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14:40
Expression Analysis of Mammalian Linker-histone Subtypes
Published on: March 19, 2012
H2A.Z nucleosomes enriched over active genes are homotypic
Christopher M Weber1, Jorja G Henikoff, Steven Henikoff
1Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
Nature Structural & Molecular Biology
|November 9, 2010
Summary
Homotypic histone variant H2A.Z nucleosomes are enriched near active promoters, unlike heterotypic ones. Their distribution suggests structural differences influence gene regulation during transcription.
Area of Science:
- Molecular Biology
- Genetics
- Chromatin Biology
Background:
- Histone variants, like H2A.Z, are crucial for gene regulation.
- Nucleosomes can be homotypic (two H2A.Z) or heterotypic (one H2A.Z, one H2A).
- The precise role and distribution patterns of H2A.Z nucleosome types remain unclear.
Purpose of the Study:
- To investigate the distribution and function of homotypic and heterotypic H2A.Z nucleosomes.
- To understand the mechanistic basis for H2A.Z enrichment at specific genomic locations.
- To correlate H2A.Z nucleosome distribution with transcriptional activity.
Main Methods:
- High-resolution mapping of homotypic and heterotypic Drosophila H2A.Z (H2Av) nucleosomes.
- Genome-wide analysis of nucleosome distribution relative to genomic features.
- Comparison of H2A.Z nucleosome patterns with classical active chromatin marks.
Main Results:
- Homotypic H2A.Z nucleosomes were enriched downstream of active promoters and intron-exon junctions.
- Heterotypic H2A.Z nucleosomes were depleted in these same regions.
- Homotypic H2A.Z nucleosome distribution mirrored active chromatin and was disrupted during transcriptional elongation.
- Both homotypic H2A.Z nucleosomes and active chromatin were depleted downstream of paused polymerases.
Conclusions:
- H2A.Z enrichment patterns are determined by the homotypic/heterotypic composition of nucleosomes.
- Intrinsic structural differences between homotypic and heterotypic H2A.Z nucleosomes impact their genomic distribution.
- These differences, revealed after disruption during transcription, are key to H2A.Z's role in gene regulation.
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