Tissue factor pathway inhibitor-2 is critical in zebrafish cardiogenesis.

Human tissue factor pathway inhibitor-2 (Tfpi-2) is an extracellular matrix-associated Kunitz-type serine proteinase inhibitor and plays an important role in various cellular processes. We have previously shown that zebrafish Tfpi-2 (zTfpi-2) mainly expressed in the brain and heart of zebrafish, and it is involved in the development of central nervous system. Here, we identified zTfpi-2 as an evolutionarily conserved protein essential for zebrafish heart development, as embryos depleted of zTfpi-2 failed to undergo cardiogenesis. Changes of cardiogenic markers, vmhc, amhc and bmp4, confirmed zTfpi-2 knockdown caused cardiac defects, including retrenched ventricle, enlarged atrium and malformation of atrioventricular boundary. The sarcomeric organization was also disrupted by embryonic depletion of zTfpi-2, thus establishing the functional role of zTfpi-2 in cardiac contractility. In addition, hematopoietic defects were detected in the zTfpi-2-deficiency embryos. Importantly, injection of ztfpi-2 mRNA attenuated those cardiac and hematopoietic defects. Taken together, this study demonstrated a critical role of zTfpi-2 during embryonic cardiac development, as well as an important regulator of hematopoiesis.