hnRNP M interacts with PSF and p54(nrb) and co-localizes within defined nuclear structures

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Updated: Jun 19, 2026

Visualization of Protein-protein Interaction in Nuclear and Cytoplasmic Fractions by Co-immunoprecipitation and In Situ Proximity Ligation Assay
10:05

Visualization of Protein-protein Interaction in Nuclear and Cytoplasmic Fractions by Co-immunoprecipitation and In Situ Proximity Ligation Assay

Published on: January 16, 2017

Marija Marko1, Michael Leichter, Meropi Patrinou-Georgoula

  • 1RNA Processing Laboratory, Institute of Biological Research and Biotechnology, National Hellenic Research Foundation, 48 Vas. Constantinou Avenue, 11635 Athens, Greece.

Experimental Cell Research
|October 31, 2009
PubMed

Insights

Heterogeneous nuclear ribonucleoprotein M (hnRNP M) interacts with PSF and p54(nrb), influencing RNA splicing. Co-expression studies reveal hnRNP M promotes exon skipping, while PSF favors inclusion, with hnRNP M reverting PSF

Area of Science:

  • Molecular Biology
  • RNA Biology
  • Gene Regulation

Background:

  • Heterogeneous nuclear ribonucleoprotein M (hnRNP M) is abundant and influences pre-mRNA splicing patterns.
  • hnRNP M interacts with early spliceosomes, suggesting a role in RNA processing.

Purpose of the Study:

  • To identify new binding partners of hnRNP M.
  • To investigate the functional implications of hnRNP M interactions in RNA splicing.

Main Methods:

  • Immunoprecipitation and pull-down assays to identify protein interactions.
  • Co-localization studies using nuclear paraspeckles.
  • Co-fractionation analysis in biochemical nuclear matrix preparations.
  • Transfection studies with a preprotachykinin (PPT) minigene to assess splicing modulation.

Main Results:

  • PSF (polypyrimidine tract-binding protein-associated splicing factor) and p54(nrb) were identified as novel binding partners of hnRNP M.
  • hnRNP M co-localizes with PSF in nuclear paraspeckles and co-fractionates with PSF and p54(nrb) in nuclear matrix preparations.
  • hnRNP M expression promoted exon skipping in PPT minigene splicing, whereas PSF expression favored exon inclusion.
  • Co-expression of hnRNP M reverted the exon inclusion effect of PSF.

Conclusions:

  • PSF and p54(nrb) are new hnRNP M binding partners involved in transcription and RNA processing.
  • hnRNP M and PSF play opposing roles in the alternative splicing of the PPT pre-mRNA.
  • These findings provide insights into the hnRNP M interaction network and its functional role in splicing regulation.

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