RESUMO
The chromatin remodeler CHD8 is among the most frequently mutated genes in autism spectrum disorder (ASD). CHD8 has a dosage-sensitive role in ASD, but when and how it becomes critical to human social function is unclear. Here, we conducted genomic analyses of heterozygous and homozygous Chd8 mouse embryonic stem cells and differentiated neural progenitors. We identify dosage-sensitive CHD8 transcriptional targets, sites of regulated accessibility, and an unexpected cooperation with SOX transcription factors. Collectively, our findings reveal that CHD8 negatively regulates expression of neuronal genes to maintain pluripotency and also during differentiation. Thus, CHD8 is essential for both the maintenance of pluripotency and neural differentiation, providing mechanistic insight into its function with potential implications for ASD.
Assuntos
Proteínas de Ligação a DNA , Dosagem de Genes/genética , Neurogênese/genética , Animais , Transtorno do Espectro Autista , Células Cultivadas , Montagem e Desmontagem da Cromatina/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Células-Tronco Embrionárias/metabolismo , Camundongos , Camundongos KnockoutRESUMO
Autism spectrum disorder (ASD) is a heterogeneous disease, but genetically defined models can provide an entry point to studying the molecular underpinnings of this disorder. We generated germline mutant mice with loss-of-function mutations in Chd8, a de novo mutation strongly associated with ASD, and demonstrate that these mice display hallmark ASD behaviors, macrocephaly, and craniofacial abnormalities similar to patient phenotypes. Chd8+/- mice display a broad, brain-region-specific dysregulation of major regulatory and cellular processes, most notably histone and chromatin modification, mRNA and protein processing, Wnt signaling, and cell-cycle regulation. We also find altered synaptic physiology in medium spiny neurons of the nucleus accumbens. Perturbation of Chd8 in adult mice recapitulates improved acquired motor learning behavior found in Chd8+/- animals, suggesting a role for CHD8 in adult striatal circuits. These results support a mechanism linking chromatin modification to striatal dysfunction and the molecular pathology of ASD.
Assuntos
Transtorno do Espectro Autista/genética , Proteínas de Ligação a DNA/genética , Megalencefalia/genética , Animais , Transtorno do Espectro Autista/patologia , Cromatina/genética , Corpo Estriado/patologia , Modelos Animais de Doenças , Regulação da Expressão Gênica no Desenvolvimento , Mutação em Linhagem Germinativa , Histonas/genética , Humanos , Megalencefalia/patologia , Camundongos , Via de Sinalização Wnt/genéticaRESUMO
MicroRNAs (miRNAs) and siRNAs have enormous potential as cancer therapeutics, but their effective delivery to most solid tumors has been difficult. Here, we show that a new lung-targeting nanoparticle is capable of delivering miRNA mimics and siRNAs to lung adenocarcinoma cells in vitro and to tumors in a genetically engineered mouse model of lung cancer based on activation of oncogenic Kirsten rat sarcoma viral oncogene homolog (Kras) and loss of p53 function. Therapeutic delivery of miR-34a, a p53-regulated tumor suppressor miRNA, restored miR-34a levels in lung tumors, specifically down-regulated miR-34a target genes, and slowed tumor growth. The delivery of siRNAs targeting Kras reduced Kras gene expression and MAPK signaling, increased apoptosis, and inhibited tumor growth. The combination of miR-34a and siRNA targeting Kras improved therapeutic responses over those observed with either small RNA alone, leading to tumor regression. Furthermore, nanoparticle-mediated small RNA delivery plus conventional, cisplatin-based chemotherapy prolonged survival in this model compared with chemotherapy alone. These findings demonstrate that RNA combination therapy is possible in an autochthonous model of lung cancer and provide preclinical support for the use of small RNA therapies in patients who have cancer.
Assuntos
Neoplasias Pulmonares/terapia , MicroRNAs/uso terapêutico , RNA Interferente Pequeno/uso terapêutico , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Adenocarcinoma/terapia , Animais , Antineoplásicos/administração & dosagem , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/terapia , Linhagem Celular Tumoral , Cisplatino/administração & dosagem , Terapia Combinada , Expressão Gênica , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Sistema de Sinalização das MAP Quinases , Camundongos , Camundongos Knockout , Camundongos Transgênicos , MicroRNAs/administração & dosagem , MicroRNAs/genética , Mutação , Nanopartículas/administração & dosagem , Nanopartículas/uso terapêutico , Nanotecnologia , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas p21(ras)/genética , RNA Neoplásico/genética , RNA Neoplásico/metabolismo , RNA Interferente Pequeno/administração & dosagem , RNA Interferente Pequeno/genética , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/genética , Proteínas ras/genéticaRESUMO
Cancer cells that express oncogenic alleles of RAS typically require sustained expression of the mutant allele for survival, but the molecular basis of this oncogene dependency remains incompletely understood. To identify genes that can functionally substitute for oncogenic RAS, we systematically expressed 15,294 open reading frames in a human KRAS-dependent colon cancer cell line engineered to express an inducible KRAS-specific shRNA. We found 147 genes that promoted survival upon KRAS suppression. In particular, the transcriptional coactivator YAP1 rescued cell viability in KRAS-dependent cells upon suppression of KRAS and was required for KRAS-induced cell transformation. Acquired resistance to Kras suppression in a Kras-driven murine lung cancer model also involved increased YAP1 signaling. KRAS and YAP1 converge on the transcription factor FOS and activate a transcriptional program involved in regulating the epithelial-mesenchymal transition (EMT). Together, these findings implicate transcriptional regulation of EMT by YAP1 as a significant component of oncogenic RAS signaling.
