Abstract 5752: Role of MicroRNA-503 in Diabetic Endotheliopathy
Diabetes disturbs endothelial function and reparative neovascularisation, thus contributing to limb ischemia. Recently, we showed that the atypical neurotrophin receptor p75NTR mediates diabetes-determined impairment of reparative neovascularization. Diabetes induces p75NTR expression in microvascular endothelial cells (ECs) of ischemic limb muscles, thus impairing EC survival and functions. Conversely, p75NTR inhibition restores proper post-ischemic neovascularization in diabetic mice. Making a step forward into the understanding of the relevance of p75NTR in diabetic microangiopathy, here we studied whether p75NTR modulates the expression of microRNAs (miRNAs) in ECs. MiRNAs are small non-coding RNAs that act as endogenous regulators of gene expression, by controlling degradation and/or translational repression of target mRNAs. Using microarray analyses of miRNAs expression in human umbilical vein ECs (HUVECs) transduced with p75NTR or control (empty vector), we detected that miRNA-503 (miR-503) was consistently induced in p75NTR-transduced ECs. Moreover, both p75NTR and miR-503 expression in HUVECs was increased following culture in high glucose to mimic diabetic hyperglycaemia. Furthermore, miR-503 expression was higher in ischemic muscles of diabetic mice in comparisons to non diabetic mice. Lentivirus-mediated overexpression of miR-503 in HUVECs impaired cell proliferation and decreased in vitro capillary-like network formation on matrigel. In order to search for miR-503 target genes, we used the CORNA R package and TargetScan to identify the link between in silico predicted target genes of miR-503 and genes downregulated in the Illumina™ microarray of p75NTR-transduced HUVECs and of p75NTR-transduced limb muscles. Functional analysis revealed that several target genes were involved in cell cycle control and angiogenesis. Among this group of genes, we identified CyclinE1, cdc25A and VEGF-A as direct targets of miR-503 in ECs. These results suggest a role of miRNA-503 in diabetes-induced microangiopathy and impaired angiogenesis.