Role and mechanism of heat shock protein 70 in airway hypersecretion

Abstract

To explore the role and mechanism of heat shock protein 70 (HSP70) in airway hypersecretion. After a stimulation of 8% cigarette smoke extract (CSE), airway cells A549 were treated with HSP70 antibody and c-Jun N-terminal kinase (JNK) specific inhibitor SP600125 respectively. And the cells were divided into 4 groups of blank contrast (serum-free medium), CSE stimulation (8% CSE for 24 h), HSP70 antibody (30-min pre-treatment of HSP70 antibody and culturing in 8% CSE for 24 h) and SP600125 (30-min pre-treatment of SP600125 30 µmol/L and culturing in 8% CSE for 24 h). The relative expression levels of MUC5AC protein in various groups were determined by enzyme-linked immunosorbent assay (ELISA). And the relative transcription level of MUC5AC mRNA was detected by reverse transcription-polymerase chain reaction (PCR) while the synthesized levels of HS70 as well as the phosphorylation levels of JNK and activated protein-1 (mostly c-Jun) were measured by Western blot. As compared with those in blank contrast group (0.26 ± 0.10, 0.28 ± 0.06, 0.30 ± 0.05, 0.30 ± 0.08, 0.36 ± 0.08), HSP70 antibody group (0.30 ± 0.12, 0.29 ± 0.09, 0.34 ± 0.06, 0.47 ± 0.19, 0.39 ± 0.13) and SP600125 group (0.38 ± 0.06, 0.31 ± 0.14, 0.39 ± 0.04, 0.44 ± 0.12, 0.48 ± 0.11), the relative expression levels of MUC5AC protein and mRNA, phosphorylation JNK (p-JNK), c-Jun and p-c-Jun (0.52 ± 0.07, 0.64 ± 0.11, 0.73 ± 0.06, 0.67 ± 0.10, 0.67 ± 0.09) significantly increased in CSE stimulation group (all P < 0.05). And the synthesis levels of HSP70 (0.75 ± 0.09) in CSE stimulation group increased than blank contrast group (0.29 ± 0.03) and HSP70 antibody group (0.40 ± 0.11) (all P < 0.05). HSP70 may enhance the expression of MUC5AC in bronchial epithelial A549 cells via a signaling pathway of JNK/AP-1..