Mechanism of Porphyromonas gingivalis-lipopolysaccharide in regulating the insulin signaling pathway in adipocytes via X-box binding protein 1.

Abstract

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 Porphyromonas gingivalis (P. gingivalis)-lipopolysaccharide (LPS), a pathogenic bacterium of periodontitis. Primary cultured rat adipocytes were stimulated by P. gingivalis-LPS (100 ng·mL-1) 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 P. gingivalis-LPS, and the protein expression of the insulin signaling pathway was detected by Western blot. The Western Blot showed decreased protein expression of the insulin signaling pathway in rat adipocytes stimulated with P. gingivalis-LPS compared with the control, and the difference was statistically significant (P<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 P. gingivalis-LPS stimulation (P<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 P. gingivalis-LPS stimulation (P<0.05). P. gingivalis-LPS regulates the insulin signaling pathway in adipocytes th-rough XBP1.