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Mohajeri A, Vaseghi-Shanjani M, Rosenfeld JA, Yang GX, Lu H, Sharma M, Lin S, Salman A, Waqas M, Sababi Azamian M, Worley KC, Del Bel KL, Kozak FK, Rahmanian R, Biggs CM, Hildebrand KJ, Lalani SR, Nicholas SK, Scott DA, Mostafavi S, van Karnebeek C, Henkelman E, Halparin J, Yang CL, Armstrong L, Turvey SE, Lehman A. Dominant negative variants in IKZF2 cause ICHAD syndrome, a new disorder characterised by immunodysregulation, craniofacial anomalies, hearing impairment, athelia and developmental delay. J Med Genet 2023; 60:1092-1104. [PMID: 37316189 PMCID: PMC11206234 DOI: 10.1136/jmg-2022-109127] [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: 12/27/2022] [Accepted: 05/29/2023] [Indexed: 06/16/2023]
Abstract
BACKGROUND Helios (encoded by IKZF2), a member of the Ikaros family of transcription factors, is a zinc finger protein involved in embryogenesis and immune function. Although predominantly recognised for its role in the development and function of T lymphocytes, particularly the CD4+ regulatory T cells (Tregs), the expression and function of Helios extends beyond the immune system. During embryogenesis, Helios is expressed in a wide range of tissues, making genetic variants that disrupt the function of Helios strong candidates for causing widespread immune-related and developmental abnormalities in humans. METHODS We performed detailed phenotypic, genomic and functional investigations on two unrelated individuals with a phenotype of immune dysregulation combined with syndromic features including craniofacial differences, sensorineural hearing loss and congenital abnormalities. RESULTS Genome sequencing revealed de novo heterozygous variants that alter the critical DNA-binding zinc fingers (ZFs) of Helios. Proband 1 had a tandem duplication of ZFs 2 and 3 in the DNA-binding domain of Helios (p.Gly136_Ser191dup) and Proband 2 had a missense variant impacting one of the key residues for specific base recognition and DNA interaction in ZF2 of Helios (p.Gly153Arg). Functional studies confirmed that both these variant proteins are expressed and that they interfere with the ability of the wild-type Helios protein to perform its canonical function-repressing IL2 transcription activity-in a dominant negative manner. CONCLUSION This study is the first to describe dominant negative IKZF2 variants. These variants cause a novel genetic syndrome characterised by immunodysregulation, craniofacial anomalies, hearing impairment, athelia and developmental delay.
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Affiliation(s)
- Arezoo Mohajeri
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Maryam Vaseghi-Shanjani
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Gui Xiang Yang
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Henry Lu
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Mehul Sharma
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Susan Lin
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Areesha Salman
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Meriam Waqas
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Mahshid Sababi Azamian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Kim C Worley
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Kate L Del Bel
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Frederick K Kozak
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Ronak Rahmanian
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Catherine M Biggs
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Kyla J Hildebrand
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Seema R Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Sarah K Nicholas
- Department of Pediatrics, Texas Children's Hospital, Houston, Texas, USA
| | - Daryl A Scott
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Sara Mostafavi
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Clara van Karnebeek
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Erika Henkelman
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Jessica Halparin
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Connie L Yang
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Linlea Armstrong
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
- Provincial Medical Genetics Program, BC Children's & Women's Hosp, Vancouver, British Columbia, Canada
| | - Stuart E Turvey
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Anna Lehman
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
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2
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Belluti S, Rigillo G, Imbriano C. Transcription Factors in Cancer: When Alternative Splicing Determines Opposite Cell Fates. Cells 2020; 9:E760. [PMID: 32244895 PMCID: PMC7140685 DOI: 10.3390/cells9030760] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/05/2020] [Accepted: 03/17/2020] [Indexed: 02/08/2023] Open
Abstract
Alternative splicing (AS) is a finely regulated mechanism for transcriptome and proteome diversification in eukaryotic cells. Correct balance between AS isoforms takes part in molecular mechanisms that properly define spatiotemporal and tissue specific transcriptional programs in physiological conditions. However, several diseases are associated to or even caused by AS alterations. In particular, multiple AS changes occur in cancer cells and sustain the oncogenic transcriptional program. Transcription factors (TFs) represent a key class of proteins that control gene expression by direct binding to DNA regulatory elements. AS events can generate cancer-associated TF isoforms with altered activity, leading to sustained proliferative signaling, differentiation block and apoptosis resistance, all well-known hallmarks of cancer. In this review, we focus on how AS can produce TFs isoforms with opposite transcriptional activities or antagonistic functions that severely impact on cancer biology. This summary points the attention to the relevance of the analysis of TFs splice variants in cancer, which can allow patients stratification despite the presence of interindividual genetic heterogeneity. Recurrent TFs variants that give advantage to specific cancer types not only open the opportunity to use AS transcripts as clinical biomarkers but also guide the development of new anti-cancer strategies in personalized medicine.
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Affiliation(s)
| | | | - Carol Imbriano
- Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 213/D, 41125 Modena, Italy; (S.B.); (G.R.)
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3
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Thornton AM, Shevach EM. Helios: still behind the clouds. Immunology 2019; 158:161-170. [PMID: 31517385 DOI: 10.1111/imm.13115] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/27/2019] [Accepted: 09/04/2019] [Indexed: 01/08/2023] Open
Abstract
Regulatory T (Treg) cells are a subset of CD4+ T cells that are critical for the maintenance of self-tolerance. The forkhead box transcription factor Foxp3 is a master regulator for the Treg phenotype and function and its expression is essential in Treg cells, as the loss of Foxp3 results in lethal autoimmunity. Two major subsets of Treg cells have been described in vivo; thymus-derived Treg (tTreg) cells that develop in the thymus and peripherally induced Treg (pTreg) cells that are derived from conventional CD4+ Foxp3- T cells and are converted in peripheral tissues to cells that express Foxp3 and acquire suppressive ability. The transcription factor Helios, a member of the Ikaros transcription factor family, is expressed in 60-70% of Treg cells in both mouse and man, and is believed to be a marker of tTreg cells. In this review, we discuss the role and function of Helios in Treg cells, the controversy surrounding the use of Helios as a marker of tTreg cells, and how Helios controls specific aspects of the Treg cell program.
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Affiliation(s)
- Angela M Thornton
- Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Ethan M Shevach
- Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
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4
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Park SM, Cho H, Thornton AM, Barlowe TS, Chou T, Chhangawala S, Fairchild L, Taggart J, Chow A, Schurer A, Gruet A, Witkin MD, Kim JH, Shevach EM, Krivtsov A, Armstrong SA, Leslie C, Kharas MG. IKZF2 Drives Leukemia Stem Cell Self-Renewal and Inhibits Myeloid Differentiation. Cell Stem Cell 2019; 24:153-165.e7. [PMID: 30472158 PMCID: PMC6602096 DOI: 10.1016/j.stem.2018.10.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 08/06/2018] [Accepted: 10/10/2018] [Indexed: 01/08/2023]
Abstract
Leukemias exhibit a dysregulated developmental program mediated through both genetic and epigenetic mechanisms. Although IKZF2 is expressed in hematopoietic stem cells (HSCs), we found that it is dispensable for mouse and human HSC function. In contrast to its role as a tumor suppressor in hypodiploid B-acute lymphoblastic leukemia, we found that IKZF2 is required for myeloid leukemia. IKZF2 is highly expressed in leukemic stem cells (LSCs), and its deficiency results in defective LSC function. IKZF2 depletion in acute myeloid leukemia (AML) cells reduced colony formation, increased differentiation and apoptosis, and delayed leukemogenesis. Gene expression, chromatin accessibility, and direct IKZF2 binding in MLL-AF9 LSCs demonstrate that IKZF2 regulates a HOXA9 self-renewal gene expression program and inhibits a C/EBP-driven differentiation program. Ectopic HOXA9 expression and CEBPE depletion rescued the effects of IKZF2 depletion. Thus, our study shows that IKZF2 regulates the AML LSC program and provides a rationale to therapeutically target IKZF2 in myeloid leukemia.
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MESH Headings
- Animals
- Cell Differentiation
- Cell Self Renewal
- Chromatin/genetics
- Chromatin/metabolism
- DNA-Binding Proteins/physiology
- Female
- Gene Expression Regulation, Leukemic
- Hematopoiesis
- Leukemia, Experimental/genetics
- Leukemia, Experimental/metabolism
- Leukemia, Experimental/pathology
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neoplastic Stem Cells/metabolism
- Neoplastic Stem Cells/pathology
- Transcription Factors/physiology
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Affiliation(s)
- Sun-Mi Park
- Molecular Pharmacology Program and Center for Cell Engineering, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Hyunwoo Cho
- Computational Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Angela M Thornton
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, USA
| | - Trevor S Barlowe
- Molecular Pharmacology Program and Center for Cell Engineering, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Timothy Chou
- Molecular Pharmacology Program and Center for Cell Engineering, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sagar Chhangawala
- Computational Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Lauren Fairchild
- Computational Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - James Taggart
- Molecular Pharmacology Program and Center for Cell Engineering, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Arthur Chow
- Molecular Pharmacology Program and Center for Cell Engineering, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Alexandria Schurer
- Molecular Pharmacology Program and Center for Cell Engineering, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Antoine Gruet
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Matthew D Witkin
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jun Hyun Kim
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Ethan M Shevach
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, USA
| | - Andrei Krivtsov
- Department of Pediatric Oncology, Dana Farber Cancer Institute, Boston, MA, USA
| | - Scott A Armstrong
- Department of Pediatric Oncology, Dana Farber Cancer Institute, Boston, MA, USA
| | - Christina Leslie
- Computational Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Michael G Kharas
- Molecular Pharmacology Program and Center for Cell Engineering, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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5
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Li Y, Liu Y, Liu C, Liu F, Dou D, Zheng W, Liu W, Liu F. Role of a non-canonical splice variant of the Helios gene in the differentiation of acute lymphoblastic leukemic T cells. Oncol Lett 2018; 15:6957-6966. [PMID: 29725423 DOI: 10.3892/ol.2018.8214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 02/21/2018] [Indexed: 11/05/2022] Open
Abstract
T-cell acute lymphoblastic leukemia is a hematopoietic malignant disease, which arises from a genetic defect in the T-cell maturation signaling pathway. As a result, it is necessary to identify the molecules that impact T-cell development and control lymphoid-lineage malignancy. The present study utilized Jurkat T lymphoblastic cells as a well-established approach for the investigation into the function of the non-canonical alternative splice variant of Helios for the in vitro study of T-cell differentiation and leukemogenesis. In the present study, the Jurkat T-cell lines with stable overexpression of the wild-type (Helios-1) or the non-canonical short isoform (Helios-Δ326-1431), were established. RNA microarray, reverse transcription-quantitative polymerase chain reaction and flow cytometry were used to assess changes in the gene expression profiles and to monitor the cell surface markers during T-cell differentiation. Multiple genes associated with T-cell differentiation and leukemogenesis were identified as being either activated or suppressed. In addition, the results indicated that the stable overexpression of the Helios isoforms stimulated the differentiation pathway of the T-lineage lymphoblastic cells. Therefore, these results suggest that full-length Helios-1 has a tumor suppressor-like and immunomodulatory role, in contrast to the oncogenic function of the non-canonical short isoform Helios-Δ326-1431.
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Affiliation(s)
- Yinghui Li
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, P.R. China
| | - Yanhua Liu
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, P.R. China
| | - Can Liu
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, P.R. China
| | - Fengyong Liu
- Department of Pathophysiology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Daolei Dou
- Department of Experimental Facility, State Key Laboratory of Medical Chemical Biology, Tianjin 300071, P.R. China
| | - Wenjie Zheng
- Technical Center for Safety of Industrial Products, Tianjin Entry-Exit Inspection and Quarantine Bureau, Tianjin 300308, P.R. China
| | - Wei Liu
- Technical Center for Safety of Industrial Products, Tianjin Entry-Exit Inspection and Quarantine Bureau, Tianjin 300308, P.R. China
| | - Feifei Liu
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, P.R. China
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6
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Zhao S, Liu W, Li Y, Liu P, Li S, Dou D, Wang Y, Yang R, Xiang R, Liu F. Alternative Splice Variants Modulates Dominant-Negative Function of Helios in T-Cell Leukemia. PLoS One 2016; 11:e0163328. [PMID: 27681508 PMCID: PMC5040427 DOI: 10.1371/journal.pone.0163328] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/06/2016] [Indexed: 12/21/2022] Open
Abstract
The molecular defects which lead to multistep incidences of human T-cell leukemia have yet to be identified. The DNA-binding protein Helios (known as IKZF2), a member of the Ikaros family of Krüppel-like zinc-finger proteins, functions pivotally in T-cell differentiation and activation. In this study, we identify three novel short Helios splice variants which are T-cell leukemic specific, and demonstrate their dominant-negative function. We then test the cellular localization of distinct Helios isoforms, as well as their capability to form heterodimer with Ikaros, and the association with complexes comprising histone deacetylase (HDAC). In addition, the ectopic expression of T-cell leukemic Helios isoforms interferes with T-cell proliferation and apoptosis. The gene expression profiling and pathway analysis indicated the enrichment of signaling pathways essential for gene expression, translation, cell cycle checkpoint, and response to DNA damage stimulus. These data indicate the molecular function of Helios to be involved in the leukemogenesis and phenotype of T-cell leukemia, and also reveal Helios deregulation as a novel marker for T-cell leukemia.
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Affiliation(s)
- Shaorong Zhao
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Wei Liu
- Tianjin Entry-Exit Inspection and Quarantine Bureau, Tianjin 300308, China
| | - Yinghui Li
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Pengjiang Liu
- Department of Hematology, First-Central Hospital, Tianjin 300060, China
| | - Shufang Li
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Daolei Dou
- State Key Laboratory of Medical Chemical Biology, Tianjin 300070, China
| | - Yue Wang
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Rongcun Yang
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Rong Xiang
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
- Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Tianjin 300071, China
- * E-mail: (FL); (RX)
| | - Feifei Liu
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
- * E-mail: (FL); (RX)
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7
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Wada T, Asahi T, Sawamura N. Nuclear cereblon modulates transcriptional activity of Ikaros and regulates its downstream target, enkephalin, in human neuroblastoma cells. Biochem Biophys Res Commun 2016; 477:388-94. [DOI: 10.1016/j.bbrc.2016.06.091] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 06/17/2016] [Indexed: 11/16/2022]
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8
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Affiliation(s)
- Claire Chougnet
- Division of Immunobiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center and the University of Cincinnati, Cincinnati, OH 45229, USA
| | - David Hildeman
- Division of Immunobiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center and the University of Cincinnati, Cincinnati, OH 45229, USA
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9
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Ross EM, Bourges D, Hogan TV, Gleeson PA, van Driel IR. Helios defines T cells being driven to tolerance in the periphery and thymus. Eur J Immunol 2014; 44:2048-58. [PMID: 24740292 DOI: 10.1002/eji.201343999] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 03/04/2014] [Accepted: 04/11/2014] [Indexed: 01/04/2023]
Abstract
The expression of the Ikaros transcription factor family member, Helios, has been shown to be associated with T-cell tolerance in both the thymus and the periphery. To better understand the importance of Helios in tolerance pathways, we have examined the expression of Helios in TCR-transgenic T cells specific for the gastric H(+) /K(+) ATPase, the autoantigen target in autoimmune gastritis. Analysis of H(+) /K(+) ATPase-specific T cells in mice with different patterns of H(+) /K(+) ATPase expression revealed that, in addition to the expression of Helios in CD4(+) Foxp3(+) regulatory T (Treg) cells, Helios is expressed by a large proportion of CD4(+) Foxp3(-) T cells in both the thymus and the paragastric lymph node (PgLN), which drains the stomach. In the thymus, Helios was expressed by H(+) /K(+) ATPase-specific thymocytes that were undergoing negative selection. In the periphery, Helios was expressed in H(+) /K(+) ATPase-specific CD4(+) T cells following H(+) /K(+) ATPase presentation and was more highly expressed when T-cell activation occurred in the absence of inflammation. Analysis of purified H(+) /K(+) ATPase-specific CD4(+) Foxp3(-) Helios(+) T cells demonstrated that they were functionally anergic. These results demonstrate that Helios is expressed by thymic and peripheral T cells that are being driven to tolerance in response to a genuine autoantigen.
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Affiliation(s)
- Ellen M Ross
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Australia
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10
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Asanuma S, Yamagishi M, Kawanami K, Nakano K, Sato-Otsubo A, Muto S, Sanada M, Yamochi T, Kobayashi S, Utsunomiya A, Iwanaga M, Yamaguchi K, Uchimaru K, Ogawa S, Watanabe T. Adult T-cell leukemia cells are characterized by abnormalities of Helios expression that promote T cell growth. Cancer Sci 2013; 104:1097-106. [PMID: 23600753 DOI: 10.1111/cas.12181] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 04/11/2013] [Accepted: 04/15/2013] [Indexed: 12/14/2022] Open
Abstract
Molecular abnormalities involved in the multistep leukemogenesis of adult T-cell leukemia (ATL) remain to be clarified. Based on our integrated database, we focused on the expression patterns and levels of Ikaros family genes, Ikaros, Helios, and Aiolos, in ATL patients and HTLV-1 carriers. The results revealed profound deregulation of Helios expression, a pivotal regulator in the control of T-cell differentiation and activation. The majority of ATL samples (32/37 cases) showed abnormal splicing of Helios expression, and four cases did not express Helios. In addition, novel genomic loss in Helios locus was observed in 17/168 cases. We identified four ATL-specific short Helios isoforms and revealed their dominant-negative function. Ectopic expression of ATL-type Helios isoform as well as knockdown of normal Helios or Ikaros promoted T-cell growth. Global mRNA profiling and pathway analysis showed activation of several signaling pathways important for lymphocyte proliferation and survival. These data provide new insights into the molecular involvement of Helios function in the leukemogenesis and phenotype of ATL cells, indicating that Helios deregulation is one of the novel molecular hallmarks of ATL.
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Affiliation(s)
- Satomi Asanuma
- Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, Japan
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11
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HELIOS-BCL11B fusion gene involvement in a t(2;14)(q34;q32) in an adult T-cell leukemia patient. Cancer Genet 2012; 205:356-64. [PMID: 22867996 DOI: 10.1016/j.cancergen.2012.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 04/10/2012] [Accepted: 04/14/2012] [Indexed: 11/21/2022]
Abstract
To provide fundamental insights into the leukemogenesis of adult T-cell leukemia/lymphoma (ATLL), we performed a molecular analysis of the chromosomal abnormalities in one ATLL case with a novel reciprocal translocation: t(2;14)(q34;q32). Using fluorescence in situ hybridization with cosmid probes derived from the 14q32 region, we characterized the rearranged 14q32 allele. Molecular cloning of the breakpoint revealed that the reciprocal translocation fused the 5' proximal region of the B-cell lymphoma 11B (BCL11B) gene segment (on 14q32) to the third intron of the HELIOS gene (on 2q34). Reverse transcription-polymerase chain reaction analysis of the leukemia cells revealed that a substantial level of the HELIOS-BCL11B fusion mRNA was expressed relative to the level of wild-type (WT)-BCL11B derived from the intact allele. In contrast, an aberrant HELIOS isoform was detected at a low level of expression compared to the expression of normal HELIOS isoforms. Functional analysis of the HELIOS-BCL11B fusion protein revealed reduced transcriptional suppression activity compared to that of the WT-BCL11B due to the loss of the N-terminal friend of GATA-repression motif, which functions as a metastasis-associated protein 2 binding site. We also found abnormal subnuclear localization of the ectopically expressed fusion protein compared to the localization of WT-BCL11B to subnuclear speckles in HEK293T cells. Our results suggest that dysfunction of the BCL11B gene plays an important role in the development of ATLL.
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12
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John LB, Ward AC. The Ikaros gene family: transcriptional regulators of hematopoiesis and immunity. Mol Immunol 2011; 48:1272-8. [PMID: 21477865 DOI: 10.1016/j.molimm.2011.03.006] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/07/2011] [Accepted: 03/08/2011] [Indexed: 01/10/2023]
Abstract
The Ikaros family of proteins - comprising Ikaros, Aiolos, Helios, Eos and Pegasus - are zinc finger transcription factors. These proteins participate in a complex network of interactions with gene regulatory elements, other family members and a raft of other transcriptional regulators to control gene expression including via chromatin remodelling. In this way, Ikaros family members regulate important cell-fate decisions during hematopoiesis, particularly in the development of the adaptive immune system. Mutation of several family members results in hematological malignancies,especially those of a lymphoid nature. This review describes the key roles of Ikaros proteins in development and disease, their mechanisms of action and gene targets, as well as explaining their evolutionary origins and role in the emergence of adaptive immunity.
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Affiliation(s)
- Liza B John
- School of Medicine, Deakin University, Waurn Ponds, Victoria 3217, Australia
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13
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Cai Q, Dierich A, Oulad-Abdelghani M, Chan S, Kastner P. Helios deficiency has minimal impact on T cell development and function. THE JOURNAL OF IMMUNOLOGY 2009; 183:2303-11. [PMID: 19620299 DOI: 10.4049/jimmunol.0901407] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Helios is a member of the Ikaros family of zinc finger transcription factors. It is expressed mainly in T cells, where it associates with Ikaros-containing complexes and has been proposed to act as a rate-limiting factor for Ikaros function. Overexpression of wild-type or dominant-negative Helios isoforms profoundly alters alphabeta T cell differentiation and activation, and endogenous Helios is expressed at strikingly high levels in regulatory T cells. Helios has also been implicated as a tumor suppressor in human T cell acute lymphoblastic leukemias. These studies suggest a central role for Helios in T cell development and homeostasis, but whether this protein is physiologically required in T cells is unclear. We report herein that inactivation of the Helios gene by homologous recombination does not impair the differentiation and effector cell function of alphabeta and gammadelta T cells, NKT cells, and regulatory T cells. These results suggest that Helios is not essential for T cells, and that its function can be compensated for by other members of the Ikaros family.
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Affiliation(s)
- Qi Cai
- Department of Cancer Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM Unité 964, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, Illkirch, France
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John LB, Yoong S, Ward AC. Evolution of the Ikaros gene family: implications for the origins of adaptive immunity. THE JOURNAL OF IMMUNOLOGY 2009; 182:4792-9. [PMID: 19342657 DOI: 10.4049/jimmunol.0802372] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Members of the Ikaros family of transcription factors are important for immune system development. Analysis of Ikaros-related genes from a range of species suggests the Ikaros family derived from a primordial gene, possibly related to the present-day protostome Hunchback genes. This duplicated before the divergence of urochordates to produce two distinct lineages: one that generated the Ikaros factor-like (IFL) 2 genes of urochordates/lower vertebrates and the Pegasus genes of higher vertebrates, and one that generated the IFL1 genes of urochordates/lower vertebrates, the IKFL1 and IKFL2 genes of agnathans and the remaining four Ikaros members of higher vertebrates. Expansion of the IFL1 lineage most likely occurred via the two intervening rounds of whole genome duplication. A proposed third whole genome duplication in teleost fish produced a further increase in complexity of the gene family with additional Pegasus and Eos members. These findings question the use of IFL sequences as evidence for the existence of adaptive immunity in early chordates and vertebrates. Instead, this study is consistent with a later emergence of adaptive immunity coincident with the appearance of the definitive lymphoid markers Ikaros, Aiolos, and Helios.
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Affiliation(s)
- Liza B John
- Center for Cellular and Molecular Biology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia.
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15
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Fujiwara SI, Yamashita Y, Nakamura N, Choi YL, Ueno T, Watanabe H, Kurashina K, Soda M, Enomoto M, Hatanaka H, Takada S, Abe M, Ozawa K, Mano H. High-resolution analysis of chromosome copy number alterations in angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, unspecified, with single nucleotide polymorphism-typing microarrays. Leukemia 2008; 22:1891-8. [PMID: 18633432 DOI: 10.1038/leu.2008.191] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Angioimmunoblastic T-cell lymphoma (AILT) and peripheral T-cell lymphoma, unspecified (PTCL-u) are relatively frequent subtypes of T- or natural killer cell lymphoma. To characterize the structural anomalies of chromosomes associated with these disorders, we here determined chromosome copy number alterations (CNAs) and loss of heterozygosity (LOH) at >55,000 single nucleotide polymorphism loci for clinical specimens of AILT (n=40) or PTCL-u (n=33). Recurrent copy number gain common to both conditions was detected on chromosomes 8, 9 and 19, whereas common LOH was most frequent for a region of chromosome 2. AILT- or PTCL-u-specific CNAs or LOH were also identified at 21 regions, some spanning only a few hundred base pairs. We also identified prognosis-related CNAs or LOH by several approaches, including Cox's proportional hazard analysis. Among the genes that mapped to such loci, a poor prognosis was linked to overexpression of CARMA1 at 7p22 and of MYCBP2 at 13q22, with both genes being localized within regions of frequent copy number gain. For a frequent LOH region at 2q34, we also identified IKAROS family zinc-finger 2 cDNAs encoding truncated proteins. Our data indicate that AILT and PTCL-u consist of heterogeneous subgroups with distinct transforming genetic alterations.
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Affiliation(s)
- S-i Fujiwara
- Division of Functional Genomics, Jichi Medical University, Tochigi, Japan
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