Publications by authors named "Yuki Hitomi"

Article Synopsis
  • Previous studies have found both shared and population-specific genetic factors contributing to primary biliary cholangitis (PBC), with more than 20 novel susceptibility loci identified in a recent meta-analysis across different populations.
  • A new genome-wide association study (GWAS) focused on the Japanese population identified the gene PTPN2 as a novel susceptibility gene for PBC, linking a specific variant (rs8098858) to the disease.
  • The risk allele (rs2292758) is shown to disrupt PTPN2 expression, leading to an impaired negative feedback mechanism in immune signaling, suggesting that targeting PTPN2 could be a promising approach for PBC treatment.
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In neurological and neuropsychiatric diseases, different brain regions are affected, and differences in gene expression patterns could potentially explain this mechanism. However, limited studies have precisely explored gene expression in different regions of the human brain. In this study, we performed long-read RNA sequencing on three different brain regions of the same individuals: the cerebellum, hypothalamus, and temporal cortex.

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CD58 plays roles in cell adhesion and co-stimulation with antigen presentation from major histocompatibility complex class II on antigen-presenting cells to T-cell antigen receptors on naïve T cells. CD58 reportedly contributes to the development of various human autoimmune diseases. Recently, genome-wide association studies (GWASs) identified CD58 as a susceptibility locus for autoimmune diseases such as systemic lupus erythematosus (SLE), multiple sclerosis (MS), and primary biliary cholangitis (PBC).

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  • The Ryukyu Islands, located in southern Japan, have distinct histories and cultures that set them apart from mainland Japan, with genetic variations among their islander populations.
  • A study analyzed the whole genomes of 50 Ryukyu islanders, revealing significant genetic differences between Miyako and Okinawa islanders due to genetic drift rather than migration rates.
  • Findings suggest that the modern population structure stems from historical admixture with mainland Japanese rather than previous subpopulations from the Neolithic Ryukyu Jomon period.
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  • Primary biliary cholangitis (PBC) is an autoimmune disease linked to specific genetic factors, particularly related to the pyruvate dehydrogenase complex.
  • A study analyzed genetic data from 1,670 PBC patients and 2,328 healthy individuals, confirming 18 known Japanese PBC-associated alleles and discovering additional novel alleles that affect disease susceptibility.
  • Certain alleles were found to be associated with a higher risk of autoimmune hepatitis and hepatocellular carcinoma in PBC patients, enhancing understanding of genetic factors influencing disease progression and complications.
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A non-covalent oral drug targeting SARS-CoV-2 main protease (M), ensitrelvir (Xocova), has been developed using structure-based drug design (SBDD). To elucidate the factors responsible for enhanced inhibitory activities from an screening hit compound to ensitrelvir, we analyzed the interaction energies of the inhibitors with each residue of M using fragment molecular orbital (FMO) calculations. This analysis reveals that functional group conversion for P1' and P1 parts in the inhibitors increases the strength of existing interactions with M and also provides novel interactions for ensitrelvir; the associated changes in the conformation of M induce further interactions for ensitrelvir in other parts, including hydrogen bonds, a halogen bond, and π-orbital interactions.

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Primary biliary cholangitis (PBC) is a chronic, progressive cholestatic liver disease in which the small intrahepatic bile ducts are destroyed by autoimmune reactions. Among autoimmune diseases, which are polygenic complex traits caused by the combined contribution of genetic and environmental factors, PBC exhibits the strongest involvement of genetic heritability in disease development. As at December 2022, genome-wide association studies (GWASs) and associated meta-analyses identified approximately 70 PBC susceptibility gene loci in various populations, including those of European and East Asian descent.

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  • Antimicrobial resistance (AMR) is a significant global health issue, with drug-resistant bacteria like Neisseria gonorrhoeae becoming harder to treat, prompting the need for new antibiotics.
  • Researchers discovered a unique allosteric inhibitory site in mitochondrial heme-copper oxidases (HCOs) that could be targeted to develop antibiotics, particularly against ceftriaxone-resistant strains of Neisseria gonorrhoeae.
  • The study combines molecular dynamics and specialized spectroscopy techniques to show how the new inhibitors block substrate access in HCOs, paving the way for innovative strategies to combat AMR.
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Background: Ligation of CD28 with ligands such as CD80 or CD86 provides a critical second signal alongside antigen presentation by class II major histocompatibility complex expressed on antigen-presenting cells through the T cell antigen receptor for naïve T cell activation. A number of studies suggested that CD28 plays an important role in the pathogenesis of various human diseases. Recent genome-wide association studies (GWASs) identified CD28 as a susceptibility locus for lymphocyte and eosinophil counts, multiple sclerosis, ulcerative colitis, celiac disease, rheumatoid arthritis, asthma, and primary biliary cholangitis.

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  • A genome-wide association study was conducted with 318 chronic hepatitis B cases and 309 healthy controls from the Thai population to identify genetic factors influencing HBV persistence.
  • Significant associations were found with several alleles in the class II region, revealing specific protective and risk variants linked to HBV chronicity.
  • The study also highlighted novel candidate loci and identified rs1061307 as the primary functional variant, enhancing our understanding of chronic hepatitis B pathophysiology.
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The identification, structure-activity relationships (SARs), and biological effects of new antimalarials consisting of a 2,3,4,9-tetrahydro-1H-β-carboline core, a coumarin ring, and an oxyalkanoyl linker are described. A cell-based phenotypic approach was employed in this search for novel antimalarial drugs with unique modes of action. Our screening campaign of the RIKEN compound library succeeded in the identification of the known tetrahydro-β-carboline derivative (4e) as a hit compound showing significant in vitro activity.

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  • Aggressive therapy-resistant acute myeloid leukemia (AML) shows a very poor prognosis, prompting research into its vulnerabilities.
  • Comprehensive analysis of high-risk human AML samples led to the identification of specific anti-apoptotic proteins and a mitosis regulator as key therapeutic targets.
  • A combination therapy targeting these vulnerabilities showed promising results, eliminating established AML in animal models and offering a potential precision-medicine approach for treatment.
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Primary biliary cholangitis (PBC) is a chronic cholestatic autoimmune liver disease that appears to be strongly influenced by genetic factors. Recently, an international meta-analysis of genome-wide association studies (GWAS) identified CC-Motif Chemokine Receptor-6 (CCR6) and FGFR1 Oncogene-Partner (FGFR1OP) as PBC-susceptibility genes. However, the lead single nucleotide polymorphisms (SNPs) of CCR6/FGFR1OP showed low linkage disequilibrium with each other in East Asian and European populations.

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Coronin-1, a hematopoietic cell-specific actin-binding protein, is thought to be involved in the phagocytic process through its interaction with actin filaments. The dissociation of coronin-1 from phagosomes after its transient accumulation on the phagosome surface is associated with lysosomal fusion. We previously reported that 1) coronin-1 is phosphorylated by protein kinase C (PKC), 2) coronin-1 has two phosphorylation sites, Ser-2 and Thr-412, and 3) Thr-412 of coronin-1 is phosphorylated during phagocytosis.

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Backgrounds & Aims: Primary biliary cholangitis (PBC) is a chronic liver disease in which autoimmune destruction of the small intrahepatic bile ducts eventually leads to cirrhosis. Many patients have inadequate response to licensed medications, motivating the search for novel therapies. Previous genome-wide association studies (GWAS) and meta-analyses (GWMA) of PBC have identified numerous risk loci for this condition, providing insight into its aetiology.

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While the advent of GWAS more than a decade ago has ushered in remarkable advances in our understanding of complex traits, the limitations of single-SNP analysis have also led to the development of several other approaches. Simulation studies have shown that the regional heritability mapping (RHM) method, which makes use of multiple adjacent SNPs jointly to estimate the genetic effect of a given region of the genome, generally has higher detection power than single-SNP GWAS. However, thus far its use has been mostly limited to agricultural settings, and its potential for the discovery of new genes in human diseases is yet to be fully exploited.

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Background & Aims: Genome-wide association studies in primary biliary cholangitis (PBC) have failed to find X chromosome (chrX) variants associated with the disease. Here, we specifically explore the chrX contribution to PBC, a sexually dimorphic complex autoimmune disease.

Methods: We performed a chrX-wide association study, including genotype data from 5 genome-wide association studies (from Italy, United Kingdom, Canada, China, and Japan; 5244 case patients and 11,875 control individuals).

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Primary biliary cholangitis (PBC) is a chronic, progressive cholestatic liver disease in which intrahepatic bile ducts are destroyed by an autoimmune reaction. Our previous genome-wide association study (GWAS) identified chromosome 11q23.1 as a susceptibility gene locus for PBC in the Japanese population.

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Stevens-Johnson syndrome (SJS) and its severe condition with extensive skin detachment and a poor prognosis, toxic epidermal necrolysis (TEN), are immunologically mediated severe cutaneous reactions of the skin and mucous membranes such as the ocular surface. Genetic variations on the HLA-A and other autosomal genes have been identified as risk factors for cold medicine-related SJS/TEN with severe ocular complications (CM-SJS/TEN with SOC). Using a whole-genome sequencing (WGS) approach, we explored other susceptible variants of CM-SJS/TEN with SOC, especially among rare variants and structural variants (SVs).

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Chagas disease is caused by infection with the protozoan parasite Trypanosoma cruzi (T. cruzi). It was originally a Latin American endemic health problem, but now is expanding worldwide as a result of increasing migration.

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We developed the world's first web-based public database for the storage, management, and sharing of fragment molecular orbital (FMO) calculation data sets describing the complex interactions between biomacromolecules, named FMO Database (https://drugdesign.riken.jp/FMODB/).

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Guillain-Barré syndrome (GBS), including its variant Miller Fisher syndrome (MFS), is an acute peripheral neuropathy that involves autoimmune mechanisms leading to the production of autoantibodies to gangliosides; sialic acid-containing glycosphingolipids. Although association with various genetic polymorphisms in the major histocompatibility complex (MHC) is shown in other autoimmune diseases, GBS is an exception, showing no such link. No significant association was found by genome wide association studies, suggesting that GBS is not associated with common variants.

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