Myocyte enhancer factor 2A orchestrates vascular redox homeostasis via direct transcriptional activation of SIRT1

Abstract

Myocyte enhancer factor 2A (MEF2A), a transcription factor implicated in coronary artery disease, remains unexplored in vascular redox regulation. To address this gap and overcome the limitations of current antioxidant therapies, we investigate the role of MEF2A in oxidative defense via human umbilical vein endothelial cells (HUVECs) and murine models. Adenoviral vectors encoding MEF2A-specific shRNAs or mRNAs are used to silence or overexpress MEF2A in HUVECs. For in vivo validation, endothelial-targeted MEF2A knockdown is achieved via AAV1-shRNA delivery in mice fed with a high-fat diet. Systemic redox status is assessed by measuring reactive oxygen species (ROS), glutathione homeostasis (GSH/GSSG ratio), the NADH/NAD+ balance, the mitochondrial membrane potential (ΔΨm), and 8-hydroxy-2′-deoxyguanosine (8-OHdG). Mechanistic insights are derived from immunofluorescence, qPCR, western blotting, and dual-luciferase reporter assays. MEF2A silencing induces redox imbalance, characterized by elevated ROS, a reduced GSH/GSSG ratio, and ΔΨm collapse. Conversely, MEF2A overexpression synergizes with SIRT1 to restore the glutathione pool, maintain NAD+ homeostasis, and suppress ROS under oxidative stress. Chromatin immunoprecipitation confirms that MEF2A directly binds to two cis-elements in the SIRT1 promoter, driving transcriptional activation. In vivo, MEF2A-deficient mice present increased vascular oxidative damage, as indicated by elevated DNA damage marker (8-OHdG) and ROS levels. The downregulation of SIRT1/PGC-1α in MEF2A-silenced cells is verified in vivo. Our findings establish MEF2A as a master regulator of endothelial redox defense via the SIRT1-PGC-1α axis, providing a mechanistic foundation for the treatment of oxidative cardiovascular disorders. This work suggests that pharmacological MEF2A activation is a novel strategy for precision antioxidant therapy in vascular medicine.

1. Introduction

Oxidative stress is a pathophysiological state characterized by excessive reactive oxygen species (ROS) production overwhelming endogenous antioxidant defenses, and serves as a critical driver of cellular dysfunction and tissue damage in chronic diseases [1]. In the cardiovascular system, this redox imbalance triggers endothelial injury, initiating a cascade of events that culminate in atherosclerosis, hypertension, and ischemic heart disease [2–5]. While ROS are essential signaling molecules at physiological levels, their pathological accumulation induces DNA damage, lipid peroxidation, and mitochondrial impairment, with vascular endothelial cells being particularly vulnerable due to their direct exposure to hemodynamic stressors [6,7].

Vascular endothelial cells, far beyond their traditional role as passive blood vessel linings, function as dynamic biosensors that regulate vascular tone, thromboresistance, and inflammatory responses through paracrine signaling [8]. Emerging evidence positions endothelial redox dysregulation as the “first domino” in atherosclerosis development, where the oxidative inactivation of nitric oxide synergizes with oxidized LDL uptake to drive foam cell formation and plaque progression [8–10]. Despite advances in antioxidant therapies (e.g., vitamins, probucol and related phenols), clinical translation remains hampered by systemic toxicity and the inability to target endothelial-specific pathways [11]. This therapeutic gap underscores the urgency of identifying master transcriptional regulators of endothelial redox homeostasis.

Sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a master regulator of mitochondrial biogenesis, form a critical nexus for redox defense [12]. SIRT1 deacetylates PGC-1α to enhance mitochondrial function and ROS scavenging [13]. Pharmacological activators such as resveratrol improve vascular function [14]; however, their reliance on upstream transcriptional control mechanisms remains unexplored. This gap parallels broader failures of nonspecific antioxidants, highlighting the urgency of defining transcription factors that coordinate mitochondrial quality control and endogenous defenses.

Myocyte enhancer factor 2A (MEF2A), a member of the MADS-box transcription factor family, has emerged as a paradoxical player in cardiovascular biology [15–17]. MEF2A was originally identified for its essential role in muscle development through its regulation of myocyte differentiation and morphogenesis [18], and it has since been shown to perform pleiotropic functions across tissues. In immun...