Intranuclear sphingomyelin is associated with transcriptionally active chromatin and plays a role in nuclear integrity

Catia Scassellati, Elisabetta Albi, Dusan Cmarko, Cinzia Tiberi, Jana Cmarkova, Cedric Bouchet-Marquis, Pernette J. Verschure, Roel Van Driel, Mariapia Viola Magni, Stanislav Fakan

Research output: Contribution to journalArticlepeer-review

Abstract

Background information. Sphingomyelin is one of the major phospholipids in the cell nucleus. However, its intranuclear distribution with regard to different functional nuclear domains as well as its possible involvement in the nuclear functional architecture remains to be elucidated. Results. We carried out an ultrastructural cytochemical study of the intranuclear distribution of SM (sphingomyelin) using an in situ binding assay of neutral SMase (sphingomyelinase) conjugated to colloidal gold particles. The enzymatic labelling was carried out on ultrathin sections of different mammalian cells prepared by means of various fixation and resin-embedding protocols. Transmission electron microscopic analysis revealed preferential localization of SM within the PR (perichromatin region), a functionally important nucleoplasmic domain containing sites of pre-mRNA synthesis and processing. In the nucleolus, SM is mostly associated with the dense fibrillar component containing transcriptionally active ribosomal genes. Microinjection of enzymatically active SMase into living cells resulted in a rapid degradation of intranuclear structure. Conclusions. Our observations, supported by biochemical data, provide evidence for the involvement of SM in important nuclear functions. They bring additional information pointing out the PR as an essential functional nuclear domain. Furthermore, they suggest a role for SM in the internal nuclear architecture.

Original languageEnglish
Pages (from-to)361-375
Number of pages15
JournalBiology of the cell / under the auspices of the European Cell Biology Organization
Volume102
Issue number6
DOIs
Publication statusPublished - Jun 2010

Keywords

  • Active chromatin
  • Intranuclear sphingomyelin
  • Nuclear integrity
  • Ultrastructural cytochemistry

ASJC Scopus subject areas

  • Cell Biology
  • Medicine(all)

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