BMPs enhance KCNK3 expression in HPASMCs via the BMPR2- Smad1/5 signaling pathway. (A, B) BMP2, BMP4, and BMP7 increased KCNK3 expression in HPASMCs. Cells were treated with BMPs (30 ng/ml) in growth media for 48 h and harvested for RT-PCR and western blot analyses. mRNA (A) and protein (B) levels of KCNK3 were analyzed relative to those in untreated controls (Cont) (triplicate experiments). (C) SiRNA-mediated BMPR2 knockdown blocked BMP-induced increase in KCNK3 expression in HPASMCs. SiRNA-transfected and non-transfected cells were treated with or without BMPs (30 ng/ml) in growth media for 48 h and harvested for real-time RT-qPCR. KCNK3 mRNA levels were measured relative to those in untreated Cont (n = 4). (D) Inhibition of Smad signaling blocked BMP-induced KCNK3 expression in HPASMCs. Cells were pre-treated with LDN193189 (LDN, 2.5 μM) and incubated with BMPs (30 ng/ml) in growth media for 48 h and analyzed using western blotting assay (triplicate experiments). Data are presented as mean ± SEM (*P < 0.05, **P < 0.01, ***P < 0.001 vs. Cont).