scholarly journals Zonulin as prehaptoglobin2 regulates lung permeability and activates the complement system

2013 ◽  
Vol 304 (12) ◽  
pp. L863-L872 ◽  
Author(s):  
Daniel Rittirsch ◽  
Michael A. Flierl ◽  
Brian A. Nadeau ◽  
Danielle E. Day ◽  
Markus S. Huber-Lang ◽  
...  
Keyword(s):  
Complement System ◽  
Serine Proteases ◽  
Neutralizing Antibody ◽  
Dependent Manner ◽  
Neutrophil Accumulation ◽  
The Complement System ◽  
Dose Dependent

Zonulin is a protein involved in the regulation of tight junctions (TJ) in epithelial or endothelial cells. Zonulin is known to affect TJ in gut epithelial cells, but little is known about its influences in other organs. Prehaptoglobin2 has been identified as zonulin and is related to serine proteases (MASPs, C1qrs) that activate the complement system. The current study focused on the role of zonulin in development of acute lung injury (ALI) in C57BL/6 male mice following intrapulmonary deposition of IgG immune complexes. A zonulin antagonist (AT-1001) and a related peptide with permeability agonist activities (AT-1002) were employed and given intratracheally or intravenously. Also, zonulin was blocked in lung with a neutralizing antibody. In a dose-dependent manner, AT-1001 or zonulin neutralizing antibody attenuated the intensity of ALI (as quantitated by albumin leak, neutrophil accumulation, and proinflammatory cytokines). A similar pattern was found using the bacterial lipopolysaccharide model of ALI. Using confocal microscopy on sections of injured lungs, staining patterns for TJ proteins were discontinuous, reduced, and fragmented. As expected, the leak of blood products into the alveolar space confirmed the passage of 3 and 20 kDa dextran, and albumin. In contrast to AT-1001, application of the zonulin agonist AT-1002 intensified ALI. Zonulin both in vitro and in vivo induced generation of complement C3a and C5a. Collectively, these data suggest that zonulin facilitates development of ALI both by enhancing albumin leak and complement activation as well as increased buildup of neutrophils and cytokines during development of ALI.

scholarly journals Wnt/beta-catenin signalling is dispensable for adult neural stem cell homeostasis and activation

2020 ◽  
Author(s):  
Sophie H. L. Austin ◽  
Lachlan Harris ◽  
Oana Paun ◽  
Piero Rigo ◽  
François Guillemot ◽  
...  
Keyword(s):  
Stem Cell ◽  
Beta Catenin ◽  
Dependent Manner ◽  
Direct Role ◽  
Adult Nscs ◽  
Hippocampal Networks ◽  
Dose Dependent

AbstractAdult mouse hippocampal neural stem cells (NSCs) generate new neurons that integrate into existing hippocampal networks and modulate mood and memory. These NSCs are largely quiescent and are stimulated by niche signals to activate and produce neurons. Wnt/β-catenin signalling acts at different steps along the hippocampal neurogenic lineage and has been shown to promote the proliferation of intermediate progenitor cells. However, whether it has a direct role in the regulation of NSCs still remains unclear. Here we used Wnt/β-catenin reporters and transcriptomic data from in vivo and in vitro models to show that both active and quiescent adult NSCs respond to Wnt/β-catenin signalling. Wnt/β-catenin stimulation instructed neuronal differentiation of active NSCs and promoted the activation or differentiation of quiescent NSCs in a dose-dependent manner. However, we found that inhibiting NSCs response to Wnt, by conditionally deleting β-catenin, did not affect their activation or maintenance of their stem cell characteristics. Together, our results indicate that whilst NSCs do respond to Wnt/β-catenin stimulation in a dose-dependent and state-specific manner, Wnt/β-catenin signalling is not cell-autonomously required to maintain NSC homeostasis, which could reconcile some of the contradictions in the literature as to the role of Wnt/β-catenin signalling in adult hippocampal NSCs.

scholarly journals Sls1p Stimulates Sec63p-Mediated Activation of Kar2p in a Conformation-Dependent Manner in the Yeast Endoplasmic Reticulum

2000 ◽  
Vol 20 (18) ◽  
pp. 6923-6934 ◽  
Author(s):  
Mehdi Kabani ◽  
Jean-Marie Beckerich ◽  
Claude Gaillardin
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Translocation ◽  
Synthetic Lethality ◽  
In Vitro Assays ◽  
Endoplasmic Reticulum Membrane ◽  
Dependent Manner ◽  
Dose Dependent

ABSTRACT We previously characterized the SLS1 gene in the yeastYarrowia lipolytica and showed that it interacts physically with YlKar2p to promote translocation across the endoplasmic-reticulum membrane (A. Boisramé, M. Kabani, J. M. Beckerich, E. Hartmann, and C. Gaillardin, J. Biol. Chem. 273:30903–30908, 1998). A Y. lipolytica Kar2p mutant was isolated that restored interaction with an Sls1p mutant, suggesting that the interaction with Sls1p could be nucleotide and/or conformation dependent. This result was used as a working hypothesis for more accurate investigations in Saccharomyces cerevisiae. We show by two-hybrid an in vitro assays that the S. cerevisiae homologue of Sls1p interacts with ScKar2p. Using dominant lethal mutants of ScKar2p, we were able to show that ScSls1p preferentially interacts with the ADP-bound conformation of the molecular chaperone. Synthetic lethality was observed between ΔScsls1 and translocation-deficientkar2 or sec63-1 mutants, providing in vivo evidence for a role of ScSls1p in protein translocation. Synthetic lethality was also observed with ER-associated degradation and folding-deficient kar2 mutants, strongly suggesting that Sls1p functions are not restricted to the translocation process. We show that Sls1p stimulates in a dose-dependent manner the binding ofScKar2p on the lumenal J domain of Sec63p fused to glutathione S-transferase. Moreover, Sls1p is shown to promote the Sec63p-mediated activation of Kar2p's ATPase activity. Our data strongly suggest that Sls1p could be the first GrpE-like protein described in the endoplasmic reticulum.

scholarly journals Ligand and Structure-Based Hybrid Screening for Anti-Parkinson Agents and their Pharmacological Evaluation

2020 ◽  
Vol 2 (02) ◽  
pp. 30-38
Author(s):  
Mudita Mishra ◽  
Pankaj K. Sonar ◽  
Avinash C. Tripathi ◽  
Shailendra K. Saraf ◽  
Santosh Kumar Verma
Keyword(s):  
Toxicity Assessment ◽  
Dependent Manner ◽  
Standard Drug ◽  
Lipinski’S Rule ◽  
Storage Vesicles ◽  
Dose Dependent ◽  
Hybrid Screening

The behavioral and biochemical antiparkinson effect of 7-hydroxyflavone (7-HF) was evaluated by using virtual screening with an e-pharmacophore and shape-based screening approach, and the compound was screened by using the Sigma Aldrich compound library. Screened hits were filtered based on Lipinski’s rule, absorption, distribution,metabolism,elimination, (software for evaluation) (ADME), and toxicity parameters. The best scoring hit, 7-hydroxy 2 phenyl-4H-chromen-4-one, i.e., 7-HF was selected based on shape similarity (> 0.7), g-score, and conserved interactions. Toxicity assessment of retrieved hits was carried out by Osiris and Lazar programs. This study aims to obtain some potential hits, against various antiparkinson category from reported literature and available online resources, and validate their potency by in vivo, in vitro methods. Reserpine 5 mg/kg produces Parkinson’s like condition by depleting presynaptic catecholamines, particularly dopamine through the process of degranulation of storage vesicles. 7-HF 25, 50, and 100 mg/kg was used as a test compound. Syndopa 275 mg/kg was used as a standard drug. The results demonstrate that treatment with 7-HF improved the total locomotor activity and muscular coordination in the rotarod test. In the open field test, enhanced rearing, grooming duration of mobility, and gripping strength in the chimney test, while a decrease in cataleptic scores in the bar test. 7-HF significantly increases catalase, superoxide dismutase, and reduces glutathione level, while reduced the Malondialdehyde (MDA) level. The total protein concentration was also increased in 7-HF treated groups. The behavioral and biochemical results obtained from this study disclosed a definite neuroprotective role of 7-HF in a dose-dependent manner. It is also clear that 7-HF showed potent and effective antiparkinson activity in a similar way as standard. Interestingly, in behavioral and biochemical studies, 7-HF showed approximately equivalent effects as compared to syndopa.

The kinetics of exsheathment of infective nematode larvae is disturbed in the presence of a tannin-rich plant extract (sainfoin) both in vitro and in vivo

Parasitology ◽  
2007 ◽  
Vol 134 (9) ◽  
pp. 1253-1262 ◽  
Author(s):  
S. BRUNET ◽  
J. AUFRERE ◽  
F. El BABILI ◽  
I. FOURASTE ◽  
H. HOSTE
Keyword(s):  
Parasite Species ◽  
Gastrointestinal Nematodes ◽  
Dependent Manner ◽  
Early Step ◽  
Nematode Larvae ◽  
Kinetics Of ◽  
Dose Dependent

SUMMARYThe mode of action of bioactive plants on gastrointestinal nematodes remains obscure. Previous in vitro studies showed that exsheathment was significantly disturbed after contact with tannin-rich extracts. However, the role of important factors (extract concentration, parasite species) has not been assessed and no information is available on the occurrence in vivo. These questions represent the objectives of this study. The model incorporated the parasites Haemonchus contortus and Trichostrongylus colubriformis with sainfoin as the bioactive plant. A set of in vitro assays was performed, measuring the changes observed, after 3 h of contact with increasing concentrations of sainfoin, on the rate of artificial exsheathment. The results indicated that sainfoin extracts interfered with exsheathment in a dose-dependent manner and the process overall was similar for both nematodes. The restoration of control values observed after adding PEG to extracts confirms a major role for tannins. A second study was performed in vivo on rumen-cannulated sheep fed with different proportions of sainfoin in the diet to verify these in vitro results. The consumption of a higher proportion of sainfoin was indeed associated with significant delays in Haemonchus exsheathment. Overall, the results confirmed that interference with the early step of nematode infection might be one of the modes of action that contributes to the anthelmintic properties of tanniniferous plants.

The Role of Membrane Bound Complement in the Aggregation of Mammalian Platelets by Collagen

1975 ◽  
Author(s):  
B. V. Chater
Keyword(s):  
Electron Microscope ◽  
Light Microscopy ◽  
Complement System ◽  
Membrane Bound ◽  
The Complement System ◽  
Adhesion Of Platelets ◽  
Collagen Stimulation

It has been observed in dogs decomplemented with purified Cobra Venom Factor, that their platelets lose the ability to aggregate in response to collagen stimulation. Further investigation of the effect of CVF in vitro in man, dog and rabbit, and in vivo in dog, reveals that in each case CVF abolishes the collagen response of platelets, and that this effect is dose related. Resuspension of CVF inactivated platelets in plasma containing complement, results in a total return of sensitivity to collagen. Examination of CVF inactivated platelets with the electron microscope, fails to show any marked difference from control platelets. Serotonin granules are still present and the platelets retain a discoid appearance. Incubation of platelets with antibodies to Cl, C3 and C5, results in inhibition of the collagen response, this effect also being dose related. Light microscopy studies indicate that CVF does not affect the adhesion of platelets to collagen but appears to prevent subsequent aggregation. It is suggested that the complement system is involved in the induction of release by collagen, and that inhibition by CVF and anti-complement antibodies is the result of a blocking of the release reaction.

IL-1β alters hemodynamics in newborn intestine: role of endothelin

2006 ◽  
Vol 291 (3) ◽  
pp. G404-G413 ◽  
Author(s):  
Philip T. Nowicki
Keyword(s):  
Endothelial Cells ◽  
Vascular Dysfunction ◽  
Mesenteric Arteries ◽  
Dependent Manner ◽  
Selective Blockade ◽  
Endothelial Nitric Oxide ◽  
Dose Dependent

Studies were carried out to determine the effects of IL-1β on newborn intestinal hemodynamics. IL-1β increased the release of ET-1 by primary endothelial cells in a dose-dependent manner; as well, it reduced expression of the endothelin (ET) type B (ETB) receptor on endothelial cells and increased expression of the ET type A (ETA) receptor on vascular smooth muscle cells. IL-1β increased endothelial cell endothelial nitric oxide (NO) synthase (eNOS) expression but did not enhance eNOS activity as evidenced by release of NOx into conditioned medium in response to acetylcholine or shear stress. The effects of IL-1β on flow-induced dilation were evaluated in terminal mesenteric arteries in vitro. Pretreatment with IL-1β (1 ng; 4 h) significantly attenuated vasodilation in response to flow rates of 100 and 200 μl/min. This effect was mediated, in part, by the endothelin ETA receptor; thus selective blockade of ETA receptors with BQ610 nearly restored flow-induced dilation. In contrast, exogenous ET-1 only shifted the diameter-flow curve downward without altering the percent vasodilation in response to flow. The effects of IL-1β on ileal oxygenation were then studied using in vivo gut loops. Intramesenteric artery infusion of IL-1β upstream of the gut loop caused ileal vasoconstriction and reduced the arterial-venous O2 difference across the gut loop; consequently, it reduced ileal oxygenation by 60%. This effect was significantly attenuated by pretreatment with BQ610. These data support a linkage between the proinflammatory cytokine IL-1β and vascular dysfunction within the intestinal circulation, mediated, at least in part, by the ET system.

scholarly journals Nitric oxide-mediated inactivation of mammalian ferrochelatase in vivo and in vitro: possible involvement of the iron-sulphur cluster of the enzyme

1995 ◽  
Vol 310 (2) ◽  
pp. 533-538 ◽  
Author(s):  
T Furukawa ◽  
H Kohno ◽  
R Tokunaga ◽  
S Taketani
Keyword(s):  
Nitric Oxide ◽  
Interferon Gamma ◽  
Biosynthetic Pathway ◽  
Raw 264.7 Cells ◽  
Dependent Manner ◽  
Macrophage Cell ◽  
Dose Dependent

To investigate the role of the iron-sulphur cluster in mammalian ferrochelatases, the terminal enzyme of the haem biosynthetic pathway, we examined the interaction of nitric oxide (NO) and ferrochelatase. When macrophage cell line RAW 264.7 cells were treated with interferon-gamma and lipopolysaccharide NO synthesis in the cells was stimulated, and a decrease in ferrochelatase activity was observed, with no change in the amount of ferrochelatase. The addition of NG-monomethyl-L-arginine, a selective inhibitor of NO synthesis, reduced the effect of interferon-gamma and lipopolysaccharide, while the effect of NG-monomethyl-L-arginine was suppressed by the addition of L-arginine, a substrate of NO synthase. When purified recombinant human ferrochelatase was treated with 3-morpholinosydnonimine, a NO-generating compound, ferrochelatase activity decreased with disappearance of characteristic absorbance spectra of the iron-sulphur cluster. S-Nitroso-N-acetylpenicillamine also reduced the activity, in a dose-dependent manner. These results indicate that ferrochelatase activity can be modulated by NO synthesis probably through disruption of the iron-sulphur cluster. We propose that inactivation of ferrochelatase mediated by NO (or NO-derived species) may play a role in the regulation of haem metabolism.

scholarly journals A U2-snRNP–independent role of SF3b in promoting mRNA export

2019 ◽  
Vol 116 (16) ◽  
pp. 7837-7846 ◽  
Author(s):  
Ke Wang ◽  
Changping Yin ◽  
Xian Du ◽  
Suli Chen ◽  
Jianshu Wang ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Mrna Export ◽  
Mrna Processing ◽  
Dependent Manner ◽  
U2 Snrnp ◽  
Dose Dependent ◽  
Antisense Morpholino

To ensure efficient and accurate gene expression, pre-mRNA processing and mRNA export need to be balanced. However, how this balance is ensured remains largely unclear. Here, we found that SF3b, a component of U2 snRNP that participates in splicing and 3′ processing of pre-mRNAs, interacts with the key mRNA export adaptor THO in vivo and in vitro. Depletion of SF3b reduces THO binding with the mRNA and causes nuclear mRNA retention. Consistently, introducing SF3b binding sites into the mRNA enhances THO recruitment and nuclear export in a dose-dependent manner. These data demonstrate a role of SF3b in promoting mRNA export. In support of this role, SF3b binds with mature mRNAs in the cells. Intriguingly, disruption of U2 snRNP by using a U2 antisense morpholino oligonucleotide does not inhibit, but promotes, the role of SF3b in mRNA export as a result of enhanced SF3b–THO interaction and THO recruitment to the mRNA. Together, our study uncovers a U2-snRNP–independent role of SF3b in mRNA export and suggests that SF3b contributes to balancing pre-mRNA processing and mRNA export.

Selective inhibition of endothelium-dependent dilation in resistance-sized vessels in vivo

1987 ◽  
Vol 253 (2) ◽  
pp. H234-H239 ◽  
Author(s):  
U. Pohl ◽  
L. Dezsi ◽  
B. Simon ◽  
R. Busse
Keyword(s):  
Potent Inhibitor ◽  
Selective Inhibition ◽  
Dependent Manner ◽  
Sham Treatment ◽  
In Vivo Experiments ◽  
Before And After ◽  
Dose Dependent

In vivo experiments were performed in autoperfused hindlimbs of rabbits to investigate the role of endothelium-mediated vasomotion in resistance-sized vessels. The flow responses to the vasodilators acetylcholine (ACh), ATP, and substance P (SP), all of which have been shown to act in an endothelium-dependent manner in large conduit arteries, were studied before and after exposure of the hindleg vasculature to gossypol (a potent inhibitor of endothelium-mediated vasodilation in vitro). The flow responses to adenosine (ADO), nitroglycerin (GTN), and prostaglandin E2 (PGE2), which induce relaxation by a direct effect on vascular smooth muscle, were tested in the same manner. All vasodilators induced dose-dependent increases in femoral flow up to two- to threefold when administered intra-arterially. After gossypol, the flow responses to the endothelium-dependent compounds (ACh, ATP, and SP) were severely reduced (by 88 +/- 3%, P less than 0.01) or sometimes were converted to constrictions (ATP). The flow increases induced by ADO, PGE2, and GTN remained largely unaffected. Sham treatment (gossypol solute only), exposure to indomethacin (10 microM), and ganglionic blockade had no differential effect on the flow responses. The selective action of gossypol in suppressing the flow responses to the endothelium-dependent compounds ACh, ATP, and SP is consistent with a vasomotor role for endothelial cells in resistance-sized vessels in vivo.

scholarly journals Fc-Independent Protection from SARS-CoV-2 Infection by Recombinant Human Monoclonal Antibodies

Antibodies ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 45
Author(s):  
Tal Noy-Porat ◽  
Avishay Edri ◽  
Ron Alcalay ◽  
Efi Makdasi ◽  
David Gur ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Complement System ◽  
Neutralizing Antibodies ◽  
Human Monoclonal Antibodies ◽  
Antibody Treatment ◽  
Future Design ◽  
The Complement System

The use of passively-administered neutralizing antibodies is a promising approach for the prevention and treatment of SARS-CoV-2 infection. Antibody-mediated protection may involve immune system recruitment through Fc-dependent activation of effector cells and the complement system. However, the role of Fc-mediated functions in the efficacious in-vivo neutralization of SARS-CoV-2 is not yet clear, and it is of high importance to delineate the role this process plays in antibody-mediated protection. Toward this aim, we have chosen two highly potent SARS-CoV-2 neutralizing human monoclonal antibodies, MD65 and BLN1 that target distinct domains of the spike (RBD and NTD, respectively). The Fc of these antibodies was engineered to include the triple mutation N297G/S298G/T299A that eliminates glycosylation and the binding to FcγR and to the complement system activator C1q. As expected, the virus neutralization activity (in-vitro) of the engineered antibodies was retained. To study the role of Fc-mediated functions, the protective activity of these antibodies was tested against lethal SARS-CoV-2 infection of K18-hACE2 transgenic mice, when treatment was initiated either before or two days post-exposure. Antibody treatment with both Fc-variants similarly rescued the mice from death reduced viral load and prevented signs of morbidity. Taken together, this work provides important insight regarding the contribution of Fc-effector functions in MD65 and BLN1 antibody-mediated protection, which should aid in the future design of effective antibody-based therapies.

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