Biology subjects

Yasui, M.

Publications and source records attributed to Yasui, M..

7 recordsLinked to original sources

bioRxiv2025

Chiral shift toward D-serine reflects intrathecal inflammation in multiple sclerosis and counteracts motor impairment in a murine model

Multiple sclerosis (MS) is characterized by chronic inflammatory demyelination involving complex interplay between the central nervous and immune systems. Neuroinflammation triggers cellular reorganization requiring O_SCPLOWLC_SCPLOW-serine for sustained syntheses of membrane lipids and nucleic acids, whereas it causes aberrant glutamatergic neurotransmission involving O_SCPLOWDC_SCPLOW-serine. However, significance of serine metabolism in MS pathology remains unexplored. Here we show that serine chiral homeostasis is disrupted in MS and endogenous O_SCPLOWDC_SCPLOW-serine prevents motor deficits caused by inflammatory demyelination. We found in a large cohort study that patients with MS exhibit elevated O_SCPLOWDC_SCPLOW-serine levels and the O_SCPLOWDC_SCPLOW-/total serine ratio in the cerebrospinal fluid at diagnosis. Steric deviation toward O_SCPLOWDC_SCPLOW-serine accords with emergence of the intrathecal inflammatory marker oligoclonal bands, and correlates negatively with proinflammatory cytokines. An in vivo animal model of MS, genetically engineered to exhibit distinct metabolic states of O_SCPLOWDC_SCPLOW-serine, revealed that endogenous O_SCPLOWDC_SCPLOW-serine synthesis mitigates the progression of motor deficits and suppresses proinflammatory and vascular endothelial pathogenic signaling. Moreover, pre-symptomatic oral supplementation with O_SCPLOWDC_SCPLOW-serine, but not O_SCPLOWLC_SCPLOW-serine, enhances production of extracellular matrices, preserves integrity of the blood brain barrier, attenuates demyelination, and improves motor function. Contrary to the previously recognized neurotoxic nature of O_SCPLOWDC_SCPLOW-serine, our findings reveal an unrecognized significance of O_SCPLOWDC_SCPLOW-serine metabolism in MS and a protective function of O_SCPLOWDC_SCPLOW-serine against neuroinflammation involving disruption of the blood brain barrier, which may present an untapped therapeutic target in MS. One Sentence SummarySerine chiral homeostasis is disturbed in multiple sclerosis and O_SCPLOWDC_SCPLOW-serine mitigates inflammatory demyelination.

neuroscience↗

bioRxiv2024

Serine chirality guides metabolic flow between one-carbon metabolism and neuromodulator synthesis

O_SCPLOWLC_SCPLOW-serine serves as a central metabolic node that integrates glycolytic flux, lipid metabolism, and one-carbon metabolism. In the mature central nervous system, O_SCPLOWLC_SCPLOW-serine is actively stereo-converted to O_SCPLOWDC_SCPLOW-serine, which functions as a neurotransmitter. However, the role of O_SCPLOWDC_SCPLOW-serine in cellular metabolism remains unclear. Here, we show that O_SCPLOWDC_SCPLOW-serine competes with mitochondrial O_SCPLOWLC_SCPLOW-serine transport, thereby suppressing one-carbon metabolism. Metabolomic analysis revealed that O_SCPLOWDC_SCPLOW-serine reduces intracellular glycine and formate levels, indicating inhibition of the initial step of the one-carbon pathway. Molecular dynamics simulations and enzymatic assays revealed that O_SCPLOWDC_SCPLOW-serine has low affinity for serine hydroxymethyltransferase 2 (Shmt2), which catalyzes the first step in mitochondrial one-carbon metabolism, and does not directly inhibit its activity. Instead, membrane transport assays demonstrated that O_SCPLOWDC_SCPLOW-serine competes with mitochondrial O_SCPLOWLC_SCPLOW-serine transport, depleting the substrate of Shmt2. Functionally, under O_SCPLOWLC_SCPLOW-serine poor conditions in vitro and ex vivo, O_SCPLOWDC_SCPLOW-serine inhibited the proliferation of immature and undifferentiated neural cells including glioblastoma stem cells, which depend highly on one-carbon metabolism. Notably, endogenous O_SCPLOWDC_SCPLOW-serine levels were low during early neurodevelopment, but increased with maturation, coinciding with a shift in the transcriptional profiles of serine metabolic enzymes at the cellular level. Given that O_SCPLOWLC_SCPLOW-serine supports neurodevelopment and O_SCPLOWDC_SCPLOW-serine modulates neurotransmission, this developmental shift in serine enantiomer metabolism appears to align with the functional transitions of the maturing nervous system. Thus, our findings reveal that serine chirality can influence mitochondrial substrate availability and one-carbon flux, offering previously unappreciated insight into the stereoselective regulation of cellular metabolism.

developmental biology↗

bioRxiv2024

DNA-free and genotype-independent CRISPR/Cas9 system in soybean

The CRISPR/Cas9 system has revolutionized the field of plant genetic engineering. Here we report a smart genome editing system of soybean by using iPB-RNP method without introducing foreign DNA and requiring traditional tissue culture processes such as embryogenesis and organogenesis. Shoot apical meristem (SAM) of embryonic axes was used the target tissue for genome editing, because the SAM in soybean mature seeds has stem cells and specific cell layer developing germ cells during reproductive growth stage. In the iPB-RNP method, the complex of ribonucleoprotein (RNP) and Cas9 protein was directly delivered into SAM stem cells via particle bombardment and genome-edited plants were generated from these SAMs. Soybean allergenic gene Gly m Bd 30K, which we previously generated genome-editing soybean by using Agrobacterium-mediated transformation and particle bombardment in our previous studies, was targeted in this study. Many E0 (the first generation of genome-edited) plants in this experiment harbored mutant alleles at the targeted locus. Editing frequency of inducing mutations transmissible to the E1 generation was approximately 0.4 to 4.6 % of all E0 plants utilized in various soybean varieties. Furthermore, Gly m Bd 30K protein in mature seeds was not detected by western blot analysis due to flame-sift mutations. Our results offer a practical approach for both plant regeneration- and DNA-free genome editing achieved by delivering RNP into the SAM of dicotyledonous plants.

plant biology↗

bioRxiv2023

Dose-dependent effects of histone methyltransferase NSD2 on site-specific double-strand break repair

Histone modifications are catalyzed and recognized by specific proteins to regulate dynamic DNA metabolism processes. NSD2 is a histone H3 lysine 36 (H3K36)-specific methyltransferase that associates both with various transcription regulators and DNA repair factors. Specifically, it has been implicated in the repair of DNA double-strand breaks (DSBs); however, the role of NSD2 during DSB repair remains enigmatic. Here, we show that NSD2 does not accumulate at DSB sites and that the localization of NSD2 at chromatin is maintained even after DSB formation. Using three different DSB repair reporter systems, which contained the endonuclease site in the active thymidine kinase gene (TK) locus, we demonstrated separate dose-dependent effects of NSD2 on HR, canonical-NHEJ (c-NHEJ), and non-canonical-NHEJ (non-c-NHEJ). Endogenous NSD2 has a role in repressing non-c-NHEJ, without affecting DSB repair efficiency by HR or total NHEJ. Furthermore, overexpression of NSD2 promotes c-NHEJ repair suppressing HR repair. Therefore, we propose that NSD2 has functions in chromatin integrity at the active regions during DSB repair.

cell biology↗

bioRxiv2022

Distribution of intraperitoneally administered D2O in AQP4-knockout mouse brain after MCA occlusion

As the movement of water in the brain is known to be involved in neural activity and various brain pathologies, the ability to assess water dynamics in the brain will be important for the understanding of brain function and the diagnosis and treatment of brain diseases. Aquaporin-4 (AQP4) is a membrane channel protein that is highly expressed in brain astrocytes and is important for the movement of water molecules in the brain. In this study, we investigated the contribution of AQP4 to brain water dynamics by administering deuterium-labeled water (D2O) intraperitoneally to wild-type and AQP4 knockout (AQP4-ko) mice that had undergone surgical occlusion of the middle cerebral artery. Water dynamics in the infarct region and on either side of the anterior cerebral artery (ACA) was monitored with proton-density-weighted imaging (PDWI) performed on a 7T animal MRI. D2O caused a negative signal change quickly after administration. The AQP4-ko mice showed a delay of the time-to-minimum in both contralateral and ipsilateral ACA region compared to wild-type mice. Also, only the AQP4-ko mice showed a delay of the time-to-minimum in the ipsilateral ACA region compared to the contralateral side. In only the wild-type mice, the signal minimum in the ipsilateral ACA region was higher than that in the contralateral ACA region. In the infarct region, the signal attenuation was slower for the AQP4-ko mice in comparison to the wild-type mice. These results suggest that AQP4 loss affects water dynamics in the ACA region not only in the infarct region. Dynamic PDWI after D2O administration may be a useful tool for showing the effects of AQP4 in vivo. HighlightsO_LIThe measurement of brain water dynamics with D2O. C_LIO_LIIn vivo investigation of AQP4 loss and focal brain ischemia. C_LIO_LIAQP4 loss affects water dynamics in the ACA region not only in the infarct region. C_LI

physiology↗

bioRxiv2021

Quantitative Measurement of Diffusion-weighted Imaging Signal Using Expression-controlled Aquaporin-4 Cells: Comparative Study of 2-compartment and Diffusion Kurtosis Imaging Models

PurposeThe purpose of this study was to compare parameter estimates for the 2-compartment (2Comp) and diffusion kurtosis imaging (DKm) models obtained from diffusion-weighted imaging (DWI) of aquaporin-4 (AQP4) expression-controlled cells, and to look for biomarkers that indicate differences in the cell membrane water permeability. MethodsDWI was performed on AQP4-expressing and non-expressing cells and the signal was analyzed with the 2Comp and DKm models. For the 2Comp model, the diffusion coefficients (Df, Ds) and volume fractions (Ff, Fs, Ff=1-Fs) of the fast and slow compartments were estimated. For the DKm model, estimates of the diffusion kurtosis (K) and corrected diffusion coefficient (D) were obtained. ResultsFor the 2Comp model, Ds and Fs showed clear differences between AQP4-expressing and non-expressing cells. Fs was also sensitive to cell density. There was no clear relationship with the cell type for the DKm parameters. ConclusionsChanges to cell membrane water permeability due to AQP4 expression affected DWI of cell suspensions. For the 2Comp and DKm models, Ds was the parameter most sensitive to differences in AQP4 expression.

cell biology↗

bioRxiv2019

Processing of a single ribonucleotide embedded into DNA by human nucleotide excision repair and DNA polymerase η

DNA polymerases often incorporate non-canonical nucleotide, i.e., ribonucleoside triphosphates into the genomic DNA. Aberrant accumulation of ribonucleotides in the genome causes various cellular abnormalities. Here, we show the possible role of human nucleotide excision repair (NER) and DNA polymerase {eta} (Pol {eta}) in processing of a single ribonucleotide embedded into DNA. We found that the reconstituted NER system can excise the oxidized ribonucleotide on the plasmid DNA. Taken together with the evidence that Pol {eta} accurately bypasses a ribonucleotide, i.e., riboguanosine (rG) or its oxidized derivative (8-oxo-rG) in vitro, we further assessed the mutagenic potential of the embedded ribonucleotide in human cells lacking NER or Pol {eta}. A single rG on the supF reporter gene predominantly induced large deletion mutations. An embedded 8-oxo-rG caused base substitution mutations at the 3-neighboring base rather than large deletions in wild-type cells. The disruption of XPA, an essential factor for NER, or Pol {eta} leads to the increased mutant frequency of 8-oxo-rG. Furthermore, the frequency of 8-oxo-rG-mediated large deletions was increased by the loss of Pol {eta}, but not XPA. Collectively, our results suggest that base oxidation of the embedded ribonucleotide enables processing of the ribonucleotide via alternative DNA repair and damage tolerance pathways.

genetics↗