| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1995: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Myelin proteolipid protein (PLP) and its alternatively spliced isoform, DM-20, are the major integral membrane proteins of central nervous system myelin.It is known that mutations of PLP cause degeneration of immature oligodendrocytes followed by severe dysmyelination.However, it has not been possible to explain why various mutations within the PLP gene affect oligodendrocyte survival.Therefore, an analysis of the function of PLP is important for understanding the development and survival of oligodendrocytes.
We previously showed that the number of oligodendrocytes present in primary glial cell cultures with supernatants from various DM-20 producing neural cell line cells was significantly higher than that of control cultures but not with the NIH3T3 (nonneural cell line) supernatant.To investigate more directly whether the PLP gene expression is involved in this process, NIH3T3 cells were forced to produce PLP or DM-20.By addition of the supernatants from the PLP/DM-20 transformants, th
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e number of oligodendrocytes in mixed glial cell cultures increased.Further, addition of purified PLP and DM-20 showed the same effect on mixed glial culture.These effects were suppressed by anti-PLP monoclonal antibody (AA3).From these findings, we have shown that expression of the PLP gene results in secretion of a factor influencing oligodendrocyte development.
In addition, we identified PLP is an inositol hexakisphosphate (InsP6)-binding protein.Most InsP6-binding proteins are involved in vesicular transport, suggesting PLP-involvement in vesicular transport.Evolutionarily, it is believed that ancestral DM-20 aquired a PLP-specific exon to create PLP,after which PLP/DM-20 became a major component of central nervous system myelin.We separated DM-20 from PLP by CM-52 chromatography and showed that DM-20 has no InsP6-binding activity.These findings indicate that the PLP-specific domain confers the InsP6-binding activity and is important for directing PLP-transport to central nervous system myelin. Less
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