Nucleotide excision repair in rat male germ cells: low level of repair in intact cells contrasts with high dual incision activity in vitro
AUTOR(ES)
Jansen, Jacob
FONTE
Oxford University Press
RESUMO
The acquisition of genotoxin-induced mutations in the mammalian germline is detrimental to the stable transfer of genomic information. In somatic cells, nucleotide excision repair (NER) is a major pathway to counteract the mutagenic effects of DNA damage. Two NER subpathways have been identified, global genome repair (GGR) and transcription-coupled repair (TCR). In contrast to somatic cells, little is known regarding the expression of these pathways in germ cells. To address this basic question, we have studied NER in rat spermatogenic cells in crude cell suspension, in enriched cell stages and within seminiferous tubules after exposure to UV or N-acetoxy-2-acetylaminofluorene. Surprisingly, repair in spermatogenic cells was inefficient in the genome overall and in transcriptionally active genes indicating non-functional GGR and TCR. In contrast, extracts from early/mid pachytene cells displayed dual incision activity in vitro as high as extracts from somatic cells, demonstrating that the proteins involved in incision are present and functional in premeiotic cells. However, incision activities of extracts from diplotene cells and round spermatids were low, indicating a stage-dependent expression of incision activity. We hypothesize that sequestering of NER proteins by mispaired regions in DNA involved in synapsis and recombination may underlie the lack of NER activity in premeiotic cells.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=31314Documentos Relacionados
- Highly efficient base excision repair (BER) in human and rat male germ cells
- Mixed spermatogenic germ cell nuclear extracts exhibit high base excision repair activity
- Nucleotide excision repair in a constitutive and inducible gene of a yeast minichromosome in intact cells.
- Structural insights into the first incision reaction during nucleotide excision repair
- Properties of damage-dependent DNA incision by nucleotide excision repair in human cell-free extracts.