Progress in high-throughput assays of MGMT and APE1 activities in cell extracts.
Cast your vote
You can rate an item by clicking the amount of stars they wish to award to this item.
When enough users have cast their vote on this item, the average rating will also be shown.
Your vote was cast
Thank you for your feedback
Thank you for your feedback
MetadataShow full item record
AbstractDNA repair activity is of interest as a potential biomarker of individual susceptibility to genotoxic agents. In view of the current trend for exploitation of large cohorts in molecular epidemiology projects, there is a pressing need for the development of phenotypic DNA repair assays that are high-throughput, very sensitive, inexpensive and reliable. Towards this goal we have developed and validated two phenotypic assays for the measurement of two DNA repair enzymes in cell extracts: (1) O(6)-methylguanine-DNA-methyltransferase (MGMT), which repairs the O(6)-alkylguanine-type of adducts induced in DNA by alkylating genotoxins; and (2) apurinic/apyrimidinic endonuclease 1 (APE 1), which participates in base excision repair (BER) by causing a rate-limiting DNA strand cleavage 5' to the abasic sites. The MGMT assay makes use of the fact that: (a) the enzyme works by irreversibly transferring the alkyl group from the O(6) position of guanine to a cystein residue in its active site and thereby becomes inactivated and (b) that the free base O(6)-benzylguanine (BG) is a very good substrate for MGMT. In the new assay, cell extracts are incubated with BG tagged with biotin and the resulting MGMT-BG-biotin complex is immobilized on anti-MGMT-coated microtiter plates, followed by quantitation using streptavidin-conjugated alkaline phosphatase and a chemiluminescence-producing substrate. A one-step/one-tube phenotypic assay for APE1 activity has been developed based on the use of a fluorescent molecular beacon (partially self-complementary oligonucleotide with a hairpin-loop structure carrying a fluorophore and a quencher at each end). It also contains a single tetrahydrofuran residue (THF) which is recognized and cleaved by APE1, and the subsequently formed single-stranded oligomer becomes a fluorescence signal emitter. Both assays are highly sensitive, require very small amounts of protein extracts, are relatively inexpensive and can be easily automated. They have been extensively validated and are being used in the context of large-scale molecular epidemiology studies.
CitationMutat. Res. 2012, 736 (1-2):25-32
SponsorsThis work was partly supported by the ECNIS (Environmental Cancer, Nutrition and Individual Susceptibility) Network of Excellence of the European Union (contract no. 513943).
- BER, MGMT, and MMR in defense against alkylation-induced genotoxicity and apoptosis.
- Authors: Kaina B, Ochs K, Grösch S, Fritz G, Lips J, Tomicic M, Dunkern T, Christmann M
- Issue date: 2001
- MGMT: key node in the battle against genotoxicity, carcinogenicity and apoptosis induced by alkylating agents.
- Authors: Kaina B, Christmann M, Naumann S, Roos WP
- Issue date: 2007 Aug 1
- Inhibition of the human apurinic/apyrimidinic endonuclease (APE1) repair activity and sensitization of breast cancer cells to DNA alkylating agents with lucanthone.
- Authors: Luo M, Kelley MR
- Issue date: 2004 Jul-Aug
- Specific recognition of O6-methylguanine in DNA by active site mutants of human O6-methylguanine-DNA methyltransferase.
- Authors: Hazra TK, Roy R, Biswas T, Grabowski DT, Pegg AE, Mitra S
- Issue date: 1997 May 13
- Probing conformational changes in Ape1 during the progression of base excision repair.
- Authors: Yu E, Gaucher SP, Hadi MZ
- Issue date: 2010 May 11