title: Bi-directional communication with the cumulus cells is involved in the deficiency of XY oocytes in the components essential for proper second meiotic spindle assembly.
abstract: The oocyte becomes competent for embryonic development by involving mutual communication with cumulus cells (CCs) during folliculogenesis. How this communication takes place under physiological conditions is not fully understood. Current study examined oocyte-CCs communication in the XY sex-revered female mouse. We have previously found that the XY oocyte is defective in its cytoplasm, causing abnormal MII-spindle assembly and a failure in embryonic development. Our present study showed that transcript levels of Pfkp, Pkm2 and Ldh1 involved in glycolysis were lower in the CCs surrounding XY oocytes than in those surrounding XX oocytes. ATP contents in XY oocytes were also lower than those in XX oocytes, suggesting that lower glycolytic gene expression in CCs resulted in lower ATP contents in the enclosed oocyte. Co-culture of oocytectomized CC-oocyte complexes (COCs) with denuded oocytes showed that XY oocytes were less efficient than XX oocytes in promoting glycolytic gene expression in CCs. Furthermore, both glycolytic gene expression levels in CCs and ATP contents in oocytes of XY COCs increased to similar levels to those of XX COCs after culture for 20h in the presence of milrinone (=preincubation), which prevented spontaneous oocyte maturation. By increasing ATP levels in XY oocytes by either COC preincubation or ATP microinjection into oocytes prior to in vitro maturation, an improvement in MII-spindle assembly was observed. We conclude that the XY oocyte produces lesser amounts of paracrine factors that affect its companion CCs, which in turn make the ooplasm deficient in its components, including ATP, essential for MII-spindle assembly.
authors.affiliation: Departments of Surgery and Biology, McGill University, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC, Canada H3A 1A1.
authors.forename: Baozeng
authors.initials: B
authors.lastname: Xu
authors.affiliation: Departments of Surgery and Biology, McGill University, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC, Canada H3A 1A1.
authors.forename: Saeid
authors.initials: S
authors.lastname: Noohi
authors.affiliation: Departments of Surgery and Biology, McGill University, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC, Canada H3A 1A1.
authors.forename: Jonghyun S
authors.initials: JS
authors.lastname: Shin
authors.affiliation: Department of Obstetrics and Gynecology, McGill University, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC, Canada H3A 1A1; Montreal Reproductive Center, 2110 Decarie Blvd, Montreal, QC, Canada H4A 3J3.
authors.forename: Seang Lin
authors.initials: SL
authors.lastname: Tan
authors.affiliation: Departments of Surgery and Biology, McGill University, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC, Canada H3A 1A1; Department of Obstetrics and Gynecology, McGill University, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC, Canada H3A 1A1; Montreal Reproductive Center, 2110 Decarie Blvd, Montreal, QC, Canada H4A 3J3. Electronic address: teruko.taketo@mcgill.ca.
authors.forename: Teruko
authors.initials: T
authors.lastname: Taketo
mesh_terms: D000818:Animals; D001483:Base Sequence; D003470:Culture Media; D054885:Cumulus Cells / Q000166:cytology*; D017931:DNA Primers; D015870:Gene Expression; D006019:Glycolysis / Q000235:genetics; D008540:Meiosis; D051379:Mice; D018613:Microscopy, Confocal; D020105:Milrinone / Q000008:administration & dosage; D009865:Oocytes / Q000166:cytology*; D060888:Real-Time Polymerase Chain Reaction; D008941:Spindle Apparatus / Q000502:physiology*; D014960:X Chromosome; D014998:Y Chromosome
chemical_list: D003470:Culture Media; D017931:DNA Primers; D020105:Milrinone
keywords: ATP; Cumulus cells; Glycolysis; Meiotic spindle; Oocyte; XY female mouse