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Marginal vitamin B‐6 deficiency does not increase uracil concentration in lymphocyte DNA
Author(s) -
Hansen Christine M.,
Mashiyama Susan T.,
Roitman Esther,
Sarmiento Stella,
Leklem James E.,
Shultz Terry D.,
Ames Bruce N.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a346-a
Subject(s) - uracil , dna , chemistry , microbiology and biotechnology , biochemistry , biology
Folate deficiency increases dUMP/dTMP ratios and uracil misincorporation into DNA, which may increase cancer risk. Because vitamin B‐6 (B6) is a required cofactor for serine hydroxymethyltransferase, catalyzing the methylation of tetrahydrofolate (THF) to 5,10‐methylene THF, B6 deficiency may have similar consequences. Improvements made to our gas chromatography‐mass spectrometry based assay for quantifying uracil in DNA resulted in an approximately 10‐fold increase in signal strength over the previous method, and a 10‐fold lower detection limit (0.2 pg uracil). Five micrograms of DNA, the amount in about 1 mL of human blood, is sufficient for this assay. DNA‐uracil was measured in lymphocytes from 12 healthy young men and women who consumed a B6 restricted diet (0.7 mg B6/day, or half the RDA) for 28 days. No significant increases in DNA‐uracil concentration were found with marginal B6 deficiency. The average concentration of DNA‐uracil was found to be approximately 3,000 uracils per diploid lymphocyte, comparable to steady state levels of an oxidative adduct of DNA, 8‐oxoguanine. More severe and/or prolonged B6 deficiency may be necessary to detect significant changes in DNA‐uracil in humans. Support: NIH grants NCCAM K05 AT001323, R21 AT001918, NCMHD P60 MD00222, NFCR grant M2661 (BNA); R03 CA89722 (TDS)