Project description:The Hippo pathway functions as a tumor-suppressor pathway in human cancers, while the dys-function of Hippo pathway is frequently observed in malignancies. Although the YAP/TAZ activity is tightly controlled by the phosphorylation cascade of MST-LATS-YAP/TAZ axis, it is still unclear why YAP/TAZ protein is activated in human cancers, even Hippo pathway is still active. Besides phosphorylation, recent studies implicate that several post-translational modifications also play critical roles in modulating TAZ function, including ubiquitination. Here, by a DUB (Deubiquitinases) siRNA screening library, we discovered DUB1 as a critical modulator to facilitate gastric cancer stemness and progression, which deubiquitinated and activated TAZ protein. We also identified DUB1 was elevated in gastric cancer, which correlated with TAZ activation and poor survival. DUB1 associated with TAZ protein and deubiquitinated TAZ at several lysine sites, which subsequently stabilized and facilitated TAZ function. Our study revealed a novel deubiquitinase of Hippo/TAZ axis and one possible therapeutic target for Hippo-driven gastric cancer.
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:The Hippo pathway plays an important role in regulating tissue homeostasis, and its effectors YAP and TAZ are responsible for mediating the vast majority of its physiological functions. Although YAP and TAZ are thought to be largely redundant and similarly regulated by Hippo signaling, they have developmental, structural, and physiological differences which suggest there may be differences in their regulation and downstream functions. To better understand the functions of YAP and TAZ in the Hippo pathway, we generated knockout cells and evaluated them in response to many conditions and stimuli. Here, we used RNA-seq to identify and compare differences in the transcriptional profiles between the YAP and TAZ.
Project description:Aims: Hippo signalling is an evolutionarily conserved pathway that controls organ size by regulating apoptosis, cell proliferation and stem cell self-renewal. Recently, the pathway has been shown to exert powerful growth regulatory activity in cardiomyocytes. However, the functional role of this stress- and cell death-related pathway in the human heart and cardiomyocytes is not known. In this study, we investigated the role of the transcriptional co-activators of Hippo signalling, YAP and TAZ, in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) in response to cardiotoxic agents and investigated the effects of modulating the pathway on cardiomyocyte function and survival. Methods and Results: RNA sequencing analysis of human heart samples with doxorubicin-induced end-stage heart failure and healthy controls showed YAP and ERBB2 (HER2) as upstream regulators of differentially expressed genes correlated with doxorubicin treatment. Thus, we tested the effects of doxorubicin and/or small molecule inhibitor lapatinib on hiPSC-CM in vitro . Using an automated high contentscreen of 96 clinically relevant chemotherapeutic drugs, we showed that doxorubicin induced the highest activation of YAP/TAZ nuclear translocation in both hiPSC-CM and control MCF7 breast cancer cells. The overexpression of YAP rescued doxorubicin- induced cell loss in hiPSC-CM by inhibiting apoptosis and inducing proliferation. In contrast, silencing of YAP and TAZ by siRNAs resulted in elevated mitochondrial membrane potential loss in response to doxorubicin. Human iPSC-CM calcium transients did not change in response to YAP/TAZ silencing. Conclusions: Our results suggest that Hippo signalling is involved in clinical anthracycline-induced cardiomyopathy. Modelling with hiPSC-CM in vitro showed similar responses to doxorubicin as adult cardiomyocytes and revealed a potential cardioprotective effect of YAP in doxorubicin-induced cardiotoxicity.
Project description:The BMP/TGFβ-Smad, Notch and VEGF signaling guides formation of endothelial tip and stalk cells. However, the crosstalk of bone morphogenetic proteins (BMPs) and vascular endothelial growth factor receptor 2 (VEGFR2) signaling has remained largely unknown. We demonstrate that BMP family members regulate VEGFR2 and Notch signaling, and act via TAZ-Hippo signaling pathway. BMPs were found to be regulated after VEGF gene transfer in C57/Bl6 mice and in a porcine myocardial ischemia model. BMPs 2/4/6 were identified as endothelium-specific targets of VEGF. BMP2 modulated VEGF-mediated endothelial sprouting via Delta like Canonical Notch Ligand 4 (DLL4). BMP6 modulated VEGF signaling by regulating VEGFR2 expression and acted via Hippo signaling effector TAZ, known to regulate cell survival/proliferation, and to be dysregulated in cancer. In a matrigel plug assay in nude mice BMP6 was further demonstrated to induce angiogenesis. BMP6 is the first member of BMP family found to directly regulate both Hippo signaling and neovessel formation. It may thus serve as a target in pro/anti-angiogenic therapies.
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:Gastric cancer is still one of the most common cancer types and third leading cause of cancer deaths worldwide. Recent studies have showed that the Hippo signaling pathway plays a critical role in progression of gastric cancer. It is of great importance to demonstrate the regulation of Hippo signaling pathway and the degradation of YAP protein in gastric cancer. In this study, we found that OTUB1 is a critical factor to facilitate gastric cancer cell stemness and progression, which deubiquitinated and stabilized YAP protein.
Project description:The Hippo pathway is crucial in organ size control and tumorigenesis. The dys-regulation of Hippo/YAP axis is vastly observed in gastric cancer, while the effective therapeutic targets for Hippo/YAP axis are still not clear. It is important and urgent to identify reliable drug targets and the underlying mechanisms, which could inhibit the activity of Hippo/YAP axis and gastric cancer progression. In our current study, we demonstrate the membrane receptor CXCR7 (C-X-C chemokine receptor 7) is an important modulator for Hippo/YAP axis. The activation of CXCR7 could stimulate gastric cancer cell progression through Hippo/YAP axis in vitro and in vivo, while pharmaceutical inhibition of CXCR7 via ACT-1004-1239 could block the tumorigenesis in gastric cancer. Molecular studies reveal that the activation of CXCR7 could dephosphorylate YAP, facilitate YAP nuclear accumulation and transcriptional activation in gastric cancer. CXCR7 functions via G-protein Gαq/11 and Rho GTPase to activate YAP activity. Interestingly, ChIP assay shows that YAP could bind to the promoter region of CXCR7 and facilitate its gene transcription, which indicates CXCR7 is both the upstream signaling and downstream target for Hippo/YAP axis in gastric cancer. In general, we identified a novel positive feedback loop between CXCR7 and Hippo/YAP axis, while blockade of CXCR7 could be a plausible strategy for gastric cancer.
Project description:The Hippo pathway is an emerging signaling cascade involved in the regulation of organ size control. It consists of evolutionally conserved protein kinases that are sequentially phosphorylated and activated. The active Hippo pathway subsequently phosphorylates a transcription coactivator, YAP, which precludes its nuclear localization and transcriptional activation. Identification of transcriptional targets of YAP in diverse cellular contexts is therefore critical to the understanding of the molecular mechanisms in which the Hippo pathway restricts tissue growth. We used microarrays to profile the gene expression patterns upon acute siRNA knockdown of Hippo pathway components in multiple mammalian cell lines and identified a set of genes representing immediate transcriptional targets of the Hippo/Yap signaling pathway. Three mammalian cell lines (HEK293T, HepG2, HaCaT) were transfected with scramble siRNA controls or siRNAs against NF2 and LATS2, two core components of the Hippo pathway, simultaneously. Total RNAs were harvested four days after transfection to reveal the gene expression pattern unsing microarry. YAP and TAZ siRNAs were also transfected along with NF2 and LATS2 siRNAs to identify YAP/TAZ-dependent transcriptional targets upon loss of NF2/LATS2.
Project description:We used RNA-seq to study the function of FABP5 in gastric cancer cells (AGS and MGC803). Down-regulation of FABP5 suppressed cell proliferation, cell migration and invasion, and induced cell apoptosis. Bioinformatics analysis revealed that Hippo signaling pathway was related to FABP5 in GC cells.Our data suggested that FABP5 might act as a potential target associated with Hippo signaling pathway for GC treatment.