RESUMO
In acute promyelocytic leukemia (APL) the retinoic acid receptor alpha (RARα) becomes an oncogene through the fusion with several partners, mostly with promyelocytic leukemia protein (PML), all of which have in common the presence of a self-association domain. The new fusion proteins, therefore, differently from the wild-type RARα, which forms only heterodimers with retinoic X receptor alpha, are also able to homo-oligomerize. The presence of such a domain has been suggested to be crucial for the leukemogenic potential of the chimeric proteins found in APL blasts. Whether or not any self-association domain is sufficient to bestow a leukemogenic activity on RARα is still under investigation. In this work, we address this question using two different X-RARα chimeras, where X represents the coiled-coil domain of PML (CC-RARα) or the oligomerization portion of the yeast transcription factor GCN4 (GCN4-RARα). We demonstrate that in vitro both proteins have transforming potential, and recapitulate the main PML-RARα biological properties, but CC-RARα is uniquely able to disrupt PML nuclear bodies. Indeed, in vivo only the CC-RARα chimera induces efficiently APL in a murine transplantation model. Thus, the PML CC domain represents the minimal structural determinant indispensable to transform RARα into an oncogenic protein.
Assuntos
Transformação Celular Neoplásica , Leucemia Promielocítica Aguda/genética , Proteínas Nucleares/genética , Receptores do Ácido Retinoico/genética , Proteínas Recombinantes de Fusão/fisiologia , Fatores de Transcrição/genética , Proteínas Supressoras de Tumor/genética , Animais , Western Blotting , Cromatografia em Gel , Imunofluorescência , Células-Tronco Hematopoéticas/metabolismo , Imunofenotipagem , Imunoprecipitação , Leucemia Promielocítica Aguda/metabolismo , Leucemia Promielocítica Aguda/patologia , Camundongos , Proteína da Leucemia Promielocítica , Multimerização Proteica , RNA Mensageiro/genética , Receptor alfa de Ácido Retinoico , Reação em Cadeia da Polimerase Via Transcriptase ReversaAssuntos
Transformação Celular Neoplásica , Fator de Transcrição GATA1/genética , Leucemia Experimental/etiologia , Proteínas de Fusão Oncogênica/genética , Proteínas Proto-Oncogênicas c-myb/genética , Animais , Fator de Transcrição GATA1/metabolismo , Rearranjo Gênico , Leucemia Experimental/patologia , Linfoma/etiologia , Linfoma/patologia , Camundongos , Camundongos Knockout , Proteínas Proto-Oncogênicas c-myb/metabolismo , Neoplasias do Timo/etiologia , Neoplasias do Timo/patologia , Proteína Supressora de Tumor p53/fisiologiaRESUMO
Conventional cytogenetics has led to the identification of the primary t(11;22)(q24;q12) translocation in the Ewing's family of tumours, and to the demonstration of certain recurring secondary aberrations that may contribute to neoplastic progression. Other important cytogenetic abnormalities may previously have been overlooked due to the limited resolution of chromosome banding. Here, we have applied the molecular cytogenetic techniques of spectral karyotyping, multiplex-fluorescence in situ hybridisation and comparative genomic hybridisation to the characterisation of seven Ewing's tumour cell lines and one primary culture. These complementary techniques have enabled us to produce a detailed description of the karyotypes of the cell lines and to demonstrate recurring numerical and structural abnormalities. In particular, we have identified a novel, unbalanced translocation involving chromosomes 16 and 17 in three of eight samples, including the primary culture. The unbalanced translocation was associated with comparative genomic hybridisation evidence of loss of 16q and 17p, copy number imbalances that were seen in five and four of the eight samples respectively. Recurrent breakpoints at 16p11.2, 16q11.1, 17p11.2 and 17q11.2 were identified. Our findings indicate that chromosomes 16 and 17 should be investigated further in the search for genes involved in the development of Ewing's family tumours.
Assuntos
Aberrações Cromossômicas , Sarcoma de Ewing/genética , Coloração Cromossômica , Cromossomos Humanos Par 16/genética , Cromossomos Humanos Par 17/genética , Citogenética , Feminino , Humanos , Hibridização in Situ Fluorescente , Cariotipagem , Masculino , Translocação Genética , Células Tumorais CultivadasRESUMO
Our aim was to examine, using microsatellite (ms) markers, the contribution of the telomeric part of the HLA region to rheumatoid arthritis (RA) predisposition in the Spanish population. We have looked at the distribution of DQB1, DRBI and five ms loci (D6S1014, D6S273, D6STNFa, MIB and C1-2-5) within the HLA region in 147 Spanish RA patients and 202 control subjects. A total of 19 conserved ms configurations were observed, twelve of them in linkage disequilibrium with particular DQB1-DRB1 haplotypes. Interestingly, haplotype c1 (DQB1*0201-DRB1*0301-D6S1014*143-D6S273*139-D6STNFa*99-MIB*350-C1-2-5*196) was significantly associated with RA predisposition. As part of this haplotype, the MIB*350 allele was found to be a risk factor independently of the RA-predisposing haplotypes. The present results along with data from others prove the existence of a second predisposing locus located inside the MHC region, and suggest that might be located within the TNFa-HLA-B region.
Assuntos
Artrite Reumatoide/genética , Artrite Reumatoide/imunologia , Predisposição Genética para Doença , Antígenos HLA/genética , Artrite Reumatoide/epidemiologia , Linhagem Celular Transformada , Genes MHC da Classe II/genética , Antígenos HLA/classificação , Haplótipos , Humanos , Repetições de Microssatélites/genética , Epidemiologia Molecular , Fenótipo , Reação em Cadeia da Polimerase , Polimorfismo Genético , Análise de Sequência de DNA , Espanha/epidemiologia , Telômero/genética , Telômero/imunologiaRESUMO
The microsatellite locus TNFa is frequently used as an additional genetic marker in studies of the major histocompatibility complex (MHC). Novel sequence variations at the TNFa locus have been described, and which may have implications for genetic analyses. In this study, we set up a nested polymerase chain reaction-sequence-specific primer (PCR-SSP) approach to type for these TNFa sequence variations. First, sequencing analysis of workshop B lymphoblastoid cell lines (n=13) showed the presence of three sequence variations upstream of the dinucleotide repeat at TNFa. Using nested PCR-SSP, we were able to detect these variations in a larger B lymphoblastoid cell line panel (n=34). Furthermore, we were able to show that TNFa alleles a7 and a10 are present in two distinct conformations leading to "splitting" of TNFa alleles exhibiting identical fragment lengths. To establish the frequency of the TNFa alleles and their variants, we performed microsatellite typing of a large panel of random individuals from the Dutch population (n=272). Subsequent nested PCR-SSP typing showed the presence of three previously described sequence variations in the Dutch population. Furthermore, the presence of a fourth subtype was established. The described variations of allele TNFa7 and TNFa10 are present in the random population with significant frequencies. Haplotyping analysis between HLA-DR, TNFa, and HLA-B showed that allele TNFa7.2 is present in an extended DR7-TNFa7.2-B13 haplotype. In this way, we were able to show that the additional sequence variations behave like distinct TNFa alleles.
Assuntos
Variação Genética , Fator de Necrose Tumoral alfa/genética , Linhagem Celular , Haplótipos , Humanos , Repetições de Microssatélites , Reação em Cadeia da Polimerase/métodos , Fator de Necrose Tumoral alfa/classificaçãoRESUMO
Glaucoma is caused by a sustained elevation of intraocular pressure due to the decreased drainage of aqueous humor from the anterior chamber of the eye. There are many types of glaucoma, which, if left untreated, may have devastating results for the patient. Glaucoma can remain uncontrolled after medical and surgical interventions. Glaucoma drainage device implants with pericardial graft placements often are helpful in relieving the effects of glaucoma and increasing the patient's quality of life.
