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PMID: 10900196 Published · ppublish English Comparative Study Journal Article Research Support, U.S. Gov't, P.H.S.

Single cell Ras-GTP analysis reveals altered Ras activity in a subpopulation of neurofibroma Schwann cells but not fibroblasts.

The Journal of biological chemistry ·Vol. 275 ·No. 39 ·2000-09-29 ·Pages 30740-5

Sherman LS, Atit R, Rosenbaum T, Cox AD, Ratner N

Abstract

Neurofibromatosis type 1 (NF1) is a common genetic disorder characterized by multiple neurofibromas, peripheral nerve tumors containing mainly Schwann cells and fibroblasts. The NF1 gene encodes neurofibromin, a tumor suppressor postulated to function in part as a Ras GTPase-activating protein. The roles of different cell types and of elevated Ras-GTP in neurofibroma formation are unclear. To determine which neurofibroma cell type has altered Ras-GTP regulation, we developed an immunocytochemical assay for active, GTP-bound Ras. In NIH 3T3 cells, the assay detected overexpressed, constitutively activated K-, N-, and Ha-Ras and insulin-induced endogenous Ras-GTP. In dissociated neurofibroma cells from NF1 patients, Ras-GTP was elevated in Schwann cells but not fibroblasts. Twelve to 62% of tumor Schwann cells showed elevated Ras-GTP, unexpectedly revealing neurofibroma Schwann cell heterogeneity. Increased basal Ras-GTP did not correlate with increased cell proliferation. Normal human Schwann cells, however, did not demonstrate elevated basal Ras activity. Furthermore, compared with cells from wild type littermates, Ras-GTP was elevated in all mouse Nf1(-/-) Schwann cells but never in Nf1(-/-) mouse fibroblasts. Our results indicate that Ras activity is detectably increased in only some neurofibroma Schwann cells and suggest that neurofibromin is not an essential regulator of Ras activity in fibroblasts.

MeSH Terms
Animals Cell Separation Fibroblasts/chemistry Glutathione Transferase/genetics,metabolism Guanosine Triphosphate/isolation & purification Histocytochemistry/methods Mice Mice, Mutant Strains Nerve Tissue Proteins/genetics Neurofibroma/chemistry,pathology Neurofibromin 1 Peptide Fragments/genetics,metabolism Protein Binding Proto-Oncogene Proteins c-raf/genetics,metabolism Recombinant Fusion Proteins/genetics,metabolism Schwann Cells/chemistry ras GTPase-Activating Proteins/genetics ras Proteins/isolation & purification
Chemicals
Nerve Tissue Proteins Neurofibromin 1 Peptide Fragments Recombinant Fusion Proteins ras GTPase-Activating Proteins Guanosine Triphosphate Glutathione Transferase Proto-Oncogene Proteins c-raf ras Proteins
Authors & Affiliations
5 authors, click to expand affiliations / ORCID
Sherman L S
Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0521, USA.
Atit R
Rosenbaum T
Cox A D
Ratner N
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Article Info
Journal
The Journal of biological chemistry
Abbr.
J Biol Chem
ISSN
0021-9258
DOI
10.1074/jbc.M001702200
Published
2000-09-29
Pages
30740-5
Language
English
Region
United States
NLM ID
2985121R
PMCID
PMC3066458
Subset
IM
Grants
NCI NIH HHS · CA76092 · United States
NINDS NIH HHS · R01 NS028840-09 · United States
NINDS NIH HHS · R01 NS028840 · United States
NINDS NIH HHS · NS10297 · United States
NINDS NIH HHS · NS28840 · United States
External Links
PubMed source DOI: 10.1074/jbc.M001702200 PMC Full Text View journal details
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