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).
Keywords: IRAK1; NF-κB; TRAF6.; diabetes; heart; microRNA-146a.