101
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Kandachar V, Roegiers F. Endocytosis and control of Notch signaling. Curr Opin Cell Biol 2012; 24:534-40. [PMID: 22818956 DOI: 10.1016/j.ceb.2012.06.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 06/19/2012] [Accepted: 06/21/2012] [Indexed: 02/06/2023]
Abstract
The Notch signaling pathway controls patterning and cell fate decisions during development in metazoans, and is associated with human diseases such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and certain cancers. Studies over the last several years have revealed sophisticated regulation of both the membrane-bound Notch receptor and its ligands by vesicle trafficking. This is perhaps most evident in neural progenitor cells in Drosophila, which divide asymmetrically to segregate Numb, an endocytic adaptor protein that acts as a Notch pathway inhibitor, to one daughter cell. Here, we discuss recent findings addressing how receptor and ligand trafficking to specific membrane compartments control activation of the Notch pathway in asymmetrically dividing cells and other tissues.
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Affiliation(s)
- Vasundhara Kandachar
- Program in Cancer Biology, Fox Chase Cancer Center, Philadelphia, PA 19111, United States
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102
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Ferreira F, Foley M, Cooke A, Cunningham M, Smith G, Woolley R, Henderson G, Kelly E, Mundell S, Smythe E. Endocytosis of G protein-coupled receptors is regulated by clathrin light chain phosphorylation. Curr Biol 2012; 22:1361-70. [PMID: 22704991 DOI: 10.1016/j.cub.2012.05.034] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 03/16/2012] [Accepted: 05/16/2012] [Indexed: 11/15/2022]
Abstract
BACKGROUND Signaling by transmembrane receptors such as G protein-coupled receptors (GPCRs) occurs at the cell surface and throughout the endocytic pathway, and signaling from the cell surface may differ in magnitude and downstream output from intracellular signaling. As a result, the rate at which signaling molecules traverse the endocytic pathway makes a significant contribution to downstream output. Modulation of the core endocytic machinery facilitates differential uptake of individual cargoes. Clathrin-coated pits are a major entry portal where assembled clathrin forms a lattice around invaginating buds that have captured endocytic cargo. Clathrin assembles into triskelia composed of three clathrin heavy chains and associated clathrin light chains (CLCs). Despite the identification of clathrin-coated pits at the cell surface over 30 years ago, the functions of CLCs in endocytosis have been elusive. RESULTS In this work, we identify a novel role for CLCs in the regulated endocytosis of specific cargoes. Small interfering RNA-mediated knockdown of either CLCa or CLCb inhibits the uptake of GPCRs. Moreover, we demonstrate that phosphorylation of Ser204 in CLCb is required for efficient endocytosis of a subset of GPCRs and identify G protein-coupled receptor kinase 2 (GRK2) as a kinase that can phosphorylate CLCb on Ser204. Overexpression of CLCb(S204A) specifically inhibits the endocytosis of those GPCRs whose endocytosis is GRK2-dependent. CONCLUSIONS Together, these results indicate that CLCb phosphorylation acts as a discriminator for the endocytosis of specific GPCRs.
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Affiliation(s)
- Filipe Ferreira
- Department of Biomedical Science, Centre for Membrane Interactions and Dynamics, University of Sheffield, Sheffield S10 2TN, UK
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103
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Borner GHH, Antrobus R, Hirst J, Bhumbra GS, Kozik P, Jackson LP, Sahlender DA, Robinson MS. Multivariate proteomic profiling identifies novel accessory proteins of coated vesicles. ACTA ACUST UNITED AC 2012; 197:141-60. [PMID: 22472443 PMCID: PMC3317806 DOI: 10.1083/jcb.201111049] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A multivariate proteomics approach identified numerous new clathrin-coated vesicle proteins as well as the first AP-4 accessory protein, and also revealed how auxilin depletion causes mitotic arrest through sequestration of spindle proteins in clathrin cages. Despite recent advances in mass spectrometry, proteomic characterization of transport vesicles remains challenging. Here, we describe a multivariate proteomics approach to analyzing clathrin-coated vesicles (CCVs) from HeLa cells. siRNA knockdown of coat components and different fractionation protocols were used to obtain modified coated vesicle-enriched fractions, which were compared by stable isotope labeling of amino acids in cell culture (SILAC)-based quantitative mass spectrometry. 10 datasets were combined through principal component analysis into a “profiling” cluster analysis. Overall, 136 CCV-associated proteins were predicted, including 36 new proteins. The method identified >93% of established CCV coat proteins and assigned >91% correctly to intracellular or endocytic CCVs. Furthermore, the profiling analysis extends to less well characterized types of coated vesicles, and we identify and characterize the first AP-4 accessory protein, which we have named tepsin. Finally, our data explain how sequestration of TACC3 in cytosolic clathrin cages causes the severe mitotic defects observed in auxilin-depleted cells. The profiling approach can be adapted to address related cell and systems biological questions.
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Affiliation(s)
- Georg H H Borner
- Cambridge Institute for Medical Research, Wellcome Trust/Medical Research Council Building, University of Cambridge, Cambridge CB2 0XY, England, UK.
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104
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Usenovic M, Knight AL, Ray A, Wong V, Brown KR, Caldwell GA, Caldwell KA, Stagljar I, Krainc D. Identification of novel ATP13A2 interactors and their role in α-synuclein misfolding and toxicity. Hum Mol Genet 2012; 21:3785-94. [PMID: 22645275 DOI: 10.1093/hmg/dds206] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Lysosomes are responsible for degradation and recycling of bulky cell material, including accumulated misfolded proteins and dysfunctional organelles. Increasing evidence implicates lysosomal dysfunction in several neurodegenerative disorders, including Parkinson's disease and related synucleinopathies, which are characterized by the accumulation of α-synuclein (α-syn) in Lewy bodies. Studies of lysosomal proteins linked to neurodegenerative disorders present an opportunity to uncover specific molecular mechanisms and pathways that contribute to neurodegeneration. Loss-of-function mutations in a lysosomal protein, ATP13A2 (PARK9), cause Kufor-Rakeb syndrome that is characterized by early-onset parkinsonism, pyramidal degeneration and dementia. While loss of ATP13A2 function plays a role in α-syn misfolding and toxicity, the normal function of ATP13A2 in the brain remains largely unknown. Here, we performed a screen to identify ATP13A2 interacting partners, as a first step toward elucidating its function. Utilizing a split-ubiquitin membrane yeast two-hybrid system that was developed to identify interacting partners of full-length integral membrane proteins, we identified 43 novel interactors that primarily implicate ATP13A2 in cellular processes such as endoplasmic reticulum (ER) translocation, ER-to-Golgi trafficking and vesicular transport and fusion. We showed that a subset of these interactors modified α-syn aggregation and α-syn-mediated degeneration of dopaminergic neurons in Caenorhabditis elegans, further suggesting that ATP13A2 and α-syn are functionally linked in neurodegeneration. These results implicate ATP13A2 in vesicular trafficking and provide a platform for further studies of ATP13A2 in neurodegeneration.
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Affiliation(s)
- Marija Usenovic
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, MassGeneral Institute for Neurodegenerative Disease, Charlestown, MA 02129, USA
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105
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A deleterious mutation in DNAJC6 encoding the neuronal-specific clathrin-uncoating co-chaperone auxilin, is associated with juvenile parkinsonism. PLoS One 2012; 7:e36458. [PMID: 22563501 PMCID: PMC3341348 DOI: 10.1371/journal.pone.0036458] [Citation(s) in RCA: 223] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 04/07/2012] [Indexed: 01/21/2023] Open
Abstract
Parkinson disease is caused by neuronal loss in the substantia nigra which manifests by abnormality of movement, muscle tone, and postural stability. Several genes have been implicated in the pathogenesis of Parkinson disease, but the underlying molecular basis is still unknown for ∼70% of the patients. Using homozygosity mapping and whole exome sequencing we identified a deleterious mutation in DNAJC6 in two patients with juvenile Parkinsonism. The mutation was associated with abnormal transcripts and marked reduced DNAJC6 mRNA level. DNAJC6 encodes the HSP40 Auxilin, a protein which is selectively expressed in neurons and confers specificity to the ATPase activity of its partner Hcs70 in clathrin uncoating. In Auxilin null mice it was previously shown that the abnormally increased retention of assembled clathrin on vesicles and in empty cages leads to impaired synaptic vesicle recycling and perturbed clathrin mediated endocytosis. Endocytosis function, studied by transferring uptake, was normal in fibroblasts from our patients, likely because of the presence of another J-domain containing partner which co-chaperones Hsc70-mediated uncoating activity in non-neuronal cells. The present report underscores the importance of the endocytic/lysosomal pathway in the pathogenesis of Parkinson disease and other forms of Parkinsonism.
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106
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Scott H, Howarth J, Lee YB, Wong LF, Bantounas I, Phylactou L, Verkade P, Uney JB. MiR-3120 is a mirror microRNA that targets heat shock cognate protein 70 and auxilin messenger RNAs and regulates clathrin vesicle uncoating. J Biol Chem 2012; 287:14726-33. [PMID: 22393045 PMCID: PMC3340243 DOI: 10.1074/jbc.m111.326041] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/28/2012] [Indexed: 12/27/2022] Open
Abstract
We show that a single gene locus gives rise to two fully processed and functional miRNAs, i.e. that due to imperfect base pairing, two distinct microRNAs (miRNAs) can be produced from the fully complementary DNA strands. The antisense strand encodes miR-214, which is transcribed by its own promoter, whereas a novel miRNA, miR-3120, is co-expressed with its host gene mRNA. We also found that miR-3120 regulates important aspects of cellular function that are similar to that of its host gene, dynamin-3. miR-3120 was found to be located in neuronal cell bodies and to target Hsc70 and auxilin, and its lentivirus-mediated expression inhibited the uncoating of clathrin-coated vesicles. Finally, mirror miRNAs are likely to represent a new group of miRNAs with complex roles in coordinating gene expression.
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Affiliation(s)
- Helen Scott
- From the Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY
| | - Joanna Howarth
- From the Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY
| | - Youn Bok Lee
- the Medical Research Council (MRC) Centre for Neurodegeneration Research, Institute of Psychiatry, King's College London, London SE5 8AF
| | - Liang-Fong Wong
- From the Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY
| | - Ioannis Bantounas
- the Faculty of Life Sciences, University of Manchester, Michael Smith Building, Manchester M13 9PL
| | - Leonidas Phylactou
- the Department of Molecular Genetics Function and Therapy, The Cyprus Institute of Neurology and Genetics, 1683 Nicosia, Cyprus, and
| | - Paul Verkade
- the Schools of Biochemistry and Physiology and Pharmacology, University of Bristol, Wolfson Bioimaging Facility, Medical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - James. B. Uney
- From the Henry Wellcome Laboratories for Integrated Neuroscience and Endocrinology, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY
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107
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Murakami N, Bolton DC, Kida E, Xie W, Hwang YW. Phosphorylation by Dyrk1A of clathrin coated vesicle-associated proteins: identification of the substrate proteins and the effects of phosphorylation. PLoS One 2012; 7:e34845. [PMID: 22514676 PMCID: PMC3325943 DOI: 10.1371/journal.pone.0034845] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 03/08/2012] [Indexed: 11/26/2022] Open
Abstract
Dyrk1A phosphorylated multiple proteins in the clathrin-coated vesicle (CCV) preparations obtained from rat brains. Mass spectrometric analysis identified MAP1A, MAP2, AP180, and α- and β-adaptins as the phosphorylated proteins in the CCVs. Each protein was subsequently confirmed by [(32)P]-labeling and immunological methods. The Dyrk1A-mediated phosphorylation released the majority of MAP1A and MAP2 and enhanced the release of AP180 and adaptin subunits from the CCVs. Furthermore, Dyrk1A displaced adaptor proteins physically from CCVs in a kinase-concentration dependent manner. The clathrin heavy chain release rate, in contrast, was not affected by Dyrk1A. Surprisingly, the Dyrk1A-mediated phosphorylation of α- and β-adaptins led to dissociation of the AP2 complex, and released only β-adaptin from the CCVs. AP180 was phosphorylated by Dyrk1A also in the membrane-free fractions, but α- and β-adaptins were not. Dyrk1A was detected in the isolated CCVs and was co-localized with clathrin in neurons from mouse brain sections and from primary cultured rat hippocampus. Previously, we proposed that Dyrk1A inhibits the onset of clathrin-mediated endocytosis in neurons by phosphorylating dynamin 1, amphiphysin 1, and synaptojanin 1. Current results suggest that besides the inhibition, Dyrk1A promotes the uncoating process of endocytosed CCVs.
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Affiliation(s)
- Noriko Murakami
- Laboratory of Molecular Regulation, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America. . gov
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108
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Motorneurons Require Cysteine String Protein-α to Maintain the Readily Releasable Vesicular Pool and Synaptic Vesicle Recycling. Neuron 2012; 74:151-65. [DOI: 10.1016/j.neuron.2012.02.019] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2012] [Indexed: 11/22/2022]
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109
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Lemmon SK, Traub LM. Getting in touch with the clathrin terminal domain. Traffic 2012; 13:511-9. [PMID: 22239657 DOI: 10.1111/j.1600-0854.2011.01321.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 12/14/2011] [Indexed: 12/16/2022]
Abstract
The N-terminal domain (TD) of the clathrin heavy chain is folded into a seven-bladed β-propeller that projects inward from the polyhedral outer clathrin coat. As the most membrane-proximal portion of assembled clathrin, the TD is a major protein-protein interaction node. Contact with the TD β-propeller occurs through short peptide sequences typically located within intrinsically disordered segments of coat components that usually are elements of the membrane-apposed, inner 'adaptor' coat layer. A huge variation in TD-binding motifs is known and now four spatially discrete interaction surfaces upon the β-propeller have been delineated. An important operational feature of the TD interaction sites in vivo is functional redundancy. The recent discovery that 'pitstop' chemical inhibitors apparently occupy only one of the four TD interaction surfaces, but potently block clathrin-mediated endocytosis, warrants careful consideration of the underlying molecular basis for this inhibition.
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Affiliation(s)
- Sandra K Lemmon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33101, USA.
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110
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König S, Nimtz M, Scheiter M, Ljunggren HG, Bryceson YT, Jänsch L. Kinome analysis of receptor-induced phosphorylation in human natural killer cells. PLoS One 2012; 7:e29672. [PMID: 22238634 PMCID: PMC3251586 DOI: 10.1371/journal.pone.0029672] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 12/01/2011] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Natural killer (NK) cells contribute to the defense against infected and transformed cells through the engagement of multiple germline-encoded activation receptors. Stimulation of the Fc receptor CD16 alone is sufficient for NK cell activation, whereas other receptors, such as 2B4 (CD244) and DNAM-1 (CD226), act synergistically. After receptor engagement, protein kinases play a major role in signaling networks controlling NK cell effector functions. However, it has not been characterized systematically which of all kinases encoded by the human genome (kinome) are involved in NK cell activation. RESULTS A kinase-selective phosphoproteome approach enabled the determination of 188 kinases expressed in human NK cells. Crosslinking of CD16 as well as 2B4 and DNAM-1 revealed a total of 313 distinct kinase phosphorylation sites on 109 different kinases. Phosphorylation sites on 21 kinases were similarly regulated after engagement of either CD16 or co-engagement of 2B4 and DNAM-1. Among those, increased phosphorylation of FYN, KCC2G (CAMK2), FES, and AAK1, as well as the reduced phosphorylation of MARK2, were reproducibly observed both after engagement of CD16 and co-engagement of 2B4 and DNAM-1. Notably, only one phosphorylation on PAK4 was differentally regulated. CONCLUSIONS The present study has identified a significant portion of the NK cell kinome and defined novel phosphorylation sites in primary lymphocytes. Regulated phosphorylations observed in the early phase of NK cell activation imply these kinases are involved in NK cell signaling. Taken together, this study suggests a largely shared signaling pathway downstream of distinct activation receptors and constitutes a valuable resource for further elucidating the regulation of NK cell effector responses.
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Affiliation(s)
- Sebastian König
- Department of Molecular Structural Biology, Helmholtz-Zentrum für Infektionsforschung, Braunschweig, Germany
| | - Manfred Nimtz
- Department of Molecular Structural Biology, Helmholtz-Zentrum für Infektionsforschung, Braunschweig, Germany
| | - Maxi Scheiter
- Department of Molecular Structural Biology, Helmholtz-Zentrum für Infektionsforschung, Braunschweig, Germany
| | - Hans-Gustaf Ljunggren
- Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Yenan T. Bryceson
- Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Lothar Jänsch
- Department of Molecular Structural Biology, Helmholtz-Zentrum für Infektionsforschung, Braunschweig, Germany
- * E-mail:
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111
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Abstract
Synaptic transmission is amongst the most sophisticated and tightly controlled biological phenomena in higher eukaryotes. In the past few decades, tremendous progress has been made in our understanding of the molecular mechanisms underlying multiple facets of neurotransmission, both pre- and postsynaptically. Brought under the spotlight by pioneer studies in the areas of secretion and signal transduction, phosphoinositides and their metabolizing enzymes have been increasingly recognized as key protagonists in fundamental aspects of neurotransmission. Not surprisingly, dysregulation of phosphoinositide metabolism has also been implicated in synaptic malfunction associated with a variety of brain disorders. In the present chapter, we summarize current knowledge on the role of phosphoinositides at the neuronal synapse and highlight some of the outstanding questions in this research field.
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Affiliation(s)
- Samuel G Frere
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, 630 West 168th Street, P&S 12-420C, 10032, New York, USA
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112
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Nak regulates localization of clathrin sites in higher-order dendrites to promote local dendrite growth. Neuron 2011; 72:285-99. [PMID: 22017988 DOI: 10.1016/j.neuron.2011.08.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2011] [Indexed: 11/22/2022]
Abstract
VIDEO ABSTRACT During development, dendrites arborize in a field several hundred folds of their soma size, a process regulated by intrinsic transcription program and cell adhesion molecule (CAM)-mediated interaction. However, underlying cellular machineries that govern distal higher-order dendrite extension remain largely unknown. Here, we show that Nak, a clathrin adaptor-associated kinase, promotes higher-order dendrite growth through endocytosis. In nak mutants, both the number and length of higher-order dendrites are reduced, which are phenocopied by disruptions of clathrin-mediated endocytosis. Nak interacts genetically with components of the endocytic pathway, colocalizes with clathrin puncta, and is required for dendritic localization of clathrin puncta. More importantly, these Nak-containing clathrin structures preferentially localize to branching points and dendritic tips that are undergoing active growth. We present evidence that the Drosophila L1-CAM homolog Neuroglian is a relevant cargo of Nak-dependent internalization, suggesting that localized clathrin-mediated endocytosis of CAMs facilitates the extension of nearby higher-order dendrites.
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113
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Tabara H, Naito Y, Ito A, Katsuma A, Sakurai MA, Ohno S, Shimizu H, Yabuta N, Nojima H. Neonatal lethality in knockout mice expressing the kinase-dead form of the gefitinib target GAK is caused by pulmonary dysfunction. PLoS One 2011; 6:e26034. [PMID: 22022498 PMCID: PMC3192135 DOI: 10.1371/journal.pone.0026034] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 09/16/2011] [Indexed: 11/18/2022] Open
Abstract
Gefitinib (Iressa) is an inhibitor of the epidermal growth factor receptor (EGFR) that has shown promising activity in the treatment of patients with non-small cell lung cancer (NSCLC). However, adverse side effects of gefitinib treatment, such as respiratory dysfunction, have limited the therapeutic benefit of this targeting strategy. The present results show that this adverse effect can be attributed to the inhibition of the novel gefitinib target GAK (Cyclin G-associated kinase), which is as potently inhibited by the drug as the tyrosine kinase activity of EGFR. Knockout mice expressing the kinase-dead form of GAK (GAK-kd) died within 30 min after birth primarily due to respiratory dysfunction. Immunohistochemical analysis revealed that surfactant protein A (SP-A) was abundant within alveolar spaces in GAK-kd(+/+) mice but not in GAK-kd(-/-) pups. E-cadherin and phosphorylated EGFR signals were also abnormal, suggesting the presence of flat alveolar cells with thin junctions. These results suggest that inhibition of GAK by gefitinib may cause pulmonary alveolar dysfunction, and the present study may help prevent side effects associated with gefitinib therapy in NSCLC patients.
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Affiliation(s)
- Hiroe Tabara
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yoko Naito
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Akihiko Ito
- Department of Pathology, Kinki University Faculty of Medicine, Osaka, Japan
| | - Asako Katsuma
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Minami A. Sakurai
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Shouichi Ohno
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Hiroyuki Shimizu
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Norikazu Yabuta
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Hiroshi Nojima
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- * E-mail:
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114
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Abstract
TPR-containing Rab8b-interacting protein (TRIP8b) is a brain-specific hydrophilic cytosolic protein that contains tetratricopeptide repeats (TPRs). Previous studies revealed interaction of this protein via its TPR-containing domain with Rab8b small GTPase, hyperpolarization-activated cyclic nucleotide-regulated channel (HCN) channels and G protein-coupled receptor calcium-independent receptor of α-latrotoxin. We identified clathrin as a major component of eluates from the TRIP8b affinity matrix. In the present study, by in vitro-binding analysis we demonstrate a direct interaction between clathrin and TRIP8b. The clathrin-binding site was localized in the N-terminal (non-TPR containing) part of the TRIP8b molecule that contains two short motifs involved in the clathrin binding. In transfected HEK293 cells, co-expression of HCN1 with TRIP8b resulted in translocation of the channels from the cell surface to large intracellular puncta where both TRIP8b and clathrin were concentrated. These puncta co-localized partially with an early endosome marker and strongly overlapped with lysosome staining reagent. When HCN1 was co-expressed with a clathrin-non-binding mutant of TRIP8b, clathrin did not translocate to HCN1 and TRIP8b-containing puncta, suggesting that TRIP8b interacts with HCN and clathrin independently. We found TRIP8b present in the fraction of clathrin-coated vesicles purified from brain tissues. Stripping the clathrin coat proteins from the vesicles with Tris alkaline buffer resulted in concomitant release of TRIP8b. Our data suggest complex regulatory functions of TRIP8b in neuronal endocytosis through independent interaction with membrane proteins and components of the clathrin coat.
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Affiliation(s)
- Nadezhda V Popova
- Laboratory of Receptor Cell Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, 117997 Moscow, Russia
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115
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Ramanan V, Agrawal NJ, Liu J, Engles S, Toy R, Radhakrishnan R. Systems biology and physical biology of clathrin-mediated endocytosis. Integr Biol (Camb) 2011; 3:803-15. [PMID: 21792431 PMCID: PMC3153420 DOI: 10.1039/c1ib00036e] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In this review, we describe the application of experimental data and modeling of intracellular endocytic trafficking mechanisms with a focus on the process of clathrin-mediated endocytosis. A detailed parts-list for the protein-protein interactions in clathrin-mediated endocytosis has been available for some time. However, recent experimental, theoretical, and computational tools have proved to be critical in establishing a sequence of events, cooperative dynamics, and energetics of the intracellular process. On the experimental front, total internal reflection fluorescence microscopy, photo-activated localization microscopy, and spinning-disk confocal microscopy have focused on assembly and patterning of endocytic proteins at the membrane, while on the theory front, minimal theoretical models for clathrin nucleation, biophysical models for membrane curvature and bending elasticity, as well as methods from computational structural and systems biology, have proved insightful in describing membrane topologies, curvature mechanisms, and energetics.
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Affiliation(s)
- Vyas Ramanan
- Department of Bioengineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
| | - Neeraj J. Agrawal
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
| | - Jin Liu
- Department of Bioengineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
| | - Sean Engles
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
| | - Randall Toy
- Department of Bioengineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
| | - Ravi Radhakrishnan
- Department of Bioengineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 210 South 33rd Street, Philadelphia, PA 19104, USA
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116
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Mattheyses AL, Atkinson CE, Simon SM. Imaging single endocytic events reveals diversity in clathrin, dynamin and vesicle dynamics. Traffic 2011; 12:1394-406. [PMID: 21689254 DOI: 10.1111/j.1600-0854.2011.01235.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The dynamics of clathrin-mediated endocytosis can be assayed using fluorescently tagged proteins and total internal reflection fluorescence microscopy. Many of these proteins, including clathrin and dynamin, are soluble and changes in fluorescence intensity can be attributed either to membrane/vesicle movement or to changes in the numbers of individual molecules. It is important for assays to discriminate between physical membrane events and the dynamics of molecules. Two physical events in endocytosis were investigated: vesicle scission from the plasma membrane and vesicle internalization. Single vesicle analysis allowed the characterization of dynamin and clathrin dynamics relative to scission and internalization. We show that vesicles remain proximal to the plasma membrane for variable amounts of time following scission, and that uncoating of clathrin can occur before or after vesicle internalization. The dynamics of dynamin also vary with respect to scission. Results from assays based on physical events suggest that disappearance of fluorescence from the evanescent field should be re-evaluated as an assay for endocytosis. These results illustrate the heterogeneity of behaviors of endocytic vesicles and the importance of establishing suitable evaluation criteria for biophysical processes.
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Affiliation(s)
- Alexa L Mattheyses
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, NY 10065, USA
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Kabani M, Martineau CN. Multiple hsp70 isoforms in the eukaryotic cytosol: mere redundancy or functional specificity? Curr Genomics 2011; 9:338-248. [PMID: 19471609 PMCID: PMC2685646 DOI: 10.2174/138920208785133280] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 05/15/2008] [Accepted: 05/19/2008] [Indexed: 12/30/2022] Open
Abstract
Hsp70 molecular chaperones play a variety of functions in every organism, cell type and organelle, and their activities have been implicated in a number of human pathologies, ranging from cancer to neurodegenerative diseases. The functions, regulations and structure of Hsp70s were intensively studied for about three decades, yet much still remains to be learned about these essential folding enzymes. Genome sequencing efforts revealed that most genomes contain multiple members of the Hsp70 family, some of which co-exist in the same cellular compartment. For example, the human cytosol and nucleus contain six highly homologous Hsp70 proteins while the yeast Saccharomyces cerevisiae contains four canonical Hsp70s and three fungal-specific ribosome-associated and specialized Hsp70s. The reasons and significance of the requirement for multiple Hsp70s is still a subject of debate. It has been postulated for a long time that these Hsp70 isoforms are functionally redundant and differ only by their spatio-temporal expression patterns. However, several studies in yeast and higher eukaryotic organisms challenged this widely accepted idea by demonstrating functional specificity among Hsp70 isoforms. Another element of complexity is brought about by specific cofactors, such as Hsp40s or nucleotide exchange factors that modulate the activity of Hsp70s and their binding to client proteins. Hence, a dynamic network of chaperone/co-chaperone interactions has evolved in each organism to efficiently take advantage of the multiple cellular roles Hsp70s can play. We summarize here our current knowledge of the functions and regulations of these molecular chaperones, and shed light on the known functional specificities among isoforms.
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Affiliation(s)
- Mehdi Kabani
- Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Bât. 34, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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Matsumura Y, David LL, Skach WR. Role of Hsc70 binding cycle in CFTR folding and endoplasmic reticulum-associated degradation. Mol Biol Cell 2011; 22:2797-809. [PMID: 21697503 PMCID: PMC3154877 DOI: 10.1091/mbc.e11-02-0137] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Hsc70 plays a productive role during cotranslational cystic fibrosis transmembrane conductance regulator folding that is outweighed by its dominant contribution to posttranslational targeting to the ubiquitin-proteasome system. Moreover, the outcome of Hsc70 binding appears highly sensitive to the duration of its binding cycle, which is governed by regulatory cochaperones. The Hsp/c70 cytosolic chaperone system facilitates competing pathways of protein folding and degradation. Here we use a reconstituted cell-free system to investigate the mechanism and extent to which Hsc70 contributes to these co- and posttranslational decisions for the membrane protein cystic fibrosis transmembrane conductance regulator (CFTR). Hsc70 binding to CFTR was destabilized by the C-terminal domain of Bag-1 (CBag), which stimulates client release by accelerating ADP-ATP exchange. Addition of CBag during CFTR translation slightly increased susceptibility of the newly synthesized protein to degradation, consistent with a profolding function for Hsc70. In contrast, posttranslational destabilization of Hsc70 binding nearly completely blocked CFTR ubiquitination, dislocation from the endoplasmic reticulum, and proteasome-mediated cleavage. This effect required molar excess of CBag relative to Hsc70 and was completely reversed by the CBag-binding subdomain of Hsc70. These results demonstrate that the profolding role of Hsc70 during cotranslational CFTR folding is counterbalanced by a dominant and essential role in posttranslational targeting to the ubiquitin-proteasome system. Moreover, the degradative outcome of Hsc70 binding appears highly sensitive to the duration of its binding cycle, which is in turn governed by the integrated expression of regulatory cochaperones.
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Affiliation(s)
- Yoshihiro Matsumura
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, OR 97239, USA
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119
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Abstract
Cysteine-string protein (CSP), a member of the DnaJ/Hsp40 family of cochaperones, is critical for maintaining neurotransmitter release and preventing neurodegeneration. CSP likely forms a chaperone complex on synaptic vesicles together with the 70-kDa heat shock cognate (Hsc70) and the small glutamine-rich tetratricopeptide repeat (TPR)-containing protein (SGT) that may control or protect the assembly and activity of SNARE proteins and various other protein substrates. Here, the author summarizes studies that elucidated CSP's neuroprotective role.
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Affiliation(s)
- Konrad E Zinsmaier
- Department of Neuroscience and Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721-0077, USA.
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120
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Recovery from Retinal Lesions: Molecular Plasticity Mechanisms in Visual Cortex Far beyond the Deprived Zone. Cereb Cortex 2011; 21:2883-92. [DOI: 10.1093/cercor/bhr079] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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121
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A sequential mechanism for clathrin cage disassembly by 70-kDa heat-shock cognate protein (Hsc70) and auxilin. Proc Natl Acad Sci U S A 2011; 108:6927-32. [PMID: 21482805 DOI: 10.1073/pnas.1018845108] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An essential stage in endocytic coated vesicle recycling is the dissociation of clathrin from the vesicle coat by the molecular chaperone, 70-kDa heat-shock cognate protein (Hsc70), and the J-domain-containing protein, auxilin, in an ATP-dependent process. We present a detailed mechanistic analysis of clathrin disassembly catalyzed by Hsc70 and auxilin, using loss of perpendicular light scattering to monitor the process. We report that a single auxilin per clathrin triskelion is required for maximal rate of disassembly, that ATP is hydrolyzed at the same rate that disassembly occurs, and that three ATP molecules are hydrolyzed per clathrin triskelion released. Stopped-flow measurements revealed a lag phase in which the scattering intensity increased owing to association of Hsc70 with clathrin cages followed by serial rounds of ATP hydrolysis prior to triskelion removal. Global fit of stopped-flow data to several physically plausible mechanisms showed the best fit to a model in which sequential hydrolysis of three separate ATP molecules is required for the eventual release of a triskelion from the clathrin-auxilin cage.
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Banks SML, Cho B, Eun SH, Lee JH, Windler SL, Xie X, Bilder D, Fischer JA. The functions of auxilin and Rab11 in Drosophila suggest that the fundamental role of ligand endocytosis in notch signaling cells is not recycling. PLoS One 2011; 6:e18259. [PMID: 21448287 PMCID: PMC3063240 DOI: 10.1371/journal.pone.0018259] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 02/23/2011] [Indexed: 12/03/2022] Open
Abstract
Notch signaling requires ligand internalization by the signal sending cells. Two endocytic proteins, epsin and auxilin, are essential for ligand internalization and signaling. Epsin promotes clathrin-coated vesicle formation, and auxilin uncoats clathrin from newly internalized vesicles. Two hypotheses have been advanced to explain the requirement for ligand endocytosis. One idea is that after ligand/receptor binding, ligand endocytosis leads to receptor activation by pulling on the receptor, which either exposes a cleavage site on the extracellular domain, or dissociates two receptor subunits. Alternatively, ligand internalization prior to receptor binding, followed by trafficking through an endosomal pathway and recycling to the plasma membrane may enable ligand activation. Activation could mean ligand modification or ligand transcytosis to a membrane environment conducive to signaling. A key piece of evidence supporting the recycling model is the requirement in signaling cells for Rab11, which encodes a GTPase critical for endosomal recycling. Here, we use Drosophila Rab11 and auxilin mutants to test the ligand recycling hypothesis. First, we find that Rab11 is dispensable for several Notch signaling events in the eye disc. Second, we find that Drosophila female germline cells, the one cell type known to signal without clathrin, also do not require auxilin to signal. Third, we find that much of the requirement for auxilin in Notch signaling was bypassed by overexpression of both clathrin heavy chain and epsin. Thus, the main role of auxilin in Notch signaling is not to produce uncoated ligand-containing vesicles, but to maintain the pool of free clathrin. Taken together, these results argue strongly that at least in some cell types, the primary function of Notch ligand endocytosis is not for ligand recycling.
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Affiliation(s)
- Susan M. L. Banks
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Bomsoo Cho
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Suk Ho Eun
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Ji-Hoon Lee
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Sarah L. Windler
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Xuanhua Xie
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Janice A. Fischer
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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Shriner D, Vaughan LK. A unified framework for multi-locus association analysis of both common and rare variants. BMC Genomics 2011; 12:89. [PMID: 21281506 PMCID: PMC3040731 DOI: 10.1186/1471-2164-12-89] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 01/31/2011] [Indexed: 11/10/2022] Open
Abstract
Background Common, complex diseases are hypothesized to result from a combination of common and rare genetic variants. We developed a unified framework for the joint association testing of both types of variants. Within the framework, we developed a union-intersection test suitable for genome-wide analysis of single nucleotide polymorphisms (SNPs), candidate gene data, as well as medical sequencing data. The union-intersection test is a composite test of association of genotype frequencies and differential correlation among markers. Results We demonstrated by computer simulation that the false positive error rate was controlled at the expected level. We also demonstrated scenarios in which the multi-locus test was more powerful than traditional single marker analysis. To illustrate use of the union-intersection test with real data, we analyzed a publically available data set of 319,813 autosomal SNPs genotyped for 938 cases of Parkinson disease and 863 neurologically normal controls for which no genome-wide significant results were found by traditional single marker analysis. We also analyzed an independent follow-up sample of 183 cases and 248 controls for replication. Conclusions We identified a single risk haplotype with a directionally consistent effect in both samples in the gene GAK, which is involved in clathrin-mediated membrane trafficking. We also found suggestive evidence that directionally inconsistent marginal effects from single marker analysis appeared to result from risk being driven by different haplotypes in the two samples for the genes SYN3 and NGLY1, which are involved in neurotransmitter release and proteasomal degradation, respectively. These results illustrate the utility of our unified framework for genome-wide association analysis of common, complex diseases.
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Affiliation(s)
- Daniel Shriner
- Center for Research on Genomics and Global Health, National Human Genome Research Institute, Bethesda, MD 20892, USA.
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Hurley JH, Boura E, Carlson LA, Różycki B. Membrane budding. Cell 2010; 143:875-87. [PMID: 21145455 PMCID: PMC3102176 DOI: 10.1016/j.cell.2010.11.030] [Citation(s) in RCA: 205] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 08/27/2010] [Accepted: 11/17/2010] [Indexed: 01/06/2023]
Abstract
Membrane budding is a key step in vesicular transport, multivesicular body biogenesis, and enveloped virus release. These events range from those that are primarily protein driven, such as the formation of coated vesicles, to those that are primarily lipid driven, such as microdomain-dependent biogenesis of multivesicular bodies. Other types of budding reside in the middle of this spectrum, including caveolae biogenesis, HIV-1 budding, and ESCRT-catalyzed multivesicular body formation. Some of these latter events involve budding away from cytosol, and this unusual topology involves unique mechanisms. This Review discusses progress toward understanding the structural and energetic bases of these different membrane-budding paradigms.
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Affiliation(s)
- James H Hurley
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0580, USA.
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125
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Suetsugu N, Takano A, Kohda D, Wada M. Structure and activity of JAC1 J-domain implicate the involvement of the cochaperone activity with HSC70 in chloroplast photorelocation movement. PLANT SIGNALING & BEHAVIOR 2010; 5:1602-6. [PMID: 21139434 PMCID: PMC3115112 DOI: 10.4161/psb.5.12.13915] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 10/11/2010] [Indexed: 05/20/2023]
Abstract
Chloroplast photorelocation movement towards weak light and away from strong light is essential for plants to adapt to the fluctuation of ambient light conditions. In the previous study, we showed that blue light receptor phototropins mediated blue light-induced chloroplast movement in Arabidopsis by regulating short actin filaments localized at the chloroplast periphery (cp-actin filaments) rather than actin cables in the cytoplasm. However, the signaling pathway for the chloroplast photorelocation movement is still unclear. We also identified JAC1 (J-domain protein required for chloroplast accumulation response 1) as an essential component for the accumulation response and dark positioning in Arabidopsis. We recently determined the crystal structure of the J-domain of JAC1. The JAC1 J-domain has a positively charged surface, which forms a putative interface with the Hsc70 chaperone by analogy to that of bovine auxilin. Furthermore, the mutation of the highly conserved HPD motif in the JAC1 J-domain impaired the in vivo activity of JAC1. These data suggest that JAC1 cochaperone activity with HSC70 is essential for chloroplast photorelocation movement.
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Affiliation(s)
- Noriyuki Suetsugu
- Department of Biology; Faculty of Sciences; Kyushu University; Fukuoka, Japan
| | - Akira Takano
- Division of Structural Biology; Medical Institute of Bioregulation; Kyushu University; Fukuoka, Japan
| | - Daisuke Kohda
- Division of Structural Biology; Medical Institute of Bioregulation; Kyushu University; Fukuoka, Japan
| | - Masamitsu Wada
- Department of Biology; Faculty of Sciences; Kyushu University; Fukuoka, Japan
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126
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Royle SJ, Lagnado L. Clathrin-mediated endocytosis at the synaptic terminal: bridging the gap between physiology and molecules. Traffic 2010; 11:1489-97. [PMID: 20633242 PMCID: PMC3371399 DOI: 10.1111/j.1600-0854.2010.01104.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
It has long been known that the maintenance of fast communication between neurons requires that presynaptic terminals recycle the small vesicles from which neurotransmitter is released. But the mechanisms that retrieve vesicles from the cell surface are still not understood. Although we have a wealth of information about the molecular details of endocytosis in non-neuronal cells, it is clear that endocytosis at the synapse is faster and regulated in distinct ways. A satisfying understanding of these processes will require molecular events to be manipulated while observing endocytosis in living synapses. Here, we review recent work that seeks to bridge the gap between physiology and molecules to unravel the endocytic machinery operating at the synaptic terminal.
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Affiliation(s)
- Stephen J Royle
- Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
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127
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Takeda H, Kawamura Y, Miura A, Mori M, Wakamatsu A, Yamamoto JI, Isogai T, Matsumoto M, Nakayama KI, Natsume T, Nomura N, Goshima N. Comparative Analysis of Human Src-Family Kinase Substrate Specificity in Vitro. J Proteome Res 2010; 9:5982-93. [DOI: 10.1021/pr100773t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Hiroyuki Takeda
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Yoshifumi Kawamura
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Aya Miura
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Masatoshi Mori
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Ai Wakamatsu
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Jun-ichi Yamamoto
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Takao Isogai
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Masaki Matsumoto
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Keiichi I. Nakayama
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Tohru Natsume
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Nobuo Nomura
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
| | - Naoki Goshima
- Japan Biological Informatics Consortium, TIME24 Building 10F 2-4-32 Aomi, Koto-ku, Tokyo 135-8073, Japan, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Reverse Proteomics Research Institute, 1-9-11 Kaji, Chiyoda-ku, Tokyo 101-0044, Japan, Medical Institute of Bioregulation, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan, and National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135
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128
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Johnson JN, Ahrendt E, Braun JEA. CSPalpha: the neuroprotective J protein. Biochem Cell Biol 2010; 88:157-65. [PMID: 20453918 DOI: 10.1139/o09-124] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cysteine string protein (CSPalpha, also called DnaJC5) is unique among J proteins. Similar to other J proteins, CSPalpha interacts with and activates the ATPase of Hsc70s (heat shock proteins of 70 kDa), thereby harnessing the ATPase activity for conformational work on client proteins. In contrast to other J proteins, CSPalpha is anchored to synaptic vesicles, as well as to exocrine, endocrine and neuroendocrine secretory granules, and has been shown to have an essential anti-neurodegenerative role. CSPalpha-null organisms exhibit progressive neurodegeneration, behavioural deficits, and premature death, most likely due to the progressive misfolding of one or more client proteins. Here we highlight recent advances in our understanding of the critical role that CSPalpha plays in governing exocytotic secretory functions.
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Affiliation(s)
- Jadah N Johnson
- Department of Physiology and Pharmacology and the Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
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129
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Vega VL, Charles W, De Maio A. A new feature of the stress response: increase in endocytosis mediated by Hsp70. Cell Stress Chaperones 2010; 15:517-27. [PMID: 20043217 PMCID: PMC3006637 DOI: 10.1007/s12192-009-0165-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 11/19/2009] [Accepted: 11/23/2009] [Indexed: 11/26/2022] Open
Abstract
The expression of heat shock proteins (HSP) is a conserved cellular response to a variety of stresses. These proteins have been found to refold denatured polypeptides and stabilize critical cellular processes. In this study, we introduce a new component of the stress response: the increase of receptor-mediated uptake of macromolecules from the external environment. We observed that endocytosis of transferrin, which is involved in the delivery of iron to the cell, was increased after stress induced by heat shock or after incubation with inhibitors of Hsp90 function. In both cases, the increase in endocytosis was reverted by inhibition of transcription, suggesting that gene expression is required. Transfection of cells with Hsp70 gene or inhibition of its expression by siRNA confirmed the role of this HSP in the increase of endocytosis. The mechanism for the enhancement of transferrin uptake was related to an accelerated internalization of the ligand-receptor complex as well as an increase in receptor recycling. These observations constitute a new paradigm for the cellular protection induced by HSP.
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Affiliation(s)
- Virginia L. Vega
- UCSD Department of Surgery, University of California San Diego, 9500 Gilman Drive, 0739, La Jolla, CA 92093-0739 USA
| | - Wisler Charles
- UCSD Department of Surgery, University of California San Diego, 9500 Gilman Drive, 0739, La Jolla, CA 92093-0739 USA
| | - Antonio De Maio
- UCSD Department of Surgery, University of California San Diego, 9500 Gilman Drive, 0739, La Jolla, CA 92093-0739 USA
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Ihara Y, Manabe S, Ikezaki M, Inai Y, Matsui ISL, Ohta Y, Muroi E, Ito Y. C-Mannosylated peptides derived from the thrombospondin type 1 repeat interact with Hsc70 to modulate its signaling in RAW264.7 cells. Glycobiology 2010; 20:1298-310. [PMID: 20581007 DOI: 10.1093/glycob/cwq096] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The thrombospondin type 1 repeat (TSR) is a functional module of proteins called TSR superfamily proteins (e.g., thrombospondin, F-spondin, mindin, etc.) and includes a conserved Trp-x-x-Trp (W-x-x-W) motif, in which the first Trp residue is preferably modified by C-mannosylation. We previously reported that synthesized C-mannosylated TSR-derived peptides (e.g., C-Man-WSPW) specifically enhanced lipopolysaccharide-induced signaling in macrophage-like RAW264.7 cells. In this study, we searched for the proteins that bind to C-mannosylated TSR-derived peptides in RAW264.7 cells and identified heat shock cognate protein 70 (Hsc70). The binding affinity of Hsc70 for C-mannosylated peptides in solution was higher than that for the peptides without C-mannose. The binding was influenced by a nucleotide-induced conformational change of Hsc70, and C-mannosylated peptides preferred the substrate-binding domain of Hsc70. Furthermore, in RAW264.7 cells, addition of Hsc70 stimulated cellular signaling to produce tumor necrosis factor-alpha, via transforming growth factor-beta-activated kinase 1, and the Hsc70-induced signaling was enhanced more in the presence of the peptides with C-mannose than that without C-mannose, suggesting functional interaction between Hsc70 and the C-mannosylated peptides in the cells. Together, these results demonstrate a novel function of the C-mannosylation of TSR-derived peptides in terms of interaction with Hsc70 to regulate cellular signaling.
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Affiliation(s)
- Yoshito Ihara
- Department of Biochemistry, Wakayama Medical University, Wakayama, Japan.
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131
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Stetler RA, Gan Y, Zhang W, Liou AK, Gao Y, Cao G, Chen J. Heat shock proteins: cellular and molecular mechanisms in the central nervous system. Prog Neurobiol 2010; 92:184-211. [PMID: 20685377 DOI: 10.1016/j.pneurobio.2010.05.002] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 05/23/2010] [Accepted: 05/27/2010] [Indexed: 12/30/2022]
Abstract
Emerging evidence indicates that heat shock proteins (HSPs) are critical regulators in normal neural physiological function as well as in cell stress responses. The functions of HSPs represent an enormous and diverse range of cellular activities, far beyond the originally identified roles in protein folding and chaperoning. HSPs are now understood to be involved in processes such as synaptic transmission, autophagy, ER stress response, protein kinase and cell death signaling. In addition, manipulation of HSPs has robust effects on the fate of cells in neurological injury and disease states. The ongoing exploration of multiple HSP superfamilies has underscored the pluripotent nature of HSPs in the cellular context, and has demanded the recent revamping of the nomenclature referring to these families to reflect a re-organization based on structure and function. In keeping with this re-organization, we first discuss the HSP superfamilies in terms of protein structure, regulation, expression and distribution in the brain. We then explore major cellular functions of HSPs that are relevant to neural physiological states, and from there we discuss known and proposed HSP impacts on major neurological disease states. This review article presents a three-part discussion on the array of HSP families relevant to neuronal tissue, their cellular functions, and the exploration of therapeutic targets of these proteins in the context of neurological diseases.
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Affiliation(s)
- R Anne Stetler
- Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, PA 15261, United States.
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132
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Fujikawa T, Munakata T, Kondo SI, Satoh N, Wada S. Stress response in the ascidian Ciona intestinalis: transcriptional profiling of genes for the heat shock protein 70 chaperone system under heat stress and endoplasmic reticulum stress. Cell Stress Chaperones 2010; 15:193-204. [PMID: 19629754 PMCID: PMC2866982 DOI: 10.1007/s12192-009-0133-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 07/02/2009] [Accepted: 07/03/2009] [Indexed: 10/20/2022] Open
Abstract
The genome of Ciona intestinalis contains eight genes for HSP70 superfamily proteins, 36 genes for J-proteins, a gene for a J-like protein, and three genes for BAG family proteins. To understand the stress responses of genes in the HSP70 chaperone system comprehensively, the transcriptional profiles of these 48 genes under heat stress and endoplasmic reticulum (ER) stress were studied using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Heat stress treatment increased the messenger RNA (mRNA) levels of six HSP70 superfamily genes, eight J-protein family genes, and two BAG family genes. In the cytoplasmic group of the DnaK subfamily of the HSP70 family, Ci-HSPA1/6/7-like was the only heat-inducible gene and Ci-HSPA2/8 was the only constitutively active gene which showed striking simplicity in comparison with other animals that have been examined genome-wide so far. Analyses of the time course and temperature dependency of the heat stress responses showed that the induction of Ci-HSPA1/6/7-like expression rises to a peak after heat stress treatment at 28 degrees C (10 degrees C upshift from control temperature) for 1 h. ER stress treatment with Brefeldin A, a drug that is known to act as ER stress inducer, increased the mRNA levels of four HSP70 superfamily genes and four J-protein family genes. Most stress-inducible genes are conserved between Ciona and vertebrates, as expected from a close evolutionary relationship between them. The present study characterized the stress responses of HSP70 chaperone system genes in Ciona for the first time and provides essential data for comprehensive understanding of the functions of the HSP70 chaperone system.
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Affiliation(s)
- Tetsuya Fujikawa
- Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829 Japan
| | - Takeo Munakata
- Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829 Japan
| | - Shin-ichi Kondo
- Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829 Japan
| | - Nori Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Promotion Corporation, Uruma, Okinawa 904-2234 Japan
| | - Shuichi Wada
- Department of Bioscience, Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Shiga 526-0829 Japan
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133
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Endocytosis and clathrin-uncoating defects at synapses of auxilin knockout mice. Proc Natl Acad Sci U S A 2010; 107:4412-7. [PMID: 20160091 DOI: 10.1073/pnas.1000738107] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neuronally expressed auxilin and ubiquitously expressed cyclin-G-dependent kinase (GAK) are homologous proteins that act as cochaperones to support the Hsc70-dependent clathrin uncoating of clathrin-coated vesicles. GAK was previously shown to be essential in mouse during embryonic development and in the adult. We have now engineered an auxilin knockout mouse. Mutant mice had a high rate of early postnatal mortality and surviving pups generally had a lower body weight than wild-type pups, although they had a normal life span. GAK was up-regulated as much as 3-fold in the brains of both surviving neonates and adult mutant mice. An increased number of clathrin-coated vesicles and empty cages were present at knockout synapses both in situ and in primary neuronal cultures. Additionally, clathrin-mediated endocytosis of synaptic vesicles in knockout hippocampal neurons was impaired, most likely due to sequestration of coat components in assembled coats and cages. Collectively, our results demonstrate the specialized role of auxilin in the recycling of synaptic vesicles at synapses, but also show that its function can be partially compensated for by up-regulation of GAK.
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134
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Abstract
Cellular membrane systems delimit and organize the intracellular space. Most of the morphological rearrangements in cells involve the coordinated remodeling of the lipid bilayer, the core of the membranes. This process is generally thought to be initiated and coordinated by specialized protein machineries. Nevertheless, it has become increasingly evident that the most essential part of the geometric information and energy required for membrane remodeling is supplied via the cooperative and synergistic action of proteins and lipids, as cellular shapes are constructed using the intrinsic dynamics, plasticity and self-organizing capabilities provided by the lipid bilayer. Here, we analyze the essential role of proteo-lipid membrane domains in conducting and coordinating morphological remodeling in cells.
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Affiliation(s)
- Anna V Shnyrova
- Laboratory of Cellular and Molecular Biology, Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-1855, USA
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135
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Mills DR, Haskell MD, Callanan HM, Flanagan DL, Brilliant KE, Yang D, Hixson DC. Monoclonal antibody to novel cell surface epitope on Hsc70 promotes morphogenesis of bile ducts in newborn rat liver. Cell Stress Chaperones 2010; 15:39-53. [PMID: 19415527 PMCID: PMC2866973 DOI: 10.1007/s12192-009-0120-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 04/19/2009] [Indexed: 12/30/2022] Open
Abstract
We previously described a cell surface reactive monoclonal antibody, MAb OC.10, which recognizes an epitope shared by rat fetal liver ductal cells, hepatic progenitor cells, mature cholangiocytes, and hepatocellular carcinomas (HCC). Here, intrasplenic injection of MAb OC.10 into newborn rats was shown by immunofluorescence microscopy to strongly label intrahepatic bile ducts. Furthermore, the in situ labeling of intrahepatic cholangiocytes by injecting MAb OC.10 increased the number of intraportal and intralobular bile ducts with well-defined lumens when compared to IgM-injected control animals. The antigen for MAb OC.10 was identified by mass spectrometry as Hsc70, a constitutively expressed heat shock protein belonging to the HSP70 family. Immunoblot analysis demonstrated that MAb OC.10 reacted with recombinant bovine Hsc70 protein, with protein immunoprecipitated from rat bile duct epithelial (BDE) cell lysates with monoclonal anti-Hsc70 antibody, and with Hsc70-FLAG protein over-expressed in human 293T cells. In addition, Hsc70-specific small interfering RNA reduced the amount of OC.10 antigen expressed in nucleofected BDE cells. Consistent with the specificity of MAb OC.10 for Hsc70, heat shock did not induce OC.10 expression in BDE cells, a characteristic of Hsp70. Immunofluorescence with BDE cells further suggested that MAb OC.10 binds a novel cell surface epitope of Hsc70. This was in contrast to a commercially available monoclonal anti-Hsc70 antibody that showed strong cytosolic reactivity. These findings demonstrate that presentation of the OC.10 epitope differs between cytosolic and surface forms of Hsc70 and may suggest distinct differences in protein conformation or epitope availability determined in part by protein-protein or protein-lipid interactions. Phage display and pepscan analysis mapped the epitope for MAb OC.10 to the N-terminal 340-384 amino acids of the ATPase domain of rat Hsc70. These findings suggest that MAb OC.10 recognizes an epitope on rat Hsc70 when presented on the cell surface that promotes morphogenic maturation of bile ducts in newborn rat liver. Furthermore, since we have shown previously that the OC.10 antigen is expressed on HCC subpopulations with oval cell characteristics, our current results indicate that Hsc70 has the potential to be expressed on the surface of certain tumor cells.
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Affiliation(s)
- David R. Mills
- Department of Medicine, Division of Hematology and Oncology, Rhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, RI 02903 USA
- Rhode Island Hospital, George Building Room 362, 593 Eddy Street, Providence, RI 02903 USA
| | - Michelle D. Haskell
- Department of Medicine, Division of Hematology and Oncology, Rhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, RI 02903 USA
| | - Helen M. Callanan
- Department of Medicine, Division of Hematology and Oncology, Rhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, RI 02903 USA
| | - Donna L. Flanagan
- Department of Medicine, Division of Hematology and Oncology, Rhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, RI 02903 USA
| | - Kate E. Brilliant
- Department of Medicine, Division of Hematology and Oncology, Rhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, RI 02903 USA
| | - DongQin Yang
- Department of Medicine, Division of Hematology and Oncology, Rhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, RI 02903 USA
| | - Douglas C. Hixson
- Department of Medicine, Division of Hematology and Oncology, Rhode Island Hospital/The Warren Alpert Medical School of Brown University, Providence, RI 02903 USA
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136
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Abstract
Notch signaling induced by canonical Notch ligands is critical for normal embryonic development and tissue homeostasis through the regulation of a variety of cell fate decisions and cellular processes. Activation of Notch signaling is normally tightly controlled by direct interactions with ligand-expressing cells, and dysregulated Notch signaling is associated with developmental abnormalities and cancer. While canonical Notch ligands are responsible for the majority of Notch signaling, a diverse group of structurally unrelated noncanonical ligands has also been identified that activate Notch and likely contribute to the pleiotropic effects of Notch signaling. Soluble forms of both canonical and noncanonical ligands have been isolated, some of which block Notch signaling and could serve as natural inhibitors of this pathway. Ligand activity can also be indirectly regulated by other signaling pathways at the level of ligand expression, serving to spatiotemporally compartmentalize Notch signaling activity and integrate Notch signaling into a molecular network that orchestrates developmental events. Here, we review the molecular mechanisms underlying the dual role of Notch ligands as activators and inhibitors of Notch signaling. Additionally, evidence that Notch ligands function independent of Notch is presented. We also discuss how ligand posttranslational modification, endocytosis, proteolysis, and spatiotemporal expression regulate their signaling activity.
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Affiliation(s)
- Brendan D'Souza
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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137
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Abstract
Notch signaling occurs through direct interaction between Notch, the receptor, and its ligands, presented on the surface of neighboring cells. Endocytosis has been shown to be essential for Notch signal activation in both signal-sending and signal-receiving cells, and numerous genes involved in vesicle trafficking have recently been shown to act as key regulators of the pathway. Defects in vesicle trafficking can lead to gain- or loss-of-function defects in a context-dependent manner. Here, we discuss how endocytosis and vesicle trafficking regulate Notch signaling in both signal-sending and signal-receiving cells. We will introduce the key players in different trafficking steps, and further illustrate how they impact the signal outcome. Some of these players act as general factors and modulate Notch signaling in all contexts, whereas others modulate signaling in a context-specific fashion. We also discuss Notch signaling during mechanosensory organ development in the fly to exemplify how endocytosis and vesicle trafficking are effectively used to determine correct cell fates. In summary, endocytosis plays an essential role in Notch signaling, whereas intracellular vesicle trafficking often plays a context-dependent or regulatory role, leading to divergent outcomes in different developmental contexts.
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138
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Cheli VT, Daniels RW, Godoy R, Hoyle DJ, Kandachar V, Starcevic M, Martinez-Agosto JA, Poole S, DiAntonio A, Lloyd VK, Chang HC, Krantz DE, Dell'Angelica EC. Genetic modifiers of abnormal organelle biogenesis in a Drosophila model of BLOC-1 deficiency. Hum Mol Genet 2009; 19:861-78. [PMID: 20015953 DOI: 10.1093/hmg/ddp555] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Biogenesis of lysosome-related organelles complex 1 (BLOC-1) is a protein complex formed by the products of eight distinct genes. Loss-of-function mutations in two of these genes, DTNBP1 and BLOC1S3, cause Hermansky-Pudlak syndrome, a human disorder characterized by defective biogenesis of lysosome-related organelles. In addition, haplotype variants within the same two genes have been postulated to increase the risk of developing schizophrenia. However, the molecular function of BLOC-1 remains unknown. Here, we have generated a fly model of BLOC-1 deficiency. Mutant flies lacking the conserved Blos1 subunit displayed eye pigmentation defects due to abnormal pigment granules, which are lysosome-related organelles, as well as abnormal glutamatergic transmission and behavior. Epistatic analyses revealed that BLOC-1 function in pigment granule biogenesis requires the activities of BLOC-2 and a putative Rab guanine-nucleotide-exchange factor named Claret. The eye pigmentation phenotype was modified by misexpression of proteins involved in intracellular protein trafficking; in particular, the phenotype was partially ameliorated by Rab11 and strongly enhanced by the clathrin-disassembly factor, Auxilin. These observations validate Drosophila melanogaster as a powerful model for the study of BLOC-1 function and its interactions with modifier genes.
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Affiliation(s)
- Verónica T Cheli
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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139
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Yasuda Y, Ohtomo E, Tsukuba T, Okamoto K, Saito T. Carbon dioxide laser irradiation stimulates mineralization in rat dental pulp cells. Int Endod J 2009; 42:940-6. [PMID: 19751293 DOI: 10.1111/j.1365-2591.2009.01598.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM To examine the effect of carbon dioxide laser irradiation on mineralization in dental pulp cells. METHODOLOGY Rat dental pulp cells were irradiated with a carbon dioxide laser at 2 W output power for 20, 40 and 60 s, and were cultured in ascorbic acid and beta-glycerophosphate containing media. Cell viability was examined 24 h after laser irradiation by a modified MTT assay. Alizarin Red S staining was performed 10 days after laser irradiation. The amounts of secreted collagen from the cells after irradiation were quantified following Sirius Red staining. The expression levels of collagen type I and HSP47, collagen-binding stress protein, were analysed by real-time PCR. HSP47 protein expression was examined by Western blotting. Statistical analysis was performed using one-way analysis of variance (anova) followed by the Tukey's multiple comparison test. RESULTS The cell viability was not affected by laser irradiation at 2 W for up to 40 s. However, it was significantly decreased by 20% at 60 s (P < 0.05). The amount of mineralization after 10 days of irradiation at 2 W for 40 s was significantly increased in comparison to the other conditions (P < 0.05). The extracellular collagen production was significantly increased by 73% on day 2 and 38% on day 4 after laser irradiation (P < 0.05). Although collagen type I gene expression was not changed by laser irradiation, HSP47 gene and protein expression was induced within 12 and 24 h, respectively. CONCLUSIONS These results suggested that carbon dioxide laser irradiation stimulated mineralization in dental pulp cells. The laser irradiation also increased HSP47 expression but not collagen gene expression.
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Affiliation(s)
- Y Yasuda
- Division of Clinical Cariology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, Hokkaido 061-0293, Japan.
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140
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Affiliation(s)
- Jeremy Dittman
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065; ,
| | - Timothy A. Ryan
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065; ,
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141
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Regulation of endosomal clathrin and retromer-mediated endosome to Golgi retrograde transport by the J-domain protein RME-8. EMBO J 2009; 28:3290-302. [PMID: 19763082 DOI: 10.1038/emboj.2009.272] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 07/28/2009] [Indexed: 12/11/2022] Open
Abstract
After endocytosis, most cargo enters the pleiomorphic early endosomes in which sorting occurs. As endosomes mature, transmembrane cargo can be sequestered into inwardly budding vesicles for degradation, or can exit the endosome in membrane tubules for recycling to the plasma membrane, the recycling endosome, or the Golgi apparatus. Endosome to Golgi transport requires the retromer complex. Without retromer, recycling cargo such as the MIG-14/Wntless protein aberrantly enters the degradative pathway and is depleted from the Golgi. Endosome-associated clathrin also affects the recycling of retrograde cargo and has been shown to function in the formation of endosomal subdomains. Here, we find that the Caemorhabditis elegans endosomal J-domain protein RME-8 associates with the retromer component SNX-1. Loss of SNX-1, RME-8, or the clathrin chaperone Hsc70/HSP-1 leads to over-accumulation of endosomal clathrin, reduced clathrin dynamics, and missorting of MIG-14 to the lysosome. Our results indicate a mechanism, whereby retromer can regulate endosomal clathrin dynamics through RME-8 and Hsc70, promoting the sorting of recycling cargo into the retrograde pathway.
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142
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Shimizu H, Nagamori I, Yabuta N, Nojima H. GAK, a regulator of clathrin-mediated membrane traffic, also controls centrosome integrity and chromosome congression. J Cell Sci 2009; 122:3145-52. [PMID: 19654208 DOI: 10.1242/jcs.052795] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cyclin G-associated kinase (GAK) is an association partner of clathrin heavy chain (CHC) and is essential for clathrin-mediated membrane trafficking. Here, we report two novel functions of GAK: maintenance of proper centrosome maturation and of mitotic chromosome congression. Indeed, GAK knockdown by siRNA caused cell-cycle arrest at metaphase, which indicates that GAK is required for proper mitotic progression. We found that this impaired mitotic progression was due to activation of the spindle-assembly checkpoint, which senses protruded, misaligned or abnormally condensed chromosomes in GAK-siRNA-treated cells. GAK knockdown also caused multi-aster formation, which was due to abnormal fragmentation of pericentriolar material, but not of the centrioles. Moreover, GAK and CHC cooperated in the same pathway and interacted in mitosis to regulate the formation of a functional spindle. Taken together, we conclude that GAK and clathrin function cooperatively not only in endocytosis, but also in mitotic progression.
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Affiliation(s)
- Hiroyuki Shimizu
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Suita City, Osaka, Japan
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143
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Stolte EH, Chadzinska M, Przybylska D, Flik G, Savelkoul HFJ, Verburg-van Kemenade BML. The immune response differentially regulates Hsp70 and glucocorticoid receptor expression in vitro and in vivo in common carp (Cyprinus carpio L.). FISH & SHELLFISH IMMUNOLOGY 2009; 27:9-16. [PMID: 19061961 DOI: 10.1016/j.fsi.2008.11.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 10/28/2008] [Accepted: 11/06/2008] [Indexed: 05/27/2023]
Abstract
Heat shock or stress proteins and glucocorticoids (cortisol) regulate a sequential pro-inflammatory and anti-inflammatory cytokine expression profile to effectively kill pathogens, whilst minimizing damage to the host. Cortisol elicits its effects through the glucocorticoid receptor (GR) for which Hsp70 and Hsp90 are required as chaperones. In common carp, (Cyprinus carpio) duplicated glucocorticoid receptor genes and splice variants with different cortisol sensitivities exist. We investigated the expression profiles of heat shock proteins Hsp70, Hsc70, Hsp90alpha and Hsp90beta and the three different variants of GR in vitro in and in vivo to define their role in immune modulation. A rapid transient induction of GR1 (a and b) and Hsp70 was seen after LPS treatment in vitro in head kidney phagocytes, whereas cortisol treatment did not affect constitutive or LPS-induced expression of Hsp70 or GR1 expression. In vivo zymosan-induced peritonitis upregulated GR and Hsp70 expression which appears to increase sensitivity for cortisol-induced immune modulation. Indeed, the increased GR and Hsp70 expression correlates with inhibition of both LPS- and zymosan-induced expression of pro-inflammatory cytokines. Infection with the blood parasite T. borreli decreases GR1a expression in thymus, but increases GR2 expression in spleen. Differentially regulated expression of Hsp70 and of glucocorticoid receptor variants with different cortisol sensitivities, underlines their physiological importance in a balanced immune response.
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Affiliation(s)
- Ellen H Stolte
- Cell Biology and Immunology Group, Wageningen University, Marijkeweg 40, Wageningen, The Netherlands
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144
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Parkar NS, Akpa BS, Nitsche LC, Wedgewood LE, Place AT, Sverdlov MS, Chaga O, Minshall RD. Vesicle formation and endocytosis: function, machinery, mechanisms, and modeling. Antioxid Redox Signal 2009; 11:1301-12. [PMID: 19113823 PMCID: PMC2850289 DOI: 10.1089/ars.2008.2397] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Vesicle formation provides a means of cellular entry for extracellular substances and for recycling of membrane constituents. Mechanisms governing the two primary endocytic pathways (i.e., caveolae- and clathrin-mediated endocytosis, as well as newly emerging vesicular pathways) have become the focus of intense investigation to improve our understanding of nutrient, hormone, and drug delivery, as well as opportunistic invasion of pathogens. In this review of endocytosis, we broadly discuss the structural and signaling proteins that compose the molecular machinery governing endocytic vesicle formation (budding, invagination, and fission from the membrane), with some regard for the specificity observed in certain cell types and species. Important biochemical functions of endocytosis and diseases caused by their disruption also are discussed, along with the structures of key components of endocytic pathways and their known mechanistic contributions. The mechanisms by which principal components of the endocytic machinery are recruited to the plasma membrane, where they interact to induce vesicle formation, are discussed, together with computational approaches used to simulate simplified versions of endocytosis with the hope of clarifying aspects of vesicle formation that may be difficult to determine experimentally. Finally, we pose several unanswered questions intended to stimulate further research interest in the cell biology and modeling of endocytosis.
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Affiliation(s)
- Nihal S Parkar
- Department of Chemical Engineering, College of Engineering and College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612, USA
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145
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Sato J, Shimizu H, Kasama T, Yabuta N, Nojima H. GAK, a regulator of clathrin-mediated membrane trafficking, localizes not only in the cytoplasm but also in the nucleus. Genes Cells 2009; 14:627-41. [PMID: 19371378 DOI: 10.1111/j.1365-2443.2009.01296.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The ubiquitously expressed Cyclin G-associated kinase (GAK) regulates clathrin-mediated membrane trafficking in the cytoplasm. However, the association of GAK with a nuclear protein Cyclin G1 that is unrelated to membrane trafficking suggests an unidentified role of GAK in the nucleus. Indeed, we report here that GAK localizes in both cytoplasm and nucleus by immunostaining, ectopic expression of GFP-GAK and pull-down assays using dissected GAK fragments. GAK forms complexes not only with cyclin G1 but also with other nuclear proteins such as p53, clathrin heavy chain (CHC) and protein phosphatase 2A (PP2A) B'alpha1. Moreover, CHC associates with GAK via a different domain depending on whether it is in the cytoplasm or nucleus. Immunostaining revealed that about 20-30% of B'alpha1, cyclin G1 and p53 complex with nuclear GAK. CHC also displayed dots in the nucleus and almost all nuclear CHC signals colocalized with GAK. These observations together suggest an important function of GAK in the nucleus.
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Affiliation(s)
- Jun Sato
- Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita City, Osaka 565-0871, Japan
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146
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Brown D, Breton S, Ausiello DA, Marshansky V. Sensing, signaling and sorting events in kidney epithelial cell physiology. Traffic 2009; 10:275-84. [PMID: 19170982 PMCID: PMC2896909 DOI: 10.1111/j.1600-0854.2008.00867.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The kidney regulates body fluid, ion and acid/base homeostasis through the interaction of a host of channels, transporters and pumps within specific tubule segments, specific cell types and specific plasma membrane domains. Furthermore, renal epithelial cells have adapted to function in an often unique and challenging environment that includes high medullary osmolality, acidic pHs, variable blood flow and constantly changing apical and basolateral 'bathing' solutions. In this review, we focus on selected protein trafficking events by which kidney epithelial cells regulate body fluid, ion and acid-base homeostasis in response to changes in physiological conditions. We discuss aquaporin 2 and G-protein-coupled receptors in fluid and ion balance, the vacuolar H(+)-adenosine triphosphatase (V-ATPase) and intercalated cells in acid/base regulation and acidification events in the proximal tubule degradation pathway. Finally, in view of its direct role in vesicle trafficking that we outline in this study, we propose that the V-ATPase itself should, under some circumstances, be considered a fourth category of vesicle 'coat' protein (COP), alongside clathrin, caveolin and COPs.
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Affiliation(s)
- Dennis Brown
- Center for Systems Biology, Program in Membrane Biology and Nephrology Division, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
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147
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Rosales-Hernandez A, Beck KE, Zhao X, Braun AP, Braun JEA. RDJ2 (DNAJA2) chaperones neural G protein signaling pathways. Cell Stress Chaperones 2009; 14:71-82. [PMID: 18595009 PMCID: PMC2673899 DOI: 10.1007/s12192-008-0056-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 05/28/2008] [Indexed: 12/11/2022] Open
Abstract
A number of structurally divergent proteins with J domains, called J proteins, interact with and activate the ATPase of Hsp70s, thereby harnessing the ATPase activity for conformational work on target proteins. The precise role of most mammalian J proteins remains undefined. In this paper, we demonstrate that transient expression of the J protein, Rdj2, in HEK 293 cells increased cellular cyclic adenosine monophosphate (cAMP) levels in the presence of the beta-adrenergic agonist isoproterenol. In CNS-derived catecholaminergic neuronal cell line (CAD) neuroblastoma cells, expression of Rdj2 increased isoproterenol-stimulated phosphorylation of cAMP response element binding protein (CREB). Moreover, we have characterized the binding properties of Rdj2 and observed a direct interaction between Rdj2 and receptor-coupled trimeric GTP-binding proteins (G proteins). We further show that the composition of the Rdj2-chaperone complex and the cysteine string protein (CSPalpha)-chaperone complex, another J protein, is distinct. Our data demonstrate that Rdj2 modulates G protein signaling and further suggest that chaperoning G proteins is an emerging theme of the J protein network.
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Affiliation(s)
- Alma Rosales-Hernandez
- Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, AB Canada T2N 4N1
| | - Katy E. Beck
- Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, AB Canada T2N 4N1
| | - Xiaoxi Zhao
- Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, AB Canada T2N 4N1
| | - Andrew P. Braun
- Libin Cardiovascular Institute of Alberta, Department of Pharmacology and Therapeutics, University of Calgary, Calgary, AB Canada T2N 4N1
| | - Janice E. A. Braun
- Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, AB Canada T2N 4N1
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Kang S, Sim C, Byrd BD, Collins FH, Hong YS. Ex vivo promoter analysis of antiviral heat shock cognate 70B gene in Anopheles gambiae. Virol J 2008; 5:136. [PMID: 18986525 PMCID: PMC2614971 DOI: 10.1186/1743-422x-5-136] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Accepted: 11/05/2008] [Indexed: 11/22/2022] Open
Abstract
Background The Anopheles gambiae heat shock cognate gene (hsc70B) encodes a constitutively expressed protein in the hsp70 family and it functions as a molecular chaperone for protein folding. However, the expression of hsc70B can be further induced by certain stimuli such as heat shock and infection. We previously demonstrated that the An. gambiae hsc70B is induced during o'nyong-nyong virus (ONNV) infection and subsequently suppresses ONNV replication in the mosquito. To further characterize the inducibility of hsc70B by ONNV infection in An. gambiae, we cloned a 2.6-kb region immediately 5' upstream of the starting codon of hsc70B into a luciferase reporter vector (pGL3-Basic), and studied its promoter activity in transfected Vero cells during infection with o'nyong-nyong, West Nile and La Crosse viruses. Results Serial deletion analysis of the hsc70B upstream sequence revealed that the putative promoter is likely located in a region 1615–2150 bp upstream of the hsc70B starting codon. Sequence analysis of this region revealed transcriptional regulatory elements for heat shock element-binding protein (HSE-bind), nuclear factor κB (NF-κB), dorsal (Dl) and fushi-tarazu (Ftz). Arbovirus infection, regardless of virus type, significantly increased the hsc70B promoter activity in transfected Vero cells. Conclusion Our results further validate the transcriptional activation of hsc70B during arbovirus infection and support the role of specific putative regulatory elements. Induction by three taxonomically distinct arboviruses suggests that the HSC70B protein may be expressed to cope with cellular stress imposed during infection.
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Affiliation(s)
- Seokyoung Kang
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana 70112, USA.
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150
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Heimel JA, Hermans JM, Sommeijer JP, Levelt CN. Genetic control of experience-dependent plasticity in the visual cortex. GENES BRAIN AND BEHAVIOR 2008; 7:915-23. [PMID: 18700840 DOI: 10.1111/j.1601-183x.2008.00431.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Depriving one eye of visual experience during a sensitive period of development results in a shift in ocular dominance (OD) in the primary visual cortex (V1). To assess the heritability of this form of cortical plasticity and identify the responsible gene loci, we studied the influence of monocular deprivation on OD in a large number of recombinant inbred mouse strains derived from mixed C57BL/6J and DBA/2J backgrounds (BXD). The strength of imaged intrinsic signal responses in V1 to visual stimuli was strongly heritable as were various elements of OD plasticity. This has important implications for the use of mice of mixed genetic backgrounds for studying OD plasticity. C57BL/6J showed the most significant shift in OD, while some BXD strains did not show any shift at all. Interestingly, the increase in undeprived ipsilateral eye responses was not correlated to the decrease in deprived contralateral eye responses, suggesting that the size of these components of OD plasticity are not genetically controlled by only a single mechanism. We identified a quantitative trait locus regulating the change in response to the deprived eye. The locus encompasses 13 genes, two of which--Stch and Nrip1--contain missense polymorphisms. The expression levels of Stch and to a lesser extent Nrip1 in whole brain correlate with the trait identifying them as novel candidate plasticity genes.
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Affiliation(s)
- J A Heimel
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands.
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