Search results for "Cholera Toxin"
showing 10 items of 25 documents
Behavioral fragmentation in the D1CT-7 mouse model of Tourette's syndrome.
2017
Aim The transgenic D1CT-7 mouse is one of the best-characterized animal models of Tourette's syndrome (TS), exhibiting spontaneous tic-like Head-Body Twitches (HBT) and deficits in sensorimotor gating. This study is aimed at evaluating the behavioral dynamics of these mutants and their potential relevance to TS. Methods The behavior of D1CT-7 and Wild Type littermates was firstly assessed by considering frequencies and durations. To detect recurrent real-time behavioral sequences, the multivariate T-pattern analysis was employed. Analyses of transition probabilities among behaviors further provided an overall picture of the behavioral dynamics. Results T-patterns and transition matrices rev…
Cholera Toxin Subunit B for Sensitive and Rapid Determination of Exosomes by Gel Filtration.
2020
We developed a sensitive fluorescence-based assay for determination of exosome concentration. In our assay, Cholera toxin subunit B (CTB) conjugated to a fluorescence probe and a gel filtration technique (size-exclusion chromatography) are used. Exosomal membranes are particularly enriched in raft-forming lipids (cholesterol, sphingolipids, and saturated phospholipids) and in GM1 ganglioside. CTB binds specifically and with high affinity to exosomal GM1 ganglioside residing in rafts only, and it has long been the probe of choice for membrane rafts. The CTB-gel filtration assay allows for detection of as little as 3 × 108 isolated exosomes/mL in a standard fluorometer, which has a sensitivit…
The Bile Acid Receptor GPBAR-1 (TGR5) Modulates Integrity of Intestinal Barrier and Immune Response to Experimental Colitis
2011
Background GP-BAR1, a member G protein coupled receptor superfamily, is a cell surface bile acid-activated receptor highly expressed in the ileum and colon. In monocytes, ligation of GP-BAR1 by secondary bile acids results in a cAMP-dependent attenuation of cytokine generation. Aims To investigate the role GP-BAR1 in regulating intestinal homeostasis and inflammation-driven immune dysfunction in rodent models of colitis. Methods Colitis was induced in wild type and GP-BAR1−/− mice by DSS and TNBS administration. Potential GP-BAR1 agonists were identified by in silico screening and computational docking studies. Results GP-BAR1−/− mice develop an abnormal morphology of colonic mucous cells a…
Coupling of Cholesterol and Cone-shaped Lipids in Bilayers Augments Membrane Permeabilization by the Cholesterol-specific Toxins Streptolysin O and V…
2001
Abstract Vibrio cholerae cytolysin (VCC) forms oligomeric pores in lipid bilayers containing cholesterol. Membrane permeabilization is inefficient if the sterol is embedded within bilayers prepared from phosphatidylcholine only but is greatly enhanced if the target membrane also contains ceramide. Although the enhancement of VCC action is stereospecific with respect to cholesterol, we show here that no such specificity applies to the two stereocenters in ceramide; all four stereoisomers of ceramide enhanced VCC activity in cholesterol-containing bilayers. A wide variety of ceramide analogs were as effective asd-erythro-ceramide, as was diacylglycerol, suggesting that the effect of ceramide …
Gliadin, zonulin and gut permeabilità: effects on celiac and non-celiac intestinal mucosa and intestinal cell lines.
2006
Objective. Little is known about the interaction of gliadin with intestinal epithelial cells and the mechanism(s) through which gliadin crosses the intestinal epithelial barrier. We investigated whether gliadin has any immediate effect on zonulin release and signaling. Material and methods. Both ex vivo human small intestines and intestinal cell monolayers were exposed to gliadin, and zonulin release and changes in paracellular permeability were monitored in the presence and absence of zonulin antagonism. Zonulin binding, cytoskeletal rearrangement, and zonula occludens-1 (ZO-1) redistribution were evaluated by immunofluorescence microscopy. Tight junction occludin and ZO-1 gene expression …
Cholera-Like Enterotoxins and Regulatory T cells
2010
Cholera toxin (CT) and the heat-labile enterotoxin of E. coli (LT), as well as their non toxic mutants, are potent mucosal adjuvants of immunization eliciting mucosal and systemic responses against unrelated co-administered antigens in experimental models and in humans (non toxic mutants). These enterotoxins are composed of two subunits, the A subunit, responsible for an ADP-ribosyl transferase activity and the B subunit, responsible for cell binding. Paradoxically, whereas the whole toxins have adjuvant properties, the B subunits of CT (CTB) and of LT (LTB) have been shown to induce antigen specific tolerance when administered mucosally with antigens in experimental models as well as, rece…
Light-Dependent Translocation of Arrestin in Rod Photoreceptors is Signaled through a Phospholipase C Cascade and Requires ATP
2009
Light adaptation of rod photoreceptors induces translocation of arrestin from inner segments (IS) to outer segments (OS). Our study suggests that components of the G-protein linked phosphoinositide pathway play a role in signaling the initiating events of arrestin translocation. We show that arrestin translocation can be stimulated by activators of phospholipase C (PLC) and protein kinase C (PKC) in the absence of light. Conversely, arrestin translocation to the OS is significantly slowed by inhibitors of PLC and PKC.In the second part of this study, we investigated the mechanism by which arrestin translocates in response to light. Other investigators have suggested that arrestin translocat…
The cytotoxin-hemolysin genes of human and eel pathogenic Vibrio vulnificus strains: comparison of nucleotide sequences and application to the geneti…
2005
Vibrio vulnificus can be divided into two groups on the basis of pathogenesis. Group 1 is pathogenic only to humans, whereas group 2 is pathogenic to eels and occasionally to humans. Although both groups produce a 50-kDa cytotoxin-hemolysin (V. vulnificus hemolysin; VVH), the toxins are different. In the present study, the nucleotide sequence of the toxin gene (vvhA ) of strain CDC B3547 (a group 2 strain) was determined, and the deduced amino acid sequence was compared to that of strain L-180 (a group 1 strain). The nucleotide sequence of vvhA of strain CDC B3547 was about 96% identical with that of strain L-180, which results in a difference of 3 amino acid residues in the C-terminal lect…
Down-regulation of transcription factors AP-1, Sp-1, and NF-kappa B precedes myocyte differentiation.
1996
Terminal differentiation of myocytes involves withdrawal from the cell cycle, induction of myogenin expression, and finally formation of myotubes. To study the factors that regulate the initial phase of muscle differentiation, we analyzed the binding activities of transcription factors AP-1, Sp-1, and NF-kappa B in L6, C2C12, and rhabdomyosarcoma BA-Han-1C cells. Temporal changes in transcription factor binding activities were compared to the activation of myogenin promoter-driven CAT reporter gene and the expression level of myogenin, a master gene of myogenic differentiation. We observed a prominent decrease in the nuclear binding activities of AP-1, Sp-1, and NF-kappa B already 12 to 24 …
Selective loss of pertussis toxin-sensitive G-proteins from the plasma membrane after antibody-induced internalization of T-cell surface molecules.
1991
Antibody-induced antigenic modulation occurs after binding of antibodies to a variety of cell surface proteins. It is characterized by aggregation and subsequent loss of the molecules from the cell surface, usually by internalization. In this study we have investigated the effect of modulation of the T-cell antigen receptor complex (TCR) and the transferrin receptor (TFR) on the distribution of cholera toxin (CTx)- and pertussis toxin (PTx)-sensitive GTP binding proteins in human T-lymphocytes. Modulation of both the TCR and the TFR induced a selective shift of PTx-sensitive G-proteins from the plasma membrane to a high density membrane fraction enriched for lysosomal membranes. The distrib…