blood volume and pressure, may be a master regulator of erythropoiesis.
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Affiliation(s)
- Yong-Chul Kim
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland (Y.-C.K., O.M., E.A.M., P.J.R., R.M.D.); and Department of Animal Biology, University of Pennsylvania, Philadelphia, Pennsylvania (D.K.Y.)
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Liu J, Yosten GLC, Ji H, Zhang D, Zheng W, Speth RC, Samson WK, Sandberg K. Selective inhibition of angiotensin receptor signaling through Erk1/2 pathway by a novel peptide. Am J Physiol Regul Integr Comp Physiol 2014; 306:R619-26. [PMID: 24523339 DOI: 10.1152/ajpregu.00562.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A seven-amino acid peptide (PEP7) is encoded within a short open reading frame within exon 2 (E2) in the 5'-leader sequence (5'LS) upstream of the rat ANG 1a-receptor (rAT1aR) mRNA. A chemically synthesized PEP7 markedly inhibited ANG II-induced Erk1/2 activation in cell culture by 62% compared with a scrambled PEP7 (sPEP7) [pErk1/2/Erk1/2 (AU): ANG II, 1.000 ± 0.0, ANG II+PEP7, 0.3812 ± 0.086, ANG II+sPEP7, 1.069 ± 0.18; n = 3]. Under these same conditions, PEP7 had no effect on ANG II-stimulated inositol-trisphosphate production. PEP7 also had no effect on epidermal growth factor- and phorbol methyl ester-induced Erk1/2 activation, suggesting PEP7 selectively inhibits AT1aR-mediated Erk1/2 signaling. PEP7 intracerebroventricularly inhibited ANG II-induced saline intake but had no effect on water intake in male and female rats, indicating PEP7 also selectively inhibits the ANG II-Erk1/2 pathway in vivo since saline drinking is Erk1/2-mediated, while water drinking is not. PEP7 inhibition of ANG II-induced saline ingestion was rapidly reversed by a subsequent intracerebroventricular injection of an oxytocin antagonist, suggesting when PEP7 blocks ANG II-stimulated Erk1/2 activation, animals no longer ingest saline to balance the continued water intake, due to the release of oxytocin and its subsequent inhibitory effects on saline drinking. PEP7 also attenuated ANG II-induced increases in arterial pressure by 35% compared with sPEP7 at the same dose. Thus, we have identified a novel peptide encoded within the rAT1aR E2 that selectively inhibits Erk1/2 activation, resulting in physiological consequences for sodium ingestion and arterial pressure that may have implications for treating sodium-sensitive diseases like hypertension and chronic kidney disease.
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Affiliation(s)
- Jun Liu
- Division of Nephrology and Hypertension, Department of Medicine, Georgetown University, Washington, D.C.
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Casare F, Milan D, Fernandez R. Stimulation of calcium-sensing receptor increases biochemical H⁺-ATPase activity in mouse cortex and outer medullary regions. Can J Physiol Pharmacol 2013; 92:181-8. [PMID: 24593782 DOI: 10.1139/cjpp-2013-0256] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The aim of this project was to investigate the interaction between the calcium-sensing receptor (CaSR) and proton extrusion by the V-ATPase and gastric-like isoform of the H(+)/K(+)-ATPase in the mouse nephron. Biochemical activity of H(+)- ATPases was analysed using a partially purified membrane fraction of mouse cortex and outer medullary region. The V-ATPase activity (sensitive to 10(-7) mol·L(-1) bafilomycin) from the cortical and outer medullary region was significantly stimulated by increasing the [Formula: see text] (outside Ca(2+)), in a dose-dependent pattern. Gastric H(+)/K(+)-ATPase activity (sensitive to 10(-5) mol·L(-1) Schering 28080) was also sensitive to changes in [Formula: see text] levels. A significant increase in V-ATPase activity was also observed when CaSR was stimulated with agonists such as 300 μmol·L(-1) Gd(3+) and 200 μmol·L(-1) neomycin, both in the cortex and outer medulla. The cortical and outer medullary gastric H(+)/K(+)-ATPase activity was also stimulated by Gd(3+) and neomycin. Finally, cortical V-ATPase activity was significantly stimulated by 10(-9) mol·L(-1) angiotensin II, and the stimulation of CaSR in the presence of angiotensin significantly enhanced this effect, suggesting that an interaction in the intracellular signaling pathways is involved. In summary, CaSR stimulation enhances the biochemical activity of V-ATPase and gastric H(+)/K(+)-ATPase in both the cortical and outer medullary region of mouse kidney.
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Affiliation(s)
- Fernando Casare
- Departamento de Fisiologia, Setor de Ciências Biológicas, Universidade Federal do Paraná (UFPR), Centro Politécnico s/n., PO Box 19031, Jardim das Américas, Curitiba, Paraná, CEP 81531-990, Brasil
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12
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Rebois RV, Hébert TE. Protein Complexes Involved in Heptahelical Receptor-Mediated Signal Transduction. ACTA ACUST UNITED AC 2011. [DOI: 10.3109/10606820308243] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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13
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Smith NJ, Chan HW, Qian H, Bourne AM, Hannan KM, Warner FJ, Ritchie RH, Pearson RB, Hannan RD, Thomas WG. Determination of the Exact Molecular Requirements for Type 1 Angiotensin Receptor Epidermal Growth Factor Receptor Transactivation and Cardiomyocyte Hypertrophy. Hypertension 2011; 57:973-80. [DOI: 10.1161/hypertensionaha.110.166710] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Nicola J. Smith
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Hsiu-Wen Chan
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Hongwei Qian
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Allison M. Bourne
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Katherine M. Hannan
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Fiona J. Warner
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Rebecca H. Ritchie
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Richard B. Pearson
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Ross D. Hannan
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
| | - Walter G. Thomas
- From the Baker IDI Heart and Diabetes Institute (N.J.S., H.-W.C., H.Q., A.M.B., R.H.R., W.G.T.), Prahran, Victoria, Australia; School of Biomedical Sciences (H.-W.C., A.M.B., W.G.T.), University of Queensland, St Lucia, Queensland, Australia; Growth Control and Differentiation Program (K.M.H., R.B.P., R.D.H.), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Centenary Institute (F.J.W.), Camperdown, New South Wales, Australia
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Makhanova NA, Crowley SD, Griffiths RC, Coffman TM. Gene expression profiles linked to AT1 angiotensin receptors in the kidney. Physiol Genomics 2010; 42A:211-8. [PMID: 20807774 DOI: 10.1152/physiolgenomics.00063.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
To characterize gene expression networks linked to AT(1) angiotensin receptors in the kidney, we carried out genome-wide transcriptional analysis of RNA from kidneys of wild-type (WT) and AT(1A) receptor-deficient mice (KOs) at baseline and after 2 days of angiotensin II infusion (1,000 ng·kg(-1)·min(-1)). At baseline, 405 genes were differentially expressed (>1.5×) between WT and KO kidneys. Of these, >80% were upregulated in the KO group including genes involved in inflammation, oxidative stress, and cell proliferation. After 2 days of angiotensin II infusion in WT mice, expression of ≈805 genes was altered (18% upregulated, 82% repressed). Genes in metabolism and ion transport pathways were upregulated while there was attenuated expression of genes protective against oxidative stress including glutathione synthetase and mitochondrial superoxide dismutase 2. Angiotensin II infusion had little effect on blood pressure in KOs. Nonetheless, expression of >250 genes was altered in kidneys from KO mice during angiotensin II infusion; 14% were upregulated, while 86% were repressed including genes involved in immune responses, angiogenesis, and glutathione metabolism. Between WT and KO kidneys during angiotensin II infusion, 728 genes were differentially expressed; 10% were increased and 90% were decreased in the WT group. Differentially regulated pathways included those involved in ion transport, immune responses, metabolism, apoptosis, cell proliferation, and oxidative stress. This genome-wide assessment should facilitate identification of critical distal pathways linked to blood pressure regulation.
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Affiliation(s)
- Natalia A Makhanova
- Department of Medicine, Division of Nephrology, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina, USA
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Long-term regulation of vacuolar H(+)-ATPase by angiotensin II in proximal tubule cells. Pflugers Arch 2009; 458:969-79. [PMID: 19396617 DOI: 10.1007/s00424-009-0668-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 03/03/2009] [Accepted: 03/27/2009] [Indexed: 10/20/2022]
Abstract
Long-term effects of angiotensin II (Ang II) on vacuolar H(+)-ATPase were studied in a SV40-transformed cell line derived from rat proximal tubules (IRPTC). Using pH(i) measurements with the fluorescent dye BCECF, the hormone increased Na(+)-independent pH recovery rate from an NH(4)Cl pulse from 0.066 +/- 0.014 pH U/min (n = 7) to 0.14 +/- 0.021 pH U/min (n = 13; p < 0.05) in 10 h Ang II (10(-9) M)-treated cells. The increased activity of H(+)-ATPase did not involve changes in mRNA or protein abundance of the B2 subunit but increased cell surface expression of the V-ATPase. Inhibition of tyrosine kinase by genistein blocked Ang II-dependent stimulation of H(+)-ATPase. Inhibition of phosphatidylinositol-3-kinase (PI3K) by wortmannin and of p38 mitogen-activated protein kinase (MAPK) by SB 203580 also blocked this effect. Thus, long-term exposure of IRPTC cells to Ang II causes upregulation of H(+)-ATPase activity due, at least in part, to increased B2 cell surface expression. This regulatory pathway is dependent on mechanisms involving tyrosine kinase, p38 MAPK, and PI3K activation.
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Aplin M, Bonde MM, Hansen JL. Molecular determinants of angiotensin II type 1 receptor functional selectivity. J Mol Cell Cardiol 2009; 46:15-24. [DOI: 10.1016/j.yjmcc.2008.09.123] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 09/09/2008] [Accepted: 09/18/2008] [Indexed: 01/14/2023]
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17
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Aplin M, Christensen GL, Hansen JL. Pharmacologic Perspectives of Functional Selectivity by the Angiotensin II Type 1 Receptor. Trends Cardiovasc Med 2008; 18:305-12. [DOI: 10.1016/j.tcm.2009.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 01/19/2009] [Accepted: 01/27/2009] [Indexed: 12/14/2022]
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18
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Garcia RAP, Afeche SC, Scialfa JH, do Amaral FG, dos Santos SHJ, Lima FB, Young ME, Cipolla-Neto J. Insulin modulates norepinephrine-mediated melatonin synthesis in cultured rat pineal gland. Life Sci 2008; 82:108-14. [DOI: 10.1016/j.lfs.2007.10.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 09/17/2007] [Accepted: 10/22/2007] [Indexed: 10/22/2022]
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Acosta E, Mendoza V, Castro E, Cruzblanca H. Modulation of a delayed-rectifier K+ current by angiotensin II in rat sympathetic neurons. J Neurophysiol 2007; 98:79-85. [PMID: 17493917 DOI: 10.1152/jn.01103.2006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is well known that angiotensin II (Angio II) mimics most of the muscarinic-mediated excitatory actions of acetylcholine on superior cervical ganglion neurons. For instance, in addition to depolarization and stimulation of norepinephrine release, muscarinic agonists and Angio II modulate the M-type K(+) current and the N-type Ca(2+) current. We recently found that muscarinic receptors modulate the delayed rectifier current I(KV) as well. Therefore a whole cell patch-clamp experiment was carried out in rat cultured sympathetic neurons to assess whether Angio II modulates I(KV). We found that Angio II increased I(KV) by about 30% with a time constant of approximately 30 s. In comparison, inhibition of M-current was faster (tau approximately 8 s) and stronger ( approximately 61%). Modulation of I(KV) was disrupted by the AT(1) receptor-antagonist losartan but not by the AT(2)-antagonist PD123319. I(KV) enhancement was reduced by the G-protein inhibitor GDP-beta-S, whereas current modulation remained unaltered after cell treatment with pertussis toxin. The peptidergic modulation of I(KV) was severely disrupted when internal ATP was replaced by its nonhydrolyzable analogue AMP-PNP. Angio II enhanced I(KV) and further reduced the stimulatory action of a muscarinic agonist on I(KV). Likewise, the muscarinc agonist enhanced I(KV) and occluded the effect of Angio II on I(KV). We have also found that the protein kinase C activator PMA enhanced I(KV), thereby mimicking and further attenuating the action of Angio II on I(KV). These results suggest that AT(1) receptors by coupling to pertussis toxin-insensitive G proteins, stimulate an ATP-dependent and PKC-mediated pathway to modulate I(KV).
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Affiliation(s)
- Eduardo Acosta
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av 25 de Julio 965, Col Villas San Sebastián, Colima, Colima, Mexico
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20
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Oliveira L, Costa-Neto CM, Nakaie CR, Schreier S, Shimuta SI, Paiva ACM. The Angiotensin II AT1 Receptor Structure-Activity Correlations in the Light of Rhodopsin Structure. Physiol Rev 2007; 87:565-92. [PMID: 17429042 DOI: 10.1152/physrev.00040.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The most prevalent physiological effects of ANG II, the main product of the renin-angiotensin system, are mediated by the AT1 receptor, a rhodopsin-like AGPCR. Numerous studies of the cardiovascular effects of synthetic peptide analogs allowed a detailed mapping of ANG II's structural requirements for receptor binding and activation, which were complemented by site-directed mutagenesis studies on the AT1 receptor to investigate the role of its structure in ligand binding, signal transduction, phosphorylation, binding to arrestins, internalization, desensitization, tachyphylaxis, and other properties. The knowledge of the high-resolution structure of rhodopsin allowed homology modeling of the AT1 receptor. The models thus built and mutagenesis data indicate that physiological (agonist binding) or constitutive (mutated receptor) activation may involve different degrees of expansion of the receptor's central cavity. Residues in ANG II structure seem to control these conformational changes and to dictate the type of cytosolic event elicited during the activation. 1) Agonist aromatic residues (Phe8 and Tyr4) favor the coupling to G protein, and 2) absence of these residues can favor a mechanism leading directly to receptor internalization via phosphorylation by specific kinases of the receptor's COOH-terminal Ser and Thr residues, arrestin binding, and clathrin-dependent coated-pit vesicles. On the other hand, the NH2-terminal residues of the agonists ANG II and [Sar1]-ANG II were found to bind by two distinct modes to the AT1 receptor extracellular site flanked by the COOH-terminal segments of the EC-3 loop and the NH2-terminal domain. Since the [Sar1]-ligand is the most potent molecule to trigger tachyphylaxis in AT1 receptors, it was suggested that its corresponding binding mode might be associated with this special condition of receptors.
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Affiliation(s)
- Laerte Oliveira
- Department of Biophysics, Escola Paulista de Medicina, Federal University of São Paulo, Brazil.
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21
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Patten CS, Daniels D, Suzuki A, Fluharty SJ, Yee DK. Structural and signaling requirements of the human melanocortin 4 receptor for MAP kinase activation. ACTA ACUST UNITED AC 2007; 142:111-22. [PMID: 17376547 DOI: 10.1016/j.regpep.2007.02.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Accepted: 02/08/2007] [Indexed: 01/04/2023]
Abstract
In addition to its well known stimulation of cAMP production, the human melanocortin type 4 (hMC4) receptor recently has been shown to mediate p44/42 MAPK activation. This finding opens new questions about the structural and signaling mechanisms that connect the receptor to this alternate cell signaling pathway. Point mutants in the hMC4 receptor that have been associated with obesity were constructed and transfected into HEK 293 cells. Functional analyses then were done to determine if these mutations would similarly impact cAMP formation and p44/42 MAPK signaling. Whereas a D90N mutation in the second transmembrane domain and a D298A mutation in the seventh transmembrane domain impaired both cAMP formation and p44/42 MAPK activation, a more conservative D298N mutation retained cAMP formation but abolished p44/42 MAPK activation. The D298N mutation identified, for the first time, differential structural requirements of the hMC4 receptor for activation of the cAMP and p44/42 MAPK pathways. Furthermore, functional characterizations of a series of chimeric receptors combining the hMC4 receptor and the hMC3 subtype, a receptor that does not couple to p44/42 MAPK activation despite stimulating adenylyl cyclase, indicate that the hMC4 cytoplasmic tail is a necessary structural element for p44/42 MAPK signaling. Subsequent investigation of the signaling requirements for p44/42 MAPK activation demonstrated that the adenylyl cyclase inhibitor 2', 5'-dideoxyadenosine blocked agonist-induced p44/42 MAPK activation, but the PKA inhibitor Rp cAMPS did not. Taken together, these data indicate that cAMP is required, but not sufficient for p44/42 MAPK activation and suggest structural elements required for hMC4 receptor signaling.
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MESH Headings
- Adenylyl Cyclase Inhibitors
- Adenylyl Cyclases/metabolism
- Amino Acid Substitution
- Base Sequence
- Cell Line
- Cyclic AMP/metabolism
- DNA Primers/genetics
- Dideoxyadenosine/analogs & derivatives
- Dideoxyadenosine/pharmacology
- Humans
- In Vitro Techniques
- MAP Kinase Signaling System
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3/metabolism
- Mutagenesis, Site-Directed
- Obesity/genetics
- Obesity/metabolism
- Receptor, Melanocortin, Type 3/chemistry
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/chemistry
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
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Affiliation(s)
- Caroline S Patten
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce St. 220E, Philadelphia, PA 19104, USA.
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Godeny MD, Sayeski PP. ERK1/2 regulates ANG II-dependent cell proliferation via cytoplasmic activation of RSK2 and nuclear activation of elk1. Am J Physiol Cell Physiol 2006; 291:C1308-17. [PMID: 16723511 DOI: 10.1152/ajpcell.00618.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In a concurrently submitted article, we show that ANG II-induced ERK1/2 activation is mediated by both c-Src/Yes/Fyn and heterotrimeric G protein/PKCζ-dependent signaling. Furthermore, we show that heterotrimeric G protein/PKCζ-activated ERK1/2 is destined for the nucleus while ERK1/2 activated by c-Src/Yes/Fyn-dependent signaling remains in the cytoplasm. Interestingly, both mechanisms of activation are required for maximum ANG II-induced cell proliferation. In this study, we sought to determine the mechanisms by which ERK1/2 facilitate cell proliferation via these distinct nuclear and cytoplasmic events, using cells that were lacking either c-Src/Yes/Fyn or heterotrimeric G protein/PKCζ-dependent ERK1/2 activation. A loss of c-Src/Yes/Fyn blocked ANG II-dependent RSK2 activation, RSK2 nuclear translocation, serum-response factor (SRF) phosphorylation, a portion of c-fos transcriptional activity and c-Fos phosphorylation. Blocking ANG II-induced heterotrimeric G protein/PKCζ activity resulted in a loss of ERK1/2 nuclear translocation, elk1 phosphorylation, and the remaining portion of c-fos transcriptional activity not dependent on c-Src/Yes/Fyn. Inhibition of RSK with the potent and selective inhibitor, SL0101, attenuated ANG II-induced cell proliferation, and, in combination with a PKCζ pseudosubstrate, completely attenuated cell proliferation. Thus we conclude that ERK1/2 mediate ANG II-dependent cell proliferation via distinct cytoplasmic and nuclear signaling events, which are in turn governed by c-Src/Yes/Fyn and heterotrimeric G protein/PKCζ-dependent signaling, respectively.
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Affiliation(s)
- Michael D Godeny
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida 32610, USA
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Godeny MD, Sayeski PP. ANG II-induced cell proliferation is dually mediated by c-Src/Yes/Fyn-regulated ERK1/2 activation in the cytoplasm and PKCζ-controlled ERK1/2 activity within the nucleus. Am J Physiol Cell Physiol 2006; 291:C1297-307. [PMID: 16723512 DOI: 10.1152/ajpcell.00617.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High-affinity binding of angiotensin II (ANG II) to the ANG II type 1 receptor (AT1R) results in the activation of ERK1/2 mitogen-activated protein kinases (MAPK). However, the precise mechanism of ANG II-induced ERK1/2 activation has not been fully characterized. Here, we investigated the signaling events leading to ANG II-induced ERK1/2 activation using a c-Src/Yes/Fyn tyrosine kinase-deficient mouse embryonic fibroblast (MEF) cell line stably transfected with the AT1R (SYF/AT1). ERK1/2 activation was reduced by ∼50% within these cells compared with wild-type controls (WT/AT1). The remaining ∼50% of intracellular ERK1/2 activation was dependent upon heterotrimeric G protein and protein kinase C zeta (PKCζ) activation. Therefore, ANG II-induced ERK1/2 activation occurs via two independent mechanisms. We next investigated whether a loss of either c-Src/Yes/Fyn or PKCζ signaling affected ERK1/2 nuclear translocation and cell proliferation in response to ANG II. ANG II-induced cell proliferation was markedly reduced in SYF/AT1cells compared with WT/AT1cells ( P < 0.01), but interestingly, ERK2 nuclear translocation was normal. ANG II-induced nuclear translocation of ERK2 was blocked via pretreatment of WT/AT1cells with a PKCζ pseudosubstrate. ANG II-induced cell proliferation was significantly reduced in PKCζ pseudosubstrate-treated WT/AT1cells ( P < 0.01) and was completely blocked in SYF/AT1cells treated with this same compound. Thus ANG II-induced cell proliferation appears to be regulated by both ERK1/2-driven nuclear and cytoplasmic events. In response to ANG II, the ability of ERK1/2 to remain within the cytoplasm or translocate into the nucleus is controlled by c-Src/Yes/Fyn or heterotrimeric G protein/PKCζ signaling, respectively.
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Affiliation(s)
- Michael D Godeny
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida 32610, USA
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24
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Oro C, Qian H, Thomas WG. Type 1 angiotensin receptor pharmacology: signaling beyond G proteins. Pharmacol Ther 2006; 113:210-26. [PMID: 17125841 PMCID: PMC7112676 DOI: 10.1016/j.pharmthera.2006.10.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 10/03/2006] [Indexed: 02/07/2023]
Abstract
Drugs that inhibit the production of angiotensin II (AngII) or its access to the type 1 angiotensin receptor (AT1R) are prescribed to alleviate high blood pressure and its cardiovascular complications. Accordingly, much research has focused on the molecular pharmacology of AT1R activation and signaling. An emerging theme is that the AT1R generates G protein dependent as well as independent signals and that these transduction systems separately contribute to AT1R biology in health and disease. Regulatory molecules termed arrestins are central to this process as is the capacity of AT1R to crosstalk with other receptor systems, such as the widely studied transactivation of growth factor receptors. AT1R function can also be modulated by polymorphisms in the AGTR gene, which may significantly alter receptor expression and function; a capacity of the receptor to dimerize/oligomerize with altered pharmacology; and by the cellular environment in which the receptor resides. Together, these aspects of the AT1R “flavour” the response to angiotensin; they may also contribute to disease, determine the efficacy of current drugs and offer a unique opportunity to develop new therapeutics that antagonize only selective facets of AT1R function.
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Affiliation(s)
- Cristina Oro
- Baker Heart Research Institute, Melbourne, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Hongwei Qian
- Baker Heart Research Institute, Melbourne, Australia
| | - Walter G. Thomas
- Baker Heart Research Institute, Melbourne, Australia
- Corresponding author. Molecular Endocrinology Laboratory, Baker Heart Research Institute, P.O. Box 6492, St. Kilda Road Central, Melbourne 8008, Australia. Tel.: +61 3 8532 1224; fax: +61 3 8532 1100.
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25
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Zhai P, Galeotti J, Liu J, Holle E, Yu X, Wagner T, Sadoshima J. An Angiotensin II Type 1 Receptor Mutant Lacking Epidermal Growth Factor Receptor Transactivation Does Not Induce Angiotensin II–Mediated Cardiac Hypertrophy. Circ Res 2006; 99:528-36. [PMID: 16902180 DOI: 10.1161/01.res.0000240147.49390.61] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have shown previously that tyrosine 319 in a conserved YIPP motif in the C terminus of angiotensin II (Ang II) type 1 receptors (AT
1
Rs) is essential for transactivation of epidermal growth factor receptor (EGFR) in vitro. We hypothesized that the signaling mechanism mediated through the specific amino acid sequence in the G protein–coupled receptor plays an important role in mediating cardiac hypertrophy in vivo. Transgenic mice with cardiac-specific overexpression of wild-type AT
1
R (Tg-WT) and an AT
1
R with a mutation in the YIPP motif (Tg-Y319F) were studied. Tg-Y319F mice developed no significant cardiac hypertrophy, in contrast to the significant development of hypertrophy in Tg-WT mice. Expression of fetal-type genes, such as atrial natriuretic factor, was also significantly lower in Tg-Y319F than in Tg-WT mice. Infusion of Ang II caused an enhancement of hypertrophy in Tg-WT mice but failed to induce hypertrophy in Tg-Y319F mice. Left ventricular myocardium in Tg-Y319F mice developed significantly less apoptosis and fibrosis than that in Tg-WT mice. EGFR phosphorylation was significantly inhibited in Tg-Y319F mice, confirming that EGFR was not activated in Tg-Y319F mouse hearts. In contrast, activation/phosphorylation of protein kinase C, STAT3, extracellular signal-regulated kinase, and Akt and translocation of Gαq/11 to the cytosolic fraction were maintained in Tg-Y319F hearts. Furthermore, a genetic cross between Tg-WT and transgenic mice with cardiac-specific overexpression of dominant negative EGFR mimicked the phenotype of Tg-Y319F mice. In conclusion, overexpression of AT
1
-Y319F in cardiac myocytes diminished EGFR transactivation and inhibited a pathological form of cardiac hypertrophy. The YIPP motif in the AT
1
R plays an important role in mediating cardiac hypertrophy in vivo.
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Affiliation(s)
- Peiyong Zhai
- Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine & Dentistry of New Jersey, New Jersey Medical School, Newark 07103, USA
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26
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Yee DK, Suzuki A, Luo L, Fluharty SJ. Identification of Structural Determinants for G Protein-Independent Activation of Mitogen-Activated Protein Kinases in the Seventh Transmembrane Domain of the Angiotensin II Type 1 Receptor. Mol Endocrinol 2006; 20:1924-34. [PMID: 16556732 DOI: 10.1210/me.2006-0018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Although the intrareceptor mechanisms whereby the angiotensin II (AngII) type 1 receptor activates phospholipase C (PLC) have been extensively investigated, analogous studies of signaling through mitogen-activated protein kinases (MAPK) have been lacking. We investigated MAPK activation and traditional G(q)/PLC signaling in transfected cells using AngII and the signaling selective agonist [Sar(1),Ile(4),Ile(8)] AngII (SII). SII stimulated MAPK without inositol trisphosphate (IP(3)) production and thereby stabilizes an activated receptor state linked to G protein-independent MAPK signaling. Using receptor mutagenesis, we focused on the seventh transmembrane domain and identified three key residues-Tyr(292), Phe(293), and Thr(287). At least three distinct activated states were revealed: 1) an AngII-stabilized state linked to G(q)/PLC signaling, 2) an AngII-stabilized state connected to G protein-independent MAPK activation, and 3) a SII-stabilized state associated with G protein-independent MAPK signaling. The mutant Y292F failed to exhibit AngII-induced IP(3) turnover yet remained capable of AngII-induced MAPK activation. SII failed to stimulate MAPK in Y292F-transfected cells. Thus, Tyr(292) is a key epitope for activated states 1 and 3 but not required for activated state 2. Although the F293L mutant retained normal AngII responses, it also showed an IP(3) response to SII, indicating that Phe(293) may be involved in constraining the receptor to its inactive state. Mutations of Thr(287) abolished all SII-induced signaling without affecting any AngII responses. Thr(287) therefore represents a key residue for a SII-stabilized activated state. Taken together, the data identified a novel structural requirement (Thr(287)) for the SII-stabilized activated state and redefined the mechanistic roles for Tyr(292) and Phe(293).
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MESH Headings
- Animals
- COS Cells
- Chlorocebus aethiops
- Conserved Sequence
- Enzyme Activation/physiology
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Extracellular Signal-Regulated MAP Kinases/physiology
- GTP-Binding Proteins/metabolism
- GTP-Binding Proteins/physiology
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Models, Biological
- Mutation
- Point Mutation
- Protein Structure, Quaternary
- Protein Structure, Tertiary
- Rats
- Receptor, Angiotensin, Type 1/agonists
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Transfection
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Affiliation(s)
- Daniel K Yee
- Department of Animal Biology, University of Pennsylvania, Philadelphia, 19104-6046, USA.
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27
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Zhai P, Yamamoto M, Galeotti J, Liu J, Masurekar M, Thaisz J, Irie K, Holle E, Yu X, Kupershmidt S, Roden DM, Wagner T, Yatani A, Vatner DE, Vatner SF, Sadoshima J. Cardiac-specific overexpression of AT1 receptor mutant lacking G alpha q/G alpha i coupling causes hypertrophy and bradycardia in transgenic mice. J Clin Invest 2006; 115:3045-56. [PMID: 16276415 PMCID: PMC1265872 DOI: 10.1172/jci25330] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 08/30/2005] [Indexed: 12/25/2022] Open
Abstract
Ang II type 1 (AT1) receptors activate both conventional heterotrimeric G protein-dependent and unconventional G protein-independent mechanisms. We investigated how these different mechanisms activated by AT1 receptors affect growth and death of cardiac myocytes in vivo. Transgenic mice with cardiac-specific overexpression of WT AT1 receptor (AT1-WT; Tg-WT mice) or an AT1 receptor second intracellular loop mutant (AT1-i2m; Tg-i2m mice) selectively activating G(alpha)q/G(alpha)i-independent mechanisms were studied. Tg-i2m mice developed more severe cardiac hypertrophy and bradycardia coupled with lower cardiac function than Tg-WT mice. In contrast, Tg-WT mice exhibited more severe fibrosis and apoptosis than Tg-i2m mice. Chronic Ang II infusion induced greater cardiac hypertrophy in Tg-i2m compared with Tg-WT mice whereas acute Ang II administration caused an increase in heart rate in Tg-WT but not in Tg-i2m mice. Membrane translocation of PKCepsilon, cytoplasmic translocation of G(alpha)q, and nuclear localization of phospho-ERKs were observed only in Tg-WT mice while activation of Src and cytoplasmic accumulation of phospho-ERKs were greater in Tg-i2m mice, consistent with the notion that G(alpha)q/G(alpha)i-independent mechanisms are activated in Tg-i2m mice. Cultured myocytes expressing AT1-i2m exhibited a left and upward shift of the Ang II dose-response curve of hypertrophy compared with those expressing AT1-WT. Thus, the AT1 receptor mediates downstream signaling mechanisms through G(alpha)q/G(alpha)i-dependent and -independent mechanisms, which induce hypertrophy with a distinct phenotype.
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MESH Headings
- Animals
- Apoptosis/genetics
- Bradycardia/genetics
- Bradycardia/metabolism
- Bradycardia/pathology
- Cells, Cultured
- Electrocardiography
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Fibrosis/genetics
- Fibrosis/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/deficiency
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11/deficiency
- GTP-Binding Protein alpha Subunits, Gq-G11/genetics
- GTP-Binding Protein alpha Subunits, Gq-G11/metabolism
- Hypertrophy, Left Ventricular/genetics
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Mice
- Mice, Transgenic
- Mutation
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Phenotype
- Protein Kinase C-epsilon/metabolism
- Rats
- Rats, Wistar
- Receptor, Angiotensin, Type 1/deficiency
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
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Affiliation(s)
- Peiyong Zhai
- Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA
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28
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Hunyady L, Catt KJ. Pleiotropic AT1 receptor signaling pathways mediating physiological and pathogenic actions of angiotensin II. Mol Endocrinol 2005; 20:953-70. [PMID: 16141358 DOI: 10.1210/me.2004-0536] [Citation(s) in RCA: 401] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Angiotensin II (Ang II) activates a wide spectrum of signaling responses via the AT1 receptor (AT1R) that mediate its physiological control of blood pressure, thirst, and sodium balance and its diverse pathological actions in cardiovascular, renal, and other cell types. Ang II-induced AT1R activation via Gq/11 stimulates phospholipases A2, C, and D, and activates inositol trisphosphate/Ca2+ signaling, protein kinase C isoforms, and MAPKs, as well as several tyrosine kinases (Pyk2, Src, Tyk2, FAK), scaffold proteins (G protein-coupled receptor kinase-interacting protein 1, p130Cas, paxillin, vinculin), receptor tyrosine kinases, and the nuclear factor-kappaB pathway. The AT1R also signals via Gi/o and G11/12 and stimulates G protein-independent signaling pathways, such as beta-arrestin-mediated MAPK activation and the Jak/STAT. Alterations in homo- or heterodimerization of the AT1R may also contribute to its pathophysiological roles. Many of the deleterious actions of AT1R activation are initiated by locally generated, rather than circulating, Ang II and are concomitant with the harmful effects of aldosterone in the cardiovascular system. AT1R-mediated overproduction of reactive oxygen species has potent growth-promoting, proinflammatory, and profibrotic actions by exerting positive feedback effects that amplify its signaling in cardiovascular cells, leukocytes, and monocytes. In addition to its roles in cardiovascular and renal disease, agonist-induced activation of the AT1R also participates in the development of metabolic diseases and promotes tumor progression and metastasis through its growth-promoting and proangiogenic activities. The recognition of Ang II's pathogenic actions is leading to novel clinical applications of angiotensin-converting enzyme inhibitors and AT1R antagonists, in addition to their established therapeutic actions in essential hypertension.
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Affiliation(s)
- László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
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29
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Rebas E, Lachowicz-Ochedalska A. The effect of angiotensin III on protein tyrosine kinase activity in rat pituitary. ACTA ACUST UNITED AC 2005; 130:14-8. [PMID: 15913807 DOI: 10.1016/j.regpep.2005.02.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Accepted: 02/04/2005] [Indexed: 10/25/2022]
Abstract
Angiotensin III is the biological active peptide from the angiotensin family, which play the important role in several cellular processes. Ang III is the product of reaction catalyzed by aminopeptidase A and in turn can be a substrate for aminopeptidase N, enzyme which converts Ang III to shorter fragment, Ang IV. Aminopeptidase N is specifically inhibited by PC18. Ang III can act by binding to receptors AT1, AT2 or other type of receptors, which are not well recognized. The connection of Ang III to AT1 and AT2 receptors could be inhibited by losartan or PD123319, respectively. The aim of this study was to investigate what is the influence of angiotensin III on protein tyrosine kinase activity in rat pituitary and what is the possible place of interaction of Ang III with target cells. The obtained results show that Ang III can modify tyrosine kinase activity in concentration dependent manner but Ang IV appeared more effective. In presence of PC18 Ang III caused the same changes as Ang III alone that suggests that Ang III, not its metabolite modify tyrosine kinase activity. Losartan and PD123319 given together with Ang III enhanced the changes induced by Ang III. It suggests that the investigated peptide has an effect on protein tyrosine kinase activity in a different way than via AT1 and AT2 receptors.
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Affiliation(s)
- Elzbieta Rebas
- Department of Medical Biochemistry, Institute of Physiology and Biochemistry, Medical University of Lodz, Poland
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30
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Mifune M, Ohtsu H, Suzuki H, Nakashima H, Brailoiu E, Dun NJ, Frank GD, Inagami T, Higashiyama S, Thomas WG, Eckhart AD, Dempsey PJ, Eguchi S. G protein coupling and second messenger generation are indispensable for metalloprotease-dependent, heparin-binding epidermal growth factor shedding through angiotensin II type-1 receptor. J Biol Chem 2005; 280:26592-9. [PMID: 15905175 DOI: 10.1074/jbc.m502906200] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
A G protein-coupled receptor agonist, angiotensin II (AngII), induces epidermal growth factor (EGF) receptor (EGFR) transactivation possibly through metalloprotease-dependent, heparin-binding EGF (HB-EGF) shedding. Here, we have investigated signal transduction of this process by using COS7 cells expressing an AngII receptor, AT1. In these cells AngII-induced EGFR transactivation was completely inhibited by pretreatment with a selective HB-EGF inhibitor, or with a metalloprotease inhibitor. We also developed a COS7 cell line permanently expressing a HB-EGF construct tagged with alkaline phosphatase, which enabled us to measure HB-EGF shedding quantitatively. In the COS7 cell line AngII stimulated release of HB-EGF. This effect was mimicked by treatment either with a phospholipase C activator, a Ca2+ ionophore, a metalloprotease activator, or H2O2. Conversely, pretreatment with an intracellular Ca2+ antagonist or an antioxidant blocked AngII-induced HB-EGF shedding. Moreover, infection of an adenovirus encoding an inhibitor of G(q) markedly reduced EGFR transactivation and HB-EGF shedding through AT1. In this regard, AngII-stimulated HB-EGF shedding was abolished in an AT1 mutant that lacks G(q) protein coupling. However, in cells expressing AT1 mutants that retain G(q) protein coupling, AngII is still able to induce HB-EGF shedding. Finally, the AngII-induced EGFR transactivation was attenuated in COS7 cells overexpressing a catalytically inactive mutant of ADAM17. From these data we conclude that AngII stimulates a metalloprotease ADAM17-dependent HB-EGF shedding through AT1/G(q)/phospholipase C-mediated elevation of intracellular Ca2+ and reactive oxygen species production, representing a key mechanism indispensable for EGFR transactivation.
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Affiliation(s)
- Mizuo Mifune
- Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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31
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Gletsu N, Doan TN, Cole J, Sutliff RL, Bernstein KE. Angiotensin II-induced hypertension in mice caused an increase in insulin secretion. Vascul Pharmacol 2005; 42:83-92. [PMID: 15792925 DOI: 10.1016/j.vph.2005.01.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE AND DESIGN Insulin action was determined in a mouse model of human hypertension via chronic angiotensin II administration followed by a glucose tolerance test. METHODS Angiotensin II or saline was infused systemically into mice via osmotic pump for 2 or 4 weeks. In angiotensin II-treated mice versus saline controls we compared blood pressure, blood glucose, and serum insulin concentrations during an intravenous glucose tolerance test and assessed glucose transport and insulin signaling in muscle. RESULTS Blood pressure increased at 2 and 4 weeks following angiotensin II treatment. Mice treated with angiotensin II for 4 weeks cleared a glucose bolus faster than mice treated with saline despite similar basal serum insulin concentrations. Upon glucose administration, the increase in serum insulin was greater in angiotensin II-treated mice, 38.8+/-6.5 pmol/l, compared to saline-treated mice, 21.8+/-2.9 pmol/l, but only at 4 weeks of angiotensin II treatment while no difference was observed at 2 weeks of angiotensin II administration. At 4 weeks of angiotensin II treatment, insulin signaling in the liver and in the skeletal muscle was not affected, since both the number of insulin receptors and phosphorylation of Akt were unchanged. Also at 4 weeks of angiotensin II treatment, ex vivo soleus muscle did not exhibit any change in basal and insulin-stimulated glucose uptake. CONCLUSIONS This study suggests that long-term angiotensin II treatment for 4 weeks enhances glucose-stimulated insulin secretion in mice. Angiotensin II-induced hyperinsulinemia may play a role in the development of insulin resistance in patients with hypertension.
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Affiliation(s)
- Nana Gletsu
- Department of Pathology and Experimental Medicine, Emory University School of Medicine, Room 7107A, 1639 Pierce Drive, Atlanta, Georgia 30322, USA
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32
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Abstract
Vacuolar H(+)-ATPases are ubiquitous multisubunit complexes mediating the ATP-dependent transport of protons. In addition to their role in acidifying the lumen of various intracellular organelles, vacuolar H(+)-ATPases fulfill special tasks in the kidney. Vacuolar H(+)-ATPases are expressed in the plasma membrane in the kidney almost along the entire length of the nephron with apical and/or basolateral localization patterns. In the proximal tubule, a high number of vacuolar H(+)-ATPases are also found in endosomes, which are acidified by the pump. In addition, vacuolar H(+)-ATPases contribute to proximal tubular bicarbonate reabsorption. The importance in final urinary acidification along the collecting system is highlighted by monogenic defects in two subunits (ATP6V0A4, ATP6V1B1) of the vacuolar H(+)-ATPase in patients with distal renal tubular acidosis. The activity of vacuolar H(+)-ATPases is tightly regulated by a variety of factors such as the acid-base or electrolyte status. This regulation is at least in part mediated by various hormones and protein-protein interactions between regulatory proteins and multiple subunits of the pump.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, Univ. of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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33
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Wallace TA, VonDerLinden D, He K, Frank SJ, Sayeski PP. Microarray analyses identify JAK2 tyrosine kinase as a key mediator of ligand-independent gene expression. Am J Physiol Cell Physiol 2004; 287:C981-91. [PMID: 15189810 DOI: 10.1152/ajpcell.00085.2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mice lacking a functional Janus kinase 2 (JAK2) allele die embryonically, indicating the mandatory role of JAK2 in basic developmental cellular transcription. Currently, however, the downstream target genes of JAK2 are largely unknown. Here, in vitro conditions were created using a cell line lacking JAK2 expression. Microarray analysis was then used to identify genes that are differentially expressed as a result of the presence, or absence, of JAK2. The data identified 621 JAK2-dependent genes as having at least a twofold change in expression. Surprisingly, these genes did not require ligand-dependent activation of JAK2 but merely its expression in the cell. Thirty-one of these genes were found to have a greater than sevenfold change in expression levels, and a subset of these were further characterized. These genes represent a diverse cluster of ontological functions including transcription factors, signaling molecules, and cell surface receptors. The expression levels of these genes were validated by Northern blot and/or quantitative RT-PCR analysis in both the JAK2 null cells and cells expressing a JAK2-dominant negative allele. As such, this work demonstrates for the first time that, in addition to being a key mediator of ligand-activated gene transcription, JAK2 can perhaps also be viewed as a critical mediator of basal level gene expression.
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Affiliation(s)
- Tiffany A Wallace
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, PO Box 100274, Gainesville, FL 32610, USA
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34
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Weiss S, Doan T, Bernstein KE, Dascal N. Modulation of Cardiac Ca2+ Channel by Gq-activating Neurotransmitters Reconstituted in Xenopus Oocytes. J Biol Chem 2004; 279:12503-10. [PMID: 14722109 DOI: 10.1074/jbc.m310196200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
L-type dihydropyridine-sensitive voltage dependent Ca(2+) channels (L-VDCCs; alpha(1C)) are crucial in cardiovascular physiology. Currents via L-VDCCs are enhanced by hormones and transmitters operating via G(q), such as angiotensin II (AngII) and acetylcholine (ACh). It has been proposed that these modulations are mediated by protein kinase C (PKC). However, reports on effects of PKC activators on L-type channels are contradictory; inhibitory and/or enhancing effects have been observed. Attempts to reproduce the enhancing effect of AngII in heterologous expression systems failed. We previously found that PKC modulation of the channel depends on alpha(1C) isoform used; only a long N-terminal (NT) isoform was up-regulated. Here we report the reconstitution of the AngII- and ACh-induced enhancement of the long-NT isoform of L-VDCC expressed in Xenopus oocytes. The current initially increased over several minutes but later declined to below baseline levels. Using different NT deletion mutants and human short- and long-NT isoforms of the channel, we found the initial segment of the NT to be crucial for the enhancing, but not for the inhibitory, effect. Using blockers of PKC and of phospholipase C (PLC) and a mutated AngII receptor lacking G(q) coupling, we demonstrate that the signaling pathway of the enhancing effect includes the activation of G(q), PLC, and PKC. The inhibitory modulation, present in both alpha(1C) isoforms, was G(q)- and PLC-independent and Ca(2+)-dependent, but not Ca(2+)-mediated, as only basal levels of Ca(2+) were essential. Reconstitution of AngII and ACh effects in Xenopus oocytes will advance the study of molecular mechanisms of these physiologically important modulations.
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Affiliation(s)
- Sharon Weiss
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel
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35
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Miura SI, Zhang J, Matsuo Y, Saku K, Karnik SS. Activation of Extracellular Signal-Activated Kinase by Angiotensin II-Induced Gq-Independent Epidermal Growth Factor Receptor Transactivation. Hypertens Res 2004; 27:765-70. [PMID: 15785012 DOI: 10.1291/hypres.27.765] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Multiple signaling pathways link the angiotensin II (Ang II) type 1 (AT1) receptor to Gq-dependent inositol phosphate (IP) production and Gq-independent phospho-extracellular signal-activated kinase (p-ERK) 1/2 activation by Ang II in the regulation of cardiovascular vasoconstriction and cell growth, respectively. An Ang II analogue, [Sar1, Ile4, Ile8]Ang II, did not stimulate Gq-dependent IP production, but still activated Gq-independent p-ERK1/2 in human coronary artery smooth muscle cells as well as in a cell line that stably expressed AT1. This activation was mostly mediated by [Sar1, Ile4, Ile8]Ang II-induced Gq-independent epidermal growth factor receptor transactivation. We found that AT1 receptor signaling shows bifurcation into functionally separate pathways. A clear understanding of this unique signaling may be necessary for the development of therapeutic agents to treat disorders such as hypertension and cardiac hypertrophy.
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Affiliation(s)
- Shin-ichiro Miura
- Department of Cardiology, Fukuoka University School of Medicine, Fukuoka, Japan.
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36
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AngiotensinII mediates cardiomyocyte hypertrophic growth pathways via MMP-dependent HB-EGF liberation. Int J Pept Res Ther 2003. [DOI: 10.1007/s10989-004-2398-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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37
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Smith NJ, Hannan RD, Thomas WG, Lew RA. AngiotensinII mediates cardiomyocyte hypertrophic growth pathways via MMP-dependent HB-EGF liberation. ACTA ACUST UNITED AC 2003. [DOI: 10.1007/bf02442574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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38
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Hines J, Fluharty SJ, Yee DK. Structural determinants for the activation mechanism of the angiotensin II type 1 receptor differ for phosphoinositide hydrolysis and mitogen-activated protein kinase pathways. Biochem Pharmacol 2003; 66:251-62. [PMID: 12826267 DOI: 10.1016/s0006-2952(03)00257-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
While the mechanism whereby the angiotensin II type 1 receptor (AT(1) receptor) activates its classical effector phospholipase C-beta (PLC-beta) has largely been elucidated, there is little consensus on how this receptor activates a more recently identified effector, the p42/44 mitogen-activated protein kinases (p42/44(MAPK)). Using transfected COS-1 cells, we investigated the activation of this signaling pathway at the receptor level itself. Previous mutational studies that relied on phosphoinositide turnover as an index of receptor activation have indicated that key residues in the second and seventh transmembrane domains participate in AT(1) receptor activation mechanisms. Thus, we introduced a variety of mutations-AT(1)[D74N], AT(1)[Y292F], AT(1)[N295S], and AT(1)[AT(2) TM7], which is composed of a chimeric substitution of the AT(1) seventh transmembrane domain with its AT(2) counterpart. These mutations that strongly diminished the receptor's ability to activate PLC-beta had little to no effect on its ability to activate p42/44(MAPK), which not only suggests that p42/44(MAPK) does not exclusively lie downstream of the G-protein G(q)/PLC-beta pathway but also indicates that more than one activation state may exist for the AT(1) receptor. The failure of a protein kinase C inhibitor to block AT(1) receptor activation of p42/44(MAPK) further corroborated evidence that the receptor's activation of p42/44(MAPK) is largely independent of the G(q)/PLC-beta/PKC pathway. Taken together, the experimental evidence strongly suggests that the mechanism whereby the AT(1) receptor activates p42/44(MAPK) is fundamentally different from that for PLC-beta, even at the level of the receptor itself.
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Affiliation(s)
- John Hines
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104-6046, USA
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39
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Dugourd C, Gervais M, Corvol P, Monnot C. Akt is a major downstream target of PI3-kinase involved in angiotensin II-induced proliferation. Hypertension 2003; 41:882-90. [PMID: 12623864 DOI: 10.1161/01.hyp.0000060821.62417.35] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Different signal transduction cascades have been implicated in angiotensin II (Ang II)-mediated cell growth, such as the extracellular signal-regulated kinase 1/2 (ERK1/2) and the phosphatidylinositol 3-kinase (PI3K) pathways. To identify the downstream targets of PI3K involved in Ang II-induced proliferation, we used both rat aortic smooth muscle (RASM) cells and a CHO cell line stably expressing the rat AT1A receptor. The ERK1/2 and PI3K pathways are independently activated and implicated in Ang II-mediated DNA synthesis and cell number increase in these 2 cell lines. In addition, a specific inhibitor of Akt inhibited Ang II-induced Akt phosphorylation, DNA synthesis and proliferation in CHO-AT1A or RASM cells. A dominant-negative mutant of Akt was also found to selectively block Ang II-induced proliferation of CHO-AT1A cells. To further elucidate the signaling events leading to Akt activation, we used an AT1 receptor mutant (AT1AD74E), deficient for Gq protein coupling, and the intracellular calcium chelator BAPTA-AM. Although altered Akt and ERK1/2 activation was observed in the CHO-AT1AD74E cell line, blockade of intracellular calcium elevation did not affect phosphorylation of these kinases. These results provide the first evidence of a specific and necessary role of Akt in Ang II-induced proliferation through a Gq protein-dependent calcium-independent pathway.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- CHO Cells
- Calcium Signaling
- Cell Division
- Cricetinae
- MAP Kinase Signaling System
- Male
- Mitogen-Activated Protein Kinase Kinases/metabolism
- Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/metabolism
- Mutation
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphorylation
- Protein Serine-Threonine Kinases
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins/physiology
- Proto-Oncogene Proteins c-akt
- Rats
- Receptor, Angiotensin, Type 1
- Receptors, Angiotensin/genetics
- Receptors, Angiotensin/metabolism
- Recombinant Proteins/metabolism
- Signal Transduction
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Affiliation(s)
- Céline Dugourd
- INSERM U36-Collège de France, 11, place Marcelin Berthelot, 75005 Paris, France
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40
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Wang Q, Liu M, Mullah B, Siderovski DP, Neubig RR. Receptor-selective effects of endogenous RGS3 and RGS5 to regulate mitogen-activated protein kinase activation in rat vascular smooth muscle cells. J Biol Chem 2002; 277:24949-58. [PMID: 12006602 DOI: 10.1074/jbc.m203802200] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Regulators of G protein signaling (RGS) proteins compose a highly diverse protein family best known for inhibition of G protein signaling by enhancing GTP hydrolysis by Galpha subunits. Little is known about the function of endogenous RGS proteins. In this study, we used synthetic ribozymes targeted to RGS2, RGS3, RGS5, and RGS7 to assess their function. After demonstrating the specificity of in vitro cleavage by the RGS ribozymes, rat aorta smooth muscle cells were used for transient transfection with the RGS-specific ribozymes. RGS3 and RGS5 ribozymes differentially enhanced carbachol- and angiotensin II-induced MAP kinase activity, respectively, whereas RGS2 and RGS7 ribozymes had no effect. This enhancement was pertussis toxin-insensitive. Thus RGS3 is a negative modulator of muscarinic m3 receptor signaling, and RGS5 is a negative modulator of angiotensin AT1a receptor signaling through G(q/11). Also, RGS5 ribozyme enhanced angiotensin-stimulated inositol phosphate release. These results indicate the feasibility of using the ribozyme technology to determine the functional role of endogenous RGS proteins in signaling pathways and to define novel receptor-selective roles of endogenous RGS3 and RGS5 in modulating MAP kinase responses to either carbachol or angiotensin.
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MESH Headings
- Animals
- Base Sequence
- Catalysis
- DNA Primers
- Enzyme Activation
- GTP-Binding Proteins
- GTPase-Activating Proteins
- Mitogen-Activated Protein Kinases/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Pertussis Toxin
- RGS Proteins/genetics
- RGS Proteins/physiology
- RNA, Catalytic/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Receptors, Angiotensin/metabolism
- Repressor Proteins
- Virulence Factors, Bordetella/pharmacology
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Affiliation(s)
- Qin Wang
- Department of Pharmacology, the University of Michigan, Ann Arbor 48109-0632, USA
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41
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Holloway AC, Qian H, Pipolo L, Ziogas J, Miura SI, Karnik S, Southwell BR, Lew MJ, Thomas WG. Side-chain substitutions within angiotensin II reveal different requirements for signaling, internalization, and phosphorylation of type 1A angiotensin receptors. Mol Pharmacol 2002; 61:768-77. [PMID: 11901215 DOI: 10.1124/mol.61.4.768] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Binding of the peptide hormone angiotensin II (AngII) to the type 1 (AT(1A)) receptor and the subsequent activation of phospholipase C-mediated signaling, involves specific determinants within the AngII peptide sequence. In contrast, the contribution of such determinants to AT(1A) receptor internalization, phosphorylation and activation of mitogen-activated protein kinase (MAPK) signaling is not known. In this study, the internalization of an enhanced green fluorescent protein-tagged AT(1A) receptor (AT(1A)-EGFP), in response to AngII and a series of substituted analogs, was visualized and quantified using confocal microscopy. AngII-stimulation resulted in a rapid, concentration-dependent internalization of the chimeric receptor, which was prevented by pretreatment with the nonpeptide AT(1) receptor antagonist EXP3174. Remarkably, AT(1A) receptor internalization was unaffected by substitution of AngII side chains, including single and double substitutions of Tyr(4) and Phe(8) that abolish phospholipase C signaling through the receptor. AngII-induced receptor phosphorylation was significantly inhibited by several substitutions at Phe(8) as well as alanine replacement of Asp(1). The activation of MAPK was only significantly inhibited by substitutions at position eight in the peptide and specific substitutions did not equally inhibit inositol phosphate production, receptor phosphorylation and MAPK activation. These results indicate that separate, yet overlapping, contacts made between the AngII peptide and the AT(1A) receptor select/induce distinct receptor conformations that preferentially affect particular receptor outcomes. The requirements for AT(1A) receptor internalization seem to be less stringent than receptor activation and signaling, suggesting an inherent bias toward receptor deactivation.
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Affiliation(s)
- Alice C Holloway
- Molecular Endocrinology Laboratory, Baker Medical Research Institute, Melbourne, Australia
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42
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Seta K, Nanamori M, Modrall JG, Neubig RR, Sadoshima J. AT1 receptor mutant lacking heterotrimeric G protein coupling activates the Src-Ras-ERK pathway without nuclear translocation of ERKs. J Biol Chem 2002; 277:9268-77. [PMID: 11777928 DOI: 10.1074/jbc.m109221200] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Angiotensin II (Ang II) type 1 receptors (AT1Rs) activate tyrosine kinases, including Src. Whether or not tyrosine kinase activation by AT1R occurs independently of heterotrimeric G protein coupling and, if so, the cellular function of such a mechanism are unknown. To address these questions, we used an AT1aR intracellular second loop mutant, which lacks heterotrimeric G protein coupling (AT1a-i2m). Surprisingly, Ang II-induced Src activation was preserved in AT1a-i2m, which was not attenuated by inhibiting protein kinase C and Ca(2+) or by inhibiting Galpha(i) or Galpha(q) in CHO-K1 cells. By contrast, Ang II-induced Src activation was abolished in a C-terminally truncated AT1a-(1--309), where Ang II-induced inositol phosphate response was preserved. Ang II activates ERKs via a Src-Ras-dependent mechanism in AT1a-i2m. ERKs activated by AT1a-i2m phosphorylate their cytoplasmic targets, including p90(RSK), but fail to translocate into the nucleus or to cause cell proliferation. Ang II-induced nuclear translocation of ERKs by wild type AT1aR was inhibited by overexpression of nuclear exportin Crm-1, while that by AT1a-i2m was restored by leptomycin B, an inhibitor of Crm-1. In summary, while Src and ERKs are activated by Ang II even without heterotrimeric G protein coupling, the carboxyl terminus of the AT1 receptor is required for activation of Src. Interestingly, ERKs activated by heterotrimeric G protein-independent mechanisms fail to phosphorylate nuclear targets due to lack of inhibition of Crm-1-induced nuclear export of ERKs. These results suggest that heterotrimeric G protein-dependent and -independent signaling mechanisms play distinct roles in Ang II-mediated cellular responses.
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Affiliation(s)
- Koichi Seta
- Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA
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43
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Luft FC. Angiotensin II and cell cycle inhibition. J Mol Med (Berl) 2001; 79:351-2. [PMID: 11466554 DOI: 10.1007/s001090100245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- F C Luft
- Franz-Volhard-Klinik, Humboldt University of Berlin, Wiltbergstrasse 50, 13125 Berlin-Buch, Germany.
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