title: Modulation of ANP-C receptor signaling by arginine-vasopressin in A-10 vascular smooth muscle cells: role of protein kinase C.
abstract: We have previously shown that pretreatment of A-10 vascular smooth muscle cells (VSMC) with angiotensin II (Ang II) attenuated atrial natriuretic peptide receptor-C (ANP-C)-mediated inhibition of adenylyl cyclase without altering [125I]ANP binding. In the present studies, we have investigated the modulation of ANP-C receptor signaling by arginine-vasopressin (AVP). Pretreatment of A-10 VSMC with AVP for 24h resulted in a reduction in ANP receptor binding activity by about 50% (B(max); control cells, 22.9+/-2.5 fmol/mg protein, AVP-treated cells, 11.4+/-1.2 fmol/mg protein). In addition, the expression of ANP-C receptor as determined by immunoblotting was also decreased by about 50% by AVP treatment, which was prevented by GF109203X, an inhibitor of protein kinase C (PKC). The decreased expression of ANP-C receptor was reflected in an attenuation of ANP-C receptor-mediated inhibition of adenylyl cyclase. C-ANP(4-23) [des(Gln(18),Ser(19),Gln(20),Leu(21),Gly(22))ANP(4-23)-NH(2)], a ring deleted peptide of ANP that interacts specifically with ANP-C receptor, inhibited adenylyl cyclase activity by about 30% in control cells, which was completely attenuated in AVP-treated cells. This attenuated inhibition was significantly restored by GF 109203X. In addition, AVP treatment augmented the levels of Gialpha-2 and Gialpha-3 proteins; however, the Gi functions were completely attenuated. The increased expression of Gialpha proteins induced by AVP was inhibited by GF109203X as well as by actinomycin D treatments. In addition, AVP treatment also enhanced the expression of Gsalpha protein and Gsalpha-mediated stimulation of adenylyl cyclase by GTPgammaS, N-ethylcarboxamide adenosine (NECA), and forskolin (FSK), whereas the levels of Gbeta were not altered by AVP treatment. These results indicate that AVP-induced PKC signaling may be responsible for the down-regulation of ANP-C receptor that results in the attenuation of C-ANP(4-23)-mediated inhibition of adenylyl cyclase activity, and suggest a cross-talk between vasopressin V(1) and ANP-C receptor-mediated signaling pathways.
authors.affiliation: Département de Physiologie et Groupe de recherche sur le Système Nerveux Autonome, Université de Montréal, CP 6128 Succursale Centre-Ville, Montreal, Que, Canada H3C 3J7.
authors.forename: Malika
authors.initials: M
authors.lastname: Boumati
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.forename: Madhu B
authors.initials: MB
authors.lastname: Anand-Srivastava
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000378:metabolism; D006162:Guanylate Cyclase / Q000096:biosynthesis / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor / Q000096:biosynthesis / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D001127:Arginine Vasopressin; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C073616:atrial natriuretic factor receptor C