EXTRACELLULAR PROTEOLYSIS IN THE ADULT MURINE BRAIN

Plasminogen activators are important mediators of extracellular metabo lism. In the nervous system, plasminogen activators are thought to be involved in the remodeling events required for cell migration during d evelopment and regeneration. We have now explored the expression of th e plasminogen activator/plasmin system in the adult murine central ner vous system. Tissue-type plasminogen activator is synthesized by neuro ns of most brain regions, while prominent tissue-type plasminogen acti vator-catalyzed proteolysis is restricted to discrete areas, in partic ular whithin the hippocampus and hypothalamus. Our observations indica te that tissue-type plasminogen activator-catalyzed proteolysis in neu ral tissues is not limited to ontogeny, but may also contribute to adu lt central nervous system physiology, for instance by influencing neur onal plasticity and synaptic reorganization. The identification of an extracellular proteolytic system active in the adult central nervous s ystem may also help gain insights into the pathogeny of neurodegenerat ive disorders associated with extracellular protein deposition.