Thyroid hormone response element-like sequence in anuran matrix metalloproteinase 1 gene is responsive to in vivo thyroid hormone administration

Gene (Rmmp 1) of matrix metalloproteinase 1 (MMP1) of the bullfrog, Rana ca tesbeiana, has been shown previously to contain a thyroid hormone response element (TRE)like sequence in its 5'-upstream region. The present study aim ed to determine whether this TRE-like sequence is functional in vivo as a t rue TRE, and to characterize the sequences of the 5'-upstream region with r espect to the regulation of the activity of the TRE when the TRE-like seque nce was proved to be a true TRE. With this aim, various sequences of TRE-li ke sequence-containing 5'-upstream region were constructed and fused to the enhanced green fluorescent protein gene as a reporter gene. The fusion con structs were bombarded to the skin of upstream enhanced bullfrog tadpoles a nd the activity of the TRE was quantitatively determined by measuring incre ased intensities of fluorescence when the animals were exposed to thyroid h ormone, The present study clearly demonstrated that the sequence of Rmmp 1 is a biologically active TRE in vivo. In addition, a unique 36 bp long sequ ence directly flanked to the 3'-end of the TRE was identified which worked co-operatively with TRE to regulate the transcriptional promoter activity. It should be emphasized that the presence of TRE. in the Rmmp 1 gene is uni que, because its presence has not been reported in the known promoter regio n of vertebrate MMPs.