Reversal of the renal hyperglycemic memory by targeting sustained tubular p21 expression

A major obstacle in diabetes is the metabolic or hyperglycemic memory, which lacks specific therapies. Here we show that glucose-mediated changes in gene expression largely persist in diabetic kidney disease (DKD) despite reversing hyperglycemia. The senescence-associated cyclin-dependent kinase inhibitor p21 (Cdkn1a) was the top hit among genes persistently induced by hyperglycemia and was associated with induction of the p53-p21 pathway. Persistent p21 induction was confirmed in various animal models, human samples and in vitro models. Tubular and urinary p21-levels were associated with DKD severity and remained elevated despite improved blood glucose levels in humans. Mechanistically, glucose-induced and sustained tubular p21 expression is linked to demethylation of its promoter and reduced DNMT1 expression. Exploiting signaling of the disease resolving protease activated protein C (3K3A-aPC, parmodulin-2) reversed sustained tubular p21 expression, tubular senescence, and DKD. Thus, p21-dependent tubular senescence is a pathway contributing to the hyperglycemic memory, which can be therapeutically targeted. In wild-type mice (C57BL/6, age 8-10 weeks) mice hyperglycemia was induced using low dose streptozotocin (STZ) injection (intraperitoneally, 60 mg/kg body weight, for 5 consecutive days). Subsets of mice were treated with a sodium-glucose co-transporter 2 inhibitor (SGLT-2i, Dapagliflozin®, 25 mg/kg body weight, in the drinking water . Mice were sacrificed at the end of study period and kidney samples were isolated and RNAseq was performed.