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Krakowian D, Lesiak M, Auguściak-Duma A, Witecka J, Kusz D, Sieroń AL, Gawron K. Analysis of the TID-I and TID-L Splice Variants' Expression Profile under In Vitro Differentiation of Human Mesenchymal Bone Marrow Cells into Osteoblasts. Cells 2024; 13:1021. [PMID: 38920651 PMCID: PMC11201664 DOI: 10.3390/cells13121021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2024] [Revised: 06/08/2024] [Accepted: 06/09/2024] [Indexed: 06/27/2024] Open
Abstract
Bone formation is a complex process regulated by a variety of pathways that are not yet fully understood. One of the proteins involved in multiple osteogenic pathways is TID (DNAJA3). The aim of this work was to study the association of TID with osteogenesis. Therefore, the expression profiles of the TID splice variants (TID-L, TID-I) and their protein products were analyzed during the proliferation and differentiation of bone marrow mesenchymal stromal cells (B-MSCs) into osteoblasts. As the reference, the hFOB1.19 cell line was used. The phenotype of B-MSCs was confirmed by the presence of CD73, CD90, and CD105 surface antigens on ~97% of cells. The osteoblast phenotype was confirmed by increased alkaline phosphatase activity, calcium deposition, and expression of ALPL and SPP1. The effect of silencing the TID gene on the expression of ALPL and SPP1 was also investigated. The TID proteins and the expression of TID splice variants were detected. After differentiation, the expression of TID-L and TID-I increased 5-fold and 3.7-fold, respectively, while their silencing resulted in increased expression of SPP1. Three days after transfection, the expression of SPP1 increased 7.6-fold and 5.6-fold in B-MSCs and differentiating cells, respectively. Our preliminary study demonstrated that the expression of TID-L and TID-I changes under differentiation of B-MSCs into osteoblasts and may influence the expression of SPP1. However, for better understanding the functional association of these results with the relevant osteogenic pathways, further studies are needed.
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Affiliation(s)
- Daniel Krakowian
- Department of Molecular Biology and Genetics, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-055 Katowice, Poland
- Toxicology Research Group, Łukasiewicz Research Network—Institute of Industrial Organic Chemistry Branch Pszczyna, 43-200 Pszczyna, Poland
| | - Marta Lesiak
- Department of Molecular Biology and Genetics, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-055 Katowice, Poland
| | - Aleksandra Auguściak-Duma
- Department of Molecular Biology and Genetics, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-055 Katowice, Poland
| | - Joanna Witecka
- Department of Molecular Biology and Genetics, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-055 Katowice, Poland
- Department of Parasitology, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia, 41-200 Sosnowiec, Poland
| | - Damian Kusz
- Department of Orthopaedics and Traumatology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-055 Katowice, Poland
| | - Aleksander L. Sieroń
- Department of Molecular Biology and Genetics, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-055 Katowice, Poland
| | - Katarzyna Gawron
- Department of Molecular Biology and Genetics, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-055 Katowice, Poland
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Loss of Tid1/DNAJA3 Co-Chaperone Promotes Progression and Recurrence of Hepatocellular Carcinoma after Surgical Resection: A Novel Model to Stratify Risk of Recurrence. Cancers (Basel) 2021; 13:cancers13010138. [PMID: 33406664 PMCID: PMC7795123 DOI: 10.3390/cancers13010138] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 12/29/2020] [Indexed: 12/15/2022] Open
Abstract
Simple Summary Tid1 acts as a tumor suppressor in various cancer types, however, its role in hepatocellular carcinoma (HCC) remains unclear. Here, we observed a low protein level of Tid1 in poorly differentiated HCC cell lines. The expression of Tid1 affected the malignancy in human HCC cell lines; meanwhile the protein level of Nrf2 was negatively regulated by Tid1. In multivariate analysis, using immunohistochemical (IHC) assay in 210 HCC cases, we found the tumor size > 5 cm, multiple tumors, presence of vascular invasion, low Tid1 expression in the non-tumor part, and high Nrf2 expression in the non-tumor part, were independently associated with worse recurrence-free survival (RFS). A scoring system by integrating the five clinical and pathological factors predicts the RFS among HCC patients after surgical resection. In summary, Tid1 plays a prognostic role for surgically resected HCC. Abstract Tid1, a mitochondrial co-chaperone protein, acts as a tumor suppressor in various cancer types. However, the role of Tid1 in hepatocellular carcinoma (HCC) remains unclear. First, we found that a low endogenous Tid1 protein level was observed in poorly differentiated HCC cell lines. Further, upregulation/downregulation of Tid1 abrogated/promoted the malignancy of human HCC cell lines, respectively. Interestingly, Tid1 negatively modulated the protein level of Nrf2. Tissue assays from 210 surgically resected HCC patients were examined by immunohistochemistry (IHC) analyses. The protein levels of Tid1 in the normal and tumor part of liver tissues were correlated with the clinical outcome of the 210 HCC cases. In multivariate analysis, we discovered that tumor size > 5 cm, multiple tumors, presence of vascular invasion, low Tid1 expression in the non-tumor part, and high Nrf2 expression in the non-tumor part were significant factors associated with worse recurrence-free survival (RFS). A scoring system by integrating the five clinical and pathological factors predicts the RFS among HCC patients after surgical resection. Together, Tid1, serving as a tumor suppressor, has a prognostic role for surgically resected HCC to predict RFS.
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Coomer AO, Black F, Greystoke A, Munkley J, Elliott DJ. Alternative splicing in lung cancer. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194388. [PMID: 31152916 DOI: 10.1016/j.bbagrm.2019.05.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 05/20/2019] [Indexed: 12/21/2022]
Abstract
Lung cancer has the highest mortality rate of all cancers worldwide. Lung cancer is a very heterogeneous disease that is often diagnosed at later stages which have a poor prognosis. Aberrant alternative splicing patterns found in lung cancer contribute to important cell functions. These include changes in splicing for the BCL2L1, MDM2, MDM4, NUMB and MET genes during lung tumourigenesis, to affect pathways involved in apoptosis, cell proliferation and cellular cohesion. Global analyses of RNASeq datasets suggest there may be many more potentially influential aberrant splicing events that need to be investigated in lung cancer. Changes in expression of the splicing factors that regulate alternative splicing events have also been identified in lung cancer. Of these, changes in expression of QKI, RBM4, RBM5, RBM6, RBM10 and SRSF1 proteins regulate many of the most frequently referenced aberrant splicing events in lung cancer. The expanding list of genes known to be aberrantly spliced in lung cancer along with the altered expression of splicing factors that regulate them are providing new clues as to how lung cancer develops, and how these events can be exploited for better treatment. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.
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Affiliation(s)
- Alice O Coomer
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, United Kingdom of Great Britain and Northern Ireland.
| | - Fiona Black
- Cellular Pathology Department, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, United Kingdom of Great Britain and Northern Ireland
| | - Alastair Greystoke
- Northern Institute for Cancer Research, Paul O'Gorman Building, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom of Great Britain and Northern Ireland
| | - Jennifer Munkley
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, United Kingdom of Great Britain and Northern Ireland
| | - David J Elliott
- Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle upon Tyne NE1 3BZ, United Kingdom of Great Britain and Northern Ireland.
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Chen CY, Jan CI, Pi WC, Wang WL, Yang PC, Wang TH, Karni R, Wang TCV. Heterogeneous nuclear ribonucleoproteins A1 and A2 modulate expression of Tid1 isoforms and EGFR signaling in non-small cell lung cancer. Oncotarget 2017; 7:16760-72. [PMID: 26919236 PMCID: PMC4941349 DOI: 10.18632/oncotarget.7606] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/10/2016] [Indexed: 11/25/2022] Open
Abstract
The Tid1 protein is a DnaJ co-chaperone that has two alternative splicing isoforms: Tid1 long form (Tid1-L) and Tid1 short form (Tid1-S). Recent studies have shown that Tid1-L functions as a tumor suppressor by decreasing EGFR signaling in various cancers, including head and neck cancer and non-small cell lung cancer (NSCLC). However, the molecular mechanism responsible for regulating the alternative splicing of Tid1 is not yet known. Two splicing factors, heterogeneous nuclear ribonucleoproteins (hnRNP) A1 and A2, participate in alternative splicing and are known to be overexpressed in lung cancers. In this work, we examined if hnRNP A1 and A2 could regulate the alternative splicing of Tid1 to modulate tumorigenesis in NSCLC. We report that RNAi-mediated depletion of both hnRNP A1/A2 (but not single depletion of either) increased Tid1-L expression, inhibited cell proliferation and attenuated EGFR signaling. Analyses of the expression levels of hnRNP A1, hnRNP A2, EGFR and Tid1-L in NSCLC tissues revealed that hnRNP A1 and A2 are positively correlated with EGFR, but negatively correlated with Tid1-L. NSCLC patients with high-level expression of hnRNP A1, hnRNP A2 and EGFR combined with low-level expression of Tid1-L were associated with poor overall survival. Taken together, our results suggest that hnRNP A1 or A2 are both capable of facilitating the alternative splicing of exon 11 in the Tid1 pre-mRNA, thereby suppressing the expression of Tid1-L and allowing EGFR-related signaling to facilitate NSCLC tumorigenesis.
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Affiliation(s)
- Chi-Yuan Chen
- Graduate Institute of Health Industry Technology and Research Center for Industry of Human Ecology, College of Human Ecology, Chang Gung University of Science and Technology, Kwei-San, Tao-Yuan 333, Taiwan
| | - Chia-Ing Jan
- Department of Pathology, China Medical University and Hospital, Taichung, Taiwan 404, Taiwan.,Department of Pathology, China Medical University and Beigang Hospital, Yunlin, Taiwan 651, Taiwan
| | - Wen-Chieh Pi
- Department of Molecular and Cellular Biology, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan 333, Taiwan
| | - Wen-Lung Wang
- Department of Otolaryngology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung City 833, Taiwan
| | - Pan-Chyr Yang
- Department of Internal Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Tong-Hong Wang
- Graduate Institute of Health Industry Technology and Research Center for Industry of Human Ecology, College of Human Ecology, Chang Gung University of Science and Technology, Kwei-San, Tao-Yuan 333, Taiwan.,Tissue Bank, Chang Gung Memorial Hospital, Tao-Yuan 333, Taiwan
| | - Rotem Karni
- The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Ein Karem, 91120, Jerusalem, Israel
| | - Tzu-Chien V Wang
- Department of Molecular and Cellular Biology, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan 333, Taiwan
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Tid1-S regulates the mitochondrial localization of EGFR in non-small cell lung carcinoma. Oncogenesis 2017; 6:e361. [PMID: 28714950 PMCID: PMC5541714 DOI: 10.1038/oncsis.2017.62] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/21/2017] [Accepted: 06/13/2017] [Indexed: 12/12/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) is the major driver of non-small cell lung carcinoma (NSCLC). Mitochondrial accumulation of EGFR has been shown to promote metastasis in NSCLC, yet little is known about how the mitochondrial localization of EGFR is regulated. In this work, we show that Tid1 (also known as mitochondrial HSP40) is involved in the mitochondrial localization of EGFR, and that the DnaJ domain of Tid1-S is essential for the Tid1-S-mediated transportation of EGFR into mitochondria. Overexpression of Tid1-S increased the migration and invasion of NSCLC cells cultured in vitro. High levels of EGFR and Tid1-S were detected in the mitochondria of cancerous lesions from stage IV NSCLC patients, and high levels of mitochondrial Tid1-S/EGFR were correlated with lymph node metastasis and poor overall survival of NSCLC patients. We thus conclude that Tid1-S critically governs the mitochondrial localization of EGFR through the mtHSP70 transportation pathway, and that the mitochondrial accumulation of EGFR appears to promote metastasis in NSCLC.
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Chen CY, Jan CI, Lo JF, Yang SC, Chang YL, Pan SH, Wang WL, Hong TM, Yang PC. Tid1-L inhibits EGFR signaling in lung adenocarcinoma by enhancing EGFR Ubiquitinylation and degradation. Cancer Res 2013; 73:4009-19. [PMID: 23698466 DOI: 10.1158/0008-5472.can-12-4066] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Tid1 (DNAJA3), a DnaJ cochaperone, may promote degradation of oncogenic kinases. Tid1 has 2 isoforms, Tid1-L and Tid1-S, that may function differently. In this study, we investigated the role of the Tid1 isoforms in regulating EGF receptor (EGFR) signaling and lung cancer progression. We found that both Tid1-L and Tid1-S expressions were reduced in patients with non-small cell lung cancer compared with normal counterparts. Tid1-L expression correlated inversely with EGFR expression. Low Tid1-L/high EGFR expression predicted poor overall survival in patients with lung adenocarcinoma. Tid1-L overexpression in lung cancer cells attenuated EGFR signaling and inhibited cell proliferation, colony formation, and tumor growth in subcutaneous and orthotropic xenograft models. Conversely, depletion of Tid1 restored EGFR signaling and increased cell proliferation and colony formation. Tid1-L, but not Tid1-S, interacted with EGFR/HSP70/HSP90 through the DnaJ domain, counteracting the EGFR regulatory function of HSP90 by causing EGFR ubiquitinylation and proteasomal degradation. Tid1-L inhibited EGFR signaling even more than the HSP90 inhibitor 17-allylamino-demethoxy geldanamycin. We concluded that Tid1-L acted as a tumor suppressor by inhibiting EGFR signaling through interaction with EGFR/HSP70/HSP90 and enhancing EGFR ubiquitinylation and degradation.
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Affiliation(s)
- Chi-Yuan Chen
- Department of Nutrition and Health Sciences, Chang Gung University of Science and Technology, Taoyuan, Taiwan
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Proft J, Faraji J, Robbins JC, Zucchi FCR, Zhao X, Metz GA, Braun JEA. Identification of bilateral changes in TID1 expression in the 6-OHDA rat model of Parkinson's disease. PLoS One 2011; 6:e26045. [PMID: 22016808 PMCID: PMC3189242 DOI: 10.1371/journal.pone.0026045] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 09/16/2011] [Indexed: 01/06/2023] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra and the aggregation of α-synuclein into Lewy bodies. Existing therapies address motor dysfunction but do not halt progression of the disease. A still unresolved question is the biochemical pathway that modulates the outcome of protein misfolding and aggregation processes in PD. The molecular chaperone network plays an important defensive role against cellular protein misfolding and has been identified as protective in experimental models of protein misfolding diseases like PD. Molecular mechanisms underlying chaperone-neuroprotection are actively under investigation. Current evidence implicates a number of molecular chaperones in PD including Hsp25, Hsp70 and Hsp90, however their precise involvement in the neurodegenerative cascade is unresolved. The J protein family (DnaJ or Hsp40 protein family) has long been known to be important in protein conformational processes.We assessed sensory and motor function of control and PD rats and then evaluated the brain region-specific expression levels of select J proteins by Western analysis. Surprisingly, we observed a widespread 26 kDa breakdown product of the J protein, TID1, (tumorous imaginal discs, mtHsp40 or DnaJ3) in a 6-hydroxydopamine (6-OHDA) rat model of PD in which food handling, gait symmetry and sensory performance were impaired. Greater behavioral deficits were associated with lower TID1 expression. Furthermore, direct application of either 6-OHDA or MPP+ (1-methyl-4-phenylpyridinum) to CAD (CNS-derived catecholinaminergic neuronal cell line) cell cultures, reduced TID1 expression levels.Our results suggest that changes in cellular TID1 are a factor in the pathogenesis of PD by impeding functional and structural compensation and exaggerating neurodegenerative processes. In contrast, no changes were observed in CSPα, Hsp40, Hsp70, Hsc70 and PrP(C) levels and no activation of caspase3 was observed. This study links TID1 to PD and provides a new target for therapeutics that halts the PD progression.
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Affiliation(s)
- Juliane Proft
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Canada
| | - Jamshid Faraji
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada
- Neuroscience Research Centre, Golestan University of Medical Sciences, Gorgan, Islamic Republic of Iran
| | - Jerrah C. Robbins
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada
| | - Fabiola C. R. Zucchi
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada
| | - Xiaoxi Zhao
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Canada
| | - Gerlinde A. Metz
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Canada
| | - Janice E. A. Braun
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Canada
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Mechanisms Regulating Microtubule Binding, DNA Replication, and Apoptosis are Controlled by the Intestinal Tumor Suppressor APC. CURRENT COLORECTAL CANCER REPORTS 2011; 7:145-151. [PMID: 23308069 DOI: 10.1007/s11888-011-0088-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Colorectal cancer (CRC) results from the progressive accumulation of both genetic and epigenetic alterations that lead to the transformation of normal colorectal epithelium to benign (adenoma) and invasive (carcinoma) disease. Since its discovery in mutated form as the causative gene for familial adenomatous polyposis coli (FAP), as well as in many sporadic CRCs, the APC tumor suppressor has been shown to possess numerous functions within the cell including regulation of WNT signaling pathways and its transcriptional effects, cell migration, and chromosome separation. In recent years, other novel roles for APC have been investigated and suggest that APC can also repress DNA replication and enhance apoptosis. Further insights into the mechanisms by which APC contributes to tumor suppression will accelerate the diagnosis and treatment of CRC.
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Abstract
The c-Met receptor tyrosine kinase (MetR) is frequently overexpressed and constitutively phosphorylated in a number of human malignancies. Activation of the receptor by its ligand, hepatocyte growth factor (HGF), leads to increased cell proliferation, motility, survival and disruption of adherens junctions. In this study, we show that hTid-1, a DNAJ/Hsp40 chaperone, represents a novel modulator of the MetR signaling pathway. hTid-1 is a co-chaperone of the Hsp70 family of proteins, and has been shown to regulate a number of cellular signaling proteins including several involved in tumorigenic and apoptotic pathways. In this study we demonstrate that hTid-1 binds to unphosphorylated MetR and becomes dissociated from the receptor upon HGF stimulation. Overexpression of the short form of hTid-1 (hTid-1(S)) in 786-0 renal clear cell carcinomas (RCCs) enhances MetR kinase activity leading to an increase in HGF-mediated cell migration with no discernible effect on cell proliferation. By contrast, knockdown of hTid-1 markedly impairs both the onset and amplitude of MetR phosphorylation in response to HGF without altering receptor protein levels. hTid-1-depleted cells display defective migratory properties, coincident with inhibition of ERK/MAP kinase and STAT3 pathways. Taken together, our findings denote hTid-1(S) as an essential regulatory component of MetR signaling. We propose that the binding of hTid-1(S) to MetR may stabilize the receptor in a ligand-competent state and this stabilizing function may influence conformational changes that take place during the catalytic cycle that promote kinase activation. Given the prevalence of HGF/MetR pathway activation in human cancers, targeted inhibition of hTid-1 may be a useful therapeutic in the management of MetR-dependent malignancies.
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Gomez AM, Van Den Broeck J, Vrolix K, Janssen SP, Lemmens MAM, Van Der Esch E, Duimel H, Frederik P, Molenaar PC, Martínez-Martínez P, De Baets MH, Losen M. Antibody effector mechanisms in myasthenia gravis-pathogenesis at the neuromuscular junction. Autoimmunity 2010; 43:353-70. [PMID: 20380584 DOI: 10.3109/08916930903555943] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Myasthenia gravis (MG) is an autoimmune disorder caused by autoantibodies that are either directed to the muscle nicotinic acetylcholine receptor (AChR) or to the muscle-specific tyrosine kinase (MuSK). These autoantibodies define two distinct subforms of the disease-AChR-MG and MuSK-MG. Both AChR and MuSK are expressed on the postsynaptic membrane of the neuromuscular junction (NMJ), which is a highly specialized region of the muscle dedicated to receive and process signals from the motor nerve. Autoantibody binding to proteins of the postsynaptic membrane leads to impaired neuromuscular transmission and muscle weakness. Pro-inflammatory antibodies of the human IgG1 and IgG3 subclass modulate the AChR, cause complement activation, and attract lymphocytes; together acting to decrease levels of the AChR and AChR-associated proteins and to reduce postsynaptic folding. In patients with anti-MuSK antibodies, there is no evidence of loss of junctional folds and no apparent loss of AChR density. Anti-MuSK antibodies are predominantly of the IgG4 isotype, which functionally differs from other IgG subclasses in its anti-inflammatory activity. Moreover, IgG4 undergoes a posttranslational modification termed Fab arm exchange that prevents cross-linking of antigens. These findings suggest that MuSK-MG may be different in etiological and pathological mechanisms from AChR-MG. The effector functions of IgG subclasses on synapse structure and function are discussed in this review.
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Affiliation(s)
- Alejandro M Gomez
- Neuroimmunology Group, Department of Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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Dhennin-Duthille I, Nyga R, Yahiaoui S, Gouilleux-Gruart V, Régnier A, Lassoued K, Gouilleux F. The tumor suppressor hTid1 inhibits STAT5b activity via functional interaction. J Biol Chem 2010; 286:5034-42. [PMID: 21106534 DOI: 10.1074/jbc.m110.155903] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
STAT5a and -5b (signal transducers and activators of transcription 5a and 5b) proteins play an essential role in hematopoietic cell proliferation and survival and are frequently constitutively active in hematologic neoplasms and solid tumors. Because STAT5a and STAT5b differ mainly in the carboxyl-terminal transactivation domain, we sought to identify new proteins that bind specifically to this domain by using a bacterial two-hybrid screening. We isolated hTid1, a human DnaJ protein that acts as a tumor suppressor in various solid tumors. hTid1 interacts specifically with STAT5b but not with STAT5a in hematopoietic cell lines. This interaction involves the cysteine-rich region of the hTid1 DnaJ domain. We also demonstrated that hTid1 negatively regulates the expression and transcriptional activity of STAT5b and suppresses the growth of hematopoietic cells transformed by an oncogenic form of STAT5b. Our findings define hTid1 as a novel partner and negative regulator of STAT5b.
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Affiliation(s)
- Isabelle Dhennin-Duthille
- INSERM, U925, Université de Picardie Jules Verne, UFR de Médecine, 3 Rue des Louvels, 80036 Amiens, France
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Kurzik-Dumke U, Hörner M, Nicotra MR, Koslowski M, Natali PG. In vivo evidence of htid suppressive activity on ErbB-2 in breast cancers over expressing the receptor. J Transl Med 2010; 8:58. [PMID: 20565727 PMCID: PMC2909173 DOI: 10.1186/1479-5876-8-58] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 06/17/2010] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Htid encoded proteins are physiological partners of a wide spectrum of molecules relevant to neoplastic transformation. One of the molecular ligands of the cytosolic hTid-L and hTid-I forms is the ErbB-2 receptor variably over expressed in diverse solid tumors. Altered ErbB-2 signalling is associated with an unfavourable prognosis in about 30% of human breast malignancies. METHODS We evaluated htid and HER-2 expression by quantitative real time PCR in tumors of different TNMG status and by immunohistochemistry in a cohort of breast tumors of the Luminal A, B, HER-2 and triple negative subtype. RESULTS The RT-PCR analysis revealed that aberrant expression of all three htid forms correlates with malignant transformation. Furthermore, elevated hTid-L expression can be associated with less aggressive tumors. The immunohistochemical testing revealed that tumors of the luminal A subtype are characterized by a high level of htid (81%). In contrast htid expression is significantly lower in tumors of the Luminal B (20%) and HER-2 (18%) subtype over expressing the receptor and in the triple negative (40%) more aggressive malignancies. A statistically significant inverse correlation between htid and ErbB-2 expression was found in human breast (p < 0,0001) and non-mammary tumors (p < 0,007), and in transgenic mice carrying the rat HER-2/neu oncogene. CONCLUSIONS Our findings provide in vivo evidence that htid is a tissue independent and evolutionarily conserved suppressor of ErbB-2.
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Affiliation(s)
- Ursula Kurzik-Dumke
- Institute of Medical Microbiology and Hygiene, Comparative Tumor Biology Group, University Medical Center, Johannes Gutenberg University, Obere Zahlbacher Str. 63, 55131 Mainz, Germany
| | - Manuela Hörner
- Institute of Medical Microbiology and Hygiene, Comparative Tumor Biology Group, University Medical Center, Johannes Gutenberg University, Obere Zahlbacher Str. 63, 55131 Mainz, Germany
| | | | - Michael Koslowski
- Experimental and Translational Oncology III, University Medical Center, Johannes Gutenberg University, Obere Zahlbacher Str. 63, 55131 Mainz, Germany
| | - Pier G Natali
- Immunology Laboratory, "Regina Elena" National Cancer Institute, Via delle Messi d'Oro 156, 0158 Rome and CIMBO Laboratories, "G.d'Annunzio" University, Chieti, Italy
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Qian J, Perchiniak EM, Sun K, Groden J. The mitochondrial protein hTID-1 partners with the caspase-cleaved adenomatous polyposis cell tumor suppressor to facilitate apoptosis. Gastroenterology 2010; 138:1418-28. [PMID: 19900451 PMCID: PMC3547615 DOI: 10.1053/j.gastro.2009.10.044] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 10/23/2009] [Accepted: 10/29/2009] [Indexed: 01/21/2023]
Abstract
BACKGROUND & AIMS The adenomatous polyposis cell (APC) tumor suppressor is a multifunctional protein involved in cell migration, proliferation, differentiation, and apoptosis. Cleavage of APC and the subsequent release of an amino-terminal segment are necessary for a transcription-independent mechanism of APC-mediated apoptosis. The aim of the current study is to elucidate the mechanism by which the amino-terminus of APC contributes to the enhancement of apoptosis. METHODS Previous yeast 2-hybrid screens, using the armadillo repeat domain of APC as bait, identified hTID-1 as a potential binding partner. Coimmunoprecipitations, coimmunofluorescence, and binding assays confirm a direct interaction between caspase-cleaved APC and hTID-1 in vivo at the mitochondria. Overexpression and small interfering RNA (siRNA) knockdown studies were designed to determine the significance of this interaction. RESULTS These experiments have identified hTID-1 as a directly interacting protein partner of caspase-cleaved APC. hTID-1 is an apoptosis modulator: 2 of its known mitochondrial protein isoforms, 43-kilodaltons and 40-kilodaltons, have opposing effects in apoptosis. We demonstrate that the amino-terminal segment of APC interacts with both hTID-1 isoforms directly, although there is a stronger association with the apoptotic suppressor 40-kilodalton isoform in vitro. This interaction localizes to amino acids 202-512 of APC, a region including 2 of the 7 armadillo repeats. Overexpression of the 40-kilodalton hTID-1 isoform partially rescues cells from apoptosis mediated by APC 1-777, whereas siRNA knockdown of this hTID-1 isoform enhances apoptosis. CONCLUSIONS These data suggest that the amino-terminal segment of APC promotes cell sensitivity to apoptosis modulated through its binding to 40- and 43-kilodalton hTID-1 isoforms.
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Affiliation(s)
| | | | | | - Joanna Groden
- Corresponding author: Joanna Groden, Ph.D., Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, 460 W 12th Street, Columbus, OH 43210-2207, , Phone: 614-688-4301
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14
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Kurzik-Dumke U, Czaja J. Htid-1, the human homolog of the Drosophila melanogaster l(2)tid tumor suppressor, defines a novel physiological role of APC. Cell Signal 2007; 19:1973-85. [PMID: 17588722 DOI: 10.1016/j.cellsig.2007.05.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 04/17/2007] [Accepted: 05/18/2007] [Indexed: 12/21/2022]
Abstract
Htid-1, the human counterpart of the Drosophila tumor suppressor gene lethal(2)tumorous imaginal discs (l(2)tid) encodes three splice forms translated into three cytosolic - Tid50, Tid48 and Tid46 - and three mitochondrial - Tid43, Tid40 and Tid38 - proteins. Here we provide evidence for the association of the endogenous Tid50/Tid48 proteins with the adenomatous polyposis coli (APC) tumor suppressor in normal colon epithelium, colorectal cancer cells and mouse NIH3T3 fibroblasts. Using the Glutathione S-transferase binding assay we show that the N-terminal region including the Armadillo domain (ARM) of APC is sufficient to bind the Tid molecules. Using immunoprecipitation and confocal microscopy we show that the two molecular partners complex at defined areas of the cells with further proteins such as Hsp70, Hsc70, Actin, Dvl and Axin. Our data implicate that the formation of the complex is not associated with APC's involvement in beta-Catenin degradation. Furthermore, though it is linked to Actin it is neither associated with regulation of Actin cytoskeleton due to APC's binding to Asef nor to Tid's binding to Ras-GAP. We suggest that the novel complex acts in maintaining APC's availability for its distinct roles in the Wnt signaling important for the cell to take the right decision, either to switch the cascade OFF or ON, thus, to regulate the onset of proliferation of the cells.
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Affiliation(s)
- Ursula Kurzik-Dumke
- Institute of Medical Microbiology and Hygiene, Laboratory for Comparative Tumor Biology, Johannes Gutenberg University, Obere Zahlbacher Strasse 63, 55131 Mainz, Germany.
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15
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Torregroza I, Evans T. Tid1 is a Smad-binding protein that can modulate Smad7 activity in developing embryos. Biochem J 2006; 393:311-20. [PMID: 16156721 PMCID: PMC1383690 DOI: 10.1042/bj20050785] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In a search for binding partners to Smad8, we identified the chicken homologue of the mammalian Tid1 protein (cTid1), which is a regulator of apoptosis related to the Drosophila tumour suppressor Tid56. The cTid1 coding sequence is highly conserved with mammalian Tid1, including the DnaJ domain that interacts with Hsp70 (heat-shock protein 70). The cTid1 gene is widely expressed with transcripts enriched in the developing blood islands of the embryonic-yolk sac. We show that cTid1 can bind to other members of the Smad family and that highest binding activity occurs with the negative regulatory Smad7, through the conserved MH2 domain. This interaction can have functional relevance in vivo, since co-expression of Tid1 blocks the dorsalizing and BMP (bone morphogenetic protein)-dependent regulatory activity of Smad7 in developing Xenopus embryos. The finding that these proteins can interact suggests the potential for linking two important cell survival/apoptosis pathways.
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Affiliation(s)
- Ingrid Torregroza
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, U.S.A
| | - Todd Evans
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, U.S.A
- To whom correspondence should be addressed (email )
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16
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Liu HY, MacDonald JIS, Hryciw T, Li C, Meakin SO. Human Tumorous Imaginal Disc 1 (TID1) Associates with Trk Receptor Tyrosine Kinases and Regulates Neurite Outgrowth in nnr5-TrkA Cells. J Biol Chem 2005; 280:19461-71. [PMID: 15753086 DOI: 10.1074/jbc.m500313200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human tumorous imaginal disc 1 (TID1) proteins including TID1(L) and TID1(S), members of the DnaJ domain protein family, are involved in multiple intracellular signaling pathways such as apoptosis induction, cell proliferation, and survival. Here we report that TID1 associates with the Trk receptor tyrosine kinases and regulates nerve growth factor (NGF)-induced neurite outgrowth in PC12-derived nnr5 cells. Binding assays and transfection studies showed that the carboxyl-terminal end of TID1 (residues 224-429) bound to Trk at the activation loop (Tyr(P)(683)-Tyr(684)(P)(684) in rat TrkA) and that TID1 was tyrosine phosphorylated by Trk both in yeast and in transfected cells. Moreover endogenous TID1 was also tyrosine phosphorylated by and co-immunoprecipitated with Trk in neurotrophin-stimulated primary rat hippocampal neurons. Overexpression studies showed that both TID1(L) and TID1(S) significantly facilitated NGF-induced neurite outgrowth in TrkA-expressing nnr5 cells possibly through a mechanism involving increased activation of mitogen-activated protein kinase. Consistently knockdown of endogenous TID1, mediated with specific short hairpin RNA, significantly reduced NGF-induced neurite growth in nnr5-TrkA cells. These data provide the first evidence that TID1 is a novel intracellular adaptor that interacts with the Trk receptor tyrosine kinases in an activity-dependent manner to facilitate Trk-dependent intracellular signaling.
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Affiliation(s)
- Hui-Yu Liu
- Cell Biology Group, Robarts Research Institute, London, Ontario, Canada
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17
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Kittler R, Pelletier L, Ma C, Poser I, Fischer S, Hyman AA, Buchholz F. RNA interference rescue by bacterial artificial chromosome transgenesis in mammalian tissue culture cells. Proc Natl Acad Sci U S A 2005; 102:2396-401. [PMID: 15695330 PMCID: PMC548992 DOI: 10.1073/pnas.0409861102] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
RNA interference (RNAi) is a widely used method for analysis of gene function in tissue culture cells. However, to date there has been no reliable method for testing the specificity of any particular RNAi experiment. The ideal experiment is to rescue the phenotype by expression of the target gene in a form refractory to RNAi. The transgene should be expressed at physiological levels and with its different splice variants. Here, we demonstrate that expression of murine bacterial artificial chromosomes in human cells provides a reliable method to create RNAi-resistant transgenes. This strategy should be applicable to all eukaryotes and should therefore be a standard technology for confirming the specificity of RNAi. We show that this technique can be extended to allow the creation of tagged transgenes, expressed at physiological levels, for the further study of gene function.
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Affiliation(s)
- Ralf Kittler
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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18
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Trentin GA, He Y, Wu DC, Tang D, Rozakis-Adcock M. Identification of a hTid-1 mutation which sensitizes gliomas to apoptosis. FEBS Lett 2005; 578:323-30. [PMID: 15589840 DOI: 10.1016/j.febslet.2004.11.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2004] [Revised: 11/05/2004] [Accepted: 11/09/2004] [Indexed: 01/13/2023]
Abstract
Human Tid-1 (hTid-1) is a DnaJ chaperone protein with homology to the Drosophila tumor suppressor Tid56. We report the first case of a tumor-associated mutation at the human TID1 locus, which was identified in the SF767 glioma cell line giving rise to aberrantly high levels of a hTid-1(L) mutant variant. In this study, we set out to determine whether this change in hTid-1 status influences the response of glioma cells to adenoviral (Ad)-mediated delivery of the two major isoforms of TID1, hTid-1(L) and hTid-1(S). Ad-hTid-1(S) induced apoptosis in hTid-1 mutant SF767 cells, while causing growth arrest in wild-type hTid-1-expressing U373 and U87 cells. By contrast, Ad-hTid-1(L) infection had no apparent effect on glioma cell growth. The apoptosis induced by hTid-1(S) was accompanied by mitochondrial cytochrome C release and caspase activation and blocked by stable overexpression of Bcl-X(L). Our findings suggest that the status of hTid-1 in gliomas may contribute to their susceptibility to cell death triggers.
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Affiliation(s)
- G A Trentin
- Faculty of Health Sciences, McMaster University, Hamilton, Ont., Canada L8N 3Z5
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19
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Tarunina M, Alger L, Chu G, Munger K, Gudkov A, Jat PS. Functional genetic screen for genes involved in senescence: role of Tid1, a homologue of the Drosophila tumor suppressor l(2)tid, in senescence and cell survival. Mol Cell Biol 2004; 24:10792-801. [PMID: 15572682 PMCID: PMC533960 DOI: 10.1128/mcb.24.24.10792-10801.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We performed a genetic suppressor element screen to identify genes whose inhibition bypasses cellular senescence. A normalized library of fragmented cDNAs was used to select for elements that promote immortalization of rat embryo fibroblasts. Fragments isolated by the screen include those with homology to genes that function in intracellular signaling, cellular adhesion and contact, protein degradation, and apoptosis. They include mouse Tid1, a homologue of the Drosophila tumor suppressor gene l(2)tid, recently implicated in modulation of apoptosis as well as gamma interferon and NF-kappaB signaling. We show that GSE-Tid1 enhances immortalization by human papillomavirus E7 and simian virus 40 T antigen and cooperates with activated ras for transformation. Expression of Tid1 is upregulated upon cellular senescence in rat and mouse embryo fibroblasts and premature senescence of REF52 cells triggered by activated ras. In accordance with this, spontaneous immortalization of rat embryo fibroblasts is suppressed upon ectopic expression of Tid1. Modulation of endogenous Tid1 activity by GSE-Tid1 or Tid1-specific RNA interference alleviates the suppression of tumor necrosis factor alpha-induced NF-kappaB activity by Tid1. We also show that NF-kappaB sequence-specific binding is strongly downregulated upon senescence in rat embryo fibroblasts. We therefore propose that Tid1 contributes to senescence by acting as a repressor of NF-kappaB signaling.
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Affiliation(s)
- Marina Tarunina
- Ludwig Institute for Cancer Research, 91 Riding House St., London W1W 7BS, United Kingdom
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20
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Edwards KM, Münger K. Depletion of physiological levels of the human TID1 protein renders cancer cell lines resistant to apoptosis mediated by multiple exogenous stimuli. Oncogene 2004; 23:8419-31. [PMID: 15156195 DOI: 10.1038/sj.onc.1207732] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The human homologue of the Drosophila tumor suppressor lethal (2) tumorous imaginal discs (l(2)tid) gene, hTID1, encodes two proteins derived from alternate mRNA splicing. The splice variants TidL and TidS were previously reported from protein overexpression and dominant-negative mutant protein studies to exhibit opposing biological activities in response to exogenous cytotoxic stimuli. TidL was found to promote apoptosis while TidS suppressed it. To elucidate the physiological function of hTID1, we depleted hTID1 proteins using the technique of RNA interference (RNAi). Here, we show that cells essentially lacking expression of hTID1 proteins are protected from cell death in response to multiple stimuli, including cisplatin, tumor necrosis factor alpha/cycloheximide and mitomycin C. We also generated stable cell populations depleted of hTID1 proteins by RNAi using DNA vectors. In addition to apoptosis resistance, stable hTID1 knockdown cells exhibited an enhanced ability for anchorage-independent growth, as measured by an increase in soft-agar colony formation. These results suggest that hTID1 functions as an important cell death regulator and raise the interesting possibility that hTID1 could exert tumor suppressor activity.
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Affiliation(s)
- Kirsten M Edwards
- Department of Pathology, Harvard Medical School, NRB 0958, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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21
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Canamasas I, Debes A, Natali PG, Kurzik-Dumke U. Understanding human cancer using Drosophila: Tid47, a cytosolic product of the DnaJ-like tumor suppressor gene l2Tid, is a novel molecular partner of patched related to skin cancer. J Biol Chem 2003; 278:30952-60. [PMID: 12783860 DOI: 10.1074/jbc.m304225200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Recessive mutations of the Drosophila gene lethal(2)-tumorous imaginal discs (l(2)tid) cause neoplastic growth of the anlagen of the adult organs, the imaginal discs. Here we report that the three proteins encoded by this evolutionarily conserved gene, Tid50, Tid47, and Tid40, identified as members of the DnaJ cochaperone family, are destined for different cellular compartments, build complexes with many proteins in a developmental stage-specific manner, and are likely to be involved in different cellular processes. We show that the cytosolic Tid47 molecule is a novel component of the Hedgehog (Hh)-Patched (Ptc) signaling regulating cell/tissue polarity and spatial patterning during development and is associated with human tumors such as basal cell carcinoma (BCC) and medulloblastoma. We provide functional evidence for its direct in vivo interaction with the Hh-bound Ptc receptor during signal transmission. Because loss of l(2)tid causes neoplastic transformation of Hh-responsive cells, we suggest that Tid47 may at least act as a guardian of the Hh signaling gradient by regulating Ptc homeostasis in the tissue. Finally, we show that the expression of htid-1, the human counterpart of l(2)tid, is altered in human BCCs. We demonstrate that in BCCs loss of htid expression correlates with loss of differentiation capacity of the neoplastic cells similar to that found in the Drosophila tumor model.
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Affiliation(s)
- Itziar Canamasas
- Institute of Genetics, Laboratory for Comparative Tumor Biology, Johannes Gutenberg University, 55131 Mainz, Germany
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22
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Syken J, Macian F, Agarwal S, Rao A, Münger K. TID1, a mammalian homologue of the drosophila tumor suppressor lethal(2) tumorous imaginal discs, regulates activation-induced cell death in Th2 cells. Oncogene 2003; 22:4636-41. [PMID: 12879007 DOI: 10.1038/sj.onc.1206569] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We previously described two human DnaJ proteins, hTid-1L and hTid-1S, which are derived from alternative splicing of the TID1 gene, the human homologue of the Drosophila tumor suppressor lethal(2) tumorous imaginal discs, and showed that hTid-1L promoted while hTid-1S antagonized apoptosis. There are two subsets of helper T cells, Th1 and Th2, of which Th2 cells are significantly less prone to apoptosis induced by stimulation through the T-cell receptor. This apoptotic process is known as activation-induced cell death (AICD). The molecular basis for the differential susceptibility of Th1 and Th2 cells to AICD is not known. Here we show that the antiapoptotic variant, Tid-1S, is selectively induced in murine Th2 cells following activation. Expression of a dominant-negative mutant of hTid-1S in a Th2 cell line strikingly enhanced activation of caspase 3 in response to CD3 stimulation, and caused the cells to become sensitive to AICD. Hence, the accumulation of Tid-1S in Th2 cells following activation represents a novel mechanism that may contribute to the induction of apoptosis resistance during the activation of Th2 cells.
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Affiliation(s)
- Josh Syken
- Department of Pathology, Harvard Medical School, 200 Longwood Avenue, D2/544A, Boston, MA 02115-5701, USA
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23
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Abstract
Ikaros is an essential transcription factor for normal lymphocyte development. Because of its interaction with a number of closely related factors, Ikaros is required for correct regulation of differentiation and cell proliferation in T- and B-cell lineages. Interestingly, Ikaros appears to function both as a transcriptional repressor and as an activator through its ability to bind a large number of nuclear factors, including components of both histone deacetylase and ATP-dependent chromatin remodelling complexes. In addition, nuclear localisation is important for Ikaros function--unlike most transcription factors, Ikaros is localised to discrete nuclear foci in lymphoid cells, suggesting it employs novel mechanisms to regulate transcription.
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Affiliation(s)
- Belinda J Westman
- School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW 2006, Australia.
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24
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Sasaki S, Nakamura T, Arakawa H, Mori M, Watanabe T, Nagawa H, Croce CM. Isolation and characterization of a novel gene, hRFI, preferentially expressed in esophageal cancer. Oncogene 2002; 21:5024-30. [PMID: 12118383 DOI: 10.1038/sj.onc.1205627] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2001] [Revised: 04/04/2002] [Accepted: 04/26/2002] [Indexed: 01/08/2023]
Abstract
hTID1, a human homologue of Drosophila tumor suppressor, I(2)tid regulates the release of cytochrome c from mitochondria and subsequent alteration of caspase-3 activity on apoptosis induced by exogenous stimuli, such as tumor necrosis factor-alpha and mitomycin C. To search for an interacting molecule with hTid1, we applied two-hybrid yeast screening and isolated a novel gene, which encodes a 46 kDa protein of 373 residues. Within the deduced amino acid sequence, a region showing homology to the Ring Finger domain of X-linked inhibitor of apoptosis protein was identified and the gene was designated as hRFI, standing for human Ring Finger homologous to IAP type. A 2.0 kb hRFI transcript was ubiquitously expressed in all human tissues as well as several cancer cell lines examined. Northern blot analysis showed that in 70% (14 out of 20) of esophageal cancer patients, expression of hRFI in cancerous regions was two or more times higher than in the corresponding normal tissues. HeLa cells transfected with hRFI construct exhibited a tendency to resist TNF-alpha induced apoptosis, suggesting an anti-apoptotic function of the hRFI product. Finally, hRFI protein was shown to be cleaved within the DEDD sequence spanning residues 230-233 by caspase-3 during the apoptotic induction.
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Affiliation(s)
- Shin Sasaki
- Department of Surgical Oncology, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
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