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Gene expression profiles in homologous tissues have been observed to be different between species, which may be due to differences between species in the gene expression program in each cell type, but may also reflect differences in cell type composition of each tissue in different species. Here, we compare expression profiles in matching primary cells in human, mouse, rat, dog, and chicken using Cap Analysis Gene Expression (CAGE) and short RNA (sRNA) sequencing data from FANTOM5. While we find that expression profiles of orthologous genes in different species are highly correlated across cell types, in each cell type many genes were differentially expressed between species. Expression of genes with products involved in transcription, RNA processing, and transcriptional regulation was more likely to be conserved, while expression of genes encoding proteins involved in intercellular communication was more likely to have diverged during evolution. Conservation of expression correlated positively with the evolutionary age of genes, suggesting that divergence in expression levels of genes critical for cell function was restricted during evolution. Motif activity analysis showed that both promoters and enhancers are activated by the same transcription factors in different species. An analysis of expression levels of mature miRNAs and of primary miRNAs identified by CAGE revealed that evolutionary old miRNAs are more likely to have conserved expression patterns than young miRNAs. We conclude that key aspects of the regulatory network are conserved, while differential expression of genes involved in cell-to-cell communication may contribute greatly to phenotypic differences between species., (© 2020 Alam et al.; Published by Cold Spring Harbor Laboratory Press.)

Long noncoding RNAs (lncRNAs) constitute the majority of transcripts in the mammalian genomes, and yet, their functions remain largely unknown. As part of the FANTOM6 project, we systematically knocked down the expression of 285 lncRNAs in human dermal fibroblasts and quantified cellular growth, morphological changes, and transcriptomic responses using Capped Analysis of Gene Expression (CAGE). Antisense oligonucleotides targeting the same lncRNAs exhibited global concordance, and the molecular phenotype, measured by CAGE, recapitulated the observed cellular phenotypes while providing additional insights on the affected genes and pathways. Here, we disseminate the largest-to-date lncRNA knockdown data set with molecular phenotyping (over 1000 CAGE deep-sequencing libraries) for further exploration and highlight functional roles for ZNF213-AS1 and lnc-KHDC3L-2 ., (© 2020 Ramilowski et al.; Published by Cold Spring Harbor Laboratory Press.)

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., (© 2019 Pawlak et al.; Published by Cold Spring Harbor Laboratory Press.)