MicroRNA 9 Is a Regulator of Endothelial to Mesenchymal Transition in Diabetic Retinopathy

Abstract

Purpose Diabetic retinopathy (DR) is a significant cause of blindness. Most research around DR focus on late-stage developments rather than early changes such as early endothelial dysfunction. Endothelial-to-mesenchymal transition (EndMT), an epigenetically regulated process whereby endothelial cells lose endothelial characteristics and adopt mesenchymal-like phenotypes, contributes to early endothelial changes in DR. The epigenetic regulator microRNA 9 (miR-9) is suppressed in the eyes during DR. MiR-9 plays a role in various diseases and regulates EndMT-related processes in other organs. We investigated the role miR-9 plays in glucose-induced EndMT in DR. Methods We examined the effects of glucose on miR-9 and EndMT using human retinal endothelial cells (HRECs). We then used HRECs and an endothelial-specific miR-9 transgenic mouse line to investigate the effect of miR-9 on glucose-induced EndMT. Finally, we used HRECs to probe the mechanisms through which miR-9 may regulate EndMT. Results We found that miR-9 inhibition was both necessary and sufficient for glucose-induced EndMT. Overexpression of miR-9 prevented glucose-induced EndMT, whereas suppressing miR-9 caused glucose-like EndMT changes. We also found that preventing EndMT with miR-9 overexpression improved retinal vascular leakage in DR. Finally, we showed that miR-9 regulates EndMT at an early stage by regulating EndMT-inducing signals such as proinflammatory and TGF-β pathways. Conclusions We have shown that miR-9 is an important regulator of EndMT in DR, potentially making it a good target for RNA-based therapy in early DR.

Non-coding RNA-mediated endothelial-to-mesenchymal transition in human diabetic cardiomyopathy, potential regulation by DNA methylation

“…The observations of EndMT and altered expressions of related ncRNAs in human hearts with DCM are largely validations of previous findings from cell and animal models [ 8 , 9 , 18 , 36 – 38 , 42 ]. In this study, we further take the opportunity to explore other facets of the complex regulation of hyperglycemia-induced EndMT in DCM.…”

“…In this study, we used cardiac tissues from autopsies to investigate one specific manifestation of endothelial dysfunction, EndMT, in DCM. We further examined the expressions and promoter methylation statuses of several ncRNAs of interest as identified by previous in vitro and in vivo studies [ 8 , 9 , 37 , 38 , 48 ]. We show, for the first time, that cardiac microvascular endothelia in patients with DCM experience pathological EndMT.…”

“…Recently, miR-132-3p-downregulated in diabetes-has been reported to regulate EndMT in the aorta via regulation of Kruppel-like factor 7 [35]. We have previously identified lncRNA ZFAS1 and miRNAs 9, 146a, and 200b as regulators of fibrosis and EndMT in DCM and other diabetic complications in cell culture and in animal models [8,9,18,[36][37][38]. mir-200b and miR-146a regulate TGF-β and proinflammatory signaling, respectively, and are downregulated in diabetic cardiac Ecs [8,36,37].…”

CircRNA_012164/MicroRNA-9-5p axis mediates cardiac fibrosis in diabetic cardiomyopathy

“…RNA was isolated from mouse heart tissue and MCECs using TRIzol TM reagent (Invitrogen Canada Inc, ON, Canada). qRT-PCR was performed as in previous publications in our lab (44,45). The data was normalized to the housekeeping gene Actb to account for variances in amount of template and reverse transcriptase efficiencies, the primer sequences are as follows (Table 1).…”

“…MiRNA-9-5p (miR9) is a highly conserved miRNA that has been shown to be involved in a variety of cancers and diabetic complications (44)(45)(46). It is a molecule of interest in the heart with regards to cardiac fibrosis, and is known to be downregulated in diabetes and in response to hyperglycemia (44).…”