THE ACTIVATION-DEPENDENT INDUCTION OF APN-(CD13) IN T-CELLS IS CONTROLLED AT DIFFERENT LEVELS OF GENE-EXPRESSION

Recently, it was shown that aminopeptidase N (E.C.3.4.11.2, CD13) is u p-regulated during mitogenic stimulation of peripheral T-cells, In thi s study, we demonstrate that the half-life of APN mRNA was considerabl y prolonged in these cells leading to a 2.7-fold increase of APN trans cript level, The apparent half-life time of the APN transcript was inv estigated by the RNA synthesis inhibitor-chase method using actinomyci n D. The steady-state APN mRNA levels was determined by a competitive RT-PCR, The half-lives estimated in resting T-cells, natural killer ce lls and permanently growing tumour cells varied between 3.5 and 6 h, F inally, nuclear run-on assays revealed that the APN gene expression of stimulated T-cells is controlled by increased promoter activity as we ll, These studies suggest a control of APN gene expression at the post -transcriptional level in addition to promoter-mediated regulation. (C ) 1997 Federation of European Biochemical Societies.