scholarly journals Regulators and Effectors of Arf GTPases in Neutrophils

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Jouda Gamara ◽  
François Chouinard ◽  
Lynn Davis ◽  
Fawzi Aoudjit ◽  
Sylvain G. Bourgoin
Keyword(s):  
Molecular Mechanisms ◽  
Proteolytic Enzymes ◽  
Leading Edge ◽  
Cell Polarization ◽  
Polymorphonuclear Neutrophils ◽  
Cellular Events ◽  
Gtpase Activating Proteins ◽  
Nadph Oxidase Complex ◽  
Pmn Functions ◽  
Phagosomal Membrane

Polymorphonuclear neutrophils (PMNs) are key innate immune cells that represent the first line of defence against infection. They are the first leukocytes to migrate from the blood to injured or infected sites. This process involves molecular mechanisms that coordinate cell polarization, delivery of receptors, and activation of integrins at the leading edge of migrating PMNs. These phagocytes actively engulf microorganisms or form neutrophil extracellular traps (NETs) to trap and kill pathogens with bactericidal compounds. Association of the NADPH oxidase complex at the phagosomal membrane for production of reactive oxygen species (ROS) and delivery of proteolytic enzymes into the phagosome initiate pathogen killing and removal. G protein-dependent signalling pathways tightly control PMN functions. In this review, we will focus on the small monomeric GTPases of the Arf family and their guanine exchange factors (GEFs) and GTPase activating proteins (GAPs) as components of signalling cascades regulating PMN responses. GEFs and GAPs are multidomain proteins that control cellular events in time and space through interaction with other proteins and lipids inside the cells. The number of Arf GAPs identified in PMNs is expanding, and dissecting their functions will provide important insights into the role of these proteins in PMN physiology.

Neutrophil activation via β2 integrins (CD11/CD18): Molecular mechanisms and clinical implications

2007 ◽  
Vol 98 (08) ◽  
pp. 262-273 ◽  
Author(s):  
Jürgen Schymeinsky ◽  
Attila Mócsai ◽  
Barbara Walzog
Keyword(s):  
Receptor Tyrosine Kinase ◽  
Acute Inflammation ◽  
Molecular Mechanisms ◽  
Inflammatory Diseases ◽  
Polymorphonuclear Neutrophils ◽  
Downstream Signaling ◽  
Β2 Integrin ◽  
Pmn Functions ◽  
Integrin Family ◽  
Β2 Integrins

SummaryPolymorphonuclear neutrophils (PMN) are key components of the innate immunity and their efficient recruitment to the sites of lesion is a prerequisite for acute inflammation. Signaling via adhesion molecules of the β2 integrin family (CD11/CD18) plays an essential role for PMN recruitment and activation during inflammation. In this review, we will focus on the non-receptor tyrosine kinase Syk, an important downstream signaling component of β2 integrins that is required for the control of different PMN functions including adhesion,migration and phagocytosis. The exploration of β2 integrin-mediated Syk activation provided not only novel insights into the control of PMN functions but also led to the identification of Syk as a new molecular target for therapeutic intervention during inflammatory diseases.

scholarly journals Type Iγ PIP Kinase Is a Novel Uropod Component that Regulates Rear Retraction during Neutrophil Chemotaxis

2007 ◽  
Vol 18 (12) ◽  
pp. 5069-5080 ◽  
Author(s):  
Mary A. Lokuta ◽  
Melissa A. Senetar ◽  
David A. Bennin ◽  
Paul A. Nuzzi ◽  
Keefe T. Chan ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Leading Edge ◽  
Time Lapse ◽  
Cell Polarization ◽  
Neutrophil Chemotaxis ◽  
Directed Migration ◽  
Time Lapse Microscopy ◽  
Phosphatidylinositol Phosphate ◽  
Phosphoinositide 3 Kinase ◽  
Made In

Cell polarization is necessary for directed migration and leukocyte recruitment to inflamed tissues. Recent progress has been made in defining the molecular mechanisms that regulate chemoattractant-induced cell polarity during chemotaxis, including the contribution of phosphoinositide 3-kinase (PI3K)-dependent phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P3] synthesis at the leading edge. However, less is known about the molecular composition of the cell rear and how the uropod functions during cell motility. Here, we demonstrate that phosphatidylinositol phosphate kinase type Iγ (PIPKIγ661), which generates PtdIns(4,5)P2, is enriched in the uropod during chemotaxis of primary neutrophils and differentiated HL-60 cells (dHL-60). Using time-lapse microscopy, we show that enrichment of PIPKIγ661 at the cell rear occurs early upon chemoattractant stimulation and is persistent during chemotaxis. Accordingly, we were able to detect enrichment of PtdIns(4,5)P2at the uropod during chemotaxis. Overexpression of kinase-dead PIPKIγ661 compromised uropod formation and rear retraction similar to inhibition of ROCK signaling, suggesting that PtdIns(4,5)P2synthesis is important to elicit the backness response during chemotaxis. Together, our findings identify a previously unknown function for PIPKIγ661 as a novel component of the backness signal that regulates rear retraction during chemotaxis.

The Signaling Pathways in Nitric Oxide Production by Neutrophils Exposed to N-nitrosodimethylamine

2018 ◽  
Vol 16 (2) ◽  
pp. 194-199
Author(s):  
Wioletta Ratajczak-Wrona ◽  
Ewa Jablonska
Keyword(s):  
Nitric Oxide ◽  
Signaling Pathways ◽  
Molecular Mechanisms ◽  
Polymorphonuclear Neutrophils ◽  
Microbial Pathogens ◽  
Human Neutrophils ◽  
No Production ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

Background: Polymorphonuclear neutrophils (PMNs) play a crucial role in the innate immune system’s response to microbial pathogens through the release of reactive nitrogen species, including Nitric Oxide (NO). </P><P> Methods: In neutrophils, NO is produced by the inducible Nitric Oxide Synthase (iNOS), which is regulated by various signaling pathways and transcription factors. N-nitrosodimethylamine (NDMA), a potential human carcinogen, affects immune cells. NDMA plays a major part in the growing incidence of cancers. Thanks to the increasing knowledge on the toxicological role of NDMA, the environmental factors that condition the exposure to this compound, especially its precursors- nitrates arouse wide concern. Results: In this article, we present a detailed summary of the molecular mechanisms of NDMA’s effect on the iNOS-dependent NO production in human neutrophils. Conclusion: This research contributes to a more complete understanding of the mechanisms that explain the changes that occur during nonspecific cellular responses to NDMA toxicity.

A novel coagulation inhibitor fromSchistosoma japonicum

Parasitology ◽  
2015 ◽  
Vol 142 (14) ◽  
pp. 1663-1672 ◽  
Author(s):  
SHIWANTHI L. RANASINGHE ◽  
KATJA FISCHER ◽  
GEOFFREY N. GOBERT ◽  
DONALD P. MCMANUS
Keyword(s):  
Human Blood ◽  
Neutrophil Elastase ◽  
Molecular Mechanisms ◽  
Genomic Sequence ◽  
Proteolytic Enzymes ◽  
Venous Blood ◽  
Coagulation Factors ◽  
Intestinal Wall ◽  
Hemostatic Disorders

SUMMARYLittle is known about the molecular mechanisms whereby the human blood flukeSchistosoma japonicumis able to survive in the host venous blood system. Protease inhibitors are likely released by the parasite enabling it to avoid attack by host proteolytic enzymes and coagulation factors. Interrogation of theS. japonicumgenomic sequence identified a gene,SjKI-1, homologous to that encoding a single domain Kunitz protein (Sjp_0020270) which we expressed in recombinant form inEscherichia coliand purified.SjKI-1is highly transcribed in adult worms and eggs but its expression was very low in cercariae and schistosomula.In situimmunolocalization with anti-SjKI-1 rabbit antibodies showed the protein was present in eggs trapped in the infected mouse intestinal wall. In functional assays, SjKI-1 inhibited trypsin in the picomolar range and chymotrypsin, neutrophil elastase, FXa and plasma kallikrein in the nanomolar range. Furthermore, SjKI-1, at a concentration of 7·5µm, prolonged 2-fold activated partial thromboplastin time of human blood coagulation. We also demonstrate that SjKI-1 has the ability to bind Ca++. We present, therefore, characterization of the first Kunitz protein fromS. japonicumwhich we show has an anti-coagulant properties. In addition, its inhibition of neutrophil elastase indicates SjKI-1 have an anti-inflammatory role. Having anti-thrombotic properties, SjKI-1 may point the way towards novel treatment for hemostatic disorders.

scholarly journals CaM kinase IIδ2-dependent regulation of vascular smooth muscle cell polarization and migration

2008 ◽  
Vol 294 (6) ◽  
pp. C1465-C1475 ◽  
Author(s):  
Melissa Z. Mercure ◽  
Roman Ginnan ◽  
Harold A. Singer
Keyword(s):  
Smooth Muscle ◽  
Cell Migration ◽  
Vascular Smooth Muscle ◽  
Cell Monolayer ◽  
Leading Edge ◽  
Cell Polarization ◽  
Loss Of Function ◽  
Downstream Signaling ◽  
Transient Activation ◽  
And Migration

Previous studies indicate involvement of the multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) in vascular smooth muscle (VSM) cell migration. In the present study, molecular loss-of-function studies were used specifically to assess the role of the predominant CaMKIIδ2 isoform on VSM cell migration using a scratch wound healing assay. Targeted CaMKIIδ2 knockdown using siRNA or inhibition of activity by overexpressing a kinase-negative mutant resulted in attenuation of VSM cell migration. Temporal and spatial assessments of kinase autophosphorylation indicated rapid and transient activation in response to wounding, in addition to a sustained activation in the leading edge of migrating and spreading cells. Furthermore, siRNA-mediated suppression of CaMKIIδ2 resulted in the inhibition of wound-induced Rac activation and Golgi reorganization, and disruption of leading edge morphology, indicating an important function for CaMKIIδ2 in regulating VSM cell polarization. Numerous previous reports link activation of CaMKII to ERK1/2 signaling in VSM. Wound-induced ERK1/2 activation was also found to be dependent on CaMKII; however, ERK activity did not account for effects of CaMKII in regulating Golgi polarization, indicating alternative mechanisms by which CaMKII affects the complex events involved in cell migration. Wounding a VSM cell monolayer results in CaMKIIδ2 activation, which positively regulates VSM cell polarization and downstream signaling, including Rac and ERK1/2 activation, leading to cell migration.

scholarly journals R-Ras Controls Membrane Protrusion and Cell Migration through the Spatial Regulation of Rac and Rho

2005 ◽  
Vol 16 (1) ◽  
pp. 84-96 ◽  
Author(s):  
Michele A. Wozniak ◽  
Lina Kwong ◽  
David Chodniewicz ◽  
Richard L. Klemke ◽  
Patricia J. Keely
Keyword(s):  
Cell Migration ◽  
Molecular Mechanisms ◽  
Leading Edge ◽  
Pi3 Kinase ◽  
Dominant Negative ◽  
Cell Periphery ◽  
Membrane Protrusion ◽  
Spatial Regulation ◽  
Entire Cell ◽  
Migratory Cells

Although it is known that the spatial coordination of Rac and Rho activity is essential for cell migration, the molecular mechanisms regulating these GTPases during migration are unknown. We found that the expression of constitutively activated R-Ras (38V) blocked membrane protrusion and random migration. In contrast, expression of dominant negative R-Ras (41A) enhanced migrational persistence and membrane protrusion. Endogenous R-Ras is necessary for cell migration, as cells that were transfected with siRNA for R-Ras did not migrate. Expression of R-Ras (38V) decreased Rac activity and increased Rho activity around the entire cell periphery, whereas expression of dominant negative R-Ras (41A) showed the converse, suggesting that R-Ras can spatially activate Rho and inactivate Rac. Consistent with this role, endogenous R-Ras localized and was preferentially activated at the leading edge of migratory cells in response to adhesion. The effects of R-Ras on cell migration are mediated by PI3-Kinase, as an effector mutant that uncouples PI3-Kinase binding from R-Ras (38V) rescued migration. From these data, we hypothesize that R-Ras plays a key role in cell migration by locally regulating the switch from Rac to Rho activity after membrane protrusion and adhesion.

scholarly journals Epigenetic Effects Induced by Methamphetamine and Methamphetamine-Dependent Oxidative Stress

2018 ◽  
Vol 2018 ◽  
pp. 1-28 ◽  
Author(s):  
Fiona Limanaqi ◽  
Stefano Gambardella ◽  
Francesca Biagioni ◽  
Carla L. Busceti ◽  
Francesco Fornai
Keyword(s):  
Molecular Mechanisms ◽  
Neuropsychiatric Disorders ◽  
Behavioral Alterations ◽  
Neuronal Phenotype ◽  
Cellular Events ◽  
Epigenetic Effects ◽  
Molecular Events ◽  
Epigenetic Events ◽  
Genetic Modifications ◽  
Altered Gene

Methamphetamine is a widely abused drug, which possesses neurotoxic activity and powerful addictive effects. Understanding methamphetamine toxicity is key beyond the field of drug abuse since it allows getting an insight into the molecular mechanisms which operate in a variety of neuropsychiatric disorders. In fact, key alterations produced by methamphetamine involve dopamine neurotransmission in a way, which is reminiscent of spontaneous neurodegeneration and psychiatric schizophrenia. Thus, understanding the molecular mechanisms operated by methamphetamine represents a wide window to understand both the addicted brain and a variety of neuropsychiatric disorders. This overlapping, which is already present when looking at the molecular and cellular events promoted immediately after methamphetamine intake, becomes impressive when plastic changes induced in the brain of methamphetamine-addicted patients are considered. Thus, the present manuscript is an attempt to encompass all the molecular events starting at the presynaptic dopamine terminals to reach the nucleus of postsynaptic neurons to explain how specific neurotransmitters and signaling cascades produce persistent genetic modifications, which shift neuronal phenotype and induce behavioral alterations. A special emphasis is posed on disclosing those early and delayed molecular events, which translate an altered neurotransmitter function into epigenetic events, which are derived from the translation of postsynaptic noncanonical signaling into altered gene regulation. All epigenetic effects are considered in light of their persistent changes induced in the postsynaptic neurons including sensitization and desensitization, priming, and shift of neuronal phenotype.

scholarly journals Emerging Roles of Redox-Mediated Angiogenesis and Oxidative Stress in Dermatoses

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Dehai Xian ◽  
Jing Song ◽  
Lingyu Yang ◽  
Xia Xiong ◽  
Rui Lai ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endothelial Cells ◽  
Growth Factors ◽  
Molecular Mechanisms ◽  
Capillary Tube ◽  
Proteolytic Enzymes ◽  
Skin Tumor ◽  
Antioxidant Systems ◽  
Antiangiogenic Factors ◽  
And Oxidative Stress

Angiogenesis is the process of new vessel formation, which sprouts from preexisting vessels. This process is highly complex and primarily involves several key steps, including stimulation of endothelial cells by growth factors, degradation of the extracellular matrix by proteolytic enzymes, migration and proliferation of endothelial cells, and capillary tube formation. Currently, it is considered that multiple cytokines play a vital role in this process, which consist of proangiogenic factors (e.g., vascular endothelial growth factor, fibroblast growth factors, and angiopoietins) and antiangiogenic factors (e.g., endostatin, thrombospondin, and angiostatin). Angiogenesis is essential for most physiological events, such as body growth and development, tissue repair, and wound healing. However, uncontrolled neovascularization may contribute to angiogenic disorders. In physiological conditions, the above promoters and inhibitors function in a coordinated way to induce and sustain angiogenesis within a limited period of time. Conversely, the imbalance between proangiogenic and antiangiogenic factors could cause pathological angiogenesis and trigger several diseases. With insights into the molecular mechanisms of angiogenesis, increasing reports have shown that a close relationship exists between angiogenesis and oxidative stress (OS) in both physiological and pathological conditions. OS, an imbalance between prooxidant and antioxidant systems, is a cause and consequence of many vascular complains and serves as one of the biomarkers for these diseases. Furthermore, emerging evidence supports that OS and angiogenesis play vital roles in many dermatoses, such as psoriasis, atopic dermatitis, and skin tumor. This review summarizes recent findings on the role of OS as a trigger of angiogenesis in skin disorders, highlights newly identified mechanisms, and introduces the antiangiogenic and antioxidant therapeutic strategies.

scholarly journals βcap73-ARF6 Interactions Modulate Cell Shape and Motility after Injury In Vitro

2003 ◽  
Vol 14 (10) ◽  
pp. 4155-4161 ◽  
Author(s):  
Kathleen N. Riley ◽  
Angel E. Maldonado ◽  
Patrice Tellier ◽  
Crislyn D'Souza-Schorey ◽  
Ira M. Herman
Keyword(s):  
Western Blot ◽  
Molecular Mechanisms ◽  
Active Form ◽  
Leading Edge ◽  
Dominant Negative ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Capping Protein ◽  
Actin Capping Protein

To understand the role that ARF6 plays in regulating isoactin dynamics and cell motility, we transfected endothelial cells (EC) with HA-tagged ARF6: the wild-type form (WT), a constitutively-active form unable to hydrolyze GTP (Q67L), and two dominant-negative forms, which are either unable to release GDP (T27N) or fail to bind nucleotide (N122I). Motility was assessed by digital imaging microscopy before Western blot analysis, coimmunoprecipitation, or colocalization studies using ARF6, β-actin, or β-actin-binding protein-specific antibodies. EC expressing ARF6-Q67L spread and close in vitro wounds at twice the control rates. EC expressing dominant-negative ARF6 fail to develop a leading edge, are unable to ruffle their membranes (N122I), and possess arborized processes. Colocalization studies reveal that the Q67L and WT ARF6-HA are enriched at the leading edge with β-actin; but T27N and N122I ARF6-HA are localized on endosomes together with the β-actin capping protein, βcap73. Coimmunoprecipitation and Western blot analyses reveal the direct association of ARF6-HA with βcap73, defining a role for ARF6 in signaling cytoskeletal remodeling during motility. Knowledge of the role that ARF6 plays in orchestrating membrane and β-actin dynamics will help to reveal molecular mechanisms regulating actin-based motility during development and disease.

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