p66shc, but not p53, is involved in early arrest of in vitro‐produced bovine embryos

• Published in: Molecular human reproduction 2004-06, Vol.10 (6), p.383-392
• Main Authors: Favetta, L.A., Robert, C., St.John, E.J., Betts, D.H., King, W.A.
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adaptor Proteins, Signal Transducing - metabolism; Animals; Apoptosis - physiology; Biological and medical sciences; Blastocyst - cytology; Blastocyst - physiology; Cattle - embryology; Cell Cycle - physiology; Cellular Senescence - physiology; developmental arrest/embryos/p53/p66shc/senescence; Embryology: invertebrates and vertebrates. Teratology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Humans; Molecular Sequence Data; Phosphorylation; RNA, Messenger - metabolism; Serine - metabolism; Shc Signaling Adaptor Proteins; Src Homology 2 Domain-Containing, Transforming Protein 1; Tumor Suppressor Protein p53 - genetics; Tumor Suppressor Protein p53 - metabolism
• ISSN: 1360-9947; 1460-2407; 1460-2407
• DOI: 10.1093/molehr/gah057

High embryo loss occurs in the first week of bovine embryo development, with a high percentage of embryonic arrest. We hypothesized that arrested embryos enter a ‘senescence‐like state’ and that both the cell cycle regulatory protein p53 and the stress‐related protein p66shc, which are involved in the onset of senescence in somatic cells, are responsible for this early embryonic arrest. In our in vitro production system, 13.5 ± 0.5% of embryos arrest at the 2–4‐cell stage. First cleavage occurs between 26 and 48 h post insemination (hpi), with early cleaving embryos showing only 0.6 ± 0.3% arrest, with later cleaving embryos exhibiting up to 14.2 ± 0.9% arrest. We compared 2–4‐cell embryos collected at 28 hpi with those arrested at the 2–4‐cell stage collected at day 8 post insemination. Quantification by real‐time PCR and by semi‐quantitative immunofluorescence showed significantly higher p66shc mRNA and protein levels in both arrested and late cleaving embryos versus 28 hpi embryos. By comparison, no significant changes in p53 mRNA, protein and phosphorylation levels were detected. Taken together, these results demonstrate that embryonic developmental potential is related to the time of first cleavage and that p66shc, but not p53, is up‐regulated in early arrested in vitro‐produced bovine embryos.