Down-Regulation of miR-133a Contributes to Up-Regulation of RhoA in Bronchial Smooth Muscle Cells

• Published in: American journal of respiratory and critical care medicine 2009-10, Vol.180 (8), p.713-719
• Main Authors: Chiba, Yoshihiko, Tanabe, Miki, Goto, Kumiko, Sakai, Hiroyasu, Misawa, Miwa
• Format: Article
• Language: English
• Subjects: Aerosols; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Asthma; Asthma - genetics; Asthma - metabolism; Biological and medical sciences; Blood. Blood and plasma substitutes. Blood products. Blood cells. Blood typing. Plasmapheresis. Apheresis; Bronchi - cytology; Bronchi - metabolism; Bronchial Hyperreactivity - genetics; Bronchial Hyperreactivity - metabolism; Bronchial Provocation Tests; Cardiomyocytes; Cells, Cultured; Disease Models, Animal; Growth factors; Humans; Intensive care medicine; Kinases; Medical sciences; Mice; Mice, Inbred BALB C; MicroRNAs; MicroRNAs - genetics; MicroRNAs - metabolism; Myocytes, Smooth Muscle - metabolism; Proteins; rhoA GTP-Binding Protein - metabolism; Smooth muscle; Transfusions. Complications. Transfusion reactions. Cell and gene therapy; Up-Regulation
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.200903-0325OC

Augmented bronchial smooth muscle (BSM) contraction is one of the causes of bronchial hyperresponsiveness. The protein RhoA and its downstream pathways have now been proposed as a new target for asthma therapy. MicroRNAs (miRNAs) play important roles in normal and diseased cell functions, and a contribution of miR-133 to RhoA expression has been suggested in cardiomyocytes. To make clear the mechanism(s) of up-regulation of RhoA observed in the BSMs of experimental asthma, the role of miR-133a in RhoA expression was tested. Total proteins and RNAs (containing miRNAs) were extracted from cultured human BSM cells (hBSMCs) that were treated with antagomirs and/or IL-13, and bronchial tissues of BALB/c mice that were sensitized and repeatedly challenged with ovalbumin. RhoA protein and miR-133a were detected by immunoblotting and quantified real-time reverse transcriptase-polymerase chain reaction, respectively. In hBSMCs, an up-regulation of RhoA was observed when the function of endogenous miR-133a was inhibited by its antagomir. Treatment of hBSMCs with IL-13 caused an up-regulation of RhoA and a down-regulation of miR-133a. In bronchial tissues of the repeatedly ovalbumin-challenged mice, a significant increase in RhoA was observed. Interestingly, the level of miR-133a was significantly decreased in BSMs of the challenged mice. These findings suggest that RhoA expression is negatively regulated by miR-133a in BSMs. IL-13 might, at least in part, contribute to the reduction of miR-133a.