The MRNA-binding Protein Human-antigen R Regulates α-SMA Expression In Human Bronchia Smooth Muscle Cells

Objective The morphological and functional abnormality of human bronchia smooth muscle cells is one of important pathophysiological alterations in asthma. Platelet-derived Growth Factor over-expression can exist in injured human bronchia smooth muscle cells, which can stimulate proliferation in human bronchia smooth muscle cells and increase in various intracellular protein synthesis. That call lead to morphological and functional changes in human bronchia smooth muscle cells. Therefore, PDGF has important stimulative roles in the starting and developmental course of asthma. α-SMA is a HBSMC characteristic marker, its content can reflect the number of HBSMC and contraction ability.mRNA—stabilizing factor HuR protein is a mRNA binding protein, which Can bind with mRNA of effect protein post—transcriptionally. It Can strengthen mRNA stability and increase relevant protein expression to exert important pathophysiological effects. A survey suggests that HuR protein Can bind with post—transcriptional mRNA of α-SMA protein and strengthen its mRNA stability and increase relevant protein expression in a physiological state. To investigate the role of mRNA binding protein HuR in the over-expression of α-SMA stimulated by PDGF in cultured HBSMC.Methods (1)HBSMC culture and treatment:The HBSMC were culture in vitro. Group were divided as follws:①PDGF 0 h; ②PDGF 6 h; ③PDGF 12 h; ④PDGF 24 h; ⑤siHuR+PDGF 0 h; ⑥siHuR+PDGF 12 h; ⑦consiRNA+PDGF 0 h; ⑧consiRNA+PDGF 12 h;(2)Total HuR protein and total a-SMA protein expression were detected by Western blot.(3) Total HuR mRNA and total a-SMA mRNA level were determined by q-PCR.(4)Using RNA interference technology to down regulate HuR protein level to study the protective effect of HuR in PDGF-stimulated a-SMA protein expression. Results PDGF up-regulated the expression of HuR and a-SMA in a time-dependent manner. The relative expression levels of whole-cell HuR protein and mRNA were:①DGF 0h:0.23±0.09、1.00±0.00; ②PDGF 6h:0.42±0.11、1.09±0.03; ③PDGF 12 h:0.93±0.21、1.16±0.03; ④PDGF 24 h:1.37±0.28、1.27±0.02; (all P<0.05).The relative expression levels of a-SMA protein and mRNA were:①PDGF 0 h: 1.O3±.O8、1.00±0.00; ②PDGF 6 h:1.20±0.09、1.17±0.02; ③PDGF 12 h:1.39±0.11、 1.23±0.02; ④PDGF 24 h:1.58±0.10、1.45±0.03; Using RNA interference technology to down regulate HuR protein level, there was a decrease marked in a-Smooth muscle actin protein expression. The relative expression levels of a-SMA protein and mRNA were:consiRNA+PDGF 0 h:1.20±0.11、0.34±0.07; consiRNA+PDGF 12 h:1.50±0.10、0.82±0.12; siHuR+PDGF 0h:1.23±0.13、0.37±0.09; siHuR+PDGF 12h:0.89±0.11、0.35±0.08.Conclusions 1.PDGF stimulation can increase the expression of HuR and a-SMA in HBSMC;2.HuR protein is involved in the expression of a-SMA protein stimulated by PDGF.