Their work
provides a molecular explanation for the derangements associated with hepatocyte IR by demonstrating that PKCε ASO restores insulin receptor substrate-2 (IRS-2) phosphorylation and protein-serine-threonine kinase activity.63 A more recent study by the same group64 developed this line of research further by demonstrating that hepatic diaglycerol content in cytoplasmic lipid droplets, which was strongly associated with activation of hepatic PKCε activity, was the best predictor of IR, being responsible for 64% of the variability in insulin sensitivity. Gupta et al. recently published the effect of exendin-4, Adriamycin a glucagon-like peptide 1 (GLP-1) analog as promoting insulin-sensitizing effects by way of PKCζ.65 Finally, FFA, which are causally linked to the development of steatosis, have been recognized
as inductors of IR via activation of protein kinases.66,67 Although requiring further study, this line of research underscores the importance of fatty liver as a precursor lesion to the development of systemic IR accounting for the finding that NAFLD individuals are twice as likely to develop T2D as those without NAFLD.5 Clearly, the mechanisms leading from hepatic X-396 mouse steatosis to long-lasting IR and, in predisposed individuals, to T2D are critical. Lipotoxicity remains key to the pathogenesis of T2D.1 Stated otherwise, the presence of long-standing IR per se is not sufficient to lead to full-blown T2D in the absence of β-cell failure. Therefore, morphological evidence of fatty changes in the pancreas could be a 上海皓元 better marker of pancreatic lipotoxicity.
Recent studies suggest that steatosis of the pancreas is visible through endoscopic ultrasound. Interestingly, risk factors for “fatty pancreas” tend to overlap with those for fatty liver68,69 suggesting a shared pathogenesis in lipotoxicity, the ectopic, extra-adipose tissue storage of lipids eventually conducive to tissue damage and organ dysfunction. Assessment of mediators of IR is of critical importance: Fetuin-A and IL-6 could be such mediators. Fetuin-A, a protein secreted by the liver and associated with the development of IR in animals and with fatty liver in humans, has been proposed as one such mediator. Stefan et al.70 in a large prospective case cohort – EPIC-Potsdam study –observed fetuin-A to be an independent predictor of T2D. IL-6 – a major pro-inflammatory cytokine, the expression of which is increased in experimental NAFLD, resulting in systemic IR – could be another mediator. Wieckowska et al. reported that the expression of IL-6 in the hepatocytes, which is selectively induced by saturated FFA, is positively correlated with hepatic inflammatory fibrotic changes and systemic.