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Browsing by Subject "Adaptor Proteins, Signal Transducing"
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Item 14-3-3σ regulation of and interaction with YAP1 in acquired gemcitabine resistance via promoting ribonucleotide reductase expression(Impact Journals, LLC, 2016-04-05) Qin, Li; Dong, Zizheng; Zhang, Jian-Ting; Department of Pharmacology and Toxicology, IU School of MedicineGemcitabine is an important anticancer therapeutics approved for treatment of several human cancers including locally advanced or metastatic pancreatic ductal adenocarcinoma (PDAC). Its clinical effectiveness, however, is hindered by existence of intrinsic and development of acquired resistances. Previously, it was found that 14-3-3σ expression associates with poor clinical outcome of PDAC patients. It was also found that 14-3-3σ expression is up-regulated in gemcitabine resistant PDAC cells and contributes to the acquired gemcitabine resistance. In this study, we investigated the molecular mechanism of 14-3-3σ function in gemcitabine resistance and found that 14-3-3σ up-regulates YAP1 expression and then binds to YAP1 to inhibit gemcitabine-induced caspase 8 activation and apoptosis. 14-3-3σ association with YAP1 up-regulates the expression of ribonucleotide reductase M1 and M2, which may mediate 14-3-3σ/YAP1 function in the acquired gemcitabine resistance. These findings suggest a possible role of YAP1 signaling in gemcitabine resistance.Item Autophagy is a gatekeeper of hepatic differentiation and carcinogenesis by controlling the degradation of Yap(Nature Research, 2018-11-23) Lee, Youngmin A.; Noon, Luke A.; Akat, Kemal M.; Ybanez, Maria D.; Lee, Ting-Fang; Berres, Marie-Luise; Fujiwara, Naoto; Goossens, Nicolas; Chou, Hsin-I; Parvin-Nejad, Fatemeh P.; Khambu, Bilon; Kramer, Elisabeth G.M.; Gordon, Ronald; Pfleger, Cathie; Germain, Doris; John, Gareth R.; Campbell, Kirk N.; Yue, Zhenyu; Yin, Xiao-Ming; Cuervo, Ana Maria; Czaja, Mark J.; Fiel, M. Isabel; Hoshida, Yujin; Friedman, Scott L.; Pathology and Laboratory Medicine, School of MedicineActivation of the Hippo pathway effector Yap underlies many liver cancers, however no germline or somatic mutations have been identified. Autophagy maintains essential metabolic functions of the liver, and autophagy-deficient murine models develop benign adenomas and hepatomegaly, which have been attributed to activation of the p62/Sqstm1-Nrf2 axis. Here, we show that Yap is an autophagy substrate and mediator of tissue remodeling and hepatocarcinogenesis independent of the p62/Sqstm1-Nrf2 axis. Hepatocyte-specific deletion of Atg7 promotes liver size, fibrosis, progenitor cell expansion, and hepatocarcinogenesis, which is rescued by concurrent deletion of Yap. Our results shed new light on mechanisms of Yap degradation and the sequence of events that follow disruption of autophagy, which is impaired in chronic liver disease.Item Critical Role of the mTOR Pathway in Development and Function of Myeloid-Derived Suppressor Cells in lal−/− Mice(Elsevier B.V., 2014-02) Ding, Xinchun; Du, Hong; Yoder, Mervin C.; Yan, Cong; Department of Pathology and Laboratory Medicine, IU School of MedicineLysosomal acid lipase (LAL) is essential for the hydrolysis of cholesteryl esters and triglycerides to generate cholesterol and free fatty acids in cellular lysosomes. Ablation of the lal gene (lal−/−) systemically increased expansion of cluster of differentiation molecule 11b (CD11b), lymphocyte antigen 6G (Ly6G) myeloid-derived suppressor cells (MDSCs) that caused myeloproliferative neoplasms in mice. Study of lal−/− bone marrow Ly6G+ MDSCs via transcriptional profiling showed increases in mammalian target of rapamycin (mTOR) signaling pathway transcripts. Injection of mTOR pharmacologic inhibitors into lal−/− mice significantly reduced bone marrow myelopoiesis and systemic CD11b+Ly6G+ cell expansion. Rapamycin treatment of lal−/− mice stimulated a shift from immature CD11b+Ly6G+ cells to CD11b+ single-positive cells in marrow and tissues and partially reversed the increased cell proliferation, decreased apoptosis, increased ATP synthesis, and increased cell cycling of bone marrow CD11b+Ly6G+ cells obtained from lal−/− mice. Pharmacologic and siRNA suppression of mTOR, regulatory-associated protein of mTOR, rapamycin-insensitive companion of mTOR, and Akt1 function corrected CD11b+Ly6G+ cell in lal−/− mice development from Lin− progenitor cells and reversed the immune suppression on T-cell proliferation and function in association with decreased reactive oxygen species production, and recovery from impairment of mitochondrial membrane potential compared with control mutant cells. These results indicate a crucial role of LAL-regulated mTOR signaling in the production and function of CD11b+Ly6G+ cells. The mTOR pathway may serve as a novel target to modulate the emergence of MDSCs in those pathophysiologic states in which these cells play an immunosuppressive role.Item Designing Visible Light-Cured Thiol-Acrylate Hydrogels for Studying the HIPPO Pathway Activation in Hepatocellular Carcinoma Cells(Wiley Blackwell (John Wiley & Sons), 2016-04) Lin, Tsai-Yu; Bragg, John C.; Lin, Chien-Chi; Department of Biomedical Engineering, School of Engineering and TechnologyVarious polymerization mechanisms have been developed to prepare peptide-immobilized poly(ethylene glycol) (PEG) hydrogels, a class of biomaterials suitable for studying cell biology in vitro. Here, a visible light mediated thiol-acrylate photopolymerization scheme is reported to synthesize dually degradable PEG-peptide hydrogels with controllable crosslinking and degradability. The influence of immobilized monothiol pendant peptide is systematically evaluated on the crosslinking of these hydrogels. Further, methods are proposed to modulate hydrogel crosslinking, including adjusting concentration of comonomer or altering the design of multifunctional peptide crosslinker. Due to the formation of thioether ester bonds, these hydrogels are hydrolytically degradable. If the dithiol peptide linkers used are susceptible to protease cleavage, these thiol-acrylate hydrogels can be designed to undergo partial proteolysis. The differences between linear and multiarm PEG-acrylate (i.e., PEGDA vs PEG4A) are also evaluated. Finally, the use of the mixed-mode thiol-acrylate PEG4A-peptide hydrogels is explored for in situ encapsulation of hepatocellular carcinoma cells (Huh7). The effects of matrix stiffness and integrin binding motif (e.g., RGDS) on Huh7 cell growth and HIPPO pathway activation are studied using PEG4A-peptide hydrogels. This visible light poly-merized thiol-acrylate hydrogel system represents an alternative to existing light-cured hydrogel platforms and shall be useful in many biomedical applications.Item Hypoxic conditions differentially regulate TAZ and YAP in cancer cells(Elsevier, 2014-11-15) Yan, Libo; Cai, Qingchun; Xu, Yan; Department of Obstetrics & Gynecology, IU School of MedicineThe Hippo-YAP pathway is altered and implicated as an oncogenic signaling pathway in many human cancers. Hypoxia is an important microenvironmental factor that promotes tumorigenesis. However, the effects of hypoxia on the two most important Hippo-YAP effectors, YAP (Yes-associated protein) and TAZ (transcriptional co-activator with PDZ-binding motif), have not been reported. In this work, we demonstrated that TAZ was functionally involved in cell proliferation and/or migration in epithelial ovarian cancer (EOC) or human ovarian surface epithelial (HOSE) cells. Hypoxic conditions (1% O2 or hypoxia mimics) induced a reduction of YAP phosphorylation (S127) and total YAP expression in EOC cell lines OVCAR5 and SKOV3. However, these conditions up-regulated levels of S69 phosphorylated TAZ in EOC cells. The known TAZ kinases, Lats1 and Akt, were unlikely to be involved in up-regulated pTAZ by hypoxic conditions. Together, our data revealed new and differential regulating mechanisms of TAZ and YAP in cancer cells by hypoxia conditions.Item Loss of function of hNav1.5 by a ZASP1 mutation associated with intraventricular conduction disturbances in left ventricular noncompaction(Ovid Technologies Wolters Kluwer -American Heart Association, 2012-10) Xi, Yutao; Ai, Tomohiko; De Lange, Enno; Li, Zhaohui; Wu, Geru; Brunelli, Luca; Kyle, W. Buck; Turker, Isik; Cheng, Jie; Ackerman, Michael J.; Kimura, Akinori; Weiss, James N.; Qu, Zhilin; Kim, Jeffrey J.; Faulkner, Georgine; Vatta, Matteo; Department of Medicine, IU School of MedicineBACKGROUND: Defects of cytoarchitectural proteins can cause left ventricular noncompaction, which is often associated with conduction system diseases. We have previously identified a p.D117N mutation in the LIM domain-binding protein 3-encoding Z-band alternatively spliced PDZ motif gene (ZASP) in a patient with left ventricular noncompaction and conduction disturbances. We sought to investigate the role of p.D117N mutation in the LBD3 NM_001080114.1 isoform (ZASP1-D117N) for the regulation of cardiac sodium channel (Na(v)1.5) that plays an important role in the cardiac conduction system. METHODS AND RESULTS: Effects of ZASP1-wild-type and ZASP1-D117N on Na(v)1.5 were studied in human embryonic kidney-293 cells and neonatal rat cardiomyocytes. Patch-clamp study demonstrated that ZASP1-D117N significantly attenuated I(Na) by 27% in human embryonic kidney-293 cells and by 32% in neonatal rat cardiomyocytes. In addition, ZASP1-D117N rightward shifted the voltage-dependent activation and inactivation in both systems. In silico simulation using Luo-Rudy phase 1 model demonstrated that altered Na(v)1.5 function can reduce cardiac conduction velocity by 28% compared with control. Pull-down assays showed that both wild-type and ZASP1-D117N can complex with Na(v)1.5 and telethonin/T-Cap, which required intact PDZ domains. Immunohistochemical staining in neonatal rat cardiomyocytes demonstrates that ZASP1-D117N did not significantly disturb the Z-line structure. Disruption of cytoskeletal networks with 5-iodonaphthalene-1-sulfonyl homopiperazine and cytochalasin D abolished the effects of ZASP1-D117N on Na(v)1.5. CONCLUSIONS: ZASP1 can form protein complex with telethonin/T-Cap and Na(v)1.5. The left ventricular noncompaction-specific ZASP1 mutation can cause loss of function of Na(v)1.5, without significant alteration of the cytoskeletal protein complex. Our study suggests that electric remodeling can occur in left ventricular noncompaction subject because of a direct effect of mutant ZASP on Na(v)1.5.Item PSIP1/p75 promotes tumorigenicity in breast cancer cells by promoting the transcription of cell cycle genes(Oxford University Press, 2017-10-01) Singh, Deepak K.; Gholamalamdari, Omid; Jadaliha, Mahdieh; Li, Xiao Ling; Lin, Yo-Chuen; Zhang, Yang; Guang, Shuomeng; Hashemikhabir, Seyedsasan; Tiwari, Saumya; Zhu, Yuelin J.; Khan, Abid; Thomas, Anu; Chakraborty, Arindam; Macias, Virgilia; Balla, Andre K.; Bhargava, Rohit; Janga, Sarath Chandra; Ma, Jian; Prasanth, Supriya G.; Lal, Ashish; Prasanth, Kannanganattu V.; BioHealth Informatics, School of Informatics and ComputingBreast cancer (BC) is a highly heterogeneous disease, both at the pathological and molecular level, and several chromatin-associated proteins play crucial roles in BC initiation and progression. Here, we demonstrate the role of PSIP1 (PC4 and SF2 interacting protein)/p75 (LEDGF) in BC progression. PSIP1/p75, previously identified as a chromatin-adaptor protein, is found to be upregulated in basal-like/triple negative breast cancer (TNBC) patient samples and cell lines. Immunohistochemistry in tissue arrays showed elevated levels of PSIP1 in metastatic invasive ductal carcinoma. Survival data analyses revealed that the levels of PSIP1 showed a negative association with TNBC patient survival. Depletion of PSIP1/p75 significantly reduced the tumorigenicity and metastatic properties of TNBC cell lines while its over-expression promoted tumorigenicity. Further, gene expression studies revealed that PSIP1 regulates the expression of genes controlling cell-cycle progression, cell migration and invasion. Finally, by interacting with RNA polymerase II, PSIP1/p75 facilitates the association of RNA pol II to the promoter of cell cycle genes and thereby regulates their transcription. Our findings demonstrate an important role of PSIP1/p75 in TNBC tumorigenicity by promoting the expression of genes that control the cell cycle and tumor metastasis.Item Schwannoma development is mediated by Hippo pathway dysregulation and modified by RAS/MAPK signaling(ASCI, 2020-10-15) Chen, Zhiguo; Li, Stephen; Mo, Juan; Hawley, Eric; Wang, Yong; He, Yongzheng; Brosseau, Jean-Philippe; Shipman, Tracey; Clapp, D. Wade; Carroll, Thomas J.; Le, Lu Q.; Pediatrics, School of MedicineSchwannomas are tumors of the Schwann cells that cause chronic pain, numbness, and potentially life-threatening impairment of vital organs. Despite the identification of causative genes, including NF2 (Merlin), INI1/SMARCB1, and LZTR1, the exact molecular mechanism of schwannoma development is still poorly understood. Several studies have identified Merlin as a key regulator of the Hippo, MAPK, and PI3K signaling pathways; however, definitive evidence demonstrating the importance of these pathways in schwannoma pathogenesis is absent. Here, we provide direct genetic evidence that dysregulation of the Hippo pathway in the Schwann cell lineage causes development of multiple schwannomas in mice. We found that canonical Hippo signaling through the effectors YAP/TAZ is required for schwannomagenesis and that MAPK signaling modifies schwannoma formation. Furthermore, cotargeting YAP/TAZ transcriptional activity and MAPK signaling demonstrated a synergistic therapeutic effect on schwannomas. Our new model provides a tractable platform to dissect the molecular mechanisms underpinning schwannoma formation and the role of combinatorial targeted therapy in schwannoma treatment.