Mechanical stretch modulates microRNA 21 expression, participating in proliferation and apoptosis in cultured human aortic smooth muscle cells.
OBJECTIVE
Stretch affects vascular smooth muscle cell proliferation and apoptosis, and several responsible genes have been proposed. We tested whether the expression of microRNA 21 (miR-21) is modulated by stretch and is involved in stretch-induced proliferation and apoptosis of human aortic smooth muscle cells (HASMCs).


RESULTS
RT-PCR revealed that elevated stretch (16% elongation, 1 Hz) increased miR-21 expression in cultured HASMCs, and moderate stretch (10% elongation, 1 Hz) decreased the expression. BrdU incorporation assay and cell counting showed miR-21 involved in the proliferation of HASMCs mediated by stretch, likely by regulating the expression of p27 and phosphorylated retinoblastoma protein (p-Rb). FACS analysis revealed that the complex of miR-21 and programmed cell death protein 4 (PDCD4) participated in regulating apoptosis with stretch. Stretch increased the expression of primary miR-21 and pre-miR-21 in HASMCs. Electrophoretic mobility shift assay (EMSA) demonstrated that stretch increased NF-κB and AP-1 activities in HASMCs, and blockade of AP-1 activity by c-jun siRNA significantly suppressed stretch-induced miR-21 expression.


CONCLUSIONS
Cyclic stretch modulates miR-21 expression in cultured HASMCs, and miR-21 plays important roles in regulating proliferation and apoptosis mediated by stretch. Stretch upregulates miR-21 expression at least in part at the transcription level and AP-1 is essential for stretch-induced miR-21 expression.
Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Department of Cardiology, Qilu Hospital, Shandong University, Jinan, Shandong, People's Republic of China.
Jian tao
Jt
Song
Bo
B
Hu
Hai yan
Hy
Qu
Cheng long
Cl
Bi
Xiao zhen
Xz
Huang
Mei
M
Zhang
D001011:Aorta / Q000166:cytology*; D017209:Apoptosis / Q000235:genetics*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000378:metabolism*; D010766:Phosphorylation; D016601:RNA-Binding Proteins / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D013314:Stress, Mechanical; D018808:Transcription Factor AP-1 / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; C114487:PDCD4 protein, human; D016601:RNA-Binding Proteins; D016160:Retinoblastoma Protein; D018808:Transcription Factor AP-1; D050760:Cyclin-Dependent Kinase Inhibitor p27