The MEF2A transcription factor interactome in cardiomyocytes

Abstract

Transcriptional regulators encoded by the Myocyte Enhancer Factor 2 (MEF2) gene family play a fundamental role in cardiac development, homeostasis and pathology. Previous studies indicate that MEF2A protein-protein interactions serve as a network hub in several cardiomyocyte cellular processes. Based on the idea that interactions with regulatory protein partners underly the diverse roles of MEF2A in cardiomyocyte gene expression, we undertook a systematic unbiased screen of the MEF2A protein interactome in primary cardiomyocytes using an affinity purification-based quantitative mass spectrometry approach. Bioinformatic processing of the MEF2A interactome revealed protein networks involved in the regulation of programmed cell death, inflammatory responses, actin dynamics and stress signaling in primary cardiomyocytes. Further biochemical and functional confirmation of specific protein-protein interactions documented a dynamic interaction between MEF2A and STAT3 proteins. Integration of transcriptome level data from MEF2A and STAT3-depleted cardiomyocytes reveals that the balance between MEF2A and STAT3 activity exerts a level of executive control over the inflammatory response and cardiomyocyte cell survival and experimentally ameliorates Phenylephrine induced cardiomyocyte hypertrophy. Lastly, we identified several MEF2A/STAT3 co-regulated genes, including the MMP9 gene. Herein, we document the cardiomyocyte MEF2A interactome, which furthers our understanding of protein networks involved in the hierarchical control of normal and pathophysiological cardiomyocyte gene expression in the mammalian heart.

FoxP1 Represses MEF2A in Striated Muscle

“…Finally, it has been previously documented that there is an upregulation of MEF2A activity in cardiac hypertrophic conditions (Moustafa et al, 2023). Therefore, we hypothesized that the depletion of FOXP1 might enhance the hypertrophic cardiomyocyte phenotype due to derepression of MEF2A activity.…”

“…In this MEF2A interactome study, we have identified a novel MEF2A binding protein, FOXP1, that negatively regulates MEF2A transcriptional activity during myogenesis and striated muscle maintenance. Previous research has begun to characterize the role of MEF2A in activating transcription for muscle-specific genes and cardiomyocyte survival (Moustafa et al, 2023). In addition, while MEF2 isoforms share a conserved MADS-box domain and MEF2 domain, the transactivation domain confers a wide range of specificity and function through post-translational modifications.…”

“…Mass spectrometry is a common high-throughput used to study protein interactions (Moustafa et al, 2023). To perform MS experiments, samples of interest are digested and purified, fragmented, and captured by mass spectrometers.…”

“…While the role of MEF2 proteins as transcriptional switches and their numerous cofactors have been well documented in various tissues (Moustafa et al, 2023;Mughal et al, 2015), a comprehensive proteomic analysis to establish a network of binding partners in skeletal muscle remains outstanding. Here, we aimed to construct an interactome network using a GFP-nanobody trap affinity purification in tandem with LC-MS/MS to identify proteins interacting with MEF2A in skeletal muscle.…”

Focal Adhesion’s Role in Cardiomyocytes Function: From Cardiomyogenesis to Mechanotransduction

“…During the formation of costameres, an additional fundamental element, myocyte enhancer factor 2A (Mef2A), is involved [64]. Mef2A belongs to a family of transcription factors that regulate muscle differentiation, and it is crucial for maintaining structural integrity and supporting cell survival during the early stages of costamere differentiation [65]. Following positive regulation through FAK-mediated phosphorylation, Mef2A exerts transcriptional control over different genes encoding proteins localized within the cytoskeletal structure.…”