scholarly journals Mammalian Septins Are Required for Phagosome Formation

2008 ◽  
Vol 19 (4) ◽  
pp. 1717-1726 ◽  
Author(s):  
Yi-Wei Huang ◽  
Ming Yan ◽  
Richard F. Collins ◽  
Jessica E. DiCiccio ◽  
Sergio Grinstein ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Transient Expression ◽  
Time Course ◽  
Membrane Dynamics ◽  
Human Neutrophils ◽  
Mouse Macrophage ◽  
Macrophage Cell ◽  
Cellular Processes ◽  
Latex Beads

Septins are members of a highly conserved family of filamentous proteins that are required in many organisms for the completion of cytokinesis. In addition, septins have been implicated in a number of important cellular processes and have been suggested to have roles in regulating membrane traffic. Given the proposed role of septins in cell membrane dynamics, we investigated the function of septins during FcγR-mediated phagocytosis. We show that several septins are expressed in RAW264.7 and J774 mouse macrophage cell lines and that SEPT2 and SEPT11 are colocalized with submembranous actin-rich structures during the early stages of FcγR-mediated phagocytosis. In addition, SEPT2 accumulation is seen in primary human neutrophils and in nonprofessional phagocytes. The time course of septin accumulation mirrors actin accumulation and is inhibited by latrunculin and genistein, but not other inhibitors of phagocytosis. Inhibition of septin function by transient expression of the BD3 domain of BORG3, known to cause septin aggregation, or depletion of SEPT2 or SEPT11 by RNAi, significantly inhibited FcγR-mediated phagocytosis of IgG-coated latex beads. Interestingly, this occurred without affecting the accumulation of actin or the actin-associated protein coronin-1. These observations show that, although not necessary for actin recruitment, septins are required for efficient FcγR-mediated phagocytosis.

Opposing effects of PKCα and PKCε on basolateral membrane dynamics in intestinal epithelia

2002 ◽  
Vol 283 (5) ◽  
pp. C1548-C1556 ◽  
Author(s):  
Jaekyung Cecilia Song ◽  
Patangi K. Rangachari ◽  
Jeffrey B. Matthews
Keyword(s):  
Time Course ◽  
Basolateral Membrane ◽  
Membrane Dynamics ◽  
T84 Cells ◽  
Intestinal Epithelia ◽  
Early Activation ◽  
Pkc Isoforms ◽  
Opposing Effects ◽  
Stimulation Of

PKC is a critical effector of plasma membrane dynamics, yet the mechanism and isoform-specific role of PKC are poorly understood. We recently showed that the phorbol ester PMA (100 nM) induces prompt activation of the novel isoform PKCε followed by late activation of the conventional isoform PKCα in T84 intestinal epithelia. PMA also elicited biphasic effects on endocytosis, characterized by an initial stimulatory phase followed by an inhibitory phase. Activation of PKCε was shown to be responsible for stimulation of basolateral endocytosis, but the role of PKCα was not defined. Here, we used detailed time-course analysis as well as selective activators and inhibitors of PKC isoforms to infer the action of PKCα on basolateral endocytosis. Inhibition of PKCα by the selective conventional PKC inhibitor Gö-6976 (5 μM) completely blocked the late inhibitory phase and markedly prolonged the stimulatory phase of endocytosis measured by FITC-dextran uptake. The PKCε-selective agonist carbachol (100 μM) induced prolonged stimulation of endocytosis devoid of an inhibitory phase. Actin disassembly caused by PMA was completely blocked by Gö-6850 but not by Gö-6976, implicating PKCε as the key isoform responsible for actin disruption. The Ca2+ agonist thapsigargin (5 μM) induced early activation of PKCα when added simultaneously with PMA. This early activation of PKCα blocked the ability of PMA to remodel basolateral F-actin and abolished the stimulatory phase of basolateral endocytosis. Activation of PKCα stabilizes F-actin and thereby opposes the effect of PKCε on membrane remodeling in T84 cells.

scholarly journals The Potential of Telomeric G-Quadruplexes Containing Modified Oligoguanosine Overhangs in Activation of Bacterial Phagocytosis and Leukotriene Synthesis in Human Neutrophils

Biomolecules ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 249 ◽  
Author(s):  
Ekaterina A. Golenkina ◽  
Galina M. Viryasova ◽  
Nina G. Dolinnaya ◽  
Valeria A. Bannikova ◽  
Tatjana V. Gaponova ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Viral Infections ◽  
Uv Spectroscopy ◽  
Human Neutrophils ◽  
First Line ◽  
Cellular Effects ◽  
Cellular Processes ◽  
G Quadruplex ◽  
New Generation

Human neutrophils are the first line of defense against bacterial and viral infections. They eliminate pathogens through phagocytosis, which activate the 5-lipoxygenase (5-LOX) pathway resulting in synthesis of leukotrienes. Using HPLC analysis, flow cytometry, and other biochemical methods, we studied the effect of synthetic oligodeoxyribonucleotides (ODNs) able to fold into G-quadruplex structures on the main functions of neutrophils. Designed ODNs contained four human telomere TTAGGG repeats (G4) including those with phosphorothioate oligoguanosines attached to the end(s) of G-quadruplex core. Just modified analogues of G4 was shown to more actively than parent ODN penetrate into cells, improve phagocytosis of Salmonella typhimurium bacteria, affect 5-LOX activation, the cytosol calcium ion level, and the oxidative status of neutrophils. As evident from CD and UV spectroscopy data, the presence of oligoguanosines flanking G4 sequence leads to dramatic changes in G-quadruplex topology. While G4 folds into a single antiparallel structure, two main folded forms have been identified in solutions of modified ODNs: antiparallel and dominant, more stable parallel. Thus, both the secondary structure of ODNs and their ability to penetrate into the cytoplasm of cells are important for the activation of neutrophil cellular effects. Our results offer new clues for understanding the role of G-quadruplex ligands in regulation of integral cellular processes and for creating the antimicrobial agents of a new generation.

scholarly journals The interrelationship between phagocytosis, autophagy and formation of neutrophil extracellular traps following infection of human neutrophils by Streptococcus pneumoniae

2017 ◽  
Vol 23 (5) ◽  
pp. 413-423 ◽  
Author(s):  
Ihsan Ullah ◽  
Neil D Ritchie ◽  
Tom J Evans
Keyword(s):  
Streptococcus Pneumoniae ◽  
Pneumococcal Infection ◽  
Neutrophil Extracellular Traps ◽  
Inhibitory Effect ◽  
Human Neutrophils ◽  
Phosphatidylinositol 3 Kinase ◽  
Cellular Processes ◽  
Extracellular Traps ◽  
Potent Inhibitory Effect

Neutrophils play an important role in the innate immune response to infection with Streptococcus pneumoniae, the pneumococcus. Pneumococci are phagocytosed by neutrophils and undergo killing after ingestion. Other cellular processes may also be induced, including autophagy and the formation of neutrophil extracellular traps (NETs), which may play a role in bacterial eradication. We set out to determine how these different processes interacted following pneumococcal infection of neutrophils, and the role of the major pneumococcal toxin pneumolysin in these various pathways. We found that pneumococci induced autophagy in neutrophils in a type III phosphatidylinositol-3 kinase dependent fashion that also required the autophagy gene Atg5. Pneumolysin did not affect this process. Phagocytosis was inhibited by pneumolysin but enhanced by autophagy, while killing was accelerated by pneumolysin but inhibited by autophagy. Pneumococci induced extensive NET formation in neutrophils that was not influenced by pneumolysin but was critically dependent on autophagy. While pneumolysin did not affect NET formation, it had a potent inhibitory effect on bacterial trapping within NETs. These findings show a complex interaction between phagocytosis, killing, autophagy and NET formation in neutrophils following pneumococcal infection that contribute to host defence against this pathogen.

scholarly journals C-Glucosylation as a tool for the prevention of PAINS-induced membrane dipole potential alterations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ana Marta de Matos ◽  
Maria Teresa Blázquez-Sánchez ◽  
Carla Sousa ◽  
Maria Conceição Oliveira ◽  
Rodrigo F. M. de Almeida ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Transmembrane Protein ◽  
New Technology ◽  
Dipole Potential ◽  
Membrane Dipole Potential ◽  
Cellular Processes ◽  
Established Relationship ◽  
And Function ◽  
Bioactive Natural Product

AbstractThe concept of Pan-Assay Interference Compounds (PAINS) is regarded as a threat to the recognition of the broad bioactivity of natural products. Based on the established relationship between altered membrane dipole potential and transmembrane protein conformation and function, we investigate here polyphenols' ability to induce changes in cell membrane dipole potential. Ultimately, we are interested in finding a tool to prevent polyphenol PAINS-type behavior and produce compounds less prone to untargeted and promiscuous interactions with the cell membrane. Di-8-ANEPPS fluorescence ratiometric measurements suggest that planar lipophilic polyphenols—phloretin, genistein and resveratrol—act by decreasing membrane dipole potential, especially in cholesterol-rich domains such as lipid rafts, which play a role in important cellular processes. These results provide a mechanism for their labelling as PAINS through their ability to disrupt cell membrane homeostasis. Aiming to explore the role of C-glucosylation in PAINS membrane-interfering behavior, we disclose herein the first synthesis of 4-glucosylresveratrol, starting from 5-hydroxymethylbenzene-1,3-diol, via C-glucosylation, oxidation and Horner-Wadsworth-Emmons olefination, and resynthesize phloretin and genistein C-glucosides. We show that C-glucosylation generates compounds which are no longer able to modify membrane dipole potential. Therefore, it can be devised as a strategy to generate bioactive natural product derivatives that no longer act as membrane dipole potential modifiers. Our results offer a new technology towards rescuing bioactive polyphenols from their PAINS danger label through C–C ligation of sugars.

scholarly journals The Role of Phosphatidylinositol Phosphate Kinases during Viral Infection

Viruses ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1124
Author(s):  
Anne Beziau ◽  
Denys Brand ◽  
Eric Piver
Keyword(s):  
Steady State ◽  
Viral Replication ◽  
Small Proportion ◽  
Membrane Dynamics ◽  
Concerted Action ◽  
Cellular Processes ◽  
Phosphatidylinositol Phosphate ◽  
Steady State Levels ◽  
Regulatory Functions

Phosphoinositides account for only a small proportion of cellular phospholipids, but have long been known to play an important role in diverse cellular processes, such as cell signaling, the establishment of organelle identity, and the regulation of cytoskeleton and membrane dynamics. As expected, given their pleiotropic regulatory functions, they have key functions in viral replication. The spatial restriction and steady-state levels of each phosphoinositide depend primarily on the concerted action of specific phosphoinositide kinases and phosphatases. This review focuses on a number of remarkable examples of viral strategies involving phosphoinositide kinases to ensure effective viral replication.

scholarly journals Early and Late Processes Driving NET Formation, and the Autocrine/Paracrine Role of Endogenous RAGE Ligands

2021 ◽  
Vol 12 ◽  
Author(s):  
Olga Tatsiy ◽  
Vanessa de Carvalho Oliveira ◽  
Hugo Tshivuadi Mosha ◽  
Patrick P. McDonald
Keyword(s):  
Signaling Pathways ◽  
Neutrophil Extracellular Trap ◽  
Net Generation ◽  
Human Neutrophils ◽  
Chromatin Decondensation ◽  
Cellular Processes ◽  
Activated Neutrophils ◽  
Arginine Residues ◽  
Neutrophil Response

Neutrophil extracellular trap (NET) formation has emerged as an important response against various pathogens; it also plays a role in chronic inflammation, autoimmunity, and cancer. Despite a growing understanding of the mechanisms underlying NET formation, much remains to be elucidated. We previously showed that in human neutrophils activated with different classes of physiological stimuli, NET formation features both early and late events that are controlled by discrete signaling pathways. However, the nature of these events has remained elusive. We now report that PAD4 inhibition only affects the early phase of NET generation, as do distinct signaling intermediates (TAK1, MEK, p38 MAPK). Accordingly, the inducible citrullination of residue R2 on histone H3 is an early neutrophil response that is regulated by these kinases; other arginine residues on histones H3 and H4 do not seem to be citrullinated. Conversely, elastase blockade did not affect NET formation by several physiological stimuli, though it did so in PMA-activated cells. Among belated events in NET formation, we found that chromatin decondensation is impaired by the inhibition of signaling pathways controlling both early and late stages of the phenomenon. In addition to chromatin decondensation, other late processes were uncovered. For instance, unstimulated neutrophils can condition themselves to be poised for rapid NET induction. Similarly, activated neutrophils release endogenous proteic factors that promote and largely mediate NET generation. Several such factors are known RAGE ligands and accordingly, RAGE inbibition largely prevents both NET formation and the conditioning of neutrophils to rapidly generate NETs upon stimulation. Our data shed new light on the cellular processes underlying NET formation, and unveil unsuspected facets of the phenomenon that could serve as therapeutic targets. In view of the involvement of NETs in both homeostasis and several pathologies, our findings are of broad relevance.

The Role of BAR Domain Proteins in the Regulation of Membrane Dynamics

Acta Naturae ◽  
2016 ◽  
Vol 8 (4) ◽  
pp. 60-69 ◽  
Author(s):  
T. B. Stanishneva-Konovalova ◽  
N. I Derkacheva ◽  
S. V. Polevova ◽  
O. S. Sokolova
Keyword(s):  
Membrane Dynamics ◽  
Actin Dynamics ◽  
Membrane Remodeling ◽  
Bar Domain ◽  
Cellular Processes ◽  
Functional Differences ◽  
Bar Domain Proteins ◽  
Domain Protein ◽  
Bar Domains

Many cellular processes are associated with membrane remodeling. The BAR domain protein family plays a key role in the formation and detection of local membrane curvatures and in attracting other proteins, including the regulators of actin dynamics. Based on their structural and phylogenetic properties, BAR domains are divided into several groups which affect membrane in various ways and perform different functions in cells. However, recent studies have uncovered evidence of functional differences even within the same group. This review discusses the principles underlying the interactions of different groups of BAR domains, and their individual representatives, with membranes.

Colony-stimulating factor-1 induces rapid behavioural responses in the mouse macrophage cell line, BAC1.2F5

1989 ◽  
Vol 93 (3) ◽  
pp. 447-456 ◽  
Author(s):  
C.A. Boocock ◽  
G.E. Jones ◽  
E.R. Stanley ◽  
J.W. Pollard
Keyword(s):  
Cell Line ◽  
Time Course ◽  
Cell Spreading ◽  
Mouse Macrophage ◽  
Colony Stimulating Factor ◽  
Macrophage Cell Line ◽  
Macrophage Cell ◽  
Stimulating Factor ◽  
Mouse Macrophage Cell Line ◽  
Stimulation Of

The cloned, SV40-immortalized mouse macrophage cell line, BAC1.2F5, resembles primary macrophages in its dependence on colony-stimulating factor-1 (CSF-1) for both viability and proliferation. Re-addition of CSF-1 stimulates rapid, transient behavioural changes in starved cells, which are rounded, with diffusely organized F-actin and few intracellular vesicles. Within 1 min, cells begin to spread, forming prominent, F-actin-rich ruffles. Small vesicles (0.5-1.0 microns), formed throughout extending lamellar processes, move centripetally and, after 3–5 min, fuse to form larger vesicles (2.0-4.0 microns), clustered around the nucleus. Immunofluorescence demonstrates that CSF-1, bound to cell-surface receptors, is internalized via these vesicles. Cell spreading and ruffling peak about 5 min after restimulation. Interference reflection microscopy indicates no corresponding change in the mode of cell-substratum adhesion: a single area of close adhesion underlies most of the cell and simply broadens during spreading. Analysis of cell aggregation kinetics shows no effect of CSF-1 on intercellular adhesiveness. Measurement of cell areas after starvation and restimulation demonstrates quantitatively the time-course and concentration-dependence of cell spreading. Mean area doubles within 5 min and, after a transient peak, decreases within 30 min to the value measured before starvation. This time-course corresponds to that of CSF-1 internalization and of the phosphorylation and subsequent degradation of CSF-1 receptors. The concentration-dependence of the spreading response resembles that of CSF-1-dependent survival and proliferation. The minimum detectable stimulation of spreading occurs at the concentration (22 pM) that supports survival without proliferation. Increasing stimulation of spreading occurs over the range of concentrations that elicit increasing proliferation.

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