Schizophrenia hiPSC neurons display expression changes that are enriched for disease risk variants and a blunted activity-dependent response

Abstract

IMPORTANCESchizophrenia (SCZ) is a common illness with complex genetic architecture where both common genetic variation and rare mutations have been implicated. SCZ candidate genes participate in common molecular pathways that are regulated by activity-dependent changes in neurons, including the signaling network that modulates synaptic strength and the network of genes that are targets of fragile X mental retardation protein. One important next step is to further our understanding on the role of activity-dependent changes of genes expression in the etiopathogenesis of SCZ.\n\nOBJECTIVETo examine whether neuronal activity-dependent changes of gene expression is dysregulated in SCZ.\n\nDESIGN, SETTING, AND PARTICIPANTSNeurons differentiated from human induced pluripotent stem cells (hiPSCs) derived from 4 cases with SCZ and 4 unaffected controls were depolarized using potassium chloride. RNA was extracted followed by genome-wide profiling of the transcriptome.\n\nMAIN OUTCOMES AND MEASURESWe performed differential expression analysis and gene co-expression analysis to identify activity-dependent or disease-specific changes of the transcriptome. Further, we used gene set analyses to identify co-expressed modules that are enriched for SCZ risk genes.\n\nRESULTSWe identified 1,669 genes that are significantly different in SCZ-associated vs. control hiPSC-derived neurons and 1,199 genes that are altered in these cells in response to depolarization. We show that the effect of activity-dependent changes of gene expression in SCZ-associated neurons is attenuated compared to controls. Furthermore, these differentially expressed genes are co-expressed in modules that are highly enriched for genes affected by genetic risk variants in SCZ and other neurodevelopmental disorders.\n\nCONCLUSIONS AND RELEVANCEOur results show that SCZ candidate genes converge to gene networks that are associated with a blunted effect of activity-dependent changes of gene expression in SCZ-associated neurons. Overall, these findings show that hiPSC neurons demonstrate activity-dependent transcriptional changes that can be utilized to examine underlying mechanisms and therapeutic interventions related to SCZ.