Biomaterial Database

Mouse Heterochromatin Adopts Digital Compaction States without Showing Hallmarks of HP1-Driven Liquid-Liquid Phase Separation. 2020

Fabian Erdel, and Anne Rademacher, and Rifka Vlijm, and Jana Tünnermann, and Lukas Frank, and Robin Weinmann, and Elisabeth Schweigert, and Klaus Yserentant, and Johan Hummert, and Caroline Bauer, and Sabrina Schumacher, and Ahmad Al Alwash, and Christophe Normand, and Dirk-Peter Herten, and Johann Engelhardt, and Karsten Rippe

LBME, Centre de Biologie Intégrative (CBI), CNRS, UPS, Toulouse, France; Division of Chromatin Networks, German Cancer Research Center (DKFZ) and Bioquant, Heidelberg, Germany. Electronic address: fabian.erdel@ibcg.biotoul.fr.

The formation of silenced and condensed heterochromatin foci involves enrichment of heterochromatin protein 1 (HP1). HP1 can bridge chromatin segments and form liquid droplets, but the biophysical principles underlying heterochromatin compartmentalization in the cell nucleus are elusive. Here, we assess mechanistically relevant features of pericentric heterochromatin compaction in mouse fibroblasts. We find that (1) HP1 has only a weak capacity to form liquid droplets in living cells; (2) the size, global accessibility, and compaction of heterochromatin foci are independent of HP1; (3) heterochromatin foci lack a separated liquid HP1 pool; and (4) heterochromatin compaction can toggle between two "digital" states depending on the presence of a strong transcriptional activator. These findings indicate that heterochromatin foci resemble collapsed polymer globules that are percolated with the same nucleoplasmic liquid as the surrounding euchromatin, which has implications for our understanding of chromatin compartmentalization and its functional consequences.

UI	MeSH Term	Description	Entries
D002843	Chromatin	The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.	Chromatins
D002868	Chromosomal Proteins, Non-Histone	Nucleoproteins, which in contrast to HISTONES, are acid insoluble. They are involved in chromosomal functions; e.g. they bind selectively to DNA, stimulate transcription resulting in tissue-specific RNA synthesis and undergo specific changes in response to various hormones or phytomitogens.	Non-Histone Chromosomal Proteins,Chromosomal Proteins, Non Histone,Chromosomal Proteins, Nonhistone,Non-Histone Chromosomal Phosphoproteins,Chromosomal Phosphoproteins, Non-Histone,Non Histone Chromosomal Phosphoproteins,Non Histone Chromosomal Proteins,Nonhistone Chromosomal Proteins,Proteins, Non-Histone Chromosomal
D005347	Fibroblasts	Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.	Fibroblast
D006570	Heterochromatin	The portion of chromosome material that remains condensed and is transcriptionally inactive during INTERPHASE.	Heterochromatins
D000090266	Chromobox Protein Homolog 5	A protein located within beta-heterochromatin that is involved in suppression of POSITION EFFECT VARIEGATION.	HP-1 Protein,Heterochromatin Protein 1,Heterochromatin-Specific Nonhistone Chromosomal Protein HP-1,HP 1 Protein
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D051379	Mice	The common name for the genus Mus.	Mice, House,Mus,Mus musculus,Mice, Laboratory,Mouse,Mouse, House,Mouse, Laboratory,Mouse, Swiss,Mus domesticus,Mus musculus domesticus,Swiss Mice,House Mice,House Mouse,Laboratory Mice,Laboratory Mouse,Mice, Swiss,Swiss Mouse,domesticus, Mus musculus
D022041	Euchromatin	Chromosome regions that are loosely packaged and more accessible to RNA polymerases than HETEROCHROMATIN. These regions also stain differentially in CHROMOSOME BANDING preparations.	Euchromatins