GH1-HMGA proteins restrict RNA-directed DNA methylation and antagonize linker histone H1 at euchromatic transposable elements
Abstract
In plant genomes, transposable elements (TEs) are silenced by CG and non-CG DNA methylation, with non-CG methylation maintained by CMT chromomethylases and the RNA-directed DNA methylation (RdDM) pathway. In Arabidopsis, linker histone H1 differentially influences these pathways, as loss of H1 causes non-CG hypermethylation at pericentromeric TEs but hypomethylation at euchromatic TEs in gene-rich regions. The molecular basis of this antagonism has remained unclear. Here, we show that GH1-HMGAs, a family of H1-related High Mobility Group proteins, bind AT-rich sequences at euchromatic TEs and prevent RdDM-dependent non-CG methylation by limiting siRNA accumulation. Furthermore, GH1-HMGA and H1 compete for chromatin association at these TEs, as loss of GH1-HMGA triggers ectopic H1 redistribution, while loss of H1 increases GH1-HMGA enrichment, providing a mechanistic explanation for the non-CG hypomethylation observed in h1 mutants. Collectively, these findings reveal how GH1-HMGA proteins specifically restrain RdDM activity at euchromatic TEs and elucidate how the H1/GH1-HMGA balance spatially partitions distinct DNA methylation pathways across the genome.
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BibTeX
@misc{feit2026gh1hmga,
title = {{GH1-HMGA proteins restrict RNA-directed DNA methylation and antagonize linker histone H1 at euchromatic transposable elements}},
author = {Léa Feit and Alejandro Edera and Emmanuel Vanrobays and Lauriane Simon and Delphine Dardalhon-Cuménal and Saad En Naimani and Zdravko J Lorković and Frederic Berger and Fredy Barneche and Christophe Tatout and Leandro Quadrana and Aline V Probst and Simon Amiard},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.64898/2026.09.08.749845},
url = {https://hal.science/hal-05778251v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - GH1-HMGA proteins restrict RNA-directed DNA methylation and antagonize linker histone H1 at euchromatic transposable elements
AU - Léa Feit
AU - Alejandro Edera
AU - Emmanuel Vanrobays
AU - Lauriane Simon
AU - Delphine Dardalhon-Cuménal
AU - Saad En Naimani
AU - Zdravko J Lorković
AU - Frederic Berger
AU - Fredy Barneche
AU - Christophe Tatout
AU - Leandro Quadrana
AU - Aline V Probst
AU - Simon Amiard
PY - 2026
DA - 2026/09/08
PB - HAL
DO - 10.64898/2026.09.08.749845
UR - https://hal.science/hal-05778251v1
AB - In plant genomes, transposable elements (TEs) are silenced by CG and non-CG DNA methylation, with non-CG methylation maintained by CMT chromomethylases and the RNA-directed DNA methylation (RdDM) pathway. In Arabidopsis, linker histone H1 differentially influences these pathways, as loss of H1 causes non-CG hypermethylation at pericentromeric TEs but hypomethylation at euchromatic TEs in gene-rich regions. The molecular basis of this antagonism has remained unclear. Here, we show that GH1-HMGAs, a family of H1-related High Mobility Group proteins, bind AT-rich sequences at euchromatic TEs and prevent RdDM-dependent non-CG methylation by limiting siRNA accumulation. Furthermore, GH1-HMGA and H1 compete for chromatin association at these TEs, as loss of GH1-HMGA triggers ectopic H1 redistribution, while loss of H1 increases GH1-HMGA enrichment, providing a mechanistic explanation for the non-CG hypomethylation observed in h1 mutants. Collectively, these findings reveal how GH1-HMGA proteins specifically restrain RdDM activity at euchromatic TEs and elucidate how the H1/GH1-HMGA balance spatially partitions distinct DNA methylation pathways across the genome.
ER -