Cloning of a functional promoter of the human sodium/iodide-symporter gene

We have cloned and sequenced genomic DNA from a human library extending 1300 bp upstream the 5'-untranslated sequence of the cDNA coding for the sodium/iodide symporter. In transient transfection assays this sequence exhibited promoter activity, which could be confined to nucleotides -443 to -395 relative to the ATG start codon. This minimal promoter, including a putative GC- and TATA- box, was preferentially activated in the rat thyroid cell line FRTL-5, but was also active in non-thyroidal cells, such as COS-7 and Chinese-hamster ovary, albeit to a markedly lower extent.