1
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Kelley LH, Caldas IV, Sullenberger MT, Yongblah KE, Niazi AM, Iyer A, Li Y, Tran PM, Valen E, Ahmed-Braimah YH, Maine EM. Poly(U) polymerase activity in Caenorhabditis elegans regulates abundance and tailing of sRNA and mRNA. Genetics 2024; 228:iyae120. [PMID: 39067069 DOI: 10.1093/genetics/iyae120] [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: 05/02/2024] [Revised: 07/09/2024] [Accepted: 07/10/2024] [Indexed: 07/30/2024] Open
Abstract
Terminal nucleotidyltransferases add nucleotides to the 3' end of RNA to modify their stability and function. In Caenorhabditis elegans, the terminal uridyltransferases/poly(U) polymerases PUP-1 (aka CID-1, CDE-1), PUP-2, and PUP-3 affect germline identity, survival, and development. Here, we identify small RNA (sRNA) and mRNA targets of these PUPs and of a fourth predicted poly(U) polymerase, F43E2.1/PUP-4. Using genetic and RNA sequencing approaches, we identify RNA targets of each PUP and the U-tail frequency and length of those targets. At the whole organism level, PUP-1 is responsible for most sRNA U-tailing, and other PUPs contribute to modifying discrete subsets of sRNAs. Moreover, the expression of PUP-2, PUP-3, and especially PUP-4 limits uridylation on some sRNAs. The relationship between uridylation status and sRNA abundance suggests that U-tailing can have a negative or positive effect on abundance depending on context. sRNAs modified by PUP activity primarily target mRNAs that are ubiquitously expressed or most highly expressed in the germline. mRNA data obtained with a Nanopore-based method reveal that the addition of U-tails to nonadenylated mRNA is substantially reduced in the absence of PUP-3. Overall, this work identifies PUP RNA targets, defines the effect of uridylation loss on RNA abundance, and reveals the complexity of PUP regulation in C. elegans development.
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Affiliation(s)
- Leanne H Kelley
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Ian V Caldas
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | | | - Kevin E Yongblah
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Adnan M Niazi
- Computational Biology Unit, Department of Informatics, University of Bergen, 5008 Bergen, Norway
| | - Anoop Iyer
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Yini Li
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Patrick Minty Tran
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Eivind Valen
- Computational Biology Unit, Department of Informatics, University of Bergen, 5008 Bergen, Norway
| | - Yasir H Ahmed-Braimah
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Eleanor M Maine
- Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
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2
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Brinkley DM, Smith KC, Fink EC, Kwen W, Yoo NH, West Z, Sullivan NL, Farthing AS, Hale VA, Goutte C. Notch signaling without the APH-2/nicastrin subunit of gamma secretase in Caenorhabditis elegans germline stem cells. Genetics 2024; 227:iyae076. [PMID: 38717968 DOI: 10.1093/genetics/iyae076] [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: 03/22/2024] [Accepted: 05/01/2024] [Indexed: 07/09/2024] Open
Abstract
The final step in Notch signaling activation is the transmembrane cleavage of Notch receptor by γ secretase. Thus far, genetic and biochemical evidence indicates that four subunits are essential for γ secretase activity in vivo: presenilin (the catalytic core), APH-1, PEN-2, and APH-2/nicastrin. Although some γ secretase activity has been detected in APH-2/nicastrin-deficient mammalian cell lines, the lack of biological relevance for this activity has left the quaternary γ secretase model unchallenged. Here, we provide the first example of in vivo Notch signal transduction without APH-2/nicastrin. The surprising dispensability of APH-2/nicastrin is observed in Caenorhabditis elegans germline stem cells (GSCs) and contrasts with its essential role in previously described C. elegans Notch signaling events. Depletion of GLP-1/Notch, presenilin, APH-1, or PEN-2 causes a striking loss of GSCs. In contrast, aph-2/nicastrin mutants maintain GSCs and exhibit robust and localized expression of the downstream Notch target sygl-1. Interestingly, APH-2/nicastrin is normally expressed in GSCs and becomes essential under conditions of compromised Notch function. Further insight is provided by reconstituting the C. elegans γ secretase complex in yeast, where we find that APH-2/nicastrin increases but is not essential for γ secretase activity. Together, our results are most consistent with a revised model of γ secretase in which the APH-2/nicastrin subunit has a modulatory, rather than obligatory role. We propose that a trimeric presenilin-APH-1-PEN-2 γ secretase complex can provide a low level of γ secretase activity, and that cellular context determines whether or not APH-2/nicastrin is essential for effective Notch signal transduction.
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Affiliation(s)
- David M Brinkley
- Program in Biochemistry and Biophysics, Amherst College, Amherst, MA 01002, USA
| | - Karen C Smith
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Emma C Fink
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Woohyun Kwen
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Nina H Yoo
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Zachary West
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Nora L Sullivan
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Alex S Farthing
- Program in Biochemistry and Biophysics, Amherst College, Amherst, MA 01002, USA
| | - Valerie A Hale
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Caroline Goutte
- Program in Biochemistry and Biophysics, Amherst College, Amherst, MA 01002, USA
- Department of Biology, Amherst College, Amherst, MA 01002, USA
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3
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Malik Y, Goncalves Silva I, Diazgranados RR, Selman C, Alic N, Tullet JM. Timing of TORC1 inhibition dictates Pol III involvement in Caenorhabditis elegans longevity. Life Sci Alliance 2024; 7:e202402735. [PMID: 38740431 DOI: 10.26508/lsa.202402735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/25/2024] [Accepted: 04/26/2024] [Indexed: 05/16/2024] Open
Abstract
Organismal growth and lifespan are inextricably linked. Target of Rapamycin (TOR) signalling regulates protein production for growth and development, but if reduced, extends lifespan across species. Reduction in the enzyme RNA polymerase III, which transcribes tRNAs and 5S rRNA, also extends longevity. Here, we identify a temporal genetic relationship between TOR and Pol III in Caenorhabditis elegans, showing that they collaborate to regulate progeny production and lifespan. Interestingly, the lifespan interaction between Pol III and TOR is only revealed when TOR signaling is reduced, specifically in adulthood, demonstrating the importance of timing to control TOR regulated developmental versus adult programs. In addition, we show that Pol III acts in C. elegans muscle to promote both longevity and healthspan and that reducing Pol III even in late adulthood is sufficient to extend lifespan. This demonstrates the importance of Pol III for lifespan and age-related health in adult C. elegans.
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Affiliation(s)
- Yasir Malik
- https://ror.org/00xkeyj56 Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury, Kent
| | - Isabel Goncalves Silva
- https://ror.org/00xkeyj56 Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury, Kent
| | - Rene Rivera Diazgranados
- https://ror.org/00xkeyj56 Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury, Kent
| | - Colin Selman
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Scotland
| | - Nazif Alic
- UCL Department of Genetics, Evolution & Environment, Institute of Healthy Ageing, London, UK
| | - Jennifer Ma Tullet
- https://ror.org/00xkeyj56 Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury, Kent
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4
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Jones M, Norman M, Tiet AM, Lee J, Lee MH. C. elegans Germline as Three Distinct Tumor Models. BIOLOGY 2024; 13:425. [PMID: 38927305 PMCID: PMC11200432 DOI: 10.3390/biology13060425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Revised: 06/04/2024] [Accepted: 06/07/2024] [Indexed: 06/28/2024]
Abstract
Tumor cells display abnormal growth and division, avoiding the natural process of cell death. These cells can be benign (non-cancerous growth) or malignant (cancerous growth). Over the past few decades, numerous in vitro or in vivo tumor models have been employed to understand the molecular mechanisms associated with tumorigenesis in diverse regards. However, our comprehension of how non-tumor cells transform into tumor cells at molecular and cellular levels remains incomplete. The nematode C. elegans has emerged as an excellent model organism for exploring various phenomena, including tumorigenesis. Although C. elegans does not naturally develop cancer, it serves as a valuable platform for identifying oncogenes and the underlying mechanisms within a live organism. In this review, we describe three distinct germline tumor models in C. elegans, highlighting their associated mechanisms and related regulators: (1) ectopic proliferation due to aberrant activation of GLP-1/Notch signaling, (2) meiotic entry failure resulting from the loss of GLD-1/STAR RNA-binding protein, (3) spermatogenic dedifferentiation caused by the loss of PUF-8/PUF RNA-binding protein. Each model requires the mutations of specific genes (glp-1, gld-1, and puf-8) and operates through distinct molecular mechanisms. Despite these differences in the origins of tumorigenesis, the internal regulatory networks within each tumor model display shared features. Given the conservation of many of the regulators implicated in C. elegans tumorigenesis, it is proposed that these unique models hold significant potential for enhancing our comprehension of the broader control mechanisms governing tumorigenesis.
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Affiliation(s)
- Mariah Jones
- Division of Hematology/Oncology, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA; (M.J.); (M.N.)
| | - Mina Norman
- Division of Hematology/Oncology, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA; (M.J.); (M.N.)
| | - Alex Minh Tiet
- Neuroscience Program, East Carolina University, Greenville, NC 27858, USA;
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
| | - Jiwoo Lee
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
| | - Myon Hee Lee
- Division of Hematology/Oncology, Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA; (M.J.); (M.N.)
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
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5
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Pires da Silva A, Kelleher R, Reynoldson L. Decoding lifespan secrets: the role of the gonad in Caenorhabditis elegans aging. FRONTIERS IN AGING 2024; 5:1380016. [PMID: 38605866 PMCID: PMC11008531 DOI: 10.3389/fragi.2024.1380016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 03/18/2024] [Indexed: 04/13/2024]
Abstract
The gonad has become a central organ for understanding aging in C. elegans, as removing the proliferating stem cells in the germline results in significant lifespan extension. Similarly, when starvation in late larval stages leads to the quiescence of germline stem cells the adult nematode enters reproductive diapause, associated with an extended lifespan. This review summarizes recent advancements in identifying the mechanisms behind gonad-mediated lifespan extension, including comparisons with other nematodes and the role of lipid signaling and transcriptional changes. Given that the gonad also mediates lifespan regulation in other invertebrates and vertebrates, elucidating the underlying mechanisms may help to gain new insights into the mechanisms and evolution of aging.
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6
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Zhang X, Wang Y, Cai Z, Wan Z, Aihemaiti Y, Tu H. A gonadal gap junction INX-14/Notch GLP-1 signaling axis suppresses gut defense through an intestinal lysosome pathway. Front Immunol 2023; 14:1249436. [PMID: 37928537 PMCID: PMC10620905 DOI: 10.3389/fimmu.2023.1249436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/03/2023] [Indexed: 11/07/2023] Open
Abstract
Gap junctions mediate intercellular communications across cellular networks in the nervous and immune systems. Yet their roles in intestinal innate immunity are poorly understood. Here, we show that the gap junction/innexin subunit inx-14 acts in the C. elegans gonad to attenuate intestinal defenses to Pseudomonas aeruginosa PA14 infection through the PMK-1/p38 pathway. RNA-Seq analyses revealed that germline-specific inx-14 RNAi downregulated Notch/GLP-1 signaling, while lysosome and PMK-1/p38 pathways were upregulated. Consistently, disruption of inx-14 or glp-1 in the germline enhanced resistance to PA14 infection and upregulated lysosome and PMK-1/p38 activity. We show that lysosome signaling functions downstream of the INX-14/GLP-1 signaling axis and upstream of PMK-1/p38 pathway to facilitate intestinal defense. Our findings expand the understanding of the links between the reproductive system and intestinal defense, which may be evolutionarily conserved in higher organism.
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Affiliation(s)
| | | | | | | | | | - Haijun Tu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan University, Changsha, Hunan, China
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7
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Beydoun S, Sridhar A, Tuckowski AM, Wang E, Leiser SF. C22 disrupts embryogenesis and extends C. elegans lifespan. Front Physiol 2023; 14:1241554. [PMID: 37791350 PMCID: PMC10544340 DOI: 10.3389/fphys.2023.1241554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 09/05/2023] [Indexed: 10/05/2023] Open
Abstract
Caenorhabditis elegans is an instrumental model in aging research due to its large brood size, short lifespan, and malleable genetics. However, maintaining a synchronous nematode population for longevity studies is challenging and time consuming due to their quick rate of development and reproduction. Multiple methods are employed in the field, ranging from worm strains with temperature dependent sterility to DNA replication inhibitors such as 5'-fluorodeoxyuridine (FUdR). In this study, we characterize a small molecule (C22) that impairs eggshell integrity and disrupts early embryogenesis to determine its applicability as a potential FUdR alternative. We find that C22 prevents egg hatching in a concentration dependent manner. However, it extends the lifespan of wild type worms and can induce FMO-2, a longevity regulating enzyme downstream of dietary restriction. Our results suggest that C22 is unlikely to be widely useful as an alternative to FUdR but its mechanism for lifespan extension may be worth further investigation.
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Affiliation(s)
- Safa Beydoun
- Molecular and Integrative Physiology Department, University of Michigan, Ann Arbor, MI, United States
| | - Aditya Sridhar
- Molecular, Cellular and Developmental Biology Department, University of Michigan, Ann Arbor, MI, United States
| | - Angela M. Tuckowski
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, United States
| | - Emily Wang
- Molecular and Integrative Physiology Department, University of Michigan, Ann Arbor, MI, United States
| | - Scott F. Leiser
- Molecular and Integrative Physiology Department, University of Michigan, Ann Arbor, MI, United States
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, United States
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8
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Wilson IBH, Yan S, Jin C, Dutkiewicz Z, Rendić D, Palmberger D, Schnabel R, Paschinger K. Increasing Complexity of the N-Glycome During Caenorhabditis Development. Mol Cell Proteomics 2023; 22:100505. [PMID: 36717059 PMCID: PMC7614267 DOI: 10.1016/j.mcpro.2023.100505] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/06/2023] [Accepted: 01/24/2023] [Indexed: 01/30/2023] Open
Abstract
Caenorhabditis elegans is a frequently employed genetic model organism and has been the object of a wide range of developmental, genetic, proteomic, and glycomic studies. Here, using an off-line MALDI-TOF-MS approach, we have analyzed the N-glycans of mixed embryos and liquid- or plate-grown L4 larvae. Of the over 200 different annotatable N-glycan structures, variations between the stages as well as the mode of cultivation were observed. While the embryonal N-glycome appears less complicated overall, the liquid- and plate-grown larvae differ especially in terms of methylation of bisecting fucose, α-galactosylation of mannose, and di-β-galactosylation of core α1,6-fucose. Furthermore, we analyzed the O-glycans by LC-electrospray ionization-MS following β-elimination; especially the embryonal O-glycomes included a set of phosphorylcholine-modified structures, previously not shown to exist in nematodes. However, the set of glycan structures cannot be clearly correlated with levels of glycosyltransferase transcripts in developmental RNA-Seq datasets, but there is an indication for coordinated expression of clusters of potential glycosylation-relevant genes. Thus, there are still questions to be answered in terms of how and why a simple nematode synthesizes such a diverse glycome.
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Affiliation(s)
- Iain B H Wilson
- Department für Chemie, Universität für Bodenkultur, Wien, Austria.
| | - Shi Yan
- Department für Chemie, Universität für Bodenkultur, Wien, Austria; Institut für Parasitologie, Veterinärmedizinische Universität Wien, Wien, Austria
| | - Chunsheng Jin
- Institutionen för Biomedicin, Göteborgs universitet, Göteborg, Sweden
| | | | - Dubravko Rendić
- Department für Chemie, Universität für Bodenkultur, Wien, Austria
| | | | - Ralf Schnabel
- Institut für Genetik, Technische Universität Braunschweig, Braunschweig, Germany
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9
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Velayudhan SS, Ellis RE. Functional divergence of orthologous temperature-sensitive mutations in C. elegans and C. briggsae. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000705. [PMID: 36575738 PMCID: PMC9790080 DOI: 10.17912/micropub.biology.000705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/01/1970] [Accepted: 12/09/2022] [Indexed: 12/29/2022]
Abstract
To learn if orthologous mutations are temperature-sensitive in related species, we studied four C. briggsae mutations orthologous to alleles of important C. elegans genes. Both Cel-glp-4(bn2) and Cbr-glp-4(v473) are temperature-sensitive, causing sterility at 25°C. By contrast, Cel-fog-1 ( q253) is strongly ts , but its ortholog Cbr-fog-1(v442) causes a loss-of-function at all temperatures. Finally, the C. elegans glp-1 alleles bn18 and e2141 are ts sterile. However, their C. briggsae orthologs, Cbr-glp-1(v429) and Cbr-glp-1(v438) respectively, are wild-type at all temperatures. Thus, a ts mutation in one species provides clues about how to design ts alleles in another, but all theoretical outcomes are possible.
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Affiliation(s)
| | - Ronald E Ellis
- Rowan University SOM
,
Correspondence to: Ronald E Ellis (
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10
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Li X, Singh N, Miller C, Washington I, Sosseh B, Gordon KL. The C. elegans gonadal sheath Sh1 cells extend asymmetrically over a differentiating germ cell population in the proliferative zone. eLife 2022; 11:e75497. [PMID: 36094368 PMCID: PMC9467509 DOI: 10.7554/elife.75497] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 08/08/2022] [Indexed: 12/04/2022] Open
Abstract
The Caenorhabditis elegans adult hermaphrodite germline is surrounded by a thin tube formed by somatic sheath cells that support germ cells as they mature from the stem-like mitotic state through meiosis, gametogenesis, and ovulation. Recently, we discovered that the distal Sh1 sheath cells associate with mitotic germ cells as they exit the niche Gordon et al., 2020. Here, we report that these sheath-associated germ cells differentiate first in animals with temperature-sensitive mutations affecting germ cell state, and stem-like germ cells are maintained distal to the Sh1 boundary. We analyze several markers of the distal sheath, which is best visualized with endogenously tagged membrane proteins, as overexpressed fluorescent proteins fail to localize to distal membrane processes and can cause gonad morphology defects. However, such reagents with highly variable expression can be used to determine the relative positions of the two Sh1 cells, one of which often extends further distal than the other.
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Affiliation(s)
- Xin Li
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - Noor Singh
- 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
| | - India Washington
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - Bintou Sosseh
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
| | - Kacy Lynn Gordon
- Department of Biology, The University of North Carolina at Chapel HillChapel HillUnited States
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11
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Vanden Broek K, Han X, Hansen D. Redundant mechanisms regulating the proliferation vs. differentiation balance in the C. elegans germline. Front Cell Dev Biol 2022; 10:960999. [PMID: 36120589 PMCID: PMC9479330 DOI: 10.3389/fcell.2022.960999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 08/15/2022] [Indexed: 11/21/2022] Open
Abstract
The proper production of gametes over an extended portion of the life of an organism is essential for a high level of fitness. The balance between germline stem cell (GSC) proliferation (self-renewal) and differentiation (production of gametes) must be tightly regulated to ensure proper gamete production and overall fitness. Therefore, organisms have evolved robust regulatory systems to control this balance. Here we discuss the redundancy in the regulatory system that controls the proliferation vs. differentiation balance in the C. elegans hermaphrodite germline, and how this redundancy may contribute to robustness. We focus on the various types of redundancy utilized to regulate this balance, as well as the approaches that have enabled these redundant mechanisms to be uncovered.
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12
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Agarwal P, Shemesh T, Zaidel-Bar R. Directed cell invasion and asymmetric adhesion drive tissue elongation and turning in C. elegans gonad morphogenesis. Dev Cell 2022; 57:2111-2126.e6. [PMID: 36049484 DOI: 10.1016/j.devcel.2022.08.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/03/2022] [Accepted: 08/09/2022] [Indexed: 12/15/2022]
Abstract
Development of the C. elegans gonad has long been studied as a model of organogenesis driven by collective cell migration. A somatic cell named the distal tip cell (DTC) is thought to serve as the leader of following germ cells; yet, the mechanism for DTC propulsion and maneuvering remains elusive. Here, we demonstrate that the DTC is not self-propelled but rather is pushed by the proliferating germ cells. Proliferative pressure pushes the DTC forward, against the resistance of the basement membrane in front. The DTC locally secretes metalloproteases that degrade the impeding membrane, resulting in gonad elongation. Turning of the gonad is achieved by polarized DTC-matrix adhesions. The asymmetrical traction results in a bending moment on the DTC. Src and Cdc42 regulate integrin adhesion polarity, whereas an external netrin signal determines DTC orientation. Our findings challenge the current view of DTC migration and offer a distinct framework to understand organogenesis.
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Affiliation(s)
- Priti Agarwal
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Tom Shemesh
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.
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13
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Dai Z, Zhang W, Shang M, Tang H, Wu L, Wu Y, Wang T, Bian P. A Non-Cell-Autonomous Mode of DNA Damage Response in Soma of Caenorhabditis elegans. Int J Mol Sci 2022; 23:ijms23147544. [PMID: 35886900 PMCID: PMC9318560 DOI: 10.3390/ijms23147544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/01/2022] [Accepted: 07/01/2022] [Indexed: 02/01/2023] Open
Abstract
Life has evolved a mechanism called DNA damage response (DDR) to sense, signal and remove/repair DNA damage, and its deficiency and dysfunction usually lead to genomic instability and development of cancer. The signaling mode of the DDR has been believed to be of cell-autonomy. However, the paradigm is being shifted with in-depth research into model organism Caenorhabditis elegans. Here, we mainly investigate the effect of DDR activation on the radiosensitivity of vulva of C. elegans, and first found that the vulval radiosensitivity is mainly regulated by somatic DDR, rather than the DDR of germline. Subsequently, the worm lines with pharynx-specific rescue of DDR were constructed, and it is shown that the 9-1-1-ATR and MRN-ATM cascades in pharynx restore approximately 90% and 70% of vulval radiosensitivity, respectively, through distantly regulating the NHEJ repair of vulval cells. The results suggest that the signaling cascade of DDR might also operate in a non-cell autonomous mode. To further explore the underlying regulatory mechanisms, the cpr-4 mutated gene is introduced into the DDR-rescued worms, and CPR-4, a cysteine protease cathepsin B, is confirmed to mediate the inter-tissue and inter-individual regulation of DDR as a signaling molecule downstream of 9-1-1-ATR. Our findings throw some light on the regulation of DNA repair in soma of C. elegans, and might also provide new cues for cancer prevention and treatment.
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Affiliation(s)
- Zhangyu Dai
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; (Z.D.); (W.Z.); (H.T.); (Y.W.)
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China
| | - Wenjing Zhang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; (Z.D.); (W.Z.); (H.T.); (Y.W.)
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China
| | - Mengke Shang
- Institute of Physical Science and Information Technology, Anhui University, Hefei 230601, China; (M.S.); (L.W.)
| | - Huangqi Tang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; (Z.D.); (W.Z.); (H.T.); (Y.W.)
| | - Lijun Wu
- Institute of Physical Science and Information Technology, Anhui University, Hefei 230601, China; (M.S.); (L.W.)
| | - Yuejin Wu
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; (Z.D.); (W.Z.); (H.T.); (Y.W.)
| | - Ting Wang
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei 230032, China
- Correspondence: (T.W.); (P.B.)
| | - Po Bian
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China; (Z.D.); (W.Z.); (H.T.); (Y.W.)
- Teaching and Research Section of Nuclear Medicine, School of Basic Medical Sciences, Anhui Medical University, Hefei 230032, China
- Correspondence: (T.W.); (P.B.)
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14
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Xin N, Durieux J, Yang C, Wolff S, Kim HE, Dillin A. The UPRmt preserves mitochondrial import to extend lifespan. J Cell Biol 2022; 221:e202201071. [PMID: 35608535 PMCID: PMC9134095 DOI: 10.1083/jcb.202201071] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/14/2022] [Accepted: 04/26/2022] [Indexed: 01/07/2023] Open
Abstract
The mitochondrial unfolded protein response (UPRmt) is dedicated to promoting mitochondrial proteostasis and is linked to extreme longevity. The key regulator of this process is the transcription factor ATFS-1, which, upon UPRmt activation, is excluded from the mitochondria and enters the nucleus to regulate UPRmt genes. However, the repair proteins synthesized as a direct result of UPRmt activation must be transported into damaged mitochondria that had previously excluded ATFS-1 owing to reduced import efficiency. To address this conundrum, we analyzed the role of the import machinery when the UPRmt was induced. Using in vitro and in vivo analysis of mitochondrial proteins, we surprisingly find that mitochondrial import increases when the UPRmt is activated in an ATFS-1-dependent manner, despite reduced mitochondrial membrane potential. The import machinery is upregulated, and an intact import machinery is essential for UPRmt-mediated lifespan extension. ATFS-1 has a weak mitochondrial targeting sequence (MTS), allowing for dynamic subcellular localization during the initial stages of UPRmt activation.
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Affiliation(s)
- Nan Xin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
- Department of Integrated Biology and Pharmacology, University of Texas, Health Science Center, Houston, TX
| | - Jenni Durieux
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Chunxia Yang
- Department of Integrated Biology and Pharmacology, University of Texas, Health Science Center, Houston, TX
| | - Suzanne Wolff
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Hyun-Eui Kim
- Department of Integrated Biology and Pharmacology, University of Texas, Health Science Center, Houston, TX
| | - Andrew Dillin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
- Howard Hughes Medical Institute, Chevy Chase, MD
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15
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Robinson-Thiewes S, Kershner AM, Shin H, Haupt KA, Kroll-Connor P, Kimble J. A sensitized genetic screen to identify regulators of Caenorhabditis elegans germline stem cells. G3 (BETHESDA, MD.) 2022; 12:jkab439. [PMID: 35100350 PMCID: PMC9210287 DOI: 10.1093/g3journal/jkab439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/08/2021] [Indexed: 11/26/2022]
Abstract
GLP-1/Notch signaling and a downstream RNA regulatory network maintain germline stem cells in Caenorhabditis elegans. In mutants lacking the GLP-1 receptor, all germline stem cells enter the meiotic cell cycle precociously and differentiate into sperm. This dramatic germline stem cell defect is called the "Glp" phenotype. The lst-1 and sygl-1 genes are direct targets of Notch transcriptional activation and functionally redundant. Whereas single lst-1 and sygl-1 mutants are fertile, lst-1 sygl-1 double mutants are sterile with a Glp phenotype. We set out to identify genes that function redundantly with either lst-1 or sygl-1 to maintain germline stem cells. To this end, we conducted forward genetic screens for mutants with a Glp phenotype in genetic backgrounds lacking functional copies of either lst-1 or sygl-1. The screens generated 9 glp-1 alleles, 2 lst-1 alleles, and 1 allele of pole-1, which encodes the catalytic subunit of DNA polymerase ε. Three glp-1 alleles reside in Ankyrin repeats not previously mutated. pole-1 single mutants have a low penetrance Glp phenotype that is enhanced by loss of sygl-1. Thus, the screen uncovered 1 locus that interacts genetically with sygl-1 and generated useful mutations for further studies of germline stem cell regulation.
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Affiliation(s)
| | | | - Heaji Shin
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kimberly A Haupt
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Peggy Kroll-Connor
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Judith Kimble
- Department of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
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16
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Garcia G, Homentcovschi S, Kelet N, Higuchi-Sanabria R. Imaging of Actin Cytoskeletal Integrity During Aging in C. elegans. Methods Mol Biol 2022; 2364:101-137. [PMID: 34542850 DOI: 10.1007/978-1-0716-1661-1_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The actin cytoskeleton plays a fundamental role in the regulation of multiple cellular pathways, including trafficking and locomotion. The functional integrity of the cytoskeleton is important during aging, as the decline of cytoskeletal integrity contributes to the physiological consequence of aging. Moreover, improving cytoskeletal form and function throughout aging is sufficient to drive life span extension and promote organismal health in multiple model systems. For these reasons, optimized protocols for visualization of the actin cytoskeleton and its downstream consequences on health span and life span are critical for understanding the aging process. In C. elegans, the actin cytoskeleton shows diverse morphologies across tissues, potentially due to the significantly different functions of each cell type. This chapter describes an imaging platform utilizing LifeAct to visualize the actin cytoskeleton in live, whole nematodes throughout the aging process and methods to perform follow-up studies on the life span and health span of these organisms.
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Affiliation(s)
- Gilberto Garcia
- Department of Molecular & Cellular Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Stefan Homentcovschi
- Department of Molecular & Cellular Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Naame Kelet
- Department of Molecular & Cellular Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Ryo Higuchi-Sanabria
- Department of Molecular & Cellular Biology, University of California, Berkeley, Berkeley, CA, USA.
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA.
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17
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Singh R, Smit RB, Wang X, Wang C, Racher H, Hansen D. Reduction of Derlin activity suppresses Notch-dependent tumours in the C. elegans germ line. PLoS Genet 2021; 17:e1009687. [PMID: 34555015 PMCID: PMC8491880 DOI: 10.1371/journal.pgen.1009687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 10/05/2021] [Accepted: 09/08/2021] [Indexed: 11/19/2022] Open
Abstract
Regulating the balance between self-renewal (proliferation) and differentiation is key to the long-term functioning of all stem cell pools. In the Caenorhabditis elegans germline, the primary signal controlling this balance is the conserved Notch signaling pathway. Gain-of-function mutations in the GLP-1/Notch receptor cause increased stem cell self-renewal, resulting in a tumour of proliferating germline stem cells. Notch gain-of-function mutations activate the receptor, even in the presence of little or no ligand, and have been associated with many human diseases, including cancers. We demonstrate that reduction in CUP-2 and DER-2 function, which are Derlin family proteins that function in endoplasmic reticulum-associated degradation (ERAD), suppresses the C. elegans germline over-proliferation phenotype associated with glp-1(gain-of-function) mutations. We further demonstrate that their reduction does not suppress other mutations that cause over-proliferation, suggesting that over-proliferation suppression due to loss of Derlin activity is specific to glp-1/Notch (gain-of-function) mutations. Reduction of CUP-2 Derlin activity reduces the expression of a read-out of GLP-1/Notch signaling, suggesting that the suppression of over-proliferation in Derlin loss-of-function mutants is due to a reduction in the activity of the mutated GLP-1/Notch(GF) receptor. Over-proliferation suppression in cup-2 mutants is only seen when the Unfolded Protein Response (UPR) is functioning properly, suggesting that the suppression, and reduction in GLP-1/Notch signaling levels, observed in Derlin mutants may be the result of activation of the UPR. Chemically inducing ER stress also suppress glp-1(gf) over-proliferation but not other mutations that cause over-proliferation. Therefore, ER stress and activation of the UPR may help correct for increased GLP-1/Notch signaling levels, and associated over-proliferation, in the C. elegans germline. Notch signaling is a highly conserved signaling pathway that is utilized in many cell fate decisions in many organisms. In the C. elegans germline, Notch signaling is the primary signal that regulates the balance between stem cell proliferation and differentiation. Notch gain-of-function mutations cause the receptor to be active, even when a signal that is normally needed to activate the receptor is absent. In the germline of C. elegans, gain-of-function mutations in GLP-1, a Notch receptor, results in over-proliferation of the stem cells and tumour formation. Here we demonstrate that a reduction or loss of Derlin activity, which is a conserved family of proteins involved in endoplasmic reticulum-associated degradation (ERAD), suppresses over-proliferation due to GLP-1/Notch gain-of-function mutations. Furthermore, we demonstrate that a surveillance mechanism utilized in cells to monitor and react to proteins that are not folded properly (Unfolded Protein Response-UPR) must be functioning well in order for the loss of Derlin activity to supress over-proliferation caused by glp-1/Notch gain-of-function mutations. This suggests that activation of the UPR may be the mechanism at work for suppressing this type of over-proliferation, when Derlin activity is reduced. Therefore, decreasing Derlin activity may be a means of reducing the impact of phenotypes and diseases due to certain Notch gain-of-function mutations.
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Affiliation(s)
- Ramya Singh
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Ryan B. Smit
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Xin Wang
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Chris Wang
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Hilary Racher
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Dave Hansen
- Department of Biological Sciences, University of Calgary, Calgary, Canada
- * E-mail:
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18
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Pushpa K, Dagar S, Kumar H, Pathak D, Mylavarapu SVS. The exocyst complex regulates C. elegans germline stem cell proliferation by controlling membrane Notch levels. Development 2021; 148:271155. [PMID: 34338279 DOI: 10.1242/dev.196345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 06/30/2021] [Indexed: 11/20/2022]
Abstract
The conserved exocyst complex regulates plasma membrane-directed vesicle fusion in eukaryotes. However, its role in stem cell proliferation has not been reported. Germline stem cell (GSC) proliferation in the nematode Caenorhabditis elegans is regulated by conserved Notch signaling. Here, we reveal that the exocyst complex regulates C. elegans GSC proliferation by modulating Notch signaling cell autonomously. Notch membrane density is asymmetrically maintained on GSCs. Knockdown of exocyst complex subunits or of the exocyst-interacting GTPases Rab5 and Rab11 leads to Notch redistribution from the GSC-niche interface to the cytoplasm, suggesting defects in plasma membrane Notch deposition. The anterior polarity (aPar) protein Par6 is required for GSC proliferation, and for maintaining niche-facing membrane levels of Notch and the exocyst complex. The exocyst complex biochemically interacts with the aPar regulator Par5 (14-3-3ζ) and Notch in C. elegans and human cells. Exocyst components are required for Notch plasma membrane localization and signaling in mammalian cells. Our study uncovers a possibly conserved requirement of the exocyst complex in regulating GSC proliferation and in maintaining optimal membrane Notch levels.
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Affiliation(s)
- Kumari Pushpa
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Sunayana Dagar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha 751024, India
| | - Harsh Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Diksha Pathak
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Sivaram V S Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha 751024, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
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19
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Mayya VK, Flamand MN, Lambert AM, Jafarnejad SM, Wohlschlegel JA, Sonenberg N, Duchaine TF. microRNA-mediated translation repression through GYF-1 and IFE-4 in C. elegans development. Nucleic Acids Res 2021; 49:4803-4815. [PMID: 33758928 PMCID: PMC8136787 DOI: 10.1093/nar/gkab162] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/24/2021] [Accepted: 03/17/2021] [Indexed: 12/11/2022] Open
Abstract
microRNA (miRNA)-mediated gene silencing is enacted through the recruitment of effector proteins that direct translational repression or degradation of mRNA targets, but the relative importance of their activities for animal development remains unknown. Our concerted proteomic surveys identified the uncharacterized GYF-domain encoding protein GYF-1 and its direct interaction with IFE-4, the ortholog of the mammalian translation repressor 4EHP, as key miRNA effector proteins in Caenorhabditis elegans. Recruitment of GYF-1 protein to mRNA reporters in vitro or in vivo leads to potent translation repression without affecting the poly(A) tail or impinging on mRNA stability. Loss of gyf-1 is synthetic lethal with hypomorphic alleles of embryonic miR-35-42 and larval (L4) let-7 miRNAs, which is phenocopied through engineered mutations in gyf-1 that abolish interaction with IFE-4. GYF-1/4EHP function is cascade-specific, as loss of gyf-1 had no noticeable impact on the functions of other miRNAs, including lin-4 and lsy-6. Overall, our findings reveal the first direct effector of miRNA-mediated translational repression in C. elegans and its physiological importance for the function of several, but likely not all miRNAs.
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Affiliation(s)
- Vinay K Mayya
- Goodman Cancer Research Center, McGill University, Montréal H3G 1Y6, Canada.,Department of Biochemistry, McGill University, Montréal H3G 1Y6, Canada
| | - Mathieu N Flamand
- Goodman Cancer Research Center, McGill University, Montréal H3G 1Y6, Canada.,Department of Biochemistry, McGill University, Montréal H3G 1Y6, Canada
| | - Alice M Lambert
- Goodman Cancer Research Center, McGill University, Montréal H3G 1Y6, Canada.,Department of Biochemistry, McGill University, Montréal H3G 1Y6, Canada
| | - Seyed Mehdi Jafarnejad
- Patrick G. Johnston Centre for Cancer Research, Queen's University of Belfast, Belfast BT9 7AE UK
| | - James A Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Nahum Sonenberg
- Goodman Cancer Research Center, McGill University, Montréal H3G 1Y6, Canada.,Department of Biochemistry, McGill University, Montréal H3G 1Y6, Canada
| | - Thomas F Duchaine
- Goodman Cancer Research Center, McGill University, Montréal H3G 1Y6, Canada.,Department of Biochemistry, McGill University, Montréal H3G 1Y6, Canada
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20
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Abstract
Polymerase Chain Reaction (PCR) is a powerful tool to detect natural variation or experimentally introduced variation in research and clinical settings and a widely-used method for genotyping. Single nucleotide polymorphisms (SNP) detection is challenging by PCR as the variant and wild type alleles differ by only one nucleotide. Traditional methods to detect SNPs, including Sanger sequencing and commercial kits, are usually time-consuming. Here we describe a simple primer design strategy that enables specific variant detection through regular one-step PCR. The strategy employs the differential efficiency of genomic PCR using a primer that has a single mismatch with the chromosome that contains the SNP to be detected (typically the variant allele) versus two mismatches with the corresponding alternative allele (typically the wild type allele). To date, we have successfully employed this approach to detect more than 20 SNPs. The simplicity and robustness of the approach allows rapid application to legacy mutations as well as newly discovered or generated SNPs.
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Affiliation(s)
- Jian Chen
- Department of Genetics, School of Medicine, Washington University in St. Louis, Missouri 63110
| | - Tim Schedl
- Department of Genetics, School of Medicine, Washington University in St. Louis, Missouri 63110
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21
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Jia F, Chi C, Han M. Regulation of Nucleotide Metabolism and Germline Proliferation in Response to Nucleotide Imbalance and Genotoxic Stresses by EndoU Nuclease. Cell Rep 2021; 30:1848-1861.e5. [PMID: 32049015 PMCID: PMC7050212 DOI: 10.1016/j.celrep.2020.01.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 12/06/2019] [Accepted: 01/15/2020] [Indexed: 12/23/2022] Open
Abstract
Nucleotide deprivation and imbalance present detrimental conditions for animals and are thus expected to trigger cellular responses that direct protective changes in metabolic, developmental, and behavioral programs, albeit such mechanisms are vastly underexplored. Following our previous finding that Caenorhabditis elegans shut down germ cell proliferation in response to pyrimidine deprivation, we find in this study that endonuclease ENDU-2 regulates nucleotide metabolism and germ cell proliferation in response to nucleotide imbalance and other genotoxic stress, and that it affects mitotic chromosomal segregation in the intestine and lifespan. ENDU-2 expression is induced by nucleotide imbalance and genotoxic stress, and ENDU-2 exerts its function in the intestine, mostly by inhibiting the phosphorylation of CTPS-1 through repressing the PKA pathway and histone deacetylase HDA-1. Human EndoU also affects the response to genotoxic drugs. Our work reveals an unknown role of ENDU-2 in regulating nucleotide metabolism and animals' response to genotoxic stress, which may link EndoU function to cancer treatment.
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Affiliation(s)
- Fan Jia
- Department of Molecular, Cellular, and Developmental Biology (MCDB), University of Colorado at Boulder, Boulder, CO 80309-0347, USA.
| | - Congwu Chi
- Department of Molecular, Cellular, and Developmental Biology (MCDB), University of Colorado at Boulder, Boulder, CO 80309-0347, USA
| | - Min Han
- Department of Molecular, Cellular, and Developmental Biology (MCDB), University of Colorado at Boulder, Boulder, CO 80309-0347, USA
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22
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Gonzalez-Hunt CP, Luz AL, Ryde IT, Turner EA, Ilkayeva OR, Bhatt DP, Hirschey MD, Meyer JN. Multiple metabolic changes mediate the response of Caenorhabditis elegans to the complex I inhibitor rotenone. Toxicology 2021; 447:152630. [PMID: 33188857 PMCID: PMC7750303 DOI: 10.1016/j.tox.2020.152630] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 11/05/2020] [Accepted: 11/09/2020] [Indexed: 12/21/2022]
Abstract
Rotenone, a mitochondrial complex I inhibitor, has been widely used to study the effects of mitochondrial dysfunction on dopaminergic neurons in the context of Parkinson's disease. Although the deleterious effects of rotenone are well documented, we found that young adult Caenorhabditis elegans showed resistance to 24 and 48 h rotenone exposures. To better understand the response to rotenone in C. elegans, we evaluated mitochondrial bioenergetic parameters after 24 and 48 h exposures to 1 μM or 5 μM rotenone. Results suggested upregulation of mitochondrial complexes II and V following rotenone exposure, without major changes in oxygen consumption or steady-state ATP levels after rotenone treatment at the tested concentrations. We found evidence that the glyoxylate pathway (an alternate pathway not present in higher metazoans) was induced by rotenone exposure; gene expression measurements showed increases in mRNA levels for two complex II subunits and for isocitrate lyase, the key glyoxylate pathway enzyme. Targeted metabolomics analyses showed alterations in the levels of organic acids, amino acids, and acylcarnitines, consistent with the metabolic restructuring of cellular bioenergetic pathways including activation of complex II, the glyoxylate pathway, glycolysis, and fatty acid oxidation. This expanded understanding of how C. elegans responds metabolically to complex I inhibition via multiple bioenergetic adaptations, including the glyoxylate pathway, will be useful in interrogating the effects of mitochondrial and bioenergetic stressors and toxicants.
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Affiliation(s)
- Claudia P Gonzalez-Hunt
- Department of Nicholas School of the Environment, Duke University, Durham, NC, 27708, United States
| | - Anthony L Luz
- Department of Nicholas School of the Environment, Duke University, Durham, NC, 27708, United States
| | - Ian T Ryde
- Department of Nicholas School of the Environment, Duke University, Durham, NC, 27708, United States
| | - Elena A Turner
- Department of Nicholas School of the Environment, Duke University, Durham, NC, 27708, United States
| | - Olga R Ilkayeva
- Duke Molecular Physiology Institute, Durham, NC, 27710, United States; Sarah W. Stedman Nutrition and Metabolism Center, Durham, NC, 27710, United States
| | - Dhaval P Bhatt
- Duke Molecular Physiology Institute, Durham, NC, 27710, United States
| | - Matthew D Hirschey
- Duke Molecular Physiology Institute, Durham, NC, 27710, United States; Sarah W. Stedman Nutrition and Metabolism Center, Durham, NC, 27710, United States; Departments of Medicine and Pharmacology & Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, United States
| | - Joel N Meyer
- Department of Nicholas School of the Environment, Duke University, Durham, NC, 27708, United States.
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23
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Lopes AFC, Bozek K, Herholz M, Trifunovic A, Rieckher M, Schumacher B. A C. elegans model for neurodegeneration in Cockayne syndrome. Nucleic Acids Res 2020; 48:10973-10985. [PMID: 33021672 PMCID: PMC7641758 DOI: 10.1093/nar/gkaa795] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/08/2020] [Accepted: 09/27/2020] [Indexed: 12/22/2022] Open
Abstract
Cockayne syndrome (CS) is a congenital syndrome characterized by growth and mental retardation, and premature ageing. The complexity of CS and mammalian models warrants simpler metazoan models that display CS-like phenotypes that could be studied in the context of a live organism. Here, we provide a characterization of neuronal and mitochondrial aberrations caused by a mutation in the csb-1 gene in Caenorhabditis elegans. We report a progressive neurodegeneration in adult animals that is enhanced upon UV-induced DNA damage. The csb-1 mutants show dysfunctional hyperfused mitochondria that degrade upon DNA damage, resulting in diminished respiratory activity. Our data support the role of endogenous DNA damage as a driving factor of CS-related neuropathology and underline the role of mitochondrial dysfunction in the disease.
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Affiliation(s)
- Amanda F C Lopes
- Institute for Genome Stability in Aging and Disease, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Katarzyna Bozek
- Center for Molecular Medicine (CMMC), Faculty of Medicine and University Hospital Cologne, University of Cologne, Robert-Koch-Str. 21, 50931 Cologne, Germany
| | - Marija Herholz
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
- Institute for Mitochondrial Diseases and Aging, Medical Faculty, University of Cologne, D-50931 Cologne, Germany
| | - Aleksandra Trifunovic
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
- Center for Molecular Medicine (CMMC), Faculty of Medicine and University Hospital Cologne, University of Cologne, Robert-Koch-Str. 21, 50931 Cologne, Germany
- Institute for Mitochondrial Diseases and Aging, Medical Faculty, University of Cologne, D-50931 Cologne, Germany
| | - Matthias Rieckher
- Institute for Genome Stability in Aging and Disease, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Björn Schumacher
- Institute for Genome Stability in Aging and Disease, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
- Center for Molecular Medicine (CMMC), Faculty of Medicine and University Hospital Cologne, University of Cologne, Robert-Koch-Str. 21, 50931 Cologne, Germany
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24
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Sural S, Liang CY, Wang FY, Ching TT, Hsu AL. HSB-1/HSF-1 pathway modulates histone H4 in mitochondria to control mtDNA transcription and longevity. SCIENCE ADVANCES 2020; 6:eaaz4452. [PMID: 33087356 PMCID: PMC7577724 DOI: 10.1126/sciadv.aaz4452] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 09/08/2020] [Indexed: 06/02/2023]
Abstract
Heat shock factor-1 (HSF-1) is a master regulator of stress responses across taxa. Overexpression of HSF-1 or genetic ablation of its conserved negative regulator, heat shock factor binding protein 1 (HSB-1), results in robust life-span extension in Caenorhabditis elegans Here, we found that increased HSF-1 activity elevates histone H4 levels in somatic tissues during development, while knockdown of H4 completely suppresses HSF-1-mediated longevity. Moreover, overexpression of H4 is sufficient to extend life span. Ablation of HSB-1 induces an H4-dependent increase in micrococcal nuclease protection of both nuclear chromatin and mitochondrial DNA (mtDNA), which consequently results in reduced transcription of mtDNA-encoded complex IV genes, decreased respiratory capacity, and a mitochondrial unfolded protein response-dependent life-span extension. Collectively, our findings reveal a previously unknown role of HSB-1/HSF-1 signaling in modulation of mitochondrial function via mediating histone H4-dependent regulation of mtDNA gene expression and concomitantly acting as a determinant of organismal longevity.
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Affiliation(s)
- Surojit Sural
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Chung-Yi Liang
- Research Center for Healthy Aging, China Medical University, Taichung, 404, Taiwan
| | - Feng-Yung Wang
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan
| | - Tsui-Ting Ching
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei 112, Taiwan.
| | - Ao-Lin Hsu
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.
- Research Center for Healthy Aging, China Medical University, Taichung, 404, Taiwan
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan
- Division of Geriatric and Palliative Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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25
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Sorensen EB, Seidel HS, Crittenden SL, Ballard JH, Kimble J. A toolkit of tagged glp-1 alleles reveals strong glp-1 expression in the germline, embryo, and spermatheca. MICROPUBLICATION BIOLOGY 2020; 2020. [PMID: 32626848 PMCID: PMC7326335 DOI: 10.17912/micropub.biology.000271] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
| | | | | | | | - Judith Kimble
- University of Wisconsin-Madison and HHMI, Madison, WI
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26
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Chen J, Mohammad A, Pazdernik N, Huang H, Bowman B, Tycksen E, Schedl T. GLP-1 Notch-LAG-1 CSL control of the germline stem cell fate is mediated by transcriptional targets lst-1 and sygl-1. PLoS Genet 2020; 16:e1008650. [PMID: 32196486 PMCID: PMC7153901 DOI: 10.1371/journal.pgen.1008650] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/13/2020] [Accepted: 02/04/2020] [Indexed: 12/16/2022] Open
Abstract
Stem cell systems are essential for the development and maintenance of polarized tissues. Intercellular signaling pathways control stem cell systems, where niche cells signal stem cells to maintain the stem cell fate/self-renewal and inhibit differentiation. In the C. elegans germline, GLP-1 Notch signaling specifies the stem cell fate, employing the sequence-specific DNA binding protein LAG-1 to implement the transcriptional response. We undertook a comprehensive genome-wide approach to identify transcriptional targets of GLP-1 signaling. We expected primary response target genes to be evident at the intersection of genes identified as directly bound by LAG-1, from ChIP-seq experiments, with genes identified as requiring GLP-1 signaling for RNA accumulation, from RNA-seq analysis. Furthermore, we performed a time-course transcriptomics analysis following auxin inducible degradation of LAG-1 to distinguish between genes whose RNA level was a primary or secondary response of GLP-1 signaling. Surprisingly, only lst-1 and sygl-1, the two known target genes of GLP-1 in the germline, fulfilled these criteria, indicating that these two genes are the primary response targets of GLP-1 Notch and may be the sole germline GLP-1 signaling protein-coding transcriptional targets for mediating the stem cell fate. In addition, three secondary response genes were identified based on their timing following loss of LAG-1, their lack of a LAG-1 ChIP-seq peak and that their glp-1 dependent mRNA accumulation could be explained by a requirement for lst-1 and sygl-1 activity. Moreover, our analysis also suggests that the function of the primary response genes lst-1 and sygl-1 can account for the glp-1 dependent peak protein accumulation of FBF-2, which promotes the stem cell fate and, in part, for the spatial restriction of elevated LAG-1 accumulation to the stem cell region. Stem cell systems are central to tissue development, homeostasis and regeneration, where niche to stem cell signaling pathways promote the stem cell fate/self-renewal and inhibit differentiation. The evolutionarily conserved GLP-1 Notch signaling pathway in the C. elegans germline is an experimentally tractable system, allowing dissection of control of the stem cell fate and inhibition of meiotic development. However, as in many systems, the primary molecular targets of the signaling pathway in stem cells is incompletely known, as are secondary molecular targets, and this knowledge is essential for a deep understanding of stem cell systems. Here we focus on the identification of the primary transcriptional targets of the GLP-1 signaling pathway that promotes the stem cell fate, employing unbiased multilevel genomic approaches. We identify only lst-1 and sygl-1, two of a number of previously reported targets, as likely the sole primary mRNA transcriptional targets of GLP-1 signaling that promote the germline stem cell fate. We also identify secondary GLP-1 signaling RNA and protein targets, whose expression shows dependence on lst-1 and sygl-1, where the protein targets reinforce the importance of posttranscriptional regulation in control of the stem cell fate.
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Affiliation(s)
- Jian Chen
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Ariz Mohammad
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Nanette Pazdernik
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Current address, Integrated DNA Technologies, Coralville, Iowa, United States of America
| | - Huiyan Huang
- Department of Pediatrics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Beth Bowman
- Department of Biology, Emory University, Atlanta, Georgia, United States of America
- Current address, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Eric Tycksen
- Genome Technology Access Center, McDonnell Genome Institute, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Tim Schedl
- Department of Genetics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
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27
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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: 73] [Impact Index Per Article: 14.6] [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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28
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Qu M, Qiu Y, Kong Y, Wang D. Amino modification enhances reproductive toxicity of nanopolystyrene on gonad development and reproductive capacity in nematode Caenorhabditis elegans. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 254:112978. [PMID: 31398636 DOI: 10.1016/j.envpol.2019.112978] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/09/2019] [Accepted: 07/28/2019] [Indexed: 05/20/2023]
Abstract
Although amino modified nanopolystyrene could cause toxicity on environmental organisms, the effect of amino modification on nanopolystyrene toxicity is still largely unclear. We here employed Caenorhabditis elegans as an animal model to compare the effects between pristine and amino modified nanopolystyrene particles in inducing reproductive toxicity. Nanopolystyrene (35 nm) could cause the damage on gonad development as indicated by the endpoints of number of total germline cells, length of gonad arm, and relative area of gonad arm. Nanopolystyrene exposure also reduced the reproductive capacity as reflected by the endpoints of brood size and number of fertilized eggs in uterus. Moreover, amino modification enhanced nanopolystyrene toxicity on both the gonad development and the reproductive capacity. Additionally, induction of germline apoptosis and formation of germline DNA damage contributed to the enhancement of nanopolystyrene toxicity in reducing reproductive capacity by amino modification. Our results highlight the potential environmental risk of amino modified nanopolystyrene in inducing reproductive toxicity on gonad development and reproductive capacity of environmental organisms.
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Affiliation(s)
- Man Qu
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education, Medical School, Southeast University, Nanjing 210009, China
| | - Yuexiu Qiu
- School of Public Health, Southeast University, Nanjing 210009, China
| | - Yan Kong
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education, Medical School, Southeast University, Nanjing 210009, China
| | - Dayong Wang
- Key Laboratory of Environmental Medicine Engineering in Ministry of Education, Medical School, Southeast University, Nanjing 210009, China; Guangdong Provincial Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China.
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29
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Tang B, Tong P, Xue KS, Williams PL, Wang JS, Tang L. High-throughput assessment of toxic effects of metal mixtures of cadmium(Cd), lead(Pb), and manganese(Mn) in nematode Caenorhabditis elegans. CHEMOSPHERE 2019; 234:232-241. [PMID: 31220657 DOI: 10.1016/j.chemosphere.2019.05.271] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/28/2019] [Accepted: 05/29/2019] [Indexed: 06/09/2023]
Abstract
Heavy metals, a class of persistent environmental toxicants, are harmful to human health. Cd and Pb are two of the most common toxic heavy metals that have been linked with cancers and malfunction of the nervous system. Notably, contamination of Mn usually coexisted with Cd and Pb in environmental and occupational settings. Studies regularly examined the toxic effects on individual metals; however, potential health and toxic effects of mixtures containing two or more heavy metals are unknown. Here, we investigated toxic effects of Cd, Pb, Mn, and their binary and ternary mixtures in the nematode Caenorhabdities elegans. The toxic outcomes, including effects on growth, reproduction, and feeding, were measured via high-throughput platform analysis. The transgenic strain BY250 with GFP in dopaminergic neurons was used to explore the neurodegenerative effects induced by single metals or their mixtures. The combination index(CI) for mixtures effect was calculated using isobolograms methods. Following the exposure, we found significant toxic effects in C. elegans. For single metals, the toxicity order for growth, reproduction, and feeding were Pb > Cd > Mn. For mixtures, the mixture of Cd + Mn induced a less than addictive effect in C. elegans, whereas the mixtures of Cd + Pb, Pb + Mn, and Cd + Pb + Mn induced greater-than-additive effects. Both single metals and their mixtures induced abnormality in dopaminergic neurons. These results showed combinative toxic and neurodegenerative effects of heavy metal mixtures, and future studies will focus on characterization of concentration-response patterns and identification of potential molecular mechanisms in C. elegans model.
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Affiliation(s)
- Bowen Tang
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA, USA
| | - Ping Tong
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, China
| | - Kathy S Xue
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA, USA
| | - Phillip L Williams
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA, USA
| | - Jia-Sheng Wang
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA, USA
| | - Lili Tang
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA, USA.
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30
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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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31
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Jordan JM, Hibshman JD, Webster AK, Kaplan REW, Leinroth A, Guzman R, Maxwell CS, Chitrakar R, Bowman EA, Fry AL, Hubbard EJA, Baugh LR. Insulin/IGF Signaling and Vitellogenin Provisioning Mediate Intergenerational Adaptation to Nutrient Stress. Curr Biol 2019; 29:2380-2388.e5. [PMID: 31280992 PMCID: PMC6650306 DOI: 10.1016/j.cub.2019.05.062] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 04/19/2019] [Accepted: 05/24/2019] [Indexed: 12/22/2022]
Abstract
The roundworm C. elegans reversibly arrests larval development during starvation [1], but extended early-life starvation reduces reproductive success [2, 3]. Maternal dietary restriction (DR) buffers progeny from starvation as young larvae, preserving reproductive success [4]. However, the developmental basis of reduced fertility following early-life starvation is unknown, and it is unclear how maternal diet modifies developmental physiology in progeny. We show here that extended starvation in first-stage (L1) larvae followed by unrestricted feeding results in a variety of developmental abnormalities in the reproductive system, including proliferative germ-cell tumors and uterine masses that express neuronal and epidermal cell fate markers. We found that maternal DR and reduced maternal insulin/insulin-like growth factor (IGF) signaling (IIS) increase oocyte provisioning of vitellogenin lipoprotein, reducing penetrance of starvation-induced abnormalities in progeny, including tumors. Furthermore, we show that maternal DR and reduced maternal IIS reduce IIS in progeny. daf-16/FoxO and skn-1/Nrf, transcriptional effectors of IIS, are required in progeny for maternal DR and increased vitellogenin provisioning to suppress starvation-induced abnormalities. daf-16/FoxO activity in somatic tissues is sufficient to suppress starvation-induced abnormalities, suggesting cell-nonautonomous regulation of reproductive system development. This work reveals that early-life starvation compromises reproductive development and that vitellogenin-mediated intergenerational insulin/IGF-to-insulin/IGF signaling mediates adaptation to nutrient availability.
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Affiliation(s)
- James M Jordan
- Department of Biology, Duke University, Durham, NC 27708, USA
| | | | - Amy K Webster
- Department of Biology, Duke University, Durham, NC 27708, USA
| | | | | | - Ryan Guzman
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Colin S Maxwell
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Rojin Chitrakar
- Department of Biology, Duke University, Durham, NC 27708, USA
| | | | - Amanda L Fry
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - E Jane Albert Hubbard
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - L Ryan Baugh
- Department of Biology, Duke University, Durham, NC 27708, USA.
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32
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Revtovich AV, Lee R, Kirienko NV. Interplay between mitochondria and diet mediates pathogen and stress resistance in Caenorhabditis elegans. PLoS Genet 2019; 15:e1008011. [PMID: 30865620 PMCID: PMC6415812 DOI: 10.1371/journal.pgen.1008011] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 02/09/2019] [Indexed: 12/22/2022] Open
Abstract
Diet is a crucial determinant of organismal biology; interactions between the host, its diet, and its microbiota are critical to determining the health of an organism. A variety of genetic and biochemical means were used to assay stress sensitivity in C. elegans reared on two standard laboratory diets: E. coli OP50, the most commonly used food for C. elegans, or E. coli HT115, which is typically used for RNAi-mediated gene knockdown. We demonstrated that the relatively subtle shift to a diet of E. coli HT115 had a dramatic impact on C. elegans's survival after exposure to pathogenic or abiotic stresses. Interestingly, this was independent of canonical host defense pathways. Instead the change arises from improvements in mitochondrial health, likely due to alleviation of a vitamin B12 deficiency exhibited by worms reared on an E. coli OP50 diet. Increasing B12 availability, by feeding on E. coli HT115, supplementing E. coli OP50 with exogenous vitamin B12, or overexpression of the B12 transporter, improved mitochondrial homeostasis and increased resistance. Loss of the methylmalonyl-CoA mutase gene mmcm-1/MUT, which requires vitamin B12 as a cofactor, abolished these improvements, establishing a genetic basis for the E. coli OP50-incurred sensitivity. Our study forges a mechanistic link between a dietary deficiency (nutrition/microbiota) and a physiological consequence (host sensitivity), using the host-microbiota-diet framework.
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Affiliation(s)
- Alexey V. Revtovich
- Department of BioSciences, Rice University, Houston TX, United States of America
| | - Ryan Lee
- Department of BioSciences, Rice University, Houston TX, United States of America
| | - Natalia V. Kirienko
- Department of BioSciences, Rice University, Houston TX, United States of America
- * E-mail:
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33
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Li Y, Maine EM. The balance of poly(U) polymerase activity ensures germline identity, survival and development in Caenorhabditis elegans. Development 2018; 145:145/19/dev165944. [PMID: 30305273 DOI: 10.1242/dev.165944] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 08/29/2018] [Indexed: 12/21/2022]
Abstract
Poly(U) polymerases (PUPs) catalyze 3' uridylation of mRNAs and small RNAs, a modification often correlating with decreased RNA stability. We have investigated the importance of three proteins with in vitro PUP activity, PUP-1/CDE-1, PUP-2 and PUP-3, in C. elegans germline development. Genetic analysis indicates that PUP-1/CDE-1 and PUP-2 are developmentally redundant under conditions of temperature stress during which they ensure germline viability and development. Multiple lines of evidence indicate that pup-1/-2 double mutant germ cells fail to maintain their identity as distinct from soma. Consistent with phenotypic data, PUP-1 and PUP-2 are expressed in embryonic germ cell precursors and throughout germline development. The developmental importance of PUP activity is presumably in regulating gene expression as both a direct and indirect consequence of modifying target RNAs. PUP-3 is significantly overexpressed in the pup-1/-2 germline, and loss of pup-3 function partially suppresses pup-1/-2 germline defects. We conclude that one major function of PUP-1/-2 is to limit PUP-3 expression. Overall, the balance of PUP-1, PUP-2 and PUP-3 activities appears to ensure proper germline development.
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Affiliation(s)
- Yini Li
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
| | - Eleanor M Maine
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
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34
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Berardi S, McFall A, Toledo-Hernandez A, Coote C, Graham H, Stine L, Rhodehouse K, Auernhamer A, Van Wynsberghe PM. The Period protein homolog LIN-42 regulates germline development in C. elegans. Mech Dev 2018; 153:42-53. [PMID: 30144508 DOI: 10.1016/j.mod.2018.08.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/20/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022]
Abstract
Germline stem cells are maintained in the distal region of the C. elegans gonad. These cells undergo mitotic divisions, and GLP-1/Notch signaling dictates whether they remain in this state. The somatic distal tip cell (DTC) caps the end of the distal gonad and is essential for maintenance of the germline mitotic zone. As germ cells move away from the DTC they exit mitosis and enter early meiotic prophase. Here we identify the Period protein homolog LIN-42 as a new regulator of germline development in C. elegans. LIN-42 is expressed in almost all somatic cells including the DTC, and LIN-42 functions as a transcription factor in the heterochronic pathway and to regulate molting. We found that the mitotic proliferative zone size in the distal gonad was significantly reduced by ~25% in lin-42 mutants compared to WT N2 worms. A lin-42 mutation also reduced the mitotic proliferative zone size caused by glp-1 partial loss-of-function and gain-of-function alleles. LIN-42 mediates this effect, at least in part, by regulating expression of the GLP-1/Notch ligand LAG-2. We further show that lin-42 expression itself is regulated by ATX-2, which promotes germline proliferation and is the homolog of the RNA binding protein ataxin-2 that is implicated in human neurodegenerative diseases. Altogether our results establish a new role for the conserved, important Period protein homolog LIN-42 in regulating early germline development. These results also suggest that in addition to regulating behavioral rhythms, the circadian clock plays an important role in communicating environmental signals to essential reproductive pathways.
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Affiliation(s)
- Skyler Berardi
- Department of Biology, Colgate University, Hamilton, NY 13346, USA
| | - Alanna McFall
- Department of Biology, Colgate University, Hamilton, NY 13346, USA
| | | | - Carolyn Coote
- Department of Biology, Colgate University, Hamilton, NY 13346, USA
| | - Hillary Graham
- Department of Biology, Colgate University, Hamilton, NY 13346, USA
| | - Laurel Stine
- Department of Biology, Colgate University, Hamilton, NY 13346, USA
| | - Kyle Rhodehouse
- Department of Biology, Colgate University, Hamilton, NY 13346, USA
| | - Anna Auernhamer
- Department of Biology, Colgate University, Hamilton, NY 13346, USA
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35
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Gutnik S, Thomas Y, Guo Y, Stoecklin J, Neagu A, Pintard L, Merlet J, Ciosk R. PRP-19, a conserved pre-mRNA processing factor and E3 ubiquitin ligase, inhibits the nuclear accumulation of GLP-1/Notch intracellular domain. Biol Open 2018; 7:bio034066. [PMID: 30012553 PMCID: PMC6078339 DOI: 10.1242/bio.034066] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 06/15/2018] [Indexed: 01/13/2023] Open
Abstract
The Notch signalling pathway is a conserved and widespread signalling paradigm, and its misregulation has been implicated in numerous disorders, including cancer. The output of Notch signalling depends on the nuclear accumulation of the Notch receptor intracellular domain (ICD). Using the Caenorhabditis elegans germline, where GLP-1/Notch-mediated signalling is essential for maintaining stem cells, we monitored GLP-1 in vivo We found that the nuclear enrichment of GLP-1 ICD is dynamic: while the ICD is enriched in germ cell nuclei during larval development, it is depleted from the nuclei in adult germlines. We found that this pattern depends on the ubiquitin proteolytic system and the splicing machinery and, identified the splicing factor PRP-19 as a candidate E3 ubiquitin ligase required for the nuclear depletion of GLP-1 ICD.
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Affiliation(s)
- Silvia Gutnik
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Yann Thomas
- Cell Cycle and Development, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris, France
| | - Yanwu Guo
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, 0316 Oslo, Norway
| | - Janosch Stoecklin
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Anca Neagu
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Lionel Pintard
- Cell Cycle and Development, Institut Jacques Monod, UMR7592 CNRS - Université Paris Diderot, Sorbonne Paris Cité, F-75013 Paris, France
| | - Jorge Merlet
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Developmental Biology Laboratory, UMR 7622, F-75005 Paris, France
| | - Rafal Ciosk
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, 0316 Oslo, Norway
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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36
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Yoon DS, Cha DS, Alfhili MA, Keiper BD, Lee MH. Subunits of the DNA polymerase alpha-primase complex promote Notch-mediated proliferation with discrete and shared functions in C. elegans germline. FEBS J 2018; 285:2590-2604. [PMID: 29775245 DOI: 10.1111/febs.14512] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 05/04/2018] [Accepted: 05/15/2018] [Indexed: 11/27/2022]
Abstract
Notch receptor signaling is a highly conserved cell communication system in most multicellular organisms and plays a critical role at several junctures in animal development. In Caenorhabditis elegans,GLP-1/Notch signaling is essential for both germline stem cell maintenance and germ cell proliferation during gonad development. Here, we show that subunits (POLA-1, DIV-1, PRI-1, and PRI-2) of the DNA polymerase alpha-primase complex are required for germ cell proliferation in response to GLP-1/Notch signaling in different tissues at different developmental stages. Specifically, genetic and functional analyses demonstrated that (a) maternally contributed DIV-1 (regulatory subunit) is indispensable non-cell autonomously for GLP-1/Notch-mediated germ cell proliferation during early larval development, whereas POLA-1 (catalytic subunit) and two primase subunits, PRI-1 and PRI-2, do not appear to be essential; (b) germline POLA-1, PRI-1, and PRI-2 play a crucial role in GLP-1/Notch-mediated maintenance of proliferative cell fate during adulthood, while DIV-1 is dispensable; and (c) germline POLA-1, DIV-1, PRI-1, and PRI-2 function in tandem with PUF (Pumilio/FBF) RNA-binding proteins to maintain germline stem cells in the adult gonad. These findings suggest that the subunits of the DNA polymerase alpha-primase complex exhibit both discrete and shared functions in GLP-1/Notch or PUF-mediated germ cell dynamics in C. elegans. These findings link the biological functions of DNA replication machineries to signals that maintain a stem cell population, and may have further implications for Notch-dependent tumors.
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Affiliation(s)
- Dong Suk Yoon
- Department of Medicine (Hematology/Oncology), Brody School of Medicine at East Carolina University, Greenville, NC, USA
| | - Dong Seok Cha
- Department of Medicine (Hematology/Oncology), Brody School of Medicine at East Carolina University, Greenville, NC, USA.,Department of Oriental Pharmacy, College of Pharmacy, Woosuk University, Jeonbuk, Korea
| | - Mohammad A Alfhili
- Department of Medicine (Hematology/Oncology), Brody School of Medicine at East Carolina University, Greenville, NC, USA.,Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Brett D Keiper
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC, USA
| | - Myon-Hee Lee
- Department of Medicine (Hematology/Oncology), Brody School of Medicine at East Carolina University, Greenville, NC, USA.,Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, NC, USA
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37
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HOP-1 Presenilin Deficiency Causes a Late-Onset Notch Signaling Phenotype That Affects Adult Germline Function in Caenorhabditis elegans. Genetics 2017; 208:745-762. [PMID: 29242286 DOI: 10.1534/genetics.117.300605] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 12/11/2017] [Indexed: 12/31/2022] Open
Abstract
Functionally redundant genes present a puzzle as to their evolutionary preservation, and offer an interesting opportunity for molecular specialization. In Caenorhabditis elegans, either one of two presenilin genes (sel-12 or hop-1) facilitate Notch activation, providing the catalytic subunit for the γ secretase proteolytic enzyme complex. For all known Notch signaling events, sel-12 can mediate Notch activation, so the conservation of hop-1 remains a mystery. Here, we uncover a novel "late-onset" germline Notch phenotype in which HOP-1-deficient worms fail to maintain proliferating germline stem cells during adulthood. Either SEL-12 or HOP-1 presenilin can impart sufficient Notch signaling for the establishment and expansion of the germline, but maintenance of an adult stem cell pool relies exclusively on HOP-1-mediated Notch signaling. We also show that HOP-1 is necessary for maximum fecundity and reproductive span. The low-fecundity phenotype of hop-1 mutants can be phenocopied by switching off glp-1/Notch function during the last stage of larval development. We propose that at the end of larval development, dual presenilin usage switches exclusively to HOP-1, perhaps offering opportunities for differential regulation of the germline during adulthood. Additional defects in oocyte size and production rate in hop-1 and glp-1 mutants indicate that the process of oogenesis is compromised when germline Notch signaling is switched off. We calculate that in wild-type adults, as much as 86% of cells derived from the stem cell pool function to support oogenesis. This work suggests that an important role for Notch signaling in the adult germline is to furnish a large and continuous supply of nurse cells to support the efficiency of oogenesis.
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38
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Flamand MN, Gan HH, Mayya VK, Gunsalus KC, Duchaine TF. A non-canonical site reveals the cooperative mechanisms of microRNA-mediated silencing. Nucleic Acids Res 2017; 45:7212-7225. [PMID: 28482037 PMCID: PMC5499589 DOI: 10.1093/nar/gkx340] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 04/18/2017] [Indexed: 01/08/2023] Open
Abstract
Although strong evidence supports the importance of their cooperative interactions, microRNA (miRNA)-binding sites are still largely investigated as functionally independent regulatory units. Here, a survey of alternative 3΄UTR isoforms implicates a non-canonical seedless site in cooperative miRNA-mediated silencing. While required for target mRNA deadenylation and silencing, this site is not sufficient on its own to physically recruit miRISC. Instead, it relies on facilitating interactions with a nearby canonical seed-pairing site to recruit the Argonaute complexes. We further show that cooperation between miRNA target sites is necessary for silencing in vivo in the C. elegans embryo, and for the recruitment of the Ccr4-Not effector complex. Using a structural model of cooperating miRISCs, we identified allosteric determinants of cooperative miRNA-mediated silencing that are required for both embryonic and larval miRNA functions. Our results delineate multiple cooperative mechanisms in miRNA-mediated silencing and further support the consideration of target site cooperation as a fundamental characteristic of miRNA function.
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Affiliation(s)
- Mathieu N Flamand
- Department of Biochemistry & Goodman Cancer Research Centre, McGill University, Montreal, Quebec H3G 1Y6 Canada
| | - Hin Hark Gan
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA
| | - Vinay K Mayya
- Department of Biochemistry & Goodman Cancer Research Centre, McGill University, Montreal, Quebec H3G 1Y6 Canada
| | - Kristin C Gunsalus
- Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA.,Division of Biology, New York University Abu Dhabi, Abu Dhabi, UAE
| | - Thomas F Duchaine
- Department of Biochemistry & Goodman Cancer Research Centre, McGill University, Montreal, Quebec H3G 1Y6 Canada
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39
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Cottee PA, Cole T, Schultz J, Hoang HD, Vibbert J, Han SM, Miller MA. The C. elegans VAPB homolog VPR-1 is a permissive signal for gonad development. Development 2017. [PMID: 28634273 PMCID: PMC5482997 DOI: 10.1242/dev.152207] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
VAMP/synaptobrevin-associated proteins (VAPs) contain an N-terminal major sperm protein domain (MSPd) that is associated with amyotrophic lateral sclerosis. VAPs have an intracellular housekeeping function, as well as an extracellular signaling function mediated by the secreted MSPd. Here we show that the C. elegans VAP homolog VPR-1 is essential for gonad development. vpr-1 null mutants are maternal effect sterile due to arrested gonadogenesis following embryo hatching. Somatic gonadal precursor cells and germ cells fail to proliferate fully and complete their respective differentiation programs. Maternal or zygotic vpr-1 expression is sufficient to induce gonadogenesis and fertility. Genetic mosaic and cell type-specific expression studies indicate that vpr-1 activity is important in the nervous system, germ line and intestine. VPR-1 acts in parallel to Notch signaling, a key regulator of germline stem cell proliferation and differentiation. Neuronal vpr-1 expression is sufficient for gonadogenesis induction during a limited time period shortly after hatching. These results support the model that the secreted VPR-1 MSPd acts at least in part on gonadal sheath cell precursors in L1 to early L2 stage hermaphrodites to permit gonadogenesis. Highlighted Article:vpr-1 null mutants are sterile upon hatching, a defect rescued by the expression of MSPd from almost any tissue except for the somatic gonad itself. See also the companion paper by Schultz et al.
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Affiliation(s)
- Pauline A Cottee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Tim Cole
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jessica Schultz
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Hieu D Hoang
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jack Vibbert
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Sung Min Han
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Michael A Miller
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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40
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Stress-Induced Sleep After Exposure to Ultraviolet Light Is Promoted by p53 in Caenorhabditis elegans. Genetics 2017; 207:571-582. [PMID: 28754659 DOI: 10.1534/genetics.117.300070] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 07/24/2017] [Indexed: 12/31/2022] Open
Abstract
Stress-induced sleep (SIS) in Caenorhabditis elegans is important for restoration of cellular homeostasis and is a useful model to study the function and regulation of sleep. SIS is triggered when epidermal growth factor (EGF) activates the ALA neuron, which then releases neuropeptides to promote sleep. To further understand this behavior, we established a new model of SIS using irradiation by ultraviolet C (UVC) light. While UVC irradiation requires ALA signaling and leads to a sleep state similar to that induced by heat and other stressors, it does not induce the proteostatic stress seen with heat exposure. Based on the known genotoxic effects of UVC irradiation, we tested two genes, atl-1 and cep-1, which encode proteins that act in the DNA damage response pathway. Loss-of-function mutants of atl-1 had no defect in UVC-induced SIS but a partial loss-of-function mutant of cep-1, gk138, had decreased movement quiescence following UVC irradiation. Germline ablation experiments and tissue-specific RNA interference experiments showed that cep-1 is required somatically in neurons for its effect on SIS. The cep-1(gk138) mutant suppressed body movement quiescence controlled by EGF, indicating that CEP-1 acts downstream or in parallel to ALA activation to promote quiescence in response to ultraviolet light.
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41
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Robertson SM, Medina J, Oldenbroek M, Lin R. Reciprocal signaling by Wnt and Notch specifies a muscle precursor in the C. elegans embryo. Development 2017; 144:419-429. [PMID: 28049659 DOI: 10.1242/dev.145391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 12/12/2016] [Indexed: 11/20/2022]
Abstract
The MS blastomere produces one-third of the body wall muscles (BWMs) in the C. elegans embryo. MS-derived BWMs require two distinct cell-cell interactions, the first inhibitory and the second, two cell cycles later, required to overcome this inhibition. The inductive interaction is not required if the inhibitory signal is absent. Although the Notch receptor GLP-1 was implicated in both interactions, the molecular nature of the two signals was unknown. We now show that zygotically expressed MOM-2 (Wnt) is responsible for both interactions. Both the inhibitory and the activating interactions require precise spatiotemporal expression of zygotic MOM-2, which is dependent upon two distinct Notch signals. In a Notch mutant defective only in the inductive interaction, MS-derived BWMs can be restored by preventing zygotic MOM-2 expression, which removes the inhibitory signal. Our results suggest that the inhibitory interaction ensures the differential lineage specification of MS and its sister blastomere, whereas the inductive interaction promotes the expression of muscle-specifying genes by modulating TCF and β-catenin levels. These results highlight the complexity of cell fate specification by cell-cell interactions in a rapidly dividing embryo.
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Affiliation(s)
- Scott M Robertson
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jessica Medina
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Marieke Oldenbroek
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rueyling Lin
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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42
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Feng WH, Xue KS, Tang L, Williams PL, Wang JS. Aflatoxin B₁-Induced Developmental and DNA Damage in Caenorhabditis elegans. Toxins (Basel) 2016; 9:toxins9010009. [PMID: 28035971 PMCID: PMC5308242 DOI: 10.3390/toxins9010009] [Citation(s) in RCA: 20] [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: 10/17/2016] [Revised: 12/06/2016] [Accepted: 12/22/2016] [Indexed: 12/31/2022] Open
Abstract
Aflatoxin B1 (AFB1) is a ubiquitous mycotoxin produced by toxicogenic Aspergillus species. AFB1 has been reported to cause serious adverse health effects, such as cancers and abnormal development and reproduction, in animals and humans. AFB1 is also a potent genotoxic mutagen that causes DNA damage in vitro and in vivo. However, the link between DNA damage and abnormal development and reproduction is unclear. To address this issue, we examined the DNA damage, germline apoptosis, growth, and reproductive toxicity following exposure to AFB1, using Caenorhabditis elegans as a study model. Results found that AFB1 induced DNA damage and germline apoptosis, and significantly inhibited growth and reproduction of the nematodes in a concentration-dependent manner. Exposure to AFB1 inhibited growth or reproduction more potently in the DNA repair-deficient xpa-1 nematodes than the wild-type N2 strain. According to the relative expression level of pathway-related genes measured by real-time PCR, the DNA damage response (DDR) pathway was found to be associated with AFB1-induced germline apoptosis, which further played an essential role in the dysfunction of growth and reproduction in C. elegans.
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Affiliation(s)
- Wei-Hong Feng
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA.
- Wuxi Center for Disease Control and Prevention, Wuxi 214023, Jiangsu, China.
| | - Kathy S Xue
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA.
| | - Lili Tang
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA.
| | - Phillip L Williams
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA.
| | - Jia-Sheng Wang
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA.
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43
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Lee C, Sorensen EB, Lynch TR, Kimble J. C. elegans GLP-1/Notch activates transcription in a probability gradient across the germline stem cell pool. eLife 2016; 5:e18370. [PMID: 27705743 PMCID: PMC5094854 DOI: 10.7554/elife.18370] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 10/04/2016] [Indexed: 12/26/2022] Open
Abstract
C. elegans Notch signaling maintains a pool of germline stem cells within their single-celled mesenchymal niche. Here we investigate the Notch transcriptional response in germline stem cells using single-molecule fluorescence in situ hybridization coupled with automated, high-throughput quantitation. This approach allows us to distinguish Notch-dependent nascent transcripts in the nucleus from mature mRNAs in the cytoplasm. We find that Notch-dependent active transcription sites occur in a probabilistic fashion and, unexpectedly, do so in a steep gradient across the stem cell pool. Yet these graded nuclear sites create a nearly uniform field of mRNAs that extends beyond the region of transcriptional activation. Therefore, active transcription sites provide a precise view of where the Notch-dependent transcriptional complex is productively engaged. Our findings offer a new window into the Notch transcriptional response and demonstrate the importance of assaying nascent transcripts at active transcription sites as a readout for canonical signaling.
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Affiliation(s)
- ChangHwan Lee
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, United States
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Erika B Sorensen
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, United States
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Tina R Lynch
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Judith Kimble
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, United States
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
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44
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Gabdank I, Ramakrishnan S, Villeneuve AM, Fire AZ. A streamlined tethered chromosome conformation capture protocol. BMC Genomics 2016; 17:274. [PMID: 27036078 PMCID: PMC4818521 DOI: 10.1186/s12864-016-2596-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 03/16/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Identification of locus-locus contacts at the chromatin level provides a valuable foundation for understanding of nuclear architecture and function and a valuable tool for inferring long-range linkage relationships. As one approach to this, chromatin conformation capture-based techniques allow creation of genome spatial organization maps. While such approaches have been available for some time, methodological advances will be of considerable use in minimizing both time and input material required for successful application. RESULTS Here we report a modified tethered conformation capture protocol that utilizes a series of rapid and efficient molecular manipulations. We applied the method to Caenorhabditis elegans, obtaining chromatin interaction maps that provide a sequence-anchored delineation of salient aspects of Caenorhabditis elegans chromosome structure, demonstrating a high level of consistency in overall chromosome organization between biological samples collected under different conditions. In addition to the application of the method to defining nuclear architecture, we found the resulting chromatin interaction maps to be of sufficient resolution and sensitivity to enable detection of large-scale structural variants such as inversions or translocations. CONCLUSION Our streamlined protocol provides an accelerated, robust, and broadly applicable means of generating chromatin spatial organization maps and detecting genome rearrangements without a need for cellular or chromatin fractionation.
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Affiliation(s)
- Idan Gabdank
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94304, USA
| | - Sreejith Ramakrishnan
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, California, 94304, USA
| | - Anne M Villeneuve
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, Stanford, California, 94304, USA
| | - Andrew Z Fire
- Departments of Pathology and Genetics, Stanford University School of Medicine, Stanford, California, 94304, USA.
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45
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Germline Stem Cell Differentiation Entails Regional Control of Cell Fate Regulator GLD-1 in Caenorhabditis elegans. Genetics 2016; 202:1085-103. [PMID: 26757772 DOI: 10.1534/genetics.115.185678] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 01/07/2016] [Indexed: 12/18/2022] Open
Abstract
Germline stem cell differentiation in Caenorhabditis elegans is controlled by glp-1 Notch signaling. Cell fate regulator GLD-1 is sufficient to induce meiotic entry and expressed at a high level during meiotic prophase, inhibiting mitotic gene activity. glp-1 signaling and other regulators control GLD-1 levels post-transcriptionally (low in stem cells, high in meiotic prophase), but many aspects of GLD-1 regulation are uncharacterized, including the link between glp-1-mediated transcriptional control and post-transcriptional GLD-1 regulation. We established a sensitive assay to quantify GLD-1 levels across an ∼35-cell diameter field, where distal germline stem cells differentiate proximally into meiotic prophase cells in the adult C. elegans hermaphrodite, and applied the approach to mutants in known or proposed GLD-1 regulators. In wild-type GLD-1 levels elevated ∼20-fold in a sigmoidal pattern. We found that two direct transcriptional targets of glp-1 signaling, lst-1 and sygl-1, were individually required for repression of GLD-1. We determined that lst-1 and sygl-1 act in the same genetic pathway as known GLD-1 translational repressor fbf-1, while lst-1 also acts in parallel to fbf-1, linking glp-1-mediated transcriptional control and post-transcriptional GLD-1 repression. Additionally, we estimated the position in wild-type gonads where germ cells irreversibly commit to meiotic development based on GLD-1 levels in worms where glp-1 activity was manipulated to cause an irreversible fate switch. Analysis of known repressors and activators, as well as modeling the sigmoidal accumulation pattern, indicated that regulation of GLD-1 levels is largely regional, which we integrated with the current view of germline stem cell differentiation.
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46
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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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47
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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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48
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Rastogi S, Borgo B, Pazdernik N, Fox P, Mardis ER, Kohara Y, Havranek J, Schedl T. Caenorhabditis elegans glp-4 Encodes a Valyl Aminoacyl tRNA Synthetase. G3 (BETHESDA, MD.) 2015; 5:2719-28. [PMID: 26464357 PMCID: PMC4683644 DOI: 10.1534/g3.115.021899] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/05/2015] [Indexed: 02/07/2023]
Abstract
Germline stem cell proliferation is necessary to populate the germline with sufficient numbers of cells for gametogenesis and for signaling the soma to control organismal properties such as aging. The Caenorhabditis elegans gene glp-4 was identified by the temperature-sensitive allele bn2 where mutants raised at the restrictive temperature produce adults that are essentially germ cell deficient, containing only a small number of stem cells arrested in the mitotic cycle but otherwise have a morphologically normal soma. We determined that glp-4 encodes a valyl aminoacyl transfer RNA synthetase (VARS-2) and that the probable null phenotype is early larval lethality. Phenotypic analysis indicates glp-4(bn2ts) is partial loss of function in the soma. Structural modeling suggests that bn2 Gly296Asp results in partial loss of function by a novel mechanism: aspartate 296 in the editing pocket induces inappropriate deacylation of correctly charged Val-tRNA(val). Intragenic suppressor mutations are predicted to displace aspartate 296 so that it is less able to catalyze inappropriate deacylation. Thus glp-4(bn2ts) likely causes reduced protein translation due to decreased levels of Val-tRNA(val). The germline, as a reproductive preservation mechanism during unfavorable conditions, signals the soma for organismal aging, stress and pathogen resistance. glp-4(bn2ts) mutants are widely used to generate germline deficient mutants for organismal studies, under the assumption that the soma is unaffected. As reduced translation has also been demonstrated to alter organismal properties, it is unclear whether changes in aging, stress resistance, etc. observed in glp-4(bn2ts) mutants are the result of germline deficiency or reduced translation.
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Affiliation(s)
- Suchita Rastogi
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri 63110
| | - Ben Borgo
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri 63110
| | - Nanette Pazdernik
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri 63110
| | - Paul Fox
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri 63110
| | - Elaine R Mardis
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri 63110
| | - Yuji Kohara
- National Institute of Genetics, Mishima, 411-8540 Japan
| | - Jim Havranek
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri 63110
| | - Tim Schedl
- Department of Genetics, Washington University School of Medicine, St Louis, Missouri 63110
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49
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Fox PM, Schedl T. Analysis of Germline Stem Cell Differentiation Following Loss of GLP-1 Notch Activity in Caenorhabditis elegans. Genetics 2015; 201:167-84. [PMID: 26158953 PMCID: PMC4566261 DOI: 10.1534/genetics.115.178061] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 07/01/2015] [Indexed: 11/18/2022] Open
Abstract
Stem cells generate the differentiated progeny cells of adult tissues. Stem cells in the Caenorhabditis elegans hermaphrodite germline are maintained within a proliferative zone of ∼230 cells, ∼20 cell diameters in length, through GLP-1 Notch signaling. The distal tip cell caps the germline and supplies GLP-1-activating ligand, and the distal-most germ cells that occupy this niche are likely self-renewing stem cells with active GLP-1 signaling. As germ cells are displaced from the niche, GLP-1 activity likely decreases, yet mitotically cycling germ cells are found throughout the proliferative zone prior to overt meiotic differentiation. Following loss of GLP-1 activity, it remains unclear whether stem cells undergo transit-amplifying (TA) divisions or more directly enter meiosis. To distinguish between these possibilities we employed a temperature-sensitive (ts) glp-1 mutant to manipulate GLP-1 activity. We characterized proliferative zone dynamics in glp-1(ts) mutants at permissive temperature and then analyzed the kinetics of meiotic entry of proliferative zone cells after loss of GLP-1. We found that entry of proliferative zone cells into meiosis following loss of GLP-1 activity is largely synchronous and independent of their distal-proximal position. Furthermore, the majority of cells complete only a single mitotic division before entering meiosis, independent of their distal-proximal position. We conclude that germ cells do not undergo TA divisions following loss of GLP-1 activity. We present a model for the dynamics of the proliferative zone that utilizes cell cycle rate and proliferative zone size and output and incorporates the more direct meiotic differentiation of germ cells following loss of GLP-1 activity.
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Affiliation(s)
- Paul M Fox
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Tim Schedl
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110
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50
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Promotion of bone morphogenetic protein signaling by tetraspanins and glycosphingolipids. PLoS Genet 2015; 11:e1005221. [PMID: 25978409 PMCID: PMC4433240 DOI: 10.1371/journal.pgen.1005221] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 04/14/2015] [Indexed: 02/08/2023] Open
Abstract
Bone morphogenetic proteins (BMPs) belong to the transforming growth factor β (TGFβ) superfamily of secreted molecules. BMPs play essential roles in multiple developmental and homeostatic processes in metazoans. Malfunction of the BMP pathway can cause a variety of diseases in humans, including cancer, skeletal disorders and cardiovascular diseases. Identification of factors that ensure proper spatiotemporal control of BMP signaling is critical for understanding how this pathway is regulated. We have used a unique and sensitive genetic screen to identify the plasma membrane-localized tetraspanin TSP-21 as a key new factor in the C. elegans BMP-like “Sma/Mab” signaling pathway that controls body size and postembryonic M lineage development. We showed that TSP-21 acts in the signal-receiving cells and genetically functions at the ligand-receptor level. We further showed that TSP-21 can associate with itself and with two additional tetraspanins, TSP-12 and TSP-14, which also promote Sma/Mab signaling. TSP-12 and TSP-14 can also associate with SMA-6, the type I receptor of the Sma/Mab pathway. Finally, we found that glycosphingolipids, major components of the tetraspanin-enriched microdomains, are required for Sma/Mab signaling. Our findings suggest that the tetraspanin-enriched membrane microdomains are important for proper BMP signaling. As tetraspanins have emerged as diagnostic and prognostic markers for tumor progression, and TSP-21, TSP-12 and TSP-14 are all conserved in humans, we speculate that abnormal BMP signaling due to altered expression or function of certain tetraspanins may be a contributing factor to cancer development. The bone morphogenetic protein (BMP) signaling pathway is required for multiple developmental processes during metazoan development. Various diseases, including cancer, can result from mis-regulation of the BMP pathway. Thus, it is critical to identify factors that ensure proper regulation of BMP signaling. Using the nematode C. elegans, we have devised a highly specific and sensitive genetic screen to identify new modulators in the BMP pathway. Through this screen, we identified three conserved tetraspanin molecules as novel factors that function to promote BMP signaling in a living organism. We further showed that these three tetraspanins likely form a complex and function together with glycosphingolipids to promote BMP signaling. Recent studies have implicated several tetraspanins in cancer initiation, progression and metastasis in mammals. Our findings suggest that the involvement of tetraspanins in cancer may partially be due to their function in modulating the activity of BMP signaling.
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