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Thomas O Tolsma, Lena M Cuevas, Santiago M Di Pietro
Clathrin mediated endocytosis is a fundamental transport pathway that depends on numerous protein-protein interactions. Testing the importance of the adaptor protein-clathrin interaction for coat formation and progression of endocytosis in vivo has been difficult due to experimental constrains. Here we addressed this question using the yeast clathrin adaptor Sla1, which is unique in showing a cargo endocytosis defect upon substitution of three amino acids in its clathrin-binding motif (sla1AAA ) that disrupt clathrin binding...
March 15, 2018: Traffic
Oxana Nekrasova, Robert M Harmon, Joshua A Broussard, Jennifer L Koetsier, Lisa M Godsel, Gillian N Fitz, Margaret L Gardel, Kathleen J Green
The epidermis is a multi-layered epithelium that serves as a barrier against water loss and environmental insults. Its morphogenesis occurs through a tightly regulated program of biochemical and architectural changes during which basal cells commit to differentiate and move towards the skin's surface. Here, we reveal an unexpected role for the vertebrate cadherin desmoglein 1 (Dsg1) in remodeling the actin cytoskeleton to promote the transit of basal cells into the suprabasal layer through a process of delamination, one mechanism of epidermal stratification...
March 13, 2018: Nature Communications
David O Holland, Margaret E Johnson
Stoichiometric balance, or dosage balance, implies that proteins that are subunits of obligate complexes (e.g. the ribosome) should have copy numbers expressed to match their stoichiometry in that complex. Establishing balance (or imbalance) is an important tool for inferring subunit function and assembly bottlenecks. We show here that these correlations in protein copy numbers can extend beyond complex subunits to larger protein-protein interactions networks (PPIN) involving a range of reversible binding interactions...
March 8, 2018: PLoS Computational Biology
Lin Zhang, Changfu Hao, Sanqiao Yao, Rong Tang, Wei Guo, Hongbin Cong, Jiangfeng Li, Lei Bao, Di Wang, Yiping Li, Xinghao Yu, Shuyin Duan, Wu Yao
Inhaling a dangerous amount of nanoparticles leads to pulmonary inflammatory and immune disorders, which integrates several kinds of cells. Exosomes are suggested to play a crucial role in intercellular communication via miRNA transmission. To investigate the role of exosomal miRNA in nanoparticle phagocytosis, a total of 54 pneumoconiosis patients along with 100 healthy controls are recruited, exosomes derived from their venous blood are collected, and then exosomal miRNAs are profiled with high-throughput sequencing technology...
March 8, 2018: Small
Metello Innocenti
Lamellipodia and ruffles are veil-shaped cell protrusions composed by a highly branched actin filament meshwork assembled by the Arp2/3 complex. They not only hallmark the leading edge of cells adopting the adhesion-based mesenchymal mode of migration but are also thought to drive cell movement. Although regarded as textbook knowledge, the mechanism of formation of lamellipodia and ruffles has been revisited in the last years leveraging new technologies. Furthermore, recent observations have also challenged our current view of the function of lamellipodia and ruffles in mesenchymal cell migration...
March 7, 2018: Cell Adhesion & Migration
Melanie Laura Duncan, Jacquelyn Horsington, Preethi Eldi, Zahrah Al Rumaih, Gunasegaran Karupiah, Timothy P Newsome
Ectromelia virus (ECTV) is an orthopoxvirus and the causative agent of mousepox. Like other poxviruses such as variola virus (agent of smallpox), monkeypox virus and vaccinia virus (the live vaccine for smallpox), ECTV promotes actin-nucleation at the surface of infected cells during virus release. Homologs of the viral protein A36 mediate this function through phosphorylation of one or two tyrosine residues that ultimately recruit the cellular Arp2/3 actin-nucleating complex. A36 also functions in the intracellular trafficking of virus mediated by kinesin-1...
March 5, 2018: Viruses
Nadia Efimova, Tatyana M Svitkina
Adherens junctions (AJs) are mechanosensitive cadherin-based intercellular adhesions that interact with the actin cytoskeleton and carry most of the mechanical load at cell-cell junctions. Both Arp2/3 complex-dependent actin polymerization generating pushing force and nonmuscle myosin II (NMII)-dependent contraction producing pulling force are necessary for AJ morphogenesis. Which actin system directly interacts with AJs is unknown. Using platinum replica electron microscopy of endothelial cells, we show that vascular endothelial (VE)-cadherin colocalizes with Arp2/3 complex-positive actin networks at different AJ types and is positioned at the interface between two oppositely oriented branched networks from adjacent cells...
March 5, 2018: Journal of Cell Biology
Md Mohibbullah, Jae-Suk Choi, Mohammad Maqueshudul Haque Bhuiyan, Md Nazmul Haque, Md Khalilur Rahman, Il Soo Moon, Yong-Ki Hong
Exogenous neurotrophins can induce neuronal differentiation, outgrowth, survival, and synaptic function in the central nervous system. In primary cultures of rat hippocampal neurons, an ethanol extract of the red alga Gracilariopsis chorda (GCE) and its active compound arachidonic acid (AA) significantly increased the densities of dendritic filopodia and spines, promoted the expression of presynaptic vesicle protein 2 (SV2) and postsynaptic density protein 95 (PSD-95), induced robust synaptogenesis, and increased the expression of cell division control protein 42 (CDC42) and actin-related protein 2 (ARP2), which are important for actin organization in dendritic protrusions, and facilitated presynaptic plasticity by increasing the size of the synaptic vesicle pool at presynaptic nerve terminals...
March 2, 2018: Journal of Medicinal Food
Yixie Zhang, Tony J C Harris
Changes to cell shape and interaction drive animal tissue morphogenesis. Reporting now in Developmental Cell, Del Signore et al. (2018) describe active lengthening of cell-cell contacts by Arp2/3-based actin networks. Through cycles of contact lengthening and shortening, the developing Drosophila eye passes through various multicellular configurations to achieve its complex architecture.
February 26, 2018: Developmental Cell
Qing Deng, Yan-Xiao Tian, JianJun Liang
Breast tumour progression results from the advancement of the disease to a metastatic phenotype. Rac1 and Cdc42 belong to the Rho family of genes that, together with their downstream effectors, Wiskott-Aldrich Syndrome protein-family verprolin-homologous protein 2 (WAVE2) and Arp2/3, assume a vital part in cytoskeletal rearrangement and the arrangement of film projections that advance malignant cell relocation and invasion. Mangiferin is a characteristic polyphenolic compound from Mangifera indica L. (Anacardiaceae), ordinarily referred to as mango, that is consumed worldwide as a natural product, including culinary and seasoning applications...
February 17, 2018: Cytotechnology
Qing Wen, Elizabeth I Tang, Nan Li, Dolores D Mruk, Will M Lee, Bruno Silvestrini, C Yan Cheng
The blood-testis barrier (BTB) is an important ultrastructure in the testis that supports meiosis and postmeiotic spermatid development since a delay in the establishment of a functional Sertoli cell barrier during postnatal development in rats or mice by 17-20 day postpartum (dpp) would lead to a delay of the first wave of meiosis. Furthermore, irreversible disruption of the BTB by toxicants also induces infertility in rodents. Herein, we summarize recent findings that BTB dynamics (i.e., disassembly, reassembly, and stabilization) are supported by the concerted efforts of the actin- and microtubule (MT)-based cytoskeletons...
2018: Methods in Molecular Biology
Alexandre F Carisey, Emily M Mace, Mezida B Saeed, Daniel M Davis, Jordan S Orange
Natural killer (NK) cells are innate immune effectors that lyse virally infected and tumorigenic cells through the formation of an immunological synapse. Actin remodeling at the lytic immunological synapse is a critical requirement for multiple facets of cytotoxic function. Activating receptor and integrin signaling leads to the regulated turnover and remodeling of actin, which is required for adhesion, sustained receptor signaling, and ultimately exocytosis. NK cells undergo lytic granule exocytosis in hypodense regions of a pervasive actin network...
January 30, 2018: Current Biology: CB
Yuka Yamagishi, Kazumasa Oya, Akira Matsuura, Hiroshi Abe
Two types of Arp2/3 complex inhibitors, CK-666/636 and CK-548/869, are commonly used to study Arp2/3 complex-dependent actin assembly both in vitro and in vivo. However, we found that CK-548 and CK-869 directly suppress microtubule (MT) assembly independent of the actin cytoskeleton. Treatment of cultured mammalian cells with 50 μM CK-869 dramatically decreased MT networks and, instead, accumulated tubulin at the cell periphery, as did nocodazole that inhibits MT assembly. An in vitro MT-sedimentation assay revealed that CK-548 and CK-869 significantly suppressed MT polymerization...
January 27, 2018: Biochemical and Biophysical Research Communications
Qing Luan, Alex Zelter, Michael J MacCoss, Trisha N Davis, Brad J Nolen
Arp2/3 complex nucleates branched actin filaments important for cellular motility and endocytosis. WASP family proteins are Arp2/3 complex activators that play multiple roles in branching nucleation, but little is known about the structural bases of these WASP functions, owing to an incomplete understanding of how WASP binds Arp2/3 complex. Recent data show WASP binds two sites, and biochemical and structural studies led to models in which the WASP C segment engages the barbed ends of the Arp3 and Arp2 subunits while the WASP A segment binds the back side of the complex on Arp3...
February 13, 2018: Proceedings of the National Academy of Sciences of the United States of America
Matthias Schlau, Daniel Terheyden-Keighley, Verena Theis, Hans Georg Mannherz, Carsten Theiss
A crucial neuronal structure for the development and regeneration of neuronal networks is the axonal growth cone. Affected by different guidance cues, it grows in a predetermined direction to reach its final destination. One of those cues is the vascular endothelial growth factor (VEGF), which was identified as a positive effector for growth cone movement. These positive effects are mainly mediated by a reorganization of the actin network. This study shows that VEGF triggers a tight colocalization of cofilin and the Arp2/3 complex to the actin cytoskeleton within chicken dorsal root ganglia (DRG)...
January 27, 2018: International Journal of Molecular Sciences
Mehrdad Piran, Saeid Vakilian, Mehran Piran, Abdollah Mohammadi-Sangcheshmeh, Simzar Hosseinzadeh, Abdolreza Ardeshirylajimi
Migration of fibroblasts into wound area is a critical phenomenon in wound healing process. We used an appropriate system to fabricate an electrospun bioactive scaffold with controlled release of PDGF-BB in order to induce migration of primary skin fibroblast cells. First of all, protein-loaded chitosan nanoparticles based on ionic gelation interaction between chitosan and sodium tripolyphosphate were prepared. Then polycaprolactone electrospun fibers containing chitosan nanoparticles or PDGF-BB-loaded chitosan nanoparticles were prepared...
January 23, 2018: Artificial Cells, Nanomedicine, and Biotechnology
A Popinako, M Antonov, D Dibrova, A Chemeris, O S Sokolova
The Arp2/3 complex plays a key role in nucleating actin filaments branching. The glia maturation factor (GMF) competes with activators for interacting with the Arp2/3 complex and initiates the debranching of actin filaments. In this study, we performed a comparative analysis of interactions between GMF and the Arp2/3 complex and identified new amino acid residues involved in GMF binding to the Arp2/3 complex at two separate sites, revealed by X-ray and single particle EM techniques. Using molecular dynamics simulations we demonstrated the quantitative and qualitative changes in hydrogen bonds upon binding with GMF...
January 12, 2018: Biochemical and Biophysical Research Communications
Chien-Ting Wu, Hsin-Yi Chen, Tang K Tang
Primary cilia play essential roles in signal transduction and development. The docking of preciliary vesicles at the distal appendages of a mother centriole is an initial/critical step of ciliogenesis, but the mechanisms are unclear. Here, we demonstrate that myosin-Va mediates the transportation of preciliary vesicles to the mother centriole and reveal the underlying mechanism. We also show that the myosin-Va-mediated transportation of preciliary vesicles is the earliest event that defines the onset of ciliogenesis...
January 15, 2018: Nature Cell Biology
Spencer A Freeman, Anthony Vega, Magdalena Riedl, Richard F Collins, Phillip P Ostrowski, Elliot C Woods, Carolyn R Bertozzi, Markku I Tammi, Diane S Lidke, Pauline Johnson, Satyajit Mayor, Khuloud Jaqaman, Sergio Grinstein
Phagocytic receptors must diffuse laterally to become activated upon clustering by multivalent targets. Receptor diffusion, however, can be obstructed by transmembrane proteins ("pickets") that are immobilized by interacting with the cortical cytoskeleton. The molecular identity of these pickets and their role in phagocytosis have not been defined. We used single-molecule tracking to study the interaction between Fcγ receptors and CD44, an abundant transmembrane protein capable of indirect association with F-actin, hence likely to serve as a picket...
January 11, 2018: Cell
Ye Tu, Lichao Zhang, Lingchang Tong, Yue Wang, Su Zhang, Rongmei Wang, Ling Li, Zhibin Wang
Macrophage motility is vital in innate immunity, which contributes strategically to the defensive inflammation process. During bacterial infection, lipopolysaccharide (LPS) potently activates the migration of macrophages via the NF-κB/iNOS/c-Src signaling pathway. However, the downstream region of c-Src that participates in macrophage migration is unclear. EFhd2, a novel actin bundling protein, was evaluated for its role in LPS-stimulated macrophage migration in this study. We found that LPS stimulated the up-regulation, tyrosine phosphorylation and membrane translocation of EFhd2 in macrophages...
December 27, 2017: International Immunopharmacology
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