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Review
. 2014 Apr 1;28(7):672-82.
doi: 10.1101/gad.238873.114.

Histone variants: dynamic punctuation in transcription

Christopher M Weber  1 , Steven Henikoff
Affiliations
Review

Histone variants: dynamic punctuation in transcription

Christopher M Weber et al. Genes Dev. .

Abstract

Eukaryotic gene regulation involves a balance between packaging of the genome into nucleosomes and enabling access to regulatory proteins and RNA polymerase. Nucleosomes are integral components of gene regulation that restrict access to both regulatory sequences and the underlying template. Whereas canonical histones package the newly replicated genome, they can be replaced with histone variants that alter nucleosome structure, stability, dynamics, and, ultimately, DNA accessibility. Here we consider how histone variants and their interacting partners are involved in transcriptional regulation through the creation of unique chromatin states.

Keywords: gene regulation; histone chaperones; nucleosome dynamics; nucleosome remodeling.

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Figures

Figure 1.
Figure 1.
(A) Structure of nucleosome core particle, showing that (H3/H4)2 is at the center of the DNA wrap, with two dimers of H2A/H2B docked at the edges, near the DNA entry and exit locations. (B) Nucleosomes modulate access to transcription factor (TF)-binding sites. Transient DNA unwrapping exposes transcription factor-binding sites. As nucleosomes unwrap, H2A/H2B dimers can be lost, exposing more DNA, and when the nucleosome is completely unwrapped, (H3/H4)2 is lost, and DNA is completely exposed.
Figure 2.
Figure 2.
(A, top) The H2A.Z futile cycle of deposition by Swr1 or orthologous complexes and then removal by Ino80, Anp32E, or Swr1 when H3K56 is acetylated. (Bottom) H2A.Z enrichment patterns and promoter architecture differences in different organisms. (B) macroH2A is deposited in the inactive X (Xi) and inactive/active genes on autosomes. (C) H3.3 deposition is mediated by the HIRA complex at genes and regulatory elements, whereas Atrx and Daxx mediate H3.3 incorporation at telomeres and pericentric heterochromatin. It is not clear how H3.3 is enriched at some cis-regulatory elements.
Figure 3.
Figure 3.
Models to explain the general role of histone variants and their deposition pathways on transcriptional regulation. Plus or minus expression level denotes the effect of the variant on transcriptional output.
See this image and copyright information in PMC

References

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