Epigenetic memory independent of symmetric histone inheritance

Abstract
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Abstract

Heterochromatic gene silencing is an important form of gene regulation that usually requires specific histone modifications. A popular model posits that inheritance of modified histones, especially in the form of H3-H4 tetramers, underlies inheritance of heterochromatin. Because H3-H4 tetramers are randomly distributed between daughter chromatids during DNA replication, rare occurrences of asymmetric tetramer inheritance within a heterochromatic domain would have the potential to destabilize heterochromatin. This model makes a prediction that shorter heterochromatic domains would experience unbalanced tetramer inheritance more frequently, and thereby be less stable. In contrast to this prediction, we found that shortening a heterochromatic domain in Saccharomyces had no impact on the strength of silencing nor its heritability. Additionally, we found that replisome mutations that disrupt inheritance of H3-H4 tetramers had only minor effects on heterochromatin stability. These findings suggest that histones carry little or no memory of the heterochromatin state through DNA replication.

Data availability

Sequencing data have been deposited in GEO under accession code GSE136897.

The following data sets were generated

1. Saxton DS
2. Rine J
(2019) Nucleosome profiles in strains with different numbers of nucleosomes at HML and HMR
NCBI Gene Expression Omnibus, GSE136897.

https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE136897

Article and author information

Author details

Daniel S Saxton

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-7152-7780
Jasper Rine

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States

For correspondence
jrine@berkeley.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-2297-9814

Funding

National Institutes of Health (GM 031105)

Jasper Rine

National Institutes of Health (GM 120374)

Jasper Rine

National Science Foundation (DGE 1752814)

Daniel S Saxton

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.