Extracts of proliferating and non-proliferating human cells display different base excision pathways and repair fidelity.
Base excision repair (BER) of damaged or inappropriate bases in DNA has been reported to take place by single nucleotide insertion or through incorporation of several nucleotides, termed short-patch and long-patch repair, respectively. We found that extracts from proliferating and non-proliferating cells both had capacity for single- and two-nucleotide insertion BER activity. However, patch size longer than two nucleotides was only detected in extracts from proliferating cells. Relative to extracts from proliferating cells, extracts from non-proliferating cells had approximately two-fold higher concentration of POLbeta, which contributed to most of two-nucleotide insertion BER. In contrast, two-nucleotide insertion in extracts from proliferating cells was not dependent on POLbeta. BER fidelity was two- to three-fold lower in extracts from the non-proliferating compared with extracts of proliferating cells. Furthermore, although one-nucleotide deletion was the predominant type of repair error in both extracts, the pattern of repair errors was somewhat different. These results establish two-nucleotide patch BER as a distinct POLbeta-dependent mechanism in non-proliferating cells and demonstrate that BER fidelity is lower in extracts from non-proliferating as compared with proliferating cells.
Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, NTNU, N-7489 Trondheim, Norway. mansour.akbari@ntnu.no
Mansour
M
Akbari
Javier
J
Peña-Diaz
Sonja
S
Andersen
Nina-Beate
NB
Liabakk
Marit
M
Otterlei
Hans Einar
HE
Krokan
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002457:Cell Extracts / Q000737:chemistry; D002460:Cell Line; D049109:Cell Proliferation; D002478:Cells, Cultured; D019951:DNA Polymerase beta / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000502:physiology*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D008214:Lymphocytes / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D009154:Mutation; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013379:Substrate Specificity
D002457:Cell Extracts; D009841:Oligonucleotides; D019951:DNA Polymerase beta