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Pispa J, Mikkonen E, Arpalahti L, Jin C, Martínez-Fernández C, Cerón J, Holmberg CI. AKIR-1 regulates proteasome subcellular function in Caenorhabditis elegans. iScience 2023; 26:107886. [PMID: 37767001 PMCID: PMC10520889 DOI: 10.1016/j.isci.2023.107886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 07/07/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
Polyubiquitinated proteins are primarily degraded by the ubiquitin-proteasome system (UPS). Proteasomes are present both in the cytoplasm and nucleus. Here, we investigated mechanisms coordinating proteasome subcellular localization and activity in a multicellular organism. We identified the nuclear protein-encoding gene akir-1 as a proteasome regulator in a genome-wide Caenorhabditis elegans RNAi screen. We demonstrate that depletion of akir-1 causes nuclear accumulation of endogenous polyubiquitinated proteins in intestinal cells, concomitant with slower in vivo proteasomal degradation in this subcellular compartment. Remarkably, akir-1 is essential for nuclear localization of proteasomes both in oocytes and intestinal cells but affects differentially the subcellular distribution of polyubiquitinated proteins. We further reveal that importin ima-3 genetically interacts with akir-1 and influences nuclear localization of a polyubiquitin-binding reporter. Our study shows that the conserved AKIR-1 is an important regulator of the subcellular function of proteasomes in a multicellular organism, suggesting a role for AKIR-1 in proteostasis maintenance.
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Affiliation(s)
- Johanna Pispa
- Department of Biochemistry and Developmental Biology, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Elisa Mikkonen
- Department of Biochemistry and Developmental Biology, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Leena Arpalahti
- Department of Biochemistry and Developmental Biology, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Congyu Jin
- Department of Anatomy, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Carmen Martínez-Fernández
- Modeling Human Diseases in C. elegans Group, Genes, Diseases, and Therapies Program, Institut d'Investigació Biomèdica de Bellvitge - IDIBELL, L'Hospitalet de Llobregat, 08908 Barcelona, Spain
| | - Julián Cerón
- Modeling Human Diseases in C. elegans Group, Genes, Diseases, and Therapies Program, Institut d'Investigació Biomèdica de Bellvitge - IDIBELL, L'Hospitalet de Llobregat, 08908 Barcelona, Spain
| | - Carina I. Holmberg
- Department of Biochemistry and Developmental Biology, Medicum, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
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2
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Qadota H, McPherson A, Corbitt R, Dackowski EK, Matsunaga Y, Oberhauser AF, Benian GM. Genetic analysis suggests a surface of PAT-4 (ILK) that interacts with UNC-112 (kindlin). G3 (BETHESDA, MD.) 2022; 12:jkac117. [PMID: 35536217 PMCID: PMC9258589 DOI: 10.1093/g3journal/jkac117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 05/05/2022] [Indexed: 11/12/2022]
Abstract
Integrin plays a crucial role in the attachment of cells to the extracellular matrix. Integrin recruits many proteins intracellularly, including a 4-protein complex (kindlin, ILK, PINCH, and parvin). Caenorhabditis elegans muscle provides an excellent model to study integrin adhesion complexes. In Caenorhabditis elegans, UNC-112 (kindlin) binds to the cytoplasmic tail of PAT-3 (β-integrin) and to PAT-4 (ILK). We previously reported that PAT-4 binding to UNC-112 is essential for the binding of UNC-112 to PAT-3. Although there are crystal structures for ILK and a kindlin, there is no co-crystal structure available. To understand the molecular interaction between PAT-4 and UNC-112, we took a genetic approach. First, using a yeast 2-hybrid method, we isolated mutant PAT-4 proteins that cannot bind to UNC-112 and then isolated suppressor mutant UNC-112 proteins that restore interaction with mutant PAT-4 proteins. Second, we demonstrated that these mutant PAT-4 proteins cannot localize to attachment structures in nematode muscle, but upon co-expression of an UNC-112 suppressor mutant protein, mutant PAT-4 proteins could localize to attachment structures. Third, overexpression of a PAT-4 mutant results in the disorganization of adhesion plaques at muscle cell boundaries and co-expression of the UNC-112 suppressor mutant protein alleviates this defect. Thus, we demonstrate that UNC-112 binding to PAT-4 is required for the localization and function of PAT-4 in integrin adhesion complexes in vivo. The missense mutations were mapped onto homology models of PAT-4 and UNC-112, and taking into account previously isolated mutations, we suggest a surface of PAT-4 that binds to UNC-112.
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Affiliation(s)
- Hiroshi Qadota
- Department of Pathology, Emory University, Atlanta, GA 30322, USA
| | - Annie McPherson
- Department of Pathology, Emory University, Atlanta, GA 30322, USA
| | - Rachel Corbitt
- Department of Pathology, Emory University, Atlanta, GA 30322, USA
| | | | - Yohei Matsunaga
- Department of Pathology, Emory University, Atlanta, GA 30322, USA
| | - Andres F Oberhauser
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Guy M Benian
- Department of Pathology, Emory University, Atlanta, GA 30322, USA
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3
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Xi Z, Davis L, Baxter K, Tynan A, Goutou A, Greiss S. Using a quadruplet codon to expand the genetic code of an animal. Nucleic Acids Res 2022; 50:4801-4812. [PMID: 34882769 PMCID: PMC9122531 DOI: 10.1093/nar/gkab1168] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/06/2021] [Accepted: 11/11/2021] [Indexed: 11/13/2022] Open
Abstract
Genetic code expansion in multicellular organisms is currently limited to the use of repurposed amber stop codons. Here, we introduce a system for the use of quadruplet codons to direct incorporation of non-canonical amino acids in vivo in an animal, the nematode worm Caenorhabditis elegans. We develop hybrid pyrrolysyl tRNA variants to incorporate non-canonical amino acids in response to the quadruplet codon UAGA. We demonstrate the efficiency of the quadruplet decoding system by incorporating photocaged amino acids into two proteins widely used as genetic tools. We use photocaged lysine to express photocaged Cre recombinase for the optical control of gene expression and photocaged cysteine to express photo-activatable caspase for light inducible cell ablation. Our approach will facilitate the routine adoption of quadruplet decoding for genetic code expansion in eukaryotic cells and multicellular organisms.
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Affiliation(s)
- Zhiyan Xi
- Centre for Discovery Brain Sciences, University of Edinburgh, UK
| | - Lloyd Davis
- Centre for Discovery Brain Sciences, University of Edinburgh, UK
| | - Kieran Baxter
- Centre for Discovery Brain Sciences, University of Edinburgh, UK
| | - Ailish Tynan
- Centre for Discovery Brain Sciences, University of Edinburgh, UK
| | - Angeliki Goutou
- Centre for Discovery Brain Sciences, University of Edinburgh, UK
| | - Sebastian Greiss
- Centre for Discovery Brain Sciences, University of Edinburgh, UK
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4
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Qadota H, Oberhauser AF, Benian GM. Missense mutation of a conserved residue in UNC-112 (kindlin) eliminates binding to PAT-4 (ILK). MICROPUBLICATION BIOLOGY 2021; 2021. [PMID: 34549173 PMCID: PMC8449257 DOI: 10.17912/micropub.biology.000454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/02/2021] [Accepted: 09/07/2021] [Indexed: 12/26/2022]
Abstract
C. elegans UNC-112 (kindlin) is required for muscle sarcomere assembly, and is one component of a conserved four-protein complex that associates with the cytoplasmic tail of integrin at the base of integrin adhesion complexes in muscle. The four-protein complex consists of UNC-112 (kindlin), PAT-4 (integrin linked kinase; ILK), PAT-6 (alpha-parvin), and UNC-97 (PINCH). UNC-112 is comprised of 720 amino acid residues and contains FERM and PH domains. The N-terminal half of UNC-112 (1-396 aa) can bind to the C-terminal half of UNC-112 (397-720 aa), and this interaction is inhibited by the association of PAT-4 (ILK) to the N-terminal half of UNC-112. In support of this model, previously, we reported identification of a D382V mutation that results in lack of binding to PAT-4. However, this residue is not conserved in human Kindlins. Here, we report identification of a novel UNC-112 mutation of a conserved residue that cannot bind to PAT-4. UNC-112 E302G cannot bind to PAT-4 and does not localize to integrin adhesion complexes in muscle.
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Affiliation(s)
- Hiroshi Qadota
- Department of Pathology, Emory University, Atlanta, Georgia
| | - Andres F Oberhauser
- Department of Neuroscience, Cell Biology & Anatomy, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas
| | - Guy M Benian
- Department of Pathology, Emory University, Atlanta, Georgia
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5
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Tang H, Cui M, Han M. Fatty acids impact sarcomere integrity through myristoylation and ER homeostasis. Cell Rep 2021; 36:109539. [PMID: 34407398 PMCID: PMC8404530 DOI: 10.1016/j.celrep.2021.109539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 06/04/2021] [Accepted: 07/26/2021] [Indexed: 01/01/2023] Open
Abstract
Decreased ability to maintain tissue integrity is critically involved in aging and degenerative diseases. Fatty acid (FA) metabolism has a profound impact on animal development and tissue maintenance, but our understanding of the underlying mechanisms is limited. We investigated whether and how FA abundance affects muscle integrity using Caenorhabditis elegans. We show that reducing the overall FA level by blocking FA biosynthesis or inhibiting protein myristoylation leads to disorganization of sarcomere structure and adult-onset paralysis. Further analysis indicates that myristoylation of two ARF guanosine triphosphatases (GTPases) critically mediates the effect of FA deficiency on sarcomere integrity through inducing endoplasmic reticulum (ER) stress and ER unfolded protein response (UPRER), which in turn leads to reduction of the level of sarcomere component PINCH and myosin disorganization. We thus present a mechanism that links FA signal, protein myristoylation, and ER homeostasis with muscle integrity, which provides valuable insights into the regulatory role of nutrients and ER homeostasis in muscle maintenance.
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Affiliation(s)
- Hongyun Tang
- Department of MCDB, University of Colorado Boulder, Boulder, CO 80309, USA; Key Laboratory of Growth Regulation and Transformation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, Zhejiang Province, China; Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
| | - Mingxue Cui
- Department of MCDB, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Min Han
- Department of MCDB, University of Colorado Boulder, Boulder, CO 80309, USA.
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6
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Davis L, Radman I, Goutou A, Tynan A, Baxter K, Xi Z, O'Shea JM, Chin JW, Greiss S. Precise optical control of gene expression in C. elegans using improved genetic code expansion and Cre recombinase. eLife 2021; 10:67075. [PMID: 34350826 PMCID: PMC8448529 DOI: 10.7554/elife.67075] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 08/04/2021] [Indexed: 11/13/2022] Open
Abstract
Synthetic strategies for optically controlling gene expression may enable the precise spatiotemporal control of genes in any combination of cells that cannot be targeted with specific promoters. We develop an improved genetic code expansion system in Caenorhabditis elegans and use it to create a photoactivatable Cre recombinase. We laser-activate Cre in single neurons within a bilaterally symmetric pair to selectively switch on expression of a loxP-controlled optogenetic channel in the targeted neuron. We use the system to dissect, in freely moving animals, the individual contributions of the mechanosensory neurons PLML/PLMR to the C. elegans touch response circuit, revealing distinct and synergistic roles for these neurons. We thus demonstrate how genetic code expansion and optical targeting can be combined to break the symmetry of neuron pairs and dissect behavioural outputs of individual neurons that cannot be genetically targeted. Animal behaviour and movement emerges from the stimulation of nerve cells that are connected together like a circuit. Researchers use various tools to investigate these neural networks in model organisms such as roundworms, fruit flies and zebrafish. The trick is to activate some nerve cells, but not others, so as to isolate their specific role within the neural circuit. One way to do this is to switch genes on or off in individual cells as a way to control their neuronal activity. This can be achieved by building a photocaged version of the enzyme Cre recombinase which is designed to target specific genes. The modified Cre recombinase contains an amino acid (the building blocks of proteins) that inactivates the enzyme. When the cell is illuminated with UV light, a part of the amino acid gets removed allowing Cre recombinase to turn on its target gene. However, cells do not naturally produce these photocaged amino acids. To overcome this, researchers can use a technology called genetic code expansion which provides cells with the tools they need to build proteins containing these synthetic amino acids. Although this technique has been used in live animals, its application has been limited due to the small amount of proteins it produces. Davis et al. therefore set out to improve the efficiency of genetic code expansion so that it can be used to study single nerve cells in freely moving roundworms. In the new system, named LaserTAC, individual cells are targeted with UV light that ‘uncages’ the Cre recombinase enzyme so it can switch on a gene for a protein that controls neuronal activity. Davis et al. used this approach to stimulate a pair of neurons sensitive to touch to see how this impacted the roundworm’s behaviour. This revealed that individual neurons within this pair contribute to the touch response in different ways. However, input from both neurons is required to produce a robust reaction. These findings show that the LaserTAC system can be used to manipulate gene activity in single cells, such as neurons, using light. It allows researchers to precisely control in which cells and when a given gene is switched on or off. Also, with the improved efficiency of the genetic code expansion, this technology could be used to modify proteins other than Cre recombinase and be applied to other artificial amino acids that have been developed in recent years.
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Affiliation(s)
- Lloyd Davis
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Inja Radman
- Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Angeliki Goutou
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ailish Tynan
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Kieran Baxter
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Zhiyan Xi
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jack M O'Shea
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jason W Chin
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Sebastian Greiss
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
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7
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Abstract
During multicellular organism development, complex structures are sculpted to form organs and tissues, which are maintained throughout adulthood. Many of these processes require cells to fuse with one another, or with themselves. These plasma membrane fusions merge endoplasmic cellular content across external, exoplasmic, space. In the nematode Caenorhabditis elegans, such cell fusions serve as a unique sculpting force, involved in the embryonic morphogenesis of the skin-like multinuclear hypodermal cells, but also in refining delicate structures, such as valve openings and the tip of the tail. During post-embryonic development, plasma membrane fusions continue to shape complex neuron structures and organs such as the vulva, while during adulthood fusion participates in cell and tissue repair. These processes rely on two fusion proteins (fusogens): EFF-1 and AFF-1, which are part of a broader family of structurally related membrane fusion proteins, encompassing sexual reproduction, viral infection, and tissue remodeling. The established capabilities of these exoplasmic fusogens are further expanded by new findings involving EFF-1 and AFF-1 in endocytic vesicle fission and phagosome sealing. Tight regulation by cell-autonomous and non-cell autonomous mechanisms orchestrates these diverse cell fusions at the correct place and time-these processes and their significance are discussed in this review.
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8
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Mao K, Breen P, Ruvkun G. Mitochondrial dysfunction induces RNA interference in C. elegans through a pathway homologous to the mammalian RIG-I antiviral response. PLoS Biol 2020; 18:e3000996. [PMID: 33264285 PMCID: PMC7735679 DOI: 10.1371/journal.pbio.3000996] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 12/14/2020] [Accepted: 11/09/2020] [Indexed: 12/27/2022] Open
Abstract
RNA interference (RNAi) is an antiviral pathway common to many eukaryotes that detects and cleaves foreign nucleic acids. In mammals, mitochondrially localized proteins such as mitochondrial antiviral signaling (MAVS), retinoic acid-inducible gene I (RIG-I), and melanoma differentiation-associated protein 5 (MDA5) mediate antiviral responses. Here, we report that mitochondrial dysfunction in Caenorhabditis elegans activates RNAi-directed silencing via induction of a pathway homologous to the mammalian RIG-I helicase viral response pathway. The induction of RNAi also requires the conserved RNA decapping enzyme EOL-1/DXO. The transcriptional induction of eol-1 requires DRH-1 as well as the mitochondrial unfolded protein response (UPRmt). Upon mitochondrial dysfunction, EOL-1 is concentrated into foci that depend on the transcription of mitochondrial RNAs that may form double-stranded RNA (dsRNA), as has been observed in mammalian antiviral responses. Enhanced RNAi triggered by mitochondrial dysfunction is necessary for the increase in longevity that is induced by mitochondrial dysfunction. Surveillance of mitochondrial dysfunction in the nematode Caenorhabditis elegans triggers the activation of an RNA interference pathway to mediate antiviral defense, in a manner homologous to the mammalian RIG-I helicase viral response pathway.
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Affiliation(s)
- Kai Mao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Peter Breen
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Gary Ruvkun
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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9
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Leveraging a gain-of-function allele of Caenorhabditis elegans paqr-1 to elucidate membrane homeostasis by PAQR proteins. PLoS Genet 2020; 16:e1008975. [PMID: 32750056 PMCID: PMC7428288 DOI: 10.1371/journal.pgen.1008975] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 08/14/2020] [Accepted: 07/01/2020] [Indexed: 12/12/2022] Open
Abstract
The C. elegans proteins PAQR-2 (a homolog of the human seven-transmembrane domain AdipoR1 and AdipoR2 proteins) and IGLR-2 (a homolog of the mammalian LRIG proteins characterized by a single transmembrane domain and the presence of immunoglobulin domains and leucine-rich repeats in their extracellular portion) form a complex that protects against plasma membrane rigidification by promoting the expression of fatty acid desaturases and the incorporation of polyunsaturated fatty acids into phospholipids, hence increasing membrane fluidity. In the present study, we leveraged a novel gain-of-function allele of PAQR-1, a PAQR-2 paralog, to carry out structure-function studies. We found that the transmembrane domains of PAQR-2 are responsible for its functional requirement for IGLR-2, that PAQR-1 does not require IGLR-2 but acts via the same pathway as PAQR-2, and that the divergent N-terminal cytoplasmic domains of the PAQR-1 and PAQR-2 proteins serve a regulatory function and may regulate access to the catalytic site of these proteins. We also show that overexpression of human AdipoR1 or AdipoR2 alone is sufficient to confer increased palmitic acid resistance in HEK293 cells, and thus act in a manner analogous to the PAQR-1 gain-of-function allele.
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10
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Chromatin Compaction by Small RNAs and the Nuclear RNAi Machinery in C. elegans. Sci Rep 2019; 9:9030. [PMID: 31227740 PMCID: PMC6588724 DOI: 10.1038/s41598-019-45052-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 05/28/2019] [Indexed: 11/25/2022] Open
Abstract
DNA is organized and compacted into higher-order structures in order to fit within nuclei and to facilitate gene regulation. Mechanisms by which higher order chromatin structures are established and maintained are poorly understood. In C. elegans, nuclear-localized small RNAs engage the nuclear RNAi machinery to regulate gene expression and direct the post-translational modification of histone proteins. Here we confirm a recent report suggesting that nuclear small RNAs initiate or maintain chromatin compaction states in C. elegans germ cells. Additionally, we show that experimentally provided small RNAs are sufficient to direct chromatin compaction and that this compaction requires the small RNA-binding Argonaute NRDE-3, the pre-mRNA associated factor NRDE-2, and the HP1-like protein HPL-2. Our results show that small RNAs, acting via the nuclear RNAi machinery and an HP1-like protein, are capable of driving chromatin compaction in C. elegans.
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11
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Brukman NG, Uygur B, Podbilewicz B, Chernomordik LV. How cells fuse. J Cell Biol 2019; 218:1436-1451. [PMID: 30936162 PMCID: PMC6504885 DOI: 10.1083/jcb.201901017] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 03/05/2019] [Accepted: 03/08/2019] [Indexed: 12/11/2022] Open
Abstract
Brukman et al. review cell–cell fusion mechanisms, focusing on the identity of the fusogens that mediate these processes and the regulation of their activities. Cell–cell fusion remains the least understood type of membrane fusion process. However, the last few years have brought about major advances in understanding fusion between gametes, myoblasts, macrophages, trophoblasts, epithelial, cancer, and other cells in normal development and in diseases. While different cell fusion processes appear to proceed via similar membrane rearrangements, proteins that have been identified as necessary and sufficient for cell fusion (fusogens) use diverse mechanisms. Some fusions are controlled by a single fusogen; other fusions depend on several proteins that either work together throughout the fusion pathway or drive distinct stages. Furthermore, some fusions require fusogens to be present on both fusing membranes, and in other fusions, fusogens have to be on only one of the membranes. Remarkably, some of the proteins that fuse cells also sculpt single cells, repair neurons, promote scission of endocytic vesicles, and seal phagosomes. In this review, we discuss the properties and diversity of the known proteins mediating cell–cell fusion and highlight their different working mechanisms in various contexts.
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Affiliation(s)
- Nicolas G Brukman
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Berna Uygur
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | | | - Leonid V Chernomordik
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
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12
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Choi S, Ambros V. The C. elegans heterochronic gene lin-28 coordinates the timing of hypodermal and somatic gonadal programs for hermaphrodite reproductive system morphogenesis. Development 2019; 146:dev164293. [PMID: 30745431 PMCID: PMC6432661 DOI: 10.1242/dev.164293] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 02/04/2019] [Indexed: 12/17/2022]
Abstract
C. elegans heterochronic genes determine the timing of expression of specific cell fates in particular stages of developing larvae. However, their broader roles in coordinating developmental events across diverse tissues have been less well investigated. Here, we show that loss of lin-28, a central heterochronic regulator of hypodermal development, causes reduced fertility associated with abnormal somatic gonadal morphology. In particular, the abnormal spermatheca-uterine valve morphology of lin-28(lf) hermaphrodites traps embryos in the spermatheca, which disrupts ovulation and causes embryonic lethality. The same genes that act downstream of lin-28 in the regulation of hypodermal developmental timing also act downstream of lin-28 in somatic gonadal morphogenesis and fertility. Importantly, we find that hypodermal expression, but not somatic gonadal expression, of lin-28 is sufficient for restoring normal somatic gonadal morphology in lin-28(lf) mutants. We propose that the abnormal somatic gonadal morphogenesis of lin-28(lf) hermaphrodites results from temporal discoordination between the accelerated hypodermal development and normally timed somatic gonadal development. Thus, our findings exemplify how a cell-intrinsic developmental timing program can also control proper development of other interacting tissues, presumably by cell non-autonomous signal(s). This article has an associated 'The people behind the papers' interview.
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Affiliation(s)
- Sungwook Choi
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Victor Ambros
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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13
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Flatt KM, Beshers C, Unal C, Cohen JD, Sundaram MV, Schroeder NE. Epidermal Remodeling in Caenorhabditis elegans Dauers Requires the Nidogen Domain Protein DEX-1. Genetics 2019; 211:169-183. [PMID: 30409788 PMCID: PMC6325711 DOI: 10.1534/genetics.118.301557] [Citation(s) in RCA: 10] [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: 08/29/2018] [Accepted: 10/29/2019] [Indexed: 01/23/2023] Open
Abstract
Phenotypic plasticity is a critical component of an organism's ability to thrive in a changing environment. The free-living nematode Caenorhabditis elegans adapts to unfavorable environmental conditions by pausing reproductive development and entering a stress-resistant larval stage known as dauer. The transition into dauer is marked by vast morphological changes, including remodeling of epidermis, neurons, and muscle. Although many of these dauer-specific traits have been described, the molecular basis of dauer-specific remodeling is still poorly understood. Here we show that the nidogen domain-containing protein DEX-1 facilitates stage-specific tissue remodeling during dauer morphogenesis. DEX-1 was previously shown to regulate sensory dendrite formation during embryogenesis. We find that DEX-1 is also required for proper remodeling of the stem cell-like epidermal seam cells. dex-1 mutant dauers lack distinct lateral cuticular alae during dauer and have increased sensitivity to sodium dodecyl sulfate. Furthermore, we find that DEX-1 is required for proper dauer mobility. We show that DEX-1 is secreted from the seam cells during dauer, but acts locally in a cell-autonomous manner. We find that dex-1 expression during dauer is regulated through DAF-16/FOXO-mediated transcriptional activation. Finally, we show that dex-1 acts with a family of zona pellucida domain-encoding genes to regulate dauer-specific epidermal remodeling. Taken together, our data indicate that DEX-1 is an extracellular matrix component that plays a central role in C. elegans epidermal remodeling during dauer.
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Affiliation(s)
- Kristen M Flatt
- Program in Neuroscience, University of Illinois at Urbana-Champaign, Illinois 61801-4730
| | - Caroline Beshers
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Illinois 61801-4730
| | - Cagla Unal
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Illinois 61801-4730
| | - Jennifer D Cohen
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6145
| | - Meera V Sundaram
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104-6145
| | - Nathan E Schroeder
- Program in Neuroscience, University of Illinois at Urbana-Champaign, Illinois 61801-4730
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Illinois 61801-4730
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14
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Kanzaki N, Tsai IJ, Tanaka R, Hunt VL, Liu D, Tsuyama K, Maeda Y, Namai S, Kumagai R, Tracey A, Holroyd N, Doyle SR, Woodruff GC, Murase K, Kitazume H, Chai C, Akagi A, Panda O, Ke HM, Schroeder FC, Wang J, Berriman M, Sternberg PW, Sugimoto A, Kikuchi T. Biology and genome of a newly discovered sibling species of Caenorhabditis elegans. Nat Commun 2018; 9:3216. [PMID: 30097582 PMCID: PMC6086898 DOI: 10.1038/s41467-018-05712-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 07/19/2018] [Indexed: 01/19/2023] Open
Abstract
A 'sibling' species of the model organism Caenorhabditis elegans has long been sought for use in comparative analyses that would enable deep evolutionary interpretations of biological phenomena. Here, we describe the first sibling species of C. elegans, C. inopinata n. sp., isolated from fig syconia in Okinawa, Japan. We investigate the morphology, developmental processes and behaviour of C. inopinata, which differ significantly from those of C. elegans. The 123-Mb C. inopinata genome was sequenced and assembled into six nuclear chromosomes, allowing delineation of Caenorhabditis genome evolution and revealing unique characteristics, such as highly expanded transposable elements that might have contributed to the genome evolution of C. inopinata. In addition, C. inopinata exhibits massive gene losses in chemoreceptor gene families, which could be correlated with its limited habitat area. We have developed genetic and molecular techniques for C. inopinata; thus C. inopinata provides an exciting new platform for comparative evolutionary studies.
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Affiliation(s)
- Natsumi Kanzaki
- Forestry and Forest Products Research Institute, Tsukuba, 305-8687, Japan
- Kansai Research Center, Forestry and Forest Products Research Institute, 68 Nagaikyutaroh, Momoyama, Fushimi, Kyoto, 612-0855, Japan
| | - Isheng J Tsai
- Biodiversity Research Center, Academia Sinica, Taipei city, 11529, Taiwan
| | - Ryusei Tanaka
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Vicky L Hunt
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Dang Liu
- Biodiversity Research Center, Academia Sinica, Taipei city, 11529, Taiwan
| | - Kenji Tsuyama
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Yasunobu Maeda
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Satoshi Namai
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Ryohei Kumagai
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Alan Tracey
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Nancy Holroyd
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Stephen R Doyle
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Gavin C Woodruff
- Forestry and Forest Products Research Institute, Tsukuba, 305-8687, Japan
- Department of Biology, Institute of Ecology and Evolution, University of Oregon, Eugene, OR, 97403-5289, USA
| | - Kazunori Murase
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Hiromi Kitazume
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Cynthia Chai
- HHMI and Division of Biology and Biological Engineering, Caltech, Pasadena, CA, 91125, USA
| | - Allison Akagi
- HHMI and Division of Biology and Biological Engineering, Caltech, Pasadena, CA, 91125, USA
| | - Oishika Panda
- Boyce Thompson Institute, and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Huei-Mien Ke
- Biodiversity Research Center, Academia Sinica, Taipei city, 11529, Taiwan
| | - Frank C Schroeder
- Boyce Thompson Institute, and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - John Wang
- Biodiversity Research Center, Academia Sinica, Taipei city, 11529, Taiwan
| | - Matthew Berriman
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Paul W Sternberg
- HHMI and Division of Biology and Biological Engineering, Caltech, Pasadena, CA, 91125, USA
| | - Asako Sugimoto
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.
| | - Taisei Kikuchi
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan.
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15
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Membrane Fluidity Is Regulated Cell Nonautonomously by Caenorhabditis elegans PAQR-2 and Its Mammalian Homolog AdipoR2. Genetics 2018; 210:189-201. [PMID: 29997234 PMCID: PMC6116961 DOI: 10.1534/genetics.118.301272] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 07/09/2018] [Indexed: 01/24/2023] Open
Abstract
The properties of cell membranes are determined mostly by the types of fatty acids that they contain. Bodhicharla et al. report that a key regulator of membrane fluidity, the PAQR-2/IGLR-2 protein complex... Maintenance of membrane properties is an essential aspect of cellular homeostasis of which the regulatory mechanisms remain mostly uncharacterized. In Caenorhabditis elegans, the PAQR-2 and IGLR-2 proteins act together as a plasma membrane sensor that responds to decreased fluidity by promoting fatty acid desaturation, hence restoring membrane fluidity. Here, we used mosaic analysis for paqr-2 and iglr-2, and tissue-specific paqr-2 expression, to show that membrane homeostasis is achieved cell nonautonomously. Specifically, we found that expression of paqr-2 in the hypodermis, gonad sheath cells, or intestine is sufficient to suppress systemic paqr-2 mutant phenotypes, including tail tip morphology, membrane fluidity in intestinal cells, cold and glucose intolerance, vitellogenin transport to the germline, germ cell development, and brood size. Finally, we show that the cell nonautonomous regulation of membrane homeostasis is conserved in human cells: HEK293 cells that express AdipoR2, a homolog of paqr-2, are able to normalize membrane fluidity in distant cells where AdipoR2 has been silenced. Finally, using C. elegans mutants and small interfering RNA against Δ9 stearoyl-CoA desaturase in HEK293 cells, we show that Δ9 desaturases are essential for the cell nonautonomous maintenance of membrane fluidity. We conclude that cells are able to share membrane components even when they are not in direct contact with each other, and that this contributes to the maintenance of membrane homeostasis in C. elegans and human cells.
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16
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Abstract
Cell-cell fusion is essential for fertilization and organ development. Dedicated proteins known as fusogens are responsible for mediating membrane fusion. However, until recently, these proteins either remained unidentified or were poorly understood at the mechanistic level. Here, we review how fusogens surmount multiple energy barriers to mediate cell-cell fusion. We describe how early preparatory steps bring membranes to a distance of ∼10 nm, while fusogens act in the final approach between membranes. The mechanical force exerted by cell fusogens and the accompanying lipidic rearrangements constitute the hallmarks of cell-cell fusion. Finally, we discuss the relationship between viral and eukaryotic fusogens, highlight a classification scheme regrouping a superfamily of fusogens called Fusexins, and propose new questions and avenues of enquiry.
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Affiliation(s)
- Javier M Hernández
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Benjamin Podbilewicz
- Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
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17
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Abstract
In the nematode Caenorhabditis elegans, RNA interference (RNAi) triggered by double-stranded RNA (dsRNA) spreads systemically to cause gene silencing throughout the organism and its progeny. We confirm that Caenorhabditis nematode SID-1 orthologs have dsRNA transport activity and demonstrate that the SID-1 paralog CHUP-1 does not transport dsRNA. Sequence comparison of these similar proteins, in conjunction with analysis of loss-of-function missense alleles, identifies several conserved 2–7 amino acid microdomains within the extracellular domain (ECD) that are important for dsRNA transport. Among these missense alleles, we identify and characterize a sid-1 allele, qt95, which causes tissue-specific silencing defects most easily explained as a systemic RNAi export defect. However, we conclude from genetic and biochemical analyses that sid-1(qt95) disrupts only import, and speculate that the apparent export defect is caused by the cumulative effect of sequentially impaired dsRNA import steps. Thus, consistent with previous studies, we fail to detect a requirement for sid-1 in dsRNA export, but demonstrate for the first time that SID-1 functions in the intestine to support environmental RNAi (eRNAi).
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18
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Cottee PA, Cole T, Schultz J, Hoang HD, Vibbert J, Han SM, Miller MA. The C. elegans VAPB homolog VPR-1 is a permissive signal for gonad development. Development 2017. [PMID: 28634273 PMCID: PMC5482997 DOI: 10.1242/dev.152207] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
VAMP/synaptobrevin-associated proteins (VAPs) contain an N-terminal major sperm protein domain (MSPd) that is associated with amyotrophic lateral sclerosis. VAPs have an intracellular housekeeping function, as well as an extracellular signaling function mediated by the secreted MSPd. Here we show that the C. elegans VAP homolog VPR-1 is essential for gonad development. vpr-1 null mutants are maternal effect sterile due to arrested gonadogenesis following embryo hatching. Somatic gonadal precursor cells and germ cells fail to proliferate fully and complete their respective differentiation programs. Maternal or zygotic vpr-1 expression is sufficient to induce gonadogenesis and fertility. Genetic mosaic and cell type-specific expression studies indicate that vpr-1 activity is important in the nervous system, germ line and intestine. VPR-1 acts in parallel to Notch signaling, a key regulator of germline stem cell proliferation and differentiation. Neuronal vpr-1 expression is sufficient for gonadogenesis induction during a limited time period shortly after hatching. These results support the model that the secreted VPR-1 MSPd acts at least in part on gonadal sheath cell precursors in L1 to early L2 stage hermaphrodites to permit gonadogenesis. Highlighted Article:vpr-1 null mutants are sterile upon hatching, a defect rescued by the expression of MSPd from almost any tissue except for the somatic gonad itself. See also the companion paper by Schultz et al.
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Affiliation(s)
- Pauline A Cottee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Tim Cole
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jessica Schultz
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Hieu D Hoang
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jack Vibbert
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Sung Min Han
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Michael A Miller
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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19
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Mikkonen E, Haglund C, Holmberg CI. Immunohistochemical analysis reveals variations in proteasome tissue expression in C. elegans. PLoS One 2017; 12:e0183403. [PMID: 28817671 PMCID: PMC5560697 DOI: 10.1371/journal.pone.0183403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 08/03/2017] [Indexed: 11/21/2022] Open
Abstract
The ubiquitin-proteasome system (UPS) plays a crucial part in normal cell function by mediating intracellular protein clearance. We have previously shown that UPS-mediated protein degradation varies in a cell type-specific manner in C. elegans. Here, we use formalin-fixed, paraffin-embedded C. elegans sections to enable studies on endogenous proteasome tissue expression. We show that the proteasome immunoreactivity pattern differs between cell types and within subcellular compartments in adult wild-type (N2) C. elegans. Interestingly, widespread knockdown of proteasome subunits by RNAi results in tissue-specific changes in proteasome expression instead of a uniform response. In addition, long-lived daf-2(e1370) mutants with impaired insulin/IGF-1 signaling (IIS) display similar proteasome tissue expression as aged-matched wild-type animals. Our study emphasizes the importance of alternate approaches to the commonly used whole animal lysate-based methods to detect changes in proteasome expression occurring at the sub-cellular, cell or tissue resolution level in a multicellular organism.
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Affiliation(s)
- Elisa Mikkonen
- Research Programs Unit, Translational Cancer Biology Program, University of Helsinki, Helsinki, Finland
| | - Caj Haglund
- Research Programs Unit, Translational Cancer Biology Program, University of Helsinki, Helsinki, Finland
- Department of Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Carina I. Holmberg
- Research Programs Unit, Translational Cancer Biology Program, University of Helsinki, Helsinki, Finland
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20
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Stress-Induced Sleep After Exposure to Ultraviolet Light Is Promoted by p53 in Caenorhabditis elegans. Genetics 2017; 207:571-582. [PMID: 28754659 DOI: 10.1534/genetics.117.300070] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 07/24/2017] [Indexed: 12/31/2022] Open
Abstract
Stress-induced sleep (SIS) in Caenorhabditis elegans is important for restoration of cellular homeostasis and is a useful model to study the function and regulation of sleep. SIS is triggered when epidermal growth factor (EGF) activates the ALA neuron, which then releases neuropeptides to promote sleep. To further understand this behavior, we established a new model of SIS using irradiation by ultraviolet C (UVC) light. While UVC irradiation requires ALA signaling and leads to a sleep state similar to that induced by heat and other stressors, it does not induce the proteostatic stress seen with heat exposure. Based on the known genotoxic effects of UVC irradiation, we tested two genes, atl-1 and cep-1, which encode proteins that act in the DNA damage response pathway. Loss-of-function mutants of atl-1 had no defect in UVC-induced SIS but a partial loss-of-function mutant of cep-1, gk138, had decreased movement quiescence following UVC irradiation. Germline ablation experiments and tissue-specific RNA interference experiments showed that cep-1 is required somatically in neurons for its effect on SIS. The cep-1(gk138) mutant suppressed body movement quiescence controlled by EGF, indicating that CEP-1 acts downstream or in parallel to ALA activation to promote quiescence in response to ultraviolet light.
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21
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Matsunaga Y, Hwang H, Franke B, Williams R, Penley M, Qadota H, Yi H, Morran LT, Lu H, Mayans O, Benian GM. Twitchin kinase inhibits muscle activity. Mol Biol Cell 2017; 28:1591-1600. [PMID: 28428253 PMCID: PMC5469603 DOI: 10.1091/mbc.e16-10-0707] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 04/04/2017] [Accepted: 04/11/2017] [Indexed: 01/03/2023] Open
Abstract
Muscles express giant polypeptides with kinase domains, but the in vivo significance of their catalytic activity has been unknown. Analysis of a mutant nematode that expresses the giant protein twitchin with a catalytically inactive kinase indicates that twitchin kinase inhibits muscle activity and is favored by selection. Muscle sarcomeres contain giant polypeptides composed of multiple immunoglobulin and fibronectin domains and one or two protein kinase domains. Although binding partners for a number of this family’s kinase domains have been identified, the catalytic necessity of these kinase domains remains unknown. In addition, various members of this kinase family are suspected pseudokinases with no or little activity. Here we address catalytic necessity for the first time, using the prototypic invertebrate representative twitchin (UNC-22) from Caenorhabditis elegans. In in vitro experiments, change of a conserved lysine (K) that is involved in ATP coordination to alanine (A) resulted in elimination of kinase activity without affecting the overall structure of the kinase domain. The same mutation, unc-22(sf21), was generated in the endogenous twitchin gene. The unc-22(sf21) worms have well-organized sarcomeres. However, unc-22(sf21) mutants move faster than wild-type worms and, by optogenetic experiments, contract more. Wild-type nematodes exhibited greater competitive fitness than unc-22(sf21) mutants. Thus the catalytic activity of twitchin kinase has a role in vivo, where it inhibits muscle activity and is likely maintained by selection.
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Affiliation(s)
- Yohei Matsunaga
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Hyundoo Hwang
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332
| | - Barbara Franke
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Rhys Williams
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - McKenna Penley
- Department of Biology, Emory University, Atlanta, GA 30322
| | - Hiroshi Qadota
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Hong Yi
- Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, GA 30322
| | - Levi T Morran
- Department of Biology, Emory University, Atlanta, GA 30322
| | - Hang Lu
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332
| | - Olga Mayans
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Guy M Benian
- Department of Pathology, Emory University, Atlanta, GA 30322
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22
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Lažetić V, Fay DS. Conserved Ankyrin Repeat Proteins and Their NIMA Kinase Partners Regulate Extracellular Matrix Remodeling and Intracellular Trafficking in Caenorhabditis elegans. Genetics 2017; 205:273-293. [PMID: 27799278 PMCID: PMC5223508 DOI: 10.1534/genetics.116.194464] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/28/2016] [Indexed: 12/27/2022] Open
Abstract
Molting is an essential developmental process in nematodes during which the epidermal apical extracellular matrix, the cuticle, is remodeled to accommodate further growth. Using genetic approaches, we identified a requirement for three conserved ankyrin repeat-rich proteins, MLT-2/ANKS6, MLT-3/ANKS3, and MLT-4/INVS, in Caenorhabditis elegans molting. Loss of mlt function resulted in severe defects in the ability of larvae to shed old cuticle and led to developmental arrest. Genetic analyses demonstrated that MLT proteins functionally cooperate with the conserved NIMA kinase family members NEKL-2/NEK8 and NEKL-3/NEK6/NEK7 to promote cuticle shedding. MLT and NEKL proteins were specifically required within the hyp7 epidermal syncytium, and fluorescently tagged mlt and nekl alleles were expressed in puncta within this tissue. Expression studies further showed that NEKL-2-MLT-2-MLT-4 and NEKL-3-MLT-3 colocalize within largely distinct assemblies of apical foci. MLT-2 and MLT-4 were required for the normal accumulation of NEKL-2 at the hyp7-seam cell boundary, and loss of mlt-2 caused abnormal nuclear accumulation of NEKL-2 Correspondingly, MLT-3, which bound directly to NEKL-3, prevented NEKL-3 nuclear localization, supporting the model that MLT proteins may serve as molecular scaffolds for NEKL kinases. Our studies additionally showed that the NEKL-MLT network regulates early steps in clathrin-mediated endocytosis at the apical surface of hyp7, which may in part account for molting defects observed in nekl and mlt mutants. This study has thus identified a conserved NEKL-MLT protein network that regulates remodeling of the apical extracellular matrix and intracellular trafficking, functions that may be conserved across species.
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Affiliation(s)
- Vladimir Lažetić
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, Wyoming 82071
| | - David S Fay
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, Wyoming 82071
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23
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Chi C, Ronai D, Than MT, Walker CJ, Sewell AK, Han M. Nucleotide levels regulate germline proliferation through modulating GLP-1/Notch signaling in C. elegans. Genes Dev 2016; 30:307-20. [PMID: 26833730 PMCID: PMC4743060 DOI: 10.1101/gad.275107.115] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this study, Chi et al. researched the link between known nutrient-sensing systems and reproductive programs. Using a model system in C. elegans, they show that a Notch signaling pathway senses the level of uridine/thymidine and controls germline proliferation, delineating a previously unknown nucleotide-sensing mechanism for controlling reproductivity. Animals alter their reproductive programs to accommodate changes in nutrient availability, yet the connections between known nutrient-sensing systems and reproductive programs are underexplored, and whether there is a mechanism that senses nucleotide levels to coordinate germline proliferation is unknown. We established a model system in which nucleotide metabolism is perturbed in both the nematode Caenorhabditis elegans (cytidine deaminases) and its food (Escherichia coli); when fed food with a low uridine/thymidine (U/T) level, germline proliferation is arrested. We provide evidence that this impact of U/T level on the germline is critically mediated by GLP-1/Notch and MPK-1/MAPK, known to regulate germline mitotic proliferation. This germline defect is suppressed by hyperactivation of glp-1 or disruption of genes downstream from glp-1 to promote meiosis but not by activation of the IIS or TORC1 pathways. Moreover, GLP-1 expression is post-transcriptionally modulated by U/T levels. Our results reveal a previously unknown nucleotide-sensing mechanism for controlling reproductivity.
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Affiliation(s)
- Congwu Chi
- Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Diana Ronai
- Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Minh T Than
- Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Cierra J Walker
- Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Aileen K Sewell
- Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Min Han
- Howard Hughes Medical Institute, Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, Colorado 80309, USA
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24
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Qadota H, Mayans O, Matsunaga Y, McMurry JL, Wilson KJ, Kwon GE, Stanford R, Deehan K, Tinley TL, Ngwa VM, Benian GM. The SH3 domain of UNC-89 (obscurin) interacts with paramyosin, a coiled-coil protein, in Caenorhabditis elegans muscle. Mol Biol Cell 2016; 27:1606-20. [PMID: 27009202 PMCID: PMC4865318 DOI: 10.1091/mbc.e15-09-0675] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 03/16/2016] [Accepted: 03/16/2016] [Indexed: 11/11/2022] Open
Abstract
UNC-89 is a giant polypeptide located at the sarcomeric M-line of Caenorhabditis elegans muscle. The human homologue is obscurin. To understand how UNC-89 is localized and functions, we have been identifying its binding partners. Screening a yeast two-hybrid library revealed that UNC-89 interacts with paramyosin. Paramyosin is an invertebrate-specific coiled-coil dimer protein that is homologous to the rod portion of myosin heavy chains and resides in thick filament cores. Minimally, this interaction requires UNC-89's SH3 domain and residues 294-376 of paramyosin and has a KD of ∼1.1 μM. In unc-89 loss-of-function mutants that lack the SH3 domain, paramyosin is found in accumulations. When the SH3 domain is overexpressed, paramyosin is mislocalized. SH3 domains usually interact with a proline-rich consensus sequence, but the region of paramyosin that interacts with UNC-89's SH3 is α-helical and lacks prolines. Homology modeling of UNC-89's SH3 suggests structural features that might be responsible for this interaction. The SH3-binding region of paramyosin contains a "skip residue," which is likely to locally unwind the coiled-coil and perhaps contributes to the binding specificity.
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Affiliation(s)
- Hiroshi Qadota
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Olga Mayans
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Yohei Matsunaga
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Jonathan L McMurry
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA 30144
| | - Kristy J Wilson
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Grace E Kwon
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Rachel Stanford
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Kevin Deehan
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Tina L Tinley
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Verra M Ngwa
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA 30144
| | - Guy M Benian
- Department of Pathology, Emory University, Atlanta, GA 30322
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25
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Svensk E, Devkota R, Ståhlman M, Ranji P, Rauthan M, Magnusson F, Hammarsten S, Johansson M, Borén J, Pilon M. Caenorhabditis elegans PAQR-2 and IGLR-2 Protect against Glucose Toxicity by Modulating Membrane Lipid Composition. PLoS Genet 2016; 12:e1005982. [PMID: 27082444 PMCID: PMC4833288 DOI: 10.1371/journal.pgen.1005982] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 03/16/2016] [Indexed: 12/19/2022] Open
Abstract
In spite of the worldwide impact of diabetes on human health, the mechanisms behind glucose toxicity remain elusive. Here we show that C. elegans mutants lacking paqr-2, the worm homolog of the adiponectin receptors AdipoR1/2, or its newly identified functional partner iglr-2, are glucose intolerant and die in the presence of as little as 20 mM glucose. Using FRAP (Fluorescence Recovery After Photobleaching) on living worms, we found that cultivation in the presence of glucose causes a decrease in membrane fluidity in paqr-2 and iglr-2 mutants and that genetic suppressors of this sensitivity act to restore membrane fluidity by promoting fatty acid desaturation. The essential roles of paqr-2 and iglr-2 in the presence of glucose are completely independent from daf-2 and daf-16, the C. elegans homologs of the insulin receptor and its downstream target FoxO, respectively. Using bimolecular fluorescence complementation, we also show that PAQR-2 and IGLR-2 interact on plasma membranes and thus may act together as a fluidity sensor that controls membrane lipid composition.
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Affiliation(s)
- Emma Svensk
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Ranjan Devkota
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Marcus Ståhlman
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Parmida Ranji
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Manish Rauthan
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Fredrik Magnusson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Sofia Hammarsten
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Maja Johansson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Jan Borén
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Marc Pilon
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
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Diapause is associated with a change in the polarity of secretion of insulin-like peptides. Nat Commun 2016; 7:10573. [PMID: 26838180 PMCID: PMC4742890 DOI: 10.1038/ncomms10573] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 12/30/2015] [Indexed: 12/19/2022] Open
Abstract
The insulin/IGF-1 signalling (IIS) pathway plays an important role in the regulation of larval diapause, the long-lived growth arrest state called dauer arrest, in Caenorhabditis elegans. In this nematode, 40 insulin-like peptides (ILPs) have been identified as putative ligands of the IIS pathway; however, it remains unknown how ILPs modulate larval diapause. Here we show that the secretory polarity of INS-35 and INS-7, which suppress larval diapause, is changed in the intestinal epithelial cells at larval diapause. These ILPs are secreted from the intestine into the body cavity during larval stages. In contrast, they are secreted into the intestinal lumen and degraded during dauer arrest, only to be secreted into the body cavity again when the worms return to developmental growth. The process that determines the secretory polarity of INS-35 and INS-7, thus, has an important role in the modulation of larval diapause. Insulin-like peptides INS-7 and INS-35 suppress larval diapause in Caenorhabditis elegans via unknown mechanism. Here, Matsunaga et al. show that the secretory polarity of both peptides changes in diapause, when these peptides are secreted into the intestinal lumen instead of the body cavity like in other larval stages.
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Shinn-Thomas JH, del Campo JJ, Wang J, Mohler WA. The EFF-1A Cytoplasmic Domain Influences Hypodermal Cell Fusions in C. elegans But Is Not Dependent on 14-3-3 Proteins. PLoS One 2016; 11:e0146874. [PMID: 26800457 PMCID: PMC4723337 DOI: 10.1371/journal.pone.0146874] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 12/25/2015] [Indexed: 12/19/2022] Open
Abstract
Background Regulatory and biophysical mechanisms of cell-cell fusion are largely unknown despite the fundamental requirement for fused cells in eukaryotic development. Only two cellular fusogens that are not of clear recent viral origin have been identified to date, both in nematodes. One of these, EFF-1, is necessary for most cell fusions in Caenorhabditis elegans. Unregulated EFF-1 expression causes lethality due to ectopic fusion between cells not developmentally programmed to fuse, highlighting the necessity of tight fusogen regulation for proper development. Identifying factors that regulate EFF-1 and its paralog AFF-1 could lead to discovery of molecular mechanisms that control cell fusion upstream of the action of a membrane fusogen. Bioinformatic analysis of the EFF-1A isoform’s predicted cytoplasmic domain (endodomain) previously revealed two motifs that have high probabilities of interacting with 14-3-3 proteins when phosphorylated. Mutation of predicted phosphorylation sites within these motifs caused measurable loss of eff-1 gene function in cell fusion in vivo. Moreover, a human 14-3-3 isoform bound to EFF-1::GFP in vitro. We hypothesized that the two 14-3-3 proteins in C. elegans, PAR-5 and FTT-2, may regulate either localization or fusion-inducing activity of EFF-1. Methodology/Principal Findings Timing of fusion events was slightly but significantly delayed in animals unable to produce full-length EFF-1A. Yet, mutagenesis and live imaging showed that phosphoserines in putative 14-3-3 binding sites are not essential for EFF-1::GFP accumulation at the membrane contact between fusion partner cells. Moreover, although the EFF-1A endodomain was required for normal rates of eff-1-dependent epidermal cell fusions, reduced levels of FTT-2 and PAR-5 did not visibly affect the function of wild-type EFF-1 in the hypodermis. Conclusions/Significance Deletion of the EFF-1A endodomain noticeably affects the timing of hypodermal cell fusions in vivo. However, prohibiting phosphorylation of candidate 14-3-3-binding sites does not impact localization of the fusogen. Hypodermal membrane fusion activity persists when 14-3-3 expression levels are reduced.
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Affiliation(s)
- Jessica H. Shinn-Thomas
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, MC-6403, 263 Farmington Avenue, Farmington, CT 06030–6403, United States of America
- * E-mail: (WAM); (JHST)
| | - Jacob J. del Campo
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, MC-6403, 263 Farmington Avenue, Farmington, CT 06030–6403, United States of America
| | - Jianjun Wang
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, MC-6403, 263 Farmington Avenue, Farmington, CT 06030–6403, United States of America
| | - William A. Mohler
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, MC-6403, 263 Farmington Avenue, Farmington, CT 06030–6403, United States of America
- * E-mail: (WAM); (JHST)
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28
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The Caenorhabditis elegans Ephrin EFN-4 Functions Non-cell Autonomously with Heparan Sulfate Proteoglycans to Promote Axon Outgrowth and Branching. Genetics 2015; 202:639-60. [PMID: 26645816 DOI: 10.1534/genetics.115.185298] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 12/02/2015] [Indexed: 01/21/2023] Open
Abstract
The Eph receptors and their cognate ephrin ligands play key roles in many aspects of nervous system development. These interactions typically occur within an individual tissue type, serving either to guide axons to their terminal targets or to define boundaries between the rhombomeres of the hindbrain. We have identified a novel role for the Caenorhabditis elegans ephrin EFN-4 in promoting primary neurite outgrowth in AIY interneurons and D-class motor neurons. Rescue experiments reveal that EFN-4 functions non-cell autonomously in the epidermis to promote primary neurite outgrowth. We also find that EFN-4 plays a role in promoting ectopic axon branching in a C. elegans model of X-linked Kallmann syndrome. In this context, EFN-4 functions non-cell autonomously in the body-wall muscle and in parallel with HS modification genes and HSPG core proteins. This is the first report of an epidermal ephrin providing a developmental cue to the nervous system.
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29
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Lagido C, McLaggan D, Glover LA. A Screenable In Vivo Assay for Mitochondrial Modulators Using Transgenic Bioluminescent Caenorhabditis elegans. J Vis Exp 2015:e53083. [PMID: 26554627 PMCID: PMC4692654 DOI: 10.3791/53083] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The multicellular model organism Caenorhabditis elegans is a small nematode of approximately 1 mm in size in adulthood that is genetically and experimentally tractable. It is economical and easy to culture and dispense in liquid medium which makes it well suited for medium-throughput screening. We have previously validated the use of transgenic luciferase expressing C. elegans strains to provide rapid in vivo assessment of the nematode’s ATP levels.1-3 Here we present the required materials and procedure to carry out bioassays with the bioluminescent C. elegans strains PE254 or PE255 (or any of their derivative strains). The protocol allows for in vivo detection of sublethal effects of drugs that may identify mitochondrial toxicity, as well as for in vivo detection of potential beneficial drug effects. Representative results are provided for the chemicals paraquat, rotenone, oxaloacetate and for four firefly luciferase inhibitory compounds. The methodology can be scaled up to provide a platform for screening drug libraries for compounds capable of modulating mitochondrial function. Pre-clinical evaluation of drug toxicity is often carried out on immortalized cancerous human cell lines which derive ATP mostly from glycolysis and are often tolerant of mitochondrial toxicants.4,5 In contrast, C. elegans depends on oxidative phosphorylation to sustain development into adulthood, drawing a parallel with humans and providing a unique opportunity for compound evaluation in the physiological context of a whole live multicellular organism.
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Affiliation(s)
| | | | - L Anne Glover
- Institute of Medical Sciences, University of Aberdeen
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30
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Maduro MF. 20 Years of unc-119 as a transgene marker. WORM 2015; 4:e1046031. [PMID: 26430568 PMCID: PMC4588520 DOI: 10.1080/21624054.2015.1046031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 04/08/2015] [Accepted: 04/23/2015] [Indexed: 01/01/2023]
Abstract
This fall marks 20 years since the cloning of unc-119 was reported. Despite having a strong phenotype that makes animals somewhat difficult to grow and handle, unc-119 mutant rescue has become one of the most frequently-used markers for C. elegans transformation. In this Commentary, I describe the history of how unc-119 rescue traveled through the worm community, contributing to the development of transgene methods in C. elegans.
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Affiliation(s)
- Morris F Maduro
- Biology Department; University of California, Riverside ; Riverside, CA USA
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31
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Kelley M, Yochem J, Krieg M, Calixto A, Heiman MG, Kuzmanov A, Meli V, Chalfie M, Goodman MB, Shaham S, Frand A, Fay DS. FBN-1, a fibrillin-related protein, is required for resistance of the epidermis to mechanical deformation during C. elegans embryogenesis. eLife 2015; 4. [PMID: 25798732 PMCID: PMC4395870 DOI: 10.7554/elife.06565] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/20/2015] [Indexed: 12/19/2022] Open
Abstract
During development, biomechanical forces contour the body and provide shape to internal organs. Using genetic and molecular approaches in combination with a FRET-based tension sensor, we characterized a pulling force exerted by the elongating pharynx (foregut) on the anterior epidermis during C. elegans embryogenesis. Resistance of the epidermis to this force and to actomyosin-based circumferential constricting forces is mediated by FBN-1, a ZP domain protein related to vertebrate fibrillins. fbn-1 was required specifically within the epidermis and FBN-1 was expressed in epidermal cells and secreted to the apical surface as a putative component of the embryonic sheath. Tiling array studies indicated that fbn-1 mRNA processing requires the conserved alternative splicing factor MEC-8/RBPMS. The conserved SYM-3/FAM102A and SYM-4/WDR44 proteins, which are linked to protein trafficking, function as additional components of this network. Our studies demonstrate the importance of the apical extracellular matrix in preventing mechanical deformation of the epidermis during development. DOI:http://dx.doi.org/10.7554/eLife.06565.001 For an animal embryo to develop, its cells must organize themselves into tissues and organs. For example, skin and the lining of internal organs—such as the lungs and gut—are made from cells called epithelial cells, which are tightly linked to form flat sheets. In a microscopic worm called Caenorhabditis elegans, the outermost layer of epithelial cells (called the epidermis) forms over the surface of the embryo early on in embryonic development. Shortly afterwards, the embryonic epidermis experiences powerful contractions along the surface of the embryo. The force generated by these contractions converts the embryo from an oval shape to a roughly cylindrical form. These contractions also squeeze the internal tissues and organs, which correspondingly elongate along with the epidermis. It has been known for decades that such ‘mechanical’ forces are important for the normal development of embryos. However, it remains poorly understood how these forces generate tissues and organs of the proper shape—partly because it is difficult to measure forces in living embryos. It is also not clear how the mechanical properties of specific tissues are controlled. Now, Kelley, Yochem, Krieg et al. have analyzed the development of C. elegans' embryos and discovered a novel mechanical interplay between the feeding organ (called the pharynx) and the worm's epidermis. The experiments involved studying several mutant worms that perturb epidermal contractions and disrupt the attachment of the pharynx to the epidermis. These studies suggested that the pharynx exerts a strong inward pulling force on the epidermis during development. Using recently developed methods, Kelley, Yochem, Krieg et al. then measured mechanical forces within intact worm embryos and demonstrated that greater forces were experienced in cells that were being pulled by the pharynx. Kelley, Yochem, Krieg et al. further analyzed how the epidermis normally resists this pulling force from the pharynx and implicated a protein called FBN-1. This worm protein is structurally related to a human protein that is affected in people with a disorder called Marfan Syndrome. Worm embryos without the FBN-1 protein become severely deformed because they are unable to withstand mechanical forces at the epidermis. FBN-1 is normally synthesized and then transported to the outside of the worm embryo by epidermal cells, where it is thought to assemble into a meshwork of long fibers. This provides a strong scaffold that attaches to the epidermis to prevent the epidermis from undergoing excessive deformation while it experiences mechanical forces. The work of Kelley, Yochem, Krieg et al. provides an opportunity to understand how FBN-1 and other fiber-forming proteins are produced and transported to the cell surface. Moreover, these findings may have implications for human diseases and birth defects that result from an inability of tissues to respond appropriately to mechanical forces. DOI:http://dx.doi.org/10.7554/eLife.06565.002
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Affiliation(s)
- Melissa Kelley
- Department of Molecular Biology, University of Wyoming, Laramie, United States
| | - John Yochem
- Department of Molecular Biology, University of Wyoming, Laramie, United States
| | - Michael Krieg
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, United States
| | - Andrea Calixto
- Department of Biological Sciences, Columbia University, New York, United States
| | - Maxwell G Heiman
- Department of Genetics, Harvard Medical School, Boston Children's Hospital, Boston, United States
| | - Aleksandra Kuzmanov
- Department of Molecular Biology, University of Wyoming, Laramie, United States
| | - Vijaykumar Meli
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - Martin Chalfie
- Department of Biological Sciences, Columbia University, New York, United States
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, United States
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Alison Frand
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, United States
| | - David S Fay
- Department of Molecular Biology, University of Wyoming, Laramie, United States
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32
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Yochem J, Lažetić V, Bell L, Chen L, Fay D. C. elegans NIMA-related kinases NEKL-2 and NEKL-3 are required for the completion of molting. Dev Biol 2015; 398:255-66. [PMID: 25523392 PMCID: PMC4314388 DOI: 10.1016/j.ydbio.2014.12.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 11/29/2014] [Accepted: 12/04/2014] [Indexed: 12/20/2022]
Abstract
Caenorhabditis elegans molting is a process during which the apical extracellular matrix of the epidermis, the cuticle, is remodeled through a process of degradation and re-synthesis. Using a genetic approach, we identified nekl-3 as essential for the completion of molting. NEKL-3 is highly similar to the mammalian NEK kinase family members NEK6 and NEK7. Animals homozygous for a hypomorphic mutation in nekl-3, sv3, had a novel molting defect in which the central body region, but not the head or tail, was unable to shed the old cuticle. In contrast, a null mutation in nekl-3, gk506, led to complete enclosure within the old cuticle. nekl-2, which is most similar to mammalian NEK8, was also essential for molting. Mosaic analyses demonstrated that NEKL-2 and NEKL-3 were specifically required within the large epidermal syncytium, hyp7, to facilitate molting. Consistent with this, NEKL-2 and NEKL-3 were expressed at the apical surface of hyp7 where they localized to small spheres or tubular structures. Inhibition of nekl-2, but not nekl-3, led to the mislocalization of LRP-1/megalin, a cell surface receptor for low-density lipoprotein (LDL)-binding proteins. In addition, nekl-2 inhibition led to the mislocalization of several other endosome-associated proteins. Notably, LRP-1 acts within hyp7 to facilitate completion of molting, suggesting at least one mechanism by which NEKL-2 may influence molting. Notably, our studies failed to reveal a requirement for NEKL-2 or NEKL-3 in cell division, a function reported for several mammalian NEKs including NEK6 and NEK7. Our findings provide the first genetic and in vivo evidence for a role of NEK family members in endocytosis, which may be evolutionarily conserved.
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Affiliation(s)
- John Yochem
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY 82071, United States; Department of Genetics, Cell Biology, and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - Vladimir Lažetić
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY 82071, United States
| | - Leslie Bell
- Department of Genetics, Cell Biology, and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - Lihsia Chen
- Department of Genetics, Cell Biology, and Development and the Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - David Fay
- Department of Molecular Biology, College of Agriculture and Natural Resources, University of Wyoming, Laramie, WY 82071, United States.
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Opperman K, Moseley-Alldredge M, Yochem J, Bell L, Kanayinkal T, Chen L. A novel nondevelopmental role of the sax-7/L1CAM cell adhesion molecule in synaptic regulation in Caenorhabditis elegans. Genetics 2015; 199:497-509. [PMID: 25488979 PMCID: PMC4317657 DOI: 10.1534/genetics.114.169581] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 12/02/2014] [Indexed: 01/25/2023] Open
Abstract
The L1CAM family of cell adhesion molecules is a conserved set of single-pass transmembrane proteins that play diverse roles required for proper nervous system development and function. Mutations in L1CAMs can cause the neurological L1 syndrome and are associated with autism and neuropsychiatric disorders. L1CAM expression in the mature nervous system suggests additional functions besides the well-characterized developmental roles. In this study, we demonstrate that the gene encoding the Caenorhabditis elegans L1CAM, sax-7, genetically interacts with gtl-2, as well as with unc-13 and rab-3, genes that function in neurotransmission. These sax-7 genetic interactions result in synthetic phenotypes that are consistent with abnormal synaptic function. Using an inducible sax-7 expression system and pharmacological reagents that interfere with cholinergic transmission, we uncovered a previously uncharacterized nondevelopmental role for sax-7 that impinges on synaptic function.
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Affiliation(s)
- Karla Opperman
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Melinda Moseley-Alldredge
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455 Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota 55455
| | - John Yochem
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Leslie Bell
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Tony Kanayinkal
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455
| | - Lihsia Chen
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455 Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota 55455
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34
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Drake M, Furuta T, Man KS, Gonzalez G, Liu B, Kalia A, Ladbury J, Fire AZ, Skeath JB, Arur S. A requirement for ERK-dependent Dicer phosphorylation in coordinating oocyte-to-embryo transition in C. elegans. Dev Cell 2014; 31:614-28. [PMID: 25490268 PMCID: PMC4261158 DOI: 10.1016/j.devcel.2014.11.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 08/12/2014] [Accepted: 11/04/2014] [Indexed: 02/03/2023]
Abstract
Signaling pathways and small RNAs direct diverse cellular events, but few examples are known of defined signaling pathways directly regulating small RNA biogenesis. We show that ERK phosphorylates Dicer on two conserved residues in its RNase IIIb and double-stranded RNA (dsRNA)-binding domains and that phosphorylation of these residues is necessary and sufficient to trigger Dicer's nuclear translocation in worms, mice, and human cells. Phosphorylation of Dicer on either site inhibits Dicer function in the female germline and dampens small RNA repertoire. Our data demonstrate that ERK phosphorylates and inhibits Dicer during meiosis I for oogenesis to proceed normally in Caenorhabditis elegans and that this inhibition is released before fertilization for embryogenesis to proceed normally. The conserved Dicer residues, their phosphorylation by ERK, and the consequences of the resulting modifications implicate an ERK-Dicer nexus as a fundamental component of the oocyte-to-embryo transition and an underlying mechanism coupling extracellular cues to small RNA production.
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Affiliation(s)
- Melanie Drake
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Tokiko Furuta
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Kin Suen Man
- Department of Biochemistry and Molecular Biology, UT MD Anderson Cancer Center, Houston, TX, 77030, USA,Graduate School of Biomedical Sciences, Houston, TX, 77030, USA
| | - Gabriel Gonzalez
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX, 77030, USA,Graduate School of Biomedical Sciences, Houston, TX, 77030, USA
| | - Bin Liu
- Center for Genetics and Genomics, UT MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Awdhesh Kalia
- Graduate Program in Diagnostic Genetics, School of Health Professions, UT MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - John Ladbury
- Department of Biochemistry and Molecular Biology, UT MD Anderson Cancer Center, Houston, TX, 77030, USA,Graduate School of Biomedical Sciences, Houston, TX, 77030, USA
| | - Andrew Z. Fire
- Department of Pathology and Genetics, Stanford University, Stanford, CA, 94305, USA
| | - James B Skeath
- Department of Genetics, Washington University School of Medicine, Scott Avenue, Saint Louis, MO, 63110, USA
| | - Swathi Arur
- Department of Genetics, UT MD Anderson Cancer Center, Houston, TX, 77030, USA,Graduate School of Biomedical Sciences, Houston, TX, 77030, USA,Center for Genetics and Genomics, UT MD Anderson Cancer Center, Houston, TX, 77030, USA,Address correspondence to: Swathi Arur, Ph.D, Department of Genetics, Unit 1010, UT MD Anderson Cancer Center, Houston, 77030, Phone: 713-745-8424,
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35
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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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36
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Alexander AG, Marfil V, Li C. Use of Caenorhabditis elegans as a model to study Alzheimer's disease and other neurodegenerative diseases. Front Genet 2014; 5:279. [PMID: 25250042 PMCID: PMC4155875 DOI: 10.3389/fgene.2014.00279] [Citation(s) in RCA: 202] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 07/31/2014] [Indexed: 12/12/2022] Open
Abstract
Advances in research and technology has increased our quality of life, allowed us to combat diseases, and achieve increased longevity. Unfortunately, increased longevity is accompanied by a rise in the incidences of age-related diseases such as Alzheimer’s disease (AD). AD is the sixth leading cause of death, and one of the leading causes of dementia amongst the aged population in the USA. It is a progressive neurodegenerative disorder, characterized by the prevalence of extracellular Aβ plaques and intracellular neurofibrillary tangles, derived from the proteolysis of the amyloid precursor protein (APP) and the hyperphosphorylation of microtubule-associated protein tau, respectively. Despite years of extensive research, the molecular mechanisms that underlie the pathology of AD remain unclear. Model organisms, such as the nematode, Caenorhabditis elegans, present a complementary approach to addressing these questions. C. elegans has many advantages as a model system to study AD and other neurodegenerative diseases. Like their mammalian counterparts, they have complex biochemical pathways, most of which are conserved. Genes in which mutations are correlated with AD have counterparts in C. elegans, including an APP-related gene, apl-1, a tau homolog, ptl-1, and presenilin homologs, such as sel-12 and hop-1. Since the neuronal connectivity in C. elegans has already been established, C. elegans is also advantageous in modeling learning and memory impairments seen during AD. This article addresses the insights C. elegans provide in studying AD and other neurodegenerative diseases. Additionally, we explore the advantages and drawbacks associated with using this model.
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Affiliation(s)
- Adanna G Alexander
- Department of Biology, City College of New York New York, NY, USA ; Department of Biology, The Graduate Center, City University of New York New York, NY, USA
| | - Vanessa Marfil
- Department of Biology, City College of New York New York, NY, USA
| | - Chris Li
- Department of Biology, City College of New York New York, NY, USA ; Department of Biology, The Graduate Center, City University of New York New York, NY, USA
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37
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Armenti ST, Chan E, Nance J. Polarized exocyst-mediated vesicle fusion directs intracellular lumenogenesis within the C. elegans excretory cell. Dev Biol 2014; 394:110-21. [PMID: 25102190 DOI: 10.1016/j.ydbio.2014.07.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 07/08/2014] [Accepted: 07/26/2014] [Indexed: 12/18/2022]
Abstract
Lumenogenesis of small seamless tubes occurs through intracellular membrane growth and directed vesicle fusion events. Within the Caenorhabditis elegans excretory cell, which forms seamless intracellular tubes (canals) that mediate osmoregulation, lumens grow in length and diameter when vesicles fuse with the expanding lumenal surface. Here, we show that lumenal vesicle fusion depends on the small GTPase RAL-1, which localizes to vesicles and acts through the exocyst vesicle-tethering complex. Loss of either the exocyst or RAL-1 prevents excretory canal lumen extension. Within the excretory canal and other polarized cells, the exocyst co-localizes with the PAR polarity proteins PAR-3, PAR-6 and PKC-3. Using early embryonic cells to determine the functional relationships between the exocyst and PAR proteins, we show that RAL-1 recruits the exocyst to the membrane, while PAR proteins concentrate membrane-localized exocyst proteins to a polarized domain. These findings reveal that RAL-1 and the exocyst direct the polarized vesicle fusion events required for intracellular lumenogenesis of the excretory cell, suggesting mechanistic similarities in the formation of topologically distinct multicellular and intracellular lumens.
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Affiliation(s)
- Stephen T Armenti
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA; Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Emily Chan
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA; Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Jeremy Nance
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA; Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA.
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The Nesprin family member ANC-1 regulates synapse formation and axon termination by functioning in a pathway with RPM-1 and β-Catenin. PLoS Genet 2014; 10:e1004481. [PMID: 25010424 PMCID: PMC4091705 DOI: 10.1371/journal.pgen.1004481] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 05/16/2014] [Indexed: 01/08/2023] Open
Abstract
Mutations in Nesprin-1 and 2 (also called Syne-1 and 2) are associated with numerous diseases including autism, cerebellar ataxia, cancer, and Emery-Dreifuss muscular dystrophy. Nesprin-1 and 2 have conserved orthologs in flies and worms called MSP-300 and abnormal nuclear Anchorage 1 (ANC-1), respectively. The Nesprin protein family mediates nuclear and organelle anchorage and positioning. In the nervous system, the only known function of Nesprin-1 and 2 is in regulation of neurogenesis and neural migration. It remains unclear if Nesprin-1 and 2 regulate other functions in neurons. Using a proteomic approach in C. elegans, we have found that ANC-1 binds to the Regulator of Presynaptic Morphology 1 (RPM-1). RPM-1 is part of a conserved family of signaling molecules called Pam/Highwire/RPM-1 (PHR) proteins that are important regulators of neuronal development. We have found that ANC-1, like RPM-1, regulates axon termination and synapse formation. Our genetic analysis indicates that ANC-1 functions via the β-catenin BAR-1, and the ANC-1/BAR-1 pathway functions cell autonomously, downstream of RPM-1 to regulate neuronal development. Further, ANC-1 binding to the nucleus is required for its function in axon termination and synapse formation. We identify variable roles for four different Wnts (LIN-44, EGL-20, CWN-1 and CWN-2) that function through BAR-1 to regulate axon termination. Our study highlights an emerging, broad role for ANC-1 in neuronal development, and unveils a new and unexpected mechanism by which RPM-1 functions. The molecular mechanisms that underpin synapse formation and axon termination are central to forming a functional, fully connected nervous system. The PHR proteins are important regulators of neuronal development that function in axon outgrowth and termination, as well as synapse formation. Here we describe the discovery of a novel, conserved pathway that is positively regulated by the C. elegans PHR protein, RPM-1. This pathway is composed of RPM-1, ANC-1 (a Nesprin family protein), and BAR-1 (a canonical β-catenin). Nesprins, such as ANC-1, regulate nuclear anchorage and positioning in multinuclear cells. We now show that in neurons, ANC-1 regulates neuronal development by positively regulating BAR-1. Thus, Nesprins are multi-functional proteins that act through β-catenin to regulate neuronal development, and link the nucleus to the actin cytoskeleton in order to mediate nuclear anchorage and positioning in multi-nuclear cells.
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Abstract
PHA-1 encodes a cytoplasmic protein that is required for embryonic morphogenesis and attachment of the foregut (pharynx) to the mouth (buccal capsule). Previous reports have in some cases suggested that PHA-1 is essential for the differentiation of most or all pharyngeal cell types. By performing mosaic analysis with a recently acquired pha-1 null mutation (tm3671), we found that PHA-1 is not required within most or all pharyngeal cells for their proper specification, differentiation, or function. Rather, our evidence suggests that PHA-1 acts in the arcade or anterior epithelial cells of the pharynx to promote attachment of the pharynx to the future buccal capsule. In addition, PHA-1 appears to be required in the epidermis for embryonic morphogenesis, in the excretory system for osmoregulation, and in the somatic gonad for normal ovulation and fertility. PHA-1 activity is also required within at least a subset of intestinal cells for viability. To better understand the role of PHA-1 in the epidermis, we analyzed several apical junction markers in pha-1(tm3671) homozygous embryos. PHA-1 regulates the expression of several components of two apical junction complexes including AJM-1–DLG-1/discs large complex and the classical cadherin–catenin complex, which may account for the role of PHA-1 in embryonic morphogenesis.
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40
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Fenker KE, Hansen AA, Chong CA, Jud MC, Duffy BA, Norton JP, Hansen JM, Stanfield GM. SLC6 family transporter SNF-10 is required for protease-mediated activation of sperm motility in C. elegans. Dev Biol 2014; 393:171-82. [PMID: 24929237 DOI: 10.1016/j.ydbio.2014.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 05/28/2014] [Accepted: 06/03/2014] [Indexed: 11/18/2022]
Abstract
Motility of sperm is crucial for their directed migration to the egg. The acquisition and modulation of motility are regulated to ensure that sperm move when and where needed, thereby promoting reproductive success. One specific example of this phenomenon occurs during differentiation of the ameboid sperm of Caenorhabditis elegans as they activate from a round spermatid to a mature, crawling spermatozoon. Sperm activation is regulated by redundant pathways to occur at a specific time and place for each sex. Here, we report the identification of the solute carrier 6 (SLC6) transporter protein SNF-10 as a key regulator of C. elegans sperm activation in response to male protease activation signals. We find that SNF-10 is present in sperm and is required for activation by the male but not by the hermaphrodite. Loss of both snf-10 and a hermaphrodite activation factor render sperm completely insensitive to activation. Using in vitro assays, we find that snf-10 mutant sperm show a specific deficit in response to protease treatment but not to other activators. Prior to activation, SNF-10 is present in the plasma membrane, where it represents a strong candidate to receive signals that lead to subcellular morphogenesis. After activation, it shows polarized localization to the cell body region that is dependent on membrane fusions mediated by the dysferlin FER-1. Our discovery of snf-10 offers insight into the mechanisms differentially employed by the two sexes to accomplish the common goal of producing functional sperm, as well as how the physiology of nematode sperm may be regulated to control motility as it is in mammals.
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Affiliation(s)
- Kristin E Fenker
- Department of Human Genetics, University of Utah, 15 North 2030 East, Room 6110B, Salt Lake City, UT 84112, USA
| | - Angela A Hansen
- Department of Human Genetics, University of Utah, 15 North 2030 East, Room 6110B, Salt Lake City, UT 84112, USA
| | - Conrad A Chong
- Department of Human Genetics, University of Utah, 15 North 2030 East, Room 6110B, Salt Lake City, UT 84112, USA
| | - Molly C Jud
- Department of Human Genetics, University of Utah, 15 North 2030 East, Room 6110B, Salt Lake City, UT 84112, USA
| | - Brittany A Duffy
- Department of Human Genetics, University of Utah, 15 North 2030 East, Room 6110B, Salt Lake City, UT 84112, USA
| | - J Paul Norton
- Department of Human Genetics, University of Utah, 15 North 2030 East, Room 6110B, Salt Lake City, UT 84112, USA
| | - Jody M Hansen
- Department of Human Genetics, University of Utah, 15 North 2030 East, Room 6110B, Salt Lake City, UT 84112, USA
| | - Gillian M Stanfield
- Department of Human Genetics, University of Utah, 15 North 2030 East, Room 6110B, Salt Lake City, UT 84112, USA.
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McKnight K, Hoang HD, Prasain JK, Brown N, Vibbert J, Hollister KA, Moore R, Ragains JR, Reese J, Miller MA. Neurosensory perception of environmental cues modulates sperm motility critical for fertilization. Science 2014; 344:754-7. [PMID: 24833393 DOI: 10.1126/science.1250598] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Environmental exposures affect gamete function and fertility, but the mechanisms are poorly understood. Here, we show that pheromones sensed by ciliated neurons in the Caenorhabditis elegans nose alter the lipid microenvironment within the oviduct, thereby affecting sperm motility. In favorable environments, pheromone-responsive sensory neurons secrete a transforming growth factor-β ligand called DAF-7, which acts as a neuroendocrine factor that stimulates prostaglandin-endoperoxide synthase [cyclooxygenase (Cox)]-independent prostaglandin synthesis in the ovary. Oocytes secrete F-class prostaglandins that guide sperm toward them. These prostaglandins are also synthesized in Cox knockout mice, raising the possibility that similar mechanisms exist in other animals. Our data indicate that environmental cues perceived by the female nervous system affect sperm function.
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Affiliation(s)
- Katherine McKnight
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Hieu D Hoang
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jeevan K Prasain
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Naoko Brown
- Department of Pediatrics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jack Vibbert
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Kyle A Hollister
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Ray Moore
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Justin R Ragains
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Jeff Reese
- Department of Pediatrics, Vanderbilt University, Nashville, TN 37232, USA. Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Michael A Miller
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Qadota H, Luo Y, Matsunaga Y, Park AS, Gernert KM, Benian GM. Suppressor mutations suggest a surface on PAT-4 (Integrin-linked Kinase) that interacts with UNC-112 (Kindlin). J Biol Chem 2014; 289:14252-62. [PMID: 24692564 PMCID: PMC4022890 DOI: 10.1074/jbc.m114.556308] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/20/2014] [Indexed: 11/06/2022] Open
Abstract
Caenorhabditis elegans striated muscle cells attach to basement membrane and transmit the force of muscle contraction through integrin adhesion complexes. The cytoplasmic tail of β-integrin (PAT-3) is associated with a conserved four-protein complex that includes UNC-112 (kindlin), PAT-4 (integrin-linked kinase), PAT-6 (α-parvin/actopaxin), and UNC-97 (PINCH). The proper localization of UNC-112 to muscle integrin adhesion sites requires PAT-4. A recent report (Qadota, H., Moerman, D. G., and Benian, G. M. (2012) A molecular mechanism for the requirement of PAT-4 (integrin-linked kinase (ILK)) for the localization of UNC-112 (kindlin) to integrin adhesion sites. J. Biol. Chem. 287, 28537-28551) suggests a possible molecular mechanism for this requirement: that UNC-112 exists in closed inactive and open active conformations, and conversion to the open active form is promoted by binding to PAT-4 (ILK). Previously, we also reported identification of a single missense mutation in UNC-112, D382V, which abolishes both binding to PAT-4 and normal localization to integrin adhesion sites in vivo. In this report, we describe isolation and characterization of PAT-4 missense mutations that permit binding with UNC-112 D382V and place nine affected residues on a homology model of PAT-4. These nine residues cluster in two regions on the surface of PAT-4, do not overlap the likely binding surface for PAT-6 (α-parvin), and therefore may reside along the interaction surface of PAT-4 for UNC-112 (kindlin). We also show that one of these PAT-4 mutations restores the ability of UNC-112 D382V to localize to integrin adhesions and participate in complex formation.
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Affiliation(s)
- Hiroshi Qadota
- From the Department of Pathology, Emory University, Atlanta, Georgia 30322 and
| | - Yating Luo
- From the Department of Pathology, Emory University, Atlanta, Georgia 30322 and
| | - Yohei Matsunaga
- From the Department of Pathology, Emory University, Atlanta, Georgia 30322 and
| | - Angela S Park
- From the Department of Pathology, Emory University, Atlanta, Georgia 30322 and
| | - Kim M Gernert
- the Biomolecular Computing Resource, Emory University, Atlanta, Georgia 30322
| | - Guy M Benian
- From the Department of Pathology, Emory University, Atlanta, Georgia 30322 and
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43
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The PAF1 complex is involved in embryonic epidermal morphogenesis in Caenorhabditis elegans. Dev Biol 2014; 391:43-53. [PMID: 24721716 DOI: 10.1016/j.ydbio.2014.04.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 03/29/2014] [Accepted: 04/02/2014] [Indexed: 11/21/2022]
Abstract
The PAF1 complex (PAF1C) is an evolutionarily conserved protein complex involved in transcriptional regulation and chromatin remodeling. How the PAF1C is involved in animal development is still not well understood. Here, we report that, in the nematode Caenorhabditis elegans, the PAF1C is involved in epidermal morphogenesis in late embryogenesis. From an RNAi screen we identified the C. elegans ortholog of a component of the PAF1C, CTR-9, as a gene whose depletion caused various defects during embryonic epidermal morphogenesis, including epidermal cell positioning, ventral enclosure and epidermal elongation. RNAi of orthologs of other four components of the PAF1C (PAFO-1, LEO-1, CDC-73 and RTFO-1) caused similar epidermal defects. In these embryos, whereas the number and cell fate determination of epidermal cells were apparently unaffected, their position and shape were severely disorganized. PAFO-1::mCherry, mCherry::LEO-1 and GFP::RTFO-1 driven by the authentic promoters were detected in the nuclei of a wide range of cells. Nuclear localization of GFP::RTFO-1 was independent of other PAF1C components, while PAFO-1::mCherry and mCherry::LEO-1 dependent on other components except RTFO-1. Epidermis-specific expression of mCherry::LEO-1 rescued embryonic lethality of the leo-1 deletion mutant. Thus, although the PAF1C is universally expressed in C. elegans embryos, its epidermal function is crucial for the viability of this animal.
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Firnhaber C, Hammarlund M. Neuron-specific feeding RNAi in C. elegans and its use in a screen for essential genes required for GABA neuron function. PLoS Genet 2013; 9:e1003921. [PMID: 24244189 PMCID: PMC3820814 DOI: 10.1371/journal.pgen.1003921] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 09/11/2013] [Indexed: 11/18/2022] Open
Abstract
Forward genetic screens are important tools for exploring the genetic requirements for neuronal function. However, conventional forward screens often have difficulty identifying genes whose relevant functions are masked by pleiotropy. In particular, if loss of gene function results in sterility, lethality, or other severe pleiotropy, neuronal-specific functions cannot be readily analyzed. Here we describe a method in C. elegans for generating cell-specific knockdown in neurons using feeding RNAi and its application in a screen for the role of essential genes in GABAergic neurons. We combine manipulations that increase the sensitivity of select neurons to RNAi with manipulations that block RNAi in other cells. We produce animal strains in which feeding RNAi results in restricted gene knockdown in either GABA-, acetylcholine-, dopamine-, or glutamate-releasing neurons. In these strains, we observe neuron cell-type specific behavioral changes when we knock down genes required for these neurons to function, including genes encoding the basal neurotransmission machinery. These reagents enable high-throughput, cell-specific knockdown in the nervous system, facilitating rapid dissection of the site of gene action and screening for neuronal functions of essential genes. Using the GABA-specific RNAi strain, we screened 1,320 RNAi clones targeting essential genes on chromosomes I, II, and III for their effect on GABA neuron function. We identified 48 genes whose GABA cell-specific knockdown resulted in reduced GABA motor output. This screen extends our understanding of the genetic requirements for continued neuronal function in a mature organism. Living organisms often reuse the same genes multiple times for different purposes. If one function of a gene is essential, death or arrest of the mutant masks other functions. Understanding the functions of essential genes is particularly critical in the nervous system, which must maintain plasticity and fend off disease long after development is complete. However, current strategies for generating conditional knockouts rely on making a new transgenic animal for each gene and thus are not useful for forward genetic screens or for other experiments involving a large number of genes. We have developed a technique in C. elegans for generating gene knockdown in selected neuron sub-types in response to feeding RNAi. Using this technique, we performed a screen aimed at identifying essential genes that are required for the function of mature GABAergic neurons. By knocking these genes down in only GABAergic neurons, we can circumvent the muddying effects of pleiotropy and find essential genes that function cell intrinsically to promote GABA neuron function. The genes we identified using this method provide a more complete understanding of the complex genetic requirements of post-developmental neurons.
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Affiliation(s)
- Christopher Firnhaber
- Department of Genetics, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Marc Hammarlund
- Department of Genetics, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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45
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Wang Z, Hou Y, Guo X, van der Voet M, Boxem M, Dixon JE, Chisholm AD, Jin Y. The EBAX-type Cullin-RING E3 ligase and Hsp90 guard the protein quality of the SAX-3/Robo receptor in developing neurons. Neuron 2013; 79:903-16. [PMID: 24012004 PMCID: PMC3779136 DOI: 10.1016/j.neuron.2013.06.035] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2013] [Indexed: 12/14/2022]
Abstract
Although protein quality control (PQC) is generally perceived as important for the development of the nervous system, the specific mechanisms of neuronal PQC have remained poorly understood. Here, we report that C. elegans Elongin BC-binding axon regulator (EBAX-1), a conserved BC-box protein, regulates axon guidance through PQC of the SAX-3/Robo receptor. EBAX-1 buffers guidance errors against temperature variations. As a substrate-recognition subunit in the Elongin BC-containing Cullin-RING ubiquitin ligase (CRL), EBAX-1 also binds to DAF-21, a cytosolic Hsp90 chaperone. The EBAX-type CRL and DAF-21 collaboratively regulate SAX-3-mediated axon pathfinding. Biochemical and imaging assays indicate that EBAX-1 specifically recognizes misfolded SAX-3 and promotes its degradation in vitro and in vivo. Importantly, vertebrate EBAX also shows substrate preference toward aberrant Robo3 implicated in horizontal gaze palsy with progressive scoliosis (HGPPS). Together, our findings demonstrate a triage PQC mechanism mediated by the EBAX-type CRL and DAF-21/Hsp90 that maintains the accuracy of neuronal wiring.
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Affiliation(s)
- Zhiping Wang
- Neurobiology Section, Division of Biological Sciences, UC San Diego, La Jolla, CA 92093
| | - Yanli Hou
- Department of Molecular, Cell, and Developmental Biology, UC Santa Cruz, CA 95064
| | - Xing Guo
- Department of Pharmacology, School of Medicine, UC San Diego, La Jolla, CA 92093
| | | | - Mike Boxem
- Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Jack E. Dixon
- Department of Pharmacology, School of Medicine, UC San Diego, La Jolla, CA 92093
- Howard Hughes Medical Institute
| | - Andrew D. Chisholm
- Neurobiology Section, Division of Biological Sciences, UC San Diego, La Jolla, CA 92093
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, UC San Diego, La Jolla, CA 92093
- Howard Hughes Medical Institute
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Hirose T, Horvitz HR. An Sp1 transcription factor coordinates caspase-dependent and -independent apoptotic pathways. Nature 2013; 500:354-8. [PMID: 23851392 PMCID: PMC3748152 DOI: 10.1038/nature12329] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 05/30/2013] [Indexed: 11/23/2022]
Abstract
During animal development, the proper regulation of apoptosis requires the precise spatial and temporal execution of cell-death programs, which can include both caspase-dependent and caspase-independent pathways1, 2. While the mechanisms of caspase-dependent and caspase-independent cell killing have been examined extensively, how these pathways are coordinated within a single cell that is fated to die is unknown. Here we show that the C. elegans Sp1 transcription factor SPTF-3 specifies the programmed cell deaths of at least two cells, the sisters of the pharyngeal M4 motor neuron and of the AQR sensory neuron, by transcriptionally activating both caspase-dependent and caspase-independent apoptotic pathways. SPTF-3 directly drives the transcription of the gene egl-1, which encodes a BH3-only protein that promotes apoptosis through the activation of the CED-3 caspase3. In addition, SPTF-3 directly drives the transcription of the AMPK-related gene pig-1, which encodes a protein kinase and functions in apoptosis of the M4 sister and AQR sister independently of the pathway that activates CED-34, 5. Thus, a single transcription factor controls two distinct cell-killing programs that act in parallel to drive apoptosis. Our findings reveal a bivalent regulatory node for caspase-dependent and caspase-independent pathways in the regulation of cell-type specific apoptosis. We propose that such nodes might act in a general mechanism for regulating cell-type specific apoptosis and could define therapeutic targets for diseases involving the dysregulation of apoptosis through multiple cell-killing mechanisms.
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Affiliation(s)
- Takashi Hirose
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Takashima Y, Kitaoka S, Bando T, Kagawa H. Expression profiles and unc-27 mutation rescue of the striated muscle type troponin I isoform-3 in Caenorhabditis elegans. Genes Genet Syst 2013; 87:243-51. [PMID: 23229311 DOI: 10.1266/ggs.87.243] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Transcription control of multiple genes in tissue- and stage-specific patterns is still of major interest. We show here that troponin I (TNI) is expressed under the control of upstream non-coding sequences and had functions as an isoform of intermediate type between pharynx and body-wall of the gene. In Caenorhabditis elegans, three striated muscle TNIs are expressed in body-wall muscles and a cardiac isoform is expressed in the pharynx. We have analyzed the gene expression mechanisms of tni-3 gene and motility function of its protein product. Promoter deletion analysis of the tni-3 gene identified muscle enhancers including the head enhancer. The CBF1/Su(H)/LAG-1-binding motif was included in the head enhancer. Yeast one-hybrid screening isolated the lag-1 clone in five candidates. Functional differences between the three striated muscle TNIs were investigated by the expression of promoter-fusion genes into tni-2/unc-27(e155) null mutant animals. The results suggest that the cis-elements in the promoters of the three genes are important for their tissue-specific expression and that from the function of TNI-3, the tni-3 gene would be an intermediate in the evolution of these genes by gene duplication. Mechanisms of tni-3 expression and its molecular function may contribute to our understanding of gene evolution and developmental programs.
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Affiliation(s)
- Yasuo Takashima
- Division of Bioscience, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
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48
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Semaphorin-1 and netrin signal in parallel and permissively to position the male ray 1 sensillum in Caenorhabditis elegans. Genetics 2012; 192:959-71. [PMID: 22942127 DOI: 10.1534/genetics.112.144253] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Netrin and semaphorin axon guidance cues have been found to function in the genesis of several mammalian organs; however, little is known about the underlying molecular mechanisms involved. A genetic approach could help to reveal the underpinnings of these mechanisms. The most anterior ray sensillum (ray 1) in the Caenorhabditis elegans male tail is frequently displaced anterior to its normal position in smp-1/semaphorin-1a and plexin-1/plx-1 mutants. Here we report that UNC-6/netrin and its UNC-40/DCC receptor signal in parallel to SMP-1/semaphorin-1a and its PLX-1/plexin-1 receptor to prevent the anterior displacement of ray 1 and that UNC-6 plus SMP-1 signaling can account entirely for this function. We also report that mab-20/semaphorin-2a mutations, which prevent the separation of neighboring rays and cause ray fusions, suppress the anterior displacements of ray 1 caused by deficiencies in SMP-1 and UNC-6 signaling and this is independent of the ray fusion phenotype, whereas overexpression of UNC-40 and PLX-1 cause ray fusions. This suggests that for ray 1 positioning, a balance is struck between a tendency of SMP-1 and UNC-6 signaling to prevent ray 1 from moving away from ray 2 and a tendency of MAB-20/semaphorin-2a signaling to separate all rays from each other. Additional evidence suggests this balance involves the relative adhesion of the ray 1 structural cell to neighboring SET and hyp 7 hypodermal cells. This finding raises the possibility that changes in ray 1 positioning depend on passive movements caused by attachment to the elongating SET cell in opposition to the morphologically more stable hyp 7 cell. Several lines of evidence indicate that SMP-1 and UNC-6 function permissively in the context of ray 1 positioning.
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49
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Qadota H, Moerman DG, Benian GM. A molecular mechanism for the requirement of PAT-4 (integrin-linked kinase (ILK)) for the localization of UNC-112 (Kindlin) to integrin adhesion sites. J Biol Chem 2012; 287:28537-51. [PMID: 22761445 PMCID: PMC3436513 DOI: 10.1074/jbc.m112.354852] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 06/11/2012] [Indexed: 11/06/2022] Open
Abstract
Caenorhabditis elegans muscle cells attach to basement membrane through adhesion plaques. PAT-3 (β-integrin), UNC-112 (kindlin), and PAT-4 (integrin-linked kinase) are associated with these structures. Genetic analysis indicated that PAT-4 is required for UNC-112 to be properly localized. We investigated the molecular basis of this requirement. We show that the cytoplasmic tail of PAT-3 binds to full-length UNC-112 and that the N- and C-terminal halves of UNC-112 bind to each other. We demonstrate competition between the UNC-112 C-terminal half and PAT-4 for binding to the UNC-112 N-terminal half. The D382V mutation results in lack of binding to PAT-4 and lack of localization to adhesion structures. T346A or E349K mutations, which abolish interaction of the N- and C-terminal halves, permit D382V UNC-112 to localize to adhesion structures. The following model is proposed. UNC-112 exists in closed inactive and open active conformations, and upon binding of PAT-4 to the UNC-112 N-terminal half, UNC-112 is converted into the open state, able to bind to PAT-3.
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Affiliation(s)
- Hiroshi Qadota
- From the Department of Pathology, Emory University, Atlanta, Georgia 30322 and
- the Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Donald G. Moerman
- the Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Guy M. Benian
- From the Department of Pathology, Emory University, Atlanta, Georgia 30322 and
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50
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SACY-1 DEAD-Box helicase links the somatic control of oocyte meiotic maturation to the sperm-to-oocyte switch and gamete maintenance in Caenorhabditis elegans. Genetics 2012; 192:905-28. [PMID: 22887816 PMCID: PMC3522166 DOI: 10.1534/genetics.112.143271] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In sexually reproducing animals, oocytes arrest at diplotene or diakinesis and resume meiosis (meiotic maturation) in response to hormones. In Caenorhabditis elegans, major sperm protein triggers meiotic resumption through a mechanism involving somatic Gαs–adenylate cyclase signaling and soma-to-germline gap-junctional communication. Using genetic mosaic analysis, we show that the major effector of Gαs–adenylate cyclase signaling, protein kinase A (PKA), is required in gonadal sheath cells for oocyte meiotic maturation and dispensable in the germ line. This result rules out a model in which cyclic nucleotides must transit through sheath-oocyte gap junctions to activate PKA in the germ line, as proposed in vertebrate systems. We conducted a genetic screen to identify regulators of oocyte meiotic maturation functioning downstream of Gαs–adenylate cyclase–PKA signaling. We molecularly identified 10 regulatory loci, which include essential and nonessential factors. sacy-1, which encodes a highly conserved DEAD-box helicase, is an essential germline factor that negatively regulates meiotic maturation. SACY-1 is a multifunctional protein that establishes a mechanistic link connecting the somatic control of meiotic maturation to germline sex determination and gamete maintenance. Modulatory factors include multiple subunits of a CoREST-like complex and the TWK-1 two-pore potassium channel. These factors are not absolutely required for meiotic maturation or its negative regulation in the absence of sperm, but function cumulatively to enable somatic control of meiotic maturation. This work provides insights into the genetic control of meiotic maturation signaling in C. elegans, and the conserved factors identified here might inform analysis in other systems through either homology or analogy.
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