The Experts below are selected from a list of 26973 Experts worldwide ranked by ideXlab platform
Kathleen G Morgan - One of the best experts on this subject based on the ideXlab platform.
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Actin Polymerization in differentiated vascular smooth muscle cells requires vasodilator stimulated phosphoprotein
American Journal of Physiology-cell Physiology, 2010Co-Authors: Philip Graceffa, Francois Ferron, Cynthia Gallant, Malgorzata Boczkowska, Roberto Dominguez, Kathleen G MorganAbstract:Our group has previously shown that vasoconstrictors increase net Actin Polymerization in differentiated vascular smooth muscle cells (dVSMC) and that increased Actin Polymerization is linked to co...
Evelyne Friederich - One of the best experts on this subject based on the ideXlab platform.
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acta and human zyxin harbour arp2 3 independent Actin Polymerization activity
Nature Cell Biology, 2001Co-Authors: Julie Fradelizi, Daniel Louvard, Cécile Sykes, Vincent Noireaux, Julie Plastino, Bernadette Menichi, Roy M Golsteyn, Evelyne FriederichAbstract:The Actin cytoskeleton is a dynamic network that is composed of a variety of F-Actin structures. To understand how these structures are produced, we tested the capacity of proteins to direct Actin Polymerization in a bead assay in vitro and in a mitochondrial-targeting assay in cells. We found that human zyxin and the related protein ActA of Listeria monocytogenes can generate new Actin structures in a vasodilator-stimulated phosphoprotein-dependent (VASP) manner, but independently of the Arp2/3 complex. These results are consistent with the concept that there are multiple Actin-Polymerization machines in cells. With these simple tests it is possible to probe the specific function of proteins or identify novel molecules that act upon cellular Actin Polymerization.
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ActA and human zyxin harbour Arp2/3-independent Actin-Polymerization activity
Nature cell biology, 2001Co-Authors: Julie Fradelizi, Daniel Louvard, Cécile Sykes, Vincent Noireaux, Julie Plastino, Bernadette Menichi, Roy M Golsteyn, Evelyne FriederichAbstract:The Actin cytoskeleton is a dynamic network that is composed of a variety of F-Actin structures. To understand how these structures are produced, we tested the capacity of proteins to direct Actin Polymerization in a bead assay in vitro and in a mitochondrial-targeting assay in cells. We found that human zyxin and the related protein ActA of Listeria monocytogenes can generate new Actin structures in a vasodilator-stimulated phosphoprotein-dependent (VASP) manner, but independently of the Arp2/3 complex. These results are consistent with the concept that there are multiple Actin-Polymerization machines in cells. With these simple tests it is possible to probe the specific function of proteins or identify novel molecules that act upon cellular Actin Polymerization.
Timothy J Mitchison - One of the best experts on this subject based on the ideXlab platform.
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spatial control of Actin Polymerization during neutrophil chemotaxis
Nature Cell Biology, 1999Co-Authors: Orion D Weiner, Matthew D Welch, Timothy J Mitchison, Guy Servant, John W Sedat, Henry R BourneAbstract:Neutrophils respond to chemotactic stimuli by increasing the nucleation and Polymerization of Actin filaments, but the location and regulation of these processes are not well understood. Here, using a permeabilized-cell assay, we show that chemotactic stimuli cause neutrophils to organize many discrete sites of Actin Polymerization, the distribution of which is biased by external chemotactic gradients. Furthermore, the Arp2/3 complex, which can nucleate Actin Polymerization, dynamically redistributes to the region of living neutrophils that receives maximal chemotactic stimulation, and the least-extractable pool of the Arp2/3 complex co-localizes with sites of Actin Polymerization. Our observations indicate that chemoattractant-stimulated neutrophils may establish discrete foci of Actin Polymerization that are similar to those generated at the posterior surface of the intracellular bacterium Listeria monocytogenes. We propose that asymmetrical establishment and/or maintenance of sites of Actin Polymerization produces directional migration of neutrophils in response to chemotactic gradients.
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Actin Polymerization is induced by arp 2 3 protein complex at the surface of listeria monocytogenes
Nature, 1997Co-Authors: Matthew D Welch, Akihiro Iwamatsu, Timothy J MitchisonAbstract:The pathogenic bacterium Listeria monocytogenes is capable of directed movement within the cytoplasm of infected host cells. Propulsion is thought to be driven by Actin Polymerization at the bacterial cell surface1,2, and moving bacteria leave in their wake a tail of Actin filaments3. Determining the mechanism by which L. monocytogenes polymerizes Actin may aid the understanding of how Actin Polymerization is controlled in the cell. Actin assembly by L. monocytogenes requires the bacterial surface protein ActA4,5 and protein components present in host cell cytoplasm. We have purified an eight-polypeptide complex that possesses the properties of the host-cell Actin Polymerization factor. The pure complex is sufficient to initiate ActA-dependent Actin Polymerization at the surface of L. monocytogenes, and is required to mediate Actin tail formation and motility. Two subunits of this protein complex are Actin-related proteins (ARPs) belonging to the Arp2 and Arp3 subfamilies. The Arp3 subunit localizes to the surface of stationary bacteria and the tails of motile bacteria in tissue culture cells infected with L. monocytogenes; this is consistent with a role for the complex in promoting Actin assembly in vivo. The activity and subunit composition of the Arp2/3 complex suggests that it forms a template that nucleates Actin Polymerization.
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Actin Polymerization is induced by Arp2/3 protein complex at the surface of Listeria monocytogenes.
Nature, 1997Co-Authors: Matthew D Welch, Akihiro Iwamatsu, Timothy J MitchisonAbstract:The pathogenic bacterium Listeria monocytogenes is capable of directed movement within the cytoplasm of infected host cells. Propulsion is thought to be driven by Actin Polymerization at the bacterial cell surface, and moving bacteria leave in their wake a tail of Actin filaments. Determining the mechanism by which L. monocytogenes polymerizes Actin may aid the understanding of how Actin Polymerization is controlled in the cell. Actin assembly by L. monocytogenes requires the bacterial surface protein ActA and protein components present in host cell cytoplasm. We have purified an eight-polypeptide complex that possesses the properties of the host-cell Actin Polymerization factor. The pure complex is sufficient to initiate ActA-dependent Actin Polymerization at the surface of L. monocytogenes, and is required to mediate Actin tail formation and motility. Two subunits of this protein complex are Actin-related proteins (ARPs) belonging to the Arp2 and Arp3 subfamilies. The Arp3 subunit localizes to the surface of stationary bacteria and the tails of motile bacteria in tissue culture cells infected with L. monocytogenes; this is consistent with a role for the complex in promoting Actin assembly in vivo. The activity and subunit composition of the Arp2/3 complex suggests that it forms a template that nucleates Actin Polymerization.
Sally H. Zigmond - One of the best experts on this subject based on the ideXlab platform.
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How WASP regulates Actin Polymerization.
The Journal of cell biology, 2000Co-Authors: Sally H. ZigmondAbstract:Protrusion of lamellipodia and filopodia from the cell surface requires that Actin polymerize locally. Actin Polymerization is initiated by numerous agonists, including growth factors, chemoattractants, extracellular matrix, and phagocytic particles. The signaling pathways from the corresponding
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Actin Polymerization: Where the WASP stings
Current biology : CB, 1999Co-Authors: Sally H. ZigmondAbstract:How do extracellular signals induce Actin Polymerization, as required for many cellular responses? Key signal transducers, such as the small GTPases Cdc42 and Rac, have now been shown to link via proteins of the WASP family to the Arp2/3 complex, which nucleates Actin Polymerization.
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Regulation of Actin Polymerization in Cell-free Systems by GTPγS and Cdc42
The Journal of cell biology, 1997Co-Authors: Sally H. Zigmond, Michael Joyce, Jane Borleis, Gary M. Bokoch, Peter N. DevreotesAbstract:We have established a cell-free system to investigate pathways that regulate Actin Polymerization. Addition of GTPγS to lysates of polymorphonuclear leukocytes (PMNs) or Dictyostelium discoideum amoeba induced formation of filamentous Actin. The GTPγS appeared to act via a small G-protein, since it was active in lysates ofD. discoideum mutants missing either the α2- or β-subunit of the heterotrimeric G-protein required for chemoattractant-induced Actin Polymerization in living cells. Furthermore, recombinant Cdc42, but not Rho or Rac, induced Polymerization in the cell-free system. The Cdc42-induced increase in filamentous Actin required GTPγS binding and was inhibited by a fragment of the enzyme PAK1 that binds Cdc42. In a high speed supernatant, GTPγS alone was ineffective, but GTPγS-loaded Cdc42 induced Actin Polymerization, suggesting that the response was limited by guanine nucleotide exchange. Stimulating exchange by chelating magnesium, by adding acidic phospholipids, or by adding the exchange factors Cdc24 or Dbl restored the ability of GTPγS to induce Polymerization. The stimulation of Actin Polymerization did not correlate with PIP2 synthesis.
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regulation of Actin Polymerization in cell free systems by gtpγs and cdc42
Journal of Cell Biology, 1997Co-Authors: Sally H. Zigmond, Michael Joyce, Jane Borleis, Gary M. Bokoch, Peter N. DevreotesAbstract:We have established a cell-free system to investigate pathways that regulate Actin Polymerization. Addition of GTPgammaS to lysates of polymorphonuclear leukocytes (PMNs) or Dictyostelium discoideum amoeba induced formation of filamentous Actin. The GTPgammaS appeared to act via a small G-protein, since it was active in lysates ofD. discoideum mutants missing either the alpha2- or beta-subunit of the heterotrimeric G-protein required for chemoattractant-induced Actin Polymerization in living cells. Furthermore, recombinant Cdc42, but not Rho or Rac, induced Polymerization in the cell-free system. The Cdc42-induced increase in filamentous Actin required GTPgammaS binding and was inhibited by a fragment of the enzyme PAK1 that binds Cdc42. In a high speed supernatant, GTPgammaS alone was ineffective, but GTPgammaS-loaded Cdc42 induced Actin Polymerization, suggesting that the response was limited by guanine nucleotide exchange. Stimulating exchange by chelating magnesium, by adding acidic phospholipids, or by adding the exchange factors Cdc24 or Dbl restored the ability of GTPgammaS to induce Polymerization. The stimulation of Actin Polymerization did not correlate with PIP2 synthesis.
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Induction of Actin Polymerization in permeabilized neutrophils. Role of ATP.
The Journal of biological chemistry, 1994Co-Authors: Tim Redmond, Marianne Tardif, Sally H. ZigmondAbstract:Abstract We have used streptolysin-O (SO)-permeabilized neutrophils to investigate the signal transduction pathway through which chemoattractants induce Actin Polymerization. Chemoattractants stimulate phosphorylation of various proteins and lipids but whether these phosphorylations are required for Actin Polymerization is not known. Addition of guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) to SO-permeabilized neutrophils induced a doubling of the F-Actin. This induction of F-Actin, assayed by TRITC-labeled phalloidin binding, did not require the addition of ATP. Neither addition of apyrase to deplete residual ATP nor addition of ADP or UDP to compete with residual endogenous ATP inhibited significantly the GTP gamma S-induced Polymerization. Addition of ATP on its own caused no increase in F-Actin and did not affect the time course or concentration dependence of GTP gamma S-induced F-Actin. Addition of ATP did increase the maximal amount of F-Actin induced by GTP gamma S by about 20%. N-Formylnorleucylleucylphenalanine (formyl-peptide) in the presence of GTP, but not in its absence, also stimulated an increase in F-Actin in SO-permeabilized cells. The F-Actin induced by formyl-peptide plus GTP was inhibited by pertussis toxin. The induction did not require addition of ATP and addition of ADP to compete with residual ATP only slightly decreased the level of Actin. However, addition of UDP significantly reduced the response to formyl-peptide plus GTP. Addition of ATP enhanced the increase in F-Actin induced by optimal concentrations of GTP with formyl-peptide. ATP also lowered the apparent Km for GTP, but not for N-formyl peptide. The non-hydrolyzable ATP analog, adenosine 5'-(beta, gamma-imino)triphosphate, did not enhance the Actin Polymerization. Rather its presence inhibited the response induced by formyl-peptide plus GTP. The data suggest that Actin Polymerization can be induced by GTP gamma S in an manner that is largely ATP-independent. A role for ATP cannot be ruled out in the induction of Actin Polymerization by formyl-peptide plus GTP.
Matthew D Welch - One of the best experts on this subject based on the ideXlab platform.
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spatial control of Actin Polymerization during neutrophil chemotaxis
Nature Cell Biology, 1999Co-Authors: Orion D Weiner, Matthew D Welch, Timothy J Mitchison, Guy Servant, John W Sedat, Henry R BourneAbstract:Neutrophils respond to chemotactic stimuli by increasing the nucleation and Polymerization of Actin filaments, but the location and regulation of these processes are not well understood. Here, using a permeabilized-cell assay, we show that chemotactic stimuli cause neutrophils to organize many discrete sites of Actin Polymerization, the distribution of which is biased by external chemotactic gradients. Furthermore, the Arp2/3 complex, which can nucleate Actin Polymerization, dynamically redistributes to the region of living neutrophils that receives maximal chemotactic stimulation, and the least-extractable pool of the Arp2/3 complex co-localizes with sites of Actin Polymerization. Our observations indicate that chemoattractant-stimulated neutrophils may establish discrete foci of Actin Polymerization that are similar to those generated at the posterior surface of the intracellular bacterium Listeria monocytogenes. We propose that asymmetrical establishment and/or maintenance of sites of Actin Polymerization produces directional migration of neutrophils in response to chemotactic gradients.
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Actin Polymerization is induced by arp 2 3 protein complex at the surface of listeria monocytogenes
Nature, 1997Co-Authors: Matthew D Welch, Akihiro Iwamatsu, Timothy J MitchisonAbstract:The pathogenic bacterium Listeria monocytogenes is capable of directed movement within the cytoplasm of infected host cells. Propulsion is thought to be driven by Actin Polymerization at the bacterial cell surface1,2, and moving bacteria leave in their wake a tail of Actin filaments3. Determining the mechanism by which L. monocytogenes polymerizes Actin may aid the understanding of how Actin Polymerization is controlled in the cell. Actin assembly by L. monocytogenes requires the bacterial surface protein ActA4,5 and protein components present in host cell cytoplasm. We have purified an eight-polypeptide complex that possesses the properties of the host-cell Actin Polymerization factor. The pure complex is sufficient to initiate ActA-dependent Actin Polymerization at the surface of L. monocytogenes, and is required to mediate Actin tail formation and motility. Two subunits of this protein complex are Actin-related proteins (ARPs) belonging to the Arp2 and Arp3 subfamilies. The Arp3 subunit localizes to the surface of stationary bacteria and the tails of motile bacteria in tissue culture cells infected with L. monocytogenes; this is consistent with a role for the complex in promoting Actin assembly in vivo. The activity and subunit composition of the Arp2/3 complex suggests that it forms a template that nucleates Actin Polymerization.
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Actin Polymerization is induced by Arp2/3 protein complex at the surface of Listeria monocytogenes.
Nature, 1997Co-Authors: Matthew D Welch, Akihiro Iwamatsu, Timothy J MitchisonAbstract:The pathogenic bacterium Listeria monocytogenes is capable of directed movement within the cytoplasm of infected host cells. Propulsion is thought to be driven by Actin Polymerization at the bacterial cell surface, and moving bacteria leave in their wake a tail of Actin filaments. Determining the mechanism by which L. monocytogenes polymerizes Actin may aid the understanding of how Actin Polymerization is controlled in the cell. Actin assembly by L. monocytogenes requires the bacterial surface protein ActA and protein components present in host cell cytoplasm. We have purified an eight-polypeptide complex that possesses the properties of the host-cell Actin Polymerization factor. The pure complex is sufficient to initiate ActA-dependent Actin Polymerization at the surface of L. monocytogenes, and is required to mediate Actin tail formation and motility. Two subunits of this protein complex are Actin-related proteins (ARPs) belonging to the Arp2 and Arp3 subfamilies. The Arp3 subunit localizes to the surface of stationary bacteria and the tails of motile bacteria in tissue culture cells infected with L. monocytogenes; this is consistent with a role for the complex in promoting Actin assembly in vivo. The activity and subunit composition of the Arp2/3 complex suggests that it forms a template that nucleates Actin Polymerization.
