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Endocytic trafficking

Sara Calafate, William Flavin, Patrik Verstreken, Diederik Moechars
Tau pathology propagates within synaptically connected neuronal circuits, but the underlying mechanisms are unclear. BIN1-amphiphysin2 is the second most prevalent genetic risk factor for late-onset Alzheimer's disease. In diseased brains, the BIN1-amphiphysin2 neuronal isoform is downregulated. Here, we show that lowering BIN1-amphiphysin2 levels in neurons promotes Tau pathology propagation whereas overexpression of neuronal BIN1-amphiphysin2 inhibits the process in two in vitro models. Increased Tau propagation is caused by increased endocytosis, given our finding that BIN1-amphiphysin2 negatively regulates endocytic flux...
October 18, 2016: Cell Reports
Wei-Shan Hung, Pin Ling, Ju-Chien Cheng, Shy-Shin Chang, Ching-Ping Tseng
Toll-like receptor 4 (TLR4) plays a pivotal role in the host response to lipopolysaccharide (LPS), a major cell wall component of Gram-negative bacteria. Here, we elucidated whether the endocytic adaptor protein Disabled-2 (Dab2), which is abundantly expressed in macrophages, plays a role in LPS-stimulated TLR4 signaling and trafficking. Molecular analysis and transcriptome profiling of RAW264.7 macrophage-like cells expressing short-hairpin RNA of Dab2 revealed that Dab2 regulated the TLR4/TRIF pathway upon LPS stimulation...
October 17, 2016: Scientific Reports
Nicole Robbins, Michaela Spitzer, Wenliang Wang, Nicholas Waglechner, Dhruv J Patel, Jonathan S O'Brien, Linda Ejim, Obi Ejim, Mike Tyers, Gerard D Wright
Natural products are invaluable historic sources of drugs for infectious diseases; however, the discovery of novel antimicrobial chemical scaffolds has waned in recent years. Concurrently, there is a pressing need for improved therapeutics to treat fungal infections. We employed a co-culture screen to identify ibomycin, a large polyketide macrolactone that has preferential killing activity against Cryptococcus neoformans. Using chemical and genome methods, we determined the structure of ibomycin and identified the biosynthetic cluster responsible for its synthesis...
October 7, 2016: Cell Chemical Biology
Z Schultzhaus, T B Johnson, B D Shaw
Cell growth necessitates extensive membrane remodeling events including vesicle fusion or fission, processes that are regulated by coat proteins. The hyphal cells of filamentous fungi concentrate both exocytosis and endocytosis at the apex. This investigation focuses on clathrin in Aspergillus nidulans, with the aim of understanding its role in membrane remodeling in growing hyphae. We examined clathrin heavy chain (ClaH-GFP) which localized to three distinct subcellular structures: late Golgi (trans-Golgi equivalents of filamentous fungi), which are concentrated just behind the hyphal tip but are intermittently present throughout all hyphal cells; the region of concentrated endocytosis just behind the hyphal apex (the "endocytic collar"); and small, rapidly moving puncta that were seen trafficking long distances in nearly all hyphal compartments...
October 14, 2016: Molecular Microbiology
Yuantai Wu, Mehmet Takar, Andrea A Cuentas-Condori, Todd R Graham
NEO1 is an essential gene in budding yeast and belongs to a highly conserved subfamily of P-type ATPase genes that encode phospholipid flippases. Inactivation of temperature sensitive neo1(ts) alleles produces pleiomorphic defects in the secretory and endocytic pathways, including fragmented vacuoles. A screen for multicopy suppressors of neo1-2(ts) growth defects yielded YPT7, which encodes a Rab7 homolog involved in SNARE-dependent vacuolar fusion. YPT7 suppressed the vacuole fragmentation phenotype of neo1-2, but did not suppress Golgi-associated protein trafficking defects...
July 2016: Cellular Logistics
Xinxin Gao, Karen Stanger, Harini Kaluarachchi, Till Maurer, Paulina Ciepla, Cecile Chalouni, Yvonne Franke, Rami N Hannoush
Cyclotides or cyclic cystine-knot peptides have emerged as a promising class of pharmacological ligands that modulate protein function. Interestingly, very few cyclotides have been shown to enter into cells. Yet, it remains unknown whether backbone cyclization is required for their cellular internalization. In this report, we studied the cellular behavior of EETI-II, a model acyclic cystine-knot peptide. Even though synthetic methods have been used to generate EETI-II, recombinant methods that allow efficient large scale biosynthesis of EETI-II have been lagging...
October 13, 2016: Scientific Reports
Salvador Damián-Zamacona, Paola Toledo-Ibelles, Mabel Z Ibarra-Abundis, Laura Uribe-Figueroa, Enrique Hernández-Lemus, Karla Paola Macedo-Alcibia, Blanca Delgado-Coello, Jaime Mas-Oliva, Juan Pablo Reyes-Grajeda
BACKGROUND: Although nowadays it is well known that the human transcriptome can importantly vary according to external or environmental condition, the reflection of this concept when studying oxidative stress and its direct relationship with gene expression profiling during the process of atherogenesis has not been thoroughly achieved. OBJECTIVE: The ability to analyze genome-wide gene expression through transcriptomics has shown that the genome responds dynamically to diverse stimuli...
2016: PloS One
Maggy Hologne, François-Xavier Cantrelle, Gwladys Riviere, Florence Guillière, Xavier Trivelli, Olivier Walker
AMSH is one of the deubiquitinating enzymes associated in the regulation of endocytic cargo trafficking. It shows an exquisite selectivity for Lys63-linked polyubiquitin chains that are the main chains involved in cargo sorting. The first step requires the ESCRT-0 complex that comprises the STAM and Hrs proteins. Previous studies have shown that the presence of the STAM protein increases the efficiency of Lys63-linked polyubiquitin chain cleavage by AMSH, one of the deubiquitinating enzyme involved in lysosomal degradation...
October 7, 2016: Journal of Molecular Biology
Fangfei Qu, Damaris N Lorenzo, Samantha J King, Rebecca Brooks, James E Bear, Vann Bennett
Endosomal membrane trafficking requires coordination between phosphoinositide lipids, Rab GTPases, and microtubule-based motors to dynamically determine endosome identity and promote long-range organelle transport. Here we report that Ankyrin-B (AnkB), through integrating all three systems, functions as a critical node in the protein circuitry underlying polarized recycling of α5β1-integrin in mouse embryonic fibroblasts, which enables persistent fibroblast migration along fibronectin gradients. AnkB associates with phosphatidylinositol 3-phosphate (PI3P)-positive organelles in fibroblasts and binds dynactin to promote their long-range motility...
October 8, 2016: ELife
Franziska Wild, Muzamil Majid Khan, Tatjana Straka, Rüdiger Rudolf
Endocytosed nicotinic acetylcholine receptors (CHRN) are degraded via macroautophagy/autophagy during atrophic conditions and are accompanied by the autophagic regulator protein SH3GLB1. The present study addressed the functional role of SH3GLB1 on CHRN trafficking and its implementation. We found an augmented ratio of total SH3GLB1 to threonine-145 phosphorylated SH3GLB1 (SH3GLB1:p-SH3GLB1) under conditions of increased CHRN vesicle numbers. Overexpression of T145 phosphomimetic (T145E) and phosphodeficient (T145A) mutants of SH3GLB1, were found to either slow down or augment the processing of endocytic CHRN vesicles, respectively...
October 7, 2016: Autophagy
G Michael Rebmann, Robert Grabski, Veronica Sanchez, William J Britt
: Human cytomegalovirus (HCMV) is the largest member of the Herpesviridae and represents a significant cause of disease. During virus replication, HCMV alters cellular functions to facilitate its replication, including significant reorganization of the secretory and endocytic pathways of the infected cell. A defining morphologic change of the infected cell is the formation of a membranous structure in the cytoplasm that is designated the virion assembly compartment (AC), which consists of virion structural proteins surrounded by cellular membranes...
October 4, 2016: MBio
Xin-Chun Huang, Yuko Inoue-Aono, Yuji Moriyasu, Pei-Ying Hsieh, Wei-Ming Tu, Shae-Chien Hsiao, Wan-Neng Jane, Hsin-Yun Hsu
Autophagy is a self-protection process against reactive oxygen species (ROS). The intracellular level of ROS increased when cells were cultured under nutrient starvation. Antioxidants such as glutathione and ascorbic acid play an important role in ROS removal. However, the cellular redox state in the autophagic pathway is still unclear. Herein, we developed a new redox-sensitive probe with a disulfide-linked silica scaffold to enable the sensing of the reduction environment in cell organelles. This redox-responsive silica nanoprobe (ReSiN) could penetrate the plant cell wall and release fluorescent molecules in response to redox states...
October 6, 2016: Analytical Chemistry
Edward Málaga-Trillo, Katharina Ochs
Prions and Amyloid beta (Aβ) peptides induce synaptic damage via complex mechanisms that include the pathological alteration of intracellular signaling cascades. The host-encoded cellular prion protein (PrP(C)) acts as a high-affinity cell surface receptor for both toxic species and it can modulate the endocytic trafficking of the N-methyl D-aspartate (NMDA) receptor and E-cadherin adhesive complexes via Src family kinases (SFKs). Interestingly, SFK-mediated control of endocytosis is a widespread mechanism used to regulate the activity of important transmembrane proteins, including neuroreceptors for major excitatory and inhibitory neurotransmitters...
September 20, 2016: Prion
Emily H Stoops, Michael Hull, Michael J Caplan
Polarized epithelial cells sort newly synthesized and recycling plasma membrane proteins into distinct trafficking pathways directed to either the apical or basolateral membrane domains. While the trans Golgi network is a well-established site of protein sorting, increasing evidence indicates a key role for endosomes in the initial trafficking of newly synthesized proteins. Both basolateral and apical proteins have been shown to traverse endosomes en route to the plasma membrane. In particular, apical proteins traffic through either subapical early or recycling endosomes...
September 20, 2016: Traffic
Edward B Cluett, Paul de Figueiredo, Marie E Bechler, Kevin D Thorsen, William J Brown
The Golgi complex is the Grand Central Station of intracellular membrane trafficking in the secretory and endocytic pathways. Anterograde and retrograde export of cargo from the Golgi complex involves a complex interplay between the formation of coated vesicles and membrane tubules, although much less is known about tubule-mediated trafficking. Recent advances using in vitro assays have identified several cytoplasmic phospholipase A2 (PLA2) enzymes that are required for the biogenesis of membrane tubules and their roles in the functional organization of the Golgi complex...
2016: Methods in Molecular Biology
Chantel M Cadwell, Wenji Su, Andrew P Kowalczyk
Cadherins are the primary adhesion molecules in adherens junctions and desmosomes and play essential roles in embryonic development. Although significant progress has been made in understanding cadherin structure and function, we lack a clear vision of how cells confer plasticity upon adhesive junctions to allow for cellular rearrangements during development, wound healing, and metastasis. Endocytic membrane trafficking has emerged as a fundamental mechanism by which cells confer a dynamic state to adhesive junctions...
September 14, 2016: Traffic
J-Y Zhu, Y Xiong, W Zhang, J Wan, J Wan
Prostate cancer (Pca) is one of the most common types of cancer for elder men. Aberrant expression of epidermal growth factor receptor (EGFR) and EGFR downstream signaling have been known to contribute to disease progression in prostate cancer. EGF-stimulated EGFR is internalized and the process of endocytic degradation of EGFR mediates its signaling which is frequently dysregulated in many kinds of cancer. In the present study, we demonstrated that endophilin B1 expression was inhibited and EGFR expression was significantly increased in prostate cancer cell lines...
2016: Cellular and Molecular Biology
Chenchang Xu, Xiuping Fu, Shaoxia Zhu, Jia-Jia Liu
Retrolinkin, a neuronal membrane protein, coordinates with endophilin A1 and mediates early endocytic trafficking and signal transduction of the ligand-receptor complex formed between brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin related Kinase B (TrkB), in dendrites of CNS (CNS) neurons. Here we report that retrolinkin interacts with the CYFIP1/2 subunit of the WAVE1 complex, a member of the WASP/WAVE family of nucleation promoting factors (NPF) that binds and activates the Arp2/3 complex to promote branched actin polymerization...
September 7, 2016: Molecular Biology of the Cell
Govinda Sharma, Koji Tsutsumi, Taro Saito, Akiko Asada, Kanae Ando, Mineko Tomomura, Shin-Ichi Hisanaga
Neurite formation, a fundamental process in neuronal maturation, requires the coordinated regulation of cytoskeletal reorganization and membrane transport. Compared to the understanding of cytoskeletal functions, less is known about the supply of membranes to growing neurites. Lemur kinase 1A (LMTK1A) is an endosomal protein kinase that is highly expressed in neurons. We recently reported that LMTK1A regulates the trafficking of Rab11-positive recycling endosomes in growing axons and dendrites. Here, we used the kinase-negative (kn) mutant to investigate the role of the kinase activity of LMTK1A in its cellular localization and interactions with the cytoskeleton in Neuro2A and PC-12 cells...
October 2016: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
Linda Gräßel, Laura Aline Fast, Konstanze D Scheffer, Fatima Boukhallouk, Gilles A Spoden, Stefan Tenzer, Klaus Boller, Ruzica Bago, Sundaresan Rajesh, Michael Overduin, Fedor Berditchevski, Luise Florin
Human papillomaviruses enter host cells via a clathrin-independent endocytic pathway involving tetraspanin proteins. However, post-endocytic trafficking required for virus capsid disassembly remains unclear. Here we demonstrate that the early trafficking pathway of internalised HPV particles involves tetraspanin CD63, syntenin-1 and ESCRT-associated adaptor protein ALIX. Following internalisation, viral particles are found in CD63-positive endosomes recruiting syntenin-1, a CD63-interacting adaptor protein...
2016: Scientific Reports
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