The role of miR-146a on NF-κB expression level in human umbilical vein endothelial cells under hyperglycemic condition.

Emerging studies have been shown that the expression of micrRNA-146a (miR-146a, as a regulator of nuclear factor κB (NF-κB)), is changed in diabetic patients and animals. This study was designed to evaluate the possible role of miR-146a in the pathogenesis of diabetes-related microvascular complications. Concurrent with the creation of cellular hyperglycemia (25 mmol/L for 24 h), human umbilical vein endothelial cells (HUVECs) were transfected with 20 nmol/L of hsa-miR-146a antagomir or scramble using HiPerFect reagent (Qiagen). D-mannitol was used as osmotic control. Hyperglycemia increased the NF-κB gene expression and protein activity (as an inflammation index) in cultured HUVECs. Moreover, the gene expression level of miR-146a, and its target proteins, tumor necrosis factor receptor-associated factor 6 (TRAF6) and interleukin-1 receptor-associated kinase 1 (IRAK1) were increased under hyperglycemic condition. The knockdown of miR-146a by transfection of miR-146a antagomir notably increased the NF-κB activity and decreased the NF-κB mRNA in hyperglycemic HUVECs. Furthermore, miR-146a antagomir significantly increased IRAK1 and TRAF6 mRNA levels under hyperglycemic condition. These results demonstrate that the expression of miR-146a is upregulated in HUVECs during early phase of hyperglycemic condition possibly to regulate the NF-κB activity through inhibition of IRAK1 and TRAF6 (Fig. 4, Ref. 32).

MicroRNA-146a and its adapter proteins are affected by diabetes in rat's heart.

OBJECTIVES: This study was conducted to explore whether microRNA-146a and its adapter proteins (TNF-α receptor-associated factor 6 (TRAF6) and interleukin-1 receptor-associated kinase 1 (IRAK1)) are affected by diabetes in the rat heart. METHODS: Twelve male Sprague-Dawley rats were randomized into control and diabetic groups (n = 6). Streptozotocin-nicotinamide experimental model was used to induce type 2 diabetes. The gene expression of MicroRNA-146a, nuclear factor-κB (NF-κB), IRAK1 and TRAF6, as well as NF-κB activity, IRAK1 and TRAF6 protein levels were measured. Moreover, NF-κB activity was measured in response to miR-146a mimic transfection (20 nmol) in human umbilical vein endothelial cells (HUVECs) under hyperglycemic condition (25 mM D-glucose for 24 h). RESULTS: The expression of MicroRNA-146a was increased in the heart tissue, 2 months after diabetes induction and in HUVECs. Also, the mRNA and protein levels of NF-κB, IRAK1 and TRAF6 were increased in the heart of diabetic rats. Moreover, transfection of miR-146a mimic prevented from a significant increase of NF-κB activity in hyperglycemic HUVECs. CONCLUSION: Presumably, a defect in the regulation of IRAK1 and TRAF6 can weaken miR-146a regulatory effect and provides a situation for sustained activation of NF-κB and its targets to promote cardiac cells toward abnormalities (Fig. 3, Ref. 28).