title: In vitro maturation of oocytes alters gene expression and signaling pathways in bovine cumulus cells.
abstract: In vitro maturation (IVM) of immature oocytes is widely used in assisted reproduction technologies in cattle, and is increasingly used to treat human infertility. The development competence of IVM oocytes, however, is lower than preovulatory, in vivo-matured oocytes. During maturation, cumulus cells (CC) are metabolically coupled with an oocyte and support the acquisition of its developmental potential. Our objective was to identify genes and pathways that were affected by IVM in bovine CC. Microarray transcriptomic analysis of CC enclosing in vitro- or in vivo-mature oocytes revealed 472 differentially expressed genes, including 28% related to apoptosis, correlating with twofold higher cell death after IVM than in vivo, as detected by TUNEL. Genes overexpressed after IVM were significantly enriched in functions involved in cell movement, focal adhesion, extracellular matrix function, and TGF-beta signaling, whereas under-expressed genes were enriched in regulating gene expression, energy metabolism, stress response, and MAP kinases pathway functions. Differential expression of 15 genes, including PAG11 (increased) and TXNIP (decreased), which were never detected in CC before, was validated by real-time RT-PCR. Moreover, protein quantification confirmed the lower abundance of glutathione S-transferase A1 and prostaglandin G/H synthase 2, and the higher abundance of hyaluronan synthase 2 and SMAD4, a member of TGF-beta pathway, in CC after IVM. Phosphorylation levels of SMAD2, MAPK3/1, and MAPK14, but not MAPK8, were higher after IVM that in vivo. In conclusion, IVM provokes the hyper-activation of TGF-beta and MAPK signaling components, modifies gene expression, leads to increased apoptosis in CC, and thus affects oocyte quality.
authors.affiliation: INRA, UR85 Physiologie de la Reproduction et des Comportements, Nouzilly, France.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Salhab
authors.forename: Sophie
authors.initials: S
authors.lastname: Dhorne-Pollet
authors.forename: Sylvain
authors.initials: S
authors.lastname: Auclair
authors.forename: Catherine
authors.initials: C
authors.lastname: Guyader-Joly
authors.forename: Daphné
authors.initials: D
authors.lastname: Brisard
authors.forename: Rozenn
authors.initials: R
authors.lastname: Dalbies-Tran
authors.forename: Joelle
authors.initials: J
authors.lastname: Dupont
authors.forename: Claire
authors.initials: C
authors.lastname: Ponsart
authors.forename: Pascal
authors.initials: P
authors.lastname: Mermillod
authors.forename: Svetlana
authors.initials: S
authors.lastname: Uzbekova
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002417:Cattle; D054885:Cumulus Cells / Q000378:metabolism*; D004734:Energy Metabolism / Q000235:genetics; D020869:Gene Expression Profiling / Q000662:veterinary; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D014453:Glucuronosyltransferase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D000076002:Hyaluronan Synthases; D020287:In Situ Nick-End Labeling / Q000662:veterinary; D059471:In Vitro Oocyte Maturation Techniques / Q000379:methods / Q000662:veterinary*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009865:Oocytes / Q000254:growth & development*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D015398:Signal Transduction / Q000502:physiology*; D051785:Smad Proteins / Q000378:metabolism
chemical_list: D051785:Smad Proteins; D011451:Prostaglandin-Endoperoxide Synthases; D014453:Glucuronosyltransferase; D000076002:Hyaluronan Synthases; D005982:Glutathione Transferase; D020928:Mitogen-Activated Protein Kinases