Spermidine mediates acetylhypusination of RIPK1 to suppress diabetes onset and progression

It has been established that N-acetyltransferase (murine NAT1 (mNAT1) and human NAT2 (hNAT2)) mediates insulin sensitivity in type 2 diabetes. Here we show that mNAT1 deficiency leads to a decrease in cellular spermidine—a natural polyamine exhibiting health-protective and anti-ageing effects—but understanding of its mechanism is limited. We identify that mNAT1 and hNAT2 modulate a type of post-translational modification involving acetylated spermidine, which we name acetylhypusination, on receptor-interacting serine/threonine-protein kinase 1 (RIPK1)—a key regulator of inflammation and cell death. Spermidine supplementation decreases RIPK1-mediated cell death and diabetic phenotypes induced by NAT1 deficiency in vivo. Furthermore, insulin resistance and diabetic kidney disease mediated by vascular pathology in NAT1-deficient mice can be blocked by inhibiting RIPK1. Finally, we demonstrate a decrease in spermidine and activation of RIPK1 in the vascular tissues of human patients with diabetes. Our study suggests a role for vascular pathology in diabetes onset and progression and identifies the inhibition of RIPK1 kinase as a potential therapeutic approach for the treatment of type 2 diabetes.