Effect of calmodulin antagonists on endocytosis and intracellular transport of ricin in polarized MDCK cells.
The effect of calmodulin antagonists on endocytosis, transcytosis, recycling, and transport to the Golgi apparatus from both the apical and the basolateral plasma membrane of polarized Madin-Darby canine kidney cells has been investigated by using the plant toxin ricin as a membrane marker. The calmodulin antagonists trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) stimulated apical endocytosis of ricin, whereas basolateral endocytosis was unaffected. A stimulation of the apical uptake of the fluid-phase marker horseradish peroxidase by calmodulin antagonists was also found both by biochemical and by ultrastructural studies. Furthermore, W-7 reduced the recycling of ricin to the apical plasma membrane, whereas the recycling to the basolateral plasma membrane was not changed. Transport of ricin to the Golgi apparatus was also selectively affected by the calmodulin antagonist W-7. After basolateral endocytosis of ricin, transport to the Golgi apparatus was reduced, whereas after apical endocytosis the fraction of endocytosed ricin transport to the Golgi apparatus was increased. Transcytosis of ricin from the basolateral to the apical pole was increased in the presence of calmodulin antagonists, whereas these compounds did not have any significant effect on the apical to basolateral transcytosis. Thus, the results obtained indicate that calmodulin is involved in regulation of apical endocytosis and recycling as well as in transcytosis of ricin from the basolateral plasma membrane. Furthermore, the data suggest that calmodulin plays a role in regulation of ricin transport to the Golgi apparatus.
Llorente
A
A
Institute for Cancer Research, Norwegian Radium Hospital, Montebello, Oslo, Norway.
Garred
O
O
Holm
P K
PK
Eker
P
P
Jacobsen
J
J
van Deurs
B
B
Sandvig
K
K
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity / Q000187:drug effects; D002478:Cells, Cultured / Q000166:cytology / Q000201:enzymology / Q000648:ultrastructure; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004285:Dogs; D018492:Dopamine Antagonists / Q000494:pharmacology; D004705:Endocytosis / Q000187:drug effects*; D006056:Golgi Apparatus / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000493:pharmacokinetics; D007070:Immunoglobulin A / Q000378:metabolism; D007457:Iodine Radioisotopes; D007686:Kidney Tubules, Distal / Q000166:cytology; D008854:Microscopy, Electron; D011493:Protein Kinase C / Q000378:metabolism; D012276:Ricin / Q000378:metabolism*; D013347:Subcellular Fractions; D013449:Sulfonamides / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D002147:Calmodulin; D018492:Dopamine Antagonists; D007070:Immunoglobulin A; D007457:Iodine Radioisotopes; D013449:Sulfonamides; D014665:Vasodilator Agents; D014268:Trifluoperazine; C017967:W 7; D012276:Ricin; D006735:Horseradish Peroxidase; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases