Brefeldin A as a regulator of grp78 gene expression in mammalian cells.
We report here that brefeldin A (BFA), which specifically blocks protein transport from an endoplasmic reticulum to the Golgi apparatus and causes resorption of Golgi membrane to the endoplasmic reticulum, specifically induced the endoplasmic reticulum-resident protein GRP78. Treatment of a human hepatoma cell line Alex-PC with BFA at a concentration of 5 micrograms/ml increased the grp78 transcript level by 12-fold. Analyses of the transcriptional rate of grp78 and the transfection with grp78 promoter suggested that this cell line utilized a posttranscriptional mechanism to increase the expression of grp78 in response to BFA. The induction process was partially dependent on de novo protein synthesis. Interestingly, in a hamster lung fibroblast cell line, K12, the induction of grp78 by BFA could be mediated by a transcriptional control mechanism. We further demonstrated that in K12 cells the region of the grp78 promoter responsive to BFA was within a 40-base pair region between -169 and -130, containing the conserved grp core and a 10-base pair region between -99 to -90 that contained a proximal CCAAT element. A model of how BFA regulates grp78 expression at both the transcriptional and posttranscriptional level is presented.
Liu
E S
ES
Department of Biochemistry, University of Southern California School of Medicine, Los Angeles.
Ou
J H
JH
Lee
A S
AS
D000199:Actins / Q000235:genetics; D015152:Blotting, Northern; D020126:Brefeldin A; D002352:Carrier Proteins / Q000235:genetics*; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003517:Cyclopentanes / Q000494:pharmacology*; D004247:DNA / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D000091342:Endoplasmic Reticulum Chaperone BiP; D005786:Gene Expression Regulation / Q000187:drug effects*; D006360:Heat-Shock Proteins; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000378:metabolism*; D018832:Molecular Chaperones; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D000199:Actins; D002352:Carrier Proteins; D003517:Cyclopentanes; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D007143:Immunoglobulin Heavy Chains; D018832:Molecular Chaperones; D012333:RNA, Messenger; D020126:Brefeldin A; D004247:DNA; D015500:Chloramphenicol O-Acetyltransferase