SMCHD1 maintains heterochromatin, genome compartments and epigenome landscape in human myoblasts

Abstract Mammalian genomes are subdivided into euchromatic A compartments that contain mostly active chromatin, and inactive, heterochromatic B compartments. However, it is not well understood how A and B genome compartments are established and maintained. Here we study SMCHD1, an SMC-like protein b...

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Main Authors: Zhijun Huang, Wei Cui, Ishara Ratnayake, Kristin L. Gallik, Lorna Cohen, Rabi Tawil, Gerd P. Pfeifer
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-62211-0
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author Zhijun Huang
Wei Cui
Ishara Ratnayake
Kristin L. Gallik
Lorna Cohen
Rabi Tawil
Gerd P. Pfeifer
author_facet Zhijun Huang
Wei Cui
Ishara Ratnayake
Kristin L. Gallik
Lorna Cohen
Rabi Tawil
Gerd P. Pfeifer
author_sort Zhijun Huang
collection DOAJ
description Abstract Mammalian genomes are subdivided into euchromatic A compartments that contain mostly active chromatin, and inactive, heterochromatic B compartments. However, it is not well understood how A and B genome compartments are established and maintained. Here we study SMCHD1, an SMC-like protein best known for its role in X chromosome inactivation, in human male myoblasts. SMCHD1 colocalizes with Lamin B1 and the heterochromatin mark H3K9me3. Loss of SMCHD1 leads to extensive heterochromatin and Lamin B1 depletion at the nuclear lamina, acquisition of active chromatin states and increased DNA methylation along chromosomes. In absence of SMCHD1, long range intra-chromosomal contacts between B compartments are lost while many new TADs and loops are formed. Inactivation of SMCHD1 promotes numerous B to A compartment transitions accompanied by activation of silenced genes. The data suggests that SMCHD1 functions as an anchor for heterochromatin domains at the nuclear lamina ensuring that these domains are poorly accessible to DNA methyltransferases and to epigenome modification enzymes that typically operate in active chromatin. Thus, the properties of SMCHD1 in heterochromatin maintenance extend well beyond its role in X chromosome inactivation.
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issn 2041-1723
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publishDate 2025-07-01
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spelling doaj-art-86a974eab59a4eb5859c98ce515b1fa02025-08-20T03:46:09ZengNature PortfolioNature Communications2041-17232025-07-0116112110.1038/s41467-025-62211-0SMCHD1 maintains heterochromatin, genome compartments and epigenome landscape in human myoblastsZhijun Huang0Wei Cui1Ishara Ratnayake2Kristin L. Gallik3Lorna Cohen4Rabi Tawil5Gerd P. Pfeifer6Department of Epigenetics, Van Andel InstituteDepartment of Epigenetics, Van Andel InstituteCryo-EM Core, Van Andel InstituteOptical Imaging Core, Van Andel InstituteOptical Imaging Core, Van Andel InstituteDepartment of Neurology, University of Rochester Medical CenterDepartment of Epigenetics, Van Andel InstituteAbstract Mammalian genomes are subdivided into euchromatic A compartments that contain mostly active chromatin, and inactive, heterochromatic B compartments. However, it is not well understood how A and B genome compartments are established and maintained. Here we study SMCHD1, an SMC-like protein best known for its role in X chromosome inactivation, in human male myoblasts. SMCHD1 colocalizes with Lamin B1 and the heterochromatin mark H3K9me3. Loss of SMCHD1 leads to extensive heterochromatin and Lamin B1 depletion at the nuclear lamina, acquisition of active chromatin states and increased DNA methylation along chromosomes. In absence of SMCHD1, long range intra-chromosomal contacts between B compartments are lost while many new TADs and loops are formed. Inactivation of SMCHD1 promotes numerous B to A compartment transitions accompanied by activation of silenced genes. The data suggests that SMCHD1 functions as an anchor for heterochromatin domains at the nuclear lamina ensuring that these domains are poorly accessible to DNA methyltransferases and to epigenome modification enzymes that typically operate in active chromatin. Thus, the properties of SMCHD1 in heterochromatin maintenance extend well beyond its role in X chromosome inactivation.https://doi.org/10.1038/s41467-025-62211-0
spellingShingle Zhijun Huang
Wei Cui
Ishara Ratnayake
Kristin L. Gallik
Lorna Cohen
Rabi Tawil
Gerd P. Pfeifer
SMCHD1 maintains heterochromatin, genome compartments and epigenome landscape in human myoblasts
Nature Communications
title SMCHD1 maintains heterochromatin, genome compartments and epigenome landscape in human myoblasts
title_full SMCHD1 maintains heterochromatin, genome compartments and epigenome landscape in human myoblasts
title_fullStr SMCHD1 maintains heterochromatin, genome compartments and epigenome landscape in human myoblasts
title_full_unstemmed SMCHD1 maintains heterochromatin, genome compartments and epigenome landscape in human myoblasts
title_short SMCHD1 maintains heterochromatin, genome compartments and epigenome landscape in human myoblasts
title_sort smchd1 maintains heterochromatin genome compartments and epigenome landscape in human myoblasts
url https://doi.org/10.1038/s41467-025-62211-0
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