The 5.8S pre-rRNA maturation factor, M-phase phosphoprotein 6, is a female fertility factor required for oocyte quality and meiosis

Cell Prolif. 2020 Mar;53(3):e12769. doi: 10.1111/cpr.12769. Epub 2020 Jan 31.

Abstract

Objectives: M-phase phosphoprotein 6 (MPP6) is important for 5.8S pre-rRNA maturation in somatic cells and was screened as a female fertility factor. However, whether MPP6 functions in oocyte meiosis and fertility is not yet known. We aimed to address this.

Materials and methods: Mouse oocytes with surrounded nucleus (SN) or non-surrounded nucleus (NSN) were used for all experiments. Peptide nanoparticle-mediated antibody transfection was used to deplete MPP6. Immunofluorescence staining, immunohistochemistry and live tracker staining were used to examine MPP6 localization and characterize phenotypes after control or MPP6 depletion. High-fidelity PCR and fluorescence in situ hybridization (FISH) were used to examine the localization and level of 5.8S rRNAs. Western blot was used to examine the protein level. MPP6-EGFP mRNA microinjection was used to do the rescue.

Results: MPP6 was enriched within ovaries and oocytes. MPP6 depletion significantly impeded oocyte meiosis. MPP6 depletion increased 5.8S pre-rRNA. The mRNA levels of MPP6 and 5.8S rRNA decreased within ageing oocytes, and MPP6 mRNA injection partially increased 5.8S rRNA maturation and improved oocyte quality.

Conclusions: MPP6 is required for 5.8S rRNA maturation, meiosis and quality control in mouse oocytes, and MPP6 level might be a marker for oocyte quality.

Keywords: 5.8S Pre-rRNA; M-phase phosphoprotein 6; female fertility factor; meiosis; oocyte; quality.

MeSH terms

  • Animals
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Division
  • Cells, Cultured
  • Cellular Senescence
  • Female
  • Fertility
  • Fertilization in Vitro
  • Meiosis
  • Mice
  • Mice, Inbred ICR
  • Oocytes / cytology*
  • Oocytes / metabolism
  • Oocytes / ultrastructure
  • RNA, Ribosomal, 5.8S / metabolism*
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*

Substances

  • Cell Cycle Proteins
  • Mphosph6 protein, mouse
  • RNA, Ribosomal, 5.8S
  • RNA-Binding Proteins