Expression of Syntaxin 8 in Visceral Adipose Tissue Is Increased in Obese Patients with Type 2 Diabetes and Related to Markers of Insulin Resistance and Inflammation

Abstract

Obesity is associated with increased adipose tissue inflammation as well as with the development of type 2 diabetes (T2D). Syntaxin 8 (STX8) is a protein required for the transport of endosomes. In this study we analyzed the relationship of STX8 with the presence of T2D in the context of obesity. With this purpose, 21 subjects (seven lean [LN], eight obese normoglycemic [OB-NG] and six obese with type 2 diabetes [OB-T2D]) were included in the study. Gene and protein expression levels of STX8 and GLUT4 were analyzed in visceral adipose tissue (VAT). mRNA (p = 0.008) and protein (p <0.001) expression levels of STX8 were significantly increased in VAT of OB-T2D patients. Moreover, gene expression levels of SLC2A4 (GLUT4) were downregulated (p = 0.002) in VAT of obese patients. We found that STX8 was positively correlated (p <0.05) with fasting glucose concentrations, plasma glucose 2 h after an OGTT and C-reactive protein. Interestingly, the expression of STX8 was negatively correlated (p <0.05) with the expression of SLC2A4 in VAT. Increased STX8 expression in VAT appears to be associated with the presence of T2D in obese patients through a mechanism that may involve GLUT4.