Project description:Abstract Hippo pathway downstream effectors Yap and Taz play key roles in cell proliferation and regeneration, regulating gene expression especially via interaction with Tead transcription factors. To investigate their role in skeletal muscle stem cells, we analysed Taz in vivo and ex vivo in comparison to Yap. Taz was expressed in activated satellite cells. siRNA knockdown or constitutive expression of wildtype or constitutively active TAZ mutants showed that TAZ promoted proliferation, a function that was shared with YAP. However, at later stages of myogenesis, TAZ also enhanced myogenic differentiation of myoblasts, whereas YAP inhibits such differentiation. Functionally, while muscle growth was mildly affected in Taz (gene symbol Wwtr1-/-) knockout mice, there were no overt effect on regeneration. However, conditional knockout of Yap in satellite cells of Pax7Cre-ERT2/+ : Yapflox/flox : Rosa26Lacz mice produced a marked regeneration deficit. To identify potential mechanisms, microarray analysis showed many common Taz/Yap targets, but Taz also regulates some genes independently of Yap, including myogenic genes such as Pax7, Myf5 and Myod1. Proteomic analysis of Yap/Taz revealed many common binding partners, but Taz also interacts with proteins distinct from Yap, that are mainly involved in myogenesis and aspects of cytoskeleton organization. Neither TAZ nor YAP bind members of the Wnt destruction complex but both extensively changed expression of Wnt and Wnt-cross talking genes with known roles in myogenesis. Finally, TAZ operates through Tead4 to enhance myogenic differentiation. In summary, Taz and Yap have overlapping functions in promoting myoblast proliferation but Taz then switches to promote myogenic differentiation.
Project description:Glioblastoma (GBM) is the most aggressive brain tumor and resistant to current available therapeutics, such as radiation. To improve the clinical efficacy, it is important to understand the cellular mechanisms underlying tumor responses to radiation. Here, we investigated long-term cellular responses of human GBM cells to ionizing radiation. Comparing to the initial response within 12 hours, gene expression modulation at 7 days after radiation is markedly different. While genes related to cell cycle arrest and DNA damage responses are mostly modulated at the initial stage; immune-related genes are specifically affected as the long-term effect. This later response is associated with increased cellular senescence and inhibition of transcriptional coactivator with PDZ-binding motif (TAZ). Mechanistically, TAZ inhibition does not depend on the canonical Hippo pathway, but relies on enhanced degradation mediated by the β-catenin destruction complex in the Wnt pathway. We further showed that depletion of TAZ by RNAi promotes radiation-induced senescence and growth arrest. Pharmacological activation of the β-catenin destruction complex is able to promote radiation-induced TAZ inhibition and growth arrest in these tumor cells. The correlation between senescence and reduced expression of YAP as well as β-catenin also occurs in human gliomas treated by radiation. Collectively, these findings suggested that inhibition of TAZ is involved in radiation-induced senescence and might benefit GBM radiotherapy.
Project description:In melanoma, a switch from a proliferative melanocytic to an invasive mesenchymal phenotype is based on dramatic transcriptional reprogramming which involves complex interactions between a variety of signaling pathways and their downstream transcriptional regulators. TGFb/SMAD, Hippo/YAP/TAZ and Wnt/b-catenin signaling pathways are major inducers of transcriptional reprogramming and converge at several levels. Here, we report that TGFb/SMAD, YAP/TAZ and b-catenin are all required for a proliferative-to-invasive phenotype switch. Loss and gain of function experimentation, global gene expression analysis, and computational nested effects models revealed the hierarchy between these signaling pathways and identified shared target genes. SMAD-mediated transcription at the top of the hierarchy leads to the activation of YAP/TAZ and of b-catenin, with YAP/TAZ governing an essential sub-program of TGFb-induced phenotype switching. Wnt/b-catenin signaling is situated further downstream and exerts a dual role: it promotes the proliferative, differentiated melanoma cell phenotype and it is essential but not sufficient for SMAD or YAP/TAZ-induced phenotype switching. The results identify epistatic interactions among the signaling pathways underlying melanoma phenotype switching and highlight the priorities in targets for melanoma therapy.
Project description:The WWTR1(TAZ)-CAMTA1 and YAP1-TFE3 gene fusions are disease defining gene alterations for epithelioid hemangioendothelioma, a vascular cancer. The resultant fusion proteins fuse the C terminus of CAMTA1 and TFE3 in frame to the N terminus of TAZ and YAP, respectively. An unbiased BioID-mass spectrometry/RNAi screen identified YEATS2 and ZZZ3 as components of the Ada2a-containing histone acetyltransferase complex and key interactors of both TAZ-CAMTA1 and YAP-TFE3. An integrative NGS approach including RNA-Seq, ChIP-Seq, and ATAC-Seq showed TAZ-CAMTA1 and YAP-TFE3 transcriptional programs overlap with TAZ and YAP but also drive expression of a novel transcriptome.
Project description:Correct neural progenitor fate determination requires the coordination of extrinsic fate determinant signals with intrinsic responses. Post-translational modifications dynamically alter protein function and so are ideally situated to regulate development. Here we show that the deubiquitylaying enzyme, Usp9x modulates both intrinsic and extrinsic regulators of mouse neural progenitors. Nestin-cre mediated deletion of Usp9x from neural progenitors results in a transient disruption of cell adhesion and apical-basal polarity as well as the premature differentiation of intermediate neural progenitors. Ablation of Usp9x also significantly increased β-catenin protein levels, especially S33/S37/T41 phospho-β-catenin, and Wnt signalling. Usp9x was found to be part of the β-catenin destruction complex and loss of Usp9x affects destruction complex composition. Notch signalling was also increased in Usp9x ablated neural progenitors, coinciding with decreased Itch and Numb, and increased Notch intracellular domain protein levels. Usp9x co-localized and immunopreciptiated with Numb from neural progenitors suggesting it is required for Numb stabilisation. These data suggest Usp9x plays a role in coordinating intrinsic responses to extrinsic signals during neural development.
Project description:Neural crest cells (NCCs) are multipotent stem cells with a remarkable ability to differentiate into multiple cell lineages, including osteoblasts and chondrocytes. NCCs contribute to the majority of craniofacial skeleton, yet the molecular mechanisms regulating NCCs diversification into osteoblasts or chondrocytes remain poorly understood. We found that Yap and Taz function redundantly as key determinants of the osteogenesis versus chondrogenesis fate decision and differentiation in NCCs in vitro, ex vivo and in vivo, and Yap/Taz-deficiency in NCCs resulted in a switch from osteogenesis to chondrogenesis. Comprehensive analysis of unbiased datasets including CUT&RUN-seq and RNA-seq indicated that Yap/Taz directly regulate key genes that govern osteogenesis and chondrogenesis. During NCC-derived osteogenesis, Yap/Taz promote expression of osteogenic genes such as Runx2 and Sp7 but repress expression of chondrogenic genes such as Sox9 and Col2a1. Further, we found Yap/Taz directly interact with β-catenin in NCCs to coordinately promote osteoblast differentiation and repress chondrogenesis. Together our data indicate that Yap/Taz promote osteogenesis in NCCs by preventing chondrogenesis, partly through interactions with the Wnt-β-catenin pathway.
Project description:The WWTR1(TAZ)-CAMTA1 and YAP1-TFE3 gene fusions are disease defining gene alterations for epithelioid hemangioendothelioma, a vascular cancer. The resultant fusion proteins fuse the C terminus of CAMTA1 and TFE3 in frame to the N terminus of TAZ and YAP, respectively. An unbiased BioID-mass spectrometry/RNAi screen identified YEATS2 and ZZZ3 as components of the Ada2a-containing histone acetyltransferase complex and key interactors of both TAZ-CAMTA1 and YAP-TFE3. An integrative NGS approach including RNA-Seq, ChIP-Seq, and ATAC-Seq showed TAZ-CAMTA1 and YAP-TFE3 transcriptional programs overlap with TAZ and YAP but also drive expression of a novel transcriptome. The altered transcriptional program of the fusion proteins owing to altered DNA binding as well as shifts in the chromatin landscape.
Project description:The WWTR1(TAZ)-CAMTA1 and YAP1-TFE3 gene fusions are disease defining gene alterations for epithelioid hemangioendothelioma, a vascular cancer. The resultant fusion proteins fuse the C terminus of CAMTA1 and TFE3 in frame to the N terminus of TAZ and YAP, respectively. An unbiased BioID-mass spectrometry/RNAi screen identified YEATS2 and ZZZ3 as components of the Ada2a-containing histone acetyltransferase complex and key interactors of both TAZ-CAMTA1 and YAP-TFE3. An integrative NGS approach including RNA-Seq, ChIP-Seq, and ATAC-Seq showed TAZ-CAMTA1 and YAP-TFE3 transcriptional programs overlap with TAZ and YAP but also drive expression of a novel transcriptome. The altered transcriptional program of the fusion proteins owing to altered DNA binding as well as shifts in the chromatin landscape.
Project description:The WWTR1(TAZ)-CAMTA1 and YAP1-TFE3 gene fusions are disease defining gene alterations for epithelioid hemangioendothelioma, a vascular cancer. The resultant fusion proteins fuse the C terminus of CAMTA1 and TFE3 in frame to the N terminus of TAZ and YAP, respectively. An unbiased BioID-mass spectrometry/RNAi screen identified YEATS2 and ZZZ3 as components of the Ada2a-containing histone acetyltransferase complex and key interactors of both TAZ-CAMTA1 and YAP-TFE3. An integrative NGS approach including RNA-Seq, ChIP-Seq, and ATAC-Seq showed TAZ-CAMTA1 and YAP-TFE3 transcriptional programs overlap with TAZ and YAP but also drive expression of a novel transcriptome. The altered transcriptional program of the fusion proteins owing to altered DNA binding as well as shifts in the chromatin landscape.
Project description:The WWTR1(TAZ)-CAMTA1 and YAP1-TFE3 gene fusions are disease defining gene alterations for epithelioid hemangioendothelioma, a vascular cancer. The resultant fusion proteins fuse the C terminus of CAMTA1 and TFE3 in frame to the N terminus of TAZ and YAP, respectively. An unbiased BioID-mass spectrometry/RNAi screen identified YEATS2 and ZZZ3 as components of the Ada2a-containing histone acetyltransferase complex and key interactors of both TAZ-CAMTA1 and YAP-TFE3. An integrative NGS approach including RNA-Seq and ATAC-Seq showed that the differentially expressed genes in YAP-TFE3 cells with knockdown of YEATS2 or ZZZ3 are nested in regions of open chromatin unique to YAP-TFE3. The altered transcriptional program of the fusion proteins is modulated by the Ada2a-containing histone acetyltransferase complex.