Highly efficient base excision repair (BER) in human and rat male germ cells

Olsen, Ann‐Karin; Bjørtuft, Helle; Wiger, Richard; Holme, Jørn A.; Seeberg, Erling; Bjørås, Magnar; Brunborg, Gunnar

doi:10.1093/nar/29.8.1781

Cited by 74 publications

(48 citation statements)

References 68 publications

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“…Western blot analyses have supported the RNA data showing greater levels of DNA ligases I and III, Xrcc-1, Ape/Ref-1, and ␤-pol proteins in mixed germ cell (MGC, i.e., all spermatogenic cell types in adult testis) nuclear extracts than in adult somatic tissues (26,48). Furthermore, we have reported higher levels of uracil-DNA glycosylase-initiated base excision repair (UDG-BER) activity in MGC nuclear extracts obtained from young adult mice compared to extracts from brain, liver, enriched preparations of prepubertal Sertoli cells, thymocytes, and small intestine (26).…”

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confidence: 74%

Base Excision Repair Is Limited by Different Proteins in Male Germ Cell Nuclear Extracts Prepared from Young and Old Mice

Intano

McMahan

McCarrey

et al. 2002

Molecular and Cellular Biology

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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 shortpatch 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.Germ line genomic stability is an important factor in reproductive health, with approximately 20% of genetic diseases attributed to new germ line mutations (12,13,46). Several autosomal dominant genetic diseases due to de novo male germ line mutations are associated with increased paternal age (18,21,45,49), suggesting that male germ line genomic stability is compromised with age. Analysis of chromosomes in spermatozoa revealed an increased frequency of aberrations with age (24, 34, 41, 54), providing additional evidence that male germ line genomic stability decreases with age. Similarly in mice, the spontaneous mutant frequency in a lacI transgene recovered from pachytene spermatocytes, round spermatids, and epididymal spermatozoa obtained from old animals was approximately 10-fold higher than the mutant frequency observed for young mice (60).In contrast to the decline in germ line genetic integrity with old age, the germ line DNA of young mice appears to be well maintained. Compared to somatic tissues, a lower spontaneous mutant frequency in the male germ line for a lacI transgene has been reported for fish (65), mice (32, 60), and rats (16). The murine mitotically proliferating male germ cell pool is comprised of primitive type A spermatogonia, which sequentially give rise to mitotically active, type ...

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mentioning

confidence: 74%

Base Excision Repair Is Limited by Different Proteins in Male Germ Cell Nuclear Extracts Prepared from Young and Old Mice

Intano

McMahan

McCarrey

et al. 2002

Molecular and Cellular Biology

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“…However, recent reports (65) have indicated that nuclear DNA of human spermatozoa is relatively resistant to damage induced by H 2 O 2 and iron treatment in vitro. This particular paradox may be due to the high relative level of BER found in testes (53,54,66) and the ability of APE to function both as a BER enzyme and as a redox regulatory molecule. Because BER may function independently of APE (67), it is likely that under circumstances of FIG.…”

Section: Discussionmentioning

confidence: 99%

Apurinic/Apyrimidinic Endonuclease (APE/REF-1) Haploinsufficient Mice Display Tissue-specific Differences in DNA Polymerase β-Dependent Base Excision Repair

Raffoul

Cabelof

Nakamura

et al. 2004

Journal of Biological Chemistry

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Apurinic/apyrimidinic (AP) endonuclease (APE) is a multifunctional protein possessing both DNA repair and redox regulatory activities. In base excision repair (BER), APE is responsible for processing spontaneous, chemical, or monofunctional DNA glycosylase-initiated AP sites via its 5 -endonuclease activity and 3 -"endtrimming" activity when processing residues produced as a consequence of bifunctional DNA glycosylases. In this study, we have fully characterized a mammalian model of APE haploinsufficiency by using a mouse containing a heterozygous gene-targeted deletion of the APE gene (Apex ؉/؊ ). Our data indicate that Apex ؉/؊ mice are indeed APE-haploinsufficient, as exhibited by a 40 -50% reduction (p < 0.05) in APE mRNA, protein, and 5 -endonuclease activity in all tissues studied. Based on gene dosage, we expected to see a concomitant reduction in BER activity; however, by using an in vitro G:U mismatch BER assay, we observed tissue-specific alterations in monofunctional glycosylase-initiated BER activity, e.g. liver (35% decrease, p < 0.05), testes (55% increase, p < 0.05), and brain (no significant difference). The observed changes in BER activity correlated tightly with changes in DNA polymerase ␤ and AP site DNA binding levels. We propose a mechanism of BER that may be influenced by the redox regulatory activity of APE, and we suggest that reduced APE may render a cell/tissue more susceptible to dysregulation of the polymerase ␤-dependent BER response to cellular stress.Apurinic/apyrimidinic (AP) 1 endonuclease (APE) is a multifunctional protein involved in the maintenance of genomic integrity and in the regulation of gene expression. After the initial discovery in Escherichia coli (1), APE was purified from calf thymus DNA and extensively characterized as an endonuclease that cleaves the backbone of double-stranded DNA containing AP sites (2, 3). APE homologues were subsequently identified and characterized in many organisms, including yeast as APN1 (4), mice as Apex (5, 6), and humans as HAP1 (7). In addition to its major 5Ј-endonuclease activity, APE also expresses minor 3Ј-phosphodiesterase, 3Ј-phosphatase, and 3Ј 3 5Ј-exonuclease activities (8), the biological significance of which is controversial (9). Independent of its discovery as a DNA repair protein, APE was also characterized as REF-1, for redox factor-1, a redox activator of cellular transcription factors (10 -12). Although the molecular detail of APE redox activity is still unclear (13), the discovery of APE as a regulator of transcriptional activity may underscore the importance of its involvement in cellular stress-response pathways.APE is the primary enzyme responsible for recognition and incision of non-coding AP sites in DNA arising as a consequence of spontaneous, chemical, or DNA glycosylase-mediated hydrolysis of the N-glycosyl bond initiated by the base excision repair (BER) pathway. These lesions are particularly common, arising at the rate of ϳ50,000 -200,000 AP sites per cell per day under normal physiological conditions (14,...

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“…Evidence from the literature indicates that other DNA repair systems may play a role during spermiogenesis. Elements of the base excision repair (BER) have been identified in elongating and elongated spermatids [Olsen et al 2001]. In addition, there is evidence that mismatch repair (MMR) involving the MSH2 protein, is playing a role during spermiogenesis.…”

Section: Further Evidence Of a Dna Repair System In Spermatidsmentioning

confidence: 99%

Spermiogenesis and DNA Repair: A Possible Etiology of Human Infertility and Genetic Disorders

Leduc¹,

Nkoma²,

Boissonneault³

2008

Systems Biology in Reproductive Medicine

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This paper reviews the possible origin of sperm DNA fragmentation and focuses on the nuclear events associated with spermiogenesis as a potential source of genetic instability and reduced fertilizing potential of the mature male gamete. Recent findings suggest a programmed DNA fragmentation and DNA damage response during the chromatin remodeling steps in spermatids. We also discuss the spermatid DNA repair mechanisms and the possible involvement of condensing proteins, such as transition proteins and protamines, in the process, as this DNA fragmentation is normally not found in late spermatids. We propose that alterations in the chromatin remodeling steps or DNA repair in elongating spermatids may lead to persistent DNA breaks. This vulnerable step of spermiogenesis may provide a clue to the etiology of sperm DNA fragmentation associated with infertility in humans. This vulnerability is further emphasized given the haploid character of spermatids that must resolve programmed double-stranded breaks by an error-prone DNA repair mechanism. Therefore, spermiogenesis has probably been overlooked as an important source of genetic instability.

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Highly efficient base excision repair (BER) in human and rat male germ cells

Cited by 74 publications

References 68 publications

Base Excision Repair Is Limited by Different Proteins in Male Germ Cell Nuclear Extracts Prepared from Young and Old Mice

Base Excision Repair Is Limited by Different Proteins in Male Germ Cell Nuclear Extracts Prepared from Young and Old Mice

Apurinic/Apyrimidinic Endonuclease (APE/REF-1) Haploinsufficient Mice Display Tissue-specific Differences in DNA Polymerase β-Dependent Base Excision Repair

Spermiogenesis and DNA Repair: A Possible Etiology of Human Infertility and Genetic Disorders

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