METTL3-Mediated m6A Modification of TIMP2 mRNA Promotes Podocyte Injury in Diabetic Nephropathy [RNA-seq]

Epigenetic changes present in many physiological and pathological processes. The N6-methyladenosine (m6A) modification is the most common modification in eukaryotic mRNA. However, the role of m6A modification in diabetic nephropathy (DN) is still elusive. Here, the level of m6A modification was significantly upregulated in podocytes stimulated by high glucose (HG), which was caused by elevated levels of METTL3. The results were consistent in the streptozotocin (STZ)-induced experimental model of type 1 diabetes and db/db type 2 diabetes mice. Knocking out METTL3 significantly reduced the inflammation and apoptosis of HG-stimulated podocytes, while its overexpression significantly aggravated these responses. More importantly, silencing METTL3 both in type 1 and type 2 diabetic mice in vivo significantly reduced urinary albumin excretion and histopathological injury. Mechanistically, METTL3 modulated Notch signaling via the m6A modification of its target gene, TIMP2, and exerted pro-inflammatory and pro-apoptotic effects. Moreover, METTL3 enhanced the stability of TIMP2 in an insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2)-dependent manner. In summary, this study suggested that METTL3-mediated m6A modification is an important mechanism of podocyte injury in DN. Targeting m6A through the writer enzyme METTL3 is a potential approach for the treatment of DN.