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Megee PC, Uhley V, Grogan J, Silverman A. Foundational and Clinical Science Integration in a Team-Based Learning Module Modeling Care of a Patient With Dyslipidemia. MedEdPORTAL 2024; 20:11397. [PMID: 38595707 PMCID: PMC11001791 DOI: 10.15766/mep_2374-8265.11397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 01/14/2024] [Indexed: 04/11/2024]
Abstract
Introduction Foundational and clinical science integration, a long-standing goal of undergraduate medical education, benefits learners by promoting retention of critical knowledge and skills as well as their transfer to the clinical setting. We implemented a team-based learning (TBL) module in which foundational knowledge and skills from the disciplines of biochemistry, nutrition, and genetics were leveraged in a simulated patient encounter for diagnosis and management of a patient with dyslipidemia. Methods The TBL was deployed in a first-year medical student cardiovascular system course with 125 students over three academic years. Following individual and team readiness assurance tests (iRAT and tRAT, respectively), teams participated in an initial application exercise requiring consideration of clinical and laboratory data and other risk factors to engage the patient in a shared decision-making process. Using dietary and family history narratives in subsequent application exercises, teams completed recommendations for an individualized diet plan and an assessment of potential disease inheritance patterns to formulate appropriate patient care management strategies. Results Student engagement with prelearning materials and session team activities was high as judged by RAT performance and application exercise outcomes: iRAT question performance ranged from 89% to 99% for individual items, and tRAT performance was routinely 100%. Learners reported that the exercises were impactful and believed the learned foundational knowledge and skills were transferable to future patient care. Discussion The dyslipidemia TBL module provides an illustration for early clinical learners of how foundational knowledge and skills can be operationalized and transferred for optimal patient care.
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Affiliation(s)
- Paul C. Megee
- Associate Professor, Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine
| | - Virginia Uhley
- Associate Professor, Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine
| | - James Grogan
- Professor, Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine
| | - Alan Silverman
- Assistant Professor, Department of Internal Medicine, Oakland University William Beaumont School of Medicine; Clinical Assistant Professor, Department of Internal Medicine, Wayne State University School of Medicine
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Woodman J, Hoffman M, Dzieciatkowska M, Hansen KC, Megee PC. Phosphorylation of the Scc2 cohesin deposition complex subunit regulates chromosome condensation through cohesin integrity. Mol Biol Cell 2015; 26:3754-67. [PMID: 26354421 PMCID: PMC4626061 DOI: 10.1091/mbc.e15-03-0165] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 08/27/2015] [Accepted: 09/04/2015] [Indexed: 01/19/2023] Open
Abstract
The cohesion of replicated sister chromatids promotes chromosome biorientation, gene regulation, DNA repair, and chromosome condensation. Cohesion is mediated by cohesin, which is deposited on chromosomes by a separate conserved loading complex composed of Scc2 and Scc4 in Saccharomyces cerevisiae. Although it is known to be required, the role of Scc2/Scc4 in cohesin deposition remains enigmatic. Scc2 is a phosphoprotein, although the functions of phosphorylation in deposition are unknown. We identified 11 phosphorylated residues in Scc2 by mass spectrometry. Mutants of SCC2 with substitutions that mimic constitutive phosphorylation retain normal Scc2-Scc4 interactions and chromatin association but exhibit decreased viability, sensitivity to genotoxic agents, and decreased stability of the Mcd1 cohesin subunit in mitotic cells. Cohesin association on chromosome arms, but not pericentromeric regions, is reduced in the phosphomimetic mutants but remains above a key threshold, as cohesion is only modestly perturbed. However, these scc2 phosphomimetic mutants exhibit dramatic chromosome condensation defects that are likely responsible for their high inviability. From these data, we conclude that normal Scc2 function requires modulation of its phosphorylation state and suggest that scc2 phosphomimetic mutants cause an increased incidence of abortive cohesin deposition events that result in compromised cohesin complex integrity and Mcd1 turnover.
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Affiliation(s)
- Julie Woodman
- Molecular Biology Program, University of Colorado School of Medicine, Aurora, CO 80045 Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Matthew Hoffman
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Monika Dzieciatkowska
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Paul C Megee
- Molecular Biology Program, University of Colorado School of Medicine, Aurora, CO 80045 Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
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Kline AD, Calof AL, Lander AD, Gerton JL, Krantz ID, Dorsett D, Deardorff MA, Blagowidow N, Yokomori K, Shirahige K, Santos R, Woodman J, Megee PC, O'Connor JT, Egense A, Noon S, Belote M, Goodban MT, Hansen BD, Timmons JG, Musio A, Ishman SL, Bryan Y, Wu Y, Bettini LR, Mehta D, Zakari M, Mills JA, Srivastava S, Haaland RE. Clinical, developmental and molecular update on Cornelia de Lange syndrome and the cohesin complex: abstracts from the 2014 Scientific and Educational Symposium. Am J Med Genet A 2015; 167:1179-92. [PMID: 25899772 DOI: 10.1002/ajmg.a.37056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 02/23/2015] [Indexed: 11/08/2022]
Abstract
Cornelia de Lange Syndrome (CdLS) is the most common example of disorders of the cohesin complex, or cohesinopathies. There are a myriad of clinical issues facing individuals with CdLS, particularly in the neurodevelopmental system, which also have implications for the parents and caretakers, involved professionals, therapists, and schools. Basic research in developmental and cell biology on cohesin is showing significant progress, with improved understanding of the mechanisms and the possibility of potential therapeutics. The following abstracts are presentations from the 6th Cornelia de Lange Syndrome Scientific and Educational Symposium, which took place on June 25-26, 2014, in conjunction with the Cornelia de Lange Syndrome Foundation National Meeting in Costa Mesa, CA. The Research Committee of the CdLS Foundation organizes the meeting, reviews and accepts abstracts, and subsequently disseminates the information to the families through members of the Clinical Advisory Board. In addition to the scientific and clinical discussions, there were educationally focused talks related to practical aspects of behavior and development. AMA CME credits were provided by Greater Baltimore Medical Center, Baltimore, MD.
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Affiliation(s)
- Antonie D Kline
- Harvey Institute for Human Genetics, Greater Baltimore Medical Center, Baltimore, Maryland
| | - Anne L Calof
- Department of Anatomy & Neurobiology, and the Center for Complex Biological Systems, University of California, Irvine, California
- Department of Developmental & Cell Biology, and the Center for Complex Biological Systems, University of California, Irvine, California
| | - Arthur D Lander
- Department of Developmental & Cell Biology, and the Center for Complex Biological Systems, University of California, Irvine, California
| | - Jennifer L Gerton
- Stowers Institute for Medical Research, University of Kansas School of Medicine, Kansas City, Missouri
- Department of Biochemistry and Molecular Biology, University of Kansas School of Medicine, Kansas City, Missouri
| | - Ian D Krantz
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Pediatrics, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Dale Dorsett
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri
| | - Matthew A Deardorff
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Pediatrics, The University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Natalie Blagowidow
- Harvey Institute for Human Genetics, Greater Baltimore Medical Center, Baltimore, Maryland
| | - Kyoko Yokomori
- Department of Biologic Chemistry, University of California, Irvine, California
| | - Katsuhiko Shirahige
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, and CREST, Japanese Science and Technology Agency, Tokyo, Japan
| | - Rosaysela Santos
- Department of Developmental & Cell Biology, and the Center for Complex Biological Systems, University of California, Irvine, California
| | - Julie Woodman
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Denver, Colorado
| | - Paul C Megee
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Denver, Colorado
| | - Julia T O'Connor
- Department of Psychiatry and Behavioral Sciences, Kennedy Krieger Institute, Baltimore, Maryland
- Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Alena Egense
- Division of Human Genetics, Department of Pediatrics, University of Maryland Medical Center, Baltimore, Maryland
| | - Sarah Noon
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Maurice Belote
- California Deaf-Blind Services, San Francisco State University, San Francisco, California
| | | | - Blake D Hansen
- Department of Counseling Psychology and Special Education, Brigham Young University, Provo, Utah
| | - Jenni Glad Timmons
- University of Minnesota Doctor of Nursing Practice-Health Innovation and Leadership, Minneapolis, Minnesota
| | - Antonio Musio
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Pisa, Italy
| | - Stacey L Ishman
- Departments of Otolaryngology and Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio
| | - Yvon Bryan
- Department of Anesthesiology, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina
| | - Yaning Wu
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Laura R Bettini
- Department of Pediatrics, Fondazione MBBM, San Gerardo Hospital, Monza, Italy
| | - Devanshi Mehta
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Musinu Zakari
- Stowers Institute for Medical Research, University of Kansas School of Medicine, Kansas City, Missouri
| | - Jason A Mills
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
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Woodman J, Fara T, Dzieciatkowska M, Trejo M, Luong N, Hansen KC, Megee PC. Cell cycle-specific cleavage of Scc2 regulates its cohesin deposition activity. Proc Natl Acad Sci U S A 2014; 111:7060-5. [PMID: 24778232 PMCID: PMC4024903 DOI: 10.1073/pnas.1321722111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sister chromatid cohesion (SCC), efficient DNA repair, and the regulation of some metazoan genes require the association of cohesins with chromosomes. Cohesins are deposited by a conserved heterodimeric loading complex composed of the Scc2 and Scc4 proteins in Saccharomyces cerevisiae, but how the Scc2/Scc4 deposition complex regulates the spatiotemporal association of cohesin with chromosomes is not understood. We examined Scc2 chromatin association during the cell division cycle and found that the affinity of Scc2 for chromatin increases biphasically during the cell cycle, increasing first transiently in late G1 phase and then again later in G2/M. Inactivation of Scc2 following DNA replication reduces cellular viability, suggesting that this post S-phase increase in Scc2 chromatin binding affinity is biologically relevant. Interestingly, high and low Scc2 chromatin binding levels correlate strongly with the presence of full-length or amino-terminally cleaved forms of Scc2, respectively, and the appearance of the cleaved Scc2 species is promoted in vitro either by treatment with specific cell cycle-staged cellular extracts or by dephosphorylation. Importantly, Scc2 cleavage eliminates Scc2-Scc4 physical interactions, and an scc2 truncation mutant that mimics in vivo Scc2 cleavage is defective for cohesin deposition. These observations suggest a previously unidentified mechanism for the spatiotemporal regulation of cohesin association with chromosomes through cell cycle regulation of Scc2 cohesin deposition activity by Scc2 dephosphorylation and cleavage.
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Affiliation(s)
- Julie Woodman
- Molecular Biology Program, andDepartment of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Tyler Fara
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Monika Dzieciatkowska
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Michael Trejo
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Nancy Luong
- Molecular Biology Program, andDepartment of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Paul C Megee
- Molecular Biology Program, andDepartment of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
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Kogut I, Wang J, Guacci V, Mistry RK, Megee PC. The Scc2/Scc4 cohesin loader determines the distribution of cohesin on budding yeast chromosomes. Genes Dev 2009; 23:2345-57. [PMID: 19797771 PMCID: PMC2758738 DOI: 10.1101/gad.1819409] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2009] [Accepted: 08/14/2009] [Indexed: 01/05/2023]
Abstract
Cohesins mediate sister chromatid cohesion and DNA repair and also function in gene regulation. Chromosomal cohesins are distributed nonrandomly, and their deposition requires the heterodimeric Scc2/Scc4 loader. Whether Scc2/Scc4 establishes nonrandom cohesin distributions on chromosomes is poorly characterized, however. To better understand the spatial regulation of cohesin association, we mapped budding yeast Scc2 and Scc4 chromosomal distributions. We find that Scc2/Scc4 resides at previously mapped cohesin-associated regions (CARs) in pericentromeric and arm regions, and that Scc2/Scc4-cohesin colocalization persists after the initial deposition of cohesins in G1/S phase. Pericentromeric Scc2/Scc4 enrichment is kinetochore-dependent, and both Scc2/Scc4 and cohesin associations are coordinately reduced in these regions following chromosome biorientation. Thus, these characteristics of Scc2/Scc4 binding closely recapitulate those of cohesin. Although present in G1, Scc2/Scc4 initially has a poor affinity for CARs, but its affinity increases as cells traverse the cell cycle. Scc2/Scc4 association with CARs is independent of cohesin, however. Taken together, these observations are inconsistent with a previous suggestion that cohesins are relocated by translocating RNA polymerases from separate loading sites to intergenic regions between convergently transcribed genes. Rather, our findings suggest that budding yeast cohesins are targeted to CARs largely by Scc2/Scc4 loader association at these locations.
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Affiliation(s)
- Igor Kogut
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Jianbin Wang
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Vincent Guacci
- Carnegie Institution of Washington, Baltimore, Maryland 21218, USA
| | - Rohinton K. Mistry
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
| | - Paul C. Megee
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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Eckert CA, Gravdahl DJ, Megee PC. The enhancement of pericentromeric cohesin association by conserved kinetochore components promotes high-fidelity chromosome segregation and is sensitive to microtubule-based tension. Genes Dev 2007; 21:278-91. [PMID: 17242156 PMCID: PMC1785119 DOI: 10.1101/gad.1498707] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Accepted: 12/05/2006] [Indexed: 02/02/2023]
Abstract
Sister chromatid cohesion, conferred by the evolutionarily conserved cohesin complex, is essential for proper chromosome segregation. Cohesin binds to discrete sites along chromosome arms, and is especially enriched surrounding centromeres, but past studies have not clearly defined the roles of arm and pericentromeric cohesion in chromosome segregation. To address this issue, we developed a technique that specifically reduced pericentromeric cohesin association on a single chromosome without affecting arm cohesin binding. Under these conditions, we observed more extensive stretching of centromeric chromatin and elevated frequencies of chromosome loss, suggesting that pericentromeric cohesin enrichment is essential for high-fidelity chromosome transmission. The magnitude of pericentromeric cohesin association was negatively correlated with tension between sister kinetochores, with the highest levels of association in cells lacking kinetochore-microtubule attachments. Pericentromeric cohesin recruitment required evolutionarily conserved components of the inner and central kinetochore. Together, these observations suggest that pericentromeric cohesin levels reflect the balance of opposing forces: the kinetochore-mediated enhancement of cohesin binding and the disruption of binding by mechanical tension at kinetochores. The involvement of conserved kinetochore components suggests that this pathway for pericentromeric cohesin enrichment may have been retained in higher eukaryotes to promote chromosome biorientation and accurate sister chromatid segregation.
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Affiliation(s)
- Carrie A. Eckert
- Program in Molecular Biology, University of Colorado Health Sciences Center, Aurora, Colorado 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Aurora, Colorado 80045, USA
| | - Daniel J. Gravdahl
- Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Aurora, Colorado 80045, USA
| | - Paul C. Megee
- Program in Molecular Biology, University of Colorado Health Sciences Center, Aurora, Colorado 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Aurora, Colorado 80045, USA
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Kiburz BM, Reynolds DB, Megee PC, Marston AL, Lee BH, Lee TI, Levine SS, Young RA, Amon A. The core centromere and Sgo1 establish a 50-kb cohesin-protected domain around centromeres during meiosis I. Genes Dev 2005; 19:3017-30. [PMID: 16357219 PMCID: PMC1315405 DOI: 10.1101/gad.1373005] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Accepted: 11/07/2005] [Indexed: 11/25/2022]
Abstract
The stepwise loss of cohesins, the complexes that hold sister chromatids together, is required for faithful meiotic chromosome segregation. Cohesins are removed from chromosome arms during meiosis I but are maintained around centromeres until meiosis II. Here we show that Sgo1, a protein required for protecting centromeric cohesins from removal during meiosis I, localizes to cohesin-associated regions (CARs) at the centromere and the 50-kb region surrounding it. Establishment of this Sgo1-binding domain requires the 120-base-pair (bp) core centromere, the kinetochore component Bub1, and the meiosis-specific factor Spo13. Interestingly, cohesins and the kinetochore proteins Iml3 and Chl4 are necessary for Sgo1 to associate with pericentric regions but less so for Sgo1 to associate with the core centromeric regions. Finally, we show that the 50-kb Sgo1-binding domain is the chromosomal region where cohesins are protected from removal during meiosis I. Our results identify the portions of chromosomes where cohesins are protected from removal during meiosis I and show that kinetochore components and cohesins themselves are required to establish this cohesin protective domain.
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Affiliation(s)
- Brendan M Kiburz
- Center for Cancer Research, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, 02139, USA
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Glynn EF, Megee PC, Yu HG, Mistrot C, Unal E, Koshland DE, DeRisi JL, Gerton JL. Genome-wide mapping of the cohesin complex in the yeast Saccharomyces cerevisiae. PLoS Biol 2004; 2:E259. [PMID: 15309048 PMCID: PMC490026 DOI: 10.1371/journal.pbio.0020259] [Citation(s) in RCA: 334] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Accepted: 05/14/2004] [Indexed: 11/19/2022] Open
Abstract
In eukaryotic cells, cohesin holds sister chromatids together until they separate into daughter cells during mitosis. We have used chromatin immunoprecipitation coupled with microarray analysis (ChIP chip) to produce a genome-wide description of cohesin binding to meiotic and mitotic chromosomes of Saccharomyces cerevisiae. A computer program, PeakFinder, enables flexible, automated identification and annotation of cohesin binding peaks in ChIP chip data. Cohesin sites are highly conserved in meiosis and mitosis, suggesting that chromosomes share a common underlying structure during different developmental programs. These sites occur with a semiperiodic spacing of 11 kb that correlates with AT content. The number of sites correlates with chromosome size; however, binding to neighboring sites does not appear to be cooperative. We observed a very strong correlation between cohesin sites and regions between convergent transcription units. The apparent incompatibility between transcription and cohesin binding exists in both meiosis and mitosis. Further experiments reveal that transcript elongation into a cohesin-binding site removes cohesin. A negative correlation between cohesin sites and meiotic recombination sites suggests meiotic exchange is sensitive to the chromosome structure provided by cohesin. The genome-wide view of mitotic and meiotic cohesin binding provides an important framework for the exploration of cohesins and cohesion in other genomes.
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Affiliation(s)
- Earl F Glynn
- 1Stowers Institute for Medical Research, Kansas CityMissouri, United States of America
| | - Paul C Megee
- 2Department of Biochemistry and Molecular Genetics, University of ColoradoDenver, Colorado, United States of America
| | - Hong-Guo Yu
- 3Howard Hughes Medical Institute, Department of EmbryologyCarnegie Institution of Washington, Baltimore, Maryland, United States of America
| | - Cathy Mistrot
- 3Howard Hughes Medical Institute, Department of EmbryologyCarnegie Institution of Washington, Baltimore, Maryland, United States of America
| | - Elcin Unal
- 3Howard Hughes Medical Institute, Department of EmbryologyCarnegie Institution of Washington, Baltimore, Maryland, United States of America
| | - Douglas E Koshland
- 3Howard Hughes Medical Institute, Department of EmbryologyCarnegie Institution of Washington, Baltimore, Maryland, United States of America
| | - Joseph L DeRisi
- 4Department of Biochemistry and Biophysics, University of CaliforniaSan Francisco, CaliforniaUnited States of America
| | - Jennifer L Gerton
- 1Stowers Institute for Medical Research, Kansas CityMissouri, United States of America
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Weber SA, Gerton JL, Polancic JE, DeRisi JL, Koshland D, Megee PC. The kinetochore is an enhancer of pericentric cohesin binding. PLoS Biol 2004; 2:E260. [PMID: 15309047 PMCID: PMC490027 DOI: 10.1371/journal.pbio.0020260] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Accepted: 05/14/2004] [Indexed: 11/18/2022] Open
Abstract
The recruitment of cohesins to pericentric chromatin in some organisms appears to require heterochromatin associated with repetitive DNA. However, neocentromeres and budding yeast centromeres lack flanking repetitive DNA, indicating that cohesin recruitment occurs through an alternative pathway. Here, we demonstrate that all budding yeast chromosomes assemble cohesin domains that extend over 20-50 kb of unique pericentric sequences flanking the conserved 120-bp centromeric DNA. The assembly of these cohesin domains requires the presence of a functional kinetochore in every cell cycle. A similar enhancement of cohesin binding was also observed in regions flanking an ectopic centromere. At both endogenous and ectopic locations, the centromeric enhancer amplified the inherent levels of cohesin binding that are unique to each region. Thus, kinetochores are enhancers of cohesin association that act over tens of kilobases to assemble pericentric cohesin domains. These domains are larger than the pericentric regions stretched by microtubule attachments, and thus are likely to counter microtubule-dependent forces. Kinetochores mediate two essential segregation functions: chromosome movement through microtubule attachment and biorientation of sister chromatids through the recruitment of high levels of cohesin to pericentric regions. We suggest that the coordination of chromosome movement and biorientation makes the kinetochore an autonomous segregation unit.
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Affiliation(s)
- Stewart A Weber
- 1Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center at FitzsimonsAurora, Colorado, United States of America
| | | | - Joan E Polancic
- 1Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center at FitzsimonsAurora, Colorado, United States of America
| | - Joseph L DeRisi
- 3Department of Biochemistry and Biophysics, University of CaliforniaSan Francisco, California, United States of America
| | - Douglas Koshland
- 4Howard Hughes Medical Institute, Department of EmbryologyCarnegie Institution of Washington, Baltimore, MarylandUnited States of America
| | - Paul C Megee
- 1Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center at FitzsimonsAurora, Colorado, United States of America
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Bird AW, Yu DY, Pray-Grant MG, Qiu Q, Harmon KE, Megee PC, Grant PA, Smith MM, Christman MF. Acetylation of histone H4 by Esa1 is required for DNA double-strand break repair. Nature 2002; 419:411-5. [PMID: 12353039 DOI: 10.1038/nature01035] [Citation(s) in RCA: 414] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2002] [Accepted: 07/02/2002] [Indexed: 11/09/2022]
Abstract
Although the acetylation of histones has a well-documented regulatory role in transcription, its role in other chromosomal functions remains largely unexplored. Here we show that distinct patterns of histone H4 acetylation are essential in two separate pathways of double-strand break repair. A budding yeast strain with mutations in wild-type H4 acetylation sites shows defects in nonhomologous end joining repair and in a newly described pathway of replication-coupled repair. Both pathways require the ESA1 histone acetyl transferase (HAT), which is responsible for acetylating all H4 tail lysines, including ectopic lysines that restore repair capacity to a mutant H4 tail. Arp4, a protein that binds histone H4 tails and is part of the Esa1-containing NuA4 HAT complex, is recruited specifically to DNA double-strand breaks that are generated in vivo. The purified Esa1-Arp4 HAT complex acetylates linear nucleosomal arrays with far greater efficiency than circular arrays in vitro, indicating that it preferentially acetylates nucleosomes near a break site. Together, our data show that histone tail acetylation is required directly for DNA repair and suggest that a related human HAT complex may function similarly.
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Affiliation(s)
- Alexander W Bird
- Department of Microbiology, University of Virginia, 1300 Jefferson Park Avenue, Charlottesville, Virginia 22908, USA
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Abstract
Cohesion between sister chromatids occurs along the length of chromosomes, where it plays essential roles in chromosome segregation. We show here that the centromere, a cis-acting cohesion factor, directs the binding of Mcd1p, a cohesin subunit, to at least 2 kb regions flanking centromeres in a sequence-independent manner. The centromere is essential for the maintenance as well as the establishment of this cohesin domain. The efficiency of Mcd1p binding within the cohesin domain is independent of the primary nucleotide sequence of the centromere-flanking DNA but correlates with high A + T DNA content. Thus, the function of centromeres in the cohesion of centromere-proximal regions may be analogous to that of enhancers, nucleating cohesin complex binding over an extended chromosomal domain of A + T-rich DNA.
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Affiliation(s)
- P C Megee
- Howard Hughes Medical Institute, Department of Embryology, Carnegie Institution of Washington, Baltimore, Maryland 21210, USA
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12
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Abstract
Cohesion of sister chromatids occurs along the entire length of chromosomes, including the centromere where it plays essential roles in chromosome segregation. Here, minichromosomes in the budding yeast Saccharomyces cerevisiae are exploited to generate a functional assay for DNA sequences involved in cohesion. The centromeric DNA element CDEIII was found to be necessary but not sufficient for cohesion. This element was shown previously to be required for assembly of the kinetochore, the centromere-associated protein complex that attaches chromosomes to the spindle. These observations establish a link between centromere-proximal cohesion and kinetochore assembly.
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Affiliation(s)
- P C Megee
- Howard Hughes Medical Institute, Department of Embryology, Carnegie Institution of Washington, 115 West University Parkway, Baltimore, MD 21210, USA
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Smith MM, Yang P, Santisteban MS, Boone PW, Goldstein AT, Megee PC. A novel histone H4 mutant defective in nuclear division and mitotic chromosome transmission. Mol Cell Biol 1996; 16:1017-26. [PMID: 8622646 PMCID: PMC231084 DOI: 10.1128/mcb.16.3.1017] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The histone proteins are essential for the assembly and function of th e eukaryotic chromosome. Here we report the first isolation of a temperature-sensitive lethal histone H4 mutant defective in mitotic chromosome transmission Saccharomyces cerevisiae. The mutant requires two amino acid substitutions in histone H4: a lethal Thr-to-Ile change at position 82, which lies within one of the DNA-binding surfaces of the protein, and a substitution of Ala to Val at position 89 that is an intragenic suppressor. Genetic and biochemical evidence shows that the mutant histone H4 is temperature sensitive for function but not for synthesis, deposition, or stability. The chromatin structure of 2 micrometer circle minichromosomes is temperature sensitive in vivo, consistent with a defect in H4-DNA interactions. The mutant also has defects in transcription, displaying weak Spt- phenotypes. At the restrictive temperature, mutant cells arrest in the cell cycle at nuclear division, with a large bud, a single nucleus with 2C DNA content, and a short bipolar spindle. At semipermissive temperatures, the frequency of chromosome loss is elevated 60-fold in the mutant while DNA recombination frequencies are unaffected. High-copy CSE4, encoding an H3 variant related to the mammalian CENP-A kinetochore antigen, was found to suppress the temperature sensitivity of the mutant without suppressing the Spt- transcription defect. These genetic, biochemical, and phenotypic results indicate that this novel histone H4 mutant defines one or more chromatin-dependent steps in chromosome segregation.
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Affiliation(s)
- M M Smith
- Department of Microbiology, University of Virginia Cancer Center, Charlottesville, 22908, USA
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Abstract
The normal progression of Saccharomyces cerevisiae through nuclear division requires the function of the amino-terminal domain of histone H4. Mutations that delete the domain, or alter 4 conserved lysine residues within the domain, cause a marked delay during the G2+M phases of the cell cycle. Site-directed mutagenesis of single and multiple lysine residues failed to map this phenotype to any particular site; the defect was only observed when all four lysines were mutated. Starting with a quadruple lysine-to-glutamine substitution allele, the insertion of a tripeptide containing a single extra lysine residue suppressed the G2+M cell cycle defect. Thus, the amino-terminal domain of histone H4 has novel genetic functions that depend on the presence of lysine per se, and not a specific primary peptide sequence. To determine the nature of this function, we examined H4 mutants that were also defective for G2/M checkpoint pathways. Disruption of the mitotic spindle checkpoint pathway had no effect on the phenotype of the histone amino-terminal domain mutant. However, disruption of RAD9, which is part of the pathway that monitors DNA integrity, caused precocious progression of the H4 mutant through nuclear division and increased cell death. These results indicate that the lysine-dependent function of histone H4 is required for the maintenance of genome integrity, and that DNA damage resulting from the loss of this function activates the RAD9-dependent G2/M checkpoint pathway.
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Affiliation(s)
- P C Megee
- Department of Microbiology, University of Virginia School of Medicine Charlottesville 22908, USA
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Abstract
The nucleosome is the fundamental unit of assembly of the chromosome and reversible modifications of the histones have been suggested to be important in many aspects of nucleosome function. The structure-function relations of the amino-terminal domain of yeast histone H4 were examined by the creation of directed point mutations. The four lysines subject to reversible acetylation were essential for histone function as the substitution of arginine or asparagine at these four positions was lethal. No single lysine residue was completely essential since arginine substitutions at each position were viable, although several of these mutants were slower in completing DNA replication. The simultaneous substitution of glutamine for the four lysine residues was viable but conferred several phenotypes including mating sterility, slow progression through the G2/M period of the division cycle, and temperature-sensitive growth, as well as a prolonged period of DNA replication. These results provide genetic proof for the roles of the H4 amino-terminal domain lysines in gene expression, replication, and nuclear division.
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Affiliation(s)
- P C Megee
- Department of Microbiology, School of Medicine, University of Virginia, Charlottesville 22908
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