The serine protease thrombin (F2) is involved in a number of physiological functions beyond hemostasis including angiogenesis, embryogenesis, tumorigenesis and inflammation. Serum levels of prothrombin derive from protein synthesis in the liver, yet expression of the prothrombin gene in a variety of other tissues has been demonstrated to occur during embryogenesis. While considerable insights have been obtained on how plasmatic thrombin exerts its crucial function in various pathologies, little is known about the (patho)physiological functions of extrahepatic prothrombin expression. Using a newly designed transgenic mouse model, we recently observed prothrombin expression in cells of hematopoetic origin.
In the project proposed here we are aiming to identify cell type(s) expressing prothrombin in the hematopoietic compartment. To this end, we will employ FACS sorting followed by luminometry based on purified cells obtained from the reporter mouse model in which endogenous prothrombin expression is tagged by luciferase reporters. Complementary, we will make use of a newly established F2 RNA-FISH technology, which will allow us to counter-validate extrahepatic prothrombin expression on a cellular level in intact murine organs.