Involvement of the p66^Shcprotein in glucose transport regulation in skeletal muscle myoblasts

Abstract

The p66(Shc) protein isoform regulates MAP kinase activity and the actin cytoskeleton turnover, which are both required for normal glucose transport responses. To investigate the role of p66(Shc) in glucose transport regulation in skeletal muscle cells, L6 myoblasts with antisense-mediated reduction (L6/p66(Shc)as) or adenovirus-mediated overexpression (L6/p66(Shc)adv) of the p66(Shc) protein were examined. L6/(Shc)as myoblasts showed constitutive activation of ERK-1/2 and disruption of the actin network, associated with an 11-fold increase in basal glucose transport. GLUT1 and GLUT3 transporter proteins were sevenfold and fourfold more abundant, respectively, and were localized throughout the cytoplasm. Conversely, in L6 myoblasts overexpressing p66(Shc), basal glucose uptake rates were reduced by 30% in parallel with a approximately 50% reduction in total GLUT1 and GLUT3 transporter levels. Inhibition of the increased ERK-1/2 activity with PD98059 in L6/(Shc)as cells had a minimal effect on increased GLUT1 and GLUT3 protein levels, but restored the actin cytoskeleton, and reduced the abnormally high basal glucose uptake by 70%. In conclusion, p66(Shc) appears to regulate the glucose transport system in skeletal muscle myoblasts by controlling, via MAP kinase, the integrity of the actin cytoskeleton and by modulating cellular expression of GLUT1 and GLUT3 transporter proteins via ERK-independent pathways.

TNFα Signals via p66Shc to Induce E-Selectin, Promote Leukocyte Transmigration and Enhance Permeability in Human Endothelial Cells

“…HUVEC expressing increased levels of the p66 Shc protein were obtained as described previously [30]. Briefly, the gene of interest was cloned into the shuttle vector pAdTrack-CMV, then co-transformed into E. coli BJ5183 cells with the adenoviral backbone plasmid pAdEasy-1, and transfected into the adenovirus packaging cell line QBI293A.…”

Oxidative Stress and Cardiovascular Risk: Obesity, Diabetes, Smoking, and Pollution

“…It is activated by hyperglycemia (31), and H 2 O 2 generated by p66 Shc was shown to be involved in DM-related complications in various organs (32). In addition, p66 Shc is involved in the regulation of glucose transport into cells (33) and is critical in maintaining insulin-dependent signaling (34). The phosphorylation of p66 Shc on Ser36, which is induced via mitochondrial ROS and results in a further increase in ROS production, is known to be activated in various pathologies associated with oxidative stress, including DM and obesity (32).…”

Insulin signaling and life span

“…Furthermore, p66Shc knockout mice are protected from dietinduced obesity, suggesting that p66Shc is a genetic determinant of fat development in adult mice. These effect might be cell specific since Natalicchio and colleagues have shown that, in rat myoblasts, p66Shc exerts an inhibitory effect on the mitogen-activated protein kinase signaling pathway, which is necessary for maintenance of IGF responsiveness of the MEK/Erk pathway and normal cell phenotype [93,94]. Again, in these cells, p66shc appears to regulate the glucose transport system by controlling, via MAP kinase, the integrity of the actin cytoskeleton.…”