c-Myc participates in high glucose-mediated endothelial inflammation via upregulation of IRAK1 expression in diabetic nephropathy.

Diabetic nephropathy (DN) is a common vascular complication of diabetes. Endothelial adhesion molecules are involved in physiopathology of DN. Interleukin-1 receptor-associated kinase 1 (IRAK1) and c-Myc participate in inflammation in DN. We hypothesized c-Myc modulates IRAK1 expression, contributing to hyperglycemia-mediated endothelial inflammation. The expression of endothelial adhesion molecules and IRAK1 were increased in glomerular endothelium of DN patients and rats. Our cellular experiments indicated high glucose-induced endothelial cell inflammation was inhibited by si-IRAK1. Additionally, high glucose increased c-Myc expression. si-c-Myc inhibited high glucose-mediated increase of IRAK1 levels and endothelial cell inflammation. c-Myc overexpression-mediated endothelial cell inflammation was counteracted by si-IRAK1. c-Myc also interacted with lysine methyltransferase 5A (KMT5A). Furthermore, high glucose decreased KMT5A expression and histone H4 lysine 20 methylation (H4K20me1). KMT5A upregulation decreased high glucose-mediated increase of IRAK1 levels as well as endothelial inflammation. KMT5A silencing-mediated endothelial inflammation was reversed by si-IRAK1. Mechanistic research indicated that c-Myc and H4K20me1 occupied IRAK1 promoter region. KMT5A silencing augmented the active action of c-Myc on IRAK1 levels. Our in vivo experiments represented KMT5A is downregulated and c-Myc is upregulated in DN patients and rats. KMT5A interacts with c-Myc to modulate IRAK1 expression, thus contributing to hyperglycemia-mediated endothelial inflammation in DN.