Claudin-1 Promotes Pulmonary Artery Smooth Muscle Cell Proliferation Through The Activation Of ERK1/2

BackgroundPulmonary arterial hypertension(PAH)is characterized by enhanced proliferation of pulmonary artery smooth muscle cells(PASMCs).Tumor necrosis factor-alpha(TNF-a)is an important proinflammatory cytokine involved in PAH development.TNF-α can induce the expression of claudin-1(CLDN1)in a variety of cells and CLDN1 has been reported to participate in the regulation of cell proliferation.Thus,we hypothesized that CLDN1 might be implicated in the etiology of pulmonary arterial remodeling and PAH.MethodsCLDN1 expression in the lungs of rats with monocrotaline(MCT)-induced PAH and patients with PAH was evaluated by means of Western blot and Immunofluorescence staining.Primary human PASMCs were pretreated with the Nuclear factor-KB(NF-κB)inhibitor BAY 11-7082 and stimulated with TNF-a,and then analyzed for CLDN1 expression.We investigated the effect of CLDN1 on the proliferation of PASMC through adenoviral infection and small interfering RNA(siRNA)transfection.Cell proliferation was determined by using cck-8 and BrdU incorporation assay.ERK1/2 phosphorylation was determined by western blot analysis.ResultsIncreased CLDN1 expression was observed in pulmonary artery smooth muscle(PASM)sections of rats with MCT-induced PAH,as well as patients with PAH.The expression of CLDN1 in primary human PASMCs was up-regulated by TNF-α,while the NF-κB inhibitor BAY 11-7082 suppressed TNF-α-induced CLDN1 expression.Overexpression of CLDN1 by adenoviral infection promoted PASMC proliferation,while silencing of CLDN1 by siRNA transfection inhibited TNF-α-induced cell proliferation.In addition,CLDN1 promoted PASMC proliferation through the activation of ERK1/2.ConclusionsOur data suggested that CLDN1 may play a critical role in pulmonary arterial remodeling in patients with PAH by means of regulation of PASMC proliferation.