MicroRNA-Mediated Epigenetic Silencing of Sirtuin1 Contributes to Impaired Angiogenic Responses
Rationale: Transforming growth factor (TGF)-beta was linked to abnormal vessel function and can mediate impairment of endothelial angiogenic responses. Its effect on microRNAs and downstream targets in this context is not known.
Objective: To study the role of miRNAs in TGF-beta mediated angiogenic activity.
Methods and Results: MiRNA profiling after TGF-beta treatment of endothelial cells identified miR-30a-3p, along with other members of the miR-30 family, to be strongly silenced. Supplementation of miR-30a-3p restored function in TGF-beta treated endothelial cells. We identified the epigenetic factor Methyl CpG binding protein 2 (MeCP2) to be a direct and functional target of miR-30a-3p. Viral over-expression of MeCP2 mimicked effects of TGF-beta, suggesting that de-repression of MeCP2 after TGF-beta treatment may be responsible for impaired angiogenic responses. Silencing of MeCP2 rescued detrimental TGF-beta effects on endothelial cells. Microarray transcriptome analysis of MeCP2 over-expressing endothelial cells identified several deregulated genes important for endothelial cell function including Sirtuin1. In vivo, experiments employing endothelial cell-specific MeCP2 null or Sirtuin1 transgenic mice confirmed involvement of MeCP2/Sirt1 in the regulation of angiogenic functions of endothelial cells. Further experiments identified that MeCP2 inhibited endothelial angiogenic characteristics partly by epigenetic silencing of Sirtuin1.
Conclusions: TGF-beta impairs endothelial angiogenic responses partly by down-regulating miR-30a-3p and subsequent de-repression of MeCP2-mediated epigenetic silencing of Sirtuin1.
- Received May 4, 2013.
- Revision received August 16, 2013.
- Accepted August 19, 2013.