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XRCC6 (X-ray repair complementing defective repair in Chinese hamster cells 6)

Identity

Other namesCTC75
CTCBF
G22P1
KU70
ML8
TLAA
HGNC (Hugo) XRCC6
LocusID (NCBI) 2547
Location 22q13.2
Location_base_pair Starts at 42017295 and ends at 42060052 bp from pter ( according to hg19-Feb_2009)  [Mapping]

DNA/RNA

Description The KU70 gene is composed of 13 exons.
Transcription 2156 bp mRNA.

Protein

Description The Ku70 protein is 609 amino acid long and its molecular weight is 69.8 kDa. It is composed of 3 domains: an amino (N) amino-terminal alpha/beta domain, a central beta-barrel domain and a helical C-terminal arm (Rivera-Calzada et al., 2007). The C-terminal region consists of a 5 kDa SAP domain (Ku70-SAP) which involved in DNA binding during NHEJ reaction.
 
Expression Ku70 is ubiquitously expressed. Changes in Ku70 expression correlated to a pathological state.
Localisation Ku was originally reported to be a nuclear protein, consistent with its functions as a subunit of DNA-PK involved in DNA double strand breaks repair. However, several studies have revealed the cytoplasmic or cell surface localization of Ku proteins in various cell types (Prabhakar et al., 1990). Recently, it has been demonstrated that the shift from the nucleus to the cytoplasm of the Ku70/Ku80 proteins in tumor cells could represents a mechanism to inhibit cell death through the Ku70-Bax-sCLU interactions, giving rise to a new chemoresistant clone with a more aggressive phenotype.
Function Ku is a heterodimeric protein composed of two subunits with molecular weight of 70 and 86 kDa. Ku forms a complex with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to form the full DNA-dependent protein kinase, DNA-PK, consisting of 470 kDa and required for the non-homologous end joining (NHEJ) pathway of DNA repair. The Ku heterodimer binds the ends of various types of DNA discontinuity, and is involved in the repair of DNA breaks caused by an incorrect DNA replication, V(D)J recombination, physiological oxidations, ionizing irradiation, and some chemotherapeutic drug effects (Featherstone and Jackson, 1999). The principal role of Ku proteins is to take care of the homeostasis of the genome being involved in telomere maintenance, specific gene transcription, DNA replication, cell-cycle regulation and regulation of apoptosis induction. Ku70 has been shown to bind to the pro-apoptotic protein BAX in the cytoplasm in normal, undamaged cell. After DNA damage inducing DNA double-strand breaks repair (UV treatment, ionizing radiation, etc.) Ku70 allows the translocation of Bax to the mitochondria leading to the release of death-promoting factors, such as cytochrome c, in the cytoplasmic compartment. In normal cells, after an irreversible cell damage, nCLU cooperates with Ku70 to induce apoptotic death, activating the translocation of Bax to mitochondria whereas the sCLU protein stabilizes the Ku70-Bax interaction in the cytoplasm acting as cytoprotectant. The Ku70-Bax-sCLU interaction in the cytoplasm seems to play an important role in cell survival pathways and in cell death escape, that in pathological condition could lead to the survival of the aberrant cell clone. Overall, the dynamic interactions among CLU, Ku70, and Bax seems to have an important role in both tumor insurgence and its progression (Pucci et al., 2009a; Pucci et al., 2009b).
 
  Ku70/80-CLU-Bax interactions. (A) Bax is localized inactive in the cytoplasm in normal, undamaged cell interacting with the Ku70 protein C-terminus. sCLU stabilizes the Ku70-Bax interaction in the cytoplasm acting as cytoprotectant. (B) After DNA damage inducing DNA double-strand breaks repair (UV treatment, ionizing radiation, etc.) Ku70 allows the translocation of Bax to the mitochondria inducing apoptosis (Mazzarelli et al., 2009).

Implicated in

Entity Colon cancer
Note The colon cancer expression and the localization of Ku70 and Ku80 are related to tumor progression in colon cancer. DNA repair is inhibited in high infiltrative colon carcinoma by Ku80 loss and Ku70 cell compartment shift (from the nucleus to the cytoplasm).
Moreover in colorectal carcinoma was demonstrated a very important role of Ku70 expression, localization, and physical interaction with CLU and Bax. In fact the Ku70-CLU-Bax colocalization in the cytoplasm and an increase in Ku70-CLU-Bax binding were observed in highly aggressive human colon cancer (Pucci et al., 2004; Pucci et al., 2009c), confirming that these interactions regulate the Bax-dependent cell death.
 
Tumor-specific modulation of Ku70/80 in human colon cancer. Ku70 staining was strongly positive in the nuclei of normal mucosa. In node-negative carcinomas (pT3N0) Ku70 expression slightly decreased and it localized mainly in the nucleus. In node-positive carcinomas (pT3N1) Ku70 staining was distributed mainly in cytoplasm. The expression of Ku86 was positive in the nuclei of control tissues (normal mucosa). Nuclear Ku86 expression was strongly decreased in node-negative tumors (pT3N0). No staining for Ku86 was found in the nucleus or in the cytoplasm of node-positive carcinomas (pT3N1).
 
Ku70-Bax-CLU pathological interaction. Apoptosis escaping. The shift of clusterin forms production, the loss of Ku80, and the cytoplasmic relocalization of Ku70 are related to cell death inhibition and cancer progression.
  
Entity Breast cancer
Note Experimental data further reported an inactivation of Ku DNA-binding activity, essential for genomic stability in breast and in bladder carcinomas. A dysfunction of this protective activity let the aberrant cell clone growing. In highly infiltrative and metastatic tumors of the breast and bladder, the impaired DNA-repair activity is due to the loss of Ku86 (Pucci et al., 2001) and to the Ku70 shifting from the nucleus to the cytoplasm. The shift from the nucleus to the cytoplasm of the Ku70/80 proteins in tumor cells could represents a mechanism to inhibit cell death through the cooperative interaction with sCLU, giving rise to a new chemoresistant clone with a more aggressive phenotype.
  

External links

Nomenclature
HGNC (Hugo)XRCC6   4055
Cards
AtlasXRCC6ID246ch22q13
Entrez_Gene (NCBI)XRCC6  2547  X-ray repair complementing defective repair in Chinese hamster cells 6
GeneCards (Weizmann)XRCC6
Ensembl (Hinxton)ENSG00000196419 [Gene_View]  chr22:42017295-42060052 [Contig_View]  XRCC6 [Vega]
AceView (NCBI)XRCC6
Genatlas (Paris)XRCC6
WikiGenes2547
SOURCE (Princeton)NM_001469
Genomic and cartography
GoldenPath (UCSC)XRCC6  -  22q13.2   chr22:42017295-42060052 +  22q13.2   [Description]    (hg19-Feb_2009)
EnsemblXRCC6 - 22q13.2 [CytoView]
Mapping of homologs : NCBIXRCC6 [Mapview]
OMIM152690   
Gene and transcription
Genbank (Entrez)AK055786 AK293439 AK304580 AK315618 BC001583
RefSeq transcript (Entrez)NM_001469
RefSeq genomic (Entrez)AC_000154 NC_000022 NC_018933 NT_011520 NW_001838745 NW_004929430
Consensus coding sequences : CCDS (NCBI)XRCC6
Cluster EST : UnigeneHs.292493 [ NCBI ]
CGAP (NCI)Hs.292493
Alternative Splicing : Fast-db (Paris)GSHG0020063
Alternative Splicing GalleryENSG00000196419
Gene ExpressionXRCC6 [ NCBI-GEO ]     XRCC6 [ SEEK ]   XRCC6 [ MEM ]
Protein : pattern, domain, 3D structure
UniProt/SwissProtP12956 (Uniprot)
NextProtP12956  [Medical]
With graphics : InterProP12956
Splice isoforms : SwissVarP12956 (Swissvar)
Catalytic activity : Enzyme3.6.4.- [ Enzyme-Expasy ]   3.6.4.-3.6.4.- [ IntEnz-EBI ]   3.6.4.- [ BRENDA ]   3.6.4.- [ KEGG ]   
Domaine pattern : Prosite (Expaxy)SAP (PS50800)   
Domains : Interpro (EBI)Ku70    Ku70/Ku80_beta-barrel_dom    Ku70_bridge/pillars_dom    Ku_C    Ku_N    SAP_dom    SPOC_like_C_dom    VWF_A   
Related proteins : CluSTrP12956
Domain families : Pfam (Sanger)Ku (PF02735)    Ku_C (PF03730)    Ku_N (PF03731)    SAP (PF02037)   
Domain families : Pfam (NCBI)pfam02735    pfam03730    pfam03731    pfam02037   
Domain families : Smart (EMBL)Ku78 (SM00559)  SAP (SM00513)  
DMDM Disease mutations2547
Blocks (Seattle)P12956
PDB (SRS)1JEQ    1JEY    1JJR    3RZX   
PDB (PDBSum)1JEQ    1JEY    1JJR    3RZX   
PDB (IMB)1JEQ    1JEY    1JJR    3RZX   
PDB (RSDB)1JEQ    1JEY    1JJR    3RZX   
Human Protein AtlasENSG00000196419
Peptide AtlasP12956
HPRD01071
IPIIPI00644712   IPI00889791   IPI00893179   IPI00893062   
Protein Interaction databases
DIP (DOE-UCLA)P12956
IntAct (EBI)P12956
FunCoupENSG00000196419
BioGRIDXRCC6
InParanoidP12956
Interologous Interaction database P12956
IntegromeDBXRCC6
STRING (EMBL)XRCC6
Ontologies - Pathways
Ontology : AmiGOtelomere maintenance  nuclear telomere cap complex  DNA binding  damaged DNA binding  double-stranded DNA binding  double-stranded telomeric DNA binding  ATP-dependent DNA helicase activity  protein binding  ATP binding  nucleus  nucleoplasm  transcription factor complex  cytosol  DNA ligation  DNA repair  double-strand break repair  double-strand break repair via nonhomologous end joining  double-strand break repair via nonhomologous end joining  transcription, DNA-templated  protein C-terminus binding  response to ionizing radiation  membrane  viral process  positive regulation of type I interferon production  V(D)J recombination  Ku70:Ku80 complex  transcription regulatory region DNA binding  innate immune response  negative regulation of transcription, DNA-dependent  positive regulation of transcription, DNA-dependent  positive regulation of transcription, DNA-dependent  positive regulation of transcription from RNA polymerase II promoter  positive regulation of neurogenesis  5'-deoxyribose-5-phosphate lyase activity  nonhomologous end joining complex  establishment of integrated proviral latency  
Ontology : EGO-EBItelomere maintenance  nuclear telomere cap complex  DNA binding  damaged DNA binding  double-stranded DNA binding  double-stranded telomeric DNA binding  ATP-dependent DNA helicase activity  protein binding  ATP binding  nucleus  nucleoplasm  transcription factor complex  cytosol  DNA ligation  DNA repair  double-strand break repair  double-strand break repair via nonhomologous end joining  double-strand break repair via nonhomologous end joining  transcription, DNA-templated  protein C-terminus binding  response to ionizing radiation  membrane  viral process  positive regulation of type I interferon production  V(D)J recombination  Ku70:Ku80 complex  transcription regulatory region DNA binding  innate immune response  negative regulation of transcription, DNA-dependent  positive regulation of transcription, DNA-dependent  positive regulation of transcription, DNA-dependent  positive regulation of transcription from RNA polymerase II promoter  positive regulation of neurogenesis  5'-deoxyribose-5-phosphate lyase activity  nonhomologous end joining complex  establishment of integrated proviral latency  
Pathways : BIOCARTATelomeres, Telomerase, Cellular Aging, and Immortality [Genes]   
Pathways : KEGGNon-homologous end-joining   
REACTOMEXRCC6
Protein Interaction DatabaseXRCC6
Wikipedia pathwaysXRCC6
Gene fusion - rearrangments
Polymorphisms : SNP, mutations, diseases
SNP Single Nucleotide Polymorphism (NCBI)XRCC6
SNP (GeneSNP Utah)XRCC6
SNP : HGBaseXRCC6
Genetic variants : HAPMAPXRCC6
1000_GenomesXRCC6 
ICGC programENSG00000196419 
Somatic Mutations in Cancer : COSMICXRCC6 
CONAN: Copy Number AnalysisXRCC6 
Mutations and Diseases : HGMDXRCC6
OMIM152690   
GENETestsXRCC6
Disease Genetic AssociationXRCC6
Huge Navigator XRCC6 [HugePedia]  XRCC6 [HugeCancerGEM]
Genomic VariantsXRCC6  XRCC6 [DGVbeta]
Exome VariantXRCC6
dbVarXRCC6
ClinVarXRCC6
snp3D : Map Gene to Disease2547
General knowledge
Homologs : HomoloGeneXRCC6
Homology/Alignments : Family Browser (UCSC)XRCC6
Phylogenetic Trees/Animal Genes : TreeFamXRCC6
Chemical/Protein Interactions : CTD2547
Chemical/Pharm GKB GenePA28467
Clinical trialXRCC6
Cancer Resource (Charite)ENSG00000196419
Other databases
Probes
Litterature
PubMed324 Pubmed reference(s) in Entrez
CoreMineXRCC6
iHOPXRCC6

Bibliography

Cell surface expression of the 70-kD component of Ku, a DNA-binding nuclear autoantigen.
Prabhakar BS, Allaway GP, Srinivasappa J, Notkins AL.
J Clin Invest. 1990 Oct;86(4):1301-5.
PMID 2212014
 
Ku, a DNA repair protein with multiple cellular functions?
Featherstone C, Jackson SP.
Mutat Res. 1999 May 14;434(1):3-15. (REVIEW)
PMID 10377944
 
Tumor specific modulation of KU70/80 DNA binding activity in breast and bladder human tumor biopsies.
Pucci S, Mazzarelli P, Rabitti C, Giai M, Gallucci M, Flammia G, Alcini A, Altomare V, Fazio VM.
Oncogene. 2001 Feb 8;20(6):739-47.
PMID 11314007
 
Modulation of different clusterin isoforms in human colon tumorigenesis.
Pucci S, Bonanno E, Pichiorri F, Angeloni C, Spagnoli LG.
Oncogene. 2004 Mar 25;23(13):2298-304.
PMID 14755245
 
Structural model of full-length human Ku70-Ku80 heterodimer and its recognition of DNA and DNA-PKcs.
Rivera-Calzada A, Spagnolo L, Pearl LH, Llorca O.
EMBO Rep. 2007 Jan;8(1):56-62. Epub 2006 Dec 8.
PMID 17159921
 
CLU and colon cancer. The dual face of CLU: from normal to malignant phenotype.
Mazzarelli P, Pucci S, Spagnoli LG.
Adv Cancer Res. 2009;105:45-61. (REVIEW)
PMID 19879422
 
Clusterin in stool: a new biomarker for colon cancer screening?
Pucci S, Bonanno E, Sesti F, Mazzarelli P, Mauriello A, Ricci F, Zoccai GB, Rulli F, Galata G, Spagnoli LG.
Am J Gastroenterol. 2009a Nov;104(11):2807-15. Epub 2009 Jul 21.
PMID 19623170
 
CLU "in and out": looking for a link.
Pucci S, Mazzarelli P, Nucci C, Ricci F, Spagnoli LG.
Adv Cancer Res. 2009c;105:93-113. (REVIEW)
PMID 19879425
 
Interleukin-6 affects cell death escaping mechanisms acting on Bax-Ku70-Clusterin interactions in human colon cancer progression.
Pucci S, Mazzarelli P, Sesti F, Boothman DA, Spagnoli LG.
Cell Cycle. 2009b Feb 1;8(3):473-81. Epub 2009 Feb 18.
PMID 19177010
 
REVIEW articlesautomatic search in PubMed
Last year publicationsautomatic search in PubMed

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Contributor(s)

Written06-2010Sabina Pucci, Maria Josè Zonetti
Lab of Molecular Pathology, Dept of Biopathology, University of Rome "Tor Vergata", Via Montpellier, 00133 Rome, Italy

Citation

This paper should be referenced as such :
Pucci S, Zonetti MJ . XRCC6 (X-ray repair complementing defective repair in Chinese hamster cells 6). Atlas Genet Cytogenet Oncol Haematol. June 2010 .
URL : http://AtlasGeneticsOncology.org/Genes/XRCC6ID246ch22q13.html

The various updated versions of this paper are referenced and archived by INIST as such :
http://documents.irevues.inist.fr/bitstream/2042/44987/1/06-2010-XRCC6ID246ch22q13.pdf   [ Bibliographic record ]

© Atlas of Genetics and Cytogenetics in Oncology and Haematology
indexed on : Fri Apr 18 17:22:52 CEST 2014

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