biostudies-literatureUnknown13Park DD<h4>Introduction</h4>The molecular mechanisms regulating cardiomyocyte (CM) proliferation during heart development are essential for understanding regenerative processes but remain incompletely defined. While adult mammalian CMs are post-mitotic, zebrafish retain proliferative capacity throughout life. We aimed to identify genetic regulators that fine-tune CM proliferation during cardiac development.<h4>Methods</h4>Using an N-ethyl-N-nitrosourea (ENU) mutagenesis screen in zebrafish, we identified the embryonic-lethal mutant <i>heart of stone (hos)</i>, which exhibits cardiac hyperplasia. Genetic mapping revealed a point mutation in <i>smarce1</i>, a component of the SWI/SNF chromatin remodeling complex. We performed morpholino knockdown, mRNA rescue, and Tet-On-driven myocardium-specific Frontiers in cell and developmental biology1636944https://www.ebi.ac.uk/biostudies/studies/S-EPMC12426013biostudies-literatureSmarce1 fine-tunes cardiomyocyte proliferation in the embryonic zebrafish heart.PMC12426013Rottbauer WKrieg LJust SPark DDDahme TfalseSmarce1 fine-tunes cardiomyocyte proliferation in the embryonic zebrafish heart.<h4>Introduction</h4>The molecular mechanisms regulating cardiomyocyte (CM) proliferation during heart development are essential for understanding regenerative processes but remain incompletely defined. While adult mammalian CMs are post-mitotic, zebrafish retain proliferative capacity throughout life. We aimed to identify genetic regulators that fine-tune CM proliferation during cardiac development.<h4>Methods</h4>Using an N-ethyl-N-nitrosourea (ENU) mutagenesis screen in zebrafish, we identified the embryonic-lethal mutant <i>heart of stone (hos)</i>, which exhibits cardiac hyperplasia. Genetic mapping revealed a point mutation in <i>smarce1</i>, a component of the SWI/SNF chromatin remodeling complex. We performed morpholino knockdown, mRNA rescue, and Tet-On-driven myocardium-specific 2025-01-01T00:00:00Z20252026-06-01T12:05:02.14Z2026-04-08T12:05:43.153ZS-EPMC124260134095041010.3389/fcell.2025.1636944