Free fatty acid-induced muscle insulin resistance and glucose uptake dysfunction: evidence for PKC activation and oxidative stress-activated signaling pathways.

In the present study, we examined the effects of free fatty acids (FFAs) on insulin sensitivity and signaling cascades in the C2C12 skeletal muscle cell culture system. Our data clearly manifested that the inhibitory effects of PKC on insulin signaling may at least in part be explained by the serine/threonine phosphorylation of IRS-1. Both oleate and palmitate treatment were able to increase the Serine(307) phosphorylation of IRS-1.

Links between enhanced fatty acid flux, protein kinase C and NFkappaB activation, and apoB-lipoprotein production in the fructose-fed hamster model of insulin resistance.

In the current study, we show evidence, in a fructose-fed hamster model of insulin resistance, that free fatty acid (FFA) can induce hepatic insulin resistance in part via PKC activation leading to increased production of atherogenic apoB100-containing lipoproteins. Interestingly, IkappaB-kinase beta (IKKbeta)-dependent NF-kappaB was activated in hepatocytes from the fructose-fed hamster as an indication for PKC activation. Treatment of hepatocytes with oleate for 16h showed the activation of the PKC isoforms, PKCalpha/betaII, in a dose dependent manner.

Protein kinase inhibitor 2-aminopurine overrides multiple genotoxic stress-induced cellular pathways to promote cell survival.

2-Aminopurine (2-AP) is an adenine analog shown to cause cells to bypass chemical- and radiation-induced cell cycle arrest through as-yet unidentified mechanisms. 2-AP has also been shown to act as a kinase inhibitor. Tumor suppressor p53 plays an important role in the control of cell cycle and apoptosis in response to genotoxic stress.