Abstract
Background It has been indicated that protein kinase C (PKC) plays a vital role in the pathogenesis of hypoxia-induced pulmonary hypertension (PH). The functions or the pathogenic roles of PKCs vary from different types, and their related downstream pathways may also be distinct. Therefore, the specific role of different types of PKC deserves to be elucidated. Discussions regarding conventional PKC (cPKC) have dominated research in recent years, however, the relationship between novel PKC (nPKC) and the development of PH remain unclear. In addition, it is less known whether nPKC has a direct effect on the proliferation of pulmonary artery smooth muscle cells (PASMCs). This study is designed to investigate the role of nPKC in mediating PASMCs proliferation in PH and the underlying mechanisms. Methods Mouse PASMCs was isolated using magnetic separation technology. The PASMCs were divided into 24 h group, 48 h group and 72 h group according to different hypoxia treatment time, then detected cell proliferation rate and nPKC expression level in each group. We treated PASMCs with agonists or inhibitors of PKCδ and PKCε and exposed them to hypoxia or normoxia for 72 h, then measured the proliferation of PASMCs. We also constructed a lentiviral vector containing siRNA fragments for inhibiting PKCδ and PKCε to transfected PASMCs, then examined their proliferation. Results PASMCs isolated successfully by magnetic separation method and were in good condition. Hypoxia promoted the proliferation of PASMCs, and the treatment for 72 h had the most significant effect. Hypoxia upregulated the expression of PKCδ and PKCε in mouse PASMCs, leading to PASMCs proliferation. Moreover, Our study demonstrated that hypoxia induced upregulation of PKCδ and PKCε expression resulting to the proliferation of PASMCs via up-regulating the phosphorylation of AKT and ERK. Conclusions Our study provides clear evidence that increased nPKC expression contributes to PASMCs proliferation and uncovers the correlation between AKT and ERK pathways and nPKC-mediated proliferation of PASMCs. These findings may provide novel targets for molecular therapy of pulmonary hypertension.
