Abstract
Purpose :
MicroRNAs (miRNA) are small non-coding RNA molecules which are involved in metabolic regulation, regulation of gene expression, differentiation, apoptosis, tumorigenesis and angiogenesis. The role of miRNAs in the regulation of hypoxia and angiogenesis in ocular neovascular diseases by targeting HIF/VEGF axis has been suggested, albeit little is known regarding miRNAs directly regulated by HIF-1α. The purpose of this study is to explore and identify HIF-1α regulated miRNAs using an in vivo mouse model of oxygen-induced retinopathy (OIR).
Methods :
Litters of mouse pups (C57BL/6J) with their nursing mothers were exposed to high oxygen concentrations (~75%) between postnatal day (P)7 and 12, and returned to room air at P12. To assay possible HIF-1α mediated miRNA, intravitreal injection of echinomycin was performed a P12, prior to HIF-1α upregulation in OIR pups. Immunofluorescence, western blot, hypoxia-regulated miRNA arrays and qPCR analysis were performed on dissected retinas of P14 pups.
Results :
Volcano plot analysis of hypoxia-regulated miRNAs arrays showed that out of 84 miRNAs, 23 are significantly down-regulated; a return to control levels was observed in echinomycin-treated mice compared to room air, while an upregulation when compared to OIR PBS-injected mice. In particular, out of 23 significantly down-regulated miRNAs, miRNA-504-p was identified to significantly return to room air control levels.
Conclusions :
These data showed a downregulation of miRNAs in OIR, which may imply an upregulation of pro-angiogenic markers’ mRNAs. Hence, blocking HIF-1α with echinomycin in OIR may lead to a normalization of miRNAs to room air control levels.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.