Soha N Yazbek
American University of Beirut, Lebanon
Title: Unfolding the novel role of SLC35b4 in glucose production and diabetes: Localization, expression, protien profiling and pathway analysis in HepG2 cells
Biography
Biography: Soha N Yazbek
Abstract
Type II diabetes is one of the most common endocrine disorders. The cumulative action of genetic variants account for 10% of heritability. SLC35b4, a solute receptor associated with obesity, insulin resistance and gluconeogenesis, transports UDP-N-acetylglucosamine and UDP-Xylose. The correlation between expression and functionality and the mechanism of action have not been elucidated. This study aimed to investigate the regulation of protein expression and localization of SLC35b4. We also aimed at comparing differentially expressed proteins between a knockdown of SLC35b4 and controls in HepG2 cells in order to decode its implication in macromolecules glycosylation and sugar production. Responsiveness was assayed using western blot analysis and immunostaining. To identify the cytoplasmic compartment harboring SLC35b4, double immunofluorescence (SLC35b4-Golgi apparatus and endoplasmic reticulum) studies were performed. The subcellular localization was confirmed using a PLA technique (duo-link). 2D gel elctrophoresis and MALDI_TOF were used to identify differentialy expressed protiens. Pathway analysis was performed to understand the downstream effect of the gene knock-out. Results revealed SLC35b4 is increased up to 60% upon glucose stimulation. SLC35b4 localized with Golgi apparatus and to a lesser extent with the endoplasmic reticulum. The presence of SLC35b4 in the Golgi apparatus confirms its involvement in the biosynthesis of glycoconjugates proteins. Four proteins were under-expressed when SLC35b4 gene was knocked out (HSPD, HSPA8, TUBA1A, and ENO1), all of which are involved in pathways affecting glucose and insulin homeostasis.We suggest that SLC35b4 activation alters the glycosylation pattern inside the cells causing an improvement of the insulin ability to inhibit endogenous glucose production.