Plasticity-related serine proteases in the brain (Review)

Serine proteases exert a variety of functions in the body; food digestion, regulation of other proteins and modification of extracellular matrix. Cumu lative evidence has shown the importance of serine proteases in the nervous system as well. It has been shown that three serine proteases, thrombin, p lasminogen activators and neuropsin, have functional roles in neural plasti city. Most of the actions of thrombin are thought to be mediated by its spe cific receptors. Thrombin reverses neurite outgrowth of serum-deprived neur oblastoma cells, and induces protective and apoptotic effects on neurons an d glial cells depending on concentration and time. Tissue-type and urokinas e-type plasminogen activators (tPA and uPA) distribute broadly in the brain , tPA and uPA exert a variety of functions during development. These protea ses also function in long-term potentiation and kindling formation. Further more, tPA is essential to excitotoxic neuronal cell death. Neuropsin is a s erine protease expressed in the limbic system of the brain. Kindling induce d neuropsin mRNA and protein expression and anti-neuropsin antibody amelior ates kindling epilepsy. The possible roles of these proteases in neural pla sticity are reviewed here.