Competitive inhibition of a set of endoplasmic reticulum protein genes (GRP78, GRP94, and ERp72) retards cell growth and lowers viability after ionophore treatment.
GRP78, a 78-kDa protein localized in the endoplasmic reticulum (ER), has been implicated in protein processing and stress protection. Its promoter contains a 36-bp region which is conserved among GRP genes across species and has the ability to compete for trans-acting factors mediating GRP gene expression. Integration of about 800 tandem copies of this sequence into the genome of a Chinese hamster ovary cell line (DG44) results in transfectants with the following phenotypes: (i) the induction level of GRP78 by the calcium ionophore A23187 and tunicamycin is reduced 4- and 2-fold, respectively, (ii) the induction levels of two other ER luminal protein genes, GRP94 and ERp72, are simultaneously down-regulated, (iii) the growth rate of these cells is half that of transfectants without the amplified sequence, and (iv) cell viability is decreased by 25-fold after A23187 treatment. These results provide new evidence that ERp72 shares common trans-acting regulatory factors with the GRP genes and that a reduction of this set of ER proteins correlates with lower viability after ionophore treatment.
Li
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Department of Biochemistry, University of Southern California School of Medicine, Los Angeles 90033.
Lee
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D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D004721:Endoplasmic Reticulum / Q000502:physiology*; D000091342:Endoplasmic Reticulum Chaperone BiP; D005784:Gene Amplification; D015870:Gene Expression / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D018832:Molecular Chaperones; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D014162:Transfection; D014415:Tunicamycin / Q000494:pharmacology
D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D012333:RNA, Messenger; C062477:endoplasmic reticulum glycoprotein p72; C018551:glucose-regulated proteins; D014415:Tunicamycin; D000001:Calcimycin