Research on proteases related to demyelination expressed by oligodendrocytes

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Spinal cord injury is medical and social problem because in most cases the recovery is poor. The limited recovery is mostly caused by scant potential of regeneration of the injured axons. Recent progress of research has shown that the extracellular environment, particularly myelin proteins, may be the primary factor for the inhibition of regeneration. We have shown that oligodendrocytes express extracellular proteases after injury to the central nervous system. In the current study we observed the change of expression of neuropsin and protease M after spinal cord injury and experimental allergic encephalitis (EAE), animal model of multiple sclerosis (MS). Furthermore, the change of possible substrates of neuropsin and nerve regeneration were also studied.All the experiments were approved by the Institute's Animal Ethical Committee.Untreated control mice showed the expression of neuropsin mRNA limited to motoneurons. Protease M mRNA was broadly expressed in white matter. After injury to … More the spinal cord, neuropsin mRNA was expressed by cells in the ventral and lateral funiculi. The upregulation was observed at 1-14 days after injury peaking at 4 day. Protease M protein was abundantly expressed in the lower CNS and the expression was colocalized with CNPase immunoreactivity, marker of mature oligodendrocytes. Electron microscopic analysis revealed that myelins were immunoreactive as well as oligodendrocyte cell bodies. After kainic acid injury, the immunoreactivity to protease M in myelin sheaths was stronger. To explore possible substrate for neuropsin, myelin protein was incubated with neuropsin and separated by electrophoresis and immunoblot was performed. The bands corresponding to myelin basic protein (MBP) became weakened after incubation with neuropsin and immunoblot analysis confirmed that these bands were MBP. EAE peaked 3-4 weeks after injection of MOG. With hematoxylin-eosin staining, infiltrating cells were observed subpial regions of the spinal cord. Neuropsin and protease M mRNA was expressed by the cell around the inflammatory regions.These results show the importance of extracellular proteases in physiological and pathological condition of the CNS. Less