INFLUENCE OF 5'-UNTRANSLATED REGION (UTR) SEQUENCE ON THE REGULATION OF HUMAN TISSUE-PLASMINOGEN ACTIVATOR (T-PA) MESSENGER-RNA EXPRESSION

Human tissue plasminogen activator (t-PA) is a serine protease that pl ays a key role in fibrinolysis, a process of dissolving blood clot. t- PA is produced by a variety of cells and tissues and many tumor cell l ines. It is well known that t-PA expression in these cell lines is reg ulated at the transcriptional level([1]). However, little is known abo ut the translational regulation of t-PA expression. We have previously reported that the 3'-untranslated region (3'-UTR) may inhibit t-PA mR NA expression and identified a segment within 3'-UTR which is responsi ble for the translational regulation([2]). The t-PA mRNA has 5'-untran slated region (5'-UTR) of about 209 nucleotides. To investigate whethe r this sequence is involved in the regulation of t-PA expression, we h ave cloned 5' end sequence of t-PA cDNA from melanoma cells by reverse transcription and PCR, then studied the influence of 5'-UTR sequence on t-PA mRNA expression both in reticulocyte lysate and in COS-7 cells .