Atlas of Genetics and Cytogenetics in Oncology and Haematology
FCGR2B
| Identity |
| Other names | CD32 |
| FCG2 | |
| FCGR2 | |
| IGFR2 | |
| HGNC (Hugo) | FCGR2B |
| Location | 1q22 |
| Location_base_pair | Starts at 161632940 and ends at 161647951 bp from pter ( according to hg19-Feb_2009) [Mapping] |
| Local_order | location, by FISH/genome sequencing; FCGR2B is contained within a locus that spans approximately 200kb and that encodes 5 low affinity IgG Fc receptor genes.The published gene orientation is as follows; Cen 1q -- 3' FCGR2A 5' -- 5'- FCGR3A - 3' -- 3' FCGR2B 5' -- 5' - FCGR3B - 3' -- 5'- FCGR2C- 3'. |
 | |
| Probe(s) - Courtesy Mariano Rocchi, Resources for Molecular Cytogenetics | |
| DNA/RNA |
| Description | The FCGR2B gene spans a 15kb genomic region; Gene orientation : centromere - 3' FCGR2B 5' - telomere; 8 exons (denoted S1, S2, EC1, EC2, TM, IC1, IC2, IC3). S1 and S2 encode the signal peptide domain, EC1 and EC2 encode the extracellular domain, TM encodes the transmembrane domain and IC1, IC2, IC3 encode the intracytoplasmic region. |
| Transcription | 1.7kb mRNA. Two alternately spliced mRNA exist in humans; FcgRIIb1 and FcgRIIb2 (a 19 aa insertion encoded by IC1 is present in b1 but not in b2). |
| Protein |
| Note | called Fc gamma RIIB |
| Description | 40kD transmembrane glycoprotein that possesses an intracytoplasmic Immunoreceptor Tyrosine-based Inhibition Motif (ITIM) (encoded by IC3). |
| Expression | B, myeloid and mast cells. |
| Localisation | Transmembrane. |
| Function | Low affinity IgG Fc receptor. Founding member ITIM family of immune inhibitory receptors. Fc gamma RIIB functions to down-regulate activatory responses mediated by Immunoreceptor Tyrosine-based Inhibition Motif (ITAM) bearing receptors such as the B-cell receptor on B cells. For example, on B-cells, negative regulation of B-cell receptor activatory signalling is initiated through co-recruitment of BCR and Fc gamma RIIB to IgG/ immune complexes. This leads to tyrosyl phosphorylation of the Fc gamma RIIB ITIM motif / recruitment of the inositol phosphatase SHIP and activation of the adaptor protein Dok - these events ultimately lead to the inhibition of ITAM-dependant Ca++ mobilisation and cellular proliferation (reduced MAPK signalling), respectively. A proapoptotic signal through the Fc gamma RIIB transmembrane sequence has been described in conditions of homo-aggregation of Fc gamma RII on murine B cells. |
| Homology | Contains two immunoglobulin-like C2 domains. |
| Implicated in |
| Entity | 1q21-23 rearrangements in NHL (Nnon-Hodgkins Lymphoma) |
| Disease | NHL (< 5% of cases with 1q21-23 breaks) |
| Prognosis | It is now known that cytogenetically determined 1q21-23 breaks can target a diversity of 1q21-23 genes. Early data has suggested a poor prognosis for 1q21 rearrangements in diffuse large cell lymphoma. |
| Cytogenetics | Deregulation of the FCGR2B gene by chromosomal translocation was first demonstrated in 3 NHL patients that showed a t(1;22)(q22;q22) in association with a t(14;18)(q32;q21). Two further cases of NHL with rearrangements affecting the FCGR2B region have since been identified. Both cases also showed t(14;18)(see below for description). This suggests a role for this deregulation in lymphoma progression. |
| Hybrid/Mutated Gene | Dysregulation of the FCGR2B gene has been identified as a consequence of a t(1;22)(q22;q11) (3 patients) and t(1;14)(q21;q32) (1 patient). The FCGR2B coding sequence and promoter region appear to remain intact in these translocations. The principal consequence is overexpression of the Fc gamma RIIb2 isoform of Fc gamma RIIB. Deregulation of FCGR2B most likely occurs as a consequence of Ig gene transcriptional enhancer activity. Other mechanisms may exist ; an NHL patient with dup(1)(q21q25) and rearrangement in the FCGR2B region has also been identified. |
| Abnormal Protein | None |
| Oncogenesis | Contribution of FCGR2B deregulation to lymphoma development or progression is currently not known. |
| External links |
| Bibliography |
| Fc receptor biology. |
| Daˆ´ron M |
| Annual review of immunology. 1997 ; 15 : 203-234. |
| PMID 9143687 |
| The IgG Fc receptor, FcgammaRIIB, is a target for deregulation by chromosomal translocation in malignant lymphoma. |
| Callanan MB, Le Baccon P, Mossuz P, Duley S, Bastard C, Hamoudi R, Dyer MJ, Klobeck G, Rimokh R, Sotto JJ, Leroux D |
| Proceedings of the National Academy of Sciences of the United States of America. 2000 ; 97 (1) : 309-314. |
| PMID 10618414 |
| Immune inhibitory receptors. |
| Ravetch JV, Lanier LL |
| Science (New York, N.Y.). 2000 ; 290 (5489) : 84-89. |
| PMID 11021804 |
| Deregulation of FCGR2B expression by 1q21 rearrangements in follicular lymphomas. |
| Chen W, Palanisamy N, Schmidt H, Teruya-Feldstein J, Jhanwar SC, Zelenetz AD, Houldsworth J, Chaganti RS |
| Oncogene. 2001 ; 20 (52) : 7686-7693. |
| PMID 11753646 |
| REVIEW articles | automatic search in PubMed |
| Last year publications | automatic search in PubMed |
| Contributor(s) |
| Written | 02-2002 | Mary Callanan, Dominique Leroux |
| Citation |
| This paper should be referenced as such : |
| Callanan M, Leroux D . FCGR2B. Atlas Genet Cytogenet Oncol Haematol. February 2002 . URL : http://AtlasGeneticsOncology.org/Genes/FCGR2BID397.html |
| © Atlas of Genetics and Cytogenetics in Oncology and Haematology | indexed on : Thu Jul 15 14:43:50 CEST 2010 |
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