title: Embryo arrest and reactivation: potential candidates controlling embryonic diapause in the tammar wallaby and mink†.
abstract: Embryonic diapause is a period of developmental arrest which requires coordination of a molecular cross-talk between the endometrium and blastocyst to ensure a successful reactivation, but the exact mechanisms are undefined. The objectives of this study were to screen the tammar blastocyst for potential diapause control factors and to investigate the potential for members of the epidermal growth factor (EGF) family to coordinate reactivation. A select number of factors were also examined in the mink to determine whether their expression patterns were conserved across diapause species. The full-length sequences of the tammar genes of interest were first cloned to establish their level of sequence conservation with other mammals. The uterine expression of EGF family members EGF and heparin-binding EGF (HBEGF) and their receptors (EGFR and erb-b2 receptor tyrosine kinase 4 (ERBB4)) was determined by quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. Both HBEGF and EGF were significantly upregulated at reactivation compared to diapause. In the blastocyst, the expression of the potential diapause factors Forkhead box class O family members (FOXO1, FOXO3, and FOXO4), tumor protein 53 (TP53), cyclin-dependent kinase inhibitor 1A (CDKN1A), and the EGF family were examined by RT-PCR and immunofluorescence. Nuclear (and hence active) FOXO expression was confirmed for the first time in a mammalian diapause blastocyst in both the tammar and the mink-CDKN1A was also expressed, but TP53 is not involved and EGFR was not detected in the blastocyst. These results indicate that the EGF family, FOXOs, and CDKN1A are promising candidates for the molecular control of embryonic diapause in mammals.
authors.affiliation: School of BioSciences, The University of Melbourne, Victoria, Australia.|Centre de recherché en reproduction animale, Faculté de médicine vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada.
authors.forename: Jane C
authors.initials: JC
authors.lastname: Fenelon
authors.affiliation: School of BioSciences, The University of Melbourne, Victoria, Australia.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Shaw
authors.affiliation: School of BioSciences, The University of Melbourne, Victoria, Australia.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Frankenberg
authors.affiliation: Centre de recherché en reproduction animale, Faculté de médicine vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Murphy
authors.affiliation: School of BioSciences, The University of Melbourne, Victoria, Australia.
authors.forename: Marilyn B
authors.initials: MB
authors.lastname: Renfree
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D003001:Cloning, Molecular; D000074767:Diapause / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology*; D004717:Endometrium / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D007614:Macropodidae / Q000196:embryology*; D008907:Mink / Q000196:embryology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D059467:Transcriptome
chemical_list: D012333:RNA, Messenger
keywords: blastocyst; comparative reproduction; diapause; endometrium; growth factors