Project description:Recent studies have revealed an essential role for embryonic cortical development in the pathophysiology of neurodevelopmental disorders, including autism spectrum disorder (ASD). However, the genetic basis and underlying mechanisms remain unclear. Here, we generate mutant human embryonic stem cell lines (Mut hESCs) carrying an NR2F1-R112K mutation that has been identified in a patient with ASD features, and investigate their neurodevelopmental alterations. Mut hESCs overproduce ventral telencephalic neuron progenitors (ventral NPCs) and inhibitory neurons, and underproduce dorsal NPCs and excitatory neurons. These alterations can be mainly attributed to the aberrantly activated Hedgehog signaling pathway. Moreover, the corresponding Nr2f1 point mutant mice display a similar excitatory/inhibitory neuron imbalance and abnormal behaviors. Antagonizing the increased inhibitory synaptic transmission partially alleviates their behavioral deficits. Together, our results suggest that the NR2F1-dependent imbalance of excitatory/inhibitory neuron differentiation caused by the activated Hedgehog pathway is one precursor of neurodevelopmental disorders and may enlighten the therapeutic approaches.
Project description:Recent studies have revealed an essential role for embryonic cortical development in the pathophysiology of neurodevelopmental disorders, including autism spectrum disorder (ASD). However, the genetic basis and underlying mechanisms remain unclear. Here, we generate mutant human embryonic stem cell lines (Mut hESCs) carrying an NR2F1-R112K mutation that has been identified in a patient with ASD features, and investigate their neurodevelopmental alterations. Mut hESCs overproduce ventral telencephalic neuron progenitors (ventral NPCs) and inhibitory neurons, and underproduce dorsal NPCs and excitatory neurons. These alterations can be mainly attributed to the aberrantly activated Hedgehog signaling pathway. Moreover, the corresponding Nr2f1 point mutant mice display a similar excitatory/inhibitory neuron imbalance and abnormal behaviors. Antagonizing the increased inhibitory synaptic transmission partially alleviates their behavioral deficits. Together, our results suggest that the NR2F1-dependent imbalance of excitatory/inhibitory neuron differentiation caused by the activated Hedgehog pathway is one precursor of neurodevelopmental disorders and may enlighten the therapeutic approaches.
Project description:Aneuploidy is a major source of gene dosage imbalance due to copy number alterations (CNA) and viable human trisomies are model disorders of altered gene expression. We studied gene and allele specific expression (ASE) of 9668 single-cell fibroblasts from T21 discordant twins and from mosaic T21, T18, T13 and T8. We examined 928 single cells with deep scRNAseq. Expected and observed overexpression of trisomic genes in trisomic vs. diploid bulk RNAseq was not detectable in trisomic vs. diploid single cells. Instead, for trisomic genes with low-to-average expression, their altered gene dosage was mainly due to the higher fraction of trisomic cells simultaneously expressing these genes, in agreement with a stochastic 2-state burst-like model of transcription. These results, confirmed in a further analysis of 8740 single fibroblasts, suggest that the specific transcriptional profile of each gene contributes to the phenotypic variability of trisomies. We propose an improved model to understand the effects of CNA and, more generally, of gene regulation on gene dosage imbalance.
Project description:Genomic imbalance caused by varying the dosage of individual chromosomes or chromosomal segments (aneuploidy) has more detrimental effects than altering the dosage of complete chromosome sets (ploidy). Previous analysis on RNA-sequencing data of varied dosage of various chromosomal regions in maize (Zea mays) revealed global modulation of gene expression both on the varied chromosome (cis) and the remainder of the genome (trans). Dysregulation of microRNA (miRNA) dosage has been reported to have profound deleterious effects in many species. miRNAs are preferentially retained as duplicates following whole-genome duplication in grass species and are postulated to be dosage-sensitive. However, little is known regarding the role of miRNAs under genomic imbalance. We examined the impact of increased and/or decreased dosage of 1 interstitial and 19 distal chromosomal regions in concert with a whole-genome ploidy series of haploid, diploid, triploid, and tetraploid via small RNA-sequencing of diploid and haploid maize mature leaf tissue to investigate the impact of aneuploidy and polyploidy on expression of miRNAs. In general, cis miRNAs in aneuploids present a predominant gene-dosage effect, whereas trans miRNAs trend toward the inverse level, although other types of responses including dosage compensation, increased effect, and decreased effect also occur. Significant correlations between expression levels of miRNAs and their targets were identified in aneuploids, indicating the regulatory role of miRNAs on gene expression triggered by genomic imbalance. The findings provide novel insights into understanding of gene balance from the aspect of the function of miRNAs.