scholarly journals Involvement of thiol transferase- and thioredoxin-dependent systems in the protection of ‘essential’ thiol groups of ornithine decarboxylase

1989 ◽  
Vol 259 (1) ◽  
pp. 111-115 ◽  
Author(s):  
F Flamigni ◽  
S Marmiroli ◽  
C M Caldarera ◽  
C Guarnieri
Keyword(s):  
Ornithine Decarboxylase ◽  
Reductase Activity ◽  
Physiological Role ◽  
Thioredoxin Reductase ◽  
Thiol Group ◽  
Transferase Activity ◽  
Strong Inhibitor ◽  
Activity Factor

Ornithine decarboxylase (ODC), an enzyme with ‘essential’ thiol group(s), may be inactivated in vitro by removal of thiol reducing agents and re-activated by soluble factors from rat liver in the presence of NADPH or GSH. The NADPH- and GSH-dependent reducing systems were separated and resolved into three components, called factors A, B1 and B2, by chromatographic techniques. Factor B1 (Mr 12,000) could reactivate ODC in the presence of GSH and co-purified with thiol transferase activity. Factor B2 (Mr 12,000) and factor A (Mr approx. 110,000) were both needed to re-activate ODC in the presence of NADPH, and co-purified with thioredoxin and thioredoxin reductase activity respectively. In an attempt to investigate the physiological role of the ‘essential’ thiol group(s) of ODC, erythroleukaemia cells were incubated with NN-bis-(2-chloroethyl)-N'-nitrosourea, t-butyl hydroperoxide and vinblastine, which are known to increase the cellular GSSG/GSH ratio, azelaic acid, an inhibitor of thioredoxin reductase, and sodium arsenite, a strong inhibitor of the ODC-re-activating factors. All these compounds were able to decrease significantly the ODC activity induced in these cells. These results suggest that the thiol transferase- and thioredoxin-dependent systems may be physiologically relevant in maintaining ODC in the active, reduced, state.

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.

scholarly journals Leptin down-regulates KCC2 activity and controls chloride homeostasis in the neonatal rat hippocampus

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Camille Dumon ◽  
Yasmine Belaidouni ◽  
Diabe Diabira ◽  
Suzanne M. Appleyard ◽  
Gary A. Wayman ◽  
...  
Keyword(s):  
Neurological Disorders ◽  
Physiological Role ◽  
Rat Hippocampus ◽  
Neonatal Rat ◽  
Chloride Homeostasis ◽  
Hypothalamic Nuclei ◽  
Hippocampal Networks ◽  
Developing Rat

Abstract The canonical physiological role of leptin is to regulate hunger and satiety acting on specific hypothalamic nuclei. Beyond this key metabolic function; leptin also regulates many aspects of development and functioning of neuronal hippocampal networks throughout life. Here we show that leptin controls chloride homeostasis in the developing rat hippocampus in vitro. The effect of leptin relies on the down-regulation of the potassium/chloride extruder KCC2 activity and is present during a restricted period of postnatal development. This study confirms and extends the role of leptin in the ontogenesis of functional GABAergic inhibition and helps understanding how abnormal levels of leptin may contribute to neurological disorders.

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 Laminin-alpha6beta1 integrin interaction enhances survival and proliferation and modulates steroidogenesis of ovine granulosa cells

2002 ◽  
Vol 172 (1) ◽  
pp. 45-59 ◽  
Author(s):  
F Le Bellego ◽  
C Pisselet ◽  
C Huet ◽  
P Monget ◽  
D Monniaux
Keyword(s):  
Estrous Cycle ◽  
Granulosa Cells ◽  
Physiological Role ◽  
Follicular Development ◽  
Antral Follicles ◽  
Final Development ◽  
Beta 1 Integrin ◽  
Arginine Glycine Aspartic Acid

This study aimed to determine the physiological role of laminin (LN) and its receptor, alpha(6)beta(1) integrin, in controlling the functions of granulosa cells (GC) during follicular development in sheep ovary. Immunohistochemistry experiments showed the presence of increasing levels of LN (P<0.0001), and high levels of mature alpha(6)beta(1) integrin in GC layers of healthy antral follicles during the follicular and the preovulatory phases of the estrous cycle. In vitro, the addition of a function-blocking antibody raised against alpha(6) subunit (anti-alpha(6) IgG) to the medium of ovine GC cultured on LN impaired cell spreading (P<0.0001), decreased the proliferation rate (P<0.05) and increased the apoptosis rate (P<0.05). Furthermore, addition of anti-alpha(6) IgG enhanced estradiol (E2) secretion by GC in the presence or absence of follicle-stimulating hormone (FSH), luteinizing hormone or insulin-like growth factor-I in culture medium (P<0.0001), and inhibited progesterone (P4) secretion in basal conditions or in the presence of low (0.5 ng/ml) FSH concentrations only (P<0.0001). The anti-alpha(6) IgG effect was specific to an interaction of LN with alpha(6)beta(1) integrin since it was ineffective on GC cultured on heat-denatured LN, RGD (arginine-glycine-aspartic acid) peptides and non-coated substratum. Hence, this study established that alpha(6)beta(1) integrin 1) was expressed in GC of antral follicles, 2) mediated the actions of LN on survival, proliferation and steroidogenesis of GC, and 3) was able to dramatically modulate P4 and E2 secretion by GC in vitro. It is suggested that during the follicular and the preovulatory phases of the estrous cycle, the increasing levels of LN in GC of large antral follicles might support their final development to ovulation.

scholarly journals 2-Hydroxy-(4-methylseleno)butanoic Acid Is Used by Intestinal Caco-2 Cells as a Source of Selenium and Protects against Oxidative Stress

2019 ◽  
Vol 149 (12) ◽  
pp. 2191-2198
Author(s):  
Joan Campo-Sabariz ◽  
David Moral-Anter ◽  
M Teresa Brufau ◽  
Mickael Briens ◽  
Eric Pinloche ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
In Vitro Model ◽  
Thioredoxin Reductase ◽  
Protein Carbonyl ◽  
Butanoic Acid ◽  
H2o2 Treatment ◽  
Vitro Model ◽  
Gpx Activity

ABSTRACT Background Selenium (Se) participates in different functions in humans and other animals through its incorporation into selenoproteins as selenocysteine. Inadequate dietary Se is considered a risk factor for several chronic diseases associated with oxidative stress. Objective The role of 2-hydroxy-(4-methylseleno)butanoic acid (HMSeBA), an organic form of Se used in animal nutrition, in supporting selenoprotein synthesis and protecting against oxidative stress was investigated in an in vitro model of intestinal Caco-2 cells. Methods Glutathione peroxidase (GPX) and thioredoxin reductase (TXNRD) activities, selenoprotein P1 protein (SELENOP) and gene (SELENOP) expression, and GPX1 and GPX2 gene expression were studied in Se-deprived (FBS removal) and further HMSeBA-supplemented (0.1–625 μM, 72 h) cultures. The effect of HMSeBA supplementation (12.5 and 625 μM, 24 h) on oxidative stress induced by H2O2 (1 mM) was evaluated by the production of reactive oxygen species (ROS), 4-hydroxy-2-nonenal (4-HNE) adducts, and protein carbonyl residues compared with a sodium selenite control (SS, 5 μM). Results Se deprivation induced a reduction (P &lt; 0.05) in GPX activity (62%), GPX1 expression, and both SELENOP (33%) and SELENOP expression. In contrast, an increase (P &lt; 0.05) in GPX2 expression and no effect in TXNRD activity (P = 0.09) were observed. HMSeBA supplementation increased (P &lt; 0.05) GPX activity (12.5–625 μM, 1.68–1.82-fold) and SELENOP protein expression (250 and 625 μM, 1.87- and 2.04-fold). Moreover, HMSeBA supplementation increased (P &lt; 0.05) GPX1 (12.5 and 625 μM), GPX2 (625 μM), and SELENOP (12.5 and 625 μM) expression. HMSeBA (625 μM) was capable of decreasing (P &lt; 0.05) ROS (32%), 4-HNE adduct (49%), and protein carbonyl residue (75%) production after H2O2 treatment. Conclusion Caco-2 cells can use HMSeBA as an Se source for selenoprotein synthesis, resulting in protection against oxidative stress.

scholarly journals Two Quenchers Formed During Photodamage of Phostosystem II and The Role of One Quencher in Preemptive Photoprotection

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Alonso Zavafer ◽  
Ievgeniia Iermak ◽  
Mun Hon Cheah ◽  
Wah Soon Chow
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Time Course ◽  
Physiological Role ◽  
Reaction Centre ◽  
Time Resolved ◽  
Fluorescence Quencher

AbstractThe quenching of chlorophyll fluorescence caused by photodamage of Photosystem II (qI) is a well recognized phenomenon, where the nature and physiological role of which are still debatable. Paradoxically, photodamage to the reaction centre of Photosystem II is supposed to be alleviated by excitation quenching mechanisms which manifest as fluorescence quenchers. Here we investigated the time course of PSII photodamage in vivo and in vitro and that of picosecond time-resolved chlorophyll fluorescence (quencher formation). Two long-lived fluorescence quenching processes during photodamage were observed and were formed at different speeds. The slow-developing quenching process exhibited a time course similar to that of the accumulation of photodamaged PSII, while the fast-developing process took place faster than the light-induced PSII damage. We attribute the slow process to the accumulation of photodamaged PSII and the fast process to an independent quenching mechanism that precedes PSII photodamage and that alleviates the inactivation of the PSII reaction centre.

scholarly journals Effect of 1,5-Anhydro-D-Fructose on the Inhibition of Adipogenesis in 3T3-L1 Adipocytes

2012 ◽  
Vol 7 (11) ◽  
pp. 1934578X1200701 ◽  
Author(s):  
Akiko Kojima-Yuasa ◽  
Yohei Deguchi ◽  
Yotaro Konishi ◽  
Isao Matsui-Yuasa
Keyword(s):  
Metabolic Diseases ◽  
Physiological Role ◽  
Structural Similarity ◽  
Regulation Of Transcription ◽  
Energy Sensor ◽  
Mammalian Tissues ◽  
Cellular Lipid Accumulation ◽  
Amp Activated Protein Kinase

1,5-Anhydro-D-fructose (1,5-AF) is a monosaccharide that shares a structural similarity to glucose. 1,5-AF is found in fungi, algae, Escherichia coli and rat liver and is produced by the degradation of starch and glycogen, which is catalyzed by the enzyme α-1,4-glucan lyase. However, the physiological role of 1,5-AF in mammalian tissues is not well understood. Here, we investigated the anti-obesity potential of 1,5-AF on adipogenesis in 3T3-L1 adipocytes. 1,5-AF caused a significant decrease in GPDH activity in 3T3-L1 preadipocytes and mature adipocytes without eliciting cytotoxicity, and inhibited cellular lipid accumulation through down-regulation of transcription factors such as PPARγ and C/EBPα. 1,5-AF also induced dose-dependent phosphorylation of AMP-activated protein kinase (AMPK), a cellular energy sensor. However, the total AMPK protein content remained unchanged. Furthermore, 1,5-AF increased the levels of reactive oxygen species, an important upstream signal for AMPK activation in 3T3-L1 adipocytes. Our results show that 1,5-AF exerts anti-obesity action in vitro and suggest that 1,5-AF is potentially a novel preventative agent for obesity and other metabolic diseases.

scholarly journals Circadian Clock and OxInflammation: Functional Crosstalk in Cutaneous Homeostasis

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Elena Frigato ◽  
Mascia Benedusi ◽  
Anna Guiotto ◽  
Cristiano Bertolucci ◽  
Giuseppe Valacchi
Keyword(s):  
Circadian Clock ◽  
Redox Homeostasis ◽  
Physiological Role ◽  
Protective Role ◽  
Circadian System ◽  
Circadian Disruption ◽  
Cellular Damage ◽  
Lifestyle Risk Factors

Circadian rhythms are biological oscillations that occur with an approximately 24 h period and optimize cellular homeostasis and responses to environmental stimuli. A growing collection of data suggests that chronic circadian disruption caused by novel lifestyle risk factors such as shift work, travel across time zones, or irregular sleep-wake cycles has long-term consequences for human health. Among the multiplicity of physiological systems hypothesized to have a role in the onset of pathologies in case of circadian disruption, there are redox-sensitive defensive pathways and inflammatory machinery. Due to its location and barrier physiological role, the skin is a prototypical tissue to study the influence of environmental insults induced OxInflammation disturbance and circadian system alteration. To better investigate the link among outdoor stressors, OxInflammation, and circadian system, we tested the differential responses of keratinocytes clock synchronized or desynchronized, in an in vitro inflammatory model exposed to O3. Being both NRF2 and NF-κB two key redox-sensitive transcription factors involved in cellular redox homeostasis and inflammation, we analyzed their activation and expression in challenged keratinocytes by O3. Our results suggest that a synchronized circadian clock not only facilitates the protective role of NRF2 in terms of a faster and more efficient defensive response against environmental insults but also moderates the cellular damage resulting from a condition of chronic inflammation. Our results bring new insights on the role of circadian clock in regulating the redox-inflammatory crosstalk influenced by O3 and possibly can be extrapolated to other pollutants able to affect the oxinflammatory cellular processes.

scholarly journals The cytosolic entry of diphtheria toxin catalytic domain requires a host cell cytosolic translocation factor complex

2003 ◽  
Vol 160 (7) ◽  
pp. 1139-1150 ◽  
Author(s):  
Ryan Ratts ◽  
Huiyan Zeng ◽  
Eric A. Berg ◽  
Clare Blue ◽  
Mark E. McComb ◽  
...  
Keyword(s):  
T Cell ◽  
Diphtheria Toxin ◽  
Essential Role ◽  
Reductase Activity ◽  
Translocation Factor ◽  
Thioredoxin Reductase ◽  
Cell Extracts ◽  
Human T Cell ◽  
Early Endosomes

In vitro delivery of the diphtheria toxin catalytic (C) domain from the lumen of purified early endosomes to the external milieu requires the addition of both ATP and a cytosolic translocation factor (CTF) complex. Using the translocation of C-domain ADP-ribosyltransferase activity across the endosomal membrane as an assay, the CTF complex activity was 650–800-fold purified from human T cell and yeast extracts, respectively. The chaperonin heat shock protein (Hsp) 90 and thioredoxin reductase were identified by mass spectrometry sequencing in CTF complexes purified from both human T cell and yeast. Further analysis of the role played by these two proteins with specific inhibitors, both in the in vitro translocation assay and in intact cell toxicity assays, has demonstrated their essential role in the productive delivery of the C-domain from the lumen of early endosomes to the external milieu. These results confirm and extend earlier observations of diphtheria toxin C-domain unfolding and refolding that must occur before and after vesicle membrane translocation. In addition, results presented here demonstrate that thioredoxin reductase activity plays an essential role in the cytosolic release of the C-domain. Because analogous CTF complexes have been partially purified from mammalian and yeast cell extracts, results presented here suggest a common and fundamental mechanism for C-domain translocation across early endosomal membranes.

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