Abstract 19018: Unraveling the Regulatory Landscape of NKX2-5 in Human Left Atrial Tissue: Implications for Atrial Fibrillation

Abstract

Cardiac transcription factors are emerging as crucial modulators of atrial fibrillation (AF), with rare and common variation implicated in AF. Mutations in NKX2-5 and more recently, NFATC1 were reported in families with autosomal dominant young-onset AF. Here, we explore the landscape of NKX2-5 and NFATC1 in human left atrium, using Chromatin Immunoprecipitation Sequencing (ChIP-seq), DAVID functional annotation and HOMER motif analyses. Post-mortem human left atrial tissue samples (n=5) were obtained from the National Disease Research Interchange (NDRI) within a recovery interval of < 4 hours. Preserved microstructural integrity and normal staining patters for TNNT2 and vimentin were verified using confocal microscopy. ChIP-seq analysis revealed an average of 2.62k NKX2-5 binding peaks, with 118 genes bound in all samples. Functional analysis identified significant enrichment in gene ontology categories and pathways (Table 1), including adrenergic and PPAR signaling pathways known to participate in AF susceptibility. Using HOMER, we mapped 55 NFATC1 consensus binding sites to the NKX2-5 ChIP peaks. Two NFATC1 consensus sites localized to an NKX2-5 binding peak located upstream from MEF2A (Figure 1). Published HI-C data from human right atrium indicates the NFATC1 binding sites are adjacent to the promoter of MEF2A in 3D space, suggesting that NKX2-5 and NFATC1 co-regulate MEF2A. In murine atria, mef2A regulates genes involved in fibrosis and adhesion, processes that are crucial in the pathogenesis of atrial fibrillation. Our data, together with published literature, provide a framework for understanding transcriptional networks that may predispose to human AF.