Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear. It has been postulated that an increase in the intracellular concentration of fatty acid metabolites activates a serine kinase cascade, which leads to defects in insulin signaling downstream to the insulin receptor. In addition, the complex network of adipokines released from adipose tissue modulates the response of tissues to insulin. Among the many molecules involved in the intracellular processing of the signal provided by insulin, the insulin receptor substrate-2, the protein kinase B and the forkhead transcription factor Foxo 1a are of particular interest, as recent data has provided strong evidence that dysfunction of these proteins results in insulin resistance in vivo. Recently, studies have revealed that phosphoinositidedependent kinase 1-independent phosphorylation of protein kinase Cε causes a reduction in insulin receptor gene expression. Additionally, it has been suggested that mitochondrial dysfunction triggers activation of several serine kinases, and weakens insulin signal transduction. Thus, in this review, the current developments in understanding the pathophysiological processes of insulin resistance in type 2 diabetes have been summarized. In addition, this study provides potential new targets for the treatment and prevention of type 2 diabetes.
Human cytomegalovirus (HCMV) is a widespread pathogen that establishes lifelong latent infection facilitated by numerous mechanisms for modulating the host immune system. The UL111A region of the HCMV genome encodes a homolog of human cellular IL-10 (hIL-10). The viral cytokine, cmvIL-10, exhibits many of the immunosuppressive properties of hIL-10. However, hIL-10 is also known to have stimulatory effects on B lymphocytes. We found that cmvIL-10 has the ability to enhance B cell proliferation, despite having only 27% sequence identity to hIL-10. Treatment with cmvIL-10 stimulated autocrine production of hIL-10 by B lymphocytes and led to activation of the latent transcription factor Stat3. In contrast, LAcmvIL-10, a truncated protein resulting from an alternatively spliced transcript in latently infected cells, did not stimulate B cell proliferation, Stat3 activation, or hIL-10 production. These results provide insights into the biological activity of the full-length and latency-associated viral cytokines and suggest different roles for each in HCMV infection.
The endothelial dysfunction has been implicated as a major event in the pathogenesis of atherosclerosis. Therefore, this study was planned to determine (a) role of endothelium-derived nitric oxide (NO) and endothelin as coronary artery disease (CAD) risk markers and (b) intergenotypic variation of endothelial nitric oxide synthase (eNOS) Glu298Asp polymorphism in CAD.The endothelin, NO and eNOS genotypes were determined in 60 patients with documented history of CAD. These were compared with 50 age- and sex- matched healthy controls. The genotype frequencies for eNOS gene polymorphism were determined by PCR and RFLP. The plasma endothelin in CAD patients was significantly higher (p < 0.001) whereas, the NO level in CAD group was significantly lower (p < 0.001) than the control group. The genotype frequencies for Glu298/Asp (Glu/Glu and Glu/Asp) genotypes were 75% and 25% in CAD subjects and 88% and 12% in control subjects, respectively. No Asp/Asp was found in any of the groups. The genotype frequencies differed significantly (p < 0.05) between the controls and cases. In conclusion, endothelin and NO may be used as markers of endothelial dysfunction in CAD. Asp allele might be a risk factor for CAD in the North Indian population.
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