Brefeldin A-resistant mutants of human epidermoid carcinoma cell line with structural changes of the Golgi apparatus.
We have isolated brefeldin A (BFA)-resistant cell lines, KB/BF-1 and KB/BF-2, from the human epidermoid carcinoma KB cell line. The BFA-resistant phenotypes have been stably maintained for more than 3 months in the absence of BFA. KB/BF-1 and KB/BF-2 showed 10-30-fold higher resistance to cytotoxicity of BFA but were 2-3-fold more sensitive to monensin and nigericin, than KB cells. KB/BF-1 showed aberrant structures of the Golgi complex with poorly developed cisternae surrounded by many small vesicles. Immunocytochemical studies were done with antibodies against a Golgi-specific antigen (chronic rheumatoid arthritis antigen) and a coatomer subunit (beta-subunit for coat proteins of non-clathrin-coated vesicles). Golgi-specific markers were distributed into the small vesicles which were localized diffusedly in cytoplasm of KB/BF-1 cells. Such Golgi markers were observed in a strictly confined perinuclear region of the parental KB cells, whereas in the mutant cells the markers were distributed more diffusedly in dot-like structures at perinuclear regions. In addition, when exposed to BFA, the mutant and parental cells showed a different distribution of these markers. Synthesis and maturation of low density lipoprotein receptor showed apparently slower rates in processing of low density lipoprotein receptor in KB/BF-1 and KB/BF-2 cells than those observed in their parental KB cells. Protein secretion in KB/BF-1 and KB/BF-2 cells was about 30% less than that in KB cells. Much less inhibition by BFA on the secretion was observed in KB/BF-1 and KB/BF-2 cells. A BFA-resistant mutation in BFA-resistant KB cell lines appears to affect assembly of the Golgi apparatus as well as some Golgi-specific functions.
Seguchi
T
T
Department of Biochemistry, Oita Medical University, Japan.
Goto
Y
Y
Ono
M
M
Fujiwara
T
T
Shimada
T
T
Kung
H F
HF
Nishioka
M
M
Ikehara
Y
Y
Kuwano
M
M
D020126:Brefeldin A; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology*; D004351:Drug Resistance / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008985:Monensin / Q000494:pharmacology; D009154:Mutation; D011233:Precipitin Tests; D011973:Receptors, LDL / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects* / Q000648:ultrastructure
D003517:Cyclopentanes; D011973:Receptors, LDL; D020126:Brefeldin A; D008985:Monensin