Project description:Splicing dysregulations extensively occur in cancers, yet the biological consequences of such alterations are mostly undefined. Here we report that the Hippo-YAP signaling, a key pathway that regulates cell proliferation and organ size, is under control of a new splicing switch. We show that TEAD4, the transcription factor that mediates Hippo-YAP signaling, undergoes alternative splicing facilitated by the tumor suppressor RBM4, producing a truncated isoform, TEAD4-S, which lacks N-terminal DNA-binding domain but maintains YAP-interaction domain. TEAD4-S is located in both nucleus and cytoplasm, acting as a dominant negative isoform to YAP activity. Consistently, TEAD4-S is reduced in cancer cells, and its re-expression suppresses cancer cell proliferation and migration, inhibiting tumor growth in xenograft mouse model. Furthermore, TEAD4-S is reduced in human cancers, and patients with elevated TEAD4-S levels have improved survival. Altogether these data reveal a novel RBM4-mediated splicing switch that serves to fine-tune Hippo-YAP pathway. Cell lines stably expressing YAP, YAP/TEAD4-S, YAP/TEAD4-FL, YAP/RBM4 and control vector were created, and the total RNA was purified from the cells using TRIzol reagents. The polyadenylated RNAs were purified for construction of sequencing library using kapa TruSeq Total RNA Sample Prep kits (UNC High Throughput Sequencing Facility).
Project description:To know the crosstalk between Hippo and AKT pathways in the liver metabolism, we generated liver-specific Pten (AKT signaling), Sav1 (Hippo signaling) and double-knockout mice and analysed the liver mRNA expression globally from 4groups (WT, Pten KO, Sav1 KO and Pten;Sav1 dKO).
Project description:Background—YAP, the nuclear effector of Hippo signaling, regulates cellular growth and survival in multiple organs, including the heart, by interacting with TEAD sequence specific DNA-binding proteins. Recent studies showed that YAP stimulates cardiomyocyte proliferation and survival. However, the direct transcriptional targets through which YAP exerts its effects are poorly defined. Methods and Results—To identify genes directly regulated by YAP in cardiomyocytes, we combined differential gene expression analysis in YAP gain- and loss-of-function with genome-wide identification of YAP bound loci using chromatin immunoprecipitation and high throughput sequencing. This screen identified Pik3cb, encoding p110β, a catalytic subunit of phosphoinositol-3-kinase (PI3K), as a candidate YAP effector that promotes cardiomyocyte proliferation and survival. We validated YAP and TEAD occupancy of a conserved enhancer within the first intron of Pik3cb, and show that this enhancer drives YAP-dependent reporter gene expression. Yap gain- and loss-of-function studies indicated that YAP is necessary and sufficient to activate the PI3K-Akt pathway. Like Yap, Pik3cb gain-of-function stimulated cardiomyocyte proliferation, and Pik3cb knockdown dampened the YAP mitogenic activity. Reciprocally, Yap loss-of-function impaired heart function and reduced cardiomyocyte proliferation and survival, all of which were significantly rescued by AAV-mediated Pik3cb expression. Conclusion—Pik3cb is a crucial direct target of YAP, through which the YAP activates PI3K-AKT pathway and regulates cardiomyocyte proliferation and survival. Yap wild type ChIPseq and input
Project description:YAP is an oncogene and an inducer of Epithelial-to-Mesenchymal Transition (EMT). We used microarrays to detail the global program of gene expression to identify YAP target genes. PUBLICATION ABSTRACT:; The Hippo pathway defines a novel signaling cascade regulating cell proliferation and survival in Drosophila, which involves the negative regulation of the transcriptional coactivator Yorkie by the kinases Hippo and Warts. We have recently shown that the human ortholog of Yorkie, YAP, maps to a minimal amplification locus in mouse and human cancers, and that it mediates dramatic transforming activity in MCF10A primary mammary epithelial cells. Here we show that LATS proteins (mammalian orthologs of Warts) interact directly with YAP in mammalian cells and that ectopic expression of LATS1, but not LATS2, effectively suppresses the YAP phenotypes. Furthermore, shRNA-mediated knockdown of LATS1 phenocopies YAP overexpression. Since this effect can be suppressed by simultaneous YAP knockdown, it suggests that YAP is the primary target of LATS1 in mammalian cells. Expression profiling of genes induced by ectopic expression of YAP or by knockdown of LATS1 reveals a subset of potential Hippo pathway targets implicated in epithelial-to-mesenchymal transition (EMT), suggesting that this is a key feature of YAP signaling in mammalian cells. Experiment Overall Design: MCF10A cells were infected with retrovirus constructs (vector or YAP) and puromycin was used to select for transduced cells. Cells were split and grown to ~60-75%% confluency at which point they were harvested for RNA. Vector vs. YAP comparison was done in duplicate.
Project description:Background—YAP, the nuclear effector of Hippo signaling, regulates cellular growth and survival in multiple organs, including the heart, by interacting with TEAD sequence specific DNA-binding proteins. Recent studies showed that YAP stimulates cardiomyocyte proliferation and survival. However, the direct transcriptional targets through which YAP exerts its effects are poorly defined. Methods and Results—To identify genes directly regulated by YAP in cardiomyocytes, we combined differential gene expression analysis in YAP gain- and loss-of-function with genome-wide identification of YAP bound loci using chromatin immunoprecipitation and high throughput sequencing. This screen identified Pik3cb, encoding p110β, a catalytic subunit of phosphoinositol-3-kinase (PI3K), as a candidate YAP effector that promotes cardiomyocyte proliferation and survival. We validated YAP and TEAD occupancy of a conserved enhancer within the first intron of Pik3cb, and show that this enhancer drives YAP-dependent reporter gene expression. Yap gain- and loss-of-function studies indicated that YAP is necessary and sufficient to activate the PI3K-Akt pathway. Like Yap, Pik3cb gain-of-function stimulated cardiomyocyte proliferation, and Pik3cb knockdown dampened the YAP mitogenic activity. Reciprocally, Yap loss-of-function impaired heart function and reduced cardiomyocyte proliferation and survival, all of which were significantly rescued by AAV-mediated Pik3cb expression. Conclusion—Pik3cb is a crucial direct target of YAP, through which the YAP activates PI3K-AKT pathway and regulates cardiomyocyte proliferation and survival. Two groups were involved in this study:TNTcreYapfl_het group and TNTcreYapfl_KO group. Each group contained three biological replicates. Embryo hearts were collected at E12.5 and dissociated. Cardiomyocytes were collected by FACS. The total RNA of cardiomyocytes were isolated for microarray analysis.
Project description:Cardiomyocyte (CM) loss after injury results in adverse remodelling and fibrosis, which inevitably lead to heart failure. Neuregulin-ErbB2 and Hippo-Yap signaling pathways are key mediators of CM proliferation and regeneration although the crosstalk between these pathways is unclear. Here, we demonstrate in mice that temporal over-expression (OE) of activated ErbB2 in CMs promotes cardiac regeneration in a heart failure model. Cellularly, OE CMs present an EMT-like regenerative response involving cytoskeletal reprograming, migration, ECM turnover, and displacement. Molecularly, we identified Yap as a critical mediator of ErbB2 signaling. In OE CMs, Yap interacts with nuclear envelope and cytoskeletal components, reflective of the altered mechanic state elicited by ErbB2. Hippo-independent activating phosphorylation on Yap at S352 and S274 were enriched in OE CMs, peaking during metaphase. Viral overexpression of Yap phospho-mutants dampened the proliferative competence of OE CMs. Taken together, we demonstrate a potent ErbB2-mediated Yap mechanosensory signaling involving EMT-like characteristics, resulting in heart regeneration.
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 prevalent understanding of Hippo signaling is one inhibitory pathway in tumor growth via deactivating the potential of YAP-TEAD transcriptional complex. The aberrant activation of YAP was observed in a series of human malignancies. However, recent studies implicate that in certain cancer types, YAP could be a tumor suppressor. Here, we reported a context-dependent function of YAP in clear cell renal carcinoma (ccRCC). Inhibition of Hippo kinase activity impeded ccRCC tumor growth and NF-κB transcriptional programs. Pharmacological blocking Hippo kinase activity or ectopic activation of YAP suppressed tumor growth in xenograft and PDX models. Mechanism studies revealed that TEAD could synchronize with P65 for NF-κB signaling activation, while YAP disrupted TEAD-NF-κB interactions and dissociated P65 from its target gene promoter, thereby inhibiting NF-κB transcriptional programs and ccRCC tumor growth. Our study identified a novel crosstalk between Hippo and NF-κB pathway, uncovered a non-canonical regulation of Hippo/YAP axis in renal cancer and suggested a novel strategy to ccRCC treatments by YAP activation.
Project description:The prevalent understanding of Hippo signaling is one inhibitory pathway in tumor growth via deactivating the potential of YAP-TEAD transcriptional complex. The aberrant activation of YAP was observed in a series of human malignancies. However, recent studies implicate that in certain cancer types, YAP could be a tumor suppressor. Here, we reported a context-dependent function of YAP in clear cell renal carcinoma (ccRCC). Inhibition of Hippo kinase activity impeded ccRCC tumor growth and NF-κB transcriptional programs. Pharmacological blocking Hippo kinase activity or ectopic activation of YAP suppressed tumor growth in xenograft and PDX models. Mechanism studies revealed that TEAD could synchronize with P65 for NF-κB signaling activation, while YAP disrupted TEAD-NF-κB interactions and dissociated P65 from its target gene promoter, thereby inhibiting NF-κB transcriptional programs and ccRCC tumor growth. Our study identified a novel crosstalk between Hippo and NF-κB pathway, uncovered a non-canonical regulation of Hippo/YAP axis in renal cancer and suggested a novel strategy to ccRCC treatments by YAP activation.
Project description:Sarcomas encompass heterogenous, difficult to treat cancers, lacking common therapeutic targets. Phosphatidylinositol-3 kinase (PI3K) signaling is activated in sarcomas to a greater degree than previously appreciated due to phosphatase and tensin homolog (PTEN) loss, and could represent such a target. Targeting PI3K signaling has largely focused on targeting mTORC1, considered the main effector of PI3K signaling, but this has not translated to success in the clinic, suggesting that there may be other effectors downstream of PI3K. One gap in our understanding of the PI3K signaling pathway has been the absence of a known oncogenic transcription factor. Herein we implicate TAZ and YAP as additional transcriptional effectors downstream of PI3K signaling regulated by a LATS1/2 dependent mechanism. Using in vitro and in vivo approaches, we show that TAZ and YAP are central oncoproteins in PI3K driven oncogenesis along with mTORC1, providing a rationale for combination therapy. Leveraging these findings, we describe a therapeutic approach that builds upon pre-existing therapeutic strategies utilizing mTORC1 inhibitors and combines them with new TEAD inhibitors that target YAP and TAZ. Combination therapy using everolimus and IK-930, an inhibitor targeting autopalmitoylation of the TEADs, synergistically diminished proliferation and anchorage dependent growth of PI3K activated sarcoma cell lines at low, physiologically achievable doses. In vivo, this combination therapy showed a synergistic effect, contrasting with the lack of effect of the individual single agent therapies, suggesting that an integrated view of PI3K and Hippo signaling can be leveraged therapeutically in PI3K activated sarcomas.