OLP-1, A NOVEL PROTEIN THAT DISTINGUISHES EARLY OLIGODENDROCYTE PRECURSORS

Oligodendrocyte development may be divided into three distinct stages: I) commitment of neuroectoderm cells to the oligodendrocyte lineage, IF) migration of precursors into the surrounding parenchyma concomitan t with increased proliferation, and III) cessation of migration and pr oliferation and initiation of myelination, Stage II of development has remained enigmatic because of the paucity of known molecules that dis tinguish these immature migratory cells, We describe a novel surface p rotein, termed OIP-1, which is restricted in expression to this develo pmental stage in the mouse, Cytofluorographic comparisons with known d evelopmental markers showed OIP-1 to be expressed primarily by stage I I precursors in vitro. Histologic analyses supported this conclusion b y showing co-localization of OIP-1 with stage II molecules in vivo. Tw o conclusions were drawn from these results, First, OIP-1 was a novel protein expressed by murine oligodendrocyte precursors at a point in d evelopment that suggested a role in migration or proliferation, Second , dispersal of OIP-1-positive cells throughout the developing brain di d not correlate with the location of myelination which, observed days later, progressed in a caudal to rostral manner, These data supported the concept that the final steps of maturation and myelin gene express ion may be dependent upon extrinsic factors located predominantly with in white matter tracts. (C) 1997 Wiley-Liss, Inc.