Assessment of the potential pathogenicity of missense mutations identified in the GTPase-activating protein (GAP)-related domain of the neurofibromatosis type-1 (NF1) gene.
Neurofibromatosis type-1 (NF1) is caused by constitutional mutations of the NF1 tumor-suppressor gene. Although ∼85% of inherited NF1 microlesions constitute truncating mutations, the remaining ∼15% are missense mutations whose pathological relevance is often unclear. The GTPase-activating protein-related domain (GRD) of the NF1-encoded protein, neurofibromin, serves to define its major function as a negative regulator of the Ras-MAPK (mitogen-activated protein kinase) signaling pathway. We have established a functional assay to assess the potential pathogenicity of 15 constitutional nonsynonymous NF1 missense mutations (11 novel and 4 previously reported but not functionally characterized) identified in the NF1-GRD (p.R1204G, p.R1204W, p.R1276Q, p.L1301R, p.I1307V, p.T1324N, p.E1327G, p.Q1336R, p.E1356G, p.R1391G, p.V1398D, p.K1409E, p.P1412R, p.K1436Q, p.S1463F). Individual mutations were introduced into an NF1-GRD expression vector and activated Ras was assayed by an enzyme-linked immunosorbent assay (ELISA). Ten NF1-GRD variants were deemed to be potentially pathogenic by virtue of significantly elevated levels of activated GTP-bound Ras in comparison to wild-type NF1 protein. The remaining five NF1-GRD variants were deemed less likely to be of pathological significance as they exhibited similar levels of activated Ras to the wild-type protein. These conclusions received broad support from both bioinformatic analysis and molecular modeling and serve to improve our understanding of NF1-GRD structure and function.
Institute of Medical Genetics, Cardiff University, Cardiff, UK.
Laura
L
Thomas
Mark
M
Richards
Matthew
M
Mort
Elaine
E
Dunlop
David N
DN
Cooper
Meena
M
Upadhyaya
D020134:Catalytic Domain; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D057809:HEK293 Cells; D006801:Humans; D008957:Models, Genetic; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D009456:Neurofibromatosis 1 / Q000235:genetics*; D025542:Neurofibromin 1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D018631:ras Proteins / Q000378:metabolism
D025542:Neurofibromin 1; D018631:ras Proteins