Abstract
Endogenous retroviruses (ERVs) comprise a significant portion of mammalian genomes. Although specific ERV loci feature regulatory roles for host gene expression, most ERV integrations are transcriptionally repressed by Setdb1-mediated H3K9me3 and DNA methylation. However, the protein network which regulates the deposition of these chromatin modifications is still incompletely understood. Here, we perform a genome-wide single guide RNA (sgRNA) screen for genes involved in ERV silencing and identify the GHKL ATPase protein Morc3 as a top-scoring hit. Morc3 knock-out (ko) cells display de-repression, reduced H3K9me3, and increased chromatin accessibility of distinct ERV families. We find that the Morc3 ATPase cycle and Morc3 SUMOylation are important for ERV chromatin regulation. Proteomic analyses reveal that Morc3 mutant proteins fail to interact with the histone H3.3 chaperone Daxx. This interaction depends on Morc3 SUMOylation and Daxx SUMO binding. Notably, in Morc3 ko cells, we observe strongly reduced histone H3.3 on Morc3 binding sites. Thus, our data demonstrate Morc3 as a critical regulator of Daxx-mediated histone H3.3 incorporation to ERV regions. Endogenous retroviruses (ERVs) compose a significant portion of mammalian genomes;however, how ERVs are regulated is not well known. Here the authors performed a genome-wide sgRNA screen to identify Morc3 as a mediator of ERV silencing. They show Morc3 associates with the H3.3 chaperone Daxx, and that loss of Morc3 leads to reduced H3.3 at ERVs.
| Dokumententyp: | Zeitschriftenartikel |
|---|---|
| Fakultät: | Medizin |
| Themengebiete: | 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit |
| Sprache: | Englisch |
| Dokumenten ID: | 98592 |
| Datum der Veröffentlichung auf Open Access LMU: | 05. Jun. 2023, 15:29 |
| Letzte Änderungen: | 17. Okt. 2023, 14:59 |
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