Nucleosome assembly and epigenetic inheritance

Abstract

In eukaryotic cells, histones are packaged into octameric core particles with DNA wrapping around to form nucleosomes, which are the basic units of chromatin (Kornberg and Thomas, 1974). Multicellular organisms utilise chromatin marks to translate one single genome into hundreds of epigenomes for their corresponding cell types. Inheritance of epigenetic status is critical for the maintenance of gene expression profile during mitotic cell divisions . During S phase, canonical histones are deposited onto DNA in a replication-coupled manner . To understand how dividing cells overcome the dilution of epigenetic marks after chromatin duplication, DNA replication coupled (RC) nucleosome assembly has been of great interest. In this review, we focus on the potential influence of RC nucleosome assembly processes on the maintenance of epigenetic status.

Nucleolar protein Spindlin1 recognizes H3K4 methylation and stimulates the expression of rRNA genes

“…Spindlin1 has been reported to be a tandem Tudor‐like domain‐containing protein (Zhao et al , 2007) associated with the meiotic spindle (Oh et al , 1997). Because of our research interest in histone modification‐mediated mitotic epigenetic inheritance (Xu & Zhu, 2010; Xu et al , 2010; Chen et al , 2011; Wu & Zhu, 2011), we decided to investigate whether Spindlin1 might be a histone lysine methylation‐binding protein that specifies the kinetochore. To our surprise, indirect immunofluorescence staining with antibodies specific for Spindlin1 showed that little Spindlin1 was localized to the mitotic spindle or centromeres in prometaphase, anaphase and telophase mouse embryonic fibroblast cells (supplementary Fig S1A–C online).…”

Epigenetic inheritance: Uncontested?

“…In order to be heritable, pre-existing modifications should, at least to some extent, be able to serve as templates to guide the reestablishment of the same modifications on newly deposited histones [62]. Considering that the vast majority of histone H3-H4 tetramers segregate in a conservative manner [26,27,40], the most likely templates might be adjacent pre-existing nucleosomes in cis (Figure 2).…”

Epigenetic inheritance mediated by histone lysine methylation: maintaining transcriptional states without the precise restoration of marks?

“…Histone modifications are also believed to be major carriers of epigenetic information. However, how the epigenetic information carried by histone modifications or histone variants is inherited during mitotic cell division remains an interesting but not fully resolved question [9][10][11][12][13][14]. In this review, we focus on the inheritance of epigenetic information carried by histone modifications.…”