Unraveling the organization of the internal nuclear matrix: RNA-dependent anchoring of NuMA to a lamin scaffold

Paola Barboro, Cristina D'Arrigo, Alberto Diaspro, Michele Mormino, Ingles Alberti, Silvio Parodi, Eligio Patrone, Cecilia Balbi

Research output: Contribution to journalArticlepeer-review

Abstract

Using quantitative immunoelectron microscopy we show here that when the nuclear matrix is isolated from rat hepatocytes in the presence of an inhibitor of RNase activity both lamins and the nuclear mitotic apparatus protein (NuMA) preferentially localize within the electron-dense domains of the internal nuclear matrix (INM). After RNA digestion NuMA undergoes a sharp depletion, while labeling by an antibody against lamins A and C within the electron-transparent regions increases, suggesting that a subset of lamin epitopes is masked by the interaction with RNA. We were able to explain this result by visualizing for the first time a thin web of lamin protofibrils which connects the electron-dense regions. Confirmation of these changes has been obtained by immunoblot analysis and confocal microscopy. As RNA digestion results both in the release of NuMA and in the collapse of the INM, we propose that a fraction of nuclear RNA brings about the association of NuMA islands with a lamin scaffold and that this interaction is required to maintain the latter in a state of high molecular dispersion.

Original languageEnglish
Pages (from-to)202-218
Number of pages17
JournalExperimental Cell Research
Volume279
Issue number2
DOIs
Publication statusPublished - 2002

Keywords

  • Confocal microscopy
  • Immunoelectron microscopy
  • Nuclear matrix
  • Nuclear proteins
  • RNA

ASJC Scopus subject areas

  • Cell Biology

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