Intracellular peptides of natriuretic peptide receptor-C inhibit vascular hypertrophy via Gqalpha/MAP kinase signaling pathways.
OBJECTIVE
The present studies were undertaken to investigate if the activation of natriuretic peptide receptor-C (NPR-C) that has been shown to inhibit cell proliferation could also modulate the hypertrophic responses of vasoactive peptides in A10 vascular smooth muscle cells (VSMC).


METHODS
For these studies A10 VSMC were incubated in the presence of angiotensin II (AngII), endothelin (ET-1) or arginine vasopressin (AVP) alone or in combination with C-ANP4-23 or NPR-C peptides for 24 h and were used for Western blotting and [3H]leucine incorporation. The different peptide fragments used were K461KYRITIERRNH472 (peptide-1) and H481RELREDSIRSH492 (peptide-3) with complete Gi activator sequences and R469RNHQEESNIGK480 (peptide-2) and I465TIERRNH472 (peptideY) with partial Gi activator sequences. The other peptide used had no structural specificity, (Q473EESNIGK480; peptide X) or was the scrambled peptide control for peptide-1 (ITIYKKRRNHRE; peptide Z).


RESULTS
AngII, ET-1 and AVP significantly stimulated protein synthesis in these cells as determined by 3H-leucine incorporation, which was inhibited by peptides 1, 2 and 3 and not by peptides X, Y or Z in a concentration-dependent manner with an apparent Ki between 1-10 nM. In addition, C-ANP4-23 also inhibited protein synthesis stimulated by AngII, ET-1 and AVP; whereas basal protein synthesis in these cells was not inhibited by C-ANP4-23 or by the peptide fragments. Furthermore, AngII-, AVP- and ET-1-induced stimulation of protein synthesis was inhibited by PD98059 (MEK inhibitor) and wortmannin (P13K inhibitor) and this inhibition was potentiated by peptide-1. In addition, peptide-1 was also able to inhibit vasoactive peptide-induced phosphorylation of ERK1/2 and AKT and enhanced the expression of Gqalpha protein in these cells.


CONCLUSIONS
These data suggest that C-ANP4-23 and small peptide fragments containing 12 amino acids from different regions of cytoplasmic domain of NPR-C could modulate vasoactive peptide-stimulated protein synthesis through Gqalpha/MAP kinase/P13K and AKT pathways.
Li
Yuan
Y
Department of Physiology, and Groupe de recherche sur le système nerveux autonome, (GRSNA) Faculty of Medicine, University of Montreal, Canada.
Hashim
Shehla
S
Anand-Srivastava
Madhu B
MB
D000730:Androstadienes / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D015153:Blotting, Western / Q000379:methods; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000473:pathology; D010446:Peptide Fragments / Q000494:pharmacology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D013268:Stimulation, Chemical; D000077191:Wortmannin
D000730:Androstadienes; D019332:Endothelin-1; D005419:Flavonoids; D010446:Peptide Fragments; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000804:Angiotensin II; C065367:atrial natriuretic factor (4-23)NH2, de-Gln(18)-de-Ser(19)-de-Gly(20,22)-de-Leu(21)-; D001127:Arginine Vasopressin; D009320:Atrial Natriuretic Factor; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D007930:Leucine; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin