title: Zygotic G2/M cell cycle arrest induced by ATM/Chk1 activation and DNA repair in mouse embryos fertilized with hydrogen peroxide-treated epididymal mouse sperm.
abstract: Human sperm cryopreservation for assisted reproduction is compromised by ROS-induced sperm cryodamage. Our previous model study in which mouse sperm were treated with H₂O₂ to simulate sperm DNA-damage caused by cryopreservation-induced ROS have discovered that mouse embryos fertilized with treated sperm showed a delay in cleavage that might be associated with cell cycle arrest. The DNA-damage checkpoint pathway underlying the delay remained elusive. Moreover, our previous study have also indicated that γH2AX, the DNA-damage repair marker, was functional in mouse embryos similarly fertilized, but the completeness and correctness are unknown and warrant more studies because insufficiency of completeness and correctness of DNA repair would otherwise trigger apoptosis. Based on the aforementioned model, we used embryo culture, inverted microscope, BrdU incorporation and immunofluorescence to explore the cell cycle phase that arrest occurred and the underlying DNA-damage checkpoint pathway in mouse zygotes fertilized with H₂O₂-treated sperm. We also adopted Tunel to investigate the apoptosis of mouse embryos similarly fertilized at different developmental stages to testify the completeness and correctness of sperm-derived DNA-damage repair. We found G2/M cell cycle arrest in zygotes fertilized with H₂O₂-treated sperm. ATM (pSer-1981) and Chk1 (pSer-345) activations, rather than ATR (pSer-428) and Chk2 (pThr-68), were detected in zygotes of the treated group. The apoptosis of embryos of different developmental stages of the treated group weren't different from those of the untreated group. In conclusions, ATM (pSer-1981)-Chk1 (pSer-345) cascade might have mediated G2/M cell cycle arrest and allowed time to facilitate sperm-derived DNA-damage repair in mouse zygotes fertilized with oxygen-stressed sperm, and the DNA-damage repair might be effective.
authors.affiliation: Reproductive Center, The First Affiliated Hospital of Shantou University Medical College, Shantou University, Shantou, Guangdong, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Zhiling
authors.initials: Z
authors.lastname: Li
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Man
authors.initials: M
authors.lastname: Chen
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Xiao
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wu
authors.forename: Wanfen
authors.initials: W
authors.lastname: Xiao
authors.forename: Yu
authors.initials: Y
authors.lastname: Song
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D059447:Cell Cycle Checkpoints; D000071877:Checkpoint Kinase 1; D004260:DNA Repair; D047108:Embryonic Development / Q000502:physiology; D004789:Enzyme Activation; D004822:Epididymis / Q000166:cytology; D005260:Female; D059565:G2 Phase Cell Cycle Checkpoints; D006861:Hydrogen Peroxide / Q000494:pharmacology; D059566:M Phase Cell Cycle Checkpoints; D008297:Male; D051379:Mice; D011494:Protein Kinases / Q000378:metabolism*; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology; D015053:Zygote / Q000378:metabolism*
chemical_list: D006861:Hydrogen Peroxide; D011494:Protein Kinases; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse
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