Objective: Deletion of the mitochondrial gene p66(Shc) protects from endothelial dysfunction and atherosclerotic plaque formation in mice fed a high-fat diet. However, the molecular mechanisms underlying this beneficial effect have not yet been delineated. The present study was designed to elucidate the proatherogenic mechanisms by which p66(Shc) mediates oxidized low-density lipoprotein (oxLDL) uptake by the endothelium, a critical step in plaque formation.
Methods and results: Incubation of human aortic endothelial cells with oxLDL led to phosphorylation of p66(Shc) at Ser36. Inhibition of lectin-like oxLDL receptor-1 prevented p66(Shc) phosphorylation, confirming that this effect is mediated by lectin-like oxLDL receptor-1. OxLDL also increased phosphorylation of protein kinase C β(2) (PKCβ(2)) at both Thr641 and Ser660, as well as c-Jun N-terminal kinase (JNK). Furthermore, inhibition of PKCβ(2) prevented the activation of JNK, suggesting that PKCβ2 is upstream of JNK. Finally, p66(Shc) silencing blunted oxLDL-induced O(2)(-·) production, underscoring the critical role of p66(Shc) in oxLDL-induced oxidative stress in endothelial cells.
Conclusions: In this study we provide the molecular mechanisms mediating the previously observed atherogenic properties of p66(Shc). Taken together, our data set the stage for the design of novel therapeutic tools to retard atherogenesis through the inhibition of p66(Shc).