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Mattila J, Viitanen A, Fabris G, Strutynska T, Korzelius J, Hietakangas V. Stem cell mTOR signaling directs region-specific cell fate decisions during intestinal nutrient adaptation. Sci Adv 2024; 10:eadi2671. [PMID: 38335286 PMCID: PMC10857434 DOI: 10.1126/sciadv.adi2671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 01/09/2024] [Indexed: 02/12/2024]
Abstract
The adult intestine is a regionalized organ, whose size and cellular composition are adjusted in response to nutrient status. This involves dynamic regulation of intestinal stem cell (ISC) proliferation and differentiation. How nutrient signaling controls cell fate decisions to drive regional changes in cell-type composition remains unclear. Here, we show that intestinal nutrient adaptation involves region-specific control of cell size, cell number, and differentiation. We uncovered that activation of mTOR complex 1 (mTORC1) increases ISC size in a region-specific manner. mTORC1 activity promotes Delta expression to direct cell fate toward the absorptive enteroblast lineage while inhibiting secretory enteroendocrine cell differentiation. In aged flies, the ISC mTORC1 signaling is deregulated, being constitutively high and unresponsive to diet, which can be mitigated through lifelong intermittent fasting. In conclusion, mTORC1 signaling contributes to the ISC fate decision, enabling regional control of intestinal cell differentiation in response to nutrition.
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Affiliation(s)
- Jaakko Mattila
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00790, Finland
| | - Arto Viitanen
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00790, Finland
- Institute of Biotechnology, University of Helsinki, Helsinki 00790, Finland
| | - Gaia Fabris
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00790, Finland
- Institute of Biotechnology, University of Helsinki, Helsinki 00790, Finland
| | - Tetiana Strutynska
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00790, Finland
| | - Jerome Korzelius
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK
| | - Ville Hietakangas
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki 00790, Finland
- Institute of Biotechnology, University of Helsinki, Helsinki 00790, Finland
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2
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Tauc HM, Rodriguez-Fernandez IA, Hackney JA, Pawlak M, Ronnen Oron T, Korzelius J, Moussa HF, Chaudhuri S, Modrusan Z, Edgar BA, Jasper H. Age-related changes in polycomb gene regulation disrupt lineage fidelity in intestinal stem cells. eLife 2021; 10:62250. [PMID: 33724181 PMCID: PMC7984841 DOI: 10.7554/elife.62250] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 03/15/2021] [Indexed: 01/01/2023] Open
Abstract
Tissue homeostasis requires long-term lineage fidelity of somatic stem cells. Whether and how age-related changes in somatic stem cells impact the faithful execution of lineage decisions remains largely unknown. Here, we address this question using genome-wide chromatin accessibility and transcriptome analysis as well as single-cell RNA-seq to explore stem-cell-intrinsic changes in the aging Drosophila intestine. These studies indicate that in stem cells of old flies, promoters of Polycomb (Pc) target genes become differentially accessible, resulting in the increased expression of enteroendocrine (EE) cell specification genes. Consistently, we find age-related changes in the composition of the EE progenitor cell population in aging intestines, as well as a significant increase in the proportion of EE-specified intestinal stem cells (ISCs) and progenitors in aging flies. We further confirm that Pc-mediated chromatin regulation is a critical determinant of EE cell specification in the Drosophila intestine. Pc is required to maintain expression of stem cell genes while ensuring repression of differentiation and specification genes. Our results identify Pc group proteins as central regulators of lineage identity in the intestinal epithelium and highlight the impact of age-related decline in chromatin regulation on tissue homeostasis.
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Affiliation(s)
- Helen M Tauc
- Immunology Discovery, Genentech, South San Francisco, United States
| | | | - Jason A Hackney
- OMNI Bioinformatics, Genentech, South San Francisco, United States
| | - Michal Pawlak
- Institute of Hematology and Blood Transfusion, Warsaw, Poland
| | | | - Jerome Korzelius
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Hagar F Moussa
- Department of Biomedical Engineering and Biological Design Center,Boston University, Boston, United States
| | - Subhra Chaudhuri
- Department of Microchemistry, Proteomics, Lipidomics and Next Generation Sequencing, Genentech, South San Francisco, United States
| | - Zora Modrusan
- Immunology Discovery, Genentech, South San Francisco, United States.,Department of Microchemistry, Proteomics, Lipidomics and Next Generation Sequencing, Genentech, South San Francisco, United States
| | - Bruce A Edgar
- Huntsman Cancer Institute, University of Utah, Salt Lake City, United States
| | - Heinrich Jasper
- Immunology Discovery, Genentech, South San Francisco, United States
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3
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Middelkamp S, Vlaar JM, Giltay J, Korzelius J, Besselink N, Boymans S, Janssen R, de la Fonteijne L, van Binsbergen E, van Roosmalen MJ, Hochstenbach R, Giachino D, Talkowski ME, Kloosterman WP, Cuppen E. Prioritization of genes driving congenital phenotypes of patients with de novo genomic structural variants. Genome Med 2019; 11:79. [PMID: 31801603 PMCID: PMC6894143 DOI: 10.1186/s13073-019-0692-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 11/14/2019] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Genomic structural variants (SVs) can affect many genes and regulatory elements. Therefore, the molecular mechanisms driving the phenotypes of patients carrying de novo SVs are frequently unknown. METHODS We applied a combination of systematic experimental and bioinformatic methods to improve the molecular diagnosis of 39 patients with multiple congenital abnormalities and/or intellectual disability harboring apparent de novo SVs, most with an inconclusive diagnosis after regular genetic testing. RESULTS In 7 of these cases (18%), whole-genome sequencing analysis revealed disease-relevant complexities of the SVs missed in routine microarray-based analyses. We developed a computational tool to predict the effects on genes directly affected by SVs and on genes indirectly affected likely due to the changes in chromatin organization and impact on regulatory mechanisms. By combining these functional predictions with extensive phenotype information, candidate driver genes were identified in 16/39 (41%) patients. In 8 cases, evidence was found for the involvement of multiple candidate drivers contributing to different parts of the phenotypes. Subsequently, we applied this computational method to two cohorts containing a total of 379 patients with previously detected and classified de novo SVs and identified candidate driver genes in 189 cases (50%), including 40 cases whose SVs were previously not classified as pathogenic. Pathogenic position effects were predicted in 28% of all studied cases with balanced SVs and in 11% of the cases with copy number variants. CONCLUSIONS These results demonstrate an integrated computational and experimental approach to predict driver genes based on analyses of WGS data with phenotype association and chromatin organization datasets. These analyses nominate new pathogenic loci and have strong potential to improve the molecular diagnosis of patients with de novo SVs.
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Affiliation(s)
- Sjors Middelkamp
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Judith M Vlaar
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Jacques Giltay
- Department of Genetics, University Medical Center Utrecht, 3584 EA, Utrecht, the Netherlands
| | - Jerome Korzelius
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
- Max Planck Institute for Biology of Aging, Cologne, Germany
| | - Nicolle Besselink
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Sander Boymans
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Roel Janssen
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Lisanne de la Fonteijne
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Ellen van Binsbergen
- Department of Genetics, University Medical Center Utrecht, 3584 EA, Utrecht, the Netherlands
| | - Markus J van Roosmalen
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Ron Hochstenbach
- Department of Genetics, University Medical Center Utrecht, 3584 EA, Utrecht, the Netherlands
| | - Daniela Giachino
- Medical Genetics Unit, Department of Clinical and Biological Sciences, University of Torino, 10043, Orbassano, Italy
| | - Michael E Talkowski
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Wigard P Kloosterman
- Department of Genetics, University Medical Center Utrecht, 3584 EA, Utrecht, the Netherlands
| | - Edwin Cuppen
- Center for Molecular Medicine and Oncode Institute, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands.
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Korzelius J, Azami S, Ronnen-Oron T, Koch P, Baldauf M, Meier E, Rodriguez-Fernandez IA, Groth M, Sousa-Victor P, Jasper H. The WT1-like transcription factor Klumpfuss maintains lineage commitment of enterocyte progenitors in the Drosophila intestine. Nat Commun 2019; 10:4123. [PMID: 31511511 PMCID: PMC6739418 DOI: 10.1038/s41467-019-12003-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 08/09/2019] [Indexed: 01/01/2023] Open
Abstract
In adult epithelial stem cell lineages, the precise differentiation of daughter cells is critical to maintain tissue homeostasis. Notch signaling controls the choice between absorptive and entero-endocrine cell differentiation in both the mammalian small intestine and the Drosophila midgut, yet how Notch promotes lineage restriction remains unclear. Here, we describe a role for the transcription factor Klumpfuss (Klu) in restricting the fate of enteroblasts (EBs) in the Drosophila intestine. Klu is induced in Notch-positive EBs and its activity restricts cell fate towards the enterocyte (EC) lineage. Transcriptomics and DamID profiling show that Klu suppresses enteroendocrine (EE) fate by repressing the action of the proneural gene Scute, which is essential for EE differentiation. Loss of Klu results in differentiation of EBs into EE cells. Our findings provide mechanistic insight into how lineage commitment in progenitor cell differentiation can be ensured downstream of initial specification cues. Notch signaling mediates intestinal enteroblast specification in Drosophila but the molecular mechanism as to how this is regulated is unclear. Here, the authors show that the transcription factor Klumpfuss ensures enteroblast commitment through repression of enteroendocrine cell fate downstream of Notch.
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Affiliation(s)
- Jerome Korzelius
- Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany. .,Max-Planck-Institute for Biology of Aging, Cologne, Germany.
| | - Sina Azami
- Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany.,Max-Planck-Institute for Biology of Aging, Cologne, Germany
| | - Tal Ronnen-Oron
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945-1400, USA
| | - Philipp Koch
- Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany
| | - Maik Baldauf
- Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany
| | - Elke Meier
- Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany
| | | | - Marco Groth
- Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany
| | - Pedro Sousa-Victor
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945-1400, USA
| | - Heinrich Jasper
- Leibniz Institute on Aging-Fritz Lipmann Institute (FLI), Jena, Germany. .,Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA, 94945-1400, USA. .,Immunology Discovery, Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, USA.
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5
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Cretu Stancu M, van Roosmalen MJ, Renkens I, Nieboer MM, Middelkamp S, de Ligt J, Pregno G, Giachino D, Mandrile G, Espejo Valle-Inclan J, Korzelius J, de Bruijn E, Cuppen E, Talkowski ME, Marschall T, de Ridder J, Kloosterman WP. Mapping and phasing of structural variation in patient genomes using nanopore sequencing. Nat Commun 2017; 8:1326. [PMID: 29109544 PMCID: PMC5673902 DOI: 10.1038/s41467-017-01343-4] [Citation(s) in RCA: 226] [Impact Index Per Article: 32.3] [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: 06/30/2017] [Accepted: 09/07/2017] [Indexed: 01/08/2023] Open
Abstract
Despite improvements in genomics technology, the detection of structural variants (SVs) from short-read sequencing still poses challenges, particularly for complex variation. Here we analyse the genomes of two patients with congenital abnormalities using the MinION nanopore sequencer and a novel computational pipeline-NanoSV. We demonstrate that nanopore long reads are superior to short reads with regard to detection of de novo chromothripsis rearrangements. The long reads also enable efficient phasing of genetic variations, which we leveraged to determine the parental origin of all de novo chromothripsis breakpoints and to resolve the structure of these complex rearrangements. Additionally, genome-wide surveillance of inherited SVs reveals novel variants, missed in short-read data sets, a large proportion of which are retrotransposon insertions. We provide a first exploration of patient genome sequencing with a nanopore sequencer and demonstrate the value of long-read sequencing in mapping and phasing of SVs for both clinical and research applications.
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Affiliation(s)
- Mircea Cretu Stancu
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Markus J van Roosmalen
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Ivo Renkens
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Marleen M Nieboer
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Sjors Middelkamp
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Joep de Ligt
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Giulia Pregno
- Medical Genetics Unit, Department of Clinical and Biological Sciences, University of Torino, Orbassano, 10043, Italy
| | - Daniela Giachino
- Medical Genetics Unit, Department of Clinical and Biological Sciences, University of Torino, Orbassano, 10043, Italy
| | - Giorgia Mandrile
- Medical Genetics Unit, Department of Clinical and Biological Sciences, University of Torino, Orbassano, 10043, Italy
| | - Jose Espejo Valle-Inclan
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Jerome Korzelius
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Ewart de Bruijn
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Edwin Cuppen
- Department of Genetics and Cancer Genomics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Michael E Talkowski
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Program in Population and Medical Genetics and Stanley Center for Psychiatric Research, The Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Tobias Marschall
- Center for Bioinformatics, Saarland University, 66123, Saarbrücken, Germany
- Max Planck Institute for Informatics, 66123, Saarbrücken, Germany
| | - Jeroen de Ridder
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands
| | - Wigard P Kloosterman
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CG, Utrecht, The Netherlands.
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6
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Korzelius J, Naumann SK, Loza-Coll MA, Chan JS, Dutta D, Oberheim J, Gläßer C, Southall TD, Brand AH, Jones DL, Edgar BA. Escargot maintains stemness and suppresses differentiation in Drosophila intestinal stem cells. EMBO J 2014; 33:2967-82. [PMID: 25298397 PMCID: PMC4282643 DOI: 10.15252/embj.201489072] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Snail family transcription factors are expressed in various stem cell types, but their function in maintaining stem cell identity is unclear. In the adult Drosophila midgut, the Snail homolog Esg is expressed in intestinal stem cells (ISCs) and their transient undifferentiated daughters, termed enteroblasts (EB). We demonstrate here that loss of esg in these progenitor cells causes their rapid differentiation into enterocytes (EC) or entero-endocrine cells (EE). Conversely, forced expression of Esg in intestinal progenitor cells blocks differentiation, locking ISCs in a stem cell state. Cell type-specific transcriptome analysis combined with Dam-ID binding studies identified Esg as a major repressor of differentiation genes in stem and progenitor cells. One critical target of Esg was found to be the POU-domain transcription factor, Pdm1, which is normally expressed specifically in differentiated ECs. Ectopic expression of Pdm1 in progenitor cells was sufficient to drive their differentiation into ECs. Hence, Esg is a critical stem cell determinant that maintains stemness by repressing differentiation-promoting factors, such as Pdm1.
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Affiliation(s)
- Jerome Korzelius
- DKFZ/ZMBH Alliance, University of Heidelberg, Heidelberg, Germany
| | - Svenja K Naumann
- DKFZ/ZMBH Alliance, University of Heidelberg, Heidelberg, Germany
| | - Mariano A Loza-Coll
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA Department of Molecular, Cell, and Developmental Biology, University of California-Los Angeles, Los Angeles, CA, USA
| | - Jessica Sk Chan
- DKFZ/ZMBH Alliance, University of Heidelberg, Heidelberg, Germany
| | - Devanjali Dutta
- DKFZ/ZMBH Alliance, University of Heidelberg, Heidelberg, Germany
| | - Jessica Oberheim
- DKFZ/ZMBH Alliance, University of Heidelberg, Heidelberg, Germany
| | - Christine Gläßer
- DKFZ/ZMBH Alliance, University of Heidelberg, Heidelberg, Germany
| | - Tony D Southall
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Andrea H Brand
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - D Leanne Jones
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA Department of Molecular, Cell, and Developmental Biology, University of California-Los Angeles, Los Angeles, CA, USA
| | - Bruce A Edgar
- DKFZ/ZMBH Alliance, University of Heidelberg, Heidelberg, Germany
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7
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Korzelius J, The I, Ruijtenberg S, Portegijs V, Xu H, Horvitz HR, van den Heuvel S. C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability. Dev Biol 2011; 350:358-69. [PMID: 21146520 PMCID: PMC3322639 DOI: 10.1016/j.ydbio.2010.12.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [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: 09/01/2010] [Revised: 11/29/2010] [Accepted: 12/01/2010] [Indexed: 11/22/2022]
Abstract
DNA replication and its connection to M phase restraint are studied extensively at the level of single cells but rarely in the context of a developing animal. C. elegans lin-6 mutants lack DNA synthesis in postembryonic somatic cell lineages, while entry into mitosis continues. These mutants grow slowly and either die during larval development or develop into sterile adults. We found that lin-6 corresponds to mcm-4 and encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex. The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase. Induction of cell cycle entry and differentiation continues in developing mcm-4 larvae, even in cells that went through abortive division. In contrast to somatic cells in mcm-4 mutants, the gonad continues DNA replication and cell division until late larval development. Expression of MCM-4 in the epidermis (also known as hypodermis) is sufficient to rescue the growth retardation and lethality of mcm-4 mutants. While the somatic gonad and germline show substantial ability to cope with lack of zygotic mcm-4 function, mcm-4 is specifically required in the epidermis for growth and survival of the whole organism. Thus, C. elegans mcm-4 has conserved functions in DNA replication and replication checkpoint control but also shows unexpected tissue-specific requirements.
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Affiliation(s)
- Jerome Korzelius
- Developmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Inge The
- Developmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Suzan Ruijtenberg
- Developmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Vincent Portegijs
- Developmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Huihong Xu
- Department of Pathology and Laboratory Medicine. Boston University School of Medicine and Boston Medical Center. 670 Albany Street, Boston MA, USA
| | - H. Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge MA, United States of America
| | - Sander van den Heuvel
- Developmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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8
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Abstract
All eukaryotes use multiple controls to restrict DNA replication to once per cell cycle. Nevertheless, inactivation of a single gene, cul-4, causes massive re-replication in Caenorhabditis elegans. A novel study explains this dramatic phenotype by demonstrating that the CUL-4 E3 ligase simultaneously controls two critical licensing factors: CDT-1 and CDC-6.
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Affiliation(s)
- Jerome Korzelius
- Division of Developmental Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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Abstract
In the United States, hydatid disease of the liver is being seen with increasing frequency in persons who have immigrated from endemic areas. At the University of California, Los Angeles Medical Center, 24 patients with 46 echinococcal cysts were managed over a 26 year period. Seven patients (29 percent) had cyst rupture: into the lungs in three patients, the biliary tree in two, and the peritoneum and duodenum in one patient each. In recent years, serologic tests, computerized axial tomography, and endoscopic retrograde cholangiopancreatography have greatly aided the diagnosis and management of these patients. Four patients were treated nonoperatively, and 20 patients (with a total of 41 cysts) underwent operation. Cyst management included partial cystectomy in 19 patients, complete cystectomy in 18 patients, left hepatic lobectomy in 2 patients, and marsupialization and removal of hepatic debris from the common duct in 1 patient each. Primary cyst closure, omental packing, external drainage, or cystojejunostomy was individualized on the basis of cyst size, location, secondary infection or rupture, and communication with the biliary tree. Morbidity, including two temporary external biliary fistulas, occurred in eight patients (40 percent) but could not be related to cyst management or preoperative rupture. No deaths occurred in this series.
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