Multiple roles for Wwtr1 in cardiac wall maturation
Ontology highlight
ABSTRACT: Cardiac trabeculation is a highly regulated process that starts with the delamination of cardiomyocytes from the compact wall to form stereotypical muscular ridges in the developing ventricle. The Hippo signaling pathway has been implicated in cardiac development but many questions remain. We investigated the role of Wwtr1, a nuclear effector of the Hippo pathway, in zebrafish and find that its loss results in hearts with reduced trabeculation. However, in mosaic animals, wwtr1-/- cardiomyocytes contribute more frequently than wwtr1+/- cardiomyocytes to the trabecular layer of wild-type hearts. To investigate this paradox, we examined the myocardial wall at early stages and find that loss of Wwtr1 leads to disruption of the compact wall architecture, as evidenced by the disorganized cortical actin structure and abnormal cell-cell junctions. The mutant compact wall is not able to support trabeculation as, in mosaic animals, wild-type cardiomyocytes are more frequently in the compact layer of mutant than heterozygous hearts. Therefore, we propose that Wwtr1 establishes the compact wall architecture necessary for trabeculation and that it also modulates a cardiomyocyte’s decision to enter the trabecular layer.
Project description:In vertebrates, the heart has two main layers of cardiac muscle, a peripheral compact layer and an internal trabecular layer. Little is known on the differerences in gene expression between both layers. In zebrafish the outer layer is named cortical layer and the internal also trabecular layer. Here we used a double transgenic line labelling with GFP tbx5-positive cells and cardiomyoctes with nuclear DsRed (nucDsRed) to distinguish cortical from trabecular myocardium. Then, we compared the transcriptome of trabecular and cortical myocardium in the adult zebrafish. We describe that Tbx5a is a good marker of trabecular myocardium.
Project description:Recently, it was described that mammalian cells are able to eliminate those with relative lower Myc levels in the epiblast through cell competition. We have described that cardiomyocytes during heart development are also able to complete eliminating cells with lower Myc levels. We have also shown that adult cardiomyocytes respond in the same way over long periods of time when cell competition is induced by overexpressing Myc in a mosaic fashion. We therefore have developed an RNASeq assay to further understand the mechanism of elimination of WT cells and the effect of mild Myc overexpression in cardiomyocytes. Myc overexpression in a mosaic fashion in adult cardiomyocytes, 2 hearts were analyzed and two wild type littermates were used as controls
Project description:The ang1-Tie2 pathway is required for normal vascular development, but its molecular effectors are not well-defined during cardiac ontogeny. Here we show that endocardial specific attenuation of Tie2 results in mid-gestation lethality due to heart defects associated with a hyperplastic but simplified trabecular meshwork (fewer but thicker trabeculae). Reduced proliferation and production of endocardial cells (ECs) following endocardial loss of Tie2 results in decreased endocardial sprouting required for trabecular assembly and extension. The hyperplastic trabeculae result from enhanced proliferation of trabecular cardiomyocyte (CMs), which is associated with upregulation of Bmp10, increased retinoic acid (RA) signaling, and Erk1/2 hyperphosphorylation in the myocardium. Intriguingly, myocardial phenotypes in Tie2-cko hearts could be partially rescued by inhibiting in utero RA signaling with pan-retinoic acid receptor antagonist BMS493. These findings reveal two complimentary functions of endocardial Tie2 during ventricular chamber formation: ensuring normal trabeculation by supporting EC proliferation and sprouting, and preventing hypertrabeculation via suppression of RA signaling in trabecular CMs.
Project description:Experiment was designed to study the effect of Hippo pathway on osimertinib resistance in non-small cell lung cancer cell lines. The specific comparisons investigated were: PC-9: NTC vs NF2 KO, EV vs YAP1 OE, EV vs WWTR1 OE, EV DMSO treated vs EV osimertinib treated HCC827: NTC vs NF2 KO, EV vs YAP1 OE, EV vs WWTR1 OE,EV DMSO treated vs EV osimertinib treated HCC4006: NTC vs NF2 KO, EV vs YAP1 OE, EV vs WWTR1 OE, EV DMSO treated vs EV osimertinib treated
Project description:Left ventricular non-compaction (LVNC) is a rare cardiomyopathy associated with a hypertrabeculated phenotype and a large spectrum of symptoms. The developmental origins and mechanistic basis of varying severity of this pathology are unknown. To investigate these issues, we inactivated the cardiac transcription factor Nkx2-5 in trabecular myocardium at different stages of trabecular morphogenesis. Conditional deletion of Nkx2-5 at embryonic stages, during trabecular formation, provokes a severe hypertrabeculated phenotype associated with subendocardial fibrosis and Purkinje fiber hypoplasia. A milder phenotype was observed after Nkx2-5 deletion at fetal stages, during trabecular compaction. A longitudinal study of cardiac function in adult Nkx2-5 conditional mutant mice demonstrates that excessive trabeculation is associated with complex ventricular conduction defects, progressively leading to strain defects, and, in 50% of mutant mice, to heart failure. Progressive impaired cardiac function correlates with conduction and strain defects independently of the degree of hypertrabeculation. Transcriptomic analysis of molecular pathways reflects myocardial remodeling with a larger number of differentially expressed genes in the severe versus mild phenotype and identifies Six1 as a marker upregulated in hypertrabeculated hearts. Our results provide insights into the etiology of LVNC and link its pathogenicity with compromised trabecular development including compaction defects and ventricular conduction system hypoplasia.
Project description:KMT2D is required in the cardiac mesoderm, anterior heart field precursors and cardiomyocytes. Kmt2d deletion in cardiac mesoderm (Mesp1Cre) is embryonic lethal at E10.5 and mutants have hypoplastic hearts; Kmt2d deletion in anterior heart field precursors (Mef2cAHF::Cre) deletion is embryonic lethal at E13.5 and mutants have defects in septation of outflow tract and interventricular septum (IVS); Kmt2d deletion in cardiomyocytes (Tnnt2::Cre) deletion is embryonic lethal at E14.5 and mutants have defects in IVS septation and compact myocardium. The goal of this study is to compare changes in gene expression in these Kmt2d conditional deletion mutants and understand common or distinct pathways dysregulated in absence of KMT2D. Whole genome gene expression analysis was performed on RNA isolated from control and mutant embryonic hearts (or right ventricles and outflow tract for anterior heart field deletion samples). Libraries were prepared using Illumina TruSeq Paired-End Cluster Kit v3, and sequenced with the Illumina HiSeq 2500 system for pair-ended 100 base pairs (PE 100 bp).
Project description:The goal of this study is to compare the relative expression genes in hearts of foxc1a-null mutants and WT siblings. 96hpf hearts of foxc1anju18 and WT siblings were dissected for total RNA extraction. RNA profiles were generated using Illumina deep sequencing. Our study represents the reduced expression of several trabeculation related signaling pathways and cell processes.
Project description:We used adenoviral-mediated overexpression of MYC-BioID2, MYC-BioID2-SKI, MYC-BioID2-WWTR1 (TAZ) in human primary cardiac fibroblasts to elucidate the interaction between SKI and the Hippo signaling pathway. Original data is also available on the Global Proteome Machine (http://hs2.proteome.ca/tandem/thegpm_tandem.html). Datasets are identified as follows: GPM10000002938 and 2939 are untreated negative control cell lysates; GPM10000002941 and 2942 are "empty" MYC-BioID2 vector; GPM10000002943 and 2944 are MYC-BioID2-SKI; and GPM10000002944 and 2945 are MYC-BioID2-WWTR1(TAZ).
Project description:Epigenetic enzymes play critical roles in embryogenesis by defining higher-order chromatin structures required for the establishment of organ-specific transcriptional networks. In this study we investigated the role of the histone 3 lysine 79 methyltrasferase Dot1L in cardiomyocytes during development. Cardiomyocyte-specific ablation of Dot1L resulted in postnatal lethality with a cardiac phenotype of enlarged, rounded heart with increased ventricular wall thickness and areas of moderate trabeculation postnatally. To understand transciptomic alterations driving the observed phenotype, we conducted RNA-seq experimens in embryonic (E16.5) and neonatal (P1) cardiomyocytes from Dot1L conditional knock out and control mice. Overall, we identified downregulation of genes higly expressed and upregulaton of genes lowly expressed. Genes dowregulated in two critical stages of cardiac development analysed were indicative of defective cardiac patterning during embryogenesis, and defective cell cycle withdrawal in the neonatal period.
Project description:Genotype directed anti-cancer therapies such BRAF inhibitor in BRAF mutant melanoma can show remarkable clinical efficacy but resistance limits their benefit. We show that a transposon activation screen efficiently identifies resistance genes to BRAF and captures a number of previously uncharacterized resistance mechanisms, including an E3 ubiquitin ligase NEDD4L and the Hippo pathway effector WWTR1 (TAZ). Resistance can be reversed by combining BRAF inhibition with tyrosine kinase inhibitors as observed previously for other resistance genes. Moreover, an integrative analysis of several gain- and loss-of-function genetic screens performed in the same context reveals smaller functional diversity of resistance mechanisms to MAPK inhibition than suggested by the broad range of resistance genes identified, implying common therapeutic strategies. A375 cells with lentiviral vector controls or WWTR1 cDNA plasmid.