# GJA1-20K is a new regulator of actin dynamics and myocardial cell-cell coupling

> **NIH NIH F31** · CEDARS-SINAI MEDICAL CENTER · 2021 · $12,667

## Abstract

PROJECT SUMMARY – ABSTRACT
 Heart disease is the leading cause of the death in the United States. In the heart,
Connexin 43 (Cx43) gap junctions are integral to healthy heart function and
synchronized muscle contraction by allowing ion passage between cardiomyocytes.
Cx43 is encoded by the GJA1 gene in a single coding exon, but GJA1 mRNA contains
six internal methionine start sites, which encode six small isoforms of Cx43 that retain
the same C-terminus tail. GJA1-20k, the 20 kDa isoform, is the most abundantly
expressed, and the Shaw laboratory has discovered that it is necessary for trafficking
Cx43 along microtubules from the nucleus to the cell membrane.
 Recent work from our group shows that the actin cytoskeleton is also required for
Cx43 trafficking, both as cargo rest stops and for proper microtubule orientation to the
cell membrane. We have also shown that GJA1-20k expression in both HeLa cells and
cardiomyocytes results in an increase in total and thicker actin fibers in the cell and
stabilizes actin filaments against Latrunculin A treatment, but a direct interaction
between GJA1-20k and actin has never been studied.
 In Aim 1, I will utilize cell free TIRF imaging of actin dynamics to uncover the role
of GJA1-20k as an actin binding protein. I will use mutagenesis to find the binding site
between GJA1-20k and actin. In Aim 2, I will use isolated cardiomyocytes to see how
GJA1-20k mediated actin stabilization protects the formation and function of gap
junction plaques. These results will uncover GJA1-20k as a novel actin binding protein
and provide better understanding of how GJA1-20k utilizes its interaction with actin to
protect gap junction plaque formation in the heart.

## Key facts

- **NIH application ID:** 10136707
- **Project number:** 5F31HL147404-03
- **Recipient organization:** CEDARS-SINAI MEDICAL CENTER
- **Principal Investigator:** Rachel Baum
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $12,667
- **Award type:** 5
- **Project period:** 2019-04-01 → 2021-09-07

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10136707

## Citation

> US National Institutes of Health, RePORTER application 10136707, GJA1-20K is a new regulator of actin dynamics and myocardial cell-cell coupling (5F31HL147404-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10136707. Licensed CC0.

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