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t(1;7)(p34;q34) TRB/LCK

Written2003-08Jacques Boyer
Laboratoire d' hématologie, CH du MANS, France

(Note : for Links provided by Atlas : click)

Identity

ICD-Topo C420,C421,C424 BLOOD, BONE MARROW, & HEMATOPOIETIC SYS
ICD-Morpho 9837/3 T lymphoblastic leukaemia/lymphoma
Atlas_Id 1045

Clinics and Pathology

Disease Specifically associated with T-cell Acute Lymphoblastic Leukemia (T-ALL). This translocation is related to LCK dysregulation.
Phenotype / cell stem origin T lineage.
Epidemiology Rare : < 1% among T-ALL

Cytogenetics

Cytogenetics Morphological 1p34 is a partner of 7q34. The other partners of 7q34 are 1p32, 9q32, 9q34, 10q24, 11p13, 15q22, 19p13. 22q13 is a novel partner of 1p34 in a precursor T-lymphoblastic leukemia.

Genes involved and Proteins

Gene Name TRB
Location 7q35
Dna / Rna The TRB locus at 7q35 spans 685 Kb. The locus contains 2 types of coding elements : TCR elements (64-67 variable genes TRBV, 2 clusters of diversity, joining and constant segments) and 8 trypsinogen genes. A portion of the TCRB locus has been duplicated and translocated to the chromosome 9 at 9p21.
Protein T cell receptor beta chains.
Gene Name LCK
Location 1p34
Dna / Rna The LCK gene encodes a lymphocyte-specific member of the Src family of protein kinases. Size and orientation strand are unknown. This gene is assigned to bands 1p34.3 by fluorescence in situ hybridation and its mapping relative to the reference marker pYNZ2 (D1S57).
LCK is normally expressed from two distinct promoters.
  • A proximal promoter initiates transcripts designated as type I.
  • A distal promoter, found approximately 30 kb further upstream, initiates transcripts designated as type II.
    Human thymocytes and all the leukemic T cell lines express both type I and type II LCK transcripts, albeit at different levels. Peripheral blood mature T cell express mainly type II LCK transcripts.
    The two types of human LCK transcripts are distingued by their 5'-untranslated regions. However, the protein kinase encoded by both transcripts is the same.
  • Protein The human lymphocyte specific protein tyrosine kinase is a 57869kDa protein (p56LCK) 508 amino acids, involved in T-cell and IL2-receptor signaling important for antigen-induced T-cell activation.

    Result of the chromosomal anomaly

    Hybrid gene
    Description The T-cell acute lymphoblastic leukemia cell line HSB-2 has the t(1;7)(p34;q34) translocation. The T-cell acute lymphoblastic leukemia cell line SUP-T12 has the same translocation.
    The breakpoint in the HSB-2 cell line at 1p34 occurs between the type I and type II promoters and thus separates the two LCK promoters and the type II promoter is translocated to the der(7) chromosome. The breakpoint in the SUP-T12 at 1p34 occurs 2kb upstream of the type II promoter, leaving an intact LCK gene on the der(1) chromosome.
    In HSB-2 the t(1;7) fuses the TCRB constant region and transcriptionnal enhancer with the type I transcription unit of LCK on the der(1) chromosome. (the type II promoter is translocated to the der(7) chromosome). Thus the TCRB enhancer upregulates the type I trancripts.
    An independent t(1;7) in SUP-T12 also resulted in the juxtaposition of LCK to TCRB. The p56LCK protein is elevated approximately 2-fold in comparaison with that in normal T-cell lines and total cellular tyrosine phosphorylation is elevated approximately 10-fold.
      
    Fusion Protein
    Note No fusion protein.
    Oncogenesis The oncogenic p56LCK in T-cell-leukemia lines contains an amino acid substitution within the CD4/CD8 binding domain, two substitutions in the kinase domain and an insertion between the SH2 and kinase domains. These mutations of LCK and the overexpression of p56LCK protein may contribute to some human T-cell leukemias.
      

    Bibliography

    Cytogenetic abnormalities in adult acute lymphoblastic leukemia: correlations with hematologic findings outcome. A Collaborative Study of the Group Français de Cytogénétique Hématologique.
    Blood. 1996 ; 87 (8) : 3135-3142.
    PMID 8605327
     
    Molecular analysis of the T-cell acute lymphoblastic leukemia-associated t(1;7)(p34;q34) that fuses LCK and TCRB.
    Burnett RC, Thirman MJ, Rowley JD, Diaz MO
    Blood. 1994 ; 84 (4) : 1232-1236.
    PMID 8049439
     
    Gene expression signatures define novel oncogenic pathways in T cell acute lymphoblastic leukemia.
    Ferrando AA, Neuberg DS, Staunton J, Loh ML, Huard C, Raimondi SC, Behm FG, Pui CH, Downing JR, Gilliland DG, Lander ES, Golub TR, Look AT
    Cancer cell. 2002 ; 1 (1) : 75-87.
    PMID 12086890
     
    Karyotype and T-cell receptor expression in T-lineage acute lymphoblastic leukemia.
    Secker-Walker LM, Campana D, Hawkins JM, Sampson RE, Coustan-Smith E
    Genes, chromosomes & cancer. 1992 ; 4 (1) : 41-45.
    PMID 1377008
     

    Citation

    This paper should be referenced as such :
    Boyer, J
    t(1;7)(p34;q34)
    Atlas Genet Cytogenet Oncol Haematol. 2003;7(4):266-267.
    Free journal version : [ pdf ]   [ DOI ]
    On line version : http://AtlasGeneticsOncology.org/Anomalies/t0107p34q34ID1045.html


    Other genes implicated (Data extracted from papers in the Atlas) [ 2 ]

    Genes LCK TRB

    Translocations implicated (Data extracted from papers in the Atlas)

     t(1;7)(p34;q34) TRB/LCK

    External links

    TRB (-) LCK (1p35.1)

    Mitelman databaset(1;7)(p34;q34) [Case List]    t(1;7)(p34;q34) [Association List] Mitelman database (CGAP - NCBI)
    arrayMapTopo ( C42) Morph ( 9837/3) - arrayMap (UZH-SIB Zurich)  [auto + random 100 samples .. if exist ]   [tabulated segments]
     
    Mitelman databaseTRB/LCK [MCList]  TRB (-) LCK (1p35.1)
     
    Disease databaset(1;7)(p34;q34) TRB/LCK
    REVIEW articlesautomatic search in PubMed
    Last year articlesautomatic search in PubMed
    All articlesautomatic search in PubMed


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