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Frédéric Adam, Alexandre Kauskot, Mathieu Kurowska, Nicolas Goudin, Isabelle Munoz, Jean-Claude Bordet, Jian-Dong Huang, Marijke Bryckaert, Alain Fischer, Delphine Borgel, Geneviève de Saint Basile, Olivier D Christophe, Gaël Ménasché
OBJECTIVE: Platelet secretion is crucial for many physiological platelet responses. Even though several regulators of the fusion machinery for secretory granule exocytosis have been identified in platelets, the underlying mechanisms are not yet fully characterized. APPROACH AND RESULTS: By studying a mouse model (cKO [conditional knockout]Kif5b ) lacking Kif5b (kinesin-1 heavy chain) in its megakaryocytes and platelets, we evidenced unstable hemostasis characterized by an increase of blood loss associated to a marked tendency to rebleed in a tail-clip assay and thrombus instability in an in vivo thrombosis model...
March 8, 2018: Arteriosclerosis, Thrombosis, and Vascular Biology
Matías A Bustos, Ornella Lucchesi, María C Ruete, Claudia N Tomes
The acrosome reaction is the regulated exocytosis of mammalian sperm's single secretory granule, essential for fertilization. It relies on small GTPases, the cAMP binding protein Epac, and the SNARE complex, among other components. Here, we describe a novel tool to investigate Rab27-related signaling pathways: a hybrid recombinant protein consisting of human Rab27A fused to TAT, a cell penetrating peptide. With this tool, we aimed to unravel the connection between Rab3, Rab27 and Rap1 in sperm exocytosis and to deepen our understanding about how isoprenylation and guanine nucleotides influence the behaviour of Rab27 in exocytosis...
April 2018: Cellular Signalling
Pin Li, Guoqin Wei, Yang Cao, Qiuping Deng, Xiaofan Han, Xiaoshuai Huang, Yingqing Huo, Yulong He, Liangyi Chen, Jincai Luo
Nonmuscle myosin II has been implicated in regulation of von Willebrand factor (VWF) release from endothelial Weibel-Palade bodies (WPBs), but the specific role of myosin IIa isoform is poorly defined. Here, we report that myosin IIa is expressed both in primary human endothelial cells and intact mouse vessels, essential for cyclic adenosine monophosphate (cAMP)-mediated endothelial VWF secretion. Downregulation of myosin IIa by shRNAs significantly suppressed both forskolin- and epinephrine-induced VWF secretion...
February 8, 2018: Blood
Margaret Alexander, Andrew G Ramstead, Kaylyn M Bauer, Soh-Hyun Lee, Marah C Runtsch, Jared Wallace, Thomas B Huffaker, Dane K Larsen, Tanya Tolmachova, Miguel C Seabra, June L Round, Diane M Ward, Ryan M O'Connell
Extracellular vesicles, including exosomes, have recently been implicated as novel mediators of immune cell communication in mammals. However, roles for endogenously produced exosomes in regulating immune cell functions in vivo are just beginning to be identified. In this article, we demonstrate that Rab27a and Rab27b double-knockout (Rab27DKO) mice that are deficient in exosome secretion have a chronic, low-grade inflammatory phenotype characterized by elevated inflammatory cytokines and myeloproliferation...
November 15, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
Tara Capece, Brandon L Walling, Kihong Lim, Kyun-Do Kim, Seyeon Bae, Hung-Li Chung, David J Topham, Minsoo Kim
The integrin lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18) is a key T cell adhesion receptor that mediates stable interactions with antigen-presenting cell (APC), as well as chemokine-mediated migration. Using our newly generated CD11a-mYFP knock-in mice, we discovered that naive CD8+ T cells reserve a significant intracellular pool of LFA-1 in the uropod during migration. Intracellular LFA-1 quickly translocated to the cell surface with antigenic stimulus. Importantly, the redistribution of intracellular LFA-1 at the contact with APC was maintained during cell division and led to an unequal inheritance of LFA-1 in divided T cells...
November 6, 2017: Journal of Cell Biology
Fushun Fan, Kohichi Matsunaga, Hao Wang, Ray Ishizaki, Eri Kobayashi, Hiroshi Kiyonari, Yoshiko Mukumoto, Katsuhide Okunishi, Tetsuro Izumi
Exophilin-8 has been reported to play a role in anchoring secretory granules within the actin cortex, due to its direct binding activities to Rab27 on the granule membrane and to F-actin and its motor protein, myosin-Va. Here, we show that exophilin-8 accumulates granules in the cortical F-actin network not by direct interaction with myosin-Va, but by indirect interaction with a specific form of myosin-VIIa through its previously unknown binding partner, RIM-BP2. RIM-BP2 also associates with exocytic machinery, Cav1...
July 4, 2017: ELife
Christian Ostalecki, Jung-Hyun Lee, Jochen Dindorf, Lena Collenburg, Stephan Schierer, Beate Simon, Stefan Schliep, Elisabeth Kremmer, Gerold Schuler, Andreas S Baur
The evolution of cancer is characterized by the appearance of specific mutations, but these mutations are translated into proteins that must cooperate to induce malignant transformation. Using a systemic approach with the multiepitope ligand cartography (MELC) technology, we analyzed protein expression profiles (PEPs) in nevi and BRAFV600E -positive superficial spreading melanomas (SSMs) from patient tissues to identify key transformation events. The PEPs in nevi and SSMs differed predominantly in the abundance of specific antigens, but the PEPs of nevi- and melanoma-associated keratinocytes gradually changed during the transformation process...
March 14, 2017: Science Signaling
Jinxie Zhang, Danfeng Chang, Yao Yang, Xudong Zhang, Wei Tao, Lijuan Jiang, Xin Liang, Hsiangi Tsai, Laiqiang Huang, Lin Mei
Polymeric nanoparticles such as PLGA-based nanoparticles are emerging as promising carriers for controlled drug delivery. However, little is known about the intracellular trafficking network of polymeric nanoparticles. Here, more than 30 Rab proteins were used as markers of multiple trafficking vesicles in endocytosis, exocytosis and autophagy to investigate in detail the intracellular trafficking pathways of PLGA nanoparticles. We observed that coumarin-6-loaded PLGA nanoparticles were internalized by the cells mainly through caveolin and clathrin-dependent endocytosis and Rab34-mediated macropinocytosis...
February 22, 2017: Nanoscale
Javier Chinen, Luigi D Notarangelo, William T Shearer
Advances in clinical immunology in the past year included the report of practice parameters for the diagnosis and management of primary immunodeficiencies to guide the clinician in the approach to these relatively uncommon disorders. We have learned of new gene defects causing immunodeficiency and of new phenotypes expanding the spectrum of conditions caused by genetic mutations such as a specific regulator of telomere elongation (RTEL1) mutation causing isolated natural killer cell deficiency and mutations in ras-associated RAB (RAB27) resulting in immunodeficiency without albinism...
December 2016: Journal of Allergy and Clinical Immunology
Joana G Silva, Nuno P Martins, Ricardo Henriques, Helena Soares
The ability of HIV-1 to replicate and to establish long-term reservoirs is strongly influenced by T cell activation. Through the use of membrane-tethered, genetically encoded calcium (Ca(2+)) indicators, we were able to detect for the first time, to our knowledge, the formation of Ca(2+) territories and determine their role in coordinating the functional signaling nanostructure of the synaptic membrane. Consequently, we report a previously unknown immune subversion mechanism involving HIV-1 exploitation, through its Nef accessory protein, of the interconnectivity among three evolutionarily conserved cellular processes: vesicle traffic, signaling compartmentalization, and the second messenger Ca(2+) We found that HIV-1 Nef specifically associates with the traffic regulators MAL and Rab11b compelling the vesicular accumulation of Lck...
November 15, 2016: Journal of Immunology: Official Journal of the American Association of Immunologists
Christian Ostalecki, Sebastian Wittki, Jung-Hyun Lee, Miriam M Geist, Nadine Tibroni, Thomas Harrer, Gerold Schuler, Oliver T Fackler, Andreas S Baur
Tumor necrosis factor (TNF) is a key cytokine in HIV replication and pathogenesis. For reasons that are not entirely clear, the cytokine remains upregulated despite anti-retroviral therapy (ART). Here we demonstrate that HIV Nef induces an alternative TNF secretion mechanism that remains active in chronic infection. Ingestion of Nef-containing plasma extracellular vesicles (pEV) from ART patients by primary immune cells, but also Nef expression, induced intracellular proTNF cleavage and secretion of vesicular TNF endosomes...
November 2016: EBioMedicine
Angela R M Kurz, Monika Pruenster, Ina Rohwedder, Mahalakshmi Ramadass, Kerstin Schäfer, Ute Harrison, Gabriel Gouveia, Claudia Nussbaum, Roland Immler, Johannes R Wiessner, Andreas Margraf, Dae-Sik Lim, Barbara Walzog, Steffen Dietzel, Markus Moser, Christoph Klein, Dietmar Vestweber, Rainer Haas, Sergio D Catz, Markus Sperandio
Neutrophils need to penetrate the perivascular basement membrane for successful extravasation into inflamed tissue, but this process is incompletely understood. Recent findings have associated mammalian sterile 20-like kinase 1 (MST1) loss of function with a human primary immunodeficiency disorder, suggesting that MST1 may be involved in immune cell migration. Here, we have shown that MST1 is a critical regulator of neutrophil extravasation during inflammation. Mst1-deficient (Mst1-/-) neutrophils were unable to migrate into inflamed murine cremaster muscle venules, instead persisting between the endothelium and the basement membrane...
November 1, 2016: Journal of Clinical Investigation
Adam J Trexler, Kem A Sochacki, Justin W Taraska
How and when the dozens of molecules that control exocytosis assemble in living cells to regulate the fusion of a vesicle with the plasma membrane is unknown. Here we image with two-color total internal reflection fluorescence microscopy the local changes of 27 proteins at single dense-core vesicles undergoing calcium-triggered fusion. We identify two broad dynamic behaviors of exocytic molecules. First, proteins enriched at exocytic sites are associated with DCVs long before exocytosis, and near the time of membrane fusion, they diffuse away...
August 1, 2016: Molecular Biology of the Cell
Zhen Meng, Maria C Edman, Pang-Yu Hsueh, Chiao-Yu Chen, Wannita Klinngam, Tanya Tolmachova, Curtis T Okamoto, Sarah F Hamm-Alvarez
The mechanism responsible for the altered spectrum of tear proteins secreted by lacrimal gland acinar cells (LGAC) in patients with Sjögren's Syndrome (SS) remains unknown. We have previously identified increased cathepsin S (CTSS) activity as a unique characteristic of tears of patients with SS. Here, we investigated the role of Rab3D, Rab27a, and Rab27b proteins in the enhanced release of CTSS from LGAC. Similar to patients with SS and to the male nonobese diabetic (NOD) mouse model of SS, CTSS activity was elevated in tears of mice lacking Rab3D...
June 1, 2016: American Journal of Physiology. Cell Physiology
Kouichi Mizuno, Takuji Fujita, Hiroshi Gomi, Tetsuro Izumi
In regulated exocytosis, it is generally assumed that vesicles must stably "dock" at the plasma membrane before they are primed to become fusion-competent. However, recent biophysical analyses in living cells that visualize fluorescent secretory granules have revealed that exocytic behaviors are not necessarily uniform: some granules beneath the plasma membrane are resistant to Ca(2+)-triggered release, while others are accelerated to fuse without a pause for stable docking. These findings suggest that stable docking is unnecessary, and can even be inhibitory or nonfunctional, for fusion...
April 1, 2016: Scientific Reports
Tomohide Uno, Masayuki Furutani, Chihiro Watanabe, Katsuhiko Sakamoto, Yuichi Uno, Kengo Kanamaru, Hiroshi Yamagata, Akira Mizoguchi, Makio Takeda
In eukaryotic cells, Rab guanosine triphosphate-ases serve as key regulators of membrane-trafficking events, such as exocytosis and endocytosis. Rab3, Rab6, and Rab27 control the regulatory secretory pathway of neuropeptides and neurotransmitters. The cDNAs of Rab3, Rab6, and Rab27 from B. mori were inserted into a plasmid, transformed into Escherichia coli, and then subsequently purified. We then produced antibodies against Rab3, Rab6, and Rab27 of Bombyx mori in rabbits and rats for use in western immunoblotting and immunohistochemistry...
July 2016: Histochemistry and Cell Biology
Hironori Higashio, Yoh-ichi Satoh, Tomoyuki Saino
Mast cell degranulation is regulated by the small guanosine triphosphatases (GTPases) Rab27a and Rab27b, which have distinct and opposing roles: Rab27b acts as a positive regulator through its effector protein Munc13-4, a non-neuronal isoform of the vesicle-priming Munc13 family of proteins, whereas Rab27a acts as a negative regulator through its effector protein melanophilin, by maintaining integrity of cortical filamentous actin (F-actin), a barrier to degranulation. Here we investigated the role of Rab37, one of the Rab GTPases assumed to be implicated in regulated secretion during mast cell degranulation...
March 2, 2016: Scientific Reports
Weiwei Dong, Jiantao Cui, Jingwen Yang, Wenmei Li, Shuo Wang, Xiaojuan Wang, Xing Li, Youyong Lu, Wenhua Xiao
The Rab27 subfamily of secretory small GTPase plays a vital role in vesicle trafficking and regulates tumor growth and metastasis in several cancer types. Thus, this research was designed to explore the clinical and prognostic significance of Rab27A and Rab27B in colorectal cancer (CRC) patients. Reverse transcription-polymerase chain reaction (RT-PCR), western blot, and immunohistochemistry (IHC) analysis were used to examine Rab27A and Rab27B expression in human CRC cell lines and primary tumors. The correlation of gene expression with clinicopathological features and prognosis was also evaluated...
December 2015: Discovery Medicine
Rajshekhar A Kore, Edathara C Abraham
Exosomes mediate secretion of crystallin alphaB (cryAB), a well characterized molecular chaperone with anti-apoptotic activity. However, the mechanisms governing its packaging and secretion remained unexplored. In glioma cells, notwithstanding extensive phosphorylation of cryAB at Ser59 followed by Ser45 (Ser19 is largely unphosphorylated), we discovered that the majority of secreted exosomal cryAB is nonphosphorylated. Transient ectopic expression of a yellow fluorescent protein (YFP) tagged triple phosphomimic (3-SD) cryAB construct in cryAB absent glioma cells led to the formation of large cytosolic inclusions...
February 2016: Biochimica et Biophysica Acta
Yuan Lu, Mikki Bowswell, William Bowswell, Kuan Yang, Manfred Schartl, Ronald B Walter
The phenotypic and genetic similarities between Xiphophorus and human melanoma render Xiphophorus a useful animal model for studying the genetic basis of melanoma etiology. In the Xiphophorus model, melanoma has been shown to be inducible by ultraviolet light (UVB) exposure among interspecies hybrids, but not in parental line fish similarly treated. This leads to questions of what genes are responsive to UVB exposure in the skin of the interspecies hybrids, as well as how parental alleles in hybrids may be differentially regulated and the potential roles they may play in induced melanomagenesis...
December 2015: Comparative Biochemistry and Physiology. Toxicology & Pharmacology: CBP
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