Project description:T-box transcription factors have been shown to play critical roles in the development and identity of the lungs. Tbx5 has been implicated as an initiator of pulmonary development through direct regulation of signaling molecules of the posterior second heart field (pSHF) and cardiopulmonary progenitors (CPs) (Arora et al. 2012 PLOS Genetics; Steimle et al 2018 PNAS). We hypothesize TBX5 regulates additional targets required for lung development. To this end, we performed ChIP-sequencing to identify localization of TBX5 during fetal lung development.
Project description:T-box transcription factors play critical roles in the development and identity of the heart. Tbx5 has been implicated as a regulator of the fast-conducting, ventricular conduction system, while Tbx3 has been implicated as a regulator of the slow-conducting node. We hypothesize TBX5 and TBX3 share common binding sites in cardiomyocytes to positively or negatively regulate transcription, respectively, for cardiac cell identity and conduction. To this end, we performed ChIP-sequencing to identify localization of TBX5 during fetal heart development and have compared it with previously published histone (GEO Series: GSE31039; ENCODE Accessions: ENCSR080GQM, ENCSR000CDL, ENCSR000CDM, ENCSR052CDF, ENCSR345RKE, ENCSR007XTC, ENCSR360ANE, ENCSR000CDK, and ENCSR357OED) and TBX3 ChIP-seq (GSM862695).
Project description:Tbx5 is expressed in the left ventricle of the developing mammalian heart. In order to test the transcriptional requirement of Tbx5 in the fetal left ventricle and bypass its early requirement in early cardiac formation, we used a combination of the ROSA26creERT2, a ubiquitously transcribed tamoxifen-dependent cre recombinase, and the Tbx5 floxed allele to remove both copies of Tbx5 at E11.5 followed by microdissection at E12.5. In addition to several well-known targets of Tbx5, we identified a novel signature of disrupted PDGF signaling.
Project description:Understanding how the atrial and ventricular chambers of the heart maintain their distinct identity is a prerequisite for treating chamber-specific diseases. Here, we selectively inactivated the transcription factor Tbx5 in the atrial working myocardium of the neonatal mouse heart to show that it is required to maintain atrial identity. Atrial Tbx5 inactivation downregulated highly chamber specific genes such as Myl7 and Nppa, and increased expression of ventricular identity genes including Myl2. Using combined single nucleus transcriptome and open chromatin profiling, we assessed genomic accessibility changes underlying the altered atrial identity expression program, identifying 1846 genomic loci with greater accessibility in control atrial cardiomyocytes compared to KO aCMs. 69% of the control-enriched ATAC regions were bound by TBX5, demonstrating a role for TBX5 in maintaining genomic accessibility. These regions were associated with genes that had higher expression in control aCMs compared to KO aCMs, suggesting they act as TBX5-dependent enhancers. To confirm this hypothesis we analyzed chromatin looping of enhancers marked by H3K27Ac using HiChIP and found 510 chromatin loops that were sensitive to TBX5 dosage. Of the loops enriched in control aCMs, 73.7% contained anchors in control-enriched ATAC regions. Conversely, Tbx5 overexpression in the ventricular myocardium drove atrial gene expression. Together, these data demonstrate a role for TBX5 in maintaining the atrial gene expression program by binding to atrial enhancers to preserve tissue-specific chromatin architecture. We highlight this phenomenon at major atrial identity genes including Nppa, Bmp10 and Myl7. HiChIP for H3K27Ac from atria of TBX5KO and control animals
Project description:Understanding how the atrial and ventricular chambers of the heart maintain their distinct identity is a prerequisite for treating chamber-specific diseases. Here, we selectively inactivated the transcription factor Tbx5 in the atrial working myocardium of the neonatal mouse heart to show that it is required to maintain atrial identity. Atrial Tbx5 inactivation downregulated highly chamber specific genes such as Myl7 and Nppa, and increased expression of ventricular identity genes including Myl2. Using combined single nucleus transcriptome and open chromatin profiling, we assessed genomic accessibility changes underlying the altered atrial identity expression program, identifying 1846 genomic loci with greater accessibility in control atrial cardiomyocytes compared to KO aCMs. 69% of the control-enriched ATAC regions were bound by TBX5, demonstrating a role for TBX5 in maintaining genomic accessibility. These regions were associated with genes that had higher expression in control aCMs compared to KO aCMs, suggesting they act as TBX5-dependent enhancers. To confirm this hypothesis we analyzed chromatin looping of enhancers marked by H3K27Ac using HiChIP and found 510 chromatin loops that were sensitive to TBX5 dosage. Of the loops enriched in control aCMs, 73.7% contained anchors in control-enriched ATAC regions. Conversely, Tbx5 overexpression in the ventricular myocardium drove atrial gene expression. Together, these data demonstrate a role for TBX5 in maintaining the atrial gene expression program by binding to atrial enhancers to preserve tissue-specific chromatin architecture. We highlight this phenomenon at major atrial identity genes including Nppa, Bmp10 and Myl7.
Project description:Underdeveloped lungs are the primary cause of death in premature infants, however, little is known about stem and progenitor cell maintenance during human lung development. In this study, we have identified that FGF7, Retinoic Acid and CHIR-99021, a small molecule that inhibits GSK3 to activate Wnt signaling, support in vitro maintenance of primary human fetal lung bud tip progenitor cells in a progenitor state. Furthermore, these factors are sufficient to derive a population of human bud tip-like progenitor cells in 3D organoid structures from human pluripotent stem cells (hPSC). Functional studies showed that hPSC-derived bud tip progenitor organoids do not contain any mesenchymal cell types, maintain multilineage potential in vitro and are able to engraft into the airways of injured mice and respond to systemic factors. We performed RNA-sequencing to assess the degree of similarity in global gene expression profiles between the full human fetal lung (59-127 days gestation), isolated human fetal bud tip progenitors, organoids grown from primary fetal bud tip progenitors, and hPSC-derived bud tip organoids. Results showed that hPSC-derived organoids have molecular profiles similar to organoids generated from primary human fetal lung tissue. Gene expression differences between hPSC-derived bud tip organoids and fetal progenitor organoids may be related to the presence of contaminating mesenchymal cells in primary cultures. hPSC-derived bud tip organoids are generated from a well-defined human cell sources, offering a distinct advantage over rare primary tissue as a means to study human specific lung development, homeostasis and disease.<br>Sample Nomenclature - Description<br> -------------------------------------------------------------------------<br> Peripheral fetal lung the distal/peripheral portion of the fetal lung (i.e., distal 0.5 cm) was excised from the rest of the lung using a scalpel. This includes all components of the lung (e.g., epithelial, mesenchymal, vascular). <br>Isolated fetal bud tip the bud peripheral portion of the fetal lung was excised with a scalpel and subjected to enzymatic digestion and microdissection. The epithelium was dissected and separated from the mesenchyme, but a small amount of associated mesenchyme likely remained. <br>Fetal progenitor organoid 3D organoid structures that arose from culturing isolated fetal epithelial bud tips. <br>Foregut spheroid 3D foregut endoderm structure as described in Dye et al. (2015). Gives rise to patterned lung organoid (PLO) when grown in 3F medium. <br> Patterned lung organoid (PLO) lung organoids that were generated by differentiating hPSCs, as described throughout the manuscript. <br> Bud tip organoid organoids derived from PLOs, enriched for SOX2/SOX9 co-expressing cells, and grown/passaged in 3F medium.