EPITHIN ON THE THYMIC EPITHELIAL CELL REGULATES ANGIOPOIETIN RECEPTOR TIE2 ON THE ENDOTHELIAL CELL

초록

Epithin (PRSS14) that was originally cloned from the thymic stroma library is a type II transmembrane serine protease. It is now also known as matriptase, ST14, MT-SP1 and to be involved in normal epithelial development and tumor progression. From the thymic epithelial cell line 427, a receptor tyrosine kinase Tie2 was identified as an interacting protein. Tie2 is a receptor for angiopoietins and well-known for its important roles in the vessel stability and angiogenesis. Epithin interacts with and degrades the Tie2 extracellular portion that contains the ligand binding domain. Epithin is located in the neighbor of Tie2 expressing vessels in normal thymic medulla and subcapsule. Furthermore, epithin can cleave and degrade Tie2 not only in the same cell but also from neighboring cells nearby, resulting in the degradation of the Tie2 ectodomain. Tie2 signaling evens after modulation by epithin was investigated and its biological significance will be discussed.