Nibrin

Nibrin
Identifiers
Symbols	NBN; AT-V1; AT-V2; ATV; FLJ10155; MGC87362; NBS; NBS1; P95
External IDs	OMIM: 602667 MGI: 1351625 HomoloGene: 1858 GeneCards: NBN Gene
Gene Ontology Molecular function • damaged DNA binding • ATP-dependent DNA helicase activity • protein binding • transcription factor binding • protein N-terminus binding Cellular component • nuclear chromosome, telomeric region • intracellular • nucleus • nucleoplasm • nucleoplasm • replication fork • chromosome • nucleolus • Mre11 complex • nuclear inclusion body Biological process • DNA damage checkpoint • telomere maintenance • double-strand break repair via homologous recombination • in utero embryonic development • blastocyst growth • DNA repair • double-strand break repair • double-strand break repair • cell cycle • cell cycle arrest • mitotic cell cycle G2/M transition DNA damage checkpoint • meiosis • positive regulation of cell proliferation • regulation of DNA-dependent DNA replication initiation • DNA damage response, signal transduction by p53 class mediator • mitotic cell cycle G1/S transition checkpoint • positive regulation of protein autophosphorylation • DNA duplex unwinding • positive regulation of kinase activity • response to drug • isotype switching • negative regulation of neuron differentiation • regulation of fibroblast proliferation • neuromuscular process controlling balance Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	4683	27354
Ensembl	ENSG00000104320	ENSMUSG00000028224
UniProt	O60934	Q9R207
RefSeq (mRNA)	NM_002485.4	NM_013752.3
RefSeq (protein)	NP_002476.2	NP_038780.3
Location (UCSC)	Chr 8: 90.95 – 91.02 Mb	Chr 4: 15.89 – 15.92 Mb
PubMed search	[1]	[2]

Nibrin, also known as NBN, is a protein which in humans is encoded by the NBN gene.^[1][2][3]

Function

Nibrin is a protein associated with the repair of double strand breaks(DSBs) which pose serious damage to a genome. It is a 754 amino acid protein identified as a member of the NBS1/hMre11/RAD50(N/M/R, more commonly referred to as MRN) double strand DNA break repair complex.^[4] This complex recognizes DNA damage and rapidly relocates to DSB sites and forms nuclear foci. It also has a role in regulation of N/M/R (MRN) protein complex activity which includes end-processing of both physiological and mutagenic DNA double strand breaks (DSBs).^[5]

Cellular Response to DSBs

Cellular response is performed by damage sensors, effectors of lesion repair and signal transduction. The central role is carried out by ataxia-telangiectasia mutated(ATM) by activating the DSB signaling cascade, phosphorylating downstream substrates such as histone H2AX and NBS1. NBS1 relocates to DSB sites by interaction of FHA/BRCT domains with phosphorylated histone H2AX. Once it interacts with nibrin c-terminal hMre11-binding domain, hMre11 and hRAD50 relocate from the cytoplasm to the nucleus then to sites of DSBs. They finally relocate to N/M/R where they form the foci at the site of damage.^[6]

Double Strand Breaks (DSBs)

DSBs occur during V(D)J recombination during early B and T cell development. This is at the point when the cells of the immune system are developing and the DSBs effect the development of lymphoid cells. DSBs also occur in immunoglobulin class switch in mature B cells.^[5] More frequently, however, DSBs are caused by mutagenic agents like radiomimetic chemicals and ionizing radiation(IR).

DSB Mutations

As mentioned, DSBs cause extreme damage to DNA. One such mutation is associated with Nijmegen breakage syndrome (NBS), a radiation hyper-sensitive disease.^[7] It is a rare inherited autosomal recessive condition of chrosomal instability. It has been linked to mutations within exons 6-10 in the NBS1 gene which results in a truncated protein.^[5] Characteristics of NBS include microcephaly, cranial characteristics, growth retardation, impaired sexual maturation, immunodeficiency/recurring infections and a predisposition to cancer. This predisposition to cancer may be linked to the DSBs occurring at the development of lymphoid cells.

Interactions

Nibrin has been shown to interact with MRE11A,^{[8][9][10][11][12]} Ataxia telangiectasia mutated,^[13][8] Rad50,^{[8][9][10][12]} H2AFX,^[14] TERF2^[15] and BRCA1.^[8][16][17]

References

1. ^ "Entrez Gene: Nibrin". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=4683. 
2. ^ Varon R, Vissinga C, Platzer M, Cerosaletti KM, Chrzanowska KH, Saar K, Beckmann G, Seemanová E, Cooper PR, Nowak NJ, Stumm M, Weemaes CM, Gatti RA, Wilson RK, Digweed M, Rosenthal A, Sperling K, Concannon P, Reis A (May 1998). "Nibrin, a novel DNA double-strand break repair protein, is mutated in Nijmegen breakage syndrome". Cell 93 (3): 467–76. doi:10.1016/S0092-8674(00)81174-5. PMID 9590180. 
3. ^ Carney JP, Maser RS, Olivares H, Davis EM, Le Beau M, Yates JR 3rd, Hays L, Morgan WF, Petrini JH (May 1998). "The hMre11/hRad50 protein complex and Nijmegen breakage syndrome: linkage of double-strand break repair to the cellular DNA damage response". Cell 93 (3): 477–86. doi:10.1016/S0092-8674(00)81175-7. PMID 9590181. 
4. ^ "Atlas of Genetics and Cytogenetics in Oncology and Haematology - NBS1". http://atlasgeneticsoncology.org//Genes/NBS1ID160.html. Retrieved 2008-02-12. 
5. ^ ^{a b c} "eMedicine - Nijmegen Breakage Syndrome". http://www.emedicine.com/DERM/topic725.htm. Retrieved 2008-02-12. 
6. ^ Molecular Biology
7. ^ Kobayashi J (2004). "Molecular mechanism of the recruitment of NBS1/hMRE11/hRAD50 complex to DNA double-strand breaks: NBS1 binds to gamma-H2AX through FHA/BRCT domain". J. Radiat. Res. 45 (4): 473–8. doi:10.1269/jrr.45.473. PMID 15635255. 
8. ^ ^{a b c d} Wang, Y; Cortez D, Yazdi P, Neff N, Elledge S J, Qin J (Apr. 2000). "BASC, a super complex of BRCA1-associated proteins involved in the recognition and repair of aberrant DNA structures". Genes Dev. (UNITED STATES) 14 (8): 927–39. ISSN 0890-9369. PMC 316544. PMID 10783165. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=316544. 
9. ^ ^{a b} Cerosaletti, Karen M; Concannon Patrick (Jun. 2003). "Nibrin forkhead-associated domain and breast cancer C-terminal domain are both required for nuclear focus formation and phosphorylation". J. Biol. Chem. (United States) 278 (24): 21944–51. doi:10.1074/jbc.M211689200. ISSN 0021-9258. PMID 12679336. 
10. ^ ^{a b} Trujillo, K M; Yuan S S, Lee E Y, Sung P (Aug. 1998). "Nuclease activities in a complex of human recombination and DNA repair factors Rad50, Mre11, and p95". J. Biol. Chem. (UNITED STATES) 273 (34): 21447–50. doi:10.1074/jbc.273.34.21447. ISSN 0021-9258. PMID 9705271. 
11. ^ Matsuzaki, Kenichiro; Shinohara Akira, Shinohara Miki (May. 2008). "Forkhead-associated domain of yeast Xrs2, a homolog of human Nbs1, promotes nonhomologous end joining through interaction with a ligase IV partner protein, Lif1". Genetics (United States) 179 (1): 213–25. doi:10.1534/genetics.107.079236. ISSN 0016-6731. PMC 2390601. PMID 18458108. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2390601. 
12. ^ ^{a b} Desai-Mehta, A; Cerosaletti K M, Concannon P (Mar. 2001). "Distinct functional domains of nibrin mediate Mre11 binding, focus formation, and nuclear localization". Mol. Cell. Biol. (United States) 21 (6): 2184–91. doi:10.1128/MCB.21.6.2184-2191.2001. ISSN 0270-7306. PMC 86852. PMID 11238951. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=86852. 
13. ^ Kim, S T; Lim D S, Canman C E, Kastan M B (Dec. 1999). "Substrate specificities and identification of putative substrates of ATM kinase family members". J. Biol. Chem. (UNITED STATES) 274 (53): 37538–43. doi:10.1074/jbc.274.53.37538. ISSN 0021-9258. PMID 10608806. 
14. ^ Kobayashi, Junya; Tauchi Hiroshi, Sakamoto Shuichi, Nakamura Asako, Morishima Ken-ichi, Matsuura Shinya, Kobayashi Toshiko, Tamai Katsuyuki, Tanimoto Keiji, Komatsu Kenshi (Oct. 2002). "NBS1 localizes to gamma-H2AX foci through interaction with the FHA/BRCT domain". Curr. Biol. (England) 12 (21): 1846–51. doi:10.1016/S0960-9822(02)01259-9. ISSN 0960-9822. PMID 12419185. 
15. ^ Zhu, X D; Küster B, Mann M, Petrini J H, de Lange T (Jul. 2000). "Cell-cycle-regulated association of RAD50/MRE11/NBS1 with TRF2 and human telomeres". Nat. Genet. (UNITED STATES) 25 (3): 347–52. doi:10.1038/77139. ISSN 1061-4036. PMID 10888888. 
16. ^ Chiba, N; Parvin J D (Oct. 2001). "Redistribution of BRCA1 among four different protein complexes following replication blockage". J. Biol. Chem. (United States) 276 (42): 38549–54. doi:10.1074/jbc.M105227200. ISSN 0021-9258. PMID 11504724. 
17. ^ Zhong, Q; Chen C F, Li S, Chen Y, Wang C C, Xiao J, Chen P L, Sharp Z D, Lee W H (Jul. 1999). "Association of BRCA1 with the hRad50-hMre11-p95 complex and the DNA damage response". Science (UNITED STATES) 285 (5428): 747–50. doi:10.1126/science.285.5428.747. ISSN 0036-8075. PMID 10426999. 

Further reading

• Kobayashi J, Antoccia A, Tauchi H, et al. (2005). "NBS1 and its functional role in the DNA damage response.". DNA Repair (Amst.) 3 (8–9): 855–61. doi:10.1016/j.dnarep.2004.03.023. PMID 15279770. 
• Digweed M, Sperling K (2005). "Nijmegen breakage syndrome: clinical manifestation of defective response to DNA double-strand breaks". DNA Repair (Amst.) 3 (8–9): 1207–17. doi:10.1016/j.dnarep.2004.03.004. PMID 15279809. 
• Matsuura S, Kobayashi J, Tauchi H, Komatsu K (2004). "Nijmegen breakage syndrome and DNA double strand break repair by NBS1 complex". Adv. Biophys. 38: 65–80. doi:10.1016/S0065-227X(04)80076-5. PMID 15493328. 
• Zhang Y, Zhou J, Lim CU (2006). "The role of NBS1 in DNA double strand break repair, telomere stability, and cell cycle checkpoint control". Cell Res. 16 (1): 45–54. doi:10.1038/sj.cr.7310007. PMID 16467875. 

External links

• GeneReviews/NCBI/NIH/UW entry on Nijmegen Breakage Syndrome
• MeSH nibrin+protein,+human