RESUMO
The last decade has proven that amyotrophic lateral sclerosis (ALS) is clinically and genetically heterogeneous, and that the genetic component in sporadic cases might be stronger than expected. This study investigates 1,200 patients to revisit ALS in the ethnically heterogeneous yet inbred Turkish population. Familial ALS (fALS) accounts for 20% of our cases. The rates of consanguinity are 30% in fALS and 23% in sporadic ALS (sALS). Major ALS genes explained the disease cause in only 35% of fALS, as compared with ~70% in Europe and North America. Whole exome sequencing resulted in a discovery rate of 42% (53/127). Whole genome analyses in 623 sALS cases and 142 population controls, sequenced within Project MinE, revealed well-established fALS gene variants, solidifying the concept of incomplete penetrance in ALS. Genome-wide association studies (GWAS) with whole genome sequencing data did not indicate a new risk locus. Coupling GWAS with a coexpression network of disease-associated candidates, points to a significant enrichment for cell cycle- and division-related genes. Within this network, literature text-mining highlights DECR1, ATL1, HDAC2, GEMIN4, and HNRNPA3 as important genes. Finally, information on ALS-related gene variants in the Turkish cohort sequenced within Project MinE was compiled in the GeNDAL variant browser (www.gendal.org).
Assuntos
Esclerose Lateral Amiotrófica/genética , Bases de Dados Genéticas , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Internet , Fenótipo , Turquia , Sequenciamento Completo do GenomaRESUMO
Wnt/ß-catenin signalling pathway plays important roles in embryonic development and carcinogenesis. Overactivation of the pathway is one of the most common driving forces in major cancers such as colorectal and breast cancers. The downstream effectors of the pathway and its regulation of carcinogenesis and metastasis are still not very well understood. In this study, which was based on two genome-wide transcriptomics screens, we identify MENA (ENAH, Mammalian enabled homologue) as a novel transcriptional target of the Wnt/ß-catenin signalling pathway. We show that the expression of MENA is upregulated upon overexpression of degradation-resistant ß-catenin. Promoters of all mammalian MENA homologues contain putative binding sites for Tcf4 transcription factor--the primary effector of the Wnt/ß-catenin pathway and we demonstrate functionality of these Tcf4-binding sites using luciferase reporter assays and overexpression of ß-catenin, Tcf4 and dominant-negative Tcf4. In addition, lithium chloride-mediated inhibition of GSK3ß also resulted in increase in MENA mRNA levels. Chromatin immunoprecipitation showed direct interaction between ß-catenin and MENA promoter in Huh7 and HEK293 cells and also in mouse brain and liver tissues. Moreover, overexpression of Wnt1 and Wnt3a ligands increased MENA mRNA levels. Additionally, knock-down of MENA ortholog in D. melanogaster eyeful and sensitized eye cancer fly models resulted in increased tumor and metastasis formations. In summary, our study identifies MENA as novel nexus for the Wnt/ß-catenin and the Notch signalling cascades.
Assuntos
Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Ativação Transcricional , Proteínas Wnt/genética , Proteínas Wnt/metabolismo , beta Catenina/genética , beta Catenina/metabolismo , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Sítios de Ligação , Linhagem Celular Transformada , Imunoprecipitação da Cromatina/métodos , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Drosophila , Quinase 3 da Glicogênio Sintase/genética , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Células HEK293 , Humanos , Ligantes , Luciferases/genética , Luciferases/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Regiões Promotoras Genéticas , RNA Mensageiro/genética , Transdução de Sinais , Fator de Transcrição 4 , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcrição Gênica , Regulação para CimaRESUMO
The Wnt signaling pathway is involved in many differentiation events during embryonic development and can lead to tumor formation after aberrant activation of its components. beta-catenin, a cytoplasmic component, plays a major role in the transduction of canonical Wnt signaling. The aim of this study was to identify novel genes that are regulated by active beta-catenin/TCF signaling in hepatocellular carcinoma-derived Huh7 cells with high (transfected) and low beta-catenin/TCF activities. High TCF activity Huh7 cells led to earlier and larger tumor formation when xenografted into nude mice. SAGE (Serial Analysis of Gene Expression), genome-wide microarray and in silico promoter analysis were performed in parallel, to compare gene expression between low and high beta-catenin/TCF activity clones, and also those that had been rescued from the xenograft tumors. SAGE and genome-wide microarray data were compared and contrasted. BRI3 and HSF2 were identified as novel targets of Wnt/beta-catenin signaling after combined analysis and confirming experiments including qRT-PCR, ChIP, luciferase assay and lithium treatment.