Cloning of murine tissue factor and regulation of gene expression by transforming growth factor type β1

We have cloned a serum- and cycloheximide-inducible mRNA from AKR-2B murine fibroblasts which encodes a protein with significant sequence similarity to human tissue factor, a cellular initiator of the blood coagulation cascade. Information derived from this clone was used to establish the presence of a virtually identical sequence in mouse brain. Most importantly, cDNA-directed expression in a quail fibroblast cell line produced high levels of tissue factor procoagulant activity, confirming the identity of this protein as murine tissue factor. Additional studies demonstrate that transforming growth factor type β1 stimulates tissue factor gene transcription and is a potent inducer of tissue factor procoagulant activity in fibroblasts. Other tested mitogens such as platelet-derived growth factor, epidermal growth factor, and insulin were weak inducers. These results may reflect a role for transforming growth factor β1 in the maintenance of hemostasis or, alternatively, a role for tissue factor in cellular functions unrelated to blood coagulation.