Glucocorticoid effect on human mesangial cell cytoskeletal proteins

In human mesangial cells (HMCs), we assessed the effect of dexamethasone on the expression and levels of tyrosine phosphorylation of two cytoskeleton-associated proteins: focal adhesion kinase (FAK) and paxillin. Dexamethasone, 10(-7) mol/L, increased levels of tyrosine phosphorylation of both proteins within 15 to 30 minutes without a change in protein levels. The exposure of HMCs to cytochalasin B, a disrupter of the cytoskeleton assembly, reduced basal tyrosine phosphorylation of both proteins. This effect was reversed by dexamethasone. These observations support a stabilizing effect of dexamethasone on the mesangial cell cytoskeleton. This may constitute a cytoprotective mechanism in the context of the anti-inflammatory action of the steroids in various glomerulopathies.