title: Neurofibromin, the neurofibromatosis type 1 Ras-GAP, is required for appropriate P0 expression and myelination.
abstract: The neurofibromatosis type 1 (NF1) gene product, neurofibromin, regulates activation of the Ras intracellular signaling pathway in Schwann cells. Schwann cells purified from mouse embryos with null mutations in the Nf1 gene increase expression of the major myelin glycoprotein P0. v-Ras expression in cultured Schwann cells partially mimics loss of Nf1, suggesting a role for Ras in upregulation of P0 expression in Nf1-deficient cells. We tested whether loss of Nf1 alters the ability of Schwann cells to form myelin. No significant changes in myelin formation resulted when Nf1-deficient or v-Ras-expressing Schwann cells were cultured with normal neurons. Yet, in organotypic cultures of neurons, Schwann cells, and fibroblasts without neurofibromin, myelination was dramatically reduced. We suggest that Nf1-dependent signaling cascades in neurons and/or fibroblasts, as well as Schwann cells, are required for normal myelination.
authors.affiliation: Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati Medical School, Ohio 45267-0521, USA.
authors.forename: T
authors.initials: T
authors.lastname: Rosenbaum
authors.forename: H A
authors.initials: HA
authors.lastname: Kim
authors.forename: Y L
authors.initials: YL
authors.lastname: Boissy
authors.forename: B
authors.initials: B
authors.lastname: Ling
authors.forename: N
authors.initials: N
authors.lastname: Ratner
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology*; D005786:Gene Expression Regulation; D016514:Genes, Neurofibromatosis 1; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018993:Myelin P0 Protein / Q000235:genetics*; D009186:Myelin Sheath / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D025542:Neurofibromin 1; D009474:Neurons / Q000502:physiology*; D009924:Organ Culture Techniques; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D012583:Schwann Cells / Q000502:physiology* / Q000648:ultrastructure; D015398:Signal Transduction
chemical_list: D018993:Myelin P0 Protein; D025542:Neurofibromin 1; D011506:Proteins