SATB1 Regulates 3D Genome Architecture in T cells by Constraining Chromatin Interactions surrounding CTCF-binding sites [RNA-seq]
Ontology highlight
ABSTRACT: Spatial genome organization is critical for precise gene regulation during development. Special AT-rich sequence binding protein 1 (SATB1) has long been proposed to act as a global chromatin loop organizer in T cells. However, the exact functions of SATB1 in genome organization remain elusive. Here we show that the depletion of SATB1 in human and murine T cells led to transcriptional dysregulation for genes involved in T cell activation, as well as alterations of 3D genome architecture at multiple scales, including the A/B compartment, topologically associating domains (TADs), and loops. Importantly, SATB1 extensively colocalizes with CTCF throughout the genome. Depletion of SATB1 led to increased chromatin contacts among and across the SATB1/CTCF co-occupied sites, thereby affecting the transcription of critical genes involved in T cell activation. The loss of SATB1 did not affect the genome-wide occupancy of CTCF, but significantly reduced the retention of CTCF in the nuclear matrix. Collectively, our data reveal that SATB1 constrains chromatin topology surrounding CTCF-binding sites by tethering CTCF to the nuclear matrix, and suggest that the functional interplay between SATB1 and CTCF contributes to 3D genome organization.
Project description:SATB1, a nuclear matrix-associated protein, has long been proposed to function as a global chromatin loop organizer in T cells. However, the precise roles of SATB1 in chromatin organization remain elusive. Here we show that the depletion of SATB1 in immortalized T cells led to pronounced changes in gene expression, particularly for genes involved in cell proliferation and T cell activation, as well as 3D genome architecture at multiple scales, including the A/B compartment, topologically associating domains (TADs), and loops. Importantly, SATB1 extensively colocalizes with CTCF throughout the genome. Depletion of SATB1 led to increased association among the SATB1/CTCF co-occupied sites, as well as increased chromatin contacts across these sites, thereby altering the genome-wide chromatin loop landscape. SATB1 does not regulate genome architecture by modulating CTCF occupancy. Rather, the topological effects imposed by SATB1 may be attributed to SATB1-dependent anchoring of CTCF to the salt extraction-resistant nuclear matrix. Together, our findings suggest that the functional interplay between nuclear matrix and CTCF plays a critical role in orchestrating 3D genome organization.
Project description:SATB1, a nuclear matrix-associated protein, has long been proposed to function as a global chromatin loop organizer in T cells. However, the precise roles of SATB1 in chromatin organization remain elusive. Here we show that the depletion of SATB1 in immortalized T cells led to pronounced changes in gene expression, particularly for genes involved in cell proliferation and T cell activation, as well as 3D genome architecture at multiple scales, including the A/B compartment, topologically associating domains (TADs), and loops. Importantly, SATB1 extensively colocalizes with CTCF throughout the genome. Depletion of SATB1 led to increased association among the SATB1/CTCF co-occupied sites, as well as increased chromatin contacts across these sites, thereby altering the genome-wide chromatin loop landscape. SATB1 does not regulate genome architecture by modulating CTCF occupancy. Rather, the topological effects imposed by SATB1 may be attributed to SATB1-dependent anchoring of CTCF to the salt extraction-resistant nuclear matrix. Together, our findings suggest that the functional interplay between nuclear matrix and CTCF plays a critical role in orchestrating 3D genome organization.
Project description:SATB1, a nuclear matrix-associated protein, has long been proposed to function as a global chromatin loop organizer in T cells. However, the precise roles of SATB1 in chromatin organization remain elusive. Here we show that the depletion of SATB1 in immortalized T cells led to pronounced changes in gene expression, particularly for genes involved in cell proliferation and T cell activation, as well as 3D genome architecture at multiple scales, including the A/B compartment, topologically associating domains (TADs), and loops. Importantly, SATB1 extensively colocalizes with CTCF throughout the genome. Depletion of SATB1 led to increased association among the SATB1/CTCF co-occupied sites, as well as increased chromatin contacts across these sites, thereby altering the genome-wide chromatin loop landscape. SATB1 does not regulate genome architecture by modulating CTCF occupancy. Rather, the topological effects imposed by SATB1 may be attributed to SATB1-dependent anchoring of CTCF to the salt extraction-resistant nuclear matrix. Together, our findings suggest that the functional interplay between nuclear matrix and CTCF plays a critical role in orchestrating 3D genome organization.
Project description:SATB1, a nuclear matrix-associated protein, has long been proposed to function as a global chromatin loop organizer in T cells. However, the precise roles of SATB1 in chromatin organization remain elusive. Here we show that the depletion of SATB1 in immortalized T cells led to pronounced changes in gene expression, particularly for genes involved in cell proliferation and T cell activation, as well as 3D genome architecture at multiple scales, including the A/B compartment, topologically associating domains (TADs), and loops. Importantly, SATB1 extensively colocalizes with CTCF throughout the genome. Depletion of SATB1 led to increased association among the SATB1/CTCF co-occupied sites, as well as increased chromatin contacts across these sites, thereby altering the genome-wide chromatin loop landscape. SATB1 does not regulate genome architecture by modulating CTCF occupancy. Rather, the topological effects imposed by SATB1 may be attributed to SATB1-dependent anchoring of CTCF to the salt extraction-resistant nuclear matrix. Together, our findings suggest that the functional interplay between nuclear matrix and CTCF plays a critical role in orchestrating 3D genome organization.
Project description:Spatial genome organization is critical for precise gene regulation during development. Special AT-rich sequence binding protein 1 (SATB1) has long been proposed to act as a global chromatin loop organizer in T cells. However, the exact functions of SATB1 in genome organization remain elusive. Here we show that the depletion of SATB1 in human and murine T cells led to transcriptional dysregulation for genes involved in T cell activation, as well as alterations of 3D genome architecture at multiple scales, including the A/B compartment, topologically associating domains (TADs), and loops. Importantly, SATB1 extensively colocalizes with CTCF throughout the genome. Depletion of SATB1 led to increased chromatin contacts among and across the SATB1/CTCF co-occupied sites, thereby affecting the transcription of critical genes involved in T cell activation. The loss of SATB1 did not affect the genome-wide occupancy of CTCF, but significantly reduced the retention of CTCF in the nuclear matrix. Collectively, our data reveal that SATB1 constrains chromatin topology surrounding CTCF-binding sites by tethering CTCF to the nuclear matrix, and suggest that the functional interplay between SATB1 and CTCF contributes to 3D genome organization.
Project description:Mechanisms of tissue-specific gene expression regulation, particularly via spatial coordination of gene promoters and their regulatory elements are poorly understood. Here we investigated the 3D genome organization of developing murine T cells. We identified a tissue-specific genome organizer SATB1 as a factor enriched at the anchors of promoter-enhancer chromatin loops. To unravel its functions in T cells, we generated Satb1fl/flCd4-Cre+ (Satb1 cKO) conditional knockout animals. Satb1 cKO animals suffer from severe autoimmunity so we sought to investigate a potential link between the autoimmunity and putatively deregulated nuclear architecture caused by SATB1 depletion. This series of Hi-C and HiChIP experiments is a part of SuperSeries including also RNA-Seq and ATAC-Seq experiments to fully understand the deregulation of Satb1 cKO thymocytes and to unravel the roles of SATB1 in T cell chromatin organization. Utilizing the HiChIP data, we compared SATB1 and CTCF-mediated chromatin loops, revealing that SATB1 builds a more refined layer of genome organization upon the CTCF scaffold. Moreover, H3K27ac HiChIP and Hi-C experiments in WT and Satb1 cKO thymocytes helped us to assess the functional impact of SATB1 and its underlying genome-wide regulome. SATB1 primarily mediates promoter-enhancer loops affecting a number of master regulator genes whose deregulation in knockout animals may comprise a cell-intrinsic mechanism of the autoimmunity. Our findings indicate a possible existence of a special class of genome organizers controlling tissue and/or time-specific transcriptional programs via spatial chromatin arrangements that are complementary to the function of conventional ubiquitously expressed genome organizers.
Project description:Mechanisms of tissue-specific gene expression regulation via 3D genome organization are poorly understood. Here we uncover the regulatory chromatin network of developing T cells and identify SATB1, a tissue-specific genome organizer, enriched at the anchors of promoter-enhancer loops. We have generated a T-cell specific Satb1 conditional knockout mouse which allows us to infer the molecular mechanisms responsible for the deregulation of its immune system. H3K27ac HiChIP and Hi-C experiments indicate that SATB1-dependent promoter-enhancer loops regulate expression of master regulator genes (such as Bcl6), the T cell receptor locus and adhesion molecule genes, collectively being critical for cell lineage specification and immune system homeostasis. SATB1-dependent regulatory chromatin loops represent a more refined layer of genome organization built upon a high-order scaffold provided by CTCF and other factors. Overall, our findings unravel the function of a tissue-specific factor that controls transcription programs, via spatial chromatin arrangements complementary to the chromatin structure imposed by ubiquitously expressed genome organizers.