MicroRNAs regulate endothelial function and angiogenesis, but their implication in pericyte biology remains undetermined. A PCR array, covering a panel of 379 human microRNAs, showed microRNA-532-5p to be one of the most differentially modulated by hypoxia, which was confirmed by qPCR in both skeletal muscle and adventitial pericytes. Furthermore, microRNA-532-5p was upregulated in murine muscular pericytes early after experimentally induced ischemia, decreasing below baseline after reperfusion. Transfection of human pericytes with anti-microRNA, microRNA-mimic, or controls indicates microRNA-532-5p modulates pro-angiogenic activity via transcriptional regulation of angiopoietin-1. Tie-2 blockade abrogated the ability of microRNA-532-5p-overexpressing pericytes to promote endothelial network formation in vitro. However, angiopoietin-1 is not a direct target of microRNA-532-5p. In silico analysis of microRNA-532-5p inhibitory targets associated with angiopoietin-1 transcription indicated three potential candidates, BACH1, HIF1AN, and EGLN1. Binding of microRNA-532-5p to the BACH1 3′ UTR was confirmed by luciferase assay. MicroRNA-532-5p silencing increased BACH1, while a microRNA-532-5p mimic decreased expression. Silencing of BACH1 modulated angiopoietin-1 gene and protein expression. ChIP confirmed BACH1 transcriptional regulation of angiopoietin-1 promoter. Finally, microRNA-532-5p overexpression increased pericyte coverage in an in vivo Matrigel assay, suggesting its role in vascular maturation. This study provides a new mechanistic understanding of the transcriptional program orchestrating angiopoietin-1/Tie-2 signaling in human pericytes. Angiopoietin-1 is an important regulator of angiogenesis, yet little is known regarding its transcriptional regulation. Slater et al. (2018) demonstrate angiopoietin-1 induction in pericytes occurs via miR-532-5p regulation of BACH1 and modulation of this pathway promotes changes in endothelial permeability, vascular stability, and angiogenesis.
Slater, S. C., Jover, E., Martello, A., Mitić, T., Rodriguez-Arabaolaza, I., Vono, R., … Madeddu, P. (2018). MicroRNA-532-5p Regulates Pericyte Function by Targeting the Transcription Regulator BACH1 and Angiopoietin-1. Molecular Therapy, 26(12), 2823–2837. https://doi.org/10.1016/j.ymthe.2018.08.020