scholarly journals Fodrin in the human polymorphonuclear leucocyte: redistribution induced by the chemotactic peptide

1990 ◽  
Vol 96 (3) ◽  
pp. 477-484
Author(s):  
T. Fujimoto ◽  
K. Ogawa
Keyword(s):  
Immunofluorescence Microscopy ◽  
Polymorphonuclear Leucocyte ◽  
Human Neutrophils ◽  
Cell Cortex ◽  
Chemotactic Peptide ◽  
Tail Region ◽  
Head Region ◽  
Posterior Portion ◽  
Skeletal Protein ◽  
Filamentous Cell

Fodrin, a membrane skeletal protein, was found to accumulate in the posterior portion of human neutrophils polarized morphologically after stimulation by the chemotactic peptide, N-formylmethionyl-leucylphenylalanine (FMLP). In most (greater than 90%) unstimulated neutrophils, the distribution of fodrin was found to be uniform by immunofluorescence microscopy. When FMLP (10(−8)M) was applied at 25 degrees C, fodrin became polarized in about 40% of cells by 1 min, about 70% by 2 min, and about 80% by 10 min. The cells with polarized distribution decreased thereafter to about 60% of the cells at 20 min and about 20% at 60 min. Using the under-agarose system, it was confirmed that the concentration of fodrin occurred in the region opposite to the direction of chemoattraction in moving cells. By immunoelectron microscopy, most of the labeling for fodrin was observed in the filamentous cell cortex and not associated with the plasma membrane itself. In cells polarized morphologically by FMLP, the fodrin labeling became concentrated in the posterior portion of the cell; the labeling was found most densely in the granule-rich cytoplasm, while the filamentous tail region was not labeled intensely. The lamellipodium in the head region was also labeled only sparsely. The results indicate that in human neutrophils fodrin exists as a cytoskeletal protein rather than as a membrane protein and that the protein accumulates in the endoplasm of the posterior portion in migrating cells. The rearrangement is likely to modulate the organization of the actin-rich cell cortex for cell locomotion.

scholarly journals Reniform Nematode, Rotylenchulus reniformis Linford & Oliveira (Nematoda: Tylenchida: Tylenchoidea: Hoplolaimidae: Rotylenchulinae)

EDIS ◽  
1969 ◽  
Vol 2004 (9) ◽  
Author(s):  
Koon-Hui Wang
Keyword(s):  
The Body ◽  
Reniform Nematode ◽  
Rotylenchulus Reniformis ◽  
Tail Region ◽  
Head Region ◽  
Anterior Portion ◽  
Root Cortex ◽  
Important Species ◽  
Posterior Portion ◽  
Feeding Site

Reniform nematodes in the genus Rotylenchulus are semiendoparasitic (partially inside roots) species in which the females penetrate the root cortex, establish a permanent-feeding site in the stele region of the root and become sedentary or immobile. The anterior portion (head region) of the body remains embedded in the root whereas the posterior portion (tail region) protrudes from the root surface and swells during maturation. The term 'reniform' refers to the kidney-shaped body of the mature female. There are ten species in the genus Rotylenchulus. Rotylenchulus reniformis is the most economically important species (Robinson 1997 ) and is called the reniform nematode. This document is EENY-210, one of a series of Featured Creatures from the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: May 2001.  EENY-210/IN367: Reniform Nematode, Rotylenchulus reniformis Linford and Oliveira (Nematoda: Tylenchida: Tylenchoidea: Hoplolaimidae: Rotylenchulinae) (ufl.edu)

scholarly journals Protein phosphatase inhibitors okadaic acid and calyculin A alter cell shape and F-actin distribution and inhibit stimulus-dependent increases in cytoskeletal actin of human neutrophils

Blood ◽  
1992 ◽  
Vol 80 (11) ◽  
pp. 2911-2919 ◽  
Author(s):  
P Kreienbuhl ◽  
H Keller ◽  
V Niggli
Keyword(s):  
Okadaic Acid ◽  
Human Neutrophils ◽  
Resting Cells ◽  
Calyculin A ◽  
Chemotactic Peptide ◽  
Phosphatase Inhibitors ◽  
Protein Phosphatase Inhibitors ◽  
Actin Localization ◽  
Shape Changes

Abstract The phosphatase inhibitors okadaic acid and calyculin A were found to elicit or to modify several neutrophil responses, suggesting that dephosphorylation plays a regulatory role. The concentrations of okadaic acid (> or = 1 mumol/L) that were effective on neutrophil functions (shape changes and marginal stimulation of pinocytosis) were shown to stimulate the incorporation of 32PO4 into many neutrophil proteins several-fold. Calyculin A was effective at 50-fold lower concentrations. In the presence of the inhibitors, the cells exhibited a nonpolar shape and the polarization response induced by chemotactic peptide was inhibited. Both phosphatase inhibitors also induced the association of F-actin with the cell membrane. A steady-state phosphatase activity is thus involved in maintaining shape and F-actin localization of resting cells. Inhibitors alone had no significant effect on the amount of cytoskeleton-associated actin. The increase in cytoskeletal actin observed at 30 minutes of stimulation with phorbol ester or 5 to 30 minutes of stimulation with chemotactic peptide, however, was abolished by okadaic acid or calyculin A, suggesting an important role of a phosphatase. In contrast, the early increase in cytoskeleton-associated actin observed at 1 minute of stimulation with peptide was not affected. This finding indicates that the increased association of actin with the cytoskeleton in the early and the later stages of neutrophil activation may be mediated by different signalling pathways.

scholarly journals Primary granule exocytosis in human neutrophils is regulated by Rac-dependent actin remodeling

2008 ◽  
Vol 295 (5) ◽  
pp. C1354-C1365 ◽  
Author(s):  
Troy Mitchell ◽  
Andrea Lo ◽  
Michael R. Logan ◽  
Paige Lacy ◽  
Gary Eitzen
Keyword(s):  
Actin Polymerization ◽  
Microscopic Analysis ◽  
Formyl Peptide Receptor ◽  
Human Neutrophils ◽  
Cell Cortex ◽  
Secretory Cells ◽  
Actin Remodeling ◽  
Granule Exocytosis ◽  
Primary Granule

The actin cytoskeleton regulates exocytosis in all secretory cells. In neutrophils, Rac2 GTPase has been shown to control primary (azurophilic) granule exocytosis. In this report, we propose that Rac2 is required for actin cytoskeletal remodeling to promote primary granule exocytosis. Treatment of neutrophils with low doses (≤10 μM) of the actin-depolymerizing drugs latrunculin B (Lat B) or cytochalasin B (CB) enhanced both formyl peptide receptor- and Ca2+ionophore-stimulated exocytosis. Higher concentrations of CB or Lat B, or stabilization of F-actin with jasplakinolide (JP), inhibited primary granule exocytosis measured as myeloperoxidase release but did not affect secondary granule exocytosis determined by lactoferrin release. These results suggest an obligatory role for F-actin disassembly before primary granule exocytosis. However, lysates from secretagogue-stimulated neutrophils showed enhanced actin polymerization activity in vitro. Microscopic analysis showed that resting neutrophils contain significant cortical F-actin, which was redistributed to sites of primary granule translocation when stimulated. Exocytosis and actin remodeling was highly polarized when cells were primed with CB; however, polarization was reduced by Lat B preincubation, and both polarization and exocytosis were blocked when F-actin was stabilized with JP. Treatment of cells with the small molecule Rac inhibitor NSC23766 also inhibited actin remodeling and primary granule exocytosis induced by Lat B/fMLF or CB/fMLF, but not by Ca2+ionophore. Therefore, we propose a role for F-actin depolymerization at the cell cortex coupled with Rac-dependent F-actin polymerization in the cell cytoplasm to promote primary granule exocytosis.

scholarly journals Regulation of CD18 expression in human neutrophils as related to shape changes

1993 ◽  
Vol 106 (2) ◽  
pp. 493-501
Author(s):  
A. Volz
Keyword(s):  
Phorbol Myristate Acetate ◽  
Surface Expression ◽  
Cytochalasin D ◽  
Human Neutrophils ◽  
Chemotactic Peptide ◽  
Myristate Acetate ◽  
Surface Distribution ◽  
Quantitative Expression ◽  
High Concentrations ◽  
Shape Changes

The study analyses the distribution and quantitative expression of surface CD18 of neutrophils exposed to distinct stimuli that produce different types of continuous shape changes, including types that are associated with locomotion and others that are not. The chemotactic peptide N-formyl-L-norleucyl-L-leucyl-L-phenylalanine, colchicine and nocodazole were used to induce a polarized locomotor morphology, phorbol myristate acetate, 1,2-dioctanoylglycerol and 1-oleoyl-2-acetyl-glycerol to induce non-polar motile cells ruffling all over the surface and 2H2O to induce non-polar cells performing circus movements as have been previously described. Except for colchicine and nocodazole, these stimuli increased surface expression of CD18. Thus, stimulated shape changes are frequently, though not always, associated with increased surface expression of CD18. High concentrations (10(−7) to 10(−5) M) of phorbol myristate acetate but not of chemotactic peptide induced down-regulation of surface CD18. Cytochalasin D (10(−4) M) stimulated CD18 expression even though it inhibited shape changes. The surface distribution of CD18 determined by light microscopy was uniform in unstimulated cells or in various forms of stimulation except for cells treated with 10(−5) M cytochalasin D. Cytochalasin D (10(−5) M) produced CD18 accumulation at the pole opposite the F-actin cap. Experiments with colchicine, nocodazole, 2H2O and cytochalasin D suggest that microtubules as well as microfilaments modulate surface expression of CD18. The results suggest that protein kinase C and phosphatases play a role in regulating surface expression of CD18 in neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Thrombospondin receptor expression in human neutrophils coincides with the release of a subpopulation of specific granules

1992 ◽  
Vol 284 (2) ◽  
pp. 513-520 ◽  
Author(s):  
S J Suchard ◽  
M J Burton ◽  
S J Stoehr
Keyword(s):  
Cytochalasin B ◽  
Anion Channel ◽  
Polymorphonuclear Leucocyte ◽  
Receptor Expression ◽  
Human Neutrophils ◽  
Ionophore A23187 ◽  
Surface Receptors ◽  
Specific Granules ◽  
Azurophil Granule ◽  
Disulphonic Acid

The extracellular matrix (ECM) protein thrombospondin (TSP) binds specifically to polymorphonuclear leucocyte (PMN) surface receptors and promotes cell adhesion and motility. TSP receptor expression increases 30-fold after activation with the synthetic chemotactic peptide, N-formylmethionyl-leucylphenylalanine (FMLP) or the Ca2+ ionophore A23187, in combination with cytochalasin B. The expression of TSP receptors was correlated with the exocytosis of both specific and azurophil granules. Newly expressed TSP receptors are not derived from easily mobilized specific granules since agents that trigger some specific granule release [phorbol myristate acetate (PMA), FMLP or ionophore A23187 alone] do not increase TSP receptor expression. In this study we used the anion-channel blocker, 4,4′-di-isothiocyanatostilbene-2,2′-disulphonic acid (DIDS) to investigate the source of these newly expressed receptors. When PMNs were exposed to cytochalasin B and FMLP or to cytochalasin B and ionophore A23187 in the presence of 30-100 microM-DIDS, TSP receptor expression increased coincidently with vitamin B12-binding protein release from specific granules. Under these same conditions, the release of the azurophil granule component, myeloperoxidase, was significantly inhibited. Using agonists that cause release of specific granules, or both specific granules and azurophil granules, we determined that DIDS blocked the release of PMA-mobilized specific granules and cytochalasin B plus FMLP- or cytochalasin B plus ionophore A23187-mobilized myeloperoxidase-containing azurophil granules but not specific granules mobilized by cytochalasin B plus FMLP or cytochalasin B plus ionophore A23187. These results suggested that PMNs contain at least two subpopulations of specific granules: one that is easily mobilized, lacks TSP receptors and is inhibitable by DIDS, and one that is difficult to mobilize, contains a large pool of TSP receptors and the release of which is enhanced in the presence of DIDS.

Sla1p couples the yeast endocytic machinery to proteins regulating actin dynamics

2002 ◽  
Vol 115 (8) ◽  
pp. 1703-1715 ◽  
Author(s):  
Derek T. Warren ◽  
Paul D. Andrews ◽  
Campbell W. Gourlay ◽  
Kathryn R. Ayscough
Keyword(s):  
Immunofluorescence Microscopy ◽  
Fluid Phase ◽  
Actin Dynamics ◽  
Cell Cortex ◽  
Cortical Actin ◽  
Binding Studies ◽  
Endocytic Machinery ◽  
Single Complex ◽  
Actin Patch ◽  
First Time

Sla1p is a protein required for cortical actin patch structure and organisation in budding yeast. Here we use a combination of immunofluorescence microscopy and biochemical approaches to demonstrate interactions of Sla1p both with proteins regulating actin dynamics and with proteins required for endocytosis. Using Sla1p-binding studies we reveal association of Sla1p with two proteins known to be important for activation of the Arp2/3 complex in yeast, Abp1p and the yeast WASP homologue Las17p/Bee1p. A recent report of Sla1p association with Pan1p puts Sla1p in the currently unique position of being the only yeast protein known to interact with all three known Arp2/3-activating proteins in yeast. Localisation of Sla1p at the cell cortex is, however, dependent on the EH-domain-containing protein End3p, which is part of the yeast endocytic machinery. Using spectral variants of GFP on Sla1p(YFP) and on Abp1p (CFP) we show for the first time that these proteins can exist in discrete complexes at the cell cortex. However, the detection of a significant FRET signal means that these proteins also come close together in a single complex, and it is in this larger complex that we propose that Sla1p binding to Abp1p and Las17p/Bee1p is able to link actin dynamics to the endocytic machinery. Finally, we demonstrate marked defects in both fluid-phase and receptor-mediated endocytosis in cells that do not express SLA1, indicating that Sla1p is central to the requirement in yeast to couple endocytosis with the actin cytoskeleton.

scholarly journals Cytosolic free calcium changes induced by chemotactic peptide in neutrophils from patients with chronic granulomatous disease

Blood ◽  
1984 ◽  
Vol 63 (1) ◽  
pp. 231-233 ◽  
Author(s):  
PD Lew ◽  
C Wollheim ◽  
RA Seger ◽  
T Pozzan
Keyword(s):  
Chronic Granulomatous Disease ◽  
Calcium Concentration ◽  
Cytosolic Calcium ◽  
Human Neutrophils ◽  
Free Calcium ◽  
Granulomatous Disease ◽  
Chemotactic Peptide ◽  
Intact Cells ◽  
Calcium Indicator ◽  
Free Calcium Concentration

Abstract Cytoplasmic free calcium concentration (Ca2+)i was measured in neutrophils from patients with the classical X-linked form of chronic granulomatous disease (CGD) by trapping the fluorescent calcium indicator Quin 2 in intact cells. CGD neutrophils do not produce superoxide and are only slightly depolarized upon stimulation by the chemotactic peptide. N-formyl-methionyl-leucyl-phenylalanine (FMLP). The resting levels, as well as (Ca2+)i changes induced by FMLP in CGD cells, were quantitatively and kinetically similar to those observed in normal cells. We conclude that the defect in CGD cells is distal to, or independent of, the changes in (Ca2+)i induced by FMLP stimulation and that normal membrane depolarization does not seem to be necessary for receptor-mediated rise in free cytosolic calcium in human neutrophils.

A Novel Cytokine That Activates Human Neutrophils

1989 ◽  
Vol 2 (2) ◽  
pp. 63-65
Author(s):  
M. Baggiolini ◽  
A. Walz ◽  
P. Peveri ◽  
B. Dewald
Keyword(s):  
Amino Acids ◽  
Mononuclear Phagocytes ◽  
Human Neutrophils ◽  
Chemotactic Peptide ◽  
Amino Terminal ◽  
Major Form

A novel neutrophil-activating peptide was recently characterized by different laboratories and named NAF (neutrophil-activating factor) (Walz et al., 1987) MDNCF (monocyte-derived neutrophil chemotactic peptide) (Yoshimura et al., 1987) and MONAP (monocyte-derived neutrophil-activating peptide) (Gregory et al., 1988). The peptide detected in the culture fluids of stimulated human mononuclear phagocytes consists of 72 amino acids. Minor amino-terminal truncation variants are also found (Lindley et al., 1988). The major form was now obtained by recombinant methods and was shown to be biologically equivalent to purified natural NAF (Lindley et al., 1988).

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