Given the complexity and heterogeneity of the genomic architecture underlying schizophrenia, molecular analyses of these patients with defined and large effect-size genomic defects could provide valuable clues. We established human-induced pluripotent stem cells from two schizophrenia patients with the 22q11.2 deletion (two cell lines from each subject, total of four cell lines) and three controls (total of four cell lines). Neurosphere size, neural differentiation efficiency, neurite outgrowth, cellular migration and the neurogenic-to-gliogenic competence ratio were significantly reduced in patient-derived cells. As an underlying mechanism, we focused on the role of DGCR8, a key gene for microRNA (miRNA) processing and mapped in the deleted region. In mice, Dgcr8 hetero-knockout is known to show a similar phenotype of reduced neurosphere size (Ouchi et al., 2013). The miRNA profiling detected reduced expression levels of miRNAs belonging to miR-17/92 cluster and miR-106a/b in the patient-derived neurospheres. Those miRNAs are reported to target p38α, and conformingly the levels of p38α were upregulated in the patient-derived cells. p38α is known to drive gliogenic differentiation. The inhibition of p38 activity by SB203580 in patient-derived neurospheres partially restored neurogenic competence. Furthermore, we detected elevated expression of GFAP, a gliogenic (astrocyte) marker, in postmortem brains from schizophrenia patients without the 22q11.2 deletion, whereas inflammation markers (IL1B and IL6) remained unchanged. In contrast, a neuronal marker, MAP2 expressions were decreased in schizophrenia brains. These results suggest that a dysregulated balance of neurogenic-to-gliogenic competence may underlie neurodevelopmental disorders such as schizophrenia.

The risk of schizophrenia is increased in offspring whose mothers experience malnutrition during pregnancy. Polyunsaturated fatty acids (PUFAs) are dietary components that are crucial for the structural and functional integrity of neural cells, and PUFA deficiency has been shown to be a risk factor for schizophrenia. Here, we show that gestational and early postnatal dietary deprivation of two PUFAs—arachidonic acid (AA) and docosahexaenoic acid (DHA)—elicited schizophrenia-like phenotypes in mouse offspring at adulthood. In the PUFA-deprived mouse group, we observed lower motivation and higher sensitivity to a hallucinogenic drug resembling the prodromal symptoms in schizophrenia. Furthermore, a working-memory task-evoked hyper-neuronal activity in the medial prefrontal cortex was also observed, along with the downregulation of genes in the prefrontal cortex involved in oligodendrocyte integrity and the gamma-aminobutyric acid (GABA)-ergic system. Regulation of these genes was mediated by the nuclear receptor genes Rxr and Ppar, whose promoters were hyper-methylated by the deprivation of dietary AA and DHA. In addition, the RXR agonist bexarotene upregulated oligodendrocyte- and GABA-related gene expression and suppressed the sensitivity of mice to the hallucinogenic drug. Notably, the expression of these nuclear receptor genes were also downregulated in hair-follicle cells from schizophrenia patients. These results suggest that PUFA deficiency during the early neurodevelopmental period in mice could model the prodromal state of schizophrenia through changes in the epigenetic regulation of nuclear receptor genes.

Betaine is known to act against various biological stresses and its levels were reported to be decreased in schizophrenia patients. We aimed to test the role of betaine in schizophrenia pathophysiology, and to evaluate its potential as a novel psychotherapeutic. Using Chdh (a gene for betaine synthesis)-deficient mice and betaine-supplemented inbred mice, we assessed the role of betaine in psychiatric pathophysiology, and its potential as a novel psychotherapeutic, by leveraging metabolomics, behavioral-, transcriptomics and DNA methylation analyses. The Chdh-deficient mice revealed remnants of psychiatric behaviors along with schizophrenia-related molecular perturbations in the brain. Betaine supplementation elicited genetic background-dependent improvement in cognitive performance, and suppressed methamphetamine (MAP)-induced behavioral sensitization. Furthermore, betaine rectified the altered antioxidative and proinflammatory responses induced by MAP and in vitro phencyclidine (PCP) treatments. Betaine also showed a prophylactic effect on behavioral abnormality induced by PCP. Notably, betaine levels were decreased in the postmortem brains from schizophrenia, and a coexisting elevated carbonyl stress, a form of oxidative stress, demarcated a subset of schizophrenia with "betaine deficit-oxidative stress pathology". We revealed the decrease of betaine levels in glyoxylase 1 (GLO1)-deficient hiPSCs, which shows elevated carbonyl stress, and the efficacy of betaine in alleviating it, thus supporting a causal link between betaine and oxidative stress conditions. Furthermore, a CHDH variant, rs35518479, was identified as a cis-expression quantitative trait locus (QTL) for CHDH expression in postmortem brains from schizophrenia, allowing genotype-based stratification of schizophrenia patients for betaine efficacy. The present study revealed the role of betaine in psychiatric pathophysiology and underscores the potential benefit of betaine in a subset of schizophrenia. FUND: This study was supported by the Strategic Research Program for Brain Sciences from AMED (Japan Agency for Medical Research and Development) under Grant Numbers JP18dm0107083 and JP19dm0107083 (TY), JP18dm0107129 (MM), JP18dm0107086 (YK), JP18dm0107107 (HY), JP18dm0107104 (AK) and JP19dm0107119 (KH), by the Grant-in-Aid for Scientific Research on Innovative Areas from the MEXT under Grant Numbers JP18H05435 (TY), JP18H05433 (AH.-T), JP18H05428 (AH.-T and TY), and JP16H06277 (HY), and by JSPS KAKENHI under Grant Number JP17H01574 (TY). In addition, this study was supported by the Collaborative Research Project of Brain Research Institute, Niigata University under Grant Numbers 2018-2809 (YK) and RIKEN Epigenetics Presidential Fund (100214-201801063606-340120) (TY).

Mice with the C3H background show greater behavioral propensity for schizophrenia, including lower prepulse inhibition (PPI), than C57BL/6 (B6) mice. To characterize as‐yet‐unknown pathophysiologies of schizophrenia, we undertook proteomics analysis of the brain in these strains, and detected elevated levels of Mpst, a hydrogen sulfide (H ₂ S)/polysulfide‐producing enzyme, and greater sulfide deposition in C3H than B6 mice. Mpst ‐deficient mice exhibited improved PPI with reduced storage sulfide levels, while Mpst ‐transgenic (Tg) mice showed deteriorated PPI, suggesting that “sulfide stress” may be linked to PPI impairment. Analysis of human samples demonstrated that the H ₂ S/polysulfides production system is upregulated in schizophrenia. Mechanistically, the Mpst‐ Tg brain revealed dampened energy metabolism, while maternal immune activation model mice showed upregulation of genes for H ₂ S/polysulfides production along with typical antioxidative genes, partly via epigenetic modifications. These results suggest that inflammatory/oxidative insults in early brain development result in upregulated H ₂ S/polysulfides production as an antioxidative response, which in turn cause deficits in bioenergetic processes. Collectively, this study presents a novel aspect of the neurodevelopmental theory for schizophrenia, unraveling a role of excess H ₂ S/polysulfides production.

The conventional practice of using trial and error mode to select antipsychotic drugs in treatment of schizophrenia can result in symptom exacerbations, relapse and severe side effects, resulting in higher costs of treatment. P-glycoprotein (ABCB1) is known to regulate the concentration of antipsychotic drugs in the brain. Variable expressivity based on polymorphism in the gene ABCB1 may reflect on the drug response and its relationship to dosage. All antipsychotic dosages administered to patients were converted to common chlorpromazine equivalents. Response to antipsychotics was based on 50% cutoff in Brief Psychiatric Rating Scale ratings after 1-year of follow-up. Using a case-control study design, ABCB1 polymorphisms were screened in 192 individuals grouped into responders and nonresponders. A strong allelic, genotypic and haplotypic association, was observed, which was predictive of good response to antipsychotics. Individuals carrying the favorable homozygous genotypes of rs1045642 and rs2032582 displayed better response with increased dosage while those carrying risk genotype manifested refractoriness on increased dosage. The study suggests that a priori knowledge of ABCB1 genotypes can provide a significant input into evaluating the patient's response to medication, and minimizing redundant dosing and refractoriness.

The disturbed integrity of myelin and white matter, along with dysregulation of the lipid metabolism, may be involved in schizophrenia pathophysiology. Considering the crucial role of sphingolipids in neurodevelopment, particularly in oligodendrocyte differentiation and myelination, we examined the role of sphingolipid dynamics in the pathophysiology of schizophrenia. We performed targeted mass spectrometry-based analysis of sphingolipids from the cortical area and corpus callosum of postmortem brain samples from patients with schizophrenia and controls. We observed lower sphingosine-1-phosphate (S1P) levels, specifically in the corpus callosum of patients with schizophrenia, but not in major depressive disorder or bipolar disorder, when compared with the controls. Patient data and animal studies showed that antipsychotic intake did not contribute to the lowered S1P levels. We also found that lowered S1P levels in the corpus callosum of patients with schizophrenia may stem from the upregulation of genes for S1P-degrading enzymes; higher expression of genes for S1P receptors suggested a potential compensatory mechanism for the lowered S1P levels. A higher ratio of the sum of sphingosine and ceramide to S1P, which can induce apoptosis and cell-cycle arrest, was also observed in the samples of patients with schizophrenia than in controls. These results suggest that an altered S1P metabolism may underlie the deficits in oligodendrocyte differentiation and myelin formation, leading to the structural and molecular abnormalities of white matter reported in schizophrenia. Our findings may pave the way toward a novel therapeutic strategy.