Reduced protein synthesis in schizophrenia patient-derived olfactory cells.
Human olfactory neurosphere-derived (ONS) cells have the potential to provide novel insights into the cellular pathology of schizophrenia. We used discovery-based proteomics and targeted functional analyses to reveal reductions in 17 ribosomal proteins, with an 18% decrease in the total ribosomal signal intensity in schizophrenia-patient-derived ONS cells. We quantified the rates of global protein synthesis in vitro and found a significant reduction in the rate of protein synthesis in schizophrenia patient-derived ONS cells compared with control-derived cells. Protein synthesis rates in fibroblast cell lines from the same patients did not differ, suggesting cell type-specific effects. Pathway analysis of dysregulated proteomic and transcriptomic data sets from these ONS cells converged to highlight perturbation of the eIF2α, eIF4 and mammalian target of rapamycin (mTOR) translational control pathways, and these pathways were also implicated in an independent induced pluripotent stem cell-derived neural stem model, and cohort, of schizophrenia patients. Analysis in schizophrenia genome-wide association data from the Psychiatric Genetics Consortium specifically implicated eIF2α regulatory kinase EIF2AK2, and confirmed the importance of the eIF2α, eIF4 and mTOR translational control pathways at the level of the genome. Thus, we integrated data from proteomic, transcriptomic, and functional assays from schizophrenia patient-derived ONS cells with genomics data to implicate dysregulated protein synthesis for the first time in schizophrenia.