The C-terminal Third Intracellular Loop of the Rat AT1A Angiotensin Receptor Plays a Key Role in G Protein Coupling Specificity and Transduction of the Mitogenic Signal

Conchon, Sophie; Barrault, Marie-Bénédicte; Miserey, Stéphanie; Corvol, Pierre; Clauser, Éric

doi:10.1074/jbc.272.41.25566

Cited by 62 publications

(41 citation statements)

References 46 publications

(44 reference statements)

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“…It is well known that the third intracellular loop of rhodopsin͞adrenergic group I receptors determines G protein coupling selectivity (41)(42)(43). Direct sequence comparisons between members of these two receptor groups, however, reveals no sequence homologies in this region and its importance in the type II family is less well-defined (16).…”

Section: Discussionmentioning

confidence: 99%

Regulation of neuroblast mitosis is determined by PACAP receptor isoform expression

Nicot

DiCicco‐Bloom

2001

Proc. Natl. Acad. Sci. U.S.A.

101

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Although neurogenesis in the embryo proceeds in a region-or lineage-specific fashion coincident with neuropeptide expression, a regulatory role for G protein-coupled receptors (GPCR) remains undefined. Pituitary adenylate cyclase activating polypeptide (PACAP) stimulates sympathetic neuroblast proliferation, whereas the peptide inhibits embryonic cortical precursor mitosis. Here, by using ectopic expression strategies, we show that the opposing mitogenic effects of PACAP are determined by expression of PACAP receptor splice isoforms and differential coupling to the phospholipase C (PLC) pathway, as opposed to differences in cellular context. In embryonic day 14 (E14) cortical precursors transfected with the hop receptor variant, but not cells transfected with the short variant, PACAP activates the PLC pathway, increasing intracellular calcium and eliciting translocation of protein kinase C. Ectopic expression of the hop variant in cortical neuroblasts transforms the antimitotic effect of PACAP into a promitogenic signal. Furthermore, PACAP promitogenic effects required PLC pathway function indicated by antagonist U-73122 studies in hop-transfected cortical cells and native sympathetic neuroblasts. These observations highlight the critical role of lineage-specific expression of GPCR variants in determining mitogenic signaling in neural precursors.

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Section: Discussionmentioning

confidence: 99%

Regulation of neuroblast mitosis is determined by PACAP receptor isoform expression

Nicot

DiCicco‐Bloom

2001

Proc. Natl. Acad. Sci. U.S.A.

101

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“…In addition to activating G protein-dependent second messenger systems, the AT 1a -R also undergoes phosphorylation and rapid internalization after agonist stimulation (29 -32). Substitution of amino acids 234 -240 of the AT 1 -R with the corresponding sequence of the ␤ 2 receptor impaired its internalization kinetics, suggesting that this region has a role in the agonist-induced internalization of the receptor (18). However, alanine substitutions of individual amino acids in the C-terminal region of IL3 did not affect the internalization kinetics of the AT 1 -R, with the exception of the F239A mutation, which reduced the internalization kinetics in a moderate extent.…”

Section: Discussionmentioning

confidence: 99%

“…Studies on the effects of replacing the distal segment of IL3 of the AT 1a -R with the corresponding regions of the ␣ 1 -adrenergic, ␤ 2 -adrenergic, and AT 2 receptors revealed that the RNDDIFR sequence (from Arg 234 to Arg 240 ) of the AT 1a -R has a major role in G protein coupling and receptor signaling (18 markedly attenuated inositol phosphate production. Because the C-terminal region of IL3 is believed to form an extension of the ␣-helical structure of the sixth transmembrane helix, this effect of amino acid deletions could result from changes in the position of Ile 238 relative to the rest of the helix.…”

Section: Discussionmentioning

confidence: 99%

“…Also, the substitution of all charged residues in the C-terminal region of IL3 markedly reduces Ang II-induced inositol phosphate signal generation (17). Furthermore, exchange of this region of the AT 1 -R with the corresponding sequence of the ␤ 2 -adrenergic receptor caused coupling of the receptor to G s as well as G q during agonist stimulation (18). Other studies have demonstrated that a 16-amino acid peptide comprising the N-terminal portion of IL3 of the AT 1 -R stimulates the binding of GTP␥S to G q (19).…”

mentioning

confidence: 99%

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Activation of the AT1 Angiotensin Receptor Is Dependent on Adjacent Apolar Residues in the Carboxyl Terminus of the Third Cytoplasmic Loop

Zhang¹,

Zhao²,

Chen³

et al. 2000

Journal of Biological Chemistry

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The C-terminal region of the third intracellular loop of the AT 1 angiotensin receptor (AT 1 -R) is an important determinant of G protein coupling. The roles of individual residues in agonist-induced activation of G q/11 -dependent phosphoinositide hydrolysis were determined by mutational analysis of the amino acids in this region. Functional studies on mutant receptors transiently expressed in COS-7 cells showed that alanine substitutions of the amino acids in positions 232-240 of the third loop had no major effect on signal generation. as the critical residues in the C-terminal region of the third intracellular loop of the AT 1 -R for receptor activation. They also suggest that an apolar amino acid corresponding to Ile 238 of the AT 1 -R is a general requirement for activation of other G protein-coupled receptors by their agonist ligands.The AT 1 angiotensin receptor (AT 1 -R) 1 is a member of the GPCR superfamily and mediates the physiological actions of the octapeptide hormone, Ang II, on cardiovascular regulation and salt/water balance. The binding of Ang II to the AT 1 -R initiates conformational changes that lead to activation of its cognate G protein(s), predominantly G q/11 , in numerous Ang II target tissues. The subsequent stimulation of phospholipase C causes the generation of inositol 1,4,5-trisphosphate and diacylglycerol, leading to the elevation of [Ca 2ϩ ] and activation of protein kinase C (1-3). The AT 1 -R is also coupled to other signaling pathways, including the Ras-mediated activation of mitogen-activated protein kinase and cell growth responses (4, 5).Although GPCRs exhibit a remarkable degree of structural and functional diversity, all share a common architecture in which seven transmembrane helices are linked by alternating intracellular and extracellular loops. Agonist binding to the extracellular loops, and/or the exofacial regions of the transmembrane domains, induces conformational changes in the transmembrane helices and intracellular regions that promote coupling of the activated receptor to its cognate G protein(s). The receptor domains that are involved in G protein coupling have been analyzed in many GPCRs. Studies using chimeric ␣ 2 /␤ 2 -, ␣ 1B /␣ 2 -, and ␣ 1/ ␤ 2 -adrenergic receptors and chimeric M 2 /M 3 muscarinic receptors have shown that modification of IL3 influences G protein selectivity, suggesting that IL3 has a critical role in receptor-G protein interaction (6 -9). The importance of the C-terminal portion of IL3 in receptor conformation has been further indicated by the ability of mutations of specific residues in this region to cause constitutive activation of several adrenergic receptors (6 -8).Studies on spin-labeled double cysteine mutants of rhodopsin have indicated that rigid body motion of helix VI compared with helix VII is an important event in receptor activation (10) and that movement of the C-terminal region of IL3 occurs in constitutively active receptors (11). In the ␤ 2 -adrenergic receptor, substitution of the C-terminal region of IL3 with those...

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“…N-e C-terminais da i3 (198,199). Estudos de mutagênese mostraram que os resíduos 219 a 225 no N-terminal da i3 (Ni3) do receptor AT IA é importante para o acoplamento com a proteína G (199).…”

Section: Interação Com a Proteína Gunclassified

Estudos conformacionais de seqüências hidrofóbicas de domínios de receptores acoplados a proteínas G (GPCR) e da proteína G. Um estudo de CD e espectroscopia de fluorescência

Casallanovo¹

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AgradecimentosAo pessoal do laboratório, Salay, Felipe, Myriam, Fábio Dyszy, Tatiana e Marcelo, obrigado pela paciência e pela ajuda. À Aninha, obrigado pelos papos, discussões e pelo apoio.Ao Carlos Àlvares, que me ajudou muito nos momentos finais.Ao pessoal que passou pelo LBE, Raquel, Berê, Noboru, Roberto Salinas, Goretti, Thelma e Mercedes.Ã Renata Fischer, pela amizade.Ao Claúdio S. Shida, que me ajudou muito em vários momentos, obrigado pelos conselhos e pela amizade.Aos meus amigos Eroc, Paulo, Luís Mayer e Luiz, obrigado pelo apoio e por me agüentar nos momentos mais dificeis.À Lua, que é uma pessoa que eu gosto muito e com a qual tive uma ótima amizade desde o primeiro dia em que entrei no laboratório como aluno de iniciação científica. Obrigado pelos conselhos e pelos momentos de alegria. À Dra. Shirley, que é uma pessoa muito especial. Poucas pessoas sabem contar estórias e atrair a admiração dos outros como você. Com você aprendi muito, sempre admirei sua postura e inteligência. Você também soube ser muito compreensiva nos momentos mais dificeis.À Fapesp e ao CNPq, obrigado pelo apoio finaceiro.o. Índice 1 Índice Lista de abreviações .................................................................................................................................... iv Resumo ........................................................................................................................................................ v O peptídeo estudado mostrou-se muito sensível à força iônica, pH e TFE, observando-se mudança de estrutura ao acaso para a-hélice em alguns pHs e na presença de TFE e para folha ~ com o aumento da força iônica.Na presença de detergentes, observou-se que o peptídeo era capaz de ligar-se tanto a interfaces com carga líquida zero (HPS e LPC) quanto com carga líquida negativa. Observou-se também que o CG tem maior afinidade por LPC do que por HPS.O estudo do CG em diferentes condições forneceu subsídios para investigannos a interação deste fragmento com regiões do receptor A TIA de angiotensina 11 que estão envolvidas com a ativação da proteína G. analog displayed the highest propensity to acquire a-helical conformation in the presence of TFE and in aqueous solution.In the presence of detergents we observed that the peptides were able to bind to different interfaces, especially negatively charged ones. In the presence of phospholipid membranes, all peptides displayed p-sheet conformation.In order to study the effect of aggregation, we performed experiments in the presence of denaturing agents such as urea and as a function of temperature. Even in the presence of high urea concentrations and at higher temperatures, the fragments remained aggregated. This result led us to another approach, where peptide films were hydrated in the presence of detergents. Using this methodology it was observed that the fragments were less aggregated, indicating that under adequate conditions the peptides tend to adopt a-helical conformation. In summary, it was possible to observe experimentall...

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The C-terminal Third Intracellular Loop of the Rat AT1A Angiotensin Receptor Plays a Key Role in G Protein Coupling Specificity and Transduction of the Mitogenic Signal

Cited by 62 publications

References 46 publications

Regulation of neuroblast mitosis is determined by PACAP receptor isoform expression

Regulation of neuroblast mitosis is determined by PACAP receptor isoform expression

Activation of the AT1 Angiotensin Receptor Is Dependent on Adjacent Apolar Residues in the Carboxyl Terminus of the Third Cytoplasmic Loop

Estudos conformacionais de seqüências hidrofóbicas de domínios de receptores acoplados a proteínas G (GPCR) e da proteína G. Um estudo de CD e espectroscopia de fluorescência

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