Regulation of sarcomere formation and function in the healthy heart requires a titin intronic enhancer.

Autor:	Kim Y; Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, United States of America., Kim SW; Department of Genetics, Harvard Medical School, Boston, United States of America., Saul D; Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, United States of America., Neyazi M; Department of Genetics, Harvard Medical School, Boston, United States of America., Schmid M; Department of Genetics, Harvard Medical School, Boston, United States of America., Wakimoto H; Department of Genetics, Harvard Medical School, Boston, United States of America., Slaven N; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, United States of America., Lee JH; Department of Biomedical Engineering, Boston University, Boston, United States of America., Layton OG; Department of Genetics, Harvard Medical School, Boston, United States of America., Wasson LK; Department of Genetics, Harvard Medical School, Boston, United States of America., Letendre JH; Department of Biomedical Engineering, Boston University, Boston, United States of America., Xiao F; Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, United States of America., Ewoldt JK; Department of Biomedical Engineering, Boston University, Boston, United States of America., Gkatzis K; Ksilink, Strasbourg, France., Sommer P; Ksilink, Strasbourg, France., Gobert B; Ksilink, Strasbourg, France., Wiest-Daesslé N; Ksilink, Strasbourg, France., McAfee Q; Cardiovascular Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America., Singhal N; Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, United States of America., Lun M; Department of Genetics, Harvard Medical School, Boston, United States of America., Gorham JM; Department of Genetics, Harvard Medical School, Boston, United States of America., Arany Z; Cardiovascular Institute, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America., Sharma A; Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, United States of America., Toepfer CN; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom., Oudit GY; Department of Medicine, University of Alberta, Edmonton, Canada., Pu WT; Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, United States of America., Dickel DE; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, United States of America., Pennacchio LA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, United States of America., Visel A; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, United States of America., Chen CS; Department of Biomedical Engineering, Boston University, Boston, United States of America., Seidman JG; Department of Genetics, Harvard Medical School, Boston, United States of America., Seidman CE; Department of Genetics, Harvard Medical School, Boston, United States of America.
Jazyk:	angličtina
Zdroj:	The Journal of clinical investigation [J Clin Invest] 2024 Dec 17. Date of Electronic Publication: 2024 Dec 17.
DOI:	10.1172/JCI183353
Abstrakt:	Heterozygous truncating variants in the sarcomere protein titin (TTN) are the most common genetic cause of heart failure. To understand mechanisms that regulate abundant cardiomyocyte TTN expression we characterized highly conserved intron 1 sequences that exhibited dynamic changes in chromatin accessibility during differentiation of human cardiomyocytes from induced pluripotent stem cells (hiPSC-CMs). Homozygous deletion of these sequences in mice caused embryonic lethality while heterozygous mice demonstrated allele-specific reduction in Ttn expression. A 296 bp fragment of this element, denoted E1, was sufficient to drive expression of a reporter gene in hiPSC-CMs. Deletion of E1 downregulated TTN expression, impaired sarcomerogenesis, and decreased contractility in hiPSC-CMs. Site-directed mutagenesis of predicted NKX2-5- and MEF2-binding sites within E1 abolished its transcriptional activity. Embryonic mice expressing E1 reporter gene constructs validated in vivo cardiac-specific activity of E1 and the requirement for NKX2-5 and MEF2 binding sequences. Moreover, isogenic hiPSC-CMs containing a rare E1 variant in the predicted MEF2 binding motif that was identified in a patient with unexplained DCM showed reduced TTN expression. Together these discoveries define an essential, functional enhancer that regulates TTN expression. Manipulation of this element may advance therapeutic strategies to treat DCM caused by TTN haploinsufficiency.
Databáze:	MEDLINE
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