Endogenous SHBG levels correlate with that of glucose transporters in insulin resistance model cells

Abstract

Gestational diabetes mellitus (GDM) is defined as glucose intolerance of any degree that occurs after onset of pregnancy. Sex hormone binding globulin (SHBG) plays an important regulatory role in insulin resistance and is a risk factor in GDM. In the current study, we aimed to examine whether SHBG can regulate glucose metabolism through glucose transporters (GLUTs). SHBG was transfected into established human insulin model cells and the expression of SHBG, GLUT1, GLUT3, and GLUT4 was detected and analyzed in normal cells, model cells, and all groups of transfected cells by real-time PCR and western blotting. Further, immunofluorescence staining was performed on cells from each group to observe protein expression. In insulin resistance model cells, the expression of SHBG was low, whereas that of GLUT1 was high and of GLUT3 and GLUT4 was low, when compared with expression in control cells. Moreover, the overexpression of SHBG inhibited the expression of GLUT1 mRNA and protein, and promoted the expression of GLUT3 and GLUT4. Our results indicate that SHBG could be involved in glucose metabolism through its regulation of multiple GLUTs. Transfection of SHBG into insulin-resistant cells may partially improve the level of GLUTs, providing a potential therapeutic approach for the treatment of insulin resistance in GDM. Although SHBG can regulate glucose metabolism through GLUTs and thus cause insulin resistance and induce gestational diabetes, the regulation mechanism of GLUTs mediated by SHBG has not been elucidated, which will be the focus of further studies.