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

Background: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Arginase 2; Arginine metabolism; Endothelial impairment; Hyperglycemia-induced metabolic memory; Mitochondrial fission.