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A role for the human DNA repair enzyme HAP1 in cellular protection against DNA damaging agents and hypoxic stress.
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MedLine Citation:
PMID:  7800476     Owner:  NLM     Status:  MEDLINE    
The HAP1 protein (also known as APE/Ref-1) is a bifunctional human nuclear enzyme required for repair of apurinic/apyrimidinic sites in DNA and reactivation of oxidized proto-oncogene products. To gain insight into the biological roles of HAP1, the effect of expressing antisense HAP1 RNA in HeLa cells was determined. The constructs for antisense RNA expression consisted of either a full-length HAP1 cDNA or a genomic DNA fragment cloned downstream of the CMV promoter in pcDNAneo. Stable HeLa cell transfectants expressing HAP1 antisense RNA were found to express greatly reduced levels of the HAP1 protein compared to equivalent sense orientation and vector-only control transfectants. The antisense HAP1 transfectants exhibited a normal growth rate, cell morphology and plating efficiency, but were hypersensitive to killing by a wide range of DNA damaging agents, including methyl methanesulphonate, hydrogen peroxide, menadione, and paraquat. However, survival after UV irradiation was unchanged. The antisense transfectants were strikingly sensitive to changes in oxygen tension, exhibiting increased killing compared to controls following exposure to both hypoxia (1% oxygen) and hyperoxia (100% oxygen). Consistent with a requirement for HAP1 in protection against hypoxic stress, expression of the HAP1 protein was found to be induced in a time-dependent manner in human cells during growth under 1% oxygen. The possible involvement of a depletion of cellular glutathione being linked to the hypoxic stress-sensitive phenotype of the antisense HAP1 transfectants came from the finding that they also exhibited hypersensitivity to buthionine sulphoximine, an inhibitor of glutathione biosynthesis. We conclude that the HAP1 protein is a key factor in cellular protection against a wide variety of cellular stresses, including DNA damage and a change in oxygen tension.
L J Walker; R B Craig; A L Harris; I D Hickson
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Nucleic acids research     Volume:  22     ISSN:  0305-1048     ISO Abbreviation:  Nucleic Acids Res.     Publication Date:  1994 Nov 
Date Detail:
Created Date:  1995-01-20     Completed Date:  1995-01-20     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0411011     Medline TA:  Nucleic Acids Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  4884-9     Citation Subset:  IM    
Imperial Cancer Research Fund Laboratories, University of Oxford, John Radcliffe Hospital, UK.
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MeSH Terms
Buthionine Sulfoximine
Carbon-Oxygen Lyases*
Cell Hypoxia
Cell Survival
DNA / drug effects*,  radiation effects
DNA-(Apurinic or Apyrimidinic Site) Lyase*
Gene Expression Regulation, Enzymologic
Glutathione / metabolism
Hela Cells
Methionine Sulfoximine / analogs & derivatives,  pharmacology
Mutagens / pharmacology*
Nuclear Proteins / biosynthesis,  physiology*
Oxidative Stress*
RNA, Antisense / biosynthesis
Ultraviolet Rays
Reg. No./Substance:
0/Mutagens; 0/Nuclear Proteins; 0/RNA, Antisense; 1982-67-8/Methionine Sulfoximine; 5072-26-4/Buthionine Sulfoximine; 70-18-8/Glutathione; 9007-49-2/DNA; EC 4.2.-/Carbon-Oxygen Lyases; EC protein, human; EC or Apyrimidinic Site) Lyase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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Journal Information
Journal ID (nlm-ta): Nucleic Acids Res
ISSN: 0305-1048
ISSN: 1362-4962
Article Information
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Print publication date: Day: 25 Month: 11 Year: 1994
Volume: 22 Issue: 23
First Page: 4884 Last Page: 4889
ID: 523752
PubMed Id: 7800476

A role for the human DNA repair enzyme HAP1 in cellular protection against DNA damaging agents and hypoxic stress.
L J Walker
R B Craig
A L Harris
I D Hickson
Imperial Cancer Research Fund Laboratories, University of Oxford, John Radcliffe Hospital, UK.

Article Categories:
  • Research Article

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