Human tissue plasminogen activator gene: regulation of expression by signals of the 3′-untranslated region

Constructs consisting of a reporter chloramphenicol acetyltransferase (CAT) gene and various deletion versions of the 3′-untranslated region (3UTR) of the human tissue plasminogen activator (tPA) gene were transiently expressed in mammalian cells. In all cases, 3UTR of the tPA gene inhibited the CAT gene expression five-to tenfold, suggesting similar mechanisms of the effect in different mammalian tissues. Experiments on the expression of the nested 3UTR deletion constructs in the CV1 cells allowed one to localize three regions (83, 169, and 219 bp) with signals influencing the reporter gene expression. The first region increased the expression 1.5-2 times, while the second and the third ones inhibited it 2.5-3 times each. Computer analysis revealed substantial homology of these regions with 3UTRs of the mouse and rat tPA genes and their localization in the distinct hairpin-like regions of the mRNA predicted secondary structure. On the basis of pCAT-Control, an expression vector permitting examination of the 3UTR regulatory elements of different genes was constructed.