NF-κB regulates HSF1 and c-Jun activation in heat stress-induced intestinal epithelial cell apoptosis

Abstract

Heat stress may induce intestinal epithelial cell apoptosis; however, the molecular mechanisms have not yet been identified. The present study used IEC-6 rat small intestinal epithelial cells to investigate heat stress-induced production of reactive oxygen species (ROS), which may be involved in nuclear factor (NF)-κB activation during heat stress. IEC-6 cells were transfected with NF-κB p65-specific small interfering RNA (siRNA), and observed a significant increase in cell apoptosis and caspase-3 cleavage; however, in cells transfected with adenovirus that constitutively overexpressed p65, the opposite results were obtained. Furthermore, p65 knockdown increased the heat stress-induced expression and activity of heat shock transcription factor 1 (HSF1); conversely, p65 overexpression slightly decreased HSF1 activity. The levels of heat stress-induced c-Jun phosphorylation were also examined: Knockdown of p65 resulted in a reduction of c-Jun phosphorylation, whereas p65 overexpression resulted in increased phosphorylation. Furthermore, siRNA-mediated knockdown of HSF1 in IEC-6 cells significantly increased heat stress-induced apoptosis. Cells pretreated with c-Jun peptide, an inhibitor of c-Jun activation, exhibited a significant reduction in apoptosis. These findings indicated that heat stress stimulation in IEC-6 cells induced the pro-apoptotic role of NF-κB by regulating HSF1 and c-Jun activation.