31 research outputs found
Monocytes/macrophages activation contributes to b-gamma-glutamyltransferase accumulation inside atherosclerotic plaques
Gamma-glutamyltransferase (GGT) is a well-established independent risk factor for cardiovascular mortality related to atherosclerotic disease. Four GGT fractions have been identified in plasma, but only b-GGT fraction accumulates in atherosclerotic plaques, and correlates with other histological markers of vulnerability. The present study was aimed to evaluate whether macrophagic lineage cells may provide a source of b-GGT within the atherosclerotic plaque
Modulation of cell growth and cisplatin sensitivity by membrane gamma-glutamyltransferase in melanoma cells.
The plasma membrane enzyme c-glutamyltransferase (GGT) is regarded as critical for the
maintenance of intracellular levels of glutathione (GSH). GGT expression has been implicated
in drug resistance through elevation of intracellular GSH. The dependence of intracellular
GSH on GGT expression was not conclusively ascertained. The present study was
designed to investigate the role of GGT and of intracellular GSH levels in modulating proliferation
and sensitivity to cisplatin of melanoma cells. GGT transfection resulted in
increased growth, both in vitro and in tumour xenografts. In addition, GGT-transfected cells
exhibited reduced sensitivity to cisplatin associated with lower DNA platination. A
decrease in intracellular GSH levels, rather than an increase, was observed in GGT-transfected
cells; moreover, in cysteine-deficient conditions, the expression of GGT did not provide
transfected cells with the ability of utilising extracellular GSH. In conclusion, these results
indicate that GGTactivity confers a growth advantage unrelated with intracellular glutathione
supply, and are consistent with the interpretation that cisplatin resistance is the consequence
of modifications of cellular pharmacokinetics as a result of extracellular drug
inactivation by thiol metabolites originated by GGT-mediated GSH cleavage
Contribution by Polymorphonucleate Granulocytes to Elevated Gamma-Glutamyltransferase in Cystic Fibrosis Sputum
Background: Cystic fibrosis (CF) is an autosomal recessive disorder characterized by a chronic neutrophilic airways
inflammation, increasing levels of oxidative stress and reduced levels of antioxidants such as glutathione (GSH). Gammaglutamyltransferase
(GGT), an enzyme induced by oxidative stress and involved in the catabolism of GSH and its derivatives,
is increased in the airways of CF patients with inflammation, but the possible implications of its increase have not yet been
investigated in detail.
Principal Findings: The present study was aimed to evaluate the origin and the biochemical characteristics of the GGT
detectable in CF sputum. We found GGT activity both in neutrophils and in the fluid, the latter significantly correlating with
myeloperoxidase expression. In neutrophils, GGT was associated with intracellular granules. In the fluid, gel-filtration
chromatography showed the presence of two distinct GGT fractions, the first corresponding to the human plasma b-GGT
fraction, the other to the free enzyme. The same fractions were also observed in the supernatant of ionomycin and fMLPactivated
neutrophils. Western blot analysis confirmed the presence of a single band of GGT immunoreactive peptide in the
CF sputum samples and in isolated neutrophils.
Conclusions: In conclusion, our data indicate that neutrophils are able to transport and release GGT, thus increasing GGT
activity in CF sputum. The prompt release of GGT may have consequences on all GGT substrates, including major
inflammatory mediators such as S-nitrosoglutathione and leukotrienes, and could participate in early modulation of
inflammatory response
HepG2 Spheroids as in Vitro Model to Study the Release of Gamma-glutamyltransferase Fractions
Effect of the three-dimensional organization of liver cells on the biogenesis of the Îł-glutamyltransferase fraction pattern
Context Four gamma-glutamyltransferase (GGT) fractions with different molecular weights (big-, medium-, small- and free-GGT) are detectable in human plasma. Objective Verify if liver cells can release all four GGT fractions and if the spatial cell organization influences their release. Methods Hepatoma (HepG2) and melanoma (Me665/2/60) cells were cultured as monolayers or spheroids. GGT released in culture media was analysed by gel-filtration chromatography. Results HepG2 and Me665/2/60 monolayers released the b-GGT fraction, while significative levels of s-GGT and f-GGT were detectable only in media of HepG2-spheroids. Bile acids alone or in combination with papain promoted the conversion of b-GGT in s-GGT or f-GGT, respectively. Conclusions GGT is usually released as b-GGT, while s-GGT and f-GGT are likely to be produced in the liver extracellular environment by the combined action of bile acids and proteases
Gamma-glutamyltransferase fractions in human plasma and bile: characteristic and biogenesis.
Total plasma gamma-glutamyltransferase (GGT) activity is a sensitive, non-specific marker of liver dysfunction. Four GGT fractions (b-, m-, s-, f-GGT) were described in plasma and their differential specificity in the diagnosis of liver diseases was suggested. Nevertheless fractional GGT properties have not been investigated yet. The aim of this study was to characterize the molecular nature of fractional GGT in both human plasma and bile. Plasma was obtained from healthy volunteers; whereas bile was collected from patients undergoing liver transplantation. Molecular weight (MW), density, distribution by centrifugal sedimentation and sensitivity to both detergent (deoxycholic acid) and protease (papain) were evaluated. A partial purification of b-GGT was obtained by ultracentrifugation. Plasma b-GGT fraction showed a MW of 2000 kDa and a density between 1.063-1.210 g/ml. Detergent converted b-GGT into s-GGT, whereas papain alone did not produce any effect. Plasma m-GGT and s-GGT showed a MW of 1,000 and 200 kDa, and densities between 1.006-1.063 g/ml and 1.063-1.210 g/ml respectively. Both fractions were unaffected by deoxycholic acid, while GGT activity was recovered into f-GGT peak after papain treatment. Plasma f-GGT showed a MW of 70 kDa and a density higher than 1.21 g/ml. We identified only two chromatographic peaks, in bile, showing similar characteristics as plasma b- and f-GGT fractions. These evidences, together with centrifugal sedimentation properties and immunogold electronic microscopy data, indicate that b-GGT is constituted of membrane microvesicles in both bile and plasma, m-GGT and s-GGT might be constituted of bile-acid micelles, while f-GGT represents the free-soluble form of the enzyme
Origins and Significance of Elevated Gamma-glutamyltransferase in Cystic Fibrosis Sputum
Studies on the possible risks of cadmium sulphide nanoparticles: interaction with DNA and living cells
Non-covalent interactions of cadmium sulphide and gold nanoparticles with DNA
Mercaptoethanol-capped CdS nanoparticles (CdSnp) and monohydroxy-(1-mercaptoundec-11-yl) tetraethylene-glycol-capped Au nanoparticles (Aunp) were synthesised, characterised and their interactions with DNA were investigated. Aunp are stable in different aqueous solvents, whereas CdSnp do precip- itate in 0.1 M NaCl and form two different cluster types in 0.1 M NaNO3. As regards the CdSnp/DNA interaction, absorbance and fluorescence titrations, ethidium bromide displacement assays and gel elec- trophoresis experiments indicate that a non-covalent interaction between DNA and the CdSnp external surface does take place. The binding constant was evaluated to be equal to (2.2 ± 0.5) 9 105 M-1. On the contrary, concerning Aunp, no direct interaction with DNA could be observed. Possible interaction with serum albumin was also checked, but no effects could be observed for either CdSnp or Aunp. Finally, short- time exposure of cultured cells to nanoparticles revealed the ability of CdSnp to enter the cells and allocate both in cytosol and nucleus, thus promoting cell proliferation at low concentration (p \ 0.005), while longer-time exposure resulted in a significant inhibition of cell growth, accompanied by apoptotic cell death. Aunp neither enter the cells, nor do affect cell proliferation. In conclusion, our data indicate that CdSnp can strongly interact with living cells and nucleic acid while no effects or interactions were observed for Aunp
Are standard cell culture conditions adequate for human umbilical cord blood mesenchymal stem cells?
Dear Sir,
Due to the detrimental action of free radicals and reactive oxygen species (ROS), oxidative stress is involved in the pathogenesis of ageing and diseases such as inflammation, cancer, cardiovascular disorders and infections. Although this view remains still valid, during the last decade the understanding of oxidative stress has progressively changed and it has become clear that free radicals and reactive oxygen species also play a key role in cell biology and function. In fact, oxidation/reduction reactions are a primary mechanism for regulation of cell proliferation, death, and most notably, cell differentiation, which involves the function of several redox-sensitive molecular elements1. (...