MRNA-binding protein Human-antigen R regulates α-SMA expression in human bronchia smooth muscle cells

Abstract

To investigate the role of mRNA binding protein Human-antigen R (HuR) in the over-expression of α-Smooth muscle actin (α-SMA) stimulated by Platelet-derived Growth Factor (PDGF) in cultured human bronchia smooth muscle cells. Human bronchia smooth muscle cells cultured in vitro were divided into 0, 6, 12 and 24 h groups according to the time of PDGF treatment. Total HuR protein and total α-SMA protein expression were detected by Western blot. Total HuR mRNA and total α-SMA mRNA level were determined by quantitative real time-polymerase chain reaction. RNA interference technology was used to down-regulate HuR protein level to study the protective effect of HuR in PDGF-stimulated α-SMA protein expression. PDGF up-regulated the expression of HuR in a time-dependent manner. The relative expression levels of whole-cell HuR protein and mRNA in 0, 6, 12, 24 h groups were 0.23±0.09, 0.42±0.11, 0.93±0.21, 1.37±0.28; 1.00±0.00, 1.09±0.03, 1.16±0.03, 1.27±0.02 (all P<0.05). The relative expression levels of α-SMA protein and mRNA in 0, 6, 12, 24 h group also showed an increase trend marked in a time-dependent manner (1.03±0.08, 1.20±0.09, 1.39±0.11, 1.58±0.10; 1.00±0.00, 1.17±0.02, 1.23±0.02, 1.45±0.03; all P<0.05). Using RNA interference technology to down-regulate HuR protein level, there was a decrease in α-SMA protein expression. PDGF stimulation can increase the expression of HuR and α-SMA in the smooth muscle cells, and HuR protein is involved in the expression of α-SMA protein stimulated by PDGF.