Document Detail

Decreased origin usage and initiation of DNA replication in haploinsufficient HCT116 Ku80+/- cells.
MedLine Citation:
PMID:  16014376     Owner:  NLM     Status:  MEDLINE    
One of the functions of the abundant heterodimeric nuclear protein, Ku (Ku70/Ku80), is its involvement in the initiation of DNA replication through its ability to bind to chromosomal replication origins in a sequence-specific and cell cycle dependent manner. Here, using HCT116 Ku80+/- cells, the effect of Ku80 deficiency on cell cycle progression and origin activation was examined. Western blot analyses revealed a 75% and 36% decrease in the nuclear expression of Ku80 and Ku70, respectively. This was concomitant with a 33% and 40% decrease in chromatin binding of both proteins, respectively. Cell cycle analysis of asynchronous and late G1 synchronized Ku80+/- cells revealed a prolonged G1 phase. Furthermore, these Ku-deficient cells had a 4.5-, 3.4- and 4.3-fold decrease in nascent strand DNA abundance at the lamin B2, beta-globin and c-myc replication origins, respectively. Chromatin immunoprecipitation (ChIP) assays showed that the association of Ku80 with the lamin B2, beta-globin and c-myc origins was decreased by 1.5-, 2.3- and 2.5-fold, respectively, whereas that of Ku70 was similarly decreased (by 2.1-, 1.5- and 1.7-fold, respectively) in Ku80+/- cells. The results indicate that a deficiency of Ku80 resulted in a prolonged G1 phase, as well as decreased Ku binding to and activation of origins of DNA replication.
Sahar Sibani; Gerald B Price; Maria Zannis-Hadjopoulos
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-07-12
Journal Detail:
Title:  Journal of cell science     Volume:  118     ISSN:  0021-9533     ISO Abbreviation:  J. Cell. Sci.     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-08-04     Completed Date:  2005-12-15     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0052457     Medline TA:  J Cell Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  3247-61     Citation Subset:  IM    
McGill Cancer Center, McGill University, Montreal, Quebec H3G 1Y6, Canada.
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MeSH Terms
Antigens, Nuclear / genetics,  metabolism*
Cell Cycle / physiology
Cell Line
Cell Nucleus / metabolism
Chromatin / metabolism
DNA Replication*
DNA-Binding Proteins / deficiency*,  genetics,  metabolism*
G1 Phase
Mice, Knockout
Protein Binding
Reg. No./Substance:
0/Antigens, Nuclear; 0/Chromatin; 0/DNA-Binding Proteins; 0/Ku autoantigen

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