Sm proteins, the constituents of the spliceosome, are components of nuage and mitochondrial cement in Xenopus oocytes

Szczepan M. Bilinski, Mariusz K. Jaglarz, Beata Szymanska, Laurence D. Etkin, Malgorzata Kloc

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

A conserved feature of germ cells in many animal species is the presence of perinuclear electron-dense material called the "nuage" that is believed to be a precursor of germinal (or polar or P) granules. In Xenopus oogenesis the nuage is first observed near the nuclear envelope and subsequently in close contact with mitochondria, at which stage it is called the mitochondrial cement. In this study, we found that, in Xenopus pre-stage I and stage I oocytes, nuage and mitochondrial cement contain the spliceosomal Sm proteins, Xcat2 mRNA, and DEAD-box RNA helicase XVLG1. Other components of Cajal bodies or splicing machinery such as coilin, SMN protein, and snRNAs are absent from the nuage and mitochondrial cement. We suggest that Xenopus Sm proteins have adapted to a role independent of pre-mRNA splicing and that instead of binding to their traditional spliceosomal partner such as snRNA, they bind mRNAs that are the components of germinal granules (i.e., Xcat2 mRNA) and facilitate the transport of these mRNAs from the nucleus to the nuage that is a precursor of germinal granules. In addition, the presence of Vasa-like DEAD-box helicase in Xenopus nuage suggests involvement of nuage in the microRNA and/or RNAi pathway, similar to the role of nuage in Drosophila.

Original languageEnglish (US)
Pages (from-to)171-178
Number of pages8
JournalExperimental Cell Research
Volume299
Issue number1
DOIs
StatePublished - Sep 10 2004

Keywords

  • Germ cells
  • Germinal granules
  • Nuage
  • Sm proteins
  • Xenopus

ASJC Scopus subject areas

  • Cell Biology

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