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Actin Depolymerizing Factor

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James R Bamburg – 1st expert on this subject based on the ideXlab platform

  • redundant and non redundant functions of Actin Depolymerizing Factor adf and cofilin in metastasis review
    , 2011
    Co-Authors: Lubna H Tahtamouni, James R Bamburg

    Abstract:

    Tumor cell motility is the hallmark of invasion and an essential step in metastasis. Cellular changes that occur during the progression of cancer affect proteins that drive Actin dynamics; these changes modulate cell cycle progression and lead to more invasive cancers. Actin Depolymerizing Factor (ADF)/cofilins (Actin dynamizing proteins) and their regulatory proteins are involved in the initiation of early steps in cell motility. ADF/cofilins play important roles in various stages of cancer progression including cell polarization and polarized migration, escape from apoptosis, and secretion of metalloproteases, all of which are important in metastasis. Vertebrates express ADF, cofilin-1 and cofilin-2, and even though ADF and cofilin have many qualitatively similar biochemical properties, they differ quantitatively in Actin interaction and in some types of regulation and, thus, are not functionally identical. This review compares the activities of these two proteins with respect to how they may function during tumor cell invasion. Understanding the molecular pathways of tumor invasion will provide new diagnostic approaches and targets for the treatment of metastatic cancer. ﺮﺒﺘﻌﺗ

  • Proteins of the Actin Depolymerizing Factor/Cofilin Family
    Actin-Monomer-Binding Proteins, 2007
    Co-Authors: Janel D Funk, James R Bamburg

    Abstract:

    Actin Depolymerizing Factor (ADF) and cofilin are the founding members of a group of structurally and functionally related Actin binding proteins now collectively known as the ADF/cofilin (AC) family. AC proteins are expressed in all eukaryotic organisms, and their unique ability to bind and dynamize filamentous Actin renders them essential to all cellular processes dependent upon Actin dynamics. Cell division, cell motility and neuronal pathfinding, membrane dynamics, and cell polarization could not proceed without the aid of these remarkable proteins.

  • proteins of the Actin Depolymerizing Factor cofilin family
    , 2007
    Co-Authors: Janel D Funk, James R Bamburg

    Abstract:

    Actin Depolymerizing Factor (ADF) and cofilin are the founding members of a group of structurally and functionally related Actin binding proteins now collectively known as the ADF/cofilin (AC) family. AC proteins are expressed in all eukaryotic organisms, and their unique ability to bind and dynamize filamentous Actin renders them essential to all cellular processes dependent upon Actin dynamics. Cell division, cell motility and neuronal pathfinding, membrane dynamics, and cell polarization could not proceed without the aid of these remarkable proteins.

Christopher J Staiger – 2nd expert on this subject based on the ideXlab platform

  • arabidopsis Actin Depolymerizing Factor atadf4 mediates defense signal transduction triggered by the pseudomonas syringae effector avrpphb
    Plant Physiology, 2009
    Co-Authors: Miaoying Tian, Faisal Chaudhry, R Ichard B. Meagher, Daniel R Ruzicka, Christopher J Staiger

    Abstract:

    The Actin cytoskeleton has been implicated in plant defenses against pathogenic fungi and oomycetes with limited, indirect evidence. To date, there are no reports linking Actin with resistance against phytopathogenic bacteria. The dynamic behavior of Actin filaments is regulated by a diverse array of Actin-binding proteins, among which is the ActinDepolymerizing Factor (ADF) family of proteins. Here, we demonstrate that Actin dynamics play a role in the activation of gene-for-gene resistance in Arabidopsis (Arabidopsis thaliana) following inoculation with the phytopathogenic bacterium Pseudomonas syringae pv tomato. Using a reverse genetics approach, we explored the roles of Arabidopsis ADFs in plant defenses. AtADF4 was identified as being specifically required for resistance triggered by the effector AvrPphB but not AvrRpt2 or AvrB. Recombinant AtADF4 bound to monomeric Actin (G-Actin) with a marked preference for the ADP-loaded form and inhibited the rate of nucleotide exchange on G-Actin, indicating that AtADF4 is a bona fide ActinDepolymerizing Factor. Exogenous application of the Actin-disrupting agent cytochalasin D partially rescued the Atadf4 mutant in the AvrPphB-mediated hypersensitive response, demonstrating that AtADF4 mediates defense signaling through modification of the Actin cytoskeleton. Unlike the mechanism by which the Actin cytoskeleton confers resistance against fungi and oomycetes, AtADF4 is not involved in resistance against pathogen entry. Collectively, this study identifies AtADF4 as a novel component of the plant defense signaling pathway and provides strong evidence for Actin dynamics as a primary component that orchestrates plant defenses against P. syringae.

  • Arabidopsis ActinDepolymerizing Factor AtADF4 Mediates Defense Signal Transduction Triggered by
    , 2009
    Co-Authors: Miaoying Tian, Faisal Chaudhry, R. Ruzicka, R Ichard B. Meagher, Christopher J Staiger

    Abstract:

    The Actin cytoskeleton has been implicated in plant defenses against pathogenic fungi and oomycetes with limited, indirect evidence. To date, there are no reports linking Actin with resistance against phytopathogenic bacteria. The dynamic behavior of Actin filaments is regulated by a diverse array of Actin-binding proteins, among which is the ActinDepolymerizing Factor (ADF) family of proteins. Here, we demonstrate that Actin dynamics play a role in the activation of gene-for-gene resistance in Arabidopsis (Arabidopsis thaliana) following inoculation with the phytopathogenic bacterium Pseudomonas syringae pv tomato. Using a reverse genetics approach, we explored the roles of Arabidopsis ADFs in plant defenses. AtADF4 was identified as being specifically required for resistance triggered by the effector AvrPphB but not AvrRpt2 or AvrB. Recombinant AtADF4 bound to monomeric Actin (G-Actin) with a marked preference for the ADP-loaded form and inhibited the rate of nucleotide exchange on G-Actin, indicating that AtADF4 is a bona fide ActinDepolymerizing Factor. Exogenous application of the Actindisrupting agent cytochalasin D partially rescued the Atadf4 mutant in the AvrPphB-mediated hypersensitive response, demonstrating that AtADF4 mediates defense signaling through modification of the Actin cytoskeleton. Unlike the mechanism by which the Actin cytoskeleton confers resistance against fungi and oomycetes, AtADF4 is not involved in resistance against pathogen entry. Collectively, this study identifies AtADF4 as a novel component of the plant defense signaling pathway and provides strong evidence for Actin dynamics as a primary component that orchestrates plant defenses against P. syringae.

  • Actin Depolymerizing Factor
    , 2000
    Co-Authors: David R Kovar, Christopher J Staiger

    Abstract:

    Unlike other Actin-binding proteins, Actin Depolymerizing Factor (ADF) binds to both filamentous and globular Actin, and causes the rapid depolymerization of Actin filaments. ADF localizes to sites of active Actin dynamics, including growing maize root hairs. ADF activity is regulated by a variety of stimuli implicated in affecting Actin organization, such as pH changes, phosphorylation and polyphosphoinositides. Our current understanding of ADF’s role in regulating Actin dynamics has been greatly enhanced through examination of the biochemical properties of plant ADFs. ADF depolymerizes Actin filaments by a combination of severing activity and enhancing the rate of Actin monomer dissociation from the pointed end. As a result, ADF-induced depolymerization creates a large pool of Actin subunits. When the ends of Actin filaments are uncapped, this pool is able to rapidly repolymerize. However, when filament ends are capped, repolymerization can not occur. Therefore, depending upon the presence of Actin-filament capping Factors, ADF either drives filament turnover or induces total depolymerization.

Kurato Mohri – 3rd expert on this subject based on the ideXlab platform

  • the two caenorhabditis elegans Actin Depolymerizing Factor cofilin proteins differently enhance Actin filament severing and depolymerization
    Biochemistry, 2005
    Co-Authors: Sawako Yamashiro, Kurato Mohri

    Abstract:

    ActinDepolymerizing Factor (ADF)/cofilin enhances the turnover of Actin filaments by two separable activities: filament severing and pointed-end depolymerization. Multicellular organisms express multiple ADF/cofilin isoforms in a tissue-specific manner, and the vertebrate proteins are grouped into ADFs and cofilins on the basis of their biochemical activity. A recent comparative study has shown that ADF has greater severing and Depolymerizing activities than cofilin [Chen, H., Bernstein, B. W., Sneider, J. M., Boyle, J. A., Minamide, L. S., and Bamburg, J. R. (2004) Biochemistry 43, 7127-7142]. Here, we show that the two Caenorhabditis elegans ADF/cofilin isoforms exhibit different activities for severing and Depolymerizing Actin filaments. The ADF-like non-muscle isoform UNC-60A had greater activities to cause net depolymerization and inhibit polymerization than the cofilin-like muscle isoform UNC-60B. Surprisingly, UNC-60B exhibited much stronger severing activity than UNC-60A, which was the opposite of what was observed for vertebrate counterparts. Moreover, UNC-60B induced much faster pointed-end depolymerization of rabbit muscle Actin than UNC-60A, while UNC-60A caused slightly faster depolymerization of C. elegans Actin than UNC-60B. These results suggest that cofilin-like UNC-60B is kinetically more efficient in enhancing Actin turnover than ADF-like UNC-60A, while ADF-like UNC-60A is suitable for maintaining higher concentrations of monomeric Actin. These functional differences might be specifically adapted for different Actin dynamics in muscle and non-muscle cells.

  • identification of functional residues on caenorhabditis elegans Actin interActing protein 1 unc 78 for disassembly of Actin Depolymerizing Factor cofilin bound Actin filaments
    Journal of Biological Chemistry, 2004
    Co-Authors: Kurato Mohri, S Vorobiev, A A Fedorov, S C Almo

    Abstract:

    Abstract Actin-interActing protein 1 (AIP1) is a WD40 repeat protein that enhances Actin filament disassembly in the presence of ActinDepolymerizing Factor (ADF)/cofilin. AIP1 also caps the barbed end of ADF/cofilin-bound Actin filament. However, the mechanism by which AIP1 interacts with ADF/cofilin and Actin is not clearly understood. We determined the crystal structure of Caenorhabditis elegans AIP1 (UNC-78), which revealed 14 WD40 modules arranged in two seven-bladed β-propeller domains. The structure allowed for the mapping of conserved surface residues, and mutagenesis studies identified five residues that affected the ADF/cofilin-dependent Actin filament disassembly activity. Mutations of these residues, which reside in blades 3 and 4 in the N-terminal propeller domain, had significant effects on the disassembly activity but did not alter the barbed end capping activity. These data support a model in which this conserved surface of AIP1 plays a direct role in enhancing fragmentation/depolymerization of ADF/cofilin-bound Actin filaments but not in barbed end capping.

  • microscopic evidence that Actin interActing protein 1 actively disassembles Actin Depolymerizing Factor cofilin bound Actin filaments
    Journal of Biological Chemistry, 2004
    Co-Authors: Kurato Mohri

    Abstract:

    Abstract ActinDepolymerizing Factor (ADF)/cofilin and gelsolin are the two major Factors to enhance Actin filament disassembly. Actin-interActing protein 1 (AIP1) enhances fragmentation of ADF/cofilin-bound filaments and caps the barbed ends. However, the mechanism by which AIP1 disassembles ADF/cofilin-bound filaments is not clearly understood. Here, we directly observed the effects of these proteins on filamentous Actin by fluorescence microscopy and gained novel insight into the function of ADF/cofilin and AIP1. ADF/cofilin severed filaments and AIP1 strongly enhanced disassembly at nanomolar concentrations. However, gelsolin, gelsolin-Actin complex, or cytochalasin D did not enhance disassembly by ADF/cofilin, suggesting that the strong activity of AIP1 cannot be explained by simple barbed end capping. Barbed end capping by ADF/cofilin and AIP1 was weak and allowed filament elongation, whereas gelsolin or gelsolin-Actin complex strongly capped and inhibited elongation. These results suggest that AIP has an active role in filament severing or depolymerization and that ADF/cofilin and AIP1 are distinct from gelsolin in modulating filament elongation.