101
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Park D, Lee U, Cho E, Zhao H, Kim JA, Lee BJ, Regan P, Ho WK, Cho K, Chang S. Impairment of Release Site Clearance within the Active Zone by Reduced SCAMP5 Expression Causes Short-Term Depression of Synaptic Release. Cell Rep 2018; 22:3339-3350. [DOI: 10.1016/j.celrep.2018.02.088] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 01/19/2018] [Accepted: 02/22/2018] [Indexed: 10/17/2022] Open
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102
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Gorvin CM, Rogers A, Hastoy B, Tarasov AI, Frost M, Sposini S, Inoue A, Whyte MP, Rorsman P, Hanyaloglu AC, Breitwieser GE, Thakker RV. AP2σ Mutations Impair Calcium-Sensing Receptor Trafficking and Signaling, and Show an Endosomal Pathway to Spatially Direct G-Protein Selectivity. Cell Rep 2018; 22:1054-1066. [PMID: 29420171 PMCID: PMC5792449 DOI: 10.1016/j.celrep.2017.12.089] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 11/30/2017] [Accepted: 12/22/2017] [Indexed: 12/29/2022] Open
Abstract
Spatial control of G-protein-coupled receptor (GPCR) signaling, which is used by cells to translate complex information into distinct downstream responses, is achieved by using plasma membrane (PM) and endocytic-derived signaling pathways. The roles of the endomembrane in regulating such pleiotropic signaling via multiple G-protein pathways remain unknown. Here, we investigated the effects of disease-causing mutations of the adaptor protein-2 σ subunit (AP2σ) on signaling by the class C GPCR calcium-sensing receptor (CaSR). These AP2σ mutations increase CaSR PM expression yet paradoxically reduce CaSR signaling. Hypercalcemia-associated AP2σ mutations reduced CaSR signaling via Gαq/11 and Gαi/o pathways. The mutations also delayed CaSR internalization due to prolonged residency time of CaSR in clathrin structures that impaired or abolished endosomal signaling, which was predominantly mediated by Gαq/11. Thus, compartmental bias for CaSR-mediated Gαq/11 endomembrane signaling provides a mechanistic basis for multidimensional GPCR signaling. Disease-causing AP2σ mutants impair Gαq/11 and Gαi/o signaling by CaSR, a class C GPCR AP2σ mutants impair trafficking of the CaSR The CaSR can signal by a sustained endosomal pathway CaSR differentially uses Gαq/11 and Gαi/o for cell-surface and endosomal signaling
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Affiliation(s)
- Caroline M Gorvin
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham, UK
| | - Angela Rogers
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Benoit Hastoy
- Diabetes Research Laboratory, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Andrei I Tarasov
- Diabetes Research Laboratory, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Morten Frost
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Silvia Sposini
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, London, UK
| | - Asuka Inoue
- Laboratory of Molecular and Cellular Biochemistry, Tohoku University, Sendai, Japan; Japan Science and Technology (JST) Agency, Precursory Research for Embryonic Science and Technology (PRESTO), Kawaguchi, Japan
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO, USA
| | - Patrik Rorsman
- Diabetes Research Laboratory, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Aylin C Hanyaloglu
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, London, UK
| | - Gerda E Breitwieser
- Geisinger Clinic, Weis Center for Research, Department of Functional and Molecular Genomics, Danville, PA, USA
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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103
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Abstract
In eukaryotes, distinct transport vesicles functionally connect various intracellular compartments. These carriers mediate transport of membranes for the biogenesis and maintenance of organelles, secretion of cargo proteins and peptides, and uptake of cargo into the cell. Transport vesicles have distinct protein coats that assemble on a donor membrane where they can select cargo and curve the membrane to form a bud. A multitude of structural elements of coat proteins have been solved by X-ray crystallography. More recently, the architectures of the COPI and COPII coats were elucidated in context with their membrane by cryo-electron tomography. Here, we describe insights gained from the structures of these two coat lattices and discuss the resulting functional implications.
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Affiliation(s)
- Julien Béthune
- Heidelberg University Biochemistry Centre, 69120 Heidelberg, Germany; ,
| | - Felix T Wieland
- Heidelberg University Biochemistry Centre, 69120 Heidelberg, Germany; ,
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104
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Beacham GM, Partlow EA, Lange JJ, Hollopeter G. NECAPs are negative regulators of the AP2 clathrin adaptor complex. eLife 2018; 7:32242. [PMID: 29345618 PMCID: PMC5785209 DOI: 10.7554/elife.32242] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 01/17/2018] [Indexed: 12/27/2022] Open
Abstract
Eukaryotic cells internalize transmembrane receptors via clathrin-mediated endocytosis, but it remains unclear how the machinery underpinning this process is regulated. We recently discovered that membrane-associated muniscin proteins such as FCHo and SGIP initiate endocytosis by converting the AP2 clathrin adaptor complex to an open, active conformation that is then phosphorylated (Hollopeter et al., 2014). Here we report that loss of ncap-1, the sole C. elegans gene encoding an adaptiN Ear-binding Coat-Associated Protein (NECAP), bypasses the requirement for FCHO-1. Biochemical analyses reveal AP2 accumulates in an open, phosphorylated state in ncap-1 mutant worms, suggesting NECAPs promote the closed, inactive conformation of AP2. Consistent with this model, NECAPs preferentially bind open and phosphorylated forms of AP2 in vitro and localize with constitutively open AP2 mutants in vivo. NECAPs do not associate with phosphorylation-defective AP2 mutants, implying that phosphorylation precedes NECAP recruitment. We propose NECAPs function late in endocytosis to inactivate AP2.
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Affiliation(s)
| | - Edward A Partlow
- Department of Molecular Medicine, Cornell University, Ithaca, United States
| | - Jeffrey J Lange
- Stowers Institute for Medical Research, Kansas City, United States
| | - Gunther Hollopeter
- Department of Molecular Medicine, Cornell University, Ithaca, United States
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105
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Mori Y, Takamori S. Molecular Signatures Underlying Synaptic Vesicle Cargo Retrieval. Front Cell Neurosci 2018; 11:422. [PMID: 29379416 PMCID: PMC5770824 DOI: 10.3389/fncel.2017.00422] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 12/15/2017] [Indexed: 12/31/2022] Open
Abstract
Efficient retrieval of the synaptic vesicle (SV) membrane from the presynaptic plasma membrane, a process called endocytosis, is crucial for the fidelity of neurotransmission, particularly during sustained neural activity. Although multiple modes of endocytosis have been identified, it is clear that the efficient retrieval of the major SV cargos into newly formed SVs during any of these modes is fundamental for synaptic transmission. It is currently believed that SVs are eventually reformed via a clathrin-dependent pathway. Various adaptor proteins recognize SV cargos and link them to clathrin, ensuring the efficient retrieval of the cargos into newly formed SVs. Here, we summarize our current knowledge of the molecular signatures within individual SV cargos that underlie efficient retrieval into SV membranes, as well as discuss possible contributions of the mechanisms under physiological conditions.
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Affiliation(s)
- Yasunori Mori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
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106
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Wood LA, Larocque G, Clarke NI, Sarkar S, Royle SJ. New tools for "hot-wiring" clathrin-mediated endocytosis with temporal and spatial precision. J Cell Biol 2017; 216:4351-4365. [PMID: 28954824 PMCID: PMC5716275 DOI: 10.1083/jcb.201702188] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 07/26/2017] [Accepted: 08/25/2017] [Indexed: 12/16/2022] Open
Abstract
Clathrin-mediated endocytosis (CME) is the major route of receptor internalization at the plasma membrane. Analysis of constitutive CME is difficult because the initiation of endocytic events is unpredictable. When and where a clathrin-coated pit will form and what cargo it will contain are difficult to foresee. Here we describe a series of genetically encoded reporters that allow the initiation of CME on demand. A clathrin-binding protein fragment ("hook") is inducibly attached to an "anchor" protein at the plasma membrane, which triggers the formation of new clathrin-coated vesicles. Our design incorporates temporal and spatial control by the use of chemical and optogenetic methods for inducing hook-anchor attachment. Moreover, the cargo is defined. Because several steps in vesicle creation are bypassed, we term it "hot-wiring." We use hot-wired endocytosis to describe the functional interactions between clathrin and AP2. Two distinct sites on the β2 subunit, one on the hinge and the other on the appendage, are necessary and sufficient for functional clathrin engagement.
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Affiliation(s)
- Laura A Wood
- Centre for Mechanochemical Cell Biology, Warwick Medical School, University of Warwick, Coventry, England, UK
| | - Gabrielle Larocque
- Centre for Mechanochemical Cell Biology, Warwick Medical School, University of Warwick, Coventry, England, UK
| | - Nicholas I Clarke
- Centre for Mechanochemical Cell Biology, Warwick Medical School, University of Warwick, Coventry, England, UK
| | - Sourav Sarkar
- Centre for Mechanochemical Cell Biology, Warwick Medical School, University of Warwick, Coventry, England, UK
| | - Stephen J Royle
- Centre for Mechanochemical Cell Biology, Warwick Medical School, University of Warwick, Coventry, England, UK
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107
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Smith SM, Baker M, Halebian M, Smith CJ. Weak Molecular Interactions in Clathrin-Mediated Endocytosis. Front Mol Biosci 2017; 4:72. [PMID: 29184887 PMCID: PMC5694535 DOI: 10.3389/fmolb.2017.00072] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 10/11/2017] [Indexed: 11/21/2022] Open
Abstract
Clathrin-mediated endocytosis is a process by which specific molecules are internalized from the cell periphery for delivery to early endosomes. The key stages in this step-wise process, from the starting point of cargo recognition, to the later stage of assembly of the clathrin coat, are dependent on weak interactions between a large network of proteins. This review discusses the structural and functional data that have improved our knowledge and understanding of the main weak molecular interactions implicated in clathrin-mediated endocytosis, with a particular focus on the two key proteins: AP2 and clathrin.
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Affiliation(s)
- Sarah M Smith
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Michael Baker
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Mary Halebian
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Corinne J Smith
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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108
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Takatsu H, Takayama M, Naito T, Takada N, Tsumagari K, Ishihama Y, Nakayama K, Shin HW. Phospholipid flippase ATP11C is endocytosed and downregulated following Ca 2+-mediated protein kinase C activation. Nat Commun 2017; 8:1423. [PMID: 29123098 PMCID: PMC5680300 DOI: 10.1038/s41467-017-01338-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 09/09/2017] [Indexed: 12/15/2022] Open
Abstract
We and others showed that ATP11A and ATP11C, members of the P4-ATPase family, translocate phosphatidylserine (PS) and phosphatidylethanolamine from the exoplasmic to the cytoplasmic leaflets at the plasma membrane. PS exposure on the outer leaflet of the plasma membrane in activated platelets, erythrocytes, and apoptotic cells was proposed to require the inhibition of PS-flippases, as well as activation of scramblases. Although ATP11A and ATP11C are cleaved by caspases in apoptotic cells, it remains unclear how PS-flippase activity is regulated in non-apoptotic cells. Here we report that the PS-flippase ATP11C, but not ATP11A, is sequestered from the plasma membrane via clathrin-mediated endocytosis upon Ca2+-mediated PKC activation. Importantly, we show that a characteristic di-leucine motif (SVRPLL) in the C-terminal cytoplasmic region of ATP11C becomes functional upon PKC activation. Moreover endocytosis of ATP11C is induced by Ca2+-signaling via Gq-coupled receptors. Our data provide the first evidence for signal-dependent regulation of mammalian P4-ATPase. ATP11C is a flippase that uses ATP hydrolysis to translocate phospholipids at the plasma membrane. Here, the authors show that the activation of Ca2+-dependent protein kinase C increases ATP11C endocytosis thus downregulating phospholipid translocation.
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Affiliation(s)
- Hiroyuki Takatsu
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Masahiro Takayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Tomoki Naito
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Naoto Takada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Kazuya Tsumagari
- Molecular and Cellular BioAnalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Yasushi Ishihama
- Molecular and Cellular BioAnalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Hye-Won Shin
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan.
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109
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Li H, Santos MS, Park CK, Dobry Y, Voglmaier SM. VGLUT2 Trafficking Is Differentially Regulated by Adaptor Proteins AP-1 and AP-3. Front Cell Neurosci 2017; 11:324. [PMID: 29123471 PMCID: PMC5662623 DOI: 10.3389/fncel.2017.00324] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 09/28/2017] [Indexed: 01/25/2023] Open
Abstract
Release of the major excitatory neurotransmitter glutamate by synaptic vesicle exocytosis depends on glutamate loading into synaptic vesicles by vesicular glutamate transporters (VGLUTs). The two principal isoforms, VGLUT1 and 2, exhibit a complementary pattern of expression in adult brain that broadly distinguishes cortical (VGLUT1) and subcortical (VGLUT2) systems, and correlates with distinct physiological properties in synapses expressing these isoforms. Differential trafficking of VGLUT1 and 2 has been suggested to underlie their functional diversity. Increasing evidence suggests individual synaptic vesicle proteins use specific sorting signals to engage specialized biochemical mechanisms to regulate their recycling. We observed that VGLUT2 recycles differently in response to high frequency stimulation than VGLUT1. Here we further explore the trafficking of VGLUT2 using a pHluorin-based reporter, VGLUT2-pH. VGLUT2-pH exhibits slower rates of both exocytosis and endocytosis than VGLUT1-pH. VGLUT2-pH recycling is slower than VGLUT1-pH in both hippocampal neurons, which endogenously express mostly VGLUT1, and thalamic neurons, which endogenously express mostly VGLUT2, indicating that protein identity, not synaptic vesicle membrane or neuronal cell type, controls sorting. We characterize sorting signals in the C-terminal dileucine-like motif, which plays a crucial role in VGLUT2 trafficking. Disruption of this motif abolishes synaptic targeting of VGLUT2 and essentially eliminates endocytosis of the transporter. Mutational and biochemical analysis demonstrates that clathrin adaptor proteins (APs) interact with VGLUT2 at the dileucine-like motif. VGLUT2 interacts with AP-2, a well-studied adaptor protein for clathrin mediated endocytosis. In addition, VGLUT2 also interacts with the alternate adaptors, AP-1 and AP-3. VGLUT2 relies on distinct recycling mechanisms from VGLUT1. Abrogation of these differences by pharmacological and molecular inhibition reveals that these mechanisms are dependent on the adaptor proteins AP-1 and AP-3. Further, shRNA-mediated knockdown reveals differential roles for AP-1 and AP-3 in VGLUT2 recycling.
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Affiliation(s)
- Haiyan Li
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
| | - Magda S Santos
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
| | - Chihyung K Park
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
| | - Yuriy Dobry
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
| | - Susan M Voglmaier
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
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110
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Gururaj S, Evely KM, Pryce KD, Li J, Qu J, Bhattacharjee A. Protein kinase A-induced internalization of Slack channels from the neuronal membrane occurs by adaptor protein-2/clathrin-mediated endocytosis. J Biol Chem 2017; 292:19304-19314. [PMID: 28982974 DOI: 10.1074/jbc.m117.804716] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 09/13/2017] [Indexed: 02/01/2023] Open
Abstract
The sodium-activated potassium (KNa) channel Kcnt1 (Slack) is abundantly expressed in nociceptor (pain-sensing) neurons of the dorsal root ganglion (DRG), where they transmit the large outward conductance IKNa and arbitrate membrane excitability. Slack channel expression at the DRG membrane is necessary for their characteristic firing accommodation during maintained stimulation, and reduced membrane channel density causes hyperexcitability. We have previously shown that in a pro-inflammatory state, a decrease in membrane channel expression leading to reduced Slack-mediated IKNa expression underlies DRG neuronal sensitization. An important component of the inflammatory milieu, PKA internalizes Slack channels from the DRG membrane, reduces IKNa, and produces DRG neuronal hyperexcitability when activated in cultured primary DRG neurons. Here, we show that this PKA-induced retrograde trafficking of Slack channels also occurs in intact spinal cord slices and that it is carried out by adaptor protein-2 (AP-2) via clathrin-mediated endocytosis. We provide mass spectrometric and biochemical evidence of an association of native neuronal AP-2 adaptor proteins with Slack channels, facilitated by a dileucine motif housed in the cytoplasmic Slack C terminus that binds AP-2. By creating a competitive peptide blocker of AP-2-Slack binding, we demonstrated that this interaction is essential for clathrin recruitment to the DRG membrane, Slack channel endocytosis, and DRG neuronal hyperexcitability after PKA activation. Together, these findings uncover AP-2 and clathrin as players in Slack channel regulation. Given the significant role of Slack in nociceptive neuronal excitability, the AP-2 clathrin-mediated endocytosis trafficking mechanism may enable targeting of peripheral and possibly, central neuronal sensitization.
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Affiliation(s)
| | - Katherine M Evely
- the Program for Neuroscience, University at Buffalo, State University of New York, Buffalo, New York 14214 and
| | - Kerri D Pryce
- From the Department of Pharmacology and Toxicology and
| | - Jun Li
- the New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, New York 14203
| | - Jun Qu
- the New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, New York 14203
| | - Arin Bhattacharjee
- From the Department of Pharmacology and Toxicology and .,the Program for Neuroscience, University at Buffalo, State University of New York, Buffalo, New York 14214 and
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111
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Archuleta TL, Frazier MN, Monken AE, Kendall AK, Harp J, McCoy AJ, Creanza N, Jackson LP. Structure and evolution of ENTH and VHS/ENTH-like domains in tepsin. Traffic 2017; 18:590-603. [PMID: 28691777 PMCID: PMC5567745 DOI: 10.1111/tra.12499] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 07/02/2017] [Accepted: 07/06/2017] [Indexed: 12/28/2022]
Abstract
Tepsin is currently the only accessory trafficking protein identified in adaptor-related protein 4 (AP4)-coated vesicles originating at the trans-Golgi network (TGN). The molecular basis for interactions between AP4 subunits and motifs in the tepsin C-terminus have been characterized, but the biological role of tepsin remains unknown. We determined X-ray crystal structures of the tepsin epsin N-terminal homology (ENTH) and VHS/ENTH-like domains. Our data reveal unexpected structural features that suggest key functional differences between these and similar domains in other trafficking proteins. The tepsin ENTH domain lacks helix0, helix8 and a lipid binding pocket found in epsin1/2/3. These results explain why tepsin requires AP4 for its membrane recruitment and further suggest ENTH domains cannot be defined solely as lipid binding modules. The VHS domain lacks helix8 and thus contains fewer helices than other VHS domains. Structural data explain biochemical and biophysical evidence that tepsin VHS does not mediate known VHS functions, including recognition of dileucine-based cargo motifs or ubiquitin. Structural comparisons indicate the domains are very similar to each other, and phylogenetic analysis reveals their evolutionary pattern within the domain superfamily. Phylogenetics and comparative genomics further show tepsin within a monophyletic clade that diverged away from epsins early in evolutionary history (~1500 million years ago). Together, these data provide the first detailed molecular view of tepsin and suggest tepsin structure and function diverged away from other epsins. More broadly, these data highlight the challenges inherent in classifying and understanding protein function based only on sequence and structure.
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Affiliation(s)
- Tara L. Archuleta
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Meredith N. Frazier
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Anderson E. Monken
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Amy K. Kendall
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Joel Harp
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
| | - Airlie J. McCoy
- Cambridge Institute for Medical Research, Department of Clinical
Biochemistry, University of Cambridge, Hills Road, Cambridge, United Kingdom
| | - Nicole Creanza
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
| | - Lauren P. Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville,
TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN,
USA
- Department of Biochemistry, Vanderbilt University, Nashville, TN,
USA
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112
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Apel AR, Hoban K, Chuartzman S, Tonikian R, Sidhu S, Schuldiner M, Wendland B, Prosser D. Syp1 regulates the clathrin-mediated and clathrin-independent endocytosis of multiple cargo proteins through a novel sorting motif. Mol Biol Cell 2017; 28:2434-2448. [PMID: 28701344 PMCID: PMC5576906 DOI: 10.1091/mbc.e15-10-0731] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 06/21/2017] [Accepted: 06/27/2017] [Indexed: 12/14/2022] Open
Abstract
Internalization of proteins from the plasma membrane (PM) allows for cell-surface composition regulation, signaling of network modulation, and nutrient uptake. Clathrin-mediated endocytosis (CME) is a major internalization route for PM proteins. During CME, endocytic adaptor proteins bind cargoes at the cell surface and link them to the PM and clathrin coat. Muniscins are a conserved family of endocytic adaptors, including Syp1 in budding yeast and its mammalian orthologue, FCHo1. These adaptors bind cargo via a C-terminal μ-homology domain (μHD); however, few cargoes exhibiting muniscin-dependent endocytosis have been identified, and the sorting sequence recognized by the µHD is unknown. To reveal Syp1 cargo-sorting motifs, we performed a phage display screen and used biochemical methods to demonstrate that the Syp1 µHD binds DxY motifs in the previously identified Syp1 cargo Mid2 and the v-SNARE Snc1. We also executed an unbiased visual screen, which identified the peptide transporter Ptr2 and the ammonium permease Mep3 as Syp1 cargoes containing DxY motifs. Finally, we determined that, in addition to regulating cargo entry through CME, Syp1 can promote internalization of Ptr2 through a recently identified clathrin-independent endocytic pathway that requires the Rho1 GTPase. These findings elucidate the mechanism of Syp1 cargo recognition and its role in trafficking.
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Affiliation(s)
| | - Kyle Hoban
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218
| | - Silvia Chuartzman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Raffi Tonikian
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Sachdev Sidhu
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Beverly Wendland
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218
| | - Derek Prosser
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218
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113
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Two Clathrin Adaptor Protein Complexes Instruct Axon-Dendrite Polarity. Neuron 2017; 90:564-80. [PMID: 27151641 DOI: 10.1016/j.neuron.2016.04.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 03/03/2016] [Accepted: 04/12/2016] [Indexed: 11/23/2022]
Abstract
The cardinal feature of neuronal polarization is the establishment and maintenance of axons and dendrites. How axonal and dendritic proteins are sorted and targeted to different compartments is poorly understood. Here, we identified distinct dileucine motifs that are necessary and sufficient to target transmembrane proteins to either the axon or the dendrite through direct interactions with the clathrin-associated adaptor protein complexes (APs) in C. elegans. Axonal targeting requires AP-3, while dendritic targeting is mediated by AP-1. The axonal dileucine motif binds to AP-3 with higher efficiency than to AP-1. Both AP-3 and AP-1 are localized to the Golgi but occupy adjacent domains. We propose that AP-3 and AP-1 directly select transmembrane proteins and target them to axon and dendrite, respectively, by sorting them into distinct vesicle pools.
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114
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Salaun C, Ritchie L, Greaves J, Bushell TJ, Chamberlain LH. The C-terminal domain of zDHHC2 contains distinct sorting signals that regulate intracellular localisation in neurons and neuroendocrine cells. Mol Cell Neurosci 2017; 85:235-246. [PMID: 28768144 PMCID: PMC5711357 DOI: 10.1016/j.mcn.2017.07.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/24/2017] [Accepted: 07/28/2017] [Indexed: 11/22/2022] Open
Abstract
The S-acyltransferase zDHHC2 mediates dynamic S-acylation of PSD95 and AKAP79/150, which impacts synaptic targeting of AMPA receptors. zDHHC2 is responsive to synaptic activity and catalyses the increased S-acylation of PSD95 that occurs following action potential blockade or application of ionotropic glutamate receptor antagonists. These treatments have been proposed to increase plasma membrane delivery of zDHHC2 via an endosomal cycling pathway, enhancing substrate accessibility. To generate an improved understanding of zDHHC2 trafficking and how this might be regulated by neuronal activity, we searched for intramolecular signals that regulate enzyme localisation. Two signals were mapped to the C-terminal tail of zDHHC2: a non-canonical dileucine motif [SxxxLL] and a downstream NP motif. Mutation of these signals enhanced plasma membrane accumulation of zDHHC2 in both neuroendocrine PC12 cells and rat hippocampal neurons, consistent with reduced endocytic retrieval. Furthermore, mutation of these signals also increased accumulation of the enzyme in neurites. Interestingly, several threonine and serine residues are adjacent to these sorting motifs and analysis of phospho-mimetic mutants highlighted a potential role for phosphorylation in regulating the efficacy of these signals. This study offers new molecular insight into the signals that determine zDHHC2 localisation and highlights a potential mechanism to regulate these trafficking signals. Dynamic trafficking of zDHHC2 regulates the localisation of this S-acylation enzyme and controls access to its substrates. Two separate (and atypical) sequences were identified within the C-terminal tail of zDHHC2 that affect enzyme localisation. Mutating these motifs induced the accumulation of zDHHC2 at the plasma membrane of hippocampal neurons and PC12 cells. Phosphorylation may be a potential mechanism to regulate the efficacy of these sorting signals.
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Affiliation(s)
- Christine Salaun
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, United Kingdom
| | - Louise Ritchie
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, United Kingdom
| | - Jennifer Greaves
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, United Kingdom
| | - Trevor J Bushell
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, United Kingdom
| | - Luke H Chamberlain
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, United Kingdom.
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Hsia CCW, Ravikumar P, Ye J. Acute lung injury complicating acute kidney injury: A model of endogenous αKlotho deficiency and distant organ dysfunction. Bone 2017; 100:100-109. [PMID: 28347910 PMCID: PMC5621379 DOI: 10.1016/j.bone.2017.03.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 03/23/2017] [Accepted: 03/23/2017] [Indexed: 12/11/2022]
Abstract
The lung interfaces with atmospheric oxygen via a large surface area and is perfused by the entire venous return bearing waste products collected from the whole body. It is logical that the lung is endowed with generous anti-oxidative capacity derived both locally and from the circulation. The single-pass pleiotropic alpha-Klotho (αKlotho) protein was discovered when its genetic disruption led to premature multi-organ degeneration and early death. The extracellular domain of αKlotho is cleaved by secretases and released into circulation as endocrine soluble αKlotho protein, exerting wide-ranging cytoprotective effects including anti-oxidation on distant organs including the lung, which exhibits high sensitivity to circulating αKlotho insufficiency. Because circulating αKlotho is derived mainly from the kidney, acute kidney injury (AKI) leads to systemic αKlotho deficiency that in turn increases the risks of pulmonary complications, i.e., edema and inflammation, culminating in the acute respiratory distress syndrome. Exogenous αKlotho increases endogenous anti-oxidative capacity partly via activation of the Nrf2 pathway to protect lungs against injury caused by direct hyperoxia exposure or AKI. This article reviews the current knowledge of αKlotho antioxidation in the lung in the setting of AKI as a model of circulating αKlotho deficiency, an under-recognized condition that weakens innate cytoprotective defenses and contributes to the dysfunction in distant organs.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, United States of America.
| | - Priya Ravikumar
- Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, United States of America; Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, United States of America
| | - Jianfeng Ye
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, United States of America
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116
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Hermanns HM, Wohlfahrt J, Mais C, Hergovits S, Jahn D, Geier A. Endocytosis of pro-inflammatory cytokine receptors and its relevance for signal transduction. Biol Chem 2017; 397:695-708. [PMID: 27071147 DOI: 10.1515/hsz-2015-0277] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 04/04/2016] [Indexed: 12/14/2022]
Abstract
The pro-inflammatory cytokines tumor necrosis factor (TNF), interleukin-1 (IL-1) and interleukin-6 (IL-6) are key players of the innate and adaptive immunity. Their activity needs to be tightly controlled to allow the initiation of an appropriate immune response as defense mechanism against pathogens or tissue injury. Excessive or sustained signaling of either of these cytokines leads to severe diseases, including rheumatoid arthritis, inflammatory bowel diseases (Crohn's disease, ulcerative colitis), steatohepatitis, periodic fevers and even cancer. Studies carried out in the last 30 years have emphasized that an elaborate control system for each of these cytokines exists. Here, we summarize what is currently known about the involvement of receptor endocytosis in the regulation of these pro-inflammatory cytokines' signaling cascades. Particularly in the last few years it was shown that this cellular process is far more than a mere feedback mechanism to clear cytokines from the circulation and to shut off their signal transduction.
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117
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Gorvin CM, Rogers A, Stewart M, Paudyal A, Hough TA, Teboul L, Wells S, Brown SD, Cox RD, Thakker RV. N-ethyl-N-nitrosourea-Induced Adaptor Protein 2 Sigma Subunit 1 ( Ap2s1) Mutations Establish Ap2s1 Loss-of-Function Mice. JBMR Plus 2017; 1:3-15. [PMID: 29479578 PMCID: PMC5824975 DOI: 10.1002/jbm4.10001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The adaptor protein‐2 sigma subunit (AP2σ), encoded by AP2S1, forms a heterotetrameric complex, with AP2α, AP2β, and AP2μ subunits, that is pivotal for clathrin‐mediated endocytosis, and AP2σ loss‐of‐function mutations impair internalization of the calcium‐sensing receptor (CaSR), a G‐protein–coupled receptor, and cause familial hypocalciuric hypercalcemia type‐3 (FHH3). Mice with AP2σ mutations that would facilitate investigations of the in vivo role of AP2σ, are not available, and we therefore embarked on establishing such mice. We screened >10,000 mice treated with the mutagen N‐ethyl‐N‐nitrosourea (ENU) for Ap2s1 mutations and identified 5 Ap2s1 variants, comprising 2 missense (Tyr20Asn and Ile123Asn) and 3 intronic base substitutions, one of which altered the invariant donor splice site dinucleotide gt to gc. Three‐dimensional modeling and cellular expression of the missense Ap2s1 variants did not reveal them to alter AP2σ structure or CaSR‐mediated signaling, but investigation of the donor splice site variant revealed it to result in an in‐frame deletion of 17 evolutionarily conserved amino acids (del17) that formed part of the AP2σ α1‐helix, α1‐β3 loop, and β3 strand. Heterozygous mutant mice (Ap2s1+/del17) were therefore established, and these had AP2σ haplosufficiency but were viable with normal appearance and growth. Ap2s1+/del17 mice, when compared with Ap2s1+/+ mice, also had normal plasma concentrations of calcium, phosphate, magnesium, creatinine, urea, sodium, potassium, and alkaline phosphatase activity; normal urinary fractional excretion of calcium, phosphate, sodium, and potassium; and normal plasma parathyroid hormone (PTH) and 1,25‐dihydroxyvitamin D (1,25(OH)2) concentrations. However, homozygous Ap2s1del17/del17 mice were non‐viable and died between embryonic days 3.5 and 9.5 (E3.5–9.5), thereby indicating that AP2σ likely has important roles at the embryonic patterning stages and organogenesis of the heart, thyroid, liver, gut, lungs, pancreas, and neural systems. Thus, our studies have established a mutant mouse model that is haplosufficient for AP2σ. © 2017 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.
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Affiliation(s)
- Caroline M Gorvin
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology, and Metabolism (OCDEM), Churchill Hospital, Oxford, UK
| | - Angela Rogers
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology, and Metabolism (OCDEM), Churchill Hospital, Oxford, UK
| | - Michelle Stewart
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council Harwell Institute, Harwell Campus, Oxfordshire, UK
| | - Anju Paudyal
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council Harwell Institute, Harwell Campus, Oxfordshire, UK
| | - Tertius A Hough
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council Harwell Institute, Harwell Campus, Oxfordshire, UK
| | - Lydia Teboul
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council Harwell Institute, Harwell Campus, Oxfordshire, UK
| | - Sara Wells
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council Harwell Institute, Harwell Campus, Oxfordshire, UK
| | - Steve Dm Brown
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council Harwell Institute, Harwell Campus, Oxfordshire, UK
| | - Roger D Cox
- Mary Lyon Centre and Mammalian Genetics Unit, Medical Research Council Harwell Institute, Harwell Campus, Oxfordshire, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology, and Metabolism (OCDEM), Churchill Hospital, Oxford, UK
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118
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γ2 and γ1AP-1 complexes: Different essential functions and regulatory mechanisms in clathrin-dependent protein sorting. Eur J Cell Biol 2017; 96:356-368. [PMID: 28372831 DOI: 10.1016/j.ejcb.2017.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/24/2017] [Accepted: 03/24/2017] [Indexed: 11/20/2022] Open
Abstract
γ2 adaptin is homologous to γ1, but is only expressed in vertebrates while γ1 is found in all eukaryotes. We know little about γ2 functions and their relation to γ1. γ1 is an adaptin of the heterotetrameric AP-1 complexes, which sort proteins in and do form clathrin-coated transport vesicles and they also regulate maturation of early endosomes. γ1 knockout mice develop only to blastocysts and thus γ2 does not compensate γ1-deficiency in development. γ2 has not been classified as a clathrin-coated vesicle adaptor protein in proteome analyses and functions for monomeric γ2 in endosomal protein sorting have been proposed, but adaptin interaction studies suggested formation of heterotetrameric AP-1/γ2 complexes. We detected γ2 at the trans-Golgi network, on peripheral vesicles and identified γ2 clathrin-coated vesicles in mice. Ubiquitous σ1A and tissue-specific σ1B adaptins bind γ2 and γ1. σ1B knockout in mice does not effect γ1/σ1A AP-1 levels, but γ2/σ1A AP-1 levels are increased in brain and adipocytes. Also γ2 is essential in development. In zebrafish AP-1/γ2 and AP-1/γ1 fulfill different, essential functions in brain and the vascular system.
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119
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Caceres PS, Benedicto I, Lehmann GL, Rodriguez-Boulan EJ. Directional Fluid Transport across Organ-Blood Barriers: Physiology and Cell Biology. Cold Spring Harb Perspect Biol 2017; 9:a027847. [PMID: 28003183 PMCID: PMC5334253 DOI: 10.1101/cshperspect.a027847] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Directional fluid flow is an essential process for embryo development as well as for organ and organism homeostasis. Here, we review the diverse structure of various organ-blood barriers, the driving forces, transporters, and polarity mechanisms that regulate fluid transport across them, focusing on kidney-, eye-, and brain-blood barriers. We end by discussing how cross talk between barrier epithelial and endothelial cells, perivascular cells, and basement membrane signaling contribute to generate and maintain organ-blood barriers.
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Affiliation(s)
- Paulo S Caceres
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, New York 10065
| | - Ignacio Benedicto
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, New York 10065
| | - Guillermo L Lehmann
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, New York 10065
| | - Enrique J Rodriguez-Boulan
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, New York 10065
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120
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Abstract
The precise sequence of events promoting clathrin-coated vesicle assembly is still debated. In this issue, Kadlecova et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201608071) test structural models using quantitative microscopy in living cells to investigate the hierarchy and temporal importance of molecular events required for clathrin-coated pit initiation.
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Affiliation(s)
- Meredith N Frazier
- Department of Biological Sciences, Center for Structural Biology, Vanderbilt University, Nashville, TN 37232
| | - Lauren P Jackson
- Department of Biological Sciences, Center for Structural Biology, Vanderbilt University, Nashville, TN 37232 .,Department of Biochemistry, Center for Structural Biology, Vanderbilt University, Nashville, TN 37232
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121
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Kadlecova Z, Spielman SJ, Loerke D, Mohanakrishnan A, Reed DK, Schmid SL. Regulation of clathrin-mediated endocytosis by hierarchical allosteric activation of AP2. J Cell Biol 2016; 216:167-179. [PMID: 28003333 PMCID: PMC5223608 DOI: 10.1083/jcb.201608071] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Revised: 10/31/2016] [Accepted: 11/30/2016] [Indexed: 01/31/2023] Open
Abstract
The critical initiation phase of clathrin-mediated endocytosis (CME) determines where and when endocytosis occurs. Heterotetrameric adaptor protein 2 (AP2) complexes, which initiate clathrin-coated pit (CCP) assembly, are activated by conformational changes in response to phosphatidylinositol-4,5-bisphosphate (PIP2) and cargo binding at multiple sites. However, the functional hierarchy of interactions and how these conformational changes relate to distinct steps in CCP formation in living cells remains unknown. We used quantitative live-cell analyses to measure discrete early stages of CME and show how sequential, allosterically regulated conformational changes activate AP2 to drive both nucleation and subsequent stabilization of nascent CCPs. Our data establish that cargoes containing Yxxφ motif, but not dileucine motif, play a critical role in the earliest stages of AP2 activation and CCP nucleation. Interestingly, these cargo and PIP2 interactions are not conserved in yeast. Thus, we speculate that AP2 has evolved as a key regulatory node to coordinate CCP formation and cargo sorting and ensure high spatial and temporal regulation of CME.
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Affiliation(s)
- Zuzana Kadlecova
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Stephanie J Spielman
- Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, PA 19122
| | - Dinah Loerke
- Department of Physics and Astronomy, University of Denver, Denver, CO 80208
| | - Aparna Mohanakrishnan
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Dana Kim Reed
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Sandra L Schmid
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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122
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Hannan FM, Babinsky VN, Thakker RV. Disorders of the calcium-sensing receptor and partner proteins: insights into the molecular basis of calcium homeostasis. J Mol Endocrinol 2016; 57:R127-42. [PMID: 27647839 PMCID: PMC5064759 DOI: 10.1530/jme-16-0124] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 08/08/2016] [Indexed: 12/20/2022]
Abstract
The extracellular calcium (Ca(2+) o)-sensing receptor (CaSR) is a family C G protein-coupled receptor, which detects alterations in Ca(2+) o concentrations and modulates parathyroid hormone secretion and urinary calcium excretion. The central role of the CaSR in Ca(2+) o homeostasis has been highlighted by the identification of mutations affecting the CASR gene on chromosome 3q21.1. Loss-of-function CASR mutations cause familial hypocalciuric hypercalcaemia (FHH), whereas gain-of-function mutations lead to autosomal dominant hypocalcaemia (ADH). However, CASR mutations are only detected in ≤70% of FHH and ADH cases, referred to as FHH type 1 and ADH type 1, respectively, and studies in other FHH and ADH kindreds have revealed these disorders to be genetically heterogeneous. Thus, loss- and gain-of-function mutations of the GNA11 gene on chromosome 19p13.3, which encodes the G-protein α-11 (Gα11) subunit, lead to FHH type 2 and ADH type 2, respectively; whilst loss-of-function mutations of AP2S1 on chromosome 19q13.3, which encodes the adaptor-related protein complex 2 sigma (AP2σ) subunit, cause FHH type 3. These studies have demonstrated Gα11 to be a key mediator of downstream CaSR signal transduction, and also revealed a role for AP2σ, which is involved in clathrin-mediated endocytosis, in CaSR signalling and trafficking. Moreover, FHH type 3 has been demonstrated to represent a more severe FHH variant that may lead to symptomatic hypercalcaemia, low bone mineral density and cognitive dysfunction. In addition, calcimimetic and calcilytic drugs, which are positive and negative CaSR allosteric modulators, respectively, have been shown to be of potential benefit for these FHH and ADH disorders.
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Affiliation(s)
- Fadil M Hannan
- Academic Endocrine UnitRadcliffe Department of Medicine, University of Oxford, Oxford, UK Department of Musculoskeletal BiologyInstitute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Valerie N Babinsky
- Academic Endocrine UnitRadcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Rajesh V Thakker
- Academic Endocrine UnitRadcliffe Department of Medicine, University of Oxford, Oxford, UK
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123
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Setti M, Osti D, Richichi C, Ortensi B, Del Bene M, Fornasari L, Beznoussenko G, Mironov A, Rappa G, Cuomo A, Faretta M, Bonaldi T, Lorico A, Pelicci G. Extracellular vesicle-mediated transfer of CLIC1 protein is a novel mechanism for the regulation of glioblastoma growth. Oncotarget 2016; 6:31413-27. [PMID: 26429879 PMCID: PMC4741615 DOI: 10.18632/oncotarget.5105] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 09/18/2015] [Indexed: 01/09/2023] Open
Abstract
Little progresses have been made in the treatment of glioblastoma (GBM), the most aggressive and lethal among brain tumors. Recently we have demonstrated that Chloride Intracellular Channel-1 (CLIC1) is overexpressed in GBM compared to normal tissues, with highest expression in patients with poor prognosis. Moreover, CLIC1-silencing in cancer stem cells (CSCs) isolated from human GBM patients negatively influences proliferative capacity and self-renewal properties in vitro and impairs the in vivo tumorigenic potential. Here we show that CLIC1 exists also as a circulating protein, secreted via extracellular vesicles (EVs) released by either cell lines or GBM-derived CSCs. Extracellular vesicles (EVs), comprising exosomes and microvesicles based on their composition and biophysical properties, have been shown to sustain tumor growth in a variety of model systems, including GBM. Interestingly, treatment of GBM cells with CLIC1-containing EVs stimulates cell growth both in vitro and in vivo in a CLIC1-dose dependent manner. EVs derived from CLIC1-overexpressing GBM cells are strong inducers of proliferation in vitro and tumor engraftment in vivo. These stimulations are significantly attenuated by treatment of GBM cells with EVs derived from CLIC1-silenced cells. However, CLIC1 modulation appears to have no direct role in EV structure, biogenesis and secretion. These findings reveal that, apart from the function of CLIC1 cellular reservoir, CLIC1 contained in EVs is a novel regulator of GBM growth.
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Affiliation(s)
- Matteo Setti
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Daniela Osti
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Cristina Richichi
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Barbara Ortensi
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Massimiliano Del Bene
- Department of Neurosurgery, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy
| | - Lorenzo Fornasari
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Galina Beznoussenko
- Institute of Molecular Oncology (IFOM) of The Italian Foundation for Cancer Research (FIRC), Milan, Italy
| | - Alexandre Mironov
- Institute of Molecular Oncology (IFOM) of The Italian Foundation for Cancer Research (FIRC), Milan, Italy
| | - Germana Rappa
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Alessandro Cuomo
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Mario Faretta
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Tiziana Bonaldi
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
| | - Aurelio Lorico
- Cancer Research Center, Roseman University of Health Sciences with Roseman University College of Medicine, Las Vegas, NV, USA
| | - Giuliana Pelicci
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy.,Department of Translational Medicine, Università del Piemonte Orientale, Novara, Italy
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124
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Li X, Ortega B, Kim B, Welling PA. A Common Signal Patch Drives AP-1 Protein-dependent Golgi Export of Inwardly Rectifying Potassium Channels. J Biol Chem 2016; 291:14963-72. [PMID: 27226616 PMCID: PMC4946915 DOI: 10.1074/jbc.m116.729822] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/12/2016] [Indexed: 12/30/2022] Open
Abstract
Nearly all members of the inwardly rectifying potassium (Kir) channel family share a cytoplasmic domain structure that serves as an unusual AP-1 clathrin adaptor-dependent Golgi export signal in one Kir channel, Kir2.1 (KCNJ2), raising the question whether Kir channels share a common Golgi export mechanism. Here we explore this idea, focusing on two structurally and functionally divergent Kir family members, Kir2.3 (KCNJ4) and Kir4.1/5.1 (KCNJ10/16), which have ∼50% amino identity. We found that Golgi export of both channels is blocked upon siRNA-mediated knockdown of the AP-1 γ subunit, as predicted for the common AP-1-dependent trafficking process. A comprehensive mutagenic analysis, guided by homology mapping in atomic resolution models of Kir2.1, Kir2.3, and Kir4.1/5.1, identified a common structure that serves as a recognition site for AP-1 binding and governs Golgi export. Larger than realized from previous studies with Kir2.1, the signal is created by a patch of residues distributed at the confluence of cytoplasmic N and C termini. The signal involves a stretch of hydrophobic residues from the C-terminal region that form a hydrophobic cleft, an adjacent cluster of basic residues within the N terminus, and a potential network of salt bridges that join the N- and C-terminal poles together. Because patch formation and AP-1 binding are dependent on proper folding of the cytoplasmic domains, the signal provides a common quality control mechanism at the Golgi for Kir channels. These findings identify a new proteostatic mechanism that couples protein folding of channels to forward trafficking in the secretory pathway.
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Affiliation(s)
- Xiangming Li
- From the Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201 and
| | - Bernardo Ortega
- the Department of Biology, The College at Brockport, State University of New York, Brockport, New York 14420-2973
| | - Boyoung Kim
- From the Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201 and
| | - Paul A Welling
- From the Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201 and
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125
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Candiello E, Kratzke M, Wenzel D, Cassel D, Schu P. AP-1/σ1A and AP-1/σ1B adaptor-proteins differentially regulate neuronal early endosome maturation via the Rab5/Vps34-pathway. Sci Rep 2016; 6:29950. [PMID: 27411398 PMCID: PMC4944158 DOI: 10.1038/srep29950] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/24/2016] [Indexed: 12/26/2022] Open
Abstract
The σ1 subunit of the AP-1 clathrin-coated-vesicle adaptor-protein
complex is expressed as three isoforms. Tissues express σ1A and one of
the σ1B and σ1C isoforms. Brain is the tissue with the
highest σ1A and σ1B expression. σ1B-deficiency
leads to severe mental retardation, accumulation of early endosomes in synapses and
fewer synaptic vesicles, whose recycling is slowed down. AP-1/σ1A and
AP-1/σ1B regulate maturation of these early endosomes into
multivesicular body late endosomes, thereby controlling synaptic vesicle protein
transport into a degradative pathway. σ1A binds ArfGAP1, and with higher
affinity brain-specific ArfGAP1, which bind Rabex-5.
AP-1/σ1A-ArfGAP1-Rabex-5 complex formation leads to more endosomal
Rabex-5 and enhanced, Rab5GTP-stimulated Vps34 PI3-kinase activity,
which is essential for multivesicular body endosome formation. Formation of
AP-1/σ1A-ArfGAP1-Rabex-5 complexes is prevented by σ1B
binding of Rabex-5 and the amount of endosomal Rabex-5 is reduced. AP-1 complexes
differentially regulate endosome maturation and coordinate protein recycling and
degradation, revealing a novel molecular mechanism by which they regulate protein
transport besides their established function in clathrin-coated-vesicle
formation.
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Affiliation(s)
- Ermes Candiello
- Georg-August University Göttingen, Department for Cellular Biochemistry, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Manuel Kratzke
- Georg-August University Göttingen, Department for Cellular Biochemistry, Humboldtallee 23, D-37073 Göttingen, Germany
| | - Dirk Wenzel
- Electron microscopy, Max-Planck-Institut for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Dan Cassel
- Israel Institute of Technology, Department Biology, Haifa 32000, Israel
| | - Peter Schu
- Georg-August University Göttingen, Department for Cellular Biochemistry, Humboldtallee 23, D-37073 Göttingen, Germany
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Brown C, Szpryngiel S, Kuang G, Srivastava V, Ye W, McKee LS, Tu Y, Mäler L, Bulone V. Structural and functional characterization of the microtubule interacting and trafficking domains of two oomycete chitin synthases. FEBS J 2016; 283:3072-88. [PMID: 27363606 DOI: 10.1111/febs.13794] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 05/31/2016] [Accepted: 06/28/2016] [Indexed: 12/18/2022]
Abstract
UNLABELLED Chitin synthases (Chs) are responsible for the synthesis of chitin, a key structural cell wall polysaccharide in many organisms. They are essential for growth in certain oomycete species, some of which are pathogenic to diverse higher organisms. Recently, a microtubule interacting and trafficking (MIT) domain, which is not found in any fungal Chs, has been identified in some oomycete Chs proteins. Based on experimental data relating to the binding specificity of other eukaryotic MIT domains, there was speculation that this domain may be involved in the intracellular trafficking of Chs proteins. However, there is currently no evidence for this or any other function for the MIT domain in these enzymes. To attempt to elucidate their function, MIT domains from two Chs enzymes from the oomycete Saprolegnia monoica were cloned, expressed, and characterized. Both were shown to interact strongly with the plasma membrane component, phosphatidic acid, and to have additional putative interactions with proteins thought to be involved in protein transport and localization. Aiding our understanding of these data, the structure of the first MIT domain from a carbohydrate-active enzyme (MIT1) was solved by NMR, and a model structure of a second MIT domain (MIT2) was built by homology modeling. Our results suggest a potential function for these MIT domains in the intracellular transport and/or regulation of Chs enzymes in the oomycetes. DATABASE Structural data are available in the Biological Magnetic Resonance Bank (BMRB) database under the accession number 19987 and the PDB database under the accession number 2MPK.
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Affiliation(s)
- Christian Brown
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm, Sweden
| | - Scarlett Szpryngiel
- Department of Biochemistry and Biophysics, The Arrhenius Laboratory, Stockholm University, Sweden
| | - Guanglin Kuang
- Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Vaibhav Srivastava
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm, Sweden
| | - Weihua Ye
- Department of Biochemistry and Biophysics, The Arrhenius Laboratory, Stockholm University, Sweden
| | - Lauren S McKee
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm, Sweden
| | - Yaoquan Tu
- Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Lena Mäler
- Department of Biochemistry and Biophysics, The Arrhenius Laboratory, Stockholm University, Sweden
| | - Vincent Bulone
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm, Sweden.,ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, Urrbrae, South Australia, Australia
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127
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Zhu S, Shanbhag V, Hodgkinson VL, Petris MJ. Multiple di-leucines in the ATP7A copper transporter are required for retrograde trafficking to the trans-Golgi network. Metallomics 2016; 8:993-1001. [PMID: 27337370 DOI: 10.1039/c6mt00093b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ATP7A protein is a ubiquitous copper-transporting P-type ATPase that is mutated in the lethal pediatric disorder of copper metabolism, Menkes disease. The steady-state location of ATP7A is within the trans-Golgi network (TGN), where it delivers copper to copper-dependent enzymes within the secretory pathway. However, ATP7A constantly cycles between the TGN and the plasma membrane, and in the presence of high copper concentrations, the exocytic arm of this cycling pathway is enhanced to promote a steady-state distribution of ATP7A to post-Golgi vesicles and the plasma membrane. A single di-leucine endocytic motif within the cytosolic carboxy tail of ATP7A (1487LL) was previously shown to be essential for TGN localization by functioning in retrieval from the plasma membrane, however, the requirement of other di-leucine signals in this region has not been fully investigated. While there has been some success in identifying sequence elements within ATP7A required for trafficking and catalysis, progress has been hampered by the instability of the ATP7A cDNA in high-copy plasmids during replication in Escherichia coli. In this study, we find that the use of DNA synthesis to generate silent mutations across the majority of both mouse and human ATP7A open reading frames was sufficient to stabilize these genes in high-copy plasmids, thus permitting the generation of full-length expression constructs. Using the stabilized mouse Atp7a construct, we identify a second di-leucine motif in the carboxy tail of ATP7A (1459LL) as essential for steady-state localization in the TGN by functioning in endosome-to-TGN trafficking. Taken together, these findings demonstrate that multiple di-leucine signals are required for recycling ATP7A from the plasma membrane to the TGN and illustrate the utility of large-scale codon reassignment as a simple and effective approach to circumvent cDNA instability in high-copy plasmids.
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Affiliation(s)
- Sha Zhu
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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128
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Restricted Location of PSEN2/γ-Secretase Determines Substrate Specificity and Generates an Intracellular Aβ Pool. Cell 2016; 166:193-208. [PMID: 27293189 DOI: 10.1016/j.cell.2016.05.020] [Citation(s) in RCA: 226] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/06/2016] [Accepted: 04/28/2016] [Indexed: 01/07/2023]
Abstract
γ-Secretases are a family of intramembrane-cleaving proteases involved in various signaling pathways and diseases, including Alzheimer's disease (AD). Cells co-express differing γ-secretase complexes, including two homologous presenilins (PSENs). We examined the significance of this heterogeneity and identified a unique motif in PSEN2 that directs this γ-secretase to late endosomes/lysosomes via a phosphorylation-dependent interaction with the AP-1 adaptor complex. Accordingly, PSEN2 selectively cleaves late endosomal/lysosomal localized substrates and generates the prominent pool of intracellular Aβ that contains longer Aβ; familial AD (FAD)-associated mutations in PSEN2 increased the levels of longer Aβ further. Moreover, a subset of FAD mutants in PSEN1, normally more broadly distributed in the cell, phenocopies PSEN2 and shifts its localization to late endosomes/lysosomes. Thus, localization of γ-secretases determines substrate specificity, while FAD-causing mutations strongly enhance accumulation of aggregation-prone Aβ42 in intracellular acidic compartments. The findings reveal potentially important roles for specific intracellular, localized reactions contributing to AD pathogenesis.
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129
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Pereira EA, daSilva LLP. HIV-1 Nef: Taking Control of Protein Trafficking. Traffic 2016; 17:976-96. [PMID: 27161574 DOI: 10.1111/tra.12412] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/05/2016] [Accepted: 05/05/2016] [Indexed: 12/25/2022]
Abstract
The Nef protein of the human immunodeficiency virus is a crucial determinant of viral pathogenesis and disease progression. Nef is abundantly expressed early in infection and is thought to optimize the cellular environment for viral replication. Nef controls expression levels of various cell surface molecules that play important roles in immunity and virus life cycle, by directly interfering with the itinerary of these proteins within the endocytic and late secretory pathways. To exert these functions, Nef physically interacts with host proteins that regulate protein trafficking. In recent years, considerable progress was made in identifying host-cell-interacting partners for Nef, and the molecular machinery used by Nef to interfere with protein trafficking has started to be unraveled. Here, we briefly review the knowledge gained and discuss new findings regarding the mechanisms by which Nef modifies the intracellular trafficking pathways to prevent antigen presentation, facilitate viral particle release and enhance the infectivity of HIV-1 virions.
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Affiliation(s)
- Estela A Pereira
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Luis L P daSilva
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
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130
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Frazier MN, Davies AK, Voehler M, Kendall AK, Borner GHH, Chazin WJ, Robinson MS, Jackson LP. Molecular Basis for the Interaction Between AP4 β4 and its Accessory Protein, Tepsin. Traffic 2016; 17:400-15. [PMID: 26756312 PMCID: PMC4805503 DOI: 10.1111/tra.12375] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 01/07/2016] [Accepted: 01/07/2016] [Indexed: 01/08/2023]
Abstract
The adaptor protein 4 (AP4) complex (ϵ/β4/μ4/σ4 subunits) forms a non-clathrin coat on vesicles departing the trans-Golgi network. AP4 biology remains poorly understood, in stark contrast to the wealth of molecular data available for the related clathrin adaptors AP1 and AP2. AP4 is important for human health because mutations in any AP4 subunit cause severe neurological problems, including intellectual disability and progressive spastic para- or tetraplegias. We have used a range of structural, biochemical and biophysical approaches to determine the molecular basis for how the AP4 β4 C-terminal appendage domain interacts with tepsin, the only known AP4 accessory protein. We show that tepsin harbors a hydrophobic sequence, LFxG[M/L]x[L/V], in its unstructured C-terminus, which binds directly and specifically to the C-terminal β4 appendage domain. Using nuclear magnetic resonance chemical shift mapping, we define the binding site on the β4 appendage by identifying residues on the surface whose signals are perturbed upon titration with tepsin. Point mutations in either the tepsin LFxG[M/L]x[L/V] sequence or in its cognate binding site on β4 abolish in vitro binding. In cells, the same point mutations greatly reduce the amount of tepsin that interacts with AP4. However, they do not abolish the binding between tepsin and AP4 completely, suggesting the existence of additional interaction sites between AP4 and tepsin. These data provide one of the first detailed mechanistic glimpses at AP4 coat assembly and should provide an entry point for probing the role of AP4-coated vesicles in cell biology, and especially in neuronal function.
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Affiliation(s)
- Meredith N Frazier
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Alexandra K Davies
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, UK
| | - Markus Voehler
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Department of Biochemistry and Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Amy K Kendall
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Georg H H Borner
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Walter J Chazin
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Department of Biochemistry and Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Margaret S Robinson
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge, UK
| | - Lauren P Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
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131
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Abstract
Liposome flotation assays are a convenient tool to study protein-phosphoinositide interactions. Working with liposomes resembles physiological conditions more than protein-lipid overlay assays, which makes this method less prone to detect false positive interactions. However, liposome lipid composition must be well-considered in order to prevent nonspecific binding of the protein through electrostatic interactions with negatively charged lipids like phosphatidylserine. In this protocol we use the PROPPIN Hsv2 (homologous with swollen vacuole phenotype 2) as an example to demonstrate the influence of liposome lipid composition on binding and show how phosphoinositide binding specificities of a protein can be characterized with this method.
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132
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Zhou X, Zeng J, Ouyang C, Luo Q, Yu M, Yang Z, Wang H, Shen K, Shi A. A novel bipartite UNC-101/AP-1 μ1 binding signal mediates KVS-4/Kv2.1 somatodendritic distribution inCaenorhabditis elegans. FEBS Lett 2015; 590:76-92. [DOI: 10.1002/1873-3468.12043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/10/2015] [Accepted: 12/04/2015] [Indexed: 12/13/2022]
Affiliation(s)
- Xin Zhou
- Department of Medical Genetics; School of Basic Medicine and the Collaborative Innovation Center for Brain Science; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Jia Zeng
- Department of Medical Genetics; School of Basic Medicine and the Collaborative Innovation Center for Brain Science; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Chenxi Ouyang
- Department of Vascular Surgery; Union Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Qianyun Luo
- Department of Medical Genetics; School of Basic Medicine and the Collaborative Innovation Center for Brain Science; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Miao Yu
- Department of Vascular Surgery; Union Hospital; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Zhenrong Yang
- Department of Medical Genetics; School of Basic Medicine and the Collaborative Innovation Center for Brain Science; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Hui Wang
- Department of Medical Genetics; School of Basic Medicine and the Collaborative Innovation Center for Brain Science; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
| | - Kang Shen
- Department of Biology; Howard Hughes Medical Institute; Stanford University; Palo Alto CA USA
| | - Anbing Shi
- Department of Medical Genetics; School of Basic Medicine and the Collaborative Innovation Center for Brain Science; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
- Institute for Brain Research; Huazhong University of Science and Technology; Wuhan Hubei China
- Key Laboratory of Neurological Disease of National Education Ministry; Tongji Medical College; Huazhong University of Science and Technology; Wuhan Hubei China
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133
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Whitfield ST, Burston HE, Bean BDM, Raghuram N, Maldonado-Báez L, Davey M, Wendland B, Conibear E. The alternate AP-1 adaptor subunit Apm2 interacts with the Mil1 regulatory protein and confers differential cargo sorting. Mol Biol Cell 2015; 27:588-98. [PMID: 26658609 PMCID: PMC4751606 DOI: 10.1091/mbc.e15-09-0621] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/01/2015] [Indexed: 12/31/2022] Open
Abstract
Adaptor complexes are important for cargo sorting in clathrin-coated vesicles. The µ adaptor subunits Apm1 and Apm2 create functionally distinct versions of the yeast AP-1 complex. A novel regulatory protein is identified that selectively binds Apm2-containing complexes and contributes to their membrane recruitment. Heterotetrameric adaptor protein complexes are important mediators of cargo protein sorting in clathrin-coated vesicles. The cell type–specific expression of alternate μ chains creates distinct forms of AP-1 with altered cargo sorting, but how these subunits confer differential function is unclear. Whereas some studies suggest the μ subunits specify localization to different cellular compartments, others find that the two forms of AP-1 are present in the same vesicle but recognize different cargo. Yeast have two forms of AP-1, which differ only in the μ chain. Here we show that the variant μ chain Apm2 confers distinct cargo-sorting functions. Loss of Apm2, but not of Apm1, increases cell surface levels of the v-SNARE Snc1. However, Apm2 is unable to replace Apm1 in sorting Chs3, which requires a dileucine motif recognized by the γ/σ subunits common to both complexes. Apm2 and Apm1 colocalize at Golgi/early endosomes, suggesting that they do not associate with distinct compartments. We identified a novel, conserved regulatory protein that is required for Apm2-dependent sorting events. Mil1 is a predicted lipase that binds Apm2 but not Apm1 and contributes to its membrane recruitment. Interactions with specific regulatory factors may provide a general mechanism to diversify the functional repertoire of clathrin adaptor complexes.
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Affiliation(s)
- Shawn T Whitfield
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Department of Biochemistry and Molecular Biology and Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Helen E Burston
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Department of Biochemistry and Molecular Biology and Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Björn D M Bean
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Department of Biochemistry and Molecular Biology and Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Nandini Raghuram
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | | | - Michael Davey
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Beverly Wendland
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218-2685
| | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Department of Biochemistry and Molecular Biology and Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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134
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Lin YH, Currinn H, Pocha SM, Rothnie A, Wassmer T, Knust E. AP-2-complex-mediated endocytosis of Drosophila Crumbs regulates polarity by antagonizing Stardust. J Cell Sci 2015; 128:4538-49. [PMID: 26527400 DOI: 10.1242/jcs.174573] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 10/26/2015] [Indexed: 12/21/2022] Open
Abstract
Maintenance of epithelial polarity depends on the correct localization and levels of polarity determinants. The evolutionarily conserved transmembrane protein Crumbs is crucial for the size and identity of the apical membrane, yet little is known about the molecular mechanisms controlling the amount of Crumbs at the surface. Here, we show that Crumbs levels on the apical membrane depend on a well-balanced state of endocytosis and stabilization. The adaptor protein 2 (AP-2) complex binds to a motif in the cytoplasmic tail of Crumbs that overlaps with the binding site of Stardust, a protein known to stabilize Crumbs on the surface. Preventing endocytosis by mutation of AP-2 causes expansion of the Crumbs-positive plasma membrane domain and polarity defects, which can be partially rescued by removing one copy of crumbs. Strikingly, knocking down both AP-2 and Stardust leads to the retention of Crumbs on the membrane. This study provides evidence for a molecular mechanism, based on stabilization and endocytosis, to adjust surface levels of Crumbs, which are essential for maintaining epithelial polarity.
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Affiliation(s)
- Ya-Huei Lin
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, Dresden 01307, Germany
| | - Heather Currinn
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Shirin Meher Pocha
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, Dresden 01307, Germany
| | - Alice Rothnie
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Thomas Wassmer
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Elisabeth Knust
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, Dresden 01307, Germany
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135
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Dennis MK, Mantegazza AR, Snir OL, Tenza D, Acosta-Ruiz A, Delevoye C, Zorger R, Sitaram A, de Jesus-Rojas W, Ravichandran K, Rux J, Sviderskaya EV, Bennett DC, Raposo G, Marks MS, Setty SRG. BLOC-2 targets recycling endosomal tubules to melanosomes for cargo delivery. ACTA ACUST UNITED AC 2015; 209:563-77. [PMID: 26008744 PMCID: PMC4442807 DOI: 10.1083/jcb.201410026] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Quantitative analyses of melanosome cargo localization and trafficking and of endosomal membrane dynamics in immortalized melanocytes from mouse Hermansky–Pudlak syndrome models show that BLOC-2 functions to specify the delivery of recycling endosomal cargo transport intermediates to maturing melanosomes. Hermansky–Pudlak syndrome (HPS) is a group of disorders characterized by the malformation of lysosome-related organelles, such as pigment cell melanosomes. Three of nine characterized HPS subtypes result from mutations in subunits of BLOC-2, a protein complex with no known molecular function. In this paper, we exploit melanocytes from mouse HPS models to place BLOC-2 within a cargo transport pathway from recycling endosomal domains to maturing melanosomes. In BLOC-2–deficient melanocytes, the melanosomal protein TYRP1 was largely depleted from pigment granules and underwent accelerated recycling from endosomes to the plasma membrane and to the Golgi. By live-cell imaging, recycling endosomal tubules of wild-type melanocytes made frequent and prolonged contacts with maturing melanosomes; in contrast, tubules from BLOC-2–deficient cells were shorter in length and made fewer, more transient contacts with melanosomes. These results support a model in which BLOC-2 functions to direct recycling endosomal tubular transport intermediates to maturing melanosomes and thereby promote cargo delivery and optimal pigmentation.
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Affiliation(s)
- Megan K Dennis
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104
| | - Adriana R Mantegazza
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104
| | - Olivia L Snir
- Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104
| | - Danièle Tenza
- Institut Curie, Centre de Recherche; Structure and Membrane Compartments, Centre National de la Recherche Scientifique, Unité Mixte de Recherche (UMR) 144; and Cell and Tissue Imaging Facility, Centre National de la Recherche Scientifique UMR144, Paris F-75248, France Institut Curie, Centre de Recherche; Structure and Membrane Compartments, Centre National de la Recherche Scientifique, Unité Mixte de Recherche (UMR) 144; and Cell and Tissue Imaging Facility, Centre National de la Recherche Scientifique UMR144, Paris F-75248, France
| | - Amanda Acosta-Ruiz
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104
| | - Cédric Delevoye
- Institut Curie, Centre de Recherche; Structure and Membrane Compartments, Centre National de la Recherche Scientifique, Unité Mixte de Recherche (UMR) 144; and Cell and Tissue Imaging Facility, Centre National de la Recherche Scientifique UMR144, Paris F-75248, France Institut Curie, Centre de Recherche; Structure and Membrane Compartments, Centre National de la Recherche Scientifique, Unité Mixte de Recherche (UMR) 144; and Cell and Tissue Imaging Facility, Centre National de la Recherche Scientifique UMR144, Paris F-75248, France
| | - Richard Zorger
- Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104
| | - Anand Sitaram
- Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104
| | - Wilfredo de Jesus-Rojas
- Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104
| | - Keerthana Ravichandran
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India 560 012
| | - John Rux
- Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 In Silico Molecular, LLC, Blue Bell, PA 19422
| | - Elena V Sviderskaya
- Molecular Cell Sciences Research Centre, St. George's, University of London, London SW17 0RE, England, UK
| | - Dorothy C Bennett
- Molecular Cell Sciences Research Centre, St. George's, University of London, London SW17 0RE, England, UK
| | - Graça Raposo
- Institut Curie, Centre de Recherche; Structure and Membrane Compartments, Centre National de la Recherche Scientifique, Unité Mixte de Recherche (UMR) 144; and Cell and Tissue Imaging Facility, Centre National de la Recherche Scientifique UMR144, Paris F-75248, France Institut Curie, Centre de Recherche; Structure and Membrane Compartments, Centre National de la Recherche Scientifique, Unité Mixte de Recherche (UMR) 144; and Cell and Tissue Imaging Facility, Centre National de la Recherche Scientifique UMR144, Paris F-75248, France Institut Curie, Centre de Recherche; Structure and Membrane Compartments, Centre National de la Recherche Scientifique, Unité Mixte de Recherche (UMR) 144; and Cell and Tissue Imaging Facility, Centre National de la Recherche Scientifique UMR144, Paris F-75248, France
| | - Michael S Marks
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104
| | - Subba Rao Gangi Setty
- Department of Pathology and Laboratory Medicine, Department of Physiology, and Penn Vision Research Center, University of Pennsylvania, Philadelphia, PA 19104 Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India 560 012
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136
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Pan PY, Marrs J, Ryan TA. Vesicular glutamate transporter 1 orchestrates recruitment of other synaptic vesicle cargo proteins during synaptic vesicle recycling. J Biol Chem 2015. [PMID: 26224632 DOI: 10.1074/jbc.m115.651711] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A long standing question in synaptic physiology is how neurotransmitter-filled vesicles are rebuilt after exocytosis. Among the first steps in this process is the endocytic retrieval of the transmembrane proteins that are enriched in synaptic vesicles (SVs). At least six types of transmembrane proteins must be recovered, but the rules for how this multiple cargo selection is accomplished are poorly understood. Among these SV cargos is the vesicular glutamate transporter (vGlut). We show here that vGlut1 has a strong influence on the kinetics of retrieval of half of the known SV cargos and that specifically impairing the endocytosis of vGlut1 in turn slows down other SV cargos, demonstrating that cargo retrieval is a collective cargo-driven process. Finally, we demonstrate that different cargos can be retrieved in the same synapse with different kinetics, suggesting that additional post-endocytic sorting steps likely occur in the nerve terminal.
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Affiliation(s)
- Ping-Yue Pan
- From the Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021
| | - Julia Marrs
- From the Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021
| | - Timothy A Ryan
- From the Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021
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Schroeder B, McNiven MA. Importance of endocytic pathways in liver function and disease. Compr Physiol 2015; 4:1403-17. [PMID: 25428849 DOI: 10.1002/cphy.c140001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hepatocellular endocytosis is a highly dynamic process responsible for the internalization of a variety of different receptor ligand complexes, trophic factors, lipids, and, unfortunately, many different pathogens. The uptake of these external agents has profound effects on seminal cellular processes including signaling cascades, migration, growth, and proliferation. The hepatocyte, like other well-polarized epithelial cells, possesses a host of different endocytic mechanisms and entry routes to ensure the selective internalization of cargo molecules. These pathways include receptor-mediated endocytosis, lipid raft associated endocytosis, caveolae, or fluid-phase uptake, although there are likely many others. Understanding and defining the regulatory mechanisms underlying these distinct entry routes, sorting and vesicle formation, as well as the postendocytic trafficking pathways is of high importance especially in the liver, as their mis-regulation can contribute to aberrant liver pathology and liver diseases. Further, these processes can be "hijacked" by a variety of different infectious agents and viruses. This review provides an overview of common components of the endocytic and postendocytic trafficking pathways utilized by hepatocytes. It will also discuss in more detail how these general themes apply to liver-specific processes including iron homeostasis, HBV infection, and even hepatic steatosis.
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Affiliation(s)
- Barbara Schroeder
- Department of Biochemistry and Molecular Biology, Center for Basic Research in Digestive Diseases, Mayo Clinic and Foundation, Rochester, Minnesota
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138
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Hierro A, Gershlick DC, Rojas AL, Bonifacino JS. Formation of Tubulovesicular Carriers from Endosomes and Their Fusion to the trans-Golgi Network. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:159-202. [PMID: 26315886 DOI: 10.1016/bs.ircmb.2015.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Endosomes undergo extensive spatiotemporal rearrangements as proteins and lipids flux through them in a series of fusion and fission events. These controlled changes enable the concentration of cargo for eventual degradation while ensuring the proper recycling of other components. A growing body of studies has now defined multiple recycling pathways from endosomes to the trans-Golgi network (TGN) which differ in their molecular machineries. The recycling process requires specific sets of lipids, coats, adaptors, and accessory proteins that coordinate cargo selection with membrane deformation and its association with the cytoskeleton. Specific tethering factors and SNARE (SNAP (Soluble NSF Attachment Protein) Receptor) complexes are then required for the docking and fusion with the acceptor membrane. Herein, we summarize some of the current knowledge of the machineries that govern the retrograde transport from endosomes to the TGN.
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Affiliation(s)
- Aitor Hierro
- Structural Biology Unit, CIC bioGUNE, Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - David C Gershlick
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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139
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Endocytosis and Trafficking of Natriuretic Peptide Receptor-A: Potential Role of Short Sequence Motifs. MEMBRANES 2015; 5:253-87. [PMID: 26151885 PMCID: PMC4584282 DOI: 10.3390/membranes5030253] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Revised: 06/25/2015] [Accepted: 06/25/2015] [Indexed: 12/19/2022]
Abstract
The targeted endocytosis and redistribution of transmembrane receptors among membrane-bound subcellular organelles are vital for their correct signaling and physiological functions. Membrane receptors committed for internalization and trafficking pathways are sorted into coated vesicles. Cardiac hormones, atrial and brain natriuretic peptides (ANP and BNP) bind to guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA) and elicit the generation of intracellular second messenger cyclic guanosine 3',5'-monophosphate (cGMP), which lowers blood pressure and incidence of heart failure. After ligand binding, the receptor is rapidly internalized, sequestrated, and redistributed into intracellular locations. Thus, NPRA is considered a dynamic cellular macromolecule that traverses different subcellular locations through its lifetime. The utilization of pharmacologic and molecular perturbants has helped in delineating the pathways of endocytosis, trafficking, down-regulation, and degradation of membrane receptors in intact cells. This review describes the investigation of the mechanisms of internalization, trafficking, and redistribution of NPRA compared with other cell surface receptors from the plasma membrane into the cell interior. The roles of different short-signal peptide sequence motifs in the internalization and trafficking of other membrane receptors have been briefly reviewed and their potential significance in the internalization and trafficking of NPRA is discussed.
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140
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Role of plasma-membrane-bound sialidase NEU3 in clathrin-mediated endocytosis. Biochem J 2015; 470:131-44. [PMID: 26251452 DOI: 10.1042/bj20141550] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 06/24/2015] [Indexed: 12/13/2022]
Abstract
Gangliosides are sialic acid-containing glycosphingolipids mainly expressed at the outer leaflet of the plasma membrane. Sialidase NEU3 is a key enzyme in the catabolism of gangliosides with its up-regulation having been observed in human cancer cells. In the case of CME (clathrin-mediated endocytosis), although this has been widely studied, the role of NEU3 and gangliosides in this cellular process has not yet been established. In the present study, we found an increased internalization of Tf (transferrin), the archetypical cargo for CME, in cells expressing complex gangliosides with high levels of sialylation. The ectopic expression of NEU3 led to a drastic decrease in Tf endocytosis, suggesting the participation of gangliosides in this process. However, the reduction in Tf endocytosis caused by NEU3 was still observed in glycosphingolipid-depleted cells, indicating that NEU3 could operate in a way that is independent of its action on gangliosides. Additionally, internalization of α2-macroglobulin and low-density lipoprotein, other typical ligands in CME, was also decreased in NEU3-expressing cells. In contrast, internalization of cholera toxin β-subunit, which is endocytosed by both clathrin-dependent and clathrin-independent mechanisms, remained unaltered. Kinetic assays revealed that NEU3 caused a reduction in the sorting of endocytosed Tf to early and recycling endosomes, with the Tf binding at the cell surface being also reduced. NEU3-expressing cells showed an altered subcellular distribution of clathrin adaptor AP-2 (adaptor protein 2), but did not reveal any changes in the membrane distribution of clathrin, PtdIns(4,5)P2 or caveolin-1. Overall, these results suggest a specific and novel role of NEU3 in CME.
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141
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Hannan FM, Howles SA, Rogers A, Cranston T, Gorvin CM, Babinsky VN, Reed AA, Thakker CE, Bockenhauer D, Brown RS, Connell JM, Cook J, Darzy K, Ehtisham S, Graham U, Hulse T, Hunter SJ, Izatt L, Kumar D, McKenna MJ, McKnight JA, Morrison PJ, Mughal MZ, O'Halloran D, Pearce SH, Porteous ME, Rahman M, Richardson T, Robinson R, Scheers I, Siddique H, Van't Hoff WG, Wang T, Whyte MP, Nesbit MA, Thakker RV. Adaptor protein-2 sigma subunit mutations causing familial hypocalciuric hypercalcaemia type 3 (FHH3) demonstrate genotype-phenotype correlations, codon bias and dominant-negative effects. Hum Mol Genet 2015; 24:5079-92. [PMID: 26082470 PMCID: PMC4550820 DOI: 10.1093/hmg/ddv226] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 06/12/2015] [Indexed: 12/05/2022] Open
Abstract
The adaptor protein-2 sigma subunit (AP2σ2) is pivotal for clathrin-mediated endocytosis of plasma membrane constituents such as the calcium-sensing receptor (CaSR). Mutations of the AP2σ2 Arg15 residue result in familial hypocalciuric hypercalcaemia type 3 (FHH3), a disorder of extracellular calcium (Ca2+o) homeostasis. To elucidate the role of AP2σ2 in Ca2+o regulation, we investigated 65 FHH probands, without other FHH-associated mutations, for AP2σ2 mutations, characterized their functional consequences and investigated the genetic mechanisms leading to FHH3. AP2σ2 mutations were identified in 17 probands, comprising 5 Arg15Cys, 4 Arg15His and 8 Arg15Leu mutations. A genotype–phenotype correlation was observed with the Arg15Leu mutation leading to marked hypercalcaemia. FHH3 probands harboured additional phenotypes such as cognitive dysfunction. All three FHH3-causing AP2σ2 mutations impaired CaSR signal transduction in a dominant-negative manner. Mutational bias was observed at the AP2σ2 Arg15 residue as other predicted missense substitutions (Arg15Gly, Arg15Pro and Arg15Ser), which also caused CaSR loss-of-function, were not detected in FHH probands, and these mutations were found to reduce the numbers of CaSR-expressing cells. FHH3 probands had significantly greater serum calcium (sCa) and magnesium (sMg) concentrations with reduced urinary calcium to creatinine clearance ratios (CCCR) in comparison with FHH1 probands with CaSR mutations, and a calculated index of sCa × sMg/100 × CCCR, which was ≥ 5.0, had a diagnostic sensitivity and specificity of 83 and 86%, respectively, for FHH3. Thus, our studies demonstrate AP2σ2 mutations to result in a more severe FHH phenotype with genotype–phenotype correlations, and a dominant-negative mechanism of action with mutational bias at the Arg15 residue.
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Affiliation(s)
- Fadil M Hannan
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Sarah A Howles
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Angela Rogers
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Treena Cranston
- Oxford Molecular Genetics Laboratory, Churchill Hospital, Oxford, UK
| | - Caroline M Gorvin
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Valerie N Babinsky
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Anita A Reed
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Clare E Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Detlef Bockenhauer
- Renal Unit, Great Ormond Street Hospital for Children NHS Foundation Trust and UCL Institute of Child Health, London, UK
| | - Rosalind S Brown
- Division of Endocrinology, Boston Children's Hospital, Boston, MA, USA
| | - John M Connell
- School of Medicine, Ninewells Hospital, University of Dundee, Dundee, UK
| | - Jacqueline Cook
- Clinical Genetics Department, Sheffield Children's Hospital NHS Foundation Trust, Sheffield, UK
| | - Ken Darzy
- Queen Elizabeth II Hospital, Welwyn Garden City, UK
| | - Sarah Ehtisham
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Manchester, UK
| | - Una Graham
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Belfast, UK
| | - Tony Hulse
- Department of Paediatrics, Evelina London Children's Hospital, St. Thomas' Hospital, London, UK
| | - Steven J Hunter
- Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Belfast, UK
| | - Louise Izatt
- Department of Clinical Genetics, Guy's Hospital, London, UK
| | - Dhavendra Kumar
- Institute of Cancer and Genetics, University Hospital of Wales, Cardiff, UK
| | - Malachi J McKenna
- Department of Endocrinology, St. Vincent's University Hospital, Dublin, Ireland
| | - John A McKnight
- Metabolic Unit, Western General Hospital, NHS Lothian and University of Edinburgh, Edinburgh, UK
| | - Patrick J Morrison
- Centre for Cancer Research and Cell Biology, Queens University of Belfast, Belfast, UK, Department of Genetic Medicine, Belfast HSC Trust, Belfast, UK
| | - M Zulf Mughal
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Manchester, UK
| | | | - Simon H Pearce
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Mary E Porteous
- SE Scotland Genetic Service, Western General Hospital, Edinburgh, UK
| | - Mushtaqur Rahman
- Department of Endocrinology, Northwick Park Hospital, London, UK
| | - Tristan Richardson
- Diabetes and Endocrine Centre, Royal Bournemouth Hospital, Bournemouth, UK
| | - Robert Robinson
- Department of Endocrinology, Chesterfield Royal Hospital NHS Foundation Trust, Derbyshire, UK
| | - Isabelle Scheers
- Pediatric Gastroenterology, Hepatology and Nutrition Unit, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Haroon Siddique
- Department of Endocrinology, Russells Hall Hospital, Dudley, UK
| | - William G Van't Hoff
- Renal Unit, Great Ormond Street Hospital for Children NHS Foundation Trust and UCL Institute of Child Health, London, UK
| | - Timothy Wang
- Department of Clinical Biochemistry, Frimley Park Hospital, Surrey, UK and
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, Missouri, USA
| | - M Andrew Nesbit
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK,
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142
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Lahav A, Rozenberg H, Parnis A, Cassel D, Adir N. Structure of the bovine COPI δ subunit μ homology domain at 2.15 Å resolution. ACTA ACUST UNITED AC 2015; 71:1328-34. [PMID: 26057672 DOI: 10.1107/s1399004715006203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 03/26/2015] [Indexed: 11/11/2022]
Abstract
The heptameric COPI coat (coatomer) plays an essential role in vesicular transport in the early secretory system of eukaryotic cells. While the structures of some of the subunits have been determined, that of the δ-COP subunit has not been reported to date. The δ-COP subunit is part of a subcomplex with structural similarity to tetrameric clathrin adaptors (APs), where δ-COP is the structural homologue of the AP μ subunit. Here, the crystal structure of the μ homology domain (MHD) of δ-COP (δ-MHD) obtained by phasing using a combined SAD-MR method is presented at 2.15 Å resolution. The crystallographic asymmetric unit contains two monomers that exhibit short sections of disorder, which may allude to flexible regions of the protein. The δ-MHD is composed of two subdomains connected by unstructured linkers. Comparison between this structure and those of known MHD domains from the APs shows significant differences in the positions of specific loops and β-sheets, as well as a more general change in the relative positions of the protein subdomains. The identified difference may be the major source of cargo-binding specificity. Finally, the crystal structure is used to analyze the potential effect of the I422T mutation in δ-COP previously reported to cause a neurodegenerative phenotype in mice.
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Affiliation(s)
- Avital Lahav
- Schulich Faculty of Chemistry, Technion, Haifa 32000, Israel
| | - Haim Rozenberg
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Anna Parnis
- Department of Biology, Technion, Haifa 32000, Israel
| | - Dan Cassel
- Department of Biology, Technion, Haifa 32000, Israel
| | - Noam Adir
- Schulich Faculty of Chemistry, Technion, Haifa 32000, Israel
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143
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Ujike M, Taguchi F. Incorporation of spike and membrane glycoproteins into coronavirus virions. Viruses 2015; 7:1700-25. [PMID: 25855243 PMCID: PMC4411675 DOI: 10.3390/v7041700] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 03/23/2015] [Accepted: 03/24/2015] [Indexed: 12/15/2022] Open
Abstract
The envelopes of coronaviruses (CoVs) contain primarily three proteins; the two major glycoproteins spike (S) and membrane (M), and envelope (E), a non-glycosylated protein. Unlike other enveloped viruses, CoVs bud and assemble at the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC). For efficient virion assembly, these proteins must be targeted to the budding site and to interact with each other or the ribonucleoprotein. Thus, the efficient incorporation of viral envelope proteins into CoV virions depends on protein trafficking and protein–protein interactions near the ERGIC. The goal of this review is to summarize recent findings on the mechanism of incorporation of the M and S glycoproteins into the CoV virion, focusing on protein trafficking and protein–protein interactions.
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Affiliation(s)
- Makoto Ujike
- Laboratory of Virology and Viral Infections, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-8602, Japan.
| | - Fumihiro Taguchi
- Laboratory of Virology and Viral Infections, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-8602, Japan.
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144
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Paczkowski JE, Richardson BC, Fromme JC. Cargo adaptors: structures illuminate mechanisms regulating vesicle biogenesis. Trends Cell Biol 2015; 25:408-16. [PMID: 25795254 DOI: 10.1016/j.tcb.2015.02.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 02/11/2015] [Accepted: 02/19/2015] [Indexed: 12/29/2022]
Abstract
Cargo adaptors sort transmembrane protein cargos into nascent vesicles by binding directly to their cytosolic domains. Recent studies have revealed previously unappreciated roles for cargo adaptors and regulatory mechanisms governing their function. The adaptor protein (AP)-1 and AP-2 clathrin adaptors switch between open and closed conformations that ensure they function at the right place at the right time. The exomer cargo adaptor has a direct role in remodeling the membrane for vesicle fission. Several different cargo adaptors functioning in distinct trafficking pathways at the Golgi are similarly regulated through bivalent binding to the ADP-ribosylation factor 1 (Arf1) GTPase, potentially enabling regulation by a threshold concentration of Arf1. Taken together, these studies highlight that cargo adaptors do more than just adapt cargos.
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Affiliation(s)
- Jon E Paczkowski
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Brian C Richardson
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - J Christopher Fromme
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.
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de la Fuente-Ortega E, Gravotta D, Perez Bay A, Benedicto I, Carvajal-Gonzalez JM, Lehmann GL, Lagos CF, Rodríguez-Boulan E. Basolateral sorting of chloride channel 2 is mediated by interactions between a dileucine motif and the clathrin adaptor AP-1. Mol Biol Cell 2015; 26:1728-42. [PMID: 25739457 PMCID: PMC4436783 DOI: 10.1091/mbc.e15-01-0047] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 02/25/2015] [Indexed: 01/03/2023] Open
Abstract
ClC-2 is a ubiquitous chloride channel that regulates cell volume, ion transport, and acid-base balance. Mice knocked out for ClC-2 are blind and sterile. Basolateral localization of ClC-2 in epithelia is mediated by the interaction of a dileucine motif with a highly conserved pocket in the γ1-σ1A hemicomplex of AP-1. In spite of the many key cellular functions of chloride channels, the mechanisms that mediate their subcellular localization are largely unknown. ClC-2 is a ubiquitous chloride channel usually localized to the basolateral domain of epithelia that regulates cell volume, ion transport, and acid–base balance; mice knocked out for ClC-2 are blind and sterile. Previous work suggested that CLC-2 is sorted basolaterally by TIFS812LL, a dileucine motif in CLC-2's C-terminal domain. However, our in silico modeling of ClC-2 suggested that this motif was buried within the channel's dimerization interface and identified two cytoplasmically exposed dileucine motifs, ESMI623LL and QVVA635LL, as candidate sorting signals. Alanine mutagenesis and trafficking assays support a scenario in which ESMI623LL acts as the authentic basolateral signal of ClC-2. Silencing experiments and yeast three-hybrid assays demonstrated that both ubiquitous (AP-1A) and epithelium-specific (AP-1B) forms of the tetrameric clathrin adaptor AP-1 are capable of carrying out basolateral sorting of ClC-2 through interactions of ESMI623LL with a highly conserved pocket in their γ1-σ1A hemicomplex.
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Affiliation(s)
- Erwin de la Fuente-Ortega
- Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065
| | - Diego Gravotta
- Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065
| | - Andres Perez Bay
- Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065
| | - Ignacio Benedicto
- Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065
| | | | - Guillermo L Lehmann
- Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065
| | - Carlos F Lagos
- Department of Endocrinology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago Centro 8330074, Santiago, Chile Facultad de Ciencia, Universidad San Sebastián, Providencia 7510157, Santiago, Chile
| | - Enrique Rodríguez-Boulan
- Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, NY 10065
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146
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Rhodes DA, Chen HC, Price AJ, Keeble AH, Davey MS, James LC, Eberl M, Trowsdale J. Activation of human γδ T cells by cytosolic interactions of BTN3A1 with soluble phosphoantigens and the cytoskeletal adaptor periplakin. THE JOURNAL OF IMMUNOLOGY 2015; 194:2390-8. [PMID: 25637025 PMCID: PMC4337483 DOI: 10.4049/jimmunol.1401064] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The three butyrophilin BTN3A molecules, BTN3A1, BTN3A2, and BTN3A3, are members of the B7/butyrophilin-like group of Ig superfamily receptors, which modulate the function of T cells. BTN3A1 controls activation of human Vγ9/Vδ2 T cells by direct or indirect presentation of self and nonself phosphoantigens (pAg). We show that the microbial metabolite (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate binds to the intracellular B30.2 domain of BTN3A1 with an affinity of 1.1 μM, whereas the endogenous pAg isopentenyl pyrophosphate binds with an affinity of 627 μM. Coculture experiments using knockdown cell lines showed that in addition to BTN3A1, BTN3A2 and BTN3A3 transmit activation signals to human γδ T cells in response to (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate and the aminobisphosphonate drug zoledronate that causes intracellular accumulation of isopentenyl pyrophosphate. The plakin family member periplakin, identified in yeast two-hybrid assays, interacted with a membrane-proximal di-leucine motif, located proximal to the B30.2 domain in the BTN3A1 cytoplasmic tail. Periplakin did not interact with BTN3A2 or BTN3A3, which do not contain the di-leucine motif. Re-expression into a BTN3A1 knockdown line of wild-type BTN3A1, but not of a variant lacking the periplakin binding motif, BTN3A1Δexon5, restored γδ T cell responses, demonstrating a functional role for periplakin interaction. These data, together with the widespread expression in epithelial cells, tumor tissues, and macrophages detected using BTN3A antiserum, are consistent with complex functions for BTN3A molecules in tissue immune surveillance and infection, linking the cell cytoskeleton to γδ T cell activation by indirectly presenting pAg to the Vγ9/Vδ2 TCR.
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Affiliation(s)
- David A Rhodes
- Immunology Division, Department of Pathology, University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom;
| | - Hung-Chang Chen
- Cardiff Institute of Infection & Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom; and
| | - Amanda J Price
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Anthony H Keeble
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Martin S Davey
- Cardiff Institute of Infection & Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom; and
| | - Leo C James
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Matthias Eberl
- Cardiff Institute of Infection & Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom; and
| | - John Trowsdale
- Immunology Division, Department of Pathology, University of Cambridge, Cambridge Institute for Medical Research, Cambridge CB2 0XY, United Kingdom
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147
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Hsu H, Baldwin CL, Telfer JC. The Endocytosis and Signaling of the γδ T Cell Coreceptor WC1 Are Regulated by a Dileucine Motif. THE JOURNAL OF IMMUNOLOGY 2015; 194:2399-406. [DOI: 10.4049/jimmunol.1402020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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148
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Kaderi Kibria KM, Rawat K, Klinger CM, Datta G, Panchal M, Singh S, Iyer GR, Kaur I, Sharma V, Dacks JB, Mohmmed A, Malhotra P. A role for adaptor protein complex 1 in protein targeting to rhoptry organelles in Plasmodium falciparum. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:699-710. [PMID: 25573429 DOI: 10.1016/j.bbamcr.2014.12.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 12/12/2014] [Accepted: 12/25/2014] [Indexed: 12/20/2022]
Abstract
The human malaria parasite Plasmodium falciparum possesses sophisticated systems of protein secretion to modulate host cell invasion and remodeling. In the present study, we provide insights into the function of the AP-1 complex in P. falciparum. We utilized GFP fusion constructs for live cell imaging, as well as fixed parasites in immunofluorescence analysis, to study adaptor protein mu1 (Pfμ1) mediated protein trafficking in P. falciparum. In trophozoites Pfμ1 showed similar dynamic localization to that of several Golgi/ER markers, indicating Golgi/ER localization. Treatment of transgenic parasites with Brefeldin A altered the localization of Golgi-associated Pfμ1, supporting the localization studies. Co-localization studies showed considerable overlap of Pfμ1 with the resident rhoptry proteins, rhoptry associated protein 1 (RAP1) and Cytoadherence linked asexual gene 3.1 (Clag3.1) in schizont stage. Immunoprecipitation experiments with Pfμ1 and PfRAP1 revealed an interaction, which may be mediated through an intermediate transmembrane cargo receptor. A specific role for Pfμ1 in trafficking was suggested by treatment with AlF4, which resulted in a shift to a predominantly ER-associated compartment and consequent decrease in co-localization with the Golgi marker GRASP. Together, these results suggest a role for the AP-1 complex in rhoptry protein trafficking in P. falciparum.
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Affiliation(s)
- K M Kaderi Kibria
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Khushboo Rawat
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Christen M Klinger
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | - Gaurav Datta
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Manoj Panchal
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Shailja Singh
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Gayatri R Iyer
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Inderjeet Kaur
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India
| | - Veena Sharma
- Department of Bioscience and Biotechnology, Banasthali University, Banasthali-304022, Rajasthan, India
| | - Joel B Dacks
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada.
| | - Asif Mohmmed
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India.
| | - Pawan Malhotra
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India.
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149
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Raman D, Sai J, Hawkins O, Richmond A. Adaptor protein2 (AP2) orchestrates CXCR2-mediated cell migration. Traffic 2014; 15:451-69. [PMID: 24450359 DOI: 10.1111/tra.12154] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/16/2014] [Accepted: 01/22/2014] [Indexed: 12/14/2022]
Abstract
The chemokine receptor CXCR2 is vital for inflammation, wound healing, angiogenesis, cancer progression and metastasis. Adaptor protein 2 (AP2), a clathrin binding heterotetrameric protein comprised of α, β2, μ2 and σ2 subunits, facilitates clathrin-mediated endocytosis. Mutation of the LLKIL motif in the CXCR2 carboxyl-terminal domain (CTD) results in loss of AP2 binding to the receptor and loss of ligand-mediated receptor internalization and chemotaxis. AP2 knockdown also results in diminished ligand-mediated CXCR2 internalization, polarization and chemotaxis. Using knockdown/rescue approaches with AP2-μ2 mutants, the binding domains were characterized in reference to CXCR2 internalization and chemotaxis. When in an open conformation, μ2 Patch 1 and Patch 2 domains bind tightly to membrane PIP2 phospholipids. When AP2-μ2, is replaced with μ2 mutated in Patch 1 and/or Patch 2 domains, ligand-mediated receptor binding and internalization are not lost. However, chemotaxis requires AP2-μ2 Patch 1, but not Patch 2. AP2-σ2 has been demonstrated to bind dileucine motifs to facilitate internalization. Expression of AP2-σ2 V88D and V98S dominant negative mutants resulted in loss of CXCR2 mediated chemotaxis. Thus, AP2 binding to both membrane phosphatidylinositol phospholipids and dileucine motifs is crucial for directional migration or chemotaxis. Moreover, AP2-mediated receptor internalization can be dissociated from AP2-mediated chemotaxis.
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Affiliation(s)
- Dayanidhi Raman
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, 37212, USA; Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
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150
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Jain S, Farías GG, Bonifacino JS. Polarized sorting of the copper transporter ATP7B in neurons mediated by recognition of a dileucine signal by AP-1. Mol Biol Cell 2014; 26:218-28. [PMID: 25378584 PMCID: PMC4294670 DOI: 10.1091/mbc.e14-07-1177] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Recognition of dileucine signals by AP-1 mediates somatodendritic sorting of the copper transporter ATP7B and the SNARE VAMP4 in hippocampal neurons, establishing AP-1 as a global regulator of polarized sorting and contributing to the understanding of neuronal copper metabolism under physiological and pathological conditions. Neurons are highly polarized cells having distinct somatodendritic and axonal domains. Here we report that polarized sorting of the Cu2+ transporter ATP7B and the vesicle-SNARE VAMP4 to the somatodendritic domain of rat hippocampal neurons is mediated by recognition of dileucine-based signals in the cytosolic domains of the proteins by the σ1 subunit of the clathrin adaptor AP-1. Under basal Cu2+ conditions, ATP7B was localized to the trans-Golgi network (TGN) and the plasma membrane of the soma and dendrites but not the axon. Mutation of a dileucine-based signal in ATP7B or overexpression of a dominant-negative σ1 mutant resulted in nonpolarized distribution of ATP7B between the somatodendritic and axonal domains. Furthermore, addition of high Cu2+ concentrations, previously shown to reduce ATP7B incorporation into AP-1–containing clathrin-coated vesicles, caused loss of TGN localization and somatodendritic polarity of ATP7B. These findings support the notion of AP-1 as an effector of polarized sorting in neurons and suggest that altered polarity of ATP7B in polarized cell types might contribute to abnormal copper metabolism in the MEDNIK syndrome, a neurocutaneous disorder caused by mutations in the σ1A subunit isoform of AP-1.
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Affiliation(s)
- Shweta Jain
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Ginny G Farías
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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