Poster abstracts
Poster number 171 submitted by Uday K. Baliga
Upstream open reading frame inactivation augments GATA4 translation and cardiomyocyte hypertrophy in mice
Uday K. Baliga (Department of Medicine, University of Rochester School of Medicine and Dentistry), Omar M Hedaya (Department of Medicine, University of Rochester School of Medicine and Dentistry), Feng Jiang (Department of Medicine, University of Rochester School of Medicine and Dentistryntistry), Yui Kawakami (Department of Medicine, University of Rochester School of Medicine and Dentistry), Si Chen (Department of Medicine, University of Rochester School of Medicine and Dentistry), Peng Yao (Department of Medicine, University of Rochester School of Medicine and Dentistry)
Abstract:
Upstream open reading frames (uORFs) are short peptide-encoding sequences residing in the 5' untranslated region (5' UTR) of mRNAs, enabling translational repression of main (m)ORFs. More than 50% of mRNAs harbor at least one uORF in humans. However, our comprehension of the biological function of uORFs remains limited. This study aims to elucidate the role of the uORF in the 5' UTR of the Gata4 gene in the context of cardiac biology. Our work demonstrates the role of the 5’ Gata4 uORF and its adjacent downstream double-stranded RNA (dsRNA) sequence to antagonize the main (m)ORF translation for the GATA4 (GATA binding protein 4) gene in human and mouse cardiomyocytes. We generated a mouse model with a non-functional uORF start codon in the Gata4 gene. These Gata4-ΔuORF mice manifest spontaneous cardiac hypertrophy without apparent fibrosis during aging. As shown by echocardiography, heart weight/tibia length, and wheat germ agglutinin or picrosirius red staining of Gata4-ΔuORF and WT mouse heart sections at 12 months. Single-nucleus RNA sequencing unveiled significant transcriptional variations between wild-type and Gata4-ΔuORF mice. Notably, mRNAs linked to sarcomeric and contractile functions had increased expression, mirroring the observed cardiac hypertrophy. We also used single-nucleus transposase-accessible chromatin (snATAC)-seq to probe alterations in chromatin accessibility. snATAC-seq revealed improved chromatin accessibility within transcription-regulatory elements associated with amplified gene transcription. These putative cis-regulatory elements (pCREs) are significantly enriched in MEF2 binding motifs. In vitro luciferase reporter assays confirmed the regulatory potential of three of these pCREs. These findings shed light on the role of the uORF in regulating GATA4 protein expression and inducing cardiomyocyte hypertrophy.
Keywords: GATA4, uORF, Heart