Project description:Angiogenesis, the process by which endothelial cells (ECs) form new blood vessels from existing ones, is intimately linked to the tissue's metabolic milieu and often occurs at nutrient-deficient sites. However, ECs rely on sufficient metabolic resources to support growth and proliferation. How endothelial nutrient acquisition and usage are regulated is unknown. Here we show that these processes are dictated by YAP/TAZ-TEAD – a transcriptional module whose function is highly responsive to changes in the tissue environment. ECs lacking YAP/TAZ or their transcriptional partners, TEAD1, 2, and 4 fail to divide, resulting in stunted vascular growth in mice. Conversely, activation of TAZ, the more abundant paralogue in ECs, boosts proliferation, leading to vascular hyperplasia. We find that YAP/TAZ promote angiogenesis by fueling nutrient mTORC1 signaling. By orchestrating the transcription of a repertoire of cell-surface transporters, YAP/TAZ-TEAD stimulate the import of amino acids and other essential nutrients, thereby enabling mTORC1 pathway activation. Dissociating mTORC1 from these nutrient inputs – elicited by the loss of Rag GTPases – inhibits mTORC1 activity and prevents YAP/TAZ-dependent vascular growth. These findings define a pivotal role for YAP/TAZ-TEAD in steering endothelial mTORC1 and illustrate the essentiality of coordinated nutrient fluxes in the vasculature.
Project description:Activation of endothelial YAP/TAZ signaling is crucial for physiological and pathological angiogenesis. The mechanisms of endothelial YAP/TAZ regulation are, however, incompletely understood. Here we report that the protocadherin FAT1 acts as a critical upstream regulator of endothelial YAP/TAZ which limits the activity of these transcriptional cofactors during developmental and tumor angiogenesis by promoting their degradation. We show that loss of endothelial FAT1 results in increased endothelial cell proliferation in vitro and in various angiogenesis models in vivo. This effect is due to perturbed YAP/TAZ protein degradation, leading to increased YAP/TAZ protein levels and expression of canonical YAP/TAZ target genes. We identified the E3 ubiquitin ligase Mind Bomb-2 (MIB2) as a novel FAT1-interacting protein mediating FAT1-induced YAP/TAZ ubiquitination and degradation. Loss of MIB2 expression in endothelial cells in vitro and in vivo recapitulated the effects of FAT1 depletion and caused decreased YAP/TAZ degradation and increased YAP/TAZ signaling. Our data identify a pivotal mechanism of YAP/TAZ regulation involving FAT1 and its associated E3 ligase MIB2, which is essential for YAP/TAZ-dependent angiogenesis.
Samples for proteomics were obtained from HUVECs transduced with the FAT1 intracellular part fused with the extracellular part and transmembrane domain of the IL-2 receptor and carrying a Flag tag on the C terminus (see above) for 36 h followed by lysis in IP buffer. Lysates were incubated with magnetic anti-FLAG beads (M8823, Sigma/Aldrich) overnight at 4Deg. Affinity purified samples were subjected to in-gel (4-12% NuPAGE Bis-Tris gels, ThermoFisher Scientific) digestion as described (DOI: 10.1038/nprot.2006.468). In brief, gel lanes were cut into nine blocks/fractions and finely diced. Embedded proteins were reduced (10 mM dithiothreitol) and alkylated (55 mM iodoacetamide), followed by overnight digestion using trypsin (Serva). Peptides were extracted by increasing concentrations of acetonitrile and lyophilized. Final desalting, concentration and storage utilized "stop and go extraction" (STAGE) tips (DOI: 10.1021/ac026117i). Eluted peptides where subjected to electrospray ionization (ESI)-mediated liquid chromatography/tandem mass spectrometry (LC/MS2) using in house-packed column emitters (15 cm length, 70 um ID, 1.9 um ReprsoSil-Pur 120 C18-AQ, Dr. Maisch) and a buffer system comprising solvent A (0.1% formic acid) and solvent B (80% acetonitrile, 0.1% formic acid). Instrumentation details and parameters were extracted and summarized using MARMoSET (DOI: 10.1074/mcp.TIR119.001505) and are repository deposited. Peptide/spectrum matching and label free quantitation were performed using the MaxQuant suite of algorithms (DOIs: 10.1038/nbt.1511, 10.1021/pr101065j, 10.1074/mcp.M113.031591) against the human UniProt database (canonical & isoforms; downloaded on 2019/01/23). Parameters are included here. Downstream statistical analysis used the limma-based (DOI: 10.1093/nar/gkv007) in-house package autonomics (https://doi.org/doi:10.18129/B9.bioc.autonomics).
Project description:The Hippo pathway downstream effectors, Yap and Taz, play key roles in cell proliferation and tissue growth, regulating gene expression especially via interaction with Tead transcription factors. To investigate their role in skeletal muscle stem cells, we analysed gene expression changes driven by Taz and compared these to Yap mediated changes to the transcriptome by measurement of gene expression on Affymetrix microarrays. To interrogate overlapping and unique transcriptional changes driven by these Hippo effectors, satellite cell-derived myoblasts were transduced with constitutively active TAZ S89A or YAP S127A retrovirus for 24h or 48h, with empty retrovirus as control. Triplicate microarray analyses of empty vector controls, hYAP1 S127A and TAZ S89A transgenic primary myoblasts were conducted.
Project description:Uncontrolled Transforming growth factor-beta (TGFβ) signaling promotes aggressive metastatic properties in late-stage breast cancers. However, how TGFβ-mediated cues are directed to induce late-stage tumorigenic events is poorly understood, particularly given that TGFβ has clear tumor suppressing activity in other contexts. Here we demonstrate that the transcriptional regulators TAZ and YAP (TAZ/YAP), key effectors of the Hippo pathway, are necessary to promote and maintain TGFβ-induced tumorigenic phenotypes in breast cancer cells. Interactions between TAZ/YAP, TGFβ-activated SMAD2/3, and TEAD transcription factors reveal convergent roles for these factors in the nucleus. Genome-wide expression analyses indicate that TAZ/YAP, TEADs and TGFβ-induced signals coordinate a specific pro-tumorigenic transcriptional program. Importantly, genes cooperatively regulated by TAZ/YAP, TEAD, and TGFβ, such as the novel targets NEGR1 and UCA1, are necessary for maintaining tumorigenic activity in metastatic breast cancer cells. Nuclear TAZ/YAP also cooperate with TGFβ signaling to promote phenotypic and transcriptional changes in non-tumorigenic cells to overcome TGFβ repressive effects. Our work thus identifies crosstalk between nuclear TAZ/YAP and TGFβ signaling in breast cancer cells, revealing novel insight into late-stage disease-driving mechanisms. Expression profiling was conducted following the repression of the transcriptional regulators TAZ and YAP (TAZ/YAP), the TEAD family of transcription factors (TEAD1/2/3/4), or the TGFb signaling pathway (with SB-431542, an inhibitor of the TBRI recpeptor) in human MDA-MB-231-LM2 breast cancer cells treated with TGFβ1. Human MDA-MB-231-LM2-4 breast cancer cells were transfected with control siRNA, or siRNAs targeting TAZ/YAP or all four TEADs and were treated 24 hours later with 500pM TGFβ1 or 5mM SB-431542 for an additional 24 hours. Total RNA was isolated and twelve microarrays in total were performed, with each condition carried out three times on separate days. The Boston University Microarray Core generated the data using the Affymetrix Human Gene 1.0 St Array.
Project description:The factors regulating cellular identity are critical for understanding the transition from health to disease and responses to therapies. Cell identity is generally assigned based on static phenotypes, like “omics” profiles. However, how such static features translate into dynamic responses to perturbations that determine cellular function is often unclear. We found that autophagy perturbation in different cell types can have opposite responses in growth-promoting oncogenic YAP/TAZ transcriptional signalling. These apparently contradictory responses can be resolved by a feedback loop where autophagy negatively regulates the levels of α-catenins LC3-interacting proteins, which inhibit YAP/TAZ, which, in turn, positively regulate autophagy. High basal levels of α-catenins enable autophagy induction to positively regulate YAP/TAZ, while low α-catenins cause YAP/TAZ activation upon autophagy inhibition. These data reveal how feedback loops enable post-transcriptional determination of cell identity and how levels of a single intermediary protein can dictate the direction of response to external or internal perturbations.
Project description:Oral squamous cell carcinoma (OSCC) is a prevalent form of cancer that develops from the epithelium of the oral cavity. OSCC is on the rise worldwide, and death rates associated with the disease are particularly high. Despite progress in understanding of the mutational and expression landscape associated with OSCC, advances in deciphering these alterations for the development of therapeutic strategies have been limited. Further insight into the molecular cues that contribute to OSCC is therefore required. Here we show that the transcriptional regulators YAP (YAP1) and TAZ (WWTR1), which are key effectors of the Hippo pathway, drive pro-tumorigenic signals in OSCC. Regions of pre-malignant oral tissues exhibit aberrant nuclear YAP accumulation, suggesting that dysregulated YAP activity contributes to the onset of OSCC. Supporting this premise, we determined that nuclear YAP and TAZ activity drives OSCC cell proliferation, survival, and migration in vitro, and is required for OSCC tumor growth and metastasis in vivo. Global gene expression profiles associated with YAP and TAZ knockdown revealed changes in the control of gene expression implicated in pro-tumorigenic signaling, including those required for cell cycle progression and survival. Notably, the transcriptional signature regulated by YAP and TAZ significantly correlates with gene expression changes occurring in human OSCCs identified by The Cancer Genome Atlas (TCGA), emphasizing a central role for YAP and TAZ in OSCC biology. Expression profiling was conducted following the repression of the transcriptional regulators TAZ and YAP (YAP/TAZ) in human SCC2 oral cancer cells. Human SCC2 oral cancer cells were transfected with control siRNA, or siRNAs targeting TAZ, YAP, or YAP/TAZ for 48 hours. Total RNA from three independent experiments carried out on separate days was isolated and purified and the samples were then profiled on Affymetrix Human Gene 2.0 Chips at the Boston University Microarray Core. The expression profiles were processed and normalized using the Robust Multi-array Average (RMA) procedure (23) based on a custom Brainarray CDF (24). For each of the siRNA experiments, signatures of genes differentially expressed between treatment and corresponding siRNA control with an FDR q-value ?0.05 and a fold change ?2 were identified as either activated (up-regulated in control) or repressed (up-regulated in treatment). The overlap between the differentially expressed gene signatures was evaluated by Fisher test. Hierarchical gene and sample clustering was performed on the top 3000 genes with highest median absolute deviation (MAD; a robust version of the variance) across 12 samples, using “ward” as the agglomeration rule, and 1 minus Pearson correlation and Euclidean as the distance measures for genes and samples, respectively.
Project description:We compared the transcriptomes of control and YAP/TAZ knockout gliomaspheres derived from mouse newborn astrocytes transformed with KRAS/shp53. We wanted to evaluate the effects of YAP/TAZ depletion on gliomaspheres transcriptional program.
Project description:The optic vesicle comprises a pool of bi-potential progenitor cells from which the retinal pigment epithelium (RPE) and neural retina fates segregate during ocular morphogenesis. Several transcription factors and signaling pathways have been shown to be important for RPE maintenance and differentiation, but an understanding of the initial fate specification and determination of this ocular cell type is lacking. We show that Yap/Taz-Tead activity is necessary and sufficient for optic vesicle progenitors to adopt RPE identity in zebrafish. A Teadresponsive transgene is expressed within the domain of the optic cup from which RPE arises, and Yap immunoreactivity localizes to the nuclei of prospective RPE cells. yap (yap1) mutants lack a subset of RPE cells and/or exhibit coloboma. Loss of RPE in yap mutants is exacerbated in combination with taz (wwtr1) mutant alleles such that, when Yap and Taz are both absent, optic vesicle progenitor cells completely lose their ability to form RPE. The mechanism of Yap dependent RPE cell type determination is reliant on both nuclear localization of Yap and interaction with a Tead co-factor. In contrast to loss of Yap and Taz, overexpression of either protein within optic vesicle progenitors leads to ectopic pigmentation in a dosagedependent manner. Overall, this study identifies Yap and Taz as key early regulators of RPE genesis and provides a mechanistic framework for understanding the congenital ocular defects of Sveinsson’s chorioretinal atrophy and congenital retinal coloboma. 60 pooled eyes from 36 hpf wild type or vsx2:Gal4/dsRed:14xUAS:YapS87A embryos were pooled for one sample. Three wild type and three vsx2:Gal4/dsRed:14xUAS:YapS87A pools were analyzed for RNA.
Project description:Endothelial cells (ECs) are constantly exposed to mechanical forces in the form of fluid shear stress, extracellular stiffness, and cyclic strain. How mechanical forces are transduced to the nucleus to drive transcriptional reprogramming in ECs is poorly understood. The mechanoresponsive activity of Yes associated protein (YAP) and its role in vascular development are well described, however, whether changes to transcription or epigenetic regulation of YAP are involved in these processes remains unanswered. Our results reveal that mechanical forces sensed at cell-cell junctions by the YAP target gene, Angiomotin-like 2 (AmotL2), are directly intervened into changes in global chromatin accessibility and EZH2 activity leading to modulation of YAP-promotor activity. Functionally, shear stress induced proliferation of ECs in vivo were reliant on AmotL2 and YAP/TAZ endothelial expression. Mechanistically, uncoupling of the nuclear-cytoskeletal connection from junctions and focal adhesions led to altered nuclear morphology, chromatin accessibility and suppression of YAP-promotor activity. Our findings reveal a role for AmotL2 and nuclear-cytoskeletal force transmission in modulating the epigenetic and transcriptional regulation of YAP to maintain a mechanoenforced positive-feedback loop of vascular homeostasis.