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Joanna R Watson, Darerca Owen, Helen R Mott
The small GTPase, Cdc42, is a key regulator of actin dynamics, functioning to connect multiple signals to actin polymerization through effector proteins of the Wiskott-Aldrich syndrome protein (WASP) and Transducer of Cdc42-dependent actin assembly (TOCA) families. WASP family members serve to couple Cdc42 with the actin nucleator, the Arp2/3 complex, via direct interactions. The regulation of these proteins in the context of actin dynamics has been extensively studied. Studies on the TOCA family, however, are more limited and relatively little is known about their roles and regulation...
August 11, 2016: Small GTPases
Alberta Palazzo, Olivier Bluteau, Kahia Messaoudi, Francesco Marangoni, Yunhua Chang, Sylvie Souquere, Gérard Pierron, Valérie Lapierre, Yi Zheng, William Vainchenker, Hana Raslova, Najet Debili
BACKGROUND: Cytoskeleton rearrangements are essential in platelet release. The RHO small GTPase family, as regulators of the actin cytoskeleton, plays an important function in proplatelet formation. In the neuronal system, CDC42 is involved in the axone formation, a process that combined elongation and branching as proplatelet formation. OBJECTIVE: To analyze the role of CDC42 and its effectors of the WASP family on proplatelet formation METHODS: Human MKs were obtained from CD34(+) cells...
September 29, 2016: Journal of Thrombosis and Haemostasis: JTH
Xenia Snetkov, Ina Weisswange, Julia Pfanzelter, Ashley C Humphries, Michael Way
During its egress, vaccinia virus transiently recruits AP-2 and clathrin after fusion with the plasma membrane. This recruitment polarizes the viral protein A36 beneath the virus, enhancing actin polymerization and the spread of infection. We now demonstrate that three NPF motifs in the C-terminus of A36 recruit AP-2 and clathrin by interacting directly with the Epsin15 homology domains of Eps15 and intersectin-1. A36 is the first identified viral NPF motif containing protein shown to interact with endocytic machinery...
2016: Nature Microbiology
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
Peter J Wen, Staffan Grenklo, Gianvito Arpino, Xinyu Tan, Hsien-Shun Liao, Johanna Heureaux, Shi-Yong Peng, Hsueh-Cheng Chiang, Edaeni Hamid, Wei-Dong Zhao, Wonchul Shin, Tuomas Näreoja, Emma Evergren, Yinghui Jin, Roger Karlsson, Steven N Ebert, Albert Jin, Allen P Liu, Oleg Shupliakov, Ling-Gang Wu
Vesicle fusion is executed via formation of an Ω-shaped structure (Ω-profile), followed by closure (kiss-and-run) or merging of the Ω-profile into the plasma membrane (full fusion). Although Ω-profile closure limits release but recycles vesicles economically, Ω-profile merging facilitates release but couples to classical endocytosis for recycling. Despite its crucial role in determining exocytosis/endocytosis modes, how Ω-profile merging is mediated is poorly understood in endocrine cells and neurons containing small ∼30-300 nm vesicles...
2016: Nature Communications
Yufeng Tian, Xinyong Tian, Grzegorz Gawlak, Nicolene Sarich, David B Sacks, Anna A Birukova, Konstantin G Birukov
Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphatidylcholine (OxPAPC) attenuates agonist-induced endothelial cell (EC) permeability and increases pulmonary endothelial barrier function via enhancement of both the peripheral actin cytoskeleton and cell junctions mediated by Rac1 and Cdc42 GTPases. This study evaluated the role for the multifunctional Rac1/Cdc42 effector and regulator, IQGAP1, as a molecular transducer of the OxPAPC-mediated EC barrier enhancing signal. IQGAP1 knockdown in endothelial cells by gene-specific siRNA abolished OxPAPC-induced enlargement of VE-cadherin-positive adherens junctions, suppressed peripheral accumulation of actin polymerization regulators, namely cortactin, N-WASP and Arp3, and attenuated remodeling of the peripheral actin cytoskeleton...
August 26, 2016: American Journal of Physiology. Lung Cellular and Molecular Physiology
Pankaj Dubey, Seema Shirolikar, Krishanu Ray
Spermatogenesis occurs inside a somatic cell enclosure. Sperm release, the most important final step and a target for contraceptives, has been extensively studied in fixed tissue preparations. Here, we provide a time-lapse description of the release process in Drosophila testis ex vivo. We show that the spermatid tails exit the somatic enclosure and enter the testicular duct first, followed by the spermatid heads. Prior to this, individual spermatid heads attempt to invade the head cyst cell, and on each occasion they are repelled by a rapid and local F-actin polymerization response from the head cyst cell...
September 12, 2016: Developmental Cell
Zhen-Bo Wang, Xue-Shan Ma, Meng-Wen Hu, Zong-Zhe Jiang, Tie-Gang Meng, Ming-Zhe Dong, Li-Hua Fan, Ying-Chun Ouyang, Scott B Snapper, Heide Schatten, Qing-Yuan Sun
STUDY QUESTION: There is an unexplored physiological role of N-WASP (neural Wiskott-Aldrich syndrome protein) in oocyte maturation that prevents completion of second meiosis. SUMMARY ANSWER: In mice, N-WASP deletion did not affect oocyte polarity and asymmetric meiotic division in first meiosis, but did impair midbody formation and second meiosis completion. WHAT IS KNOWN ALREADY: N-WASP regulates actin dynamics and participates in various cell activities through the RHO-GTPase-Arp2/3 (actin-related protein 2/3 complex) pathway, and specifically the Cdc42 (cell division cycle 42)-N-WASP-Arp2/3 pathway...
September 2016: Molecular Human Reproduction
Liane Rauch, Kirsten Hennings, Claudia Trasak, Anja Röder, Barbara Schröder, Friedrich Koch-Nolte, Felix Rivera-Molina, Derek Toomre, Martin Aepfelbacher
Activation and invasion of the vascular endothelium by Staphylococcus aureus is a major cause of sepsis and endocarditis. For endothelial cell invasion, S. aureus triggers actin polymerization through Cdc42, N-WASp (also known as WASL) and the Arp2/3 complex to assemble a phagocytic cup-like structure. Here, we show that after stimulating actin polymerization staphylococci recruit Cdc42GAP (also known as ARHGAP1) which deactivates Cdc42 and terminates actin polymerization in the phagocytic cups. Cdc42GAP is delivered to the invading bacteria on recycling endocytic vesicles in concert with the exocyst complex...
August 1, 2016: Journal of Cell Science
Mao-Liang Chen, Fu-Ming Tsai, Ming-Cheng Lee, Yi-Yin Lin
Long-term administration of antipsychotic drugs (APDs) has been theorized to effect drug-induced changes in protein expression in the brain. Our previous findings revealed that ADPs can regulate Rho GDP-dissociation inhibitor 1 (RhoGDI1) expression in glial cells. To reveal whether APDs (haloperidol, risperidone, and clozapine) might regulate cell functions in rat brain by affecting RhoGDI1, RhoGDI1 regulation, RhoGDI1-related Rho family protein, and also MLC2 in brain of 7-day APD treatment rat were examined...
November 3, 2016: Progress in Neuro-psychopharmacology & Biological Psychiatry
G V Sharonov, M N Balatskaya, V A Tkachuk
Glycosylphosphatidylinositol-anchored proteins (GPI-AP) are important players in reception and signal transduction, cell adhesion, guidance, formation of immune synapses, and endocytosis. At that, a particular GPI-AP can have different activities depending on a ligand. It is known that GPI-AP oligomer creates a lipid raft in its base on plasma membrane, which serves as a signaling platform for binding and activation of src-family kinases. Yet, this does not explain different activities of GPI-APs. Meanwhile, it has been shown that short-lived actomyosin complexes are bound to GPI-APs through lipid rafts...
June 2016: Biochemistry. Biokhimii︠a︡
Z I Krutetskaya, A V Melnitskaya, V G Antonov, A D Nozdrachev
Using voltage-clamp technique, the involvement of WASP proteins and Arp2/3 complex in the effect of immunomodulator drug glutoxim on Na(+) transport in frog skin was investigated. It was shown for the first time that preincubation of the skin with the N-WASP inhibitor wiskostatin or the Arp2/3 complex inhibitor CK-0944666 significantly decreases the stimulatory effect of glutoxim on Na(+) transport. The data suggest the involvement of actin filament polymerization and branching in the glutoxim effect on Na(+) transport in frog skin...
March 2016: Doklady. Biochemistry and Biophysics
Neeraj Jain, Lee Wei Lim, Wei Ting Tan, Bhawana George, Eugene Makeyev, Thirumaran Thanabalu
No abstract text is available yet for this article.
May 13, 2016: Experimental Neurology
Joel Oppliger, Giulia Torriani, Antonio Herrador, Stefan Kunz
UNLABELLED: The pathogenic Old World arenavirus Lassa virus (LASV) causes a severe hemorrhagic fever with a high rate of mortality in humans. Several LASV receptors, including dystroglycan (DG), TAM receptor tyrosine kinases, and C-type lectins, have been identified, suggesting complex receptor use. Upon receptor binding, LASV enters the host cell via an unknown clathrin- and dynamin-independent pathway that delivers the virus to late endosomes, where fusion occurs. Here we investigated the mechanisms underlying LASV endocytosis in human cells in the context of productive arenavirus infection, using recombinant lymphocytic choriomeningitis virus (rLCMV) expressing the LASV glycoprotein (rLCMV-LASVGP)...
July 15, 2016: Journal of Virology
Kurchi Bhattacharya, Karthic Swaminathan, Vivek S Peche, Christoph S Clemen, Philipp Knyphausen, Michael Lammers, Angelika A Noegel, Raphael H Rastetter
The contribution of the actin cytoskeleton to the unique architecture of the Golgi complex is manifold. An important player in this process is Coronin7 (CRN7), a Golgi-resident protein that stabilizes F-actin assembly at the trans-Golgi network (TGN) thereby facilitating anterograde trafficking. Here, we establish that CRN7-mediated association of F-actin with the Golgi apparatus is distinctly modulated via the small Rho GTPase Cdc42 and N-WASP. We identify N-WASP as a novel interaction partner of CRN7 and demonstrate that CRN7 restricts spurious F-actin reorganizations by repressing N-WASP 'hyperactivity' upon constitutive Cdc42 activation...
2016: Scientific Reports
Joanna R Watson, Helen M Fox, Daniel Nietlispach, Jennifer L Gallop, Darerca Owen, Helen R Mott
Transducer of Cdc42-dependent actin assembly protein 1 (TOCA1) is an effector of the Rho family small G protein Cdc42. It contains a membrane-deforming F-BAR domain as well as a Src homology 3 (SH3) domain and a G protein-binding homology region 1 (HR1) domain. TOCA1 binding to Cdc42 leads to actin rearrangements, which are thought to be involved in processes such as endocytosis, filopodia formation, and cell migration. We have solved the structure of the HR1 domain of TOCA1, providing the first structural data for this protein...
June 24, 2016: Journal of Biological Chemistry
Jorge Eduardo Shortrede, Ivonne Denise Uzair, Flavia Judith Neira, Marina Inés Flamini, Angel Matías Sanchez
Breast cancer is the major cause of cancer-related death in women. Its treatment is particularly difficult when metastasis occurs. The ability of cancer cells to move and invade the surrounding environment is the basis of local and distant metastasis. Cancer cells are able to remodel the actin cytoskeleton, which requires the recruitment of numerous structural and regulatory proteins that modulate actin filaments dynamics, including Paxillin or the Neural Wiskott-Aldrich Syndrome Protein (N-WASP). We show that 17-β estradiol (E2) induces phosphorylation of Paxillin and its translocation toward membrane sites where focal adhesion complexes are assembled...
July 15, 2016: Molecular and Cellular Endocrinology
Wenwu Zhang, Youliang Huang, Susan J Gunst
KEY POINTS: In airway smooth muscle, tension development caused by a contractile stimulus requires phosphorylation of the 20 kDa myosin light chain (MLC), which activates crossbridge cycling and the polymerization of a pool of submembraneous actin. The p21-activated kinases (Paks) can regulate the contractility of smooth muscle and non-muscle cells, and there is evidence that this occurs through the regulation of MLC phosphorylation. We show that Pak has no effect on MLC phosphorylation during the contraction of airway smooth muscle, and that it regulates contraction by mediating actin polymerization...
September 1, 2016: Journal of Physiology
Brant M Wagener, Meng Hu, Anni Zheng, Xueke Zhao, Pulin Che, Angela Brandon, Naseem Anjum, Scott Snapper, Judy Creighton, Jun-Lin Guan, Qimei Han, Guo-Qiang Cai, Xiaosi Han, Jean-Francois Pittet, Qiang Ding
TGF-β1 induces an increase in paracellular permeability and actin stress fiber formation in lung microvascular endothelial and alveolar epithelial cells via small Rho GTPase. The molecular mechanism involved is not fully understood. Neuronal Wiskott-Aldrich syndrome protein (N-WASP) has an essential role in actin structure dynamics. We hypothesized that N-WASP plays a critical role in these TGF-β1-induced responses. In these cell monolayers, we demonstrated that N-WASP down-regulation by short hairpin RNA prevented TGF-β1-mediated disruption of the cortical actin structure, actin stress filament formation, and increased permeability...
July 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Hervé Agaisse
The intracellular pathogen Shigella flexneri is the causative agent of bacillary dysentery in humans. The disease is characterized by bacterial invasion of intestinal cells, dissemination within the colonic epithelium through direct spread from cell to cell, and massive inflammation of the intestinal mucosa. Here, we review the mechanisms supporting S. flexneri dissemination. The dissemination process primarily relies on actin assembly at the bacterial pole, which propels the pathogen throughout the cytosol of primary infected cells...
2016: Frontiers in Cellular and Infection Microbiology
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