Time-dependent predominance of nonhomologous DNA end-joining pathways during embryonic development in mice.
Repair of DNA double-strand breaks (DSBs) is crucial for maintaining genomic integrity during the successful development of a fertilized egg into a whole organism. To date, the mechanism of DSB repair in postimplantation embryos has been largely unknown. In the present study, using a cell-free repair system derived from the different embryonic stages of mice, we find that canonical nonhomologous end joining (NHEJ), one of the major DSB repair pathways in mammals, is predominant at 14.5 day of embryonic development. Interestingly, all four types of DSBs tested were repaired by ligase IV/XRCC4 and Ku-dependent classical NHEJ. Characterization of end-joined junctions and expression studies further showed evidences for canonical NHEJ. Strikingly, in contrast to the above, we observed noncanonical end joining accompanied by DSB resection, dependent on microhomology and ligase III in 18.5-day embryos. Interestingly, we observed an elevated expression of CtIP, MRE11, and NBS1 at this stage, suggesting that it could act as a switch between classical end joining and microhomology-mediated end joining at later stages of embryonic development. Thus, our results establish for the first time the existence of both canonical and alternative NHEJ pathways during the postimplantation stages of mammalian embryonic development.
Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India.
Kishore K
KK
Chiruvella
Robin
R
Sebastian
Sheetal
S
Sharma
Anjali A
AA
Karande
Bibha
B
Choudhary
Sathees C
SC
Raghavan
D000818:Animals; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D000076228:MRE11 Homologue Protein; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009687:Nuclear Proteins / Q000235:genetics; D000075223:Poly-ADP-Ribose Binding Proteins; D011247:Pregnancy; D012689:Sequence Homology, Nucleic Acid; D000071857:Tumor Suppressor p53-Binding Protein 1; D029867:Xenopus Proteins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C512689:Mre11a protein, mouse; C466108:Nijmegen breakage syndrome 1 protein, mouse; D009687:Nuclear Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; C498302:Trp53bp1 protein, mouse; D000071857:Tumor Suppressor p53-Binding Protein 1; C511788:XRCC4 protein, mouse; D029867:Xenopus Proteins; D000076228:MRE11 Homologue Protein; D011088:DNA Ligases; D045643:DNA Repair Enzymes; D000072481:DNA Ligase ATP; C000618816:DNA ligase III alpha protein, Xenopus; C000618818:Lig3 protein, mouse