Tribbles expression in cumulus cells is related to oocyte maturation and fatty acid metabolism.
BACKGROUND
In mammals, the Tribbles family includes widely expressed serine-threonine kinase-like proteins (TRIB1, TRIB2 and TRIB3) that are involved in multiple biological processes including cell proliferation and fatty acid (FA) metabolism. Our recent studies highlighted the importance of FA metabolism in cumulus cells (CC) during oocyte maturation in vertebrates and reported a higher TRIB1 expression in CC surrounding in vivo mature oocytes as compared to immature ooocytes in mice and cows. The objective was to investigate Tribbles expression patterns in bovine CC during in vitro maturation (IVM) and to examine their roles in the cumulus-oocyte complex.


METHODS
Tribbles gene expression was analyzed in bovine and murine CC using quantitative RT-PCR. Proteins were detected using Western blot and intracellular localization was assessed by immunofluorescence. Bovine COCs were treated with etomoxir, an inhibitor of FA oxidation (FAO) which blocks CPT1 activity, during 6 h and 18 h IVM. Oocyte meiotic stage was assessed and expression of Tribbles and lipid metabolism genes was quantified in CC.


CONCLUSIONS
TRIB1 and TRIB3 were more strongly expressed whereas TRIB2 was less expressed in CC surrounding the oocytes from preovulatory follicles than in CC of immature ones. In CC, Tribbles were located in the cytoplasm and nucleus; in mitotic cells TRIB2 and TRIB3 were detected in the spindle. In the oocyte, Tribbles proteins were detected in the ooplasm; also TRIB2 and TRIB3 were more accumulated in the germinal vesicle. In bovine CC, expression of TRIB1 and TRIB3 was transiently increased at a time preceding oocyte meiosis resumption in vitro. Treatment with etomoxir (150 μM) during IVM resulted in a significant reduction of oocyte maturation rate and decreased MAPK3/1 phosphorylation in the oocytes. In CC, 18 h IVM of etomoxir treatment significantly increased expression of TRIB1, TRIB3, CPTA1 (enzyme regulating FA entry in mitochondria for FAO) and CD36 (thrombospondin receptor involved in FA transport). Under the same conditions, expression of TRIB2 and ACACA (Acetyl coenzyme A carboxylase involved in FA synthesis) decreased in CC. All considered, Tribbles family members may be involved in cell proliferation and in FAO signaling in CC and participate in oocyte meiotic resumption regulation.
INRA, UMR 85 Physiologie de la Reproduction et des Comportements, Nouzilly 37380, France ; CNRS UMR7247, Nouzilly 37380, France ; Université François Rabelais de Tours, Tours 37000, France ; IFCE, Nouzilly 37380, France.
Daphné
D
Brisard
CNRS, Université de Rennes 1, UMR6290, Rennes 35000, France.
Franck
F
Chesnel
INRA, UMR 85 Physiologie de la Reproduction et des Comportements, Nouzilly 37380, France ; CNRS UMR7247, Nouzilly 37380, France ; Université François Rabelais de Tours, Tours 37000, France ; IFCE, Nouzilly 37380, France.
Sébastien
S
Elis
INRA, UMR 85 Physiologie de la Reproduction et des Comportements, Nouzilly 37380, France ; CNRS UMR7247, Nouzilly 37380, France ; Université François Rabelais de Tours, Tours 37000, France ; IFCE, Nouzilly 37380, France.
Alice
A
Desmarchais
INRA, UMR 85 Physiologie de la Reproduction et des Comportements, Nouzilly 37380, France ; CNRS UMR7247, Nouzilly 37380, France ; Université François Rabelais de Tours, Tours 37000, France ; IFCE, Nouzilly 37380, France.
Laura
L
Sánchez-Lazo
INRA, UMR 85 Physiologie de la Reproduction et des Comportements, Nouzilly 37380, France ; CNRS UMR7247, Nouzilly 37380, France ; Université François Rabelais de Tours, Tours 37000, France ; IFCE, Nouzilly 37380, France.
Manon
M
Chasles
INRA, UMR 85 Physiologie de la Reproduction et des Comportements, Nouzilly 37380, France ; CNRS UMR7247, Nouzilly 37380, France ; Université François Rabelais de Tours, Tours 37000, France ; IFCE, Nouzilly 37380, France.
Virginie
V
Maillard
INRA, UMR 85 Physiologie de la Reproduction et des Comportements, Nouzilly 37380, France ; CNRS UMR7247, Nouzilly 37380, France ; Université François Rabelais de Tours, Tours 37000, France ; IFCE, Nouzilly 37380, France.
Svetlana
S
Uzbekova
D000818:Animals; D002417:Cattle; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D054885:Cumulus Cells / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004852:Epoxy Compounds / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D050356:Lipid Metabolism; D008810:Mice, Inbred C57BL; D009865:Oocytes / Q000502:physiology*; D009866:Oogenesis; D006080:Ovarian Follicle / Q000166:cytology / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D004852:Epoxy Compounds; D005227:Fatty Acids; D047908:Intracellular Signaling Peptides and Proteins; C474830:TRB3 protein, mouse; C523598:Trib1 protein, mouse; C515847:tribbles 2 protein, mouse; D017346:Protein Serine-Threonine Kinases; C054207:etomoxir
Cumulus cells; Fatty acid metabolism; Oocyte maturation; Tribbles