title: High levels of p66shc and intracellular ROS in permanently arrested early embryos.
abstract: A high incidence of permanent embryo arrest occurs during the first week of in vitro development. We hypothesize that this developmental arrest event is regulated by the stress adaptor protein p66shc, a genetic determinant of life span in mammals, which regulates ROS metabolism, apoptosis, and cellular senescence. The aim of this study was to assess the relationship between intracellular oxidative stress levels with the incidence of embryo arrest and the expression of senescent-associated genes in embryos produced under different oxygen tensions. Embryos cultured under 20% oxygen conditions showed approximately 10-fold increase in oxidative stress, 2-fold increase in the percentage of 2- to 4-cell arrest, and significantly lower developmental capabilities compared to embryos cultured under a 5% oxygen environment. Quantification by real-time PCR and by semiquantitative immunofluorescence showed significantly higher p66shc mRNA and protein levels, respectively, in embryos cultured in 20% versus those cultured in 5% oxygen atmosphere. No significant changes in p53 mRNA and protein levels were detected among embryos derived from both oxygen tensions. Taken together, these results demonstrate that p66shc, but not p53, is significantly more abundant in an embryo population that exhibits higher frequencies of embryo arrest and quantities of intracellular ROS. These results further substantiate that p66shc and oxidative stress are associated with a p53-independent embryonic arrest event for in vitro-produced embryos.
authors: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada.
authors: Laura A
authors: LA
authors: Favetta
authors: Elizabeth J
authors: EJ
authors: St John
authors: W Allan
authors: WA
authors: King
authors: Dean H
authors: DH
authors: Betts
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002417:Cattle; D002455:Cell Division; D005260:Female; D005307:Fertilization in Vitro; D007700:Kinetics; D008297:Male; D009865:Oocytes / Q000502:physiology; D010053:Ovary; D010101:Oxygen Consumption; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012661:Semen / Q000502:physiology; D055765:Shc Signaling Adaptor Proteins; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017382:Reactive Oxygen Species; D055765:Shc Signaling Adaptor Proteins; D016159:Tumor Suppressor Protein p53; D012313:RNA