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Cover image for Vol. 16 Issue 7

Early View (Online Version of Record published before inclusion in an issue)

Edited By: Michael S. Marks, Trina A. Schroer, Tom H. Stevens, Sharon A. Tooze

Online ISSN: 1600-0854

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  1. 1 - 12
  1. Original Articles

    1. Dengue Virus Uses a Non-Canonical Function of the Host GBF1-Arf-COPI System for Capsid Protein Accumulation on Lipid Droplets

      Nestor G. Iglesias, Juan A. Mondotte, Laura A. Byk, Federico A. De Maio, Marcelo M. Samsa, Cecilia Alvarez and Andrea V. Gamarnik

      Article first published online: 29 JUN 2015 | DOI: 10.1111/tra.12305

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      The dengue virus capsid protein accumulates progressively around cellular organelles named lipid droplets (LDs) during infection. Using different methods of intervention, we defined that capsid transport from virally modified endoplasmic reticulum (ER) membranes to LDs requires a functional GBF1 protein. The process was found to be COPI dependent, while it was independent of both COPII components and Golgi integrity, supporting a non-canonical function of GBF1/ARF/COPI transport system.

    2. You have full text access to this OnlineOpen article
      GSK-3β Phosphorylation of Cytoplasmic Dynein Reduces Ndel1 Binding to Intermediate Chains and Alters Dynein Motility

      Feng J. Gao, Sachin Hebbar, Xu A. Gao, Michael Alexander, Jai P. Pandey, Michael D. Walla, William E. Cotham, Stephen J. King and Deanna S. Smith

      Article first published online: 26 JUN 2015 | DOI: 10.1111/tra.12304

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      A model for GSK-3β-dependent regulation of retrograde organelle transport in response to insulin signaling. A) In control cells, active GSK-3 phosphorylates dynein. B) GSK-3 inactivation by insulin signaling or by inhibitors such as CT99021 (CT) or LiCl results in less phosphorylated dynein. Loss of phosphorylated residues in intermediate chains allows more efficient binding to Ndel1. Ndel1 stimulates dynein-dependent cargo movement toward microtubule minus ends, suggesting a potential mechanism for regulation of retrograde organelle transport in response to extracellular cues.

    3. The Phosphoinositide-Gated Lysosomal Ca2+ Channel, TRPML1, Is Required for Phagosome Maturation

      Roya M. Dayam, Amra Saric, Ryan E. Shilliday and Roberto J. Botelho

      Article first published online: 18 JUN 2015 | DOI: 10.1111/tra.12303

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      TRPML1 is a lysosomal Ca2+ channel gated by phosphatidylinositol-3,5-bisphosphate, a signaling lipid that controls late endosome and lysosome function. Here, we show that TRPML1 is necessary to trigger fusion of lysosomes docked to phagosomes, for efficient killing of phagocytosed bacteria and the release of lysosomal Ca2+ into the cytosol after phagocytosis.

    4. Highlight

      Sorting of Clathrin-Independent Cargo Proteins Depends on Rab35 Delivered by Clathrin-Mediated Endocytosis

      Dipannita Dutta and Julie G. Donaldson

      Article first published online: 4 JUN 2015 | DOI: 10.1111/tra.12302

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      Here we show that inhibition of clathrin-mediated endocytosis does not inhibit clathrin-independent endocytosis but does alter the endosomal trafficking of cargo proteins that enter cells this way. The altered trafficking can be rescued by over-expression of Rab35 or induced by depletion of Rab35 suggesting that Rab35 activity may serve as an indicator of normal input from clathrin-mediated endocytosis.

  2. Reviews

    1. Synaptic Cytoskeletal Plasticity in the Prefrontal Cortex Following Psychostimulant Exposure

      Lauren M. DePoy and Shannon L. Gourley

      Article first published online: 1 JUN 2015 | DOI: 10.1111/tra.12295

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      Exposure to cocaine and amphetamine structurally reorganizes excitatory neurons in the medial and orbital prefrontal cortices (mPFC and oPFC), inducing dendritic spine proliferation in the mPFC and eliminating spines in the oPFC. Modifications may be causally associated with addiction etiology. Certain cytoskeletal regulatory proteins expressed in the oPFC and implicated in postnatal neural development also regulate behavioral sensitivity to cocaine, potentially opening a window of opportunity for the identification of novel pharmacotherapeutic targets in the treatment of drug abuse disorders.

  3. Original Articles

    1. Chondroitin Sulfate Accelerates Trans-Golgi-to-Surface Transport of Proteoglycan Amyloid Precursor Protein

      Deyan Mihov, Eva Raja and Martin Spiess

      Article first published online: 25 MAY 2015 | DOI: 10.1111/tra.12294

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      The role of glycosaminoglycans (GAGs) as sorting determinants in intracellular protein transport is not well understood. We took advantage of amyloid precursor protein (APP) as a part-time proteoglycan that naturally exists in proteoglycan and GAG-free forms. We discovered that GAGs act as an alternative sorting determinant in APP transport that is dominant over its cytoplasmic signals and involves a distinct sorting mechanism shared by protein-free GAG chains. The pathways of both the proteoglycan and the GAG-free forms of APP involve endosomes.

    2. You have free access to this content
      Multiple Domains in PEX16 Mediate Its Trafficking and Recruitment of Peroxisomal Proteins to the ER

      Rong Hua, Satinder K. Gidda, Alexander Aranovich, Robert T. Mullen and Peter K. Kim

      Article first published online: 12 MAY 2015 | DOI: 10.1111/tra.12292

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      PEX16 is an essential regulator of peroxisome biogenesis required for the endoplasmic reticulum (ER)-dependent trafficking of peroxisomal membrane proteins (PMPs). We carried out a comprehensive mutagenesis analysis of human PEX16 to gain insight to its functions. We show that the first transmembrane domain serves as an ER signal anchor sequence and residues 71–81 are required for its subsequent targeting to peroxisomes. We also show that residues 66–103 are required for PEX16 to recruit a wide range of PMPs to the ER.

  4. Toolbox

    1. Assessing Mitochondrial Movement Within Neurons: Manual Versus Automated Tracking Methods

      Helena Bros, Anja Hauser, Friedemann Paul, Raluca Niesner and Carmen Infante-Duarte

      Article first published online: 12 MAY 2015 | DOI: 10.1111/tra.12291

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      We examined the suitability of automated tools for tracking mitochondria within neurons, compared with manual tracking (lines indicating mitochondrial movements are marked on each micrograph). The results from automated programs differed significantly from those obtained manually, and both correlation and agreement between methods were poor. However, automated tools could detect relative transport alterations induced by experimental interventions. Thus, automated mitochondrial tracking may be suitable for assessing relative differences in transport, but not for providing absolute quantification of mitochondrial dynamics.

  5. Original Articles

    1. You have full text access to this OnlineOpen article
      Vaccinia Virus Infection Requires Maturation of Macropinosomes

      Zaira Rizopoulos, Giuseppe Balistreri, Samuel Kilcher, Caroline K. Martin, Mohammedyaseen Syedbasha, Ari Helenius and Jason Mercer

      Article first published online: 6 MAY 2015 | DOI: 10.1111/tra.12290

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      Vaccinia virus VACV, the prototypic poxvirus, enters cells by inducing macropinocytosis. However, the identity of the intracellular transport vesicles and trafficking factors required to carry the virus to the sites of uncoating remain undefined. Using a combination of fixed- and live-cell imaging, and an endocytosis-directed RNAi screen, we identified these compartments as maturing macropinosomes. Perturbation of endosome maturation showed that Rab7a and PIKfyve were critical for VACV infection. These results indicate that VACV is a late-penetrating virus that depends on macropinosome maturation for productive entry.

  6. Toolbox

    1. Adaptation of Cryo-Sectioning for IEM Labeling of Asymmetric Samples: A Study Using Caenorhabditis elegans

      Ophélie Nicolle, Agnès Burel, Gareth Griffiths, Grégoire Michaux and Irina Kolotuev

      Article first published online: 6 MAY 2015 | DOI: 10.1111/tra.12289

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      The cryo-sectioning procedure developed by Tokuyasu enables efficient protein localization at the ultrastructural level of diverse samples but has proven to be technically difficult for asymmetric samples. Here, we describe a method that enables reproducible cryo-sectioning of Caenorhabditis elegans larvae and embryos. The procedure considerably simplifies manipulation and lateral orientation. In addition to the standard chemical fixation-based procedure, we have improved the hybrid cryo-immobilization–rehydration technique. Ultrastructure preservation was efficient using both approaches, but immuno-electron localization of different C. elegans specific proteins gave better results with the fast-hybrid procedure. Our method can be successfully used to prepare small asymmetric samples for immunogold labeling.

    2. A Cell-Based Assay Reveals Nuclear Translocation of Intracellular Domains Released by SPPL Proteases

      Torben Mentrup, Robert Häsler, Regina Fluhrer, Paul Saftig and Bernd Schröder

      Article first published online: 6 MAY 2015 | DOI: 10.1111/tra.12287

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      The intramembrane proteases signal peptide peptidase-like 2a/b (SPPL) liberate intracellular domains (ICDs) from type II transmembrane proteins. We describe a cell-based assay employing β-galactosidase fragment complementation for quantifying the activity of SPPL2 or other intramembrane proteases based on detecting nuclear translocation of released substrate ICDs. In this system, we demonstrate nuclear translocation of CD74-, TNF- and ITM2B-ICDs and characterize SFRP2 as potential transcriptional target of the CD74-ICD. The assay will allow to screen for novel inhibitors and to analyze the regulation of intramembrane proteases.

  7. Original Articles

    1. A Spatial Model of Insulin-Granule Dynamics in Pancreatic β-Cells

      Jaber Dehghany, Peter Hoboth, Anna Ivanova, Hassan Mziaut, Andreas Müller, Yannis Kalaidzidis, Michele Solimena and Michael Meyer-Hermann

      Article first published online: 1 MAY 2015 | DOI: 10.1111/tra.12286

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      An agent-based model of insulin-granule dynamics is developed based on the measured spatial distribution and motility of granules. This novel model reproduces measured spatial organization of granules and insulin secretion patterns under different stimulation protocols. Our results implicate that potentiation of insulin secretion relies on the exocytosis machinery and on the number of docking sites and not on the delivery of new granules to the cortical region and the plasma membrane.

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