Role And Mechanism Of Heat Shock Protein 70 In Airway Hypersecretion

Objective:To observe the relationship between Heat shock protein 70 (HSP70) and activated protein-1, and explore the role and mechanism of HSP70 in airway hypersecretion.Methods:After stimulated by 8% cigarette smoke extract (CSE), the airway cells A549 were treated with HSP70 antibody, c-Jun N-terminal kinase (JNK) specific inhibitor SP600125, respectively. A549 cells were divided into four groups:vacuity contrast group cultured in serum-free medium, CSE stimulation group cultured in 8% CSE for 24 h, HSP70 antibody group pre-treated by HSP70 antibody for 30 minutes then cultured in 8% CSE for 24h, SP600125 group pre-treated by JNK specific inhibitor SP60012530 μmol/L for 30 minutes then cultured in 8% CSE for 24 h. The relative expressions levels of MUC5AC in various groups were determined by enzyme linked immunosorbent assay (ELISA). The relative transcription levels of MUC5AC mRNA were detectived by reverse transcription-PCR, the synthesized levels of HS70 as well as the phosphorylation levels of JNK and activated protein-1 (mainly c-Jun) were measured by Western blot.Result:As compared with those in vacuity contrast group(0.28±0.06, 0.26±0.10,0.30±0.05,0.30±0.08,0.36±0.08), HSP70 antibody group(0.29±0.09,0.30±0.12,0.34±0.06,0.47±0.19,0.39±0.13) and SP600125 group(0.31±0.14,0.38±0.06,0.39±0.04,0.44±0.12,0.48±0.11), the relative expression levels of MUC5AC mRNAand protein, phosphorylation JNK (p-JNK), c-Jun and p-c-Jun(0.64±0.11,0.52±0.07, 0.73±0.06,0.67±0.10,0.67±0.09) were significantly increasing in CSE stimulation group(all P<0.05). As well as the synthesized levels of HSP70(0.75±0.09) in CSE stimulation group was increasing than vacuity contrast group(0.29±0.03) and HSP70 antibody group(0.40±0.11) (all P<0.05).Conclusion:CSE could enhance the expression levels of HSP70 and AP-1, and HSP70 may enhance the expression of the MUC5AC in bronchial epithelial A549 cells via a JNK/AP-1 signaling pathway.