A Surveillance Mechanism Ensures Repair of DNA Lesions during Zygotic Reprogramming

Cell. 2016 Dec 15;167(7):1774-1787.e13. doi: 10.1016/j.cell.2016.11.009. Epub 2016 Dec 1.


Sexual reproduction culminates in a totipotent zygote with the potential to produce a whole organism. Sperm chromatin reorganization and epigenetic reprogramming that alter DNA and histone modifications generate a totipotent embryo. Active DNA demethylation of the paternal genome has been proposed to involve base excision and DNA repair-based mechanisms. The nature and consequence of DNA lesions generated during reprogramming are not known. Using mouse genetics and chemical biology, we discovered that Tet3-dependent zygotic reprogramming generates paternal DNA lesions that are monitored by a surveillance mechanism. In vivo structure-function rescue assays revealed that cohesin-dependent repair of paternal DNA lesions prevents activation of a Chk1-dependent checkpoint that delays mitotic entry. Culturing conditions affect checkpoint stringency, which has implications for human in vitro fertilization. We propose the zygotic checkpoint senses DNA lesions generated during paternal DNA demethylation and ensures reprogrammed loci are repaired before mitosis to prevent chromosome fragmentation, embryo loss, and infertility.

Keywords: DNA damage repair; checkpoint; cohesin; reprogramming; zygote.

MeSH terms

  • Animals
  • Cell Cycle Proteins / metabolism
  • Cellular Reprogramming
  • Chromosomal Proteins, Non-Histone / metabolism
  • DNA Methylation
  • DNA Repair*
  • DNA-Binding Proteins / metabolism
  • Embryo, Mammalian / metabolism
  • Female
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Proto-Oncogene Proteins / metabolism
  • X-ray Repair Cross Complementing Protein 1
  • Zygote / cytology*
  • Zygote / metabolism*


  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Phosphoproteins
  • Proto-Oncogene Proteins
  • Rad21 protein, mouse
  • X-ray Repair Cross Complementing Protein 1
  • cohesins
  • Tet3 protein, mouse