RESUMEN
Rett syndrome (RTT) is a postnatal neurodevelopmental disorder characterized by the loss of acquired motor and language skills, autistic features, and unusual stereotyped movements. RTT is caused by mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2). Mutations in MECP2 cause a variety of neurodevelopmental disorders including X-linked mental retardation, psychiatric disorders, and some cases of autism. Although MeCP2 was identified as a methylation-dependent transcriptional repressor, transcriptional profiling of RNAs from mice lacking MeCP2 did not reveal significant gene expression changes, suggesting that MeCP2 does not simply function as a global repressor. Changes in expression of a few genes have been observed, but these alterations do not explain the full spectrum of Rett-like phenotypes, raising the possibility that additional MeCP2 functions play a role in pathogenesis. In this study, we show that MeCP2 interacts with the RNA-binding protein Y box-binding protein 1 and regulates splicing of reporter minigenes. Importantly, we found aberrant alternative splicing patterns in a mouse model of RTT. Thus, we uncovered a previously uncharacterized function of MeCP2 that involves regulation of splicing, in addition to its role as a transcriptional repressor.
Asunto(s)
Metilación de ADN , Proteína 2 de Unión a Metil-CpG/metabolismo , Empalme del ARN/genética , Transcripción Genética/genética , Animales , Línea Celular Tumoral , Exones/genética , Perfilación de la Expresión Génica , Genes Reporteros/genética , Humanos , Proteína 2 de Unión a Metil-CpG/genética , Ratones , Modelos Genéticos , Unión Proteica , ARN/genética , Síndrome de Rett/genéticaRESUMEN
Increasing evidence indicates that transcription and pre-mRNA processing are functionally coupled to modulate gene expression. Here, we report that two members of the U2AF65 family of proteins, hCC1.3, which we call CAPERalpha, and a related protein, CAPERbeta, regulate both steroid hormone receptor-mediated transcription and alternative splicing. The CAPER proteins coactivate the progesterone receptor in luciferase transcription reporter assays and alter alternative splicing of a calcitonin/calcitonin gene-related peptide minigene in a hormone-dependent manner. The importance of CAPER coactivators in the regulation of alternative RNA splicing of an endogenous cellular gene (VEGF) was substantiated by siRNA knockdown of CAPERalpha. Mutational analysis of CAPERbeta indicates that the transcriptional and splicing functions are located in distinct and separable domains of the protein. These results indicate that steroid hormone receptor-regulated transcription and pre-mRNA splicing can be directly linked through dual function coactivator molecules such as CAPERalpha and CAPERbeta.
Asunto(s)
Empalme Alternativo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Receptores de Esteroides/genética , Receptores de Esteroides/metabolismo , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Péptido Relacionado con Gen de Calcitonina/genética , Péptido Relacionado con Gen de Calcitonina/metabolismo , Línea Celular , Chlorocebus aethiops , Receptor alfa de Estrógeno/genética , Receptor alfa de Estrógeno/metabolismo , Células HeLa , Humanos , Datos de Secuencia Molecular , Precursores del ARN/genética , Precursores del ARN/metabolismo , ARN Interferente Pequeño/genética , Receptores de Progesterona/genética , Receptores de Progesterona/metabolismo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Factor de Empalme U2AF , Activación Transcripcional , TransfecciónRESUMEN
Three new chlorinated diterpenes, 6-8, along with five known ones, 1-5, were isolated from the molluscs Pleurobranchus albiguttatus and P. forskalii collected in the Philippines. These diterpenes are presumably metabolites of a Lissoclinum species of ascidian on which the molluscs have fed. The structures of the new compounds were determined by interpretation of their spectral data. Compounds 1 and 2 were found to be potent cytotoxins in the National Cancer Institute's screening panel of 60 tumor cell lines and showed some selectivity for melanomas. Two other samples exhibited solid tumor selectivity in a soft agar disk diffusion assay.
