RAPID COMMUNICATION Regulation of the Plasminogen Activator Inhibitor Type-2 Gene in Monocytes: Localization of an Upstream Transcriptional Silencer

Transcriptional regulation of the plasminogen activator inhibitor type-2 (PAI-2) gene appears to be an important factor in the response of mononuclear phagocytes to inflammation. We have investigated here the molecular basis for PAI2 synthesis in monocytic cells by reporter gene deletion analysis. A DNA fragment containing 5.1 kb of 5' flanking region through to the start of the second exon was fused t o a chloramphenicol acetyl transferase (CAT) reporter gene, transfected into macrophage and nonmacrophage cells and tested for PAI-2 promoter-directed CAT activity in the presence and absence of phorbol ester. Deletion analysis showed the existence of three major transcription regulatory regions. (1) A positive regulatory region contained in the proximal promoter mediates basal transcription and 12-phorbol 13-myristate acetate inducibility. (2) A negative regulatory region, or silencer, present between -1977 and -1675, was found t o repress PAL2 promoter activity in an orientation-