title: DNA sequences involved in the transcriptional activation of a human placental lactogen gene.
abstract: To identify regulatory elements in the promoter of a human placental lactogen gene (hPL3) that are important for its transcriptional activation, sequences 5' to the start of transcription were linked to the reporter gene chloramphenicol acetyltransferase (CAT) and transiently transfected into JEG-3 cells, a human placental choriocarcinoma cell line. In the presence of the hPL3 enhancer, deletion of the promoter sequence between -142 and -129 basepairs resulted in an 8-fold decrease in CAT activity. Similar results were seen with the SV40 enhancer and the hPL3 promoter in HepG2 liver cells. Nuclear proteins from HepG2, HeLa, and JEG-3 cells formed specific binding complexes with this region of the hPL3 promoter by a gel mobility shift assay, indicating that the DNA-binding protein was not tissue specific. The -142 to -129 basepair region contains a sequence similar to that of a variant binding site for the transcription factor Sp1. An oligonucleotide containing Sp1-binding sites specifically competes for proteins binding the hPL3 promoter, and the methylation interference pattern is similar to that for an Sp1-binding site. This suggests that the hPL3 promoter binds Sp1- or an Sp1-like trans-acting factor, and this binding site is important for transcriptional regulation by the hPL3 enhancer in PL-producing cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
authors.forename: S L
authors.initials: SL
authors.lastname: Fitzpatrick
authors.forename: W H
authors.initials: WH
authors.lastname: Walker
authors.forename: G F
authors.initials: GF
authors.lastname: Saunders
mesh_terms: D001483:Base Sequence; D006528:Carcinoma, Hepatocellular; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D002822:Choriocarcinoma; D002872:Chromosome Deletion; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000235:genetics; D006150:Guanine Nucleotides / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008113:Liver Neoplasms; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000378:metabolism; D010920:Placenta; D010928:Placental Lactogen / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D006150:Guanine Nucleotides; D009687:Nuclear Proteins; D016329:Sp1 Transcription Factor; D004247:DNA; D010928:Placental Lactogen; D015500:Chloramphenicol O-Acetyltransferase