MiR-423-5p activated by E2F1 promotes neovascularization in diabetic retinopathy by targeting HIPK2

Qing Xiao,Jia Xu,Hongjing Sun,Yinu Zhao,Limo Gao,Wenjie Li

doi:10.1186/s13098-021-00769-7

Abstract

BackgroundDiabetic retinopathy (DR) is a diabetic complication and the primary cause of blindness in the world. However, the treatments of DR are challenging given its complicated pathogenesis. Here, we investigated the molecular mechanisms of DR by focusing on the function of E2F1/miR-423-5p/HIPK2/HIF1α/VEGF axis.MethodsCultured retinal endothelial cells (hRMECs, hRECs) were treated with 25 mM glucose to mimic the high glucose-induced DR in vitro. Streptozotocin (STZ) was injected into mice to induce DR in mice. qRT-PCR, western blotting, immunohistochemistry, and ELISA were employed to measure levels of E2F1, miR-423-5p, HIPK2, HIF1α, and VEGF. H&E staining was utilized to examine retinal neovascularization. CCK-8 assay, transwell assay, and vascular tube formation assay were used to assess the cell viability, migration, and angiogenesis. Dual luciferase assay was performed to validate interactions between E2F1 and miR-423-5p, miR-423-5p and HIPK2.ResultsHG treatment increased the cell viability, migration, and angiogenesis accompanied by upregulation of E2F1, miR-423-5p, HIF1α, and VEGF levels, but reduction in HIPK2 expression. Knockdown of E2F1 or miR-423-5p suppressed the HG-induced increases in cell viability, migration, and angiogenesis. E2F1 transcriptionally activated miR-423-5p expression and miR-423-5p mimics blocked the effects of E2F1 knockdown on angiogenesis. Moreover, miR-423-5p directly targeted HIPK2 to disinhibit HIF1α/VEGF signaling. Knockdown of HIPK2 reversed the effects of miR-423-5p inhibitor on cell viability, migration, and angiogenesis. Knockdown of E2F1 suppressed neovascularization during DR in vivo.ConclusionsE2F1 activates miR-423-5p transcription during DR to promote angiogenesis via suppressing HIPK2 expression to disinhibit HIF1α/VEGF signaling. Strategies targeting E2F1/miR-423-5p/HIPK2 axis could be potentially used for DR treatment.

Highlights

Diabetic retinopathy (DR) is a diabetic complication and the primary cause of blindness in the world
HG increased E2F transcription factor 1 (E2F1) and miR‐423‐5p but diminished Homeodomain-interacting protein kinase 2 (HIPK2) in Human retinal microvascular endothelial cells (hRMECs) and human primary retinal endothelial cells (hRECs) cells To study the functions of E2F1/miR-423-5p/HIPK2 axis in DR, we employed the cell model of DR by challenging hRMEC and hREC cells with HG condition and measured their levels
Compared to cells cultured in normal glucose (NG) condition, E2F1 massager RNAs (mRNAs) and miR-423-5p levels were greatly up-regulated in cells grown in HG condition while HIPK2 mRNA was diminished (Fig. 1A and B)

Summary

Introduction

Diabetic retinopathy (DR) is a diabetic complication and the primary cause of blindness in the world. The most common complication of diabetes is diabetic retinopathy (DR), a condition that damages. It has been shown that E2F1 plays critical roles in regulating cell cycle progression, cell death, and development [7, 8]. Some studies indicated important functions of E2F1 in angiogenesis and oxidative stress [9, 10], two processes crucial for diabetes. A recent study showed that E2F1 mediated diabetic retinal neuronal death [11]. E2F1 can regulate expression of multiple microRNAs (miRNAs) [12, 13]. Emerging evidence shows that miRNAs have important roles in multiple cellular processes, including physiological processes and diseases [15]. Whether E2F1 regulates miR-423-5p expression is unknown

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