Cellular responses to sodium butyrate exhibit the dominance of one parental phenotype in somatic cell hybrids.
The glycoprotein hormone alpha-subunit (GPHalpha) gene is inducible by sodium butyrate (NaBtr) in nontrophoblastic tumor cell lines such as HeLa (cervical carcinoma) but not in trophoblastic tumor cell lines such as JEG-3 (choriocarcinoma). The studies summarized in this report examined the ability of NaBtr to induce GPHalpha expression in somatic cell hybrids between HeLa SR3(hyg) and JEG-3(neo). The hybrid cells, pooled clones resistant to both hygromycin B and G418 sulfate, have been named JELA and were indistinguishable from the SR3 parent with regard to induction of the GPHalpha gene. The effects of NaBtr on cell proliferation were also similar in HeLa and JELA but different from those in JEG-3. The GPHalpha gene could be induced by NaBtr in the JEG-3 parent only when they were simultaneously treated with cycloheximide (CHX). The ability of NaBtr to induce GPHalpha in CHX-treated JEG-3 cells occurred concomitantly with a change in the electrophoretic mobility of enhancer binding proteins as determined in gel shift assays. The DNA-protein complexes generated between a trophoblast specific element (TSE) and nuclear proteins in HeLa SR3 and JELA migrated significantly more slowly than the complex generated by JEG-3 nuclear proteins. However, when nuclear extracts were prepared from CHX-treated JEG-3 cells, the complex generated with the TSE oligonucleotide migrated more slowly than the complex from untreated JEG-3 cells and coincident with the complexes produced with nuclear extracts from HeLa SR3 and JELA cells. Together, these data demonstrate that inducibility of the GPHalpha gene by NaBtr in JELA cell hybrids resembles that of the HeLa SR3 parent and that its inducibility in the JEG-3 parent parallels the status of an enhancer binding protein (TSEB) as judged from changes in electrophoretic mobility. The results are consistent with a model in which the status of TSEB has a profound influence on the gene's response to NaBtr.
Cox
G S
GS
Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, 984525 Nebraska Medical Center, Omaha, Nebraska, 68198-4525, USA.
D002087:Butyrates / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002822:Choriocarcinoma / Q000378:metabolism / Q000473:pathology; D006063:Chorionic Gonadotropin / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004351:Drug Resistance; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D005799:Genes, Dominant; D005839:Gentamicins / Q000494:pharmacology; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics*; D006801:Humans; D006822:Hybrid Cells / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D006921:Hygromycin B / Q000494:pharmacology; D009687:Nuclear Proteins / Q000378:metabolism; D009928:Organ Specificity; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D014162:Transfection; D014327:Trophoblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014407:Tumor Cells, Cultured; D002583:Uterine Cervical Neoplasms / Q000378:metabolism / Q000473:pathology
D002087:Butyrates; D006063:Chorionic Gonadotropin; D004268:DNA-Binding Proteins; D005839:Gentamicins; D015292:Glycoprotein Hormones, alpha Subunit; D009687:Nuclear Proteins; D012333:RNA, Messenger; D006921:Hygromycin B; D004247:DNA; D003513:Cycloheximide; C010680:antibiotic G 418