Np95 is implicated in pericentromeric heterochromatin replication and in major satellite silencing

Roberto Papait, Christian Pistore, Diego Negri, Daniela Pecoraro, Lisa Cantarini, Ian Marc Bonapace

Research output: Contribution to journalArticle


Heterochromatin plays an important role in transcriptional repression, for the correct segregation of chromosomes and in the maintenance of genome stability. Pericentric heterochromatin (PH) replication and formation have been proposed to occur in the pericentric heterochromatin duplication body (pHDB). A central question is how the underacetylated state of heterochromatic histone H4 tail is established and controlled, because it is a key event during PH replication and is essential to maintain the compacted and silenced state of these regions. Np95 is a cell cycle regulated and is a nuclear histone-binding protein that also recruits HDAC-1 to target promoters. It is essential for S phase and for embryonic formation and is implicated in chromosome stability. Here we show that Np95 is part of the pHDB, and its functional ablation causes a strong reduction in PH replication. Depletion of Np95 also causes a hyperacetylation of lysines 8, 12, and 16 of heterochromatin histone H4 and an increase of pericentromeric major satellite transcription, whose RNAs are key players for heterochromatin formation. We propose that Np95 is a new relevant protein involved in heterochromatin replication and formation.

Original languageEnglish
Pages (from-to)1098-1106
Number of pages9
JournalMolecular Biology of the Cell
Issue number3
Publication statusPublished - Mar 2007


ASJC Scopus subject areas

  • Cell Biology
  • Genetics
  • Molecular Biology

Cite this