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Christophers B, Leahy SN, Soffar DB, von Saucken VE, Broadie K, Baylies MK. Muscle cofilin alters neuromuscular junction postsynaptic development to strengthen functional neurotransmission. Development 2024; 151:dev202558. [PMID: 38869008 PMCID: PMC11266751 DOI: 10.1242/dev.202558] [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: 11/21/2023] [Accepted: 06/05/2024] [Indexed: 06/14/2024]
Abstract
Cofilin, an actin-severing protein, plays key roles in muscle sarcomere addition and maintenance. Our previous work found that Drosophila cofilin (DmCFL) knockdown in muscle causes progressive deterioration of muscle structure and function and produces features seen in nemaline myopathy caused by cofilin mutations. We hypothesized that disruption of actin cytoskeleton dynamics by DmCFL knockdown would impact other aspects of muscle development, and, thus, conducted an RNA-sequencing analysis that unexpectedly revealed upregulated expression of numerous neuromuscular junction (NMJ) genes. We found that DmCFL is enriched in the muscle postsynaptic compartment and that DmCFL muscle knockdown causes F-actin disorganization in this subcellular domain prior to the sarcomere defects observed later in development. Despite NMJ gene expression changes, we found no significant changes in gross presynaptic Bruchpilot active zones or total postsynaptic glutamate receptor levels. However, DmCFL knockdown resulted in mislocalization of GluRIIA class glutamate receptors in more deteriorated muscles and strongly impaired NMJ transmission strength. These findings expand our understanding of the roles of cofilin in muscle to include NMJ structural development and suggest that NMJ defects may contribute to the pathophysiology of nemaline myopathy.
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Affiliation(s)
- Briana Christophers
- Weill Cornell–Rockefeller–Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Shannon N. Leahy
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
| | - David B. Soffar
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Victoria E. von Saucken
- Weill Cornell–Rockefeller–Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10065, USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
- Kennedy Center for Research on Human Development, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
| | - Mary K. Baylies
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
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2
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Clayworth K, Gilbert M, Auld V. Cell Biology Techniques for Studying Drosophila Peripheral Glial Cells. Cold Spring Harb Protoc 2024; 2024:pdb.top108159. [PMID: 37399179 DOI: 10.1101/pdb.top108159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
Glial cells are essential for the proper development and functioning of the peripheral nervous system (PNS). The ability to study the biology of glial cells is therefore critical for our ability to understand PNS biology and address PNS maladies. The genetic and proteomic pathways underlying vertebrate peripheral glial biology are understandably complex, with many layers of redundancy making it sometimes difficult to study certain facets of PNS biology. Fortunately, many aspects of vertebrate peripheral glial biology are conserved with those of the fruit fly, Drosophila melanogaster With simple and powerful genetic tools and fast generation times, Drosophila presents an accessible and versatile model for studying the biology of peripheral glia. We introduce here three techniques for studying the cell biology of peripheral glia of Drosophila third-instar larvae. With fine dissection tools and common laboratory reagents, third-instar larvae can be dissected, with extraneous tissues removed, revealing the central nervous system (CNS) and PNS to be processed using a standard immunolabeling protocol. To improve the resolution of peripheral nerves in the z-plane, we describe a cryosectioning method to achieve 10- to 20-µm thick coronal sections of whole larvae, which can then be immunolabeled using a modified version of standard immunolabeling techniques. Finally, we describe a proximity ligation assay (PLA) for detecting close proximity between two proteins-thus inferring protein interaction-in vivo in third-instar larvae. These methods, further described in our associated protocols, can be used to improve our understanding of Drosophila peripheral glia biology, and thus our understanding of PNS biology.
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Affiliation(s)
- Katherine Clayworth
- Department of Zoology, Cell and Developmental Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Mary Gilbert
- Department of Zoology, Cell and Developmental Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Vanessa Auld
- Department of Zoology, Cell and Developmental Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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3
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Christophers B, Leahy SN, Soffar DB, von Saucken VE, Broadie K, Baylies MK. Muscle cofilin alters neuromuscular junction postsynaptic development to strengthen functional neurotransmission. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.21.568166. [PMID: 38045306 PMCID: PMC10690168 DOI: 10.1101/2023.11.21.568166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Cofilin, an actin severing protein, plays critical roles in muscle sarcomere addition and maintenance. Our previous work has shown Drosophila cofilin (DmCFL) knockdown causes progressive deterioration of muscle structure and function and produces features seen in nemaline myopathy (NM) caused by cofilin mutations. We hypothesized that disruption of actin cytoskeleton dynamics by DmCFL knockdown would impact other aspects of muscle development, and, thus, conducted an RNA sequencing analysis which unexpectedly revealed upregulated expression of numerous neuromuscular junction (NMJ) genes. We found that DmCFL is enriched in the muscle postsynaptic compartment and that DmCFL deficiency causes F-actin disorganization in this subcellular domain prior to the sarcomere defects observed later in development. Despite NMJ gene expression changes, we found no significant changes in gross presynaptic Bruchpilot active zones or total postsynaptic glutamate receptor levels. However, DmCFL knockdown results in mislocalization of glutamate receptors containing the GluRIIA subunit in more deteriorated muscles and neurotransmission strength is strongly impaired. These findings expand our understanding of cofilin's roles in muscle to include NMJ structural development and suggest that NMJ defects may contribute to NM pathophysiology.
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Affiliation(s)
- Briana Christophers
- Weill Cornell–Rockefeller–Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, 10065, USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Shannon N. Leahy
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
| | - David B. Soffar
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Victoria E. von Saucken
- Weill Cornell–Rockefeller–Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, 10065, USA
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
- Kennedy Center for Research on Human Development, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, TN 37235, USA
| | - Mary K. Baylies
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
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4
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Chou VT, Johnson SA, Van Vactor D. Synapse development and maturation at the drosophila neuromuscular junction. Neural Dev 2020; 15:11. [PMID: 32741370 PMCID: PMC7397595 DOI: 10.1186/s13064-020-00147-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/14/2020] [Indexed: 12/12/2022] Open
Abstract
Synapses are the sites of neuron-to-neuron communication and form the basis of the neural circuits that underlie all animal cognition and behavior. Chemical synapses are specialized asymmetric junctions between a presynaptic neuron and a postsynaptic target that form through a series of diverse cellular and subcellular events under the control of complex signaling networks. Once established, the synapse facilitates neurotransmission by mediating the organization and fusion of synaptic vesicles and must also retain the ability to undergo plastic changes. In recent years, synaptic genes have been implicated in a wide array of neurodevelopmental disorders; the individual and societal burdens imposed by these disorders, as well as the lack of effective therapies, motivates continued work on fundamental synapse biology. The properties and functions of the nervous system are remarkably conserved across animal phyla, and many insights into the synapses of the vertebrate central nervous system have been derived from studies of invertebrate models. A prominent model synapse is the Drosophila melanogaster larval neuromuscular junction, which bears striking similarities to the glutamatergic synapses of the vertebrate brain and spine; further advantages include the simplicity and experimental versatility of the fly, as well as its century-long history as a model organism. Here, we survey findings on the major events in synaptogenesis, including target specification, morphogenesis, and the assembly and maturation of synaptic specializations, with a emphasis on work conducted at the Drosophila neuromuscular junction.
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Affiliation(s)
- Vivian T Chou
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Seth A Johnson
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
| | - David Van Vactor
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
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Wang SJH, Sinclair DAR, Kim HY, Kinsey SD, Yoo B, Shih CRY, Wong KKL, Krieger C, Harden N, Verheyen EM. Homeodomain-interacting protein kinase (Hipk) plays roles in nervous system and muscle structure and function. PLoS One 2020; 15:e0221006. [PMID: 32187190 PMCID: PMC7080231 DOI: 10.1371/journal.pone.0221006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 02/13/2020] [Indexed: 12/26/2022] Open
Abstract
Homeodomain-interacting protein kinases (Hipks) have been previously associated with cell proliferation and cancer, however, their effects in the nervous system are less well understood. We have used Drosophila melanogaster to evaluate the effects of altered Hipk expression on the nervous system and muscle. Using genetic manipulation of Hipk expression we demonstrate that knockdown and over-expression of Hipk produces early adult lethality, possibly due to the effects on the nervous system and muscle involvement. We find that optimal levels of Hipk are critical for the function of dopaminergic neurons and glial cells in the nervous system, as well as muscle. Furthermore, manipulation of Hipk affects the structure of the larval neuromuscular junction (NMJ) by promoting its growth. Hipk regulates the phosphorylation of the synapse-associated cytoskeletal protein Hu-li tai shao (Hts; adducin in mammals) and modulates the expression of two important protein kinases, Calcium-calmodulin protein kinase II (CaMKII) and Partitioning-defective 1 (PAR-1), all of which may alter neuromuscular structure/function and influence lethality. Hipk also modifies the levels of an important nuclear protein, TBPH, the fly orthologue of TAR DNA-binding protein 43 (TDP-43), which may have relevance for understanding motor neuron diseases.
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Affiliation(s)
- Simon J. H. Wang
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Donald A. R. Sinclair
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Hae-Yoon Kim
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Stephen D. Kinsey
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Byoungjoo Yoo
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Claire R. Y. Shih
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Kenneth K. L. Wong
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Charles Krieger
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Nicholas Harden
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Esther M. Verheyen
- Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
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6
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McNeill EM, Warinner C, Alkins S, Taylor A, Heggeness H, DeLuca TF, Fulga TA, Wall DP, Griffith LC, Van Vactor D. The conserved microRNA miR-34 regulates synaptogenesis via coordination of distinct mechanisms in presynaptic and postsynaptic cells. Nat Commun 2020; 11:1092. [PMID: 32107390 PMCID: PMC7046720 DOI: 10.1038/s41467-020-14761-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 01/31/2020] [Indexed: 01/30/2023] Open
Abstract
Micro(mi)RNA-based post-transcriptional regulatory mechanisms have been broadly implicated in the assembly and modulation of synaptic connections required to shape neural circuits, however, relatively few specific miRNAs have been identified that control synapse formation. Using a conditional transgenic toolkit for competitive inhibition of miRNA function in Drosophila, we performed an unbiased screen for novel regulators of synapse morphogenesis at the larval neuromuscular junction (NMJ). From a set of ten new validated regulators of NMJ growth, we discovered that miR-34 mutants display synaptic phenotypes and cell type-specific functions suggesting distinct downstream mechanisms in the presynaptic and postsynaptic compartments. A search for conserved downstream targets for miR-34 identified the junctional receptor CNTNAP4/Neurexin-IV (Nrx-IV) and the membrane cytoskeletal effector Adducin/Hu-li tai shao (Hts) as proteins whose synaptic expression is restricted by miR-34. Manipulation of miR-34, Nrx-IV or Hts-M function in motor neurons or muscle supports a model where presynaptic miR-34 inhibits Nrx-IV to influence active zone formation, whereas, postsynaptic miR-34 inhibits Hts to regulate the initiation of bouton formation from presynaptic terminals. Although micro(mi)RNA-based post-transcriptional regulatory mechanisms have been implicated in the assembly and modulation of synaptic connections, few miRNAs have been identified that control synapse formation. Here, authors performed an unbiased screen for novel regulators of synapse morphogenesis at the Drosophila larval neuromuscular junction and discovered that miR-34 inhibits Nrx-IV to influence active zone formation, whereas, postsynaptic miR-34 inhibits Hts to regulate the initiation of bouton formation from presynaptic terminals.
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Affiliation(s)
- Elizabeth M McNeill
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA.,Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA
| | - Chloe Warinner
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA
| | - Stephen Alkins
- Department of Biology and Volen National Center for Complex Systems, Brandeis University, Waltham, MA, 02454, USA
| | - Alicia Taylor
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA.,Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA
| | - Hansine Heggeness
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA
| | - Todd F DeLuca
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA
| | - Tudor A Fulga
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA.,Weatherall Institute, Oxford University, Oxford, UK
| | - Dennis P Wall
- Department of Pediatrics, Division of Systems Medicine, Stanford University, Palo Alto, CA, 94305, USA
| | - Leslie C Griffith
- Department of Biology and Volen National Center for Complex Systems, Brandeis University, Waltham, MA, 02454, USA
| | - David Van Vactor
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA.
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Tettweiler G, Blaquiere JA, Wray NB, Verheyen EM. Hipk is required for JAK/STAT activity during development and tumorigenesis. PLoS One 2019; 14:e0226856. [PMID: 31891940 PMCID: PMC6938406 DOI: 10.1371/journal.pone.0226856] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 12/05/2019] [Indexed: 12/24/2022] Open
Abstract
Drosophila has been instrumental as a model system in studying signal transduction and revealing molecular functions in development and human diseases. A point mutation in the Drosophila Janus kinase JAK (called hop) causes constitutive activation of the JAK/STAT pathway. We provide robust genetic evidence that the Homeodomain interacting protein kinase (Hipk) is required for endogenous JAK/STAT activity. Overexpression of Hipk can phenocopy the effects of overactive JAK/STAT mutations and lead to melanized tumors, and loss of Hipk can suppress the effects of hyperactive JAK/STAT. Further, the loss of the pathway effector Stat92E can suppress Hipk induced overgrowth. Interaction studies show that Hipk can physically interact with Stat92E and regulate Stat92E subcellular localization. Together our results show that Hipk is a novel factor required for effective JAK/STAT signaling.
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Affiliation(s)
- Gritta Tettweiler
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, B.C Canada
| | - Jessica A. Blaquiere
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, B.C Canada
| | - Nathan B. Wray
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, B.C Canada
| | - Esther M. Verheyen
- Department of Molecular Biology and Biochemistry, Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, B.C Canada
- * E-mail:
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8
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Wang Q, Han TH, Nguyen P, Jarnik M, Serpe M. Tenectin recruits integrin to stabilize bouton architecture and regulate vesicle release at the Drosophila neuromuscular junction. eLife 2018; 7:35518. [PMID: 29901439 PMCID: PMC6040883 DOI: 10.7554/elife.35518] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/13/2018] [Indexed: 11/15/2022] Open
Abstract
Assembly, maintenance and function of synaptic junctions depend on extracellular matrix (ECM) proteins and their receptors. Here we report that Tenectin (Tnc), a Mucin-type protein with RGD motifs, is an ECM component required for the structural and functional integrity of synaptic specializations at the neuromuscular junction (NMJ) in Drosophila. Using genetics, biochemistry, electrophysiology, histology and electron microscopy, we show that Tnc is secreted from motor neurons and striated muscles and accumulates in the synaptic cleft. Tnc selectively recruits αPS2/βPS integrin at synaptic terminals, but only the cis Tnc/integrin complexes appear to be biologically active. These complexes have distinct pre- and postsynaptic functions, mediated at least in part through the local engagement of the spectrin-based membrane skeleton: the presynaptic complexes control neurotransmitter release, while postsynaptic complexes ensure the size and architectural integrity of synaptic boutons. Our study reveals an unprecedented role for integrin in the synaptic recruitment of spectrin-based membrane skeleton. Nerve cells or neurons can communicate with each other by releasing chemical messengers into the gap between them, the synapse. Both neurons and synapses are surrounded by a network of proteins called the extracellular matrix, which anchors, protects and supports the synapse. The matrix also helps to regulate the dynamic communication across the synapses and consequently neurons. Little is known about the proteins of the extracellular matrix, in particular about the ones involved in structural support. This is especially important for the so-called neuromuscular junctions, where neurons stimulate muscle contraction and trigger vigorous movement. Receptor proteins on cell surfaces, such as integrins, can bind to the extracellular matrix proteins to anchor the cells and are important for all cell junctions, including synaptic junctions. But because of their many essential roles during development, it was unclear how integrins modulate the activity of the synapse. To investigate this further, Wang et al. studied the neuromuscular junctions of fruit flies. The experiments revealed that both muscle and neurons secrete a large protein called Tenectin, which accumulates into the small space between the neuron and the muscle, the synaptic cleft. This protein can bind to integrin and is necessary to support the neuromuscular junction structurally and functionally. Wang et al. discovered that Tenectin works by gathering integrins on the surface of the neuron and the muscle. In the neuron, Tenectin forms complexes with integrin to regulate the release of neurotransmitters. In the muscle, the complexes provide support to the synaptic structures. However, when Tenectin was experimentally removed, it only disrupted the integrins at the neuromuscular junction, without affecting integrins in other regions of the cells, such as the site where the muscle uses integrins to attach to the tendon. Moreover, without Tenectin an important intracellular scaffolding meshwork that lines up and reinforces cell membranes was no longer organized properly at the synapse. A next step will be to identify the missing components between Tenectin/integrin complexes on the surface of neurons and the neurotransmitter release machinery inside the cells. The extracellular matrix and its receptors play fundamental roles in the development and function of the nervous system. A better knowledge of the underlying mechanisms will help us to better understand the complex interplay between the synapse and the extracellular matrix.
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Affiliation(s)
- Qi Wang
- Section on Cellular Communication, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Tae Hee Han
- Section on Cellular Communication, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Peter Nguyen
- Section on Cellular Communication, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Michal Jarnik
- Section on Intracellular Protein Trafficking, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Mihaela Serpe
- Section on Cellular Communication, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
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9
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Stephens R, Lim K, Portela M, Kvansakul M, Humbert PO, Richardson HE. The Scribble Cell Polarity Module in the Regulation of Cell Signaling in Tissue Development and Tumorigenesis. J Mol Biol 2018; 430:3585-3612. [PMID: 29409995 DOI: 10.1016/j.jmb.2018.01.011] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/19/2018] [Accepted: 01/19/2018] [Indexed: 01/22/2023]
Abstract
The Scribble cell polarity module, comprising Scribbled (Scrib), Discs-large (Dlg) and Lethal-2-giant larvae (Lgl), has a tumor suppressive role in mammalian epithelial cancers. The Scribble module proteins play key functions in the establishment and maintenance of different modes of cell polarity, as well as in the control of tissue growth, differentiation and directed cell migration, and therefore are major regulators of tissue development and homeostasis. Whilst molecular details are known regarding the roles of Scribble module proteins in cell polarity regulation, their precise mode of action in the regulation of other key cellular processes remains enigmatic. An accumulating body of evidence indicates that Scribble module proteins play scaffolding roles in the control of various signaling pathways, which are linked to the control of tissue growth, differentiation and cell migration. Multiple Scrib, Dlg and Lgl interacting proteins have been discovered, which are involved in diverse processes, however many function in the regulation of cellular signaling. Herein, we review the components of the Scrib, Dlg and Lgl protein interactomes, and focus on the mechanism by which they regulate cellular signaling pathways in metazoans, and how their disruption leads to cancer.
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Affiliation(s)
- Rebecca Stephens
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Krystle Lim
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Marta Portela
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute (CSIC), Avenida Doctor Arce, 37, Madrid 28002, Spain
| | - Marc Kvansakul
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Victoria, Australia
| | - Patrick O Humbert
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Victoria, Australia; Department of Biochemistry & Molecular Biology, University of Melbourne, Melbourne, Victoria 3010, Australia; Department of Pathology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Helena E Richardson
- Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Victoria, Australia; Department of Biochemistry & Molecular Biology, University of Melbourne, Melbourne, Victoria 3010, Australia; Department of Anatomy & Neurobiology, University of Melbourne, Melbourne, Victoria 3010, Australia.
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10
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Gan G, Zhang C. The precise subcellular localization of Dlg in the Drosophila larva body wall using improved pre-embedding immuno-EM. J Neurosci Res 2017; 96:467-480. [PMID: 29231975 DOI: 10.1002/jnr.24139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 07/12/2017] [Accepted: 07/21/2017] [Indexed: 12/21/2022]
Abstract
Discs-large (Dlg) plays important roles in nerve tissue and epithelial tissue in Drosophila. However, the precise positioning of Dlg in the neuromuscular junction remains to be confirmed using an optimized labeling method. In this study, we improved the method of pre-embedding immunogold electron microscopy without the osmic tetroxide procedure, and we found that Lowicryl K4 M resin and low temperature helped to preserve the authenticity of the labeling signal with relatively good contrast. Dlg was strongly expressed in the entire subsynaptic reticulum (SSR) membrane of type Ib boutons, expressed in parts of the SSR membrane of type Is boutons, weakly expressed in axon terminals and axons, and not expressed in pre- or postsynaptic membranes of type Is boutons. In muscle cells and stratum corneum cells, Dlg was expressed both in the cytoplasm and in organelles with biomembranes. The precise location of Dlg in SSR membranes, rather than in postsynaptic membranes, shows that Dlg, with its multiple domains, acts as a remote or indirect regulator in postsynaptic signal transduction.
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Affiliation(s)
- Guangming Gan
- Medical School Southeast University, Nanjing, China.,Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Southeast University, Nanjing, China
| | - Chenchen Zhang
- Medical School Southeast University, Nanjing, China.,Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Southeast University, Nanjing, China
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11
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The Long 3'UTR mRNA of CaMKII Is Essential for Translation-Dependent Plasticity of Spontaneous Release in Drosophila melanogaster. J Neurosci 2017; 37:10554-10566. [PMID: 28954869 DOI: 10.1523/jneurosci.1313-17.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 09/05/2017] [Accepted: 09/19/2017] [Indexed: 12/27/2022] Open
Abstract
A null mutation of the Drosophila calcium/calmodulin-dependent protein kinase II gene (CaMKII) was generated using homologous recombination. Null animals survive to larval and pupal stages due to a large maternal contribution of CaMKII mRNA, which consists of a short 3'-untranslated region (UTR) form lacking regulatory elements that guide local translation. The selective loss of the long 3'UTR mRNA in CaMKII-null larvae allows us to test its role in plasticity. Development and evoked function of the larval neuromuscular junction are surprisingly normal, but the resting rate of miniature excitatory junctional potentials (mEJPs) is significantly lower in CaMKII mutants. Mutants also lack the ability to increase mEJP rate in response to spaced depolarization, a type of activity-dependent plasticity shown to require both transcription and translation. Consistent with this, overexpression of miR-289 in wild-type animals blocks plasticity of spontaneous release. In addition to the defects in regulation of mEJP rate, CaMKII protein is largely lost from synapses in the mutant. All phenotypes are non-sex-specific and rescued by a fosmid containing the entire wild-type CaMKII locus, but only viability and CaMKII localization are rescued by genomic fosmids lacking the long 3'UTR. This suggests that synaptic CaMKII accumulates by two distinct mechanisms: local synthesis requiring the long 3'UTR form of CaMKII mRNA and a process that requires zygotic transcription of CaMKII mRNA. The origin of synaptic CaMKII also dictates its functionality. Locally translated CaMKII has a privileged role in regulation of spontaneous release, which cannot be fulfilled by synaptic CaMKII from the other pool.SIGNIFICANCE STATEMENT As a regulator of synaptic development and plasticity, CaMKII has important roles in both normal and pathological function of the nervous system. CaMKII shows high conservation between Drosophila and humans, underscoring the usefulness of Drosophila in modeling its function. Drosophila CaMKII-null mutants remain viable throughout development, enabling morphological and electrophysiological characterization. Although the structure of the synapse is normal, maternally contributed CaMKII does not localize to synapses. Zygotic production of CaMKII mRNA with a long 3'-untranslated region is necessary for modulating spontaneous neurotransmission in an activity-dependent manner, but not for viability. These data argue that regulation of CaMKII localization and levels by local transcriptional processes is conserved. This is the first demonstration of distinct functions for Drosophila CaMKII mRNA variants.
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Krieger C, Wang SJH, Yoo SH, Harden N. Adducin at the Neuromuscular Junction in Amyotrophic Lateral Sclerosis: Hanging on for Dear Life. Front Cell Neurosci 2016; 10:11. [PMID: 26858605 PMCID: PMC4731495 DOI: 10.3389/fncel.2016.00011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 01/13/2016] [Indexed: 12/11/2022] Open
Abstract
The neurological dysfunction in amyotrophic lateral sclerosis (ALS)/motor neurone disease (MND) is associated with defective nerve-muscle contacts early in the disease suggesting that perturbations of cell adhesion molecules (CAMs) linking the pre- and post-synaptic components of the neuromuscular junction (NMJ) are involved. To search for candidate proteins implicated in this degenerative process, researchers have studied the Drosophila larval NMJ and find that the cytoskeleton-associated protein, adducin, is ideally placed to regulate synaptic contacts. By controlling the levels of synaptic proteins, adducin can de-stabilize synaptic contacts. Interestingly, elevated levels of phosphorylated adducin have been reported in ALS patients and in a mouse model of the disease. Adducin is regulated by phosphorylation through protein kinase C (PKC), some isoforms of which exhibit Ca2+-dependence, raising the possibility that changes in intracellular Ca2+ might alter PKC activation and secondarily influence adducin phosphorylation. Furthermore, adducin has interactions with the alpha subunit of the Na+/K+-ATPase. Thus, the phosphorylation of adducin may secondarily influence synaptic stability at the NMJ and so influence pre- and post-synaptic integrity at the NMJ in ALS.
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Affiliation(s)
- Charles Krieger
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University Burnaby, BC, Canada
| | - Simon Ji Hau Wang
- Department of Biomedical Physiology and Kinesiology, Simon Fraser UniversityBurnaby, BC, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser UniversityBurnaby, BC, Canada
| | - Soo Hyun Yoo
- Department of Biomedical Physiology and Kinesiology, Simon Fraser UniversityBurnaby, BC, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser UniversityBurnaby, BC, Canada
| | - Nicholas Harden
- Department of Molecular Biology and Biochemistry, Simon Fraser University Burnaby, BC, Canada
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Wang S, Yoo S, Kim HY, Wang M, Zheng C, Parkhouse W, Krieger C, Harden N. Detection of in situ protein-protein complexes at the Drosophila larval neuromuscular junction using proximity ligation assay. J Vis Exp 2015:52139. [PMID: 25650626 DOI: 10.3791/52139] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Discs large (Dlg) is a conserved member of the membrane-associated guanylate kinase family, and serves as a major scaffolding protein at the larval neuromuscular junction (NMJ) in Drosophila. Previous studies have shown that the postsynaptic distribution of Dlg at the larval NMJ overlaps with that of Hu-li tai shao (Hts), a homologue to the mammalian adducins. In addition, Dlg and Hts are observed to form a complex with each other based on co-immunoprecipitation experiments involving whole adult fly lysates. Due to the nature of these experiments, however, it was unknown whether this complex exists specifically at the NMJ during larval development. Proximity Ligation Assay (PLA) is a recently developed technique used mostly in cell and tissue culture that can detect protein-protein interactions in situ. In this assay, samples are incubated with primary antibodies against the two proteins of interest using standard immunohistochemical procedures. The primary antibodies are then detected with a specially designed pair of oligonucleotide-conjugated secondary antibodies, termed PLA probes, which can be used to generate a signal only when the two probes have bound in close proximity to each other. Thus, proteins that are in a complex can be visualized. Here, it is demonstrated how PLA can be used to detect in situ protein-protein interactions at the Drosophila larval NMJ. The technique is performed on larval body wall muscle preparations to show that a complex between Dlg and Hts does indeed exist at the postsynaptic region of NMJs.
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Affiliation(s)
- Simon Wang
- Department of Molecular Biology and Biochemistry, Simon Fraser University
| | - SooHyun Yoo
- Department of Molecular Biology and Biochemistry, Simon Fraser University
| | - Hae-Yoon Kim
- Department of Molecular Biology and Biochemistry, Simon Fraser University
| | - Mannan Wang
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University
| | - Clare Zheng
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University
| | - Wade Parkhouse
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University
| | - Charles Krieger
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University
| | - Nicholas Harden
- Department of Molecular Biology and Biochemistry, Simon Fraser University;
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