UROKINASE PLASMINOGEN-ACTIVATOR RECEPTOR (UPAR CD87) EXPRESSION ON MONOCYTIC CELLS AND T-CELLS IS MODULATED BY HIV-1 INFECTION

The transmembranous urokinase-type plasminogen activator receptor (uPA R; CD87) focuses the formation of active plasmin at the cell surface, thus enhancing directional extracellular proteolysis. Since proteolysi s is involved in processes like adhesion, chemotaxis and migration whi ch are important for viral spreading, rye investigated the expression of uPAR in HIV-infected cells. Expression of CD87 was upmodulated in U 937 monocytic cells as well as in the T cell line H9 and in peripheral blood mononuclear cells (PBMC), both on protein and on mRNA level. Th is upmodulation was not caused by enhanced mRNA stability but by an en hanced transcriptional rate of the CD87 gene as shown by nuclear run-o n analysis. To identify the HN-responsive element in the CD87 promoter we investigated the promoter activity in U937 and H9 cells at differe nt time points after HIV-infection. Although the transcription of the CD87 gene is higher in HIV-infected cells the promoter activity declin es after infection, indicating the presence of an additional regulator y element located upstream of the known promoter sequence or in intron sequences.