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CFTR protein is involved in the efflux of neutral amino acids
No full textTrans-membrane fluxes of leucine were measured in mouse C127i cells transfected with the wild type (C127 CFTRw/t) or the ΔF508 CF gene (C127 CFTRΔF508). Leucine efflux was significantly faster in C127 CFTRw/t cells. On the contrary, leucine influx was comparable in the two cell lines and referable to a 'L-type' transport system. No significant differences in leucine content were detected among the two cell lines when maintained in complete growth medium; in contrast, after prolonged incubation in amino-acid-free saline solution, the amount of intracellular leucine was significantly smaller in C127 CFTRw/t than in C127 CFTRΔF508 cells. Leucine behavior was shared by other neutral amino acids with non polar side chains. These results suggest that the expression of normal CFTR increases the efflux of a subgroup of neutral amino acids
Employment of confocal microscopy for the dynamic visualization of domes in intact epithelial cell cultures
No full textLPS and TNF alpha increase arginine transport but not nitric oxide production in cultured human endothelial cells
No full textTwo-way arginine transport in human endothelial cells: TNF-alpha stimulation is restricted to system y(+)
No full textHuman umbilical vein endothelial cells transport arginine through two Na(+)-independent systems. System y(+)L is insensitive to N-ethylmaleimide (NEM), inhibited by L-leucine in the presence of Na(+), and referable to the expression of SLC7A6/y(+)LAT2, SLC7A7/y(+)LAT1, and SLC3A2/4F2hc. System y(+) is referable to the expression of SLC7A1/CAT1 and SLC7A2/CAT2B. Tumor necrosis factor-alpha (TNF-alpha) and bacterial lipopolysaccharide induce a transient stimulation of arginine influx and efflux through system y(+). Increased expression of SLC7A2/CAT2B is detectable from 3 h of treatment, while SLC7A1 expression is inhibited at later times of incubation. System y(+)L activity and expression remain unaltered. Nitric oxide synthase type 2 mRNA is not detected in the absence or presence of TNF-alpha, while the latter condition lowers nitric oxide synthase type 3 expression at the mRNA and the protein level. Nitrite accumulation is comparable in cytokine-treated and control cells up to 48 h of treatment. It is concluded that modulation of endothelial arginine transport by TNF-alpha or lipopolysaccharide occurs exclusively through changes in CAT2B and CAT1 expression and is dissociated from stimulation of nitric oxide production.Human umbilical vein endothelial cells transport arginine through two Na+-independent systems. System y+L is insensitive to N-ethylmaleimide (NEM), inhibited by L-leucine in the presence of Na+, and referable to the expression of SLC7A6/y+LAT2, SLC7A7/y+LAT1, and SLC3A2/4F2hc. System y+ is referable to the expression of SLC7A1/CAT1 and SLC7A2/CAT2B. Tumor necrosis factor-α (TNF-α) and bacterial lipopolysaccharide induce a transient stimulation of arginine influx and efflux through system y+. Increased expression of SLC7A2/CAT2B is detectable from 3 h of treatment, while SLC7A1 expression is inhibited at later times of incubation. System y+L activity and expression remain unaltered. Nitric oxide synthase type 2 mRNA is not detected in the absence or presence of TNF-α, while the latter condition lowers nitric oxide synthase type 3 expression at the mRNA and the protein level. Nitrite accumulation is comparable in cytokine-treated and control cells up to 48 h of treatment. It is concluded that modulation of endothelial arginine transport by TNF-α or lipopolysaccharide occurs exclusively through changes in CAT2B and CAT1 expression and is dissociated from stimulation of nitric oxide production
Gliadin modulates epithelial permeability by stimulating arginine metabolism in macrophages
No full textMonocytes from infliximab-resistant patients with Crohn's disease exhibit a disordered cytokine profile
No full textCrohn's disease (CD) is a chronic inflammatory disorder characterized by immune response dysregulation. Tumor necrosis factor-alpha (TNF alpha) is a key cytokine in the pathogenesis of CD, as indicated by the efficacy of anti-TNF-alpha therapy with infliximab (IFX). However, approximately 30-40% of CD patients fail to respond to IFX with still unclear underlying mechanisms. This study compares the inflammatory phenotype of monocytes from CD patients, who respond or non-respond to IFX. Under basal conditions, the mRNA for the cytokines TNF alpha, IL-23, IL-1 beta and the chemokines CXCL8/IL-8, CCL5/RANTES and CCL2/MCP-1 was up-regulated in monocytes from non-responders than responders. The expression of the same cytokines and CCL2/MCP-1 was higher in non-responders also upon LPS treatment. Moreover, higher secretion of TNF alpha, IL-1 beta, IFN gamma and IL-2 proteins occurred in the supernatants of LPS-treated non-responders cells. Resistance to IFX in CD may result from a transcriptional dysregulation of circulating monocytes, leading to hyperactivation of pro-inflammatory pathways. Monocytes' cytokine profile may thus represent a predictive marker of response to IFX. Monocytes were isolated from blood samples of 19 CD patients (11 responders, 8 non-responders) and incubated with or without LPS. Cytokine profiles were assessed by RT-qPCR and, in the supernatants, by ELISA assay
LPS and TNF alpha increase arginine transport and CAT-2 expression in cultured human endothelial cells
No full textChanges in neutral amino acid efflux and membrane potential associated with the expression of CFTR protein
No full textThe expression of wild type CFTR facilitates the efflux of neutral amino acids; as a result, after an extensive depletion of intracellular amino acid pool obtained through an incubation in saline solution, the intracellular leucine levels were lower in murine C127 cells transfected with the wild type CF gene (C127 CFTRw/t) than in cells transfected with either mutant CF (C127 CFTRΔF508 cells) or mock vector only. No change in amino acid efflux was detected when C127 CFTRw/t and C127 CFTRΔF508 cells were studied under conditions known to activate protein kinase A. Upon an incubation in Cl- free medium, a permeant analogue of cAMP caused a marked cell depolarization of C127 CFTRw/t cells but not of C127 CFTRΔF508 cells, thus showing a functional expression of CFTR protein in the former cell line. However, we found that, upon a Cl- free incubation and in the absence of exogenous cAMP, C127 CFTRw/t cells developed a marked hyperpolarization that was not detected in C127 CFTRΔF508 cells. It is concluded that the expression of normal CFTR accelerates amino acid efflux and enhances cell hyperpolarization in Cl- free media; both these effects appear to be independent from PKA stimulation of CFTR
The relative expression of genes for arginine transporters in alveolar macrophages from BAL of non specific interstitial pneumonia patients (NSIP)
No full textLPS and TNF alpha increase arginine transport but not nitric oxide production in cultured human endothelial cells
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