Rho signaling pathway enhances proliferation of PASMCs by suppressing nuclear translocation of Smad1 in PAH

Hongwei Wei; Dongqing Zhang; Lili Liu; Wei Xia; Fuhai Li

doi:10.3892/etm.2018.6942

Rho signaling pathway enhances proliferation of PASMCs by suppressing nuclear translocation of Smad1 in PAH

Exp Ther Med. 2019 Jan;17(1):71-78. doi: 10.3892/etm.2018.6942. Epub 2018 Nov 8.

Authors

Hongwei Wei¹, Dongqing Zhang², Lili Liu², Wei Xia², Fuhai Li²

Affiliations

¹ Department of Pediatrics, The Third Hospital of Jinan, Jinan, Shandong 250132, P.R. China.
² Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China.

Abstract

Bone morphogenetic protein (BMP) and Rho kinase signaling pathways exert counter regulatory effects on pulmonary artery smooth muscle cell (PASMC) proliferation in pulmonary artery hypertension (PAH). To elucidate the mechanism of this interaction, the present study tested whether Rho kinase activated by platelet derived growth factor-BB (PDGF-BB) enhances PASMC proliferation by suppressing the nuclear translocation of Smad1 induced by BMP-2. BMP-2 was used to activate the Smad1 signaling pathway and PDGF-BB was used to activate the Rho kinase signaling pathway when cells were pretreated with or without Rho-associated protein kinase (ROCK) inhibitor Y-27632 or dual specificity mitogen-activated protein kinase kinase (MEK) 1 and 2 inhibitor U0126. Western blotting was used to determine the expression of the components of the Rho signaling pathway, and the expression of various variants of phosphorylated mothers against decapentaplegic homolog (p-Smad)1 in the cytoplasm and nucleus. Immunofluorescent staining was used to observe subcellular distribution of p-Smad1. A cell counting kit was used to analyze cell proliferation. Active RhoA/Rho kinase signaling and decreased nuclear translocation of Smad1 were found in primary cultured PASMCs from the rat model of PAH compared with the control PASMCs. Treatment with BMP-2 significantly increased nuclear accumulation of Smad1 and inhibited the proliferation of PASMCs. However, pretreatment with PDGF-BB significantly decreased the nuclear accumulation of Smad1 induced by BMP-2 and enhanced the proliferation of PASMCs. Furthermore, pretreatment with Y-27632 or U0126 was found to restore the nuclear translocation of Smad1 suppressed by PDGF-BB and decrease the proliferation of PASMCs. In conclusion, the present study suggested that Rho kinase activated by PDGF-BB suppressed BMP-2-induced nuclear translocation of Smad1 via the MEK/mitogen-activated protein kinase and enhanced BMP-2-inhibited proliferation of PASMCs.

Keywords: Rho signaling; bone morphogenetic protein 2; mothers against decapentaplegic homolog 1; pulmonary artery hypertension; pulmonary artery smooth muscle cell.