P66Shc-rac1 pathway-mediated ROS production and cell migration is downregulated by ascorbic acid

Abstract

The oxidative role(s) of p66Shc protein has been increasingly expanded over the last decade. However, its relation with the most potent antioxidant molecule, i.e. ascorbic acid has never been studied. We have previously shown that p66Shc mediates rac1 activation, reactive oxygen species (ROS) production and cell death. Here we studied the effect of ascorbic acid on the pathway involving p66Shc and rac1. Our results indicate a decrease in the expression of p66Shc in a dose- and time-dependent manner. We studied the effect of ascorbic acid on rac1 expression and its activity. Ascorbic acid has no effect on total rac1 expression; however, rac1 activation was inhibited in a dose-dependent manner. Results suggest that the decrease in rac1 activity is mediated through ascorbic acid-modulated p66Shc expression. The decrease in rac1 activity was evident in cells transfected with the p66shc mutant (proline motif mutant, at residues P47 to P50). Our studies indicate that p66Shc-mediated ROS upregulation is significantly decreased in the presence of ascorbic acid. Cell migration experiments point towards the inhibition of p66Shc-rac1-mediated migration in the presence of ascorbic acid. Finally, results are suggestive that ascorbic acid-mediated decrease in Shc expression occurs through an increased Shc ubiquitination. Overall, the study brings out the novel role of ascorbic acid in antioxidant signal transduction.

<div>Epigenetic memory of oxidative stress: does nephrilin exert its protective effects via Rac1?</div>

“…Rictor complex is implicated in the activation of Prex1, PKCs alpha and beta-2 and — indirectly through PKC-beta-2 — p66shc 12,18,26,27. Our results, taken together, suggest at least two pathways (PKC-beta and Prex1) through which Rictor complex might control the activation of Rac1/2, and possibly a third via activated PKC-alpha and ERK 26.…”

The Adaptor Proteins p66Shc and Grb2 Regulate the Activation of the GTPases ARF1 and ARF6 in Invasive Breast Cancer Cells

“…Although p66Shc has been reported to influence cellular growth and migration on a variety of cell types (37,39,40,44,45), we demonstrate for the first time its physiological role in invasive breast cancer cells. We show that knockdown of p66Shc significantly attenuates the growth of MDA-MB-231 cells.…”

“…p66Shc Mediates Breast Cancer Cell Growth and MigrationBecause ARF1 and p66Shc have been previously reported to mediate cell growth and migration (29,37,39,40), we next evaluated the physiological role of p66Shc in MDA-MB-231 cells. First, we evaluated the importance of p66Shc expression in cell proliferation using a cell counting assay.…”

“…A signaling cascade also implicated in the induction of breast cancer cell migration (32). Additionally, p66Shc has been shown to induce migration via the activation of another small GTPase, Rac1 (39). Recently, we have demonstrated that Rac1 9.…”

p66Shc regulates migration of castration-resistant prostate cancer cells

“…In the mitochondrial intermembrane space, p66Shc binds and oxidizes cytochrome C, uncoupling the electron transport chain and inducing production of reactive oxygen species (ROS) [10]. Additionally, p66Shc has been reported to induce Rac1 activation in mouse fibroblasts and breast cancer, though their interaction in PCa is unknown [11]. Rac1 is a key regulator of cell motility and can also increase ROS production via interaction with NOX family of NADPH oxidases [12].…”