Project description:It has been shown that up regulation activity of CD81(TAPA-1, the portal of entry of Hepatitis C virus) by agonistic antibody results in phosphorylation of Ezrin. We have previously shown that in liver, Ezrin phosphorylation occurs via Syk kinase, causing suppression of hippo intensity, therefore increases sequential Yap activity. The opposite occurs when Glypican-3 (GPC3) or E2 protein of HCV bind to CD81. Mice over-expressing GPC3 in hepatocytes have decreased p-Ezrin(Thr567) and Yap, increased Hippo activity and suppressed liver regeneration. The role of Ezrin in these processes has been speculated, but not proven. We now provide dynamic picture of Ezrin regulates Hippo pathway and Yap. Forced expression of plasmids expressing mutant Ezrin (T567D) (which mimics p-Ezrin(Thr567)) suppressed Hippo activity and activated Yap signaling. And this mutant Ezrin drive more cell proliferation to cell division through up regulated Yap activity in vitro and in vivo. CD81 loses expression, while p-Ezrin(Thr567) increases in JM1 and JM2 hepatocellular carcinoma (HCC) cells. Administration with compound NSC668394, a characterized p-Ezrin(Thr567) antagonist, caused significant decrease in HCC cell proliferation. We additionally present evidence that pEzrin(T567) is also controlled by EGFR and MET. Conclusions: Ezrin phosphorylation, mediated by CD81 associated Syk kinase, is directly involved in regulation of Hippo pathway, Yap levels and growth rates of normal and neoplastic hepatocytes. The finding has mechanistic and potentially therapeutic applications in understanding and regulating growth of hepatocytes and HCC and HCV pathogenesis. We used microarrays to detail the global programme of gene expression in GFP positive hepatocytes of FVB mice adminstration with EzrinT567D plasmids
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:The Post-translational modification of Hippo/YAP pathway members plays an important role in regulating the activation of Hippo/YAP pathway and its effects in tumors. S-Palmitoylation, also known as S-acylation, is the most common protein Lipid modification, mainly composed of palmitoyl transferases (PATs) from the DHHC (Asp His His Cys) family Catalysis. The results showed that ZDHHC15 mediated palmitoylation of KIBRA up-regulated the expression of YAP downstream target genes, and regulated the invasion function of breast cancer and ovarian cancer cells. The research results will reveal new regulatory mechanisms of the Hippo pathway
Project description:The Post-translational modification of Hippo/YAP pathway members plays an important role in regulating the activation of Hippo/YAP pathway and its effects in tumors. S-Palmitoylation, also known as S-acylation,is the most common protein Lipid modification, mainly composed of palmitoyl transferases (PATs) from the DHHC (Asp His His Cys) family Catalysis. The results showed that ZDHHC15 mediated palmitoylation of KIBRA up-regulated the expression of YAP downstream target genes, and regulated the invasion function of breast cancer and ovarian cancer cells. The research results will reveal new regulatory mechanisms of the Hippo pathway
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.
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:The activation of CD81 [the portal of entry of hepatitis C virus (HCV)] by agonistic antibody results in phosphorylation of Ezrin via Syk kinase and is associated with inactivation of the Hippo pathway and increase in yes-associated protein (Yap1). The opposite occurs when glypican-3 or E2 protein of HCV binds to CD81. Hepatocyte-specific glypican-3 transgenic mice have decreased levels of phosphorylated (p)-Ezrin (Thr567) and Yap, increased Hippo activity, and suppressed liver regeneration. The role of Ezrin in these processes has been speculated, but not proved. We show that Ezrin has a direct role in the regulation of Hippo pathway and Yap. Forced expression of plasmids expressing mutant Ezrin (T567D) that mimics p-Ezrin (Thr567) suppressed Hippo activity and activated Yap signaling in hepatocytes in vivo and enhanced activation of pathways of β-catenin and leucine rich repeat containing G protein-coupled receptor 4 (LGR4) and LGR5 receptors. Hepatoma cell lines JM1 and JM2 have decreased CD81 expression and Hippo activity and up-regulated p-Ezrin (T567). NSC668394, a p-Ezrin (Thr567) antagonist, significantly decreased hepatoma cell proliferation. We additionally show that p-Ezrin (T567) is controlled by epidermal growth factor receptor and MET. Ezrin phosphorylation, mediated by CD81-associated Syk kinase, is directly involved in regulation of Hippo pathway, Yap levels, and growth of normal and neoplastic hepatocytes. The finding has mechanistic and potentially therapeutic applications in hepatocyte growth biology, hepatocellular carcinoma, and HCV pathogenesis.
Project description:Regulation of hepatocyte proliferation and liver morphology is of critical importance to tissue and whole-body homeostasis. However, the molecular mechanisms that underlie this complex process are incompletely understood. Here we describe a novel role for the ubiquitin ligase BRAP in regulation of hepatocyte morphology and turnover via regulation of MST2, a protein kinase in the Hippo pathway. The Hippo pathway has been implicated in control of liver morphology, inflammation and fibrosis. We demonstrate here that liver-specific ablation of Brap in mice results in gross and cellular morphological alterations of the liver. Brap-deficient livers exhibit increased hepatocyte proliferation, cell death, and inflammation. We show that loss of BRAP protein alters Hippo pathway signaling, causing a reduction in phosphorylation of YAP and increased expression of YAP target genes, including those regulating cell growth and interactions with the extracellular environment. Finally, increased Hippo signaling in Brap knockout mice alters the pattern of liver lipid accumulation in dietary models of obesity. These studies identify a role for BRAP as a modulator of the hepatic Hippo pathway with relevance to human liver disease. tissue and whole-body homeostasis. However, the molecular mechanisms that underlie this complex process are incompletely understood. Here we describe a novel role for the ubiquitin ligase BRAP in regulation of hepatocyte morphology and turnover via regulation of MST2, a protein kinase in the Hippo pathway. The Hippo pathway has been implicated in control of liver morphology, inflammation and fibrosis. We demonstrate here that liver-specific ablation of Brap in mice results in gross and cellular morphological alterations of the liver. Brap-deficient livers exhibit increased hepatocyte proliferation, cell death, and inflammation. We show that loss of BRAP protein alters Hippo pathway signaling, causing a reduction in phosphorylation of YAP and increased expression of YAP target genes, including those regulating cell growth and interactions with the extracellular environment. Finally, increased Hippo signaling in Brap knockout mice alters the pattern of liver lipid accumulation in dietary models of obesity. These studies identify a role for BRAP as a modulator of the hepatic Hippo pathway with relevance to human liver disease.
Project description:We identified the Hippo pathway and its effector YAP as a key pathway that controls stellate cell activation. YAP is a transcriptional co-activator and we found that it drives the earliest changes in gene expression during stellate cell activation. Activation of stellate cells in vivo by CCl4 or activation in vitro caused rapid activation of YAP as revealed by its nuclear translocation and the induction of YAP target genes.