Structural and Functional Characterization of Liver Cell-Specific Activity of the Human Sodium/Taurocholate Cotransporter
| Autor: | Linda C. Quattrochi, Marilee J. Wick, Ishtiaq Qadri, Te-Yen Shiao, Francis R. Simon, Mieko Iwahashi, Susan Bowman, John Fortune |
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| Rok vydání: | 2000 |
| Předmět: |
Hepatocyte Nuclear Factor 3-alpha
Transcription Genetic TATA box Molecular Sequence Data Organic Anion Transporters Sodium-Dependent Dogs Gene expression Genetics Transcriptional regulation Animals Humans Amino Acid Sequence Cloning Molecular Binding site Promoter Regions Genetic Gene Transcription factor Cells Cultured SLC10A1 Binding Sites Base Sequence Symporters biology Liver cell Nuclear Proteins Sequence Analysis DNA Molecular biology Rats DNA-Binding Proteins Gene Expression Regulation Liver Organ Specificity CCAAT-Enhancer-Binding Proteins Hepatocytes biology.protein Carrier Proteins Transcription Factors |
| Zdroj: | Genomics. 69:203-213 |
| ISSN: | 0888-7543 |
| DOI: | 10.1006/geno.2000.6329 |
| Popis: | Bile salts are rapidly removed from the circulation by the liver-specific sodium/taurocholate cotransporter ( SLC10A1 ). To understand factors controlling its liver-specific expression, we isolated human SLC10A1 from a YAC chromosomal clone. SLC10A1 spans ∼23 kb distributed over five exons. The major transcription start site is at 299 bp, and a minor start site is at 395 bp from the translational start site. A 1.2-kb portion of the 5′ flanking region was sequenced and shown to contain a number of liver-enriched elements, but no TATA box. Using secreted alkaline phosphatase reporter constructs liver-specific expression was examined. Transient transfection demonstrated that SLC10A1 promoter expression was selectively expressed eightfold in FAO and rat hepatocytes, while deletion mutants demonstrated liver-specific expression in a region extending from −5 to +198 bp, which contained putative sites for C/EBP and HNF3. Mutations of the C/EBP site resulted in loss of 77% of transcriptional activity. Cotransfection of C/EBP, but not other putative liver-enriched binding factors, increased SLC10A1 promoter activity. Electrophoretic mobility shift assays demonstrated specific protein–DNA interactions that involved C/EBPα and β. These studies demonstrate that the TATA-less human SLC10A1 promoter exhibits liver-specific activity and its regulatory elements contain binding sites for C/EBP, which contributes specifically to its transcriptional regulation. |
| Databáze: | OpenAIRE |
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