title: K-ras is critical for modulating multiple c-kit-mediated cellular functions in wild-type and Nf1+/- mast cells.
abstract: p21(ras) (Ras) proteins and GTPase-activating proteins (GAPs) tightly modulate extracellular growth factor signals and control multiple cellular functions. The specific function of each Ras isoform (H, N, and K) in regulating distinct effector pathways, and the role of each GAP in negatively modulating the activity of each Ras isoform in myeloid cells and, particularly, mast cells is incompletely understood. In this study, we use murine models of K-ras- and Nf1-deficient mice to examine the role of K-ras in modulating mast cell functions and to identify the role of neurofibromin as a GAP for K-ras in this lineage. We find that K-ras is required for c-kit-mediated mast cell proliferation, survival, migration, and degranulation in vitro and in vivo. Furthermore, the hyperactivation of these cellular functions in Nf1(+/-) mast cells is decreased in a K-ras gene dose-dependent fashion in cells containing mutations in both loci. These findings identify K-ras as a key effector in multiple mast cell functions and identify neurofibromin as a GAP for K-ras in mast cells.
authors.affiliation: Department Microbiology & Immunology, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Waleed F
authors.initials: WF
authors.lastname: Khalaf
authors.forename: Feng-Chun
authors.initials: FC
authors.lastname: Yang
authors.forename: Shi
authors.initials: S
authors.lastname: Chen
authors.forename: Hilary
authors.initials: H
authors.lastname: White
authors.forename: Waylan
authors.initials: W
authors.lastname: Bessler
authors.forename: David A
authors.initials: DA
authors.lastname: Ingram
authors.forename: D Wade
authors.initials: DW
authors.lastname: Clapp
mesh_terms: D000818:Animals; D015550:Cell Degranulation / Q000235:genetics / Q000276:immunology*; D002465:Cell Movement / Q000235:genetics / Q000276:immunology*; D049109:Cell Proliferation; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D008407:Mast Cells / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D025542:Neurofibromin 1 / Q000172:deficiency / Q000276:immunology*; D019009:Proto-Oncogene Proteins c-kit / Q000276:immunology*; D016283:Proto-Oncogene Proteins p21(ras) / Q000172:deficiency / Q000276:immunology*; D040641:Quantitative Trait Loci / Q000235:genetics / Q000276:immunology
chemical_list: D025542:Neurofibromin 1; D019009:Proto-Oncogene Proteins c-kit; D016283:Proto-Oncogene Proteins p21(ras)