151
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Haire RN, Miracle AL, Rast JP, Litman GW. Members of the Ikaros gene family are present in early representative vertebrates. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:306-12. [PMID: 10861066 DOI: 10.4049/jimmunol.165.1.306] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Members of the Ikaros multigene family of zinc finger proteins are expressed in a tissue-specific manner and most are critical determinants in the development of both the B and T lymphocytes as well as NK and dendritic APC lineages. A PCR amplification strategy that is based on regions of shared sequence identity in Ikaros multigene family members found in mammals and several other vertebrates has led to the recovery of cDNAs that represent the orthologues of Ikaros, Aiolos, Helios, and Eos in Raja eglanteria (clearnose skate), a cartilaginous fish that is representative of an early divergence event in the phylogenetic diversification of the vertebrates. The tissue-specific patterns of expression for at least two of the four Ikaros family members in skate resemble the patterns observed in mammals, i.e., in hematopoietic tissues. Prominent expression of Ikaros in skate also is found in the lymphoid Leydig organ and epigonal tissues, which are unique to cartilaginous fish. An Ikaros-related gene has been identified in Petromyzon marinus (sea lamprey), a jawless vertebrate species, in which neither Ig nor TCRs have been identified. In addition to establishing a high degree of evolutionary conservation of the Ikaros multigene family from cartilaginous fish through mammals, these studies define a possible link between factors that regulate the differentiation of immune-type cells in the jawed vertebrates and related factors of unknown function in jawless vertebrates.
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Affiliation(s)
- R N Haire
- Department of Pediatrics and Institute for Biomolecular Sciences, University of South Florida College of Medicine, Children's Research Institute, St. Petersburg, FL 33701, USA
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152
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Koipally J, Georgopoulos K. Ikaros interactions with CtBP reveal a repression mechanism that is independent of histone deacetylase activity. J Biol Chem 2000; 275:19594-602. [PMID: 10766745 DOI: 10.1074/jbc.m000254200] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously shown that Ikaros can repress transcription through the recruitment of histone deacetylase complexes. Here we provide evidence that Ikaros can also repress transcription through its interactions with the co-repressor, C-terminal binding protein (CtBP). CtBP interacts with Ikaros isoforms through a PEDLS motif present at the N terminus of these proteins but not with homologues like Aiolos which lack this motif. Mutations in Ikaros that prevent CtBP interactions reduce its ability to repress transcription. CtBP interacts with Sin3A but not with the Mi-2 co-repressor and it represses transcription in a manner that is independent of histone deacetylase activity. These data strongly suggest that CtBP contributes to a histone deacetylase activity independent mechanism of repression by Ikaros. Finally, we show that the viral oncoprotein E1A, which binds to CtBP, also shows a strong association with Ikaros. This Ikaros-E1A interaction may underlie Ikaros's decreased ability to repress transcription in E1A transformed cells.
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Affiliation(s)
- J Koipally
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA
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153
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Hansen JD, McBlane JF. Recombination-activating genes, transposition, and the lymphoid-specific combinatorial immune system: a common evolutionary connection. Curr Top Microbiol Immunol 2000; 248:111-35. [PMID: 10793476 DOI: 10.1007/978-3-642-59674-2_6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- J D Hansen
- Basel Institute for Immunology, Switzerland.
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154
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Abstract
Since the initial discovery of histone acetyltransferases, numerous reports have established that histone acetyltransferases and histone deacetylases regulate transcription by acetylating and deacetylating histones, respectively. Recent studies have focused on the effects of histone acetylation on gene expression regulation during development and the roles of histone hypoacetylation in the maintenance of centromeric structure, X-inactivation and genomic imprinting. Recent findings have also shown that the functions of non-histone proteins can also be regulated by acetylation. Together, these data highlight the importance of acetylation of histones and non-histone proteins in a variety of chromosomal functions.
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Affiliation(s)
- W L Cheung
- Department of Microbiology, Box 800733, University of Virginia, Health Science Center, Charlottesville, VA 22908-0733, USA
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155
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Spicuglia S, Payet D, Tripathi RK, Rameil P, Verthuy C, Imbert J, Ferrier P, Hempel WM. TCRalpha enhancer activation occurs via a conformational change of a pre-assembled nucleo-protein complex. EMBO J 2000; 19:2034-45. [PMID: 10790370 PMCID: PMC305700 DOI: 10.1093/emboj/19.9.2034] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The TCR alpha enhancer (Ealpha) has served as a paradigm for studying how enhancers organize trans-activators into nucleo-protein complexes thought to recruit and synergistically stimulate the transcriptional machinery. Little is known, however, of either the extent or dynamics of Ealpha occupancy by nuclear factors during T cell development. Using dimethyl sulfate (DMS) in vivo footprinting, we demonstrate extensive Ealpha occupancy, encompassing both previously identified and novel sites, not only in T cells representing a developmental stage where Ealpha is known to be active (CD4(+)CD8(+)-DP cells), but surprisingly, also in cells at an earlier developmental stage where Ealpha is not active (CD4(-)CD8(-)-DN cells). Partial occupancy was also established in B-lymphoid but not non-lymphoid cells. In vivo DNase I footprinting, however, implied developmentally induced changes in nucleo-protein complex topography. Stage-specific differences in factor composition at Ealpha sequences were also suggested by EMSA analysis. These results, which indicate that alterations in the structure of a pre-assembled nucleo-protein complex correlate with the onset of Ealpha activity, may exemplify one mechanism by which enhancers can rapidly respond to incoming stimuli.
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Affiliation(s)
- S Spicuglia
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, Case 906, 13288 Marseille and INSERM U119, 27 boulevard Leï Roure, 13009 Marseille, France
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156
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Abstract
The molecular and cellular requirements for the development of different populations of human dendritic cells (DC) were studied. Conditions were defined that support DC production from lymphoid progenitors but that fail to induce DC formation from peripheral monocytes. The production of these lymphoid-related DC was severely blocked when hematopoietic progenitors overexpressed Ik7, a mutant dominant-negative Ikaros protein. In contrast, Ik7 did not block the formation of DC in conditions supporting the development of monocyte-derived DC. Furthermore, Ik7 did not block the formation of monocyte/macrophages and enhanced granulopoiesis. One of the molecular mechanisms mediated by Ik7 appears to be down-regulation of the flt3-receptor mRNA. Thus, distinct signals control the formation of DC demonstrating that some aspects of DC diversity are determined in part by distinct molecular cues at the hematopoietic level. (Blood. 2000;95:128-137)
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157
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Abstract
Abstract
The molecular and cellular requirements for the development of different populations of human dendritic cells (DC) were studied. Conditions were defined that support DC production from lymphoid progenitors but that fail to induce DC formation from peripheral monocytes. The production of these lymphoid-related DC was severely blocked when hematopoietic progenitors overexpressed Ik7, a mutant dominant-negative Ikaros protein. In contrast, Ik7 did not block the formation of DC in conditions supporting the development of monocyte-derived DC. Furthermore, Ik7 did not block the formation of monocyte/macrophages and enhanced granulopoiesis. One of the molecular mechanisms mediated by Ik7 appears to be down-regulation of the flt3-receptor mRNA. Thus, distinct signals control the formation of DC demonstrating that some aspects of DC diversity are determined in part by distinct molecular cues at the hematopoietic level. (Blood. 2000;95:128-137)
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158
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Sun L, Goodman PA, Wood CM, Crotty ML, Sensel M, Sather H, Navara C, Nachman J, Steinherz PG, Gaynon PS, Seibel N, Vassilev A, Juran BD, Reaman GH, Uckun FM. Expression of aberrantly spliced oncogenic ikaros isoforms in childhood acute lymphoblastic leukemia. J Clin Oncol 1999; 17:3753-66. [PMID: 10577847 DOI: 10.1200/jco.1999.17.12.3753] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE We sought to determine if molecular abnormalities involving the Ikaros gene could contribute to the development of acute lymphoblastic leukemia (ALL) in children. PATIENTS AND METHODS We studied Ikaros gene expression in normal human bone marrow, normal thymocytes, normal fetal liver-derived immature lymphocyte precursor cell lines, eight different ALL cell lines, and leukemic cells from 69 children with ALL (T-lineage ALL, n = 18; B-lineage ALL, n = 51). Expression of Ikaros protein and its subcellular localization were examined by immunoblotting and confocal laser-scanning microscopy, respectively. Polymerase chain reaction (PCR) and nucleotide sequencing were used to identify the specific Ikaros isoforms expressed in these cells. Genomic sequencing of splice junction regions of the Ikaros gene was performed in search for mutations. RESULTS In each of the ALL cases, we found high-level expression of a non-DNA-binding or aberrant DNA-binding isoform of Ikaros with abnormal subcellular compartmentalization patterns. In contrast, only wild-type Ik-1 and Ik-2 isoforms with normal subcellular localization were found in normal bone marrow cells and thymus-derived or fetal liver-derived normal lymphocyte precursors. In leukemic cells expressing the aberrant Ikaros coding sequences with the 30-base-pair deletion, genomic sequence analysis of the intron-exon junctions between exons 6 and 7 yielded the wild-type sequence. We identified a single nucleotide polymorphism (SNP) affecting the third base of the triplet codon for a proline (CCC or CCA) in the highly conserved bipartite activation region (viz, A or C at position 1002 numbering from the translation start site of Ik-1) within our Ikaros clones. Bi-allelic expression of truncated and/or non-DNA-binding isoforms along with wild-type isoforms was observed in leukemic cells, which implicates trans-acting factor(s) affecting splice site recognition. CONCLUSION Our findings link specific molecular defects involving the Ikaros gene to childhood ALL. Posttranscriptional regulation of alternative splicing of Ikaros RNA seems to be defective in leukemic lymphocyte precursors from most children with ALL. Consequently, leukemic cells from ALL patients, in contrast to normal lymphocyte precursors, express high levels of non-DNA-binding Ikaros isoforms that are reminiscent of the non-DNA-binding Ikaros isoforms that lead to lymphoblastic leukemia in mice.
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Affiliation(s)
- L Sun
- Parker Hughes Cancer Center and Children's Cancer Group ALL Biology Reference Laboratory, Hughes Institute, St Paul, MN 55113, USA
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159
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Okano H, Saito Y, Miyazawa T, Shinbo T, Chou D, Kosugi S, Takahashi Y, Odani S, Niwa O, Kominami R. Homozygous deletions and point mutations of the Ikaros gene in gamma-ray-induced mouse thymic lymphomas. Oncogene 1999; 18:6677-83. [PMID: 10597273 DOI: 10.1038/sj.onc.1203100] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Our previous genome-wide analysis of allelic loss for thymic lymphomas that were induced by gamma-irradiation in F1 hybrid mice between BALB/c and MSM strains suggested the centromeric region on chromosome 11 as a site harboring a tumor suppressor gene. Interestingly, to this region the mouse Ikaros gene was mapped which was postulated to participate in oncogenic process from the study of Ikaros knockout mice. Here we show fine allelic loss mapping in the vicinity of Ikaros in 191 lymphomas, indicating that the critical region of allelic loss was centered at the Ikaros locus. PCR analysis revealed that nine lymphomas failed to give PCR-amplification for either of two exon primer pairs, indicative of homozygous deletion. Six and five mutations were detected in the N-terminal zinc finger domain and the activation domain of Ikaros, respectively, and six of the eleven were frameshift or nonsense mutations that resulted in truncation of Ikaros protein. The results strongly suggest a direct role for Ikaros in development of mouse thymic lymphomas. This provides the experimental basis for further analysis of Ikaros mutations in human cancer.
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Affiliation(s)
- H Okano
- Department of Biochemistry, Niigata University School of Medicine, Japan
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160
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Nichogiannopoulou A, Trevisan M, Neben S, Friedrich C, Georgopoulos K. Defects in hemopoietic stem cell activity in Ikaros mutant mice. J Exp Med 1999; 190:1201-14. [PMID: 10544193 PMCID: PMC2195677 DOI: 10.1084/jem.190.9.1201] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/1999] [Accepted: 08/19/1999] [Indexed: 11/18/2022] Open
Abstract
Here we provide evidence that the Ikaros family of DNA binding factors is critical for the activity of hemopoietic stem cells (HSCs) in the mouse. Mice homozygous for an Ikaros null mutation display a >30-fold reduction in long-term repopulation units, whereas mice homozygous for an Ikaros dominant negative mutation have no measurable activity. The defect in HSC activity is also illustrated by the ability of wild-type marrow to repopulate unconditioned Ikaros mutants. A progressive reduction in multipotent CFU-S(14) (colony-forming unit-spleen) progenitors and the earliest erythroid-restricted precursors (BFU-E [burst-forming unit-erythroid]) is also detected in the Ikaros mutant strains consistent with the reduction in HSCs. Nonetheless, the more mature clonogenic erythroid and myeloid precursors are less affected, indicating either the action of a compensatory mechanism to provide more progeny or a negative role of Ikaros at later stages of erythromyeloid differentiation. In Ikaros mutant mice, a decrease in expression of the tyrosine kinase receptors flk-2 and c-kit is observed in the lineage-depleted c-kit(+)Sca-1(+) population that is normally enriched for HSCs and may in part contribute to the early hemopoietic phenotypes manifested in the absence of Ikaros.
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Affiliation(s)
- Aliki Nichogiannopoulou
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129
| | - Maryanne Trevisan
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129
| | - Steve Neben
- Bayer Corporation, Biotechnology Division, Berkeley, California 94710
| | - Christoph Friedrich
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129
| | - Katia Georgopoulos
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129
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161
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Hosokawa Y, Maeda Y, Takahashi EI, Suzuki M, Seto M. Human aiolos, an ikaros-related zinc finger DNA binding protein: cDNA cloning, tissue expression pattern, and chromosomal mapping. Genomics 1999; 61:326-9. [PMID: 10552935 DOI: 10.1006/geno.1999.5949] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Ikaros gene (symbol ZNFN1A1) encodes the hematopoietic zinc finger DNA binding protein, which is now recognized as a central regulator of lymphoid differentiation and has been implicated in leukemogenesis. Recently, an Ikaros-related zinc finger protein, called Aiolos (ZNFN1A3), has been identified and characterized, thus establishing the presence of a gene family whose members may be hematopoietic transcription factors. Among Aiolos-mutant mice, development of B-cell lymphoma was frequently seen. As an initial approach to examining the possible involvement of Aiolos in the pathogenesis of human lymphoid proliferative disease, we isolated cDNA clones for human Aiolos from a B-cell cDNA library. The human Aiolos protein predicted from the cDNA sequence consists of 509 amino acid residues and shares 86% sequence identity with its mouse counterpart. As in the case with mouse Aiolos, no isoform for human Aiolos has been found. Northern blot analysis of various human tissues revealed that the Aiolos transcripts are expressed most strongly in peripheral blood leukocytes, the spleen, and the thymus, supporting the notion that Aiolos plays an important role in lymphoid lineages. Fluorescence in situ hybridization using a BAC clone established that the Aiolos gene is mapped to human chromosome band 17q11.2.
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Affiliation(s)
- Y Hosokawa
- Laboratory of Chemotherapy, Aichi Cancer Center Research Institute, Nagoya, 464-8681, Japan.
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162
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Abstract
Aiolos is an Ikaros-related lymphoid regulatory protein involved in B cell development and function. To evaluate the role of Aiolos in avian B lymphopoiesis, we have cloned and characterized the first non-mammalian Aiolos ortholog in the avian. In sharp contrast to the avian Ikaros, expressed already at the multipotential stage and prior to the colonization of the lymphoid rudiments, Aiolos transcripts were not expressed in early ontogeny and were first detected in cells isolated from the embryonic bursa of Fabricius and thymus. In accordance with Ikaros, the avian Aiolos is also highly related to the mammalian homolog, thus suggesting an evolutionarily conserved function in lymphocyte development. Interestingly, in contrast to the mammalian Aiolos, at least one alternatively spliced form of avian Aiolos is detected in addition to the primary full-length transcript. Both of these alternate transcripts are expressed in bursa, thymus and peripheral lymphoid cells, and no major differences in the expression were detected during lymphocyte development. Furthermore, avian Aiolos is clearly expressed at various stages of B cell development, thus supporting recent evidence for the importance of Aiolos in B cell development and function.
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Affiliation(s)
- J Liippo
- Turku Graduate School of Biomedical Sciences, Turku Immunology Centre and Department of Medical Microbiology, University of Turku, Turku, Finland.
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163
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Affiliation(s)
- S L Reiner
- Gwen Knapp Center for Lupus and Immunology Research, Department of Medicine, The University of Chicago, Illinois 60637, USA.
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164
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Koipally J, Renold A, Kim J, Georgopoulos K. Repression by Ikaros and Aiolos is mediated through histone deacetylase complexes. EMBO J 1999; 18:3090-100. [PMID: 10357820 PMCID: PMC1171390 DOI: 10.1093/emboj/18.11.3090] [Citation(s) in RCA: 240] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Here we show that the lymphoid lineage-determining factors Ikaros and Aiolos can function as strong transcriptional repressors. This function is mediated through two repression domains and is dependent upon the promoter context and cell type. Repression by Ikaros proteins correlates with hypo-acetylation of core histones at promoter sites and is relieved by histone deacetylase inhibitors. Consistent with these findings, Ikaros and its repression domains can interact in vivo and in vitro with the mSin3 family of co-repressors which bind to histone deacetylases. Based on these and our recent findings of associations between Ikaros and Mi-2-HDAC, we propose that Ikaros family members modulate gene expression during lymphocyte development by recruiting distinct histone deacetylase complexes to specific promoters.
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Affiliation(s)
- J Koipally
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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165
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Honma Y, Kiyosawa H, Mori T, Oguri A, Nikaido T, Kanazawa K, Tojo M, Takeda J, Tanno Y, Yokoya S, Kawabata I, Ikeda H, Wanaka A. Eos: a novel member of the Ikaros gene family expressed predominantly in the developing nervous system. FEBS Lett 1999; 447:76-80. [PMID: 10218586 DOI: 10.1016/s0014-5793(99)00265-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We identified a novel member of the Ikaros gene family, which has critical roles in the development of lymphoid lineages. This gene, which we named Eos, was expressed predominantly in the developing central and peripheral nervous system. Eos protein could interact with itself and Ikaros protein through its C-terminal portion in the yeast two hybrid assay. These findings suggested that Eos may have important roles in neural development similarly to the Ikaros family in the development of hemolymphoid tissue.
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Affiliation(s)
- Y Honma
- Department of Cell Science, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima City, Japan
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166
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Kim J, Sif S, Jones B, Jackson A, Koipally J, Heller E, Winandy S, Viel A, Sawyer A, Ikeda T, Kingston R, Georgopoulos K. Ikaros DNA-binding proteins direct formation of chromatin remodeling complexes in lymphocytes. Immunity 1999; 10:345-55. [PMID: 10204490 DOI: 10.1016/s1074-7613(00)80034-5] [Citation(s) in RCA: 459] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The Ikaros gene family encodes zinc finger DNA-binding proteins essential for lineage determination and control of proliferation in the lymphoid system. Here, we report that, in the nucleus of a T cell, a major fraction of Ikaros and Aiolos proteins associate with the DNA-dependent ATPase Mi-2 and histone deacetylases, in a 2 MD complex. This Ikaros-NURD complex is active in chromatin remodeling and histone deacetylation. Upon T cell activation, Ikaros recruits Mi-2/HDAC to regions of heterochromatin. These studies reveal that Ikaros proteins are capable of targeting chromatin remodeling and deacetylation complexes in vivo. We propose that the restructuring of chromatin is a key aspect of Ikaros function in lymphocyte differentiation.
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Affiliation(s)
- J Kim
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown 02129, USA
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167
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Brown KE, Baxter J, Graf D, Merkenschlager M, Fisher AG. Dynamic repositioning of genes in the nucleus of lymphocytes preparing for cell division. Mol Cell 1999; 3:207-17. [PMID: 10078203 DOI: 10.1016/s1097-2765(00)80311-1] [Citation(s) in RCA: 324] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We show that several transcriptionally inactive genes localize to centromeric heterochromatin in the nucleus of cycling but not quiescent (noncycling) primary B lymphocytes. In quiescent cells, centromeric repositioning of inactive loci was induced after mitogenic stimulation. A dynamic repositioning of selected genes was also observed in developing T cells. Rag and TdT loci were shown to relocate to centromeric domains following heritable gene silencing in primary CD4+8+ thymocytes, but not in a phenotypically similar cell line in which silencing occurred but was not heritable. Collectively, these data indicate that the spatial organization of genes in cycling and noncycling lymphocytes is different and that locus repositioning may be a feature of heritable gene silencing.
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Affiliation(s)
- K E Brown
- Lymphocyte Development Group, MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital, London, United Kingdom
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168
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Sun L, Heerema N, Crotty L, Wu X, Navara C, Vassilev A, Sensel M, Reaman GH, Uckun FM. Expression of dominant-negative and mutant isoforms of the antileukemic transcription factor Ikaros in infant acute lymphoblastic leukemia. Proc Natl Acad Sci U S A 1999; 96:680-5. [PMID: 9892693 PMCID: PMC15196 DOI: 10.1073/pnas.96.2.680] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ikaros, a zinc finger-containing DNA-binding protein, is required for normal lymphocyte development, and germline mutant mice that express only non-DNA binding dominant-negative "leukemogenic" Ikaros isoforms lacking critical N-terminal zinc fingers develop an aggressive form of lymphoblastic leukemia 3-6 months after birth. Therefore, we sought to determine whether molecular abnormalities involving the Ikaros gene could contribute to the development of acute lymphoblastic leukemia (ALL) in infants. Primary leukemic cells were freshly obtained from 12 infants (<1 year of age) with newly diagnosed ALL. In leukemic cells from each of the 12 infants with ALL, we found high level expression of dominant-negative isoforms of Ikaros with abnormal subcellular compartmentalization patterns. PCR cloning and nucleotide sequencing were used to identify the specific Ikaros isoforms and detect Ikaros gene mutations in these cells. Leukemic cells from seven of seven infants with ALL, including five of five MLL-AF4(+) infants, expressed dominant-negative Ikaros isoforms Ik-4, Ik-7, and Ik-8 that lack critical N-terminal zinc fingers. In six of seven patients, we detected a specific mutation leading to an in-frame deletion of 10 amino acids (Delta KSSMPQKFLG) upstream of the transcription activation domain adjacent to the C-terminal zinc fingers of Ik-2, Ik-4, Ik-7, and Ik-8. In contrast, only wild-type Ik-1 and Ik-2 isoforms with normal nuclear localization were found in normal infant bone marrow cells and infant thymocytes. These results implicate the expression of dominant-negative Ikaros isoforms and the disruption of normal Ikaros function in the leukemogenesis of ALL in infants.
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Affiliation(s)
- L Sun
- Parker Hughes Cancer Center, Children's Cancer Group ALL Biology Reference Laboratory, Departments of Genetics, Hughes Institute, St. Paul, MN 55113, USA
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169
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Lampisuo M, Liippo J, Vainio O, McNagny KM, Kulmala J, Lassila O. Characterization of prethymic progenitors within the chicken embryo. Int Immunol 1999; 11:63-9. [PMID: 10050674 DOI: 10.1093/intimm/11.1.63] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The thymic primordium in both birds and mammals is first colonized by cells emerging from the intra-embryonic mesenchyme but the nature of these precursors is poorly understood. We demonstrate here an early embryonic day 7 prethymic population with T lymphoid potential. Our work is a phenotypic analysis of, to date, the earliest embryonic prethymic progenitors arising in the avian para-aortic area during ontogeny. The phenotype of these cells, expressing the cell surface molecules alpha2beta1 integrin, c-kit, thrombomucin/MEP21, HEMCAM and chL12, reflects functional properties required for cell adhesion, migration and growth factor responsiveness. Importantly, the presence of these antigens was found to correlate with the recolonization of the recipient thymus following intrathymic cell transfers. These intra-embryonic cells were also found to express the Ikaros transcription factor, the molecular function of which is considered to be prerequisite for embryonic lymphoid development.
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Affiliation(s)
- M Lampisuo
- Turku Immunology Centre, Department of Medical Microbiology, University of Turku, Finland
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170
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Whetton AD, Spooncer E. Role of cytokines and extracellular matrix in the regulation of haemopoietic stem cells. Curr Opin Cell Biol 1998; 10:721-6. [PMID: 9914176 DOI: 10.1016/s0955-0674(98)80113-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The understanding of molecular mechanisms regulating the formation, growth and differentiation of haemopoietic stem cells has advanced considerably recently. Particular progress has been made in defining the cytokines, chemokines and extracellular matrix components which retain and maintain primitive haemopoietic cell populations in bone marrow. Furthermore, signal transduction pathways that are critical for haemopoiesis, both in vivo and in vitro, and that are activated by cytokines have also been identified and further characterised. The importance of these processes has, this year, been exemplified by the phenotypes of mice deficient in key signal transduction proteins and the discovery that mutations in the component proteins of some signalling pathways are linked to human diseases. Significant advances in understanding the molecular mechanisms for mobilisation of stem cells from bone marrow have also been made this year; this has potential importance for bone marrow transplantation.
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Affiliation(s)
- A D Whetton
- Leukaemia Research Fund Unit Department of Biomolecular Sciences University of Manchester Institute of Science and Technology PO Box 88 Sackville Street Manchester M60 1QD UK.
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Wang JH, Avitahl N, Cariappa A, Friedrich C, Ikeda T, Renold A, Andrikopoulos K, Liang L, Pillai S, Morgan BA, Georgopoulos K. Aiolos regulates B cell activation and maturation to effector state. Immunity 1998; 9:543-53. [PMID: 9806640 DOI: 10.1016/s1074-7613(00)80637-8] [Citation(s) in RCA: 240] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Aiolos encodes a zinc finger DNA-binding protein that is highly expressed in mature B cells and is homologous to Ikaros. In the periphery of mice homozygous for an Aiolos-null mutation, B cells exhibit an activated cell surface phenotype and undergo augmented antigen receptor (BCR)-mediated in vitro proliferative responses, even at limiting amounts of stimulant. In vivo, T cell-dependent B cell responses, including the formation of germinal centers and elevated serum IgG and IgE, are detected in Aiolos-deficient mice in the absence of immunization. Auto-antibodies and development of B cell lymphomas are frequently seen among aging Aiolos mutants. In sharp contrast to conventional B cells, B cells of the peritoneum, of the marginal zone, and the recirculating bone marrow population are greatly reduced.
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Affiliation(s)
- J H Wang
- Cutaneous Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown 02129, USA
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