NMMHC IIA inhibition impedes tissue factor expression and venous thrombosis via Akt/GSK3β-NF-κB signalling pathways in the endothelium

Non-muscle myosin heavy chain IIA (NMMHC IIA) has been shown to be involved in thrombus formation and inflammatory microparticle re, lease in endothelial cells. However, the role of NMMHC IIA in regulating the expression of tissue factor (IF) and deep venous thrombosis remains to be elucidated. In the present study, endothelial cells were stimulated with tumour necrosis factor-alpha (TNF-alpha) to induce TF expression. Pretreatment with the NMMHC II inhibitor blebbistatin suppressed the mRNA and protein expressions as well as the procoagulant activity of IF in a dose-dependent manner. Blebbistatin enhanced Akt and GSK3 beta phosphorylation and inhibited NF-kappa B p65 nuclear translocation and I kappa B? degradation. These observations were similar to the effect of CHIR99021, a GSK3 beta inhibitor. TF downregulation by blebbistatin was antagonised by the PI3K inhibitor, wortmannin. Furthermore, siRNA knockdown of NMMHC IIA, but not IIB or IIC, inhibited TF expression, activated Akt/GSK3 beta and suppressed NF-kappa B signailing pathways, whereas the overexpression of NMMHC IIA increased TF expression. The binding of NMMHC IIA and TNF receptor 2 mediated signal internalisation in TNF-alpha-stimulated endothelial cells. Importantly, blebbistatin decreased endothelium NMMHC IIA and IF expression, deactivated GSK3 beta by inducing its phosphorylation, suppressed p65 nuclear translocation, and inhibited thrombus formation in a mouse deep venous thrombosis model. Our findings provide solid evidence that inhibition of NMMHC II, most likely NMMHC IIA, impedes IF expression and venous thrombosis via Akt/GSK3 beta-NF-kappa B signalling pathways in the endothelium both in vitro and in vivo. NMMHC IIA might be a potential novel target for the treatment of thrombotic disorders.