Down-regulation of myosin light chain kinase expression in vascular smooth muscle cells accelerates cell proliferation: Requirement of its actin-binding domain for reversion to normal rates

Myosin light-chain kinase (mlck) is a multi-domain protein with kinase and actin-binding domains,among others. deficiency of mlck expression in gbasm-4 vascular smooth muscle cells enhanced cell proliferation rate and shortened cell doubling time. transient transfection of the mlck-deficient cells with cdna constructs of either wild-type mlck or its mutant lacking the kinase activity reverted the cell proliferation rate to that of wild-type cells,whereas that of mlck lacking the actin-binding domain maintained cell proliferation at an elevated rate similar to the mlck-deficient cells. thus,the actin-binding domain of mlck seems to play a role in regulating cell proliferation. © the japanese pharmacological society.