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Cui C, Huang C, Zhou W, Ji X, Zhang F, Wang L, Zhou Y, Cui Q. AGTR2, One Possible Novel Key Gene for the Entry of SARS-CoV-2 Into Human Cells. IEEE/ACM Trans Comput Biol Bioinform 2021; 18:1230-1233. [PMID: 32750889 DOI: 10.1109/tcbb.2020.3009099] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Recently, it was confirmed that ACE2 is the receptor of SARS-CoV-2, the pathogen causing the recent outbreak of severe pneumonia around the world. It is confused that ACE2 is widely expressed across a variety of organs and is expressed moderately but not highly in lung, which, however, is the major infected organ. Therefore, we hypothesized that there could be some other genes playing key roles in the entry of SARS-CoV-2 into human cells. Here we found that AGTR2 (angiotensin II receptor type 2), a G-protein coupled receptor, has interaction with ACE2 and is highly expressed in lung with a high tissue specificity. More importantly, simulation of 3D structure based protein-protein interaction reveals that AGTR2 shows a higher binding affinity with the Spike protein of SARS-CoV-2 than ACE2 (energy: -8.2 vs. -5.1 [kcal/mol]). A number of compounds, biologics and traditional Chinese medicine that could decrease the expression level of AGTR2 were predicted. Finally, we suggest that AGTR2 could be a putative novel gene for the entry of SARS-CoV-2 into human cells, which could provide different insight for the research of SARS-CoV-2 proteins with their receptors.
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MESH Headings
- Angiotensin-Converting Enzyme 2/chemistry
- Angiotensin-Converting Enzyme 2/physiology
- Antiviral Agents/pharmacology
- COVID-19/genetics
- COVID-19/physiopathology
- COVID-19/virology
- Computational Biology
- Computer Simulation
- Drug Evaluation, Preclinical
- Humans
- Models, Molecular
- Protein Interaction Maps
- Receptor, Angiotensin, Type 2/chemistry
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/physiology
- Receptors, Virus/chemistry
- Receptors, Virus/genetics
- Receptors, Virus/physiology
- SARS-CoV-2/drug effects
- SARS-CoV-2/pathogenicity
- SARS-CoV-2/physiology
- Serine Endopeptidases/genetics
- Spike Glycoprotein, Coronavirus/chemistry
- Spike Glycoprotein, Coronavirus/physiology
- Transcriptome/drug effects
- Virus Internalization
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2
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Amin M, Sorour MK, Kasry A. Comparing the Binding Interactions in the Receptor Binding Domains of SARS-CoV-2 and SARS-CoV. J Phys Chem Lett 2020; 11:4897-4900. [PMID: 32478523 PMCID: PMC7294866 DOI: 10.1021/acs.jpclett.0c01064] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 06/01/2020] [Indexed: 05/21/2023]
Abstract
SARS-CoV-2, since emerging in Wuhan, China, has been a major concern because of its high infection rate and has left more than six million infected people around the world. Many studies endeavored to reveal the structure of the SARS-CoV-2 compared to the SARS-CoV, in order to find solutions to suppress this high infection rate. Some of these studies showed that the mutations in the SARS-CoV spike (S) protein might be responsible for its higher affinity to the ACE2 human cell receptor. In this work, we used molecular dynamics simulations and Monte Carlo sampling to compare the binding affinities of the S proteins of SARS-CoV and SARS-CoV-2 to the ACE2. Our results show that the protein surface of the ACE2 at the receptor binding domain (RBD) exhibits negative electrostatic potential, while a positive potential is observed for the S proteins of SARS-CoV/SARS-CoV-2. In addition, the binding energies at the interface are slightly higher for SARS-CoV-2 because of enhanced electrostatic interactions. The major contributions to the electrostatic binding energies result from the salt bridges forming between R426 and ACE-2-E329 in the case of SARS-CoV and K417 and ACE2-D30 in the SARS-CoV-2. In addition, our results indicate that the enhancement in the binding energy is not due to a single mutant but rather because of the sophisticated structural changes induced by all these mutations together. This finding suggests that it is implausible for the SARS-CoV-2 to be a lab-engineered virus.
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Affiliation(s)
- Muhamed Amin
- Department of Sciences, University
College Groningen, University of Groningen,
Hoendiepskade 23/24, 9718 BG Groningen, The
Netherlands
- Center for Free-Electron Laser
Science, Deutsches Elektronen-Synchrotron
DESY, Notkestrasse 85, 22607 Hamburg,
Germany
- Centre for Theoretical Physics,
The British University in Egypt,
Sherouk City, 11837 Cairo, Egypt
| | - Mariam K. Sorour
- Nanotechnology Research Centre (NTRC),
the British University in Egypt
(BUE), El Sherouk City, Suez Desert Road, Cairo 1183,
Egypt
| | - Amal Kasry
- Nanotechnology Research Centre (NTRC),
the British University in Egypt
(BUE), El Sherouk City, Suez Desert Road, Cairo 1183,
Egypt
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3
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Vasile S, Hallberg A, Sallander J, Hallberg M, Åqvist J, Gutiérrez-de-Terán H. Evolution of Angiotensin Peptides and Peptidomimetics as Angiotensin II Receptor Type 2 (AT2) Receptor Agonists. Biomolecules 2020; 10:E649. [PMID: 32340100 PMCID: PMC7226584 DOI: 10.3390/biom10040649] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 04/01/2020] [Accepted: 04/17/2020] [Indexed: 12/19/2022] Open
Abstract
Angiotensin II receptor type 1 and 2 (AT1R and AT2R) are two G-protein coupled receptors that mediate most biological functions of the octapeptide Angiotensin II (Ang II). AT2R is upregulated upon tissue damage and its activation by selective AT2R agonists has become a promising approach in the search for new classes of pharmaceutical agents. We herein analyzed the chemical evolution of AT2R agonists starting from octapeptides, through shorter peptides and peptidomimetics to the first drug-like AT2R-selective agonist, C21, which is in Phase II clinical trials and aimed for idiopathic pulmonary fibrosis. Based on the recent crystal structures of AT1R and AT2R in complex with sarile, we identified a common binding model for a series of 11 selected AT2R agonists, consisting of peptides and peptidomimetics of different length, affinity towards AT2R and selectivity versus AT1R. Subsequent molecular dynamics simulations and free energy perturbation (FEP) calculations of binding affinities allowed the identification of the bioactive conformation and common pharmacophoric points, responsible for the key interactions with the receptor, which are maintained by the drug-like agonists. The results of this study should be helpful and facilitate the search for improved and even more potent AT2R-selective drug-like agonists.
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Affiliation(s)
- Silvana Vasile
- Sweden and Science for Life Laboratory, Department of Cell and Molecular Biology, BMC (H.G.T.), Biomedical Centre (BMC), Uppsala University, P.O. BOX 596, SE-751 24 Uppsala, Sweden; (S.V.); (J.S.); (J.Å.)
| | - Anders Hallberg
- Department of Medicinal Chemistry, Division of Organic Pharmaceutical Chemistry, BMC, Uppsala University, P.O. Box 574, SE-751 23 Uppsala, Sweden;
| | - Jessica Sallander
- Sweden and Science for Life Laboratory, Department of Cell and Molecular Biology, BMC (H.G.T.), Biomedical Centre (BMC), Uppsala University, P.O. BOX 596, SE-751 24 Uppsala, Sweden; (S.V.); (J.S.); (J.Å.)
| | - Mathias Hallberg
- The Beijer Laboratory, Department of Pharmaceutical Biosciences, Division of Biological Research on Drug Dependence, BMC, Uppsala University, P.O. Box 591, SE-751 24 Uppsala, Sweden;
| | - Johan Åqvist
- Sweden and Science for Life Laboratory, Department of Cell and Molecular Biology, BMC (H.G.T.), Biomedical Centre (BMC), Uppsala University, P.O. BOX 596, SE-751 24 Uppsala, Sweden; (S.V.); (J.S.); (J.Å.)
| | - Hugo Gutiérrez-de-Terán
- Sweden and Science for Life Laboratory, Department of Cell and Molecular Biology, BMC (H.G.T.), Biomedical Centre (BMC), Uppsala University, P.O. BOX 596, SE-751 24 Uppsala, Sweden; (S.V.); (J.S.); (J.Å.)
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4
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Connolly A, Holleran BJ, Simard É, Baillargeon JP, Lavigne P, Leduc R. Interplay between intracellular loop 1 and helix VIII of the angiotensin II type 2 receptor controls its activation. Biochem Pharmacol 2019; 168:330-338. [PMID: 31348898 DOI: 10.1016/j.bcp.2019.07.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/19/2019] [Indexed: 01/09/2023]
Abstract
The signaling mechanisms of the angiotensin II type 2 receptor (AT2R), a heptahelical receptor, have not yet been clearly and completely defined. In the present contribution, we set out to identify the molecular determinants involved in AT2R activation. Although AT2R has not been shown to engage Gq/11, G12, Gi2, and β-arrestin (βarr) pathways as does the AT1R upon angiotensin II (AngII) stimulation, the atypical positioning of helix VIII in the recently published AT2R structure may play a role in the receptor's capacity to couple to downstream effectors. In the AT2R structure, helix VIII points inwards and towards intracellular loop 3 (ICL3) to form tertiary interactions with transmembrane domain 6 (TM6), possibly impeding access to signaling effectors. On the other hand, in most class A GPCRs, helix VIII is found to be engaged in tertiary interactions with ICL1 and away from the effector binding site. Upon closer examination of the AT2R structure, we found that the residues contained within intracellular loop 1 (ICL1) may be involved in driving this unusual conformation of helix VIII. To explore this hypothesis, we designed a series of AT1R/AT2R receptor chimeras to validate the roles of ICL1 and helix VIII in AT2R signaling. Substituting the AT1R ICL1 into AT2R led to a mutant receptor that coupled to Gi2. The substitution of the helix VIII and C-terminal domains of AT2R into the AT1R backbone led to a mutant receptor that retained AT1R-like signaling properties. These results suggest that the C-terminal portion of AT2R is compatible with canonical GPCR signaling and that ICL1 of AT2R is involved in repositioning helix VIII, which impedes engagement of classical GPCR effectors such as G proteins or βarrs.
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Affiliation(s)
- Alexandre Connolly
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Institut de Pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Brian J Holleran
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Institut de Pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Élie Simard
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Institut de Pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Jean-Patrice Baillargeon
- Division of Endocrinology, Department of Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke J1H 5N4, Québec, Canada
| | - Pierre Lavigne
- Institut de Pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Department of Biochemistry, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Richard Leduc
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada; Institut de Pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
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5
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Sharma MC. Molecular modelling studies for the discovery of new substituted pyridines derivatives with angiotensin II AT1 receptor antagonists. Interdiscip Sci 2014; 6:197-207. [PMID: 25205497 DOI: 10.1007/s12539-013-0201-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 09/16/2013] [Accepted: 09/26/2013] [Indexed: 11/26/2022]
Abstract
A QSAR study has been performed on a series of pyridines derivatives with potent angiotensin II AT1 receptor antagonists. Structural features responsible for the activity of the compounds were characterized by using topological, electrotopological, group based and 3D descriptors, calculated from the Molecular Design Suite software (V-life MDS 3.5). To elucidate the structural properties required for antihypertensive activity, four different molecular modeling techniques; two-dimensional, Group-based (G-QSAR), k-nearest neighbour and pharmacophore approach. A suitable set of molecular descriptors was calculated and stepwise - partial component regression (SW-PCR) was employed to select the descriptors that resulted in the models with the best fit to the data. This study was performed with twenty two compounds using sphere exclusion algorithm method for the division of the data set into training and test set. The statistically significant 2D QSAR model having r(2) = 0.8407 and q(2) = 0.7395 with pred_r(2) = 0.7971 was developed by stepwise-partial component regression (SW-PCR) and best Group based QSAR model having R(2) = 0.8132 and Q(2) = 0.6804 with pred_r(2) = 0.7661 was developed by SW-PCR. The analyzed k-nearest neighbour MFA model revealed a good fit, having q(2) value of 0.7635. The predictive power of the model generated was validated using a test set molecules with pred _r(2) value of 0.7314. The generated k-nearest neighbour models suggest that steric and electrostatic interactions play an important role in describing the variation in binding affinity. Additionally the pharmacophore model well corraborated with k-nearest neighbour studies as the contours of later were in good agreement with the 3D orientation of the pharmacophoric features. The present analysis has shown that the antihypertensive activity can be improved with the presence of specific steric substituent and electro-donating and electro-withdrawing groups nearby the pyridine moiety. The Pharmacophore information shows that the four features used were two AroC feature, one HAc, one AlaC features. The structural variations in the molecular fields at particular regions in the space provide underlying structural requirements and 3D-QSAR models generated give good predictive ability and aid in the design of potent antihypertensive activity.
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Affiliation(s)
- Mukesh C Sharma
- Drug Research Laboratory, School of Pharmacy, Devi Ahilya University, Takshila Campus, Khandwa Road, Indore, M.P, 452 001, India,
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6
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Prokop JW, Santos RAS, Milsted A. Differential mechanisms of activation of the Ang peptide receptors AT1, AT2, and MAS: using in silico techniques to differentiate the three receptors. PLoS One 2013; 8:e65307. [PMID: 23755216 PMCID: PMC3670877 DOI: 10.1371/journal.pone.0065307] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 04/25/2013] [Indexed: 12/01/2022] Open
Abstract
The renin-angiotensin system is involved in multiple conditions ranging from cardiovascular disorders to cancer. Components of the pathway, including ACE, renin and angiotensin receptors are targets for disease treatment. This study addresses three receptors of the pathway: AT1, AT2, and MAS and how the receptors are similar and differ in activation by angiotensin peptides. Combining biochemical and amino acid variation data with multiple species sequence alignments, structural models, and docking site predictions allows for visualization of how angiotensin peptides may bind and activate the receptors; allowing identification of conserved and variant mechanisms in the receptors. MAS differs from AT1 favoring Ang-(1–7) and not Ang II binding, while AT2 recently has been suggested to preferentially bind Ang III. A new model of Ang peptide binding to AT1 and AT2 is proposed that correlates data from site directed mutagenesis and photolabled experiments that were previously considered conflicting. Ang II binds AT1 and AT2 through a conserved initial binding mode involving amino acids 111 (consensus 325) of AT1 (Asn) interacting with Tyr (4) of Ang II and 199 and 256 (consensus 512 and 621, a Lys and His respectively) interacting with Phe (8) of Ang II. In MAS these sites are not conserved, leading to differential binding and activation by Ang-(1–7). In both AT1 and AT2, the Ang II peptide may internalize through Phe (8) of Ang II propagating through the receptors’ conserved aromatic amino acids to the final photolabled positioning relative to either AT1 (amino acid 294, Asn, consensus 725) or AT2 (138, Leu, consensus 336). Understanding receptor activation provides valuable information for drug design and identification of other receptors that can potentially bind Ang peptides.
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Affiliation(s)
- Jeremy W. Prokop
- Department of Biology, Program in Integrated Bioscience, The University of Akron, Akron, Ohio, United States of America
| | - Robson A. S. Santos
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Amy Milsted
- Department of Biology, Program in Integrated Bioscience, The University of Akron, Akron, Ohio, United States of America
- * E-mail:
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7
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Jiang L, Teng GMK, Chan EYM, Au SWN, Wise H, Lee SST, Cheung WT. Impact of cell type and epitope tagging on heterologous expression of G protein-coupled receptor: a systematic study on angiotensin type II receptor. PLoS One 2012; 7:e47016. [PMID: 23056563 PMCID: PMC3466278 DOI: 10.1371/journal.pone.0047016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 09/11/2012] [Indexed: 12/19/2022] Open
Abstract
Despite heterologous expression of epitope-tagged GPCR is widely adopted for functional characterization, there is lacking of systematic analysis of the impact of expression host and epitope tag on GPCR expression. Angiotensin type II (AT2) receptor displays agonist-dependent and -independent activities, coupling to a spectrum of signaling molecules. However, consensus has not been reached on the subcellular distributions, signaling cascades and receptor-mediated actions. To examine the contributions of host cell and epitope tag on receptor expression and activity, epitope-tagged AT2 receptor variants were transiently or stably expressed in HEK293, CHO-K1 and PC12 cells. The epitope-tagged AT2 receptor variants were detected both on the cell membrane and in the perinuclear region. In transiently transfected HEK293 cells, Myc-AT2 existed predominantly as monomer. Additionally, a ladder of ubiquitinated AT2 receptor proteins was detected. By contrast, stably expressed epitope-tagged AT2 receptor variants existed as both monomer and high molecular weight complexes, and the latter was enriched in cell surface. Glycosylation promoted cell surface expression of Myc-AT2 but had no effect on AT2-GFP in HEK293 cells. In cells that stably expressed Myc-AT2, serum starvation induced apoptosis in CHO-K1 cells but not in HEK293 or PC12 cells. Instead, HEK293 and PC12 cells stably expressing Myc-AT2 exhibited partial cell cycle arrest with cells accumulating at G1 and S phases, respectively. Taken together, these results suggest that expression levels, subcellular distributions and ligand-independent constitutive activities of AT2 receptor were cell type-dependent while posttranslational processing of nascent AT2 receptor protein was modulated by epitope tag and mode of expression.
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Affiliation(s)
- Lili Jiang
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Gladys M. K. Teng
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Elaine Y. M. Chan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Shannon W. N. Au
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Helen Wise
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Susanna S. T. Lee
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- * E-mail: (WTC); (SL)
| | - Wing-Tai Cheung
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- * E-mail: (WTC); (SL)
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8
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Salhan D, Sagar A, Kumar D, Rattanavich R, Rai P, Maheshwari S, Adabala M, Husain M, Ding G, Malhotra A, Chander PN, Singhal PC. HIV-associated nephropathy: role of AT2R. Cell Signal 2012; 24:734-41. [PMID: 22108089 PMCID: PMC3258382 DOI: 10.1016/j.cellsig.2011.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 10/22/2011] [Accepted: 11/04/2011] [Indexed: 10/15/2022]
Abstract
AT(1)R has been reported to play an important role in the progression of HIV-associated nephropathy (HIVAN); however, the effect of AT(2)R has not been studied. Age and sex matched control (FVB/N) and Tg26 mice aged 4, 8, and 16weeks were studied for renal tissue expression of AT(1)R and AT(2)R (Protocol A). Renal tissue mRNA expression of AT(2)R was lower in Tg26 mice when compared with control mice. In Protocol B, Tg26 mice were treated with either saline, telmisartan (TEL, AT(1) blocker), PD123319 (PD, AT(2)R blocker), or TEL+PD for two weeks. TEL-receiving Tg26 (TRTg) displayed less advanced glomerular and tubular lesions when compared with saline-receiving Tg26 (SRTg). TRTgs displayed enhanced renal tissue AT(2)R expression when compared to SRTgs. Diminution of renal tissue AT(2)R expression was associated with advanced renal lesions in SRTgs; whereas, upregulation of AT(2)R expression in TRTgs was associated with attenuated renal lesions. PD-receiving Tg26 mice (PDRTg) did not show any alteration in the course of HIVAN; whereas, PD+TEL-receiving Tg26 (PD-TRTg) showed worsening of renal lesions when compared to TRTgs. Interestingly, plasma as well as renal tissues of Tg26 mice displayed several fold higher concentration of Ang III, a ligand of AT(2)R.
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Affiliation(s)
- Divya Salhan
- Division of Kidney Diseases and Hypertension, North Shore-LIJ Health System, Great Neck, NY 11021, United States
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9
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Guan XX, Zhou Y, Li JY. Reciprocal roles of angiotensin II and Angiotensin II Receptors Blockade (ARB) in regulating Cbfa1/RANKL via cAMP signaling pathway: possible mechanism for hypertension-related osteoporosis and antagonistic effect of ARB on hypertension-related osteoporosis. Int J Mol Sci 2011; 12:4206-13. [PMID: 21845073 PMCID: PMC3155346 DOI: 10.3390/ijms12074206] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 05/20/2011] [Accepted: 06/14/2011] [Indexed: 01/11/2023] Open
Abstract
Hypertension is a risk factor for osteoporosis. Animal and epidemiological studies demonstrate that high blood pressure is associated with increased calcium loss, elevated parathyroid hormone, and increased calcium movement from bone. However, the mechanism responsible for hypertension-related osteoporosis remains elusive. Recent epidemiological studies indicate the benefits of Angiotensin II Receptors Blockade (ARB) on decreasing fracture risks. Since receptors for angiotensin II, the targets of ARB, are expressed in both osteoblasts and osteoclasts, we postulated that angiotensin II plays an important role in hypertension-related osteoporosis. Cbfa1 and RANKL, the important factors for maintaining bone homeostasis and key mediators in controlling osteoblast and osteoclast differentiation, are both regulated by cAMP-dependent signaling. Angiotensin II along with factors such as LDL, HDL, NO and homocysteine that are commonly altered both in hypertension and osteoporosis, can down-regulate the expression of Cbfa1 but up-regulate RANKL expression via the cAMP signaling pathway. We thus hypothesized that, by altering the ratio of Cbfa1/RANKL expression via the cAMP-dependent pathway, angiotensin II differently regulates osteoblast and osteoclast differentiation leading to enhanced bone resorption and reduced bone formation. Since ARB can antagonize the adverse effect of angiotensin II on bone by lowering cAMP levels and modifying other downstream targets, including LDL, HDL, NO and Cbfa1/RANKL, we propose the hypothesis that the antagonistic effects of ARB may also be exerted via cAMP signaling pathway.
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Affiliation(s)
- Xiao-Xu Guan
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China; E-Mails: (X.-X.G.); (Y.Z.)
| | - Yi Zhou
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China; E-Mails: (X.-X.G.); (Y.Z.)
| | - Ji-Yao Li
- West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +86-28-85501439; Fax: +86-28-85527829
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10
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Bernardi S, Candido R, Toffoli B, Carretta R, Fabris B. Prevention of accelerated atherosclerosis by AT1 receptor blockade in experimental renal failure. Nephrol Dial Transplant 2010; 26:832-8. [PMID: 20810455 DOI: 10.1093/ndt/gfq524] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
MESH Headings
- Angiotensin II Type 1 Receptor Blockers/therapeutic use
- Animals
- Aorta/drug effects
- Aorta/pathology
- Apolipoproteins E/physiology
- Atherosclerosis/metabolism
- Atherosclerosis/prevention & control
- Benzimidazoles/therapeutic use
- Biphenyl Compounds
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Nephrectomy
- Phenotype
- RNA, Messenger/genetics
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/chemistry
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Renal Insufficiency/drug therapy
- Renal Insufficiency/etiology
- Renal Insufficiency/metabolism
- Renin-Angiotensin System/drug effects
- Renin-Angiotensin System/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Tetrazoles/therapeutic use
- Uremia/metabolism
- Uremia/prevention & control
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11
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Akazawa H, Komuro I. [Angiotensin II type 1 and type 2 receptor]. Nihon Rinsho 2009; 67:687-694. [PMID: 19348229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The octapeptide angiotensin II (AngII) plays a homeostatic role in the regulation of blood pressure and water and electrolyte balance, and contributes to the progression of cardiovascular remodeling. AngII activates AngII type 1 (AT1) receptor and type 2 (AT2) receptor, both of which belong to the seven-transmembrane, G protein-coupled receptor family. Most of the actions of AngII such as promotion of cellular proliferation, hypertrophy, and fibrosis are mediated by AT1 receptor. However, in some pathological situations, AT2 receptor showed an increase in expression level and functions to antagonize the actions by AT1 receptor stimulation. Recent studies have advanced our understanding of the molecular mechanisms underlying receptor activation and signal transduction, and elucidated the pathophysiological roles of AT1 and AT2 receptors in the cardiovascular system.
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Affiliation(s)
- Hiroshi Akazawa
- Division of Cardiovascular Pathophysiology, Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine
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12
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Abstract
Angiotensin (Ang) II exerts its important physiological functions through 2 distinct receptor subtypes, type 1 (AT
1
) and type 2 (AT
2
) receptors. Recently, new evidence has accumulated showing the existence of several novel receptor interacting proteins and various angiotensin II receptor activation mechanisms beyond the classical actions of receptors for Ang II. These associated proteins could contribute not only to Ang II receptors’ functions, but also to influencing pathophysiological states. Receptor dimerization of Ang II receptors such as homodimer, heterodimer, and complex formation with other G protein-coupled receptors has also been focused on as a new mechanism of their activation or inactivation. Moreover, ligand-independent receptor activation systems such as mechanical stretch for the AT
1
receptor have also been revealed. These emerging concepts of regulation of Ang II receptors and a new insight into future drug discovery are discussed in this review.
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MESH Headings
- Adaptor Proteins, Signal Transducing/metabolism
- Angiotensin II/metabolism
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Angiotensin II Type 1 Receptor Blockers/therapeutic use
- Animals
- Antihypertensive Agents/pharmacology
- Antihypertensive Agents/therapeutic use
- Autoantibodies/metabolism
- Dimerization
- Drug Inverse Agonism
- GTP-Binding Proteins/metabolism
- Humans
- Hypertension/drug therapy
- Hypertension/metabolism
- Kruppel-Like Transcription Factors/metabolism
- Ligands
- Membrane Transport Proteins/metabolism
- Multiprotein Complexes/metabolism
- Protein Conformation
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/metabolism
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/drug effects
- Receptor, Angiotensin, Type 1/immunology
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/agonists
- Receptor, Angiotensin, Type 2/chemistry
- Receptor, Angiotensin, Type 2/metabolism
- Signal Transduction/drug effects
- Tumor Suppressor Proteins/metabolism
- Ubiquitin-Conjugating Enzymes/metabolism
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Affiliation(s)
- Masaki Mogi
- FAHA, Professor and Chairman, Department of Molecular Cardiovascular Biology and Pharmacology, Ehime University, Graduate School of Medicine, Shitsukawa, Tohon, Ehime 791-0295, Japan
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13
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Sköld C, Karlén A. Development of CoMFA models of affinity and selectivity to angiotensin II type-1 and type-2 receptors. J Mol Graph Model 2007; 26:145-53. [PMID: 17161636 DOI: 10.1016/j.jmgm.2006.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 09/26/2006] [Accepted: 10/20/2006] [Indexed: 11/28/2022]
Abstract
The renin-angiotensin system (RAS) is of major importance in cardiovascular and renal regulation and has been an attractive target in drug discovery for a long time. The main receptors involved in the RAS are the Angiotensin type-1 (AT(1)) and type-2 (AT(2)) receptors, which are both activated by the endogenous octapeptide angiotensin II (AngII). This study describes the development of 3D-QSAR models for AT(1) and AT(2) receptor affinity and AT(1)/AT(2) receptor selectivity using CoMFA. A data set of 244 compounds, based on the triazolinone and quinazolinone structural classes was compiled from the literature. Before CoMFA could be performed, an alignment rule for the two structural classes was defined using the pharmacophore-searching program DISCOtech. Models were validated using a test set obtained by dividing the data set into a training set and test set using hierarchical clustering, based on the CoMFA fields, AT(1)-, AT(2)-receptor affinities, and AT(1)/AT(2) selectivity values. Predictive models with good statistics could be developed both for AT(1) and AT(2) receptor affinity as well as selectivity towards these receptors.
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MESH Headings
- Angiotensin II Type 1 Receptor Blockers/chemistry
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Angiotensin II Type 2 Receptor Blockers
- Computer Simulation
- Databases, Factual
- Drug Design
- Humans
- In Vitro Techniques
- Ligands
- Models, Molecular
- Quantitative Structure-Activity Relationship
- Receptor, Angiotensin, Type 1/chemistry
- Receptor, Angiotensin, Type 1/drug effects
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/chemistry
- Receptor, Angiotensin, Type 2/drug effects
- Receptor, Angiotensin, Type 2/metabolism
- Renin-Angiotensin System/drug effects
- Software
- Thermodynamics
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Affiliation(s)
- Christian Sköld
- Division of Organic Pharmaceutical Chemistry, Department of Medicinal Chemistry, BMC, Uppsala University, Sweden
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14
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Katsuya T, Ogihara T. [Angiotensin II type 2 receptor gene]. Nihon Rinsho 2006; 64 Suppl 5:445-9. [PMID: 16897880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Affiliation(s)
- Tomohiro Katsuya
- Department of Geriatric Medicine, Osaka University Graduate School of Medicine
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15
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Abstract
1. During the course of studies directed to determine the transport of Angiotensin II AT(2) receptors in the rat brain, we found that stab wounds to the brain revealed a binding site recognized by the AT(2) receptor ligand CGP42112 but not by Angiotensin II. 2. We localized this novel site to macrophages/microglia associated with physical or chemical injuries of the brain. 3. The non-Angiotensin II site was also highly localized to inflammatory lesions of peripheral arteries. 4. In rodent tissues, high binding expression was limited to the spleen and to circulating monocytes. A high-affinity binding site was also characterized in human monocytes. 5. Lack of affinity for many ligands binding to known macrophage receptors indicated the possibility that the non-Angiotensin II CGP42112 binding corresponds to a novel site.6. CGP42112 enhanced cell attachment to fibronectin and collagen and metalloproteinase-9 secretion from human monocytes incubated in serum-free medium but did not promote cytokine secretion. 7. When added in the presence of lipopolysaccharide, CGP42112 reduced the lipopolysaccharide-stimulated secretion of the pro-inflammatory cytokines TNF-alpha, IL-1, IL-1 beta, and IL-6, and increased protein kinase A. 8. Molecular modeling revealed that a CGP42112 derivative was selective for the novel macrophage site and did not recognize the Angiotensin II AT(2) receptor. 9. These results demonstrate that CGP42112, previously considered as a selective Angiotensin II AT(2) ligand, recognizes an additional non-Angiotensin II site different from AT(2) receptors. 10. Our observations indicate that CGP42112 or related molecules could be considered of interest as potential anti-inflammatory compounds.
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Affiliation(s)
- Juan M Saavedra
- Section on Pharmacology, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda 20892, USA.
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16
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Pulakat L, Rahman S, Gray A, Knowle D, Gavini N. Roles of the intracellular regions of angiotensin II receptor AT2 in mediating reduction of intracellular cGMP levels. Cell Signal 2005; 17:395-404. [PMID: 15567070 DOI: 10.1016/j.cellsig.2004.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2004] [Revised: 08/21/2004] [Accepted: 08/23/2004] [Indexed: 02/04/2023]
Abstract
We have shown previously that the angiotensin II (Ang II) receptor AT2 reduces the intracellular levels of cGMP in Xenopus oocytes when activated by ligand binding, and the C-terminal cytoplasmic tail of the AT2 acts as a negative regulator of this function. Here we report the effects of mutations in the 2nd and 3rd intracellular loops of AT2 on AT2-mediated cGMP reduction. Mutating the highly conserved DRY motif (D141G-R142G-Y143A) of the 2nd ICL implicated in activating G(alpha) subunit of trimeric G-proteins did not affect AT2-mediated cGMP reduction. Moreover, anti-Gialpha antibody or phosphodiesterase inhibitor IBMX did not inhibit AT2-mediated cGMP reduction, suggesting that Gialpha activation and subsequent phosphodiesterase activation are not involved in this function. In contrast, mutations T250R-R251N and L255F-K256R located in the C-terminus of the 3rd ICL of AT2 retained ligand-binding properties of the wild-type AT2, and its ability to interact with the ErbB3 in yeast two-hybrid assay, but abolished AT2-mediated cGMP reduction. Similarities in the roles of ICLs of AT2 in AT2-mediated cGMP reduction in oocytes, and AT2-mediated SHP1 activation in COS-7 cells, (need of 3rd ICL for both functions and lack of involvement of DRY motif), suggest that the cascade of events in these two signaling mechanisms could be similar, and that an oocyte-specific SHP1-like protein may be involved in AT2-mediated cGMP reduction in these cells.
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Affiliation(s)
- Lakshmi Pulakat
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA
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17
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Rosenström U, Sköld C, Plouffe B, Beaudry H, Lindeberg G, Botros M, Nyberg F, Wolf G, Karlén A, Gallo-Payet N, Hallberg A. New selective AT2 receptor ligands encompassing a gamma-turn mimetic replacing the amino acid residues 4-5 of angiotensin II act as agonists. J Med Chem 2005; 48:4009-24. [PMID: 15943474 DOI: 10.1021/jm0491492] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
New benzodiazepine-based gamma-turn mimetics with one or two amino acid side chains were synthesized. The gamma-turn mimetics were incorporated into angiotensin II (Ang II) replacing the Val(3)-Tyr(4)-Ile(5) or Tyr(4)-Ile(5) peptide segments. All of the resulting pseudopeptides displayed high AT(2)/AT(1) receptor selectivity and exhibited AT(2) receptor affinity in the low nanomolar range. Molecular modeling was used to investigate whether the compounds binding to the AT(2) receptor could position important structural elements in common areas. A previously described benzodiazepine-based gamma-turn mimetic with high affinity for the AT(2) receptor was also included in the modeling. It was found that the molecules, although being structurally quite different, could adopt the same binding mode/interaction pattern in agreement with the model hypothesis. The pseudopeptides selected for agonist studies were shown to act as AT(2) receptor agonists being able to induce outgrowth of neurite cells, stimulate p42/p44(mapk), and suppress proliferation of PC12 cells.
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18
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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19
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Miura SI, Karnik SS, Saku K. Constitutively Active Homo-oligomeric Angiotensin II Type 2 Receptor Induces Cell Signaling Independent of Receptor Conformation and Ligand Stimulation. J Biol Chem 2005; 280:18237-44. [PMID: 15746093 DOI: 10.1074/jbc.m500639200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the G-protein-coupled receptor superfamily (GPCRs) undergo homo- and/or hetero-oligomerization to induce cell signaling. Although some of these show constitutive activation, it is not clear how such GPCRs undergo homo-oligomerization with transmembrane helix movement. We previously reported that angiotensin II (Ang II) type 2 (AT(2)) receptor, a GPCR, showed constitutive activation and induced apoptosis independent of its ligand, Ang II. In the present study, we analyzed the translocation and oligomerization of the AT(2) receptor with transmembrane movement when the receptor induces cell signaling. Constitutively active homo-oligomerization, which was due to disulfide bonding between Cys(35) in one AT(2) receptor and Cys(290) in another AT(2) receptor, was localized in the cell membrane without Ang II stimulation and induced apoptosis without changes in receptor conformation. These results provide the direct evidence that the constitutively active homo-oligomeric GPCRs by intermolecular interaction in two extracellular loops is translocated to the cell membrane and induces cell signaling independent of receptor conformation and ligand stimulation.
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Affiliation(s)
- Shin-Ichiro Miura
- Department of Cardiology, Fukuoka University School of Medicine, 7-45-1 Nanakuma, Jonan-Ku, Fukuoka, 810-0180, Japan.
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20
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Wruck CJ, Funke-Kaiser H, Pufe T, Kusserow H, Menk M, Schefe JH, Kruse ML, Stoll M, Unger T. Regulation of Transport of the Angiotensin AT2 Receptor by a Novel Membrane-Associated Golgi Protein. Arterioscler Thromb Vasc Biol 2005; 25:57-64. [PMID: 15539617 DOI: 10.1161/01.atv.0000150662.51436.14] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective—
Synthesis and maturation of G protein–coupled receptors are complex events that require an intricate combination of processes including protein folding, posttranslational modifications, and transport through distinct cellular compartments. Little is known concerning the regulation of G protein–coupled receptor transport from the endoplasmic reticulum to the cell surface.
Methods and Results—
Here we show that the cytoplasmatic carboxy-terminal of the angiotensin AT2 receptor (AT2R) acts independently as an endoplasmic reticulum–export signal. Using a yeast two-hybrid system, we identified a Golgi membrane–associated protein termed ATBP50 (for AT2R binding protein of 50 kDa) that binds to this motif. We also cloned ATBP60 and ATBP135 encoded by the same gene as ATBP50 that mapped to chromosomes 8p21.3. Downregulation of ATBP50 using siRNA leads to retention of AT2R in inner compartments, reduced cell surface expression, and decreased antiproliferative effects of the receptor.
Conclusion—
Our results indicate that ATBP50 regulates the transport of the AT2R to cell membrane by binding to a specific motif within its cytoplasmic carboxy-terminal and thereby enabling the antiproliferative effects of the receptor.
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Affiliation(s)
- Christoph J Wruck
- Institute of Pharmacology, University Hospital Schleswig-Holstein, Campus Kiel, Germany.
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21
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Pulakat L, Mandavia CH, Gavini N. Role of Phe308 in the seventh transmembrane domain of the AT2 receptor in ligand binding and signaling. Biochem Biophys Res Commun 2004; 319:1138-43. [PMID: 15194486 DOI: 10.1016/j.bbrc.2004.05.092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Indexed: 11/28/2022]
Abstract
Studies on Angiotensin II (Ang II) receptor type AT1 have suggested that interaction between the two highly conserved residues, Tyr292 in the 7th transmembrane domain (TMD) and the Asp74 in the 2nd TMD, is critical for linking the Ang II binding and AT1 receptor-Gq protein coupling. In the Ang II receptor type AT2, the Asp is conserved (Asp90 in 2nd TMD), however, there is no Tyr residue in the 7th TMD and Phe308 occupies the analogous position to Tyr292 of the AT1. Replacing this Phe308 with Ala reduced receptor affinity to peptidic ligands (125)I-Ang II (K(d) = 0.37 nM) and (125)I-CGP42112A (K(d) = 0.56 nM), but retained the ability of the AT2 to reduce cGMP levels in Xenopus oocytes. Thus, the Phe308 of the AT2 does not mimic the role of Tyr292 of the AT1 in the receptor activation upon Ang II binding. We have also shown that the M8 mutant of the AT2 with the 7th TMD similar to that of wild type AT2 can couple to PLC like the AT1 and bind the AT2-specific ligands with high affinity. Since the Ang II is shown to bind to both the AT1 and the AT2 in an identical manner, we propose that the absence of Tyr in the 7th TMD of the AT2 does not prevent the receptor from coupling to Gq-protein, rather may contribute to the freedom of the AT2 to couple to trimeric G-proteins in both G- betagamma dependent and independent manners upon Ang II binding.
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Affiliation(s)
- Lakshmi Pulakat
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA.
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22
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Nouet S, Amzallag N, Li JM, Louis S, Seitz I, Cui TX, Alleaume AM, Di Benedetto M, Boden C, Masson M, Strosberg AD, Horiuchi M, Couraud PO, Nahmias C. Trans-inactivation of receptor tyrosine kinases by novel angiotensin II AT2 receptor-interacting protein, ATIP. J Biol Chem 2004; 279:28989-97. [PMID: 15123706 DOI: 10.1074/jbc.m403880200] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Negative regulation of mitogenic pathways is a fundamental process that remains poorly characterized. The angiotensin II AT2 receptor is a rare example of a 7-transmembrane domain receptor that negatively cross-talks with receptor tyrosine kinases to inhibit cell growth. In the present study, we report the molecular cloning of a novel protein, ATIP1 (AT2-interacting protein), which interacts with the C-terminal tail of the AT2 receptor, but not with those of other receptors such as angiotensin AT1, bradykinin BK2, and adrenergic beta(2) receptor. ATIP1 defines a family of at least four members that possess the same domain of interaction with the AT2 receptor, contain a large coiled-coil region, and are able to dimerize. Ectopic expression of ATIP1 in eukaryotic cells leads to inhibition of insulin, basic fibroblast growth factor, and epidermal growth factor-induced ERK2 activation and DNA synthesis, and attenuates insulin receptor autophosphorylation, in the same way as the AT2 receptor. The inhibitory effect of ATIP1 requires expression, but not ligand activation, of the AT2 receptor and is further increased in the presence of Ang II, indicating that ATIP1 cooperates with AT2 to transinactivate receptor tyrosine kinases. Our findings therefore identify ATIP1 as a novel early component of growth inhibitory signaling cascade.
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Affiliation(s)
- Sandrine Nouet
- Department of Cell Biology, Institut Cochin, INSERM U567-CNRS UMR8104, 22 rue Méchain, 75014 Paris, France
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23
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Hoe KL, Armando I, Baiardi G, Sreenath T, Kulkarni A, Martínez A, Saavedra JM. Molecular cloning, characterization, and distribution of the gerbil angiotensin II AT2 receptor. Am J Physiol Regul Integr Comp Physiol 2003; 285:R1373-83. [PMID: 14615403 DOI: 10.1152/ajpregu.00008.2003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We isolated a cDNA clone encoding the gerbil AT2 receptor (gAT2) gene from a gerbil adrenal gland cDNA library. The full-length cDNA contains a 1,089-bp open reading frame encoding 363 amino acid residues with 90.9, 96.1, and 95.6% identity with the human (hAT2), rat (rAT2), and mouse AT2 (mAT2) receptors, respectively. There are at least seven nonconserved amino acids in the NH2-terminal domain and in positions Val196, Val217, and Met293, important for angiotensin (ANG) II but not for CGP-42112 binding. Displacement studies in adrenal sections revealed that affinity of the gAT2 receptor was 10-20 times lower for ANG II, ANG III, and PD-123319 than was affinity of the rAT2 receptor. The affinity of each receptor remained the same for CGP-42112. When transfected into COS-7 cells, the gAT2 receptor shows affinity for ANG II that is three times lower than that shown by the hAT2 receptor, whereas affinities for ANG III and the AT2 receptor ligands CGP-42112 and PD-123319 were similar. Autoradiography in sections of the gerbil head showed higher binding in muscles, retina, skin, and molars at embryonic day 19 than at 1 wk of age. In situ hybridization and emulsion autoradiography revealed that at embryonic day 19 the gAT2 receptor mRNA was highly localized to the base of the dental papilla of maxillary and mandibular molars. Our results suggest selective growth-related functions in late gestation and early postnatal periods for the gAT2 receptor and provide an essential basis for future mutagenesis studies to further define structural requirements for agonist binding.
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MESH Headings
- Adrenal Glands/embryology
- Adrenal Glands/physiology
- Amino Acid Sequence
- Animals
- Blotting, Northern
- Blotting, Southern
- COS Cells
- Cloning, Molecular
- Gene Expression Regulation, Developmental
- Gerbillinae
- Head/embryology
- Head/physiology
- In Situ Hybridization
- Male
- Molecular Sequence Data
- Protein Binding
- Protein Structure, Tertiary
- RNA, Messenger/analysis
- Radioligand Assay
- Rats
- Receptor, Angiotensin, Type 2/chemistry
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Species Specificity
- Tooth/embryology
- Tooth/physiology
- Transfection
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Affiliation(s)
- Kwang-Lae Hoe
- Section on Pharmacology, National Institute of Mental Health, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-1514, USA.
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