Autism-associated deletions of the lncRNA PTCHD1-AS result in synaptic dysfunction in human neurons
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ABSTRACT: The long non-coding (lnc) RNA PTCHD1-AS is frequently disrupted in males with autism spectrum disorder (ASD), but its role in neuron function is unknown. We generated induced pluripotent stem (iPS) cells from two ASD subjects with PTCHD1 locus microdeletions, and produced neurons that exhibited reduced miniature excitatory post-synaptic current (mEPSC) frequency and NMDA receptor hypofunction. Mutation of the lncRNA PTCHD1-AS had no impact on expression of the divergently transcribed neighboring PTCHD1 gene in cis, but 14 genes were differentially expressed. Alternative splicing patterns of the nuclear lncRNA were affected by exon 3 loss, and its importance was reinforced by discovery of a novel ASD-associated exon 3 deletion. Finally, genome editing of exon 3 in iPS cells recapitulated diminished mEPSC frequency in neurons. Our findings directly implicate PTCHD1-AS in excitatory synapse function, and reveal the first association of lncRNA deletion with neuronal under-connectivity in ASD.
Project description:The Xp22.11 locus that encompasses PTCHD1, DDX53, and the long noncoding RNA (lncRNA) PTCHD1-AS is frequently disrupted in males with autism spectrum disorder (ASD), but the functional consequences of these genetic risk factors for ASD are unknown. : iPSC-derived neurons from the ASD subjects exhibited reduced miniature excitatory post-synaptic current (mEPSC) frequency and NMDA receptor hypofunction. We found that 35 ASD-associated deletions mapping to the PTCHD1 locus disrupt exons of PTCHD1-AS. We also report a novel ASD-associated deletion of PTCHD1-AS exon 3, and we show exon 3 loss alters PTCHD1-AS splicing without affecting expression of the neighboring PTCHD1 coding gene. Finally, targeted disruption of PTCHD1-AS exon 3 recapitulated diminished mEPSC frequency, supporting a role for the lncRNA in the etiology of ASD. Our genetic findings provide strong evidence that PTCHD1-AS deletions are risk factors for ASD, and human iPSC-derived neurons implicate these deletions in the neurophysiology of excitatory synapses and in ASD-associated synaptic impairment.
Project description:iPS cell lines were generated from a male with ASD (proband or prb) and his unaffected mother (control or ctrl). Both individuals carry X-linked 167kb microdeletions that disrupt both PTCHD1 and PTCHD1-AS. We found that cells PTCHD1/PTCHD1-AS-null cells tended to have abnormal karyotypes. Copy number variation analyses were performed to examine genomic stability in control and proband iPS cell lines.
Project description:Synapse development and neuronal activity represent fundamental processes for the establishment of cognitive function. Structural organization as well as signalling pathways from receptor stimulation to gene expression regulation are mediated by synaptic activity and misregulated in neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability (ID). Deleterious mutations in the PTCHD1 (Patched domain containing 1) gene have been described in male patients with X-linked ID and/or ASD. The structure of PTCHD1 protein is similar to the Patched (PTCH1) receptor; however, the cellular mechanisms and pathways associated with PTCHD1 in the developing brain are poorly determined. Here we show that PTCHD1 displays a C-terminal PDZ-binding motif that binds to the postsynaptic proteins PSD95 and SAP102. We also report that PTCHD1 is unable to rescue the canonical sonic hedgehog (SHH) pathway in cells depleted of PTCH1, suggesting that both proteins are involved in distinct cellular signalling pathways. We find that Ptchd1 deficiency in male mice (Ptchd1-/y) induces global changes in synaptic gene expression, affects the expression of the immediate-early expression genes Egr1 and Npas4 and finally impairs excitatory synaptic structure and neuronal excitatory activity in the hippocampus, leading to cognitive dysfunction, motor disabilities and hyperactivity. Thus our results support that PTCHD1 deficiency induces a neurodevelopmental disorder causing excitatory synaptic dysfunction.
Project description:To investigate whether a SNV in the gene PTCHD1 was disease causative, we introduced the variant to KOLF-2 iPSCs via CRISPR/Cas9 homology directed repair. Three experimentally matched SNV and WT clones and two clones with truncating mutations were generated, and neural induction was induced. We then performed gene expression profiling analysis using data obtained from RNA-seq of these cells at two timepoints (day 0 and day 24 of neural induction).
Project description:MDGA2 is an excitatory synaptic suppressor and its mutations have been associated with autism spectrum disorder (ASD). However, the detailed physiological function of MDGA2 and the mechanism underlying MDGA2 deficiency-caused ASD has yet to be elucidated. Herein, we not only confirm that Mdga2+/- mice exhibit increased excitatory synapse transmission and ASD-like behaviors, but also identify aberrant BDNF/TrkB signaling activation in these mice. We demonstrate that MDGA2 interacts with TrkB through its MAM domain, thereby competing the binding of BDNF to TrkB. Both loss of MDGA2 and the ASD-associated MDGA2 V930I mutation promote the BDNF/TrkB signaling activity. Importantly, we demonstrate that inhibiting the BDNF/TrkB signaling by both small molecular compound and MDGA2-derived peptide can attenuate the increase of AMPA receptor-mediated excitatory synaptic activity and social deficits in MDGA2 deficient mice. These results highlight a novel MDGA2-BDNF/TrkB-dependent mechanism underlying the synaptic function regulation, which may become a therapeutic target for ASD.
Project description:In this study we analyzed the contribution of PHF8 histone demethylase to astrocytes differentiation from mouse neural stem cells. We found that PHF8 depletion affects astocytes differentiation. Moreover, PHF8 is crucial for synaptogenesis in neurons/astrocytes cocultures. Genome wide analysis demonstrated that PHF8 controls the expression of critical astrogenic and synaptogenic genes by keeping low levels of H4K20me1 at promoters. PHF8 depletion induces aberrant astrocytes phenotype and caused a significant decrease in miniature excitatory postsynaptic currents (mEPSC) frequency and amplitude in neurons/astrocytes coclutures. These data reveal a new role of PHF8 in astrocyte differentiation and function, modulating neuronal synapse. Thus, lack of histone demethylase activity associated to PHF8 mutations might led to synapse disfunction that could directly impact into X-linked intellectual disabilities.
Project description:In this study we analyzed the contribution of PHF8 histone demethylase to astrocytes differentiation from mouse neural stem cells. We found that PHF8 depletion affects astocytes differentiation. Moreover, PHF8 is crucial for synaptogenesis in neurons/astrocytes cocultures. Genome wide analysis demonstrated that PHF8 controls the expression of critical astrogenic and synaptogenic genes by keeping low levels of H4K20me1 at promoters. PHF8 depletion induces aberrant astrocytes phenotype and caused a significant decrease in miniature excitatory postsynaptic currents (mEPSC) frequency and amplitude in neurons/astrocytes coclutures. These data reveal a new role of PHF8 in astrocyte differentiation and function, modulating neuronal synapse. Thus, lack of histone demethylase activity associated to PHF8 mutations might led to synapse disfunction that could directly impact into X-linked intellectual disabilities.
Project description:Shank2 is an excitatory postsynaptic scaffolding protein strongly implicated in autism spectrum disorders (ASD). Shank2-mutant mice with a homozygous deletion of exons 6 and 7 show decreased NMDA receptor (NMDAR) functions and autistic-like behaviors in juvenile (~postnatal day or P21) and adult (> P56) stages that are rescued by NMDAR activation. These mice, however, show an opposite change increased NMDAR functions—at ~P14, and NMDAR suppression by early and chronic memantine treatment during P7–21 prevents NMDAR hypofunction and autistic-like behaviors at juvenile (~P21) and adult (~P56) stages. To explore molecular mechanisms underlying the long-lasting effects of early memantine treatment, we performed RNA-Seq analysis of forebrains from wild-type and Shank2-mutant mice early and chronically treated with vehicle or memantine. Memantine-treated Shank2-mutant mice showed upregulations of chromatin-related genes and downregulations of mitochondria- and ribosome-related genes. In addition, vehicle-treated Shank2-mutant mice showed transcriptomic patterns that are largely opposite to those observed in ASD, as supported by the expression patterns of ASD-risk/related genes and cell-type-specific genes. These patterns, likely representing compensatory changes, were weakened by early memantine treatment. These results suggest that early chronic memantine treatment in Shank2-mutant mice alters chromatin- and mitochondria/ribosome-related gene expressions and weakens anti-ASD transcriptomic patterns.
Project description:Williams syndrome (WS), characterized by positive sociality, provides a unique model for studying transcriptional networks underlying social dysfunction, relevant to disorders like autism spectrum disorder (ASD) and schizophrenia (SCHZ). In a cohort lymphoblastoid cell lines derived from 52 individuals (34 WS patients, 18 parental controls), genome-wide exon-level arrays identified a core set of differentially expressed genes (DEGs), with WS-deleted genes ranking among the top transcripts. Findings were validated by PCR, RNA-seq, and western blots. Network analyses revealed perturbed actin cytoskeletal signaling in excitatory dendritic spines, alongside interactions in MAPK, IGF1-PI3K-AKT-mTOR/insulin, and synaptic actin pathways. These transcriptional networks show parallels to ASD and SCHZ, highlighting shared mechanisms across social behavior disorders.