Inhibitory effect of calcitonin gene-related peptide on hypoxia-induced rat pulmonary artery smooth muscle cells proliferation: role of ERK1/2 and p27.
Calcitonin gene-related peptide (CGRP) inhibits angiotensin II-induced proliferation of aortic smooth muscle cells via inactivation of extracellular signal-regulated protein kinase 1/2 (ERK1/2). ERK1/2 is necessary for the degradation or down-regulation of the cell cycle inhibitor p27, and is also crucial in mediating proliferation of pulmonary artery smooth muscle cells (PASMCs). Whether ERK1/2/p27 signal pathway is involved in CGRP-mediated pathogenesis of pulmonary hypertension and vascular remodeling remains unknown. Pulmonary hypertension was induced by hypoxia in rats, and capsaicin (50 mg/kg, s.c.) was used to deplete endogenous CGRP. Proliferation of cultured PASMCs was determined by BrdU incorporation method and flow cytometry. The expression/level of CGRP, p27, ERK1/2, c-fos and c-myc was analyzed by radioimmunoassay, immunohistochemistry, real-time PCR or Western blot. Sensory CGRP depletion by capsaicin exacerbated hypoxia-induced pulmonary hypertension in rats, as shown by an increase in right ventricle systolic pressure, mean pulmonary artery pressure and vascular hypertrophy, accompanied with decreased p27 expression and increased expression of phosphorylated ERK1/2, c-fos and c-myc. Exogenous application of CGRP significantly inhibited hypoxia-induced proliferation of PASMCs concomitantly with increased p27 expression and decreased expression of phosphorylated ERK1/2, c-fos and c-myc. These effects of CGRP were abolished in the presence of CGRP(8-37). Knockdown of p27 also reversed the inhibitory effect of CGRP on proliferation of PASMCs and expression of c-fos and c-myc, but not on ERK1/2 phosphorylation. These results suggest that CGRP inhibits hypoxia-induced proliferation of PASMCs via ERK1/2/p27/c-fos/c-myc pathway. Down-regulation of CGRP may contribute to remodeling of pulmonary arteries in hypoxia-induced pulmonary hypertension.
Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
Xian-Wei
XW
Li
Chang-Ping
CP
Hu
Wei-Hua
WH
Wu
Wei-Fang
WF
Zhang
Xiao-Zhou
XZ
Zou
Yuan-Jian
YJ
Li
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000187:drug effects / Q000494:pharmacology / Q000502:physiology*; D002211:Capsaicin / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000096:biosynthesis / Q000235:genetics; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques / Q000379:methods; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D000860:Hypoxia; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology; D010766:Phosphorylation; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis; D011651:Pulmonary Artery / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D010446:Peptide Fragments; D016760:Proto-Oncogene Proteins c-fos; D016271:Proto-Oncogene Proteins c-myc; C058636:calcitonin gene-related peptide (8-37); D050760:Cyclin-Dependent Kinase Inhibitor p27; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin