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Brown HE, Varderesian HV, Keane SA, Ryder SP. The mex-3 3' untranslated region is essential for reproduction during temperature stress. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.01.587367. [PMID: 38798418 PMCID: PMC11123400 DOI: 10.1101/2024.04.01.587367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Organisms must sense temperature and modify their physiology to ensure survival during environmental stress. Elevated temperature leads to reduced fertility in most sexually reproducing organisms. Maternally supplied mRNAs are required for embryogenesis. They encode proteins that govern early events in embryonic patterning. RNA-binding proteins (RBPs) are major effectors of maternal mRNA regulation. MEX-3 is a conserved RBP essential for anterior patterning of Caenorhabditis elegans embryos. We previously demonstrated that the mex-3 3' untranslated region (3'UTR) represses MEX-3 abundance in the germline yet is dispensable for fertility. Here, we show that the 3'UTR becomes essential during thermal stress. Deletion of the 3'UTR causes a highly penetrant temperature sensitive embryonic lethality phenotype distinct from a mex-3 null. Loss of the 3'UTR decreases MEX-3 abundance specifically in maturing oocytes and early embryos experiencing temperature stress, suggesting a mechanism that regulates MEX-3 abundance at the oocyte-to-embryo transition is sensitive to temperature. We propose that a primary role of the mex-3 3'UTR is to buffer MEX-3 expression to ensure viability during fluctuating temperature. We hypothesize that a major role of maternally supplied mRNAs is to ensure robust expression of key cell fate determinants in uncertain conditions.
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2
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Albarqi MMY, Ryder SP. The role of RNA-binding proteins in orchestrating germline development in Caenorhabditis elegans. Front Cell Dev Biol 2023; 10:1094295. [PMID: 36684428 PMCID: PMC9846511 DOI: 10.3389/fcell.2022.1094295] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 12/19/2022] [Indexed: 01/06/2023] Open
Abstract
RNA passed from parents to progeny controls several aspects of early development. The germline of the free-living nematode Caenorhabditis elegans contains many families of evolutionarily conserved RNA-binding proteins (RBPs) that target the untranslated regions of mRNA transcripts to regulate their translation and stability. In this review, we summarize what is known about the binding specificity of C. elegans germline RNA-binding proteins and the mechanisms of mRNA regulation that contribute to their function. We examine the emerging role of miRNAs in translational regulation of germline and embryo development. We also provide an overview of current technology that can be used to address the gaps in our understanding of RBP regulation of mRNAs. Finally, we present a hypothetical model wherein multiple 3'UTR-mediated regulatory processes contribute to pattern formation in the germline to ensure the proper and timely localization of germline proteins and thus a functional reproductive system.
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3
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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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4
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Tocchini C, Rohner M, Guerard L, Ray P, Von Stetina SE, Mango SE. Translation-dependent mRNA localization to Caenorhabditis elegans adherens junctions. Development 2021; 148:273751. [PMID: 34846063 PMCID: PMC8722394 DOI: 10.1242/dev.200027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 11/08/2021] [Indexed: 11/27/2022]
Abstract
mRNA localization is an evolutionarily widespread phenomenon that can facilitate subcellular protein targeting. Extensive work has focused on mRNA targeting through ‘zip-codes’ within untranslated regions (UTRs), whereas much less is known about translation-dependent cues. Here, we examine mRNA localization in Caenorhabditis elegans embryonic epithelia. From an smFISH-based survey, we identified mRNAs associated with the cell membrane or cortex, and with apical junctions in a stage- and cell type-specific manner. Mutational analyses for one of these transcripts, dlg-1/discs large, revealed that it relied on a translation-dependent process and did not require its 5′ or 3′ UTRs. We suggest a model in which dlg-1 transcripts are co-translationally localized with the nascent protein: first the translating complex goes to the cell membrane using sequences located at the C-terminal/3′ end, and then apically using N-terminal/5′ sequences. These studies identify a translation-based process for mRNA localization within developing epithelia and determine the necessary cis-acting sequences for dlg-1 mRNA targeting. Summary: An smFISH-based survey identifies a subset of mRNAs encoding junctional components that localize at or in proximity to the adherens junction through a translation-dependent mechanism.
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Affiliation(s)
| | - Michèle Rohner
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | | | - Poulomi Ray
- Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | | | - Susan E Mango
- Biozentrum, University of Basel, 4056 Basel, Switzerland
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5
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Grzybowska EA, Wakula M. Protein Binding to Cis-Motifs in mRNAs Coding Sequence Is Common and Regulates Transcript Stability and the Rate of Translation. Cells 2021; 10:2910. [PMID: 34831133 PMCID: PMC8616275 DOI: 10.3390/cells10112910] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/22/2021] [Accepted: 10/24/2021] [Indexed: 12/19/2022] Open
Abstract
Protein binding to the non-coding regions of mRNAs is relatively well characterized and its functionality has been described in many examples. New results obtained by high-throughput methods indicate that binding to the coding sequence (CDS) by RNA-binding proteins is also quite common, but the functions thereof are more obscure. As described in this review, CDS binding has a role in the regulation of mRNA stability, but it has also a more intriguing role in the regulation of translational efficiency. Global approaches, which suggest the significance of CDS binding along with specific examples of CDS-binding RBPs and their modes of action, are outlined here, pointing to the existence of a relatively less-known regulatory network controlling mRNA stability and translation on yet another level.
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Affiliation(s)
- Ewa A. Grzybowska
- Molecular and Translational Oncology, Maria Sklodowska-Curie National Research Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland;
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6
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Albarqi MMY, Ryder SP. The endogenous mex-3 3´UTR is required for germline repression and contributes to optimal fecundity in C. elegans. PLoS Genet 2021; 17:e1009775. [PMID: 34424904 PMCID: PMC8412283 DOI: 10.1371/journal.pgen.1009775] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 09/02/2021] [Accepted: 08/11/2021] [Indexed: 11/18/2022] Open
Abstract
RNA regulation is essential to successful reproduction. Messenger RNAs delivered from parent to progeny govern early embryonic development. RNA-binding proteins (RBPs) are the key effectors of this process, regulating the translation and stability of parental transcripts to control cell fate specification events prior to zygotic gene activation. The KH-domain RBP MEX-3 is conserved from nematode to human. It was first discovered in Caenorhabditis elegans, where it is essential for anterior cell fate and embryo viability. Here, we show that loss of the endogenous mex-3 3´UTR disrupts its germline expression pattern. An allelic series of 3´UTR deletion variants identify repressing regions of the UTR and demonstrate that repression is not precisely coupled to reproductive success. We also show that several RBPs regulate mex-3 mRNA through its 3´UTR to define its unique germline spatiotemporal expression pattern. Additionally, we find that both poly(A) tail length control and the translation initiation factor IFE-3 contribute to its expression pattern. Together, our results establish the importance of the mex-3 3´UTR to reproductive health and its expression in the germline. Our results suggest that additional mechanisms control MEX-3 function when 3´UTR regulation is compromised. In sexually reproducing organisms, germ cells undergo meiosis and differentiate to form oocytes or sperm. Coordination of this process requires a gene regulatory program that acts while the genome is undergoing chromatin condensation. As such, RNA regulatory pathways are an important contributor. The germline of the nematode Caenorhabditis elegans is a suitable model system to study germ cell differentiation. Several RNA-binding proteins (RBPs) coordinate each transition in the germline such as the transition from mitosis to meiosis. MEX-3 is a conserved RNA-binding protein found in most animals including humans. In C. elegans, MEX-3 displays a highly restricted pattern of expression. Here, we define the importance of the 3´UTR in regulating MEX-3 expression pattern in vivo and characterize the RNA-binding proteins involved in this regulation. Our results show that deleting various mex-3 3´UTR regions alter the pattern of expression in the germline in various ways. These mutations also reduced—but did not eliminate—reproductive capacity. Finally, we demonstrate that multiple post-transcriptional mechanisms control MEX-3 levels in different domains of the germline. Our data suggest that coordination of MEX-3 activity requires multiple layers of regulation to ensure reproductive robustness.
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Affiliation(s)
- Mennatallah M. Y. Albarqi
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Sean P. Ryder
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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7
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Samaddar M, Goudeau J, Sanchez M, Hall DH, Bohnert KA, Ingaramo M, Kenyon C. A genetic screen identifies new steps in oocyte maturation that enhance proteostasis in the immortal germ lineage. eLife 2021; 10:e62653. [PMID: 33848238 PMCID: PMC8043744 DOI: 10.7554/elife.62653] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 03/24/2021] [Indexed: 12/24/2022] Open
Abstract
Somatic cells age and die, but the germ-cell lineage is immortal. In Caenorhabditis elegans, germline immortality involves proteostasis renewal at the beginning of each new generation, when oocyte maturation signals from sperm trigger the clearance of carbonylated proteins and protein aggregates. Here, we explore the cell biology of this proteostasis renewal in the context of a whole-genome RNAi screen. Oocyte maturation signals are known to trigger protein-aggregate removal via lysosome acidification. Our findings suggest that lysosomes are acidified as a consequence of changes in endoplasmic reticulum activity that permit assembly of the lysosomal V-ATPase, which in turn allows lysosomes to clear the aggregates via microautophagy. We define two functions for mitochondria, both of which appear to be independent of ATP generation. Many genes from the screen also regulate lysosome acidification and age-dependent protein aggregation in the soma, suggesting a fundamental mechanistic link between proteostasis renewal in the germline and somatic longevity.
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Affiliation(s)
| | - Jérôme Goudeau
- Calico Life Sciences LLCSouth San FranciscoUnited States
| | - Melissa Sanchez
- Department of Molecular and Cellular Biology, University of California, BerkeleyBerkeleyUnited States
| | - David H Hall
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of MedicineNew YorkUnited States
| | - K Adam Bohnert
- Calico Life Sciences LLCSouth San FranciscoUnited States
| | - Maria Ingaramo
- Calico Life Sciences LLCSouth San FranciscoUnited States
| | - Cynthia Kenyon
- Calico Life Sciences LLCSouth San FranciscoUnited States
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8
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Hafner M, Katsantoni M, Köster T, Marks J, Mukherjee J, Staiger D, Ule J, Zavolan M. CLIP and complementary methods. ACTA ACUST UNITED AC 2021. [DOI: 10.1038/s43586-021-00018-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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9
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Müller-McNicoll M, Rossbach O, Hui J, Medenbach J. Auto-regulatory feedback by RNA-binding proteins. J Mol Cell Biol 2020; 11:930-939. [PMID: 31152582 PMCID: PMC6884704 DOI: 10.1093/jmcb/mjz043] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/25/2019] [Accepted: 04/23/2019] [Indexed: 12/19/2022] Open
Abstract
RNA-binding proteins (RBPs) are key regulators in post-transcriptional control of gene expression. Mutations that alter their activity or abundance have been implicated in numerous diseases such as neurodegenerative disorders and various types of cancer. This highlights the importance of RBP proteostasis and the necessity to tightly control the expression levels and activities of RBPs. In many cases, RBPs engage in an auto-regulatory feedback by directly binding to and influencing the fate of their own mRNAs, exerting control over their own expression. For this feedback control, RBPs employ a variety of mechanisms operating at all levels of post-transcriptional regulation of gene expression. Here we review RBP-mediated autogenous feedback regulation that either serves to maintain protein abundance within a physiological range (by negative feedback) or generates binary, genetic on/off switches important for e.g. cell fate decisions (by positive feedback).
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Affiliation(s)
- Michaela Müller-McNicoll
- Institute of Cell Biology and Neuroscience, Goethe University Frankfurt, Max-von-Laue-Strasse 13, D-60438 Frankfurt am Main, Germany
| | - Oliver Rossbach
- Institute of Biochemistry, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany
| | - Jingyi Hui
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jan Medenbach
- Institute of Biochemistry I, University of Regensburg, Universitaetsstrasse 31, D-93053 Regensburg, Germany
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10
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Nousch M, Yeroslaviz A, Eckmann CR. Stage-specific combinations of opposing poly(A) modifying enzymes guide gene expression during early oogenesis. Nucleic Acids Res 2020; 47:10881-10893. [PMID: 31511882 PMCID: PMC6845980 DOI: 10.1093/nar/gkz787] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 09/01/2019] [Accepted: 09/03/2019] [Indexed: 11/14/2022] Open
Abstract
RNA-modifying enzymes targeting mRNA poly(A) tails are universal regulators of post-transcriptional gene expression programs. Current data suggest that an RNA-binding protein (RBP) directed tug-of-war between tail shortening and re-elongating enzymes operates in the cytoplasm to repress or activate specific mRNA targets. While this concept is widely accepted, it was primarily described in the final meiotic stages of frog oogenesis and relies molecularly on a single class of RBPs, i.e. CPEBs, the deadenylase PARN and cytoplasmic poly(A) polymerase GLD-2. Using the spatial and temporal resolution of female gametogenesis in the nematode C. elegans, we determined the distinct roles of known deadenylases throughout germ cell development and discovered that the Ccr4-Not complex is the main antagonist to GLD-2-mediated mRNA regulation. We find that the Ccr4-Not/GLD-2 balance is critical for essentially all steps of oocyte production and reiteratively employed by various classes of RBPs. Interestingly, its two deadenylase subunits appear to affect mRNAs stage specifically: while a Caf1/GLD-2 antagonism regulates mRNA abundance during all stages of oocyte production, a Ccr4/GLD-2 antagonism regulates oogenesis in an mRNA abundance independent manner. Our combined data suggests that the Ccr4-Not complex represents the evolutionarily conserved molecular opponent to GLD-2 providing an antagonistic framework of gene-specific poly(A)-tail regulation.
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Affiliation(s)
- Marco Nousch
- Developmental Genetics, Institute of Biology, Martin Luther University Halle-Wittenberg (MLU), Weinbergweg 10, Halle (Saale) 06120, Germany
| | - Assa Yeroslaviz
- Max Planck Institute of Biochemistry (MPIB), Am Klopferspitz 18, Martinsried 82152, Germany
| | - Christian R Eckmann
- Developmental Genetics, Institute of Biology, Martin Luther University Halle-Wittenberg (MLU), Weinbergweg 10, Halle (Saale) 06120, Germany
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11
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Sharma M, Sharma S, Alawada A. Understanding the binding specificities of mRNA targets by the mammalian Quaking protein. Nucleic Acids Res 2020; 47:10564-10579. [PMID: 31602485 PMCID: PMC6847458 DOI: 10.1093/nar/gkz877] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 09/18/2019] [Accepted: 10/08/2019] [Indexed: 01/01/2023] Open
Abstract
Mammalian Quaking (QKI) protein, a member of STAR family of proteins is a mRNA-binding protein, which post-transcriptionally modulates the target RNA. QKI protein possesses a maxi-KH domain composed of single heterogeneous nuclear ribonucleoprotein K homology (KH) domain and C-terminal QUA2 domain, that binds a sequence-specific QKI RNA recognition element (QRE), CUAAC. To understand the binding specificities for different mRNA sequences of the KH-QUA2 domain of QKI protein, we introduced point mutations at different positions in the QRE resulting in twelve different mRNA sequences with single nucleotide change. We carried out long unbiased molecular dynamics simulations using two different sets of recently updated forcefield parameters: AMBERff14SB+RNAχOL3 and CHARMM36 (with CMAP correction). We analyzed the changes in intermolecular dynamics as a result of mutation. Our results show that AMBER forcefields performed better to model the interactions between mRNA and protein. We also calculated the binding affinities of different mRNA sequences and found that the relative order correlates to the reported experimental studies. Our study shows that the favorable binding with the formation of stable complex will occur when there is an increase of the total intermolecular contacts between mRNA and protein, but without the loss of native contacts within the KH-QUA domain.
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Affiliation(s)
- Monika Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Sector 81, Knowledge City, SAS Nagar, Punjab, India
| | - Shakshi Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Sector 81, Knowledge City, SAS Nagar, Punjab, India
| | - Apoorv Alawada
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Sector 81, Knowledge City, SAS Nagar, Punjab, India
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12
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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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13
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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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14
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Theil K, Herzog M, Rajewsky N. Post-transcriptional Regulation by 3' UTRs Can Be Masked by Regulatory Elements in 5' UTRs. Cell Rep 2019; 22:3217-3226. [PMID: 29562178 DOI: 10.1016/j.celrep.2018.02.094] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 11/20/2017] [Accepted: 02/23/2018] [Indexed: 11/29/2022] Open
Abstract
In mRNA sequences, 3' UTRs are thought to contain most elements that specifically regulate localization, turnover, and translation. Although high-throughput experiments indicate that many RNA-binding proteins (RBPs) also bind 5' UTRs, much less is known about specific post-transcriptional control exerted by 5' UTRs. GLD-1 is a conserved RBP and a translational repressor with essential roles in Caenorhabditis elegans germ cell development. Previously, we showed that GLD-1 binds highly conserved sites in both 3' and 5' UTRs. Here, by targeted single-copy insertion of transgenes, we systematically tested in vivo functionality of 5' and 3' UTR binding sites individually and in combination. Our data show that sites in 5' UTRs mediate specific and strong translational repression, independent of exact position. Intriguingly, we found that the functionality of 3' UTR sites can be masked by 5' UTR sites and vice versa. We conclude that it is important to study both UTRs simultaneously.
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Affiliation(s)
- Kathrin Theil
- Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
| | - Margareta Herzog
- Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
| | - Nikolaus Rajewsky
- Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany.
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15
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Theil K, Imami K, Rajewsky N. Identification of proteins and miRNAs that specifically bind an mRNA in vivo. Nat Commun 2019; 10:4205. [PMID: 31527589 PMCID: PMC6746756 DOI: 10.1038/s41467-019-12050-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 08/19/2019] [Indexed: 12/26/2022] Open
Abstract
Understanding regulation of an mRNA requires knowledge of its regulators. However, methods for reliable de-novo identification of proteins binding to a particular RNA are scarce and were thus far only successfully applied to abundant noncoding RNAs in cell culture. Here, we present vIPR, an RNA-protein crosslink, RNA pulldown, and shotgun proteomics approach to identify proteins bound to selected mRNAs in C. elegans. Applying vIPR to the germline-specific transcript gld-1 led to enrichment of known and novel interactors. By comparing enrichment upon gld-1 and lin-41 pulldown, we demonstrate that vIPR recovers both common and specific RNA-binding proteins, and we validate DAZ-1 as a specific gld-1 regulator. Finally, combining vIPR with small RNA sequencing, we recover known and biologically important transcript-specific miRNA interactions, and we identify miR-84 as a specific interactor of the gld-1 transcript. We envision that vIPR will provide a platform for investigating RNA in vivo regulation in diverse biological systems.
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Affiliation(s)
- Kathrin Theil
- Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany.
| | - Koshi Imami
- Proteome Dynamics, Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany
- Laboratory of Molecular and Cellular BioAnalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
| | - Nikolaus Rajewsky
- Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125, Berlin, Germany.
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16
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MINA-1 and WAGO-4 are part of regulatory network coordinating germ cell death and RNAi in C. elegans. Cell Death Differ 2019; 26:2157-2178. [PMID: 30728462 DOI: 10.1038/s41418-019-0291-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/23/2018] [Accepted: 11/26/2018] [Indexed: 01/22/2023] Open
Abstract
Post-transcriptional control of mRNAs by RNA-binding proteins (RBPs) has a prominent role in the regulation of gene expression. RBPs interact with mRNAs to control their biogenesis, splicing, transport, localization, translation, and stability. Defects in such regulation can lead to a wide range of human diseases from neurological disorders to cancer. Many RBPs are conserved between Caenorhabditis elegans and humans, and several are known to regulate apoptosis in the adult C. elegans germ line. How these RBPs control apoptosis is, however, largely unknown. Here, we identify mina-1(C41G7.3) in a RNA interference-based screen as a novel regulator of apoptosis, which is exclusively expressed in the adult germ line. The absence of MINA-1 causes a dramatic increase in germ cell apoptosis, a reduction in brood size, and an impaired P granules organization and structure. In vivo crosslinking immunoprecipitation experiments revealed that MINA-1 binds a set of mRNAs coding for RBPs associated with germ cell development. Additionally, a system-wide analysis of a mina-1 deletion mutant compared with wild type, including quantitative proteome and transcriptome data, hints to a post-transcriptional regulatory RBP network driven by MINA-1 during germ cell development in C. elegans. In particular, we found that the germline-specific Argonaute WAGO-4 protein levels are increased in mina-1 mutant background. Phenotypic analysis of double mutant mina-1;wago-4 revealed that contemporary loss of MINA-1 and WAGO-4 strongly rescues the phenotypes observed in mina-1 mutant background. To strengthen this functional interaction, we found that upregulation of WAGO-4 in mina-1 mutant animals causes hypersensitivity to exogenous RNAi. Our comprehensive experimental approach allowed us to describe a phenocritical interaction between two RBPs controlling germ cell apoptosis and exogenous RNAi. These findings broaden our understanding of how RBPs can orchestrate different cellular events such as differentiation and death in C. elegans.
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17
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Multi-modal regulation of C. elegans hermaphrodite spermatogenesis by the GLD-1-FOG-2 complex. Dev Biol 2018; 446:193-205. [PMID: 30599151 DOI: 10.1016/j.ydbio.2018.11.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 11/07/2018] [Accepted: 11/12/2018] [Indexed: 01/26/2023]
Abstract
Proper germ cell sex determination in Caenorhabditis nematodes requires a network of RNA-binding proteins (RBPs) and their target mRNAs. In some species, changes in this network enabled limited XX spermatogenesis, and thus self-fertility. In C. elegans, one of these selfing species, the global sex-determining gene tra-2 is regulated in germ cells by a conserved RBP, GLD-1, via the 3' untranslated region (3'UTR) of its transcript. A C. elegans-specific GLD-1 cofactor, FOG-2, is also required for hermaphrodite sperm fate, but how it modifies GLD-1 function is unknown. Germline feminization in gld-1 and fog-2 null mutants has been interpreted as due to cell-autonomous elevation of TRA-2 translation. Consistent with the proposed role of FOG-2 in translational control, the abundance of nearly all GLD-1 target mRNAs (including tra-2) is unchanged in fog-2 mutants. Epitope tagging reveals abundant TRA-2 expression in somatic tissues, but an undetectably low level in wild-type germ cells. Loss of gld-1 function elevates germline TRA-2 expression to detectable levels, but loss of fog-2 function does not. A simple quantitative model of tra-2 activity constrained by these results can successfully sort genotypes into normal or feminized groups. Surprisingly, fog-2 and gld-1 activity enable the sperm fate even when GLD-1 cannot bind to the tra-2 3' UTR. This suggests the GLD-1-FOG-2 complex regulates uncharacterized sites within tra-2, or other mRNA targets. Finally, we quantify the RNA-binding capacities of dominant missense alleles of GLD-1 that act genetically as "hyper-repressors" of tra-2 activity. These variants bind RNA more weakly in vitro than does wild-type GLD-1. These results indicate that gld-1 and fog-2 regulate germline sex via multiple interactions, and that our understanding of the control and evolution of germ cell sex determination in the C. elegans hermaphrodite is far from complete.
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18
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Dynein Light Chain DLC-1 Facilitates the Function of the Germline Cell Fate Regulator GLD-1 in Caenorhabditis elegans. Genetics 2018; 211:665-681. [PMID: 30509955 DOI: 10.1534/genetics.118.301617] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Accepted: 11/21/2018] [Indexed: 11/18/2022] Open
Abstract
Developmental transitions of germ cells are often regulated at the level of post-transcriptional control of gene expression. In the Caenorhabditis elegans germline, stem and progenitor cells exit the proliferative phase and enter meiotic differentiation to form gametes essential for fertility. The RNA binding protein GLD-1 is a cell fate regulator that promotes meiosis and germ cell differentiation during development by binding to and repressing translation of target messenger RNAs. Here, we discovered that some GLD-1 functions are promoted by binding to DLC-1, a small protein that functions as an allosteric regulator of multisubunit protein complexes. We found that DLC-1 is required to regulate a subset of GLD-1 target messenger RNAs and that DLC-1 binding GLD-1 prevents ectopic germ cell proliferation and facilitates gametogenesis in vivo Additionally, our results reveal a new requirement for GLD-1 in the events of oogenesis leading to ovulation. DLC-1 contributes to GLD-1 function independent of its role as a light chain component of the dynein motor. Instead, we propose that DLC-1 promotes assembly of GLD-1 with other binding partners, which facilitates formation of regulatory ribonucleoprotein complexes and may direct GLD-1 target messenger RNA selectivity.
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19
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Day NJ, Ellenbecker M, Voronina E. Caenorhabditis elegans DLC-1 associates with ribonucleoprotein complexes to promote mRNA regulation. FEBS Lett 2018; 592:3683-3695. [PMID: 30264890 PMCID: PMC6263831 DOI: 10.1002/1873-3468.13259] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 09/07/2018] [Accepted: 09/14/2018] [Indexed: 12/21/2022]
Abstract
Ribonucleoprotein complexes, which contain mRNAs and their regulator proteins, carry out post-transcriptional control of gene expression. The function of many RNA-binding proteins depends on their association with cofactors. Here, we use a genomic approach to identify transcripts associated with DLC-1, a protein previously identified as a cofactor of two unrelated RNA-binding proteins that act in the Caenorhabditis elegans germline. Among the 2732 potential DLC-1 targets, most are germline mRNAs associated with oogenesis. Removal of DLC-1 affects expression of its targets expressed in the oocytes, meg-1 and meg-3. We propose that DLC-1 acts as a cofactor for multiple ribonucleoprotein complexes, including the ones regulating gene expression during oogenesis.
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Affiliation(s)
- Nicholas J Day
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Mary Ellenbecker
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Ekaterina Voronina
- Division of Biological Sciences, University of Montana, Missoula, MT, USA
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20
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Multiple Mechanisms Inactivate the LIN-41 RNA-Binding Protein To Ensure a Robust Oocyte-to-Embryo Transition in Caenorhabditis elegans. Genetics 2018; 210:1011-1037. [PMID: 30206186 PMCID: PMC6218228 DOI: 10.1534/genetics.118.301421] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 09/10/2018] [Indexed: 12/23/2022] Open
Abstract
In the nematode Caenorhabditis elegans, the conserved LIN-41 RNA-binding protein is a translational repressor that coordinately controls oocyte growth and meiotic maturation. LIN-41 exerts these effects, at least in part, by preventing the premature activation of the cyclin-dependent kinase CDK-1. Here we investigate the mechanism by which LIN-41 is rapidly eliminated upon the onset of meiotic maturation. Elimination of LIN-41 requires the activities of CDK-1 and multiple SCF (Skp1, Cul1, and F-box protein)-type E3 ubiquitin ligase subunits, including the conserved substrate adaptor protein SEL-10/Fbw7/Cdc4, suggesting that LIN-41 is a target of ubiquitin-mediated protein degradation. Within the LIN-41 protein, two nonoverlapping regions, Deg-A and Deg-B, are individually necessary for LIN-41 degradation; both contain several potential phosphodegron sequences, and at least one of these sequences is required for LIN-41 degradation. Finally, Deg-A and Deg-B are sufficient, in combination, to mediate SEL-10-dependent degradation when transplanted into a different oocyte protein. Although LIN-41 is a potent inhibitor of protein translation and M phase entry, the failure to eliminate LIN-41 from early embryos does not result in the continued translational repression of LIN-41 oocyte messenger RNA targets. Based on these observations, we propose a model for the elimination of LIN-41 by the SEL-10 E3 ubiquitin ligase and suggest that LIN-41 is inactivated before it is degraded. Furthermore, we provide evidence that another RNA-binding protein, the GLD-1 tumor suppressor, is regulated similarly. Redundant mechanisms to extinguish translational repression by RNA-binding proteins may both control and provide robustness to irreversible developmental transitions, including meiotic maturation and the oocyte-to-embryo transition.
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21
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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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22
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MAPK signaling couples SCF-mediated degradation of translational regulators to oocyte meiotic progression. Proc Natl Acad Sci U S A 2018; 115:E2772-E2781. [PMID: 29496961 DOI: 10.1073/pnas.1715439115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
RNA-binding proteins (RBPs) are important regulators of gene expression programs, especially during gametogenesis. How the abundance of particular RBPs is restricted to defined stages of meiosis remains largely elusive. Here, we report a molecular pathway that subjects two nonrelated but broadly evolutionarily conserved translational regulators (CPB-3/CPEB and GLD-1/STAR) to proteosomal degradation in Caenorhabditis elegans germ cells at the transition from pachytene to diplotene of meiotic prophase. Both RBPs are recognized by the same ubiquitin ligase complex, containing the molecular scaffold Cullin-1 and the tumor suppressor SEL-10/FBXW7 as its substrate recognition subunit. Destabilization of either RBP through this Skp, Cullin, F-box-containing complex (SCF) ubiquitin ligase appears to loosen its negative control over established target mRNAs, and presumably depends on a prior phosphorylation of CPB-3 and GLD-1 by MAPK (MPK-1), whose activity increases in mid- to late pachytene to promote meiotic progression and oocyte differentiation. Thus, we propose that the orchestrated degradation of RBPs via MAPK-signaling cascades during germ cell development may act to synchronize meiotic with sexual differentiation gene expression changes.
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23
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West SM, Mecenas D, Gutwein M, Aristizábal-Corrales D, Piano F, Gunsalus KC. Developmental dynamics of gene expression and alternative polyadenylation in the Caenorhabditis elegans germline. Genome Biol 2018; 19:8. [PMID: 29368663 PMCID: PMC5784609 DOI: 10.1186/s13059-017-1369-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 12/03/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The 3' untranslated regions (UTRs) of mRNAs play a major role in post-transcriptional regulation of gene expression. Selection of transcript cleavage and polyadenylation sites is a dynamic process that produces multiple transcript isoforms for the same gene within and across different cell types. Using LITE-Seq, a new quantitative method to capture transcript 3' ends expressed in vivo, we have characterized sex- and cell type-specific transcriptome-wide changes in gene expression and 3'UTR diversity in Caenorhabditis elegans germline cells undergoing proliferation and differentiation. RESULTS We show that nearly half of germline transcripts are alternatively polyadenylated, that differential regulation of endogenous 3'UTR variants is common, and that alternative isoforms direct distinct spatiotemporal protein expression patterns in vivo. Dynamic expression profiling also reveals temporal regulation of X-linked gene expression, selective stabilization of transcripts, and strong evidence for a novel developmental program that promotes nucleolar dissolution in oocytes. We show that the RNA-binding protein NCL-1/Brat is a posttranscriptional regulator of numerous ribosome-related transcripts that acts through specific U-rich binding motifs to down-regulate mRNAs encoding ribosomal protein subunits, rRNA processing factors, and tRNA synthetases. CONCLUSIONS These results highlight the pervasive nature and functional potential of patterned gene and isoform expression during early animal development.
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Affiliation(s)
- Sean M West
- Center for Genomics & Systems Biology, Department of Biology, New York University, New York, NY, 10012, USA
| | - Desirea Mecenas
- Center for Genomics & Systems Biology, Department of Biology, New York University, New York, NY, 10012, USA
| | - Michelle Gutwein
- Center for Genomics & Systems Biology, Department of Biology, New York University, New York, NY, 10012, USA
| | - David Aristizábal-Corrales
- Center for Genomics & Systems Biology, Department of Biology, New York University, New York, NY, 10012, USA
| | - Fabio Piano
- Center for Genomics & Systems Biology, Department of Biology, New York University, New York, NY, 10012, USA.
- Center for Genomics & Systems Biology, NYU Abu Dhabi, P.O. Box 129188, Saadiyat Island, Abu Dhabi, United Arab Emirates.
| | - Kristin C Gunsalus
- Center for Genomics & Systems Biology, Department of Biology, New York University, New York, NY, 10012, USA.
- Center for Genomics & Systems Biology, NYU Abu Dhabi, P.O. Box 129188, Saadiyat Island, Abu Dhabi, United Arab Emirates.
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24
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Bohnert KA, Kenyon C. A lysosomal switch triggers proteostasis renewal in the immortal C. elegans germ lineage. Nature 2017; 551:629-633. [PMID: 29168500 PMCID: PMC5936623 DOI: 10.1038/nature24620] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 10/05/2017] [Indexed: 12/14/2022]
Abstract
Although individuals age and die with time, an animal species can continue indefinitely, because of its immortal germ-cell lineage. How the germline avoids transmitting damage from one generation to the next remains a fundamental question in biology. Here we identify a lysosomal switch that enhances germline proteostasis before fertilization. We find that Caenorhabditis elegans oocytes whose maturation is arrested by the absence of sperm exhibit hallmarks of proteostasis collapse, including protein aggregation. Remarkably, sperm-secreted hormones re-establish oocyte proteostasis once fertilization becomes imminent. Key to this restoration is activation of the vacuolar H+-ATPase (V-ATPase), a proton pump that acidifies lysosomes. Sperm stimulate V-ATPase activity in oocytes by signalling the degradation of GLD-1, a translational repressor that blocks V-ATPase synthesis. Activated lysosomes, in turn, promote a metabolic shift that mobilizes protein aggregates for degradation, and reset proteostasis by enveloping and clearing the aggregates. Lysosome acidification also occurs during Xenopus oocyte maturation; thus, a lysosomal switch that enhances oocyte proteostasis in anticipation of fertilization may be conserved in other species.
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Affiliation(s)
- K Adam Bohnert
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California 94158, USA
- Calico Life Sciences, South San Francisco, California 94080, USA
| | - Cynthia Kenyon
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California 94158, USA
- Calico Life Sciences, South San Francisco, California 94080, USA
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25
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Subasic D, Stoeger T, Eisenring S, Matia-González AM, Imig J, Zheng X, Xiong L, Gisler P, Eberhard R, Holtackers R, Gerber AP, Pelkmans L, Hengartner MO. Post-transcriptional control of executioner caspases by RNA-binding proteins. Genes Dev 2017; 30:2213-2225. [PMID: 27798844 PMCID: PMC5088569 DOI: 10.1101/gad.285726.116] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 09/16/2016] [Indexed: 12/03/2022]
Abstract
In this study, Subasic et al. investigated the post-transcriptional control of caspases. The authors describe four conserved RNA-binding proteins (RBPs) that sequentially repress the CED-3 caspase in distinct regions of the C. elegans germline and identify seven RBPs that regulate human caspase-3 expression and/or activation, suggesting that translational inhibition of executioner caspases by RBPs might be a general strategy used widely across the animal kingdom to control apoptosis. Caspases are key components of apoptotic pathways. Regulation of caspases occurs at several levels, including transcription, proteolytic processing, inhibition of enzymatic function, and protein degradation. In contrast, little is known about the extent of post-transcriptional control of caspases. Here, we describe four conserved RNA-binding proteins (RBPs)—PUF-8, MEX-3, GLD-1, and CGH-1—that sequentially repress the CED-3 caspase in distinct regions of the Caenorhabditis elegans germline. We demonstrate that GLD-1 represses ced-3 mRNA translation via two binding sites in its 3′ untranslated region (UTR), thereby ensuring a dual control of unwanted cell death: at the level of p53/CEP-1 and at the executioner caspase level. Moreover, we identified seven RBPs that regulate human caspase-3 expression and/or activation, including human PUF-8, GLD-1, and CGH-1 homologs PUM1, QKI, and DDX6. Given the presence of unusually long executioner caspase 3′ UTRs in many metazoans, translational control of executioner caspases by RBPs might be a strategy used widely across the animal kingdom to control apoptosis.
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Affiliation(s)
- Deni Subasic
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland.,Molecular Life Sciences PhD Program, Swiss Federal Institute of Technology, University of Zurich, 8057 Zurich, Switzerland
| | - Thomas Stoeger
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland.,Systems Biology PhD Program, Swiss Federal Institute of Technology, University of Zurich, 8057 Zurich, Switzerland
| | - Seline Eisenring
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Ana M Matia-González
- Faculty of Health and Medical Sciences, Department of Microbial and Cellular Sciences, University of Surrey, Stag Hill Campus, GU2 7XH Guildford, United Kingdom
| | - Jochen Imig
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, 8093 Zurich, Switzerland
| | - Xue Zheng
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Lei Xiong
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Pascal Gisler
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Ralf Eberhard
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - René Holtackers
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - André P Gerber
- Faculty of Health and Medical Sciences, Department of Microbial and Cellular Sciences, University of Surrey, Stag Hill Campus, GU2 7XH Guildford, United Kingdom
| | - Lucas Pelkmans
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Michael O Hengartner
- Institute of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
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26
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LIN41 Post-transcriptionally Silences mRNAs by Two Distinct and Position-Dependent Mechanisms. Mol Cell 2017; 65:476-489.e4. [DOI: 10.1016/j.molcel.2016.12.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 11/11/2016] [Accepted: 12/13/2016] [Indexed: 12/14/2022]
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27
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Kaymak E, Farley BM, Hay SA, Li C, Ho S, Hartman DJ, Ryder SP. Efficient generation of transgenic reporter strains and analysis of expression patterns in Caenorhabditis elegans using library MosSCI. Dev Dyn 2016; 245:925-36. [PMID: 27294288 PMCID: PMC4981527 DOI: 10.1002/dvdy.24426] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 05/09/2016] [Accepted: 06/03/2016] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In C. elegans, germline development and early embryogenesis rely on posttranscriptional regulation of maternally transcribed mRNAs. In many cases, the 3' untranslated region (UTR) is sufficient to govern the expression patterns of these transcripts. Several RNA-binding proteins are required to regulate maternal mRNAs through the 3'UTR. Despite intensive efforts to map RNA-binding protein-mRNA interactions in vivo, the biological impact of most binding events remains unknown. Reporter studies using single copy integrated transgenes are essential to evaluate the functional consequences of interactions between RNA-binding proteins and their associated mRNAs. RESULTS In this report, we present an efficient method of generating reporter strains with improved throughput by using a library variant of MosSCI transgenesis. Furthermore, using RNA interference, we identify the suite of RNA-binding proteins that control the expression pattern of five different maternal mRNAs. CONCLUSIONS The results provide a generalizable and efficient strategy to assess the functional relevance of protein-RNA interactions in vivo, and reveal new regulatory connections between key RNA-binding proteins and their maternal mRNA targets. Developmental Dynamics 245:925-936, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ebru Kaymak
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Brian M. Farley
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Samantha A. Hay
- Virginia Commonwealth University School of Medicine, VA, USA
| | - Chihua Li
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Samantha Ho
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | | | - Sean P. Ryder
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
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28
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Gomes LC, Odedra D, Dikic I, Pohl C. Autophagy and modular restructuring of metabolism control germline tumor differentiation and proliferation in C. elegans. Autophagy 2016; 12:529-46. [PMID: 26759963 PMCID: PMC4835962 DOI: 10.1080/15548627.2015.1136771] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Autophagy can act either as a tumor suppressor or as a survival mechanism for established tumors. To understand how autophagy plays this dual role in cancer, in vivo models are required. By using a highly heterogeneous C. elegans germline tumor, we show that autophagy-related proteins are expressed in a specific subset of tumor cells, neurons. Inhibition of autophagy impairs neuronal differentiation and increases tumor cell number, resulting in a shorter life span of animals with tumors, while induction of autophagy extends their life span by impairing tumor proliferation. Fasting of animals with fully developed tumors leads to a doubling of their life span, which depends on modular changes in transcription including switches in transcription factor networks and mitochondrial metabolism. Hence, our results suggest that metabolic restructuring, cell-type specific regulation of autophagy and neuronal differentiation constitute central pathways preventing growth of heterogeneous tumors.
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Affiliation(s)
- Ligia C Gomes
- a Buchmann Institute for Molecular Life Sciences, Goethe University , Frankfurt (Main) , Germany.,b Institute of Biochemistry II, School of Medicine, Goethe University , Frankfurt (Main) , Germany
| | - Devang Odedra
- a Buchmann Institute for Molecular Life Sciences, Goethe University , Frankfurt (Main) , Germany.,b Institute of Biochemistry II, School of Medicine, Goethe University , Frankfurt (Main) , Germany
| | - Ivan Dikic
- a Buchmann Institute for Molecular Life Sciences, Goethe University , Frankfurt (Main) , Germany.,b Institute of Biochemistry II, School of Medicine, Goethe University , Frankfurt (Main) , Germany.,c Department of Immunology and Medical Genetics , University of Split, School of Medicine , Split , Croatia
| | - Christian Pohl
- a Buchmann Institute for Molecular Life Sciences, Goethe University , Frankfurt (Main) , Germany.,b Institute of Biochemistry II, School of Medicine, Goethe University , Frankfurt (Main) , Germany
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Hubstenberger A, Cameron C, Noble SL, Keenan S, Evans TC. Modifiers of solid RNP granules control normal RNP dynamics and mRNA activity in early development. J Cell Biol 2015; 211:703-16. [PMID: 26527741 PMCID: PMC4639854 DOI: 10.1083/jcb.201504044] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 09/25/2015] [Indexed: 12/13/2022] Open
Abstract
Modifiers of aberrant solid RNP granules suggest new insights into pathways that control dynamics of large-scale RNP bodies and mRNAs during C. elegans oogenesis. Ribonucleoproteins (RNPs) often coassemble into supramolecular bodies with regulated dynamics. The factors controlling RNP bodies and connections to RNA regulation are unclear. During Caenorhabditis elegans oogenesis, cytoplasmic RNPs can transition among diffuse, liquid, and solid states linked to mRNA regulation. Loss of CGH-1/Ddx6 RNA helicase generates solid granules that are sensitive to mRNA regulators. Here, we identified 66 modifiers of RNP solids induced by cgh-1 mutation. A majority of genes promote or suppress normal RNP body assembly, dynamics, or metabolism. Surprisingly, polyadenylation factors promote RNP coassembly in vivo, suggesting new functions of poly(A) tail regulation in RNP dynamics. Many genes carry polyglutatmine (polyQ) motifs or modulate polyQ aggregation, indicating possible connections with neurodegenerative disorders induced by CAG/polyQ expansion. Several RNP body regulators repress translation of mRNA subsets, suggesting that mRNAs are repressed by multiple mechanisms. Collectively, these findings suggest new pathways of RNP modification that control large-scale coassembly and mRNA activity during development.
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Affiliation(s)
- Arnaud Hubstenberger
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 Pierre-and-Marie-Curie University, University Paris 06, 75005 Paris, France
| | - Cristiana Cameron
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Scott L Noble
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 Graduate Program in Molecular Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Sean Keenan
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Thomas C Evans
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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Nousch M, Eckmann CR. Translational activation maintains germline tissue homeostasis during adulthood. WORM 2015; 4:e1042644. [PMID: 26430565 PMCID: PMC4588557 DOI: 10.1080/21624054.2015.1042644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 03/30/2015] [Accepted: 04/10/2015] [Indexed: 02/03/2023]
Abstract
Adult tissue maintenance is achieved through a tightly controlled equilibrium of 2 opposing cell fates: stem cell proliferation and differentiation. In recent years, the germ line emerged as a powerful in vivo model tissue to investigate the underlying gene expression mechanisms regulating this balance. Studies in numerous organisms highlighted the prevalence of post-transcriptional mRNA regulation, which relies on RNA-targeting factors that influence mRNA fates (e.g. decay or translational efficiency). Conserved translational repressors were identified that build negative feedback loops to ensure one or the other cell fate. However, to facilitate a fast and efficient transition between 2 opposing cell fates, translational repression per se appears not to be sufficient, suggesting the involvement of additional modes of gene expression regulation. Cytoplasmic poly(A) polymerases (cytoPAPs) represent a unique class of post-transcriptional mRNA regulators that modify mRNA 3' ends and positively influence cytoplasmic mRNA fates. We recently discovered that the 2 main cytoPAPs, GLD-2 and GLD-4, use distinct mechanisms to promote gene expression and that cytoPAP-mediated mRNA activation is important for regulating the size of the proliferative germ cell pool in the adult Caenorhabditis elegans gonad. Here, we comment on the different mechanisms of the 2 cytoPAPs as translational activators in germ cell development and focus on their biological roles in maintaining the balance between germline stem cell proliferation and differentiation in the Caenorhabditis elegans gonad.
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Affiliation(s)
- Marco Nousch
- Division of Genetics; Institute of Biology; Martin Luther University, Halle-Wittenberg ; Halle, Saales, Germany
| | - Christian R Eckmann
- Division of Genetics; Institute of Biology; Martin Luther University, Halle-Wittenberg ; Halle, Saales, Germany ; Max Planck Institute of Molecular Cell Biology and Genetics ; Dresden, Germany
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Levi-Ferber M, Gian H, Dudkevich R, Henis-Korenblit S. Transdifferentiation mediated tumor suppression by the endoplasmic reticulum stress sensor IRE-1 in C. elegans. eLife 2015; 4. [PMID: 26192965 PMCID: PMC4507713 DOI: 10.7554/elife.08005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 07/02/2015] [Indexed: 12/18/2022] Open
Abstract
Deciphering effective ways to suppress tumor progression and to overcome acquired apoptosis resistance of tumor cells are major challenges in the tumor therapy field. We propose a new concept by which tumor progression can be suppressed by manipulating tumor cell identity. In this study, we examined the effect of ER stress on apoptosis resistant tumorous cells in a Caenorhabditis elegans germline tumor model. We discovered that ER stress suppressed the progression of the lethal germline tumor by activating the ER stress sensor IRE-1. This suppression was associated with the induction of germ cell transdifferentiation into ectopic somatic cells. Strikingly, transdifferentiation of the tumorous germ cells restored their ability to execute apoptosis and enabled their subsequent removal from the gonad. Our results indicate that tumor cell transdifferentiation has the potential to combat cancer and overcome the escape of tumor cells from the cell death machinery. DOI:http://dx.doi.org/10.7554/eLife.08005.001 If a cell in the body becomes damaged or stops working properly, it can trigger its own destruction. This helps to prevent the accumulation of damaged cells. However, cancer cells can often tolerate much greater damage than normal cells. Toxic chemotherapies, which are often used to treat cancer, work by severely damaging the cells to help trigger their self-destruction. Unfortunately, chemotherapy does not work on all cancer cells, and the remaining treatment-resistant cells may continue to grow and spread in more aggressive ways. Now, Levi-Ferber et al. have found a way to change the identity of cancer cells, which makes them more likely to self-destruct. The experiments used roundworms called Caenorhabditis elegans that had a genetic mutation that causes them to develop tumors in their reproductive organs. Normally, the cells in these tumors do not self-destruct. Levi-Ferber et al. exposed tumor cells from the worms to chemicals or to genetic modifications that cause unfolded proteins to accumulate inside the cell. This build-up of proteins stresses a structure in the cell called the endoplasmic reticulum. Normally, if endoplasmic reticulum stress gets too high, the cell activates various pathways to relieve the stress, and if these fail, the cell self-destructs. Levi-Ferber et al. showed that a protein called IRE-1, which senses endoplasmic reticulum stress, caused the tumor cells to change into a type of non-cancerous cell. After the change, the cells were also more sensitive to self-destruction. This meant that tumors grew more slowly and ended up smaller, allowing the animals to survive longer. Together, the experiments suggest that treatments that force cancer cells to become a different cell type might be one way to prevent the emergence of treatment-resistant tumor cells. Future research will be needed to investigate exactly how IRE-1 causes the identity of the cell to change, and to see if this process could treat other kinds of cancer. DOI:http://dx.doi.org/10.7554/eLife.08005.002
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Affiliation(s)
- Mor Levi-Ferber
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Hai Gian
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Reut Dudkevich
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Sivan Henis-Korenblit
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
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Control of Caenorhabditis elegans germ-line stem-cell cycling speed meets requirements of design to minimize mutation accumulation. BMC Biol 2015; 13:51. [PMID: 26187634 PMCID: PMC4538916 DOI: 10.1186/s12915-015-0148-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 06/02/2015] [Indexed: 12/28/2022] Open
Abstract
Background Stem cells are thought to play a critical role in minimizing the accumulation of mutations, but it is not clear which strategies they follow to fulfill that performance objective. Slow cycling of stem cells provides a simple strategy that can minimize cell pedigree depth and thereby minimize the accumulation of replication-dependent mutations. Although the power of this strategy was recognized early on, a quantitative assessment of whether and how it is employed by biological systems is missing. Results Here we address this problem using a simple self-renewing organ – the C. elegans gonad – whose overall organization is shared with many self-renewing organs. Computational simulations of mutation accumulation characterize a tradeoff between fast development and low mutation accumulation, and show that slow-cycling stem cells allow for an advantageous compromise to be reached. This compromise is such that worm germ-line stem cells should cycle more slowly than their differentiating counterparts, but only by a modest amount. Experimental measurements of cell cycle lengths derived using a new, quantitative technique are consistent with these predictions. Conclusions Our findings shed light both on design principles that underlie the role of stem cells in delaying aging and on evolutionary forces that shape stem-cell gene regulatory networks. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0148-y) contains supplementary material, which is available to authorized users.
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PUF-8 Functions Redundantly with GLD-1 to Promote the Meiotic Progression of Spermatocytes in Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2015; 5:1675-84. [PMID: 26068572 PMCID: PMC4528324 DOI: 10.1534/g3.115.019521] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Successful meiotic progression of germ cells is crucial for gametogenesis. Defects in this process affect proper genetic transmission and sometimes lead to tumor formation in the germline. In Caenorhabditis elegans, the RNA-binding protein GLD-1 is essential for the meiotic development of oocytes. However, its role during spermatogenesis has not been understood. Here, we show that GLD-1 functions redundantly with the PUF family protein PUF-8 to ensure proper meiotic development of spermatocytes. When grown at 20°-the standard laboratory temperature for C. elegans growth-primary spermatocytes in both gld-1 and puf-8 single-mutant males and hermaphrodites complete the meiotic divisions normally. By contrast, some of the gld-1; puf-8 double-mutant spermatocytes exit meiosis and form germ cell tumors in both sexes. During larval development, gld-1; puf-8 double-mutant germ cells begin to express the meiotic marker HIM-3, lose P granules, and form the sperm-specific membranous organelle, which are characteristics of developing spermatocytes. However, some of these cells quickly lose HIM-3 and form germ cell tumors that lack membranous organelle but contain P granules. Mutations that block meiotic progression at late pachytene or diakinetic stage fail to arrest the tumorigenesis, suggesting that the gld-1; puf-8 double-mutant spermatocytes exit meiosis prior to the completion of pachytene. Together, results presented here uncover a novel function for gld-1 in the meiotic development of spermatocytes in both hermaphrodites and males.
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Osborne Nishimura E, Zhang JC, Werts AD, Goldstein B, Lieb JD. Asymmetric transcript discovery by RNA-seq in C. elegans blastomeres identifies neg-1, a gene important for anterior morphogenesis. PLoS Genet 2015; 11:e1005117. [PMID: 25875092 PMCID: PMC4395330 DOI: 10.1371/journal.pgen.1005117] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 03/03/2015] [Indexed: 11/23/2022] Open
Abstract
After fertilization but prior to the onset of zygotic transcription, the C. elegans zygote cleaves asymmetrically to create the anterior AB and posterior P1 blastomeres, each of which goes on to generate distinct cell lineages. To understand how patterns of RNA inheritance and abundance arise after this first asymmetric cell division, we pooled hand-dissected AB and P1 blastomeres and performed RNA-seq. Our approach identified over 200 asymmetrically abundant mRNA transcripts. We confirmed symmetric or asymmetric abundance patterns for a subset of these transcripts using smFISH. smFISH also revealed heterogeneous subcellular patterning of the P1-enriched transcripts chs-1 and bpl-1. We screened transcripts enriched in a given blastomere for embryonic defects using RNAi. The gene neg-1 (F32D1.6) encoded an AB-enriched (anterior) transcript and was required for proper morphology of anterior tissues. In addition, analysis of the asymmetric transcripts yielded clues regarding the post-transcriptional mechanisms that control cellular mRNA abundance during asymmetric cell divisions, which are common in developing organisms.
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Affiliation(s)
- Erin Osborne Nishimura
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jay C. Zhang
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Adam D. Werts
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Bob Goldstein
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jason D. Lieb
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Human Genetics, University of Chicago, Chicago, Illinois, United States of America
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36
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Abstract
RNA-binding proteins (RBPs) are important regulators of eukaryotic gene expression. Genomes typically encode dozens to hundreds of proteins containing RNA-binding domains, which collectively recognize diverse RNA sequences and structures. Recent advances in high-throughput methods for assaying the targets of RBPs in vitro and in vivo allow large-scale derivation of RNA-binding motifs as well as determination of RNA–protein interactions in living cells. In parallel, many computational methods have been developed to analyze and interpret these data. The interplay between RNA secondary structure and RBP binding has also been a growing theme. Integrating RNA–protein interaction data with observations of post-transcriptional regulation will enhance our understanding of the roles of these important proteins.
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37
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Beadell AV, Haag ES. Evolutionary Dynamics of GLD-1-mRNA complexes in Caenorhabditis nematodes. Genome Biol Evol 2014; 7:314-35. [PMID: 25502909 PMCID: PMC4316625 DOI: 10.1093/gbe/evu272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2014] [Indexed: 12/17/2022] Open
Abstract
Given the large number of RNA-binding proteins and regulatory RNAs within genomes, posttranscriptional regulation may be an underappreciated aspect of cis-regulatory evolution. Here, we focus on nematode germ cells, which are known to rely heavily upon translational control to regulate meiosis and gametogenesis. GLD-1 belongs to the STAR-domain family of RNA-binding proteins, conserved throughout eukaryotes, and functions in Caenorhabditis elegans as a germline-specific translational repressor. A phylogenetic analysis across opisthokonts shows that GLD-1 is most closely related to Drosophila How and deuterostome Quaking, both implicated in alternative splicing. We identify messenger RNAs associated with C. briggsae GLD-1 on a genome-wide scale and provide evidence that many participate in aspects of germline development. By comparing our results with published C. elegans GLD-1 targets, we detect nearly 100 that are conserved between the two species. We also detected several hundred Cbr-GLD-1 targets whose homologs have not been reported to be associated with C. elegans GLD-1 in either of two independent studies. Low expression in C. elegans may explain the failure to detect most of them, but a highly expressed subset are strong candidates for Cbr-GLD-1-specific targets. We examine GLD-1-binding motifs among targets conserved in C. elegans and C. briggsae and find that most, but not all, display evidence of shared ancestral binding sites. Our work illustrates both the conservative and the dynamic character of evolution at the posttranslational level of gene regulation, even between congeners.
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Affiliation(s)
- Alana V Beadell
- Program in Behavior, Evolution, Ecology, and Systematics, University of Maryland, College Park Present address: Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL
| | - Eric S Haag
- Program in Behavior, Evolution, Ecology, and Systematics, University of Maryland, College Park Department of Biology, University of Maryland, College Park
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38
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Competition between target sites of regulators shapes post-transcriptional gene regulation. Nat Rev Genet 2014; 16:113-26. [PMID: 25488579 DOI: 10.1038/nrg3853] [Citation(s) in RCA: 193] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Post-transcriptional gene regulation (PTGR) of mRNA turnover, localization and translation is mediated by microRNAs (miRNAs) and RNA-binding proteins (RBPs). These regulators exert their effects by binding to specific sequences within their target mRNAs. Increasing evidence suggests that competition for binding is a fundamental principle of PTGR. Not only can miRNAs be sequestered and neutralized by the targets with which they interact through a process termed 'sponging', but competition between binding sites on different RNAs may also lead to regulatory crosstalk between transcripts. Here, we quantitatively model competition effects under physiological conditions and review the role of endogenous sponges for PTGR in light of the key features that emerge.
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39
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Spike CA, Coetzee D, Nishi Y, Guven-Ozkan T, Oldenbroek M, Yamamoto I, Lin R, Greenstein D. Translational control of the oogenic program by components of OMA ribonucleoprotein particles in Caenorhabditis elegans. Genetics 2014; 198:1513-33. [PMID: 25261697 PMCID: PMC4256769 DOI: 10.1534/genetics.114.168823] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 08/29/2014] [Indexed: 02/02/2023] Open
Abstract
The oocytes of most sexually reproducing animals arrest in meiotic prophase I. Oocyte growth, which occurs during this period of arrest, enables oocytes to acquire the cytoplasmic components needed to produce healthy progeny and to gain competence to complete meiosis. In the nematode Caenorhabditis elegans, the major sperm protein hormone promotes meiotic resumption (also called meiotic maturation) and the cytoplasmic flows that drive oocyte growth. Prior work established that two related TIS11 zinc-finger RNA-binding proteins, OMA-1 and OMA-2, are redundantly required for normal oocyte growth and meiotic maturation. We affinity purified OMA-1 and identified associated mRNAs and proteins using genome-wide expression data and mass spectrometry, respectively. As a class, mRNAs enriched in OMA-1 ribonucleoprotein particles (OMA RNPs) have reproductive functions. Several of these mRNAs were tested and found to be targets of OMA-1/2-mediated translational repression, dependent on sequences in their 3'-untranslated regions (3'-UTRs). Consistent with a major role for OMA-1 and OMA-2 in regulating translation, OMA-1-associated proteins include translational repressors and activators, and some of these proteins bind directly to OMA-1 in yeast two-hybrid assays, including OMA-2. We show that the highly conserved TRIM-NHL protein LIN-41 is an OMA-1-associated protein, which also represses the translation of several OMA-1/2 target mRNAs. In the accompanying article in this issue, we show that LIN-41 prevents meiotic maturation and promotes oocyte growth in opposition to OMA-1/2. Taken together, these data support a model in which the conserved regulators of mRNA translation LIN-41 and OMA-1/2 coordinately control oocyte growth and the proper spatial and temporal execution of the meiotic maturation decision.
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Affiliation(s)
- Caroline A Spike
- Department of Genetics, Cell Biology and Development, University of Minnesota Minneapolis, Minnesota 55455
| | - Donna Coetzee
- Department of Genetics, Cell Biology and Development, University of Minnesota Minneapolis, Minnesota 55455
| | - Yuichi Nishi
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Tugba Guven-Ozkan
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Marieke Oldenbroek
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Ikuko Yamamoto
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Rueyling Lin
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - David Greenstein
- Department of Genetics, Cell Biology and Development, University of Minnesota Minneapolis, Minnesota 55455
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40
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Spike CA, Coetzee D, Eichten C, Wang X, Hansen D, Greenstein D. The TRIM-NHL protein LIN-41 and the OMA RNA-binding proteins antagonistically control the prophase-to-metaphase transition and growth of Caenorhabditis elegans oocytes. Genetics 2014; 198:1535-58. [PMID: 25261698 PMCID: PMC4256770 DOI: 10.1534/genetics.114.168831] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 09/26/2014] [Indexed: 01/24/2023] Open
Abstract
In many animals, oocytes enter meiosis early in their development but arrest in meiotic prophase I. Oocyte growth, which occurs during this arrest period, enables the acquisition of meiotic competence and the capacity to produce healthy progeny. Meiotic resumption, or meiotic maturation, involves the transition to metaphase I (M phase) and is regulated by intercellular signaling and cyclin-dependent kinase activation. Premature meiotic maturation would be predicted to diminish fertility as the timing of this event, which normally occurs after oocyte growth is complete, is crucial. In the accompanying article in this issue, we identify the highly conserved TRIM-NHL protein LIN-41 as a translational repressor that copurifies with OMA-1 and OMA-2, RNA-binding proteins redundantly required for normal oocyte growth and meiotic maturation. In this article, we show that LIN-41 enables the production of high-quality oocytes and plays an essential role in controlling and coordinating oocyte growth and meiotic maturation. lin-41 null mutants display a striking defect that is specific to oogenesis: pachytene-stage cells cellularize prematurely and fail to progress to diplotene. Instead, these cells activate CDK-1, enter M phase, assemble spindles, and attempt to segregate chromosomes. Translational derepression of the CDK-1 activator CDC-25.3 appears to contribute to premature M-phase entry in lin-41 mutant oocytes. Genetic and phenotypic analyses indicate that LIN-41 and OMA-1/2 exhibit an antagonistic relationship, and we suggest that translational regulation by these proteins could be important for controlling and coordinating oocyte growth and meiotic maturation.
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Affiliation(s)
- Caroline A Spike
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Donna Coetzee
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Carly Eichten
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Xin Wang
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Dave Hansen
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - David Greenstein
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
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41
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Blackinton JG, Keene JD. Post-transcriptional RNA regulons affecting cell cycle and proliferation. Semin Cell Dev Biol 2014; 34:44-54. [PMID: 24882724 PMCID: PMC4163074 DOI: 10.1016/j.semcdb.2014.05.014] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 05/21/2014] [Indexed: 01/19/2023]
Abstract
The cellular growth cycle is initiated and maintained by punctual, yet agile, regulatory events involving modifications of cell cycle proteins as well as coordinated gene expression to support cyclic checkpoint decisions. Recent evidence indicates that post-transcriptional partitioning of messenger RNA subsets by RNA-binding proteins help physically localize, temporally coordinate, and efficiently translate cell cycle proteins. This dynamic organization of mRNAs encoding cell cycle components contributes to the overall economy of the cell cycle consistent with the post-transcriptional RNA regulon model of gene expression. This review examines several recent studies demonstrating the coordination of mRNA subsets encoding cell cycle proteins during nuclear export and subsequent coupling to protein synthesis, and discusses evidence for mRNA coordination of p53 targets and the DNA damage response pathway. We consider how these observations may connect to upstream and downstream post-transcriptional coordination and coupling of splicing, export, localization, and translation. Published examples from yeast, nematode, insect, and mammalian systems are discussed, and we consider genetic evidence supporting the conclusion that dysregulation of RNA regulons may promote pathogenic states of growth such as carcinogenesis.
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Affiliation(s)
- Jeff G Blackinton
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, Box 3020, Durham, NC 27710, USA
| | - Jack D Keene
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, Box 3020, Durham, NC 27710, USA.
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42
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Millonigg S, Minasaki R, Nousch M, Eckmann CR. GLD-4-mediated translational activation regulates the size of the proliferative germ cell pool in the adult C. elegans germ line. PLoS Genet 2014; 10:e1004647. [PMID: 25254367 PMCID: PMC4177745 DOI: 10.1371/journal.pgen.1004647] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 08/04/2014] [Indexed: 12/26/2022] Open
Abstract
To avoid organ dysfunction as a consequence of tissue diminution or tumorous growth, a tight balance between cell proliferation and differentiation is maintained in metazoans. However, cell-intrinsic gene expression mechanisms controlling adult tissue homeostasis remain poorly understood. By focusing on the adult Caenorhabditis elegans reproductive tissue, we show that translational activation of mRNAs is a fundamental mechanism to maintain tissue homeostasis. Our genetic experiments identified the Trf4/5-type cytoplasmic poly(A) polymerase (cytoPAP) GLD-4 and its enzymatic activator GLS-1 to perform a dual role in regulating the size of the proliferative zone. Consistent with a ubiquitous expression of GLD-4 cytoPAP in proliferative germ cells, its genetic activity is required to maintain a robust proliferative adult germ cell pool, presumably by regulating many mRNA targets encoding proliferation-promoting factors. Based on translational reporters and endogenous protein expression analyses, we found that gld-4 activity promotes GLP-1/Notch receptor expression, an essential factor of continued germ cell proliferation. RNA-protein interaction assays documented also a physical association of the GLD-4/GLS-1 cytoPAP complex with glp-1 mRNA, and ribosomal fractionation studies established that GLD-4 cytoPAP activity facilitates translational efficiency of glp-1 mRNA. Moreover, we found that in proliferative cells the differentiation-promoting factor, GLD-2 cytoPAP, is translationally repressed by the stem cell factor and PUF-type RNA-binding protein, FBF. This suggests that cytoPAP-mediated translational activation of proliferation-promoting factors, paired with PUF-mediated translational repression of differentiation factors, forms a translational control circuit that expands the proliferative germ cell pool. Our additional genetic experiments uncovered that the GLD-4/GLS-1 cytoPAP complex promotes also differentiation, forming a redundant translational circuit with GLD-2 cytoPAP and the translational repressor GLD-1 to restrict proliferation. Together with previous findings, our combined data reveals two interconnected translational activation/repression circuitries of broadly conserved RNA regulators that maintain the balance between adult germ cell proliferation and differentiation. Throughout adulthood, animal tissue homeostasis requires adult stem cell activities. A tight balance between self-renewal and differentiation protects against tissue overgrowth or loss. This balance is strongly influenced by niche-mediated signaling pathways that primarily trigger a transcriptional response in stem cells to promote self-renewal/proliferation. However, the cell-intrinsic mechanisms that modulate signaling pathways to promote proliferation or differentiation are poorly understood. Recently, post-transcriptional mRNA regulation emerged in diverse germline stem cell systems as an important gene expression mechanism, primarily preventing the protein synthesis of factors that promote the switch to differentiation. In the adult C. elegans germ line, this study finds that the evolutionarily conserved cytoplasmic poly(A) polymerase, GLD-4, plays an crucial role in maintaining a healthy balance between proliferation and differentiation forces. This is in part due to translational activation of the mRNA that encodes the germ cell-expressed Notch signaling receptor, an essential regulator of proliferation. Moreover, GLD-4 activity is part of a redundant genetic network downstream of Notch that, together with several other conserved mRNA regulators, promotes differentiation onset. Given the widespread expression of these conserved RNA regulators in metazoans, cell fate balances that are reinforced by translational activation and repression circuitries may therefore be a general mechanism of adult tissue maintenance.
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Affiliation(s)
- Sophia Millonigg
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
| | - Ryuji Minasaki
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
| | - Marco Nousch
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
| | - Christian R. Eckmann
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
- * E-mail:
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Nousch M, Yeroslaviz A, Habermann B, Eckmann CR. The cytoplasmic poly(A) polymerases GLD-2 and GLD-4 promote general gene expression via distinct mechanisms. Nucleic Acids Res 2014; 42:11622-33. [PMID: 25217583 PMCID: PMC4191412 DOI: 10.1093/nar/gku838] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Post-transcriptional gene regulation mechanisms decide on cellular mRNA activities. Essential gatekeepers of post-transcriptional mRNA regulation are broadly conserved mRNA-modifying enzymes, such as cytoplasmic poly(A) polymerases (cytoPAPs). Although these non-canonical nucleotidyltransferases efficiently elongate mRNA poly(A) tails in artificial tethering assays, we still know little about their global impact on poly(A) metabolism and their individual molecular roles in promoting protein production in organisms. Here, we use the animal model Caenorhabditis elegans to investigate the global mechanisms of two germline-enriched cytoPAPs, GLD-2 and GLD-4, by combining polysome profiling with RNA sequencing. Our analyses suggest that GLD-2 activity mediates mRNA stability of many translationally repressed mRNAs. This correlates with a general shortening of long poly(A) tails in gld-2-compromised animals, suggesting that most if not all targets are stabilized via robust GLD-2-mediated polyadenylation. By contrast, only mild polyadenylation defects are found in gld-4-compromised animals and few mRNAs change in abundance. Interestingly, we detect a reduced number of polysomes in gld-4 mutants and GLD-4 protein co-sediments with polysomes, which together suggest that GLD-4 might stimulate or maintain translation directly. Our combined data show that distinct cytoPAPs employ different RNA-regulatory mechanisms to promote gene expression, offering new insights into translational activation of mRNAs.
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Affiliation(s)
- Marco Nousch
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, Dresden, 01307, Germany
| | - Assa Yeroslaviz
- Max Planck Institute of Biochemistry (MPIB), Am Klopferspitz 18, Martinsried, 82152, Germany
| | - Bianca Habermann
- Max Planck Institute of Biochemistry (MPIB), Am Klopferspitz 18, Martinsried, 82152, Germany
| | - Christian R Eckmann
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, Dresden, 01307, Germany
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Two classes of gap junction channels mediate soma-germline interactions essential for germline proliferation and gametogenesis in Caenorhabditis elegans. Genetics 2014; 198:1127-53. [PMID: 25195067 PMCID: PMC4224157 DOI: 10.1534/genetics.114.168815] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In all animals examined, somatic cells of the gonad control multiple biological processes essential for germline development. Gap junction channels, composed of connexins in vertebrates and innexins in invertebrates, permit direct intercellular communication between cells and frequently form between somatic gonadal cells and germ cells. Gap junctions comprise hexameric hemichannels in apposing cells that dock to form channels for the exchange of small molecules. Here we report essential roles for two classes of gap junction channels, composed of five innexin proteins, in supporting the proliferation of germline stem cells and gametogenesis in the nematode Caenorhabditis elegans. Transmission electron microscopy of freeze-fracture replicas and fluorescence microscopy show that gap junctions between somatic cells and germ cells are more extensive than previously appreciated and are found throughout the gonad. One class of gap junctions, composed of INX-8 and INX-9 in the soma and INX-14 and INX-21 in the germ line, is required for the proliferation and differentiation of germline stem cells. Genetic epistasis experiments establish a role for these gap junction channels in germline proliferation independent of the glp-1/Notch pathway. A second class of gap junctions, composed of somatic INX-8 and INX-9 and germline INX-14 and INX-22, is required for the negative regulation of oocyte meiotic maturation. Rescue of gap junction channel formation in the stem cell niche rescues germline proliferation and uncovers a later channel requirement for embryonic viability. This analysis reveals gap junctions as a central organizing feature of many soma–germline interactions in C. elegans.
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Abstract
STAR (signal transduction and activation of RNA) proteins are a family of RNA-binding proteins that regulate post-transcriptional gene regulation events at various levels, such as pre-mRNA alternative splicing, RNA export, translation and stability. Most of these proteins are regulated by signalling pathways through post-translational modifications, such as phosphorylation and arginine methylation. These proteins share a highly conserved RNA-binding domain, denoted STAR domain. Structural investigations of this STAR domain in complex with RNA have highlighted how a subset of STAR proteins specifically recognizes its RNA targets. The present review focuses on the structural basis of RNA recognition by this family of proteins.
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Ivshina M, Lasko P, Richter JD. Cytoplasmic polyadenylation element binding proteins in development, health, and disease. Annu Rev Cell Dev Biol 2014; 30:393-415. [PMID: 25068488 DOI: 10.1146/annurev-cellbio-101011-155831] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The cytoplasmic polyadenylation element binding (CPEB) proteins are sequence-specific mRNA binding proteins that control translation in development, health, and disease. CPEB1, the founding member of this family, has become an important model for illustrating general principles of translational control by cytoplasmic polyadenylation in gametogenesis, cancer etiology, synaptic plasticity, learning, and memory. Although the biological functions of the other members of this protein family in vertebrates are just beginning to emerge, it is already evident that they, too, mediate important processes, such as cancer etiology and higher cognitive function. In Drosophila, the CPEB proteins Orb and Orb2 play key roles in oogenesis and in neuronal function, as do related proteins in Caenorhabditis elegans and Aplysia. We review the biochemical features of the CPEB proteins, discuss their activities in several biological systems, and illustrate how understanding CPEB activity in model organisms has an important impact on neurological disease.
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Affiliation(s)
- Maria Ivshina
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605;
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Daubner GM, Brümmer A, Tocchini C, Gerhardy S, Ciosk R, Zavolan M, Allain FHT. Structural and functional implications of the QUA2 domain on RNA recognition by GLD-1. Nucleic Acids Res 2014; 42:8092-105. [PMID: 24838563 PMCID: PMC4081071 DOI: 10.1093/nar/gku445] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 05/04/2014] [Accepted: 05/06/2014] [Indexed: 01/13/2023] Open
Abstract
The STAR family comprises ribonucleic acid (RNA)-binding proteins that play key roles in RNA-regulatory processes. RNA recognition is achieved by a KH domain with an additional α-helix (QUA2) that seems to extend the RNA-binding surface to six nucleotides for SF1 (Homo sapiens) and seven nucleotides for GLD-1 (Caenorhabditis elegans). To understand the structural basis of this probable difference in specificity, we determined the solution structure of GLD-1 KH-QUA2 with the complete consensus sequence identified in the tra-2 gene. Compared to SF1, the GLD-1 KH-QUA2 interface adopts a different conformation resulting indeed in an additional sequence-specific binding pocket for a uracil at the 5'end. The functional relevance of this binding pocket is emphasized by our bioinformatics analysis showing that GLD-1 binding sites with this 5'end uracil are more predictive for the functional response of the messenger RNAs to gld-1 knockout. We further reveal the importance of the KH-QUA2 interface in vitro and that its alteration in vivo affects the level of translational repression dependent on the sequence of the GLD-1 binding motif. In conclusion, we demonstrate that the QUA2 domain distinguishes GLD-1 from other members of the STAR family and contributes more generally to the modulation of RNA-binding affinity and specificity of KH domain containing proteins.
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Affiliation(s)
- Gerrit M Daubner
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, 8093 Zürich, Switzerland
| | - Anneke Brümmer
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Cristina Tocchini
- Friedrich Miescher Institute for Biomedical Research, 4002 Basel, Switzerland
| | - Stefan Gerhardy
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, 8093 Zürich, Switzerland
| | - Rafal Ciosk
- Friedrich Miescher Institute for Biomedical Research, 4002 Basel, Switzerland
| | | | - Frédéric H-T Allain
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH) Zürich, 8093 Zürich, Switzerland
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Affiliation(s)
- Jack D Keene
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, USA
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Wang X, Gupta P, Fairbanks J, Hansen D. Protein kinase CK2 both promotes robust proliferation and inhibits the proliferative fate in the C. elegans germ line. Dev Biol 2014; 392:26-41. [PMID: 24824786 DOI: 10.1016/j.ydbio.2014.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/02/2014] [Accepted: 05/02/2014] [Indexed: 11/18/2022]
Abstract
Stem cells are capable of both self-renewal (proliferation) and differentiation. Determining the regulatory mechanisms controlling the balance between stem cell proliferation and differentiation is not only an important biological question, but also holds the key for using stem cells as therapeutic agents. The Caenorhabditis elegans germ line has emerged as a valuable model to study the molecular mechanisms controlling stem cell behavior. In this study, we describe a large-scale RNAi screen that identified kin-10, which encodes the β subunit of protein kinase CK2, as a novel factor regulating stem cell proliferation in the C. elegans germ line. While a loss of kin-10 in an otherwise wild-type background results in a decrease in the number of proliferative cells, loss of kin-10 in sensitized genetic backgrounds results in a germline tumor. Therefore, kin-10 is not only necessary for robust proliferation, it also inhibits the proliferative fate. We found that kin-10's regulatory role in inhibiting the proliferative fate is carried out through the CK2 holoenzyme, rather than through a holoenzyme-independent function, and that it functions downstream of GLP-1/Notch signaling. We propose that a loss of kin-10 leads to a defect in CK2 phosphorylation of its downstream targets, resulting in abnormal activity of target protein(s) that are involved in the proliferative fate vs. differentiation decision. This eventually causes a shift towards the proliferative fate in the stem cell fate decision.
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Affiliation(s)
- Xin Wang
- Department of Biological Sciences, University of Calgary, 2500 University Drive, Calgary, Alberta, Canada T2N 1N4
| | - Pratyush Gupta
- Department of Biological Sciences, University of Calgary, 2500 University Drive, Calgary, Alberta, Canada T2N 1N4
| | - Jared Fairbanks
- Department of Biological Sciences, University of Calgary, 2500 University Drive, Calgary, Alberta, Canada T2N 1N4
| | - Dave Hansen
- Department of Biological Sciences, University of Calgary, 2500 University Drive, Calgary, Alberta, Canada T2N 1N4.
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Doh JH, Jung Y, Reinke V, Lee MH. C. elegans RNA-binding protein GLD-1 recognizes its multiple targets using sequence, context, and structural information to repress translation. WORM 2014; 2:e26548. [PMID: 24744981 DOI: 10.4161/worm.26548] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/12/2013] [Accepted: 09/19/2013] [Indexed: 11/19/2022]
Abstract
Caenorhabditis elegans GLD-1, a maxi-KH motif containing RNA-binding protein, has various functions mainly during female germ cell development, suggesting that it likely controls the expression of a selective group of maternal mRNAs. To gain an insight into how GLD-1 specifically recognizes these mRNA targets, we identified 38 biochemically proven GLD-1 binding regions from multiple mRNA targets that are among over 100 putative targets co-immunoprecipitated with GLD-1. The sequence information of these regions revealed three over-represented and phylogenetically conserved sequence motifs. We found that two of the motifs, one of which is novel, are important for GLD-1 binding in several GLD-1 binding regions but not in other regions. Further analyses indicate that the importance of one of the sequence motifs is dependent on two aspects: (1) surrounding sequence information, likely acting as an accessory feature for GLD-1 to efficiently select the sequence motif and (2) RNA secondary structural environment where the sequence motif resides, which likely provides "binding-site accessibility" for GLD-1 to effectively recognize its targets. Our data suggest some mRNAs recruit GLD-1 by a distinct mechanism, which involves more than one sequence motif that needs to be embedded in the correct context and structural environment.
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Affiliation(s)
- Jung H Doh
- Department of Biological Sciences; University at Albany; SUNY; Albany, NY USA
| | - Yuchae Jung
- Department of Biological Sciences; University at Albany; SUNY; Albany, NY USA
| | - Valerie Reinke
- Department of Genetics; Yale University School of Medicine; New Haven, CT USA
| | - Min-Ho Lee
- Department of Biological Sciences; University at Albany; SUNY; Albany, NY USA
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