title: Base excision repair is limited by different proteins in male germ cell nuclear extracts prepared from young and old mice.
abstract: The combined observations of elevated DNA repair gene expression, high uracil-DNA glycosylase-initiated base excision repair, and a low spontaneous mutant frequency for a lacI transgene in spermatogenic cells from young mice suggest that base excision repair activity is high in spermatogenic cell types. Notably, the spontaneous mutant frequency of the lacI transgene is greater in spermatogenic cells obtained from old mice, suggesting that germ line DNA repair activity may decline with age. A paternal age effect in spermatogenic cells is recognized for the human population as well. To determine if male germ cell base excision repair activity changes with age, uracil-DNA glycosylase-initiated base excision repair activity was measured in mixed germ cell (i.e., all spermatogenic cell types in adult testis) nuclear extracts prepared from young, middle-aged, and old mice. Base excision repair activity was also assessed in nuclear extracts from premeiotic, meiotic, and postmeiotic spermatogenic cell types obtained from young mice. Mixed germ cell nuclear extracts exhibited an age-related decrease in base excision repair activity that was restored by addition of apurinic/apyrimidinic (AP) endonuclease. Uracil-DNA glycosylase and DNA ligase were determined to be limiting in mixed germ cell nuclear extracts prepared from young animals. Base excision repair activity was only modestly elevated in pachytene spermatocytes and round spermatids relative to other spermatogenic cells. Thus, germ line short-patch base excision repair activity appears to be relatively constant throughout spermatogenesis in young animals, limited by uracil-DNA glycosylase and DNA ligase in young animals, and limited by AP endonuclease in old animals.
authors.affiliation: Department of Cellular & Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
authors.forename: Gabriel W
authors.initials: GW
authors.lastname: Intano
authors.forename: C Alex
authors.initials: CA
authors.lastname: McMahan
authors.forename: John R
authors.initials: JR
authors.lastname: McCarrey
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Walter
authors.forename: Allison E
authors.initials: AE
authors.lastname: McKenna
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Mark A
authors.initials: MA
authors.lastname: MacInnes
authors.forename: David J
authors.initials: DJ
authors.lastname: Chen
authors.forename: Christi A
authors.initials: CA
authors.lastname: Walter
mesh_terms: D000375:Aging / Q000235:genetics* / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D019757:Carbon-Oxygen Lyases / Q000378:metabolism; D002457:Cell Extracts / Q000737:chemistry; D045647:DNA Glycosylases; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D008297:Male; D051379:Mice; D009699:N-Glycosyl Hydrolases / Q000378:metabolism; D000075223:Poly-ADP-Ribose Binding Proteins; D013091:Spermatogenesis / Q000235:genetics; D013094:Spermatozoa / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism*; D013737:Testis / Q000166:cytology; D013997:Time Factors; D051981:Uracil-DNA Glycosidase; D029867:Xenopus Proteins
chemical_list: D002457:Cell Extracts; D000075223:Poly-ADP-Ribose Binding Proteins; D029867:Xenopus Proteins; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D051981:Uracil-DNA Glycosidase; D019757:Carbon-Oxygen Lyases; C486216:Apex1 protein, mouse; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D011088:DNA Ligases; D000072481:DNA Ligase ATP; C000618816:DNA ligase III alpha protein, Xenopus