Protein toxins: mode of action and cell entry

Sandvig, Kirsten; Dubinina, E. E.; Garred, Øystein; Prydz, Kristian; Kozlov, J. V.; Hansen, Steen Ingemann; Deurs, Bo van

doi:10.1042/bst0200724

Cited by 16 publications

(13 citation statements)

References 6 publications

(6 reference statements)

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“…One possibility is that in normal cells, direct transport from the late endosomes to the Golgi complex occurs, but transport to the lysosomes is relatively minor. Consistent with this pathway are the observations that (i) a fraction of endocytosed Shiga toxin, a glycolipid-binding toxin, is transported to the trans-Golgi network (33)(34)(35)(36) during internalization and (ii) some exogenous glycosphingolipid analogs are transported in part to the Golgi complex during endocytosis (37,38). In this model, ''lipid sorting'' between the Golgi and the lysosomes would be altered in ML-IV cells, perhaps due to alteration of membrane properties or lysosomal accumulation of endogenous lipids.…”

Section: Resultssupporting

confidence: 55%

Abnormal transport along the lysosomal pathway in Mucolipidosis, type IV disease

Chen

Bach

Pagano

1998

Proc. Natl. Acad. Sci. U.S.A.

190

173

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Mucolipidosis, type IV (ML-IV) is an autosomal recessive storage disease that is characterized by lysosomal accumulation of sphingolipids, phospholipids, and acid mucopolysaccharides. Unlike most other storage diseases, the lysosomal hydrolases participating in the catabolism of the stored molecules appear to be normal. In the present study, we examined the hypothesis that the ML-IV phenotype might arise from abnormal transport along the lysosomal pathway. By using various markers for endocytosis, we found that plasma membrane internalization and recycling were nearly identical in ML-IV and normal fibroblasts. A f luorescent analog of lactosylceramide (LacCer) was used to study plasma membrane lipid internalization and subsequent transport. Lipid internalization at 19°C was similar in both cell types; however, 40-60 min after raising the temperature to 37°C, the f luorescent lipid accumulated in the lysosomes of ML-IV cells but was mainly concentrated at the Golgi complex of normal fibroblasts. Biochemical studies demonstrated that at these time points, hydrolysis of the lipid analog was minimal (ϳ7%) in both cell types. A f luorescence ratio imaging assay was developed to monitor accumulation of f luorescent LacCer in the lysosomes and showed that the apparent concentration of the lipid increased more rapidly and to a greater extent in ML-IV cells than in normal fibroblasts. By 60 min, LacCer apparently decreased in the lysosomes of normal fibroblasts but not in ML-IV cells, suggesting that lipid eff lux from the lysosomes was also impaired. These results demonstrate that there is a defect in ML-IV fibroblasts that affects membrane sorting and͞or late steps of endocytosis.

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Section: Resultssupporting

confidence: 55%

Abnormal transport along the lysosomal pathway in Mucolipidosis, type IV disease

Chen

Bach

Pagano

1998

Proc. Natl. Acad. Sci. U.S.A.

190

173

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“…After multivalent binding to Gb 3 receptors, VT1 (and VT2) ( 7 ) is internalized via receptor-mediated endocytosis by both clathrin ( 45,46 ) and caveolar ( 47-49 ) mediated mechanisms. Then the toxin follows a retrograde transport route to the Golgi apparatus and endoplasmic reticulum (ER) ( 15,46,(50)(51)(52) where the A subunit is translocated to the cytosol to inhibit protein synthesis ( 7 ). Despite equivalent Gb 3 expression, cells with higher levels of shorter fatty acid (C16:0,C18) containing Gb 3 were signifi cantly more sensitive to VT1 compared with a cell line with higher levels of longer fatty acid (C24:0) Gb 3 content ( 53 ).…”

Section: Discussionmentioning

confidence: 99%

Fatty acid-dependent globotriaosyl ceramide receptor function in detergent resistant model membranes

Mahfoud

Manis

Lingwood

2009

Journal of Lipid Research

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“…7B). Drugs blocking the endocytic pathway acidification (bafilomycin A 1 , chloroquine, or monensin), known to prevent many bacterial toxins from penetration into the cytosol (19), blocked the activity of LT on cells (data not shown). When Don-wt cells in medium containing anti-LT antibodies were microinjected with LT, they rapidly exhibited the cytopathogenic effect characteristic of LT (Fig.…”

Section: Inhibition Of Egf-induced Phosphorylation Of Map Kinases In mentioning

confidence: 99%

Ras, Rap, and Rac Small GTP-binding Proteins Are Targets for Clostridium sordellii Lethal Toxin Glucosylation

Popoff

Chaves-Olarte

Lemichez

et al. 1996

Journal of Biological Chemistry

201

160

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Lethal toxin (LT) fromClostridium sordellii is one of the high molecular mass clostridial cytotoxins. On cultured cells, it causes a rounding of cell bodies and a disruption of actin stress fibers. We demonstrate that LT is a glucosyltransferase that uses UDP-Glc as a cofactor to covalently modify 21-kDa proteins both in vitro and in vivo. LT glucosylates Ras, Rap, and Rac. In Ras, threonine at position 35 was identified as the target amino acid glucosylated by LT. Other related members of the Ras GTPase superfamily, including RhoA, Cdc42, and Rab6, were not modified by LT. Incubation of serumstarved Swiss 3T3 cells with LT prevents the epidermal growth factor-induced phosphorylation of mitogen-activated protein kinases ERK1 and ERK2, indicating that the toxin blocks Ras function in vivo. We also demonstrate that LT acts inside the cell and that the glucosylation reaction is required to observe its dramatic effect on cell morphology. LT is thus a powerful tool to inhibit Ras function in vivo.Several different species of the genus Clostridium produce large molecular mass (ϳ250 -300 kDa) cytotoxins that cause effects on the actin cytoskeleton, including disruption of actin stress fibers and rounding of cell bodies. This subgroup of clostridial cytotoxins includes toxins A and B from Clostridium difficile, lethal toxin (LT) 1 and hemorrhagic toxin from Clostridium sordellii, and Clostridium novyi ␣-toxin (1). Recently, toxins A and B from C. difficile, the causative agent of antibiotic-associated diarrhea (2), were shown to covalently modify the mammalian protein Rho by UDP-Glc-dependent glucosylation of threonine 37 (3, 4). Rho is a small Ras-related GTPbinding protein involved in the control of actin polymerization (5). Glucosylation of threonine 37 of Rho by C. difficile toxin A or B apparently inactivates this protein and results in a loss of actin stress fiber assembly.C. sordellii produces two toxins, LT and hemorrhagic toxin, two major virulence factors inducing gas gangrene and hemorrhagic diarrhea in humans and animals (6). These C. sordellii toxins have some similarities to toxins A and B from C. difficile in terms of amino acid sequences and immunological epitopes (7). Despite these similarities, it seems that LT and toxins A and B affect different intracellular target proteins. LT causes morphological and cytoskeletal effects different from those elicited by the C. difficile toxins. The effects consist of the rounding of cell bodies with the reorganization of F-actin structures into numerous cell-surface filopodia and a loss of actin stress fibers (8, 9). In addition, we have recently shown that overexpression of RhoA, RhoB, or RhoC cDNA in HeLa cells protects these cells from the effects of toxins A and B, but not from those of LT (9). These observations clearly pointed out that Rho small GTPbinding proteins were the main substrate for the C. difficile toxins and that the targets of LT were distinct.A mutant hamster fibroblast cell line has been described that is resistant to toxins A and B from C. dif...

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Protein toxins: mode of action and cell entry

Cited by 16 publications

References 6 publications

Abnormal transport along the lysosomal pathway in Mucolipidosis, type IV disease

Abnormal transport along the lysosomal pathway in Mucolipidosis, type IV disease

Fatty acid-dependent globotriaosyl ceramide receptor function in detergent resistant model membranes

Ras, Rap, and Rac Small GTP-binding Proteins Are Targets for Clostridium sordellii Lethal Toxin Glucosylation

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