Characterization of the promoter region of the human somatostatin receptor subtype 2 gene and localization of sequences required for estrogen-responsiveness.
Somatostatin receptor (sst) subtype 2 mRNA is potently regulated by 17beta-estradiol (E2) in a time and dose-dependent manner in the estrogen receptor (+) human breast cancer cell line T47D. To explore the mechanism involved in E2 regulated expression of sst2, we isolated and characterized a genomic clone containing over 5.3 kilobase pairs (kb) of the 5' flanking region of the human sst2 gene. The 5'-flanking region lacks both TATA and CCAAT boxes. Primer extension and RNAase protection analysis revealed the existence of two transcriptional start sites, located within an initiator-like sequence, 85 and 82 bp upstream of the translational initiation methionine. The 5.3-kb 5'-flanking region was an active promoter in T47D cells but was inactive in MDA MB 435s cells, a human breast cancer cell line that does not express sst2. Deletion analysis identified both positive and negative regulatory elements within the 5.3-kb fragment. Furthermore, transcriptional regulation by E2 was mediated by a distal 1.5-kb fragment located 3.8 kb from the transcriptional start sites. Determining the precise ERE will provide important insights into the complex regulation of sst2 expression in normal and neoplastic tissue.
Department of Medicine, SUNY at Stony Brook, NY 11794, USA.
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Xu
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Berelowitz
J F
JF
Bruno
D001483:Base Sequence; D001943:Breast Neoplasms; D003001:Cloning, Molecular; D004958:Estradiol / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017481:Receptors, Somatostatin / Q000235:genetics; D011993:Recombinant Fusion Proteins; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D014158:Transcription, Genetic / Q000235:genetics; D014407:Tumor Cells, Cultured
D017481:Receptors, Somatostatin; D011993:Recombinant Fusion Proteins; D004958:Estradiol; C093733:somatostatin receptor 2