MiR-485-5p targets RGS4 to promote angiogenesis in lower limb ischemia by activating VEGFR-2/AKT/ERK1/2 signaling.

Abstract

Angiogenesis is critical for post-ischemic tissue repair. Although miR-485-5p is highly expressed in vascular tissues and RGS4 regulates angiogenesis, their specific roles under hypoxia remain largely unknown. This study aimed to elucidate these functions and underlying mechanisms. Using a CoCl₂-induced hypoxic model in HUVECs, we observed that hypoxia significantly downregulated miR-485-5p expression while concurrently upregulating RGS4 mRNA levels. Notably, either inhibition of RGS4 or overexpression of miR-485-5p markedly enhanced HUVEC proliferation, migration, and tube formation. A luciferase reporter assay further confirmed that miR-485-5p directly targets RGS4. In addition, miR-485-5p overexpression or RGS4 inhibition increased the phosphorylation levels of VEGFR-2, AKT, and ERK1/2. Through co-immunoprecipitation assays, we revealed for the first time a direct interaction between RGS4 and VEGFR-2, which suppresses VEGF signaling and consequently impairs angiogenesis. Conversely, overexpression of RGS4 reversed the pro-angiogenic effects of miR-485-5p, as evidenced by reduced VEGFR-2/AKT/ERK1/2 phosphorylation and decreased proliferation, migration, and tube formation in HUVECs. These findings indicate that miR-485-5p promotes angiogenesis by downregulating RGS4. Consistent with these in vitro results, experiments in vivo using a rat hindlimb ischemia model confirmed that inhibition of RGS4 via si-RGS4 or overexpression of miR-485-5p via agomir-miR-485-5p markedly improved blood perfusion recovery, enhanced vascular angiogenesis, and increased VEGFR-2/AKT/ERK1/2 phosphorylation. Collectively, our study demonstrates that the miR-485-5p/RGS4 axis promotes hypoxia-induced angiogenesis by relieving RGS4-mediated inhibition of VEGFR-2/AKT/ERK1/2 signaling, thereby providing a strong rationale for targeting miR-485-5p as a possible treatment approach for lower extremity arterial disease.