Cellular uptake and release of the immunomodulating fungal toxin gliotoxin

Waring, Paul; Newcombe, Nicole; Edel, Michael J.; Lin, Qin Hui; Jiang, Hui; Sjaarda, Allan; Piva, Terrence J.; Müllbacher, Arno

doi:10.1016/0041-0101(94)90301-8

Cited by 38 publications

(25 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…GT is a hydrophobic molecule, known to enter cells within seconds. 23 However, in contrast to previous suggestions, 23 it does not seem to act in the cytoplasm or mitochondria for the following reasons: (i) GT is immediately reduced by high levels of glutathione once entering the cytoplasm, and reduced GT cannot trigger apoptosis (data not shown);…”

Section: Discussioncontrasting

confidence: 42%

“…The toxin therefore initiates apoptosis on the plasma membrane, rather than in the cytoplasm or directly on mitochondria (see Supplementary Information and Supplementary Figure S1), although it is known to be taken up by cells. 23,24 GT induces several protein kinase signaling pathways, but only the JNK1/2 pathway is crucial for apoptosis induction. To identify the apoptotic signaling from the cell surface to Bak activation on mitochondria, we monitored in BEAS-2B cells the activation of the signaling kinases AKT, MEK and ERK, p38 MAPK and JNK1/2 in response to GT by using phosphospecific antibodies specific for the active forms of each protein kinase.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Apoptosis induced by the fungal pathogen gliotoxin requires a triple phosphorylation of Bim by JNK

et al. 2013

View full text Add to dashboard Cite

We previously reported that gliotoxin (GT), the major virulence factor of the mold Aspergillus fumigatus causing invasive aspergillosis (IA) in immunocompromised patients, induces apoptosis in a Bak-dependent manner. The signaling pathway leading to Bak activation and subsequent mitochondrial outer membrane permeabilization (MOMP) is elusive. Here, we show that GT and the supernatant of A. fumigatus (but not its GT-defective mutant) activate the JNK pathway and require a co-operative JNK-mediated Bim EL phosphorylation at three sites (S100, T112 and S114) to induce apoptosis in mouse fibroblasts, human bronchial and mouse alveolar epithelial cells. Cells (i) treated with the JNK inhibitor SP600125, (ii) deleted or knocked down for JNK1/2 or Bim or (iii) carrying the Bim EL triple phosphomutant S100A/T112A/S114A instead of wild-type Bim EL are similarly resistant to GT-induced apoptosis. Triple-phosphorylated Bim EL is more stable, redistributes from a cytoskeletal to a membrane fraction, better interacts with Bcl-2 and Bcl-x L and more effectively activates Bak than the unphosphorylated mutant. These data indicate that JNK-mediated Bim EL phosphorylation at S100, T112 and S114 constitutes a novel regulatory mechanism to activate Bim in response to apoptotic stimuli.

show abstract

Section: Discussioncontrasting

confidence: 42%

Section: Resultsmentioning

confidence: 99%

Apoptosis induced by the fungal pathogen gliotoxin requires a triple phosphorylation of Bim by JNK

et al. 2013

View full text Add to dashboard Cite

show abstract

“…A549 cells were shown to have a concentration-dependant growth inhibition to gliotoxin [22] which could be attributed to reactive oxygen species generated through redox cycling [23][24][25]. In rat macrophages and human colonic epithelial cells, gliotoxin inhibited NF-κB activation and significantly inhibited cytokine secretion when stimulated with lipopolysaccharide [26].…”

Section: Discussionmentioning

confidence: 99%

Cytotoxicity of Bacterial-Derived Toxins to Immortal Lung Epithelial and Macrophage Cells

Peterson

Collier

Katterman

et al. 2009

Appl Biochem Biotechnol

View full text Add to dashboard Cite

Health risks associated with inhalation and deposition of biological materials have been a topic of great concern due to highly publicized cases of inhalation anthrax, of new regulations on the release of particulate matter, and to increased concerns on the hazards of indoor air pollution. Here, we present an evaluation of the sensitivity of two immortal cell lines (A549, human lung carcinoma epithelia) and NR8383 (rat alveolar macrophages) to a variety of bacterial-derived inhalation hazards and simulants including etoposide, gliotoxin, streptolysin O, and warfarin. The cell response is evaluated through quantification of changes in mitochondrial succinate dehydrogenase activity, release of lactate dehydrogenase, initiation of apoptosis, and through changes in morphology as determined by visible light microscopy and scanning electron microscopy. These cells display dose-response relations to each toxin, except for triton which has a step change response. The first observable responses of the epithelial cells to these compounds are changes in metabolism for one toxin (warfarin) and alterations in membrane permeability for another (gliotoxin). The other four toxins display a similar time course in response as gauged by changes in metabolism and loss of membrane integrity. Macrophages are more sensitive to most toxins; however, they display a lower level of stability. This information can be used in the design of cell-based sensors responding to these and similar hazards.

show abstract

“…Bond-We have previously reported that gliotoxin actively accumulates in a variety of cell types including human and murine cell lines as well as murine lymphocytes and that up to 40% of the total mass of toxin added to a cell suspension becomes cell-associated within 5-10 min (16). These experiments were carried out with cell densities of 1 ϫ 10 6 /ml.…”

Section: Active Uptake Of Gliotoxin Requires the Bridged Disulfidementioning

confidence: 99%

“…35 S-Labeled gliotoxin was prepared and purified as described (16). Gliotoxin was prepared as a stock solution in absolute ethanol at 1 mg/ml.…”

Section: Chemicals-mentioning

confidence: 99%

A Novel Redox Mechanism for the Glutathione-dependent Reversible Uptake of a Fungal Toxin in Cells

Bernardo

Brasch

Chai

et al. 2003

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

The fungal metabolite gliotoxin is characterized by an internal disulfide bridge and can exist in either disulfide or dithiol forms. Gliotoxin and other members of the epipolythiodioxopiperazine class of toxins have immunosuppressive properties and have been implicated in human and animal mycotoxicoses. The bridged disulfide moiety is thought to be generally essential for biological activity. Here we show that only the natural (oxidized) form of gliotoxin is actively concentrated in a cell line in a glutathione-dependent manner. Intracellular levels of the toxin can be up to 1500-fold greater than the applied concentration, and toxin in the cells exists almost exclusively in the reduced form. A simple model of toxin entry followed by reduction to the cell-impermeant dithiol explains active uptake, cell density dependence of EC 50 values and predicts a value for the maximum concentration of toxin at limiting cell density in agreement with the experiment. Oxidation of the intracellular toxin results in rapid efflux from the cell that also occurs when glutathione levels fall following induction of apoptotic cell death by the toxin. This mechanism allows for minimal production of the toxin while enabling maximal intracellular concentration and thus maximal efficacy of killing in a competitor organism initially present at low cell density. The toxin effluxes from the apoptotic cell exclusively in the oxidized form and can further enter and kill neighboring cells, thus acting in a pseudocatalytic way.

show abstract

Cellular uptake and release of the immunomodulating fungal toxin gliotoxin

Cited by 38 publications

References 24 publications

Apoptosis induced by the fungal pathogen gliotoxin requires a triple phosphorylation of Bim by JNK

Apoptosis induced by the fungal pathogen gliotoxin requires a triple phosphorylation of Bim by JNK

Cytotoxicity of Bacterial-Derived Toxins to Immortal Lung Epithelial and Macrophage Cells

A Novel Redox Mechanism for the Glutathione-dependent Reversible Uptake of a Fungal Toxin in Cells

Contact Info

Product

Resources

About