High-resolutions light-microscopic studies of synaptic extracellular proteolysis
Proteolytic remodeling of perisynaptic environment, including extracellular matrix and adhesion molecules, is a novel important mechanism of synaptic plasticity. Among several enzymes participating in the phenomenon, the major role is played by matrix metalloproteinase 9 (MMP-9), a principal neuronal MMP. Recent evidence indicates MMP-9 being involved in long-term potentiation, learning and memory formation, as well as in pathological plasticity underlying epileptogenesis. Here, I present the results of the light-microscopic studies on MMP-9 localization at the synapses in situ, in both central and peripheral nervous systems. The data have been obtained using fl uorescent cytochemical techniques, including immunofl orescence, in situ hybridization and in situ zymography, with the aid of deconvolution-enhanced confocal microscopy. The results underscore the potential of light-microscope-based molecular morphology for studying synaptic function in situ.