ZBTB16 Gene in Heart Vessels Acts as a Brake on Cardiac Aging
A transcription factor in endothelial cells declines with age and its loss drives fibrosis, hypertrophy, and diastolic dysfunction — but restoring it reverses damage.
Summary
Scientists at Goethe University Frankfurt discovered that a gene called ZBTB16 — active in the cells lining heart blood vessels — dramatically declines with aging in both humans and mice. When this gene is deleted in young mice, their hearts rapidly develop hallmarks of old age: stiffness, scarring, abnormal enlargement, and loss of nerve fibers. Conversely, when ZBTB16 was restored in aged mice using a gene therapy approach, heart function measurably improved and fibrosis was reduced. The protein works partly by suppressing a downstream target called NRIP1, which otherwise activates scar-forming cells. The findings open a new therapeutic angle for age-related heart disease by targeting the vascular niche rather than heart muscle cells directly.
Detailed Summary
Cardiovascular disease is the leading cause of death in older adults, and while cardiac aging involves multiple cell types, the role of endothelial cells — which line every blood vessel — has been underappreciated. Researchers at the Institute of Cardiovascular Regeneration, Goethe University Frankfurt, conducted a comprehensive multi-omic investigation of aged hearts to identify epigenetically regulated mechanisms driving endothelial dysfunction. Their central discovery: the transcription factor ZBTB16 is robustly expressed in young endothelial cells but is progressively silenced with aging, and this silencing is mechanistically linked to the cardiac deterioration that defines cardiovascular aging.
The team performed single-nucleus ATAC-seq (snATAC-seq) and single-nucleus RNA-seq (snRNA-seq) on cardiac tissue from young (3-month-old) and aged (24-month-old) mice, as well as analysis of human cardiac single-cell datasets. Chromatin accessibility at the ZBTB16 locus was significantly reduced in aged endothelial cells in both species, and transcriptomic data confirmed corresponding decreases in ZBTB16 mRNA expression. This convergent evidence across species established ZBTB16 as an age-regulated epigenetic target specifically in the cardiac vascular niche.
To probe causality, the investigators generated two genetic loss-of-function models: Zbtb16-haploinsufficient mice (heterozygous global deletion) and endothelial-specific Zbtb16 knockout mice. Both models, despite being young adults, developed cardiac phenotypes characteristic of natural aging — diastolic dysfunction as measured by echocardiography, increased cardiac fibrosis (elevated collagen deposition), cardiomyocyte hypertrophy, reduced capillary density, and diminished sympathetic nerve fiber density. These findings in young knockout animals essentially phenocopied aged wild-type hearts, confirming that ZBTB16 loss is sufficient to drive premature cardiac aging.
Mechanistic in vitro studies revealed that endothelial cells lacking ZBTB16 secrete a pro-fibrotic, pro-inflammatory secretome (a senescence-associated secretory phenotype, or SASP). Conditioned medium from ZBTB16-deficient ECs activated cardiac fibroblasts (promoting myofibroblast transformation), induced cardiomyocyte hypertrophy, and impaired sympathetic neuron sprouting — recapitulating the in vivo phenotypes. The researchers identified nuclear receptor-interacting protein 1 (NRIP1) as a key downstream effector: ZBTB16 normally suppresses NRIP1 expression, and when ZBTB16 is lost, NRIP1 rises and drives fibroblast activation and fibrotic signalling. Additionally, the axon-guidance molecule EFNB2 was reduced in ZBTB16-deficient ECs, explaining the defect in neuronal sprouting.
Critically, the study demonstrated therapeutic reversibility. Overexpression of ZBTB16 in senescent ECs in vitro reduced SASP markers and reversed fibroblast activation. In aged mice, cardiac-targeted AAV9-mediated overexpression of Zbtb16 significantly improved diastolic function, reduced cardiac fibrosis, and attenuated hypertrophic remodelling compared to aged controls receiving a control vector. These results establish that restoring ZBTB16 expression — even in already-aged tissue — is sufficient to meaningfully improve cardiac function, suggesting translational potential as a gene therapy or small-molecule target for age-related heart disease.
Key Findings
- ZBTB16 chromatin accessibility and mRNA expression were significantly reduced in endothelial cells of aged (24-month) mouse hearts and confirmed down-regulated in human aged cardiac single-cell datasets
- Young Zbtb16-haploinsufficient and endothelial-specific knockout mice developed diastolic dysfunction, cardiac fibrosis, capillary rarefaction, and reduced sympathetic nerve fiber density — a premature aging cardiac phenotype
- Conditioned medium from ZBTB16-deficient endothelial cells activated cardiac fibroblasts into myofibroblasts, induced cardiomyocyte hypertrophy, and impaired sympathetic neuron sprouting in vitro
- NRIP1 was identified as a key downstream target suppressed by ZBTB16; its elevation upon ZBTB16 loss drives pro-fibrotic fibroblast signalling in the cardiac niche
- EFNB2 (ephrin-B2) was reduced in ZBTB16-deficient endothelial cells, mechanistically linking ZBTB16 loss to impaired nerve fiber density in the aging heart
- AAV9-mediated overexpression of Zbtb16 in aged mice reversed diastolic dysfunction, reduced cardiac fibrosis, and attenuated cardiomyocyte hypertrophy compared to aged controls
- Overexpression of ZBTB16 in senescent endothelial cells in vitro reduced pro-inflammatory and pro-fibrotic secretome markers, reversing SASP-associated paracrine dysfunction
Methodology
The study combined snATAC-seq and snRNA-seq on young (3-month) and aged (24-month) mouse hearts, alongside human cardiac single-cell datasets, to identify ZBTB16 as an age-regulated endothelial transcription factor. Genetic models included global Zbtb16-haploinsufficient mice and endothelial-specific Zbtb16 knockout mice for loss-of-function phenotyping, with echocardiography, histology, and immunofluorescence used to quantify cardiac structure and function. In vitro mechanistic assays used conditioned medium transfer experiments to assess paracrine effects of ZBTB16-deficient or ZBTB16-overexpressing ECs on fibroblasts, cardiomyocytes, and neurons. Therapeutic overexpression was achieved via AAV9 cardiac gene delivery in aged mice, with functional endpoints including diastolic function parameters and fibrosis quantification.
Study Limitations
The study is primarily preclinical, conducted in mice, and while human single-cell RNA-seq data confirmed ZBTB16 down-regulation, direct functional human data or clinical trial evidence is absent. The AAV9 overexpression approach delivers supraphysiological ZBTB16 levels, and the long-term safety, optimal dosing, and systemic off-target effects of such gene therapy have not been characterized. The authors do not report potential conflicts of interest in the available full text, and the precise upstream epigenetic mechanism driving ZBTB16 silencing during aging remains to be fully elucidated.
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