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- Title
Haploinsufficiency for the neurofibromatosis 1 (NF1) tumor suppressor results in increased astrocyte proliferation.
- Authors
Gutmann, David H; Loehr, Allison; Zhang, Yujing; Kim, Joanna; Henkemeyer, Mark; Cashen, Amanda
- Abstract
Individuals affected with neurofibromatosis 1 (NF1) harbor increased numbers of GFAP-immunoreactive cerebral astrocytes and develop astrocytomas that can lead to blindness and death. Mice heterozygous for a targeted Nf1 mutation (Nf1+/-) were employed as a model for the human disease to evaluate the hypothesis that reduced NF1 protein (neurofibromin) expression may confer a growth advantage for astrocytes, such that inactivation of only one NF1 allele is sufficient for abnormal astrocyte proliferation. Here, we report that Nf1+/- mice have increased numbers of cerebral astrocytes and increased astrocyte proliferation compared to wild-type littermates. Intriguingly, primary Nf1+/- astrocyte cultures failed to demonstrate a cell-autonomous growth advantage unless they were co-cultured with C17 neuronal cells. This C17 neuronal cell-induced Nf1+/- increase in proliferation was blocked by MEK inhibition (PD98059), suggesting a p21-ras-dependent effect. Furthermore, mice heterozygous for a targeted mutation in another GAP molecule, p120-GAP, demonstrated no increases in cerebral astrocyte number. These findings suggest that reduced NF1 expression results in a cell context-dependent increase in astrocyte proliferation that may be sufficient for the development of astrocytic growth abnormalities in patients with NF1.
- Subjects
NEUROFIBROMATOSIS; ASTROCYTES; PROTEINS; CELL growth; CELL proliferation
- Publication
Oncogene, 1999, Vol 18, Issue 31, p4450
- ISSN
0950-9232
- Publication type
Article
- DOI
10.1038/sj.onc.1202829