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Manish K Rana, Francesca M Aloisio, Changhoon Choi, Diane L Barber
The role of distinct actin filaments architectures in epithelial plasticity remains incompletely understood. We, therefore, determined roles for formins and the Arp2/3 complex, which are actin nucleators generating unbranched and branched actin filaments, respectively, in the process of epithelial to mesenchymal transition (EMT). In clonal lung, mammary and renal epithelial cells, the formin activity inhibitor SMIFH2 but not the Arp2/3 complex activity inhibitor CK666 blocked EMT induced by TGF-β. SMIFH2 prevented the proximal signal of increased Smad2 phosphorylation, and hence also blocked downstream EMT markers, including actin filament remodeling, decreased expression of the adherens junction protein E-cadherin and increased expression of the matrix protein fibronectin and the transcription factor Snail...
April 18, 2018: Molecular Biology of the Cell
Tim B Fessenden, Yvonne Beckham, Mathew Perez-Neut, Guillermina Ramirez-San Juan, Aparajita H Chourasia, Kay F Macleod, Patrick W Oakes, Margaret L Gardel
Developing tissues change shape and tumors initiate spreading through collective cell motility. Conserved mechanisms by which tissues initiate motility into their surroundings are not known. We investigated cytoskeletal regulators during collective invasion by mouse tumor organoids and epithelial Madin-Darby canine kidney (MDCK) acini undergoing branching morphogenesis in collagen. Use of the broad-spectrum formin inhibitor SMIFH2 prevented the formation of migrating cell fronts in both cell types. Focusing on the role of the formin Dia1 in branching morphogenesis, we found that its depletion in MDCK cells does not alter planar cell motility either within the acinus or in two-dimensional scattering assays...
February 5, 2018: Journal of Cell Biology
Laura Weise-Cross, Michelle Sands, Joshua R Sheak, Brad R S Broughton, Jessica B Snow, Laura V Gonzalez Bosc, Nikki L Jernigan, Benjimen R Walker, Thomas C Resta
Chronic hypoxia (CH) augments basal and endothelin 1 (ET-1)-induced pulmonary vasoconstrictor reactivity through reactive oxygen species (ROS) generation and RhoA/Rho kinase (ROCK)-dependent myofilament Ca2+ sensitization. Because ROCK promotes actin polymerization and the actin cytoskeleton regulates smooth muscle tension, we hypothesized that actin polymerization is required for enhanced basal and ET-1-dependent vasoconstriction following CH. To test this hypothesis, both endpoints were monitored in pressurized, endothelium-disrupted pulmonary arteries (4th -5th order) from control and CH (4 wk at 0...
January 26, 2018: American Journal of Physiology. Heart and Circulatory Physiology
Angélica Aparecida Antoniellis Silveira, Venina Marcela Dominical, Camila Bononi Almeida, Hanan Chweih, Wilson Alves Ferreira, Cristina Pontes Vicente, Fabio Trindade Maranhão Costa, Claudio C Werneck, Fernando Ferreira Costa, Nicola Conran
Although essential for inflammatory responses, leukocyte recruitment to blood vessel walls in response to inflammatory stimuli, such as TNF-α, can contribute to vascular occlusion in inflammatory diseases, including atherosclerosis. We aimed to further characterize the mechanisms by which TNF stimulates adhesive and morphologic alterations in neutrophils. Microfluidic and intravital assays confirmed the potent effect that TNF has on human and murine neutrophil adhesion and recruitment in vitro and in vivo, respectively...
January 2018: Journal of Leukocyte Biology
Sreetama Basu, Irina Kustanovich, Raphael Lamprecht
The actin cytoskeleton is involved in key neuronal functions such as synaptic transmission and morphogenesis. However, the roles and regulation of actin cytoskeleton in memory formation remain to be clarified. In this study, we unveil the mechanism whereby actin cytoskeleton is regulated to form memory by exploring the roles of the major actin-regulatory proteins Arp2/3, VASP, and formins in long-term memory formation. Inhibition of Arp2/3, involved in actin filament branching and neuronal morphogenesis, in lateral amygdala (LA) with the specific inhibitor CK-666 during fear conditioning impaired long-term, but not short-term, fear memory...
November 2016: ENeuro
Megan A Ziske, Krista M Pettee, MaNada Khaing, Kaitlin Rubinic, Kathryn M Eisenmann
Due to a lack of effective screening or prevention protocol for epithelial ovarian cancer (EOC), there is a critical unmet need to develop therapeutic interventions for EOC treatment. EOC metastasis is unique. Initial dissemination is not primarily hematogenous, yet is facilitated through shedding of primary tumor cells into the peritoneal fluid and accumulating ascites. Increasingly, isolated patient spheroids point to a clinical role for spheroids in EOC metastasis. EOC spheroids are highly invasive structures that disseminate upon peritoneal mesothelium, and visceral tissues including liver and omentum...
March 25, 2016: Biochemical and Biophysical Research Communications
Amparo Rosero, Denisa Oulehlová, Lenka Stillerová, Petra Schiebertová, Michal Grunt, Viktor Žárský, Fatima Cvrčková
Plant cell morphogenesis involves concerted rearrangements of microtubules and actin microfilaments. We previously reported that FH1, the main Arabidopsis thaliana housekeeping Class I membrane-anchored formin, contributes to actin dynamics and microtubule stability in rhizodermis cells. Here we examine the effects of mutations affecting FH1 (At3g25500) on cell morphogenesis and above-ground organ development in seedlings, as well as on cytoskeletal organization and dynamics, using a combination of confocal and variable angle epifluorescence microscopy with a pharmacological approach...
March 2016: Plant & Cell Physiology
Sofya Borinskaya, Katrina B Velle, Kenneth G Campellone, Arthur Talman, Diego Alvarez, Hervé Agaisse, Yi I Wu, Leslie M Loew, Bruce J Mayer
The Nck adaptor protein recruits cytosolic effectors such as N-WASP that induce localized actin polymerization. Experimental aggregation of Nck SH3 domains at the membrane induces actin comet tails--dynamic, elongated filamentous actin structures similar to those that drive the movement of microbial pathogens such as vaccinia virus. Here we show that experimental manipulation of the balance between unbranched/branched nucleation altered the morphology and dynamics of Nck-induced actin comets. Inhibition of linear, formin-based nucleation with the small-molecule inhibitor SMIFH2 or overexpression of the formin FH1 domain resulted in formation of predominantly circular-shaped actin structures with low mobility (actin blobs)...
January 15, 2016: Molecular Biology of the Cell
Lingyan Cao, Jessica L Henty-Ridilla, Laurent Blanchoin, Christopher J Staiger
Actin filaments in plant cells are incredibly dynamic; they undergo incessant remodeling and assembly or disassembly within seconds. These dynamic events are choreographed by a plethora of actin-binding proteins, but the exact mechanisms are poorly understood. Here, we dissect the contribution of Arabidopsis (Arabidopsis thaliana) PROFILIN1 (PRF1), a conserved actin monomer-binding protein, to actin organization and single filament dynamics during axial cell expansion of living epidermal cells. We found that reduced PRF1 levels enhanced cell and organ growth...
January 2016: Plant Physiology
Jessica D Arden, Kari I Lavik, Kaitlin A Rubinic, Nicolas Chiaia, Sadik A Khuder, Marthe J Howard, Andrea L Nestor-Kalinoski, Arthur S Alberts, Kathryn M Eisenmann
The extensive invasive capacity of glioblastoma (GBM) makes it resistant to surgery, radiotherapy, and chemotherapy and thus makes it lethal. In vivo, GBM invasion is mediated by Rho GTPases through unidentified downstream effectors. Mammalian Diaphanous (mDia) family formins are Rho-directed effectors that regulate the F-actin cytoskeleton to support tumor cell motility. Historically, anti-invasion strategies focused upon mDia inhibition, whereas activation remained unexplored. The recent development of small molecules directly inhibiting or activating mDia-driven F-actin assembly that supports motility allows for exploration of their role in GBM...
November 1, 2015: Molecular Biology of the Cell
Yu M Efremov, A A Dokrunova, A V Efremenko, M P Kirpichnikov, K V Shaitan, O S Sokolova
The actin cytoskeleton is substantially modified in cancer cells because of changes in actin-binding protein abundance and functional activity. As a consequence, cancer cells have distinctive motility and mechanical properties, which are important for many processes, including invasion and metastasis. Here, we studied the effects of actin cytoskeleton alterations induced by specific nucleation inhibitors (SMIFH2, CK-666), cytochalasin D, Y-27632 and detachment from the surface by trypsinization on the mechanical properties of normal Vero and prostate cancer cell line DU145...
November 2015: Biochimica et Biophysica Acta
Tadamoto Isogai, Rob van der Kammen, Metello Innocenti
Formin proteins are key regulators of the cytoskeleton involved in developmental and homeostatic programs, and human disease. For these reasons, small molecules interfering with Formins' activity have gained increasing attention. Among them, small molecule inhibitor of Formin Homology 2 domains (SMIFH2) is often used as a pharmacological Formin blocker. Although SMIFH2 inhibits actin polymerization by Formins and affects the actin cytoskeleton, its cellular mechanism of action and target specificity remain unclear...
April 30, 2015: Scientific Reports
Hak-Cheol Kim, Yu-Jin Jo, Nam-Hyung Kim, Suk Namgoong
Dynamic actin reorganization is the main driving force for spindle migration and asymmetric cell division in mammalian oocytes. It has been reported that various actin nucleators including Formin-2 are involved in the polarization of the spindle and in asymmetric cell division. In mammals, the formin family is comprised of 15 proteins. However, their individual roles in spindle migration and/or asymmetric division have not been elucidated yet. In this study, we employed a newly developed inhibitor for formin family proteins, small molecule inhibitor of formin homology 2 domains (SMIFH2), to assess the functions of the formin family in mouse oocyte maturation...
2015: PloS One
Amparo Rosero, Viktor Žársky, Fatima Cvrčková
Plant cell growth and morphogenesis depend on remodelling of both actin and microtubule cytoskeletons. AtFH1 (At5g25500), the main housekeeping Arabidopsis formin, is targeted to membranes and known to nucleate and bundle actin. The effect of mutations in AtFH1 on root development and cytoskeletal dynamics was examined. Consistent with primarily actin-related formin function, fh1 mutants showed increased sensitivity to the actin polymerization inhibitor latrunculin B (LatB). LatB-treated mutants had thicker, shorter roots than wild-type plants...
January 2013: Journal of Experimental Botany
Syed A Rizvi, Erin M Neidt, Jiayue Cui, Zach Feiger, Colleen T Skau, Margaret L Gardel, Sergey A Kozmin, David R Kovar
Formins stimulate actin filament assembly for fundamental cellular processes including division, adhesion, establishing polarity, and motility. A formin inhibitor would be useful because most cells express multiple formins whose functions are not known and because metastatic tumor formation depends on the deregulation of formin-dependent processes. We identified a general small molecule inhibitor of formin homology 2 domains (SMIFH2) by screening compounds for the ability to prevent formin-mediated actin assembly in vitro...
November 25, 2009: Chemistry & Biology
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