Isolation of a liver-specific promoter for human growth hormone receptor gene

The biological actions of growth hormone (GH) are mediated through the growth hormone receptor (GHR). The GHR gene is expressed in a tissue specific manner and multiple variants (V1 to V8) of GHR mRNA have been detected in human tissues. To understand the regulation of GHR gene expression, a human genomic clone containing the 5'-untranslated region (5'UTR) of the V1, V4, V7 and V8 exons of the GHR was isolated. The 2 kilobase (kb) 5' upstream sequence of the V1 specific UTR has promoter activity in transient transfection assays of the human hepatoma cell line, HepG2. The exclusive expression of the V1 variant in adult liver, and the lack of expression of the other variants in this tissue, suggests that the V1 5'UTR represents the liver specific 5' noncoding exon for the human GHR gene. The data are consistent with the first isolation of a liver specific promoter for human GHR.