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Horsfield JA. Full circle: a brief history of cohesin and the regulation of gene expression. FEBS J 2023; 290:1670-1687. [PMID: 35048511 DOI: 10.1111/febs.16362] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/21/2021] [Accepted: 01/18/2022] [Indexed: 12/17/2022]
Abstract
The cohesin complex has a range of crucial functions in the cell. Cohesin is essential for mediating chromatid cohesion during mitosis, for repair of double-strand DNA breaks, and for control of gene transcription. This last function has been the subject of intense research ever since the discovery of cohesin's role in the long-range regulation of the cut gene in Drosophila. Subsequent research showed that the expression of some genes is exquisitely sensitive to cohesin depletion, while others remain relatively unperturbed. Sensitivity to cohesin depletion is also remarkably cell type- and/or condition-specific. The relatively recent discovery that cohesin is integral to forming chromatin loops via loop extrusion should explain much of cohesin's gene regulatory properties, but surprisingly, loop extrusion has failed to identify a 'one size fits all' mechanism for how cohesin controls gene expression. This review will illustrate how early examples of cohesin-dependent gene expression integrate with later work on cohesin's role in genome organization to explain mechanisms by which cohesin regulates gene expression.
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Affiliation(s)
- Julia A Horsfield
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
- Genetics Otago Research Centre, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, New Zealand
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2
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de Wit E, Nora EP. New insights into genome folding by loop extrusion from inducible degron technologies. Nat Rev Genet 2023; 24:73-85. [PMID: 36180596 DOI: 10.1038/s41576-022-00530-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2022] [Indexed: 01/24/2023]
Abstract
Chromatin folds into dynamic loops that often span hundreds of kilobases and physically wire distant loci together for gene regulation. These loops are continuously created, extended and positioned by structural maintenance of chromosomes (SMC) protein complexes, such as condensin and cohesin, and their regulators, including CTCF, in a highly dynamic process known as loop extrusion. Genetic loss of extrusion factors is lethal, complicating their study. Inducible protein degradation technologies enable the depletion of loop extrusion factors within hours, leading to the rapid reconfiguration of chromatin folding. Here, we review how these technologies have changed our understanding of genome organization, upsetting long-held beliefs on its role in transcription. Finally, we examine recent models that attempt to reconcile observations after chronic versus acute perturbations, and discuss future developments in this rapidly developing field of research.
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Affiliation(s)
- Elzo de Wit
- Division of Gene Regulation, Oncode Institute, Amsterdam, the Netherlands.
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, the Netherlands.
| | - Elphège P Nora
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA.
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
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Abstract
Mutations of the cohesin complex in human cancer were first discovered ~10 years ago. Since then, researchers worldwide have demonstrated that cohesin is among the most commonly mutated protein complexes in cancer. Inactivating mutations in genes encoding cohesin subunits are common in bladder cancers, paediatric sarcomas, leukaemias, brain tumours and other cancer types. Also in those 10 years, the prevailing view of the functions of cohesin in cell biology has undergone a revolutionary transformation. Initially, the predominant view of cohesin was as a ring that encircled and cohered replicated chromosomes until its cleavage triggered the metaphase-to-anaphase transition. As such, early studies focused on the role of tumour-derived cohesin mutations in the fidelity of chromosome segregation and aneuploidy. However, over the past 5 years the cohesin field has shifted dramatically, and research now focuses on the primary role of cohesin in generating, maintaining and regulating the intra-chromosomal DNA looping events that modulate 3D genome organization and gene expression. This Review focuses on recent discoveries in the cohesin field that provide insight into the role of cohesin inactivation in cancer pathogenesis, and opportunities for exploiting these findings for the clinical benefit of patients with cohesin-mutant cancers.
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Affiliation(s)
- Todd Waldman
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University School of Medicine, Washington, DC, USA.
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4
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Martins NMC, Cisneros-Soberanis F, Pesenti E, Kochanova NY, Shang WH, Hori T, Nagase T, Kimura H, Larionov V, Masumoto H, Fukagawa T, Earnshaw WC. H3K9me3 maintenance on a human artificial chromosome is required for segregation but not centromere epigenetic memory. J Cell Sci 2020; 133:jcs242610. [PMID: 32576667 PMCID: PMC7390644 DOI: 10.1242/jcs.242610] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 06/11/2020] [Indexed: 12/24/2022] Open
Abstract
Most eukaryotic centromeres are located within heterochromatic regions. Paradoxically, heterochromatin can also antagonize de novo centromere formation, and some centromeres lack it altogether. In order to investigate the importance of heterochromatin at centromeres, we used epigenetic engineering of a synthetic alphoidtetO human artificial chromosome (HAC), to which chimeric proteins can be targeted. By tethering the JMJD2D demethylase (also known as KDM4D), we removed heterochromatin mark H3K9me3 (histone 3 lysine 9 trimethylation) specifically from the HAC centromere. This caused no short-term defects, but long-term tethering reduced HAC centromere protein levels and triggered HAC mis-segregation. However, centromeric CENP-A was maintained at a reduced level. Furthermore, HAC centromere function was compatible with an alternative low-H3K9me3, high-H3K27me3 chromatin signature, as long as residual levels of H3K9me3 remained. When JMJD2D was released from the HAC, H3K9me3 levels recovered over several days back to initial levels along with CENP-A and CENP-C centromere levels, and mitotic segregation fidelity. Our results suggest that a minimal level of heterochromatin is required to stabilize mitotic centromere function but not for maintaining centromere epigenetic memory, and that a homeostatic pathway maintains heterochromatin at centromeres.This article has an associated First Person interview with the first authors of the paper.
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Affiliation(s)
| | | | - Elisa Pesenti
- Wellcome Trust Centre for Cell Biology, Edinburgh, UK
| | | | - Wei-Hao Shang
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Tetsuya Hori
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | | | - Hiroshi Kimura
- Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Vladimir Larionov
- National Cancer Institute, National Institutes of Health, Bethesda, USA
| | | | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
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Pertesi M, Ekdahl L, Palm A, Johnsson E, Järvstråt L, Wihlborg AK, Nilsson B. Essential genes shape cancer genomes through linear limitation of homozygous deletions. Commun Biol 2019; 2:262. [PMID: 31341961 PMCID: PMC6642121 DOI: 10.1038/s42003-019-0517-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 06/26/2019] [Indexed: 12/26/2022] Open
Abstract
The landscape of somatic acquired deletions in cancer cells is shaped by positive and negative selection. Recurrent deletions typically target tumor suppressor, leading to positive selection. Simultaneously, loss of a nearby essential gene can lead to negative selection, and introduce latent vulnerabilities specific to cancer cells. Here we show that, under basic assumptions on positive and negative selection, deletion limitation gives rise to a statistical pattern where the frequency of homozygous deletions decreases approximately linearly between the deletion target gene and the nearest essential genes. Using DNA copy number data from 9,744 human cancer specimens, we demonstrate that linear deletion limitation exists and exposes deletion-limiting genes for seven known deletion targets (CDKN2A, RB1, PTEN, MAP2K4, NF1, SMAD4, and LINC00290). Downstream analysis of pooled CRISPR/Cas9 data provide further evidence of essentiality. Our results provide further insight into how the deletion landscape is shaped and identify potentially targetable vulnerabilities.
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Affiliation(s)
- Maroulio Pertesi
- Hematology and Transfusion Medicine Department of Laboratory Medicine, BMC, SE-221 84 Lund, Sweden
| | - Ludvig Ekdahl
- Hematology and Transfusion Medicine Department of Laboratory Medicine, BMC, SE-221 84 Lund, Sweden
| | - Angelica Palm
- Hematology and Transfusion Medicine Department of Laboratory Medicine, BMC, SE-221 84 Lund, Sweden
| | - Ellinor Johnsson
- Hematology and Transfusion Medicine Department of Laboratory Medicine, BMC, SE-221 84 Lund, Sweden
| | - Linnea Järvstråt
- Hematology and Transfusion Medicine Department of Laboratory Medicine, BMC, SE-221 84 Lund, Sweden
| | - Anna-Karin Wihlborg
- Hematology and Transfusion Medicine Department of Laboratory Medicine, BMC, SE-221 84 Lund, Sweden
| | - Björn Nilsson
- Hematology and Transfusion Medicine Department of Laboratory Medicine, BMC, SE-221 84 Lund, Sweden
- Broad Institute, 415 Main Street, Cambridge, MA 02142 USA
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Reimer M, Pulakanti K, Shi L, Abel A, Liang M, Malarkannan S, Rao S. Deletion of Tet proteins results in quantitative disparities during ESC differentiation partially attributable to alterations in gene expression. BMC DEVELOPMENTAL BIOLOGY 2019; 19:16. [PMID: 31286885 PMCID: PMC6615237 DOI: 10.1186/s12861-019-0196-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/30/2019] [Indexed: 12/12/2022]
Abstract
Background The Tet protein family (Tet1, Tet2, and Tet3) regulate DNA methylation through conversion of 5-methylcytosine to 5-hydroxymethylcytosine which can ultimately result in DNA demethylation and play a critical role during early mammalian development and pluripotency. While multiple groups have generated knockouts combining loss of different Tet proteins in murine embryonic stem cells (ESCs), differences in genetic background and approaches has made it difficult to directly compare results and discern the direct mechanism by which Tet proteins regulate the transcriptome. To address this concern, we utilized genomic editing in an isogenic pluripotent background which permitted a quantitative, flow-cytometry based measurement of pluripotency in combination with genome-wide assessment of gene expression and DNA methylation changes. Our ultimate goal was to generate a resource of large-scale datasets to permit hypothesis-generating experiments. Results We demonstrate a quantitative disparity in the differentiation ability among Tet protein deletions, with Tet2 single knockout exhibiting the most severe defect, while loss of Tet1 alone or combinations of Tet genes showed a quantitatively intermediate phenotype. Using a combination of transcriptomic and epigenomic approaches we demonstrate an increase in DNA hypermethylation and a divergence of transcriptional profiles in pluripotency among Tet deletions, with loss of Tet2 having the most profound effect in undifferentiated ESCs. Conclusions We conclude that loss of Tet2 has the most dramatic effect both on the phenotype of ESCs and the transcriptome compared to other genotypes. While loss of Tet proteins increased DNA hypermethylation, especially in gene promoters, these changes in DNA methylation did not correlate with gene expression changes. Thus, while loss of different Tet proteins alters DNA methylation, this change does not appear to be directly responsible for transcriptome changes. Thus, loss of Tet proteins likely regulates the transcriptome epigenetically both through altering 5mC but also through additional mechanisms. Nonetheless, the transcriptome changes in pluripotent Tet2−/− ESCs compared to wild-type implies that the disparities in differentiation can be partially attributed to baseline alterations in gene expression. Electronic supplementary material The online version of this article (10.1186/s12861-019-0196-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michael Reimer
- Blood Research Institute, Versiti, 8733 West Watertown Plank Road, Milwaukee, WI, 53226, USA
| | - Kirthi Pulakanti
- Blood Research Institute, Versiti, 8733 West Watertown Plank Road, Milwaukee, WI, 53226, USA
| | - Linzheng Shi
- Blood Research Institute, Versiti, 8733 West Watertown Plank Road, Milwaukee, WI, 53226, USA.,Vanderbilt University, Nashville, TN, 37240, USA
| | - Alex Abel
- Blood Research Institute, Versiti, 8733 West Watertown Plank Road, Milwaukee, WI, 53226, USA.,Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Mingyu Liang
- Department of Physiology, Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Subramaniam Malarkannan
- Blood Research Institute, Versiti, 8733 West Watertown Plank Road, Milwaukee, WI, 53226, USA.,Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.,Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.,Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Sridhar Rao
- Blood Research Institute, Versiti, 8733 West Watertown Plank Road, Milwaukee, WI, 53226, USA. .,Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, 53226, USA. .,Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
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Toth Z, Smindak RJ, Papp B. Inhibition of the lytic cycle of Kaposi's sarcoma-associated herpesvirus by cohesin factors following de novo infection. Virology 2017; 512:25-33. [PMID: 28898712 PMCID: PMC5653454 DOI: 10.1016/j.virol.2017.09.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/25/2017] [Accepted: 09/01/2017] [Indexed: 01/03/2023]
Abstract
Establishment of Kaposi's sarcoma-associated herpesvirus (KSHV) latency following infection is a multistep process, during which polycomb proteins are recruited onto the KSHV genome, which is crucial for the genome-wide repression of lytic genes during latency. Strikingly, only a subset of lytic genes are expressed transiently in the early phase of infection prior to the binding of polycomb proteins onto the KSHV genome, which raises the question what restricts lytic gene expression in the first hours of infection. Here, we demonstrate that both CTCF and cohesin chromatin organizing factors are rapidly recruited to the viral genome prior to the binding of polycombs during de novo infection, but only cohesin is required for the genome-wide inhibition of lytic genes. We propose that cohesin is required for the establishment of KSHV latency by initiating the repression of lytic genes following infection, which is an essential step in persistent infection of humans.
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Affiliation(s)
- Zsolt Toth
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL 32610, USA; UF Genetics Institute, USA; UF Health Cancer Center, USA.
| | - Richard J Smindak
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL 32610, USA
| | - Bernadett Papp
- Department of Oral Biology, University of Florida College of Dentistry, 1395 Center Drive, Gainesville, FL 32610, USA; UF Genetics Institute, USA; UF Health Cancer Center, USA
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Blinka S, Rao S. Nanog Expression in Embryonic Stem Cells - An Ideal Model System to Dissect Enhancer Function. Bioessays 2017; 39:10.1002/bies.201700086. [PMID: 28977693 PMCID: PMC5878941 DOI: 10.1002/bies.201700086] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 08/31/2017] [Indexed: 01/17/2023]
Abstract
Embryonic stem cells (ESCs) are derived from the preimplantation embryo and can differentiate into virtually any other cell type (termed pluripotency), which is governed by lineage specific transcriptions factors (TFs) binding to cis regulatory elements (CREs) to mediate changes in gene expression. The reliance on transcriptional regulation to maintain pluripotency makes ESCs a valuable model to study the role of distal CREs such as enhancers in modulating gene expression to affect cell fate decisions. This review will highlight recent advance on transcriptional enhancers, focusing on studies performed in ESCs. In addition, we argue that the Nanog locus, which encodes for an ESC-critical TF, is particularly informative because it contains multiple co-regulated genes and enhancers in close proximity to one another. The unique landscape at Nanog permits the study of ongoing questions including whether multiple enhancers function additively versus synergistically, determinants of gene specificity, and cell-to-cell variability in gene expression.
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Affiliation(s)
- Steven Blinka
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Blood Research Institute, Blood Center of Wisconsin, 8733 West Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Sridhar Rao
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Blood Research Institute, Blood Center of Wisconsin, 8733 West Watertown Plank Road, Milwaukee, WI 53226, USA
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Blinka S, Reimer MH, Pulakanti K, Rao S. Super-Enhancers at the Nanog Locus Differentially Regulate Neighboring Pluripotency-Associated Genes. Cell Rep 2017; 17:19-28. [PMID: 27681417 DOI: 10.1016/j.celrep.2016.09.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 06/13/2016] [Accepted: 08/30/2016] [Indexed: 12/20/2022] Open
Abstract
Super-enhancers are tissue-specific cis-regulatory elements that drive expression of genes associated with cell identity and malignancy. A cardinal feature of super-enhancers is that they are transcribed to produce enhancer-derived RNAs (eRNAs). It remains unclear whether super-enhancers robustly activate genes in situ and whether their functions are attributable to eRNAs or the DNA element. CRISPR/Cas9 was used to systematically delete three discrete super-enhancers at the Nanog locus in embryonic stem cells, revealing functional differences in Nanog transcriptional regulation. One distal super-enhancer 45 kb upstream of Nanog (-45 enhancer) regulates both nearest neighbor genes, Nanog and Dppa3. Interestingly, eRNAs produced at the -45 enhancer specifically regulate Dppa3 expression by stabilizing looping of the -45 enhancer and Dppa3. Our work illustrates that genomic editing is required to determine enhancer function and points to a method to selectively target a subset of super-enhancer-regulated genes by depleting eRNAs.
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Affiliation(s)
- Steven Blinka
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226, USA
| | - Michael H Reimer
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226, USA
| | - Kirthi Pulakanti
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226, USA
| | - Sridhar Rao
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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