PROJECT SUMMARY
This project will test the hypothesis that DNA damage in cardiomyocytes activates p53 leading to mitochondrial
alterations and secretion of paracrine factors that drive heart failure. The premise for this has been established
from our preliminary data and from the work of others. First, DNA damage and activated DNA damage response
(DDR) have been observed in cardiovascular disease (CVD) in humans. Second, studies also show evidence
that multiple cell types in the cardiac unit, including cardiomyocytes (CM) and cardiac fibroblasts (CF) display
markers of DNA damage and cellular senescence in several disease pathologies. Third, we have recently
identified that nuclear DNA damage drives dilated cardiomyopathy. Specifically, cardiomyocyte-depletion of the
DNA repair endonuclease, ERCC1-XPF in mice, upregulates the DNA damage response gene, p53, and leads
to irregular mitochondrial cristae, accumulation of lipids and increased oxidative stress. Additionally, there is an
increase in several cardiac failure and senescence associated markers. However, the exact molecular
underpinnings and cell-specificity of these DNA damage-induced changes is poorly understood. One barrier to
addressing this question in vivo has been lack of appropriate tools, where DNA damage can be introduced in
only one cell type (e.g., CM) and its effect on CF and cardiac function can be investigated. Additionally, 2D cell
culture and co-culture systems fall short, as they cannot reproduce tissue dynamics present in a cardiac unit.
Herein, we have developed several tools enable the study of cell-cell communication of 3D multicellular system.
Specific Aim 1 will map the molecular, functional, and architectural changes upon loss of ERCC1 in CM. In this
aim, we will test the mechanistic role of p53 and reactive oxygen species on a number of cellular and
mitochondrial parameters, as well as cardiomyocyte electrophysiology. Specific Aim 2 will test whether
stochastic, spontaneous DNA damage in the CM or CF drives cardiac electromechanical dysfunction in a cell-
autonomous or cell non-autonomous manner through a paracrine effect on neighboring cells. Here, we will
analyze the pathological secretome upon genotoxic stress, as well as test the role of eliminating senescent cells
on cardiac health. This work is technically innovative as it uses a number of unique tools including concomitant
optical and bioelectrical measurements in 3D cardiac organoids. These contributions will be significant because
DNA damage is unavoidable and intimately linked to cardiac health and disease. Our team is uniquely qualified
to perform this work, with expertise in DNA damage/ repair, cellular senescence, nanofabrication, human iPSC-
derived cardiac tissue engineering, and data science. This analysis, we believe, will increase our fundamental
understanding of the connection between DNA damage and heart disease and potentially pave the way for new
treatment strategies.
