RESUMEN
The p73 protein, a homologue of the tumour-suppressor protein p53, can activate p53-responsive promoters and induce apoptosis in p53-deficient cells. Here we report that some tumour-derived p53 mutants can bind to and inactivate p73. The binding of such mutants is influenced by whether TP53 (encoding p53) codon 72, by virtue of a common polymorphism in the human population, encodes Arg or Pro. The ability of mutant p53 to bind p73, neutralize p73-induced apoptosis and transform cells in cooperation with EJ-Ras was enhanced when codon 72 encoded Arg. We found that the Arg-containing allele was preferentially mutated and retained in squamous cell tumours arising in Arg/Pro germline heterozygotes. Thus, inactivation of p53 family members may contribute to the biological properties of a subset of p53 mutants, and a polymorphic residue within p53 affects mutant behaviour.
Asunto(s)
Mutagénesis Sitio-Dirigida , Polimorfismo Genético , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Alelos , Arginina/genética , Carcinoma de Células Escamosas/genética , Línea Celular , Codón/genética , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/fisiología , Genes Supresores de Tumor , Genes p53 , Tamización de Portadores Genéticos , Mutación de Línea Germinal , Humanos , Sustancias Macromoleculares , Proteínas Nucleares/antagonistas & inhibidores , Proteínas Nucleares/metabolismo , Proteínas Nucleares/fisiología , Prolina/genética , Unión Proteica/genética , Conformación Proteica , Células Tumorales Cultivadas , Proteína Tumoral p73 , Proteína p53 Supresora de Tumor/fisiología , Proteínas Supresoras de TumorRESUMEN
The Alu repeat sequence is estimated to account for 5% of human genomic DNA. The precise relationship of Alu sequences to human fully spliced cDNA has yet to be determined, although many new protocols for cloning cDNAs either depend on the presence of Alus or--more usually--rely on their absence in a population of messages. Previous estimates of the percentage of fully spliced human transcripts that contain Alu repeats have relied on hybridization procedures. Here we have gone directly to the DNA sequence by extracting over 1600 entries from GenBank that are described as human complete cDNAs, and we have assessed the frequency with which the Alu repeat sequence occurs in these sequences. We find that 5% of fully spliced human cDNAs contain Alu sequences. In addition, we have quantified the appearance of Alus in the different cDNA regions, 5' untranslated region (UTR), coding region, and 3' UTR. The vast majority of Alus are found in the 3' UTR, but 14% lie in the 5' UTR, and very rarely an Alu sequence is present within, or partially within, the coding region of the transcript.
Asunto(s)
ADN Complementario/genética , Secuencias Repetitivas de Ácidos Nucleicos , Bases de Datos Factuales , Genoma Humano , Humanos , Biosíntesis de ProteínasRESUMEN
We have mapped GRB2, a signal transduction gene whose protein product is an essential component of the pathway between tyrosine kinases (such as the epidermal growth factor receptor) and downstream proteins (such as Ras and Sos). We assigned GRB2 to human chromosome 17 by hybridization to a somatic cell hybrid mapping panel. To position the locus at a much finer resolution, we have isolated the human GRB2 gene in three different cosmids, which we have mapped by fluorescence in situ hybridization to the long arm of human chromosome 17 (17q24-q25). We have hybridized a human GRB2 open reading frame probe to mouse DNAs from the European Interspecific Backcross. The segregation patterns reveal that the mouse Grb2 locus maps distally on chromosome 11, and an additional Grb2-related locus is present on chromosome 4 of one of the parental strains, Mus spretus/CRC.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales , Cromosomas Humanos Par 17 , Ratones/genética , Proteínas/genética , Transducción de Señal/genética , Animales , Secuencia de Bases , Mapeo Cromosómico , Cósmidos , Cricetinae , Cricetulus , Cruzamientos Genéticos , Proteína Adaptadora GRB2 , Humanos , Hibridación Fluorescente in Situ , Datos de Secuencia Molecular , Muridae/genética , Sistemas de Lectura Abierta , Especificidad de la EspecieRESUMEN
We have mapped the PLCG2 gene, which encodes the enzyme phosphatidyl inositol-specific phospholipase C-gamma 2. This is one of the phospholipases responsible for catalyzing the hydrolysis of phosphatidyl inositol in response to a great many mitogenic stimuli. PL C-gamma 2 is an essential component of the signal transduction pathway between tyrosine kinases and downstream events such as protein kinase C activation and intracellular calcium release. We assigned PLCG2 to human chromosome 16 by amplification within a somatic cell hybrid mapping panel. To position the locus at a much finer resolution, PLCG2 sequences were amplified from a chromosome 16-specific somatic cell hybrid panel, which placed the gene on the long arm of the chromosome in band 16q24.1, a region that has few known genes. We have hybridized a mouse Plcg2 open reading frame probe to mouse DNAs from the European Interspecific Backcross. The segregation pattern reveals the mouse Plcg2 locus maps to distal chromosome 8.
Asunto(s)
Mapeo Cromosómico , Hidrolasas Diéster Fosfóricas/genética , Animales , Secuencia de Bases , Cromosomas Humanos Par 16 , Cruzamientos Genéticos , Cartilla de ADN/genética , ADN Complementario/genética , Femenino , Humanos , Células Híbridas , Masculino , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Muridae , Fosfatidilinositol Diacilglicerol-Liasa , Fosfoinositido Fosfolipasa CRESUMEN
The SHC gene encodes a protein that is thought to act as an adapter in many signal transduction pathways; the SHC protein probably facilitates the activation of RAS proteins in response to a variety of factors. We have mapped the human SHC gene and have identified a new SHC-related sequence. We have sequenced the region corresponding to the SHC 3' UTR from both loci and have mapped cosmids by fluorescence in situ hybridization. The human SHC gene maps to the proximal long arm of chromosome 1 and the SHC-related sequence maps to the proximal long arm of chromosome 17. A number of cancers have been positioned in the proximal long arm of chromosome 1; this is of interest given the oncogenic potential of the SHC protein.
Asunto(s)
Cromosomas Humanos Par 17/genética , Cromosomas Humanos Par 1/genética , Proteínas/genética , Secuencia de Bases , Mapeo Cromosómico , Cósmidos , Humanos , Hibridación Fluorescente in Situ , Datos de Secuencia Molecular , Análisis de Secuencia de ADN , Homología de Secuencia de Ácido NucleicoRESUMEN
To understand the architecture of the human genome, we need a complete definition of all the repeat sequence families, as these make up the majority of human DNA. We have isolated a small DNA fragment from human chromosome 21 and have used sequence analysis of this fragment to uncover a new low copy repeat element of approximately 300 bp that we term the Mermaid repeat. This repeat is related to, but is different from, the MER12 repeat and is interspersed in the genome. Mermaid family members that we have studied are between 81%-87% identical to our preliminary consensus sequence. Therefore, we have added a new member to the large collection of human repetitive elements. In addition, we have mapped a Mermaid repeat to a telomeric position on the long arm of human chromosome 21, at 21q22.3.
Asunto(s)
Cromosomas Humanos Par 21 , Genoma Humano , Secuencias Repetitivas de Ácidos Nucleicos , Secuencia de Bases , Southern Blotting , Mapeo Cromosómico , Clonación Molecular , ADN/genética , Sondas de ADN , ADN Complementario , Humanos , Datos de Secuencia Molecular , Homología de Secuencia de Ácido NucleicoRESUMEN
To access a wide a variety of expressed sequence from human chromosome 21 we have placed this chromosome into undifferentiated P19 mouse embryonic carcinoma cells. Cell lines resulting from these experiments have a range of morphologies and a wide variety of karyotypes. We have studied the retinoic acid response of five cell lines, compared to P19 cells, by observing three markers of retinoic acid induced P19 differentiation--cell morphology, RAR alpha and Wnt1 transcription. We see an 'early' retinoic acid response effect, however this response breaks down by the time the 'late' gene. Wnt1 would be transcribed in P19 cells. A highly responsive cell line will be useful for cloning expressed sequences from human chromosome 21 which are produced by early genes in retinoic acid inducible pathways, such as those involved in neurogenesis.