Receptor-selective effects of endogenous RGS3 and RGS5 to regulate mitogen-activated protein kinase activation in rat vascular smooth muscle cells.
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.
Wang
Qin
Q
Department of Pharmacology, the University of Michigan, Ann Arbor 48109-0632, USA.
Liu
Min
M
Mullah
Bashar
B
Siderovski
David P
DP
Neubig
Richard R
RR
D000818:Animals; D001483:Base Sequence; D002384:Catalysis; D017931:DNA Primers; D004789:Enzyme Activation; D019204:GTP-Binding Proteins; D020690:GTPase-Activating Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D037342:Pertussis Toxin; D020710:RGS Proteins / Q000235:genetics / Q000502:physiology*; D016337:RNA, Catalytic / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011945:Receptors, Angiotensin / Q000378:metabolism*; D012097:Repressor Proteins; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D017931:DNA Primers; D020690:GTPase-Activating Proteins; D020710:RGS Proteins; D016337:RNA, Catalytic; D012333:RNA, Messenger; D011945:Receptors, Angiotensin; D012097:Repressor Proteins; C415085:Rgs3 protein, mouse; C437714:Rgs3 protein, rat; C491348:Rgs5 protein, rat; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins