scholarly journals Ganglioside Synthesis by Plasma Membrane-Associated Sialyltransferase in Macrophages

2020 ◽  
Vol 21 (3) ◽  
pp. 1063
Author(s):  
Aldo Vilcaes ◽  
Eduardo Garbarino-Pico ◽  
Vanina Torres Demichelis ◽  
Jose Daniotti
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Fluorescent Microscopy ◽  
Physiological Role ◽  
No Synthase ◽  
Raw264.7 Cells ◽  
No Production ◽  
Ganglioside Metabolism ◽  
Gd3 Ganglioside

Gangliosides are constituents of the mammalian cell membranes and participate in the inflammatory response. However, little is known about the presence and enzymatic activity of ganglioside sialyltransferases at the cell surface of macrophages, one of the most important immune cells involved in the innate inflammatory process. In the present study, using biochemical and fluorescent microscopy approaches, we found that endogenous ST8Sia-I is present at the plasma membrane (ecto-ST8Sia-I) of murine macrophage RAW264.7 cells. Moreover, ecto-ST8Sia-I can synthetize GD3 ganglioside at the cell surface in lipopolysaccharide (LPS)-stimulated macrophages even when LPS-stimulated macrophages reduced the total ST8Sia-I expression levels. Besides, cotreatment of LPS with an inhibitor of nitric oxide (NO) synthase recovered the ecto-ST8Sia-I expression, suggesting that NO production is involved in the reduction of ST8Sia-I expression. The diminution of ST8Sia-I expression in LPS-stimulated macrophages correlated with a reduction of GD3 and GM1 gangliosides and with an increment of GD1a. Taken together, the data supports the presence and activity of sialyltransferases at the plasma membrane of RAW264.7 cells. The variations of ecto-ST8Sia-I and ganglioside levels in stimulated macrophages constitutes a promissory pathway to further explore the physiological role of this and others ganglioside metabolism-related enzymes at the cell surface during the immune response.

scholarly journals Saponin-induced release of cell-surface-anchored Thy-1 by serum glycosylphosphatidylinositol-specific phospholipase D

1994 ◽  
Vol 298 (3) ◽  
pp. 661-668 ◽  
Author(s):  
A S Bergman ◽  
S R Carlsson
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Human Serum ◽  
Lipid Bilayer ◽  
Phospholipase D ◽  
Physiological Role ◽  
Highly Active ◽  
T Lymphoma Cells ◽  
T Lymphoma

A glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) was purified from human serum and used for studies on the release of GPI-anchored Thy-1 glycoprotein from mouse T lymphoma cells Y191. Previous studies have shown that whereas GPI-PLD is highly active against detergent-solubilized GPI-anchored proteins, it is normally unable to release GPI-containing proteins anchored in a lipid bilayer. Confirming these findings, the addition of GPI-PLD to intact Y191 cells did not result in cleavage of Thy-1. However, pretreatment of cells with saponin, a cholesterol-sequestering agent, rendered Thy-1 susceptible to hydrolysis. Very little solubilization of GPI-containing Thy-1 occurred under these conditions. From experiments with reconstituted liposomes it was inferred that the effect of saponin on cells was to aid in the presentation of Thy-1 to GPI-PLD. Furthermore, it was concluded that cholesterol-saponin complexes formed in the membrane were not alone responsible for the effect. Rather, additional molecules in the plasma membrane are possibly involved in the presentation of Thy-1 on saponin-treated cells. This finding may have implications for a physiological role of circulating GPI-PLD in the regulation of GPI-anchored proteins on cells.

scholarly journals Purinergic Modulation of Interleukin-1β Release from Microglial Cells Stimulated with Bacterial Endotoxin

1997 ◽  
Vol 185 (3) ◽  
pp. 579-582 ◽  
Author(s):  
Davide Ferrari ◽  
Paola Chiozzi ◽  
Simonetta Falzoni ◽  
Stefania Hanau ◽  
Francesco Di  Virgilio
Keyword(s):  
Plasma Membrane ◽  
P2x7 Receptor ◽  
Purinergic Receptor ◽  
Present Report ◽  
Physiological Role ◽  
Bacterial Endotoxin ◽  
Microglial Cells

Microglial cells express a peculiar plasma membrane receptor for extracellular ATP, named P2Z/P2X7 purinergic receptor, that triggers massive transmembrane ion fluxes and a reversible permeabilization of the plasma membrane to hydrophylic molecules of up to 900 dalton molecule weight and eventual cell death (Di Virgilio, F. 1995. Immunol. Today. 16:524–528). The physiological role of this newly cloned (Surprenant, A., F. Rassendren, E. Kawashima, R.A. North and G. Buell. 1996. Science (Wash. DC). 272:735–737) cytolytic receptor is unknown. In vitro and in vivo activation of the macrophage and microglial cell P2Z/P2X7 receptor by exogenous ATP causes a large and rapid release of mature IL-1β. In the present report we investigated the role of microglial P2Z/P2X7 receptor in IL-1β release triggered by LPS. Our data suggest that LPS-dependent IL-1β release involves activation of this purinergic receptor as it is inhibited by the selective P2Z/P2X7 blocker oxidized ATP and modulated by ATP-hydrolyzing enzymes such as apyrase or hexokinase. Furthermore, microglial cells release ATP when stimulated with LPS. LPS-dependent release of ATP is also observed in monocyte-derived human macrophages. It is suggested that bacterial endotoxin activates an autocrine/paracrine loop that drives ATP-dependent IL-1β secretion.

Immunomodulation by 17β-estradiol in bivalve hemocytes

2006 ◽  
Vol 291 (3) ◽  
pp. R664-R673 ◽  
Author(s):  
Laura Canesi ◽  
Caterina Ciacci ◽  
Lucia Cecilia Lorusso ◽  
Michele Betti ◽  
Tiziana Guarnieri ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Hydrolytic Enzymes ◽  
Physiological Role ◽  
Estrogen Receptor Α ◽  
Nitrite Accumulation ◽  
No Production ◽  
17Β Estradiol

In mammals, estrogens have dose- and cell-type-specific effects on immune cells and may act as pro- and anti-inflammatory stimuli, depending on the setting. In the bivalve mollusc Mytilus, the natural estrogen 17β-estradiol (E2) has been shown to affect neuroimmune functions. We have investigated the immunomodulatory role of E2 in Mytilus hemocytes, the cells responsible for the innate immune response. E2 at 5–25 nM rapidly stimulated phagocytosis and oxyradical production in vitro; higher concentrations of E2 inhibited phagocytosis. E2-induced oxidative burst was prevented by the nitric oxide (NO) synthase inhibitor NG-monomethyl-l-arginine and superoxide dismutase, indicating involvement of NO and O2−; NO production was confirmed by nitrite accumulation. The effects of E2 were prevented by the antiestrogen tamoxifen and by specific kinase inhibitors, indicating a receptor-mediated mechanism and involvement of p38 MAPK and PKC. E2 induced rapid and transient increases in the phosphorylation state of PKC, as well as of a aCREB-like (cAMP responsive element binding protein) transcription factor, as indicated by Western blot analysis with specific anti-phospho-antibodies. Localization of estrogen receptor-α- and -β-like proteins in hemocytes was investigated by immunofluorescence confocal microscopy. The effects of E2 on immune function were also investigated in vivo at 6 and 24 h in hemocytes of E2-injected mussels. E2 significantly affected hemocyte lysosomal membrane stability, phagocytosis, and extracellular release of hydrolytic enzymes: lower concentrations of E2 resulted in immunostimulation, and higher concentrations were inhibitory. Our data indicate that the physiological role of E2 in immunomodulation is conserved from invertebrates to mammals.

Compartmentalization of protein traffic in insulin-sensitive cells

1996 ◽  
Vol 271 (1) ◽  
pp. E1-E14 ◽  
Author(s):  
K. V. Kandror ◽  
P. F. Pilch
Keyword(s):  
Cell Surface ◽  
Physiological Role ◽  
Fat Cells ◽  
Protein Traffic ◽  
Glut 1 ◽  
Glut 4 ◽  
Factor Ii ◽  
Nutritional Needs

Insulin-sensitive cells, adipocytes and myocytes, translocate a number of intracellular proteins to the cell surface in response to insulin. Among these proteins are glucose transporters 1 and 4 (GLUT-1 and GLUT-4, respectively), receptors for insulin-like growth factor II (IGF-II)/mannose 6-phosphate (Man-6-P) and transferrin, the aminopeptidase gp 160, caveolin, and a few others. In the case of insulin-activated glucose transport, this translocation has been proven to be the major, if not the only regulatory mechanism of this process. It seems likely that the cell surface recruitment of the IGF-II/Man-6-P and transferrin receptors also serves the nutritional needs of cells, whereas the physiological role of the aminopeptidase gp160 remains uncertain. Analysis of the compartmentalization and trafficking pathways of translocatable proteins in fat cells identified more than one population of recycling vesicles, although all have identical sedimentation coefficients and buoyant densities in vitro. GLUT-4-containing vesicles include essentially all the intracellular GLUT-4, gp160, and the acutely recycling populations of receptors for IGF-II/Man-6-P and transferrin. Besides these proteins, which can be considered as vesicle “cargo”, GLUT-4-containing vesicles have other components, like secretory carrier-associated membrane proteins (SCAMP), Rab(s), and vesicle-associated membrane protein (VAMP)/cellubrevin, which are ubiquitous to secretory vesicles and granules from different tissues. GLUT-1 and caveolin are excluded from GLUT-4-containing vesicles and form different vesicular populations of unknown polypeptide composition. In skeletal muscle, two independent populations of GLUT-4-containing vesicles are found, insulin sensitive and exercise sensitive, which explains the additive effect of insulin and exercise on glucose uptake. Both vesicular populations are similar to each other and to analogous vesicles in fat cells.

scholarly journals Phospholipase D2 Mediates Acute Aldosterone Secretion in Response to Angiotensin II in Adrenal Glomerulosa Cells

Endocrinology ◽  
2010 ◽  
Vol 151 (5) ◽  
pp. 2162-2170 ◽  
Author(s):  
Haixia Qin ◽  
Michael A. Frohman ◽  
Wendy B. Bollag
Keyword(s):  
Plasma Membrane ◽  
Angiotensin Ii ◽  
Cell Surface ◽  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Cell Interior ◽  
Aldosterone Secretion ◽  
Phospholipase D2 ◽  
Glomerulosa Cells

In primary bovine adrenal glomerulosa cells, the signaling enzyme phospholipase D (PLD) is suggested to mediate priming, the enhancement of aldosterone secretion after pretreatment with and removal of angiotensin II (AngII), via the formation of persistently elevated diacylglycerol (DAG). To further explore PLD’s role in priming, glomerulosa cells were pretreated with an exogenous bacterial PLD. Using this approach, phosphatidic acid (PA) is generated on the outer, rather than the inner, leaflet of the plasma membrane. Although PA is not readily internalized, the PA is nonetheless rapidly hydrolyzed by cell-surface PA phosphatases to DAG, which efficiently flips to the inner leaflet and accesses the cell interior. Pretreatment with bacterial PLD resulted in priming upon subsequent AngII exposure, supporting a role of DAG in this process, because the increase in DAG persisted after exogenous PLD removal. To determine the PLD isoform mediating aldosterone secretion, and presumably priming, primary glomerulosa cells were infected with adenoviruses expressing GFP, PLD1, PLD2, or lipase-inactive mutants. Overexpressed PLD2 increased aldosterone secretion by approximately 3-fold over the GFP-infected control under basal conditions, with a significant enhancement to about 16-fold over the basal value upon AngII stimulation. PLD activity was also increased basally and upon stimulation with AngII. In contrast, PLD1 overexpression had little effect on aldosterone secretion, despite the fact that PLD activity was enhanced. In both cases, the lipase-inactive PLD mutants showed essentially no effect on PLD activity or aldosterone secretion. Our results suggest that PLD2 is the isoform that mediates aldosterone secretion and likely priming.

Role of airway nitric oxide on the regulation of pulmonary circulation by carbon dioxide

2001 ◽  
Vol 91 (3) ◽  
pp. 1121-1130 ◽  
Author(s):  
Yasushi Yamamoto ◽  
Hitoshi Nakano ◽  
Hiroshi Ide ◽  
Toshiyuki Ogasa ◽  
Toru Takahashi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
No Synthase ◽  
No Production ◽  
Pulmonary Vasoconstriction ◽  
Exhaled No ◽  
Progressive Hypoxia ◽  
Pulmonary Arterial

The effects of hypercapnia (CO2) confined to either the alveolar space or the intravascular perfusate on exhaled nitric oxide (NO), perfusate NO metabolites (NOx), and pulmonary arterial pressure (Ppa) were examined during normoxia and progressive 20-min hypoxia in isolated blood- and buffer-perfused rabbit lungs. In blood-perfused lungs, when alveolar CO2concentration was increased from 0 to 12%, exhaled NO decreased, whereas Ppa increased. Increments of intravascular CO2levels increased Ppa without changes in exhaled NO. In buffer-perfused lungs, alveolar CO2 increased Ppa with reductions in both exhaled NO from 93.8 to 61.7 (SE) nl/min ( P < 0.01) and perfusate NOx from 4.8 to 1.8 nmol/min ( P < 0.01). In contrast, intravascular CO2 did not affect either exhaled NO or Ppa despite a tendency for perfusate NOx to decline. Progressive hypoxia elevated Ppa by 28% from baseline with a reduction in exhaled NO during normocapnia. Alveolar hypercapnia enhanced hypoxic Ppa response up to 50% with a further decline in exhaled NO. Hypercapnia did not alter the apparent K m for O2, whereas it significantly decreased the V max from 66.7 to 55.6 nl/min. These results suggest that alveolar CO2 inhibits epithelial NO synthase activity noncompetitively and that the suppressed NO production by hypercapnia augments hypoxic pulmonary vasoconstriction, resulting in improved ventilation-perfusion matching.

scholarly journals Neisseria gonorrhoeae Porin P1.B Induces Endosome Exocytosis and a Redistribution of Lamp1 to the Plasma Membrane

2002 ◽  
Vol 70 (11) ◽  
pp. 5965-5971 ◽  
Author(s):  
Patricia Ayala ◽  
Brandi Vasquez ◽  
Lee Wetzler ◽  
Magdalene So
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Neisseria Gonorrhoeae ◽  
Bacterial Infection ◽  
Immunoglobulin A ◽  
Late Endosomes ◽  
A Cell ◽  
Iga Protease

ABSTRACT The immunoglobulin A (IgA) protease secreted by pathogenic Neisseria spp. cleaves Lamp1, thereby altering lysosomes in a cell and promoting bacterial intracellular survival. We sought to determine how the IgA protease gains access to cellular Lamp1 in order to better understand the role of this cleavage event in bacterial infection. In a previous report, we demonstrated that the pilus-induced Ca2+ transient triggers lysosome exocytosis in human epithelial cells. This, in turn, increases the level of Lamp1 at the plasma membrane, where it can be cleaved by IgA protease. Here, we show that porin also induces a Ca2+ flux in epithelial cells. This transient is similar in nature to that observed in phagocytes exposed to porin. In contrast to the pilus-induced Ca2+ transient, the porin-induced event does not trigger lysosome exocytosis. Instead, it stimulates exocytosis of early and late endosomes and increases Lamp1 on the cell surface. These results indicate that Neisseria pili and porin perturb Lamp1 trafficking in epithelial cells by triggering separate and distinct Ca2+-dependent exocytic events, bringing Lamp1 to the cell surface, where it can be cleaved by IgA protease.

scholarly journals CYRI-A regulates macropinocytic cup maturation and mediates integrin uptake, limiting invasive migration

2020 ◽  
Author(s):  
Anh Hoang Le ◽  
Tamas Yelland ◽  
Nikki Paul ◽  
Loic Fort ◽  
Savvas Nikolaou ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Ewing Sarcoma ◽  
Negative Regulator ◽  
Cell Surface Receptor ◽  
Actin Dynamics ◽  
Surface Receptor ◽  
Sarcoma Cells ◽  
Wave Complex

The Scar/WAVE complex is the major driver of actin nucleation at the plasma membrane, resulting in lamellipodia and membrane ruffles. While lamellipodia aid migration, membrane ruffles can generate macropinosomes - cup-like structures - important for nutrient uptake and regulation of cell surface receptor levels. How macropinosomes are formed and the role of the actin machinery in their formation and resolution is still not well understood. Mammalian CYRI-B is a recently described negative regulator of the Scar/WAVE complex by RAC1 sequestration, but its other paralogue, CYRI-A has not been characterised. Here we implicate CYRI-A as a key regulator of macropinocytosis maturation and integrin internalisation from the cell surface. We find that CYRI-A is recruited to nascent macropinosomes in a transient but distinct burst, downstream of PIP3-mediated RAC1 activation to regulate actin polymerisation. CYRI-A precedes RAB5A recruitment to engulfed macropinocytic cups and departs as RAB5A is recruited, consistent with a role for CYRI-A as a local suppressor of actin dynamics, enabling the resolution of the macropinocytic cup. The suppression of integrin a5b1 uptake caused by the co-depletion of CYRI-A and B in Ewing sarcoma cells, leads to an enhancement of surface integrin levels and enhanced invasion and anchorage-independent growth in 3D. Thus CYRI-A is a dynamic regulator of integrin uptake via macropinocytosis, functioning together with CYRI-B to regulate integrin homeostasis on the cell surface.

scholarly journals Microdomain protein Nce102 is a local sensor of plasma membrane sphingolipid balance

2021 ◽  
Author(s):  
Jakub Zahumensky ◽  
Caroline Mota Fernandes ◽  
Petra Vesela ◽  
Maurizio Del Poeta ◽  
James Bernard Konopka ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Physiological Role ◽  
Building Blocks ◽  
Mass Spectrometry Analysis ◽  
Spectrometry Analysis ◽  
Signalling Molecules ◽  
Human Fungal Pathogen ◽  
Sphingolipid Biosynthesis ◽  
Complex Sphingolipids

Sphingolipids are essential building blocks of eukaryotic membranes and important signalling molecules, tightly regulated in response to environmental and physiological inputs. Mechanism of sphingolipid level perception at the plasma membrane remains unclear. In Saccharomyces cerevisiae, Nce102 protein has been proposed to function as sphingolipid sensor as it changes its plasma membrane distribution in response to sphingolipid biosynthesis inhibition. We show that Nce102 redistributes specifically in regions of increased sphingolipid demand, e.g., membranes of nascent buds. Furthermore, we report that production of Nce102 increases following sphingolipid biosynthesis inhibition and Nce102 is internalized when excess sphingolipid precursors are supplied. This suggests that the total amount of Nce102 in the plasma membrane is a measure of the current need for sphingolipids, whereas its local distribution marks sites of high sphingolipid demand. Physiological role of Nce102 in regulation of sphingolipid synthesis is demonstrated by mass spectrometry analysis showing reduced levels of complex sphingolipids and long-chain bases in nce102? deletion mutant. Nce102 behaves analogously in human fungal pathogen Candida albicans, suggesting a conserved principle of local sphingolipid control across species.

scholarly journals Salt-induced hypertension in Dahl salt-resistant and salt-sensitive rats with NOS II inhibition

1999 ◽  
Vol 277 (2) ◽  
pp. H732-H739 ◽  
Author(s):  
M. Audrey Rudd ◽  
Maria Trolliet ◽  
Susan Hope ◽  
Anne Ward Scribner ◽  
Geraldine Daumerie ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Function ◽  
No Synthase ◽  
No Production ◽  
Induced Hypertension ◽  
Blood Pressures ◽  
Diameter Change ◽  
Inducible Nos ◽  
Tail Cuff

Although recent evidence suggests that reduced nitric oxide (NO) production may be involved in salt-induced hypertension, the specific NO synthase (NOS) responsible for the conveyance of salt sensitivity remains unknown. To determine the role of inducible NOS (NOS II) in salt-induced hypertension, we treated Dahl salt-resistant (DR) rats with the selective NOS II inhibitor 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) for 12 days. Tail-cuff systolic blood pressures rose 29 ± 6 and 42 ± 8 mmHg in DR rats given 150 and 300 nmol AMT/h, respectively ( P < 0.01, 2-way ANOVA) after 7 days of 8% NaCl diet. We observed similar results with two other potent selective NOS II inhibitors, S-ethylisourea (EIT) and N-[3-(aminomethyl)benzyl]acetamidine hydrochloride (1400W). Additionally, AMT effects were independent of alterations in endothelial function as assessed by diameter change of mesenteric arterioles in response to methacholine using videomicroscopy. We, therefore, conclude from these data that NOS II is important in salt-induced hypertension.

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