Effect of the BMPR-II-SMAD3/MRTF complex on proliferation and migration of ASMCs and the mechanism in asthma.

Phenotype transformation of airway smooth muscle (ASM) is the key feature of airway remodelling in asthma. A variety of smooth muscle-specific genes and proteins, including SMAD3, BMPR-II, and MRTF, are involved in airway remodelling in asthma. Bone morphogenetic protein (BMP) signalling plays an important role in the physiological and pathological processes of asthma. As a receptor of BMP signalling, BMPR-II has important roles in variety of cellular processes. However, the understanding of the roles and underlying mechanism of BMPR-II in airway smooth muscle cells (ASMCs) in asthma remains incomplete. First, we observed significant increases in BMPR-II, SMAD3 and MRTF in asthmatic ASMCs at both the mRNA and protein levels. Second, we observed that silencing of siBMPR-II and siMRTF inhibits proliferation, migratory capacity and intracellular Ca2+ concentration in ASMCs. Furthermore, our results revealed these three factors, BMPR-II, SMAD3 and MRTF, form a complex that affects the bioactivities of ASMCs. Taken together, this study indicates that the BMPR-II-SMAD3/MRTF signalling pathway is involved in the process of ASM remodelling, providing novel avenues for the identification of new therapeutic modalities.