Fibroblast growth factor-9 modulates the expression of myelin related proteins and multiple fibroblast growth factor receptors in developing oligodendrocytes

The effect of fibroblast growth factor (FGF)-9 on the expression of FGF rec eptors (FGFR) and the major myelin proteins was examined in cultures of dev eloping rat brain oligodendrocytes (OLs), using immunological techniques. F GFR-1, -3, and -4 were expressed at all developmental stages but were not p resent in isolated myelin fractions. By contrast, FGFR-2 protein was predom inantly localized to differentiating cells and myelin. FGF-9 altered FGFR a nd myelin protein levels during OL differentiation; there was increased exp ression of FGFR-1 and decreased levels of both FGFR-2 and myelin proteins. Further, FGF-9 stimulated mitogen-associated protein kinase (MAPK) phosphor ylation. The effect of FGF-9 on MAPK, however, was transient and less robus t in progenitor cells than in differentiated oligodendrocytes. The effects of FGF-9 and FGF-2 on FGFR and myelin protein levels were comparable; both up-regulated FGFR-1, and down-regulated FGFR-2, CNP, PLP and MBP. These fin dings suggest that FGF-9 may be important for glial cell development. Publi shed 2000 Wiley-Liss, Inc.(dagger)