title: Potent and selective inhibition of angiotensin AT1 receptor signaling by RGS2: roles of its N-terminal domain.
abstract: Emerging evidence indicates that R4/B subfamily RGS (regulator of G protein signaling) proteins play roles in functional regulation in the cardiovascular system. In this study, we compared effects of three R4/B subfamily proteins, RGS2, RGS4 and RGS5 on angiotensin AT1 receptor signaling, and investigated roles of the N-terminus of RGS2. In HEK293T cells expressing AT1 receptor stably, intracellular Ca(2+) responses induced by angiotensin II were much more strongly attenuated by RGS2 than by RGS4 and RGS5. N-terminally deleted RGS2 proteins lost this potent inhibitory effect. Replacement of the N-terminal residues 1-71 of RGS2 with the corresponding residues (1-51) of RGS5 decreased significantly the inhibitory effect. On the other hand, replacement of the residues 1-51 of RGS5 with the residues 1-71 of RGS2 increased the inhibitory effect dramatically. Furthermore, we investigated functional contribution of N-terminal subdomains of RGS2, namely, an N-terminal region (residues 16-55) with an amphipathic α helix domain (the subdomain N1), a probable non-specific membrane-targeting subdomain, and another region (residues 56-71) between the α helix and the RGS box (the subdomain N2), a probable GPCR-recognizing subdomain. RGS2 chimera proteins with the residues 1-33 or 34-52 of RGS5 showed weak inhibitory activity, and either of RGS5 chimera proteins with residues 1-55 or 56-71 of RGS2 showed strong inhibitory effects on AT1 receptor signaling. The present study indicates the essential roles of both N-terminal subdomains for the potent inhibitory activity of RGS2 on AT1 receptor signaling.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Matsuzaki
authors.forename: Mariko
authors.initials: M
authors.lastname: Nishiyama
authors.forename: Dan
authors.initials: D
authors.lastname: Song
authors.forename: Kayoko
authors.initials: K
authors.lastname: Moroi
authors.forename: Sadao
authors.initials: S
authors.lastname: Kimura
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D019332:Endothelin-1 / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020710:RGS Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism*; D017466:Receptors, Endothelin / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D019332:Endothelin-1; D020710:RGS Proteins; C087182:RGS2 protein, human; D044140:Receptor, Angiotensin, Type 1; D017466:Receptors, Endothelin; D011993:Recombinant Fusion Proteins; D000804:Angiotensin II; D002118:Calcium