Mechanism of -lipopolysaccharide in Regulating the Insulin Signaling Pathway in Adipocytes Via X-box Binding Protein 1

Objectives: This study aims to investigate the effect of X-box binding protein 1 (XBP1), a key signal molecule of ERS, on the insulin signaling pathway in adipocytes stimulated by ()-lipopolysaccharide (LPS), a pathogenic bacterium of periodontitis.

Methods: Primary cultured rat adipocytes were stimulated by -LPS (100 ng·mL) for 4, 8, 12, and 24 h. The protein expression levels of insulin receptor substrate-1 (IRS-1), phosphoinositide dependent protein kinase (p-PDK-1), and protein kinase B (p-AKT-1) in the insulin signaling pathway were detected by Western blot analysis. pLVX-NC1, pLVX-XBP1, pLVX-NC2, and pLVX-XBP1-RNAi were transfected into adipocytes, respectively. The transfected rat adipocytes were stimulated by -LPS, and the protein expression of the insulin signaling pathway was detected by Western blot.

Results: The Western Blot showed decreased protein expression of the insulin signaling pathway in rat adipocytes stimulated with -LPS compared with the control, and the difference was statistically significant (<0.05). The protein expression levels of IRS-1, p-PDK-1, and p-AKT in the rat adipocytes of pLVX-XBP1 were significantly higher than those in pLVX-NC1 at 8 and 12 h after -LPS stimulation (<0.05). The protein expression levels of IRS-1, p-PDK-1, and p-AKT in the rat adipocytes of pLVX-XBP1-RNAi were significantly lower than those in pLVX-NC2 at 4, 8, 12, and 24 h after -LPS stimulation (<0.05).

Conclusions: -LPS regulates the insulin signaling pathway in adipocytes th-rough XBP1.