Neonatal Tbr1 Dosage Controls Cortical Layer 6 Connectivity.
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ABSTRACT:
PROVIDER: PRJNA488898 | ENA |
REPOSITORIES: ENA
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Project description:An understanding of how heterozygous loss-of-function mutations in ASD risk genes, such as TBR1, contribute to ASD remains elusive. Conditional Tbr1 deletion during late mouse gestation in cortical layer 6 neurons (Tbr1layer6 mutants) provides novel insights into its function, including dendritic patterning, synaptogenesis, and cell intrinsic physiology. These phenotypes occur in heterozygotes, providing insights into mechanisms that may underlie ASD pathophysiology. Restoring expression of Wnt7b, largely rescues the synaptic deficit in Tbr1layer6 mutant neurons. Furthermore, Tbr1layer6 heterozygotes have increased anxiety-like behavior, a phenotype seen ASD. Integrating TBR1 ChIP-Seq and RNA-Seq data from layer 6 neurons, and activity of TBR1 bound candidate enhancers, provides evidence for how TBR1 regulates layer 6 properties. Moreover, several putative TBR1 targets are ASD risk genes, placing TBR1 in a central position both for ASD risk and for regulating transcriptional circuits that control multiple steps in layer 6 development essential for the assembly of neural circuits.
2018-09-02 | GSE119362 | GEO
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Project description:Exome sequencing studies have identified multiple genes harboring de novo loss-of-function (LoF) variants in individuals with autism spectrum disorders (ASD), including TBR1, a master regulator of cortical development. We performed ChIP-seq for TBR1 during mouse cortical neurogenesis and show that TBR1-bound regions are enriched adjacent to ASD genes. ASD genes were also enriched among genes that are differentially expressed in Tbr1 knockouts, which together with the ChIP-seq data, suggests direct transcriptional regulation. Of the 9 ASD genes examined, 7 were misexpressed in the cortices of Tbr1 knockout mice, including 6 with increased expression in the deep cortical layers. ASD genes with adjacent cortical TBR1 ChIP-seq peaks also showed unusually low levels of LoF mutations in a reference human population and among Icelanders. We then leveraged TBR1 binding to identify an appealing subset of candidate ASD genes. Our findings highlight a TBR1-regulated network of ASD genes in the developing neocortex that are relatively intolerant to LoF mutations, indicating that these genes may play critical roles in normal cortical development.
2016-06-17 | GSE71384 | GEO
Project description:Tbr1 is a high confidence autism spectrum disorder (ASD) gene encoding a transcription factor with distinct pre- and postnatal functions. Postnatally, Tbr1 conditional mutants (CKOs) and constitutive heterozygotes have immature dendritic spines and reduced synaptic density. Tbr1 regulates expression of several genes that underlie synaptic defects, including a kinesin (Kif1a) and a WNT signaling ligand (Wnt7b). Furthermore, Tbr1 mutant corticothalamic neurons have reduced thalamic axonal arborization. LiCl and a GSK3b-inhibitor, two WNT-signaling agonists, robustly rescue the dendritic spines, synaptic and axonal defects, suggesting that this could have relevance for therapeutic approaches in some forms of ASD.
2020-03-04 | GSE146298 | GEO
Project description:Areas and layers of the cerebral cortex are specified by genetic programs that are initiated in progenitor cells and then, implemented in postmitotic neurons. Here, we report that Tbr1, a transcription factor expressed in postmitotic projection neurons, exerts positive and negative control over both regional (areal) and laminar identity. Tbr1 null mice exhibited profound defects of frontal cortex and layer 6 differentiation, as indicated by down-regulation of gene-expression markers such as Bcl6 and Cdh9. Conversely, genes that implement caudal cortex and layer 5 identity, such as Bhlhb5 and Fezf2, were up-regulated in Tbr1 mutants. Tbr1 implements frontal identity in part by direct promoter binding and activation of Auts2, a frontal cortex gene implicated in autism. Tbr1 regulates laminar identity in part by downstream activation or maintenance of Sox5, an important transcription factor controlling neuronal migration and corticofugal axon projections. Similar to Sox5 mutants, Tbr1 mutants exhibit ectopic axon projections to the hypothalamus and cerebral peduncle. Together, our findings show that Tbr1 coordinately regulates regional and laminar identity of postmitotic cortical neurons. Mouse E14.5 neocortices and Postnatal day (P) 0.5 brains: E14.5 neocortices KO, 3; E14.5 neocortices WT, 3; Postnatal day (P) 0.5 brains frontal WT, 4; Postnatal day (P) 0.5 brains frontal KO, 4; Postnatal day (P) 0.5 brains parietal WT, 4; Postnatal day (P) 0.5 brains parietal KO, 4; Postnatal day (P) 0.5 brains occipital WT, 4; Postnatal day (P) 0.5 brains occipital KO, 4.
2010-07-27 | E-GEOD-22371 | biostudies-arrayexpress
Project description:Areas and layers of the cerebral cortex are specified by genetic programs that are initiated in progenitor cells and then, implemented in postmitotic neurons. Here, we report that Tbr1, a transcription factor expressed in postmitotic projection neurons, exerts positive and negative control over both regional (areal) and laminar identity. Tbr1 null mice exhibited profound defects of frontal cortex and layer 6 differentiation, as indicated by down-regulation of gene-expression markers such as Bcl6 and Cdh9. Conversely, genes that implement caudal cortex and layer 5 identity, such as Bhlhb5 and Fezf2, were up-regulated in Tbr1 mutants. Tbr1 implements frontal identity in part by direct promoter binding and activation of Auts2, a frontal cortex gene implicated in autism. Tbr1 regulates laminar identity in part by downstream activation or maintenance of Sox5, an important transcription factor controlling neuronal migration and corticofugal axon projections. Similar to Sox5 mutants, Tbr1 mutants exhibit ectopic axon projections to the hypothalamus and cerebral peduncle. Together, our findings show that Tbr1 coordinately regulates regional and laminar identity of postmitotic cortical neurons.
2010-07-27 | GSE22371 | GEO
Project description:TBR1 is a forebrain specific T-box transcription factor. Tbr1-/- mice have been characterized by defective axonal projections from cerebral cortex and abnormal neuronal migration of cerebral cortex and amygdala. To investigate how TBR1 regulates neural development, the gene expression profile of Tbr1-/- brains was compared with WT littermates. Total RNAs purified from forebrains at embryonic day 16.5 were hybridized on Affymetrix microarrays
2013-12-31 | E-GEOD-49237 | biostudies-arrayexpress
Project description:Noonan syndrome (NS) is a genetic disorder mainly caused by gain-of-function mutations of SHP2. Although diverse neurological manifestations are commonly diagnosed in NS patients, mechanisms on how the SHP2 mutation induces the neurodevelopmental defects remain elusive. Here, we report that cortical organoids (NS-COs) derived from NS-induced pluripotent stem cells (iPSCs) exhibit developmental abnormalities, especially in excitatory neurons (ENs). Although NS-COs normally develop in appearance, single-cell transcriptomic analysis represented increment of EN population and overexpression of cortical layer markers in NS-COs. Surprisingly, EN subpopulation co-expressing upper layer marker SATB2 and deep layer maker CTIP2 was enriched in NS-COs during the cortical development. In parallel with the developmental disruptions, NS-COs also exhibited reduced synaptic connectivity. Collectively, our findings suggest that perturbed cortical layer identity and impeded neuronal connectivity account for the neurological manifestations of NS.
2023-04-24 | GSE213798 | GEO
Project description:TBR1 is a forebrain specific T-box transcription factor. Tbr1-/- mice have been characterized by defective axonal projections from cerebral cortex and abnormal neuronal migration of cerebral cortex and amygdala. To investigate how TBR1 regulates neural development, the gene expression profile of Tbr1-/- brains was compared with WT littermates.
2013-12-31 | GSE49237 | GEO
Project description:Mutations of Tbr1, a high-confidence ASD (autism spectrum disorder)-risk gene encoding the transcription regulator TBR1, in mice have been shown to induce diverse ASD-related molecular, synaptic, neuronal, and behavioral dysfunctions. However, it remains unclear whether Tbr1 mutations derived from autistic individuals cause similar dysfunctions in mice remains unclear. Here we generated and characterized mice carrying the TBR1-K228E de novo mutation identified in human ASD and identified various ASD-related phenotypes. In heterozygous mice carrying this mutation (Tbr1+/K228E mice), the levels of the TBR1-K228E protein, which cannot bind to target DNA, were strongly increased. RNA-Seq analysis of the Tbr1+/K228E embryonic brain indicated significant changes in the expression of genes associated with neurons, astrocytes, ribosomes, neuronal synapses, and ASD risk. The Tbr1+/K228E neocortex displayed abnormal distribution of parvalbumin-positive interneurons, with the density lower in superficial layers but higher in deep layers. This was associated with increased inhibitory synaptic transmission in layer 6 pyramidal neurons, which was resistant to compensation by network activity. Behaviorally, Tbr1+/K228E mice showed decreased social interaction, increased self-grooming, and modestly increased anxiety-like behaviors. These results suggest that the human heterozygous TBR1-K228E mutation induces ASD-related protein, transcriptomic, neuronal, synaptic, and behavioral dysfunctions in mice.
2019-09-29 | GSE134526 | GEO