The lymphoid transcription factor LyF-1 is encoded by specific, alternatively spliced mRNAs derived from the Ikaros gene

1994 ◽  
Vol 14 (11) ◽  
pp. 7111-7123
Author(s):  
K Hahm ◽  
P Ernst ◽  
K Lo ◽  
G S Kim ◽  
C Turck ◽  
...  
Keyword(s):  
Amino Acid ◽  
T Cell ◽  
Dna Binding ◽  
Amino Acid Sequence ◽  
Zinc Finger ◽  
T Cell Development ◽  
Cell Development ◽  
Control Element ◽  
Early Stages ◽  
Alternatively Spliced

The lymphocyte-specific DNA-binding protein LyF-1 interacts with a critical control element in the terminal deoxynucleotidyltransferase (TdT) promoter as well as with the promoters for other genes expressed during early stages of B- and T-cell development. We have purified LyF-1 and have obtained a partial amino acid sequence from proteolytic peptides. The amino acid sequence suggests that LyF-1 is a zinc finger protein encoded by the Ikaros gene, which previously was implicated in T-cell development. Recombinant Ikaros expressed in Escherichia coli bound to the TdT promoter, and antisera directed against the recombinant protein specifically blocked the DNA-binding activity of LyF-1 in crude extracts. Further analysis revealed that at least six distinct mRNAs are derived from the Ikaros/LyF-1 gene by alternative splicing. Only two of the isoforms possess the N-terminal zinc finger domain that is necessary and sufficient for TdT promoter binding. Although both of these isoforms bound to similar sequences in the TdT, lambda 5, VpreB, and lck promoters, one isoform contains an additional zinc finger that resulted in altered recognition of some binding sites. At least four of the Ikaros/LyF-1 isoforms were detectable in extracts from B- and T-cell lines, with the relative amounts of the isoforms varying considerably. These data reveal that the LyF-1 protein is encoded by specific mRNAs derived from the alternatively-spliced Ikaros gene, suggesting that this gene may be important for the early stages of both B- and T-lymphocyte development.

scholarly journals The lymphoid transcription factor LyF-1 is encoded by specific, alternatively spliced mRNAs derived from the Ikaros gene.

1994 ◽  
Vol 14 (11) ◽  
pp. 7111-7123 ◽  
Author(s):  
K Hahm ◽  
P Ernst ◽  
K Lo ◽  
G S Kim ◽  
C Turck ◽  
...  
Keyword(s):  
Amino Acid ◽  
T Cell ◽  
Dna Binding ◽  
Amino Acid Sequence ◽  
Zinc Finger ◽  
T Cell Development ◽  
Cell Development ◽  
Control Element ◽  
Early Stages ◽  
Alternatively Spliced

The lymphocyte-specific DNA-binding protein LyF-1 interacts with a critical control element in the terminal deoxynucleotidyltransferase (TdT) promoter as well as with the promoters for other genes expressed during early stages of B- and T-cell development. We have purified LyF-1 and have obtained a partial amino acid sequence from proteolytic peptides. The amino acid sequence suggests that LyF-1 is a zinc finger protein encoded by the Ikaros gene, which previously was implicated in T-cell development. Recombinant Ikaros expressed in Escherichia coli bound to the TdT promoter, and antisera directed against the recombinant protein specifically blocked the DNA-binding activity of LyF-1 in crude extracts. Further analysis revealed that at least six distinct mRNAs are derived from the Ikaros/LyF-1 gene by alternative splicing. Only two of the isoforms possess the N-terminal zinc finger domain that is necessary and sufficient for TdT promoter binding. Although both of these isoforms bound to similar sequences in the TdT, lambda 5, VpreB, and lck promoters, one isoform contains an additional zinc finger that resulted in altered recognition of some binding sites. At least four of the Ikaros/LyF-1 isoforms were detectable in extracts from B- and T-cell lines, with the relative amounts of the isoforms varying considerably. These data reveal that the LyF-1 protein is encoded by specific mRNAs derived from the alternatively-spliced Ikaros gene, suggesting that this gene may be important for the early stages of both B- and T-lymphocyte development.

scholarly journals Expression of a non–DNA-binding isoform of Helios induces T-cell lymphoma in mice

Blood ◽  
2006 ◽  
Vol 109 (5) ◽  
pp. 2190-2197 ◽  
Author(s):  
Zheng Zhang ◽  
C. Scott Swindle ◽  
John T. Bates ◽  
Rose Ko ◽  
Claudiu V. Cotta ◽  
...  
Keyword(s):  
T Cell ◽  
Dna Binding ◽  
Zinc Finger ◽  
Zinc Finger Protein ◽  
Cell Lymphoma ◽  
T Cell Development ◽  
Constitutive Expression ◽  
Cell Development ◽  
T Cell Lymphoma ◽  
Full Length

Abstract Helios is a zinc-finger protein belonging to the Ikaros family of transcriptional regulators. It is expressed, along with Ikaros, throughout early stages of thymocyte development where it quantitatively associates with Ikaros through C-terminal zinc-finger domains that mediate heterodimerization between Ikaros family members. To understand the role of Helios in T-cell development, we used a retroviral vector to express full-length Helios or a Helios isoform that lacked the N-terminal DNA-binding domain in hematopoietic progenitor cells of reconstituted mice. Constitutive expression of full-length Helios resulted in an inhibition of T-cell development at the double-negative stage within the thymus. Although expression of the DNA-binding mutant of Helios did not contribute to developmental abnormalities at early times after transplantation, 60% of animals that expressed the Helios DNA-binding mutant developed an aggressive and transplantable T-cell lymphoma 4 to 10 months after transplantation. These results demonstrate a vital function for Helios in maintaining normal homeostasis of developing T cells and formally show that non–DNA-binding isoforms of Helios are lymphomagenic if aberrantly expressed within the T-cell lineage.

Reduction of Core Binding Factor beta (CBFβ) Dosage Blocks T Cell Development.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2714-2714
Author(s):  
Yalin Guo ◽  
Laleh Talebian ◽  
Ivan Maillard ◽  
Caroline L. Speck ◽  
Warren S. Pear ◽  
...  
Keyword(s):  
T Cell ◽  
Dna Binding ◽  
Fetal Liver ◽  
T Cell Development ◽  
Notch Pathway ◽  
Cell Development ◽  
Liver Cells ◽  
Normal Numbers ◽  
Hematopoietic Stem ◽  
Fetal Liver Cells

Abstract Core binding factors (CBFs) are heterodimers consisting of a DNA binding subunit (Runx1, Runx2, or Runx3) and a non-DNA binding CBFβ subunit. CBFβ increases the affinity of the Runx subunits for DNA. Embryos deficient for Runx1 or CBFβ die at midgestation with a complete failure of definitive hematopoiesis due to a block in hematopoietic stem cell (HSC) emergence. To examine the role of core binding factors at later stages of hematopoiesis, we generated a hypomorphic Cbfb allele (Cbfbrss), that when carried over a Cbfb null allele (Cbfbrss/−) results in a 3-4 fold reduction in CBFβ protein levels. Although HSCs emerge in Cbfbrss/− animals, fetal T cell development is severely impaired. Here we examined the T cell developmental block in more detail by culturing fetal liver cells from Cbfbrss/− animals on OP9 stromal cells that express the Notch ligand Delta-like-1 (DL1) (Schmitt and Zúñiga-Pflücker, Immunity17: 749, 2002). Fetal livers (E14.5) from Cbfbrss/− animals contained normal numbers of both c-kit+Sca-1+lin- cells and c-kit+IL7r+ lymphoid progenitors. Lin- fetal liver progenitors cultured on OP9-DL1 cells in the presence of IL-7 and Flt3L displayed a growth disadvantage relative to wild type cells, and a block at the double negative 1 (DN1, CD44+ CD25−) stage of T cell development. The T cell defect could be rescued by retroviral transduction of the CBFβ heterodimerization domain into lin- fetal liver cells, but not by a G61A/N104A mutant that cannot bind the Runx subunits. Genes whose expression was decreased in DN1 cells purified from the OP9-DL1 cultures included CD3 and the early T cell transcription factors GATA3 and TCF. Although expression of several Notch pathway genes (Notch1, Hes-1/5, Deltex-1) was mildly decreased, Notch signals were clearly transduced, suggesting that Notch signaling was intact. These data demonstrate that reduced CBFβ levels impair the differentiation of stem cells/progenitors into T cells at the earliest stage of T cell development. This in vitro model will be useful for characterizing the molecular circuitry involving CBFβ in T cell development, and for identifying CBFβ protein partners.

A Hypomorphic Cbfb Allele Reveals a Critical Dosage-Sensitive Function of Core Binding Factors at the Earliest Stages of T Cell Development.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 124-124
Author(s):  
Ivan Maillard ◽  
Laleh Talebian ◽  
Zhe Li ◽  
Yalin Guo ◽  
Daisuke Sugiyama ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Dna Binding ◽  
B Cell ◽  
Bone Marrow Cells ◽  
T Cell Development ◽  
Cell Development ◽  
B Cell Development ◽  
Hematopoietic Stem

Abstract The family of core binding factors includes the DNA-binding subunits Runx1-3 and the common non-DNA binding partner CBFβ. Runx1 and CBFβ are essential for the emergence of hematopoietic stem cells during fetal development, but not for stem cell maintenance during later ontogeny. Runx1 is also required for megakaryocyte differentiation, B cell development, and for the DN2 to DN3 transition in thymocyte development. Runx2/CBFβ are critical for normal osteogenesis, and Runx3 for CD4 silencing in CD8+ T cells, but their contribution to other steps of hematopoietic development is unknown. To examine the collective role of core binding factors in hematopoiesis, we generated a hypomorphic Cbfb allele (Cbfbrss). CBFβ protein levels were reduced by approximately 2–3 fold in fetuses homozygous for the Cbfbrss allele (Cbfbrss/rss), and 3–4 fold in fetuses carrying one hypomorphic and one knockout allele (Cbfbrss/−). Cbfbrss/rss and Cbfbrss/− fetuses had normal erythroid and B cell development, and relatively mild abnormalities in megakaryocyte and granulocyte differentiation. In contrast, T cell development was very sensitive to an incremental reduction of CBFβ levels: mature thymocytes were decreased in Cbfbrss/rss fetuses, and virtually absent in Cbfbrss/−fetuses. We next assessed the development of Cbfbrss/rss and Cbfbrss/− fetal liver progenitors after transplantation to irradiated adult recipients, in competition with wild-type (wt) bone marrow cells. Wt, Cbfbrss/rss and Cbfbrss/− fetal progenitors replenished the erythroid, myeloid and B cell compartments equally well. The overall development of Cbfbrss/rss T cells was preserved, although CD4 expression was derepressed in double negative thymocytes. In Cbfbrss/− chimeras, mature thymocytes were entirely derived from competitor cells. Furthermore, the developmental block in Cbfbrss/− progenitors was present at the earliest stages of T cell development within the DN1 (ETP) and DN2 subsets. Our data define a critical CBFβ threshold for normal T cell development, and they situate an essential role of core binding factors during the earliest stages of T cell development. In addition, early thymopoiesis appeared more severely affected by reduced CBFβ dosage than by the lack of Runx1 (Ichikawa et al., Nat Med 2004; Growney et al., Blood 2005), suggesting that Runx2/3 may contribute to core binding factor activity in the T cell lineage.

scholarly journals Erratum: Requirement for Notch1 signals at sequential early stages of intrathymic T cell development

2005 ◽  
Vol 6 (9) ◽  
pp. 954-954
Author(s):  
Joanne B Tan ◽  
Ioana Visan ◽  
Julie S Yuan ◽  
Cynthia J Guidos
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Early Stages

scholarly journals Cytosolic Sequestration of Prep1 Influences Early Stages of T Cell Development

PLoS ONE ◽  
2008 ◽  
Vol 3 (6) ◽  
pp. e2424 ◽  
Author(s):  
Dmitry Penkov ◽  
Martina Palazzolo ◽  
Anna Mondino ◽  
Francesco Blasi
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Early Stages

scholarly journals Impairment of  T Cell Development in δEF1 Mutant Mice

1997 ◽  
Vol 185 (8) ◽  
pp. 1467-1480 ◽  
Author(s):  
Yujiro Higashi ◽  
Hiroki Moribe ◽  
Tsuyoshi Takagi ◽  
Ryohei Sekido ◽  
Kiyoshi Kawakami ◽  
...  
Keyword(s):  
T Cell ◽  
Zinc Finger ◽  
Early Stage ◽  
T Cell Development ◽  
Embryonic Stem ◽  
Cell Development ◽  
Mutant Mice ◽  
Regulatory Function ◽  
Thymocyte Development ◽  
Single Positive

Using the method of gene targeting in mouse embryonic stem cells, regulatory function of δEF1, a zinc finger and homeodomain-containing transcription factor, was investigated in vivo by generating the δEF1 mutant mice. The mutated allele of δEF1 produced a truncated form of the δEF1 protein lacking a zinc finger cluster proximal to COOH terminus. The homozygous δEF1 mutant mice had poorly developed thymi with no distinction of cortex and medulla. Analysis of the mutant thymocyte showed reduction of the total cell number by two orders of magnitude accompanying the impaired thymocyte development. The early stage intrathymic c-kit+ T precursor cells were largely depleted. The following thymocyte development also seemed to be affected as assessed by the distorted composition of CD4- or CD8-expressing cells. The mutant thymocyte showed elevated α4 integrin expression, which might be related to the T cell defect in the mutant mice. In the peripheral lymph node tissue of the mutant mice, the CD4−CD8+ single positive cells were significantly reduced relative to CD4+CD8− single positive cells. In contrast to T cells, other hematopoietic lineages appeared to be normal. The data indicated that δEF1 is involved in regulation of T cell development at multiple stages.

scholarly journals Signals from the IL-9 Receptor Are Critical for the Early Stages of Human Intrathymic T Cell Development

2000 ◽  
Vol 164 (4) ◽  
pp. 1761-1767 ◽  
Author(s):  
Magda De Smedt ◽  
Bruno Verhasselt ◽  
Tessa Kerre ◽  
Dominique Vanhecke ◽  
Evelien Naessens ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Early Stages

The BCL11B Tumor Suppressor Is Mutated In Human T-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4177-4177
Author(s):  
Alejandro Gutierrez ◽  
Alex Kentsis ◽  
Takaomi Sanda ◽  
Julia Etchin ◽  
Alexei Protopopov ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
Tumor Suppressor ◽  
Treatment Failure ◽  
Zinc Finger ◽  
Array Cgh ◽  
T Cell Development ◽  
Cell Development ◽  
Developmental Arrest ◽  
Risk Of Treatment

Abstract Abstract 4177 The BCL11B transcription factor, previously identified as a central player in normal α/β T-cell development, has recently been found to play critical roles in the maintenance of T-cell identity, with biallelic Bcl11b inactivation in T-cell precursors severely impairing their continued development into the T-cell lineage. Previous work has demonstrated that Bcl11b haploinsufficiency accelerates the onset of thymic lymphomas in p53-mutant mice, as well as T-lymphoid blast crisis in a mouse model of chronic myeloid leukemia induced by BCR-ABL. Furthermore, we have recently identified recurrent monoallelic Bcl11b deletions in 91% of T-cell acute lymphoblastic leukemias (T-ALL) arising in Atm-deficient mice, further supporting a role for Bcl11b haploinsufficiency in T-cell leukemogenesis. In order to determine whether BCL11B inactivation plays a role in the molecular pathogenesis of human T-ALL, we analyzed BCL11B status in primary T-ALL patient samples by array CGH and sequencing analysis. Monoallelic BCL11B deletions were identified in 6% of cases (n = 3 of 47) analyzed by array CGH, including one microdeletion within the BCL11B locus, one small deletion involving BCL11B and 6 additional genes, and one large 26 Mbp deletion of the distal arm of chromosome 14. BCL11B sequencing revealed heterozygous missense mutations in an additional 9% (n = 4 of 43) of primary T-ALL patient samples and in 19% (n = 3 of 16) of T-ALL cell lines. Structural homology modeling revealed that many of the mutations identified, including 3 of the 4 in the primary patient samples, disrupted key amino acids within BCL11B zinc finger domains that are involved in DNA recognition or structural stabilization required for zinc finger domain-mediated transcriptional activity. Analysis of TCRγ rearrangement status and gene expression data revealed that most cases with BCL11B inactivation were characterized by biallelic TCRγ rearrangements together with an early thymocyte precursor (ETP) gene expression signature, indicating developmental arrest at a prethymocyte stage of T-cell development, which we and others have shown confers an increased risk of treatment failure (Coustan-Smith et al. Lancet Oncol 2009; Gutierrez et al. J Clin Oncol 2010). Given that BCL11B expression during normal T-cell development increases markedly at the prethymocyte stage, our findings suggest that BCL11B inactivation may be directly responsible for developmental arrest at a prethymocyte stage during thymocyte transformation. Our findings provide compelling evidence that BCL11B is a tumor suppressor in a subset of human T-ALLs with a high risk of treatment failure. Disclosures: No relevant conflicts of interest to declare.

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