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t(7;9)(q34;q32) TRB/TAL2

Written2002-11Jacques 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 1056

Clinics and Pathology

Disease Specifically associated with T-cell Acute lymphoblastic leukemia (T-ALL)
Epidemiology The t(7;9)(q34;q32) is present in two cases of a serie of 5 patients with 7q34 involvment.
Clinics Children with large mediastinal mass
Cytology The hematological feature of the T-ALL with rearrangement of 7q34 shows high WBC (range 95 to 400 x 109/L)

Cytogenetics

Cytogenetics Morphological 9q32 is a partner of 7q34. The other partners are 1p34,1p32, 9q34,10q24,11p13, 15q22 and 19p13
Additional anomalies del(6)(q21), del(4)(q31q35)

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 TAL2
Location 9q32
Dna / Rna The TAL2 gene is located at q32
Protein TAL2 potentially encodes a basic helix-loop-helix (bHLH) phosphoprotein (size 108 amino acids) that is highly related to those specified by TAL1 and LYL1 also implicated in T-ALL. The bHLH protein interacts with the product of RBTN1 and RBTN2 (cysteine-rich LIM motifs)

Result of the chromosomal anomaly

Hybrid gene
Description TAL2 is transcriptionaly activated by t(7;9)(q34;q32) in T-ALL.The chromosome 9 breakpoints of the t(7;9)(q34;q32) occur 33 kbp downstream of sequences that encode the TAL2 HLH domain. Translocated TAL2 are juxtaposed with transcriptional regulatory elements within the T-cell receptor beta-chain locus.
  
Fusion Protein
Note No fusion protein.
Oncogenesis The TAL2 transcription is activated ectopically in lymphoid cells and the inappropriate expression of TAL2 in these cells promotes development of T-ALL. Normaly, the TAL genes are not expressed in the thymus. The TAL genes become activated and expressed in the thymus upon chromosomal translocation which ultimately leads to the development of T-ALL.
The (7;9) translocation express a TAL2 gene product of 108 amino acids. In leukemic cells this product exists in both a phosphorylated and an unphosphorylated form. Serine residue 100 is the major site of TAL2 phosphorylation in vivo. And it serves as an effective in vitro substrate for MAP kinases such as ERK1.
TAL2 polypeptides interact in vivo with the E2A gene products to form HLH heterodimers that bind DNA, the result is the E2A inactivation. The E2A products are transcriptional factors implicated in the B and T cell development.
TAL2 product was also shown to bind with a GTP binding protein (DRG). The properties of TAL2 broadly resemble those described previously for TAL1 and therefore support the idea that both encoded proteins promote T-ALL by a common mechanism and the malignant potential of these proteins is likely to reside within their HLH domains though the inactivation of E2A.
  

To be noted

Case Report Translocation t(7;9)(q34;q32) found in pediatric T-cell Acute Lymphoblastic Leukemia

Bibliography

Cytogenetic abnormalities in adult acute lymphoblastic leukemia: correlations with hematologic findings outcome. A Collaborative Study of the Groupe Français de Cytogénétique Hématologique (GFCH).
Blood. 1996 ; 87 (8) : 3135-3142.
PMID 8605327
 
TAL1, TAL2 and LYL1: a family of basic helix-loop-helix proteins implicated in T cell acute leukaemia.
Baer R
Seminars in cancer biology. 1993 ; 4 (6) : 341-347.
PMID 8142619
 
E2A deficiency leads to abnormalities in alphabeta T-cell development and to rapid development of T-cell lymphomas.
Bain G, Engel I, Robanus Maandag EC, te Riele HP, Voland JR, Sharp LL, Chun J, Huey B, Pinkel D, Murre C
Molecular and cellular biology. 1997 ; 17 (8) : 4782-4791.
PMID 9234734
 
Association of a novel GTP binding protein, DRG, with TAL oncogenic proteins.
Mahajan MA, Park ST, Sun XH
Oncogene. 1996 ; 12 (11) : 2343-2350.
PMID 8649774
 
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
 
Clinical and biologic characterization of T-cell neoplasias with rearrangements of chromosome 7 band q34.
Smith SD, Morgan R, Gemmell R, Amylon MD, Link MP, Linker C, Hecht BK, Warnke R, Glader BE, Hecht F
Blood. 1988 ; 71 (2) : 395-402.
PMID 2962650
 
Specific in vivo association between the bHLH and LIM proteins implicated in human T cell leukemia.
Wadman I, Li J, Bash RO, Forster A, Osada H, Rabbitts TH, Baer R
The EMBO journal. 1994 ; 13 (20) : 4831-4839.
PMID 7957052
 
TAL2, a helix-loop-helix gene activated by the (7;9)(q34;q32) translocation in human T-cell leukemia.
Xia Y, Brown L, Yang CY, Tsan JT, Siciliano MJ, Espinosa R III, Le Beau MM, Baer RJ
Proceedings of the National Academy of Sciences of the United States of America. 1991 ; 88 (24) : 11416-11420.
PMID 1763056
 
Products of the TAL2 oncogene in leukemic T cells: bHLH phosphoproteins with DNA-binding activity.
Xia Y, Hwang LY, Cobb MH, Baer R
Oncogene. 1994 ; 9 (5) : 1437-1446.
PMID 8152805
 

Citation

This paper should be referenced as such :
Boyer, J
t(7;9)(q34;q32)
Atlas Genet Cytogenet Oncol Haematol. 2003;7(1):38-39.
Free journal version : [ pdf ]   [ DOI ]
On line version : http://AtlasGeneticsOncology.org/Anomalies/t0709q34q32ID1056.html


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

Genes TAL2 TRB

Translocations implicated (Data extracted from papers in the Atlas)

 t(7;9)(q34;q32) TRB/TAL2

External links

TRB (-) TAL2 (9q31.2)

Mitelman databaset(7;9)(q34;q32) [Case List]    t(7;9)(q34;q32) [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/TAL2 [MCList]  TRB (-) TAL2 (9q31.2)
 
Disease databaset(7;9)(q34;q32) TRB/TAL2
REVIEW articlesautomatic search in PubMed
Last year articlesautomatic search in PubMed
All articlesautomatic search in PubMed


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