Stabilization of blood platelet microtubular system by staurosporine

The stimulative effects of phorbol myristate acetate (PMA) on rabbit platelet shape change and platelet adhesion were completely inhibited by staurosporine (STS)-pretreatment. When the platelets were observed by whole mount immuno transmission electron microscopy (TEM), STS was found to stabilize platelet microtubular cytoskeleton. Electrophoretic analysis of the isolated marginal bundles of cytoskeleton after STS-PMA treatment revealed a newly formed 200 K high molecular weight protein band accompanied with heavy losses of tubulin monomers. These bundles of STS-treated platelets as observed in immuno TEM responded poorly to the anti alpha- or beta-tubulin antibody as compared with those of the control platelets. The results suggest that sts favour the specific assembly of tubulin bundles with a possible involvement of the microtubular associated proteins (MAPs). The resultant tight marginal bundles (MB) of cytoskeleton will stabilize the platelets and resist the effects of exogeneously added stimulants such as PMA.