Publications by authors named "Takashi Umehara"

Inhaled anesthetics were first introduced into clinical use in the 1840s. Molecular and transgenic animal studies indicate that inhaled anesthetics act through several ion channels, including γ-aminobutyric acid type A receptors (GABAARs) and two-pore domain K+ (K2P) channels, but other targets may mediate anesthetic effects. Mutations in the type 1 ryanodine receptor (RyR1), which is a calcium release channel on the endoplasmic reticulum membrane, are relevant to malignant hyperthermia, a condition that can be induced by inhaled anesthetics.

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A polypeptide folds into its protein tertiary structure in the native state through a folding intermediate in the non-native state. The transition between these states is thermodynamically driven. A folding intermediate of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) autophosphorylates intramolecularly, whereas DYRK1A in the native state no longer catalyzes this reaction.

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Structurally novel inhibitors of the lysine methyltransferase G9a have attracted considerable interest as potential drug candidates for cancer and genetic diseases. Here, a detailed account of potency optimization from early leads 8 and 9 to compound 16g is presented. Our search for an alternative scaffold for the 4-oxo-4,5,6,7-tetrahydro-1H-indole moiety of compounds 8 and 9 via parallel synthesis led to the identification of the 4-pyridin-4-ylamino phenyl substructure in compound 16g.

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Background: Toll-like receptors (TLRs) are critical components of the innate immune system and are expressed in various cells, including the reproductive system. Although their roles in female reproductive tissues such as the ovaries and uterus, including their involvement in fertilization and implantation, have been extensively reviewed, their expression and function in male germ cells, particularly in sperm, remain underexplored.

Methods: This review provides a comprehensive summary of research on TLRs expressed in sperm, including findings from experimental models in mice, humans, and industrial livestock.

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Sperm cells are highly susceptible to oxidative stress, which decreases their motility and fertility. However, glutathione (GSH) plays a critical role in protecting sperm cells from oxidative damage, a common byproduct of mitochondrial oxidative phosphorylation. On the other hand, GSH biosynthesis in sperm is limited by the availability of cysteine (Cys), which is inherently unstable and found at low concentrations in boar seminal plasma.

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People today are choosing to have children later in life, often in their thirties and forties, when their fertility is in decline. We sought to identify and compile effective methods for improving either male or female fertility in this context of advanced reproductive age. We found few clinical studies with strong evidence for therapeutics that mitigate reproductive aging or extend fertility; however, this Perspective summarizes the range of emerging experimental strategies under development.

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Lysine-specific demethylase 1 (LSD1/KDM1A) is a pivotal epigenetic enzyme that contributes to several malignancies including malignant glioma. LSD1 is a flavin adenine dinucleotide dependent histone demethylase that specifically targets histone H3 lysine (K) 4 mono- (me1) and di-methylation (me2) and H3K9me1/2 for demethylation. Herein we report the development of an LSD inhibitor, S2172, which efficiently penetrates the blood-brain barrier.

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Study Question: Is oocyte developmental competence associated with changes in granulosa cell (GC) metabolism?

Summary Answer: GC metabolism is regulated by the LH surge, altered by obesity and reproductive aging, and, in women, specific metabolic profiles are associated with failed fertilization versus increased blastocyst development.

What Is Known Already: The cellular environment in which an oocyte matures is critical to its future developmental competence. Metabolism is emerging as a potentially important factor; however, relative energy production profiles between GCs and cumulus cells and their use of differential substrates under normal in vivo ovulatory conditions are not well understood.

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Article Synopsis
  • Researchers focused on developing new inhibitors for lysine methyltransferase G9a, which plays a significant role in epigenetics.
  • They improved an existing compound (7a) to create a much more effective inhibitor (7i), which has a low IC value of 0.024 μM, indicating strong potency.
  • Studies using X-ray crystallography and SPR showed that 7i binds to G9a differently than other compounds, and it effectively reduced certain histone modifications and increased γ-globin mRNA levels in specific human cells.
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Ovarian fibrosis contributes to age-related ovarian dysfunction. In our previous study, we observed ovarian fibrosis in both obese and aging mice with intracellular lipid droplets in the fibrotic ovaries. Although the importance of mitochondria in ovarian fibrosis has been recognized in pharmacological studies, their role in lipid metabolism remains unclear.

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Article Synopsis
  • The study focuses on creating artificial cell models using lipid vesicles that can facilitate cell-free protein synthesis (CFPS), which is key for protein expression and gene circuits.
  • Researchers investigated how different lipid compositions (neutral, positively, negatively charged) in giant lipid vesicles affect transcription and translation processes over various incubation times.
  • Results indicated that lipid vesicles with positively charged lipids exhibited higher transcriptional and translational activities, highlighting their potential for improving artificial cell designs.
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Polycomb repressive complexes 1 and 2 (PRC1 and PRC2) are transcriptional repressor complexes that play a fundamental role in epigenomic regulation and the cell-fate decision; these complexes are widely conserved in multicellular organisms. PRC1 is an E3 ubiquitin (ub) ligase that generates histone H2A ubiquitinated at lysine (K) 119 (H2AK119ub1), whereas PRC2 is a histone methyltransferase that specifically catalyzes tri-methylation of histone H3K27 (H3K27me3). Genome-wide analyses have confirmed that these two key epigenetic marks highly overlap across the genome and contribute to gene repression.

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It is known that sperm and seminal plasma (SP) affect uterine immunity. In cattle, artificial insemination enables breeding by depositing frozen and largely diluted sperm with a negligible amount of SP into the uterus. Thus, the present study focused on the impact of frozen-thawed sperm on bovine uterine immunity.

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Glioma amplified sequence 41 (GAS41), which has the Yaf9, ENL, AF9, Taf14, and Sas5 (YEATS) domain that recognizes lysine acetylation (Kac), regulates gene expression as a subunit of the SRCAP (SNF2-related CREBBP activator protein) complex that deposits histone H2A.Z at promoters in eukaryotes. The YEATS domains of the proteins AF9 and ENL recognize Kac by hydrogen bonding the aromatic cage to arginine situated just before K9ac or K27ac in the N-terminal tail of histone H3.

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Background: Super-enhancers (SEs), which activate genes involved in cell-type specificity, have mainly been defined as genomic regions with top-ranked enrichment(s) of histone H3 with acetylated K27 (H3K27ac) and/or transcription coactivator(s) including a bromodomain and extra-terminal domain (BET) family protein, BRD4. However, BRD4 preferentially binds to multi-acetylated histone H4, typically with acetylated K5 and K8 (H4K5acK8ac), leading us to hypothesize that SEs should be defined by high H4K5acK8ac enrichment at least as well as by that of H3K27ac.

Results: Here, we conducted genome-wide profiling of H4K5acK8ac and H3K27ac, BRD4 binding, and the transcriptome by using a BET inhibitor, JQ1, in three human glial cell lines.

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Freezing and thawing diminish sperm motility and fertility by disrupting the cholesterol balance in sperm plasma and organelle membranes. The aim of this study was to elucidate the mechanisms through which exogeneous cholesterol treatment enhances the quality of frozen-thawed bull sperm. The incorporation of cholesterol was investigated using boron-dipyrromethene (BODIPY)-cholesterol, and BODIPY signals were detected not only in the plasma membrane but also in the midpiece region immediately after thawing.

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Histone acetylation is important for the activation of gene transcription but little is known about its direct read/write mechanisms. Here, we report cryogenic electron microscopy structures in which a p300/CREB-binding protein (CBP) multidomain monomer recognizes histone H4 N-terminal tail (NT) acetylation (ac) in a nucleosome and acetylates non-H4 histone NTs within the same nucleosome. p300/CBP not only recognized H4NTac via the bromodomain pocket responsible for reading, but also interacted with the DNA minor grooves via the outside of that pocket.

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Histone lysine acylation, including acetylation and crotonylation, plays a pivotal role in gene transcription in health and diseases. However, our understanding of histone lysine acylation has been limited to gene transcriptional activation. Here, we report that histone H3 lysine 27 crotonylation (H3K27cr) directs gene transcriptional repression rather than activation.

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TEAD transcription factors are responsible for the transcriptional output of Hippo signaling. TEAD activity is primarily regulated by phosphorylation of its coactivators, YAP and TAZ. In addition, cysteine palmitoylation has recently been shown to regulate TEAD activity.

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The dynamic regulation of histone methylation and demethylation plays an important role in the regulation of gene expression. Aberrant expression of histone lysine demethylases has been implicated in various diseases including intractable cancers, and thus lysine demethylases serve as promising therapeutic targets. Recent studies in epigenomics and chemical biology have led to the development of a series of small-molecule demethylase inhibitors that are potent, specific, and have in vivo efficacy.

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Identification of structurally novel inhibitors of lysine methyltransferase G9a has been a subject of intense research in cancer epigenetics. Starting with the high-throughput screening (HTS) hit - obtained from the chemical library of the University of Tokyo Drug Discovery Initiative, the structure-activity relationship of the unique substrate-competitive inhibitors was established with the help of X-ray crystallography and fragment molecular orbital (FMO) calculations for the ligand-protein interaction. Further optimization of the characteristics and drug metabolism and pharmacokinetics (DMPK) properties led to the identification of (RK-701), which is a structurally distinct potent inhibitor of G9a/GLP (IC = 27/53 nM).

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Article Synopsis
  • * A new selective G9a inhibitor, RK-701, effectively increases fetal globin expression in human cells and mice without causing genetic damage.
  • * The long non-coding RNA BGLT3 is crucial for γ-globin production induced by RK-701 and other treatments, highlighting its significance in therapeutic approaches for SCD.
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Polycomb repressive complex 1 (PRC1) and PRC2 are responsible for epigenetic gene regulation. PRC1 ubiquitinates histone H2A (H2Aub), which subsequently promotes PRC2 to introduce the H3 lysine 27 tri-methyl (H3K27me3) repressive chromatin mark. Although this mechanism provides a link between the two key transcriptional repressors, PRC1 and PRC2, it is unknown how histone-tail dynamics contribute to this process.

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Eukaryotic gene expression is regulated through chromatin conformation, in which enhancers and promoters physically interact (E-P interactions). How such chromatin-mediated E-P interactions affect gene expression is not yet fully understood, but the roles of histone acetylation and methylation, pioneer transcription factors, and architectural proteins such as CCCTC binding factor (CTCF) and cohesin have recently attracted attention. Moreover, accumulated data suggest that E-P interactions are mechanistically involved in biophysical events, including liquid-liquid phase separation, and in biological events, including cancers.

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