RESUMO
Neurofibromatosis type 2 (NF2) is an autosomal dominant disease that causes a predisposition to nervous system tumors. Deleterious point mutations have been found in about 55% of NF2 patients, and large genomic deletions account for approximately 33% of NF2 gene alterations. The majority of these deletions are larger than 50 kb, with a breakpoint usually lying outside the NF2 gene. We identified two cases of intragenic deletion with loss of 1.5 and 40 kb, respectively. In both cases, one boundary of the deletion was located in or at the proximity of an SVA sequence in NF2 intron 4. No sequence identity longer than 5 bases and no signal of specific recombination have been evidenced on either side of the deletion breakpoints. These observations are compatible with a nonhomologous recombination being responsible for the genomic deletions. In a third case, a paracentric inversion of chromosome 22 was found. This chromosomal rearrangement breaks the NF2 gene in two parts and carries the first NF2 exon in a juxta-centromeric position. The variability in position of the deletions and the observation of a new chromosomal rearrangement in the NF2 gene underscore the importance of FISH analysis in the molecular diagnosis of NF2.
Assuntos
Rearranjo Gênico , Proteínas de Membrana/genética , Neurofibromatose 2/genética , Sequência de Bases , Deleção Cromossômica , Inversão Cromossômica , DNA/química , DNA/genética , Análise Mutacional de DNA , Mutação em Linhagem Germinativa , Humanos , Hibridização in Situ Fluorescente , Dados de Sequência Molecular , Neurofibromina 2 , Homologia de Sequência do Ácido NucleicoRESUMO
Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder that predisposes to nervous system tumors. The schwannomin (also termed merlin) protein encoded by the NF2 gene shows a close relationship to the family of cytoskeleton-to-membrane proteins linkers ERM (ezrin-radixin-moesin proteins). Even though penetrance of the disease is >95% and no genetic heterogeneity has been described, point mutations in the NF2 gene have been observed in only 34-66% of the screened NF2 patients, depending on the series. In order to generate tools that would enable an exhaustive alteration screening for the NF2 gene, we have deduced its entire genomic sequence. This knowledge has provided the delineation of a mutation screening strategy which, when applied to a series of 19 NF2 patients, has revealed a high recurrence of large deletions in the gene and has raised the efficiency of mutation detection in NF2 patients to 84% of the cases in this series. The remaining three patients who express two functional NF2 alleles are all sporadic cases, an observation compatible with the presence of mosaicism for NF2 mutation.
Assuntos
Genes da Neurofibromatose 2/genética , Neurofibromatose 2/genética , Células Cultivadas , DNA/química , DNA/genética , Éxons , Rearranjo Gênico , Humanos , Hibridização in Situ Fluorescente , Dados de Sequência Molecular , Mutação Puntual , Polimorfismo Genético , RNA/análise , RNA/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNARESUMO
Transfection of brown leghorn chicken embryo fibroblasts by DNA containing v-myb sequences cloned either in a complete AMV proviral DNA or in a retroviral derived vector has led to the isolation of two kinds of transformed cells. A characterization of the proviral sequences retained and expressed in these transformed cells revealed that they contained either new or altered v-myb-related RNA species. The experiments presented in this paper also show that both types of transformants expressed truncated myb-related polypeptides, suggesting that alterations of the v-myb product may result in a new target specificity, leading to the transformation of chicken embryo fibroblasts.
Assuntos
Vírus da Leucose Aviária/genética , Vírus da Mieloblastose Aviária/genética , Transformação Celular Neoplásica , Genes Virais , Oncogenes , Animais , Células Cultivadas , Embrião de Galinha , Clonagem Molecular , DNA/isolamento & purificação , DNA Recombinante/metabolismo , Fibroblastos/citologia , Genes , Peso Molecular , Proteínas de Neoplasias/genética , Peptídeos/isolamento & purificação , RNA/isolamento & purificação , TransfecçãoRESUMO
Two cDNA libraries were constructed, using respectively the 12S and the 16S sucrose gradient fractions of polysomal poly (A)+ RNA from mouse C243 cells induced with Newcastle disease virus. Screening of a part of both libraries by mRNA selection hybridization assays revealed the presence of two plasmids hybridizing to an mRNA, whose translation product was characterized as mouse IFN-beta. Blot analysis of RNA indicated that mRNA hybridizing to the DNA from both plasmids could be detected in induced but not in uninduced C243 cells. The two cDNA inserts did not cross hybridize and had distinct restriction maps. Sequencing revealed that both inserts represented the end of the coding region and the entire 3' non coding region of two district mRNAs. Although different, the putative 39 AA and 65 AA carboxy termini of both Mu IFN-beta s display some homology to human IFN-beta 1. Thus there are at least two different murine IFN-beta genes.