Two key components of mammalian heterochromatin that play a structural role in higher order chromatin organization are the heterochromatin protein 1alpha (HP1alpha) and the linker histone H1. Here, we show that these proteins interact in vivo and in vitro through their hinge and C-terminal domains, respectively. The phosphorylation of H1 by CDK2, which is required for efficient cell cycle progression, disrupts this interaction. We propose that phosphorylation of H1 provides a signal for the disassembly of higher order chromatin structures during interphase, independent of histone H3-lysine 9 (H3-K9) methylation, by reducing the affinity of HP1alpha for heterochromatin.
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http://dx.doi.org/10.1016/j.molcel.2006.04.016 | DOI Listing |
Unlabelled: Compartmentalization of the nucleus into heterochromatin and euchromatin is highly conserved across eukaryotes. Constitutive heterochromatin (C-Het) constitutes a liquid-like condensate that packages the repetitive regions of the genome through the enrichment of histone modification H3K9me3 and recruitment of its cognate reader protein Heterochromatin Protein-1 (HP1a). The ability for well-ordered nucleosome arrays and HP1a to independently form biomolecular condensates suggests that the emergent material properties of C-Het compartments may contribute to its functions such as force-buffering, dosage-dependent gene silencing, and selective permeability.
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Institute of Plant Sciences Paris-Saclay, Centre Nationale de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Evry, Université Paris-Saclay, 91405 Orsay, France.
Nucleosomes, the chromatin building blocks, play an important role in controlling DNA and chromatin accessibility. Nucleosome remodeling and the incorporation of distinct histone variants confer unique structural and biochemical properties, influencing the targeting of multiple epigenetic pathways, particularly DNA methylation. This stable epigenetic mark suppresses transposable element expression in plants and mammals, serving as an additional layer of chromatin regulation.
View Article and Find Full Text PDFProper histone gene expression is critical to cell viability and maintaining genomic integrity. Multiple histone genes organized into three genomic loci encode for replication coupled core and linker histones. Histone gene expression and transcript processing is orchestrated in the histone locus body (HLB) within the nucleus.
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Department of Genetics and Biotechnology, Graduate School of Biotechnology, College of Life Sciences, Kyung Hee University, Yongin, Korea.
Melanosome transport is regulated by major proteins, including Rab27a, Melanophilin (Mlph), and Myosin Va (Myo-Va), that form a tripartite complex. Mutation of these proteins causes melanosome aggregation around the nucleus. Among these proteins, Mlph is a linker between Rab27a and Myo-Va.
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N. N. Blokhin National Medical Research Center of Oncology, Ministry of Health of Russia, 24 Kashirskoe Shosse, 115522 Moscow, Russia.
Previously we discovered that among 15 DNA-binding plant secondary metabolites (PSMs) possessing anticancer activity, 11 compounds cause depletion of the chromatin-bound linker histones H1.2 and/or H1.4.
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