1
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Breimann L, Bahry E, Zouinkhi M, Kolyvanov K, Street LA, Preibisch S, Ercan S. Analysis of developmental gene expression using smFISH and in silico staging of C. elegans embryos. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.15.594414. [PMID: 38798598 PMCID: PMC11118362 DOI: 10.1101/2024.05.15.594414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Regulation of transcription during embryogenesis is key to development and differentiation. To study transcript expression throughout Caenorhabditis elegans embryogenesis at single-molecule resolution, we developed a high-throughput single-molecule fluorescence in situ hybridization (smFISH) method that relies on computational methods to developmentally stage embryos and quantify individual mRNA molecules in single embryos. We applied our system to sdc-2, a zygotically transcribed gene essential for hermaphrodite development and dosage compensation. We found that sdc-2 is rapidly activated during early embryogenesis by increasing both the number of mRNAs produced per transcription site and the frequency of sites engaged in transcription. Knockdown of sdc-2 and dpy-27, a subunit of the dosage compensation complex (DCC), increased the number of active transcription sites for the X chromosomal gene dpy-23 but not the autosomal gene mdh-1, suggesting that the DCC reduces the frequency of dpy-23 transcription. The temporal resolution from in silico staging of embryos showed that the deletion of a single DCC recruitment element near the dpy-23 gene causes higher dpy-23 mRNA expression after the start of dosage compensation, which could not be resolved using mRNAseq from mixed-stage embryos. In summary, we have established a computational approach to quantify temporal regulation of transcription throughout C. elegans embryogenesis and demonstrated its potential to provide new insights into developmental gene regulation.
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Affiliation(s)
- Laura Breimann
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Ella Bahry
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Helmholtz Imaging, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | - Marwan Zouinkhi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Klim Kolyvanov
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Lena Annika Street
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Stephan Preibisch
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
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2
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Kim J, Wang H, Ercan S. Cohesin mediated loop extrusion from active enhancers form chromatin jets in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.18.558239. [PMID: 37786717 PMCID: PMC10541618 DOI: 10.1101/2023.09.18.558239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
In mammals, cohesin and CTCF organize the 3D genome into topologically associated domains (TADs) to regulate communication between cis-regulatory elements. However, many organisms, including S. cerevisiae , C. elegans , and A. thaliana lack CTCF. Here, we use C. elegans as a model to investigate the function of cohesin in 3D genome organization in an animal without CTCF. We use auxin-inducible degradation to acutely deplete SMC-3 or its negative regulator WAPL-1 from somatic cells. Using Hi-C data, we identify a cohesin-dependent 3D genome organization feature called chromatin jets (aka fountains). These are population average reflections of DNA loops that are ∼20-40 kb in scale and often cover a few transcribed genes. The jets emerge from NIPBL occupied segments, and the trajectory of the jets coincides with cohesin binding. Cohesin translocation from jet origins depends on a fully intact complex and is extended upon WAPL-1 depletion. Hi-C results support the idea that cohesin is preferentially loaded at NIPBL occupied sites and loop extrudes in an effectively two-sided manner. The location of putative loading sites coincide with active enhancers and the strength of chromatin jet pattern correlates with transcription. Hi-C analyses upon WAPL-1 depletion reveal unequal loop extrusion processivity on each side and stalling due to cohesin molecules colliding. Compared to mammalian systems, average processivity of C. elegans cohesin is ∼10-fold shorter and NIPBL binding does not depend on cohesin. We conclude that the processivity of cohesin scales with genome size; and regardless of CTCF presence, preferential loading of cohesin at enhancers is a conserved mechanism of genome organization that regulates the interaction of gene regulatory elements in 3D.
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3
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Yang Q, Lo TW, Brejc K, Schartner C, Ralston EJ, Lapidus DM, Meyer BJ. X-chromosome target specificity diverged between dosage compensation mechanisms of two closely related Caenorhabditis species. eLife 2023; 12:e85413. [PMID: 36951246 PMCID: PMC10076027 DOI: 10.7554/elife.85413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 03/21/2023] [Indexed: 03/24/2023] Open
Abstract
An evolutionary perspective enhances our understanding of biological mechanisms. Comparison of sex determination and X-chromosome dosage compensation mechanisms between the closely related nematode species Caenorhabditis briggsae (Cbr) and Caenorhabditis elegans (Cel) revealed that the genetic regulatory hierarchy controlling both processes is conserved, but the X-chromosome target specificity and mode of binding for the specialized condensin dosage compensation complex (DCC) controlling X expression have diverged. We identified two motifs within Cbr DCC recruitment sites that are highly enriched on X: 13 bp MEX and 30 bp MEX II. Mutating either MEX or MEX II in an endogenous recruitment site with multiple copies of one or both motifs reduced binding, but only removing all motifs eliminated binding in vivo. Hence, DCC binding to Cbr recruitment sites appears additive. In contrast, DCC binding to Cel recruitment sites is synergistic: mutating even one motif in vivo eliminated binding. Although all X-chromosome motifs share the sequence CAGGG, they have otherwise diverged so that a motif from one species cannot function in the other. Functional divergence was demonstrated in vivo and in vitro. A single nucleotide position in Cbr MEX can determine whether Cel DCC binds. This rapid divergence of DCC target specificity could have been an important factor in establishing reproductive isolation between nematode species and contrasts dramatically with the conservation of target specificity for X-chromosome dosage compensation across Drosophila species and for transcription factors controlling developmental processes such as body-plan specification from fruit flies to mice.
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Affiliation(s)
- Qiming Yang
- Howard Hughes Medical InstituteBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Te-Wen Lo
- Howard Hughes Medical InstituteBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Katjuša Brejc
- Howard Hughes Medical InstituteBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Caitlin Schartner
- Howard Hughes Medical InstituteBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Edward J Ralston
- Howard Hughes Medical InstituteBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Denise M Lapidus
- Howard Hughes Medical InstituteBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Barbara J Meyer
- Howard Hughes Medical InstituteBerkeleyUnited States
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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4
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Morao AK, Kim J, Obaji D, Sun S, Ercan S. Topoisomerases I and II facilitate condensin DC translocation to organize and repress X chromosomes in C. elegans. Mol Cell 2022; 82:4202-4217.e5. [PMID: 36302374 PMCID: PMC9837612 DOI: 10.1016/j.molcel.2022.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 05/24/2022] [Accepted: 10/03/2022] [Indexed: 11/18/2022]
Abstract
Condensins are evolutionarily conserved molecular motors that translocate along DNA and form loops. To address how DNA topology affects condensin translocation, we applied auxin-inducible degradation of topoisomerases I and II and analyzed the binding and function of an interphase condensin that mediates X chromosome dosage compensation in C. elegans. TOP-2 depletion reduced long-range spreading of condensin-DC (dosage compensation) from its recruitment sites and shortened 3D DNA contacts measured by Hi-C. TOP-1 depletion did not affect long-range spreading but resulted in condensin-DC accumulation within expressed gene bodies. Both TOP-1 and TOP-2 depletion resulted in X chromosome derepression, indicating that condensin-DC translocation at both scales is required for its function. Together, the distinct effects of TOP-1 and TOP-2 suggest two distinct modes of condensin-DC association with chromatin: long-range DNA loop extrusion that requires decatenation/unknotting of DNA and short-range translocation across genes that requires resolution of transcription-induced supercoiling.
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Affiliation(s)
- Ana Karina Morao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA.
| | - Jun Kim
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Daniel Obaji
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Siyu Sun
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA.
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5
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Combinatorial clustering of distinct DNA motifs directs synergistic binding of Caenorhabditis elegans dosage compensation complex to X chromosomes. Proc Natl Acad Sci U S A 2022; 119:e2211642119. [PMID: 36067293 PMCID: PMC9477397 DOI: 10.1073/pnas.2211642119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Diverse regulatory mechanisms balance X-chromosome gene expression between sexes in mammals, fruit flies, and nematodes (XY/XO males and XX females/hermaphrodites). We identify DNA motifs on X that recruit dosage compensation complexes (DCCs) in nematode hermaphrodites to reduce X-chromosome expression. Recruitment sites on X, but not regions on autosomes, contain diverse combinations of different motifs or multiple copies of one motif. DCC binding studies in vivo and in vitro of wild-type and mutant X-recruitment sites validate motif usage. We find that clustering of motifs in different combinations with appropriate orientation and spacing promotes synergy in DCC binding, thereby triggering DCC assembly specifically along X. We demonstrate how regulatory complexes can be recruited across an entire chromosome to control its gene expression. Organisms that count X-chromosome number to determine sex utilize dosage compensation mechanisms to balance X-gene expression between sexes. Typically, a regulatory complex is recruited to X chromosomes of one sex to modulate gene expression. A major challenge is to determine the mechanisms that target regulatory complexes specifically to X. Here, we identify critical X-sequence motifs in Caenorhabditis elegans that act synergistically in hermaphrodites to direct X-specific recruitment of the dosage compensation complex (DCC), a condensin complex. We find two DNA motifs that collaborate with a previously defined 12-bp motif called MEX (motif enriched on X) to mediate binding: MEX II, a 26-bp X-enriched motif and Motif C, a 9-bp motif that lacks X enrichment. Inserting both MEX and MEX II into a new location on X creates a DCC binding site equivalent to an endogenous recruitment site, but inserting only MEX or MEX II alone does not. Moreover, mutating MEX, MEX II, or Motif C in endogenous recruitment sites with multiple different motifs dramatically reduces DCC binding in vivo to nearly the same extent as mutating all motifs. Changing the orientation or spacing of motifs also reduces DCC binding. Hence, synergy in DCC binding via combinatorial clustering of motifs triggers DCC assembly specifically on X chromosomes. Using an in vitro DNA binding assay, we refine the features of motifs and flanking sequences that are critical for DCC binding. Our work reveals general principles by which regulatory complexes can be recruited across an entire chromosome to control its gene expression.
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6
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Ragipani B, Albritton SE, Morao AK, Mesquita D, Kramer M, Ercan S. Increased gene dosage and mRNA expression from chromosomal duplications in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2022; 12:jkac151. [PMID: 35731207 PMCID: PMC9339279 DOI: 10.1093/g3journal/jkac151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 06/09/2022] [Indexed: 11/14/2022]
Abstract
Isolation of copy number variations and chromosomal duplications at high frequency in the laboratory suggested that Caenorhabditis elegans tolerates increased gene dosage. Here, we addressed if a general dosage compensation mechanism acts at the level of mRNA expression in C. elegans. We characterized gene dosage and mRNA expression in 3 chromosomal duplications and a fosmid integration strain using DNA-seq and mRNA-seq. Our results show that on average, increased gene dosage leads to increased mRNA expression, pointing to a lack of genome-wide dosage compensation. Different genes within the same chromosomal duplication show variable levels of mRNA increase, suggesting feedback regulation of individual genes. Somatic dosage compensation and germline repression reduce the level of mRNA increase from X chromosomal duplications. Together, our results show a lack of genome-wide dosage compensation mechanism acting at the mRNA level in C. elegans and highlight the role of epigenetic and individual gene regulation contributing to the varied consequences of increased gene dosage.
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Affiliation(s)
- Bhavana Ragipani
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Sarah Elizabeth Albritton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Ana Karina Morao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Diogo Mesquita
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Maxwell Kramer
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
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7
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Meyer BJ. The X chromosome in C. elegans sex determination and dosage compensation. Curr Opin Genet Dev 2022; 74:101912. [PMID: 35490475 DOI: 10.1016/j.gde.2022.101912] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/17/2022] [Accepted: 03/24/2022] [Indexed: 11/16/2022]
Abstract
Abnormalities in chromosome dose can reduce organismal fitness and viability by disrupting the balance of gene expression. Unlike imbalances in chromosome dose that cause pathologies, differences in X-chromosome dose that determine sex are well tolerated. Dosage compensation mechanisms have evolved in diverse species to balance X-chromosome gene expression between sexes. Mechanisms underlying nematode X-chromosome counting to determine sex revealed how small quantitative differences in molecular signals are translated into dramatically different developmental fates. Mechanisms underlying X-chromosome dosage compensation revealed the interplay between chromatin modification and three-dimensional chromosome structure imposed by an X-specific condensin complex to regulate gene expression over vast chromosomal territories. In a surprising twist of evolution, this dosage-compensation condensin complex also regulates lifespan and tolerance to proteotoxic stress.
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Affiliation(s)
- Barbara J Meyer
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, 16 Barker Hall, Berkeley, CA 94720-3204, USA.
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8
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Meyer BJ. Mechanisms of sex determination and X-chromosome dosage compensation. Genetics 2022; 220:6498458. [PMID: 35100381 PMCID: PMC8825453 DOI: 10.1093/genetics/iyab197] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 10/25/2021] [Indexed: 12/03/2022] Open
Abstract
Abnormalities in chromosome number have the potential to disrupt the balance of gene expression and thereby decrease organismal fitness and viability. Such abnormalities occur in most solid tumors and also cause severe developmental defects and spontaneous abortions. In contrast to the imbalances in chromosome dose that cause pathologies, the difference in X-chromosome dose used to determine sexual fate across diverse species is well tolerated. Dosage compensation mechanisms have evolved in such species to balance X-chromosome gene expression between the sexes, allowing them to tolerate the difference in X-chromosome dose. This review analyzes the chromosome counting mechanism that tallies X-chromosome number to determine sex (XO male and XX hermaphrodite) in the nematode Caenorhabditis elegans and the associated dosage compensation mechanism that balances X-chromosome gene expression between the sexes. Dissecting the molecular mechanisms underlying X-chromosome counting has revealed how small quantitative differences in intracellular signals can be translated into dramatically different fates. Dissecting the process of X-chromosome dosage compensation has revealed the interplay between chromatin modification and chromosome structure in regulating gene expression over vast chromosomal territories.
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Affiliation(s)
- Barbara J Meyer
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720-3204, USA
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9
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Kim J, Jimenez DS, Ragipani B, Zhang B, Street LA, Kramer M, Albritton SE, Winterkorn LH, Morao AK, Ercan S. Condensin DC loads and spreads from recruitment sites to create loop-anchored TADs in C. elegans. eLife 2022; 11:68745. [PMID: 36331876 PMCID: PMC9635877 DOI: 10.7554/elife.68745] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 10/23/2022] [Indexed: 11/06/2022] Open
Abstract
Condensins are molecular motors that compact DNA via linear translocation. In Caenorhabditis elegans, the X-chromosome harbors a specialized condensin that participates in dosage compensation (DC). Condensin DC is recruited to and spreads from a small number of recruitment elements on the X-chromosome (rex) and is required for the formation of topologically associating domains (TADs). We take advantage of autosomes that are largely devoid of condensin DC and TADs to address how rex sites and condensin DC give rise to the formation of TADs. When an autosome and X-chromosome are physically fused, despite the spreading of condensin DC into the autosome, no TAD was created. Insertion of a strong rex on the X-chromosome results in the TAD boundary formation regardless of sequence orientation. When the same rex is inserted on an autosome, despite condensin DC recruitment, there was no spreading or features of a TAD. On the other hand, when a 'super rex' composed of six rex sites or three separate rex sites are inserted on an autosome, recruitment and spreading of condensin DC led to the formation of TADs. Therefore, recruitment to and spreading from rex sites are necessary and sufficient for recapitulating loop-anchored TADs observed on the X-chromosome. Together our data suggest a model in which rex sites are both loading sites and bidirectional barriers for condensin DC, a one-sided loop-extruder with movable inactive anchor.
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Affiliation(s)
- Jun Kim
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
| | - David S Jimenez
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
| | - Bhavana Ragipani
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
| | - Bo Zhang
- UCSF HSWSan FranciscoUnited States
| | - Lena A Street
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
| | - Maxwell Kramer
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
| | - Sarah E Albritton
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
| | - Lara H Winterkorn
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
| | - Ana K Morao
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
| | - Sevinc Ercan
- Department of Biology and Center for Genomics and Systems Biology, New York UniversityNew YorkUnited States
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10
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Breimann L, Morao AK, Kim J, Jimenez DS, Maryn N, Bikkasani K, Carrozza MJ, Albritton SE, Kramer M, Street LA, Cerimi K, Schumann VF, Bahry E, Preibisch S, Woehler A, Ercan S. The H4K20 demethylase DPY-21 regulates the dynamics of condensin DC binding. J Cell Sci 2021; 135:273768. [PMID: 34918745 PMCID: PMC8917352 DOI: 10.1242/jcs.258818] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 11/29/2021] [Indexed: 11/26/2022] Open
Abstract
Condensin is a multi-subunit structural maintenance of chromosomes (SMC) complex that binds to and compacts chromosomes. Here, we addressed the regulation of condensin binding dynamics using Caenorhabditis elegans condensin DC, which represses X chromosomes in hermaphrodites for dosage compensation. We established fluorescence recovery after photobleaching (FRAP) using the SMC4 homolog DPY-27 and showed that a well-characterized ATPase mutation abolishes DPY-27 binding to X chromosomes. Next, we performed FRAP in the background of several chromatin modifier mutants that cause varying degrees of X chromosome derepression. The greatest effect was in a null mutant of the H4K20me2 demethylase DPY-21, where the mobile fraction of condensin DC reduced from ∼30% to 10%. In contrast, a catalytic mutant of dpy-21 did not regulate condensin DC mobility. Hi-C sequencing data from the dpy-21 null mutant showed little change compared to wild-type data, uncoupling Hi-C-measured long-range DNA contacts from transcriptional repression of the X chromosomes. Taken together, our results indicate that DPY-21 has a non-catalytic role in regulating the dynamics of condensin DC binding, which is important for transcription repression. Summary: The histone demethylase DPY-21 has catalytic and non-catalytic roles in condensin DC-mediated X chromosome repression. The non-catalytic activity regulates dynamics of condensin DC binding to X chromosomes.
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Affiliation(s)
- Laura Breimann
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA.,Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Institute for Biology, Humboldt University of Berlin, Berlin, Germany
| | - Ana Karina Morao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Jun Kim
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - David Sebastian Jimenez
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Nina Maryn
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Krishna Bikkasani
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Michael J Carrozza
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Sarah E Albritton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Maxwell Kramer
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Lena Annika Street
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Kustrim Cerimi
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Vic-Fabienne Schumann
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ella Bahry
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Stephan Preibisch
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Andrew Woehler
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
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11
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Anderson EC, Frankino PA, Higuchi-Sanabria R, Yang Q, Bian Q, Podshivalova K, Shin A, Kenyon C, Dillin A, Meyer BJ. X Chromosome Domain Architecture Regulates Caenorhabditis elegans Lifespan but Not Dosage Compensation. Dev Cell 2019; 51:192-207.e6. [PMID: 31495695 DOI: 10.1016/j.devcel.2019.08.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 06/26/2019] [Accepted: 08/06/2019] [Indexed: 12/21/2022]
Abstract
Mechanisms establishing higher-order chromosome structures and their roles in gene regulation are elusive. We analyzed chromosome architecture during nematode X chromosome dosage compensation, which represses transcription via a dosage-compensation condensin complex (DCC) that binds hermaphrodite Xs and establishes megabase-sized topologically associating domains (TADs). We show that DCC binding at high-occupancy sites (rex sites) defines eight TAD boundaries. Single rex deletions disrupted boundaries, and single insertions created new boundaries, demonstrating that a rex site is necessary and sufficient to define DCC-dependent boundary locations. Deleting eight rex sites (8rexΔ) recapitulated TAD structure of DCC mutants, permitting analysis when chromosome-wide domain architecture was disrupted but most DCC binding remained. 8rexΔ animals exhibited no changes in X expression and lacked dosage-compensation mutant phenotypes. Hence, TAD boundaries are neither the cause nor the consequence of DCC-mediated gene repression. Abrogating TAD structure did, however, reduce thermotolerance, accelerate aging, and shorten lifespan, implicating chromosome architecture in stress responses and aging.
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Affiliation(s)
- Erika C Anderson
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Phillip A Frankino
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ryo Higuchi-Sanabria
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Qiming Yang
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Qian Bian
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | - Aram Shin
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Cynthia Kenyon
- Calico Life Sciences, South San Francisco, CA 94080, USA
| | - Andrew Dillin
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Barbara J Meyer
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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12
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Street LA, Morao AK, Winterkorn LH, Jiao CY, Albritton SE, Sadic M, Kramer M, Ercan S. Binding of an X-Specific Condensin Correlates with a Reduction in Active Histone Modifications at Gene Regulatory Elements. Genetics 2019; 212:729-742. [PMID: 31123040 PMCID: PMC6614895 DOI: 10.1534/genetics.119.302254] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 05/20/2019] [Indexed: 12/13/2022] Open
Abstract
Condensins are evolutionarily conserved protein complexes that are required for chromosome segregation during cell division and genome organization during interphase. In Caenorhabditis elegans, a specialized condensin, which forms the core of the dosage compensation complex (DCC), binds to and represses X chromosome transcription. Here, we analyzed DCC localization and the effect of DCC depletion on histone modifications, transcription factor binding, and gene expression using chromatin immunoprecipitation sequencing and mRNA sequencing. Across the X, the DCC accumulates at accessible gene regulatory sites in active chromatin and not heterochromatin. The DCC is required for reducing the levels of activating histone modifications, including H3K4me3 and H3K27ac, but not repressive modification H3K9me3. In X-to-autosome fusion chromosomes, DCC spreading into the autosomal sequences locally reduces gene expression, thus establishing a direct link between DCC binding and repression. Together, our results indicate that DCC-mediated transcription repression is associated with a reduction in the activity of X chromosomal gene regulatory elements.
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Affiliation(s)
- Lena Annika Street
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York 10003
| | - Ana Karina Morao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York 10003
| | - Lara Heermans Winterkorn
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York 10003
| | - Chen-Yu Jiao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York 10003
| | | | - Mohammed Sadic
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York 10003
| | - Maxwell Kramer
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York 10003
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York 10003
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13
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Jordan W, Rieder LE, Larschan E. Diverse Genome Topologies Characterize Dosage Compensation across Species. Trends Genet 2019; 35:308-315. [PMID: 30808531 DOI: 10.1016/j.tig.2019.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/29/2019] [Accepted: 02/01/2019] [Indexed: 01/19/2023]
Abstract
Dosage compensation is the process by which transcript levels of the X chromosome are equalized with those of autosomes. Although diverse mechanisms of dosage compensation have evolved across species, these mechanisms all involve distinguishing the X chromosome from autosomes. Because one chromosome is singled out from other chromosomes for precise regulation, dosage compensation serves as an important model for understanding how specific cis-elements are identified within the highly compacted 3D genome to co-regulate thousands of genes. Recently, multiple genomic approaches have provided key insights into the mechanisms of dosage compensation, extending what we have learned from classical genetic studies. In the future, newer genomic approaches that require little starting material show great promise to provide an understanding of the heterogeneity of dosage compensation between cells and how it functions in nonmodel organisms.
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Affiliation(s)
- William Jordan
- Department of Molecular Biology, Cellular Biology and Biochemistry, Brown University, Providence, RI, USA
| | - Leila E Rieder
- Department of Molecular Biology, Cellular Biology and Biochemistry, Brown University, Providence, RI, USA; Department of Biology, Emory University, Atlanta, GA, USA
| | - Erica Larschan
- Department of Molecular Biology, Cellular Biology and Biochemistry, Brown University, Providence, RI, USA.
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14
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Paul MR, Markowitz TE, Hochwagen A, Ercan S. Condensin Depletion Causes Genome Decompaction Without Altering the Level of Global Gene Expression in Saccharomyces cerevisiae. Genetics 2018; 210:331-344. [PMID: 29970489 PMCID: PMC6116964 DOI: 10.1534/genetics.118.301217] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 06/25/2018] [Indexed: 12/12/2022] Open
Abstract
Condensins are broadly conserved chromosome organizers that function in chromatin compaction and transcriptional regulation, but to what extent these two functions are linked has remained unclear. Here, we analyzed the effect of condensin inactivation on genome compaction and global gene expression in the yeast Saccharomyces cerevisiae by performing spike-in-controlled genome-wide chromosome conformation capture (3C-seq) and mRNA-sequencing analysis. 3C-seq analysis shows that acute condensin inactivation leads to a global decrease in close-range intrachromosomal interactions as well as more specific losses of interchromosomal tRNA gene clustering. In addition, a condensin-rich interaction domain between the ribosomal DNA and the centromere on chromosome XII is lost upon condensin inactivation. Unexpectedly, these large-scale changes in chromosome architecture are not associated with global changes in mRNA levels. Our data suggest that the global transcriptional program of proliferating S. cerevisiae is resistant to condensin inactivation and the associated profound changes in genome organization.
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Affiliation(s)
- Matthew Robert Paul
- Department of Biology, New York University, New York 10003
- Center for Genomics and Systems Biology, New York University, New York 10003
| | | | | | - Sevinç Ercan
- Department of Biology, New York University, New York 10003
- Center for Genomics and Systems Biology, New York University, New York 10003
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15
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A Simple Method for Visualization of Locus-Specific H4K20me1 Modifications in Living Caenorhabditis elegans Single Cells. G3-GENES GENOMES GENETICS 2018; 8:2249-2255. [PMID: 29724885 PMCID: PMC6027889 DOI: 10.1534/g3.118.200333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Recently, advances in next-generation sequencing technologies have enabled genome-wide analyses of epigenetic modifications; however, it remains difficult to analyze the states of histone modifications at a single-cell resolution in living multicellular organisms because of the heterogeneity within cellular populations. Here we describe a simple method to visualize histone modifications on the specific sequence of target locus at a single-cell resolution in living Caenorhabditis elegans, by combining the LacO/LacI system and a genetically-encoded H4K20me1-specific probe, “mintbody”. We demonstrate that Venus-labeled mintbody and mTurquoise2-labeled LacI can co-localize on an artificial chromosome carrying both the target locus and LacO sequences, where H4K20me1 marks the target locus. We demonstrate that our visualization method can precisely detect H4K20me1 depositions on the her-1 gene sequences on the artificial chromosome, to which the dosage compensation complex binds to regulate sex determination. The degree of H4K20me1 deposition on the her-1 sequences on the artificial chromosome correlated strongly with sex, suggesting that, using the artificial chromosome, this method can reflect context-dependent changes of H4K20me1 on endogenous genomes. Furthermore, we demonstrate live imaging of H4K20me1 depositions on the artificial chromosome. Combined with ChIP assays, this mintbody-LacO/LacI visualization method will enable analysis of developmental and context-dependent alterations of locus-specific histone modifications in specific cells and elucidation of the underlying molecular mechanisms.
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16
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Lucchesi JC. Transcriptional modulation of entire chromosomes: dosage compensation. J Genet 2018; 97:357-364. [PMID: 29932054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Dosage compensation is a regulatory system designed to equalize the transcription output of the genes of the sex chromosomes that are present in different doses in the sexes (X or Z chromosome, depending on the animal species involved). Different mechanisms of dosage compensation have evolved in different animal groups. In Drosophila males, a complex (male-specific lethal) associates with the X chromosome and enhances the activity of most X-linked genes by increasing the rate of RNAPII elongation. In Caenorhabditis, a complex (dosage compensation complex) that contains a number of proteins involved in condensing chromosomes decreases the level of transcription of both X chromosomes in the XX hermaphrodite. In mammals, dosage compensation is achieved by the inactivation, early during development, of most X-linked genes on one of the two X chromosomes in females. The mechanism involves the synthesis of an RNA (Tsix) that protects one of the two Xs from inactivation, and of another RNA (Xist) that coats the other X chromosome and recruits histone and DNA modifying enzymes. This review will focus on the current progress in understanding the dosage compensation mechanisms in the three taxa where it has been best studied at the molecular level: flies, round worms and mammals.
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Affiliation(s)
- John C Lucchesi
- Department of Biology, Emory University, Atlanta, GA 30322, USA. E-mail:
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17
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18
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Albritton SE, Ercan S. Caenorhabditis elegans Dosage Compensation: Insights into Condensin-Mediated Gene Regulation. Trends Genet 2017; 34:41-53. [PMID: 29037439 DOI: 10.1016/j.tig.2017.09.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/19/2017] [Accepted: 09/25/2017] [Indexed: 01/05/2023]
Abstract
Recent work demonstrating the role of chromosome organization in transcriptional regulation has sparked substantial interest in the molecular mechanisms that control chromosome structure. Condensin, an evolutionarily conserved multisubunit protein complex, is essential for chromosome condensation during cell division and functions in regulating gene expression during interphase. In Caenorhabditis elegans, a specialized condensin forms the core of the dosage compensation complex (DCC), which specifically binds to and represses transcription from the hermaphrodite X chromosomes. DCC serves as a clear paradigm for addressing how condensins target large chromosomal domains and how they function to regulate chromosome structure and transcription. Here, we discuss recent research on C. elegans DCC in the context of canonical condensin mechanisms as have been studied in various organisms.
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Affiliation(s)
- Sarah Elizabeth Albritton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA.
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