Silencing of ClC‐3 protects against preadipocyte apoptosis in type 2 diabetes (1142.6)

Abstract

OBJECTIVE: ClC‐3 chloride channel, plays an important role in the regulation of cell volume,proliferation and apoptosis. Preadipocytes of type 2 diabetes show a tendency to enhanced apoptosis. We hypothesized that there is a relation between ClC‐3 and insulin resistance, and one underlying mechanism may be associated with the modulation of free fatty acid (FFA) ‐induced preadipocyte apoptosis by ClC‐3.METHODS: Type 2 diabetes mellitus (T2DM) models in ClC‐3 KO mice and rats were induced by fed with high‐sucrose‐high‐fat diet combined with a low dose of streptozocin. The cellular apoptosis was detected by Annexin V‐PI staining.RESULTS: Compared with the wild‐type T2DM models, ClC‐3 knockout T2DM mice displayed an improvement in insulin resistance, a decrease in serum plasma free fatty acid (FFA) levels and preadipocyte apoptosis in epididymal fat pad, as evidenced by significant decrease in homeostatic model assessment of insulin resistance (HOMA‐IR) and flow cytometry. In T2DM rat models, we further found that ClC‐3 protein in adipose tissue is increased, and was positively correlated to HOMA‐IR, but was not the case in liver and skeletal muscle. We further found that palmitate‐induced preadipocyte apoptosis in vitro was parallel to a significant increase in the endogenous expression of ClC‐3 protein. Transfection with ClC‐3 siRNA decreased apoptosis and activation of caspase‐3 and 9, whereas increased ratio of Bcl‐2/Bax in palmitate‐treated preadipocytes. ClC‐3 affected apoptosis mainly through regulating ER stress signaling proteins such as Grp78, CHOP and ATF4.CONCLUSION: We concluded that chloride channel ClC‐3 modulates palmitate‐induced apoptosis in preadipocytes via the ER stress pathway. ClC‐3 in adipocyte tissue may be involved in the development of type 2 diabetes.Grant Funding Source: Supported by National Natural Science Foundation of China (No. 81370897,No. 813111115 and No. 812300