Urotensin II contributes to collagen synthesis and up-regulates Egr-1 expression in cultured pulmonary arterial smooth muscle cells through the ERK1/2 pathway

Abstract

AimThe objective of this study was to investigate the effects of urotensin II (UII) treatment on the proliferation and collagen synthesis of cultured rat pulmonary arterial smooth muscle cells (PASMCs) and to explore whether these effects are mediated by mitogen-activated protein kinase (MAPK) signaling pathways and early growth response 1 (Egr-1). MethodsThe proliferation of cultured PASMCs stimulated with different doses of UII was detected by BrdU incorporation. The mRNA expression levels of procollagen I (procol I), procollagen III (procol III), extracellular regulated protein kinase 1/2 (ERK1/2), stress-stimulated protein kinase (Sapk), p38 MAPK (p38), and Egr-1 mRNA in cultured PASMCs after treatment with UII, the UII-specific antagonist urantide, and the ERK1/2 inhibitor PD98059 were detected by real-time polymerase chain reaction (PCR), and the protein expression levels of procol I, procol III, phosphorylated (p)-ERK1/2, p-Sapk, p-p38, and Egr-1 were detected by Western blotting. ResultsTreatment with UII increased the proliferation of cultured PASMCs in a dose-dependent manner (P<0.05). However, treatment with urantide and PD98059 inhibited the promoting effect of UII on PASMC proliferation (P<0.05). Real-time PCR analysis showed that UII up-regulated the expression of procol I, procol III, ERK1/2, Sapk, and Egr-1 mRNA (P<0.05), but not p38 mRNA. However, the up-regulating effect of UII was inhibited by PD98059 and urantide. Western blotting analysis showed that UII increased the synthesis of collagen I, collagen III, p-ERK1/2, p-Sapk, and Egr-1, and these effects also were inhibited by PD98059 and urantide (P<0.05). ConclusionsEgr-1 participates in the UII-mediated proliferation and collagen synthesis of cultured rat PASMCs via activation of the ERK1/2 signaling pathway.