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https://www.readbyqxmd.com/read/29150658/differential-regulation-of-synaptic-ap-2-clathrin-vesicle-uncoating-in-synaptic-plasticity
#1
Ermes Candiello, Ratnakar Mishra, Bernhard Schmidt, Olaf Jahn, Peter Schu
AP-1/σ1B-deficiency causes X-linked intellectual disability. AP-1/σ1B -/- mice have impaired synaptic vesicle recycling, fewer synaptic vesicles and enhanced endosome maturation mediated by AP-1/σ1A. Despite defects in synaptic vesicle recycling synapses contain two times more endocytic AP-2 clathrin-coated vesicles. We demonstrate increased formation of two classes of AP-2/clathrin coated vesicles. One which uncoats readily and a second with a stabilised clathrin coat. Coat stabilisation is mediated by three molecular mechanisms: reduced recruitment of Hsc70 and synaptojanin1 and enhanced μ2/AP-2 phosphorylation and activation...
November 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29150640/early-endosome-motility-mediates-%C3%AE-amylase-production-and-cell-differentiation-in-aspergillus-oryzae
#2
Yusuke Togo, Yujiro Higuchi, Yoshinori Katakura, Kaoru Takegawa
Recent research in filamentous fungi has revealed that the motility of an endocytic organelle early endosome (EE) has a versatile role in many physiological functions. Here, to further examine the motility of EEs in the industrially important fungus Aspergillus oryzae, we visualized these organelles via the Rab5 homolog AoRab5 and identified AoHok1, a putative linker protein between an EE and a motor protein. The Aohok1 disruptant showed retarded mycelial growth and no EE motility, in addition to an apical accumulation of EEs and peroxisomes...
November 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29150437/mechanism-of-activation-of-sgk3-by-growth-factors-via-the-class-1-and-class-3-pi3ks
#3
Nazma Malik, Thomas Macartney, Annika Hornberger, Karen Anderson, Hannah Tovell, Alan R Prescott, Dario R Alessi
Derailment of the PI3K-AGC protein kinase signalling network contributes to many human diseases including cancer. Recent work has revealed that the poorly studied AGC kinase family member, SGK3 promotes resistance to cancer therapies that target the Class 1 PI3K pathway, by substituting for loss of Akt kinase activity. SGK3 is recruited and activated at endosomes, by virtue of its PX domain binding to PtdIns(3)P. Here we demonstrate that endogenous SGK3 is rapidly activated by growth factors such as IGF1, through pathways involving both Class 1 and Class 3 PI3Ks...
November 17, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/29150077/unique-arginine-array-improves-cytosolic-localization-of-hydrocarbon-stapled-peptides
#4
Kim Quach, Jonathan LaRochelle, Xiao-Han Li, Elizabeth Rhoades, Alanna Schepartz
We have previously reported that miniature proteins containing a distinct array of 5 arginine residues on a folded α-helix - a penta-arg motif - traffic with high efficiency from endosomes into the cytosol and nucleus of mammalian cells. Here we evaluate whether a penta-arg motif can improve the intracellular trafficking of an otherwise impermeant hydrocarbon-stapled peptide, SAH-p53-4(Rho). We prepared a panel of SAH-p53-4(Rho) variants containing penta-arg sequences with different spacings and axial arrangement and evaluated their overall uptake (as judged by flow cytometry) and their intracellular access (as determined by fluorescence correlation spectroscopy, FCS)...
November 7, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/29149609/snapshot-functions-of-endoplasmic-reticulum-membrane-contact-sites
#5
Raquel Salvador-Gallego, Melissa J Hoyer, Gia K Voeltz
The endoplasmic reticulum (ER) consists of the nuclear envelope and a reticulated interconnected network of tubules and sheets. ER sheets are studded with ribosomes and provide the entryway for proteins into the secretory pathway. ER tubules move dynamically on microtubules and form membrane contact sites with other organelles, where membranes are tethered, but not fused. This Snapshot reviews key biological processes that take place at ER contact sites with the Golgi, endosomes, and mitochondria.
November 16, 2017: Cell
https://www.readbyqxmd.com/read/29146245/repurposing-cationic-amphiphilic-drugs-as-adjuvants-to-induce-lysosomal-sirna-escape-in-nanogel-transfected-cells
#6
Freya Joris, Lynn De Backer, Thijs Van de Vyver, Chiara Bastiancich, Stefaan C De Smedt, Koen Raemdonck
Cytosolic delivery remains a major bottleneck for siRNA therapeutics. To facilitate delivery, siRNAs are often enclosed in nanoparticles (NPs). However, upon endocytosis such NPs are mainly trafficked towards lysosomes. To avoid degradation, cytosolic release of siRNA should occur prior to fusion of endosomes with lysosomes, but current endosomal escape strategies remain inefficient. In contrast to this paradigm, we aim to exploit lysosomal accumulation by treating NP-transfected cells with low molecular weight drugs that release the siRNA from the lysosomes into the cytosol...
November 13, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/29142761/aeromonas-hydrophila-utilizes-tlr4-topology-for-synchronous-activation-of-myd88-and-trif-to-orchestrate-anti-inflammatory-responses-in-zebrafish
#7
Nidhi Srivastava, Asha Shelly, Manmohan Kumar, Archana Pant, Bhabatosh Das, Tanmay Majumdar, Shibnath Mazumder
Toll-like receptor 4 (TLR4) plays a critical role in host immunity against Gram-negative bacteria. It transduces signals through two distinct TIR-domain-containing adaptors, MyD88 and TRIF, which function at the plasma membrane and endosomes, respectively. Using zebrafish Aeromonas hydrophila infection model, we demonstrate that synchronization of MyD88 and TRIF dependent pathways is critical for determining the fate of infection. Zebrafish were infected with A. hydrophila, and bacterial recovery studies suggested its effective persistence inside the host...
2017: Cell Death Discovery
https://www.readbyqxmd.com/read/29142129/entry-of-human-coronavirus-nl63-to-the-cell
#8
Aleksandra Milewska, Paulina Nowak, Katarzyna Owczarek, Artur Szczepanski, Miroslaw Zarebski, Agnieszka Hoang-Bujnowicz, Krzysztof Berniak, Jacek Wojarski, Slawomir Zeglen, Zbigniew Baster, Zenon Rajfur, Krzysztof Pyrc
First steps of human coronavirus NL63 (HCoV-NL63) infection were previously described. The virus binds to target cells by heparan sulfate proteoglycans, and interacts with the ACE2 protein. Subsequent events, including virus internalization and trafficking, remain to be elucidated. In this study, we mapped the process of HCoV-NL63 entry into LLC-Mk2 cell line and ex vivo 3D tracheobronchial tissue.Using a variety of techniques we have shown that HCoV-NL63 virions require endocytosis for successful entry to the LLC-MK2 cells, and interaction between the virus and the ACE2 molecule triggers recruitment of clathrin...
November 15, 2017: Journal of Virology
https://www.readbyqxmd.com/read/29142073/gga1-regulates-signal-dependent-sorting-of-bace1-to-recycling-endosomes-which-moderates-a%C3%AE-production
#9
Wei Hong Toh, Pei Zhi Cheryl Chia, Mohammed Iqbal Hossain, Paul A Gleeson
The diversion of the membrane-bound β-secretase BACE1 from the endo-lysosomal pathway to recycling endosomes represents an important transport step in the regulation of amyloid beta (Aβ) production. However, the mechanisms that regulate endosome sorting of BACE1 are poorly understood. Here we assessed the transport of BACE1 from early to recycling endosomes and have identified essential roles for the SNX4-mediated, signal independent pathway and for a novel signal-mediated pathway. The signal-mediated pathway is regulated by the phosphorylation of the acidic cluster-dileucine DISLL cytoplasmic tail motif of BACE1...
November 15, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/29141923/src-family-kinase-inhibitors-blunt-the-pacap-induced-pac1-receptor-endocytosis-phosphorylation-of-erk-and-increase-in-cardiac-neuron-excitability
#10
John D Tompkins, Todd A Clason, Thomas R Buttolph, Beatrice M Girard, Anne K Linden, Jean C Hardwick, Laura A Merriam, Victor May, Rodney L Parsons
Pituitary adenylate cyclase activating polypeptide (PACAP, Adcyap1) activation of PAC1 receptors (Adcyap1r1) significantly increases excitability of guinea pig cardiac neurons. This modulation of excitability is mediated in part by plasma membrane G protein-dependent activation of adenylyl cyclase and downstream signaling cascades. However, additional mechanisms responsible for the enhanced excitability are activated following internalization of the PAC1 receptor and endosomal signaling. Src family kinases play critical roles mediating endocytosis of many trophic factor and G-protein coupled receptors...
November 15, 2017: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/29141870/ig%C3%AE-ubiquitination-activates-pi3k-signals-required-for-endosomal-sorting
#11
Margaret Veselits, Azusa Tanaka, Yaoqing Chen, Keith Hamel, Malay Mandal, Matheswaran Kandasamy, Balaji Manicassamy, Shannon K O'Neill, Patrick Wilson, Roger Sciammas, Marcus R Clark
A wealth of in vitro data has demonstrated a central role for receptor ubiquitination in endocytic sorting. However, how receptor ubiquitination functions in vivo is poorly understood. Herein, we report that ablation of B cell antigen receptor ubiquitination in vivo uncouples the receptor from CD19 phosphorylation and phosphatidylinositol 3-kinase (PI3K) signals. These signals are necessary and sufficient for accumulating phosphatidylinositol (3,4,5)-trisphosphate (PIP3) on B cell receptor-containing early endosomes and proper sorting into the MHC class II antigen-presenting compartment (MIIC)...
November 15, 2017: Journal of Experimental Medicine
https://www.readbyqxmd.com/read/29140158/endosomal-trafficking-regulates-receptor-mediated-transcytosis-of-antibodies-across-the-blood-brain-barrier
#12
Arsalan S Haqqani, Christie E Delaney, Eric Brunette, Ewa Baumann, Graham K Farrington, William Sisk, John Eldredge, Wen Ding, Tammy-Lynn Tremblay, Danica B Stanimirovic
Current methods for examining antibody trafficking are either non-quantitative such as immunocytochemistry or require antibody labeling with tracers. We have developed a multiplexed quantitative method for antibody 'tracking' in endosomal compartments of brain endothelial cells. Rat brain endothelial cells were co-incubated with blood-brain barrier (BBB)-crossing FC5, monovalent FC5Fc or bivalent FC5Fc fusion antibodies and control antibodies. Endosomes were separated using sucrose-density gradient ultracentrifugation and analyzed using multiplexed mass spectrometry to simultaneously quantify endosomal markers, receptor-mediated transcytosis (RMT) receptors and the co-incubated antibodies in each fraction...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/29138439/abma-a-small-molecule-that-inhibits-intracellular-toxins-and-pathogens-by-interfering-with-late-endosomal-compartments
#13
Yu Wu, Valérie Pons, Amélie Goudet, Laetitia Panigai, Annette Fischer, Jo-Ana Herweg, Sabrina Kali, Robert A Davey, Jérôme Laporte, Céline Bouclier, Rahima Yousfi, Céline Aubenque, Goulven Merer, Emilie Gobbo, Roman Lopez, Cynthia Gillet, Sandrine Cojean, Michel R Popoff, Pascal Clayette, Roger Le Grand, Claire Boulogne, Noël Tordo, Emmanuel Lemichez, Philippe M Loiseau, Thomas Rudel, Didier Sauvaire, Jean-Christophe Cintrat, Daniel Gillet, Julien Barbier
Intracellular pathogenic microorganisms and toxins exploit host cell mechanisms to enter, exert their deleterious effects as well as hijack host nutrition for their development. A potential approach to treat multiple pathogen infections and that should not induce drug resistance is the use of small molecules that target host components. We identified the compound 1-adamantyl (5-bromo-2-methoxybenzyl) amine (ABMA) from a cell-based high throughput screening for its capacity to protect human cells and mice against ricin toxin without toxicity...
November 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29135085/retromer-and-the-cimpr-time-for-a-trial-separation
#14
Matthew N J Seaman
The retromer cargo-selective complex (CSC) comprising Vps35, Vps29 and Vps26 mediates the endosome-to-Golgi retrieval of the cation-independent mannose 6-phosphate receptor (CIMPR). Or does it? Recently published data has questioned the validity of this long established theory. Here the evidence for and against a role for the retromer CSC in CIMPR endosome-to-Golgi retrieval is examined in the light of the new data that the SNX-BAR dimer is actually responsible for CIMPR retrieval.
November 14, 2017: Traffic
https://www.readbyqxmd.com/read/29135058/distinct-features-of-multivesicular-body-lysosome-fusion-revealed-by-a-new-cell-free-content-mixing-assay
#15
Mahmoud Abdul Karim, Dieter Ronny Samyn, Sevan Mattie, Christopher Leonard Brett
When marked for degradation, surface receptor and transporter proteins are internalized and delivered to endosomes where they are packaged into intralumenal vesicles (ILVs). Many rounds of ILV formation create multivesicular bodies (MVBs) that fuse with lysosomes exposing ILVs to hydrolases for catabolism. Despite being critical for protein degradation, the molecular underpinnings of MVB-lysosome fusion remain unclear, although machinery underlying other lysosome fusion events is implicated. But how then is specificity conferred? And how is MVB maturation and fusion coordinated for efficient protein degradation? To address these questions, we developed a cell-free MVB-lysosome fusion assay using S...
November 14, 2017: Traffic
https://www.readbyqxmd.com/read/29134778/the-axonal-endoplasmic-reticulum-one-organelle-many-functions-in-development-maintenance-and-plasticity
#16
REVIEW
Alejandro Luarte, Víctor Hugo Cornejo, Francisca Bertin, Javiera Gallardo, Andrés Couve
The endoplasmic reticulum (ER) is highly conserved in eukaryotes and neurons. Indeed, the localization of the organelle in axons has been known for nearly half a century. However, the relevance of the axonal ER is only beginning to emerge. In this review, we discuss the structure of the ER in axons, examining the role of ER-shaping proteins and highlighting reticulons. We analyze the multiple functions of the ER and their potential contribution to axonal physiology. First, we examine the emerging roles of the axonal ER in lipid synthesis, protein translation, processing, quality control, and secretory trafficking of transmembrane proteins...
November 14, 2017: Developmental Neurobiology
https://www.readbyqxmd.com/read/29133526/involvement-of-g%C3%AE-%C3%AE-subunits-of-gi-protein-coupled-with-s1p-receptor-on-multivesicular-endosomes-in-f-actin-formation-and-cargo-sorting-into-exosomes
#17
Taketoshi Kajimoto, Nesma Nabil Ibrahim Mohamed, Shaymaa Mohamed Mohamed Badawy, Shubi Ambwene Matovelo, Mitsuhiro Hirase, Shunsuke Nakamura, Daisuke Yoshida, Taro Okada, Takeshi Ijuin, Shun-Ichi Nakamura
Exosomes play a critical role in cell-to-cell communication by delivering cargo molecules to recipient cells. However, the mechanism underlying the generation of the exosomal multivesicular endosome (MVE) is one of the mysteries in the field of endosome research. Although sphingolipid metabolites such as ceramide and sphingosine 1-phosphate (S1P) are known to play important roles in MVE formation and maturation, the detailed molecular mechanisms are still unclear. Here, we show that Rho family GTPases, including Cdc42 and Rac1, are constitutively activated on exosomal MVEs and are regulated by S1P signaling as measured by fluorescence resonance energy transfer (FRET)-based conformational changes...
November 13, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29133347/analysis-of-the-human-mucosal-response-to-cholera-reveals-sustained-activation-of-innate-immune-signaling-pathways
#18
Daniel L Bourque, Taufiqur Rahman Bhuiyan, Diane P Genereux, Rasheduzzaman Rashu, Crystal N Ellis, Fahima Chowdhury, Ashraful I Khan, Nur Haq Alam, Anik Paul Lazina Hossain, Leslie M Mayo-Smith, Richelle C Charles, Ana A Weil, Regina C LaRocque, Stephen B Calderwood, Edward T Ryan, Elinor K Karlsson, Firdausi Qadri, Jason B Harris
To better understand the innate immune response to Vibrio cholerae infection, we tracked gene expression in the duodenal mucosa of eleven Bangladeshi adults with cholera, using biopsies obtained immediately after rehydration and at 30 and 180 days later. We identified differentially expressed genes and performed an analysis to predict differentially regulated pathways and upstream regulators. During acute cholera, there was a broad increase in the expression of genes associated with innate immunity, including activation of the NF-κB, MAPK, and TLR-mediated signaling pathways, which unexpectedly persisted even 30 days after infection...
November 13, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/29131611/synthesis-and-in-vitro-evaluation-of-monodisperse-amino-functional-polyester-dendrimers-with-rapid-degradability-and-antibacterial-properties
#19
Patrik Stenström, Erik Hjort, Yuning Zhang, Oliver C J Andrén, Simon Guette-Marquet, Marianne Schultzberg, Michael Malkoch
Amine functional polymers, especially cationically charged, are interesting biomacromolecules for several reasons including easy cell membrane entrance, their ability to escape endosomes through the proton sponge effect, spontaneous complexation and delivery of drugs and siRNA and simple functionalization in aqueous solutions. Dendrimers, a subclass of precision polymers, are monodisperse and exhibit a large and exact number of peripheral end groups in relation to their size and have shown promise in drug delivery, biomedical imaging and as anti-viral agents...
November 13, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/29130884/ubiquitin-turnover-and-endocytic-trafficking-in-yeast-are-regulated-by-ser57-phosphorylation-of-ubiquitin
#20
Sora Lee, Jessica M Tumolo, Aaron C Ehlinger, Kristin K Jernigan, Susan J Qualls-Histed, Pi-Chiang Hsu, W Hayes McDonald, Walter J Chazin, Jason A MacGurn
Despite its central role in protein degradation little is known about the molecular mechanisms that sense, maintain, and regulate steady state concentration of ubiquitin in the cell. Here, we describe a novel mechanism for regulation of ubiquitin homeostasis that is mediated by phosphorylation of ubiquitin at the Ser57 position. We find that loss of Ppz phosphatase activity leads to defects in ubiquitin homeostasis that are at least partially attributable to elevated levels of Ser57 phosphorylated ubiquitin...
November 13, 2017: ELife
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