Data for "S100A4 is activated by RhoA and catalyzesthe polymerization of non-muscle myosin, adhesion complex assembly and contraction in airway smooth muscle"

Abstract

S100A4 binds to the heavy chain of non-muscle (NM) myosin II and can regulate the motility of crawling cells. S100A4 is widely expressed in many tissues including smooth muscle (SM), but its role in regulating their physiologic function is not known. We hypothesized that S100A4 contributes to the regulation of contraction in airway SM by regulating a pool of NM myosin II at the cell cortex. NM myosin II undergoes polymerization in airway SM and regulates contraction by catalyzing the assembly of integrin-associated adhesome complexes that activate pathways that catalyzeactin polymerization. Acetylcholine (ACh) stimulated the interaction of S100A4 with NM myosin II in airway SM at the cell cortex and catalyzed NM myosin filament assembly. RhoA GTPase regulated the activation of S100A4 via rhotekin, which facilitated the formation of a complex between RhoA, S100A4 and NM myosin II. The depletion of S100A4, RhoA or rhotekin from airway SM tissues using shRNA or siRNA prevented NM myosin II polymerization, the recruitment of vinculin and paxillin to adhesome signaling complexes in response to ACh, and inhibited actin polymerization and tension development. S100A4 depletion did not affect ACh-stimulated SM myosin RLC phosphorylation. Results show that S100A4 plays a critical role in tension development in airway SM tissue by catalyzing NM myosin filament assembly, and that the interaction of S100A4 with NM myosin in response to contractile stimulation is activated by RhoA GTPase. These results may be broadly relevant to the physiologic function of S100A4 in other cell and tissue types.