CBX3 encodes heterochromatin protein 1 gamma, the major isoform of a family of proteins that reads repressive chemical marks on histones, the spools around which DNA is wound. By binding to methylated histone marks such as H3K9, H1K26, and modified G9a peptides, CBX3 helps to condense stretches of DNA into constitutive heterochromatin, a tightly packed configuration that stabilizes chromosomes and keeps inappropriate genes switched off. In the vascular wall, this silencing function matters enormously: misplaced expression of pro-inflammatory cytokines and growth factors in vascular tissue can drive atherogenesis and pathological remodeling, so a protein that locks such genes down has obvious protective potential. The review emphasizes that this is not a static role, because CBX3 subfragments have been shown to display anti-silencing activity in pluripotent cells that disappears upon differentiation, meaning the protein’s regulatory output depends intimately on cellular state.

The most striking cardiovascular findings concern vascular smooth muscle cells, the cells whose proliferation, migration, and conversion into a synthetic, proliferative state drive neointima formation, the thickening of the vessel wall that underlies restenosis after angioplasty and contributes to atherosclerosis. Studies cited in the review show that CBX3 suppresses vascular smooth muscle cell proliferation, migration, and neointima formation largely through the Notch3 pathway, a signaling cascade central to vascular development and repair. By transcriptionally repressing Notch3 signaling, CBX3 modulates key smooth muscle cell phenotypes, including expression of contractile genes such as smooth muscle myosin heavy chain, calponin, and smooth muscle alpha-actin 2. CBX3 also binds promoter regions of these contractile genes and facilitates signaling through diaphanous homolog 1 and serum response factor, nudging the cells toward a differentiated, contractile identity while reducing expression of collagen genes col1a1 and col4a1.

Animal experiments add weight to the story. CBX3 expression was markedly enhanced in the neointima of rat carotid arteries after injury, and, conversely, silencing CBX3 in a mouse model of carotid artery injury decreased neointimal hyperplasia and vascular remodeling, a finding the authors interpret as evidence that carefully timed CBX3 modulation could become a therapeutic strategy against restenosis. A separate line of work on transfer RNA-derived stress-induced fragments found that a small RNA called tiRNA-Gly-GCC is upregulated in synthetic vascular smooth muscle cells and atherosclerotic tissue, and that blocking its activity through CBX3 promoted retention of the myogenic phenotype, reduced smooth muscle cell proliferation and migration, and diminished neointima formation after vascular injury.

Beyond smooth muscle, the review documents CBX3’s reach into the epigenetic regulation of microRNAs with established cardiovascular functions. CBX3 represses miR-21, a pro-fibrotic and pro-inflammatory microRNA whose silencing in cardiac fibroblasts diminishes fibrosis and adverse remodeling under stress, and it also regulates miR-126, an endothelial microRNA essential for vascular integrity and angiogenic signaling. In neural progenitor cells, CBX3 binding upregulates cardiac lineage genes including TNNT3, TBX20, TBX3, and HAND1, while its knockdown shifts differentiation toward mesodermal and circulatory-system programs through genes such as WNT4, hinting at a role in cardiovascular development itself. Loss of CBX3 also reduces recruitment of the transcriptional kinase CDK8 to cardiovascular development genes, reinforcing its position within an intricate gene-regulatory network.

One of the review’s most provocative threads links CBX3 to lipid genetics through the ABCG1 locus. Methylation changes at a specific CpG site within ABCG1, cg27243685, have been associated with elevated triglycerides, increased risk of new-onset coronary heart disease, and a history of myocardial infarction in studies including the Framingham Heart Study. A minor allele of the intronic variant rs4148086 increases methylation at this site and lowers ABCG1 expression in blood, illustrating how tiny genomic regions can shape cardiovascular risk through DNA methylation. The authors also connect altered CBX3 activity to ApoC3 expression, whose overexpression promotes atherogenesis, and to metabolic regulation relevant to type 2 diabetes, a disease that shares genetic predispositions with cardiovascular conditions.

Perhaps most striking is the emerging intersection with cancer, particularly lung cancer. Cardiovascular disease and lung cancer share risk factors including smoking, hypertension, diabetes, aging, and obesity, and epidemiological cohorts from Nordic and European countries show that a history of cardiovascular disease raises the risk of subsequent lung cancer, apparently through shared channels of inflammation, oxidative stress, and endothelial dysfunction. CBX3 is overexpressed in many tumor types and correlates with poor prognosis, and its binding is associated with increased acetylation of histones H3 and H4, marks of active transcription tied to cellular senescence. The same proliferative machinery that CBX3 drives in cancer cells could, the review suggests, contribute to loss of cell-cycle checkpoint control and premature senescence in cardiovascular cells, while silencing CBX3 induces G0/G1 cell-cycle arrest and early apoptosis. Shared programs of metabolic reprogramming and pathological angiogenesis in failing hearts and tumors round out a picture in which CBX3-relevant pathways could inform combined treatment strategies for patients with both diseases.

The immune dimension is equally consequential. CBX3 expression correlates with immune cell infiltration across tumor types and positively with T helper, T memory, gamma-delta, and Th2 cells, and it alters the function of CD8-positive effector memory T cells by inducing sustained increases of LEF-1 and IL-21R. Within the artery wall, the review proposes that CBX3 could influence monocyte, macrophage, and lymphocyte accumulation, foam cell formation, and plaque stability. It also prevents activation of the NLRP3 inflammasome, a key innate immune sensor triggered by cholesterol crystals abundant in atherosclerotic lesions, thereby reducing release of the inflammatory messenger IL-1beta. Notably, patients treated with immune checkpoint inhibitors face roughly three-fold higher rates of atherosclerotic events and aortic plaque progression, and because CBX3 promotes TGF-beta signaling by inhibiting SMURF2 in pancreatic cancer, the authors speculate that selective CBX3 inhibition might help stabilize vulnerable plaques in such high-risk patients.

Translational prospects are emerging in parallel. Epigenetic drugs are already being tested in cardiology, exemplified by the BET-onMACE Phase 3 trial of the BET-protein inhibitor apabetalone, and histone deacetylases and acetyltransferases are recognized as principal epigenetic regulators of heart health. CBX3-directed strategies could range from small-molecule inhibitors and RNA interference to approaches that boost CBX3 where its activity is protective, potentially combined with stem cell transplantation to repair infarcted myocardium. The authors stress that major gaps remain, including CBX3’s effects on endothelial function and on immune infiltration of the arterial wall, and that next-generation sequencing and network analyses, such as the identification of roughly fifty CBX3-binding proteins, should clarify its molecular partnerships. As cardiovascular medicine pivots toward precision approaches, and as traditional risk models still miss at-risk individuals, this unassuming heterochromatin protein may prove to be far more than a chromosome caretaker: it could be a molecular barometer of vascular health and a lever for treating the world’s leading cause of death.

Subject of Research: The role of the epigenetic regulator CBX3 in cardiovascular disease mechanisms and its potential as a biomarker and therapeutic target

Article Title: Uncovering the significance of CBX3 as an up-and-coming biomarker in cardio-vascular health

Article References: Wahab, M. A., Gaudio, N. D., Gargiulo, B., Quagliariello, V., Maurea, N., Grieco, M., Benedetti, R., Nebbioso, A., Altucci, L., & Conte, M. (2025). Uncovering the significance of CBX3 as an up-and-coming biomarker in cardio-vascular health. Epigenetics Communications, 5(1), Article 1. https://doi.org/10.1186/s43682-024-00032-w

Image Credits: AI Generated

DOI: 10.1186/s43682-024-00032-w

Keywords: CBX3, cardiovascular disease, epigenetics, heterochromatin protein 1, vascular smooth muscle cells, Notch3 pathway, atherosclerosis, neointima formation, inflammation, NLRP3 inflammasome, biomarkers, vascular remodeling