Diabetes (especially Type II) is one of the primary threats to cardiovascular health. Wound healing defects and vascular dysfunction are common in diabetic patients, and the primary cause of deterioration is sustained high plasma glucose. microRNA, a noncoding RNA, has regulatory functions that are critical to maintaining homeostasis. MicroRNA (miR)-126-3p is a potential diabetes biomarker and a proangiogenic factor, and its plasma level decreases in diabetic patients. Previous studies have revealed the proangiogenic character of the gasotransmitter hydrogen sulfide (H₂S). However, little is known about the relationship between H₂S and miR-126-3p when the extracellular glucose level is high, let alone their influences on deteriorated endothelial cell migration, a key component of angiogenesis, which is crucial for wound healing. Human umbilical vein endothelial cells (HUVECs) were treated with high glucose (33.3 mmol/L) or normal glucose (5.5 mmol/L) for 48 h. Affymetrix miRNA profiling and real-time PCR were used to validate the miRNA expression. An H₂S probe (HSip-1) was used to detect endogenous H₂S. Scratch wound-healing assays were used to evaluate HUVEC migration. The protein levels were quantified by Western blot. Both exogenous and endogenous H₂S could upregulate the miR-126-3p levels in HUVECs or muscle tissue. High glucose decreased the H₂S level and the protein expression of the H₂S-producing enzyme cystathionine γ-lyase (CSE) in HUVECs; however, the DNA methyltransferase 1 (DNMT1) protein level was upregulated. CSE overexpression not only increased the miR-126-3p level by decreasing the DNMT1 protein level but also rescued the deteriorated cell migration in HUVECs treated with high glucose. DNMT1 overexpression decreased the miR-126-3p level and inhibited the migration of HUVECs, whereas silencing DNMT1 improved cell migration. High glucose decreased the endogenous H₂S and miR-126-3p levels and increased the DNMT1 expression, thus inducing the migration dysfunction of HUVECs. Treatment with exogenous H₂S or the overexpression of the endogenously produced enzyme CSE would rescue this migration dysfunction through H₂S-DNMT1-miR-126-3p.

Rui-qin Chen

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