RESUMEN
Loss of heterozygosity (LOH) represents the most frequent genetic alteration observed in hepatocellular carcinoma (HCC). Chromosome 16q is of particular interest as it exhibits LOH in 29% of HCC tumors and is frequently lost in breast, prostate, ovarian and gastric carcinomas. We genotyped 157 HCC tumors for 17 microsatellite markers distributed on chromosome 16q and determined a common region of LOH localized between the markers D16S518 and D16S504. By refining the boundaries of two interstitial LOH and two homozygous deletions, the critical region was delimited to 180 kb between D16S3096 and D16S3029. This region is located in intron 8 of the WWOX/FOR gene, but a search for mutations in all coding exons of this gene in 27 HCC tumors and cell lines did not reveal any tumor somatic alterations. Furthermore, by RT-PCR, no abnormal transcripts of this WWOX/FOR gene was detected in nine HCC cell lines. Finally, analysis of the p53 gene mutations with the clinical parameters of all tumors revealed that the two homozygous deletions have occurred in tumors presenting a R249S mutation. Our data revealed a relationship between chromosome 16q homozygous deletions and R249S p53 mutations in tumors where the patient had been exposed to aflatoxin B1 (P=0.002). These results are consistent with a role of aflatoxin B1 in the instability of chromosome 16q at the fragile site FRA16D. However, the nature of the specific gene that is altered during hepatocarcinogenesis remains to be elucidated.
Asunto(s)
Aflatoxina B1 , Carcinógenos , Carcinoma Hepatocelular/inducido químicamente , Carcinoma Hepatocelular/genética , Deleción Cromosómica , Cromosomas Humanos Par 16 , Homocigoto , Neoplasias Hepáticas/inducido químicamente , Neoplasias Hepáticas/genética , Alelos , Mapeo Cromosómico , Exones , Citometría de Flujo , Genes p53/genética , Genotipo , Humanos , Pérdida de Heterocigocidad , Repeticiones de Microsatélite , Modelos Genéticos , Mutación , ARN Mensajero/metabolismo , Células Tumorales CultivadasRESUMEN
FISH identified a cryptic t(5;14)(q35;q32) in T acute lymphoblastic leukemia (ALL), whereas it was not observed in B ALL samples. This translocation is present in five out of 23 (22%) children and adolescents with T ALL tested. RanBP17, a gene coding for a member of the importin beta protein family, and Hox11Like2, an orphan homeobox gene were mapped close to the chromosome 5 breakpoints and CTIP2, which is highly expressed during normal T cell differentiation, was localized in the vicinity of the chromosome 14 breakpoints. The Hox11L2 gene was found to be transcriptionally activated as a result of the translocation, probably under the influence of CTIP2 transcriptional regulation elements. These data establish the t(5;14)(q35;q32) as a major abnormality, and Hox11 family member activation as an important pathway in T ALL leukemogenesis.
Asunto(s)
Cromosomas Humanos Par 14 , Cromosomas Humanos Par 5 , Proteínas de Homeodominio/genética , Leucemia-Linfoma de Células T del Adulto/genética , Proteínas Oncogénicas/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Translocación Genética/genética , Adolescente , Adulto , Secuencia de Aminoácidos , Estudios de Casos y Controles , Transformación Celular Neoplásica , Niño , Preescolar , Rotura Cromosómica , Análisis Citogenético , Femenino , Humanos , Leucemia-Linfoma de Células T del Adulto/etiología , Masculino , Datos de Secuencia Molecular , Leucemia-Linfoma Linfoblástico de Células Precursoras/etiología , Proteínas Proto-Oncogénicas , Alineación de Secuencia , Proteína de Unión al GTP ran/genéticaRESUMEN
Giant axonal neuropathy (GAN) is a rare autosomal recessive neurodegenerative disorder, characterised clinically by the development of chronic distal polyneuropathy during childhood, mental retardation, kinky or curly hair, skeletal abnormalities and, ultrastructurally, by axons in the central and peripheral nervous systems distended by masses of tightly woven neurofilaments. We recently localised the GAN locus in 16q24.1 to a 5-cM interval between the D16S507 and D16S511 markers by homozygosity mapping in three consanguineous Tunisian families. We have now established a contig-based physical map of the region comprising YACs and BACs where we have placed four genes, ten ESTs, three STSs and two additional microsatellite markers, and where we have identified six new SSCP polymorphisms and six new microsatellite markers. Using these markers, we have refined the position of our previous flanking recombinants. We also identified a shared haplotype between two Tunisian families and a small region of homozygosity in a Turkish family with distant consanguinity, both suggesting the occurrence of historic recombinations and supporting the conclusions based on the phase-known recombinations. Taken together, these results allow us to establish a transcription map of the region, and to narrow down the GAN position to a < 590 kb critical interval, an important step toward the identification of the defective gene.
Asunto(s)
Axones/patología , Huesos/anomalías , Mapeo Contig , Discapacidad Intelectual/genética , Síndrome del Pelo Ensortijado/genética , Enfermedades Neurodegenerativas/genética , Mapeo Cromosómico , Cromosomas Humanos Par 16/genética , Consanguinidad , Cartilla de ADN/química , Femenino , Haplotipos , Homocigoto , Humanos , Discapacidad Intelectual/patología , Desequilibrio de Ligamiento , Masculino , Síndrome del Pelo Ensortijado/patología , Repeticiones de Microsatélite , Enfermedades Neurodegenerativas/patología , Linaje , Mapeo Físico de Cromosoma , Reacción en Cadena de la Polimerasa , Polimorfismo Genético , Polineuropatías/genética , Polineuropatías/patologíaRESUMEN
The HERV-H family is one of the largest human endogenous retrovirus families, with approximately 1000 elements. Using a direct coupled in vitro transcription/translation approach (PTT for protein truncation test) and an extended series of primers on human genomic DNA, on monochromosomal hybrids and on a BAC library, we could demonstrate that there are only three envelopes with a large open reading frame encompassing the immunosuppressive (ISU) domain, corresponding to 62-, 60-, and 59-kDa potential translational products. The associated proviruses, HERV-H/env62, HERV-H/env60, and HERV-H/env59 were sequenced together with their flanking DNA and mapped by FISH, and their entry times within the primate lineage were determined. Analysis of the LTR sequences revealed numerous recombinational and/or homogenization events in the course of evolution, with divergences between 5' and 3' LTRs higher than expected for a simple time-dependent genetic drift. PTT analyses further revealed that the three large envelopes in humans are prematurely stopped in the majority of primates, and sequencing of the largest envelope gene, from HERV-H/env62, in five human individuals revealed two polymorphic sites. The results are consistent with the absence of a strong selective pressure for the conservation of a functional envelope gene of possible benefit for the host, but do not exclude somatic effects possibly associated with the immunosuppressive domain carried by these genes.
Asunto(s)
Retrovirus Endógenos/clasificación , Primates/virología , Provirus/clasificación , Animales , Secuencia de Bases , Evolución Molecular , Genoma Viral , Humanos , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Reacción en Cadena de la Polimerasa , Biosíntesis de Proteínas , Secuencias Repetidas Terminales/genética , Transcripción Genética , Proteínas del Envoltorio Viral/genéticaRESUMEN
We report on the fusion of the monocytic leukemia zinc finger protein (MOZ) gene to the adenoviral E1A-associated protein p300 (p300) gene in acute monocytic leukemia M5 associated with a t(8;22)(p11;q13) translocation. We studied two patients with double-color fluorescence in situ hybridization (FISH) using the yeast artificial chromosome 176C9 and the bacterial artificial chromosome clone H59D10 specific to the MOZ and p300 genes, respectively. Both probes were split in the patients' chromosome metaphase cells, and the two derivative chromosomes were each labeled with both probes. We showed by Southern blot the rearrangement of the MOZ gene, and cloned the fusion transcripts in one patient carrying the t(8;22) by reverse transcription-polymerase chain reaction using MOZ- and p300-specific primers. Both fusion transcripts were expressed. This result defines a novel reciprocal translocation involving two acetyltransferases, MOZ and p300, resulting in an abnormal transcriptional co-activator that could play a critical role in leukemogenesis.
Asunto(s)
Acetiltransferasas/genética , Cromosomas Humanos Par 22/genética , Cromosomas Humanos Par 8/genética , Leucemia Monocítica Aguda/genética , Proteínas Nucleares/genética , Transactivadores/genética , Translocación Genética/genética , Acetiltransferasas/aislamiento & purificación , Secuencia de Aminoácidos , Proteína p300 Asociada a E1A , Reordenamiento Génico , Histona Acetiltransferasas , Humanos , Hibridación Fluorescente in Situ , Leucemia Monocítica Aguda/enzimología , Leucemia Mielomonocítica Crónica/enzimología , Leucemia Mielomonocítica Crónica/genética , Datos de Secuencia Molecular , Proteínas Nucleares/aislamiento & purificación , ARN Mensajero/aislamiento & purificación , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/aislamiento & purificación , Transactivadores/aislamiento & purificación , Células Tumorales CultivadasRESUMEN
SPOCK, previously identified as testican, is a modular proteoglycan that carries both chondroitin and heparan sulfate glycosaminoglycan side chains. The overall genomic organization has been established. The SPOCK gene spans at least 70 kb and is composed of 11 exons: the first half of the gene is dramatically expanded, but the second half is more compact. In situ hybridization and YAC mapping independently linked the SPOCK gene to 5q31, a region containing an impressive number of genes encoding growth factors, cytokines, and neurotransmitter and hormone receptors. The gene is located between the IL9 and the EGR1 genes, bordering the smallest commonly deleted region of chromosome 5.
Asunto(s)
Cromosomas Humanos Par 5 , Proteoglicanos/genética , Bandeo Cromosómico , Mapeo Cromosómico , Cromosomas Artificiales de Levadura , Exones/genética , Biblioteca de Genes , Humanos , Hibridación Fluorescente in SituRESUMEN
We report the cloning of a cDNA encoding human syntaxin 8 (STX8), using the regulator (R) domain of the cystic fibrosis transmembrane conductance regulator (CFTR) as a bait to screen a human fetal lung cDNA library by the yeast two-hybrid system. This gene was found broadly transcribed and its mRNA size is about 1.3 kb. The STX8 gene maps to chromosomal band 17p12 and it encodes a 236-amino-acid protein. Syntaxin 8 contains in its C-terminal half a coiled-coil domain found highly conserved in the t-SNARE (SNAP receptor on target membrane) superfamily of proteins, which are involved in vesicular trafficking and docking. In syntaxin 8, a C-terminal hydrophobic domain may constitute a transmembrane anchor. It was recently shown that CFTR-mediated chloride currents can be regulated by syntaxin 1A, a t-SNARE family member, through direct protein-protein interaction. This raises the possibility that syntaxin 8 may also be involved in such regulations.
Asunto(s)
Cromosomas Humanos Par 17/genética , Expresión Génica , Proteínas de la Membrana/genética , Proteínas de Transporte Vesicular , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Northern Blotting , Mapeo Cromosómico , Clonación Molecular , Secuencia Conservada , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Etiquetas de Secuencia Expresada , Humanos , Pulmón/embriología , Pulmón/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Datos de Secuencia Molecular , Sistemas de Lectura Abierta/genética , Unión Proteica , Estructura Secundaria de Proteína , Proteínas Qa-SNARE , ARN Mensajero/análisis , ARN Mensajero/genética , Proteínas SNARE , Homología de Secuencia de Aminoácido , Sintaxina 1 , Levaduras/genética , Levaduras/metabolismoRESUMEN
The recurrent t(1;22)(p13;q13) translocation is exclusively associated with infant acute megakaryoblastic leukemia. We have identified the two genes involved in this translocation. Both genes possess related sequences in the Drosophila genome. The chromosome 22 gene (megakaryocytic acute leukemia, MAL) product is predicted to be involved in chromatin organization, and the chromosome 1 gene (one twenty-two, OTT) product is related to the Drosophila split-end (spen) family of proteins. Drosophila genetic experiments identified spen as involved in connecting the Raf and Hox pathways. Because almost all of the sequences and all of the identified domains of both OTT and MAL proteins are included in the predicted fusion protein, the OTT-MAL fusion could aberrantly modulate chromatin organization, Hox differentiation pathways, or extracellular signaling.