The Effects Of Chronic Mechanical Stress On Mucin 5ac Expression And Its Signal Transduction Mechanism

Objective To investigate the effect of chronic mechanical stress on the mucin(MUC)5AC expression in airway epithelial cells and its possible signaling transduction pathway.Methods (1)The rats airway epithelial cells were cultured in transwell microporous membrane at an air-liquid interface and treated with EGFR kinase inhibitor AG1478,specific inhibitor of the ERK pathway PD-98059 respectively. Then chronic mechanical stress was used to stimulus the treated cells.The MUC5AC protein was detected by enzyme-linked immunosorbent assay,MUC5AC mRNA level was analyzed by RT-PCR (2) The cells were divided into 4 groups:a negative control group, a stress treatment group, an AG1478 pre-treatment group and a PD98059 pre-treatment group. Stress treatment group were divided into 3 level:10cmH2O,20cmH2O,30cmH2O.The MUC5AC protein was detected by enzyme-linked immunosorbent assay,MUC5AC mRNA level was analyzed by RT-PCR,the protein contents of phosphorylated extracelluar signal-regulated kinase (p-ERK), phosphorylated c-Jun N-terminal kinase (p-JNK), and phosphorylated P38(p-P38) were detected by Western blotting.Results (1)The expression of MUC5AC protein and mRNA in stress treatment group were significantly higher than those in control group dose dependently. The highest effect observed in the 30cmH2O stress treatment group. (2)The protein contents of p-ERK in stress treatment group were higher than that in control group, but the level of p-JNK and p-P38 was not significantly different from that of the control group.(3)After pretreatment with AG1478 and PD-98059 respectively,the relative content of MUC5AC protein and mRNA and p-ERK decreased significantly than that in 30cmH2O stress treatment group.Conclusions (1)Chronic mechanical stress can significantly up-regulates the expression of MUC5AC protein and mRNA dose dependently.EGFR and ERK signal cascades play a role in the process.(2)This process may through collapse of the lateral intercellular space (LIS) under chronic mechanical stress.