m6A demethylase FTO ameliorates metabolic abnormalities in diabetic kidney disease by regulating PDK1 expression

Background: Proximal renal tubular damage plays an important role in the occurrence and progression of diabetic kidney disease (DKD). N6-methyladenosine (m6A) is the most abundant modification of mammalian mRNAs and plays a key role in many biological processes, including diabetes. The role of m6A in the development of diabetic kidney disease remains unclear. This study aimed to evaluate changes in diabetes-related renal m6A and its underlying mechanisms.Methods: C57BL/6 mice were fed a high-fat diet (HFD) for eight weeks, administered low-dose streptozotocin (STZ) by intraperitoneal injection for five consecutive days, followed by continued high-fat feeding for eight weeks. Blood and urine samples were collected from the mice, and their renal cortices were collected for follow-up studies. Results: We first tested blood and urine samples to ensure the success of the DKD model, followed by preliminary screening by m6Aseq, which showed that pyruvate dehydrogenase kinase 1 (PDK1) m6A methylation was elevated, and FTO expression was reduced in DKD mice. PDK1 protein was significantly enriched in the proximal renal tubules. A high-glucose environment significantly inhibited FTO function and increased PDK1 m6A methylation in HK2 cells, resulting in increased PDK1 protein expression and elevated p-PDH and lactate levels, which in turn led to metabolic abnormalities.Conclusions: Taken together, our results reveal the FTO/m6A/PDK1 axis and provide insight into the mechanisms of DKD development and progression.