1
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Lacroix B, Vigneron S, Labbé JC, Pintard L, Lionne C, Labesse G, Castro A, Lorca T. Increases in cyclin A/Cdk activity and in PP2A-B55 inhibition by FAM122A are key mitosis-inducing events. EMBO J 2024; 43:993-1014. [PMID: 38378890 PMCID: PMC10943098 DOI: 10.1038/s44318-024-00054-z] [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: 06/19/2023] [Revised: 01/31/2024] [Accepted: 02/06/2024] [Indexed: 02/22/2024] Open
Abstract
Entry into mitosis has been classically attributed to the activation of a cyclin B/Cdk1 amplification loop via a partial pool of this kinase becoming active at the end of G2 phase. However, how this initial pool is activated is still unknown. Here we discovered a new role of the recently identified PP2A-B55 inhibitor FAM122A in triggering mitotic entry. Accordingly, depletion of the orthologue of FAM122A in C. elegans prevents entry into mitosis in germline stem cells. Moreover, data from Xenopus egg extracts strongly suggest that FAM122A-dependent inhibition of PP2A-B55 could be the initial event promoting mitotic entry. Inhibition of this phosphatase allows subsequent phosphorylation of early mitotic substrates by cyclin A/Cdk, resulting in full cyclin B/Cdk1 and Greatwall (Gwl) kinase activation. Subsequent to Greatwall activation, Arpp19/ENSA become phosphorylated and now compete with FAM122A, promoting its dissociation from PP2A-B55 and taking over its phosphatase inhibition role until the end of mitosis.
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Affiliation(s)
- Benjamin Lacroix
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, 1919 Route de Mende, 34293, Montpellier cedex 5, France
- Programme équipes Labellisées Ligue Contre le Cancer, Paris, France
| | - Suzanne Vigneron
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, 1919 Route de Mende, 34293, Montpellier cedex 5, France
- Programme équipes Labellisées Ligue Contre le Cancer, Paris, France
| | - Jean Claude Labbé
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, 1919 Route de Mende, 34293, Montpellier cedex 5, France
- Programme équipes Labellisées Ligue Contre le Cancer, Paris, France
| | - Lionel Pintard
- Programme équipes Labellisées Ligue Contre le Cancer, Paris, France
- Université Paris Cité, Institut Jacques Monod, F-75013, Paris, France
| | - Corinne Lionne
- Centre de Biologie Structurale (CBS), CNRS, INSERM, Montpellier University, Montpellier, France
| | - Gilles Labesse
- Centre de Biologie Structurale (CBS), CNRS, INSERM, Montpellier University, Montpellier, France
| | - Anna Castro
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, 1919 Route de Mende, 34293, Montpellier cedex 5, France.
- Programme équipes Labellisées Ligue Contre le Cancer, Paris, France.
| | - Thierry Lorca
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, 1919 Route de Mende, 34293, Montpellier cedex 5, France.
- Programme équipes Labellisées Ligue Contre le Cancer, Paris, France.
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2
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Horakova A, Konecna M, Anger M. Chromosome Division in Early Embryos-Is Everything under Control? And Is the Cell Size Important? Int J Mol Sci 2024; 25:2101. [PMID: 38396778 PMCID: PMC10889803 DOI: 10.3390/ijms25042101] [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: 12/22/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Chromosome segregation in female germ cells and early embryonic blastomeres is known to be highly prone to errors. The resulting aneuploidy is therefore the most frequent cause of termination of early development and embryo loss in mammals. And in specific cases, when the aneuploidy is actually compatible with embryonic and fetal development, it leads to severe developmental disorders. The main surveillance mechanism, which is essential for the fidelity of chromosome segregation, is the Spindle Assembly Checkpoint (SAC). And although all eukaryotic cells carry genes required for SAC, it is not clear whether this pathway is active in all cell types, including blastomeres of early embryos. In this review, we will summarize and discuss the recent progress in our understanding of the mechanisms controlling chromosome segregation and how they might work in embryos and mammalian embryos in particular. Our conclusion from the current literature is that the early mammalian embryos show limited capabilities to react to chromosome segregation defects, which might, at least partially, explain the widespread problem of aneuploidy during the early development in mammals.
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Affiliation(s)
- Adela Horakova
- Department of Genetics and Reproductive Biotechnologies, Veterinary Research Institute, 621 00 Brno, Czech Republic
- Institute of Animal Physiology and Genetics, Czech Academy of Science, 277 21 Libechov, Czech Republic
- Faculty of Science, Masaryk University, 602 00 Brno, Czech Republic
| | - Marketa Konecna
- Department of Genetics and Reproductive Biotechnologies, Veterinary Research Institute, 621 00 Brno, Czech Republic
- Institute of Animal Physiology and Genetics, Czech Academy of Science, 277 21 Libechov, Czech Republic
- Faculty of Science, Masaryk University, 602 00 Brno, Czech Republic
| | - Martin Anger
- Department of Genetics and Reproductive Biotechnologies, Veterinary Research Institute, 621 00 Brno, Czech Republic
- Institute of Animal Physiology and Genetics, Czech Academy of Science, 277 21 Libechov, Czech Republic
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3
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Perry JA, Werner ME, Rivenbark L, Maddox AS. Caenorhabditis elegans septins contribute to the development and structure of the oogenic germline. Cytoskeleton (Hoboken) 2023; 80:215-227. [PMID: 37265173 PMCID: PMC10524836 DOI: 10.1002/cm.21763] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/27/2023] [Accepted: 05/04/2023] [Indexed: 06/03/2023]
Abstract
Oocytes must be exceptionally large cells in order to support embryonic development. Throughout animal phylogeny, a specialized cell called a syncytium, wherein many nuclei share a continuous cytoplasm, achieves oogenesis. The syncytial nature of germline architecture is key to its function and depends on conserved components of the cortical cytoskeleton. Septins form non-polar cytoskeletal polymers that associate with membranes. In the syncytial germline of the nematode Caenorhabditis elegans, septins are highly enriched on the cortex and generally required for fertility, but the role of septins in the germline is poorly understood. We report that the C. elegans septins, UNC-59 and UNC-61, are important for germline extension during development, the maintenance of its syncytial architecture, and production of oocytes. While much of our findings substantiate the idea that the two C. elegans septins act together, we also found evidence that they have distinct functions. Loss of UNC-61 perturbed germline extension during germline development, while the loss of UNC-59 function severely affected germline architecture in adult hermaphrodites. Consultation of clustering results from a large-scale high-throughput screen suggested that septins are involved in germ cell proliferation and/or differentiation. In sum, our findings implicate a conserved cytoskeletal component in the complex architecture of a germline syncytium.
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Affiliation(s)
- Jenna A Perry
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Michael E Werner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Larry Rivenbark
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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4
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Crittenden SL, Seidel HS, Kimble J. Analysis of the C. elegans Germline Stem Cell Pool. Methods Mol Biol 2023; 2677:1-36. [PMID: 37464233 DOI: 10.1007/978-1-0716-3259-8_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
The Caenorhabditis elegans germline is an excellent model for studying the genetic and molecular regulation of stem cell self-renewal and progression of cells from a stem cell state to a differentiated state. The germline tissue is organized in an assembly line with the germline stem cell (GSC) pool at one end and differentiated gametes at the other. A simple mesenchymal niche caps the GSC pool and maintains GSCs in an undifferentiated state by signaling through the conserved Notch pathway. Notch signaling activates transcription of the key GSC regulators lst-1 and sygl-1 proteins in a gradient through the GSC pool. LST-1 and SYGL-1 proteins work with PUF RNA regulators in a self-renewal hub to maintain the GSC pool. In this chapter, we present methods for characterizing the C. elegans GSC pool and early stages of germ cell differentiation. The methods include examination of germlines in living and fixed worms, cell cycle analysis, and analysis of markers. We also discuss assays to separate mutant phenotypes that affect the stem cell vs. differentiation decision from those that affect germ cell processes more generally.
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Affiliation(s)
- Sarah L Crittenden
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
| | - Hannah S Seidel
- Department of Biology, Eastern Michigan University, Ypsilanti, MI, USA
| | - Judith Kimble
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
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5
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Gerhold AR, Labbé JC, Singh R. Uncoupling cell division and cytokinesis during germline development in metazoans. Front Cell Dev Biol 2022; 10:1001689. [PMID: 36407108 PMCID: PMC9669650 DOI: 10.3389/fcell.2022.1001689] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
The canonical eukaryotic cell cycle ends with cytokinesis, which physically divides the mother cell in two and allows the cycle to resume in the newly individualized daughter cells. However, during germline development in nearly all metazoans, dividing germ cells undergo incomplete cytokinesis and germ cells stay connected by intercellular bridges which allow the exchange of cytoplasm and organelles between cells. The near ubiquity of incomplete cytokinesis in animal germ lines suggests that this is an ancient feature that is fundamental for the development and function of this tissue. While cytokinesis has been studied for several decades, the mechanisms that enable regulated incomplete cytokinesis in germ cells are only beginning to emerge. Here we review the current knowledge on the regulation of germ cell intercellular bridge formation, focusing on findings made using mouse, Drosophila melanogaster and Caenorhabditis elegans as experimental systems.
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Affiliation(s)
- Abigail R. Gerhold
- Department of Biology, McGill University, Montréal, QC, Canada
- *Correspondence: Abigail R. Gerhold, ; Jean-Claude Labbé,
| | - Jean-Claude Labbé
- Institute for Research in Immunology and Cancer (IRIC), Montréal, QC, Canada
- Department of Pathology and Cell Biology, Université de Montréal, Succ. Centre-ville, Montréal, QC, Canada
- *Correspondence: Abigail R. Gerhold, ; Jean-Claude Labbé,
| | - Ramya Singh
- Department of Biology, McGill University, Montréal, QC, Canada
- Institute for Research in Immunology and Cancer (IRIC), Montréal, QC, Canada
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6
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Tolkin T, Hubbard EJA. Germline Stem and Progenitor Cell Aging in C. elegans. Front Cell Dev Biol 2021; 9:699671. [PMID: 34307379 PMCID: PMC8297657 DOI: 10.3389/fcell.2021.699671] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/07/2021] [Indexed: 11/13/2022] Open
Abstract
Like many animals and humans, reproduction in the nematode C. elegans declines with age. This decline is the cumulative result of age-related changes in several steps of germline function, many of which are highly accessible for experimental investigation in this short-lived model organism. Here we review recent work showing that a very early and major contributing step to reproductive decline is the depletion of the germline stem and progenitor cell pool. Since many cellular and molecular aspects of stem cell biology and aging are conserved across animals, understanding mechanisms of age-related decline of germline stem and progenitor cells in C. elegans has broad implications for aging stem cells, germline stem cells, and reproductive aging.
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Affiliation(s)
- Theadora Tolkin
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY, United States
| | - E Jane Albert Hubbard
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, NYU Grossman School of Medicine, New York, NY, United States
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7
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Bloomfield M, Chen J, Cimini D. Spindle Architectural Features Must Be Considered Along With Cell Size to Explain the Timing of Mitotic Checkpoint Silencing. Front Physiol 2021; 11:596263. [PMID: 33584330 PMCID: PMC7877541 DOI: 10.3389/fphys.2020.596263] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 12/23/2020] [Indexed: 11/25/2022] Open
Abstract
Mitosis proceeds through a defined series of events that is largely conserved, but the amount of time needed for their completion can vary in different cells and organisms. In many systems, mitotic duration depends on the time required to satisfy and silence the spindle assembly checkpoint (SAC), also known as the mitotic checkpoint. Because SAC silencing involves trafficking SAC molecules among kinetochores, spindle, and cytoplasm, the size and geometry of the spindle relative to cell volume are expected to affect mitotic duration by influencing the timing of SAC silencing. However, the relationship between SAC silencing, cell size, and spindle dimensions is unclear. To investigate this issue, we used four DLD-1 tetraploid (4N) clones characterized by small or large nuclear and cell size. We found that the small 4N clones had longer mitotic durations than the parental DLD-1 cells and that this delay was due to differences in their metaphase duration. Leveraging a previous mathematical model for spatiotemporal regulation of SAC silencing, we show that the difference in metaphase duration, i.e., SAC silencing time, can be explained by the distinct spindle microtubule densities and sizes of the cell, spindle, and spindle poles in the 4N clones. Lastly, we demonstrate that manipulating spindle geometry can alter mitotic and metaphase duration, consistent with a model prediction. Our results suggest that spindle size does not always scale with cell size in mammalian cells and cell size is not sufficient to explain the differences in metaphase duration. Only when a number of spindle architectural features are considered along with cell size can the kinetics of SAC silencing, and hence mitotic duration, in the different clones be explained.
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Affiliation(s)
- Mathew Bloomfield
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA, United States
| | - Jing Chen
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA, United States
| | - Daniela Cimini
- Department of Biological Sciences and Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA, United States
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8
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Zellag RM, Zhao Y, Poupart V, Singh R, Labbé JC, Gerhold AR. CentTracker: a trainable, machine-learning-based tool for large-scale analyses of Caenorhabditis elegans germline stem cell mitosis. Mol Biol Cell 2021; 32:915-930. [PMID: 33502892 PMCID: PMC8108535 DOI: 10.1091/mbc.e20-11-0716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Investigating the complex interactions between stem cells and their native environment requires an efficient means to image them in situ. Caenorhabditis elegans germline stem cells (GSCs) are distinctly accessible for intravital imaging; however, long-term image acquisition and analysis of dividing GSCs can be technically challenging. Here we present a systematic investigation into the technical factors impacting GSC physiology during live imaging and provide an optimized method for monitoring GSC mitosis under minimally disruptive conditions. We describe CentTracker, an automated and generalizable image analysis tool that uses machine learning to pair mitotic centrosomes and that can extract a variety of mitotic parameters rapidly from large-scale data sets. We employ CentTracker to assess a range of mitotic features in a large GSC data set. We observe spatial clustering of mitoses within the germline tissue but no evidence that subpopulations with distinct mitotic profiles exist within the stem cell pool. We further find biases in GSC spindle orientation relative to the germline’s distal–proximal axis and thus the niche. The technical and analytical tools provided herein pave the way for large-scale screening studies of multiple mitotic processes in GSCs dividing in situ, in an intact tissue, in a living animal, under seemingly physiological conditions.
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Affiliation(s)
- Réda M Zellag
- Department of Biology, McGill University, Montréal, QC H2A 1B1, Canada.,Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Yifan Zhao
- Department of Biology, McGill University, Montréal, QC H2A 1B1, Canada.,Present address: Harvard-MIT Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, MA 02139
| | - Vincent Poupart
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Ramya Singh
- Department of Biology, McGill University, Montréal, QC H2A 1B1, Canada.,Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Jean-Claude Labbé
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada.,Department of Pathology and Cell Biology, Université de Montréal, Succursale Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Abigail R Gerhold
- Department of Biology, McGill University, Montréal, QC H2A 1B1, Canada
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9
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Défachelles L, Russo AE, Nelson CR, Bhalla N. The conserved AAA-ATPase PCH-2 TRIP13 regulates spindle checkpoint strength. Mol Biol Cell 2020; 31:2219-2233. [PMID: 32697629 PMCID: PMC7550697 DOI: 10.1091/mbc.e20-05-0310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Spindle checkpoint strength is dictated by the number of unattached kinetochores, cell volume, and cell fate. We show that the conserved AAA-ATPase PCH-2/TRIP13, which remodels the checkpoint effector Mad2 from an active conformation to an inactive one, controls checkpoint strength in Caenorhabditis elegans. Having previously established that this function is required for spindle checkpoint activation, we demonstrate that in cells genetically manipulated to decrease in cell volume, PCH-2 is no longer required for the spindle checkpoint or recruitment of Mad2 at unattached kinetochores. This role is not limited to large cells: the stronger checkpoint in germline precursor cells also depends on PCH-2. PCH-2 is enriched in germline precursor cells, and this enrichment relies on conserved factors that induce asymmetry in the early embryo. Finally, the stronger checkpoint in germline precursor cells is regulated by CMT-1, the ortholog of p31comet, which is required for both PCH-2′s localization to unattached kinetochores and its enrichment in germline precursor cells. Thus, PCH-2, likely by regulating the availability of inactive Mad2 at and near unattached kinetochores, governs checkpoint strength. This requirement may be particularly relevant in oocytes and early embryos enlarged for developmental competence, cells that divide in syncytial tissues, and immortal germline cells.
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Affiliation(s)
- Lénaïg Défachelles
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Anna E Russo
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Christian R Nelson
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Needhi Bhalla
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
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10
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Recent Advances in the Genetic, Anatomical, and Environmental Regulation of the C. elegans Germ Line Progenitor Zone. J Dev Biol 2020; 8:jdb8030014. [PMID: 32707774 PMCID: PMC7559772 DOI: 10.3390/jdb8030014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/13/2020] [Accepted: 07/15/2020] [Indexed: 12/16/2022] Open
Abstract
The C. elegans germ line and its gonadal support cells are well studied from a developmental genetics standpoint and have revealed many foundational principles of stem cell niche biology. Among these are the observations that a niche-like cell supports a self-renewing stem cell population with multipotential, differentiating daughter cells. While genetic features that distinguish stem-like cells from their differentiating progeny have been defined, the mechanisms that structure these populations in the germ line have yet to be explained. The spatial restriction of Notch activation has emerged as an important genetic principle acting in the distal germ line. Synthesizing recent findings, I present a model in which the germ stem cell population of the C. elegans adult hermaphrodite can be recognized as two distinct anatomical and genetic populations. This review describes the recent progress that has been made in characterizing the undifferentiated germ cells and gonad anatomy, and presents open questions in the field and new directions for research to pursue.
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11
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Gordon KL, Zussman JW, Li X, Miller C, Sherwood DR. Stem cell niche exit in C. elegans via orientation and segregation of daughter cells by a cryptic cell outside the niche. eLife 2020; 9:e56383. [PMID: 32692313 PMCID: PMC7467730 DOI: 10.7554/elife.56383] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 07/17/2020] [Indexed: 12/17/2022] Open
Abstract
Stem cells reside in and rely upon their niche to maintain stemness but must balance self-renewal with the production of daughters that leave the niche to differentiate. We discovered a mechanism of stem cell niche exit in the canonical C. elegans distal tip cell (DTC) germ stem cell niche mediated by previously unobserved, thin, membranous protrusions of the adjacent somatic gonad cell pair (Sh1). A disproportionate number of germ cell divisions were observed at the DTC-Sh1 interface. Stem-like and differentiating cell fates segregated across this boundary. Spindles polarized, pairs of daughter cells oriented between the DTC and Sh1, and Sh1 grew over the Sh1-facing daughter. Impeding Sh1 growth by RNAi to cofilin and Arp2/3 perturbed the DTC-Sh1 interface, reduced germ cell proliferation, and shifted a differentiation marker. Because Sh1 membrane protrusions eluded detection for decades, it is possible that similar structures actively regulate niche exit in other systems.
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Affiliation(s)
- Kacy L Gordon
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - Jay W Zussman
- Department of Biology, Duke UniversityDurhamUnited States
| | - Xin Li
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - Camille Miller
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - David R Sherwood
- Department of Biology, Duke UniversityDurhamUnited States
- Regeneration Next, Duke UniversityDurhamUnited States
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12
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Hubbard EJA, Schedl T. Biology of the Caenorhabditis elegans Germline Stem Cell System. Genetics 2019; 213:1145-1188. [PMID: 31796552 PMCID: PMC6893382 DOI: 10.1534/genetics.119.300238] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 09/09/2019] [Indexed: 12/14/2022] Open
Abstract
Stem cell systems regulate tissue development and maintenance. The germline stem cell system is essential for animal reproduction, controlling both the timing and number of progeny through its influence on gamete production. In this review, we first draw general comparisons to stem cell systems in other organisms, and then present our current understanding of the germline stem cell system in Caenorhabditis elegans In contrast to stereotypic somatic development and cell number stasis of adult somatic cells in C. elegans, the germline stem cell system has a variable division pattern, and the system differs between larval development, early adult peak reproduction and age-related decline. We discuss the cell and developmental biology of the stem cell system and the Notch regulated genetic network that controls the key decision between the stem cell fate and meiotic development, as it occurs under optimal laboratory conditions in adult and larval stages. We then discuss alterations of the stem cell system in response to environmental perturbations and aging. A recurring distinction is between processes that control stem cell fate and those that control cell cycle regulation. C. elegans is a powerful model for understanding germline stem cells and stem cell biology.
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Affiliation(s)
- E Jane Albert Hubbard
- Skirball Institute of Biomolecular Medicine, Departments of Cell Biology and Pathology, New York University School of Medicine, New York 10016
| | - Tim Schedl
- and Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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13
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Lee C, Shin H, Kimble J. Dynamics of Notch-Dependent Transcriptional Bursting in Its Native Context. Dev Cell 2019; 50:426-435.e4. [PMID: 31378588 PMCID: PMC6724715 DOI: 10.1016/j.devcel.2019.07.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 05/23/2019] [Accepted: 07/01/2019] [Indexed: 12/16/2022]
Abstract
Transcription is well known to be inherently stochastic and episodic, but the regulation of transcriptional dynamics is not well understood. Here, we analyze how Notch signaling modulates transcriptional bursting during animal development. Our focus is Notch regulation of transcription in germline stem cells of the nematode C. elegans. Using the MS2 system to visualize nascent transcripts and live imaging to record dynamics, we analyze bursting as a function of position within the intact animal. We find that Notch-dependent transcriptional activation is indeed "bursty"; that wild-type Notch modulates burst duration (ON-time) rather than duration of pauses between bursts (OFF-time) or mean burst intensity; and that a mutant Notch receptor, which is compromised for assembly into the Notch transcription factor complex, primarily modifies burst size (duration × intensity). These analyses thus visualize the effect of a canonical signaling pathway on metazoan transcriptional bursting in its native context.
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Affiliation(s)
- ChangHwan Lee
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Heaji Shin
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Judith Kimble
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA; Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53706, USA.
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14
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Brown A, Geiger H. Chromosome integrity checkpoints in stem and progenitor cells: transitions upon differentiation, pathogenesis, and aging. Cell Mol Life Sci 2018; 75:3771-3779. [PMID: 30066086 PMCID: PMC6154040 DOI: 10.1007/s00018-018-2891-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 07/22/2018] [Accepted: 07/25/2018] [Indexed: 01/30/2023]
Abstract
Loss of chromosome integrity is a major contributor to cancer. Checkpoints within the cell division cycle that facilitate the accuracy and outcome of chromosome segregation are thus critical pathways for preserving chromosome integrity and preventing chromosomal instability. The spindle assembly checkpoint, the decatenation checkpoint and the post-mitotic tetraploidy checkpoint ensure the appropriate establishment of the spindle apparatus, block mitotic entry upon entanglement of chromosomes or prevent further progression of post-mitotic cells that display massive spindle defects. Most of our knowledge on these mechanisms originates from studies conducted in yeast, cancer cell lines and differentiated cells. Considering that in many instances cancer derives from transformed stem and progenitor cells, our knowledge on these checkpoints in these cells just started to emerge. With this review, we provide a general overview of the current knowledge of these checkpoints in embryonic as well as in adult stem and progenitor cells with a focus on the hematopoietic system and outline common mis-regulations of their function associated with cancer and leukemia. Most cancers are aging-associated diseases. We will thus also discuss changes in the function and outcome of these checkpoints upon aging of stem and progenitor cells.
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Affiliation(s)
- Andreas Brown
- Institute of Molecular Medicine, Ulm University, Life Science Building N27, James Franck-Ring/Meyerhofstrasse, 89081, Ulm, Germany
| | - Hartmut Geiger
- Institute of Molecular Medicine, Ulm University, Life Science Building N27, James Franck-Ring/Meyerhofstrasse, 89081, Ulm, Germany.
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA.
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15
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Gerhold AR, Poupart V, Labbé JC, Maddox PS. Spindle assembly checkpoint strength is linked to cell fate in the Caenorhabditis elegans embryo. Mol Biol Cell 2018; 29:1435-1448. [PMID: 29688794 PMCID: PMC6014101 DOI: 10.1091/mbc.e18-04-0215] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The spindle assembly checkpoint (SAC) is a conserved mitotic regulator that preserves genome stability by monitoring kinetochore-microtubule attachments and blocking anaphase onset until chromosome biorientation is achieved. Despite its central role in maintaining mitotic fidelity, the ability of the SAC to delay mitotic exit in the presence of kinetochore-microtubule attachment defects (SAC "strength") appears to vary widely. How different cellular aspects drive this variation remains largely unknown. Here we show that SAC strength is correlated with cell fate during development of Caenorhabditis elegans embryos, with germline-fated cells experiencing longer mitotic delays upon spindle perturbation than somatic cells. These differences are entirely dependent on an intact checkpoint and only partially attributable to differences in cell size. In two-cell embryos, cell size accounts for half of the difference in SAC strength between the larger somatic AB and the smaller germline P1 blastomeres. The remaining difference requires asymmetric cytoplasmic partitioning downstream of PAR polarity proteins, suggesting that checkpoint-regulating factors are distributed asymmetrically during early germ cell divisions. Our results indicate that SAC activity is linked to cell fate and reveal a hitherto unknown interaction between asymmetric cell division and the SAC.
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Affiliation(s)
- Abigail R Gerhold
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Vincent Poupart
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Jean-Claude Labbé
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada.,Department of Pathology and Cell Biology, Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Paul S Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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16
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Abstract
The Caenorhabditis elegans germline is an excellent model for studying the regulation of a pool of stem cells and progression of cells from a stem cell state to a differentiated state. At the tissue level, the germline is organized in an assembly line with the germline stem cell (GSC) pool at one end and differentiated cells at the other. A simple mesenchymal niche caps the GSC region of the germline and maintains GSCs in an undifferentiated state by signaling through the conserved Notch pathway. Downstream of Notch signaling, key regulators include novel LST-1 and SYGL-1 proteins and a network of RNA regulatory proteins. In this chapter we present methods for characterizing the C. elegans GSC pool and early germ cell differentiation. The methods include examination of the germline in living and fixed worms, cell cycle analysis, and analysis of markers. We also discuss assays to separate mutants that affect the stem cell vs. differentiation decision from those that affect germ cell processes more generally.
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Affiliation(s)
- Sarah L Crittenden
- HHMI/Department of Biochemistry, Howard Hughes Medical Institute and University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI, 53706-1544, USA.
| | - Hannah S Seidel
- HHMI/Department of Biochemistry, Howard Hughes Medical Institute and University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI, 53706-1544, USA
| | - Judith Kimble
- HHMI/Department of Biochemistry, Howard Hughes Medical Institute and University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI, 53706-1544, USA
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17
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Arena ET, Rueden CT, Hiner MC, Wang S, Yuan M, Eliceiri KW. Quantitating the cell: turning images into numbers with ImageJ. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2016; 6. [PMID: 27911038 DOI: 10.1002/wdev.260] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 10/06/2016] [Accepted: 10/15/2016] [Indexed: 01/14/2023]
Abstract
Modern biological research particularly in the fields of developmental and cell biology has been transformed by the rapid evolution of the light microscope. The light microscope, long a mainstay of the experimental biologist, is now used for a wide array of biological experimental scenarios and sample types. Much of the great developments in advanced biological imaging have been driven by the digital imaging revolution with powerful processors and algorithms. In particular, this combination of advanced imaging and computational analysis has resulted in the drive of the modern biologist to not only visually inspect dynamic phenomena, but to quantify the involved processes. This need to quantitate images has become a major thrust within the bioimaging community and requires extensible and accessible image processing routines with corresponding intuitive software packages. Novel algorithms both made specifically for light microscopy or adapted from other fields, such as astronomy, are available to biologists, but often in a form that is inaccessible for a number of reasons ranging from data input issues, usability and training concerns, and accessibility and output limitations. The biological community has responded to this need by developing open source software packages that are freely available and provide access to image processing routines. One of the most prominent is the open-source image package ImageJ. In this review, we give an overview of prominent imaging processing approaches in ImageJ that we think are of particular interest for biological imaging and that illustrate the functionality of ImageJ and other open source image analysis software. WIREs Dev Biol 2017, 6:e260. doi: 10.1002/wdev.260 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ellen T Arena
- Morgridge Institute for Research, Madison, WI, USA.,Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI, USA
| | - Curtis T Rueden
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI, USA
| | - Mark C Hiner
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI, USA
| | - Shulei Wang
- Department of Statistics, University of Wisconsin at Madison, Madison, WI, USA
| | - Ming Yuan
- Morgridge Institute for Research, Madison, WI, USA.,Department of Statistics, University of Wisconsin at Madison, Madison, WI, USA
| | - Kevin W Eliceiri
- Morgridge Institute for Research, Madison, WI, USA.,Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI, USA
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18
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Mattingly HH, Chen JJ, Arur S, Shvartsman SY. A Transport Model for Estimating the Time Course of ERK Activation in the C. elegans Germline. Biophys J 2016; 109:2436-45. [PMID: 26636953 DOI: 10.1016/j.bpj.2015.10.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 09/01/2015] [Accepted: 10/01/2015] [Indexed: 02/02/2023] Open
Abstract
The Caenorhabditis elegans germline is a well-studied model system for investigating the control of cell fate by signaling pathways. Cell signals at the distal tip of the germline promote cell proliferation; just before the loop, signals couple cell maturation to organism-level nutrient status; at the proximal end of the germline, signals coordinate oocyte maturation and fertilization in the presence of sperm. The latter two events require dual phosphorylation and activation of ERK, the effector molecule of the Ras/MAPK cascade. In C. elegans, ERK is known as MPK-1. At this point, none of today's methods for real-time monitoring of dually phosphorylated MPK-1 are working in the germline. Consequently, quantitative understanding of the MPK-1-dependent processes during germline development is limited. Here, we make a step toward advancing this understanding using a model-based framework that reconstructs the time course of MPK-1 activation from a snapshot of a fixed germline. Our approach builds on a number of recent studies for estimating temporal dynamics from fixed organisms, but takes advantage of the anatomy of the germline to simplify the analysis. Our model predicts that the MPK-1 signal turns on ∼30 h into germ cell progression and peaks ∼7 h later.
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Affiliation(s)
- Henry H Mattingly
- Department of Chemical and Biological Engineering and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey
| | - Jessica J Chen
- The University of Texas Graduate School of Biomedical Sciences and Department of Genetics, University of Texas M. D. Anderson Cancer Center, Houston, Texas
| | - Swathi Arur
- The University of Texas Graduate School of Biomedical Sciences and Department of Genetics, University of Texas M. D. Anderson Cancer Center, Houston, Texas.
| | - Stanislav Y Shvartsman
- Department of Chemical and Biological Engineering and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey.
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19
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Galli M, Morgan DO. Cell Size Determines the Strength of the Spindle Assembly Checkpoint during Embryonic Development. Dev Cell 2016; 36:344-52. [PMID: 26859356 DOI: 10.1016/j.devcel.2016.01.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Revised: 12/23/2015] [Accepted: 01/06/2016] [Indexed: 11/16/2022]
Abstract
The spindle assembly checkpoint (SAC) delays mitotic progression when chromosomes are not properly attached to microtubules of the mitotic spindle. Cells vary widely in the extent to which they delay mitotic progression upon SAC activation. To explore the mechanisms that determine checkpoint strength in different cells, we systematically measured the mitotic delay induced by microtubule disruption at different stages of embryogenesis in Caenorhabditis elegans. Strikingly, we observed a gradual increase in SAC strength after each round of division. Analysis of mutants that alter cell size or ploidy revealed that SAC strength is determined primarily by cell size and the number of kinetochores. These findings provide clear evidence in vivo that the kinetochore-to-cytoplasm ratio determines the strength of the SAC, providing new insights into why cells exhibit such large variations in their SAC responses.
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Affiliation(s)
- Matilde Galli
- Department of Physiology and Department of Biochemistry and Biophysics, University of California, 600 16(th) Street, San Francisco, CA 94143, USA.
| | - David O Morgan
- Department of Physiology and Department of Biochemistry and Biophysics, University of California, 600 16(th) Street, San Francisco, CA 94143, USA.
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20
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Park S, Greco V, Cockburn K. Live imaging of stem cells: answering old questions and raising new ones. Curr Opin Cell Biol 2016; 43:30-37. [PMID: 27474806 DOI: 10.1016/j.ceb.2016.07.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/21/2016] [Accepted: 07/07/2016] [Indexed: 11/15/2022]
Abstract
Stem cells are essential for both tissue maintenance and injury repair, but many aspects of stem cell biology remain incompletely understood. Recent advances in live imaging technology have allowed the direct visualization and tracking of a wide variety of tissue-resident stem cells in their native environments over time. Results from these studies have helped to resolve long-standing debates about stem cell regulation and function while also revealing previously unanticipated phenomena that raise new questions for future work. Here we review recent discoveries of both types, with a particular emphasis on how stem cells behave and interact with their niches during homeostasis, as well as how these behaviours change in response to wounding.
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Affiliation(s)
- Sangbum Park
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Valentina Greco
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA; Departments of Dermatology & Cell Biology, Yale Stem Cell Center, Yale Cancer Center, Yale School of Medicine, New Haven, CT 06510, USA.
| | - Katie Cockburn
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA.
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21
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Gerhold A, Labbé JC, Maddox P. Bigger Isn’t Always Better: Cell Size and the Spindle Assembly Checkpoint. Dev Cell 2016; 36:244-6. [DOI: 10.1016/j.devcel.2016.01.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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Roy D, Michaelson D, Hochman T, Santella A, Bao Z, Goldberg JD, Hubbard EJA. Cell cycle features of C. elegans germline stem/progenitor cells vary temporally and spatially. Dev Biol 2016; 409:261-271. [PMID: 26577869 PMCID: PMC4827254 DOI: 10.1016/j.ydbio.2015.10.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 10/26/2015] [Accepted: 10/27/2015] [Indexed: 11/24/2022]
Abstract
Many organisms accumulate a pool of germline stem cells during development that is maintained in later life. The dynamics of establishment, expansion and homeostatic maintenance of this pool are subject to both developmental and physiological influences including the availability of a suitable niche microenvironment, nutritional status, and age. Here, we investigated the dynamics of germline proliferation during stages of expansion and homeostasis, using the C. elegans germ line as a model. The vast majority of germ cells in the proliferative zone are in interphase stages of mitosis (G1, S, G2) rather than in the active mitotic (M) phase. We examined mitotic index and DNA content, comparing different life stages, mutants, and physiological conditions. We found that germ cells in larval stages cycle faster than in adult stages, but that this difference could not be attributed to sexual fate of the germ cells. We also found that larval germ cells exhibit a lower average DNA content compared to adult germ cells. We extended our analysis to consider the effects of distance from the niche and further found that the spatial pattern of DNA content differs between larval and adult stages in the wild type and among mutants in pathways that interfere with cell cycle progression, cell fate, or both. Finally, we characterized expansion of the proliferative pool of germ cells during adulthood, using a regeneration paradigm (ARD recovery) in which animals are starved and re-fed. We compared adult stage regeneration and larval stage expansion, and found that the adult germ line is capable of rapid accumulation but does not sustain a larval-level mitotic index nor does it recapitulate the larval pattern of DNA content. The regenerated germ line does not reach the number of proliferative zone nuclei seen in the continuously fed adult. Taken together, our results suggest that cell cycle dynamics are under multiple influences including distance from the niche, age and/or maturation of the germ line, nutrition and, possibly, latitude for physical expansion.
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Affiliation(s)
- Debasmita Roy
- Skirball Institute of Biomolecular Medicine, Helen L. and Martin S. Kimmel Center for Stem Cell Biology, Departments of Cell Biology and Pathology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - David Michaelson
- Skirball Institute of Biomolecular Medicine, Helen L. and Martin S. Kimmel Center for Stem Cell Biology, Departments of Cell Biology and Pathology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Tsivia Hochman
- Departments of Population Health and Environmental Medicine, Division of Biostatistics, New York University School of Medicine, 540 First Avenue, New York, NY, 10016, USA
| | - Anthony Santella
- Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY, 10065, USA
| | - Zhirong Bao
- Developmental Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY, 10065, USA
| | - Judith D Goldberg
- Departments of Population Health and Environmental Medicine, Division of Biostatistics, New York University School of Medicine, 540 First Avenue, New York, NY, 10016, USA
| | - E Jane Albert Hubbard
- Skirball Institute of Biomolecular Medicine, Helen L. and Martin S. Kimmel Center for Stem Cell Biology, Departments of Cell Biology and Pathology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
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23
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Abstract
In eukaryotes, the microtubule-based spindle drives chromosome segregation. In this issue, Schweizer et al. (2015; J. Cell Biol.http://dx.doi.org/10.1083/jcb.201506107) find that the spindle area is demarcated by a semipermeable organelle barrier. Molecular crowding, which is microtubule independent, causes the enrichment and/or retention of crucial factors in the spindle region. Their results add an important new feature to the models of how this structure assembles and is regulated.
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Affiliation(s)
- Paul S Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Anne-Marie Ladouceur
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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24
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Narbonne P, Maddox PS, Labbé JC. DAF-18/PTEN locally antagonizes insulin signalling to couple germline stem cell proliferation to oocyte needs in C. elegans. Development 2015; 142:4230-41. [PMID: 26552888 DOI: 10.1242/dev.130252] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 10/29/2015] [Indexed: 01/02/2023]
Abstract
During development, stem cell populations rapidly proliferate to populate the expanding tissues and organs. During this phase, nutrient status, by systemically affecting insulin/IGF-1 signalling, largely dictates stem cell proliferation rates. In adults, however, differentiated stem cell progeny requirements are generally reduced and vary according to the spatiotemporal needs of each tissue. We demonstrate here that differential regulation of germline stem cell proliferation rates in Caenorhabditis elegans adults is accomplished through localized neutralization of insulin/IGF-1 signalling, requiring DAF-18/PTEN, but not DAF-16/FOXO. Indeed, the specific accumulation of oocytes, the terminally differentiated stem cell progeny, triggers a feedback signal that locally antagonizes insulin/IGF-1 signalling outputs in the germ line, regardless of their systemic levels, to block germline stem cell proliferation. Thus, during adulthood, stem cells can differentially respond within tissues to otherwise equal insulin/IGF-1 signalling inputs, according to the needs for production of their immediate terminally differentiated progeny.
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Affiliation(s)
- Patrick Narbonne
- Département de Pathologie et Biologie Cellulaire, Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada H3T 1J4
| | - Paul S Maddox
- Département de Pathologie et Biologie Cellulaire, Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada H3T 1J4 Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jean-Claude Labbé
- Département de Pathologie et Biologie Cellulaire, Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada H3T 1J4
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25
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Seidel HS, Kimble J. Cell-cycle quiescence maintains Caenorhabditis elegans germline stem cells independent of GLP-1/Notch. eLife 2015; 4. [PMID: 26551561 PMCID: PMC4718729 DOI: 10.7554/elife.10832] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/07/2015] [Indexed: 12/13/2022] Open
Abstract
Many types of adult stem cells exist in a state of cell-cycle quiescence, yet it has remained unclear whether quiescence plays a role in maintaining the stem cell fate. Here we establish the adult germline of Caenorhabditis elegans as a model for facultative stem cell quiescence. We find that mitotically dividing germ cells--including germline stem cells--become quiescent in the absence of food. This quiescence is characterized by a slowing of S phase, a block to M-phase entry, and the ability to re-enter M phase rapidly in response to re-feeding. Further, we demonstrate that cell-cycle quiescence alters the genetic requirements for stem cell maintenance: The signaling pathway required for stem cell maintenance under fed conditions--GLP-1/Notch signaling--becomes dispensable under conditions of quiescence. Thus, cell-cycle quiescence can itself maintain stem cells, independent of the signaling pathway otherwise essential for such maintenance.
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Affiliation(s)
- Hannah S Seidel
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States.,The Ellison Medical Foundation Fellow of the Life Sciences Research Foundation, The Lawrence Ellison Foundation, Mount Airy, United States
| | - Judith Kimble
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States.,Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, United States
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