ABSTRACT
Evaluation of expression profile in autism spectrum disorder (ASD) patients is an important approach to understand possible similar functional consequences that may underlie disease pathophysiology regardless of its genetic heterogeneity. Induced pluripotent stem cell (iPSC)-derived neuronal models have been useful to explore this question, but larger cohorts and different ASD endophenotypes still need to be investigated. Moreover, whether changes seen in this in vitro model reflect previous findings in ASD postmortem brains and how consistent they are across the studies remain underexplored questions. We examined the transcriptome of iPSC-derived neuronal cells from a normocephalic ASD cohort composed mostly of high-functioning individuals and from non-ASD individuals. ASD patients presented expression dysregulation of a module of co-expressed genes involved in protein synthesis in neuronal progenitor cells (NPC), and a module of genes related to synapse/neurotransmission and a module related to translation in neurons. Proteomic analysis in NPC revealed potential molecular links between the modules dysregulated in NPC and in neurons. Remarkably, the comparison of our results to a series of transcriptome studies revealed that the module related to synapse has been consistently found as upregulated in iPSC-derived neurons-which has an expression profile more closely related to fetal brain-while downregulated in postmortem brain tissue, indicating a reliable association of this network to the disease and suggesting that its dysregulation might occur in different directions across development in ASD individuals. Therefore, the expression pattern of this network might be used as biomarker for ASD and should be experimentally explored as a therapeutic target.
Subject(s)
Autism Spectrum Disorder , Induced Pluripotent Stem Cells , Autism Spectrum Disorder/genetics , Humans , Neurons , Proteomics , Transcriptome/geneticsSubject(s)
Autism Spectrum Disorder/pathology , Gene Expression Regulation/physiology , Multipotent Stem Cells/metabolism , Multiprotein Complexes/metabolism , Signal Transduction/physiology , TOR Serine-Threonine Kinases/metabolism , Androstadienes/pharmacology , Case-Control Studies , Cell Differentiation/drug effects , Cell Proliferation/drug effects , Cells, Cultured , Child , Culture Media, Serum-Free/pharmacology , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Gene Expression Regulation/drug effects , Humans , Immunosuppressive Agents/pharmacology , Male , Mechanistic Target of Rapamycin Complex 1 , Multipotent Stem Cells/drug effects , Phosphorylation/drug effects , Serum/metabolism , Signal Transduction/drug effects , Sirolimus/pharmacology , Time Factors , WortmanninABSTRACT
An increasing number of genetic variants have been implicated in autism spectrum disorders (ASDs), and the functional study of such variants will be critical for the elucidation of autism pathophysiology. Here, we report a de novo balanced translocation disruption of TRPC6, a cation channel, in a non-syndromic autistic individual. Using multiple models, such as dental pulp cells, induced pluripotent stem cell (iPSC)-derived neuronal cells and mouse models, we demonstrate that TRPC6 reduction or haploinsufficiency leads to altered neuronal development, morphology and function. The observed neuronal phenotypes could then be rescued by TRPC6 complementation and by treatment with insulin-like growth factor-1 or hyperforin, a TRPC6-specific agonist, suggesting that ASD individuals with alterations in this pathway may benefit from these drugs. We also demonstrate that methyl CpG binding protein-2 (MeCP2) levels affect TRPC6 expression. Mutations in MeCP2 cause Rett syndrome, revealing common pathways among ASDs. Genetic sequencing of TRPC6 in 1041 ASD individuals and 2872 controls revealed significantly more nonsynonymous mutations in the ASD population, and identified loss-of-function mutations with incomplete penetrance in two patients. Taken together, these findings suggest that TRPC6 is a novel predisposing gene for ASD that may act in a multiple-hit model. This is the first study to use iPSC-derived human neurons to model non-syndromic ASD and illustrate the potential of modeling genetically complex sporadic diseases using such cells.
Subject(s)
Autistic Disorder/pathology , Neurons/pathology , TRPC Cation Channels/metabolism , Animals , Antineoplastic Combined Chemotherapy Protocols/metabolism , Autistic Disorder/genetics , Autistic Disorder/physiopathology , Carboplatin/metabolism , Cell Differentiation/genetics , Cell Line , Cell Proliferation/genetics , Cells, Cultured , Child , Disease Models, Animal , Embryo, Mammalian , Etoposide/metabolism , Gene Expression Regulation/genetics , Humans , In Vitro Techniques , Induced Pluripotent Stem Cells/physiology , Inhibitory Postsynaptic Potentials/genetics , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Mitoxantrone/metabolism , Mutation/genetics , Neurons/metabolism , Prednisolone/metabolism , Signal Transduction/genetics , TRPC Cation Channels/genetics , TRPC6 Cation ChannelABSTRACT
Autism spectrum disorders (ASD) is a group of behaviorally defined neurodevelopmental disabilities characterized by multiple genetic etiologies and a complex presentation. Several studies suggest the involvement of the serotonin system in the development of ASD, but only few have investigated serotonin receptors. We have performed a case-control and a family-based study with 9 polymorphisms mapped to two serotonin receptor genes (HTR1B and HTR2C) in 252 Brazilian male ASD patients of European ancestry. These analyses showed evidence of undertransmission of the HTR1B haplotypes containing alleles -161G and -261A at HTR1B gene to ASD (P=0.003), but no involvement of HTR2C to the predisposition to this disease. Considering the relatively low level of statistical significance and the power of our sample, further studies are required to confirm the association of these serotonin-related genes and ASD.
