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Myosin IIA drives membrane bleb retraction.
Taneja N, Burnette DT
(2019) Mol Biol Cell 30: 1051-1059
MeSH Terms: Actins, Animals, Blister, COS Cells, Cell Membrane, Cell Membrane Structures, Cell Movement, Cell Surface Extensions, Chlorocebus aethiops, Cytokinesis, Cytoplasm, Cytoskeletal Proteins, HeLa Cells, Humans, Myosin Type II, Nerve Tissue Proteins, Nonmuscle Myosin Type IIA, Nonmuscle Myosin Type IIB
Show Abstract · Added March 27, 2019
Membrane blebs are specialized cellular protrusions that play diverse roles in processes such as cell division and cell migration. Blebbing can be divided into three distinct phases: bleb nucleation, bleb growth, and bleb retraction. Following nucleation and bleb growth, the actin cortex, comprising actin, cross-linking proteins, and nonmuscle myosin II (MII), begins to reassemble on the membrane. MII then drives the final phase, bleb retraction, which results in reintegration of the bleb into the cellular cortex. There are three MII paralogues with distinct biophysical properties expressed in mammalian cells: MIIA, MIIB, and MIIC. Here we show that MIIA specifically drives bleb retraction during cytokinesis. The motor domain and regulation of the nonhelical tailpiece of MIIA both contribute to its ability to drive bleb retraction. These experiments have also revealed a relationship between faster turnover of MIIA at the cortex and its ability to drive bleb retraction.
0 Communities
1 Members
0 Resources
18 MeSH Terms
MyTH4-FERM myosins in the assembly and maintenance of actin-based protrusions.
Weck ML, Grega-Larson NE, Tyska MJ
(2017) Curr Opin Cell Biol 44: 68-78
MeSH Terms: Actins, Animals, Cell Surface Extensions, Humans, Myosins, Pseudopodia
Show Abstract · Added April 7, 2017
Unconventional myosins are actin-based molecular motors that serve a multitude of roles within the cell. One group of myosin motors, the MyTH4-FERM myosins, play an integral part in building and maintaining finger-like protrusions, which allow cells to interact with their external environment. Suggested to act primarily as transporters, these motor proteins enrich adhesion molecules, actin-regulatory proteins and other factors at the tips of filopodia, microvilli, and stereocilia. Below we review data from biophysical, biochemical, and cell biological studies, which implicate these myosins as central players in the assembly, maintenance and function of actin-based protrusions.
Copyright © 2016 Elsevier Ltd. All rights reserved.
1 Communities
1 Members
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6 MeSH Terms
Role of iPLA(2) in the regulation of Src trafficking and microglia chemotaxis.
Lee SH, Schneider C, Higdon AN, Darley-Usmar VM, Chung CY
(2011) Traffic 12: 878-89
MeSH Terms: Adenosine Diphosphate, Animals, Arachidonic Acid, Biological Transport, Boron Compounds, Cell Line, Cell Membrane, Cell Surface Extensions, Chemotaxis, Endosomes, Enzyme Activation, Enzyme Inhibitors, Fluorescent Dyes, Focal Adhesions, Microglia, Phosphatidylinositol 3-Kinases, Phosphoinositide-3 Kinase Inhibitors, Phospholipases A2, Calcium-Independent, Recombinant Fusion Proteins, src-Family Kinases
Show Abstract · Added January 20, 2015
Microglia are immune effector cells in the central nervous system (CNS) and their activation, migration and proliferation play crucial roles in brain injuries and diseases. We examined the role of intracellular Ca(2+) -independent phospholipase A(2) (iPLA(2)) in the regulation of microglia chemotaxis toward ADP. Inhibition of iPLA(2) by 4-bromoenol lactone (BEL) or iPLA(2) knockdown exerted a significant inhibition on phosphatidylinositol-3-kinase (PI3K) activation and chemotaxis. Further examination revealed that iPLA(2) knockdown abrogated Src activation, which is required for PI3K activation and chemotaxis. Colocalization studies showed that cSrc-GFP was retained in the endosomal recycling compartment (ERC) in iPLA(2) knockdown cells, but the addition of arachidonic acid (AA) could restore cSrc trafficking to the plasma membrane by allowing the formation/release of recycling endosomes associated with cSrc-GFP. Using BODIPY-AA, we showed that AA is selectively enriched in recycling endosomes. These results suggest that AA is required for the cSrc trafficking to the plasma membrane by controlling the formation/release of recycling endosomes from the ERC.
© 2011 John Wiley & Sons A/S.
0 Communities
1 Members
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20 MeSH Terms
Cell-cell fusion: a new function for invadosomes.
Sung BH, Weaver A
(2011) Curr Biol 21: R121-3
MeSH Terms: Actins, Animals, Cell Membrane, Cell Surface Extensions, Drosophila, Drosophila Proteins, Membrane Fusion, Microfilament Proteins, Models, Biological, Wiskott-Aldrich Syndrome Protein
Show Abstract · Added May 19, 2014
Podosomes are cytoskeletal-based structures involved in extracellular matrix remodeling and cellular motility. A new study now implicates podosomes in pore formation during myoblast fusion.
Copyright © 2011 Elsevier Ltd. All rights reserved.
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1 Members
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10 MeSH Terms
Sensing and modulation of invadopodia across a wide range of rigidities.
Parekh A, Ruppender NS, Branch KM, Sewell-Loftin MK, Lin J, Boyer PD, Candiello JE, Merryman WD, Guelcher SA, Weaver AM
(2011) Biophys J 100: 573-582
MeSH Terms: Acrylic Resins, Animals, Basement Membrane, Biomechanical Phenomena, Cell Surface Extensions, Elastic Modulus, Extracellular Matrix, Microscopy, Atomic Force, Models, Biological, Polyurethanes, Pressure, Sus scrofa, Urinary Bladder
Show Abstract · Added December 5, 2013
Recent studies have suggested that extracellular matrix rigidity regulates cancer invasiveness, including the formation of cellular invadopodial protrusions; however, the relevant mechanical range is unclear. Here, we used a combined analysis of tissue-derived model basement membrane (BM) and stromal matrices and synthetic materials to understand how substrate rigidity regulates invadopodia. Urinary bladder matrix-BM (UBM-BM) was found to be a rigid material with elastic moduli of 3-8 MPa, as measured by atomic force microscopy and low-strain tensile testing. Stromal elastic moduli were ∼6-fold lower, indicating a more compliant material. Using synthetic substrates that span kPa-GPa moduli, we found a peak of invadopodia-associated extracellular matrix degradation centered around 30 kPa, which also corresponded to a peak in invadopodia/cell. Surprisingly, we observed another peak in invadopodia numbers at 2 GPa as well as gene expression changes that indicate cellular sensing of very high moduli. Based on the measured elastic moduli of model stroma and BM, we expected to find more invadopodia formation on the stroma, and this was verified on the stromal versus BM side of UBM-BM. These data suggest that cells can sense a wide range of rigidities, up into the GPa range. Furthermore, there is an optimal rigidity range for invadopodia activity that may be limited by BM rigidity.
Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.
3 Communities
4 Members
0 Resources
13 MeSH Terms
Myosin motor function: the ins and outs of actin-based membrane protrusions.
Nambiar R, McConnell RE, Tyska MJ
(2010) Cell Mol Life Sci 67: 1239-54
MeSH Terms: Actins, Animals, Cell Movement, Cell Surface Extensions, Humans, Myosins
Show Abstract · Added May 19, 2014
Cells build plasma membrane protrusions supported by parallel bundles of F-actin to enable a wide variety of biological functions, ranging from motility to host defense. Filopodia, microvilli and stereocilia are three such protrusions that have been the focus of intense biological and biophysical investigation in recent years. While it is evident that actin dynamics play a significant role in the formation of these organelles, members of the myosin superfamily have also been implicated as key players in the maintenance of protrusion architecture and function. Based on a simple analysis of the physical forces that control protrusion formation and morphology, as well as our review of available data, we propose that myosins play two general roles within these structures: (1) as cargo transporters to move critical regulatory components toward distal tips and (2) as mediators of membrane-cytoskeleton adhesion.
1 Communities
1 Members
0 Resources
6 MeSH Terms
Regulation of cancer invasion by reactive oxygen species and Tks family scaffold proteins.
Weaver AM
(2009) Sci Signal 2: pe56
MeSH Terms: Adaptor Proteins, Vesicular Transport, Animals, Cell Surface Extensions, Humans, NADPH Oxidases, Neoplasm Invasiveness, Neoplasms, Phosphoproteins, Reactive Oxygen Species
Show Abstract · Added March 5, 2014
Reactive oxygen species (ROS) are increasingly recognized as important signaling regulators. The family of the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox's) is responsible for the production of most signaling ROS in cells. An emerging paradigm is that individual Nox family members are organized and activated at distinct subcellular locations for specific functions. Tyrosine kinase substrate (Tks) family adaptor proteins have now been identified as Nox organizer proteins that enhance the production of ROS at invadopodia and podosomes, which are subcellular adhesion structures associated with extracellular matrix degradation. ROS production is also shown to be required for invadopodia and podosome formation. These findings broaden the known signaling roles of ROS and identify a potential mechanism for the correlation of ROS production with cancer invasion.
1 Communities
1 Members
0 Resources
9 MeSH Terms
SopB promotes phosphatidylinositol 3-phosphate formation on Salmonella vacuoles by recruiting Rab5 and Vps34.
Mallo GV, Espina M, Smith AC, Terebiznik MR, Alemán A, Finlay BB, Rameh LE, Grinstein S, Brumell JH
(2008) J Cell Biol 182: 741-52
MeSH Terms: Bacterial Proteins, Biological Transport, Cell Membrane, Cell Surface Extensions, Enzyme Activation, HeLa Cells, Humans, Models, Biological, Mutation, Phosphatidylinositol 3-Kinases, Phosphatidylinositol Phosphates, Phosphoinositide-3 Kinase Inhibitors, Protein Kinase Inhibitors, Salmonella, Vacuoles, rab5 GTP-Binding Proteins
Show Abstract · Added November 26, 2018
Salmonella colonizes a vacuolar niche in host cells during infection. Maturation of the Salmonella-containing vacuole (SCV) involves the formation of phosphatidylinositol 3-phosphate (PI(3)P) on its outer leaflet. SopB, a bacterial virulence factor with phosphoinositide phosphatase activity, was proposed to generate PI(3)P by dephosphorylating PI(3,4)P2, PI(3,5)P2, and PI(3,4,5)P3. Here, we examine the mechanism of PI(3)P formation during Salmonella infection. SopB is required to form PI(3,4)P2/PI(3,4,5)P3 at invasion ruffles and PI(3)P on nascent SCVs. However, we uncouple these events experimentally and reveal that SopB does not dephosphorylate PI(3,4)P2/PI(3,4,5)P3 to produce PI(3)P. Instead, the phosphatase activity of SopB is required for Rab5 recruitment to the SCV. Vps34, a PI3-kinase that associates with active Rab5, is responsible for PI(3)P formation on SCVs. Therefore, SopB mediates PI(3)P production on the SCV indirectly through recruitment of Rab5 and its effector Vps34. These findings reveal a link between phosphoinositide phosphatase activity and the recruitment of Rab5 to phagosomes.
0 Communities
1 Members
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16 MeSH Terms
Extracellular matrix rigidity promotes invadopodia activity.
Alexander NR, Branch KM, Parekh A, Clark ES, Iwueke IC, Guelcher SA, Weaver AM
(2008) Curr Biol 18: 1295-1299
MeSH Terms: Actin Cytoskeleton, Azepines, Cell Line, Tumor, Cell Surface Extensions, Crk-Associated Substrate Protein, Enzyme Inhibitors, Extracellular Matrix, Focal Adhesion Kinase 1, Gelatin, Heterocyclic Compounds, 4 or More Rings, Humans, Integrins, Myosin Type II, Myosin-Light-Chain Kinase, Naphthalenes, Signal Transduction
Show Abstract · Added March 5, 2014
Invadopodia are actin-rich subcellular protrusions with associated proteases used by cancer cells to degrade extracellular matrix (ECM) [1]. Molecular components of invadopodia include branched actin-assembly proteins, membrane trafficking proteins, signaling proteins, and transmembrane proteinases [1]. Similar structures exist in nontransformed cells, such as osteoclasts and dendritic cells, but are generally called podosomes and are thought to be more involved in cell-matrix adhesion than invadopodia [2-4]. Despite intimate contact with their ECM substrates, it is unknown whether physical or chemical ECM signals regulate invadopodia function. Here, we report that ECM rigidity directly increases both the number and activity of invadopodia. Transduction of ECM-rigidity signals depends on the cellular contractile apparatus [5-7], given that inhibition of nonmuscle myosin II, myosin light chain kinase, and Rho kinase all abrogate invadopodia-associated ECM degradation. Whereas myosin IIA, IIB, and phosphorylated myosin light chain do not localize to invadopodia puncta, active phosphorylated forms of the mechanosensing proteins p130Cas (Cas) and focal adhesion kinase (FAK) are present in actively degrading invadopodia, and the levels of phospho-Cas and phospho-FAK in invadopodia are sensitive to myosin inhibitors. Overexpression of Cas or FAK further enhances invadopodia activity in cells plated on rigid polyacrylamide substrates. Thus, in invasive cells, ECM-rigidity signals lead to increased matrix-degrading activity at invadopodia, via a myosin II-FAK/Cas pathway. These data suggest a potential mechanism, via invadopodia, for the reported correlation of tissue density with cancer aggressiveness.
2 Communities
3 Members
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16 MeSH Terms
Dependence of invadopodia function on collagen fiber spacing and cross-linking: computational modeling and experimental evidence.
Enderling H, Alexander NR, Clark ES, Branch KM, Estrada L, Crooke C, Jourquin J, Lobdell N, Zaman MH, Guelcher SA, Anderson AR, Weaver AM
(2008) Biophys J 95: 2203-18
MeSH Terms: Cell Line, Tumor, Cell Movement, Cell Surface Extensions, Collagen, Computer Simulation, Extracellular Matrix, Feedback, Physiological, Gelatin, Humans, Image Processing, Computer-Assisted, Microscopy, Electron, Microscopy, Fluorescence, Models, Biological
Show Abstract · Added October 31, 2013
Invadopodia are subcellular organelles thought to be critical for extracellular matrix (ECM) degradation and the movement of cells through tissues. Here we examine invadopodia generation, turnover, and function in relation to two structural aspects of the ECM substrates they degrade: cross-linking and fiber density. We set up a cellular automaton computational model that simulates ECM penetration and degradation by invadopodia. Experiments with denatured collagen (gelatin) were used to calibrate the model and demonstrate the inhibitory effect of ECM cross-linking on invadopodia degradation and penetration. Incorporation of dynamic invadopodia behavior into the model amplified the effect of cross-linking on ECM degradation, and was used to model feedback from the ECM. When the model was parameterized with spatial fibrillar dimensions that closely matched the organization, in real life, of native ECM collagen into triple-helical monomers, microfibrils, and macrofibrils, little or no inhibition of invadopodia penetration was observed in simulations of sparse collagen gels, no matter how high the degree of cross-linking. Experimental validation, using live-cell imaging of invadopodia in cells plated on cross-linked gelatin, was consistent with simulations in which ECM cross-linking led to higher rates of both invadopodia retraction and formation. Analyses of invadopodia function from cells plated on cross-linked gelatin and collagen gels under standard concentrations were consistent with simulation results in which sparse collagen gels provided a weak barrier to invadopodia. These results suggest that the organization of collagen, as it may occur in stroma or in vitro collagen gels, forms gaps large enough so as to have little impact on invadopodia penetration/degradation. By contrast, dense ECM, such as gelatin or possibly basement membranes, is an effective obstacle to invadopodia penetration and degradation, particularly when cross-linked. These results provide a novel framework for further studies on ECM structure and modifications that affect invadopodia and tissue invasion by cells.
2 Communities
3 Members
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13 MeSH Terms