Over-expression of HSP70 induces apoptosis of intestinal epithelial cells in heat-stressed pigs: A proteomic approach

Background Heat stress (HS)-induced intestinal epithelial cell apoptosis may play a pivotal role in intestinal barrier function injury in animals. However, the underlying molecular mechanism by which HS induces apoptosis of intestinal epithelial cells is still poorly understood. Methods The trial uses a prospective study. Firstly, a eukaryotic expression vector for the HSP70 gene was constructed and transfected into intestinal porcine epithelial cells (IPEC-J2) and then analyzed with a functional proteomics approach followed by liquid-chromatography-tandem mass spectrometry (LC-MS/MS) identification. Next, heat stress treatment of IPEC-J2 cells and pigs were performed. Immunoblotting and flow cytometry were used to examine the protein changes and cellular apoptosis. Results 246 differentially expressed proteins (DEPs) were identified in HSP70-overexpressed IPEC-J2 cells, functional annotation suggested that most of the DEPs were related to ECM-receptor interaction, focal adhesion, and apoptosis. Moreover, apoptosis rate was increased in IPEC-J2 cells transfected with porcine HSP70 overexpressing plasmid accompanied with the expression of apoptosis-related proteins, Caspase-3, PARP, and Bax were up-regulated, whereas Bcl-2 protein expression was down-regulated. Interestingly, increased Caspase-3, PARP, and Bax with decreased Bcl-2 were observed in IPEC-J2 cells under heat stress conditions. In an in vivo porcine model, HS-induced cellular apoptosis in the duodenum, cecum, and colon, as well the up-regulation of HSP70 in the intestinal tissues. Conclusions HSP70 may play a regulatory role in cellular apoptosis within IPEC-J2 cells. Taken together, our findings provide new insights for understanding the molecular mechanisms of cellular apoptosis associated with HSP70.