Cap G, a gelsolin family protein modulating protective effects of unidirectional shear stress

Atherosclerosis is a progressive and complex pathophysiological process occurring in large arteries. Although it is of multifactorial origin, the disease develops at preferential sites along the vasculature in regions experiencing specific hemodynamic conditions that are predisposed to endothelial dysfunction. The exact mechanisms allowing endothelial cells to discriminate between plaque-free and plaque-prone flows remain to be explored. To investigate such mechanisms, we performed a proteomic analysis on endothelial cells exposed in vitro to these two-flow patterns. A few spots on the two-dimensional gel had an intensity that was differentially regulated by plaque-free versus plaque-prone flows. One of them was further investigated and identified as macrophage-capping protein (Cap G), a member of the gelsolin protein superfamily. A 2-fold increase of Cap G protein and a 5-fold increase of Cap G mRNA were observed in cells exposed to a plaque-free flow as compared with static cultures. This increase was not observed in cells exposed to plaque-prone flow. Plaque-free flow induced a corresponding increase in nuclear and cytoskeletal-associated Cap G. Finally, overexpression of Cap G in transfection assays increased the motility potential of endothelial cells. These observations together with the known functions of Cap G suggest that Cap G may contribute to the protective effect exerted by plaque-free flow on endothelial cells. On the contrary, in cells exposed to a plaque-prone flow, no induction of Cap G expression could be observed.