Effects of calcium binding protein S100A16 on promoting insulin resistance

Objective To explore the effects of S100A16, a calcium-binding protein on insulin resistance. Methods Immunoprecipitation was performed with S100A16 antibody, and mass spectrometry was used to find proteins interacting with S100A16. HepG2 cells transfected with shRNA plasmids or S100A16 overexpression plasmids were defined as experimental group 1 and HepG2 cells transfected with vector plasmids as control group 1. Chronic insulin stimulation was done to the cells to establish insulin resistance models, in which cells transfected with shRNA plasmids were experimental group 2. Those not transfected or transfected with vector plasmids were set to be control group 2. Cells treated with pioglitazone were experimental group 3 and those without pioglitazone treatment were control group 3 in insulin resistance group. The expression levels of relevant proteins were detected by Western blot. Unpaired t test was used for statistical analysis. Results Compared with control group 1, the expression of Fetuin A in overexpressed S100A16 group in experimental group 1 was increased significantly (1.39±0.54 vs 2.85±0.25, P< 0.05) , while the expression of Fetuin A in shRNA group in experimental group 1 was significantly decrease (0.36±0.03 vs 0.20±0.03, P< 0.01) . In contrast to control group 2, the expression of IRS-2 (insulin receptor substrate-2) in experimental group 2 was significantly increased under the condition of insulin resistance (0.11±0.04 vs 1.65±0.48, P< 0.01) . And compared with control group 3, the expression of IRS-2 in experimental group 3 was obviously increased (0.26±0.11 vs 0.52±0.05, P< 0.01) . Conclusion S100A16 promotes insulin resistancein HepG2 cells via Fetuin A. Key words: S100A16; Insulin resistance; Fetuin A; Insulin Receptor Substrate-2; HepG2 cells