Abstract 19241: Downregulation of microRNA-494 Facilitates Smooth Muscle Cell Proliferation and Vascular Remodeling
Introduction: Proliferation of vascular smooth muscle cells (VSMC) plays a crucial role in the development of vascular proliferative diseases such as atherosclerosis and in-stent-restenosis. MicroRNAs (miR) are small noncoding RNAs that modulate gene expression in a posttranscriptional manner.
Hypothesis: in this project we aimed to determine the functional impact of a micro-RNA which is strongly regulated during vascular remodeling.
Methods and Results: Neointima formation was induced by a wire-mediated injury of the femoral artery in C57BL/6 mice. Microarray analysis of the developing neointimal lesion showed a strong reduction of miR-494 (0.411±0.04) at 7 days after injury as compared to uninjured controls, which could be confirmed by qPCR. Interestingly, miR-494 was found to be predominantly expressed in SMC as determined by in situ hybridization. The regulation of miR-494 expression was further analyzed in vitro after stimulation of SMC with 10% FCS. Following this mitogenic stimulation, mir-494 expression dropped robustly and significantly in a time-dependent manner at 6, 9, and 24 hours. To investigate the functional impact of miR-494 on SMC proliferation, miR-494 was overexpressed using miR-494-mimics (20μM). Overexpression of miR-494 significantly reduced the FCS-induced proliferation of SMC as assessed by BrdU-incorporation and total cell counts. In silico analyses of potential target genes for miR-494 identified survivin, an important molecule for cell cycle regulation, as potential target of miR-494. Indeed, survivin was found down-regulated on the mRNA and protein level after transfection of SMC with miR-494 mimics and could be confirmed as direct target using luciferase reporter assays.
Conclusions: Taken together, our results show that mir-494 is strongly down-regulated in proliferating SMC in vitro as well as during neointimal lesion formation in vivo. Moreover, the anti-proliferative effect of miR-494-reconstitution reveals a crucial functional role of miR-494 in the mitogenic response of SMC. Thus, miR-494 might represent a novel and promising SMC-specific target for future therapeutic strategies in the treatment of vascular proliferative diseases.
Author Disclosures: K. Donde: None. J. Daniel: None. J. Dutzmann: None. J. Bauersachs: None. D. Sedding: None.
- © 2014 by American Heart Association, Inc.