MYELIN BASIC-PROTEIN MESSENGER-RNA TRANSLOCATION IN OLIGODENDROCYTES IS INHIBITED BY ASTROCYTES IN-VITRO

Myelin basic protein (MBP) mRNAs are translocated from cell bodies int o the slender processes connecting oligodendrocyte somas with the myel in sheath in vivo. This translocation was observed in mixed glial cult ures prepared from newborn mouse brains and it occurred in approximate ly 25% of the cells expressing the gene. However, when ''enriched'' ol igodendrocytes were prepared by shaking them free of other glial cells , MBP mRNA translocation occurred into the processes of essentially al l of the cells. When enriched oligodendrocytes were plated back onto a strocytes, MBP mRNA was observed to be confined to the cell bodies of almost all the cells, indicating a marked inhibition of translocation of the mRNA. This inhibition of mRNA translocation did not appear to b e mediated through soluble factors secreted by astrocytes or by ''astr omatrix,'' but rather through physical contact between the oligodendro cytes and astrocytes. Intact, but not necessarily live, astrocytes wer e required for the inhibition of mRNA translocation in the oligodendro cytes. Fibroblasts and a neuroblastoma cell line, SKN-SH, did not inhi bit MBP mRNA translocation in oligodendrocytes suggesting that astrocy te surface-specific components might be involved in the interaction be tween astrocytes and oligodendrocytes in culture. These results sugges t that contact between these two cell types can influence intramolecul ar events related to myelinogenesis. (C) 1993 Wiley-Liss, Inc.