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The protein Aly links pre-messenger-RNA splicing to nuclear export in metazoans

Z Zhou1, M J Luo, K Straesser

  • 1Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.

Nature
|October 3, 2000
PubMed

Insights

Splicing enhances messenger RNA (mRNA) export in metazoans. The protein Aly links these processes by binding spliced mRNA, promoting its efficient transport from the nucleus to the cytoplasm.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Metazoan pre-messenger RNAs (pre-mRNAs) contain introns removed by splicing.
  • Spliced mRNAs are exported from the nucleus to the cytoplasm.
  • The mechanism coupling splicing and mRNA export is currently unknown.

Purpose of the Study:

  • To investigate the mechanism coupling pre-mRNA splicing and mRNA export.
  • To identify factors involved in linking these two essential cellular processes.

Main Methods:

  • Recruitment assays of Aly protein to different messenger ribonucleoprotein (mRNP) complexes.
  • Analysis of Aly protein association with spliced and unspliced mRNAs.
  • Investigation of Aly shuttling and its effect on mRNA export rates in vivo.
  • Co-localization studies of Aly with splicing factors.

Main Results:

  • Aly, a homolog of yeast mRNA export factor Yralp, is recruited specifically to spliced mRNPs.
  • Aly does not associate with mRNPs from intronless mRNAs or heterogeneous nuclear RNP (hnRNP) complexes.
  • Aly is recruited during spliceosome assembly and tightly associates with spliced mRNPs.
  • Aly shuttles between the nucleus and cytoplasm, and its overexpression enhances mRNA export rate and efficiency.
  • Aly co-localizes with nuclear splicing factors, confirming splicing-dependent recruitment.

Conclusions:

  • Splicing is essential for efficient mRNA export in metazoans.
  • The protein Aly acts as a crucial link between the splicing machinery and the mRNA export pathway.
  • Aly's recruitment to spliced mRNPs facilitates their subsequent export to the cytoplasm.

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