Loss of Cnot6l impairs inosine RNA modifications in mouse oocytes

Pavla Brachova, Nehemiah S. Alvarez, Lane K. Christenson

Research output: Contribution to journalArticlepeer-review

Abstract

Mammalian oocytes must degrade maternal transcripts through a process called translational mRNA decay, in which maternal mRNA undergoes translational activation, followed by deadenylation and mRNA decay. Once a transcript is translationally activated, it becomes deadenylated by the CCR4-NOT complex. Knockout of CCR4-NOT Transcription Complex Subunit 6 Like (Cnot6l), a deadenylase within the CCR4-NOT complex, results in mRNA decay defects during metaphase I (MI) entry. Knockout of B-cell translocation gene-4 (Btg4), an adaptor protein of the CCR4-NOT complex, results in mRNA decay defects following fertilization. Therefore, mechanisms controlling mRNA turnover have significant impacts on oocyte competence and early embryonic development. Post-transcriptional inosine RNA modifications can impact mRNA stability, possibly through a translation mechanism. Here, we assessed inosine RNA modifications in oocytes, eggs, and embryos from Cnot6l-/- and Btg4-/- mice, which display stabilization of mRNA and overtranslation of the stabilized transcripts. If inosine modifications have a role in modulating RNA stability, we hypothesize that in these mutant backgrounds, we would observe changes or a disruption in inosine mRNA modifications. To test this, we used a computational approach to identify inosine RNA modifications in total and polysomal RNA-seq data during meiotic maturation (GV, MI, and MII stages). We observed pronounced depletion of inosine mRNA modifications in samples from Cnot6l-/-, but not in Btg4-/- mice. Additionally, analysis of ribosome-associated RNA revealed clearance of inosine modified mRNA. These observations suggest a novel mechanism of mRNA clearance during oocyte maturation, in which inosine-containing transcripts decay in an independent, but parallel mechanism to CCR4-NOT deadenylation.

Original languageEnglish (US)
Article number1191
Pages (from-to)1-17
Number of pages17
JournalInternational journal of molecular sciences
Volume22
Issue number3
DOIs
StatePublished - Feb 1 2021

Keywords

  • ADAR
  • CCR4-NOT
  • GV-to-MII transition
  • Inosine RNA modifications
  • Oocyte
  • Polysome
  • RNA decay
  • Translation

ASJC Scopus subject areas

  • Catalysis
  • Molecular Biology
  • Spectroscopy
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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