Effects of cyclic mechanical stretch on the activity of STAT3 in human bronchial epithelial cell (16HBEC)

Objective To study the effects of cyclic mechanical stretch on the activity and expression of STAT3 in Human bronchial epithelial Cell(16HBEC). Methods The 16HBECs were subjected to cyclic mechanical stretch by the four-point bending system at 0.5 Hz of 1 kPa,2 kPa,3 kPa,4 kPa for 30 min or for 30 min,1 h,3 h,and 6 h of 3 kPa respectively. The mRNA level of STAT3 was semi-quantified by RT-PCR; STAT3 protein and phosphorylated STAT3 were detected by western blot. Results Phosphorylation level of STAT3 Tyr705 was higher under 3 kPa cyclic mechanical stretch than the others. 3 kPa stretch phosphorylatd STAT3 Tyr705 in 16HBE cells in a time-dependent manner. The phosphorylation of STAT3-Tyr705 was significantly increased at 30min compared with the control group(P0.05),and reached the highest phosphorylation level at 1h,then showed a sharp descending tendency. There was no effect of 3 kPa stretch on the phosphorylation of STAT3 Ser727,expression of STAT3 protein or mRNA levels. Conclusion STAT3 played an important role in the response and signal transduction of 16HBECs to the cyclic mechanical stretch stimulation through the phosphorylation of STAT3 Tyr705.