STAG2 promotes the myelination transcriptional program in oligodendrocytes
Curation statements for this article:-
Curated by eLife
Evaluation Summary:
This manuscript will be of interest to scientists working on genome organisation and transcriptional control of myelination during mammalian brain development. The authors combine diverse and complimentary experimental approaches to generate insights into how DNA looping contributes to transcriptional regulation in functionally specialised cell types. The experiments have been rigorously performed and the main conclusions are justified.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1, Reviewer #2 and Reviewer #3 agreed to share their name with the authors.)
This article has been Reviewed by the following groups
Listed in
- Evaluated articles (eLife)
Abstract
Cohesin folds chromosomes via DNA loop extrusion. Cohesin-mediated chromosome loops regulate transcription by shaping long-range enhancer–promoter interactions, among other mechanisms. Mutations of cohesin subunits and regulators cause human developmental diseases termed cohesinopathy. Vertebrate cohesin consists of SMC1, SMC3, RAD21, and either STAG1 or STAG2. To probe the physiological functions of cohesin, we created conditional knockout (cKO) mice with Stag2 deleted in the nervous system. Stag2 cKO mice exhibit growth retardation, neurological defects, and premature death, in part due to insufficient myelination of nerve fibers. Stag2 cKO oligodendrocytes exhibit delayed maturation and downregulation of myelination-related genes. Stag2 loss reduces promoter-anchored loops at downregulated genes in oligodendrocytes. Thus, STAG2-cohesin generates promoter-anchored loops at myelination-promoting genes to facilitate their transcription. Our study implicates defective myelination as a contributing factor to cohesinopathy and establishes oligodendrocytes as a relevant cell type to explore the mechanisms by which cohesin regulates transcription.
Article activity feed
-
-
Evaluation Summary:
This manuscript will be of interest to scientists working on genome organisation and transcriptional control of myelination during mammalian brain development. The authors combine diverse and complimentary experimental approaches to generate insights into how DNA looping contributes to transcriptional regulation in functionally specialised cell types. The experiments have been rigorously performed and the main conclusions are justified.
(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1, Reviewer #2 and Reviewer #3 agreed to share their name with the authors.)
-
Reviewer #1 (Public Review):
The authors generate a conditional mouse model of the STAG2 cohesin protein and use it to abolish STAG2 function in the brain. The authors show that while inactivation of STAG2 in the entire embryo is lethal, brain-specific STAG2 inactivation is compatible with development. However, such mice show neurological defects. The authors find that nerve fibre myelination is defective and focus on defective cohesin function in oligodendrocytes as the major cause of the myelination defects. They show misregulation of a subset of genes, which are enriched for those involved in cholesterol biosynthesis. Genome-wider chromosome capture experiments in oligodendrocytes found that coarse-range chromosome structure was not affected, however, the authors find effects on gene-looping. The results provide a framework for …
Reviewer #1 (Public Review):
The authors generate a conditional mouse model of the STAG2 cohesin protein and use it to abolish STAG2 function in the brain. The authors show that while inactivation of STAG2 in the entire embryo is lethal, brain-specific STAG2 inactivation is compatible with development. However, such mice show neurological defects. The authors find that nerve fibre myelination is defective and focus on defective cohesin function in oligodendrocytes as the major cause of the myelination defects. They show misregulation of a subset of genes, which are enriched for those involved in cholesterol biosynthesis. Genome-wider chromosome capture experiments in oligodendrocytes found that coarse-range chromosome structure was not affected, however, the authors find effects on gene-looping. The results provide a framework for understanding the pathogenicity of cohesin mutations in humans.
-
Reviewer #2 (Public Review):
The folding of chromosomes during interphase is controlled by two cohesin complexes, which share several common subunits but contain either STAG1 or STAG2. Mutations in the STAG proteins, as well as other cohesin subunits, are associated with developmental disease and cancer in humans.
This paper studies the function of STAG2 cohesin during neural development using a CRE/LOX approach to delete the gene in neural stem cells that give rise to a variety of functionally specialised cell types in the brain. This caused abnormal growth and neurological defects, and transcriptional analysis highlighted the cholesterol biosynthesis pathway, which is known to be important for myelination, as preferentially affected. Accordingly, histological analysis revealed that the brains of STAG2 mutant mice had fewer myelin …
Reviewer #2 (Public Review):
The folding of chromosomes during interphase is controlled by two cohesin complexes, which share several common subunits but contain either STAG1 or STAG2. Mutations in the STAG proteins, as well as other cohesin subunits, are associated with developmental disease and cancer in humans.
This paper studies the function of STAG2 cohesin during neural development using a CRE/LOX approach to delete the gene in neural stem cells that give rise to a variety of functionally specialised cell types in the brain. This caused abnormal growth and neurological defects, and transcriptional analysis highlighted the cholesterol biosynthesis pathway, which is known to be important for myelination, as preferentially affected. Accordingly, histological analysis revealed that the brains of STAG2 mutant mice had fewer myelin fibres. Using a combination of single-cell and bulk RNA sequencing the authors found that oligodendrocytes, which are responsible for myelination, were present at roughly normal proportions among cells of the brain, but had altered gene expression patterns, including in cholesterol biosynthesis genes. Analysis of DNA looping by chromosome conformation capture revealed that STAG2 deletion affected the formation of short DNA loops emanating from promoters, but not longer-range units of genome organisation such as TADs and compartments.
Overall, this manuscript contains an impressive body of work that advances our understanding of how specialised cohesin complexes contribute to cell-type-specific transcription and genome organisation. To the best of my knowledge, the experiments have been performed to a high standard, and use diverse but appropriate methodologies.
-
Reviewer #3 (Public Review):
The authors investigated the role of STAG2, one of the cohesin complex subunits, in developing CNS, by using the Nex-Cre system. Conditional Stag2 KO in the CNS leads to neurological defects and premature death. RNAseq analysis from Stag2 ablated brain revealed changes in expression of myelin-related genes, correlating with defective myelin fiber formation. By single-cell RNAseq from Stag2 ablated brain, the authors revealed a maturation defect of Stag2 deleted oligodendrocytes (OLs), and RNAseq from purified OLs revealed changes in cholesterol biosynthesis-related genes, possibly underling the myelination defects. HiC studies revealed that Stag2 deficiency mainly leaves A and B compartments and TADs unaffected, while the number and strength of Promoter anchored loops were decreased genome-wide and at the …
Reviewer #3 (Public Review):
The authors investigated the role of STAG2, one of the cohesin complex subunits, in developing CNS, by using the Nex-Cre system. Conditional Stag2 KO in the CNS leads to neurological defects and premature death. RNAseq analysis from Stag2 ablated brain revealed changes in expression of myelin-related genes, correlating with defective myelin fiber formation. By single-cell RNAseq from Stag2 ablated brain, the authors revealed a maturation defect of Stag2 deleted oligodendrocytes (OLs), and RNAseq from purified OLs revealed changes in cholesterol biosynthesis-related genes, possibly underling the myelination defects. HiC studies revealed that Stag2 deficiency mainly leaves A and B compartments and TADs unaffected, while the number and strength of Promoter anchored loops were decreased genome-wide and at the level of downregulated genes. Altogether, this data extends our knowledge of the role of cohesin and 3D chromatin architecture in brain development.
-
-