title: Cumulus Cell Transcripts Transit to the Bovine Oocyte in Preparation for Maturation.
abstract: So far, the characteristics of a good quality egg have been elusive, similar to the nature of the physiological, cellular, and molecular cues leading to its production both in vivo and in vitro. Current understanding highlights a strong and complex interdependence between the follicular cells and the gamete. Secreted factors induce cellular responses in the follicular cells, and direct exchange of small molecules from the cumulus cells to the oocyte through gap junctions controls meiotic arrest. Studying the interconnection between the cumulus cells and the oocyte, we previously demonstrated that the somatic cells also contribute transcripts to the gamete. Here, we show that these transcripts can be visualized moving down the transzonal projections (TZPs) to the oocyte, and that a time course analysis revealed progressive RNA accumulation in the TZPs, indicating that RNA transfer occurs before the initiation of meiosis resumption under a timetable fitting with the acquisition of developmental competence. A comparison of the identity of the nascent transcripts trafficking in the TZPs, with those in the oocyte increasing in abundance during maturation, and that are present on the oocyte's polyribosomes, revealed transcripts common to all three fractions, suggesting the use of transferred transcripts for translation. Furthermore, the removal of potential RNA trafficking by stripping the cumulus cells caused a significant reduction in maturation rates, indicating the need for the cumulus cell RNA transfer to the oocyte. These results offer a new perspective to the determinants of oocyte quality and female fertility, as well as provide insight that may eventually be used to improve in vitro maturation conditions.
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada.
authors.forename: Angus D
authors.initials: AD
authors.lastname: Macaulay
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Gilbert
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Scantland
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Fournier
authors.affiliation: Department of Biomedical Sciences, Reproductive Biology Lab, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Fazl
authors.initials: F
authors.lastname: Ashkar
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Bastien
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada.
authors.forename: Habib A Shojaei
authors.initials: HA
authors.lastname: Saadi
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada.
authors.forename: Dominic
authors.initials: D
authors.lastname: Gagné
authors.affiliation: Département de Psychiatrie et Neurosciences, Institut universitaire en santé mentale de Québec, Université Laval, Québec City, Québec, Canada.
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Sirard
authors.affiliation: Département de Psychiatrie et Neurosciences, Institut universitaire en santé mentale de Québec, Université Laval, Québec City, Québec, Canada.
authors.forename: Édouard W
authors.initials: ÉW
authors.lastname: Khandjian
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada.
authors.forename: François J
authors.initials: FJ
authors.lastname: Richard
authors.affiliation: Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Poul
authors.initials: P
authors.lastname: Hyttel
authors.affiliation: Département des sciences animales, Centre de recherche en biologie de la reproduction, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Québec, Québec, Canada claude.robert@fsaa.ulaval.ca.
authors.forename: Claude
authors.initials: C
authors.lastname: Robert
mesh_terms: D000818:Animals; D002417:Cattle; D054885:Cumulus Cells / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D005298:Fertility; D005786:Gene Expression Regulation; D015698:Genomic Library; D005854:Germ Cells; D008540:Meiosis; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D009866:Oogenesis / Q000502:physiology; D006080:Ovarian Follicle / Q000166:cytology; D011132:Polyribosomes; D012313:RNA / Q000096:biosynthesis / Q000235:genetics
chemical_list: D012313:RNA
keywords: RNA transfer; cumulus cells; maturation; oocyte; transzonal projection