Epigenetic and O-glycosylation regulation of p66Shc mitigates mitochondrial oxidative stress in aortic dissection

Background: Aortic dissection (AD) is a life-threatening vascular emergency with limited effective pharmacological treatments.Recent studies have identified p66Shc as a crucial mediator of oxidative stress, apoptosis, and inflammation in aortic cells, thereby contributing to cellular dysfunction and vascular remodeling implicated in AD development and progression.Despite its established role in promoting vascular dysfunction and remodeling, the protective potential of targeting p66Shc in AD remains unclear.Methods: We analyzed clinical samples using ELISA assays to determine the changes in aPC concentrations between the control group and the aortic dissection (AD) group.Additionally, we detected the expression alterations of p66Shc protein in these two groups via Western blot (WB), immunohistochemistry (IHC), and immunofluorescence (IF) assays.We established an aortic dissection model in TM-mutant ApoE -/-mice and administered exogenous PC to verify its effect on aortic dissection.Meanwhile, we performed a series of functional experiments in vitro, including Western blot, co-immunoprecipitation, double-label immunofluorescence, chromatin immunoprecipitation, luciferase reporter gene assays and mitochondrial function evaluations.Results: In this study, we demonstrate that activated protein C (aPC), a coagulation protease with known cytoprotective properties, downregulates p66Shc expression through epigenetic modifications.Additionally, aPC can modulate the expression of a cold shock protein Y box binding protein 1 (YBX1), which acts as a transcription factor, leading to elevated glycosyltransferase levels.This upregulation enhances the O-glycosylation of p66Shc on its 29th tyrosine residue, preventing its mitochondrial translocation, preserving mitochondrial membrane potential, and reducing reactive oxygen species (ROS) production.Consequently, these molecular mechanisms inhibit the onset and progression of AD.Conclusions: aPC epigenetically represses p66Shc transcription and promotes O-glycosylation at Thr29 via the YB-1/OGT axis, thereby inhibiting mitochondrial ROS production and preventing vascular injury.