Genomic structure and promoter activity of the human tissue factor pathway inhibitor-2 gene

Human type-2 tissue factor pathway inhibitor (TFPI-2), also known as placental protein 5, is a 32 kDa serine proteinase inhibitor consisting of three tandemly arranged Kunitz-type inhibitor domains homologous to tissue factor pathway inhibitor. TFPI-2 strongly inhibits a wide variety of serine proteinases including trypsin, chymotrypsin, plasmin, kallikrein and blood coagulation factor XIa. In this study, we have isolated and characterized a genomic clone from an artificial chromosome genomic library that encodes the entire human TFPI-2 gene. The human TFPI-2 gene spans approximately 7 kb and consists of five exons and four introns. Each Kunitz-type domain is encoded by a single exon, similar to that observed for murine TFPI-2 and other Kunitz-type proteinase inhibitors. A total of 535 bp of the 3'-flanking region contain two probable polyadenylation sites (AATAAA) at +4297 and +4314. A single transcription initiation site was identified by oligo-capping and reverse transcription-PCR analysis. Transient transfection of reporter plasmids containing segments of the 5'-flanking region into human transformed bone marrow endothelial cells and glioblastoma cells identified an 85 bp region (-224 to -139) sufficient for transcription of the human TFPI-2 gene.