THE ROLE OF PLASMINOGEN IN THE PROLIFERATION OF MURINE HEPATOCYTES IN PRIMARY CULTURE

摘要

Liver regeneration after partial hepatectomy is thought to be regulated by various molecules including the components of the plasminogen activator (PA)-plasmin system. This system has pleiotropic effects, being active in fibrin and ECM degradation, ingrowth factor activation, and in the integrin signaling in cell proliferation. PA is a serine protease that converts the inactive proenzyme, plasminogen, to its active form, plasmin. There are two types of PA known, tissue-type PA (tPA) and urokinase-type PA (uPA, ref.4), and their activities are regulated by a specific inhibitor to PAs, type-1 PA inhibitor (PAI-1). PA and PA1-1 genes are categorized as early growth response genes which are induced after the partial hepatectomy or by growth stimuli, thus the normal liver expresses very tittle PAs or PAI-1. These lines of evidences suggest that PAs and PAI-1 may play important roles in liver regeneration and remodeling. However, the role of the PA-plasmin system in liver regeneration and the regulation mechanisms of the system remain unclear.