Endothelial Arg2 regulates HIMM-induced mitochondrial hyperfission via affecting arginine metabolism

Pathological features of cardiovascular complications remain persistent in diabetic patients, even under strict blood glucose control. Hyperglycemia-induced metabolic memory (HIMM) in endothelial cells (ECs) is a significant contributor to this phenomenon, particularly through its effects on mitochondrial function. Arginase2 (Arg2), a mitochondrial enzyme, plays a crucial role in regulating mitochondrial and vascular homeostasis in various vascular diseases, but the role of endothelial Arg2 in HIMM remains unclear.

We established both in vivo (HIMM-mouse model) and in vitro (HIMM-EC model) systems to assess the activation status of arginase 2 (Arg2), alterations in arginine metabolism, and mitochondrial function. Endothelial-specific Arg2-overexpressing and knockout mice were generated to evaluate the critical role of Arg2 in cardiovascular function and HIMM-induced protection via ultrasound imaging system, laser speckle flowmetry, myograph, and immunofluorescence staining. Arg2-knockout/overexpression cell lines were established and mitochondrial function and its regulatory mechanisms in response to damage was assessed using MitoSOX, MitoTracker, oxygen consumption rate (OCR), and Western blot.

We initially observed that HIMM triggered significant Arg2 activation, arginine metabolism dysregulation, mitochondrial dysfunction, and vascular impairment in both in vivo and in vitro models. Endothelial-specific Arg2 overexpression successfully recapitulated these pathological phenotypes, leading to endothelial damage and vascular dysfunction. Further we confirmed that endothelial Arg2 knockout effectively protected against HIMM-induced endothelial damage, mitochondrial hyper-fragmentation, and cardiac dysfunction. These improvements were mediated by correcting aberrant Arg2 expression, which restored arginine levels, activated the NO-cGMP-PKG signaling pathway, and ultimately suppressed excessive mitochondrial fission, leading to improved cardiovascular function.

Our findings highlight the critical role of endothelial Arg2 in maintaining vascular homeostasis via arginine metabolism and mitochondrial fission. This identifies Arg2 as a promising therapeutic target for HIMM-related vascular diseases.