title: Neurofibromin GTPase-activating protein-related domains restore normal growth in Nf1-/- cells.
abstract: Members of the Ras superfamily of signaling proteins modulate fundamental cellular processes by cycling between an active GTP-bound conformation and an inactive GDP-bound form. Neurofibromin, the protein product of the NF1 tumor suppressor gene, and p120GAP are GTPase-activating proteins (GAPs) for p21(Ras) (Ras) and negatively regulate output by accelerating GTP hydrolysis on Ras. Neurofibromin and p120GAP differ markedly outside of their conserved GAP-related domains (GRDs), and it is therefore unknown if the respective GRDs contribute functional specificity. To address this question, we expressed the GRDs of neurofibromin and p120GAP in primary cells from Nf1 mutant mice in vitro and in vivo. Here we show that expression of neurofibromin GRD, but not the p120GAP GRD, restores normal growth and cytokine signaling in three lineages of primary Nf1-deficient cells that have been implicated in the pathogenesis of neurofibromatosis type 1 (NF1). Furthermore, utilizing a GAP-inactive mutant NF1 GRD identified in a family with NF1, we demonstrate that growth restoration is a function of NF1 GRD GAP activity on p21(Ras). Thus, the GRDs of neurofibromin and p120GAP specify nonoverlapping functions in multiple primary cell types.
authors.affiliation: Herman B Wells Center for Pediatric Research, Departments of Microbiology/Immunology and Pediatrics, Indiana University School of Medicine, Indianapolis 46202, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Hiatt
authors.forename: D A
authors.initials: DA
authors.lastname: Ingram
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: G
authors.initials: G
authors.lastname: Bollag
authors.forename: D W
authors.initials: DW
authors.lastname: Clapp
mesh_terms: D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000378:metabolism; D005838:Genotype; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D009456:Neurofibromatosis 1 / Q000235:genetics / Q000378:metabolism; D025542:Neurofibromin 1; D010957:Plasmids / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction; D014162:Transfection; D020729:p120 GTPase Activating Protein / Q000378:metabolism
chemical_list: D009419:Nerve Tissue Proteins; D025542:Neurofibromin 1; D011994:Recombinant Proteins; D020729:p120 GTPase Activating Protein; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019950:Mitogen-Activated Protein Kinase 1; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)