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Mizumoto K, Jin Y, Bessereau JL. Synaptogenesis: unmasking molecular mechanisms using Caenorhabditis elegans. Genetics 2023; 223:iyac176. [PMID: 36630525 PMCID: PMC9910414 DOI: 10.1093/genetics/iyac176] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/22/2022] [Indexed: 01/13/2023] Open
Abstract
The nematode Caenorhabditis elegans is a research model organism particularly suited to the mechanistic understanding of synapse genesis in the nervous system. Armed with powerful genetics, knowledge of complete connectomics, and modern genomics, studies using C. elegans have unveiled multiple key regulators in the formation of a functional synapse. Importantly, many signaling networks display remarkable conservation throughout animals, underscoring the contributions of C. elegans research to advance the understanding of our brain. In this chapter, we will review up-to-date information of the contribution of C. elegans to the understanding of chemical synapses, from structure to molecules and to synaptic remodeling.
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Affiliation(s)
- Kota Mizumoto
- Department of Zoology, University of British Columbia, Vancouver V6T 1Z3, Canada
| | - Yishi Jin
- Department of Neurobiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Jean-Louis Bessereau
- Univ Lyon, University Claude Bernard Lyon 1, CNRS UMR 5284, INSERM U 1314, Melis, 69008 Lyon, France
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2
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Cortés E, Pak JS, Özkan E. Structure and evolution of neuronal wiring receptors and ligands. Dev Dyn 2023; 252:27-60. [PMID: 35727136 PMCID: PMC10084454 DOI: 10.1002/dvdy.512] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 06/13/2022] [Accepted: 06/14/2022] [Indexed: 01/04/2023] Open
Abstract
One of the fundamental properties of a neuronal circuit is the map of its connections. The cellular and developmental processes that allow for the growth of axons and dendrites, selection of synaptic targets, and formation of functional synapses use neuronal surface receptors and their interactions with other surface receptors, secreted ligands, and matrix molecules. Spatiotemporal regulation of the expression of these receptors and cues allows for specificity in the developmental pathways that wire stereotyped circuits. The families of molecules controlling axon guidance and synapse formation are generally conserved across animals, with some important exceptions, which have consequences for neuronal connectivity. Here, we summarize the distribution of such molecules across multiple taxa, with a focus on model organisms, evolutionary processes that led to the multitude of such molecules, and functional consequences for the diversification or loss of these receptors.
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Affiliation(s)
- Elena Cortés
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.,The Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
| | - Joseph S Pak
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.,The Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA.,The Neuroscience Institute, University of Chicago, Chicago, Illinois, USA
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3
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Nandigrami P, Szczepaniak F, Boughter CT, Dehez F, Chipot C, Roux B. Computational Assessment of Protein-Protein Binding Specificity within a Family of Synaptic Surface Receptors. J Phys Chem B 2022; 126:7510-7527. [PMID: 35787023 DOI: 10.1021/acs.jpcb.2c02173] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atomic-level information is essential to explain the formation of specific protein complexes in terms of structure and dynamics. The set of Dpr and DIP proteins, which play a key role in the neuromorphogenesis in the nervous system of Drosophila melanogaster, offer a rich paradigm to learn about protein-protein recognition. Many members of the DIP subfamily cross-react with several members of the Dpr family and vice versa. While there exists a total of 231 possible Dpr-DIP heterodimer complexes from the 21 Dpr and 11 DIP proteins, only 57 "cognate" pairs have been detected by surface plasmon resonance (SPR) experiments, suggesting that the remaining 174 pairs have low or unreliable binding affinity. Our goal is to assess the performance of computational approaches to characterize the global set of interactions between Dpr and DIP proteins and identify the specificity of binding between each DIP with their corresponding Dpr binding partners. In addition, we aim to characterize how mutations influence the specificity of the binding interaction. In this work, a wide range of knowledge-based and physics-based approaches are utilized, including mutual information, linear discriminant analysis, homology modeling, molecular dynamics simulations, Poisson-Boltzmann continuum electrostatics calculations, and alchemical free energy perturbation to decipher the origin of binding specificity of the Dpr-DIP complexes examined. Ultimately, the results show that those two broad strategies are complementary, with different strengths and limitations. Biological inter-relations are more clearly revealed through knowledge-based approaches combining evolutionary and structural features, the molecular determinants controlling binding specificity can be predicted accurately with physics-based approaches based on atomic models.
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Affiliation(s)
- Prithviraj Nandigrami
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, United States
| | - Florence Szczepaniak
- Unité Mixte de Recherche No. 7019, Université de Lorraine, B.P. 70239, 54506 Vandœuvre-lès-Nancy cedex, France
| | - Christopher T Boughter
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, United States
| | - François Dehez
- Unité Mixte de Recherche No. 7019, Université de Lorraine, B.P. 70239, 54506 Vandœuvre-lès-Nancy cedex, France
| | - Christophe Chipot
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, United States.,Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, Unité Mixte de Recherche No. 7019, Université de Lorraine, B.P. 70239, 54506 Vandœuvre-lès-Nancy cedex, France.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, United States
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, United States
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4
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Bali N, Lee HK(P, Zinn K. Sticks and Stones, a conserved cell surface ligand for the Type IIa RPTP Lar, regulates neural circuit wiring in Drosophila. eLife 2022; 11:e71469. [PMID: 35356892 PMCID: PMC9000958 DOI: 10.7554/elife.71469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 03/31/2022] [Indexed: 11/13/2022] Open
Abstract
Type IIa receptor-like protein tyrosine phosphatases (RPTPs) are essential for neural development. They have cell adhesion molecule (CAM)-like extracellular domains that interact with cell-surface ligands and coreceptors. We identified the immunoglobulin superfamily CAM Sticks and Stones (Sns) as a new partner for the Drosophila Type IIa RPTP Lar. Lar and Sns bind to each other in embryos and in vitro, and the human Sns ortholog, Nephrin, binds to human Type IIa RPTPs. Genetic analysis shows that Lar and Sns function together to regulate larval neuromuscular junction development, axon guidance in the mushroom body (MB), and innervation of the optic lobe (OL) medulla by R7 photoreceptors. In the neuromuscular system, Lar and Sns are both required in motor neurons, and may function as coreceptors. In the MB and OL, however, the relevant Lar-Sns interactions are in trans (between neurons), so Sns functions as a Lar ligand in these systems.
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Affiliation(s)
- Namrata Bali
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Hyung-Kook (Peter) Lee
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Kai Zinn
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
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5
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Stødkilde K, Nielsen JT, Petersen SV, Paetzold B, Brüggemann H, Mulder FAA, Andersen CBF. Solution Structure of the Cutibacterium acnes-Specific Protein RoxP and Insights Into Its Antioxidant Activity. Front Cell Infect Microbiol 2022; 12:803004. [PMID: 35223541 PMCID: PMC8873378 DOI: 10.3389/fcimb.2022.803004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 01/24/2022] [Indexed: 11/13/2022] Open
Abstract
Cutibacterium acnes is a predominant bacterium on human skin and is generally regarded as commensal. Recently, the abundantly secreted protein produced by C. acnes, RoxP, was shown to alleviate radical-induced cell damage, presumably via antioxidant activity, which could potentially be harnessed to fortify skin barrier function. The aim of this study was to determine the structure of RoxP and elucidate the mechanisms behind its antioxidative effect. Here, we present the solution structure of RoxP revealing a compact immunoglobulin-like domain containing a long flexible loop which, in concert with the core domain, forms a positively charged groove that could function as a binding site for cofactors or substrates. Although RoxP shares structural features with cell-adhesion proteins, we show that it does not appear to be responsible for adhesion of C. acnes bacteria to human keratinocytes. We identify two tyrosine-containing stretches located in the flexible loop of RoxP, which appear to be responsible for the antioxidant activity of RoxP.
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Affiliation(s)
| | | | | | | | | | - Frans A A Mulder
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
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6
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Sengupta T, Koonce NL, Vázquez-Martínez N, Moyle MW, Duncan LH, Emerson SE, Han X, Shao L, Wu Y, Santella A, Fan L, Bao Z, Mohler W, Shroff H, Colón-Ramos DA. Differential adhesion regulates neurite placement via a retrograde zippering mechanism. eLife 2021; 10:71171. [PMID: 34783657 PMCID: PMC8843091 DOI: 10.7554/elife.71171] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 11/15/2021] [Indexed: 11/13/2022] Open
Abstract
During development, neurites and synapses segregate into specific neighborhoods or layers within nerve bundles. The developmental programs guiding placement of neurites in specific layers, and hence their incorporation into specific circuits, are not well understood. We implement novel imaging methods and quantitative models to document the embryonic development of the C. elegans brain neuropil, and discover that differential adhesion mechanisms control precise placement of single neurites onto specific layers. Differential adhesion is orchestrated via developmentally-regulated expression of the IgCAM SYG-1, and its partner ligand SYG-2. Changes in SYG-1 expression across neuropil layers result in changes in adhesive forces, which sort SYG-2-expressing neurons. Sorting to layers occurs, not via outgrowth from the neurite tip, but via an alternate mechanism of retrograde zippering, involving interactions between neurite shafts. Our study indicates that biophysical principles from differential adhesion govern neurite placement and synaptic specificity in vivo in developing neuropil bundles.
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Affiliation(s)
- Titas Sengupta
- Yale University School of Medicine, New Haven, United States
| | - Noelle L Koonce
- Yale University School of Medicine, New Haven, United States
| | | | - Mark W Moyle
- Yale University School of Medicine, New Haven, United States
| | | | - Sarah E Emerson
- Yale University School of Medicine, New Haven, United States
| | - Xiaofei Han
- National Institutes of Health, Bethesda, United States
| | - Lin Shao
- Yale University School of Medicine, New Haven, United States
| | - Yicong Wu
- National Institutes of Health, Bethesda, United States
| | - Anthony Santella
- Developmental Biology Program, Molecular Cytology Core, Sloan-Kettering Institute, New York, United States
| | - Li Fan
- Helen and Robert Appel Alzheimer's Disease Institute, Weill Cornell Medicine, New York, United States
| | - Zhirong Bao
- Developmental Biology Program, Sloan-Kettering Institute, New York, United States
| | - William Mohler
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, United States
| | - Hari Shroff
- National Institutes of Health, Bethesda, United States
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7
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Wang J, Vaddadi N, Pak JS, Park Y, Quilez S, Roman CA, Dumontier E, Thornton JW, Cloutier JF, Özkan E. Molecular and structural basis of olfactory sensory neuron axon coalescence by Kirrel receptors. Cell Rep 2021; 37:109940. [PMID: 34731636 PMCID: PMC8628261 DOI: 10.1016/j.celrep.2021.109940] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/30/2021] [Accepted: 10/13/2021] [Indexed: 01/21/2023] Open
Abstract
Projections from sensory neurons of olfactory systems coalesce into glomeruli in the brain. The Kirrel receptors are believed to homodimerize via their ectodomains and help separate sensory neuron axons into Kirrel2- or Kirrel3-expressing glomeruli. Here, we present the crystal structures of homodimeric Kirrel receptors and show that the closely related Kirrel2 and Kirrel3 have evolved specific sets of polar and hydrophobic interactions, respectively, disallowing heterodimerization while preserving homodimerization, likely resulting in proper segregation and coalescence of Kirrel-expressing axons into glomeruli. We show that the dimerization interface at the N-terminal immunoglobulin (IG) domains is necessary and sufficient to create homodimers and fail to find evidence for a secondary interaction site in Kirrel ectodomains. Furthermore, we show that abolishing dimerization of Kirrel3 in vivo leads to improper formation of glomeruli in the mouse accessory olfactory bulb as observed in Kirrel3-/- animals. Our results provide evidence for Kirrel3 homodimerization controlling axonal coalescence.
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Affiliation(s)
- Jing Wang
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA; Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL 60637, USA
| | - Neelima Vaddadi
- The Neuro-Montreal Neurological Institute and Hospital, McGill University, Montréal, QC H3A 2B4, Canada; Department of Neurology and Neurosurgery, McGill University, Montréal, QC H3A 2B4, Canada
| | - Joseph S Pak
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA; Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL 60637, USA
| | - Yeonwoo Park
- Committee on Genetics, Genomics and Systems Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Sabrina Quilez
- The Neuro-Montreal Neurological Institute and Hospital, McGill University, Montréal, QC H3A 2B4, Canada; Department of Neurology and Neurosurgery, McGill University, Montréal, QC H3A 2B4, Canada
| | - Christina A Roman
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Emilie Dumontier
- The Neuro-Montreal Neurological Institute and Hospital, McGill University, Montréal, QC H3A 2B4, Canada
| | - Joseph W Thornton
- Committee on Genetics, Genomics and Systems Biology, The University of Chicago, Chicago, IL 60637, USA; Department of Human Genetics, The University of Chicago, Chicago, IL 60637, USA; Department of Ecology and Evolution, The University of Chicago, Chicago, IL 60637, USA
| | - Jean-François Cloutier
- The Neuro-Montreal Neurological Institute and Hospital, McGill University, Montréal, QC H3A 2B4, Canada; Department of Neurology and Neurosurgery, McGill University, Montréal, QC H3A 2B4, Canada; Department of Anatomy and Cell Biology, McGill University, Montréal, QC H3A 0C7, Canada.
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA; Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL 60637, USA.
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8
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Rodríguez-Pérez F, Manford AG, Pogson A, Ingersoll AJ, Martínez-González B, Rape M. Ubiquitin-dependent remodeling of the actin cytoskeleton drives cell fusion. Dev Cell 2021; 56:588-601.e9. [PMID: 33609460 DOI: 10.1016/j.devcel.2021.01.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 11/14/2020] [Accepted: 01/24/2021] [Indexed: 12/11/2022]
Abstract
Cell-cell fusion is a frequent and essential event during development, and its dysregulation causes diseases ranging from infertility to muscle weakness. Fusing cells need to repeatedly remodel their plasma membrane through orchestrated formation and disassembly of actin filaments, but how the dynamic reorganization of the cortical actin cytoskeleton is controlled is still poorly understood. Here, we identified a ubiquitin-dependent toggle switch that establishes reversible actin bundling during mammalian cell fusion. We found that EPS8-IRSp53 complexes stabilize cortical actin bundles at sites of cell contact to promote close membrane alignment. EPS8 monoubiquitylation by CUL3KCTD10 displaces EPS8-IRSp53 from membranes and counteracts actin bundling, a dual activity that restricts actin bundling to allow paired cells to progress with fusion. We conclude that cytoskeletal rearrangements during development are precisely controlled by ubiquitylation, raising the possibility of modulating the efficiency of cell-cell fusion for therapeutic benefit.
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Affiliation(s)
- Fernando Rodríguez-Pérez
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Andrew G Manford
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Angela Pogson
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Andrew J Ingersoll
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Brenda Martínez-González
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Michael Rape
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA.
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9
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Honig B, Shapiro L. Adhesion Protein Structure, Molecular Affinities, and Principles of Cell-Cell Recognition. Cell 2021; 181:520-535. [PMID: 32359436 DOI: 10.1016/j.cell.2020.04.010] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/25/2020] [Accepted: 04/06/2020] [Indexed: 12/14/2022]
Abstract
The ability of cells to organize into multicellular structures in precise patterns requires that they "recognize" one another with high specificity. We discuss recent progress in understanding the molecular basis of cell-cell recognition, including unique phenomena associated with neuronal interactions. We describe structures of select adhesion receptor complexes and their assembly into larger intercellular junction structures and discuss emerging principles that relate cell-cell organization to the binding specificities and energetics of adhesion receptors. Armed with these insights, advances in protein design and gene editing should pave the way for breakthroughs toward understanding the molecular basis of cell patterning in vivo.
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Affiliation(s)
- Barry Honig
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Medicine, Columbia University, New York, NY 10032, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA.
| | - Lawrence Shapiro
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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10
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Belardi B, Son S, Felce JH, Dustin ML, Fletcher DA. Cell-cell interfaces as specialized compartments directing cell function. Nat Rev Mol Cell Biol 2020; 21:750-764. [PMID: 33093672 DOI: 10.1038/s41580-020-00298-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2020] [Indexed: 12/14/2022]
Abstract
Cell-cell interfaces are found throughout multicellular organisms, from transient interactions between motile immune cells to long-lived cell-cell contacts in epithelia. Studies of immune cell interactions, epithelial cell barriers, neuronal contacts and sites of cell-cell fusion have identified a core set of features shared by cell-cell interfaces that critically control their function. Data from diverse cell types also show that cells actively and passively regulate the localization, strength, duration and cytoskeletal coupling of receptor interactions governing cell-cell signalling and physical connections between cells, indicating that cell-cell interfaces have a unique membrane organization that emerges from local molecular and cellular mechanics. In this Review, we discuss recent findings that support the emerging view of cell-cell interfaces as specialized compartments that biophysically constrain the arrangement and activity of their protein, lipid and glycan components. We also review how these biophysical features of cell-cell interfaces allow cells to respond with high selectivity and sensitivity to multiple inputs, serving as the basis for wide-ranging cellular functions. Finally, we consider how the unique properties of cell-cell interfaces present opportunities for therapeutic intervention.
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Affiliation(s)
- Brian Belardi
- Department of Bioengineering & Biophysics Program, UC Berkeley, Berkeley, CA, USA
| | - Sungmin Son
- Department of Bioengineering & Biophysics Program, UC Berkeley, Berkeley, CA, USA
| | | | | | - Daniel A Fletcher
- Department of Bioengineering & Biophysics Program, UC Berkeley, Berkeley, CA, USA. .,Division of Biological Systems & Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
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11
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Jin H, Kim B. Neurite Branching Regulated by Neuronal Cell Surface Molecules in Caenorhabditis elegans. Front Neuroanat 2020; 14:59. [PMID: 32973467 PMCID: PMC7471659 DOI: 10.3389/fnana.2020.00059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/04/2020] [Indexed: 01/02/2023] Open
Abstract
The high synaptic density in the nervous system results from the ability of neurites to branch. Neuronal cell surface molecules play central roles during neurite branch formation. The underlying mechanisms of surface molecule activity have often been elucidated using invertebrates with simple nervous systems. Here, we review recent advances in understanding the molecular mechanisms of neurite branching in the nematode Caenorhabditis elegans. We discuss how cell surface receptor complexes link to and modulate actin dynamics to regulate dendritic and axonal branch formation. The mechanisms of neurite branching are often coupled with other neural circuit developmental processes, such as synapse formation and axon guidance, via the same cell-cell surface molecular interactions. We also cover ectopic and sex-specific neurite branching in C. elegans in an attempt to illustrate the importance of these studies in contributing to our understanding of conserved cell surface molecule regulation of neurite branch formation.
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Affiliation(s)
- HoYong Jin
- Department of Life Science, Dongguk University-Seoul, Goyang, South Korea
| | - Byunghyuk Kim
- Department of Life Science, Dongguk University-Seoul, Goyang, South Korea
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12
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Kirrel3-Mediated Synapse Formation Is Attenuated by Disease-Associated Missense Variants. J Neurosci 2020; 40:5376-5388. [PMID: 32503885 DOI: 10.1523/jneurosci.3058-19.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 05/24/2020] [Accepted: 05/26/2020] [Indexed: 12/12/2022] Open
Abstract
Missense variants in Kirrel3 are repeatedly identified as risk factors for autism spectrum disorder and intellectual disability, but it has not been reported if or how these variants disrupt Kirrel3 function. Previously, we studied Kirrel3 loss of function using KO mice and showed that Kirrel3 is a synaptic adhesion molecule necessary to form one specific type of hippocampal synapse in vivo Here, we developed an in vitro, gain-of-function assay for Kirrel3 using neuron cultures prepared from male and female mice and rats. We find that WT Kirrel3 induces synapse formation selectively between Kirrel3-expressing neurons via homophilic, transcellular binding. We tested six disease-associated Kirrel3 missense variants and found that five attenuate this synaptogenic function. All variants tested traffic to the cell surface and localize to synapses similar to WT Kirrel3. Two tested variants lack homophilic transcellular binding, which likely accounts for their reduced synaptogenic function. Interestingly, we also identified variants that bind in trans but cannot induce synapses, indicating that Kirrel3 transcellular binding is necessary but not sufficient for its synaptogenic function. Collectively, these results suggest Kirrel3 functions as a synaptogenic, cell-recognition molecule, and this function is attenuated by missense variants associated with autism spectrum disorder and intellectual disability. Thus, we provide critical insight to the mechanism of Kirrel3 function and the consequences of missense variants associated with autism and intellectual disability.SIGNIFICANCE STATEMENT Here, we advance our understanding of mechanisms mediating target-specific synapse formation by providing evidence that Kirrel3 transcellular interactions mediate target recognition and signaling to promote synapse development. Moreover, this study tests the effects of disease-associated Kirrel3 missense variants on synapse formation, and thereby, increases understanding of the complex etiology of neurodevelopmental disorders arising from rare missense variants in synaptic genes.
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13
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The novel miR-1269b-regulated protein SVEP1 induces hepatocellular carcinoma proliferation and metastasis likely through the PI3K/Akt pathway. Cell Death Dis 2020; 11:320. [PMID: 32371982 PMCID: PMC7200779 DOI: 10.1038/s41419-020-2535-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/06/2020] [Accepted: 04/22/2020] [Indexed: 12/05/2022]
Abstract
Decreased intercellular adhesion is a key step in the metastasis and recurrence of many cancers, including hepatocellular carcinoma (HCC). SVEP1 is an important cell adhesion molecule that plays a key role in regulating intercellular adhesion and embryonic lymphatic development. However, the expression patterns and roles of SVEP1 in HCC are still largely unknown. We identified SVEP1 expression by analyzing 220 HCC samples from our cancer center. TCGA and GEO online-databases were used for data calibration and validation. SVEP1 was differentially expressed in two groups of HCCs with different risks of recurrence and was deemed as an independent risk factor for the prognosis of HCC. The expression of SVEP1 is negatively related to the proliferation and metastasis of HCC. Downregulation of SVEP1 expression promoted in vitro HCC cell migration, chemotaxis, invasion and proliferation, as well as in vivo tumor growth, local invasion and metastasis in a mouse model. Bioinformatic analysis and RT-PCR results showed that miR-1269b expression is negatively correlated with the SVEP1 expression and the prognosis of HCC patients. Further experiments showed that miR-1269b directly targets and downregulates the expression of SVEP1, which further induces the phosphorylation of Akt at thr308. These regulatory effects ultimately mediate the proliferation and metastasis of HCC cells. SVEP1 could serve as a promising prognostic marker of HCC. MiR-1269b downregulates SVEP1 expression and promotes HCC proliferation and metastasis likely through the PI3k/Akt signaling pathway.
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14
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Rozbesky D, Monistrol J, Jain V, Hillier J, Padilla-Parra S, Jones EY. Drosophila OTK Is a Glycosaminoglycan-Binding Protein with High Conformational Flexibility. Structure 2020; 28:507-515.e5. [PMID: 32187531 PMCID: PMC7203548 DOI: 10.1016/j.str.2020.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 01/29/2020] [Accepted: 02/27/2020] [Indexed: 11/25/2022]
Abstract
The transmembrane protein OTK plays an essential role in plexin and Wnt signaling during Drosophila development. We have determined a crystal structure of the last three domains of the OTK ectodomain and found that OTK shows high conformational flexibility resulting from mobility at the interdomain interfaces. We failed to detect direct binding between Drosophila Plexin A (PlexA) and OTK, which was suggested previously. We found that, instead of PlexA, OTK directly binds semaphorin 1a. Our binding analyses further revealed that glycosaminoglycans, heparin and heparan sulfate, are ligands for OTK and thus may play a role in the Sema1a-PlexA axon guidance system.
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Affiliation(s)
- Daniel Rozbesky
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
| | - Jim Monistrol
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Vitul Jain
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - James Hillier
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Sergi Padilla-Parra
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; Cellular imaging, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London SE1 9RT, UK; Randall Centre for Cell and Molecular Biology, King's College London, London SE1 1UL, UK
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
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15
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Sanes JR, Zipursky SL. Synaptic Specificity, Recognition Molecules, and Assembly of Neural Circuits. Cell 2020; 181:536-556. [DOI: 10.1016/j.cell.2020.04.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/23/2020] [Accepted: 04/06/2020] [Indexed: 01/02/2023]
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16
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Reddy VRAP, Mwangi W, Sadigh Y, Nair V. In vitro Interactions of Chicken Programmed Cell Death 1 (PD-1) and PD-1 Ligand-1 (PD-L1). Front Cell Infect Microbiol 2019; 9:436. [PMID: 31921710 PMCID: PMC6930881 DOI: 10.3389/fcimb.2019.00436] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/05/2019] [Indexed: 12/13/2022] Open
Abstract
In the present study, we determined the in vitro characteristics and binding interactions of chicken PD-1 (chPD-1) and PD-L1 (chPD-L1) and developed a panel of specific monoclonal antibodies against the two proteins. ChPD-1 and chPD-L1 sequence identities and similarities were lower compared with those of humans and other mammalian species. Furthermore, in phylogenetic analysis, chPD-1 and chPD-L1 were grouped separately from the mammalian PD-1 and PD-L1 sequences. As in other species, chPD-1 and chPD-L1 sequences showed signal peptide, extracellular domain, a transmembrane domain and intracellular domain. Based on the three dimensional (3D) structural homology, chPD-1, and chPD-L1 were similar to 3D structures of mammalian PD-1 and PD-L1. Further, Ig V domain of chPD-1 and the Ig V and Ig C domains of chPD-L1 were highly conserved with the mammalian counterparts. In vitro binding interaction studies using Superparamagnetic Dynabeads® confirmed that recombinant soluble chPD-1/PD-L1 fusion proteins and surface chPD-1/PD-L1 proteins interacted with each other on COS cells. Two monoclonal antibodies specific against chPD-1 and five antibodies against chPD-L1 were developed and their specific binding characteristics confirmed by immunofluorescence staining and Western blotting.
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Affiliation(s)
| | - William Mwangi
- Viral Oncogenesis Group, The Pirbright Institute, Pirbright, United Kingdom
| | - Yashar Sadigh
- Viral Oncogenesis Group, The Pirbright Institute, Pirbright, United Kingdom
| | - Venugopal Nair
- Viral Oncogenesis Group, The Pirbright Institute, Pirbright, United Kingdom
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17
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Abstract
Cell-cell fusion is indispensable for creating life and building syncytial tissues and organs. Ever since the discovery of cell-cell fusion, how cells join together to form zygotes and multinucleated syncytia has remained a fundamental question in cell and developmental biology. In the past two decades, Drosophila myoblast fusion has been used as a powerful genetic model to unravel mechanisms underlying cell-cell fusion in vivo. Many evolutionarily conserved fusion-promoting factors have been identified and so has a surprising and conserved cellular mechanism. In this review, we revisit key findings in Drosophila myoblast fusion and highlight the critical roles of cellular invasion and resistance in driving cell membrane fusion.
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Affiliation(s)
- Donghoon M Lee
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA;
| | - Elizabeth H Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA;
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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18
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Abstract
Cell-cell fusion is a fundamental process underlying fertilization, development, regeneration and physiology of metazoans. It is a multi-step process involving cell recognition and adhesion, actin cytoskeletal rearrangements, fusogen engagement, lipid mixing and fusion pore formation, ultimately resulting in the integration of two fusion partners. Here, we focus on the asymmetric actin cytoskeletal rearrangements at the site of fusion, known as the fusogenic synapse, which was first discovered during myoblast fusion in Drosophila embryos and later also found in mammalian muscle and non-muscle cells. At the asymmetric fusogenic synapse, actin-propelled invasive membrane protrusions from an attacking fusion partner trigger actomyosin-based mechanosensory responses in the receiving cell. The interplay between the invasive and resisting forces generated by the two fusion partners puts the fusogenic synapse under high mechanical tension and brings the two cell membranes into close proximity, promoting the engagement of fusogens to initiate fusion pore formation. In this Cell Science at a Glance article and the accompanying poster, we highlight the molecular, cellular and biophysical events at the asymmetric fusogenic synapse using Drosophila myoblast fusion as a model.
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Affiliation(s)
- Ji Hoon Kim
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Elizabeth H Chen
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA .,Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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19
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Kim B. Evolutionarily conserved and divergent functions for cell adhesion molecules in neural circuit assembly. J Comp Neurol 2019; 527:2061-2068. [PMID: 30779135 DOI: 10.1002/cne.24666] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 02/11/2019] [Accepted: 02/11/2019] [Indexed: 12/17/2022]
Abstract
The developing nervous system generates remarkably precise synaptic connections between neurons and their postsynaptic target cells. Numerous neural cell adhesion proteins have been identified to mediate cell recognition between synaptic partners in several model organisms. Here, I review the role of protein interactions of cell adhesion molecules in neural circuit assembly and address how these interactions are utilized to form different neural circuitries in different species. The emerging evidence suggests that the extracellular trans-interactions of cell adhesion proteins for neural wiring are evolutionarily conserved across taxa, but they are often used in different steps of circuit assembly. I also highlight how these conserved protein interactions work together as a group to specify neural connectivity.
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Affiliation(s)
- Byunghyuk Kim
- Department of Life Science, Dongguk University Seoul, Goyang, Republic of Korea
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20
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Hendi A, Kurashina M, Mizumoto K. Intrinsic and extrinsic mechanisms of synapse formation and specificity in C. elegans. Cell Mol Life Sci 2019; 76:2719-2738. [PMID: 31037336 PMCID: PMC11105629 DOI: 10.1007/s00018-019-03109-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/11/2019] [Accepted: 04/15/2019] [Indexed: 12/18/2022]
Abstract
Precise neuronal wiring is critical for the function of the nervous system and is ultimately determined at the level of individual synapses. Neurons integrate various intrinsic and extrinsic cues to form synapses onto their correct targets in a stereotyped manner. In the past decades, the nervous system of nematode (Caenorhabditis elegans) has provided the genetic platform to reveal the genetic and molecular mechanisms of synapse formation and specificity. In this review, we will summarize the recent discoveries in synapse formation and specificity in C. elegans.
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Affiliation(s)
- Ardalan Hendi
- Department of Zoology, The University of British Columbia, 2406-2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Mizuki Kurashina
- Department of Zoology, The University of British Columbia, 2406-2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Kota Mizumoto
- Department of Zoology, The University of British Columbia, 2406-2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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21
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Nihalani D, Solanki AK, Arif E, Srivastava P, Rahman B, Zuo X, Dang Y, Fogelgren B, Fermin D, Gillies CE, Sampson MG, Lipschutz JH. Disruption of the exocyst induces podocyte loss and dysfunction. J Biol Chem 2019; 294:10104-10119. [PMID: 31073028 PMCID: PMC6664173 DOI: 10.1074/jbc.ra119.008362] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/06/2019] [Indexed: 11/06/2022] Open
Abstract
Although the slit diaphragm proteins in podocytes are uniquely organized to maintain glomerular filtration assembly and function, little is known about the underlying mechanisms that participate in trafficking these proteins to the correct location for development and homeostasis. Identifying these mechanisms will likely provide novel targets for therapeutic intervention to preserve podocyte function following glomerular injury. Analysis of structural variation in cases of human nephrotic syndrome identified rare heterozygous deletions of EXOC4 in two patients. This suggested that disruption of the highly-conserved eight-protein exocyst trafficking complex could have a role in podocyte dysfunction. Indeed, mRNA profiling of injured podocytes identified significant exocyst down-regulation. To test the hypothesis that the exocyst is centrally involved in podocyte development/function, we generated homozygous podocyte-specific Exoc5 (a central exocyst component that interacts with Exoc4) knockout mice that showed massive proteinuria and died within 4 weeks of birth. Histological and ultrastructural analysis of these mice showed severe glomerular defects with increased fibrosis, proteinaceous casts, effaced podocytes, and loss of the slit diaphragm. Immunofluorescence analysis revealed that Neph1 and Nephrin, major slit diaphragm constituents, were mislocalized and/or lost. mRNA profiling of Exoc5 knockdown podocytes showed that vesicular trafficking was the most affected cellular event. Mapping of signaling pathways and Western blot analysis revealed significant up-regulation of the mitogen-activated protein kinase and transforming growth factor-β pathways in Exoc5 knockdown podocytes and in the glomeruli of podocyte-specific Exoc5 KO mice. Based on these data, we propose that exocyst-based mechanisms regulate Neph1 and Nephrin signaling and trafficking, and thus podocyte development and function.
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Affiliation(s)
- Deepak Nihalani
- From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425,
| | - Ashish K Solanki
- From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Ehtesham Arif
- From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Pankaj Srivastava
- From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Bushra Rahman
- From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Xiaofeng Zuo
- From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Yujing Dang
- From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Ben Fogelgren
- the Department of Anatomy, Biochemistry, and Physiology, University of Hawaii at Manoa, Honolulu, Hawaii 96813
| | | | | | - Matthew G Sampson
- the Department of Pediatrics-Nephrology and.,Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, and
| | - Joshua H Lipschutz
- From the Department of Medicine, Medical University of South Carolina, Charleston, South Carolina 29425.,the Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
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22
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Abstract
Cell surface transmembrane receptors often form nanometer- to micrometer-scale clusters to initiate signal transduction in response to environmental cues. Extracellular ligand oligomerization, domain-domain interactions, and binding to multivalent proteins all contribute to cluster formation. Here we review the current understanding of mechanisms driving cluster formation in a series of representative receptor systems: glycosylated receptors, immune receptors, cell adhesion receptors, Wnt receptors, and receptor tyrosine kinases. We suggest that these clusters share properties of systems that undergo liquid-liquid phase separation and could be investigated in this light.
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Affiliation(s)
- Lindsay B Case
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; , ,
| | - Jonathon A Ditlev
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; , ,
| | - Michael K Rosen
- Department of Biophysics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; , ,
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23
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Cheng S, Ashley J, Kurleto JD, Lobb-Rabe M, Park YJ, Carrillo RA, Özkan E. Molecular basis of synaptic specificity by immunoglobulin superfamily receptors in Drosophila. eLife 2019; 8:41028. [PMID: 30688651 PMCID: PMC6374074 DOI: 10.7554/elife.41028] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 01/22/2019] [Indexed: 01/19/2023] Open
Abstract
In stereotyped neuronal networks, synaptic connectivity is dictated by cell surface proteins, which assign unique identities to neurons, and physically mediate axon guidance and synapse targeting. We recently identified two groups of immunoglobulin superfamily proteins in Drosophila, Dprs and DIPs, as strong candidates for synapse targeting functions. Here, we uncover the molecular basis of specificity in Dpr-DIP mediated cellular adhesions and neuronal connectivity. First, we present five crystal structures of Dpr-DIP and DIP-DIP complexes, highlighting the evolutionary and structural origins of diversification in Dpr and DIP proteins and their interactions. We further show that structures can be used to rationally engineer receptors with novel specificities or modified affinities, which can be used to study specific circuits that require Dpr-DIP interactions to help establish connectivity. We investigate one pair, engineered Dpr10 and DIP-α, for function in the neuromuscular circuit in flies, and reveal roles for homophilic and heterophilic binding in wiring.
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Affiliation(s)
- Shouqiang Cheng
- Department of Biochemistry and Molecular BiologyUniversity of ChicagoChicagoUnited States
| | - James Ashley
- Department of Molecular Genetics and Cell BiologyUniversity of ChicagoChicagoUnited States
| | - Justyna D Kurleto
- Department of Biochemistry and Molecular BiologyUniversity of ChicagoChicagoUnited States,Faculty of Biochemistry, Biophysics and BiotechnologyJagiellonian UniversityKrakowPoland
| | - Meike Lobb-Rabe
- Department of Molecular Genetics and Cell BiologyUniversity of ChicagoChicagoUnited States,Graduate Program in Cell and Molecular BiologyUniversity of ChicagoChicagoUnited States
| | - Yeonhee Jenny Park
- Department of Biochemistry and Molecular BiologyUniversity of ChicagoChicagoUnited States
| | - Robert A Carrillo
- Department of Molecular Genetics and Cell BiologyUniversity of ChicagoChicagoUnited States
| | - Engin Özkan
- Department of Biochemistry and Molecular BiologyUniversity of ChicagoChicagoUnited States
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24
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Cosmanescu F, Katsamba PS, Sergeeva AP, Ahlsen G, Patel SD, Brewer JJ, Tan L, Xu S, Xiao Q, Nagarkar-Jaiswal S, Nern A, Bellen HJ, Zipursky SL, Honig B, Shapiro L. Neuron-Subtype-Specific Expression, Interaction Affinities, and Specificity Determinants of DIP/Dpr Cell Recognition Proteins. Neuron 2018; 100:1385-1400.e6. [PMID: 30467080 PMCID: PMC6309224 DOI: 10.1016/j.neuron.2018.10.046] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/29/2018] [Accepted: 10/24/2018] [Indexed: 10/27/2022]
Abstract
Binding between DIP and Dpr neuronal recognition proteins has been proposed to regulate synaptic connections between lamina and medulla neurons in the Drosophila visual system. Each lamina neuron was previously shown to express many Dprs. Here, we demonstrate, by contrast, that their synaptic partners typically express one or two DIPs, with binding specificities matched to the lamina neuron-expressed Dprs. A deeper understanding of the molecular logic of DIP/Dpr interaction requires quantitative studies on the properties of these proteins. We thus generated a quantitative affinity-based DIP/Dpr interactome for all DIP/Dpr protein family members. This revealed a broad range of affinities and identified homophilic binding for some DIPs and some Dprs. These data, along with full-length ectodomain DIP/Dpr and DIP/DIP crystal structures, led to the identification of molecular determinants of DIP/Dpr specificity. This structural knowledge, along with a comprehensive set of quantitative binding affinities, provides new tools for functional studies in vivo.
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Affiliation(s)
- Filip Cosmanescu
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Phinikoula S Katsamba
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Alina P Sergeeva
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA
| | - Goran Ahlsen
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA
| | - Saurabh D Patel
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Division of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Boston, MA 02115, USA
| | - Joshua J Brewer
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Liming Tan
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shuwa Xu
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Qi Xiao
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Sonal Nagarkar-Jaiswal
- Department of Molecular and Human Genetics, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Aljoscha Nern
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - S Lawrence Zipursky
- Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Barry Honig
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Systems Biology, Columbia University, New York, NY 10032, USA; Department of Medicine, Columbia University, New York, NY 10032, USA.
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA.
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25
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Interactions between the Ig-Superfamily Proteins DIP-α and Dpr6/10 Regulate Assembly of Neural Circuits. Neuron 2018; 100:1369-1384.e6. [PMID: 30467079 PMCID: PMC7501880 DOI: 10.1016/j.neuron.2018.11.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/28/2018] [Accepted: 10/31/2018] [Indexed: 01/08/2023]
Abstract
Drosophila Dpr (21 paralogs) and DIP proteins (11 paralogs) are cell recognition molecules of the immunoglobulin superfamily (IgSF) that form a complex protein interaction network. DIP and Dpr proteins are expressed in a synaptic layer-specific fashion in the visual system. How interactions between these proteins regulate layer-specific synaptic circuitry is not known. Here we establish that DIP-α and its interacting partners Dpr6 and Dpr10 regulate multiple processes, including arborization within layers, synapse number, layer specificity, and cell survival. We demonstrate that heterophilic binding between Dpr6/10 and DIP-α and homophilic binding between DIP-α proteins promote interactions between processes in vivo. Knockin mutants disrupting the DIP/Dpr binding interface reveal a role for these proteins during normal development, while ectopic expression studies support an instructive role for interactions between DIPs and Dprs in circuit development. These studies support an important role for the DIP/Dpr protein interaction network in regulating cell-type-specific connectivity patterns.
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26
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Ben-Aharon Z, Levitt M, Kalisman N. Automatic Inference of Sequence from Low-Resolution Crystallographic Data. Structure 2018; 26:1546-1554.e2. [PMID: 30293812 DOI: 10.1016/j.str.2018.08.011] [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: 07/06/2017] [Revised: 04/18/2018] [Accepted: 08/23/2018] [Indexed: 11/17/2022]
Abstract
At resolutions worse than 3.5 Å, the electron density is weak or nonexistent at the locations of the side chains. Consequently, the assignment of the protein sequences to their correct positions along the backbone is a difficult problem. In this work, we propose a fully automated computational approach to assign sequence at low resolution. It is based on our surprising observation that standard reciprocal-space indicators, such as the initial unrefined R value, are sensitive enough to detect an erroneous sequence assignment of even a single backbone position. Our approach correctly determines the amino acid type for 15%, 13%, and 9% of the backbone positions in crystallographic datasets with resolutions of 4.0 Å, 4.5 Å, and 5.0 Å, respectively. We implement these findings in an application for threading a sequence onto a backbone structure. For the three resolution ranges, the application threads 83%, 81%, and 64% of the sequences exactly as in the deposited PDB structures.
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Affiliation(s)
- Ziv Ben-Aharon
- Department of Biological Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Michael Levitt
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Nir Kalisman
- Department of Biological Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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27
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Chen J, Wang B, Wu Y. Structural Characterization and Function Prediction of Immunoglobulin-like Fold in Cell Adhesion and Cell Signaling. J Chem Inf Model 2018; 58:532-542. [PMID: 29356528 DOI: 10.1021/acs.jcim.7b00580] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Domains that belong to an immunoglobulin (Ig) fold are extremely abundant in cell surface receptors, which play significant roles in cell-cell adhesion and signaling. Although the structures of domains in an Ig fold share common topology of β-barrels, functions of receptors in adhesion and signaling are regulated by the very heterogeneous binding between these domains. Additionally, only a small number of domains are directly involved in the binding between two multidomain receptors. It is challenging and time consuming to experimentally detect the binding partners of a given receptor and further determine which specific domains in this receptor are responsible for binding. Therefore, current knowledge in the binding mechanism of Ig-fold domains and their impacts on cell adhesion and signaling is very limited. A bioinformatics study can shed light on this topic from a systematic point of view. However, there is so far no computational analysis on the structural and functional characteristics of the entire Ig fold. We constructed nonredundant structural data sets for all domains in Ig fold, depending on their functions in cell adhesion and signaling. We found that data sets of domains in adhesion receptors show different binding preference from domains in signaling receptors. Using structural alignment, we further built a common structural template for each group of a domain data set. By mapping the protein-protein binding interface of each domain in a group onto the surface of its structural template, we found binding interfaces are highly overlapped within each specific group. These overlapped interfaces, we called consensus binding interfaces, are distinguishable among different data sets of domains. Finally, the residue compositions on the consensus interfaces were used as indicators for multiple machine learning algorithms to predict if they can form homotypic interactions with each other. The overall performance of the cross-validation tests shows that our prediction accuracies ranged between 0.6 and 0.8.
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Affiliation(s)
- Jiawen Chen
- Department of Systems and Computational Biology, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Bo Wang
- Department of Systems and Computational Biology, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Yinghao Wu
- Department of Systems and Computational Biology, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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28
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Targeting Neph1 and ZO-1 protein-protein interaction in podocytes prevents podocyte injury and preserves glomerular filtration function. Sci Rep 2017; 7:12047. [PMID: 28935902 PMCID: PMC5608913 DOI: 10.1038/s41598-017-12134-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 09/05/2017] [Indexed: 11/08/2022] Open
Abstract
Targeting protein-protein interaction (PPI) is rapidly becoming an attractive alternative for drug development. While drug development commonly involves inhibiting a PPI, in this study, we show that stabilizing PPI may also be therapeutically beneficial. Junctional proteins Neph1 and ZO-1 and their interaction is an important determinant of the structural integrity of slit diaphragm, which is a critical component of kidney's filtration system. Since injury induces loss of this interaction, we hypothesized that strengthening this interaction may protect kidney's filtration barrier and preserve kidney function. In this study, Neph1-ZO-1 structural complex was screened for the presence of small druggable pockets formed from contributions from both proteins. One such pocket was identified and screened using a small molecule library. Isodesmosine (ISD) a rare naturally occurring amino acid and a biomarker for pulmonary arterial hypertension was selected as the best candidate and to establish the proof of concept, its ability to enhance Neph1-CD and ZO-1 binding was tested. Results from biochemical binding analysis showed that ISD enhanced Neph1 and ZO-1 interaction under in vitro and in vivo conditions. Importantly, ISD treated podocytes were resistant to injury-induced loss of transepithelial permeability. Finally, mouse and zebrafish studies show that ISD protects from injury-induced renal damage.
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29
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Kim B, Emmons SW. Multiple conserved cell adhesion protein interactions mediate neural wiring of a sensory circuit in C. elegans. eLife 2017; 6:29257. [PMID: 28901288 PMCID: PMC5619950 DOI: 10.7554/elife.29257] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Accepted: 09/08/2017] [Indexed: 01/06/2023] Open
Abstract
Nervous system function relies on precise synaptic connections. A number of widely-conserved cell adhesion proteins are implicated in cell recognition between synaptic partners, but how these proteins act as a group to specify a complex neural network is poorly understood. Taking advantage of known connectivity in C. elegans, we identified and studied cell adhesion genes expressed in three interacting neurons in the mating circuits of the adult male. Two interacting pairs of cell surface proteins independently promote fasciculation between sensory neuron HOA and its postsynaptic target interneuron AVG: BAM-2/neurexin-related in HOA binds to CASY-1/calsyntenin in AVG; SAX-7/L1CAM in sensory neuron PHC binds to RIG-6/contactin in AVG. A third, basal pathway results in considerable HOA-AVG fasciculation and synapse formation in the absence of the other two. The features of this multiplexed mechanism help to explain how complex connectivity is encoded and robustly established during nervous system development.
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Affiliation(s)
- Byunghyuk Kim
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States
| | - Scott W Emmons
- Department of Genetics, Albert Einstein College of Medicine, Bronx, United States.,Dominick P Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, United States
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30
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Zadka Ł, Dzięgiel P, Kulus M, Olajossy M. Clinical Phenotype of Depression Affects Interleukin-6 Synthesis. J Interferon Cytokine Res 2017; 37:231-245. [PMID: 28418766 DOI: 10.1089/jir.2016.0074] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Major depressive disorder (MDD) is not a single disease, but a number of various ailments that form one entity. Psychomotor retardation, anhedonia, sleep disorders, an increased suicide risk, and anxiety are the main symptoms that often define the clinical diagnosis of depression. Interleukin-6 (IL-6), as one of the proinflammatory cytokines, seems to be overexpressed during certain mental disorders, including MDD. Overexpression of IL-6 in depression is thought to be a factor associated with bad prognosis and worse disease course. IL-6 may directly affect brain functioning and production of neurotransmitters; moreover, its concentration is correlated with certain clinical symptoms within the wide range of depressive symptomatology. Furthermore, there is a strong correlation between IL-6 synthesis and psychosomatic functioning of the patient. This article discusses potential sources and significance of IL-6 in the pathogenesis of depression.
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Affiliation(s)
- Łukasz Zadka
- 1 Department of Histology and Embryology, Wroclaw Medical University , Wrocław, Poland .,2 II Department of Psychiatry and Psychiatric Rehabilitation, Independent Public Teaching Hospital No 1 in Lublin, Medical University of Lublin , Lublin, Poland
| | - Piotr Dzięgiel
- 1 Department of Histology and Embryology, Wroclaw Medical University , Wrocław, Poland
| | - Michał Kulus
- 1 Department of Histology and Embryology, Wroclaw Medical University , Wrocław, Poland
| | - Marcin Olajossy
- 2 II Department of Psychiatry and Psychiatric Rehabilitation, Independent Public Teaching Hospital No 1 in Lublin, Medical University of Lublin , Lublin, Poland
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31
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Cheng S, Seven AB, Wang J, Skiniotis G, Özkan E. Conformational Plasticity in the Transsynaptic Neurexin-Cerebellin-Glutamate Receptor Adhesion Complex. Structure 2016; 24:2163-2173. [PMID: 27926833 PMCID: PMC5149402 DOI: 10.1016/j.str.2016.11.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 10/11/2016] [Accepted: 11/07/2016] [Indexed: 01/07/2023]
Abstract
Synaptic specificity is a defining property of neural networks. In the cerebellum, synapses between parallel fiber neurons and Purkinje cells are specified by the simultaneous interactions of secreted protein cerebellin with pre-synaptic neurexin and post-synaptic delta-type glutamate receptors (GluD). Here, we determined the crystal structures of the trimeric C1q-like domain of rat cerebellin-1, and the first complete ectodomain of a GluD, rat GluD2. Cerebellin binds to the LNS6 domain of α- and β-neurexin-1 through a high-affinity interaction that involves its highly flexible N-terminal domain. In contrast, we show that the interaction of cerebellin with isolated GluD2 ectodomain is low affinity, which is not simply an outcome of lost avidity when compared with binding with a tetrameric full-length receptor. Rather, high-affinity capture of cerebellin by post-synaptic terminals is likely controlled by long-distance regulation within this transsynaptic complex. Altogether, our results suggest unusual conformational flexibility within all components of the complex.
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Affiliation(s)
- Shouqiang Cheng
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Alpay B Seven
- Department of Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jing Wang
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Georgios Skiniotis
- Department of Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA.
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32
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Pronker MF, Lemstra S, Snijder J, Heck AJR, Thies-Weesie DME, Pasterkamp RJ, Janssen BJC. Structural basis of myelin-associated glycoprotein adhesion and signalling. Nat Commun 2016; 7:13584. [PMID: 27922006 PMCID: PMC5150538 DOI: 10.1038/ncomms13584] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/17/2016] [Indexed: 01/06/2023] Open
Abstract
Myelin-associated glycoprotein (MAG) is a myelin-expressed cell-adhesion and bi-directional signalling molecule. MAG maintains the myelin–axon spacing by interacting with specific neuronal glycolipids (gangliosides), inhibits axon regeneration and controls myelin formation. The mechanisms underlying MAG adhesion and signalling are unresolved. We present crystal structures of the MAG full ectodomain, which reveal an extended conformation of five Ig domains and a homodimeric arrangement involving membrane-proximal domains Ig4 and Ig5. MAG-oligosaccharide complex structures and biophysical assays show how MAG engages axonal gangliosides at domain Ig1. Two post-translational modifications were identified—N-linked glycosylation at the dimerization interface and tryptophan C-mannosylation proximal to the ganglioside binding site—that appear to have regulatory functions. Structure-guided mutations and neurite outgrowth assays demonstrate MAG dimerization and carbohydrate recognition are essential for its regeneration-inhibiting properties. The combination of trans ganglioside binding and cis homodimerization explains how MAG maintains the myelin–axon spacing and provides a mechanism for MAG-mediated bi-directional signalling. Myelin-associated glycoprotein (MAG) maintains myelin-axon spacing. Here, the authors report the crystal structures of the MAG full ectodomain in complex with oligosaccharide, and use additional assays to provide insights into the mechanism of MAG-mediated signalling.
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Affiliation(s)
- Matti F Pronker
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Suzanne Lemstra
- Department for Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Joost Snijder
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Department of Chemistry and Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Department of Chemistry and Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Dominique M E Thies-Weesie
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute of Nanomaterials Science, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - R Jeroen Pasterkamp
- Department for Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Bert J C Janssen
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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33
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Schejter ED. Myoblast fusion: Experimental systems and cellular mechanisms. Semin Cell Dev Biol 2016; 60:112-120. [DOI: 10.1016/j.semcdb.2016.07.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/11/2016] [Accepted: 07/12/2016] [Indexed: 12/18/2022]
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34
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Ettensohn CA, Dey D. KirrelL, a member of the Ig-domain superfamily of adhesion proteins, is essential for fusion of primary mesenchyme cells in the sea urchin embryo. Dev Biol 2016; 421:258-270. [PMID: 27866905 DOI: 10.1016/j.ydbio.2016.11.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 11/01/2016] [Accepted: 11/01/2016] [Indexed: 11/25/2022]
Abstract
In the sea urchin embryo, primary mesenchyme cells (PMCs) adhere to one another and fuse via filopodia, forming cable-like structures within which skeletal rods are deposited. Although this process was first described more than a century ago, molecules that participate in PMC adhesion and fusion have not been identified. Here we show that KirrelL, a PMC-specific, Ig domain-containing transmembrane protein, is essential for PMC fusion, probably by mediating filopodial adhesions that are a pre-requisite for subsequent membrane fusion. We show that KirrelL is not required for PMC specification, migration, or for direct filopodial contacts between PMCs. In the absence of KirrelL, however, filopodial contacts do not result in fusion. kirrelL is a member of a family of closely related, intronless genes that likely arose through an echinoid-specific gene expansion, possibly via retrotransposition. Our findings are significant in that they establish a direct linkage between the transcriptional network deployed in the PMC lineage and an effector molecule required for a critically important PMC morphogenetic process. In addition, our results point to a conserved role for Ig domain-containing adhesion proteins in facilitating cell fusion in both muscle and non-muscle cell lineages during animal development.
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Affiliation(s)
- Charles A Ettensohn
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, United States.
| | - Debleena Dey
- Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, United States
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35
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Role and organization of the actin cytoskeleton during cell-cell fusion. Semin Cell Dev Biol 2016; 60:121-126. [PMID: 27476112 DOI: 10.1016/j.semcdb.2016.07.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 11/23/2022]
Abstract
Cell-cell fusion is a ubiquitous process that underlies fertilization and development of eukaryotes. This process requires fusogenic machineries to promote plasma membrane merging, and also relies on the organization of dedicated sub-cortical cytoskeletal assemblies. This review describes the role of actin structures, so called actin fusion foci, essential for the fusion of two distinct cell types: Drosophila myoblast cells, which fuse to form myotubes, and sexually differentiated cells of the fission yeast Schizosaccharomyces pombe, which fuse to form a zygote. I describe the respective composition and organization of the two structures, discuss their proposed role in promoting plasma membrane apposition, and consider the universality of similar structures for cell-cell fusion.
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36
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Grahammer F, Wigge C, Schell C, Kretz O, Patrakka J, Schneider S, Klose M, Kind J, Arnold SJ, Habermann A, Bräuniger R, Rinschen MM, Völker L, Bregenzer A, Rubbenstroth D, Boerries M, Kerjaschki D, Miner JH, Walz G, Benzing T, Fornoni A, Frangakis AS, Huber TB. A flexible, multilayered protein scaffold maintains the slit in between glomerular podocytes. JCI Insight 2016; 1:86177. [PMID: 27430022 DOI: 10.1172/jci.insight.86177] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Vertebrate life critically depends on renal filtration and excretion of low molecular weight waste products. This process is controlled by a specialized cell-cell contact between podocyte foot processes: the slit diaphragm (SD). Using a comprehensive set of targeted KO mice of key SD molecules, we provided genetic, functional, and high-resolution ultrastructural data highlighting a concept of a flexible, dynamic, and multilayered architecture of the SD. Our data indicate that the mammalian SD is composed of NEPHRIN and NEPH1 molecules, while NEPH2 and NEPH3 do not participate in podocyte intercellular junction formation. Unexpectedly, homo- and heteromeric NEPHRIN/NEPH1 complexes are rarely observed. Instead, single NEPH1 molecules appear to form the lower part of the junction close to the glomerular basement membrane with a width of 23 nm, while single NEPHRIN molecules form an adjacent junction more apically with a width of 45 nm. In both cases, the molecules are quasiperiodically spaced 7 nm apart. These structural findings, in combination with the flexibility inherent to the repetitive Ig folds of NEPHRIN and NEPH1, indicate that the SD likely represents a highly dynamic cell-cell contact that forms an adjustable, nonclogging barrier within the renal filtration apparatus.
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Affiliation(s)
- Florian Grahammer
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christoph Wigge
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Christoph Schell
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine.,Faculty of Biology, and
| | - Oliver Kretz
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,Institute of Anatomy, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jaakko Patrakka
- KI/AZ Integrated Cardio-Metabolic Center (ICMC), Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Simon Schneider
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Martin Klose
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium and.,German Cancer Research Center, Heidelberg, Germany
| | - Julia Kind
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian J Arnold
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anja Habermann
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Ricarda Bräuniger
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Markus M Rinschen
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Linus Völker
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Andreas Bregenzer
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Dennis Rubbenstroth
- Institute of Virology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Melanie Boerries
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium and.,German Cancer Research Center, Heidelberg, Germany
| | | | - Jeffrey H Miner
- Renal Division, Washington University, St. Louis, Missouri, USA
| | - Gerd Walz
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Alessia Fornoni
- Division of Nephrology and Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Achilleas S Frangakis
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Tobias B Huber
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,FRIAS, Freiburg Institute for Advanced Studies and ZBSA, Center for Biological System Analysis, Albert-Ludwigs-University of Freiburg, Germany
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37
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Abstract
Desmosomes are intercellular adhesive junctions that impart strength to vertebrate tissues. Their dense, ordered intercellular attachments are formed by desmogleins (Dsgs) and desmocollins (Dscs), but the nature of trans-cellular interactions between these specialized cadherins is unclear. Here, using solution biophysics and coated-bead aggregation experiments, we demonstrate family-wise heterophilic specificity: All Dsgs form adhesive dimers with all Dscs, with affinities characteristic of each Dsg:Dsc pair. Crystal structures of ectodomains from Dsg2 and Dsg3 and from Dsc1 and Dsc2 show binding through a strand-swap mechanism similar to that of homophilic classical cadherins. However, conserved charged amino acids inhibit Dsg:Dsg and Dsc:Dsc interactions by same-charge repulsion and promote heterophilic Dsg:Dsc interactions through opposite-charge attraction. These findings show that Dsg:Dsc heterodimers represent the fundamental adhesive unit of desmosomes and provide a structural framework for understanding desmosome assembly.
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38
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Carrillo RA, Özkan E, Menon KP, Nagarkar-Jaiswal S, Lee PT, Jeon M, Birnbaum ME, Bellen HJ, Garcia KC, Zinn K. Control of Synaptic Connectivity by a Network of Drosophila IgSF Cell Surface Proteins. Cell 2016; 163:1770-1782. [PMID: 26687361 DOI: 10.1016/j.cell.2015.11.022] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 09/27/2015] [Accepted: 11/10/2015] [Indexed: 12/16/2022]
Abstract
We have defined a network of interacting Drosophila cell surface proteins in which a 21-member IgSF subfamily, the Dprs, binds to a nine-member subfamily, the DIPs. The structural basis of the Dpr-DIP interaction code appears to be dictated by shape complementarity within the Dpr-DIP binding interface. Each of the six dpr and DIP genes examined here is expressed by a unique subset of larval and pupal neurons. In the neuromuscular system, interactions between Dpr11 and DIP-γ affect presynaptic terminal development, trophic factor responses, and neurotransmission. In the visual system, dpr11 is selectively expressed by R7 photoreceptors that use Rh4 opsin (yR7s). Their primary synaptic targets, Dm8 amacrine neurons, express DIP-γ. In dpr11 or DIP-γ mutants, yR7 terminals extend beyond their normal termination zones in layer M6 of the medulla. DIP-γ is also required for Dm8 survival or differentiation. Our findings suggest that Dpr-DIP interactions are important determinants of synaptic connectivity.
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Affiliation(s)
- Robert A Carrillo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Engin Özkan
- Dept. of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL.,Howard Hughes Medical Institute, Depts. of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA
| | - Kaushiki P Menon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Sonal Nagarkar-Jaiswal
- Howard Hughes Medical Institute, Program in Developmental Biology, Dept. of Molecular and Human Genetics, Jan and Dan Duncan Neurological Research Institute at TCH, Baylor College of Medicine, Houston, TX
| | - Pei-Tseng Lee
- Howard Hughes Medical Institute, Program in Developmental Biology, Dept. of Molecular and Human Genetics, Jan and Dan Duncan Neurological Research Institute at TCH, Baylor College of Medicine, Houston, TX
| | - Mili Jeon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA.,Howard Hughes Medical Institute, Depts. of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA
| | - Michael E Birnbaum
- Howard Hughes Medical Institute, Depts. of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA
| | - Hugo J Bellen
- Howard Hughes Medical Institute, Program in Developmental Biology, Dept. of Molecular and Human Genetics, Jan and Dan Duncan Neurological Research Institute at TCH, Baylor College of Medicine, Houston, TX
| | - K Christopher Garcia
- Howard Hughes Medical Institute, Depts. of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA
| | - Kai Zinn
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
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39
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Dhanyasi N, Segal D, Shimoni E, Shinder V, Shilo BZ, VijayRaghavan K, Schejter ED. Surface apposition and multiple cell contacts promote myoblast fusion in Drosophila flight muscles. J Cell Biol 2016; 211:191-203. [PMID: 26459604 PMCID: PMC4602036 DOI: 10.1083/jcb.201503005] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transmission EM methods reveal that cell–cell fusion of individual myoblasts with growing Drosophila flight muscles is a stepwise process in which the cell adhesion and branched actin machineries mediate tight apposition and formation of multiple contacts and pores between the surfaces of the fusing cells. Fusion of individual myoblasts to form multinucleated myofibers constitutes a widely conserved program for growth of the somatic musculature. We have used electron microscopy methods to study this key form of cell–cell fusion during development of the indirect flight muscles (IFMs) of Drosophila melanogaster. We find that IFM myoblast–myotube fusion proceeds in a stepwise fashion and is governed by apparent cross talk between transmembrane and cytoskeletal elements. Our analysis suggests that cell adhesion is necessary for bringing myoblasts to within a minimal distance from the myotubes. The branched actin polymerization machinery acts subsequently to promote tight apposition between the surfaces of the two cell types and formation of multiple sites of cell–cell contact, giving rise to nascent fusion pores whose expansion establishes full cytoplasmic continuity. Given the conserved features of IFM myogenesis, this sequence of cell interactions and membrane events and the mechanistic significance of cell adhesion elements and the actin-based cytoskeleton are likely to represent general principles of the myoblast fusion process.
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Affiliation(s)
- Nagaraju Dhanyasi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India Manipal University, Manipal, Karnataka 576104, India
| | - Dagan Segal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Vera Shinder
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - K VijayRaghavan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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40
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Kevenaar JT, Hoogenraad CC. The axonal cytoskeleton: from organization to function. Front Mol Neurosci 2015; 8:44. [PMID: 26321907 PMCID: PMC4536388 DOI: 10.3389/fnmol.2015.00044] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 07/31/2015] [Indexed: 01/20/2023] Open
Abstract
The axon is the single long fiber that extends from the neuron and transmits electrical signals away from the cell body. The neuronal cytoskeleton, composed of microtubules (MTs), actin filaments and neurofilaments, is not only required for axon formation and axonal transport but also provides the structural basis for several specialized axonal structures, such as the axon initial segment (AIS) and presynaptic boutons. Emerging evidence suggest that the unique cytoskeleton organization in the axon is essential for its structure and integrity. In addition, the increasing number of neurodevelopmental and neurodegenerative diseases linked to defect in actin- and microtubule-dependent processes emphasizes the importance of a properly regulated cytoskeleton for normal axonal functioning. Here, we provide an overview of the current understanding of actin and microtubule organization within the axon and discuss models for the functional role of the cytoskeleton at specialized axonal structures.
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Affiliation(s)
- Josta T. Kevenaar
- Cell Biology, Faculty of Science, Utrecht UniversityUtrecht, Netherlands
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41
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Maro GS, Gao S, Olechwier AM, Hung WL, Liu M, Özkan E, Zhen M, Shen K. MADD-4/Punctin and Neurexin Organize C. elegans GABAergic Postsynapses through Neuroligin. Neuron 2015; 86:1420-32. [PMID: 26028574 DOI: 10.1016/j.neuron.2015.05.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 04/07/2015] [Accepted: 05/01/2015] [Indexed: 11/29/2022]
Abstract
At synapses, the presynaptic release machinery is precisely juxtaposed to the postsynaptic neurotransmitter receptors. We studied the molecular mechanisms underlying this exquisite alignment at the C. elegans inhibitory synapses. We found that the sole C. elegans neuroligin homolog, NLG-1, localizes specifically at GABAergic postsynapses and is required for clustering the GABA(A) receptor UNC-49. Two presynaptic factors, Punctin/MADD-4, an ADAMTS-like extracellular protein, and neurexin/NRX-1, act partially redundantly to recruit NLG-1 to synapses. In the absence of both MADD-4 and NRX-1, NLG-1 and GABA(A) receptors fail to cluster, and GABAergic synaptic transmission is severely compromised. Biochemically, we detect an interaction between MADD-4 and NLG-1, as well as between MADD-4 and NRX-1. Interestingly, the presence of NRX-1 potentiates binding between Punctin/MADD-4 and NLG-1, suggestive of a tripartite receptor ligand complex. We propose that presynaptic terminals induce postsynaptic receptor clustering through the action of both secreted ECM proteins and trans-synaptic adhesion complexes.
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Affiliation(s)
- Géraldine S Maro
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Shangbang Gao
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G1X5, Canada
| | - Agnieszka M Olechwier
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Wesley L Hung
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G1X5, Canada
| | - Michael Liu
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G1X5, Canada.
| | - Kang Shen
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA.
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42
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Kim JH, Jin P, Duan R, Chen EH. Mechanisms of myoblast fusion during muscle development. Curr Opin Genet Dev 2015; 32:162-70. [PMID: 25989064 DOI: 10.1016/j.gde.2015.03.006] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/13/2015] [Accepted: 03/17/2015] [Indexed: 01/24/2023]
Abstract
The development and regeneration of skeletal muscle require the fusion of mononucleated muscle cells to form multinucleated, contractile muscle fibers. Studies using a simple genetic model, Drosophila melanogaster, have discovered many evolutionarily conserved fusion-promoting factors in vivo. Recent work in zebrafish and mouse also identified several vertebrate-specific factors required for myoblast fusion. Here, we integrate progress in multiple in vivo systems and highlight conceptual advance in understanding how muscle cell membranes are brought together for fusion. We focus on the molecular machinery at the fusogenic synapse and present a three-step model to describe the molecular and cellular events leading to fusion pore formation.
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Affiliation(s)
- Ji Hoon Kim
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Peng Jin
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Rui Duan
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Elizabeth H Chen
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States.
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Grahammer F, Benzing T, Huber TB. New insights into mechanisms of glomerular injury and repair from the 10th International Podocyte Conference 2014. Kidney Int 2015; 87:885-93. [DOI: 10.1038/ki.2015.5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 11/11/2014] [Accepted: 11/20/2014] [Indexed: 01/17/2023]
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Kim JH, Ren Y, Ng WP, Li S, Son S, Kee YS, Zhang S, Zhang G, Fletcher DA, Robinson DN, Chen EH. Mechanical tension drives cell membrane fusion. Dev Cell 2015; 32:561-73. [PMID: 25684354 DOI: 10.1016/j.devcel.2015.01.005] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 11/14/2014] [Accepted: 01/10/2015] [Indexed: 01/05/2023]
Abstract
Membrane fusion is an energy-consuming process that requires tight juxtaposition of two lipid bilayers. Little is known about how cells overcome energy barriers to bring their membranes together for fusion. Previously, we have shown that cell-cell fusion is an asymmetric process in which an "attacking" cell drills finger-like protrusions into the "receiving" cell to promote cell fusion. Here, we show that the receiving cell mounts a Myosin II (MyoII)-mediated mechanosensory response to its invasive fusion partner. MyoII acts as a mechanosensor, which directs its force-induced recruitment to the fusion site, and the mechanosensory response of MyoII is amplified by chemical signaling initiated by cell adhesion molecules. The accumulated MyoII, in turn, increases cortical tension and promotes fusion pore formation. We propose that the protrusive and resisting forces from fusion partners put the fusogenic synapse under high mechanical tension, which helps to overcome energy barriers for membrane apposition and drives cell membrane fusion.
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Affiliation(s)
- Ji Hoon Kim
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yixin Ren
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Win Pin Ng
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Shuo Li
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sungmin Son
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Yee-Seir Kee
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Shiliang Zhang
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Guofeng Zhang
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, MD 20892, USA
| | - Daniel A Fletcher
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Douglas N Robinson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Elizabeth H Chen
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Coles CH, Jones EY, Aricescu AR. Extracellular regulation of type IIa receptor protein tyrosine phosphatases: mechanistic insights from structural analyses. Semin Cell Dev Biol 2015; 37:98-107. [PMID: 25234613 PMCID: PMC4765084 DOI: 10.1016/j.semcdb.2014.09.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 09/02/2014] [Accepted: 09/05/2014] [Indexed: 01/06/2023]
Abstract
The receptor protein tyrosine phosphatases (RPTPs) exhibit a wide repertoire of cellular signalling functions. In particular, type IIa RPTP family members have recently been highlighted as hubs for extracellular interactions in neurons, regulating neuronal extension and guidance, as well as synaptic organisation. In this review, we will discuss the recent progress of structural biology investigations into the architecture of type IIa RPTP ectodomains and their interactions with extracellular ligands. Structural insights, in combination with biophysical and cellular studies, allow us to begin to piece together molecular mechanisms for the transduction and integration of type IIa RPTP signals and to propose hypotheses for future experimental validation.
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Affiliation(s)
- Charlotte H Coles
- Laboratory for Axon Growth and Regeneration, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
| | - A Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
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46
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Cherra SJ, Jin Y. Advances in synapse formation: forging connections in the worm. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2014; 4:85-97. [PMID: 25472860 DOI: 10.1002/wdev.165] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Revised: 10/09/2014] [Accepted: 10/24/2014] [Indexed: 12/27/2022]
Abstract
UNLABELLED Synapse formation is the quintessential process by which neurons form specific connections with their targets to enable the development of functional circuits. Over the past few decades, intense research efforts have identified thousands of proteins that localize to the pre- and postsynaptic compartments. Genetic dissection has provided important insights into the nexus of the molecular and cellular network, and has greatly advanced our knowledge about how synapses form and function physiologically. Moreover, recent studies have highlighted the complex regulation of synapse formation with the identification of novel mechanisms involving cell interactions from non-neuronal sources. In this review, we cover the conserved pathways required for synaptogenesis and place specific focus on new themes of synapse modulation arising from studies in Caenorhabditis elegans. For further resources related to this article, please visit the WIREs website. CONFLICT OF INTEREST The authors have declared no conflicts of interest for this article.
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Affiliation(s)
- Salvatore J Cherra
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
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Abstract
Synapses are specialized asymmetric cell-cell connections permitting the controlled transfer of an electrical or chemical signal between a presynaptic neuronal cell and a postsynaptic target cell (e.g. neuron or muscle). Adequate synapse function is an essential prerequisite of all neuronal processing, including higher cognitive functions, such as learning and memory. At synapses, neurotransmitters (e.g. amino acids, amines, peptides, and acetylcholine) are released from synaptic vesicles into the synaptic cleft in response to action potentials. The Nobel Prize for Physiology and Medicine in 2013 was awarded to James E. Rothman, Randy W. Schekman and Thomas C. Südhof "for their discoveries of the machinery regulating vesicle traffic, a major transport system in our cells". This included crucial revelations, such as the identification of the core machinery of synaptic vesicle fusion. However, in contrast to the advances concerning the organization of the core functions of the synapse, our current understanding of the processes of synapse formation and maintenance--i.e. 'synaptogenesis'--is still somewhat fragmentary. Here, we will outline the current status and future directions of the field of synaptogenesis, primarily from the perspective of the presynaptic release site.
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Affiliation(s)
- Astrid G Petzoldt
- Neurogenetik, Institut für Biologie, Freie Universität Berlin, 14195 Berlin, Germany; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Stephan J Sigrist
- Neurogenetik, Institut für Biologie, Freie Universität Berlin, 14195 Berlin, Germany; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany.
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Coles CH, Mitakidis N, Zhang P, Elegheert J, Lu W, Stoker AW, Nakagawa T, Craig AM, Jones EY, Aricescu AR. Structural basis for extracellular cis and trans RPTPσ signal competition in synaptogenesis. Nat Commun 2014; 5:5209. [PMID: 25385546 PMCID: PMC4239663 DOI: 10.1038/ncomms6209] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 09/09/2014] [Indexed: 01/26/2023] Open
Abstract
Receptor protein tyrosine phosphatase sigma (RPTPσ) regulates neuronal extension and acts as a presynaptic nexus for multiple protein and proteoglycan interactions during synaptogenesis. Unknown mechanisms govern the shift in RPTPσ function, from outgrowth promotion to synaptic organization. Here, we report crystallographic, electron microscopic and small-angle X-ray scattering analyses, which reveal sufficient inter-domain flexibility in the RPTPσ extracellular region for interaction with both cis (same cell) and trans (opposite cell) ligands. Crystal structures of RPTPσ bound to its postsynaptic ligand TrkC detail an interaction surface partially overlapping the glycosaminoglycan-binding site. Accordingly, heparan sulphate and heparin oligomers compete with TrkC for RPTPσ binding in vitro and disrupt TrkC-dependent synaptic differentiation in neuronal co-culture assays. We propose that transient RPTPσ ectodomain emergence from the presynaptic proteoglycan layer allows capture by TrkC to form a trans-synaptic complex, the consequent reduction in RPTPσ flexibility potentiating interactions with additional ligands to orchestrate excitatory synapse formation.
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Affiliation(s)
- Charlotte H. Coles
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Nikolaos Mitakidis
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Peng Zhang
- Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5
| | - Jonathan Elegheert
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Weixian Lu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Andrew W. Stoker
- Cancer Section, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, 702 Light Hall (0615), Nashville, Tennessee 37232-0615, USA
| | - Ann Marie Craig
- Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B5
| | - E. Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - A. Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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Lennon R, Randles MJ, Humphries MJ. The importance of podocyte adhesion for a healthy glomerulus. Front Endocrinol (Lausanne) 2014; 5:160. [PMID: 25352829 PMCID: PMC4196579 DOI: 10.3389/fendo.2014.00160] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/21/2014] [Indexed: 12/23/2022] Open
Abstract
Podocytes are specialized epithelial cells that cover the outer surfaces of glomerular capillaries. Unique cell junctions, known as slit diaphragms, which feature nephrin and Neph family proteins in addition to components of adherens, tight, and gap junctions, connect adjacent podocyte foot processes. Single gene disorders affecting the slit diaphragm result in nephrotic syndrome in humans, characterized by massive loss of protein across the capillary wall. In addition to specialized cell junctions, interconnecting podocytes also adhere to the glomerular basement membrane (GBM) of the capillary wall. The GBM is a dense network of secreted, extracellular matrix (ECM) components and contains tissue-restricted isoforms of collagen IV and laminin in addition to other structural proteins and ECM regulators such as proteases and growth factors. The specialized niche of the GBM provides a scaffold for endothelial cells and podocytes to support their unique functions and human genetic mutations in GBM components lead to renal failure, thus highlighting the importance of cell-matrix interactions in the glomerulus. Cells adhere to ECM via adhesion receptors, including integrins, syndecans, and dystroglycan and in particular the integrin heterodimer α3β1 is required to maintain barrier integrity. Therefore, the sophisticated function of glomerular filtration relies on podocyte adhesion both at cell junctions and at the interface with the ECM. In health, the podocyte coordinates signals from cell junctions and cell-matrix interactions, in response to environmental cues in order to regulate filtration and as our understanding of mechanisms that control cell adhesion in the glomerulus develops, then insight into the effects of disease will improve. The ultimate goal will be to develop targeted therapies to prevent or repair defects in the filtration barrier and to restore glomerular function.
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Affiliation(s)
- Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
- Department of Paediatric Nephrology, Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK
- *Correspondence: Rachel Lennon, Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Michael Smith Building, Manchester M13 9PT, UK e-mail:
| | - Michael J. Randles
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
| | - Martin J. Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
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