Growth Arrest and DNA Damage-Inducible 45 Gamma Knockdown Attenuates Cadmium-Induced Endothelial Dysfunction in...

Atherosclerosis (AS), driven by endothelial dysfunction, is exacerbated by environmental cadmium (Cd²⁺). This study elucidates the molecular mechanism by which Cd²⁺ promotes AS, focusing on the role of growth arrest and DNA damage-inducible 45 gamma (GADD45G). Clinical correlation between plaque Cd²⁺ levels and plaque burden was assessed in human samples. In vivo studies utilized apolipoprotein E-deficient (ApoE^-⁄-) mice fed a high-fat diet (HFD) with varying cadmium chloride (CdCl₂) doses. In vitro analyses employed human umbilical vein endothelial cells (HUVECs) treated with CdCl₂, combined with siRNA knockdown, MEKK4 overexpression plasmids, and pharmacological agonists. GADD45G^-/- zebrafish were generated and exposed to HFD and CdCl₂. Functional assays included cell viability, apoptosis, migration, tube formation, inflammation, lipid deposition (Oil Red O), and molecular analyses. Cd²⁺ concentration positively correlated with plaque area in humans and dose-dependently increased plaque burden in ApoE^-⁄- mice. CdCl₂ upregulated GADD45G expression and activated the MEKK4-p38MAPK pathway in HUVECs. GADD45G knockdown attenuated CdCl₂-induced endothelial apoptosis, impaired migration and angiogenesis, and reduced inflammation and MAPK pathway activation. These protective effects were reversed by the p38MAPK agonist anisomycin or by MEKK4 overexpression. In zebrafish, CdCl₂ exacerbated HFD-induced vascular lipid deposition and inflammatory gene expression. GADD45G knockout mitigated these effects induced by HFD, which were reversed by CdCl₂ co-exposure. Cd²⁺ exacerbates AS by inducing endothelial dysfunction via GADD45G-mediated activation of the MEKK4-p38MAPK signaling axis. Thus, the GADD45G-MEKK4-p38MAPK axis represents a novel therapeutic target for mitigating Cd²⁺-associated cardiovascular risk.