TY - JOUR
T1 - Expression of mutant dynamin inhibits toxicity and transport of endocytosed ricin to the Golgi apparatus
AU - Llorente, Alicia
AU - Rapak, Andrzej
AU - Schmid, Sandra L.
AU - Van Deurs, Bo
AU - Sandvig, Kirsten
PY - 1998/2/9
Y1 - 1998/2/9
N2 - Endocytosis and intracellular transport of ricin were studied in stable transfected HeLa cells where overexpression of wild-type (WT) or mutant dynamin is regulated by tetracycline. Overexpression of the temperature- sensitive mutant dyn(G273D) at the nonpermissive temperature or the dyn(K44A) mutant inhibits clathrin-dependent endocytosis (Damke, H., T. Baba, A.M. van der Blieck, and S.L. Schmid. 1995. J. Cell Biol. 131: 69-80; Damke, H., T. Baba, D.E. Warhock, and S.L. Schmid. 1994. J. Cell Biol. 127:915-934). Under these conditions, ricin was endocytosed at a normal level. Surprisingly, overexpression of both mutants made the cells less sensitive to ricin. Butyric acid and trichostatin A treatment enhanced dynamin overexpression and increased the difference in toxin sensitivity between cells with normal and mutant dynamin. Intoxication with ricin seems to require toxin transport to the Golgi apparatus (Sandirg, K., and B. van Deurs. 1996. Physiol. Rev. 76:949-966), and this process was monitored by measuring the incorporation of radioactive sulfate into a modified ricin molecule containing a tyrosine sulfation site. The sulfation of ricin was much greater in cells expressing dyn(WT) than in cells expressing dyn(K44A). Ultrastructural analysis using a ricin-HRP conjugate confirmed that transport to the Golgi apparatus was severely inhibited in cells expressing dyn(K44A). In contrast, ricin transport to lysosomes as measured by degradation of 125I-ricin was essentially unchanged in cells expressing dyn(K44A). These data demonstrate that although ricin is internalized by clathrin-independent endocytosis in cells expressing mutant dynamin, there is a strong and apparently selective inhibition of ricin transport to the Golgi apparatus. Also, in cells with mutant dynamin, there is a redistribution of the mannose-6-phosphate receptor.
AB - Endocytosis and intracellular transport of ricin were studied in stable transfected HeLa cells where overexpression of wild-type (WT) or mutant dynamin is regulated by tetracycline. Overexpression of the temperature- sensitive mutant dyn(G273D) at the nonpermissive temperature or the dyn(K44A) mutant inhibits clathrin-dependent endocytosis (Damke, H., T. Baba, A.M. van der Blieck, and S.L. Schmid. 1995. J. Cell Biol. 131: 69-80; Damke, H., T. Baba, D.E. Warhock, and S.L. Schmid. 1994. J. Cell Biol. 127:915-934). Under these conditions, ricin was endocytosed at a normal level. Surprisingly, overexpression of both mutants made the cells less sensitive to ricin. Butyric acid and trichostatin A treatment enhanced dynamin overexpression and increased the difference in toxin sensitivity between cells with normal and mutant dynamin. Intoxication with ricin seems to require toxin transport to the Golgi apparatus (Sandirg, K., and B. van Deurs. 1996. Physiol. Rev. 76:949-966), and this process was monitored by measuring the incorporation of radioactive sulfate into a modified ricin molecule containing a tyrosine sulfation site. The sulfation of ricin was much greater in cells expressing dyn(WT) than in cells expressing dyn(K44A). Ultrastructural analysis using a ricin-HRP conjugate confirmed that transport to the Golgi apparatus was severely inhibited in cells expressing dyn(K44A). In contrast, ricin transport to lysosomes as measured by degradation of 125I-ricin was essentially unchanged in cells expressing dyn(K44A). These data demonstrate that although ricin is internalized by clathrin-independent endocytosis in cells expressing mutant dynamin, there is a strong and apparently selective inhibition of ricin transport to the Golgi apparatus. Also, in cells with mutant dynamin, there is a redistribution of the mannose-6-phosphate receptor.
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U2 - 10.1083/jcb.140.3.553
DO - 10.1083/jcb.140.3.553
M3 - Article
C2 - 9456316
AN - SCOPUS:0032498544
SN - 0021-9525
VL - 140
SP - 553
EP - 563
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 3
ER -