4-Phenylbutyric acid protects islet β cell against cellular damage induced by glucocorticoids.

This study, using the MIN6 cell line, examines the effect of glucocorticoids (GCs) on the expression and protein levels of endoplasmic reticulum stress (ERS) related genes. Furthermore, we evaluated the protective role of 4-phenylbutyric acid (4-PBA) on the aforesaid GCs induced changes. Pancreatic islet MIN6 cells were treated with dexamethasone (DEX) at distinct concentrations (0.1 μmol/L and 0.5 μmol/L) for different periods (1 h, 4 h, 12 h, and 24 h). The mRNA and protein levels of ERS related genes were measured using real-time qPCR (qRT-PCR) and western blotting. Similar evaluations were also carried out for the cells treated with 4-PBA combined with DEX. Upon DEX intervention which induces the unfolded protein response (UPR), the expression levels of BIP, ATF6, IRE1, and PERK increased in the MIN6 cells, both in concentration and time-dependent manner. Similarly, ERS associated gene CHOP, which is involved in the apoptotic pathway, also showed increased levels both in concentration and time-dependent manner. However, treatment with 4-PBA decreased the expression levels of ERS related proteins. Quantitative analysis found that all these results were statistically significant (P < 0.05). GCs markedly activates the ERS in the MIN6 cell line in vitro, however, this effect can be significantly alleviated upon treatment with 4-PBA.