Levels of uracil DNA glycosylase and AP endonuclease in murine B- and T-lymphocytes do not change with age.
Two DNA repair enzyme activities, uracil DNA glycosylase and AP endonuclease, were measured in extracts of T- and B-lymphocytes isolated from mice ranging in age from 3 to 24 months. T- and B-lymphocytes had roughly equal levels of AP endonuclease which did not change appreciably with age. T-lymphocytes had roughly twice as high a level of uracil DNA glycosylase as B-lymphocytes; these levels were not affected by age either. This constancy with age contrasts dramatically with increases in both enzymes--roughly 3-fold on a protein basis or 50-fold on a per cell basis--in a transformed line (MPC-11) derived from a carcinogen-induced lymphocytoma. These results are similar to those obtained with cultured murine fibroblasts, wherein a relative constancy was noted with passage of non-transformed cells, followed by dramatic changes upon transformation (La Belle, M & Linn, S, Mutat res 132 (1984) 51). Hence these enzyme assays do not support the notion of a drop in base excision DNA repair capacity as being a causative factor in aging, but suggest instead that DNA repair properties might differ dramatically in transformed vs non-transformed cells.
J
J
Barnard
M
M
La Belle
S
S
Linn
D000375:Aging; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000201:enzymology*; D002478:Cells, Cultured; D045647:DNA Glycosylases; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D013154:Spleen / Q000166:cytology / Q000254:growth & development; D013601:T-Lymphocytes / Q000166:cytology / Q000201:enzymology*; D051981:Uracil-DNA Glycosidase
D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D051981:Uracil-DNA Glycosidase; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase