Sonic hedgehog (Shh) is essential for limb development, and the mechanisms that govern the propagation and maintenance of its expression has been well studied; however, the mechanisms that govern the initiation of Shh expression are incomplete. Here we report that ETV2 initiates Shh expression by changing the chromatin status of the developmental limb enhancer, ZRS. Etv2 expression precedes Shh in limb buds, and Etv2 inactivation prevents the opening of limb chromatin, including the ZRS, resulting in an absence of Shh expression. Etv2 overexpression in limb buds causes nucleosomal displacement at the ZRS, ectopic Shh expression, and polydactyly. Areas of nucleosome displacement coincide with ETS binding site clusters. ETV2 also functions as a transcriptional activator of ZRS and is antagonized by ETV4/5 repressors. Known human polydactyl mutations introduce novel ETV2 binding sites in the ZRS, suggesting that ETV2 dosage regulates ZRS activation. These studies identify ETV2 as a pioneer transcription factor (TF) regulating the onset of Shh expression, having both a chromatin regulatory role and a transcriptional activation role.
Aims Congenital heart disease (CHD) is the most common genetic birth defect, which has considerable morbidity and mortality. We focused on deciphering key regulators that govern cardiac progenitors and cardiogenesis. FOXK1 is a forkhead/winged helix transcription factor known to regulate cell cycle kinetics and is restricted to mesodermal progenitors, somites and the heart. In the present study, we define an essential role for FOXK1 during cardiovascular development. Methods & Results We used the mouse embryoid body system to differentiate control and Foxk1 KO ESCs into mesodermal, cardiac progenitor cells and mature cardiac cells. Using flow cytometry, immunohistochemistry, cardiac beating, transcriptional and ChIP qPCR assays, bulk RNAseq and ATACseq analyses, FOXK1 was observed to be an important regulator of cardiogenesis. Flow cytometry analyses revealed perturbed cardiogenesis in Foxk1 KO EBs. Bulk RNAseq analysis at two developmental stages showed a significant reduction of the cardiac molecular program in Foxk1 KO EBs compared to the control EBs. ATACseq analysis during EB differentiation demonstrated that the chromatin landscape nearby known important regulators of cardiogenesis was significantly relaxed in control EBs compared to Foxk1 KO EBs. Furthermore, we demonstrated that in the absence of FOXK1, cardiac differentiation was markedly impaired by assaying for cTnT expression and cardiac contractility. We demonstrate that FOXK1 is an important regulator of cardiogenesis by repressing the Wnt/β-catenin signaling pathway and thereby promoting differentiation. Conclusions These results identify FOXK1 as an essential transcriptional and epigenetic regulator of cardiovascular development. Mechanistically, FOXK1 represses Wnt signaling to promote the development of cardiac progenitor cells. Translational perspective Congenital heart disease is the most common birth defect. Deciphering the networks that govern cardiomyocyte specification, proliferation and differentiation will provide insights regarding therapeutic interventions for cardiovascular disease. The winged helix/forkhead family of transcription factors have been shown to have critical roles in epigenetics, organogenesis, cellular proliferation and differentiation. FOXK1 is an important transcription factor that regulates cardiovascular development through the Wnt signaling pathway. This FOXK1-Wnt pathway defines a network that may be therapeutically targeted to promote cardiogenesis.
The position of the nucleosome and chromatin packaging in eukaryotic genomes govern gene regulation and cellular functions. Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) is an efficient and precise method for revealing chromatin accessibility across the genome. However, there is no method that is specifically designed for detecting differential chromatin accessibility using ATAC-seq datasets. In this study, we developed a bioinformatics tool called SeATAC, that used a conditional variational autoencoder (CVAE) model to learn the latent representation of ATAC-seq V-plots, and to estimate the statistically differential chromatin accessibility. We demonstrated that SeATAC outperformed MACS2 and NucleoATAC on four separate tasks including: (1) detection of differential V-plots; (2) definition of nucleosome positions; (3) detection of nucleosome changes and (4) designation of transcriptional factor binding sites (TFBS) with differential chromatin accessibility. By applying SeATAC to several pioneer factor induced differentiation or reprogramming ATAC-seq datasets, we found that induction of these pioneer factors not only relaxed the closed chromatin but also decreased the chromatin accessibility of 20% - 30% of their target sites. These two groups of TF binding sites were characterized by different genomic distribution and histone marks. Here, we present SeATAC as a novel tool to accurately reveal the genomic regions with differential chromatin accessibility from ATAC-seq data.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.