Regulation of Cell Proliferation and Apoptosis by ERK Signaling Pathway in Airway Smooth Muscle Cells of Rats / 中国生物化学与分子生物学报

ABSTRACT

The regulative role of extracellular signal-regulated kinase(ERK)signaling pathway on proliferation and apoptosis in rats' airway smooth muscle cells(ASMCs)was investigated.Primary cultures of ASMCs were established and cells between passages 4 and 7 were used for experiments.ASMCs were U-eated with ERK activator epidermal growth factor(EGF)and inhibitor PD98059.The expressions of ERK mRNA and protein were detected by RT-PCR and immunofluorescence staining.Proliferation of ASMCs were detected by MTT eolorimetric assay and [3H] thymidine incorporation.Apoptosis of ASMCs were detected by Hoechst staining and Annexin-V FITC PI donble staining.The levels of ERK1/2,phosphorylated forms of ERK1/2(p-ERK1/2) and proeaspase-3 protein were detected by Western blotting.The expressions of ERK mRNA and ERK protein were obviously observed in ASMCs. Compared with control,the absorbanee(A490) value and DNA synthesis index of PD-treated ASMCs were significantly decreased(P＜0.05).The apoptotic index and the percentage of the early apoptotic cells were significantly increased(P＜0.05).The expressions of ERK1/2 and pERK1/2 protein were significantly down-regulated.The expressions of procaspase-3 protein was significantly increased.Compared with c,ontrol,the A490 value and DNA synthesis index were significantly increased(P＜0.05)in EGF-treated cells.Apoptotic index and the percentage of the early apoptotic cells were significantly decreased(P＜0.05).The levels of ERK1/2 and pERK1/2 protein were significantly increased,and the levels of procaspase-3 protein were significantly decreased, There were no significant differences between control and P+E group(P＞0.05).ERK signaling pathway may play an important role in regulating ASMCs proliferation and apoptosis and ERK regulating the apoptosis of ASMCs possibly relates to the expressions of procaspase-3 protein. The finding will help to understand the mechanisms of asthmatic ASMCs involved in abnormal proliferation.