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Bercier V, Hubbard JM, Fidelin K, Duroure K, Auer TO, Revenu C, Wyart C, Del Bene F. Dynactin1 depletion leads to neuromuscular synapse instability and functional abnormalities. Mol Neurodegener 2019; 14:27. [PMID: 31291987 PMCID: PMC6617949 DOI: 10.1186/s13024-019-0327-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 06/10/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Dynactin subunit 1 is the largest subunit of the dynactin complex, an activator of the molecular motor protein complex dynein. Reduced levels of DCTN1 mRNA and protein have been found in sporadic amyotrophic lateral sclerosis (ALS) patients, and mutations have been associated with disease, but the role of this protein in disease pathogenesis is still unknown. METHODS We characterized a Dynactin1a depletion model in the zebrafish embryo and combined in vivo molecular analysis of primary motor neuron development with live in vivo axonal transport assays in single cells to investigate ALS-related defects. To probe neuromuscular junction (NMJ) function and organization we performed paired motor neuron-muscle electrophysiological recordings and GCaMP calcium imaging in live, intact larvae, and the synapse structure was investigated by electron microscopy. RESULTS Here we show that Dynactin1a depletion is sufficient to induce defects in the development of spinal cord motor neurons and in the function of the NMJ. We observe synapse instability, impaired growth of primary motor neurons, and higher failure rates of action potentials at the NMJ. In addition, the embryos display locomotion defects consistent with NMJ dysfunction. Rescue of the observed phenotype by overexpression of wild-type human DCTN1-GFP indicates a cell-autonomous mechanism. Synaptic accumulation of DCTN1-GFP, as well as ultrastructural analysis of NMJ synapses exhibiting wider synaptic clefts, support a local role for Dynactin1a in synaptic function. Furthermore, live in vivo analysis of axonal transport and cytoskeleton dynamics in primary motor neurons show that the phenotype reported here is independent of modulation of these processes. CONCLUSIONS Our study reveals a novel role for Dynactin1 in ALS pathogenesis, where it acts cell-autonomously to promote motor neuron synapse stability independently of dynein-mediated axonal transport.
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Affiliation(s)
- Valérie Bercier
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, Sorbonne Université, F-75005 Paris, France
- Present Address: VIB-KU Leuven, Center for Brain & Disease Research, Leuven, Belgium
| | - Jeffrey M. Hubbard
- Sorbonne Université, Inserm, CNRS, AP-HP, Institut du Cerveau et de la Moelle Épinière, ICM, F-75013 Paris, France
| | - Kevin Fidelin
- Sorbonne Université, Inserm, CNRS, AP-HP, Institut du Cerveau et de la Moelle Épinière, ICM, F-75013 Paris, France
- Present Address: Zuckerman Mind Brain Behavior Institute, Columbia University, New York, USA
| | - Karine Duroure
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, Sorbonne Université, F-75005 Paris, France
| | - Thomas O. Auer
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, Sorbonne Université, F-75005 Paris, France
- Present Address: Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Céline Revenu
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, Sorbonne Université, F-75005 Paris, France
| | - Claire Wyart
- Sorbonne Université, Inserm, CNRS, AP-HP, Institut du Cerveau et de la Moelle Épinière, ICM, F-75013 Paris, France
| | - Filippo Del Bene
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, Sorbonne Université, F-75005 Paris, France
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2
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Echbarthi M, Vallin J, Grantham J. Interactions between monomeric CCTδ and p150 Glued: A novel function for CCTδ at the cell periphery distinct from the protein folding activity of the molecular chaperone CCT. Exp Cell Res 2018; 370:137-149. [PMID: 29913154 DOI: 10.1016/j.yexcr.2018.06.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 01/08/2023]
Abstract
Chaperonin containing tailless complex polypeptide 1 (CCT) is a molecular chaperone consisting of eight distinct protein subunits, that when oligomeric is essential for the folding of newly synthesized tubulin and actin. In addition to folding, CCT activity includes functions of individual subunits in their monomeric form. For example, when CCTδ monomer levels are increased in cultured mammalian cells, numerous cell surface protrusions are formed from retraction fibres, indicating that an underlying function for the CCTδ monomer exists. Here, using a yeast two-hybrid screen we identify the dynactin complex component p150Glued as a binding partner for CCTδ and show by siRNA depletion that this interaction is required for the formation of CCTδ-induced cell surface protrusions. Intact microtubules are necessary for the formation of the protrusions, consistent with microtubule minus end transport driving the retraction fibre formation and depletion of either p150Glued or the dynactin complex-associated transmembrane protein dynAP prevents the previously observed localization of GFP-CCTδ to the plasma membrane. Wound healing assays reveal that CCTδ monomer levels influence directional cell migration and together our observations demonstrate that in addition to the folding activity of CCT in its oligomer form, a monomeric subunit is associated with events that involve the assembled cytoskeleton.
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Affiliation(s)
- Meriem Echbarthi
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530, Sweden
| | - Josefine Vallin
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530, Sweden
| | - Julie Grantham
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530, Sweden.
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3
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Tsoumpekos G, Nemetschke L, Knust E. Drosophila Big bang regulates the apical cytocortex and wing growth through junctional tension. J Cell Biol 2018; 217:1033-1045. [PMID: 29326288 PMCID: PMC5839783 DOI: 10.1083/jcb.201705104] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/22/2017] [Accepted: 11/28/2017] [Indexed: 01/28/2023] Open
Abstract
Growth of epithelial tissues is regulated by a plethora of components, including signaling and scaffolding proteins, but also by junctional tension, mediated by the actomyosin cytoskeleton. However, how these players are spatially organized and functionally coordinated is not well understood. Here, we identify the Drosophila melanogaster scaffolding protein Big bang as a novel regulator of growth in epithelial cells of the wing disc by ensuring proper junctional tension. Loss of big bang results in the reduction of the regulatory light chain of nonmuscle myosin, Spaghetti squash. This is associated with an increased apical cell surface, decreased junctional tension, and smaller wings. Strikingly, these phenotypic traits of big bang mutant discs can be rescued by expressing constitutively active Spaghetti squash. Big bang colocalizes with Spaghetti squash in the apical cytocortex and is found in the same protein complex. These results suggest that in epithelial cells of developing wings, the scaffolding protein Big bang controls apical cytocortex organization, which is important for regulating cell shape and tissue growth.
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Affiliation(s)
- Giorgos Tsoumpekos
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Linda Nemetschke
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Elisabeth Knust
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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4
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Kreko-Pierce T, Eaton BA. The Drosophila LC8 homolog cut up specifies the axonal transport of proteasomes. J Cell Sci 2017; 130:3388-3398. [PMID: 28808087 DOI: 10.1242/jcs.207027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 08/09/2017] [Indexed: 01/05/2023] Open
Abstract
Because of their functional polarity and elongated morphologies, microtubule-based transport of proteins and organelles is critical for normal neuronal function. The proteasome is required throughout the neuron for the highly regulated degradation of a broad set of protein targets whose functions underlie key physiological responses, including synaptic plasticity and axonal degeneration. Molecularly, the relationship between proteasome transport and the transport of the targets of proteasomes is unclear. The dynein motor complex is required for the microtubule-based motility of numerous proteins and organelles in neurons. Here, we demonstrate that microtubule-based transport of proteasomes within the neuron in Drosophila utilizes a different dynein light chain to that used by synaptic proteins. Live imaging of proteasomes and synaptic vesicle proteins in axons and synapses finds that these cargoes traffic independently, and that proteasomes exhibit significantly reduced retrograde transport velocities compared to those of synaptic vesicle proteins. Genetic and biochemical analyses reveals that the Drosophila homolog of the LC8 dynein light chains (mammalian DYNLL1 and DYNLL2), called Cut up, binds proteasomes and functions specifically during their transport. These data support the model that Cut up functions to specify the dynein-mediated transport of neuronal proteasomes.
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Affiliation(s)
- Tabita Kreko-Pierce
- The Barshop Institute for Longevity and Aging Studies, Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Benjamin A Eaton
- The Barshop Institute for Longevity and Aging Studies, Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Hosaka Y, Inoshita T, Shiba-Fukushima K, Cui C, Arano T, Imai Y, Hattori N. Reduced TDP-43 Expression Improves Neuronal Activities in a Drosophila Model of Perry Syndrome. EBioMedicine 2017. [PMID: 28625517 PMCID: PMC5514405 DOI: 10.1016/j.ebiom.2017.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Parkinsonian Perry syndrome, involving mutations in the dynein motor component dynactin or p150Glued, is characterized by TDP-43 pathology in affected brain regions, including the substantia nigra. However, the molecular relationship between p150Glued and TDP-43 is largely unknown. Here, we report that a reduction in TDP-43 protein levels alleviates the synaptic defects of neurons expressing the Perry mutant p150G50R in Drosophila. Dopaminergic expression of p150G50R, which decreases dopamine release, disrupts motor ability and reduces the lifespan of Drosophila. p150G50R expression also causes aggregation of dense core vesicles (DCVs), which contain monoamines and neuropeptides, and disrupts the axonal flow of DCVs, thus decreasing synaptic strength. The above phenotypes associated with Perry syndrome are improved by the removal of a copy of Drosophila TDP-43 TBPH, thus suggesting that the stagnation of axonal transport by dynactin mutations promotes TDP-43 aggregation and interferes with the dynamics of DCVs and synaptic activities. Fly model of Perry syndrome exhibits motor disturbance and impaired dopamine release. Perry mutation in dynactin produces aggregation of dense core vesicles (DCVs) in axons and disrupts axonal flux of DCVs. Removal of a copy of the TDP-43 gene improves retrograde flux of DCVs.
Parkinsonian Perry syndrome (PS), caused by mutations in a component of the retrograde transport complex, Dynactin, is pathologically characterized by the accumulation of an RNA-binding protein, TDP-43, in affected neurons. The neuronal accumulation of TDP-43 is observed in various neurodegenerative diseases including amyotrophic lateral sclerosis and Alzheimer's disease. We report that decreased TDP-43 expression improves defects in the axonal transport of dense core vesicles and in the dopamine release in a Drosophila PS model. This study provides insight into the possibility that a transient decrease in TDP-43 in neurons may be a promising therapeutic approach for treating neurodegenerative disorders associated with TDP-43 pathology, including PS.
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Affiliation(s)
- Yuka Hosaka
- Department of Neurology, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Tsuyoshi Inoshita
- Department of Treatment and Research in Multiple Sclerosis and Neuro-intractable Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Kahori Shiba-Fukushima
- Department of Treatment and Research in Multiple Sclerosis and Neuro-intractable Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Changxu Cui
- Department of Research for Parkinson's Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Taku Arano
- Center for Genomic and Regenerative Medicine, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Yuzuru Imai
- Department of Neurology, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan; Department of Treatment and Research in Multiple Sclerosis and Neuro-intractable Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan.
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan; Department of Treatment and Research in Multiple Sclerosis and Neuro-intractable Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan; Department of Research for Parkinson's Disease, Juntendo University, Graduate School of Medicine, Tokyo 113-8421, Japan.
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6
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Mallik B, Dwivedi MK, Mushtaq Z, Kumari M, Verma PK, Kumar V. Regulation of neuromuscular junction organization by Rab2 and its effector ICA69 in Drosophila. Development 2017; 144:2032-2044. [PMID: 28455372 DOI: 10.1242/dev.145920] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 04/19/2017] [Indexed: 12/31/2022]
Abstract
The mechanisms underlying synaptic differentiation, which involves neuronal membrane and cytoskeletal remodeling, are not completely understood. We performed a targeted RNAi-mediated screen of Drosophila BAR-domain proteins and identified islet cell autoantigen 69 kDa (ICA69) as one of the key regulators of morphological differentiation of the larval neuromuscular junction (NMJ). We show that Drosophila ICA69 colocalizes with α-Spectrin at the NMJ. The conserved N-BAR domain of ICA69 deforms liposomes in vitro Full-length ICA69 and the ICAC but not the N-BAR domain of ICA69 induce filopodia in cultured cells. Consistent with its cytoskeleton regulatory role, ICA69 mutants show reduced α-Spectrin immunoreactivity at the larval NMJ. Manipulating levels of ICA69 or its interactor PICK1 alters the synaptic level of ionotropic glutamate receptors (iGluRs). Moreover, reducing PICK1 or Rab2 levels phenocopies ICA69 mutation. Interestingly, Rab2 regulates not only synaptic iGluR but also ICA69 levels. Thus, our data suggest that: (1) ICA69 regulates NMJ organization through a pathway that involves PICK1 and Rab2, and (2) Rab2 functions genetically upstream of ICA69 and regulates NMJ organization and targeting/retention of iGluRs by regulating ICA69 levels.
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Affiliation(s)
- Bhagaban Mallik
- Department of Biological Sciences, AB-3, Indian Institute of Science Education and Research, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Manish Kumar Dwivedi
- Department of Biological Sciences, AB-3, Indian Institute of Science Education and Research, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Zeeshan Mushtaq
- Department of Biological Sciences, AB-3, Indian Institute of Science Education and Research, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Manisha Kumari
- National Institute of Plant Genome Research (NIPGR), New Delhi 110067, India
| | - Praveen Kumar Verma
- National Institute of Plant Genome Research (NIPGR), New Delhi 110067, India
| | - Vimlesh Kumar
- Department of Biological Sciences, AB-3, Indian Institute of Science Education and Research, Bhauri, Bhopal, Madhya Pradesh 462066, India
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Ghezzi A, Zomeno M, Pietrzykowski AZ, Atkinson NS. Immediate-early alcohol-responsive miRNA expression in Drosophila. J Neurogenet 2016; 30:195-204. [PMID: 27845601 DOI: 10.1080/01677063.2016.1252764] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
At the core of the changes characteristic of alcoholism are alterations in gene expression in the brain of the addicted individual. These changes are believed to underlie some of the neuroadaptations that promote compulsive drinking. Unfortunately, the mechanisms by which alcohol consumption produces changes in gene expression remain poorly understood. MicroRNAs (miRNAs) have emerged as important regulators of gene expression because they can coordinately modulate the translation efficiency of large sets of specific mRNAs. Here, we investigate the early miRNA responses elicited by an acute sedating dose of alcohol in the Drosophila model organism. In our analysis, we combine the power of next-generation sequencing with Drosophila genetics to identify alcohol-sensitive miRNAs and to functionally test them for a role in modulating alcohol sensitivity. We identified 14 known Drosophila miRNAs, and 13 putative novel miRNAs that respond to an acute sedative exposure to alcohol. Using the GeneSwitch Gal4/UAS system, a subset of these ethanol-responsive miRNAs was functionally tested to determine their individual contribution in modulating ethanol sensitivity. We identified two microRNAs that when overexpressed significantly increased ethanol sensitivity: miR-6 and miR-310. MicroRNA target prediction analysis revealed that the different alcohol-responsive miRNAs target-overlapping sets of mRNAs. Alcoholism is the product of accumulated cellular changes produced by chronic ethanol consumption. Although all of the changes described herein are extremely rapid responses evoked by a single ethanol exposure, understanding the gene expression changes that occur in the first few minutes after ethanol exposure will help us to categorize ethanol responses into those that are near instantaneous and those that are emergent responses produced only by repeated ethanol exposure.
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Affiliation(s)
- Alfredo Ghezzi
- a Department of Biology , University of Puerto Rico , Rio Piedras, San Juan , Puerto Rico
| | - Marie Zomeno
- b Department of Neuroscience and Waggoner Center for Alcohol and Addiction Research , The University of Texas at Austin , Austin , TX , USA
| | - Andrzej Z Pietrzykowski
- c The Biologically Inspired Neural and Dynamical Systems (BINDS) Lab, Department of Computer Science , University of Massachusetts Amherst , Amherst , MA , USA
| | - Nigel S Atkinson
- b Department of Neuroscience and Waggoner Center for Alcohol and Addiction Research , The University of Texas at Austin , Austin , TX , USA
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8
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Calero-Cuenca FJ, Espinosa-Vázquez JM, Reina-Campos M, Díaz-Meco MT, Moscat J, Sotillos S. Nuclear fallout provides a new link between aPKC and polarized cell trafficking. BMC Biol 2016; 14:32. [PMID: 27089924 PMCID: PMC4836198 DOI: 10.1186/s12915-016-0253-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 03/31/2016] [Indexed: 12/31/2022] Open
Abstract
Background Cell polarity, essential for cell physiology and tissue coherence, emerges as a consequence of asymmetric localization of protein complexes and directional trafficking of cellular components. Although molecules required in both processes are well known their relationship is still poorly understood. Results Here we show a molecular link between Nuclear Fallout (Nuf), an adaptor of Rab11-GTPase to the microtubule motor proteins during Recycling Endosome (RE) trafficking, and aPKC, a pivotal kinase in the regulation of cell polarity. We demonstrate that aPKC phosphorylates Nuf modifying its subcellular distribution. Accordingly, in aPKC mutants Nuf and Rab11 accumulate apically indicating altered RE delivery. We show that aPKC localization in the apico-lateral cortex is dynamic. When we block exocytosis, by means of exocyst-sec mutants, aPKC accumulates inside the cells. Moreover, apical aPKC concentration is reduced in nuf mutants, suggesting aPKC levels are maintained by recycling. Conclusions We demonstrate that active aPKC interacts with Nuf, phosphorylating it and, as a result, modifying its subcellular distribution. We propose a regulatory loop by which Nuf promotes aPKC apical recycling until sufficient levels of active aPKC are reached. Thus, we provide a novel link between cell polarity regulation and traffic control in epithelia. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0253-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Francisco J Calero-Cuenca
- CABD, CSIC/JA/UPO, Campus Universidad Pablo de Olavide, Ctra. De Utrera Km. 1, Seville, 41013, Spain
| | | | | | - María T Díaz-Meco
- Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA
| | - Jorge Moscat
- Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA
| | - Sol Sotillos
- CABD, CSIC/JA/UPO, Campus Universidad Pablo de Olavide, Ctra. De Utrera Km. 1, Seville, 41013, Spain.
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Deshpande M, Rodal AA. The Crossroads of Synaptic Growth Signaling, Membrane Traffic and Neurological Disease: Insights from Drosophila. Traffic 2015; 17:87-101. [PMID: 26538429 DOI: 10.1111/tra.12345] [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: 09/16/2015] [Revised: 10/29/2015] [Accepted: 10/29/2015] [Indexed: 12/13/2022]
Abstract
Neurons require target-derived autocrine and paracrine growth factors to maintain proper identity, innervation, homeostasis and survival. Neuronal growth factor signaling is highly dependent on membrane traffic, both for the packaging and release of the growth factors themselves, and for regulation of intracellular signaling by their transmembrane receptors. Here, we review recent findings from the Drosophila larval neuromuscular junction (NMJ) that illustrate how specific steps of intracellular traffic and inter-organelle interactions impinge on signaling, particularly in the bone morphogenic protein, Wingless and c-Jun-activated kinase pathways, regulating elaboration and stability of NMJ arbors, construction of synapses and synaptic transmission and homeostasis. These membrane trafficking and signaling pathways have been implicated in human motor neuron diseases including amyotrophic lateral sclerosis and hereditary spastic paraplegia, highlighting their importance for neuronal health and survival.
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Affiliation(s)
| | - Avital A Rodal
- Department of Biology, Brandeis University, Waltham, MA, USA
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10
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Eiseler T, Wille C, Koehler C, Illing A, Seufferlein T. Protein Kinase D2 Assembles a Multiprotein Complex at the Trans-Golgi Network to Regulate Matrix Metalloproteinase Secretion. J Biol Chem 2015; 291:462-77. [PMID: 26507660 DOI: 10.1074/jbc.m115.673582] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Indexed: 11/06/2022] Open
Abstract
Vesicle formation and fission are tightly regulated at the trans-Golgi network (TGN) during constitutive secretion. Two major protein families regulate these processes: members of the adenosyl-ribosylation factor family of small G-proteins (ARFs) and the protein kinase D (PKD) family of serine/threonine kinases. The functional relationship between these two key regulators of protein transport from the TGN so far is elusive. We here demonstrate the assembly of a novel functional protein complex at the TGN and its key members: cytosolic PKD2 binds ARF-like GTPase (ARL1) and shuttles ARL1 to the TGN. ARL1, in turn, localizes Arfaptin2 to the TGN. At the TGN, where PKD2 interacts with active ARF1, PKD2, and ARL1 are required for the assembly of a complex comprising of ARF1 and Arfaptin2 leading to secretion of matrix metalloproteinase-2 and -7. In conclusion, our data indicate that PKD2 is a core factor in the formation of this multiprotein complex at the TGN that controls constitutive secretion of matrix metalloproteinase cargo.
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Affiliation(s)
- Tim Eiseler
- From the Department of Internal Medicine I, Ulm University, Albert Einstein Allee 23, D-89081 Ulm, Germany and
| | - Christoph Wille
- From the Department of Internal Medicine I, Ulm University, Albert Einstein Allee 23, D-89081 Ulm, Germany and
| | - Conny Koehler
- the Department of Internal Medicine I, Martin-Luther University Halle-Wittenberg, Ernst-Grube, Strasse 40, D-06120 Halle (Saale), Germany
| | - Anett Illing
- From the Department of Internal Medicine I, Ulm University, Albert Einstein Allee 23, D-89081 Ulm, Germany and
| | - Thomas Seufferlein
- From the Department of Internal Medicine I, Ulm University, Albert Einstein Allee 23, D-89081 Ulm, Germany and
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11
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Natarajan R, Barber K, Buckley A, Cho P, Egbejimi A, Wairkar YP. Tricornered Kinase Regulates Synapse Development by Regulating the Levels of Wiskott-Aldrich Syndrome Protein. PLoS One 2015; 10:e0138188. [PMID: 26393506 PMCID: PMC4578898 DOI: 10.1371/journal.pone.0138188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 08/26/2015] [Indexed: 11/19/2022] Open
Abstract
Precise regulation of synapses during development is essential to ensure accurate neural connectivity and function of nervous system. Many signaling pathways, including the mTOR (mechanical Target of Rapamycin) pathway operate in neurons to maintain genetically determined number of synapses during development. mTOR, a kinase, is shared between two functionally distinct multi-protein complexes- mTORC1 and mTORC2, that act downstream of Tuberous Sclerosis Complex (TSC). We and others have suggested an important role for TSC in synapse development at the Drosophila neuromuscular junction (NMJ) synapses. In addition, our data suggested that the regulation of the NMJ synapse numbers in Drosophila largely depends on signaling via mTORC2. In the present study, we further this observation by identifying Tricornered (Trc) kinase, a serine/threonine kinase as a likely mediator of TSC signaling. trc genetically interacts with Tsc2 to regulate the number of synapses. In addition, Tsc2 and trc mutants exhibit a dramatic reduction in synaptic levels of WASP, an important regulator of actin polymerization. We show that Trc regulates the WASP levels largely, by regulating the transcription of WASP. Finally, we show that overexpression of WASP (Wiskott-Aldrich Syndrome Protein) in trc mutants can suppress the increase in the number of synapses observed in trc mutants, suggesting that WASP regulates synapses downstream of Trc. Thus, our data provide a novel insight into how Trc may regulate the genetic program that controls the number of synapses during development.
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Affiliation(s)
- Rajalaxmi Natarajan
- Department of Neurology and Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Kara Barber
- Neuroscience Graduate Program, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Amanda Buckley
- Department of Neurology and Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Phillip Cho
- Summer Undergraduate Research Program, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Anuoluwapo Egbejimi
- Department of Neurology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Neuroscience Graduate Program, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yogesh P. Wairkar
- Department of Neurology and Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
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12
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Kessels MM, Qualmann B. Different functional modes of BAR domain proteins in formation and plasticity of mammalian postsynapses. J Cell Sci 2015; 128:3177-85. [PMID: 26285709 DOI: 10.1242/jcs.174193] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A plethora of cell biological processes involve modulations of cellular membranes. By using extended lipid-binding interfaces, some proteins have the power to shape membranes by attaching to them. Among such membrane shapers, the superfamily of Bin-Amphiphysin-Rvs (BAR) domain proteins has recently taken center stage. Extensive structural work on BAR domains has revealed a common curved fold that can serve as an extended membrane-binding interface to modulate membrane topologies and has allowed the grouping of the BAR domain superfamily into subfamilies with structurally slightly distinct BAR domain subtypes (N-BAR, BAR, F-BAR and I-BAR). Most BAR superfamily members are expressed in the mammalian nervous system. Neurons are elaborately shaped and highly compartmentalized cells. Therefore, analyses of synapse formation and of postsynaptic reorganization processes (synaptic plasticity) - a basis for learning and memory formation - has unveiled important physiological functions of BAR domain superfamily members. These recent advances, furthermore, have revealed that the functions of BAR domain proteins include different aspects. These functions are influenced by the often complex domain organization of BAR domain proteins. In this Commentary, we review these recent insights and propose to classify BAR domain protein functions into (1) membrane shaping, (2) physical integration, (3) action through signaling components, and (4) suppression of other BAR domain functions.
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Affiliation(s)
- Michael M Kessels
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University, Nonnenplan 2-4, 07743 Jena, Germany
| | - Britta Qualmann
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University, Nonnenplan 2-4, 07743 Jena, Germany
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Chang L, Kreko-Pierce T, Eaton BA. The guanine exchange factor Gartenzwerg and the small GTPase Arl1 function in the same pathway with Arfaptin during synapse growth. Biol Open 2015; 4:947-53. [PMID: 26116655 PMCID: PMC4542281 DOI: 10.1242/bio.011262] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The generation of neuronal morphology requires transport vesicles originating from the Golgi apparatus (GA) to deliver specialized components to the axon and dendrites. Drosophila Arfaptin is a membrane-binding protein localized to the GA that is required for the growth of the presynaptic nerve terminal. Here we provide biochemical, cellular and genetic evidence that the small GTPase Arl1 and the guanine-nucleotide exchange factor (GEF) Gartenzwerg are required for Arfaptin function at the Golgi during synapse growth. Our data define a new signaling pathway composed of Arfaptin, Arl1, and Garz, required for the generation of normal synapse morphology.
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Affiliation(s)
- Leo Chang
- Department of Physiology, Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Tabita Kreko-Pierce
- Department of Physiology, Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Benjamin A Eaton
- Department of Physiology, Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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Ojelade SA, Acevedo SF, Rothenfluh A. The role of the actin cytoskeleton in regulating Drosophila behavior. Rev Neurosci 2014; 24:471-84. [PMID: 24077615 DOI: 10.1515/revneuro-2013-0017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 08/21/2013] [Indexed: 10/26/2022]
Abstract
Over the past decade, the function of the cytoskeleton has been studied extensively in developing and mature neurons. Actin, a major cytoskeletal protein, is indispensable for the structural integrity and plasticity of neurons and their synapses. Disruption of actin dynamics has significant consequence for neurons, neuronal circuits, and the functions they govern. In particular, cell adhesion molecules, members of the Rho family of GTPases, and actin-binding proteins are important modulators of actin dynamics and neuronal as well as behavioral plasticity. In this review, we discuss recent advances in Drosophila that highlight the importance of actin regulatory proteins in mediating fly behaviors such as circadian rhythm, courtship behavior, learning and memory, and the development of drug addiction.
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Adult neuronal Arf6 controls ethanol-induced behavior with Arfaptin downstream of Rac1 and RhoGAP18B. J Neurosci 2013; 32:17706-13. [PMID: 23223291 DOI: 10.1523/jneurosci.1944-12.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Alcohol use disorders affect millions of individuals. However, the genes and signaling pathways involved in behavioral ethanol responses and addiction are poorly understood. Here we identify a conserved biochemical pathway that underlies the sedating effects of ethanol in Drosophila. Mutations in the Arf6 small GTPase signaling pathway cause hypersensitivity to ethanol-induced sedation. We show that Arf6 functions in the adult nervous system to control ethanol-induced behavior. We also find that the Drosophila Arfaptin protein directly binds to the activated forms of Arf6 and Rac1 GTPases, and mutants in Arfaptin also display ethanol sensitivity. Arf6 acts downstream of Rac1 and Arfaptin to regulate ethanol-induced behaviors, and we thus demonstrate that this conserved Rac1/Arfaptin/Arf6 pathway is a major mediator of ethanol-induced behavioral responses.
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