MICROTUBULE-ASSOCIATED PROTEIN MAP1B EXPRESSION PRECEDES THE MORPHOLOGICAL-DIFFERENTIATION OF OLIGODENDROCYTES

The microtubule-associated protein MAP1B is believed to play an import ant role in the outgrowth of neurites from neurons (Tucker and Matus, Dev Biol 130:423-434, 1988). We have investigated the possibility that MAP1B might participate in the formation of processes in cultured oli godendrocytes by an analysis of the expression of MAP1B during oligode ndrocyte progenitor development. The appearance of the antigens recogn ized by the monoclonal antibodies A2B5, O4, and O1 which define distin ct stages in the maturation of progenitors, was compared with the deve lopmental expression of MAP1B. MAP1B is first detectable in O4+ preoli godendrocytes prior to the acquisition of galactocerebroside and immed iately before they develop the complex process-bearing morphology char acteristic of terminally differentiated myelin-forming oligodendrocyte s in the CNS. In contrast, astrocytes have negligible amounts of MAP1B . These results demonstrate that the expression of MAP1B precedes the development of the mature oligodendrocyte phenotype and suggest that i nteractions between microtubules and MAP1B might have a role in the fo rmation and stabilization of myelin-forming processes.