Role of Tmem163 in zinc-regulated insulin storage of MIN6 cells: Functional exploration of an Indian type 2 diabetes GWAS associated gene

Abstract Genome wide association study for type 2 diabetes discovered TMEM163 as a risk locus. Perturbations in TMEM163 expression was reported to be associated with impaired intracellular zinc homeostasis. Physiological concentration of zinc is instrumental to maintain insulin storage and functionality in pancreatic β cells. We found abundant TMEM163 expression in human pancreas, both at transcriptional and translational levels. Knockdown of endogenous Tmem163 in MIN6 cells resulted in increased intracellular zinc and total insulin content, coupled with compromised insulin secretion at high glucose stimuli. Furthermore, Tmem163 knockdown led to enhanced cellular glucose uptake. Upon next generation sequencing, one-third of the studied T2D patients were found to have a novel missense variant in TMEM163 gene. Study participants harboring this missense variant displayed a trend of higher glycemic indices. This is the first report on exploring the biological role of TMEM163 in relation to T2D pathophysiology.