title: Human placental lactogen transcriptional enhancer. Tissue specificity and binding with specific proteins.
abstract: Human placental lactogen (hPL) and growth hormone (hGH) are thought to be derived from a common ancestral gene and have similar nucleotide and amino acid sequences. Although the genes are similar in structure, they are expressed in different tissues. A transcriptional enhancer has been found 2.2 kilobases 3' of the hPL3 gene at the distal extreme of the hPL/hGH gene cluster. This enhancer is at least 20-fold more active in hPL-producing human choriocarcinoma JEG-3 cells than in non-hPL-producing cells. The enhancer is active when linked to either the hPL3 or SV40 promoter. We have localized the hPL enhancer to a 138-base pair (bp) region that retains tissue specificity in transient transfection assays. Gel mobility shift assays showed that the hPL enhancer interacted specifically with nuclear proteins from JEG-3 cells and placental tissue. Within the 138-bp enhancer, a 22-bp region overlapping a TEF-1 binding site was shown to be protected from DNase I digestion by placental and HeLa nuclear extracts. Placental protein(s) binding this region may be instrumental in tissue-specific activity of the hPL enhancer.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
authors.forename: W H
authors.initials: WH
authors.lastname: Walker
authors.forename: S L
authors.initials: SL
authors.lastname: Fitzpatrick
authors.forename: G F
authors.initials: GF
authors.lastname: Saunders
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D002822:Choriocarcinoma; D002872:Chromosome Deletion; D004273:DNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D004742:Enhancer Elements, Genetic; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009250:NADP Transhydrogenases / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D009928:Organ Specificity; D010920:Placenta / Q000378:metabolism; D010928:Placental Lactogen / Q000235:genetics*; D011247:Pregnancy; D015183:Restriction Mapping; D014158:Transcription, Genetic; D014594:Uterine Neoplasms
chemical_list: D004273:DNA, Neoplasm; D009687:Nuclear Proteins; D010928:Placental Lactogen; D009247:NADH, NADPH Oxidoreductases; D009250:NADP Transhydrogenases