title: ATRX is a novel progesterone-regulated protein and biomarker of low developmental potential in mammalian oocytes.
abstract: A multi-species meta-analysis of published transcriptomic data from models of oocyte competence identified the chromatin remodelling factorATRXas a putative biomarker of oocyte competence. The objective of the current study was to test the hypothesis that ATRX protein expression by cumulus-oocyte complexes (COCs) reflects their intrinsic quality and developmental potential. In excess of 10,000 bovine COCs were utilised to test our hypothesis. COCs werein vitromatured (IVM) under conditions associated with reduced developmental potential: IVM in the presence or absence of (1) progesterone synthesis inhibitor (Trilostane); (2) nuclear progesterone receptor inhibitor (Aglepristone) or (3) an inducer of DNA damage (Staurosporine). ATRX protein expression and localisation were determined using immunocytochemistry and Western blot analysis. A proportion of COCs matured in the presence or absence of Trilostane wasin vitrofertilised and cultured, and subsequent embryo development characteristics were analysed. In addition, ATRX expression was investigated in 40 human germinal vesicle-stage COCs. Our results showed that ATRX is expressed in human and bovine germinal vesicle oocytes and cumulus cells. In bovine, expression decreases after IVM. However, this decline is not observed in COCs matured under sub-optimal conditions. Blastocyst development rate and cell number are decreased, whereas the incidence of abnormal metaphase phase spindle and chromosome alignment are increased, after IVM in the presence of Trilostane (P< 0.05). In conclusion, localisation of ATRX to the cumulus cell nuclei and oocyte chromatin, after IVM, is associated with poor oocyte quality and low developmental potential. Furthermore, ATRX is dynamically regulated in response to progesterone signalling.
authors.affiliation: School of Agriculture and Food Sciences lynne.oshea@ucd.ie.|School of Medicine.
authors.forename: Lynne C
authors.initials: LC
authors.lastname: O'Shea
authors.affiliation: School of Agriculture and Food Sciences.
authors.forename: Edward
authors.initials: E
authors.lastname: Daly
authors.affiliation: School of Bimolecular and Biomedical ScienceUniversity College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Carmel
authors.initials: C
authors.lastname: Hensey
authors.affiliation: School of Agriculture and Food Sciences.
authors.forename: Trudee
authors.initials: T
authors.lastname: Fair
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism; D002417:Cattle; D054885:Cumulus Cells / Q000166:cytology* / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D047108:Embryonic Development / Q000187:drug effects*; D005260:Female; D005307:Fertilization in Vitro; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D059471:In Vitro Oocyte Maturation Techniques; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology; D000075924:X-linked Nuclear Protein
chemical_list: D015415:Biomarkers; D009687:Nuclear Proteins; D011374:Progesterone; D004265:DNA Helicases; C092332:ATRX protein, human; D000075924:X-linked Nuclear Protein