scholarly journals Ras Inhibitor CAPRI Enables Neutrophils to Chemotax Through a Higher-Concentration Range of Gradients

2020 ◽  
Author(s):  
Xuehua Xu ◽  
Xi Wen ◽  
Amer Moosa ◽  
Smit Bhimani ◽  
Tian Jin
Keyword(s):  
Actin Polymerization ◽  
Human Neutrophils ◽  
Inhibitory Mechanism ◽  
High Concentration ◽  
Concentration Gradients ◽  
First Line ◽  
Enhanced Sensitivity ◽  
Gpcr Activation ◽  
Ras Activation ◽  
First Time

AbstractNeutrophils sense and migrate through an enormous range of chemoattractant gradients through adaptation. Here, we reveal that, in human neutrophils, Calcium-promoted Ras inactivator (CAPRI) locally controls the GPCR-stimulated Ras adaptation. Human neutrophils lacking CAPRI (caprikd) exhibit chemoattractant-induced non-adaptive Ras activation; significantly increased phosphorylation of AKT, GSK3α/3β, and cofilin; and excessive actin polymerization. caprikd cells display defective chemotaxis in response to high-concentration gradients but exhibit improved chemotaxis in low- or subsensitive-concentration gradients of various chemoattractants as a result of their enhanced sensitivity. Taken together, our data reveal that CAPRI controls GPCR activation-mediated Ras adaptation and lowers the sensitivity of human neutrophils so that they are able to chemotax through a higher concentration range of chemoattractant gradients.Significance StatementNeutrophils provide first-line host defense by migrating through chemoattractant gradients to the sites of inflammation. Inappropriate recruitment and mis-regulated activation of neutrophils contribute to tissue damage and cause autoimmune and inflammatory disease. One fascinating feature of chemotactic neutrophils is their ability to migrate through an enormous concentration range of chemoattractant gradients (10−9 ∼ 10−5 M) through “adaptation,” in which cells no longer respond to the present stimuli, but remain sensitive to stronger stimuli. The inhibitory mechanism largely remains elusive, although many molecules of the excitatory signaling pathway have been identified. Our study reveals, for the first time, that the inhibitory component, CAPRI, is essential for both the sensitivity and the GPCR-mediated adaptation of human neutrophils.

Ras inhibitor CAPRI enables neutrophil-like cells to chemotax through a higher-concentration range of gradients

2021 ◽  
Vol 118 (43) ◽  
pp. e2002162118
Author(s):  
Xuehua Xu ◽  
Xi Wen ◽  
Amer Moosa ◽  
Smit Bhimani ◽  
Tian Jin
Keyword(s):  
Actin Polymerization ◽  
Human Neutrophils ◽  
High Concentration ◽  
Concentration Gradients ◽  
Enhanced Sensitivity ◽  
Gpcr Activation ◽  
Ras Activation

Neutrophils sense and migrate through an enormous range of chemoattractant gradients through adaptation. Here, we reveal that in human neutrophils, calcium-promoted Ras inactivator (CAPRI) locally controls the GPCR-stimulated Ras adaptation. Human neutrophils lacking CAPRI (caprikd) exhibit chemoattractant-induced, nonadaptive Ras activation; significantly increased phosphorylation of AKT, GSK-3α/3β, and cofilin; and excessive actin polymerization. caprikd cells display defective chemotaxis in response to high-concentration gradients but exhibit improved chemotaxis in low- or subsensitive-concentration gradients of various chemoattractants, as a result of their enhanced sensitivity. Taken together, our data reveal that CAPRI controls GPCR activation-mediated Ras adaptation and lowers the sensitivity of human neutrophils so that they are able to chemotax through a higher-concentration range of chemoattractant gradients.

scholarly journals Extracellular Nucleic Acids Present in the Candida albicans Biofilm Trigger the Release of Neutrophil Extracellular Traps

2021 ◽  
Vol 11 ◽  
Author(s):  
Magdalena Smolarz ◽  
Marcin Zawrotniak ◽  
Dorota Satala ◽  
Maria Rapala-Kozik
Keyword(s):  
Candida Albicans ◽  
Nucleic Acids ◽  
Fungal Infection ◽  
Fungal Infections ◽  
Neutrophil Extracellular Traps ◽  
Human Neutrophils ◽  
High Concentration ◽  
First Line ◽  
Extracellular Traps ◽  
Biofilm Structure

Neutrophils, the first line of the host’s defense, use a variety of antimicrobial mechanisms to fight invading pathogens. One of the most crucial is the production of neutrophil extracellular traps (NETs) in the process called NETosis. The unique structure of NETs effectively inhibits the spread of pathogens and ensures their exposure to a high concentration of NET-embedded antimicrobial compounds. NETosis strategy is often used by the host to defend against fungal infection caused by Candida albicans. In immunocompromised patients, this microorganism is responsible for developing systemic fungal infections (candidiasis). This is correlated with the use of a vast array of virulence factors, leading to the acquisition of specific resistance to host defense factors and available drug therapies. One of the most important features favoring the development of drug resistance is a C. albicans ability to form biofilms that protect fungal cells mainly through the production of an extracellular matrix (ECM). Among the main ECM-building macromolecules extracellular nucleic acids have been identified and their role is probably associated with the stbilization of the biofilm structure. The complex interactions of immune cells with the thick ECM layer, comprising the first line of contact between these cells and the biofilm structure, are still poorly understood. Therefore, the current studies aimed to assess the release of extracellular nucleic acids by C. albicans strains at different stages of biofilm formation, and to determine the role of these molecules in triggering the NETosis. We showed for the first time that fungal nucleic acids, purified directly from mature C. albicans biofilm structure or obtained from the whole fungal cells, have the potential to induce NET release in vitro. In this study, we considered the involvement of TLR8 and TLR9 in NETosis activation. We showed that DNA and RNA molecules initiated the production of reactive oxygen species (ROS) by activation of the NADPH oxidase complex, essential for ROS-dependent NETosis. Furthermore, analysis of the cell migration showed that the nucleic acids located in the extracellular space surrounding the biofilm may be also effective chemotactic factors, driving the dynamic migration of human neutrophils to the site of ongoing fungal infection.

Decline of contractility during ischemia-reperfusion injury: actin glutathionylation and its effect on allosteric interaction with tropomyosin

2006 ◽  
Vol 290 (3) ◽  
pp. C719-C727 ◽  
Author(s):  
Frank C. Chen ◽  
Ozgur Ogut
Keyword(s):  
Reperfusion Injury ◽  
Posttranslational Modifications ◽  
Actin Polymerization ◽  
Time Course ◽  
Troponin I ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
High Concentration ◽  
Cross Sectional ◽  
The Impact

The severity and duration of ischemia-reperfusion injury is hypothesized to play an important role in the ability of the heart subsequently to recover contractility. Permeabilized trabeculae were prepared from a rat model of ischemia-reperfusion injury to examine the impact on force generation. Compared with the control perfused condition, the maximum force (Fmax) per cross-sectional area and the rate of tension redevelopment of Ca2+-activated trabeculae fell by 71% and 44%, respectively, during ischemia despite the availability of a high concentration of ATP. The reduction in Fmax with ischemia was accompanied by a decline in fiber stiffness, implying a drop in the absolute number of attached cross bridges. However, the declines during ischemia were largely recovered after reperfusion, leading to the hypothesis that intrinsic, reversible posttranslational modifications to proteins of the contractile filaments occur during ischemia-reperfusion injury. Examination of thin-filament proteins from ischemic or ischemia-reperfused hearts did not reveal proteolysis of troponin I or T. However, actin was found to be glutathionylated with ischemia. Light-scattering experiments demonstrated that glutathionylated G-actin did not polymerize as efficiently as native G-actin. Although tropomyosin accelerated the time course of native and glutathionylated G-actin polymerization, the polymerization of glutathionylated G-actin still lagged native G-actin at all concentrations of tropomyosin tested. Furthermore, cosedimentation experiments demonstrated that tropomyosin bound glutathionylated F-actin with significantly reduced cooperativity. Therefore, glutathionylated actin may be a novel contributor to the diverse set of posttranslational modifications that define the function of the contractile filaments during ischemia-reperfusion injury.

Actin Polymerization, Calcium-Transients, and Phospholipid Metabolism in Human Neutrophils After Stimulation with Interleukin-8 and N-formyl Peptide

1994 ◽  
Vol 102 (3) ◽  
pp. 310-314 ◽  
Author(s):  
Johannes Norgauer ◽  
Jean Krutmann ◽  
Gustav J. Dobos ◽  
Alexis E. Traynor-Kaplan ◽  
Zenaida G. Oades ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Phospholipid Metabolism ◽  
Interleukin 8 ◽  
Calcium Transients ◽  
Human Neutrophils ◽  
Formyl Peptide

ARCHITECTURE OF FLOWER-LIKE rGO/CNTs-LOADED CuxO NANOPARTICLES AND ITS PHOTOCATALYTIC PROPERTIES

NANO ◽  
2013 ◽  
Vol 08 (05) ◽  
pp. 1350052 ◽  
Author(s):  
BIN ZENG ◽  
XIAOHUA CHEN ◽  
XUTAO NING ◽  
CHUANSHENG CHEN ◽  
HUI LONG
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Performance ◽  
Degradation Process ◽  
Photocatalytic Properties ◽  
High Concentration ◽  
Graphene Oxides ◽  
Transmission Electron ◽  
Time Scanning ◽  
Reduced Graphene ◽  
First Time

Novel flower-like composite architecture was successfully synthesized by spray drying and post-calcinating method for the first time. Scanning electron microscopy and transmission electron microscopy observations confirmed that reduced graphene oxides/carbon nanotubes hybrid (rGO/CNTs) formed a flower-like micrometer structure and Cu2O , CuO ( Cu x O , x = 1 or 2) nanoparticles were decorated inside them. The photocatalytic properties were further investigated by evaluating the photodegradation of a pollutant methyl orange (MO). The experimental results indicated that this novel architecture enhanced photocatalytic performance with 96.2% decomposition of MO after 25 min in the presence of H 2 O 2 under visible light irradiation, which was much higher than that of Cu x O powders (33.2%). This could be attributed to the more efficient adsorption of MO molecules on flower-like rGO/CNTs and provide a high concentration of MO near to the Cu x O nanoparticles, thus promoting the photocatalytic degradation process.

scholarly journals Intermittent Hypoxia Affects the Spontaneous DifferentiationIn Vitroof Human Neutrophils into Long-Lived Giant Phagocytes

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Larissa Dyugovskaya ◽  
Slava Berger ◽  
Andrey Polyakov ◽  
Peretz Lavie ◽  
Lena Lavie
Keyword(s):  
Nadph Oxidase ◽  
Intermittent Hypoxia ◽  
Oxidase Inhibitor ◽  
Human Neutrophils ◽  
Hypoxic Conditions ◽  
Oxygen Conditions ◽  
Extended Lifespan ◽  
First Time ◽  
Dose Dependent

Previously we identified, for the first time, a new small-size subset of neutrophil-derived giant phagocytes (Gϕ) which spontaneously developin vitrowithout additional growth factors or cytokines. Gϕare CD66b+/CD63+/MPO+/LC3B+and are characterized by extended lifespan, large phagolysosomes, active phagocytosis, and reactive oxygen species (ROS) production, and autophagy largely controls their formation. Hypoxia, and particularly hypoxia/reoxygenation, is a prominent feature of many pathological processes. Herein we investigated Gϕformation by applying various hypoxic conditions. Chronic intermittent hypoxia (IH) (29 cycles/day for 5 days) completely abolished Gϕformation, while acute IH had dose-dependent effects. Exposure to 24 h (56 IH cycles) decreased their size, yield, phagocytic ability, autophagy, mitophagy, and gp91-phox/p22-phoxexpression, whereas under 24 h sustained hypoxia (SH) the size and expression of LC3B and gp91-phox/p22-phoxresembled Gϕformed in normoxia. Diphenyl iodide (DPI), a NADPH oxidase inhibitor, as well as the PI3K/Akt and autophagy inhibitor LY294002 abolished Gϕformation at all oxygen conditions. However, the potent antioxidant, N-acetylcysteine (NAC) abrogated the effects of IH by inducing large CD66b+/LC3B+Gϕand increased both NADPH oxidase expression and phagocytosis. These findings suggest that NADPH oxidase, autophagy, and the PI3K/Akt pathway are involved in Gϕdevelopment.

The protein kinase C inhibitor H-7 activates human neutrophils: effect on shape, actin polymerization, fluid pinocytosis and locomotion

1990 ◽  
Vol 96 (1) ◽  
pp. 99-106
Author(s):  
H.U. Keller ◽  
V. Niggli ◽  
A. Zimmermann ◽  
R. Portmann
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Actin Polymerization ◽  
Kinase Inhibitor ◽  
Human Neutrophils ◽  
Kinase C ◽  
Chemotactic Peptides ◽  
Protein Kinase C Inhibitor ◽  
Shape Changes ◽  
Stimulation Of

The present study demonstrates new properties of H-7. The protein kinase inhibitor H-7 is a potent activator of several neutrophil functions. Stimulation of initially spherical nonmotile neutrophils elicits vigorous shape changes within a few seconds, increases in cytoskeletal actin, altered F-actin distribution, increased adhesiveness and a relatively small increase in pinocytic activity. H-7 has also chemokinetic activities. Depending on the experimental condition, H-7 may elicit or inhibit neutrophil locomotion. It failed to induce chemotaxis. Thus, the response pattern elicited by H-7 is different from that of other leukocyte activators such as chemotactic peptides, PMA or diacylglycerols. The finding that H-7 can elicit shape changes, actin polymerization and pinocytosis suggests that these events can occur without activation of protein kinase C (PKC). PMA-induced shape changes and stimulation of pinocytosis were not inhibited by H-7.

scholarly journals Activation of human neutrophils by mastoparan. Reorganization of the cytoskeleton, formation of phosphatidylinositol 3,4,5-trisphosphate, secretion up-regulation of complement receptor type 3 and superoxide anion production are stimulated by mastoparan

1992 ◽  
Vol 282 (2) ◽  
pp. 393-397 ◽  
Author(s):  
J Norgauer ◽  
M Eberle ◽  
H D Lemke ◽  
K Aktories
Keyword(s):  
Pertussis Toxin ◽  
Actin Polymerization ◽  
Cytochalasin B ◽  
Superoxide Radical ◽  
Human Neutrophils ◽  
Superoxide Anion Production ◽  
Radical Production ◽  
Rapid Formation ◽  
Primary Granules ◽  
Type 3

In human neutrophils, mastoparan induced rapid F-actin polymerization which was followed by a slow and sustained depolymerization to below the initial F-actin content. Incubation of neutrophils with pertussis toxin inhibited mastoparan-stimulated actin polymerization; however it did not prevent sustained depolymerization of F-actin. Analyses of phospholipids performed in parallel revealed that mastoparan stimulated rapid formation of phosphatidylinositol 3,4,5-trisphosphate (PIP3) and consumption of phosphatidylinositol 4,5-bisphosphate (PIP2). Pertussis toxin treatment blocked mastoparan-induced formation of PIP3. Furthermore, mastoparan stimulated the release of N-acetylglucosaminidase from primary granules. Cytochalasin B enhanced mastoparan-stimulated secretion. Mastoparan triggered superoxide radical production in a cytochalasin B-sensitive manner and induced complement type 3 receptor (CR3) up-regulation.

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 Evaluation of volatile constituents, exudation of resin and occurrence of galls of Protium aracouchini (Aubl.) Marchand

2021 ◽  
Vol 5 (3) ◽  
pp. 88
Author(s):  
Thiago Augusto Araujo Correia Lima (in memorian) ◽  
Leonardo Pinto Cunha ◽  
José Eduardo Lahoz da Silva Ribeiro ◽  
Marcia Ortiz Mayo Marques ◽  
Maria da Paz Lima
Keyword(s):  
Essential Oil ◽  
Essential Oils ◽  
Chemical Constituents ◽  
Brazilian Amazon ◽  
High Concentration ◽  
Forest Reserve ◽  
Volatile Constituents ◽  
Aerial Parts ◽  
First Time ◽  
Time Information

Protium aracouchini (Aubl.) Marchand [sin Icica aracouchini Aubl.], which occurs in the Adolpho Ducke Forest Reserve, in the Brazilian Amazon, was evaluated for the presence of galls, for resin exudation and the composition of the essential oils from the aerial parts and the resin. The experiment to stimulate the exudation of resin from the trunk was conducted using a 2-chloroethylphosphonic acid solution. The resin produced after 40 days and the aerial parts had their essential oils extracted in a Clevenger apparatus and the volatile chemical constituents were analyzed using GC/MS. The non-oxygenated sesquiterpenes α-copaene (21.15%) and α-gurjunene (13.69%), in addition to the oxygenated sesquiterpene spathulenol (10.32%), were detected as the majority constituents of the essential oil of the leaves, and a concentration similar to that of α-gurjunene was found in the branches (13.28%). The resin essential oil showed a high concentration of hydrocarbon monoterpenes (76.49%) with a predominance of α-pinene (17.57%) and limonene (46.11%). Four gall morphotypes were found associated with this species. The present study reports for the first time information on the volatile constituents and the resinous potential of P. aracouchini, and registers the morphotypes of the galls that help in the taxonomy of the species.

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