Biology subjects

Imamura, T.

Publications and source records attributed to Imamura, T..

11 recordsLinked to original sources

bioRxiv2026

Calibrated ADAMTS13 inhibition prevents cardiovascular shear coagulopathy

Mechanical circulatory support essential for managing severe heart failure frequently triggers bleeding complications, driven by shear stress-induced over-proteolysis of von Willebrand factor (VWF) by ADAMTS13. Inhibiting ADAMTS13 presents a rationale to treat this condition, known as acquired von Willebrand syndrome (AVWS). However, conventional therapeutic strategies remain limited due to the risk of triggering thrombotic thrombocytopenic purpura. Here we show that HA10, a humanized anti-ADAMTS13 antibody, preserves a residual level of ADAMTS13 activity above the thrombosis-associated threshold. Multimodal structural and biophysical analyses--including NMR, SAXS, and SANS--revealed that HA10 bound to the disintegrin-like domain of ADAMTS13, dynamically competing with VWF while leaving 10- 20% residual enzymatic activity. The therapeutic efficacy and safety of HA10 were verified in non-human primate models of AVWS. Our findings establish a novel paradigm of enzymatic calibration rather than complete blockade, offering a mechanistically targeted and safe therapeutic approach for cardiovascular bleeding.

biochemistry↗

bioRxiv2026

A cyclo-DOPA 6-O-glucosyltransferase-mediated route for gomphrenin I biosynthesis in Basella alba and Gomphrena globosa

O_LIBetacyanins are red pigments characteristic of Caryophyllales and show considerable structural diversity, yet the enzymatic basis underlying 6-O-glucosylated betacyanins such as gomphrenin I has remained unclear. In particular, how alternative glucosylation patterns contribute to betacyanin diversification is poorly understood. C_LIO_LIHere, we identified cyclo-DOPA glucosyltransferases from Basella alba and Gomphrena globosa and examined their roles in gomphrenin I biosynthesis using transient expression assays and tobacco BY-2 cell systems. Phylogenetic analyses, structural modelling and site-directed mutagenesis were employed to investigate their functional and structural characteristics. C_LIO_LIBacDOPA5/6GTs catalysed both 5-O- and 6-O-glucosylation of cyclo-DOPA, leading to the production of betanin and gomphrenin I, whereas GgcDOPA6GT specifically mediated gomphrenin I formation. These enzymes belong to distinct subclades within the cDOPA-GT family, and mutational analyses demonstrated essential roles for conserved histidine residues and an -helical region adjacent to the catalytic site. C_LIO_LIThermal stability analyses further showed that gomphrenin I is more thermally stable than betanin, likely due to the formation of an intramolecular hydrogen bond. Together, these results reveal an additional cDOPA6GT-mediated route for gomphrenin I biosynthesis and provide insight into the diversification and functional specialization of betacyanins, linking the position of glucosylation to pigment stability and biochemical properties. C_LI

plant biology↗

bioRxiv2024

AUTS2, a causative gene for microcephaly, regulates division of intermediate progenitor cells and production of upper-layer neurons

AUTS2 mutations often exhibit neurodevelopmental disorders and microcephaly. However, how AUTS2 regulates neuron production and affects brain size remains unclear. Here, we show that AUTS2 cooperates with the Polycomb complex PRC2 to regulate gene expression and cortical neurogenesis. Auts2 mutant mice exhibit reduced division of intermediate progenitor cells (IPCs), leading to decreased neurons and thickness in the upper-layer cortex. Expression of Robo1 is increased in the mutants, which in turn suppresses IPC division. Transcriptome and chromatin profiling experiments show that, in IPCs, AUTS2 primarily represses transcription of genes, including Robo1. Promoter region of AUTS2 target genes is enriched with H3K27me3, a repressive histone modification, but its levels are reduced in Auts2 mutants. AUTS2 interacts with PRC2, and together, they promote IPC division. These suggest that AUTS2 collaborates with PRC2 to repress gene transcription through H3K27 trimethylation, promoting neuron production. This sheds light on AUTS2 pathophysiological mechanisms in neurogenesis and microcephaly.

neuroscience↗

bioRxiv2023

Willingness of Japanese people in their 20s, 30s and 40s to pay for genetically modified foods

The application of genetically modified (GM) technology to food products has increased worldwide. The adaptation has extended to conventional grains and animal products, such as salmon. However, in Japan, the publics acceptance of GM foods is low and experts and policymakers need to know the publics preference for various types of GM foods. Therefore, this study aims to clarify and compare the preferences for various GM foods among Japanese people in their 20s, 30s, and 40s, using the Willingness-to-pay (WTP) indicator. An online survey with 1122 valid responses from people in their 20s-40s was used for analysis. The results showed that the percentages of willingness to purchase various items were as follows - GM blue roses (n = 628; 56%), tomatoes fertilized with GM oil cake (n = 519; 46.3%), potato chips made from GM potatoes (n = 489; 43.6%), chicken thighs fed on GM corn (n = 472; 42.1%), corn flakes made from GM corn (n = 471; 42.0%), GM apples (n = 420; 37.4%), wine brewed with GM yeast (n = 416; 37.1%), GM tomatoes (n = 408; 36.4%), GM chicken thighs (n = 360; 32.1%), GM salmon (n = 349; 31.1%). Comparing the WTP discount rates for animal and plant foods, it was around 20% for animal products (GM chicken thighs = 17.8% and GM salmon = 19.5%), and 15-35% for plant foods (GM corn flakes = 24.1%, GM tomatoes = 17.2%, GM potato chips = 16.4%, GM yeast wine = 36.7%, GM apples = 25.3%). The WTP discount rates were 11.9% for tomatoes fertilized with GM oil cake compared with 17.2% for GM tomatoes, and 21.5% for GM-fed animal products compared with 17.8% for chicken thighs fed with GM corn. Therefore, the WTP values of GM animal foods were lower than GM plant foods and ornamental products.

scientific communication and education↗

bioRxiv2023

Zinc finger domains bind low-complexity domain polymers

Self-association of low-complexity protein sequences (LC domains) is important for polymer formation. Several molecular chaperones are involved in the regulation of LC domain polymer formation. However, the mechanisms underlying cell recognition of LC domain polymers remain unclear. Here we show that zinc finger domains (ZnFs) bind LC domains of RNA-binding proteins in a cross-{beta} polymer-dependent manner. ZnFs bound to LC domain hydrogels and suppressed LC domain polymer formation. Moreover, ZnFs preferentially recognize LC domains in the polymeric state. These findings suggest that ZnFs act as physiological regulators of LC domain polymer formation.

biochemistry↗

bioRxiv2023

Method for Spatially Confined Stimulation by Retinal Scanning Displays: Are Blind Spots Really Blind?

Conventional displays, such as CRTs and LCDs, are commonly used to present and manipulate visual stimuli in many vision science studies. However, such displays pose difficulties when the goal is to constrain stimulation to specific retinal locations, so as to isolate their contribution to downstream effects. Scattered and refracted light can stimulate unintended areas, contaminating the outcomes. In this investigation, we evaluate a laser-based retinal scanning display for its ability to map and exclusively stimulate the retinal blind spot. This application stimulates melanopsin receptors inside the blind spot, separately from rod and cone photoreceptors, which lie outside the blind spot. This paper covers three experiments: 1. The initial exploratory observations; 2. the examination of pupillary responses, and; 3. the inference of implicit visual perception arising from the blind spot. We aimed to simultaneously validate our technical methods, while increasing our understanding of the role of melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) in vision and implicit visual perception.

neuroscience↗

bioRxiv2021

Fungal effector SIB1 of Colletotrichum orbiculare has unique structural features and can suppress plant immunity in Nicotiana benthamiana

Functional screening of effector candidates using a transient expression assay in Nicotiana benthamiana identified two virulence-related effectors, named SIB1 and SIB2 (Suppression of Immunity in N. benthamiana), of an anthracnose fungus Colletotrichum orbiculare, which infects both cucurbits and N. benthamiana. Agrobacterium-mediated transient expression of SIB1 or SIB2 increased the susceptibility of N. benthamiana to C. orbiculare, which suggested these effectors can suppress immune responses in N. benthamiana. The presence of SIB1 and SIB2 homologs was found to be limited to the genus Colletotrichum. SIB1 suppressed both the generation of reactive oxygen species (ROS) triggered by the bacterial pathogen-associated molecular pattern (PAMP), flg22, and the cell death response triggered by the Phytophthora infestans INF1 elicitin in N. benthamiana. We determined the NMR-based structure of SIB1 to obtain its structural insights. The three-dimensional structure of SIB1 comprises five {beta}-strands, each containing three disulfide bonds. The overall conformation was found to be a cylindrical shape, such as the well-known antiparallel {beta}-barrel structure. However, the {beta}-strands were found to display a unique topology, one pair of these {beta}-strands formed a parallel {beta}-sheet. These results suggest that the effector SIB1 present in Colletotrichum fungi has unique structural features and can suppress PAMP-triggered immunity (PTI) in N. benthamiana.

microbiology↗

bioRxiv2020

Red-beet betalain pigments inhibit amyloid-beta aggregation and prevent the progression of Alzheimer's disease in a Caenorhabditis elegans model

BACKGROUNDBetalain pigments are mainly produced by plants in the order Caryophyllales. Recent interest in the biological functions of betalain pigments has increased with antioxidant, anti-inflammatory, and anticancer activities reported. RESULTSWe investigated the effects of betalain pigments derived from red-beet on amyloid-{beta} (A{beta}) aggregation, a cause of Alzheimers disease. Inhibition of A{beta} aggregation against A{beta}40 and A{beta}42 by betalain pigments in vitro was demonstrated by the Thioflavin T fluorescence assay, circular dichroism spectroscopy analysis and transmission electron microscopic observations. Moreover, we examined the ability of betalain pigments to interfere with A{beta} toxicity by using the transgenic Caenorhabditis elegans strain CL2006, which expresses the human A{beta}42 protein intracellularly within the body wall muscle and responds to A{beta}-toxicity with paralysis. Treatment with 50 M betalain pigments significantly delayed the paralysis of Caenorhabditis elegans. CONCLUSIONThese results suggest that betalain pigments reduce A{beta}-induced toxicity by inhibiting A{beta} aggregation and may lead to their use as inhibitors of A{beta} aggregation.

pharmacology and toxicology↗

bioRxiv2020

Production of ORF8 protein from SARS-CoV-2 using an inducible virus-mediated expression-system in suspension-cultured tobacco BY-2 cells

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which spread worldwide in 2020, is an urgent problem to be overcome. The ORF8 of SARS-CoV-2 has been suggested to be associated with the symptoms of COVID-19, according to reports of clinical studies. However, little is known about the function of ORF8. As one of the ways to advance the functional analysis of ORF8, mass production of ORF8 with the correct three-dimensional structure is necessary. In this study, we attempted to produce ORF8 protein by chemically inducible protein production system using tobacco BY-2 cells. An ORF8-producing line was generated by the Agrobacterium method. As a result, the production of ORF8 of 8.8 {+/-} 1.4 mg/L of culture medium was confirmed. SDS-PAGE and nuclear magnetic resonance (NMR) analysis confirmed that the ORF8 produced by this system is a dimeric form with a single structure, unlike that produced in Escherichia coli. Furthermore, it was suggested that the ORF8 produced by this system was glycosylated. Through this study, we succeeded in producing ORF8 folded into a single structure in a chemically inducible protein production system using tobacco BY-2 cells. It is expected that the functional analysis of ORF8 will be advanced using the ORF8 produced by this system and that it will greatly contribute to the development of antibodies and therapeutic agents targeting ORF8.

plant biology↗

bioRxiv2020

Recovery of cryo-injured rabbit urethras by biofabricated C-shaped adipose-derived mesenchymal cell structures

Urethral tissue damage can cause stress urinary incontinence or urinary retention, and there are few long-term, effective treatments. For structural and functional recovery of urethral tissues, we designed and constructed C-shaped structures composed of adipose-derived mesenchymal cells (AMCs) by using a three-dimensional (3D)-bioprinter system, which could be transplanted in damaged urethras without obstructing the lumen. We determined if transplantation of the biofabricated structures could reconstruct the urethral tissues. AMCs were harvested from rabbits, cultured and labeled with PKH26 to form spheroids. The spheroids were assembled on a custom-designed C-shaped support by a 3D bioprinter. Urethras of rabbits were cryo-injured by spraying with liquid nitrogen for 20 seconds, incised and biofabricated structure was autologously transplanted. Control rabbits were treated similarly but without transplantation structure. Two and four weeks after surgery, the control urethras were partially constricted; however, the structure-transplanted urethras were patent. The AMCs within the structures differentiated into skeletal muscle, smooth muscle, nerve, or endothelial cells. Some cells contained growth factors and cytokines. Therefore, biofabricated C-shaped AMC structures have potential to be an effective treatment for urethral recovery. Summary StatementThree-dimensional bioprinter was used to biofabricate novel C-shaped structures composed of adipose-derived mesenchymal cells (AMCs) and have the potential to be an effective treatment for urethral recovery.

bioengineering↗

bioRxiv2018

National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB): Outline and Patient-Matching Technique

BackgroundThe National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) is a comprehensive database of health insurance claims data under Japans National Health Insurance system. The NDB uses two types of personal identification variables (referred to in the database as \"ID1\" and \"ID2\") to link the insurance claims of individual patients. However, the information entered against these ID variables is prone to change for several reasons, such as when claimants find or change employment, or due to variations in the spelling of their name. In the present study, we developed a new patient-matching technique that improves upon the existing system of using ID1 and ID2 variables. We also sought to validate a new personal ID variable (ID0) that we propose in order to enhance the efficiency of patient matching in the NDB database.\n\nMethodsOur study targeted data from health insurance claims filed between April 2013 and March 2016 for hospitalization, combined diagnostic procedures, outpatient treatment, and dispensing of prescription medication. We developed a new patient-matching algorithm based on the ID1 and ID2 variables, as well as variables for treatment date and clinical outcome. We then attempted to validate our algorithm by comparing the number of patients identified by patient matching with the current ID1 variable and our proposed ID0 variable against the estimated patient population as of 1 October 2015.\n\nResultsThe numbers of patients in each sex and age group that were identified with the ID0 variable were lower than those identified using the ID1 variable. By using the ID0 variable, we were able to reduce the number of duplicate records for male and female patients by 5.8% and 6.4%, respectively. The numbers of children, adults older than 75 years, and women of reproductive age identified using the ID1 patient-matching variable were all higher than their corresponding estimates. Conversely, the numbers of these patients identified with the ID0 patient-matching variable were all within their corresponding estimates.\n\nConclusionOur findings show that the proposed ID0 variable delivers more precise patient-matching results than the existing ID1 variable. The ID0 variable is currently the best available technique for patient matching in the NDB database. Future patient population estimates should therefore rely on the ID0 variable instead of the ID1 variable.

epidemiology↗