Differential expression of alternatively spliced neural cell adhesion molecule L1 isoforms during oligodendrocyte maturation

The expression of neural cell adhesion molecules and myelin-specific molecu les is precisely regulated according to cell type and developmental age. We investigated whether different isoforms of these molecules change during d evelopment of oligodendrocytes, Immature oligodendrocytes cultured from emb ryonic day 18 rat cerebrum were distinguished into early stage and late sta ge by morphological and immunocytochemical criteria. mRNA levels of the neu ral cell adhesion molecule L1 in late-stage immature oligodendrocytes were approximately fivefold higher than in early-stage cells, but early-stage im mature oligodendrocytes predominantly expressed an L1 spliced isoform lacki ng two region (exon 2 and 27), Late-stage cells expressed full-length L1 id entical to the neuronal form. mRNA for the neural cell adhesion molecules N CAM and MAG did not show any difference in expression pattern. These result s suggest that alternatively spliced isoforms of L1 might be regulated by t emporal and spatial factors during oligodendrocyte development. (C) 2000 Wi ley-Liss, Inc.