Biology subjects

Mizuno, M.

Publications and source records attributed to Mizuno, M..

7 recordsLinked to original sources

bioRxiv2026

Comprehensive transcriptomic and proteomic profiling of mTOR-related epilepsy

Malformations of cortical development (MCDs) are a major cause of drug-resistant epilepsy (DRE) in children. A subset of MCDs, including focal cortical dysplasia type II, tuberous sclerosis complex, and hemimegalencephaly, shares characteristic histopathological features and somatic mutations in genes within the PI3K-AKT-mTOR signaling cascade, and is termed mTORopathies. However, the molecular mechanisms that drive epileptogenesis and consequent uncontrollable seizures in these disorders remain poorly understood. Here, we performed integrated genomic, transcriptomic, and proteomic analyses of 60 surgical brain specimens from 42 patients with MCDs and 18 with mesial temporal lobe epilepsy. Targeted genomic sequencing identified 19 somatic mutations in PI3K-AKT-mTOR pathway genes, including novel variants in AKT3 (L51H) and MTOR (A512T). RNA sequencing comparing mTORopathy brains with controls, along with cross-validation using an independent public dataset, identified 287 consistently differentially expressed genes that were consistently altered. Downregulated genes were enriched in oxidative phosphorylation (OXPHOS) and mitochondrial metabolic pathways, whereas upregulated genes were associated with gliogenesis and cellular senescence. Proteomic profiling identified 44 differentially expressed proteins, including significant reductions in OXPHOS-related proteins (COX5B, NDUFS4, GOT2, RAB27B, and DKK3). Our study provides a patient-matched, multi-omics dataset of human mTOR-related epilepsies from a single-institution cohort. Integrated analyses across transcriptomic and proteomic layers highlight impairment of OXPHOS as a molecular hallmark of mTORopathies, Integrated transcriptomic and proteomic analyses identified impaired OXPHOS as a molecular hallmark, potentially contributing to focal hypometabolism in mTORopathy. These findings offer mechanistic insights into epileptogenesis and provide a valuable resource for understanding molecular pathologies and developing mechanism-based therapies for mTOR-related epilepsy.

neuroscience↗

bioRxiv2026

Single-cell-resolved spatial multi-omics identifies mTOR-driven neuronal and astroglial pathogenicity underlying epileptogenic focal cortical dysplasia

Focal cortical dysplasia type II (FCDII) is a malformation of cortical development caused by somatic mutations in the mTOR signaling pathway. Two hallmark pathological cell types in FCDII, dysmorphic neurons (DNs) and balloon cells (BCs), arise as a result of somatic mutations in the mTOR signaling pathway and are implicated in the pathophysiology of drug-resistant epilepsy. However, how these somatic mutations reshape cell states within the human cortex remains poorly understood. Here, we integrate imaging-based spatial transcriptomics (iST), single-nucleus RNA sequencing, and proteomics of surgically resected FCDIIb tissue to define the transcriptional and proteomic profiles of DNs and BCs. Spatial mapping of iST data resolved transcriptional signatures in histologically validated DNs and BCs within FCDIIb sections. Integrative omics analysis further revealed that DNs show upregulation of PI3K-AKT-mTOR and p53-CROT metabolic programs accompanied by suppression of synaptic signaling, whereas BCs exhibit transcriptional signatures of reactive astrocytes with increased phagocytic and immune-like activity. These data delineate cell-type-specific consequences of somatic mTOR pathway mutations at single-cell resolution and reveal previously unrecognized metabolic and immunoregulatory mechanisms contributing to epileptogenesis in drug-resistant epilepsy. Our study establishes a spatial multi-omics framework for dissecting human cortical malformations and highlights potential therapeutic targets for drug-resistant epilepsy.

neuroscience↗

bioRxiv2026

MEIS1 is Required for Establishing Bergmann Glia-Specific Properties in the Developing Cerebellum

Compared to normal multipolar astrocytes, Bergmann glial cells (BGs), specifically differentiated astrocytes in the cerebellum, possess unique unipolar morphology and additional cellular functions. However, the molecular mechanisms that confer BG-specific properties onto normal multipolar astrocytes remain unknown. Here, we show that the transcription factor, MEIS1, is involved in BGs acquiring their unique characteristics. Targeted disruption of Meis1 in the whole cerebellum or astroglial lineage cells resulted in a marked reduction of BGs accompanied by an increase in multipolar astrocytes in mice. Postnatal deletion of Meis1 in Bergmann glia-like progenitors (BGLPs), which produce both BGs and multipolar astrocytes, suppressed their differentiation into BGs while promoting into multipolar astrocytes. Single-cell RNA sequencing, immunohistochemistry, and ChIP-Atlas analyses indicated that MEIS1 directly upregulates expression of BG-specific genes, including Vimentin and Zeb2, which are known to contribute to the correct localization and the unipolar process formation of BGs. These findings suggest that MEIS1 promotes the endowment of BG-specific properties to astrocytes by controlling the expression of BG-specific genes, thereby ensuring proper differentiation of BGLPs into BGs.

developmental biology↗

bioRxiv2025

Postoperative Automated Platelet Count and Its Predictive Factors in Dogs Undergoing Mitral Valve Repair

ObjectivesThis study aimed to describe early postoperative changes in automated platelet counts (PLT) after mitral valve repair (MVR) in dogs with myxomatous mitral valve disease (MMVD) and to identify factors associated with these changes. DesignSingle-center retrospective cohort study. AnimalsDogs with MMVD that underwent MVR from July 2022 to July 2023. After data extraction, the ten most common breeds were selected, and mixed breeds as well as breeds known for inherent platelet abnormalities (Cavalier King Charles Spaniels and Norfolk Terriers) were excluded. Measurements and Main ResultsA total of 313 dogs representing seven breeds met the inclusion criteria. PLT levels were assessed preoperatively (Day 0) and daily for 4 days postoperatively (Days 1-4). Mean (standard deviation) PLT values were 393{+/-}127 x103/{micro}L on Day 0, 159{+/-}72 on Day 1, 137{+/-}67 on Day 2, 157{+/-}87 on Day 3, and 187{+/-}104 on Day 4. Postoperative thrombocytopenia (<100 x103/{micro}L) occurred in 124 of 313 dogs during Days 1-4. In a multivariable mixed-effects model, PLT declined significantly after surgery (Day 0 to 1; {beta} = -207.17 [x103/{micro}L per day], P < 0.001) and showed a postoperative upward trend (Day 1 to 4; {beta} = 20.62 [x103/{micro}L per day], P = 0.079). Older age was associated with higher PLT; Toy Poodles and Yorkshire Terriers demonstrated lower PLT than Chihuahuas; dogs with ACVIM Stages C- D had higher PLT compared with Stage B2; lower body weight correlated with lower PLT; and intact dogs tended to have higher PLT than neutered dogs. ConclusionsPLT decreased sharply following MVR and demonstrated partial recovery within 5 days. Age, breed, clinical stage, body weight, and neuter status were associated with postoperative PLT patterns, indicating their importance for perioperative assessment and monitoring.

physiology↗

bioRxiv2025

Lineage Analysis and Molecular Characterization of Bergmann Glia-like Progenitors in the Postnatal Mouse Cerebellum using in vivo Electroporation and Spatial Transcriptomics

In the mammalian cerebellum, three types of astroglial cells--Bergmann glial cells (BGs), inner granule cell layer (IGL) astrocytes, and white matter (WM) astrocytes--arise in postnatal timing from two types of progenitors: Bergmann glia-like progenitors (BGLPs) and astrocyte-like progenitors (AsLPs). In contrast to AsLPs, which are commonly observed in other brain regions, BGLPs have not been well studied. Here we investigate their dynamic changes in number, their differentiation abilities and their gene expression profiles during cerebellar development. BGLPs and AsLPs decrease in number as development progresses from P0, and are almost absent by P10. We developed an electroporation-based method to investigate the progeny cells of BGLPs. We found that BGLPs at P6 differentiate into BGs and IGL astrocytes, but not into WM astrocytes, which is consistent with a previous report. However, BGLPs at P0 were observed to differentiate into not only BGs and IGL astrocytes, but also WM astrocytes, indicating that P0 BGLPs possess wider pluripotency than P6 BGLPs. By conducting spatial transcriptomic analysis of the cerebellum at P0 and P6 with over 5,000 probes (Xenium, 5k), we successfully obtained clusters corresponding to BGLPs at P0 and P6, respectively. Further informatics analyses suggested that P0 BGLPs exhibit more stem cell-like features, while P6 BGLPs show a shift toward BG-like characteristics. This study, which includes transcriptome big data, will contribute to understanding the differentiation of BGs and astrocytes, as well as other types of cells, during postnatal cerebellar development.

developmental biology↗

bioRxiv2023

Normative modeling of brain morphometry in Clinical High-Risk for Psychosis

ImportanceThe lack of robust neuroanatomical markers of psychosis risk has been traditionally attributed to heterogeneity. A complementary hypothesis is that variation in neuroanatomical measures in the majority of individuals at psychosis risk may be nested within the range observed in healthy individuals. ObjectiveTo quantify deviations from the normative range of neuroanatomical variation in individuals at clinical high-risk for psychosis (CHR-P) and evaluate their overlap with healthy variation and their association with positive symptoms, cognition, and conversion to a psychotic disorder. Design, Setting, and ParticipantsClinical, IQ and FreeSurfer-derived regional measures of cortical thickness (CT), cortical surface area (SA), and subcortical volume (SV) from 1,340 CHR-P individuals [47.09% female; mean age: 20.75 (4.74) years] and 1,237 healthy individuals [44.70% female; mean age: 22.32 (4.95) years] from 29 international sites participating in the ENIGMA Clinical High Risk for Psychosis Working Group. Main Outcomes and MeasuresFor each regional morphometric measure, z-scores were computed that index the degree of deviation from the normative means of that measure in a healthy reference population (N=37,407). Average deviation scores (ADS) for CT, SA, SV, and globally across all measures (G) were generated by averaging the respective regional z-scores. Regression analyses were used to quantify the association of deviation scores with clinical severity and cognition and two-proportion z-tests to identify case-control differences in the proportion of individuals with infranormal (z<-1.96) or supranormal (z>1.96) scores. ResultsCHR-P and healthy individuals overlapped in the distributions of the observed values, regional z-scores, and all ADS vales. The proportion of CHR-P individuals with infranormal or supranormal values in any metric was low (<12%) and similar to that of healthy individuals. CHR-P individuals who converted to psychosis compared to those who did not convert had a higher percentage of infranormal values in temporal regions (5-7% vs 0.9-1.4%). In the CHR-P group, only the ADSSA showed significant but weak associations (|{beta}|<0.09; PFDR<0.05) with positive symptoms and IQ. Conclusions and RelevanceThe study findings challenge the usefulness of macroscale neuromorphometric measures as diagnostic biomarkers of psychosis risk and suggest that such measures do not provide an adequate explanation for psychosis risk. Key pointsO_ST_ABSQuestionC_ST_ABSIs the risk of psychosis associated with brain morphometric changes that deviate significantly from healthy variation? FindingsIn this study of 1340 individuals high-risk for psychosis (CHR-P) and 1237 healthy participants, individual-level variation in macroscale neuromorphometric measures of the CHR-P group was largely nested within healthy variation and was not associated with the severity of positive psychotic symptoms or conversion to a psychotic disorder. MeaningThe findings suggest the macroscale neuromorphometric measures have limited utility as diagnostic biomarkers of psychosis risk.

neuroscience↗

bioRxiv2018

PP2AB55δ Responsible for the High Initial Rates of Alcoholic Fermentation in Sake Yeast Strains of Saccharomyces cerevisiae

Sake yeast strain Kyokai no. 7 (K7) and its Saccharomyces cerevisiae relatives carry a homozygous loss-of-function mutation in the RIM15 gene, which encodes a Greatwall-family protein kinase. Disruption of RIM15 in non-sake yeast strains leads to improved alcoholic fermentation, indicating that the defect in Rim15p is associated with the enhanced fermentation performance of sake yeast cells. In order to understand how Rim15p mediates fermentation control, we here focused on target-of-rapamycin protein kinase complex 1 (TORC1) and protein phosphatase 2A with the B55{Delta} regulatory subunit (PP2AB55{delta}), complexes that are known to act upstream and downstream of Rim15p, respectively. Several lines of evidence, including our previous transcriptomic analysis data, suggested enhanced TORC1 signaling in sake yeast cells during sake fermentation. Fermentation tests of the TORC1-related mutants using a laboratory strain revealed that TORC1 signaling positively regulates the initial fermentation rate in a Rim15p-dependent manner. Deletion of the CDC55 gene encoding B55{delta} abolished the high fermentation performance of Rim15p-deficient laboratory yeast and sake yeast cells, indicating that PP2AB55{delta} mediates the fermentation control by TORC1 and Rim15p. The TORC1-Greatwall-PP2AB55{delta} pathway similarly affected the fermentation rate in the fission yeast Schizosaccharomyces pombe, strongly suggested that the evolutionarily conserved pathway governs alcoholic fermentation in yeasts. It is likely that elevated PP2AB55{delta} activity accounts for the high fermentation performance of sake yeast cells. Heterozygous loss-of-function mutations in CDC55 found in K7-related sake strains may indicate that the Rim15p-deficient phenotypes are disadvantageous to cell survival.\n\nIMPORTANCEThe biochemical processes and enzymes responsible for glycolysis and alcoholic fermentation by the yeast S. cerevisiae have long been the subject of scientific research. Nevertheless, the factors determining fermentation performance in vivo are not fully understood. As a result, the industrial breeding of yeast strains has required empirical characterization of fermentation by screening numerous mutants through laborious fermentation tests. To establish a rational and efficient breeding strategy, key regulators of alcoholic fermentation need to be identified. In the present study, we focused on how sake yeast strains of S. cerevisiae have acquired high alcoholic fermentation performance. Our findings provide a rational molecular basis to design yeast strains with optimal fermentation performance for production of alcoholic beverages and bioethanol. In addition, as the evolutionarily conserved TORC1-Greatwall-PP2AB55{delta} pathway plays a major role in the glycolytic control, our work may contribute to research on carbohydrate metabolism in higher eukaryotes.

microbiology↗