Project description:The Hippo pathway plays a crucial in organ size control during development and tissue homeostasis in adult life. To examine a role for Hippo signaling in the intestinal epithelium, we analyzed gene expression patterns in the mouse intestinal epithelilum transfected with siRNAs or expression plasmids for shRNAs targeting the Hippo pathway effectors, YAP and TAZ. We performed two independent series of experiments (siGFP (n=3) vs siYAP/siTAZ (n=3), and shLacZ (n=1) vs shYAP/shTAZ (n=1)). Control siRNA (siGFP), YAP/TAZ siRNAs, or expression plasmids for control shRNA (shLacZ) or YAP/TAZ shRNAs were introduced into the mouse intestinal epithelium by the newly-developed in vivo transfection method. Four days after transfection, intestinal epithelial cells were isolated from the tissues and total RNA was extracted.
Project description:The skin is a squamous epithelium that is continuously renewed by a population of basal layer stem/progenitor cells and can heal wounds. Here, we show that the transcription regulators YAP and TAZ localise to the nucleus in the basal layer of skin and are elevated upon wound healing. Skin-specific deletion of both YAP and TAZ in adult mice slows proliferation of basal layer cells, leads to hair loss and impairs regeneration after wounding. Contact with the basal extracellular matrix and consequent integrin-Src signalling is a key determinant of the nuclear localisation of YAP/TAZ in basal layer cells and in skin tumours. Contact with the basement membrane is lost in differentiating daughter cells, where YAP and TAZ become mostly cytoplasmic. In other types of squamous epithelia and squamous cell carcinomas, a similar control mechanism is present. By contrast, columnar epithelia differentiate an apical domain that recruits CRB3, Merlin (also known as NF2), KIBRA (also known as WWC1) and SAV1 to induce Hippo signalling and retain YAP/TAZ in the cytoplasm despite contact with the basal layer extracellular matrix. When columnar epithelial tumours lose their apical domain and become invasive, YAP/TAZ becomes nuclear and tumour growth becomes sensitive to the Src inhibitor Dasatinib.
Project description:Proper lung function relies on precisely balanced numbers of specialized epithelial cell types that work together and are maintained in homeostasis. In this study we have described essential roles for the transcriptional regulators YAP and TAZ, which are key effectors of Hippo pathway signaling, in maintaining lung epithelial homeostasis. Phenotypes associated with Yap/Taz deletion include alveolar defects and a striking development of goblet cell metaplasia throughout the airways. Lineage specific deletion of Yap and Taz in Scgb1a1+ cells leads to increased Mucin production within the knockout cells in vivo. In order better characterize the in vivo transcriptional changes associated with Yap/Taz knockout in these cells, we have isolated Scgb1a1 lineage traced cells from control and yap/taz cNull mice and performed bulk RNA sequencing.
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:VEGF is a major driver of blood vessel formation. However, the signal transduction pathways culminating into the biological consequences of VEGF signaling are partially understood. Here we show that the Hippo pathway effectors YAP and TAZ, work as a regulatory hub in mediating VEGF-VEGFR2 signaling during angiogenesis. We demonstrate that YAP/TAZ are essential for vascular development as endothelium specific deletion of YAP/TAZ leads to impaired vascularization and embryonic lethality. Mechanistically, we show that VEGF activates YAP/TAZ via its effects on actin cytoskeleton remodeling, and that activated YAP/TAZ induce a transcriptional program that results in the expression of a set of genes to further control cytoskeleton dynamics, and thus ensure a proper angiogenic response. YAP/TAZ deletion also results in VEGFR2 trafficking defects from the Golgi to the plasma membrane. Together, our study establishes YAP/TAZ as a central regulatory hub that mediates VEGF signaling, and hence, regulates angiogenesis.
Project description:VEGF is a major driver of blood vessel formation. However, the signal transduction pathways culminating into the biological consequences of VEGF signaling are partially understood. Here we show that the Hippo pathway effectors YAP and TAZ, work as a regulatory hub in mediating VEGF-VEGFR2 signaling during angiogenesis. We demonstrate that YAP/TAZ are essential for vascular development as endothelium specific deletion of YAP/TAZ leads to impaired vascularization and embryonic lethality. Mechanistically, we show that VEGF activates YAP/TAZ via its effects on actin cytoskeleton remodeling, and that activated YAP/TAZ induce a transcriptional program that results in the expression of a set of genes to further control cytoskeleton dynamics, and thus ensure a proper angiogenic response. YAP/TAZ deletion also results in VEGFR2 trafficking defects from the Golgi to the plasma membrane. Together, our study establishes YAP/TAZ as a central regulatory hub that mediates VEGF signaling, and hence, regulates angiogenesis.
Project description:The two effector proteins of the Hippo signaling pathway, YAP and TAZ, play a pivotal role in the cellular homeostasis of podocytes and in the pathogenesis of focal segmental glomerulosclerosis (FSGS). We aim to unravel the unique and redundant functions of YAP and TAZ in the podocyte by identifying podocyte-specific interactors. We generated stable heat sensitive mouse podocytes (hsMPs) carrying a single copy integration of a transgenic construct expressing a flagged version of mouse Yap (3XFLAG.YAP), Taz (3XFLAG.TAZ) or Ruby (3XFLAG.RUBY) in the Rosa26 locus. To explore the interactome of YAP and TAZ in podocytes we immunoprecipitated the tagged proteins and characterized the co-immunoprecipitated protein complexes by mass spectrometry. Within the interactome analyses of the hsMPs, we identified shared and non-shared interacting proteins between YAP and TAZ. Among these identified proteins many well established interactors of YAP and TAZ were included, like proteins of the Tead family, different angiomotins or large tumor suppressor kinase 1 (Lats1). Strikingly, among the shared proteins were numerous proteins of the nuclear shuttling machinery, like importins (Ipo), exportins (Xpo), transportins (Tnpo) and nucleoporins (Nup) that form the nuclear pore complex (NPC), such as NUP107, NUP133, NUP205 and XPO5.
Project description:Proper lung function relies on precisely balanced numbers of specialized epithelial cell types that work together and are maintained in homeostasis. We describe essential roles for the transcriptional regulators Yap and Taz, which are key effectors of Hippo pathway signaling, in maintaining lung epithelial homeostasis. We report that conditional deletion of Yap1/Yap and Wwtr1/Taz in the lung epithelium of adult mice results in severe defects with consequent animal lethality. Phenotypes associated with Yap/Taz deletion include alveolar defects and a striking development of goblet cell metaplasia throughout the airways. We performed gene expression analysis of wild type and Yap/Taz null primary mouse airway epithelial cells in order to define Yap/Taz controlled gene expression.
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:EGFP (control) and TEADi expressing podocytes were generated by lentivirus transduction to analyze transcriptional signaling by YAP/TAZ-TEAD. Tetracycline-inducible TEADi is a GFP-tagged inhibitor of the interaction of YAP1 and TAZ with TEAD transcription factors. pInducer20 EGFP-TEADi was a gift from Ramiro Iglesias-Bartolome (Addgene plasmid # 140145 ; http://n2t.net/addgene:140145 ; RRID:Addgene_140145). TEADi was previously described: YAP1/TAZ-TEAD transcriptional networks maintain skin homeostasis by regulating cell proliferation and limiting KLF4 activity. Yuan Y., Park J., Feng A., Awasthi P., Wang Z., Chen Q., Iglesias-Bartolome R.. Nat Commun 11, 1472 (2020). 10.1038/s41467-020-15301-0. Transcriptome profiling (RNA-Sequencing) and differential gene expression analysis of 3 independent replicates per genotype was performed. TEADi podocytes exhibit transcriptional changes compared to WT cells including downregulation of prominent YAP target genes like CTGF, CYR61 and ANKRD1.