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Van Bael S, Ludwig C, Baggerman G, Temmerman L. Identification and Targeted Quantification of Endogenous Neuropeptides in the Nematode Caenorhabditis elegans Using Mass Spectrometry. Methods Mol Biol 2024; 2758:341-373. [PMID: 38549024 DOI: 10.1007/978-1-0716-3646-6_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The nematode Caenorhabditis elegans lends itself as an excellent model organism for peptidomics studies. Its ease of cultivation and quick generation time make it suitable for high-throughput studies. The nervous system, with its 302 neurons, is probably the best-known and studied endocrine tissue. Moreover, its neuropeptidergic signaling pathways display numerous similarities with those observed in other metazoans. Here, we describe two label-free approaches for neuropeptidomics in C. elegans: one for discovery purposes, and another for targeted quantification and comparisons of neuropeptide levels between different samples. Starting from a detailed peptide extraction procedure, we here outline the liquid chromatography tandem mass spectrometry (LC-MS/MS) setup and describe subsequent data analysis approaches.
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Affiliation(s)
- Sven Van Bael
- Department of Biology, Animal Physiology & Neurobiology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Christina Ludwig
- Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), Technical University of Munich (TUM), Freising, Germany
| | - Geert Baggerman
- Center for Proteomics, University of Antwerp, Antwerp, Belgium
| | - Liesbet Temmerman
- Department of Biology, Animal Physiology & Neurobiology, University of Leuven (KU Leuven), Leuven, Belgium.
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2
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Mauro M, Ugo P, Walton Z, Ali S, Rastellini C, Cicalese L. Glypican-3 (GPC-3) Structural Analysis and Cargo in Serum Small Extracellular Vesicles of Hepatocellular Carcinoma Patients. Int J Mol Sci 2023; 24:10922. [PMID: 37446098 DOI: 10.3390/ijms241310922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 07/15/2023] Open
Abstract
Glypican-3 (GPC-3) is a heparin sulfate proteoglycan located extracellularly and anchored to the cell membrane of transformed hepatocytes. GPC-3 is not expressed in normal or cirrhotic liver tissue but is overexpressed in hepatocellular carcinoma (HCC). Because of this, GPC-3 is one of the most important emerging immunotargets for treatment and as an early detection marker of HCC. To determine if GPC-3 domains associated with serum small extracellular vesicles (sEVs) could be used as an HCC diagnostic marker, we predicted in silico GPC-3 structural properties and tested for the presence of its full-length form and/or cleaved domains in serum sEVs isolated from patients with HCC. Structural analysis revealed that the Furin cleavage site of GPC-3 is exposed and readily accessible, suggesting the facilitation of GPC-3 cleavage events. Upon isolation of sEVs from both hepatocytes, culture media and serum of patients with HCC were studied for GPC-3 content. This data suggests that Furin-dependent GPC-3 cleaved domains could be a powerful tool for detection of initial stages of HCC and serve as a predictor for disease prognosis.
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Affiliation(s)
- Montalbano Mauro
- Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555-5302, USA
| | - Perricone Ugo
- Molecular Informatics Group, Fondazione Ri.MED., 90133 Palermo, Italy
| | - Zachary Walton
- John Sealy School of Medicine, University of Texas Medical Branch, Galveston, TX 77555-5302, USA
| | - Shirafkan Ali
- Rutgers Health, Department of Cardiac Surgery, New Brunswick, NJ 08901, USA
| | - Cristiana Rastellini
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77555-5302, USA
| | - Luca Cicalese
- Department of Neurobiology, University of Texas Medical Branch, Galveston, TX 77555-5302, USA
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3
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Glendinning S, Fitzgibbon QP, Smith GG, Ventura T. Unravelling the neuropeptidome of the ornate spiny lobster Panulirus ornatus: A focus on peptide hormones and their processing enzymes expressed in the reproductive tissues. Gen Comp Endocrinol 2023; 332:114183. [PMID: 36471526 DOI: 10.1016/j.ygcen.2022.114183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 11/21/2022] [Accepted: 11/24/2022] [Indexed: 11/29/2022]
Abstract
Neuropeptides are commonly produced in the neural tissues yet can have effects on far-reaching targets, with varied biological responses. We describe here the neuropeptidome of the ornate spiny lobster, Panulirus ornatus, a species of emerging importance to closed-system aquaculture, with a focus on peptide hormones produced by the reproductive tissues. Transcripts for a precursor to one neuropeptide, adipokinetic hormone/corazonin-related peptide (ACP) were identified in high numbers in the sperm duct of adult spiny lobsters suggesting a role for ACP in the reproduction of this species. Neuropeptide production in the sperm duct may be linked with physiological control of spermatophore production in the male, or alternatively may function in signalling to the female. The enzymes which process nascent neuropeptide precursors into their mature, active forms have seldom been studied in decapods, and never before at the multi-tissue level. We have identified transcripts for multiple members of the proprotein convertase subtisilin/kexin family in the ornate spiny lobster, with some enzymes showing specificity to certain tissues. In addition, other enzyme transcripts involved with neuropeptide processing are identified along with their tissue and life stage expression patterns.
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Affiliation(s)
- Susan Glendinning
- Centre for Bioinnovation, University of the Sunshine Coast, Maroochydore, QLD, Australia; School of Science and Engineering, University of the Sunshine Coast, Maroochydore, QLD, Australia.
| | - Quinn P Fitzgibbon
- Institute for Marine and Antarctic Studies (IMAS), University of Tasmania, Private Bag 49, Hobart, Tasmania 7001, Australia
| | - Gregory G Smith
- Institute for Marine and Antarctic Studies (IMAS), University of Tasmania, Private Bag 49, Hobart, Tasmania 7001, Australia
| | - Tomer Ventura
- Centre for Bioinnovation, University of the Sunshine Coast, Maroochydore, QLD, Australia; School of Science and Engineering, University of the Sunshine Coast, Maroochydore, QLD, Australia
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4
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Positive interaction between ASH and ASK sensory neurons accelerates nociception and inhibits behavioral adaptation. iScience 2022; 25:105287. [PMID: 36304123 PMCID: PMC9593764 DOI: 10.1016/j.isci.2022.105287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 05/22/2022] [Accepted: 10/04/2022] [Indexed: 11/23/2022] Open
Abstract
Central and peripheral sensory neurons tightly regulate nociception and avoidance behavior. The peripheral modulation of nociception provides more veridical and instantaneous information for animals to achieve rapid, more fine-tuned and concentrated behavioral responses. In this study, we find that positive interaction between ASH and ASK sensory neurons is essential for the fast-rising phase of ASH Ca2+ responses to noxious copper ions and inhibits the adaption of avoiding Cu2+. We reveal the underlying neuronal circuit mechanism. ASK accelerates the ASH Ca2+ responses by transferring cGMP through gap junctions. ASH excites ASK via a disinhibitory neuronal circuit composed of ASH, AIA, and ASK. Avoidance adaptation depends on the slope rate of the rising phase of ASH Ca2+ responses. Thus, in addition to amplitude, sensory kinetics is significant for sensations and behaviors, especially for sensory and behavioral adaptations.
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Scott E, Holden-Dye L, O'Connor V, Wand ME. Intra Strain Variation of the Effects of Gram-Negative ESKAPE Pathogens on Intestinal Colonization, Host Viability, and Host Response in the Model Organism Caenorhabditis elegans. Front Microbiol 2020; 10:3113. [PMID: 32038555 PMCID: PMC6985274 DOI: 10.3389/fmicb.2019.03113] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 12/24/2019] [Indexed: 01/21/2023] Open
Abstract
In its native environment of rotting vegetation, the soil nematode Caenorhabditis elegans encounters a range of bacteria. This includes species from the ESKAPE group of pathogens that pose a clinical problem in acquired hospital infections. Here, we investigated three Gram-negative members of the ESKAPE group, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii. Pathogenicity profiles as measured by time to kill adult C. elegans showed that P. aeruginosa was the most pathogenic, followed by K. pneumoniae, while C. elegans cultured on A. baumannii exhibited the same survival as those on the standard laboratory food source for C. elegans, Escherichia coli OP50. The pathogenicity was paralleled by a reduction in time that C. elegans resided on the bacterial lawn with the most pathogenic strains triggering an increase in the frequency of food-leaving. Previous reports indicate that gut colonization is a feature of pathogenicity, but we found that the most pathogenic strains were not associated with the highest level of colonization. Indeed, clearance of P. aeruginosa strains from the C. elegans gut was independent of bacterial pathogenicity. We show that this clearance is regulated by neuromodulation as C. elegans mutants in unc-31 and egl-3 have enhanced clearance of P. aeruginosa. Intriguingly this is also not linked to their pathogenicity. It is likely that there is a dynamic balance occurring in the C. elegans intestinal environment between maintaining a healthy, beneficial microbiota and removal of pathogenic bacteria.
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Affiliation(s)
- Euan Scott
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Lindy Holden-Dye
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Vincent O'Connor
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Matthew E Wand
- National Infection Service, Public Health England, Salisbury, United Kingdom
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6
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Hammond MJ, Wang T, Cummins SF. Characterisation of early metazoan secretion through associated signal peptidase complex subunits, prohormone convertases and carboxypeptidases of the marine sponge (Amphimedon queenslandica). PLoS One 2019; 14:e0225227. [PMID: 31714927 PMCID: PMC6850559 DOI: 10.1371/journal.pone.0225227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/30/2019] [Indexed: 01/31/2023] Open
Abstract
Efficient communication between cells requires the ability to process precursor proteins into their mature and biologically active forms, prior to secretion into the extracellular space. Eukaryotic cells achieve this via a suite of enzymes that involve a signal peptidase complex, prohormone convertases and carboxypeptidases. Using genome and transcriptome data of the demosponge Amphimedon queenslandica, a universal ancestor to metazoan multicellularity, we endeavour to bridge the evolution of precursor processing machinery from single-celled eukaryotic ancestors through to the complex multicellular organisms that compromise Metazoa. The precursor processing repertoire as defined in this study of A. queenslandica consists of 3 defined signal peptidase subunits, 6 prohormone convertases and 1 carboxypeptidase, with 2 putative duplicates identified for signal peptidase complex subunits. Analysis of their gene expression levels throughout the sponge development enabled us to predict levels of activity. Some A. queenslandica precursor processing components belong to established functional clades while others were identified as having novel, yet to be discovered roles. These findings have clarified the presence of precursor processing machinery in the poriferans, showing the necessary machinery for the removal of precursor sequences, a critical post-translational modification required by multicellular organisms, and further sets a foundation towards understanding the molecular mechanism for ancient protein processing.
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Affiliation(s)
- Michael J. Hammond
- Genecology Research Centre, University of the Sunshine Coast, Maroochydore Dc, Queensland, Australia
| | - Tianfang Wang
- Genecology Research Centre, University of the Sunshine Coast, Maroochydore Dc, Queensland, Australia
| | - Scott F. Cummins
- Genecology Research Centre, University of the Sunshine Coast, Maroochydore Dc, Queensland, Australia
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7
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Harris G, Wu T, Linfield G, Choi MK, Liu H, Zhang Y. Molecular and cellular modulators for multisensory integration in C. elegans. PLoS Genet 2019; 15:e1007706. [PMID: 30849079 PMCID: PMC6426271 DOI: 10.1371/journal.pgen.1007706] [Citation(s) in RCA: 14] [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: 09/18/2018] [Revised: 03/20/2019] [Accepted: 01/23/2019] [Indexed: 12/19/2022] Open
Abstract
In the natural environment, animals often encounter multiple sensory cues that are simultaneously present. The nervous system integrates the relevant sensory information to generate behavioral responses that have adaptive values. However, the neuronal basis and the modulators that regulate integrated behavioral response to multiple sensory cues are not well defined. Here, we address this question using a behavioral decision in C. elegans when the animal is presented with an attractive food source together with a repulsive odorant. We identify specific sensory neurons, interneurons and neuromodulators that orchestrate the decision-making process, suggesting that various states and contexts may modulate the multisensory integration. Among these modulators, we characterize a new function of a conserved TGF-β pathway that regulates the integrated decision by inhibiting the signaling from a set of central neurons. Interestingly, we find that a common set of modulators, including the TGF-β pathway, regulate the integrated response to the pairing of different foods and repellents. Together, our results provide mechanistic insights into the modulatory signals regulating multisensory integration. The present study characterizes the modulation of a behavioral decision in C. elegans when the worm is presented with a food lawn that is paired with a repulsive smell. We show that multiple specific sensory neurons and interneurons play roles in making the decision. We also identify several modulatory molecules that are essential for the integrated decision when the animal faces a choice between the cues of opposing valence. We further show that many of these factors, which often represent different states and contexts, are common for behavioral decisions that integrate sensory information from different types of foods and repellents. Overall, our results reveal the molecular and cellular basis for integration of simultaneously present attractive and repulsive cues to fine-tune decision-making.
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Affiliation(s)
- Gareth Harris
- Department of Organismic and Evolutionary Biology, Center for Brain Sciences, Harvard University, Cambridge, MA, United States of America
- * E-mail: (GH); (YZ)
| | - Taihong Wu
- Department of Organismic and Evolutionary Biology, Center for Brain Sciences, Harvard University, Cambridge, MA, United States of America
| | - Gaia Linfield
- Department of Organismic and Evolutionary Biology, Center for Brain Sciences, Harvard University, Cambridge, MA, United States of America
| | - Myung-Kyu Choi
- Department of Organismic and Evolutionary Biology, Center for Brain Sciences, Harvard University, Cambridge, MA, United States of America
| | - He Liu
- Department of Organismic and Evolutionary Biology, Center for Brain Sciences, Harvard University, Cambridge, MA, United States of America
| | - Yun Zhang
- Department of Organismic and Evolutionary Biology, Center for Brain Sciences, Harvard University, Cambridge, MA, United States of America
- * E-mail: (GH); (YZ)
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8
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Doshi S, Price E, Landis J, Barot U, Sabatella M, Lans H, Kalb RG. Neuropeptide signaling regulates the susceptibility of developing C. elegans to anoxia. Free Radic Biol Med 2019; 131:197-208. [PMID: 30529384 DOI: 10.1016/j.freeradbiomed.2018.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/05/2018] [Accepted: 12/05/2018] [Indexed: 02/04/2023]
Abstract
Inadequate delivery of oxygen to organisms during development can lead to cell dysfunction/death and life-long disabilities. Although the susceptibility of developing cells to low oxygen conditions changes with maturation, the cellular and molecular pathways that govern responses to low oxygen are incompletely understood. Here we show that developing Caenorhabditis elegans are substantially more sensitive to anoxia than adult animals and that this sensitivity is controlled by nervous system generated hormones (e.g., neuropeptides). A screen of neuropeptide genes identified and validated nlp-40 and its receptor aex-2 as a key regulator of anoxic survival in developing worms. The survival-promoting action of impaired neuropeptide signaling does not rely on five known stress resistance pathways and is specific to anoxic insult. Together, these data highlight a novel cell non-autonomous pathway that regulates the susceptibility of developing organisms to anoxia.
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Affiliation(s)
- Shachee Doshi
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Emma Price
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Justin Landis
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Urva Barot
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Mariangela Sabatella
- Department of Molecular Genetics, Erasmus Medical Centre, Oncode Institute, Cancer Genomics Netherlands, Rotterdam 3015 CN, the Netherlands
| | - Hannes Lans
- Department of Molecular Genetics, Erasmus Medical Centre, Oncode Institute, Cancer Genomics Netherlands, Rotterdam 3015 CN, the Netherlands
| | - Robert G Kalb
- Division of Neurology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Proteases Shape the Chlamydomonas Secretome: Comparison to Classical Neuropeptide Processing Machinery. Proteomes 2018; 6:proteomes6040036. [PMID: 30249063 PMCID: PMC6313938 DOI: 10.3390/proteomes6040036] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 09/17/2018] [Accepted: 09/20/2018] [Indexed: 12/25/2022] Open
Abstract
The recent identification of catalytically active peptidylglycine α-amidating monooxygenase (PAM) in Chlamydomonas reinhardtii, a unicellular green alga, suggested the presence of a PAM-like gene and peptidergic signaling in the last eukaryotic common ancestor (LECA). We identified prototypical neuropeptide precursors and essential peptide processing enzymes (subtilisin-like prohormone convertases and carboxypeptidase B-like enzymes) in the C.
reinhardtii genome. Reasoning that sexual reproduction by C. reinhardtii requires extensive communication between cells, we used mass spectrometry to identify proteins recovered from the soluble secretome of mating gametes, and searched for evidence that the putative peptidergic processing enzymes were functional. After fractionation by SDS-PAGE, signal peptide-containing proteins that remained intact, and those that had been subjected to cleavage, were identified. The C. reinhardtii mating secretome contained multiple matrix metalloproteinases, cysteine endopeptidases, and serine carboxypeptidases, along with one subtilisin-like proteinase. Published transcriptomic studies support a role for these proteases in sexual reproduction. Multiple extracellular matrix proteins (ECM) were identified in the secretome. Several pherophorins, ECM glycoproteins homologous to the Volvox sex-inducing pheromone, were present; most contained typical peptide processing sites, and many had been cleaved, generating stable N- or C-terminal fragments. Our data suggest that subtilisin endoproteases and matrix metalloproteinases similar to those important in vertebrate peptidergic and growth factor signaling play an important role in stage transitions during the life cycle of C.
reinhardtii.
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Rapti G, Li C, Shan A, Lu Y, Shaham S. Glia initiate brain assembly through noncanonical Chimaerin-Furin axon guidance in C. elegans. Nat Neurosci 2017; 20:1350-1360. [PMID: 28846083 PMCID: PMC5614858 DOI: 10.1038/nn.4630] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/19/2017] [Indexed: 01/08/2023]
Abstract
Brain assembly is hypothesized to begin when pioneer axons extend over non-neuronal cells, forming tracts guiding follower axons. Yet pioneer-neuron identities, their guidance substrates, and their interactions are not well understood. Here, using time-lapse embryonic imaging, genetics, protein-interaction, and functional studies, we uncover the early events of C. elegans brain assembly. We demonstrate that C. elegans glia are key for assembly initiation, guiding pioneer and follower axons using distinct signals. Pioneer sublateral neurons, with unique growth properties, anatomy, and innervation, cooperate with glia to mediate follower-axon guidance. We further identify a Chimaerin (CHIN-1)- Furin (KPC-1) double-mutant that severely disrupts assembly. CHIN-1 and KPC-1 function noncanonically, in glia and pioneer neurons, for guidance-cue trafficking. We exploit this bottleneck to define roles for glial Netrin and Semaphorin in pioneer- and follower-axon guidance, respectively, and for glial and pioneer-neuron Flamingo (CELSR) in follower-axon navigation. Taken together, our studies reveal previously undescribed glial roles in pioneer-axon guidance, suggesting conserved principles of brain assembly.
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Affiliation(s)
- Georgia Rapti
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Chang Li
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
- These authors contributed equally to this work
| | - Alan Shan
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
- These authors contributed equally to this work
| | - Yun Lu
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
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11
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Neuropeptide signals cell non-autonomous mitochondrial unfolded protein response. Cell Res 2016; 26:1182-1196. [PMID: 27767096 PMCID: PMC5099867 DOI: 10.1038/cr.2016.118] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 09/18/2016] [Accepted: 09/19/2016] [Indexed: 11/21/2022] Open
Abstract
Neurons have a central role in the systemic coordination of mitochondrial unfolded protein response (UPRmt) and the cell non-autonomous modulation of longevity. However, the mechanism by which the nervous system senses mitochondrial stress and communicates to the distal tissues to induce UPRmt remains unclear. Here we employ the tissue-specific CRISPR-Cas9 approach to disrupt mitochondrial function only in the nervous system of Caenorhabditis elegans, and reveal a cell non-autonomous induction of UPRmt in peripheral cells. We further show that a neural sub-circuit composed of three types of sensory neurons, and one interneuron is required for sensing and transducing neuronal mitochondrial stress. In addition, neuropeptide FLP-2 functions in this neural sub-circuit to signal the non-autonomous UPRmt. Taken together, our results suggest a neuropeptide coordination of mitochondrial stress response in the nervous system.
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12
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Tu H, Huhtala P, Lee HM, Adams JC, Pihlajaniemi T. Membrane-associated collagens with interrupted triple-helices (MACITs): evolution from a bilaterian common ancestor and functional conservation in C. elegans. BMC Evol Biol 2015; 15:281. [PMID: 26667623 PMCID: PMC4678570 DOI: 10.1186/s12862-015-0554-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 12/02/2015] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Collagens provide structural support and guidance cues within the extracellular matrix of metazoans. Mammalian collagens XIII, XXIII and XXV form a unique subgroup of type II transmembrane proteins, each comprising a short N-terminal cytosolic domain, a transmembrane domain and a largely collagenous ectodomain. We name these collagens as MACITs (Membrane-Associated Collagens with Interrupted Triple-helices), and here investigate their evolution and conserved properties. To date, these collagens have been studied only in mammals. Knowledge of the representation of MACITs in other extant metazoans is lacking. This question is of interest for understanding structural/functional relationships in the MACIT family and also for insight into the evolution of MACITs in relation to the secreted, fibrillar collagens that are present throughout the metazoa. RESULTS MACITs are restricted to bilaterians and are represented in the Ecdysozoa, Hemichordata, Urochordata and Vertebrata (Gnathostomata). They were not identified in available early-diverging metazoans, Lophotrochozoa, Echinodermata, Cephalochordata or Vertebrata (Cyclostomata). Whereas invertebrates encode a single MACIT, collagens XIII/XXIII/XXV of jawed vertebrates are paralogues that originated from the two rounds of en-bloc genome duplication occurring early in vertebrate evolution. MACITs have conserved domain architecture in which a juxta-membrane furin-cleavage site and the C-terminal 34 residues are especially highly conserved, whereas the cytoplasmic domains are weakly conserved. To study protein expression and function in a metazoan with a single MACIT gene, we focused on Caenorhabditis elegans and its col-99 gene. A col-99 cDNA was cloned and expressed as protein in mammalian CHO cells, two antibodies against COL-99 protein were generated, and a col-99-bearing fosmid gene construct col-99::egfp::flag was used to generate transgenic C. elegans lines. The encoded COL-99 polypeptide is 85 kDa in size and forms a trimeric protein. COL-99 is plasma membrane-associated and undergoes furin-dependent ectodomain cleavage and shedding. COL-99 is detected in mouth, pharynx, body wall and the tail, mostly in motor neurons and muscle systems and is enriched at neuromuscular junctions. CONCLUSIONS Through identification of MACITs in multiple metazoan phyla we developed a model for the evolution of MACITs. The experimental data demonstrate conservation of MACIT molecular and cellular properties and tissue localisations in the invertebrate, C. elegans.
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Affiliation(s)
- Hongmin Tu
- Centre of Excellence in Cell-Extracellular Matrix Research, Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Aapistie 5, Oulu, FIN 90014, Finland.
| | - Pirkko Huhtala
- Centre of Excellence in Cell-Extracellular Matrix Research, Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Aapistie 5, Oulu, FIN 90014, Finland.
| | - Hang-Mao Lee
- Centre of Excellence in Cell-Extracellular Matrix Research, Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Aapistie 5, Oulu, FIN 90014, Finland.
| | - Josephine C Adams
- School of Biochemistry, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
| | - Taina Pihlajaniemi
- Centre of Excellence in Cell-Extracellular Matrix Research, Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Aapistie 5, Oulu, FIN 90014, Finland.
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13
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Fittler H, Depp A, Avrutina O, Dahms SO, Than ME, Empting M, Kolmar H. Engineering a Constrained Peptidic Scaffold towards Potent and Selective Furin Inhibitors. Chembiochem 2015; 16:2441-4. [DOI: 10.1002/cbic.201500447] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Heiko Fittler
- Clemens-Schöpf-Institut für organische und Biochemie; Technische Universität Darmstadt; Alarich-Weiss Strasse 4 64287 Darmstadt Germany
| | - Alexander Depp
- Clemens-Schöpf-Institut für organische und Biochemie; Technische Universität Darmstadt; Alarich-Weiss Strasse 4 64287 Darmstadt Germany
| | - Olga Avrutina
- Clemens-Schöpf-Institut für organische und Biochemie; Technische Universität Darmstadt; Alarich-Weiss Strasse 4 64287 Darmstadt Germany
| | - Sven O. Dahms
- Leibniz Institute for Age Research-Fritz Lipmann Institute (FLI); Beutenbergstrasse 11 07745 Jena Germany
| | - Manuel E. Than
- Leibniz Institute for Age Research-Fritz Lipmann Institute (FLI); Beutenbergstrasse 11 07745 Jena Germany
| | - Martin Empting
- Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS); Campus C2.3 66123 Saarbrücken Germany
| | - Harald Kolmar
- Clemens-Schöpf-Institut für organische und Biochemie; Technische Universität Darmstadt; Alarich-Weiss Strasse 4 64287 Darmstadt Germany
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Salzberg Y, Ramirez-Suarez NJ, Bülow HE. The proprotein convertase KPC-1/furin controls branching and self-avoidance of sensory dendrites in Caenorhabditis elegans. PLoS Genet 2014; 10:e1004657. [PMID: 25232734 PMCID: PMC4169376 DOI: 10.1371/journal.pgen.1004657] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/09/2014] [Indexed: 11/18/2022] Open
Abstract
Animals sample their environment through sensory neurons with often elaborately branched endings named dendritic arbors. In a genetic screen for genes involved in the development of the highly arborized somatosensory PVD neuron in C. elegans, we have identified mutations in kpc-1, which encodes the homolog of the proprotein convertase furin. We show that kpc-1/furin is necessary to promote the formation of higher order dendritic branches in PVD and to ensure self-avoidance of sister branches, but is likely not required during maintenance of dendritic arbors. A reporter for kpc-1/furin is expressed in neurons (including PVD) and kpc-1/furin can function cell-autonomously in PVD neurons to control patterning of dendritic arbors. Moreover, we show that kpc-1/furin also regulates the development of other neurons in all major neuronal classes in C. elegans, including aspects of branching and extension of neurites as well as cell positioning. Our data suggest that these developmental functions require proteolytic activity of KPC-1/furin. Recently, the skin-derived MNR-1/menorin and the neural cell adhesion molecule SAX-7/L1CAM have been shown to act as a tripartite complex with the leucine rich transmembrane receptor DMA-1 on PVD mechanosensory to orchestrate the patterning of dendritic branches. Genetic analyses show that kpc-1/furin functions in a pathway with MNR-1/menorin, SAX-7/L1CAM and DMA-1 to control dendritic branch formation and extension of PVD neurons. We propose that KPC-1/furin acts in concert with the ‘menorin’ pathway to control branching and growth of somatosensory dendrites in PVD. Sensory neurons receive input from other neurons or sample their environment through elaborate structures termed dendritic trees. The correct patterning of dendritic trees is crucial for the proper function of the nervous system, and ample evidence points to the involvement of dendritic defects in a wide range of neuropsychiatric diseases. However, we still do not understand fully how this process is regulated at the molecular level. We discovered an important role for the protein-processing enzyme KPC-1/furin in the development of touch-sensitive dendritic trees in the roundworm C. elegans. Animals lacking this enzyme show multiple defects in the size, shape and number of these dendritic branches as well as other neurons. We further show that the gene encoding KPC-1 is expressed widely in the nervous system and that it is required within the branching neuron to exert its function on dendritic growth. Finally, we reveal a genetic connection between KPC-1 function and genes of the menorin pathway, which was recently discovered to also play an essential role in dendrite development. Thus, our findings add new insight into the molecular understanding of dendrite formation.
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Affiliation(s)
- Yehuda Salzberg
- Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, United States of America
| | - Nelson J. Ramirez-Suarez
- Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, United States of America
| | - Hannes E. Bülow
- Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, United States of America
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, United States of America
- * E-mail:
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15
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Husson SJ, Reumer A, Temmerman L, De Haes W, Schoofs L, Mertens I, Baggerman G. Worm peptidomics. EUPA OPEN PROTEOMICS 2014. [DOI: 10.1016/j.euprot.2014.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Hung WL, Wang Y, Chitturi J, Zhen M. A Caenorhabditis elegans developmental decision requires insulin signaling-mediated neuron-intestine communication. Development 2014; 141:1767-79. [PMID: 24671950 PMCID: PMC3978837 DOI: 10.1242/dev.103846] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Adverse environmental conditions trigger C. elegans larvae to activate an alternative developmental program, termed dauer diapause, which renders them stress resistant. High-level insulin signaling prevents constitutive dauer formation. However, it is not fully understood how animals assess conditions to choose the optimal developmental program. Here, we show that insulin-like peptide (ILP)-mediated neuron-intestine communication plays a role in this developmental decision. Consistent with, and extending, previous findings, we show that the simultaneous removal of INS-4, INS-6 and DAF-28 leads to fully penetrant constitutive dauer formation, whereas the removal of INS-1 and INS-18 significantly inhibits constitutive dauer formation. These ligands are processed by the proprotein convertases PC1/KPC-1 and/or PC2/EGL-3. The agonistic and antagonistic ligands are expressed by, and function in, neurons to prevent or promote dauer formation. By contrast, the insulin receptor DAF-2 and its effector, the FOXO transcription factor DAF-16, function solely in the intestine to regulate the decision to enter diapause. These results suggest that the nervous system normally establishes an agonistic ILP-dominant paradigm to inhibit intestinal DAF-16 activation and allow reproductive development. Under adverse conditions, a switch in the agonistic-antagonistic ILP balance activates intestinal DAF-16, which commits animals to diapause.
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Affiliation(s)
- Wesley L Hung
- Lunenfeld-Tanenbaum Research Institute, University of Toronto, Toronto, Ontario, M5G 1X5, Canada
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17
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Leinwand SG, Chalasani SH. From genes to circuits and behaviors: Neuropeptides expand the coding potential of the nervous system. WORM 2014; 3:e27730. [PMID: 25254145 PMCID: PMC4165544 DOI: 10.4161/worm.27730] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 12/21/2013] [Accepted: 01/03/2014] [Indexed: 12/18/2022]
Abstract
Neuropeptide signaling remodels the composition of a chemosensory circuit and shapes behavior in Caenorhabditis elegans. We reported that the ASE left (ASEL) salt sensory neuron uses a proprotein convertase, BLI-4, to cleave the insulin-like peptide INS-6. INS-6 peptides are released from the ASEL neuron in response to large, but not small changes in salt stimuli. Fast INS-6 signaling functionally transforms the AWC olfactory sensory neuron into an interneuron in the neural circuit for high salt. This new circuit configuration potentiates behavioral attraction to high salt. Here, in the context of genes, circuits, and behaviors, we discuss the diverse modes of neuropeptide processing and signaling, which expand the coding potential of the nervous system. First, neuropeptide processing and release genes prepare insulin peptides to signal in the nervous system. Second, this neuropeptide signaling diversifies the communication of neural circuits and introduces circuit-level flexibility. Finally, the resulting multisensory neurons and circuits drive finely tuned behavioral choices.
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Affiliation(s)
- Sarah G Leinwand
- Neurosciences Graduate Program; University of California San Diego; La Jolla, CA USA ; Molecular Neurobiology Laboratory; The Salk Institute for Biological Studies; La Jolla, CA USA
| | - Sreekanth H Chalasani
- Neurosciences Graduate Program; University of California San Diego; La Jolla, CA USA ; Molecular Neurobiology Laboratory; The Salk Institute for Biological Studies; La Jolla, CA USA
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18
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Li C, Kim K. Family of FLP Peptides in Caenorhabditis elegans and Related Nematodes. Front Endocrinol (Lausanne) 2014; 5:150. [PMID: 25352828 PMCID: PMC4196577 DOI: 10.3389/fendo.2014.00150] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 09/09/2014] [Indexed: 11/16/2022] Open
Abstract
Neuropeptides regulate all aspects of behavior in multicellular organisms. Because of their ability to act at long distances, neuropeptides can exert their effects beyond the conventional synaptic connections, thereby adding an intricate layer of complexity to the activity of neural networks. In the nematode Caenorhabditis elegans, a large number of neuropeptide genes that are expressed throughout the nervous system have been identified. The actions of these peptides supplement the synaptic connections of the 302 neurons, allowing for fine tuning of neural networks and increasing the ways in which behaviors can be regulated. In this review, we focus on a large family of genes encoding FMRFamide-related peptides (FaRPs). These genes, the flp genes, have been used as a starting point to identifying flp genes throughout Nematoda. Nematodes have the largest family of FaRPs described thus far. The challenges in the future are the elucidation of their functions and the identification of the receptors and signaling pathways through which they function.
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Affiliation(s)
- Chris Li
- Department of Biology, City College of New York and The Graduate Center, City University of New York, New York, NY, USA
- *Correspondence: Chris Li, 160 Convent Avenue, MR526, New York, NY 10031, USA e-mail: ; Kyuhyung Kim, 333 Techno Jungang-Daero, Hyeonpung-Myeon, Dalseong-Gun, Daegu 711-873, South Korea e-mail:
| | - Kyuhyung Kim
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, South Korea
- *Correspondence: Chris Li, 160 Convent Avenue, MR526, New York, NY 10031, USA e-mail: ; Kyuhyung Kim, 333 Techno Jungang-Daero, Hyeonpung-Myeon, Dalseong-Gun, Daegu 711-873, South Korea e-mail:
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19
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Schroeder NE, Androwski RJ, Rashid A, Lee H, Lee J, Barr MM. Dauer-specific dendrite arborization in C. elegans is regulated by KPC-1/Furin. Curr Biol 2013; 23:1527-35. [PMID: 23932402 PMCID: PMC4671503 DOI: 10.1016/j.cub.2013.06.058] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 06/04/2013] [Accepted: 06/24/2013] [Indexed: 11/17/2022]
Abstract
BACKGROUND Dendrites often display remarkably complex and diverse morphologies that are influenced by developmental and environmental cues. Neuroplasticity in response to adverse environmental conditions entails both hypertrophy and resorption of dendrites. How dendrites rapidly alter morphology in response to unfavorable environmental conditions is unclear. The nematode Caenorhabditis elegans enters into a stress-resistant dauer larval stage in response to an adverse environment. RESULTS Here we show that the IL2 bipolar sensory neurons undergo dendrite arborization and axon remodeling during dauer development. When dauer larvae are returned to favorable environmental conditions, animals resume reproductive development and IL2 dendritic branches retract, leaving behind remnant branches in postdauer L4 and adult animals. The C. elegans furin homolog KPC-1 is required for dauer IL2 dendritic arborization and dauer-specific nictation behavior. KPC-1 is also necessary for dendritic arborization of PVD and FLP sensory neurons. In mammals, furin is essential, ubiquitously expressed, and associated with numerous pathologies, including neurodegenerative diseases. While broadly expressed in C. elegans neurons and epithelia, KPC-1 acts cell autonomously in IL2 neurons to regulate dauer-specific dendritic arborization and nictation. CONCLUSIONS Neuroplasticity of the C. elegans IL2 sensory neurons provides a paradigm to study stress-induced and reversible dendritic branching, and the role of environmental and developmental cues in this process. The newly discovered role of KPC-1 in dendrite morphogenesis provides insight into the function of proprotein convertases in nervous system development.
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Affiliation(s)
- Nathan E Schroeder
- Department of Genetics and The Human Genetics Institute of New Jersey, Rutgers University, 145 Bevier Road, Piscataway, NJ 08854 USA
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20
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Katrib M, Ikin RJ, Brossier F, Robinson M, Slapetova I, Sharman PA, Walker RA, Belli SI, Tomley FM, Smith NC. Stage-specific expression of protease genes in the apicomplexan parasite, Eimeria tenella. BMC Genomics 2012; 13:685. [PMID: 23216867 PMCID: PMC3770453 DOI: 10.1186/1471-2164-13-685] [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] [Received: 08/31/2012] [Accepted: 12/04/2012] [Indexed: 12/28/2022] Open
Abstract
Background Proteases regulate pathogenesis in apicomplexan parasites but investigations of proteases have been largely confined to the asexual stages of Plasmodium falciparum and Toxoplasma gondii. Thus, little is known about proteases in other Apicomplexa, particularly in the sexual stages. We screened the Eimeria tenella genome database for proteases, classified these into families and determined their stage specific expression. Results Over forty protease genes were identified in the E. tenella genome. These were distributed across aspartic (three genes), cysteine (sixteen), metallo (fourteen) and serine (twelve) proteases. Expression of at least fifteen protease genes was upregulated in merozoites including homologs of genes known to be important in host cell invasion, remodelling and egress in P. falciparum and/or T. gondii. Thirteen protease genes were specifically expressed or upregulated in gametocytes; five of these were in two families of serine proteases (S1 and S8) that are over-represented in the coccidian parasites, E. tenella and T. gondii, distinctive within the Apicomplexa because of their hard-walled oocysts. Serine protease inhibitors prevented processing of EtGAM56, a protein from E. tenella gametocytes that gives rise to tyrosine-rich peptides that are incorporated into the oocyst wall. Conclusion Eimeria tenella possesses a large number of protease genes. Expression of many of these genes is upregulated in asexual stages. However, expression of almost one-third of protease genes is upregulated in, or confined to gametocytes; some of these appear to be unique to the Coccidia and may play key roles in the formation of the oocyst wall, a defining feature of this group of parasites.
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Affiliation(s)
- Marilyn Katrib
- Institute for the Biotechnology of Infectious Diseases, University of Technology, Sydney, Broadway, N.S.W. 2007, Australia
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21
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Melo JA, Ruvkun G. Inactivation of conserved C. elegans genes engages pathogen- and xenobiotic-associated defenses. Cell 2012; 149:452-66. [PMID: 22500807 DOI: 10.1016/j.cell.2012.02.050] [Citation(s) in RCA: 281] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 01/02/2012] [Accepted: 02/23/2012] [Indexed: 12/18/2022]
Abstract
The nematode C. elegans is attracted to nutritious bacteria and is repelled by pathogens and toxins. Here we show that RNAi and toxin-mediated disruption of core cellular activities, including translation, respiration, and protein turnover, stimulate behavioral avoidance of normally attractive bacteria. RNAi of these and other essential processes induces expression of detoxification and innate immune effectors, even in the absence of toxins or pathogens. Disruption of core processes in non-neuronal tissues was sufficient to stimulate aversion behavior, revealing a neuroendocrine axis of control that additionally required serotonergic and Jnk kinase signaling pathways. We propose that surveillance pathways overseeing core cellular activities allow animals to detect invading pathogens that deploy toxins and virulence factors to undermine vital host functions. Variation in cellular surveillance and endocrine pathways controlling behavior, detoxification, and immunity selected by past toxin or microbial interactions could underlie aberrant responses to foods, medicines, and microbes.
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Affiliation(s)
- Justine A Melo
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
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22
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Neuropeptide gene families in Caenorhabditis elegans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 692:98-137. [PMID: 21189676 DOI: 10.1007/978-1-4419-6902-6_6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Neuropeptides are short sequences ofamino acids that function in all multicellular organisms to communicate information between cells. The first sequence ofa neuropeptide was reported in 1970' and the number of identified neuropeptides remained relatively small until the 1990s when the DNA sequence of multiple genomes revealed treasure troves ofinformation. Byblasting away at the genome, gene families, the sizes ofwhich were previously unknown, could now be determined. This information has led to an exponential increase in the number of putative neuropeptides and their respective gene families. The molecular biology age greatly benefited the neuropeptide field in the nematode Caenorhabditis elegans. Its genome was among the first to be sequenced and this allowed us the opportunity to screen the genome for neuropeptide genes. Initially, the screeningwas slow, as the Genefinder and BLAST programs had difficulty identifying small genes and peptides. However, as the bioinformatics programs improved, the extent of the neuropeptide gene families in C. elegans gradually emerged.
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23
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Meli VS, Osuna B, Ruvkun G, Frand AR. MLT-10 defines a family of DUF644 and proline-rich repeat proteins involved in the molting cycle of Caenorhabditis elegans. Mol Biol Cell 2010; 21:1648-61. [PMID: 20335506 PMCID: PMC2869372 DOI: 10.1091/mbc.e08-07-0708] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Molting of nematodes involves the synthesis and removal of a collagen-rich exoskeleton. We describe Caenorhabditis elegans MLT-10, which defines a large family of DUF644 and proline-rich repeat proteins. We show that MLT-10 is released from the epidermis during molting and that MLT-10 is involved in renewal of the exoskeleton and development of the epidermis. The molting cycle of nematodes involves the periodic synthesis and removal of a collagen-rich exoskeleton, but the underlying molecular mechanisms are not well understood. Here, we describe the mlt-10 gene of Caenorhabditis elegans, which emerged from a genetic screen for molting-defective mutants sensitized by low cholesterol. MLT-10 defines a large family of nematode-specific proteins comprised of DUF644 and tandem P-X2-L-(S/T)-P repeats. Conserved nuclear hormone receptors promote expression of the mlt-10 gene in the hypodermis whenever the exoskeleton is remade. Further, a MLT-10::mCherry fusion protein is released from the hypodermis to the surrounding matrices and fluids during molting. The fusion protein is also detected in strands near the surface of animals. Both loss-of-function and gain-of-function mutations of mlt-10 impede the removal of old cuticles. However, the substitution mutation mlt-10(mg364), which disrupts the proline-rich repeats, causes the most severe phenotype. Mutations of mlt-10 are also associated with abnormalities in the exoskeleton and improper development of the epidermis. Thus, mlt-10 encodes a secreted protein involved in three distinct but interconnected aspects of the molting cycle. We propose that the molting cycle of C. elegans involves the dynamic assembly and disassembly of MLT-10 and possibly the paralogs of MLT-10.
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Affiliation(s)
- Vijaykumar S Meli
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1737, USA
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24
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Mai K, Sharman PA, Walker RA, Katrib M, De Souza D, McConville MJ, Wallach MG, Belli SI, Ferguson DJP, Smith NC. Oocyst wall formation and composition in coccidian parasites. Mem Inst Oswaldo Cruz 2010; 104:281-9. [PMID: 19430654 DOI: 10.1590/s0074-02762009000200022] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 12/04/2009] [Indexed: 11/22/2022] Open
Abstract
The oocyst wall of coccidian parasites is a robust structure that is resistant to a variety of environmental and chemical insults. This resilience allows oocysts to survive for long periods, facilitating transmission from host to host. The wall is bilayered and is formed by the sequential release of the contents of two specialized organelles - wall forming body 1 and wall forming body 2 - found in the macrogametocyte stage of Coccidia. The oocyst wall is over 90% protein but few of these proteins have been studied. One group is cysteine-rich and may be presumed to crosslink via disulphide bridges, though this is yet to be investigated. Another group of wall proteins is rich in tyrosine. These proteins, which range in size from 8-31 kDa, are derived from larger precursors of 56 and 82 kDa found in the wall forming bodies. Proteases may catalyze processing of the precursors into tyrosine-rich peptides, which are then oxidatively crosslinked in a reaction catalyzed by peroxidases. In support of this hypothesis, the oocyst wall has high levels of dityrosine bonds. These dityrosine crosslinked proteins may provide a structural matrix for assembly of the oocyst wall and contribute to its resilience.
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Affiliation(s)
- Kelly Mai
- Institute for Biotechnology of Infectious Diseases, University of Technology, Sydney, Australia
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25
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Husson SJ, Landuyt B, Nys T, Baggerman G, Boonen K, Clynen E, Lindemans M, Janssen T, Schoofs L. Comparative peptidomics of Caenorhabditis elegans versus C. briggsae by LC-MALDI-TOF MS. Peptides 2009; 30:449-57. [PMID: 18760316 DOI: 10.1016/j.peptides.2008.07.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 07/30/2008] [Accepted: 07/30/2008] [Indexed: 11/21/2022]
Abstract
Neuropeptides are important signaling molecules that function in cell-cell communication as neurotransmitters or hormones to orchestrate a wide variety of physiological conditions and behaviors. These endogenous peptides can be monitored by high throughput peptidomics technologies from virtually any tissue or organism. The neuropeptide complement of the soil nematode Caenorhabditis elegans has been characterized by on-line two-dimensional liquid chromatography and quadrupole time-of-flight tandem mass spectrometry (2D-nanoLC Q-TOF MS/MS). Here, we use an alternative peptidomics approach combining liquid chromatography (LC) with matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry to map the peptide content of C. elegans and another Caenorhabditis species, Caenorhabditis briggsae. This study allows a better annotation of neuropeptide-encoding genes from the C. briggsae genome and provides a promising basis for further evolutionary comparisons.
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Affiliation(s)
- Steven J Husson
- Functional Genomics and Proteomics Unit, Department of Biology, K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
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26
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Yamashita M, Iwasaki K, Doi M. The non-neuronal syntaxin SYN-1 regulates defecation behavior and neural activity in C. elegans through interaction with the Munc13-like protein AEX-1. Biochem Biophys Res Commun 2008; 378:404-8. [PMID: 19028454 DOI: 10.1016/j.bbrc.2008.11.064] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Accepted: 11/09/2008] [Indexed: 11/16/2022]
Abstract
We have previously shown that the AEX-1 protein, which is expressed in postsynaptic muscles, retrogradely regulates presynaptic neural activity at the Caenorhabditis elegans neuromuscular junctions. AEX-1 is similar to vertebrate Munc13-4 protein, suggesting a function for vesicle exocytosis from a kind of cells. Compared to emerging evidences of the role of Munc13 proteins in synaptic vesicle release, however, the precise mechanism for vesicle exocytosis by AEX-1 and Munc13-4 is little understood. Here we have identified SYN-1 as a candidate molecule of AEX-1-dependent vesicle exocytosis from non-neuronal cells. The syn-1 gene encodes a C. elegans syntaxin, which is distantly related to the neuronal syntaxin UNC-64. The syn-1 gene is predominantly expressed in non-neuronal tissues and genetically interacts with aex-1 for presynaptic activity. However, the two proteins did not interact physically in our yeast two-hybrid system and mutational SYN-1 did not bypass the requirement of AEX-1 for the behavioral defects in aex-1 mutants, whereas mutant UNC-64 does in unc-13 mutants. These results suggest that a novel molecular interaction between the AEX-1 and syntaxin may regulate vesicle exocytosis for retrograde signal release.
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Affiliation(s)
- Masahiro Yamashita
- Neuroscience Research Institute, AIST, Tsukuba Central 6, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
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27
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Mahoney TR, Luo S, Round EK, Brauner M, Gottschalk A, Thomas JH, Nonet ML. Intestinal signaling to GABAergic neurons regulates a rhythmic behavior in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2008; 105:16350-5. [PMID: 18852466 PMCID: PMC2570992 DOI: 10.1073/pnas.0803617105] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Indexed: 11/18/2022] Open
Abstract
The Caenorhabditis elegans defecation motor program (DMP) is a highly coordinated rhythmic behavior that requires two GABAergic neurons that synapse onto the enteric muscles. One class of DMP mutants, called anterior body wall muscle contraction and expulsion defective (aex) mutants, exhibits similar defects to those caused by the loss of these two neurons. Here, we demonstrate that aex-2 encodes a G-protein-coupled receptor (GPCR) and aex-4 encodes an exocytic SNAP25 homologue. We found that aex-2 functions in the nervous system and activates a G(s)alpha signaling pathway to regulate defecation. aex-4, on the other hand, functions in the intestinal epithelial cells. Furthermore, we show that aex-5, which encodes a pro-protein convertase, functions in the intestine to regulate the DMP and that its secretion from the intestine is impaired in aex-4 mutants. Activation of the G(s)alpha GPCR pathway in GABAergic neurons can suppress the defecation defect of the intestinal mutants aex-4 and aex-5. Lastly, we demonstrate that activation of GABAergic neurons using the light-gated cation channel channelrhodopsin-2 is sufficient to suppress the behavioral defects of aex-2, aex-4, and aex-5. These results genetically place intestinal genes aex-4 and aex-5 upstream of GABAergic GPCR signaling. We propose a model whereby the intestinal genes aex-4 and aex-5 control the DMP by regulating the secretion of a signal, which activates the neuronal receptor aex-2.
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Affiliation(s)
- Timothy R. Mahoney
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Shuo Luo
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Elaine K. Round
- Department of Genome Sciences, University of Washington, Seattle, WA 98195; and
| | - Martin Brauner
- Institute for Biochemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe-University Frankfurt, D-60439 Frankfurt, Germany
| | - Alexander Gottschalk
- Institute for Biochemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe-University Frankfurt, D-60439 Frankfurt, Germany
| | - James H. Thomas
- Department of Genome Sciences, University of Washington, Seattle, WA 98195; and
| | - Michael L. Nonet
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
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Abstract
The role of neuropeptides in modulating behavior is slowly being elucidated. With the sequencing of the C. elegans genome, the extent of the neuropeptide genes in C. elegans can be determined. To date, 113 neuropeptide genes encoding over 250 distinct neuropeptides have been identified. Of these, 40 genes encode insulin-like peptides, 31 genes encode FMRFamide-related peptides, and 42 genes encode non-insulin, non-FMRFamide-related neuropeptides. As in other systems, C. elegans neuropeptides are derived from precursor molecules that must be post-translationally processed to yield the active peptides. These precursor molecules contain a single peptide, multiple copies of a single peptide, multiple distinct peptides, or any combination thereof. The neuropeptide genes are expressed extensively throughout the nervous system, including in sensory, motor, and interneurons. In addition, some of the genes are also expressed in non-neuronal tissues, such as the somatic gonad, intestine, and vulval hypodermis. To address the effects of neuropeptides on C. elegans behavior, animals in which the different neuropeptide genes are inactivated or overexpressed are being isolated. In a complementary approach the receptors to which the neuropeptides bind are also being identified and examined. Among the knockout animals analyzed thus far, defects in locomotion, dauer formation, egg laying, ethanol response, and social behavior have been reported. These data suggest that neuropeptides have a modulatory role in many, if not all, behaviors in C. elegans.
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Affiliation(s)
- Chris Li
- Department of Biology, City College of New York, New York, NY 10031, USA.
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Husson SJ, Schoofs L. Altered neuropeptide profile of Caenorhabditis elegans lacking the chaperone protein 7B2 as analyzed by mass spectrometry. FEBS Lett 2007; 581:4288-92. [PMID: 17707816 DOI: 10.1016/j.febslet.2007.08.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 07/18/2007] [Accepted: 08/06/2007] [Indexed: 10/23/2022]
Abstract
Cellular synthesis of naturally occurring, bioactive peptides requires the proprotein convertase PC2/EGL-3 for cleavage from the larger peptide precursors. A neuroendocrine chaperone 7B2 is needed for the proteolytical activation of proPC2, as extensively studied in mouse models. To determine the role of its orthologue in Caenorhabditis elegans, we analyzed wild-type and 7B2-null strains by HPLC and matrix-assisted laser desorption ionization time-of-flight mass spectrometry, which allowed the identification of a novel neuropeptide gene, flp-33. The presence and/or absence of some neuropeptides in 7B2-null animals strongly differs form the peptide profile in wild-type, suggesting a specific and determined action of 7B2 in C. elegans.
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Affiliation(s)
- Steven J Husson
- Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
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30
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Liu T, Kim K, Li C, Barr MM. FMRFamide-like neuropeptides and mechanosensory touch receptor neurons regulate male sexual turning behavior in Caenorhabditis elegans. J Neurosci 2007; 27:7174-82. [PMID: 17611271 PMCID: PMC6794584 DOI: 10.1523/jneurosci.1405-07.2007] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Caenorhabditis elegans male mating provides a powerful model to study the relationship between the nervous system, genes, and innate sexual behaviors. Male mating is the most complex behavior exhibited by the nematode C. elegans and involves the steps of response, backing, turning, vulva location, spicule insertion, and sperm transfer. Because neuropeptides are important neural regulators of many complex animal behaviors, we explored the function of the FMRFamide-like neuropeptide (flp) gene family in regulating male copulation. We found that peptidergic signaling mediated by FMRF-amide like neuropeptides (FLPs) FLP-8, FLP-10, FLP-12, and FLP-20 is required for the sensory transduction involved in male turning behavior. flp-8, flp-10, flp-12, and flp-20 mutant males significantly increase repetition of substep(s) of turning behavior compared with wild-type males. Genes controlling neuropeptide processing and secretion in general, including egl-3, egl-21, ida-1, and unc-31, are also required for inhibiting repetitive turning behavior. Neuropeptidergic signaling adjusts the repetitiveness of turning independently of serotonergic modulation of the timing of turning. Surprisingly, the mechanosensitive touch receptor neurons are found to be part of the neural circuitry regulating male turning behavior, indicating the existence of functional dimorphisms in the nervous system with regard to sex-specific behaviors.
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Affiliation(s)
| | - Kyuhyung Kim
- Department of Biology, Boston University, Boston, Massachusetts 02215
| | - Chris Li
- Department of Biology, Boston University, Boston, Massachusetts 02215
| | - Maureen M. Barr
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin–Madison, Madison, Wisconsin 53705, and
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31
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Husson SJ, Janssen T, Baggerman G, Bogert B, Kahn-Kirby AH, Ashrafi K, Schoofs L. Impaired processing of FLP and NLP peptides in carboxypeptidase E (EGL-21)-deficient Caenorhabditis elegans as analyzed by mass spectrometry. J Neurochem 2007; 102:246-60. [PMID: 17564681 DOI: 10.1111/j.1471-4159.2007.04474.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biologically active peptides are synthesized from inactive pre-proproteins or peptide precursors by the sequential actions of processing enzymes. Proprotein convertases cleave the precursor at pairs of basic amino acids, which are then removed from the carboxyl terminus of the generated fragments by a specific carboxypeptidase. Caenorhabditis elegans strains lacking proprotein convertase EGL-3 display a severely impaired neuropeptide profile (Husson et al. 2006, J. Neurochem.98, 1999-2012). In the present study, we examined the role of the C. elegans carboxypeptidase E orthologue EGL-21 in the processing of peptide precursors. More than 100 carboxy-terminally extended neuropeptides were detected in egl-21 mutant strains. These findings suggest that EGL-21 is a major carboxypeptidase involved in the processing of FMRFamide-like peptide (FLP) precursors and neuropeptide-like protein (NLP) precursors. The impaired peptide profile of egl-3 and egl-21 mutants is reflected in some similar phenotypes. They both share a severe widening of the intestinal lumen, locomotion defects, and retention of embryos. In addition, egl-3 animals have decreased intestinal fat content. Taken together, these results suggest that EGL-3 and EGL-21 are key enzymes for the proper processing of neuropeptides that control egg-laying, locomotion, fat storage and the nutritional status.
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Affiliation(s)
- Steven J Husson
- Functional Genomics and Proteomics Unit, Department of Biology, Katholieke Universiteit Leuven, Leuven, Belgium.
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32
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Poole CB, Jin J, McReynolds LA. Subtilisin-like proteases in nematodes. Mol Biochem Parasitol 2007; 155:1-8. [PMID: 17570539 DOI: 10.1016/j.molbiopara.2007.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 04/30/2007] [Accepted: 05/01/2007] [Indexed: 11/30/2022]
Abstract
Cleavage by subtilisin-like proteases (subtilases) is an essential step in post-translational processing of proteins found in organisms ranging from yeast to mammals. Our knowledge of the diversity of this protease family in nematodes is aided by the rapid increase in sequence information, especially from the Brugia malayi genome project. Genetic studies of the subtilases in Caenorhabitis elegans give valuable insight into the biological function of these proteases in other nematode species. In this review, we focus on the subtilases in filarial nematodes as well as other parasitic and free-living nematodes in comparison to what is known in C. elegans. Topics to be addressed include expansion and diversity of the subtilase gene family during evolution, enhanced complexity created by alternative RNA splicing, molecular and biochemical characterization of the different subtilases and the challenges of designing subtilase-specific inhibitors for parasitic nematodes.
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33
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Husson SJ, Mertens I, Janssen T, Lindemans M, Schoofs L. Neuropeptidergic signaling in the nematode Caenorhabditis elegans. Prog Neurobiol 2007; 82:33-55. [PMID: 17383075 DOI: 10.1016/j.pneurobio.2007.01.006] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 12/14/2006] [Accepted: 01/29/2007] [Indexed: 11/25/2022]
Abstract
The nematode Caenorhabditis elegans joins the menagerie of behavioral model systems next to the fruit fly Drosophila melanogaster, the marine snail Aplysia californica and the mouse. In contrast to Aplysia, which contains 20,000 neurons having cell bodies of hundreds of microns in diameter, C. elegans harbors only 302 tiny neurons from which the cell lineage is completely described, as is the case for all the other somatic cells. As such, this nervous system appears at first sight incommensurable with those of higher organisms, although genome-wide comparison of predicted C. elegans genes with their counterparts in vertebrates revealed many parallels. Together with its short lifespan and ease of cultivation, suitability for high-throughput genetic screenings and genome-wide RNA interference approaches, access to an advanced genetic toolkit and cell-ablation techniques, it seems that this tiny transparent organism of only 1mm in length has nothing to hide. Recently, highly exciting developments have occurred within the field of neuropeptidergic signaling in C. elegans, not only because of the availability of a sequenced genome since 1998, but especially because of state of the art post genomic technologies, that allow for molecular characterization of the signaling molecules. Here, we will focus on endogenous, bioactive (neuro)peptides and mainly discuss biosynthesis, peptide sequence information, localization and G-protein coupled receptors of the three major peptide families in C. elegans.
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Affiliation(s)
- Steven J Husson
- Functional Genomics and Proteomics Unit, Department of Biology, Katholieke Universiteit Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
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34
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Husson SJ, Clynen E, Baggerman G, Janssen T, Schoofs L. Defective processing of neuropeptide precursors in Caenorhabditis elegans lacking proprotein convertase 2 (KPC-2/EGL-3): mutant analysis by mass spectrometry. J Neurochem 2006; 98:1999-2012. [PMID: 16945111 DOI: 10.1111/j.1471-4159.2006.04014.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Biologically active peptides are synthesized as larger inactive proprotein peptide precursors which are processed by the concerted action of a cascade of enzymes. Among the proprotein convertases, PC2 is widely expressed in neuro-endocrine tissues and has been proposed to be the major convertase involved in the biosynthesis of neuropeptides. In this study, we have examined the role of the Caenorhabditis elegans orthologue PC2/EGL-3 in the processing of proprotein peptide precursors. We recently isolated and identified 60 endogenous peptides in the nematode C. elegans by two-dimensional nanoscale liquid chromatography - quadrupole time-of-flight tandem mass spectrometry. In the present study, we compare the peptide profile of different C. elegans strains, including PC2/EGL-3 mutants. For this purpose, we used an offline approach in which HPLC fractions are analysed by a matrix-assisted laser desorption ionisation - time of flight mass spectrometer. This differential peptidomic approach unambiguously provides evidence for the role of PC2/EGL-3 in the processing of FMRFamide-like peptide (FLP) precursors and neuropeptide-like protein (NLP) precursors in nematodes.
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Affiliation(s)
- Steven J Husson
- Laboratory of Developmental Physiology, Genomics and Proteomics, Katholieke Universiteit Leuven, Leuven, Belgium.
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35
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Ford L, Guiliano DB, Oksov Y, Debnath AK, Liu J, Williams SA, Blaxter ML, Lustigman S. Characterization of a Novel Filarial Serine Protease Inhibitor, Ov-SPI-1, from Onchocerca volvulus, with Potential Multifunctional Roles during Development of the Parasite. J Biol Chem 2005; 280:40845-56. [PMID: 16186127 DOI: 10.1074/jbc.m504434200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A novel filarial serine protease inhibitor (SPI) from the human parasitic nematode Onchocerca volvulus, Ov-SPI-1, was identified through the analysis of a molting third-stage larvae expressed sequence tag dataset. Subsequent analysis of the expressed sequence tag datasets of O. volvulus and other filariae identified four other members of this family. These proteins are related to the low molecular weight SPIs originally isolated from Ascaris suum where they are believed to protect the parasite from host intestinal proteases. The two Ov-spi transcripts are up-regulated in the molting larvae and adult stages of the development of the parasite. Recombinant Ov-SPI-1 is an active inhibitor of serine proteases, specifically elastase, chymotrypsin, and cathepsin G. Immunolocalization of the Ov-SPI proteins demonstrates that the endogenous proteins are localized to the basal layer of the cuticle of third-stage, molting third-stage, and fourth-stage larvae, the body channels and multivesicular bodies of third-stage larvae and the processed material found between the two cuticles during molting. In O. volvulus adult worms the Ov-SPI proteins are localized to the sperm and to eggshells surrounding the developing embryos. RNA interference targeting the Ov-spi genes resulted in the specific knockdown of the transcript levels of both Ov-spi-1 and Ov-spi-2, a loss of native proteins, and a significant reduction in both molting and viability of third-stage larvae. We suggest the Ov-SPI proteins play a vital role in nematode molting by controlling the activity of an endogenous serine protease(s). The localization data in adults also indicate that these inhibitors may be involved in other processes such as embryogenesis and spermatogenesis.
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Affiliation(s)
- Louise Ford
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York 10021, USA
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36
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Abstract
A current challenge in neuroscience is to bridge the gaps between genes, proteins, neurons, neural circuits, and behavior in a single animal model. The nematode Caenorhabditis elegans has unique features that facilitate this synthesis. Its nervous system includes exactly 302 neurons, and their pattern of synaptic connectivity is known. With only five olfactory neurons, C. elegans can dynamically respond to dozens of attractive and repellent odors. Thermosensory neurons enable the nematode to remember its cultivation temperature and to track narrow isotherms. Polymodal sensory neurons detect a wide range of nociceptive cues and signal robust escape responses. Pairing of sensory stimuli leads to long-lived changes in behavior consistent with associative learning. Worms exhibit social behaviors and complex ultradian rhythms driven by Ca(2+) oscillators with clock-like properties. Genetic analysis has identified gene products required for nervous system function and elucidated the molecular and neural bases of behaviors.
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Affiliation(s)
- Mario de Bono
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
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37
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Zahn TR, Angleson JK, MacMorris MA, Domke E, Hutton JF, Schwartz C, Hutton JC. Dense core vesicle dynamics in Caenorhabditis elegans neurons and the role of kinesin UNC-104. Traffic 2005; 5:544-59. [PMID: 15180830 DOI: 10.1111/j.1600-0854.2004.00195.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have developed a model system in Caenorhabditis elegans to perform genetic and molecular analysis of peptidergic neurotransmission using green fluorescent protein (GFP)-tagged IDA-1. IDA-1 represents the nematode ortholog of the transmembrane proteins ICA512 and phogrin that are localized to dense core secretory vesicles (DCVs) of mammalian neuroendocrine tissues. IDA-1::GFP was expressed in a small subset of neurons and present in both axonal and dendritic extensions, where it was localized to small mobile vesicular elements that at the ultrastructural level corresponded to 50 nm electron-dense objects in the neuronal processes. The post-translational processing of IDA-1::GFP in transgenic worms was dependent on the neuropeptide proprotein convertase EGL-3, indicating that the protein was efficiently targeted to the peptidergic secretory pathway. Time-lapse epifluorescence microscopy of IDA-1::GFP revealed that DCVs moved in a saltatory and bidirectional manner. DCV velocity profiles exhibited multiple distinct peaks, suggesting the participation of multiple molecular motors with distinct properties. Differences between velocity profiles for axonal and dendritic processes furthermore suggested a polarized distribution of the molecular transport machinery. Study of a number of candidate mutants identified the kinesin UNC-104 (KIF1A) as the microtubule motor that is specifically responsible for anterograde axonal transport of DCVs at velocities of 1.6 microm/s-2.7 microm/s.
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Affiliation(s)
- Tobias R Zahn
- Barbara Davis Center for Childhood Diabetes and Department of Biochemistry and Molecular Genetics, University of Colorado Health Sciences Center, Denver, CO 80262, USA
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38
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Osterwalder T, Kuhnen A, Leiserson WM, Kim YS, Keshishian H. Drosophila serpin 4 functions as a neuroserpin-like inhibitor of subtilisin-like proprotein convertases. J Neurosci 2004; 24:5482-91. [PMID: 15201320 PMCID: PMC6729332 DOI: 10.1523/jneurosci.5577-03.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The proteolytic processing of neuropeptide precursors is believed to be regulated by serine proteinase inhibitors, or serpins. Here we describe the molecular cloning and functional expression of a novel member of the serpin family, Serine protease inhibitor 4 (Spn4), that we propose is involved in the regulation of peptide maturation in Drosophila. The Spn4 gene encodes at least two different serpin proteins, generated by alternate splicing of the last coding exon. The closest vertebrate homolog to Spn4 is neuroserpin. Like neuroserpin, one of the Spn4 proteins (Spn4.1) features a unique C-terminal extension, reminiscent of an endoplasmic reticulum (ER) retention signal; however, Spn4.1 and neuroserpin have divergent reactive site loops, with Spn4.1 showing a generic recognition site for furin/SPC1, the founding member of the intracellularly active family of subtilisin-like proprotein convertases (SPCs). In vitro, Spn4.1 forms SDS-stable complexes with the SPC furin and directly inhibits it. When Spn4.1 is overexpressed in specific peptidergic cells of Drosophila larvae, the animals exhibit a phenotype consistent with disrupted neuropeptide processing. This observation, together with the unique combination of an ER-retention signal, a target sequence for SPCs in the reactive site loop, and the in vitro inhibitory activity against furin, strongly suggests that Spn4.1 is an intracellular regulator of SPCs.
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Affiliation(s)
- Thomas Osterwalder
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8103, USA
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39
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Ogiwara K, Shinohara M, Takahashi T. Expression of proprotein convertase 2 mRNA in the ovarian follicles of the medaka, Oryzias latipes. Gene 2004; 337:79-89. [PMID: 15276204 DOI: 10.1016/j.gene.2004.04.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Revised: 03/29/2004] [Accepted: 04/13/2004] [Indexed: 12/01/2022]
Abstract
Proprotein convertases (PCs) are enzymes responsible for processing the precursors of many bioactive peptides in vertebrates and invertebrates. In the present study, a cDNA for proprotein convertase 2 (PC2) was cloned for the first time from a fish. The clone, which was isolated from the ovary of the medaka, Oryzias latipes, by a combination of RT-PCR cloning and 5'- and 3'-rapid amplification of cDNA ends, codes for a protein of 641 amino acid residues highly homologous to other vertebrate PC2. The medaka preproPC2 consists of a signal sequence, a propeptide with sites for autocatalytic activation, a Kex2-like catalytic domain, and a P-domain. The catalytic triad residues (Asp-169, His-210, and Ser-386) were all conserved. Northern blot analysis revealed that PC2 was expressed in the brain, ovary, and kidney of the fish. The size of PC2 mRNA expressed in the ovary was 2.3 kb, whereas those of the brain and kidney were 2.8 kb. This size difference was attributed to the lack of an approximately 300-bp nucleotide sequence just before the poly(A)+ tail of the ovarian PC2 mRNA. Ovarian expression of the PC2 gene was found in the medaka but not in the mouse, and therefore further analysis was conducted for the fish ovary. The greatest expression of PC2 mRNA in the oocytes of small growing follicles in the mature medaka was demonstrated by Northern blotting, RT-PCR and in situ hybridization analysis. These results suggest that PC2 may play a role in the processing of proproteins and/or pro-hormones expressed in the growing oocytes.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Female
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Enzymologic
- Male
- Molecular Sequence Data
- Oryzias/genetics
- Ovarian Follicle/enzymology
- Ovarian Follicle/growth & development
- Ovarian Follicle/metabolism
- Proprotein Convertase 2/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
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Affiliation(s)
- Katsueki Ogiwara
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
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40
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Rozan L, Krysan DJ, Rockwell NC, Fuller RS. Plasticity of Extended Subsites Facilitates Divergent Substrate Recognition by Kex2 and Furin. J Biol Chem 2004; 279:35656-63. [PMID: 15159396 DOI: 10.1074/jbc.m405362200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast Kex2 and human furin are subtilisin-related proprotein convertases that function in the late secretory pathway and exhibit similar though distinguishable patterns of substrate recognition. Although both enzymes prefer Arg at P(1) and basic residues at P(2), the two differ in recognition of P(4) and P(6) residues. To probe P(4) and P(6) recognition by Kex2p, furin-like substitutions were made in the putative S(4) and S(6) subsites of Kex2. T252D and Q283E mutations were introduced to increase the preference for Arg at P(4) and P(6), respectively. Glu(255) was replaced with Ile to limit recognition of P(4) Arg. The effects of putative S(4) and S(6) mutations were determined by examining the cleavage by purified mutant enzymes of a series of fluorogenic substrates with systematic changes in P(4) and/or P(6). Whereas wild Kex2 exhibited little preference type for Arg at P(6), the T252D mutant and T252D/Q283E double mutant exhibited clear interactions with P(6) Arg. Moreover, the T252D and T252D/Q283E substitutions altered the influence of the P(6) residue on P(4) recognition. We infer that cross-talk between S(4) and S(6), not seen in furin, allows wild type and mutant forms of Kex2 to adapt their subsites for altered modes of recognition. This apparent plasticity may allow the subsites to rearrange their local environment to interact with different substrates in a productive manner. E255I-Kex2 exhibited significantly decreased recognition of P(4) Arg in a tetrapeptide substrate with Lys at P(1), although the general pattern of selectivity for aliphatic residues at P(4) remained unchanged.
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Affiliation(s)
- Laura Rozan
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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41
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Page AP, Winter AD. Enzymes involved in the biogenesis of the nematode cuticle. ADVANCES IN PARASITOLOGY 2003; 53:85-148. [PMID: 14587697 DOI: 10.1016/s0065-308x(03)53003-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Nematodes include species that are significant parasites of man, his domestic animals and crops, and cause chronic debilitating diseases in the developing world; such as lymphatic filariasis and river blindness caused by filarial species. Around one third of the World's population harbour parasitic nematodes; no vaccines exist for prevention of infection, limited effective drugs are available and drug resistance is an ever-increasing problem. A critical structure of the nematode is the protective cuticle, a collagen-rich extracellular matrix (ECM) that forms the exoskeleton, and is critical for viability. This resilient structure is synthesized sequentially five times during nematode development and offers protection from the environment, including the hosts' immune response. The detailed characterization of this complex structure; it's components, and the means by which they are synthesized, modified, processed and assembled will identify targets that may be exploited in the future control of parasitic nematodes. This review will focus on the nematode cuticle. This structure is predominantly composed of collagens, a class of proteins that are modified by a range of co- and post-translational modifications prior to assembly into higher order complexes or ECMs. The collagens and their associated enzymes have been comprehensively characterized in vertebrate systems and some of these studies will be addressed in this review. Conversely, the biosynthesis of this class of essential structural proteins has not been studied in such detail in the nematodes. As with all morphogenetic, functional and developmental studies in the Nematoda phylum, the free-living species Caenorhabditis elegans has proven to be invaluable in the characterization of the cuticle and the cuticle collagen gene family, and is now proving to be an excellent model in the study of cuticle collagen biosynthetic enzymes. This model system will be the main focus of this review.
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Affiliation(s)
- Antony P Page
- Wellcome Centre for Molecular Parasitology, The Anderson College, The University of Glasgow, Glasgow G11 6NU, UK
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42
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Poole CB, Jin J, McReynolds LA. Cloning and biochemical characterization of blisterase, a subtilisin-like convertase from the filarial parasite, Onchocerca volvulus. J Biol Chem 2003; 278:36183-90. [PMID: 12855702 DOI: 10.1074/jbc.m302601200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Blisterase is a subtilisin-like proprotein convertase of nematodes. The enzyme is named after the blistered cuticle found in Caenorhabditis elegans with the bli-4 e937 mutation. The critical role of the enzyme in cuticle production makes it a potential drug target for parasitic nematodes. We have cloned and expressed blisterase from the parasitic nematode Onchocerca volvulus, a major cause of blindness in Africa. The catalytic domain of the protease exhibits 84% identity with the corresponding domain of its closest homologue, C. elegans blisterase. O. volvulus blisterase expressed in insect cells has maximal activity in 1 mm calcium at neutral pH. The protease is inhibited by EDTA, the suicide substrate decanoyl-RVKR-chloromethylketone, alpha1-antitrypsin Portland and by its own propeptide. Substrate assays with fluorescent peptides show that O. volvulus blisterase requires a P4 arginine and a basic amino acid at P1 for cleavage. The kcat of blisterase on the peptide substrate, t-butyloxycarbonyl-RVRR-4-methylcoumaryl-7-amide was determined to be 0.018 s-1. In vitro cleavage studies with the nematode polyprotein antigen demonstrated that blisterase cleaved at tetrabasic (RRKR) but not at dibasic (KR) sites. This report describes the first biochemical characterization of the nematode specific protease, blisterase.
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Affiliation(s)
- Catherine B Poole
- Molecular Parasitology Division, New England Biolabs, Beverly, Massachusetts 01915, USA
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43
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The EGL-21 carboxypeptidase E facilitates acetylcholine release at Caenorhabditis elegans neuromuscular junctions. J Neurosci 2003. [PMID: 12657671 DOI: 10.1523/jneurosci.23-06-02122.2003] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Proneuropeptides are packaged into dense-core vesicles in which they are processed into active peptides by copackaged enzymes. Proprotein convertases (PCs) cleave precursors after dibasic residues, and carboxypeptidases remove basic residues from the C terminals. We show here that the Caenorhabditis elegans egl-21 gene encodes a protein that is very similar to carboxypeptidase E (CPE) and is broadly expressed in the nervous system. Mutants lacking either egl-21 CPE or egl-3, which encodes the C. elegans ortholog of PC type 2 (PC2), were defective for processing endogenously expressed FMRFamide (Phe-Met-Arg-Phe-NH2)-related peptides (FaRPs). Mutants lacking the unc-104 kinesin motor protein were defective for anterograde movement of dense-core vesicle components, including egl-3 PC2, egl-21 CPE, and FaRPs. We provide evidence that egl-3 PC2 and egl-21 CPE mutants have diminished acetylcholine release at neuromuscular junctions (NMJs). Taken together, these results suggest that egl-21 CPE and egl-3 PC2 process endogenous neuropeptides that facilitate acetylcholine release at C. elegans NMJs.
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44
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Lesage G, Guimond J, Boileau G. trans-Complementation assay establishes the role of proregion hydrophobic amino acid residues in the biosynthesis of Saccharomyces cerevisiae Kex2p endoprotease. Yeast 2003; 20:397-406. [PMID: 12673623 DOI: 10.1002/yea.972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The proregion of Saccharomyces cerevisiae endoprotease Kex2p is essential for the biosynthesis of an active enzyme. It has been suggested that the proregion acts in the endoplasmic reticulum to catalyse folding of the enzyme. To identify amino acid residues important for proregion function, we used an in vivo system in which the Kex2p proregion can act in trans to activate a Kex2p enzyme synthesized without its proregion. Activation of Kex2p by wild-type and mutated proregions revealed the essential role of hydrophobic residues F(37), V(39) and F(70) in enzyme activation. Further exploration of the role of these residues by in vitro inhibition of Kex2p activity by its proregion indicated that they are essential to form the proregion/enzyme bimolecular complex. In contrast, basic residues K(108) and R(109), located in the C-terminus of the proregion, are not involved in complex formation but are necessary for the biosynthesis of an active enzyme.
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Affiliation(s)
- Guillaume Lesage
- Département de Biochimie, Université de Montréal, Montréal (Québec) H3C 3J7, Canada
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Li W, Kennedy SG, Ruvkun G. daf-28 encodes a C. elegans insulin superfamily member that is regulated by environmental cues and acts in the DAF-2 signaling pathway. Genes Dev 2003; 17:844-58. [PMID: 12654727 PMCID: PMC196030 DOI: 10.1101/gad.1066503] [Citation(s) in RCA: 263] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In Caenorhabditis elegans, the decision to enter a developmentally arrested dauer larval stage is triggered by a combination of signals from sensory neurons in response to environmental cues, which include a dauer pheromone. These sensory inputs are coupled to the parallel DAF-2/insulin receptor-like and DAF-7/TGFbeta-like signaling pathways. Although sensory inputs have been shown to physiologically regulate DAF-7/TGFbeta expression, no such regulation of insulin-like ligands in the DAF-2 pathway has been reported. We show here that daf-28 encodes an insulin-like protein, which when mutated causes dauer arrest and down-regulation of DAF-2/IR signaling. A daf-28GFP fusion gene is expressed in ASI and ASJ, two sensory neurons that regulate dauer arrest. daf-28GFP expression in ASI and ASJ is down-regulated under dauer-inducing conditions and in mutants of DAF-11/guanylyl cyclase, a predicted component of the dauer-pheromone-sensing pathway. Thus, daf-28 expression in sensory neurons is regulated by the environmental cues that normally trigger dauer arrest. Among the 38 C. elegans insulin genes, daf-28 is so far the only insulin mutant to affect dauer arrest. daf-28 was revealed from this functional redundancy by a dominant-negative allele that disrupts a probable proteolytic processing site required for insulin maturation. This DAF-28 mutant is likely to be poisonous to wild-type DAF-28 and other insulins.
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Affiliation(s)
- Weiqing Li
- Department of Molecular Biology, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
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Francis MM, Mellem JE, Maricq AV. Bridging the gap between genes and behavior: recent advances in the electrophysiological analysis of neural function in Caenorhabditis elegans. Trends Neurosci 2003; 26:90-9. [PMID: 12536132 DOI: 10.1016/s0166-2236(02)00041-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The nematode Caenorhabditis elegans has long been popular with researchers interested in fundamental issues of neural development, sensory processing and behavior. Recently, advances in applying electrophysiological techniques to C. elegans have made this genetically tractable organism considerably more attractive to neurobiologists studying the molecular mechanisms of synaptic organization and function. The development of techniques that involve voltage-clamp of specific neurons and muscles has allowed the coupling of genetic perturbation techniques with electrophysiological analyses of nervous system function. Recent studies combining these biophysical and genetic techniques have provided novel insights into the mechanisms of presynaptic neurotransmitter release, postsynaptic responses to neurotransmitters and information processing by neural circuits.
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Affiliation(s)
- Michael M Francis
- Department of Biology, University of Utah, Salt Lake City 84112, USA
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Thomas G. Furin at the cutting edge: from protein traffic to embryogenesis and disease. Nat Rev Mol Cell Biol 2002; 3:753-66. [PMID: 12360192 PMCID: PMC1964754 DOI: 10.1038/nrm934] [Citation(s) in RCA: 893] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Furin catalyses a simple biochemical reaction--the proteolytic maturation of proprotein substrates in the secretory pathway. But the simplicity of this reaction belies furin's broad and important roles in homeostasis, as well as in diseases ranging from Alzheimer's disease and cancer to anthrax and Ebola fever. This review summarizes various features of furin--its structural and enzymatic properties, intracellular localization, trafficking, substrates, and roles in vivo.
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Affiliation(s)
- Gary Thomas
- Vollum Institute, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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Kovaleva ES, Yakovlev AG, Masler EP, Chitwood DJ. Human proprotein convertase 2 homologue from a plant nematode: cloning, characterization, and comparison with other species. FASEB J 2002; 16:1099-101. [PMID: 12039853 DOI: 10.1096/fj.01-0940fje] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Proprotein convertases (PCs) are evolutionarily conserved enzymes responsible for processing the precursors of many bioactive peptides in mammals. The invertebrate homologues of PC2 play important roles during development that makes the enzyme a good target for practical applications in pest management. Screening of a plant nematode Heterodera glycines cDNA library resulted in isolation of a full-length clone encoding a PC2-like precursor. The deduced protein (74.2 kD) exhibits strong amino acid homology to all known PC2s, including human, and shares the main structural characteristics: signal peptide; prosegment; catalytic domain, with D/H/S catalytic triad, PC2-specific residues, and 7B2 binding sites; P domain (with RRGDT pentapeptide); and carboxyl terminus. Comparative analysis of PC2s from 15 species discloses the presence of an insert in the catalytic domain unique to nematodes. Expression of PC2-like mRNA found in eggs and juveniles was undetectable in adult stages of H. glycines. Nucleotide analysis reveals distinctive differences in base composition and codon usage between H. glycines and Caenorhabditis elegans PC2s. The H. glycines cDNA clone encoding PC2 is the first one isolated from plant-parasitic nematodes.
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Affiliation(s)
- Elena S Kovaleva
- Nematology Laboratory, USDA, ARS/PSI, Beltsville, Maryland 20705-2350, USA.
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Nonet ML. AEXpulsing a retrograde signal. Neuron 2002; 33:155-6. [PMID: 11804562 DOI: 10.1016/s0896-6273(02)00562-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A variety of secreted components have been identified as retrograde signals mediating diverse aspects of synaptic development, maintenance, and plasticity; however, little is known about the mechanisms mediating the release of secreted retrograde signals. Doi and Iwasaki (this issue of Neuron) implicate AEX-1, a protein distantly related to the UNC-13/Munc13 family, as an attractive candidate regulator of the retrograde release machinery in muscle.
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Affiliation(s)
- Michael L Nonet
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
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Doi M, Iwasaki K. Regulation of retrograde signaling at neuromuscular junctions by the novel C2 domain protein AEX-1. Neuron 2002; 33:249-59. [PMID: 11804572 DOI: 10.1016/s0896-6273(01)00587-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Retrograde signaling from postsynaptic cells to presynaptic neurons is essential for regulation of synaptic development, maintenance, and plasticity. Here we report that the novel protein AEX-1 controls retrograde signaling at neuromuscular junctions in C. elegans. aex-1 mutants show neural defects including reduced presynaptic activity and abnormal localization of the synaptic vesicle fusion protein UNC-13. Muscle-specific AEX-1 expression rescues these defects but neuron-specific expression does not. AEX-1 has an UNC-13 homologous domain and appears to regulate exocytosis in muscles. This retrograde signaling requires prohormone-convertase function in muscles, suggesting that a peptide is the retrograde signal. This signal regulates synaptic vesicle release via the EGL-30 Gq(alpha) protein at presynaptic terminals.
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Affiliation(s)
- Motomichi Doi
- Laboratory of Molecular Neurobiology, Neuroscience Research Institute AIST, Tsukuba, 305-8566, Japan
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