Expression of mutant dynamin protects cells against diphtheria toxin but not against ricin
UNSPECIFIED. (1998) Expression of mutant dynamin protects cells against diphtheria toxin but not against ricin. EXPERIMENTAL CELL RESEARCH, 239 (2). pp. 293-300. ISSN 0014-4827Full text not available from this repository.
Diphtheria toxin is believed to enter sensitive mammalian cells via receptor-mediated endocytosis from clathrin-coated pits, while ricin can enter via both clathrin-dependent and clathrin-independent endocytosis. The present study has confirmed this by determining the toxin sensitivity of COS-7y cells which were transiently overexpressing a trans dominant negative mutant of dynamin, a GTPase required for the budding of clathrin-coated vesicles from the plasma membrane. Cells overexpressing wild-type dynamin showed normal receptor-mediated endocytosis of transferrin and remained sensitive to both diphtheria toxin and ricin. Cells overexpressing a mutant dynamin defective in GTP binding and hydrolysis were unable to endocytose transferrin and were protected against diphtheria toxin, but they remained completely sensitive to ricin intoxication. Treating nontransfected cells or cells overexpressing mutant dynamin with nystatin caused a redistribution of the caveolae membrane marker protein VIP21-caveolin from the cell surface to intracellular locations, but did not affect their sensitivity to ricin. The redistribution of caveolin seen after nystatin treatment may reflect the disappearance of caveolae. If this is the case, caveolae are not responsible for the endocytosis of ricin. An alternative clathrin-independent route may operate for ricin, since cellular uptake, intracellular transport, and translocation into the cytosol remain unaffected when clathrin-dependent endocytosis is effectively blocked. (C) 1998 Academic Press.
|Item Type:||Journal Article|
|Subjects:||R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology (including Cancer)
Q Science > QH Natural history > QH301 Biology
|Journal or Publication Title:||EXPERIMENTAL CELL RESEARCH|
|Publisher:||ACADEMIC PRESS INC|
|Date:||15 March 1998|
|Number of Pages:||8|
|Page Range:||pp. 293-300|
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