Yutaka Nakachi

Schizophrenia is a severe neurodevelopmental disorder whose etiology remains incompletely understood. Epidemiological studies of the Dutch Hunger Winter demonstrated that maternal famine during early gestation increased the risk of schizophrenia in offspring, implicating the Developmental Origins of Health and Disease (DOHaD) framework. However, the molecular mechanisms underlying this association remain unclear. Here, we developed a novel DOHaD-based schizophrenia model by subjecting pregnant mice to transient fasting restricted to the peri-implantation period, a critical window of global epigenomic reprogramming. Male offspring of fasted dams exhibited schizophrenia-related phenotypes, including impaired sensorimotor gating, abnormal behavioral patterns, and reduced dendritic spine density in the medial prefrontal cortex. Multi-omics profiling, integrating bulk RNA sequencing, Visium HD spatial transcriptomics, and DNA methylation arrays, revealed convergent alterations in synaptic organization, protein homeostasis, and oxidative stress pathways. These findings highlight how brief maternal fasting reprograms the epigenome and reshapes neural circuitry. Our work establishes the first animal model that directly mirrors early gestational famine exposure linked to schizophrenia risk, providing a unique platform for uncovering epigenetic mechanisms underlying the developmental origins of psychiatric disorders.

Major depression (MD) is caused by both genetic and environmental factors. Epigenetic mechanisms, particularly DNA methylation (5mC) and hydroxymethylation (5hmC), are thought to mediate gene - environment interactions. However, findings in mouse models remain dispersed. This review evaluates the studies on 5mC and 5hmC in mouse models of depression. We systematically searched PubMed, Scopus, and Web of Science using terms related to 5mC/5hmC, depression, and mouse, until December 2024. We grouped the articles as candidate, global, cellular, and comprehensive studies and summarized the findings accordingly. Sixty-eight studies met inclusion criteria. The main findings were environmental models, especially chronic stress paradigms, which were most frequently used to induce depression models. Candidate gene studies focused on Bdnf and Nr3c1, while global and cellular assays revealed both regional and widespread 5mC/5hmC changes. Genome-wide approaches revealed that epigenetic changes are not limited to isolated loci rather affect broad genomic regions involved in neural development and plasticity. This review provides a comprehensive summary of existing research on epigenetic changes in terms of DNA methylation in mouse models of depression. Broader application of standardized, integrative, and cell-type-specific approaches is needed to fully elucidate the role of epigenetic regulation in the pathology of MD.

Retrotransposon long interspersed nuclear element-1 (LINE-1, L1) constitutes a large proportion of the mammalian genome. A fraction of L1s, which have no deleterious mutations in the structure, can amplify their copies via a process called retrotransposition (RT). RT affects genome stability and gene expression and is involved in the pathogenesis of many hereditary diseases. Measuring expression of RT-capable L1s (rc-L1s) among the hundreds of thousands of non rc-L1s is an essential step to understand the impact of RT. We developed mobile element-originated read enrichment from RNA-seq data (MORE-RNAseq), a pipeline for calculating expression of rc-L1s using manually curated L1 references in humans and mice. MORE-RNAseq allows for quantification of expression levels of overall (sum of the expression of all rc-L1s) and individual rc-L1s with consideration of the genomic context. We applied MORE-RNAseq to publicly available RNA-seq data of human and mouse cancer cell lines from the studies that reported increased L1 expression. We found the significant increase of rc-L1 expressions at the overall level in both inter- and intragenic contexts. We also identified differentially expressed rc-L1s at the locus level, which will be the important candidates for downstream analysis. We also applied our method to young and aged human muscle RNA-seq data with no prior information about L1 expression, and found a significant increase of rc-L1 expression in the aged samples. Our method will contribute to understand the role of rc-L1s in various physiological and pathophysiological conditions using standard RNA-seq data. All scripts are available at https://github.com/molbrain/MORE-RNAseq.

Recent epigenetic age studies suggested accelerated aging in schizophrenia. Although antipsychotics may modulate epigenetic age, direct estimation of their roles was impeded when tissues derived from patients were used for analysis. By using a cellular model, we found that antipsychotics generally worked as epigenetic age regulators in vitro.

Bipolar disorder (BD) is a severe psychiatric disorder characterized by repeated conflicting manic and depressive states. In addition to genetic factors, complex gene–environment interactions, which alter the epigenetic status in the brain, contribute to the etiology and pathophysiology of BD. Here, we performed a promoter-wide DNA methylation analysis of neurons and nonneurons derived from the frontal cortices of mutant Polg1 transgenic (n = 6) and wild-type mice (n = 6). The mutant mice expressed a proofreading-deficient mitochondrial DNA (mtDNA) polymerase under the neuron-specific CamK2a promoter and showed BD-like behavioral abnormalities, such as activity changes and altered circadian rhythms. We identified a total of 469 differentially methylated regions (DMRs), consisting of 267 neuronal and 202 nonneuronal DMRs. Gene ontology analysis of DMR-associated genes showed that cell cycle-, cell division-, and inhibition of peptide activity-related genes were enriched in neurons, whereas synapse- and GABA-related genes were enriched in nonneurons. Among the DMR-associated genes, Trim2 and Lrpprc showed an inverse relationship between DNA methylation and gene expression status. In addition, we observed that mutant Polg1 transgenic mice shared several features of DNA methylation changes in postmortem brains of patients with BD, such as dominant hypomethylation changes in neurons, which include hypomethylation of the molecular motor gene and altered DNA methylation of synapse-related genes in nonneurons. Taken together, the DMRs identified in this study will contribute to understanding the pathophysiology of BD from an epigenetic perspective.

COVID-19, caused by SARS-CoV-2, has spread worldwide with dire consequence. Vaccine is just not enough to suppress to this pandemic, and it is desired to develop the prophylactic and therapeutic agents for preventing the spread of infection and severity. Therefore, it is extremely important to propose therapeutic strategies by using pathological models. In this study, we established an animal model with highly susceptible to SARS-CoV-2 via the intratracheal tract infection in CAG-promoter-driven human angiotensin-converting enzyme 2 transgenic (CAG-hACE2) mice that more than 15 copies of hACE2 genes were tandemly integrated into the mouse genome. The CAG-hACE2 mice showed several severe symptoms of SARS-CoV-2 infection, with definitive weight loss and subsequent death. Acute pneumonia with elevated cytokine and chemokine levels was observed at an early stage of infection in CAG-hACE2 mice infected with SARS-CoV-2. In the developed model, administration of remdesivir, which is antiviral agent, or injection of plasma from immunized mice prevented body weight loss and lethality due to infection with SARS-CoV-2. These results indicated that a highly susceptible model of SARS-CoV-2 infection in CAG-hACE2 mice via the intratracheal tract is suitable for evaluating antibody therapeutics and medicines.