Loss of function of FMR2 due to either hypermethylation of the CpG island as a consequence of the expansion of the CCG repeat near its transcription start site, or internal deletion of FMR2 is considered to be the major cause of FRAXE fragile site associated intellectual disability. FMR2 was shown to be a potent transcription activator as well as an RNA binding protein capable of regulating alternative splicing.
Loss of FMR2 further emphasizes the link between deregulation of immediate early response genes FOS and JUN and intellectual disability.
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View SamplesWe identify a brain-specific microRNAmiR-128that represses Nonsense Mediated mRNA Decay (NMD) and thereby controls batteries of transcripts in neural cells. miR-128 represses NMD by targeting the RNA helicase UPF1 and the exon-junction complex core component MLN51. We employed exon arrays for this analysis, as this platform detects expression levels of individual exons and thus allows detection of not only differentially expressed transcripts (DETs), but also alternative isoform transcripts (AITs). The latter is particularly relevant to our study because alternative RNA processing events (e.g., RNA splicing, alternative promoter usage, and alternative polyadenylation-site usage) often place a translation termination codon in a premature context and thereby trigger NMD.
Identification of a microRNA that activates gene expression by repressing nonsense-mediated RNA decay.
Specimen part
View SamplesNonsense-mediated mRNA decay (NMD) surveillance pathways are best known to be involved in the degradation of mRNA with premature termination codons (PTCs). More recent studies demonstrate that the role of NMD pathways goes well beyond the degradation of PTC containing mRNA, into the regulation of cell function and thus normal development.
Transcriptome profiling of UPF3B/NMD-deficient lymphoblastoid cells from patients with various forms of intellectual disability.
Specimen part, Disease, Disease stage, Cell line, Subject
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Transcriptome profiling of UPF3B/NMD-deficient lymphoblastoid cells from patients with various forms of intellectual disability.
Specimen part, Disease, Disease stage, Cell line, Subject
View SamplesYin and yang 1 (YY1) is a well-known zinc-finger transcription factor with crucial roles in normal development and malignancy. YY1 acts both as a repressor and an activator of gene expression. We have identified 23 individuals with de novo mutations or deletions of YY1 and phenotypic features that define a syndrome of cognitive impairment, behavioral alterations, intrauterine growth retardation, feeding problems, and various congenital malformations. Our combined clinical and molecular data define the 'YY1 syndrome' as a haploinsufficiency syndrome. Through immunoprecipitation of YY1-bound chromatin from person-derived cells, using antibodies recognizing both ends of the protein, we show that YY1 deletions and missense mutations lead to a global loss of YY1 binding, with a preferential retention at high-occupancy sites. Finally, we uncover a widespread loss of H3K27 acetylation in particular on the YY1-bound enhancers, underscoring a crucial role for YY1 in enhancer regulation. Collectively, these results define a clinical syndrome caused by haploinsufficiency of YY1 through dysregulation of key transcriptional regulators. Overall design: Individuals with mutations or deletion in YY1 were identified among patients with idiopathic intellectual disability. LCLs were established from 4 of these patients (1 deletion, 2 missense mutations, and 1 non-sense mutation undergoing non-sense-mediated decay) as well as from unrelated controls, and their transcriptome were compared.
YY1 Haploinsufficiency Causes an Intellectual Disability Syndrome Featuring Transcriptional and Chromatin Dysfunction.
Specimen part, Subject
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