The Drosophila forked protein induces the formation of actin fiber bundles in vertebrate cells

1999 ◽  
Vol 112 (13) ◽  
pp. 2203-2211 ◽  
Author(s):  
S. Grieshaber ◽  
N.S. Petersen
Keyword(s):  
Gene Expression ◽  
Developmental Biology ◽  
Proximal Tubule ◽  
Actin Polymerization ◽  
Actin Binding ◽  
Fiber Bundles ◽  
Actin Bundle ◽  
Actin Binding Protein ◽  
Kidney Proximal Tubule ◽  
Actin Fiber

The forked protein is an actin binding protein involved in the formation of large actin fiber bundles in developing Drosophila bristles. These are the largest example of a type of actin bundle characterized by parallel, hexagonally packed actin fibers, also found in intestinal microvilli, kidney proximal tubule microvilli, and stereocilia in the ear. Understanding how these structures are constructed and how that construction is regulated is an important question in cell and developmental biology. Because the timing of forked gene expression coincides with the formation of the actin fiber bundles, and since the forked protein is localized at the site of initiation of these bundles before they form, it has been proposed that the forked protein is an initiator of actin bundle formation. In this paper we show that the forked protein can induce the formation of bundles and increase actin polymerization in vertebrate cells. We use this system to identify regions of the forked protein which are essential for bundle formation and actin co-localization.

scholarly journals Actin-binding protein promotes the bipolar and perpendicular branching of actin filaments.

1980 ◽  
Vol 87 (3) ◽  
pp. 841-848 ◽  
Author(s):  
J H Hartwig ◽  
J Tyler ◽  
T P Stossel
Keyword(s):  
Actin Filaments ◽  
Actin Polymerization ◽  
Average Length ◽  
Binding Protein ◽  
Actin Binding ◽  
Branch Points ◽  
Heavy Meromyosin ◽  
Actin Binding Protein ◽  
Protein Dimers ◽  
Protein Molecules

Branching filaments with striking perpendicularity form when actin polymerizes in the presence of macrophage actin-binding protein. Actin-binding protein molecules are visible at the branch points. Compared with actin polymerized in the absence of actin-binding proteins, not only do the filaments branch but the average length of the actin filaments decreases from 3.2 to 0.63 micrometer. Arrowhead complexes formed by addition of heavy meromyosin molecules to the branching actin filaments point toward the branch points. Actin-binding protein also accelerates the onset of actin polymerization. All of these findings show that actin filaments assemble from nucleating sites on actin-binding protein dimers. A branching polymerization of actin filaments from a preexisting lattice of actin filaments joined by actin-binding protein molecules could generate expansion of cortical cytoplasm in amoeboid cells.

scholarly journals Actin-binding Protein Drebrin Regulates HIV-1-triggered Actin Polymerization and Viral Infection

2013 ◽  
Vol 288 (39) ◽  
pp. 28382-28397 ◽  
Author(s):  
Mónica Gordón-Alonso ◽  
Vera Rocha-Perugini ◽  
Susana Álvarez ◽  
Ángeles Ursa ◽  
Nuria Izquierdo-Useros ◽  
...  
Keyword(s):  
Viral Infection ◽  
Actin Polymerization ◽  
Binding Protein ◽  
Actin Binding ◽  
Actin Binding Protein ◽  
Hiv 1

scholarly journals Cytoskeletal proteins in the cell nucleus: a special nuclear actin perspective

2019 ◽  
Vol 30 (15) ◽  
pp. 1781-1785 ◽  
Author(s):  
Piergiorgio Percipalle ◽  
Maria Vartiainen
Keyword(s):  
Gene Expression ◽  
Cell Nucleus ◽  
Cell Biology ◽  
Genome Stability ◽  
Actin Polymerization ◽  
Nuclear Architecture ◽  
Nuclear Lamina ◽  
Cytoskeletal Proteins ◽  
Actin Binding ◽  
Special Focus

The emerging role of cytoskeletal proteins in the cell nucleus has become a new frontier in cell biology. Actin and actin-binding proteins regulate chromatin and gene expression, but importantly they are beginning to be essential players in genome organization. These actin-based functions contribute to genome stability and integrity while affecting DNA replication and global transcription patterns. This is likely to occur through interactions of actin with nuclear components including nuclear lamina and subnuclear organelles. An exciting future challenge is to understand how these actin-based genome-wide mechanisms may regulate development and differentiation by interfering with the mechanical properties of the cell nucleus and how regulated actin polymerization plays a role in maintaining nuclear architecture. With a special focus on actin, here we summarize how cytoskeletal proteins operate in the nucleus and how they may be important to consolidate nuclear architecture for sustained gene expression or silencing.

scholarly journals The architecture of actin filaments and the ultrastructural location of actin-binding protein in the periphery of lung macrophages.

1986 ◽  
Vol 103 (3) ◽  
pp. 1007-1020 ◽  
Author(s):  
J H Hartwig ◽  
P Shevlin
Keyword(s):  
Electron Microscopy ◽  
Critical Point ◽  
Binding Protein ◽  
The Body ◽  
Actin Binding ◽  
Actin Network ◽  
Actin Binding Protein ◽  
Freeze Dried ◽  
Critical Point Drying ◽  
Actin Fiber

A highly branched filament network is the principal structure in the periphery of detergent-extracted cytoskeletons of macrophages that have been spread on a surface and either freeze or critical point dried, and then rotary shadowed with platinum-carbon. This array of filaments completely fills lamellae extended from the cell and bifurcates to form 0.2-0.5 micron thick layers on the top and bottom of the cell body. Reaction of the macrophage cytoskeletons with anti-actin IgG and with anti-IgG bound to colloidal gold produces dense staining of these filaments, and incubation with myosin subfragment 1 uniformly decorates these filaments, identifying them as actin. 45% of the total cellular actin and approximately 70% of actin-binding protein remains in the detergent-insoluble cell residue. The soluble actin is not filamentous as determined by sedimentation analysis, the DNAase I inhibition assay, and electron microscopy, indicating that the cytoskeleton is not fragmented by detergent extraction. The spacing between the ramifications of the actin network is 94 +/- 47 nm and 118 +/- 72 nm in cytoskeletons prepared for electron microscopy by freeze drying and critical point drying, respectively. Free filament ends are rare, except for a few which project upward from the body of the network or which extend down to the substrate. Filaments of the network intersect predominantly at right angles to form either T-shaped and X-shaped overlaps having striking perpendicularity or else Y-shaped intersections composed of filaments intersecting at 120-130 degrees angles. The actin filament concentration in the lamellae is high, with an average value of 12.5 mg/ml. The concentration was much more uniform in freeze-dried preparations than in critical point-dried specimens, indicating that there is less collapse associated with the freezing technique. The orthogonal actin network of the macrophage cortical cytoplasm resembles actin gels made with actin-binding protein. Reaction of cell cytoskeletons and of an actin gel made with actin-binding protein with anti-actin-binding protein IgG and anti-IgG-coated gold beads resulted in the deposition of clusters of gold at points where filaments intersect and at the ends of filaments that may have been in contact with the membrane before its removal with detergent. In the actin gel made with actin-binding protein, 75% of actin-fiber intersections labeled, and the filament spacing between intersections is consistent with that predicted on theoretical grounds if each added actin-binding protein molecule cross-links two filaments to form an intersection in the gel.(ABSTRACT TRUNCATED AT 400 WORDS)

Cytoskeletal regulation of the platelet glycoprotein Ib/V/IX–von Willebrand factor interaction

Blood ◽  
2000 ◽  
Vol 96 (10) ◽  
pp. 3480-3489 ◽  
Author(s):  
Nayna Mistry ◽  
Susan L. Cranmer ◽  
Yuping Yuan ◽  
Pierre Mangin ◽  
Sacha M. Dopheide ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Cho Cells ◽  
Actin Polymerization ◽  
Cytochalasin D ◽  
Actin Binding ◽  
Platelet Glycoprotein ◽  
Actin Binding Protein ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Shear-induced binding of von Willebrand factor (vWf) to the platelet glycoprotein (GP) Ib/V/IX complex plays a key role in initiating platelet adhesion and aggregation at sites of vascular injury. This study demonstrated that pretreating human platelets with inhibitors of actin polymerization, cytochalasin D or latrunculin B, dramatically enhances platelet aggregation induced by vWf. The effects of these inhibitors were specific to the vWf-GPIbα interaction because they enhanced vWf-induced aggregation of Glanzmann thrombasthenic platelets and Chinese hamster ovary (CHO) cells transfected with GPIb/V/IX. Moreover, cytochalasin D enhanced the extent of platelet aggregation induced by high shear stress (5000 s−1) and also lowered the shear threshold required to induce aggregation from 3000 s−1 to as low as 500 s−1. Studies of CHO cells expressing GPIbα cytoplasmic tail truncation mutants that failed to bind actin-binding protein-280 (deletion of residues 569-610 or 535-568) demonstrated that the linkage between GPIb and actin-binding protein-280 was not required for vWf-induced actin polymerization, but was critical for the enhancing effects of cytochalasin D on vWf-induced cell aggregation. Taken together, these studies suggest a fundamentally important role for the cytoskeleton in regulating the adhesive function of GPIb/V/IX.

IDENTIFICATION OF GLYCOPROTEIN Ib8 AS THE Mr = 24,000 PLATELET POLYPEPTIDE PHOSPHORYLATED BY AGENTS THAT ELEVATE CYCLIC AMP

1987 ◽  
Author(s):  
J E B Fox ◽  
C C Reynolds ◽  
J K Boyles ◽  
R A Abel ◽  
M M Johnson
Keyword(s):  
Cyclic Amp ◽  
Platelet Function ◽  
Actin Polymerization ◽  
Binding Protein ◽  
Membrane Skeleton ◽  
Actin Binding ◽  
Inhibitory Effects ◽  
Actin Binding Protein ◽  
Triton X ◽  
Β Chain

Platelet function is inhibited by agents that elevate intracellular cyclic AMP concentrations, presumably as a result of the cyclic AMP-stimulated phosphorylation of intracellular proteins. Polypeptides that become phosphorylated are of Mr = 250,000, Mr = 51.000 (P51), Mr = 36,000 (P36), Mr = 24,000 (P24), and Mr = 22.000 (P22). The Mr = 250,000 polypeptide is actin-binding protein, but the identity of the other polypeptides 1s unknown. In the present study, we identified the P24 polypeptide. Platelets were radiolabeled with [32P]P1 and then Incubated for 2-5 min in the presence or absence of 5 μM prostaglandin E1 (PGE1). The PGE1-induced phosphorylation of P24 was detected on autoradiograms of SDS-gels. Since P24 has been shown to be membrane-associated, its molecular weight was compared with those of known membrane proteins. P24 comigrated with the β-chain of purified GP Ib on reduced gels (Mr = 24,000) and also on nonreduced gels (when GP Ibβ is disulfide-linked to GP Ibα and migrates with Mr = 170,000). Like GP Ibβ, P24 was associated with actin filaments in Triton X-100 lysates. Both GP Ibβ and P24 were selectively associated with filaments of the membrane skeleton and were released from filaments when the Ca2+-dependent protease was active. Antibodies against GP Ib immunoprecipitated P24 from platelet lysates. Finally, exposure of Bernard-Soulier platelets (that lacked GP Ib) to PGE1 resulted in phosphorylation of actin-binding protein, P51, P36, and P22, but not P24. We conclude that P24 is GP Ibβ. To determine whether phosphorylation of GP Ibβ is responsible for the inhibitory effects of PGE1 on platelets, we compared the action of PGE1 on control platelets with that on Bernard-Soulier platelets. One of the ways in which PGE1 inhibits platelet activation is by inhibiting the polymerization of actin. While PGE1 inhibited actin polymerization in control platelets, it did not in Bernard-Soulier platelets. We conclude that GP Ibβ is phosphorylated by agents that elevate cyclic AMP and that phosphorylation of this glycoprotein results in inhibition of platelet function.

The Actin Binding Protein Plastin-3 Is Involved in the Pathogenesis of Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1662-1662
Author(s):  
Arne Velthaus ◽  
Kerstin Cornils ◽  
Saskia Grüb ◽  
Hauke Stamm ◽  
Daniel Wicklein ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Myeloid Leukemia ◽  
Stromal Cells ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Binding Protein ◽  
Actin Binding ◽  
Actin Binding Protein ◽  
Mutational Status ◽  
Acute Myeloid

Abstract Leukemia-initiating cells reside within the bone marrow (BM) in specialized niches where they undergo complex interactions with their surrounding stromal cells. In order to identify genes being implicated in the interaction of acute myeloid leukemia (AML) cells and stromal cells, we performed co-cultures of primary AML cells with primary endothelial cells and osteoblasts. The gene expression of co-cultured AML blasts was compared to AML cells grown without adherent cells using microarray analysis. Amongst those genes being dysregulated upon co-culture was the actin binding protein plastin-3 (PLS3). Further RT-qPCR analysis revealed an endogenous PLS3 expression in about 50% of BM samples from AML patients (n=25). In contrast, expression of PLS3 was only detected in 2 of 12 analyzed AML cell lines with Kasumi-1 showing strong and THP-1 showing only weak expression. Therefore, functional analysis of PLS3 in AML was studied using shRNA knockdown and overexpression of PLS3 in Kasumi-1 cells. We could show that PLS3 has an impact on the colony formation capacity of AML cells in vitro as the knockdown resulted in significantly reduced colony numbers while increased colony growth was observed in the Kasumi-1 cells overexpressing PLS3 (p<0.001 and p<0.001, respectively). To investigate the role of PLS3 in vivo, NSG mice were transplanted with the PLS3 knockdown Kasumi-1 cells. Compared to mice transplanted with Kasumi-1 cells transduced with a vector carrying a scrambled shRNA, the PLS3 knockdown mice survived significantly longer (median survival time 64 vs. 110 days, respectively; p<0.001; n=9 mice per group). Finally, we investigated whether the expression of PLS3 was associated with AML patients' outcome using published microarray-based gene expression data (Verhaak et al, Haematologica 2009;94). Clinical data of 290 AML patients were available. Based on the mean gene expression value, the patient cohort was divided into high vs low PLS3 expressors. The overall survival was analyzed in a multivariate Cox proportional hazards model including PLS3 gene expression and the baseline parameters age, karyotype and FLT3 mutational status. After a stepwise removal of insignificant terms, the patient's age and a high PLS3 expression remained as independent prognostic survival markers (for PLS3: HR 1.58 (CI 1.05 - 2.37) and for age: HR 1.01 (CI 1.00 - 1.03)). In conclusion, our results identify the actin binding protein PLS3 as potential novel therapeutic target in AML. Disclosures Stamm: Astellas: Other: Travel, Accommodation, Expenses. Heuser:BerGenBio: Research Funding; Tetralogic: Research Funding; Novartis: Consultancy, Research Funding; Celgene: Honoraria; Bayer Pharma AG: Research Funding; Pfizer: Research Funding; Karyopharm Therapeutics Inc: Research Funding. Fiedler:Kolltan: Research Funding; Ariad/Incyte: Consultancy; Novartis: Consultancy; Gilead: Other: Travel; Teva: Other: Travel; GSO: Other: Travel; Pfizer: Research Funding; Amgen: Consultancy, Other: Travel, Patents & Royalties, Research Funding. Wellbrock:Astellas: Other: Travel, Accommodation, Expenses.

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