Abstract
112 - Coordinated MicroRNA Silencing of Nox4 NADPH Oxidase and Myocardin Regulates Smooth Muscle Cell Dedifferentiation in Vascular Disease
Free radical biology & medicine, Vol.87(Suppl 1), pp.S58-S58
10/2015
DOI: 10.1016/j.freeradbiomed.2015.10.152
Abstract
The transcription factor myocardin plays a critical role in the regulation of smooth muscle cell (SMC) phenotypic switching in vascular disease. The Nox4 NADPH oxidase has been implicated in SMC differentiation and its expression associated with changes in myocardin levels. However, the molecular basis of Nox4 regulation and the mechanisms by which vascular injury result in molecular reprogramming by myocardin are poorly understood. We hypothesized that microRNAs (miR)-mediate changes in Nox4 expression and regulate expression of genes implicated in SMC differentiation. Analysis of the 3'UTR of Nox4 identified putative miR-9 and miR-25 binding sites which were confirmed with luciferase reporter assays. Treatment of human SMCs with a miR-9 or miR-25 mimic (1) silenced Nox4 mRNA and decreased ROS levels; (2) suppressed myocardin mRNA expression; (3) decreased expression of multiple differentiation genes; and (4) was sufficient to induce cell migration. Expression of miR-9 and miR-25 was increased in cultured human SMCs and human pulmonary artery segments after treatment with TNF-a or thrombin, and in murine carotid artery ten days after partial carotid ligation. Interestingly, despite silencing by a miR-25 mimic, the myocardin 3'UTR binds miR-9 but not miR-25. We found that miR-25 induced the expression of miR-9 and pretreatment with a miR-9 inhibitor prevented miR-25-mediated silencing of Nox4 and myocardin. Suggesting a potential mechanism, miR-25 mimic caused demethylation of the miR-9 promoter. Finally, a miR-9 inhibitor prevented the migration of cultured SMC to thrombin and decreased neointimal formation by more than 50% to carotid partial ligation in mice. We conclude that following vascular injury (1) miR-25 induces epigenetic modifications resulting in the expression of miR-9; (2) miR-9 and mir-25 cooperate to silence Nox4; (3) Nox4 effects on SMC differentiation involve miR-9 regulation of myocardin; (4) inhibition of miR-9 blocks neointimal formation. These findings identify miR-9/Nox4 as part of a novel regulatory pathway and therapeutic target in vascular disease.
Details
- Title: Subtitle
- 112 - Coordinated MicroRNA Silencing of Nox4 NADPH Oxidase and Myocardin Regulates Smooth Muscle Cell Dedifferentiation in Vascular Disease
- Creators
- Brandon M Schickling - University of IowaFrancis J Miller - University of Iowa
- Resource Type
- Abstract
- Publication Details
- Free radical biology & medicine, Vol.87(Suppl 1), pp.S58-S58
- DOI
- 10.1016/j.freeradbiomed.2015.10.152
- ISSN
- 0891-5849
- eISSN
- 1873-4596
- Publisher
- Elsevier Inc
- Language
- English
- Date published
- 10/2015
- Academic Unit
- Obstetrics and Gynecology
- Record Identifier
- 9984966834502771
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