Fusion genes (updated 2016) | AFF3 (2q11.2) / BCL2 (18q21.33) | ATRX (Xq21.1) / BCL2 (18q21.33) | BCL2 (18q21.33) / BCL2 (18q21.33) |
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BCL2 (18q21.33) / C18orf8 (18q11.2) | BCL2 (18q21.33) / HFE2 (1q21.1) | BCL2 (18q21.33) / IGH (14q32.33) |
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BCL2 (18q21.33) / IGL (22q11.22) | BCL2 (18q21.33) / Ig () | BCL2 (18q21.33) / Immunoglobulin () |
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BCL2 (18q21.33) / TSPO (22q13.2) | BCL2 (18q21.33) / VPS4B (18q21.33) | BCL6 (3q27.3) / BCL2 (18q21.33) |
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DHRS12 (13q14.3) / BCL2 (18q21.33) | HFE2 (1q21.1) / BCL2 (18q21.33) | IGH (14q32.33) / BCL2 (18q21.33) |
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IGHG1 (14q32.33) / BCL2 (18q21.33) | IGK (14q32.33) / BCL2 (18q21.33) | IGL (22q11.22) / BCL2 (18q21.33) |
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IGLV3-10 () / BCL2 (18q21.33) | NEDD4L (18q21.31) / BCL2 (18q21.33) | NGB (14q24.3) / BCL2 (18q21.33) |
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ZNF791 (19p13.2) / BCL2 (18q21.33) |
| Description | 25 kDa; 205 amino acids (BCL2b) or 239 amino acids (BCL2a, which has, in addition, a hydrophobic tail for membrane anchorage; this tail seems necessary for anti apoptotic ability); contain homo/heterodimerization domains (BH) and NH domains. |
| Expression | wide; in B and T cells in particular |
| Localisation | mainly in the mitochondrial membrane; other membranes |
| Function | antiapoptosis, through a possibly complex process; dimerization, especially with BAX; role of the BCL2 anti-apoptosis members in forming complexes with caspase-9 and APAF1 (homolog of the nematode CED-4), which prevent them to initiate the protease cascade (through caspase-3 cytochrome C dependent activation and) leading to apoptosis |
| Homology | with Ced9 (nematode C. elegans); with other member of the BCL2 family: 1- apoptosis inhibitors BCLX, MCL1, and 2- apoptosis inducers BAX, BAD, BIK, ... |
| Note | |
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| Entity | t(14;18)(q32;q21)/B-cell malignancies --> IgH - BCL2 |
| Disease | B- cell NHL mainly; found in 80 to 90 % of follicular lymphomas, 30% of diffuse large cell lymphomas |
| Prognosis | according to the cyto-pathologic subtype (small cleaved cell follicular lymphomas have a good prognosis; large cell lymphomas have a worse prognosis; the t(14;18) may have no prognostic significance) |
| Cytogenetics | complex karyotypes are frequent with +7, del(6q), +12, + X,... |
| Hybrid/Mutated Gene | 5' BCL2 translocated on chromosome 14 near JH (junctions genes of IgH) and C in 3' |
| Abnormal Protein | no fusion protein, but promoter exchange; the immunoglobulin gene enhancer stimulates the expression of BCL2 |
| Oncogenesis | as BCL2 is an apoptosis inhibitor, cell death is delayed, and there is cell accumulation (more than real transformation) |
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| Entity | chronic lymphocytic leukaemia |
| Oncogenesis | BCL2 is hypomethylated in the promotor region, and, therefore, overexpressed |
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| Cloning the chromosomal breakpoint of t(14;18) human lymphomas: clustering around JH on chromosome 14 and near a transcriptional unit on 18. |
| Bakhshi A, Jensen JP, Goldman P, Wright JJ, McBride OW, Epstein AL, Korsmeyer SJ |
| Cell. 1985 ; 41 (3) : 899-906. |
| PMID 3924412 |
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| Nucleotide sequence of a t(14;18) chromosomal breakpoint in follicular lymphoma and demonstration of a breakpoint-cluster region near a transcriptionally active locus on chromosome 18. |
| Cleary ML, Sklar J |
| Proceedings of the National Academy of Sciences of the United States of America. 1985 ; 82 (21) : 7439-7443. |
| PMID 2865728 |
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| Bcl-XL interacts with Apaf-1 and inhibits Apaf-1-dependent caspase-9 activation. |
| Hu Y, Benedict MA, Wu D, Inohara N, Nez G |
| Proceedings of the National Academy of Sciences of the United States of America. 1998 ; 95 (8) : 4386-4391. |
| PMID 9539746 |
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| Bcl-2 heterodimerizes in vivo with a conserved homolog, Bax, that accelerates programmed cell death. |
| Oltvai ZN, Milliman CL, Korsmeyer SJ |
| Cell. 1993 ; 74 (4) : 609-619. |
| PMID 8358790 |
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| Structure, function, and regulation of human cAMP-dependent protein kinases. |
| Taskén K, Skålhegg BS, Taskén KA, Solberg R, Knutsen HK, Levy FO, Sandberg M, Orstavik S, Larsen T, Johansen AK, Vang T, Schrader HP, Reinton NT, Torgersen KM, Hansson V, Jahnsen T |
| Advances in second messenger and phosphoprotein research. 1997 ; 31 : 191-204. |
| PMID 9344252 |
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