🧬🫀 What if a mitochondrial metabolic defect—not cholesterol alone—drives atherosclerosis? A new study in Nature Communications identifies DDIT4 (REDD1) as a metabolic–epigenetic regulator of vascular smooth muscle cell (VSMC) plasticity, revealing a potential therapeutic strategy for atherosclerosis and restenosis. The central discovery: DDIT4 directly disrupts the pyruvate dehydrogenase complex (PDC), reducing acetyl-CoA production and histone acetylation, thereby driving VSMCs from a contractile to a proliferative, synthetic phenotype. 🔬 1. DDIT4 increases during vascular remodeling Researchers identified DDIT4 through integrated transcriptomic analysis of human coronary artery smooth muscle cells. • PDGF-BB and IL-1β stimulation increased DDIT4 expression. • Repsox-induced differentiation suppressed DDIT4. • DDIT4 increased in mouse neointimal lesions and atherosclerotic plaques. • Higher DDIT4 correlated with greater plaque burden. In Western diet-fed Apoe⁻/⁻ mice: DDIT4 vs. plaque area: r = 0.8619 DDIT4 vs. ACTA2: r = −0.7514 These observations link DDIT4 expression to loss of the contractile VSMC phenotype. ⚡ 2. DDIT4 promotes pathological phenotypic switching DDIT4 overexpression in human coronary artery smooth muscle cells caused: • Contractile markers ACTA2, CNN1, TAGLN, and MYH11 ↓ • Synthetic phenotype markers KLF4 and SPP1 ↑ • Cell proliferation ↑ • Extracellular matrix remodeling programs ↑ Conversely, DDIT4 knockdown restored contractile markers and suppressed proliferation. Interestingly, DDIT4 did not significantly alter mTOR phosphorylation in these VSMCs, suggesting a mechanism distinct from its classical mTOR-inhibitory function. 🧬 3. A newly identified DDIT4–PDC interaction Using BioID2 proximity labeling, mass spectrometry, and co-immunoprecipitation, researchers identified interactions between DDIT4 and three PDC components: PDHA1 | PDHB | DLAT DDIT4 overexpression disrupted interactions among PDC subunits and reduced enzymatic activity. Two DDIT4 mutants, C140A/G141A and K219A/Y222A, showed reduced PDC binding and diminished inhibition of PDC activity. DDIT4 also increased inhibitory PDHA1 phosphorylation and weakened the PDP1–PDHA1 interaction. The metabolic consequences were: PDC activity ↓ → NADH ↓ → Acetyl-CoA ↓ 🔥 4. Metabolic dysfunction rewires the epigenome Acetyl-CoA is not simply a mitochondrial metabolic intermediate. It also supplies acetyl groups for histone acetylation, linking cellular metabolism to gene expression. DDIT4 overexpression reduced: • Global histone H3 acetylation • H3K9ac • H3K27ac CUT&Tag analysis demonstrated reduced acetylation at regulatory regions of contractile phenotype-associated genes, including SRF, CNN1, and CCN5. The proposed mechanism: DDIT4 ↑ → PDC inhibition → Acetyl-CoA ↓ → H3K9ac/H3K27ac ↓ → Contractile gene repression → Synthetic VSMC transition This establishes a mechanistic connection between mitochondrial metabolism and vascular cell identity. 🧪 5. Restoring metabolic–epigenetic signaling rescues VSMCs Researchers tested whether restoring PDC activity or histone acetylation could reverse the effects of DDIT4. PDP1 overexpression: • Reduced inhibitory PDHA1 phosphorylation. • Restored contractile proteins. Acetate supplementation: • Restored histone acetylation. • Increased SRF, CNN1, ACTA2, and related markers. • Suppressed DDIT4-associated VSMC proliferation. The HDAC inhibitor trichostatin A also restored histone acetylation and contractile protein expression. These rescue experiments support the functional importance of the PDC–acetyl-CoA–histone acetylation axis. 🩸 6. Genetic targeting of DDIT4 reduces atherosclerosis in mice The investigators used vascular injury and atherosclerosis models to test DDIT4 function in vivo. DDIT4 overexpression: • Increased neointimal hyperplasia. • Increased atherosclerotic lesion burden. • Reduced VSMC contractile markers. VSMC-specific Ddit4 deletion: • Reduced neointimal formation. • Reduced aortic plaque burden. • Restored ACTA2, CNN1, and TAGLN expression. Importantly, these effects occurred without significant changes in circulating cholesterol, triglycerides, or body weight. This suggests that vascular DDIT4 influences disease progression independently of major systemic lipid changes. 💊 7. Acetate partially reverses DDIT4-driven vascular disease In Apoe⁻/⁻ mice with VSMC-targeted DDIT4 overexpression, sodium acetate supplementation: • Reduced aortic atherosclerotic lesions. • Increased H3K9ac and H3K27ac. • Restored contractile phenotype-associated proteins. These results support metabolic–epigenetic rescue as a potential intervention. However, acetate has additional biological actions, and these experiments do not establish that its protective effects are exclusively mediated through histone acetylation. 🔍 8. Human vascular specimens support clinical relevance Analysis of human atherosclerotic arteries revealed: • DDIT4 ↑ • Inhibitory phospho-PDHA1 ↑ • ACTA2, SRF, and CNN1 ↓ • H3K9ac and H3K27ac ↓ DDIT4 expression also correlated positively with coronary artery stenosis severity in the examined patient cohort. Public transcriptomic datasets independently supported increased DDIT4 expression in atherosclerotic plaques, particularly advanced lesions. These human findings are consistent with the experimental mechanism, although they do not establish causality in patients. 🎯 9. Therapeutic implications The findings suggest several potential strategies: • Selective inhibition of DDIT4 in vascular smooth muscle cells. • Disruption of the DDIT4–PDC interaction. • Restoration of PDC activity. • Modulation of acetyl-CoA availability. • Preservation of contractile gene-associated histone acetylation. An especially interesting possibility is targeting DDIT4–PDC protein interactions rather than globally inhibiting DDIT4, potentially reducing interference with its other stress-response functions. ⚠️ Important limitations The therapeutic evidence remains preclinical. The study did not identify a clinically validated DDIT4 inhibitor. The DDIT4 mutants may affect additional binding partners. Only selected histone acetylation marks were investigated. The long-term safety of manipulating PDC activity or histone acetylation in vascular tissues remains unknown. The broader implication Atherosclerosis is not exclusively a disorder of lipid accumulation and inflammation. It is also a disease of metabolic reprogramming and cellular identity. DDIT4 connects mitochondrial pyruvate metabolism to chromatin regulation, determining whether vascular smooth muscle cells maintain their contractile identity or adopt a pathological synthetic phenotype. Targeting this metabolic–epigenetic interface could provide a complementary therapeutic approach to conventional lipid-lowering treatments. 📄 Li F, Yue B, Xia L, et al. Smooth muscle DDIT4 exacerbates vascular remodeling in atherosclerosis and vascular injury by impairing PDC activity. Nature Communications. 2026. Article in Press. DOI: doi.org/10.1038/s41467-026-7… Research datasets: RNA-seq: GSE311133, GSE310361 CUT&Tag: GSE311116 Proteomics: PXD083369 #Atherosclerosis #DDIT4 #REDD1 #VascularSmoothMuscle #PDC #PDHA1 #AcetylCoA #Epigenetics #HistoneAcetylation #VascularRemodeling #CardiovascularResearch #MetabolicReprogramming #PrecisionMedicine Source: Uploaded original research article, particularly Figures 1–10, including the DDIT4–PDC interaction experiments, metabolic–epigenetic rescue studies, genetic mouse models, and human vascular specimens. s41467-026-79145-w_reference.pdf