Plasminogen activator inhibitor type 2 gene induction by tumor necrosis factor and phorbol ester involves transcriptional and post-transcriptional events. Identification of a functional nonameric AU-rich motif in the 3'-untranslated region.
Plasminogen activator inhibitor type 2 (PAI-2) mRNA and antigen levels are synergistically induced in HT-1080 fibrosarcoma cells when treated with a combination of tumor necrosis factor (TNF) and phorbol 12-myristate 13-acetate (PMA). Here we demonstrate that this effect is not fully reflected at the level of gene transcription, suggesting a contribution of post-transcriptional events in this induction. Insertion of the 3'-untranslated region (3'-UTR) of PAI-2 mRNA into the 3'-UTR of a rabbit beta-globin reporter gene reduces beta-globin-PAI-2 chimeric mRNA expression in stably transfected cells. The region within the PAI-2 3'-UTR responsible for this effect is located within the 368-nucleotide sequence preceding the poly(A) tail, a segment that includes a nonameric UUAUUUAUU motif. Mutagenesis of this element abolishes the PAI-2 3'-UTR destabilizing effect, revealing a functional role for this motif. TNF and PMA co-treatment of transfected cells increases beta-globin-PAI-2 chimeric mRNA expression 3-4-fold, indicating that the inherently unstable 3'-UTR of PAI-2 mRNA can become stabilized in response to TNF and PMA. Our results indicate that induction of PAI-2 gene expression by TNF and PMA involves both direct transcription as well as mRNA stabilization, the latter involving an AU-rich nonameric motif in the 3'-UTR.
Maurer
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F
Monash University, Department of Medicine, Box Hill Hospital, Box Hill 3128, Australia.
Medcalf
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RL
D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D017931:DNA Primers / Q000378:metabolism; D004357:Drug Synergism; D004587:Electrophoresis, Agar Gel; D005354:Fibrosarcoma / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D005914:Globins / Q000235:genetics; D006801:Humans; D009690:Nucleic Acid Conformation; D017396:Plasminogen Activator Inhibitor 2 / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D017931:DNA Primers; D017396:Plasminogen Activator Inhibitor 2; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D005914:Globins; D013755:Tetradecanoylphorbol Acetate