@article {112, title = {Dynamics of cardiomyocyte transcriptome and chromatin landscape demarcates key events of heart development.}, journal = {Genome Res}, volume = {29}, year = {2019}, month = {2019 03}, pages = {506-519}, abstract = {

Organogenesis involves dynamic regulation of gene transcription and complex multipathway interactions. Despite our knowledge of key factors regulating various steps of heart morphogenesis, considerable challenges in understanding its mechanism still exist because little is known about their downstream targets and interactive regulatory network. To better understand transcriptional regulatory mechanism driving heart development and the consequences of its disruption in vivo, we performed time-series analyses of the transcriptome and genome-wide chromatin accessibility in isolated cardiomyocytes (CMs) from wild-type zebrafish embryos at developmental stages corresponding to heart tube morphogenesis, looping, and maturation. We identified genetic regulatory modules driving crucial events of heart development that contained key cardiac TFs and are associated with open chromatin regions enriched for DNA sequence motifs belonging to the family of the corresponding TFs. Loss of function of cardiac TFs Gata5, Tbx5a, and Hand2 affected the cardiac regulatory networks and caused global changes in chromatin accessibility profile, indicating their role in heart development. Among regions with differential chromatin accessibility in mutants were highly conserved noncoding elements that represent putative enhancers driving heart development. The most prominent gene expression changes, which correlated with chromatin accessibility modifications within their proximal promoter regions, occurred between heart tube morphogenesis and looping, and were associated with metabolic shift and hematopoietic/cardiac fate switch during CM maturation. Our results revealed the dynamic regulatory landscape throughout heart development and identified interactive molecular networks driving key events of heart morphogenesis.

}, keywords = {Animals, Cells, Cultured, Chromatin, Chromatin Assembly and Disassembly, Gene Expression Regulation, Developmental, Gene Regulatory Networks, Heart, Myocytes, Cardiac, Transcription Factors, Transcriptome, Zebrafish, Zebrafish Proteins}, issn = {1549-5469}, doi = {10.1101/gr.244491.118}, author = {Pawlak, Michal and Kedzierska, Katarzyna Z and Migdal, Maciej and Nahia, Karim Abu and Ramilowski, Jordan A and Bugajski, Lukasz and Hashimoto, Kosuke and Marconi, Aleksandra and Piwocka, Katarzyna and Carninci, Piero and Winata, Cecilia L} } @article {113, title = {A novel conserved enhancer at zebrafish zic3 and zic6 loci drives neural expression.}, journal = {Dev Dyn}, volume = {248}, year = {2019}, month = {2019 09}, pages = {837-849}, abstract = {

BACKGROUND: Identifying enhancers and deciphering their putative roles represent a major step to better understand the mechanism of metazoan gene regulation, development, and the role of regulatory elements in disease. Comparative genomics and transgenic assays have been used with some success to identify critical regions that are involved in regulating the spatiotemporal expression of genes during embryogenesis.

RESULTS: We identified two novel tetrapod-teleost conserved noncoding elements within the vicinity of the zic3 and zic6 loci in the zebrafish genome and demonstrated their ability to drive tissue-specific expression in a transgenic zebrafish assay. The syntenic analysis and robust green fluorescent expression in the developing habenula in the stable transgenic line were correlated with known sites of endogenous zic3 and zic6 expression.

CONCLUSION: This transgenic line that expresses green fluorescent protein in the habenula is a valuable resource for studying a specific population of cells in the zebrafish central nervous system. Our observations indicate that a genomic sequence that is conserved between humans and zebrafish acts as an enhancer that likely controls zic3 and zic6 expression.

}, keywords = {Animals, Animals, Genetically Modified, Conserved Sequence, Embryonic Development, Enhancer Elements, Genetic, Gene Expression Regulation, Developmental, Green Fluorescent Proteins, Habenula, Homeodomain Proteins, Humans, Nervous System, Repressor Proteins, Transcription Factors, Zebrafish, Zebrafish Proteins}, issn = {1097-0177}, doi = {10.1002/dvdy.69}, author = {Minhas, Rashid and Paterek, Aleksandra and {\L}api{\'n}ski, Maciej and Baza{\l}a, Micha{\l} and Korzh, Vladimir and Winata, Cecilia L} }