# The Role of Runx1 in Cardiomyocyte Cell Cycle and Ploidy

> **NIH NIH F31** · MEDICAL COLLEGE OF WISCONSIN · 2022 · $46,752

## Abstract

PROJECT SUMMARY
Cardiovascular disease remains the leading cause of death worldwide, necessitating continued research to
develop novel therapeutic strategies. Historically, adult mammalian cardiomyocytes (CMs) were thought to be
post-mitotic and therefore unable to regenerate the myocardium after injury. However, in recent years,
scientists have shown that the adult mammalian CM is capable of a small amount of proliferation, though this
competence is potentially restricted to a subset of cardiomyocytes. Patterson et. al demonstrated using the
hybrid mouse diversity panel that having greater percentages of the rare mononuclear diploid cardiomyocyte
(MNDCM) is associated with improved function, smaller scars, and enhanced CM proliferation after myocardial
infarction. An accompanying genome-wide association analysis identified genetic loci associated with the
frequency of the MNDCM population. One gene to come out of this screen was Runx1. Concurrently, RUNX1
captured the attention of cardiac regeneration researchers due to its increased presence in disease states,
with some suggesting it may be a marker for dedifferentiation (fetal gene induction). CM-specific
overexpression of Runx1 results in a doubling of the MNDCM population, thereby validating its influence on the
population. Via multiple contexts including postnatal development and adult injury, knocking out Runx1
decreases DNA synthesis while overexpressing Runx1 increases DNA synthesis. Furthermore, an initial
analysis of RNA sequencing data demonstrates that RUNX1 overexpression in a neonatal mouse upregulates
known fetal CM genes and markers of CM cell cycle activity. These preliminary data are supported by the
literature, which has shown in many other tissues that RUNX1, a transcription factor, directly regulates many
genes associated with the cell cycle, indicating that RUNX1's role may be highly conserved across cell types.
The central hypothesis of this study is that Runx1 regulates the CM response to heart failure via transcriptional
induction of fetal genes and cell cycle activity. To test this idea the work proposed here will utilize both gain-
and loss-of-function Runx1 mouse models temporally controlled by a CM-specific Cre. Aim 1 will investigate
the effect of Runx1 on post-infarction outcomes and CM cell cycle. Aim 2 will assess transcriptional control of
RUNX1 through two complementary genome-wide approaches: RNA sequencing and CUT&Tag. Results from
this study will further advance the field's understanding of the genetic components involved during a cardiac
injury and improve future treatment strategies.

## Key facts

- **NIH application ID:** 10386330
- **Project number:** 1F31HL162468-01
- **Recipient organization:** MEDICAL COLLEGE OF WISCONSIN
- **Principal Investigator:** Samantha K Swift
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $46,752
- **Award type:** 1
- **Project period:** 2022-02-01 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10386330

## Citation

> US National Institutes of Health, RePORTER application 10386330, The Role of Runx1 in Cardiomyocyte Cell Cycle and Ploidy (1F31HL162468-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10386330. Licensed CC0.

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