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Petersen M, Dubielecka P. Adaptor protein Abelson interactor 1 in homeostasis and disease. Cell Commun Signal 2024; 22:468. [PMID: 39354505 PMCID: PMC11446139 DOI: 10.1186/s12964-024-01738-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/04/2024] [Indexed: 10/03/2024] Open
Abstract
Dysregulation of Abelson interactor 1 (ABI1) is associated with various states of disease including developmental defects, pathogen infections, and cancer. ABI1 is an adaptor protein predominantly known to regulate actin cytoskeleton organization processes such as those involved in cell adhesion, migration, and shape determination. Linked to cytoskeleton via vasodilator-stimulated phosphoprotein (VASP), Wiskott-Aldrich syndrome protein family (WAVE), and neural-Wiskott-Aldrich syndrome protein (N-WASP)-associated protein complexes, ABI1 coordinates regulation of various cytoplasmic protein signaling complexes dysregulated in disease states. The roles of ABI1 beyond actin cytoskeleton regulation are much less understood. This comprehensive, protein-centric review describes molecular roles of ABI1 as an adaptor molecule in the context of its dysregulation and associated disease outcomes to better understand disease state-specific protein signaling and affected interconnected biological processes.
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Affiliation(s)
- Max Petersen
- Division of Hematology/Oncology, Department of Medicine, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI, USA
- Center for the Biology of Aging, Brown University, Providence, RI, USA
- Legoretta Cancer Center, Brown University, Providence, RI, USA
| | - Pat Dubielecka
- Division of Hematology/Oncology, Department of Medicine, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI, USA.
- Center for the Biology of Aging, Brown University, Providence, RI, USA.
- Legoretta Cancer Center, Brown University, Providence, RI, USA.
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2
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Chaudhari K, Zhang K, Yam PT, Zang Y, Kramer DA, Gagnon S, Schlienger S, Calabretta S, Michaud JF, Collins M, Wang J, Srour M, Chen B, Charron F, Bashaw GJ. A human DCC variant causing mirror movement disorder reveals that the WAVE regulatory complex mediates axon guidance by netrin-1-DCC. Sci Signal 2024; 17:eadk2345. [PMID: 39353037 PMCID: PMC11568466 DOI: 10.1126/scisignal.adk2345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 05/06/2024] [Accepted: 09/06/2024] [Indexed: 10/04/2024]
Abstract
The axon guidance cue netrin-1 signals through its receptor DCC (deleted in colorectal cancer) to attract commissural axons to the midline. Variants in DCC are frequently associated with congenital mirror movements (CMMs). A CMM-associated variant in the cytoplasmic tail of DCC is located in a conserved motif predicted to bind to a regulator of actin dynamics called the WAVE (Wiskott-Aldrich syndrome protein-family verprolin homologous protein) regulatory complex (WRC). Here, we explored how this variant affects DCC function and may contribute to CMM. We found that a conserved WRC-interacting receptor sequence (WIRS) motif in the cytoplasmic tail of DCC mediated the interaction between DCC and the WRC. This interaction was required for netrin-1-mediated axon guidance in cultured rodent commissural neurons. Furthermore, the WIRS motif of Fra, the Drosophila DCC ortholog, was required for attractive signaling in vivo at the Drosophila midline. The CMM-associated R1343H variant of DCC, which altered the WIRS motif, prevented the DCC-WRC interaction and impaired axon guidance in cultured commissural neurons and in Drosophila. The findings reveal the WRC as a pivotal component of netrin-1-DCC signaling and uncover a molecular mechanism explaining how a human genetic variant in the cytoplasmic tail of DCC may lead to CMM.
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Affiliation(s)
- Karina Chaudhari
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- These authors contributed equally
| | - Kaiyue Zhang
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC, H2W 1R7, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, QC, H3A 2B4, Canada
- These authors contributed equally
| | - Patricia T. Yam
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC, H2W 1R7, Canada
| | - Yixin Zang
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Daniel A. Kramer
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Sarah Gagnon
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Sabrina Schlienger
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC, H2W 1R7, Canada
- Department of Anatomy and Cell Biology, Division of Experimental Medicine, McGill University, Montreal, QC, H3A 0G4, Canada
| | - Sara Calabretta
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC, H2W 1R7, Canada
| | - Jean-Francois Michaud
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC, H2W 1R7, Canada
| | - Meagan Collins
- McGill University Health Center Research Institute, Montreal, QC, H4A 3J1, Canada
| | - Junmei Wang
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Myriam Srour
- Department of Neurology and Neurosurgery, McGill University, Montreal, H3A 2B4, Quebec, Canada
- Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montreal, QC, H4A 3J1, Canada
- McGill University Health Center Research Institute, Montreal, QC, H4A 3J1, Canada
| | - Baoyu Chen
- Roy J. Carver Department of Biochemistry, Biophysics & Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - Frédéric Charron
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC, H2W 1R7, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, QC, H3A 2B4, Canada
- Department of Anatomy and Cell Biology, Division of Experimental Medicine, McGill University, Montreal, QC, H3A 0G4, Canada
- Department of Medicine, University of Montreal, Montreal, QC, H3T 1J4, Canada
| | - Greg J. Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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Puri D, Sharma S, Samaddar S, Ravivarma S, Banerjee S, Ghosh-Roy A. Muscleblind-1 interacts with tubulin mRNAs to regulate the microtubule cytoskeleton in C. elegans mechanosensory neurons. PLoS Genet 2023; 19:e1010885. [PMID: 37603562 PMCID: PMC10470942 DOI: 10.1371/journal.pgen.1010885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 08/31/2023] [Accepted: 07/26/2023] [Indexed: 08/23/2023] Open
Abstract
Regulation of the microtubule cytoskeleton is crucial for the development and maintenance of neuronal architecture, and recent studies have highlighted the significance of regulated RNA processing in the establishment and maintenance of neural circuits. In a genetic screen conducted using mechanosensory neurons of C. elegans, we identified a mutation in muscleblind-1/mbl-1 as a suppressor of loss of kinesin-13 family microtubule destabilizing factor klp-7. Muscleblind-1(MBL-1) is an RNA-binding protein that regulates the splicing, localization, and stability of RNA. Our findings demonstrate that mbl-1 is required cell-autonomously for axon growth and proper synapse positioning in the posterior lateral microtubule (PLM) neuron. Loss of mbl-1 leads to increased microtubule dynamics and mixed orientation of microtubules in the anterior neurite of PLM. These defects are also accompanied by abnormal axonal transport of the synaptic protein RAB-3 and reduction of gentle touch sensation in mbl-1 mutant. Our data also revealed that mbl-1 is genetically epistatic to mec-7 (β tubulin) and mec-12 (α tubulin) in regulating axon growth. Furthermore, mbl-1 is epistatic to sad-1, an ortholog of BRSK/Brain specific-serine/threonine kinase and a known regulator of synaptic machinery, for synapse formation at the correct location of the PLM neurite. Notably, the immunoprecipitation of MBL-1 resulted in the co-purification of mec-7, mec-12, and sad-1 mRNAs, suggesting a direct interaction between MBL-1 and these transcripts. Additionally, mbl-1 mutants exhibited reduced levels and stability of mec-7 and mec-12 transcripts. Our study establishes a previously unknown link between RNA-binding proteins and cytoskeletal machinery, highlighting their crucial roles in the development and maintenance of the nervous system.
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Affiliation(s)
- Dharmendra Puri
- National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Sunanda Sharma
- National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Sarbani Samaddar
- National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Sruthy Ravivarma
- National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Sourav Banerjee
- National Brain Research Centre, Manesar, Gurgaon, Haryana, India
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Dailey-Krempel B, Martin AL, Jo HN, Junge HJ, Chen Z. A tug of war between DCC and ROBO1 signaling during commissural axon guidance. Cell Rep 2023; 42:112455. [PMID: 37149867 DOI: 10.1016/j.celrep.2023.112455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/07/2023] [Accepted: 04/14/2023] [Indexed: 05/09/2023] Open
Abstract
Dynamic and coordinated axonal responses to changing environments are critical for establishing neural connections. As commissural axons migrate across the CNS midline, they are suggested to switch from being attracted to being repelled in order to approach and to subsequently leave the midline. A molecular mechanism that is hypothesized to underlie this switch in axonal responses is the silencing of Netrin1/Deleted in Colorectal Carcinoma (DCC)-mediated attraction by the repulsive SLIT/ROBO1 signaling. Using in vivo approaches including CRISPR-Cas9-engineered mouse models of distinct Dcc splice isoforms, we show here that commissural axons maintain responsiveness to both Netrin and SLIT during midline crossing, although likely at quantitatively different levels. In addition, full-length DCC in collaboration with ROBO3 can antagonize ROBO1 repulsion in vivo. We propose that commissural axons integrate and balance the opposing DCC and Roundabout (ROBO) signaling to ensure proper guidance decisions during midline entry and exit.
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Affiliation(s)
| | - Andrew L Martin
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ha-Neul Jo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Harald J Junge
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Zhe Chen
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
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A DNA replication-independent function of pre-replication complex genes during cell invasion in C. elegans. PLoS Biol 2022; 20:e3001317. [PMID: 35192608 PMCID: PMC8863262 DOI: 10.1371/journal.pbio.3001317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 12/01/2021] [Indexed: 11/19/2022] Open
Abstract
Cell invasion is an initiating event during tumor cell metastasis and an essential process during development. A screen of C. elegans orthologs of genes overexpressed in invasive human melanoma cells has identified several components of the conserved DNA pre-replication complex (pre-RC) as positive regulators of anchor cell (AC) invasion. The pre-RC genes function cell-autonomously in the G1-arrested AC to promote invasion, independently of their role in licensing DNA replication origins in proliferating cells. While the helicase activity of the pre-RC is necessary for AC invasion, the downstream acting DNA replication initiation factors are not required. The pre-RC promotes the invasive fate by regulating the expression of extracellular matrix genes and components of the PI3K signaling pathway. Increasing PI3K pathway activity partially suppressed the AC invasion defects caused by pre-RC depletion, suggesting that the PI3K pathway is one critical pre-RC target. We propose that the pre-RC, or a part of it, acts in the postmitotic AC as a transcriptional regulator that facilitates the switch to an invasive phenotype.
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6
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Flynn ED, Tsu AL, Kasela S, Kim-Hellmuth S, Aguet F, Ardlie KG, Bussemaker HJ, Mohammadi P, Lappalainen T. Transcription factor regulation of eQTL activity across individuals and tissues. PLoS Genet 2022; 18:e1009719. [PMID: 35100260 PMCID: PMC8830792 DOI: 10.1371/journal.pgen.1009719] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 02/10/2022] [Accepted: 01/06/2022] [Indexed: 11/18/2022] Open
Abstract
Tens of thousands of genetic variants associated with gene expression (cis-eQTLs) have been discovered in the human population. These eQTLs are active in various tissues and contexts, but the molecular mechanisms of eQTL variability are poorly understood, hindering our understanding of genetic regulation across biological contexts. Since many eQTLs are believed to act by altering transcription factor (TF) binding affinity, we hypothesized that analyzing eQTL effect size as a function of TF level may allow discovery of mechanisms of eQTL variability. Using GTEx Consortium eQTL data from 49 tissues, we analyzed the interaction between eQTL effect size and TF level across tissues and across individuals within specific tissues and generated a list of 10,098 TF-eQTL interactions across 2,136 genes that are supported by at least two lines of evidence. These TF-eQTLs were enriched for various TF binding measures, supporting with orthogonal evidence that these eQTLs are regulated by the implicated TFs. We also found that our TF-eQTLs tend to overlap genes with gene-by-environment regulatory effects and to colocalize with GWAS loci, implying that our approach can help to elucidate mechanisms of context-specificity and trait associations. Finally, we highlight an interesting example of IKZF1 TF regulation of an APBB1IP gene eQTL that colocalizes with a GWAS signal for blood cell traits. Together, our findings provide candidate TF mechanisms for a large number of eQTLs and offer a generalizable approach for researchers to discover TF regulators of genetic variant effects in additional QTL datasets.
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Affiliation(s)
- Elise D. Flynn
- Department of Systems Biology, Columbia University, New York, New York, United States of America
- New York Genome Center, New York, New York, United States of America
| | - Athena L. Tsu
- New York Genome Center, New York, New York, United States of America
- Department of Biomedical Engineering, Columbia University, New York, New York, United States of America
| | - Silva Kasela
- Department of Systems Biology, Columbia University, New York, New York, United States of America
- New York Genome Center, New York, New York, United States of America
| | - Sarah Kim-Hellmuth
- Department of Systems Biology, Columbia University, New York, New York, United States of America
- New York Genome Center, New York, New York, United States of America
- Department of Pediatrics, Dr. von Hauner Children’s Hospital, University Hospital, LMU Munich, Munich, Germany
| | - Francois Aguet
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Kristin G. Ardlie
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Harmen J. Bussemaker
- Department of Systems Biology, Columbia University, New York, New York, United States of America
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Pejman Mohammadi
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, United States of America
- Scripps Translational Science Institute, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail: (PM); (TL)
| | - Tuuli Lappalainen
- Department of Systems Biology, Columbia University, New York, New York, United States of America
- New York Genome Center, New York, New York, United States of America
- KTH Royal Institute of Technology, Stockholm, Sweden
- * E-mail: (PM); (TL)
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Moritz S, Krause M, Schlatter J, Cordes N, Vehlow A. Lamellipodin-RICTOR Signaling Mediates Glioblastoma Cell Invasion and Radiosensitivity Downstream of EGFR. Cancers (Basel) 2021; 13:5337. [PMID: 34771501 PMCID: PMC8582497 DOI: 10.3390/cancers13215337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 11/19/2022] Open
Abstract
Glioblastoma is a tumor type of unmet need despite the development of multimodal treatment strategies. The main factors contributing to the poor prognosis of glioblastoma patients are diverse genetic and epigenetic changes driving glioblastoma persistence and recurrence. Complemented are these factors by extracellular cues mediated through cell surface receptors, which further aid in fostering pro-invasion and pro-survival signaling contributing to glioblastoma therapy resistance. The underlying mechanisms conferring this therapy resistance are poorly understood. Here, we show that the cytoskeleton regulator Lamellipodin (Lpd) mediates invasiveness, proliferation and radiosensitivity of glioblastoma cells. Phosphoproteome analysis identified the epidermal growth factor receptor (EGFR) signaling axis commonly hyperactive in glioblastoma to depend on Lpd. Mechanistically, EGFR signaling together with an interaction between Lpd and the Rapamycin-insensitive companion of mammalian target of rapamycin (RICTOR) jointly regulate glioblastoma radiosensitivity. Collectively, our findings demonstrate an essential function of Lpd in the radiation response and invasiveness of glioblastoma cells. Thus, we uncover a novel Lpd-driven resistance mechanism, which adds an additional critical facet to the complex glioblastoma resistance network.
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Affiliation(s)
- Stefanie Moritz
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, PF 41, 01307 Dresden, Germany; (S.M.); (N.C.)
| | - Matthias Krause
- Randall Centre of Cell and Molecular Biophysics, New Hunt’s House, Guy’s Campus, King’s College London, London SE1 1UL, UK; (M.K.); (J.S.)
| | - Jessica Schlatter
- Randall Centre of Cell and Molecular Biophysics, New Hunt’s House, Guy’s Campus, King’s College London, London SE1 1UL, UK; (M.K.); (J.S.)
| | - Nils Cordes
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, PF 41, 01307 Dresden, Germany; (S.M.); (N.C.)
- Institute of Radiooncology-OncoRay, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
- Department of Radiotherapy and Radiation Oncology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, PF 50, 01307 Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69192 Heidelberg, Germany
| | - Anne Vehlow
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, PF 41, 01307 Dresden, Germany; (S.M.); (N.C.)
- German Cancer Consortium (DKTK), Partner Site Dresden, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69192 Heidelberg, Germany
- National Center for Tumor Diseases (NCT), Partner Site Dresden, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69192 Heidelberg, Germany
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Weaver CJ, Poulain FE. From whole organism to ultrastructure: progress in axonal imaging for decoding circuit development. Development 2021; 148:271122. [PMID: 34328171 DOI: 10.1242/dev.199717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Since the pioneering work of Ramón y Cajal, scientists have sought to unravel the complexities of axon development underlying neural circuit formation. Micrometer-scale axonal growth cones navigate to targets that are often centimeters away. To reach their targets, growth cones react to dynamic environmental cues that change in the order of seconds to days. Proper axon growth and guidance are essential to circuit formation, and progress in imaging has been integral to studying these processes. In particular, advances in high- and super-resolution microscopy provide the spatial and temporal resolution required for studying developing axons. In this Review, we describe how improved microscopy has revolutionized our understanding of axonal development. We discuss how novel technologies, specifically light-sheet and super-resolution microscopy, led to new discoveries at the cellular scale by imaging axon outgrowth and circuit wiring with extreme precision. We next examine how advanced microscopy broadened our understanding of the subcellular dynamics driving axon growth and guidance. We finally assess the current challenges that the field of axonal biology still faces for imaging axons, and examine how future technology could meet these needs.
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Affiliation(s)
- Cory J Weaver
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Fabienne E Poulain
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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9
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Manjarrez JR, Mailler R. Stress and timing associated with Caenorhabditis elegans immobilization methods. Heliyon 2020; 6:e04263. [PMID: 32671240 PMCID: PMC7339059 DOI: 10.1016/j.heliyon.2020.e04263] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/12/2019] [Accepted: 06/17/2020] [Indexed: 12/11/2022] Open
Abstract
Background Caenorhabditis elegans is a model organism used to study gene, protein, and cell influence on function and behavior. These studies frequently require C. elegans to be immobilized for imaging or laser ablation experiments. There are a number of known techniques for immobilizing worms, but to our knowledge, there are no comprehensive studies of the various agents in common use today. New method This study determines the relationship between concentration, immobilization time, exposure time, and recovery likelihood for several immobilization agents. The agents used in this study are 1-Phenoxy-2-propanol, levamisole, sodium azide, polystyrene beads, and environmental cold shock. These tests are conducted using a humidified chamber to keep chemical concentrations consistent. Each of these agents is also tested to determine if they exhibit stress-related after effects using the gcs-1, daf-16, hsp-4, hif-1, hsp-16.2, and tmem-135 stress reporters. Results We present a range of quick mount immobilization and recovery conditions for each agent tested. This study shows that, under controlled conditions, 1-Phenoxy-2-propanol shows significant stress from the daf-16 reporter. While 1-Phenoxy-2-propanol and sodium azide both create stress related after effects with long term recovery in the case of the hsp-16.2 reporter. Comparison with existing method(s) This study shows that commonly used concentrations of immobilizing agents are ineffective when evaporation is prevented. Conclusions To improve reproducibility of results it is essential to use consistent concentrations of immobilizing agents. It is also critically important to account for stress-related after effects elicited by immobilization agents when designing any experiment.
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Affiliation(s)
| | - Roger Mailler
- University of Tulsa, 800 S. Tucker Dr., Tulsa, OK, 74104, USA
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10
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Gallop J. Filopodia and their links with membrane traffic and cell adhesion. Semin Cell Dev Biol 2020; 102:81-89. [DOI: 10.1016/j.semcdb.2019.11.017] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 11/14/2019] [Accepted: 11/28/2019] [Indexed: 01/24/2023]
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Sundararajan L, Smith CJ, Watson JD, Millis BA, Tyska MJ, Miller DM. Actin assembly and non-muscle myosin activity drive dendrite retraction in an UNC-6/Netrin dependent self-avoidance response. PLoS Genet 2019; 15:e1008228. [PMID: 31220078 PMCID: PMC6605669 DOI: 10.1371/journal.pgen.1008228] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/02/2019] [Accepted: 06/04/2019] [Indexed: 01/08/2023] Open
Abstract
Dendrite growth is constrained by a self-avoidance response that induces retraction but the downstream pathways that balance these opposing mechanisms are unknown. We have proposed that the diffusible cue UNC-6(Netrin) is captured by UNC-40(DCC) for a short-range interaction with UNC-5 to trigger self-avoidance in the C. elegans PVD neuron. Here we report that the actin-polymerizing proteins UNC-34(Ena/VASP), WSP-1(WASP), UNC-73(Trio), MIG-10(Lamellipodin) and the Arp2/3 complex effect dendrite retraction in the self-avoidance response mediated by UNC-6(Netrin). The paradoxical idea that actin polymerization results in shorter rather than longer dendrites is explained by our finding that NMY-1 (non-muscle myosin II) is necessary for retraction and could therefore mediate this effect in a contractile mechanism. Our results also show that dendrite length is determined by the antagonistic effects on the actin cytoskeleton of separate sets of effectors for retraction mediated by UNC-6(Netrin) versus outgrowth promoted by the DMA-1 receptor. Thus, our findings suggest that the dendrite length depends on an intrinsic mechanism that balances distinct modes of actin assembly for growth versus retraction. Neurons may extend highly branched dendrites to detect input over a broad receptive field. The formation of actin filaments may drive dendrite elongation. The architecture of the dendritic arbor also depends on mechanisms that limit expansion. For example, sister dendrites from a single neuron usually do not overlap due to self-avoidance. Although cell surface proteins are known to mediate self-avoidance, the downstream pathways that drive dendrite retraction in this phenomenon are largely unknown. Studies of the highly branched PVD sensory neuron in C. elegans have suggested a model of self-avoidance in which the UNC-40/DCC receptor captures the diffusible cue UNC-6/Netrin at the tips of PVD dendrites where it interacts with the UNC-5 receptor on an opposing sister dendrite to induce retraction. Here we report genetic evidence that UNC-5-dependent retraction requires downstream actin polymerization. This finding evokes a paradox: How might actin polymerization drive both dendrite growth and retraction? We propose two answers: (1) Distinct sets of effectors are involved in actin assembly for growth vs retraction; (2) Non-muscle myosin interacts with a nascent actin assemblage to trigger retraction. Our results show that dendrite length depends on the balanced effects of specific molecular components that induce growth vs retraction.
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Affiliation(s)
- Lakshmi Sundararajan
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Cody J. Smith
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Joseph D. Watson
- Neuroscience Graduate Program, Vanderbilt University, Nashville, Nashville, Tennessee, United States of America
| | - Bryan A. Millis
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Cell Imaging Shared Resource, Vanderbilt University, Nashville, Nashville, Tennessee, United States of America
- Vanderbilt Biophotonics Center, Vanderbilt University, Nashville, Nashville, Tennessee, United States of America
| | - Matthew J. Tyska
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - David M. Miller
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Neuroscience Graduate Program, Vanderbilt University, Nashville, Nashville, Tennessee, United States of America
- * E-mail:
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12
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Regulation of Caenorhabditis elegans neuronal polarity by heterochronic genes. Proc Natl Acad Sci U S A 2019; 116:12327-12336. [PMID: 31164416 DOI: 10.1073/pnas.1820928116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Many neurons display characteristic patterns of synaptic connections that are under genetic control. The Caenorhabditis elegans DA cholinergic motor neurons form synaptic connections only on their dorsal axons. We explored the genetic pathways that specify this polarity by screening for gene inactivations and mutations that disrupt this normal polarity of a DA motorneuron. A RAB-3::GFP fusion protein that is normally localized to presynaptic terminals along the dorsal axon of the DA9 motorneuron was used to screen for gene inactivations that disrupt the DA9 motorneuron polarity. This screen identified heterochronic genes as major regulators of DA neuron presynaptic polarity. In many heterochronic mutants, presynapses of this cholinergic motoneuron are mislocalized to the dendrite at the ventral side: inactivation of the blmp-1 transcription factor gene, the lin-29/Zn finger transcription factor, lin-28/RNA binding protein, and the let-7miRNA gene all disrupt the presynaptic polarity of this DA cholinergic neuron. We also show that the dre-1/F box heterochronic gene functions early in development to control maintenance of polarity at later stages, and that a mutation in the let-7 heterochronic miRNA gene causes dendritic misplacement of RAB-3 presynaptic markers that colocalize with muscle postsynaptic terminals ectopically. We propose that heterochronic genes are components in the UNC-6/Netrin pathway of synaptic polarity of these neurons. These findings highlight the role of heterochronic genes in postmitotic neuronal patterning events.
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Sundararajan L, Stern J, Miller DM. Mechanisms that regulate morphogenesis of a highly branched neuron in C. elegans. Dev Biol 2019; 451:53-67. [PMID: 31004567 DOI: 10.1016/j.ydbio.2019.04.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 03/09/2019] [Accepted: 04/05/2019] [Indexed: 02/08/2023]
Abstract
The shape of an individual neuron is linked to its function with axons sending signals to other cells and dendrites receiving them. Although much is known of the mechanisms for axonal outgrowth, the striking complexity of dendritic architecture has hindered efforts to uncover pathways that direct dendritic branching. Here we review the results of an experimental strategy that exploits the power of genetic analysis and live cell imaging of the PVD sensory neuron in C. elegans to reveal key molecular drivers of dendrite morphogenesis.
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Affiliation(s)
- Lakshmi Sundararajan
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Jamie Stern
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - David M Miller
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA.
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14
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Duraikannu A, Krishnan A, Chandrasekhar A, Zochodne DW. Beyond Trophic Factors: Exploiting the Intrinsic Regenerative Properties of Adult Neurons. Front Cell Neurosci 2019; 13:128. [PMID: 31024258 PMCID: PMC6460947 DOI: 10.3389/fncel.2019.00128] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/14/2019] [Indexed: 01/19/2023] Open
Abstract
Injuries and diseases of the peripheral nervous system (PNS) are common but frequently irreversible. It is often but mistakenly assumed that peripheral neuron regeneration is robust without a need to be improved or supported. However, axonal lesions, especially those involving proximal nerves rarely recover fully and injuries generally are complicated by slow and incomplete regeneration. Strategies to enhance the intrinsic growth properties of reluctant adult neurons offer an alternative approach to consider during regeneration. Since axons rarely regrow without an intimately partnered Schwann cell (SC), approaches to enhance SC plasticity carry along benefits to their axon partners. Direct targeting of molecules that inhibit growth cone plasticity can inform important regenerative strategies. A newer approach, a focus of our laboratory, exploits tumor suppressor molecules that normally dampen unconstrained growth. However several are also prominently expressed in stable adult neurons. During regeneration their ongoing expression “brakes” growth, whereas their inhibition and knockdown may enhance regrowth. Examples have included phosphatase and tensin homolog deleted on chromosome ten (PTEN), a tumor suppressor that inhibits PI3K/pAkt signaling, Rb1, the protein involved in retinoblastoma development, and adenomatous polyposis coli (APC), a tumor suppressor that inhibits β-Catenin transcriptional signaling and its translocation to the nucleus. The identification of several new targets to manipulate the plasticity of regenerating adult peripheral neurons is exciting. How they fit with canonical regeneration strategies and their feasibility require additional work. Newer forms of nonviral siRNA delivery may be approaches for molecular manipulation to improve regeneration.
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Affiliation(s)
- Arul Duraikannu
- Division of Neurology, Department of Medicine, and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Anand Krishnan
- Division of Neurology, Department of Medicine, and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Ambika Chandrasekhar
- Division of Neurology, Department of Medicine, and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Douglas W Zochodne
- Division of Neurology, Department of Medicine, and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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15
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Limerick G, Tang X, Lee WS, Mohamed A, Al-Aamiri A, Wadsworth WG. A Statistically-Oriented Asymmetric Localization (SOAL) Model for Neuronal Outgrowth Patterning by Caenorhabditis elegans UNC-5 (UNC5) and UNC-40 (DCC) Netrin Receptors. Genetics 2018; 208:245-272. [PMID: 29092889 PMCID: PMC5753861 DOI: 10.1534/genetics.117.300460] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 10/29/2017] [Indexed: 01/01/2023] Open
Abstract
Neurons extend processes that vary in number, length, and direction of "outgrowth". Extracellular cues help determine outgrowth patterns. In Caenorhabditis elegans, neurons respond to the extracellular UNC-6 (netrin) cue via UNC-40 (DCC) and UNC-5 (UNC5) receptors. Previously, we presented evidence that UNC-40 asymmetric localization at the plasma membrane is self-organizing, and that UNC-40 can localize and mediate outgrowth at randomly selected sites. Here, we provide further evidence for a statistically-oriented asymmetric localization (SOAL) model in which UNC-5 receptor activity affects patterns of axon outgrowth by regulating UNC-40 asymmetric localization. According to the SOAL model, the direction of outgrowth activity fluctuates across the membrane over time. Random walk modeling predicts that increasing the degree to which the direction of outgrowth fluctuates will decrease the outward displacement of the membrane. By differentially affecting the degree to which the direction of outgrowth activity fluctuates over time, extracellular cues can produce different rates of outgrowth along the surface and create patterns of "extension". Consistent with the SOAL model, we show that unc-5 mutations alter UNC-40 asymmetric localization, increase the degree to which the direction of outgrowth fluctuates, and reduce the extent of outgrowth in multiple directions relative to the source of UNC-6 These results are inconsistent with current models, which predict that UNC-5 mediates a "repulsive" response to UNC-6 Genetic interactions suggest that UNC-5 acts through the UNC-53 (NAV2) cytoplasmic protein to regulate UNC-40 asymmetric localization in response to both the UNC-6 and EGL-20 (Wnt) extracellular cues.
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Affiliation(s)
- Gerard Limerick
- Department of Pathology and Laboratory Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Xia Tang
- Department of Pathology and Laboratory Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Won Suk Lee
- Department of Pathology and Laboratory Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Ahmed Mohamed
- Department of Pathology and Laboratory Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - Aseel Al-Aamiri
- Department of Pathology and Laboratory Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| | - William G Wadsworth
- Department of Pathology and Laboratory Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
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Abstract
The Slit-Robo GTPase-activating proteins (srGAPs) were first identified as potential Slit-Robo effectors that influence growth cone guidance. Given their N-terminal F-BAR, central GAP and C-terminal SH3 domains, srGAPs have the potential to affect membrane dynamics, Rho family GTPase activity and other binding partners. Recent research has clarified how srGAP family members act in distinct ways at the cell membrane, and has expanded our understanding of the roles of srGAPs in neuronal and non-neuronal cells. Gene duplication of the human-specific paralog of srGAP2 has resulted in srGAP2 family proteins that may have increased the density of dendritic spines and promoted neoteny of the human brain during crucial periods of human evolution, underscoring the importance of srGAPs in the unique sculpting of the human brain. Importantly, srGAPs also play roles outside of the nervous system, including during contact inhibition of cell movement and in establishing and maintaining cell adhesions in epithelia. Changes in srGAP expression may contribute to neurodevelopmental disorders, cancer metastasis and inflammation. As discussed in this Review, much remains to be discovered about how this interesting family of proteins functions in a diverse set of processes in metazoans and the functional roles srGAPs play in human disease.
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Affiliation(s)
- Bethany Lucas
- Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
| | - Jeff Hardin
- Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
- Department of Integrative Biology, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
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17
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Ivakhnitskaia E, Lin RW, Hamada K, Chang C. Timing of neuronal plasticity in development and aging. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 7. [PMID: 29139210 DOI: 10.1002/wdev.305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 08/21/2017] [Accepted: 09/11/2017] [Indexed: 01/21/2023]
Abstract
Molecular oscillators are well known for their roles in temporal control of some biological processes like cell proliferation, but molecular mechanisms that provide temporal control of differentiation and postdifferentiation events in cells are less understood. In the nervous system, establishment of neuronal connectivity during development and decline in neuronal plasticity during aging are regulated with temporal precision, but the timing mechanisms are largely unknown. Caenorhabditis elegans has been a preferred model for aging research and recently emerges as a new model for the study of developmental and postdevelopmental plasticity in neurons. In this review we discuss the emerging mechanisms in timing of developmental lineage progression, axon growth and pathfinding, synapse formation, and reorganization, and neuronal plasticity in development and aging. We also provide a current view on the conserved core axon regeneration molecules with the intention to point out potential regulatory points of temporal controls. We highlight recent progress in understanding timing mechanisms that regulate decline in regenerative capacity, including progressive changes of intrinsic timers and co-opting the aging pathway molecules. WIREs Dev Biol 2018, 7:e305. doi: 10.1002/wdev.305 This article is categorized under: Invertebrate Organogenesis > Worms Establishment of Spatial and Temporal Patterns > Regulation of Size, Proportion, and Timing Nervous System Development > Worms Gene Expression and Transcriptional Hierarchies > Regulatory RNA.
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Affiliation(s)
- Evguenia Ivakhnitskaia
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA.,Medical Scientist Training Program, University of Illinois at Chicago, Chicago, IL, USA.,Graduate Program in Neuroscience, University of Illinois at Chicago, Chicago, IL, USA
| | - Ryan Weihsiang Lin
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Kana Hamada
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Chieh Chang
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA.,Graduate Program in Neuroscience, University of Illinois at Chicago, Chicago, IL, USA
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18
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Establishing Neuronal Polarity with Environmental and Intrinsic Mechanisms. Neuron 2017; 96:638-650. [DOI: 10.1016/j.neuron.2017.10.021] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 10/14/2017] [Accepted: 10/15/2017] [Indexed: 12/31/2022]
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19
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Brain specific Lamellipodin knockout results in hyperactivity and increased anxiety of mice. Sci Rep 2017; 7:5365. [PMID: 28710397 PMCID: PMC5511208 DOI: 10.1038/s41598-017-05043-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 05/24/2017] [Indexed: 11/08/2022] Open
Abstract
Lamellipodin (Lpd) functions as an important signalling integrator downstream of growth factor and axon guidance receptors. Mechanistically, Lpd promotes actin polymerization by interacting with F-actin and the actin effectors Ena/VASP proteins and the SCAR/WAVE complex. Thereby, Lpd supports lamellipodia protrusion, cell migration and endocytosis. In the mammalian central nervous system, Lpd contributes to neuronal morphogenesis, neuronal migration during development and its C. elegans orthologue MIG-10 also supports synaptogenesis. However, the consequences of loss of Lpd in the CNS on behaviour are unknown. In our current study, we crossed our Lpd conditional knockout mice with a mouse line expressing Cre under the CNS specific Nestin promoter to restrict the genetic ablation of Lpd to the central nervous system. Detailed behavioural analysis of the resulting Nestin-Cre-Lpd knockout mouse line revealed a specific behavioural phenotype characterised by hyperactivity and increased anxiety.
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20
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The Caenorhabditis elegans NF2/Merlin Molecule NFM-1 Nonautonomously Regulates Neuroblast Migration and Interacts Genetically with the Guidance Cue SLT-1/Slit. Genetics 2016; 205:737-748. [PMID: 27913619 DOI: 10.1534/genetics.116.191957] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 11/23/2016] [Indexed: 11/18/2022] Open
Abstract
During nervous system development, neurons and their progenitors migrate to their final destinations. In Caenorhabditis elegans, the bilateral Q neuroblasts and their descendants migrate long distances in opposite directions, despite being born in the same posterior region. QR on the right migrates anteriorly and generates the AQR neuron positioned near the head, and QL on the left migrates posteriorly, giving rise to the PQR neuron positioned near the tail. In a screen for genes required for AQR and PQR migration, we identified an allele of nfm-1, which encodes a molecule similar to vertebrate NF2/Merlin, an important tumor suppressor in humans. Mutations in NF2 lead to neurofibromatosis type II, characterized by benign tumors of glial tissues. Here we demonstrate that in C. elegans, nfm-1 is required for the ability of Q cells and their descendants to extend protrusions and to migrate, but is not required for direction of migration. Using a combination of mosaic analysis and cell-specific expression, we show that NFM-1 is required nonautonomously, possibly in muscles, to promote Q lineage migrations. We also show a genetic interaction between nfm-1 and the C. elegans Slit homolog slt-1, which encodes a conserved secreted guidance cue. Our results suggest that NFM-1 might be involved in the generation of an extracellular cue that promotes Q neuroblast protrusion and migration that acts with or in parallel to SLT-1 In vertebrates, NF2 and Slit2 interact in axon pathfinding, suggesting a conserved interaction of NF2 and Slit2 in regulating migratory events.
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21
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Xu Y, Quinn CC. SYD-1 Promotes Multiple Developmental Steps Leading to Neuronal Connectivity. Mol Neurobiol 2016; 53:6768-6773. [PMID: 26660112 PMCID: PMC5841450 DOI: 10.1007/s12035-015-9592-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 12/01/2015] [Indexed: 11/30/2022]
Abstract
The establishment of neuronal connectivity requires precise orchestration of multiple developmental steps, including axon specification, axon guidance, selection of synaptic target sites, and development of synaptic specializations. Although these are separate developmental steps, evidence indicates that some of the signaling molecules that regulate these steps are shared. In this review, we focus on SYD-1, a RhoGAP-like protein that has been implicated in each step of axonal development. We discuss interactions between SYD-1, UNC-40(DCC) and RhoGTPases and highlight both similarities and differences in how SYD-1 functions to regulate the different steps of axonal development. These observations reveal an example of how a signaling protein can be repurposed across sequential developmental steps.
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Affiliation(s)
- Yan Xu
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA
| | - Christopher C Quinn
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA.
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22
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Chisholm AD, Hutter H, Jin Y, Wadsworth WG. The Genetics of Axon Guidance and Axon Regeneration in Caenorhabditis elegans. Genetics 2016; 204:849-882. [PMID: 28114100 PMCID: PMC5105865 DOI: 10.1534/genetics.115.186262] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 09/06/2016] [Indexed: 11/18/2022] Open
Abstract
The correct wiring of neuronal circuits depends on outgrowth and guidance of neuronal processes during development. In the past two decades, great progress has been made in understanding the molecular basis of axon outgrowth and guidance. Genetic analysis in Caenorhabditis elegans has played a key role in elucidating conserved pathways regulating axon guidance, including Netrin signaling, the slit Slit/Robo pathway, Wnt signaling, and others. Axon guidance factors were first identified by screens for mutations affecting animal behavior, and by direct visual screens for axon guidance defects. Genetic analysis of these pathways has revealed the complex and combinatorial nature of guidance cues, and has delineated how cues guide growth cones via receptor activity and cytoskeletal rearrangement. Several axon guidance pathways also affect directed migrations of non-neuronal cells in C. elegans, with implications for normal and pathological cell migrations in situations such as tumor metastasis. The small number of neurons and highly stereotyped axonal architecture of the C. elegans nervous system allow analysis of axon guidance at the level of single identified axons, and permit in vivo tests of prevailing models of axon guidance. C. elegans axons also have a robust capacity to undergo regenerative regrowth after precise laser injury (axotomy). Although such axon regrowth shares some similarities with developmental axon outgrowth, screens for regrowth mutants have revealed regeneration-specific pathways and factors that were not identified in developmental screens. Several areas remain poorly understood, including how major axon tracts are formed in the embryo, and the function of axon regeneration in the natural environment.
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Affiliation(s)
| | - Harald Hutter
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, and
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093
- Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, Chevy Chase, Maryland, and
| | - William G Wadsworth
- Department of Pathology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
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23
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Amin L, Nguyen XTA, Rolle IG, D'Este E, Giachin G, Tran TH, Šerbec VČ, Cojoc D, Legname G. Characterization of prion protein function by focal neurite stimulation. J Cell Sci 2016; 129:3878-3891. [PMID: 27591261 DOI: 10.1242/jcs.183137] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 08/16/2016] [Indexed: 12/22/2022] Open
Abstract
The cellular prion protein (PrPC), encoded by the PRNP gene, is a ubiquitous glycoprotein, which is highly expressed in the brain. This protein, mainly known for its role in neurodegenerative diseases, is involved in several physiological processes including neurite outgrowth. By using a novel focal stimulation technique, we explored the potential function of PrPC, in its soluble form, as a signaling molecule. Thus, soluble recombinant prion proteins (recPrP) encapsulated in micro-vesicles were released by photolysis near the hippocampal growth cones. Local stimulation of wild-type growth cones with full-length recPrP induced neurite outgrowth and rapid growth cone turning towards the source. This effect was shown to be concentration dependent. Notably, PrPC-knockout growth cones were insensitive to recPrP stimulation, but this property was rescued in PrP-knockout growth cones expressing GFP-PrP. Taken together, our findings indicate that recPrP functions as a signaling molecule, and that its homophilic interaction with membrane-anchored PrPC might promote neurite outgrowth and facilitate growth cone guidance.
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Affiliation(s)
- Ladan Amin
- Department of Neuroscience, Laboratory of Prion Biology, Scuola Internazionale Superiore di Studi Avanzati (SISSA), I-34136 Trieste, Italy
| | - Xuan T A Nguyen
- Department of Neuroscience, Laboratory of Prion Biology, Scuola Internazionale Superiore di Studi Avanzati (SISSA), I-34136 Trieste, Italy
| | - Irene Giulia Rolle
- Department of Neuroscience, Laboratory of Prion Biology, Scuola Internazionale Superiore di Studi Avanzati (SISSA), I-34136 Trieste, Italy
| | - Elisa D'Este
- Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Gabriele Giachin
- Department of Neuroscience, Laboratory of Prion Biology, Scuola Internazionale Superiore di Studi Avanzati (SISSA), I-34136 Trieste, Italy
| | - Thanh Hoa Tran
- Department of Neuroscience, Laboratory of Prion Biology, Scuola Internazionale Superiore di Studi Avanzati (SISSA), I-34136 Trieste, Italy
| | - Vladka Čurin Šerbec
- Department for Production of Diagnostic Reagents and Research, Blood Transfusion Centre of Slovenia, 1000 Ljubljana, Slovenia
| | - Dan Cojoc
- Optical Manipulation (OM)-Lab, Institute of Materials (IOM), National Research Council (CNR), I-34149 Trieste, Italy
| | - Giuseppe Legname
- Department of Neuroscience, Laboratory of Prion Biology, Scuola Internazionale Superiore di Studi Avanzati (SISSA), I-34136 Trieste, Italy
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Miller CL, Muthupalani S, Shen Z, Drees F, Ge Z, Feng Y, Chen X, Gong G, Nagar KK, Wang TC, Gertler FB, Fox JG. Lamellipodin-Deficient Mice: A Model of Rectal Carcinoma. PLoS One 2016; 11:e0152940. [PMID: 27045955 PMCID: PMC4821566 DOI: 10.1371/journal.pone.0152940] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 03/20/2016] [Indexed: 01/27/2023] Open
Abstract
During a survey of clinical rectal prolapse (RP) cases in the mouse population at MIT animal research facilities, a high incidence of RP in the lamellipodin knock-out strain, C57BL/6-Raph1tm1Fbg (Lpd-/-) was documented. Upon further investigation, the Lpd-/- colony was found to be infected with multiple endemic enterohepatic Helicobacter species (EHS). Lpd-/- mice, a transgenic mouse strain produced at MIT, have not previously shown a distinct immune phenotype and are not highly susceptible to other opportunistic infections. Predominantly male Lpd-/- mice with RP exhibited lesions consistent with invasive rectal carcinoma concomitant to clinically evident RP. Multiple inflammatory cytokines, CD11b+Gr1+ myeloid-derived suppressor cell (MDSC) populations, and epithelial cells positive for a DNA damage biomarker, H2AX, were elevated in affected tissue, supporting their role in the neoplastic process. An evaluation of Lpd-/- mice with RP compared to EHS-infected, but clinically normal (CN) Lpd-/- animals indicated that all of these mice exhibit some degree of lower bowel inflammation; however, mice with prolapses had significantly higher degree of focal lesions at the colo-rectal junction. When Helicobacter spp. infections were eliminated in Lpd-/- mice by embryo transfer rederivation, the disease phenotype was abrogated, implicating EHS as a contributing factor in the development of rectal carcinoma. Here we describe lesions in Lpd-/- male mice consistent with a focal inflammation-induced neoplastic transformation and propose this strain as a mouse model of rectal carcinoma.
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Affiliation(s)
- Cassandra L. Miller
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Sureshkumar Muthupalani
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Zeli Shen
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Frauke Drees
- David H Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Zhongming Ge
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Yan Feng
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Xiaowei Chen
- Division of Digestive and Liver Diseases, Columbia University, New York, NY, United States of America
| | - Guanyu Gong
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Karan K. Nagar
- Division of Digestive and Liver Diseases, Columbia University, New York, NY, United States of America
| | - Timothy C. Wang
- Division of Digestive and Liver Diseases, Columbia University, New York, NY, United States of America
| | - Frank B. Gertler
- David H Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - James G. Fox
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- * E-mail:
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25
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Mariani L, Lussi YC, Vandamme J, Riveiro A, Salcini AE. The H3K4me3/2 histone demethylase RBR-2 controls axon guidance by repressing the actin-remodeling gene wsp-1. Development 2016; 143:851-63. [PMID: 26811384 DOI: 10.1242/dev.132985] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/16/2016] [Indexed: 12/25/2022]
Abstract
The dynamic regulation of histone modifications is important for modulating transcriptional programs during development. Aberrant H3K4 methylation is associated with neurological disorders, but how the levels and the recognition of this modification affect specific neuronal processes is unclear. Here, we show that RBR-2, the sole homolog of the KDM5 family of H3K4me3/2 demethylases in Caenorhabditis elegans, ensures correct axon guidance by controlling the expression of the actin regulator wsp-1. Loss of rbr-2 results in increased levels of H3K4me3 at the transcriptional start site of wsp-1, with concomitant higher wsp-1 expression responsible for defective axon guidance. In agreement, overexpression of WSP-1 mimics rbr-2 loss, and its depletion restores normal axon guidance in rbr-2 mutants. NURF-1, an H3K4me3-binding protein and member of the chromatin-remodeling complex NURF, is required for promoting aberrant wsp-1 transcription in rbr-2 mutants and its ablation restores wild-type expression of wsp-1 and axon guidance. Thus, our results establish a precise role for epigenetic regulation in neuronal development by demonstrating a functional link between RBR-2 activity, H3K4me3 levels, the NURF complex and the expression of WSP-1.
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Affiliation(s)
- Luca Mariani
- Biotech Research & Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Yvonne C Lussi
- Biotech Research & Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Julien Vandamme
- Biotech Research & Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Alba Riveiro
- Biotech Research & Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Anna Elisabetta Salcini
- Biotech Research & Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark Centre for Epigenetics, University of Copenhagen, 2200 Copenhagen, Denmark
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Menon S, Gupton SL. Building Blocks of Functioning Brain: Cytoskeletal Dynamics in Neuronal Development. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 322:183-245. [PMID: 26940519 PMCID: PMC4809367 DOI: 10.1016/bs.ircmb.2015.10.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neural connectivity requires proper polarization of neurons, guidance to appropriate target locations, and establishment of synaptic connections. From when neurons are born to when they finally reach their synaptic partners, neurons undergo constant rearrangment of the cytoskeleton to achieve appropriate shape and polarity. Of particular importance to neuronal guidance to target locations is the growth cone at the tip of the axon. Growth-cone steering is also dictated by the underlying cytoskeleton. All these changes require spatiotemporal control of the cytoskeletal machinery. This review summarizes the proteins that are involved in modulating the actin and microtubule cytoskeleton during the various stages of neuronal development.
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Affiliation(s)
- Shalini Menon
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, United States of America
| | - Stephanie L Gupton
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, United States of America; Neuroscience Center and Curriculum in Neurobiology, University of North Carolina, Chapel Hill, NC, United States of America; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America.
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27
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Lagarrigue F, Vikas Anekal P, Lee HS, Bachir AI, Ablack JN, Horwitz AF, Ginsberg MH. A RIAM/lamellipodin-talin-integrin complex forms the tip of sticky fingers that guide cell migration. Nat Commun 2015; 6:8492. [PMID: 26419705 PMCID: PMC4589889 DOI: 10.1038/ncomms9492] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/26/2015] [Indexed: 01/10/2023] Open
Abstract
The leading edge of migrating cells contains rapidly translocating activated integrins associated with growing actin filaments that form 'sticky fingers' to sense extracellular matrix and guide cell migration. Here we utilized indirect bimolecular fluorescence complementation to visualize a molecular complex containing a Mig-10/RIAM/lamellipodin (MRL) protein (Rap1-GTP-interacting adaptor molecule (RIAM) or lamellipodin), talin and activated integrins in living cells. This complex localizes at the tips of growing actin filaments in lamellipodial and filopodial protrusions, thus corresponding to the tips of the 'sticky fingers.' Formation of the complex requires talin to form a bridge between the MRL protein and the integrins. Moreover, disruption of the MRL protein-integrin-talin (MIT) complex markedly impairs cell protrusion. These data reveal the molecular basis of the formation of 'sticky fingers' at the leading edge of migrating cells and show that an MIT complex drives these protrusions.
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Affiliation(s)
- Frederic Lagarrigue
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Praju Vikas Anekal
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Ho-Sup Lee
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Alexia I Bachir
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Jailal N Ablack
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Alan F Horwitz
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Mark H Ginsberg
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
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Hansen SD, Mullins RD. Lamellipodin promotes actin assembly by clustering Ena/VASP proteins and tethering them to actin filaments. eLife 2015; 4:e06585. [PMID: 26295568 PMCID: PMC4543927 DOI: 10.7554/elife.06585] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 07/27/2015] [Indexed: 11/16/2022] Open
Abstract
Enabled/Vasodilator (Ena/VASP) proteins promote actin filament assembly at multiple locations, including: leading edge membranes, focal adhesions, and the surface of intracellular pathogens. One important Ena/VASP regulator is the mig-10/Lamellipodin/RIAM family of adaptors that promote lamellipod formation in fibroblasts and drive neurite outgrowth and axon guidance in neurons. To better understand how MRL proteins promote actin network formation we studied the interactions between Lamellipodin (Lpd), actin, and VASP, both in vivo and in vitro. We find that Lpd binds directly to actin filaments and that this interaction regulates its subcellular localization and enhances its effect on VASP polymerase activity. We propose that Lpd delivers Ena/VASP proteins to growing barbed ends and increases their polymerase activity by tethering them to filaments. This interaction represents one more pathway by which growing actin filaments produce positive feedback to control localization and activity of proteins that regulate their assembly.
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Affiliation(s)
- Scott D Hansen
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, United States
| | - R Dyche Mullins
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco School of Medicine, San Francisco, United States
- Howard Hughes Medical Institute, University of California, San Francisco, United States
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29
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Glypican Is a Modulator of Netrin-Mediated Axon Guidance. PLoS Biol 2015; 13:e1002183. [PMID: 26148345 PMCID: PMC4493048 DOI: 10.1371/journal.pbio.1002183] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/15/2015] [Indexed: 11/19/2022] Open
Abstract
Netrin is a key axon guidance cue that orients axon growth during neural circuit formation. However, the mechanisms regulating netrin and its receptors in the extracellular milieu are largely unknown. Here we demonstrate that in Caenorhabditis elegans, LON-2/glypican, a heparan sulfate proteoglycan, modulates UNC-6/netrin signaling and may do this through interactions with the UNC-40/DCC receptor. We show that developing axons misorient in the absence of LON-2/glypican when the SLT-1/slit guidance pathway is compromised and that LON-2/glypican functions in both the attractive and repulsive UNC-6/netrin pathways. We find that the core LON-2/glypican protein, lacking its heparan sulfate chains, and secreted forms of LON-2/glypican are functional in axon guidance. We also find that LON-2/glypican functions from the epidermal substrate cells to guide axons, and we provide evidence that LON-2/glypican associates with UNC-40/DCC receptor-expressing cells. We propose that LON-2/glypican acts as a modulator of UNC-40/DCC-mediated guidance to fine-tune axonal responses to UNC-6/netrin signals during migration.
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30
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Piper M, Lee AC, van Horck FPG, McNeilly H, Lu TB, Harris WA, Holt CE. Differential requirement of F-actin and microtubule cytoskeleton in cue-induced local protein synthesis in axonal growth cones. Neural Dev 2015; 10:3. [PMID: 25886013 PMCID: PMC4350973 DOI: 10.1186/s13064-015-0031-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 02/04/2015] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Local protein synthesis (LPS) via receptor-mediated signaling plays a role in the directional responses of axons to extrinsic cues. An intact cytoskeleton is critical to enact these responses, but it is not known whether the two major cytoskeletal elements, F-actin and microtubules, have any roles in regulating axonal protein synthesis. RESULTS Here, we show that pharmacological disruption of either microtubules or actin filaments in growth cones blocks netrin-1-induced de novo synthesis of proteins, as measured by metabolic incorporation of labeled amino acids, implicating both elements in axonal synthesis. However, comparative analysis of the activated translation initiation regulator, eIF4E-BP1, revealed a striking difference in the point of action of the two elements: actin disruption completely inhibited netrin-1-induced eIF4E-BP1 phosphorylation while microtubule disruption had no effect. An intact F-actin, but not microtubule, cytoskeleton was also required for netrin-1-induced activation of the PI3K/Akt/mTOR pathway, upstream of translation initiation. Downstream of translation initiation, microtubules were required for netrin-1-induced activation of eukaryotic elongation factor 2 kinase (eEF2K) and eEF2. CONCLUSIONS Taken together, our results show that while actin and microtubules are both crucial for cue-induced axonal protein synthesis, they serve distinct roles with F-actin being required for the initiation of translation and microtubules acting later at the elongation step.
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Affiliation(s)
- Michael Piper
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing street, Cambridge, CB2 3DY, UK.
- Current address: The School of Biomedical Sciences and the Queensland Brain Institute, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Aih Cheun Lee
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing street, Cambridge, CB2 3DY, UK.
- Current address: Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Francisca P G van Horck
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing street, Cambridge, CB2 3DY, UK.
| | - Heather McNeilly
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing street, Cambridge, CB2 3DY, UK.
| | - Trina Bo Lu
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing street, Cambridge, CB2 3DY, UK.
| | - William A Harris
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing street, Cambridge, CB2 3DY, UK.
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing street, Cambridge, CB2 3DY, UK.
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31
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Wang L, Shen W, Lei S, Matus D, Sherwood D, Wang Z. MIG-10 (Lamellipodin) stabilizes invading cell adhesion to basement membrane and is a negative transcriptional target of EGL-43 in C. elegans. Biochem Biophys Res Commun 2014; 452:328-33. [PMID: 25148942 DOI: 10.1016/j.bbrc.2014.08.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 08/11/2014] [Indexed: 11/28/2022]
Abstract
Cell invasion through basement membrane (BM) occurs in many physiological and pathological contexts. MIG-10, the Caenorhabditis elegans Lamellipodin (Lpd), regulates diverse biological processes. Its function and regulation in cell invasive behavior remain unclear. Using anchor cell (AC) invasion in C. elegans as an in vivo invasion model, we have previously found that mig-10's activity is largely outside of UNC-6 (netrin) signaling, a chemical cue directing AC invasion. We have shown that MIG-10 is a target of the transcription factor FOS-1A and facilitates BM breaching. Combining genetics and imaging analyses, we report that MIG-10 synergizes with UNC-6 to promote AC attachment to the BM, revealing a functional role for MIG-10 in stabilizing AC-BM adhesion. MIG-10 is also required for F-actin accumulation in the absence of UNC-6. Further, we identify mig-10 as a transcriptional target negatively regulated by EGL-43A (C. elegans Evi-1 proto-oncogene), a transcription factor positively controlled by FOS-1A. The revelation of this negative regulation unmasks an incoherent feedforward circuit existing among fos-1, egl-43 and mig-10. Moreover, our study suggests the functional importance of the negative regulation on mig-10 expression by showing that excessive MIG-10 impairs AC invasion. Thus, we provide new insight into MIG-10's function and its complex transcriptional regulation during cell invasive behavior.
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Affiliation(s)
- Lin Wang
- Center for Tissue Engineering and Regenerative Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Wanqing Shen
- Center for Tissue Engineering and Regenerative Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Shijun Lei
- Center for Tissue Engineering and Regenerative Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - David Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - David Sherwood
- Department of Biology, Duke University, 124 Science Drive, Box 90388, Durham, NC 27708, USA
| | - Zheng Wang
- Center for Tissue Engineering and Regenerative Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China; Department of Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China.
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32
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Impaired mitochondrial respiration promotes dendritic branching via the AMPK signaling pathway. Cell Death Dis 2014; 5:e1175. [PMID: 24722300 PMCID: PMC5424120 DOI: 10.1038/cddis.2014.144] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 02/27/2014] [Indexed: 12/28/2022]
Abstract
Functional neuronal circuits require a constant remodeling of their network composed of highly interconnected neurons. The plasticity of synapses and the shaping of elaborated dendritic branches are energy demanding and therefore depend on an efficient mitochondrial oxidative phosphorylation (OXPHOS). The spatial and functional regulations of dendritic patterning occur also after cell fate specification; however, the molecular mechanisms underlying this complex process remain elusive. Here, we exploit the changes in dendritic architecture in highly branched neurons as a result of aberrant mitochondrial activity. In sensory neurons of Caenorhabditis elegans, genetic manipulations of mitochondrial complex I subunits cause an unexpected outgrowth of dendritic arbors and ectopic structures. The increased number of dendritic branches is coordinated through a specific signaling cascade rather than as a simple consequence of oxidative stress. On the basis of genetic and pharmacological evidence, we show that OXPHOS deficiency promotes branching through the activation of the AMP-activated protein kinase AMPK and the downstream target phosphoinositide 3-kinase PI3K. Taken together, our findings describe a well-defined signaling pathway that regulates dendritic outgrowth in conditions of compromised OXPHOS and the resulting AMPK activation.
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33
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Wang Z, Chi Q, Sherwood DR. MIG-10 (lamellipodin) has netrin-independent functions and is a FOS-1A transcriptional target during anchor cell invasion in C. elegans. Development 2014; 141:1342-53. [PMID: 24553288 PMCID: PMC3943185 DOI: 10.1242/dev.102434] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 01/09/2014] [Indexed: 02/04/2023]
Abstract
To transmigrate basement membrane, cells must coordinate distinct signaling activities to breach and pass through this dense extracellular matrix barrier. Netrin expression and activity are strongly associated with invasion in developmental and pathological processes, but how netrin signaling is coordinated with other pathways during invasion is poorly understood. Using the model of anchor cell (AC) invasion in C. elegans, we have previously shown that the integrin receptor heterodimer INA-1/PAT-3 promotes netrin receptor UNC-40 (DCC) localization to the invasive cell membrane of the AC. UNC-6 (netrin)/UNC-40 interactions generate an invasive protrusion that crosses the basement membrane. To understand how UNC-40 signals during invasion, we have used genetic, site of action and live-cell imaging studies to examine the roles of known effectors of UNC-40 signaling in axon outgrowth during AC invasion. UNC-34 (Ena/VASP), the Rac GTPases MIG-2 and CED-10 and the actin binding protein UNC-115 (abLIM) are dedicated UNC-40 effectors that are recruited to the invasive membrane by UNC-40 and generate F-actin. MIG-10 (lamellipodin), an effector of UNC-40 in neurons, however, has independent functions from UNC-6/UNC-40. Furthermore, unlike other UNC-40 effectors, its expression is regulated by FOS-1A, a transcription factor that promotes basement membrane breaching. Similar to UNC-40, however, MIG-10 localization to the invasive cell membrane is also dependent on the integrin INA-1/PAT-3. These studies indicate that MIG-10 has distinct functions from UNC-40 signaling in cell invasion, and demonstrate that integrin coordinates invasion by localizing these molecules to the cell-basement membrane interface.
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Affiliation(s)
- Zheng Wang
- Department of Biology, Duke University, Science Drive, Box 90388, Durham, NC 27708, USA
| | - Qiuyi Chi
- Department of Biology, Duke University, Science Drive, Box 90388, Durham, NC 27708, USA
| | - David R. Sherwood
- Department of Biology, Duke University, Science Drive, Box 90388, Durham, NC 27708, USA
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34
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Kulkarni G, Xu Z, Mohamed AM, Li H, Tang X, Limerick G, Wadsworth WG. Experimental evidence for UNC-6 (netrin) axon guidance by stochastic fluctuations of intracellular UNC-40 (DCC) outgrowth activity. Biol Open 2013; 2:1300-12. [PMID: 24337114 PMCID: PMC3863414 DOI: 10.1242/bio.20136346] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
How the direction of axon guidance is determined is not understood. In Caenorhabditis elegans the UNC-40 (DCC) receptor mediates a response to the UNC-6 (netrin) guidance cue that directs HSN axon development. UNC-40 becomes asymmetrically localized within the HSN neuron to the site of axon outgrowth. Here we provide experimental evidence that the direction of guidance can be explained by the stochastic fluctuations of UNC-40 asymmetric outgrowth activity. We find that the UNC-5 (UNC5) receptor and the cytoskeletal binding protein UNC-53 (NAV2) regulate the induction of UNC-40 localization by UNC-6. If UNC-40 localization is induced without UNC-6 by using an unc-53 mutation, the direction of UNC-40 localization undergoes random fluctuations. Random walk models describe the path made by a succession of randomly directed movement. This model was experimentally tested using mutations that affect Wnt/PCP signaling. These mutations inhibit UNC-40 localization in the anterior and posterior directions. As the axon forms in Wnt/PCP mutants, the direction of UNC-40 localization randomly fluctuates; it can localize in either the anterior, posterior, or ventral direction. Consistent with a biased random walk, over time the axon will develop ventrally in response to UNC-6, even though at a discrete time UNC-40 localization and outgrowth can be observed anterior or posterior. Also, axon formation is slower in the mutants than in wild-type animals. This is also consistent with a random walk since this model predicts that the mean square displacement (msd) will increase only linearly with time, whereas the msd increases quadratically with time for straight-line motion.
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Affiliation(s)
- Gauri Kulkarni
- Department of Pathology, Robert Wood Johnson Medical School, Rutgers University, 675 Hoes Lane West, Piscataway, NJ 08854, USA
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35
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Grossman EN, Giurumescu CA, Chisholm AD. Mechanisms of ephrin receptor protein kinase-independent signaling in amphid axon guidance in Caenorhabditis elegans. Genetics 2013; 195:899-913. [PMID: 23979582 PMCID: PMC3813872 DOI: 10.1534/genetics.113.154393] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 08/16/2013] [Indexed: 12/30/2022] Open
Abstract
Eph receptors and their ephrin ligands are key conserved regulators of axon guidance and can function in a variety of signaling modes. Here we analyze the genetic and cellular requirements for Eph signaling in a Caenorhabditis elegans axon guidance choice point, the ventral guidance of axons in the amphid commissure. The C. elegans Eph receptor EFN-1 has both kinase-dependent and kinase-independent roles in amphid ventral guidance. Of the four C. elegans ephrins, we find that only EFN-1 has a major role in amphid axon ventral guidance, and signals in both a receptor kinase-dependent and kinase-independent manner. Analysis of EFN-1 and EFN-1 expression and tissue-specific requirements is consistent with a model in which VAB-1 acts in amphid neurons, interacting with EFN-1 expressed on surrounding cells. Unexpectedly, left-hand neurons are more strongly affected than right-hand neurons by loss of Eph signaling, indicating a previously undetected left-right asymmetry in the requirement for Eph signaling. By screening candidate genes involved in Eph signaling, we find that the Eph kinase-independent pathway involves the ABL-1 nonreceptor tyrosine kinase and possibly the phosphatidylinositol 3-kinase pathway. Overexpression of ABL-1 is sufficient to rescue EFN-1 ventral guidance defects cell autonomously. Our results reveal new aspects of Eph signaling in a single axon guidance decision in vivo.
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Affiliation(s)
- Emily N. Grossman
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California 92093
| | - Claudiu A. Giurumescu
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California 92093
| | - Andrew D. Chisholm
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California 92093
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36
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Alan JK, Struckhoff EC, Lundquist EA. Multiple cytoskeletal pathways and PI3K signaling mediate CDC-42-induced neuronal protrusion in C. elegans. Small GTPases 2013; 4:208-20. [PMID: 24149939 PMCID: PMC4011816 DOI: 10.4161/sgtp.26602] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 09/23/2013] [Accepted: 09/25/2013] [Indexed: 12/30/2022] Open
Abstract
Rho GTPases are key regulators of cellular protrusion and are involved in many developmental events including axon guidance during nervous system development. Rho GTPase pathways display functional redundancy in developmental events, including axon guidance. Therefore, their roles can often be masked when using simple loss-of-function genetic approaches. As a complement to loss-of-function genetics, we constructed a constitutively activated CDC-42(G12V) expressed in C. elegans neurons. CDC-42(G12V) drove the formation of ectopic lamellipodial and filopodial protrusions in the PDE neurons, which resembled protrusions normally found on migrating growth cones of axons. We then used a candidate gene approach to identify molecules that mediate CDC-42(G12V)-induced ectopic protrusions by determining if loss of function of the genes could suppress CDC-42(G12V). Using this approach, we identified 3 cytoskeletal pathways previously implicated in axon guidance, the Arp2/3 complex, UNC-115/abLIM, and UNC-43/Ena. We also identified the Nck-interacting kinase MIG-15/NIK and p21-activated kinases (PAKs), also implicated in axon guidance. Finally, PI3K signaling was required, specifically the Rictor/mTORC2 branch but not the mTORC1 branch that has been implicated in other aspects of PI3K signaling including stress and aging. Our results indicate that multiple pathways can mediate CDC-42-induced neuronal protrusions that might be relevant to growth cone protrusions during axon pathfinding. Each of these pathways involves Rac GTPases, which might serve to integrate the pathways and coordinate the multiple CDC-42 pathways. These pathways might be relevant to developmental events such as axon pathfinding as well as disease states such as metastatic melanoma.
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Affiliation(s)
| | - Eric C Struckhoff
- Department of Molecular Biosciences; University of Kansas; Lawrence, KS USA
| | - Erik A Lundquist
- Department of Molecular Biosciences; University of Kansas; Lawrence, KS USA
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37
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Barsi-Rhyne BJ, Miller KM, Vargas CT, Thomas AB, Park J, Bremer M, Jarecki JL, VanHoven MK. Kinesin-1 acts with netrin and DCC to maintain sensory neuron position in Caenorhabditis elegans. Genetics 2013; 194:175-87. [PMID: 23475988 PMCID: PMC3632465 DOI: 10.1534/genetics.113.149310] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 02/24/2013] [Indexed: 11/18/2022] Open
Abstract
The organization of neurons and the maintenance of that arrangement are critical to brain function. Failure of these processes in humans can lead to severe birth defects, mental retardation, and epilepsy. Several kinesins have been shown to play important roles in cell migration in vertebrate systems, but few upstream and downstream pathway members have been identified. Here, we utilize the genetic model organism Caenorhabditis elegans to elucidate the pathway by which the C. elegans Kinesin-1 Heavy Chain (KHC)/KIF5 ortholog UNC-116 functions to maintain neuronal cell body position in the PHB sensory neurons. We find that UNC-116/KHC acts in part with the cell and axon migration molecules UNC-6/Netrin and UNC-40/DCC in this process, but in parallel to SAX-3/Robo. We have also identified several potential adaptor, cargo, and regulatory proteins that may provide insight into the mechanism of UNC-116/KHC's function in this process. These include the cargo receptor UNC-33/CRMP2, the cargo adaptor protein UNC-76/FEZ and its regulator UNC-51/ULK, the cargo molecule UNC-69/SCOCO, and the actin regulators UNC-44/Ankyrin and UNC-34/Enabled. These genes also act in cell migration and axon outgrowth; however, many proteins that function in these processes do not affect PHB position. Our findings suggest an active posterior cell migration mediated by UNC-116/KHC occurs throughout development to maintain proper PHB cell body position and define a new pathway that mediates maintenance of neuronal cell body position.
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Affiliation(s)
| | - Kristine M. Miller
- Department of Biological Sciences, San José State University, San José, California 95192
| | - Christopher T. Vargas
- Department of Biological Sciences, San José State University, San José, California 95192
| | - Anthony B. Thomas
- Department of Biological Sciences, San José State University, San José, California 95192
| | - Joori Park
- Department of Biological Sciences, San José State University, San José, California 95192
| | - Martina Bremer
- Department of Mathematics, San José State University, San José, California 95192
| | - Jessica L. Jarecki
- Department of Biological Sciences, San José State University, San José, California 95192
| | - Miri K. VanHoven
- Department of Biological Sciences, San José State University, San José, California 95192
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38
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Nelson JC, Stavoe AKH, Colón-Ramos DA. The actin cytoskeleton in presynaptic assembly. Cell Adh Migr 2013; 7:379-87. [PMID: 23628914 DOI: 10.4161/cam.24803] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dramatic morphogenetic processes underpin nearly every step of nervous system development, from initial neuronal migration and axon guidance to synaptogenesis. Underlying this morphogenesis are dynamic rearrangements of cytoskeletal architecture. Here we discuss the roles of the actin cytoskeleton in the development of presynaptic terminals, from the elaboration of terminal arbors to the recruitment of presynaptic vesicles and active zone components. The studies discussed here underscore the importance of actin regulation at every step in neuronal circuit assembly.
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Affiliation(s)
- Jessica C Nelson
- Program in Cellular Neuroscience, Neurodegeneration and Repair; Department of Cell Biology; Yale University; New Haven, CT USA
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39
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Serotonergic neurosecretory synapse targeting is controlled by netrin-releasing guidepost neurons in Caenorhabditis elegans. J Neurosci 2013; 33:1366-76. [PMID: 23345213 DOI: 10.1523/jneurosci.3471-12.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurosecretory release sites lack distinct postsynaptic partners, yet target to specific circuits. This targeting specificity regulates local release of neurotransmitters and modulation of adjacent circuits. How neurosecretory release sites target to specific regions is not understood. Here we identify a molecular mechanism that governs the spatial specificity of extrasynaptic neurosecretory terminal (ENT) formation in the serotonergic neurosecretory-motor (NSM) neurons of Caenorhabditis elegans. We show that postembryonic arborization and neurosecretory terminal targeting of the C. elegans NSM neuron is dependent on the Netrin receptor UNC-40/DCC. We observe that UNC-40 localizes to specific neurosecretory terminals at the time of axon arbor formation. This localization is dependent on UNC-6/Netrin, which is expressed by nerve ring neurons that act as guideposts to instruct local arbor and release site formation. We find that both UNC-34/Enabled and MIG-10/Lamellipodin are required downstream of UNC-40 to link the sites of ENT formation to nascent axon arbor extensions. Our findings provide a molecular link between release site development and axon arborization and introduce a novel mechanism that governs the spatial specificity of serotonergic ENTs in vivo.
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Kirszenblat L, Neumann B, Coakley S, Hilliard MA. A dominant mutation in mec-7/β-tubulin affects axon development and regeneration in Caenorhabditis elegans neurons. Mol Biol Cell 2012; 24:285-96. [PMID: 23223572 PMCID: PMC3564523 DOI: 10.1091/mbc.e12-06-0441] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Microtubules are the basic elements of the cytoskeleton. This study demonstrates that a specific mutation in mec-7/β-tubulin is necessary for the correct number of neurites a neuron extends in vivo and the neuron’s capacity for axonal regeneration following injury. Microtubules have been known for decades to be basic elements of the cytoskeleton. They form long, dynamic, rope-like structures within the cell that are essential for mitosis, maintenance of cell shape, and intracellular transport. More recently, in vitro studies have implicated microtubules as signaling molecules that, through changes in their stability, have the potential to trigger growth of axons and dendrites in developing neurons. In this study, we show that specific mutations in the Caenorhabditis elegans mec-7/β-tubulin gene cause ectopic axon formation in mechanosensory neurons in vivo. In mec-7 mutants, the ALM mechanosensory neuron forms a long ectopic neurite that extends posteriorly, a phenotype that can be mimicked in wild-type worms with a microtubule-stabilizing drug (paclitaxel), and suppressed by mutations in unc-33/CRMP2 and the kinesin-related gene, vab-8. Our results also reveal that these ectopic neurites contain RAB-3, a marker for presynaptic loci, suggesting that they have axon-like properties. Interestingly, in contrast with the excessive axonal growth observed during development, mec-7 mutants are inhibited in axonal regrowth and remodeling following axonal injury. Together our results suggest that MEC-7/β-tubulin integrity is necessary for the correct number of neurites a neuron generates in vivo and for the capacity of an axon to regenerate.
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Affiliation(s)
- Leonie Kirszenblat
- Queensland Brain Institute, The University of Queensland, Brisbane 4072, Australia
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Stavoe AKH, Nelson JC, Martínez-Velázquez LA, Klein M, Samuel ADT, Colón-Ramos DA. Synaptic vesicle clustering requires a distinct MIG-10/Lamellipodin isoform and ABI-1 downstream from Netrin. Genes Dev 2012; 26:2206-21. [PMID: 23028145 DOI: 10.1101/gad.193409.112] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The chemotrophic factor Netrin can simultaneously instruct different neurodevelopmental programs in individual neurons in vivo. How neurons correctly interpret the Netrin signal and undergo the appropriate neurodevelopmental response is not understood. Here we identify MIG-10 isoforms as critical determinants of individual cellular responses to Netrin. We determined that distinct MIG-10 isoforms, varying only in their N-terminal motifs, can localize to specific subcellular domains and are differentially required for discrete neurodevelopmental processes in vivo. We identified MIG-10B as an isoform uniquely capable of localizing to presynaptic regions and instructing synaptic vesicle clustering in response to Netrin. MIG-10B interacts with Abl-interacting protein-1 (ABI-1)/Abi1, a component of the WAVE complex, to organize the actin cytoskeleton at presynaptic sites and instruct vesicle clustering through SNN-1/Synapsin. We identified a motif in the MIG-10B N-terminal domain that is required for its function and localization to presynaptic sites. With this motif, we engineered a dominant-negative MIG-10B construct that disrupts vesicle clustering and animal thermotaxis behavior when expressed in a single neuron in vivo. Our findings indicate that the unique N-terminal domains confer distinct MIG-10 isoforms with unique capabilities to localize to distinct subcellular compartments, organize the actin cytoskeleton at these sites, and instruct distinct Netrin-dependent neurodevelopmental programs.
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Affiliation(s)
- Andrea K H Stavoe
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06536, USA
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Xu Y, Quinn CC. MIG-10 functions with ABI-1 to mediate the UNC-6 and SLT-1 axon guidance signaling pathways. PLoS Genet 2012; 8:e1003054. [PMID: 23209429 PMCID: PMC3510047 DOI: 10.1371/journal.pgen.1003054] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 09/07/2012] [Indexed: 11/30/2022] Open
Abstract
Extracellular guidance cues steer axons towards their targets by eliciting morphological changes in the growth cone. A key part of this process is the asymmetric recruitment of the cytoplasmic scaffolding protein MIG-10 (lamellipodin). MIG-10 is thought to asymmetrically promote outgrowth by inducing actin polymerization. However, the mechanism that links MIG-10 to actin polymerization is not known. We have identified the actin regulatory protein ABI-1 as a partner for MIG-10 that can mediate its outgrowth-promoting activity. The SH3 domain of ABI-1 binds to MIG-10, and loss of function of either of these proteins causes similar axon guidance defects. Like MIG-10, ABI-1 functions in both the attractive UNC-6 (netrin) pathway and the repulsive SLT-1 (slit) pathway. Dosage sensitive genetic interactions indicate that MIG-10 functions with ABI-1 and WVE-1 to mediate axon guidance. Epistasis analysis reveals that ABI-1 and WVE-1 function downstream of MIG-10 to mediate its outgrowth-promoting activity. Moreover, experiments with cultured mammalian cells suggest that the interaction between MIG-10 and ABI-1 mediates a conserved mechanism that promotes formation of lamellipodia. Together, these observations suggest that MIG-10 interacts with ABI-1 and WVE-1 to mediate the UNC-6 and SLT-1 guidance pathways. To form neural circuits, axons must navigate through the developing nervous system to reach their correct targets. Axon navigation is led by the growth cone, a structure at the tip of the growing axon that responds to extracellular guidance cues. Many of these guidance cues and their receptors have been identified. However, much less is known about the internal signaling events that give rise to the structural changes required for growth cone steering. A key component of the internal response is MIG-10, a protein that becomes asymmetrically localized in response to the extracellular cues. MIG-10 is thought to serve as a scaffold that can spatially control outgrowth-promoting proteins within the growth cone. However, we do not know the identity of the outgrowth-promoting proteins that associate with MIG-10. Here we report that MIG-10 associates physically with the actin regulatory protein ABI-1. We present genetic evidence indicating that ABI-1 functions downstream of MIG-10 to mediate its outgrowth-promoting activity. Additional genetic evidence indicates that these proteins function in both attractive and repulsive guidance signaling pathways. We also present evidence suggesting that the connection between MIG-10 and ABI-1 represents a phylogenetically conserved mechanism for the control of cellular outgrowth.
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Affiliation(s)
| | - Christopher C. Quinn
- Department of Biological Sciences, University of Wisconsin–Milwaukee, Milwaukee, Wisconsin, United States of America
- * E-mail:
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A phosphatidylinositol lipids system, lamellipodin, and Ena/VASP regulate dynamic morphology of multipolar migrating cells in the developing cerebral cortex. J Neurosci 2012; 32:11643-56. [PMID: 22915108 DOI: 10.1523/jneurosci.0738-12.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the developing mammalian cerebral cortex, excitatory neurons are generated in the ventricular zone (VZ) and subventricular zone; these neurons migrate toward the pial surface. The neurons generated in the VZ assume a multipolar morphology and remain in a narrow region called the multipolar cell accumulation zone (MAZ) for ∼24 h, in which they extend and retract multiple processes dynamically. They eventually extend an axon tangentially and begin radial migration using a migratory mode called locomotion. Despite the potential biological importance of the process movement of multipolar cells, the molecular mechanisms remain to be elucidated. Here, we observed that the processes of mouse multipolar cells were actin rich and morphologically resembled the filopodia and lamellipodia in growth cones; thus, we focused on the actin-remodeling proteins Lamellipodin (Lpd) and Ena/vasodilator-stimulated phosphoprotein (VASP). Lpd binds to phosphatidylinositol (3,4)-bisphosphate [PI(3,4)P₂] and recruits Ena/VASP, which promotes the assembly of actin filaments, to the plasma membranes. In situ hybridization and immunohistochemistry revealed that Lpd is expressed in multipolar cells in the MAZ. The functional silencing of either Lpd or Ena/VASP decreased the number of primary processes. Immunostaining and a Förster resonance energy transfer analysis revealed the subcellular localization of PI(3,4)P₂ at the tips of the processes. A knockdown experiment and treatment with an inhibitor for Src homology 2-containing inositol phosphatase-2, a 5-phosphatase that produces PI(3,4)P₂ from phosphatidylinositol (3,4,5)-triphosphate, decreased the number of primary processes. Our observations suggest that PI(3,4)P₂, Lpd, and Ena/VASP are involved in the process movement of multipolar migrating cells.
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Kölsch V, Shen Z, Lee S, Plak K, Lotfi P, Chang J, Charest PG, Romero JL, Jeon TJ, Kortholt A, Briggs SP, Firtel RA. Daydreamer, a Ras effector and GSK-3 substrate, is important for directional sensing and cell motility. Mol Biol Cell 2012; 24:100-14. [PMID: 23135995 PMCID: PMC3541958 DOI: 10.1091/mbc.e12-04-0271] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Daydreamer (DydA), a new Mig10/RIAM/lamellipodin family adaptor protein, is a Ras effector required for cell polarization and directional movement during chemotaxis. DydA is phosphorylated by glycogen synthase kinase-3, which is required for some, but not all, of DydA's functions. gskA− cells exhibit very strong chemotactic phenotypes, a subset of which are exhibited by dydA− cells. How independent signaling pathways are integrated to holistically control a biological process is not well understood. We have identified Daydreamer (DydA), a new member of the Mig10/RIAM/lamellipodin (MRL) family of adaptor proteins that localizes to the leading edge of the cell. DydA is a putative Ras effector that is required for cell polarization and directional movement during chemotaxis. dydA− cells exhibit elevated F-actin and assembled myosin II (MyoII), increased and extended phosphoinositide-3-kinase (PI3K) activity, and extended phosphorylation of the activation loop of PKB and PKBR1, suggesting that DydA is involved in the negative regulation of these pathways. DydA is phosphorylated by glycogen synthase kinase-3 (GSK-3), which is required for some, but not all, of DydA's functions, including the proper regulation of PKB and PKBR1 and MyoII assembly. gskA− cells exhibit very strong chemotactic phenotypes, as previously described, but exhibit an increased rate of random motility. gskA− cells have a reduced MyoII response and a reduced level of phosphatidylinositol (3,4,5)-triphosphate production, but a highly extended recruitment of PI3K to the plasma membrane and highly extended kinetics of PKB and PKBR1 activation. Our results demonstrate that GSK-3 function is essential for chemotaxis, regulating multiple substrates, and that one of these effectors, DydA, plays a key function in the dynamic regulation of chemotaxis.
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Affiliation(s)
- Verena Kölsch
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0380, USA
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Bacon C, Endris V, Rappold GA. The cellular function of srGAP3 and its role in neuronal morphogenesis. Mech Dev 2012; 130:391-5. [PMID: 23127797 DOI: 10.1016/j.mod.2012.10.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/15/2012] [Accepted: 10/17/2012] [Indexed: 10/27/2022]
Abstract
The Slit-Robo GTPase activating protein 3 (srGAP3) dynamically regulates cytoskeletal reorganisation through inhibition of the Rho GTPase Rac1 and interaction with actin remodelling proteins. SrGAP3-mediated reorganisation of the actin cytoskeleton is crucial for the normal development of dendritic spines and loss of srGAP3 leads to abnormal synaptic activity and impaired cognitive behaviours in mice, which is reminiscent of an association between disrupted srGAP3 and intellectual disability in humans. Additionally, srGAP3 has been implicated to act downstream of Slit-Robo signalling in commissural axons of the spinal cord. Thus, srGAP3-mediated cytoskeletal reorganisation has an important influence on a variety of neurodevelopmental processes, which may be required for normal cognitive function.
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Affiliation(s)
- Claire Bacon
- Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
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McShea MA, Schmidt KL, Dubuke ML, Baldiga CE, Sullender ME, Reis AL, Zhang S, O'Toole SM, Jeffers MC, Warden RM, Kenney AH, Gosselin J, Kuhlwein M, Hashmi SK, Stringham EG, Ryder EF. Abelson interactor-1 (ABI-1) interacts with MRL adaptor protein MIG-10 and is required in guided cell migrations and process outgrowth in C. elegans. Dev Biol 2012; 373:1-13. [PMID: 23022657 DOI: 10.1016/j.ydbio.2012.09.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 09/12/2012] [Accepted: 09/21/2012] [Indexed: 11/19/2022]
Abstract
Directed cell migration and process outgrowth are vital to proper development of many metazoan tissues. These processes are dependent on reorganization of the actin cytoskeleton in response to external guidance cues. During development of the nervous system, the MIG-10/RIAM/Lamellipodin (MRL) signaling proteins are thought to transmit positional information from surface guidance cues to the actin polymerization machinery, and thus to promote polarized outgrowth of axons. In C. elegans, mutations in the MRL family member gene mig-10 result in animals that have defects in axon guidance, neuronal migration, and the outgrowth of the processes or 'canals' of the excretory cell, which is required for osmoregulation in the worm. In addition, mig-10 mutant animals have recently been shown to have defects in clustering of vesicles at the synapse. To determine additional molecular partners of MIG-10, we conducted a yeast two-hybrid screen using isoform MIG-10A as bait and isolated Abelson-interactor protein-1 (ABI-1). ABI-1, a downstream target of Abl non-receptor tyrosine kinase, is a member of the WAVE regulatory complex (WRC) involved in the initiation of actin polymerization. Further analysis using a co-immunoprecipitation system confirmed the interaction of MIG-10 and ABI-1 and showed that it requires the SH3 domain of ABI-1. Single mutants for mig-10 and abi-1 displayed similar phenotypes of incomplete migration of the ALM neurons and truncated outgrowth of the excretory cell canals, suggesting that the ABI-1/MIG-10 interaction is relevant in vivo. Cell autonomous expression of MIG-10 isoforms rescued both the neuronal migration and the canal outgrowth defects, showing that MIG-10 functions autonomously in the ALM neurons and the excretory cell. These results suggest that MIG-10 and ABI-1 interact physically to promote cell migration and process outgrowth in vivo. In the excretory canal, ABI-1 is thought to act downstream of UNC-53/NAV2, linking this large scaffolding protein to actin polymerization during excretory canal outgrowth. abi-1(RNAi) enhanced the excretory canal truncation observed in mig-10 mutants, while double mutant analysis between unc-53 and mig-10 showed no increased truncation of the posterior canal beyond that observed in mig-10 mutants. Morphological analysis of mig-10 and unc-53 mutants showed that these genes regulate canal diameter as well as its length, suggesting that defective lumen formation may be linked to the ability of the excretory canal to grow out longitudinally. Taken together, our results suggest that MIG-10, UNC-53, and ABI-1 act sequentially to mediate excretory cell process outgrowth.
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Affiliation(s)
- Molly A McShea
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.
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Semaphorin 4D/Plexin-B1-mediated M-Ras GAP activity regulates actin-based dendrite remodeling through Lamellipodin. J Neurosci 2012; 32:8293-305. [PMID: 22699910 DOI: 10.1523/jneurosci.0799-12.2012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Semaphorins have been identified as repulsive guidance molecules in the developing nervous system. We recently reported that the semaphorin 4D (Sema4D) receptor Plexin-B1 induces repulsion in axon and dendrites by functioning as a GTPase-activating protein (GAP) for R-Ras and M-Ras, respectively. In axons, Sema4D stimulation induces growth cone collapse, and downregulation of R-Ras activity by Plexin-B1-mediated GAP activity is required for the action. Axonal R-Ras GAP activity downregulates phosphatidylinositol 3-kinase signaling pathway, and thereby induces inactivation of a microtubule assembly promoter protein, CRMP-2. However, in contrast to the well studied roles of semaphorins and plexins in axonal guidance, signaling molecules linking M-Ras GAP to dendritic cytoskeleton remain obscure. Here we identified an Ena/VASP ligand, Lamellipodin (Lpd), as a novel effector of M-Ras in dendrites. Lpd was expressed in F-actin-rich distal dendritic processes and was required for both basal and M-Ras-mediated dendrite development. Subcellular fractionation showed M-Ras-dependent membrane translocation of Lpd, which was suppressed by Sema4D. Furthermore, the Ena/VASP-binding region within Lpd was required for dendrite development, and its membrane targeting was sufficient to overcome the Sema4D-mediated reduction of dendritic outgrowth and disappearance of F-actin from distal dendrites. Furthermore, in utero electroporation experiments also indicated that regulation of the M-Ras-Lpd system by the GAP activity of Plexin is involved in the normal development of cortical dendrites in vivo. Overall, our study sheds light on how repulsive guidance molecules regulate actin cytoskeleton in dendrites, revealing a novel mechanism that the M-Ras-Lpd system regulates actin-based dendrite remodeling by Sema/Plexin in rats or mice of either sex.
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Zou Y, Chiu H, Domenger D, Chuang CF, Chang C. The lin-4 microRNA targets the LIN-14 transcription factor to inhibit netrin-mediated axon attraction. Sci Signal 2012; 5:ra43. [PMID: 22692424 DOI: 10.1126/scisignal.2002437] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
miR-125 microRNAs, such as lin-4 in Caenorhabditis elegans, were among the first microRNAs discovered, are phylogenetically conserved, and have been implicated in regulating developmental timing. Here, we showed that loss-of-function mutations in lin-4 microRNA increased axon attraction mediated by the netrin homolog UNC-6. The absence of lin-4 microRNA suppressed the axon guidance defects of anterior ventral microtubule (AVM) neurons caused by loss-of-function mutations in slt-1, which encodes a repulsive guidance cue. Selective expression of lin-4 microRNA in AVM neurons of lin-4-null animals indicated that the effect of lin-4 on AVM axon guidance was cell-autonomous. Promoter reporter analysis suggested that lin-4 was likely expressed strongly in AVM neurons during the developmental time frame that the axons are guided to their targets. In contrast, the lin-4 reporter was barely detectable in anterior lateral microtubule (ALM) neurons, axon guidance of which is insensitive to netrin. In AVM neurons, the transcription factor LIN-14, a target of lin-4 microRNA, stimulated UNC-6-mediated ventral guidance of the AVM axon. LIN-14 promoted attraction of the AVM axon through the UNC-6 receptor UNC-40 [the worm homolog of vertebrate Deleted in Colorectal Cancer (DCC)] and its cofactor MADD-2, which signals through both the UNC-34 (Ena) and the CED-10 (Rac1) downstream pathways. LIN-14 stimulated UNC-6-mediated axon attraction in part by increasing UNC-40 abundance. Our study indicated that lin-4 microRNA reduced the activity of LIN-14 to terminate UNC-6-mediated axon guidance of AVM neurons.
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Affiliation(s)
- Yan Zou
- Division of Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229, USA
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Coló GP, Lafuente EM, Teixidó J. The MRL proteins: adapting cell adhesion, migration and growth. Eur J Cell Biol 2012; 91:861-8. [PMID: 22555291 DOI: 10.1016/j.ejcb.2012.03.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 03/08/2012] [Accepted: 03/12/2012] [Indexed: 11/19/2022] Open
Abstract
MIG-10, RIAM and Lamellipodin (Lpd) are the founding members of the MRL family of multi-adaptor molecules. These proteins have common domain structures but display distinct functions in cell migration and adhesion, signaling, and in cell growth. The binding of RIAM with active Rap1 and with talin provides these MRL molecules with important regulatory roles on integrin-mediated cell adhesion and migration. Furthermore, RIAM and Lpd can regulate actin dynamics through their binding to actin regulatory Ena/VASP proteins. Recent data generated with the Drosophila MRL ortholog called Pico and with RIAM in melanoma cells indicate that these proteins can also regulate cell growth. As MRL proteins represent a relatively new family, many questions on their structure-function relationships remain unanswered, including regulation of their expression, post-translational modifications, new interactions, involvement in signaling and their knockout mice phenotype.
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Affiliation(s)
- Georgina P Coló
- Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas, Madrid, Spain
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Stavoe AKH, Colón-Ramos DA. Netrin instructs synaptic vesicle clustering through Rac GTPase, MIG-10, and the actin cytoskeleton. ACTA ACUST UNITED AC 2012; 197:75-88. [PMID: 22451697 PMCID: PMC3317799 DOI: 10.1083/jcb.201110127] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Netrin is a chemotrophic factor known to regulate a number of neurodevelopmental processes, including cell migration, axon guidance, and synaptogenesis. Although the role of Netrin in synaptogenesis is conserved throughout evolution, the mechanisms by which it instructs synapse assembly are not understood. Here we identify a mechanism by which the Netrin receptor UNC-40/DCC instructs synaptic vesicle clustering in vivo. UNC-40 localized to presynaptic regions in response to Netrin. We show that UNC-40 interacted with CED-5/DOCK180 and instructed CED-5 presynaptic localization. CED-5 in turn signaled through CED-10/Rac1 and MIG-10/Lamellipodin to organize the actin cytoskeleton in presynaptic regions. Localization of this signaling pathway to presynaptic regions was necessary for synaptic vesicle clustering during synapse assembly but not for the subcellular localization of active zone proteins. Thus, vesicle clustering and localization of active zone proteins are instructed by separate pathways downstream of Netrin. Our data indicate that signaling modules known to organize the actin cytoskeleton during guidance can be co-opted to instruct synaptic vesicle clustering.
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Affiliation(s)
- Andrea K H Stavoe
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06536, USA
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