RESUMEN
Chromodomain helicase DNA-binding (CHD) chromatin remodelers regulate transcription and DNA repair. They govern cell-fate decisions during embryonic development and are often deregulated in human pathologies. Chd1-8 show upon germline disruption pronounced, often developmental lethal phenotypes. Here we show that contrary to Chd1-8 disruption, Chd9-/-animals are viable, fertile and display no developmental defects or disease predisposition. Germline deletion of Chd9 only moderately affects gene expression in tissues and derived cells, whereas acute depletion in human cancer cells elicits more robust changes suggesting that CHD9 is a highly context-dependent chromatin regulator that, surprisingly, is dispensable for mouse development.
Asunto(s)
ADN Helicasas/genética , Transactivadores/genética , Animales , Línea Celular , Células Cultivadas , Cromatina/metabolismo , Ensamble y Desensamble de Cromatina , Desarrollo Embrionario , Regulación del Desarrollo de la Expresión Génica , Técnicas de Inactivación de Genes , Mutación de Línea Germinal , Humanos , Células K562 , Ratones , Células Madre Embrionarias de Ratones/citologíaRESUMEN
Cdkn2ab knockout mice, generated from 129P2 ES cells develop skin carcinomas. Here we show that the incidence of these carcinomas drops gradually in the course of backcrossing to the FVB/N background. Microsatellite analyses indicate that this cancer phenotype is linked to a 20 Mb region of 129P2 chromosome 15 harboring the Wnt7b gene, which is preferentially expressed from the 129P2 allele in skin carcinomas and derived cell lines. ChIPseq analysis shows enrichment of H3K27-Ac, a mark for active enhancers, in the 5' region of the Wnt7b 129P2 gene. The Wnt7b 129P2 allele appears sufficient to cause in vitro transformation of Cdkn2ab-deficient cell lines primarily through CDK6 activation. These results point to a critical role of the Cdkn2ab locus in keeping the oncogenic potential of physiological levels of WNT signaling in check and illustrate that GWAS-based searches for cancer predisposing allelic variants can be enhanced by including defined somatically acquired lesions as an additional input.
Asunto(s)
Carcinogénesis/genética , Inhibidor p15 de las Quinasas Dependientes de la Ciclina/deficiencia , Inhibidor p16 de la Quinasa Dependiente de Ciclina/deficiencia , Variación Genética , Neoplasias Cutáneas/genética , Vía de Señalización Wnt/genética , Alelos , Animales , Emparejamiento Base/genética , Línea Celular Tumoral , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Cromosomas de los Mamíferos/genética , Quinasa 6 Dependiente de la Ciclina/metabolismo , Inhibidor p15 de las Quinasas Dependientes de la Ciclina/metabolismo , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Fibroblastos/metabolismo , Ligamiento Genético , Pulmón/patología , Metaplasia , Ratones Noqueados , Factor de Crecimiento Derivado de Plaquetas/metabolismoRESUMEN
Yeast artificial chromosomes (YACs) that contain human DNA backbone undergo DNA double-strand breaks (DSBs) and recombination during yeast meiosis at rates similar to the yeast native chromosomes. Surprisingly, YACs containing DNA covering a recombination hot spot in the mouse major histocompatibility complex class III region do not show meiotic DSBs and undergo meiotic recombination at reduced levels. Moreover, segregation of these YACs during meiosis is seriously compromised. In meiotic yeast cells carrying the mutations sir2 or sir4, but not sir3, these YACs show DSBs, suggesting that a unique chromatin structure of the YACs, involving Sir2 and Sir4, protects the YACs from the meiotic recombination machinery. We speculate that the paucity of DSBs and recombination events on these YACs during yeast meiosis may reflect the refractory nature of the corresponding region in the mouse genome.
