Continuous live imaging reveals a subtle pathological alteration with cell behaviors in congenital heart malformation.

To form fully functional four-chambered structure, mammalian heart development undergoes a transient finger-shaped trabeculae, crucial for efficient contraction and exchange for gas and nutrient. Although its developmental origin and direct relevance to congenital heart disease has been studied extensively, the time-resolved cellular mechanism underlying hypotrabeculation remains elusive. Here, we employed live imaging and reconstructed the holistic cell lineages and cellular behavior landscape of control and hypotrabeculed hearts of mouse embryos from E9.

Long-term, in toto live imaging of cardiomyocyte behaviour during mouse ventricle chamber formation at single-cell resolution.

Mapping of the holistic cell behaviours sculpting the four-chambered mammalian heart has been a goal or previous studies, but so far only success in transparent invertebrates and lower vertebrates with two-chambered hearts has been achieved. Using a live-imaging system comprising a customized vertical light-sheet microscope equipped with a mouse embryo culture module, a heartbeat-gated imaging strategy and a digital image processing framework, we realized volumetric imaging of developing mouse hearts at single-cell resolution and with uninterrupted cell lineages for up to 1.5 d.

The lncRNA / locus orchestrates heart development through regulation of precise expression of .

Exploration and dissection of potential actions and effects of long noncoding RNA (lncRNA) in animals remain challenging. Here, using multiple knockout mouse models and single cell RNA sequencing, we demonstrate that the divergent lncRNA / has a key complex modulatory effect on the expression of its neighboring gene and subsequently on heart development and function. Short deletion of the promoter in mouse diminishes transcription to ∼8-32%, but fails to affect 2 expression and yields no discernable heart phenotypes.

Single-Cell Transcriptomics Reveals Chemotaxis-Mediated Intraorgan Crosstalk During Cardiogenesis.

Rationale: We hypothesized that the differentiation processes of cardiac progenitor cell (CP) from first and second heart fields (FHF and SHF) may undergo the unique instructive gene regulatory networks or signaling pathways, and the precise SHF progression is contingent on the FHF signaling developmental cues.

Objective: We investigated how the intraorgan communications control sequential building of discrete anatomic regions of the heart at single-cell resolution.

Methods And Results: By single-cell transcriptomic analysis of Nkx2-5 (NK2 homeobox 5) and Isl1 (ISL LIM homeobox 1) lineages at embryonic day 7.

Replication-Independent Histone Turnover Underlines the Epigenetic Homeostasis in Adult Heart.

Rationale: Replication-independent histone turnover has been linked to cis-regulatory chromatin domains in cultured cell lines, but its molecular underpinnings and functional relevance in adult mammalian tissues remain yet to be defined.

Objective: We investigated regulatory functions of replication-independent histone turnover in chromatin states of postmitotic cardiomyocytes from adult mouse heart.

Methods And Results: We used H2B-GFP (histone 2B-green fluorescent protein) fusion protein pulse-and-chase approaches to measure histone turnover rate in mouse cardiomyocytes.

Divergent Requirements for EZH1 in Heart Development Versus Regeneration.

Rationale: Polycomb repressive complex 2 is a major epigenetic repressor that deposits methylation on histone H3 on lysine 27 (H3K27me) and controls differentiation and function of many cells, including cardiac myocytes. EZH1 and EZH2 are 2 alternative catalytic subunits with partial functional redundancy. The relative roles of EZH1 and EZH2 in heart development and regeneration are unknown.

EED orchestration of heart maturation through interaction with HDACs is H3K27me3-independent.

In proliferating cells, where most Polycomb repressive complex 2 (PRC2) studies have been performed, gene repression is associated with PRC2 trimethylation of H3K27 (H3K27me3). However, it is uncertain whether PRC2 writing of H3K27me3 is mechanistically required for gene silencing. Here, we studied PRC2 function in postnatal mouse cardiomyocytes, where the paucity of cell division obviates bulk H3K27me3 rewriting after each cell cycle.