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A letter to the editor is presented discussing stress-induced hyperglycemia and diabetes mellitus in a Chinese population.

Aims: The present study aimed to explore the mechanism of a potential beneficial effect of pre-existing diabetes in acute hyperglycemia during critical illness.Methods: Pathophysiological changes including blood glucose variability, changes of inflammatory and oxidative stress responses after lipopolysaccharide (LPS)-induced acute infection were compared between type 2 diabetic rat model (GK rats) and normal controls (Wistar rats).Results: After LPS injection, Wistar rats showed serious infective symptoms while GK rats did not. Blood glucose (BG) levels were significantly elevated in both GK and Wistar rats; however, compared to Wistar rats, GK rats had lower BG variability, smaller increases in the serum tumor necrosis factor (TNF)-α and interleukin (IL)-6 levels, a larger increase in the serum IL-10 level, and a smaller decrease in the IκB-α protein level of lung tissue. Serum malondialdehyde (MDA) levels increased and serum total antioxidant capacity (T-AOC) levels decreased for both GK and Wistar rats.Conclusions: We found diabetes was associated with adaptive changes at the cellular level that might actually be protective in acute hyperglycemia-mediated damage during sepsis. Chronic exposure to hyperglycemia potentially reduced the acute deleterious effects of acute hyperglycemia on septic mortality by decreasing BG variability, blunting the pro-inflammatory response and elevating the anti-inflammatory response. [ABSTRACT FROM AUTHOR]

Fatty acid-induced lipotoxicity plays an important role in the pathogenesis of diabetes mellitus. Our previous studies have documented that lipotoxicity contributes to the onset and development of diabetes via insulin resistance and/or compromised function of the pancreatic β-cells. However, the underlying molecular mechanisms associating lipotoxicity with insulin resistance remain to be fully elucidated. In this study, we explored the role of TRB3-COP1-SIRT1 in lipotoxicity leading to insulin resistance in hepatocytes. High fat diet (HFD)-fed mice and hepG2 cells stimulated with palmitate were utilized as models of lipid metabolism disorders. We analyzed the interactions of SIRT1 and COP1 with each other and with TRB3 using co-immunoprecipitation, western blotting. SIRT1 ubiquitination was also explored. Animal and cell experiments showed that lipotoxicity induced SIRT1 down-regulation at the protein level without altering the mRNA level, whereas, lipotoxicity led to up-regulation of TRB3 and COP1 at both the gene and protein levels. Mechanistic analysis indicated that COP1 functioned as an E3 Ub-ligase of SIRT1, responsible for its proteasomal degradation under lipotoxic conditions. TRB3 recruited COP1 to SIRT1 to promote its ubiquitination. Our data indicated for the first time that TRB3-COP1-SIRT1 pathway played an important role in lipotoxicity leading to insulin resistance in hepatocytes, and suggested that COP1 could be a potential therapeutic choice for the treatment of diabetes mellitus, with lipotoxicity being the important pathomechanism. • SFA induced COP1 expression both in mRNA and protein levels in hepatocytes. • SFA induced down-regulation of SIRT1 without altering its expression level. • SIRT1 interacted with COP1 and TRB3. • COP1 was a new E3 ubiquitin ligase for SIRT1. • TRB3-COP1-SIRT1 pathway worked in insulin resistance triggered by lipotoxicity. [ABSTRACT FROM AUTHOR]