Publications by authors named "Junko Sasaki"

Voltage-sensing phosphatase (VSP) exhibits voltage-dependent phosphatase activity toward phosphoinositides. VSP generates a specialized phosphoinositide environment in mammalian sperm flagellum. However, the voltage-sensing mechanism of VSP in spermatozoa is not yet characterized.

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H3.1 histone is predominantly synthesized and enters the nucleus during the G1/S phase of the cell cycle, as a new component of duplicating nucleosomes. Here, we found that p53 is necessary to secure the normal behavior and modification of H3.

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A hallmark of fetal alcohol spectrum disorders (FASD) is neurobehavioral deficits that still do not have effective treatment. Here, we present that reduction of Apolipoprotein E (APOE) is critically involved in neurobehavioral deficits in FASD. We show that prenatal alcohol exposure (PAE) changes chromatin accessibility of Apoe locus, and causes reduction of APOE levels in both the brain and peripheral blood in postnatal mice.

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Background: Numerous studies demonstrated the risk factors for urological complications in patients with diabetes before sodium-glucose co-transporter 2 inhibitor (SGLT2i) became commercially available. This study aimed to comprehensively investigate urological characteristics in patients with type 2 diabetes (T2DM) after SGLT2i became commercially available.

Methods: We examined 63 outpatients with T2DM suspected of bacteriuria based on urinary sediment examinations.

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Severity of neurobehavioral deficits in children born from adverse pregnancies, such as maternal alcohol consumption and diabetes, does not always correlate with the adversity's duration and intensity. Therefore, biological signatures for accurate prediction of the severity of neurobehavioral deficits, and robust tools for reliable identification of such biomarkers, have an urgent clinical need. Here, we demonstrate that significant changes in the alternative splicing (AS) pattern of offspring lymphocyte RNA can function as accurate peripheral biomarkers for motor learning deficits in mouse models of prenatal alcohol exposure (PAE) and offspring of mother with diabetes (OMD).

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The PIP/PI3K network is a central regulator of metabolism and is frequently activated in cancer, commonly by loss of the PIP/PI(3,4)P phosphatase, PTEN. Despite huge research investment, the drivers of the PI3K network in normal tissues and how they adapt to overactivation are unclear. We find that in healthy mouse prostate PI3K activity is driven by RTK/IRS signaling and constrained by pathway feedback.

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Phosphoinositides (PIPs) act as intracellular signaling molecules that regulate various cellular processes. Abnormalities in PIP metabolism cause various pathological conditions, including neurodegenerative diseases, cancer and immune disorders. Several neurological diseases with diverse phenotypes, such as ataxia with cerebellar atrophy or intellectual disability without brain malformation, are caused by mutations in INPP4A, which encodes a phosphoinositide phosphatase.

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The genetic associations of TREM2 loss-of-function variants with Alzheimer disease (AD) indicate the protective roles of microglia in AD pathogenesis. Functional deficiencies of TREM2 disrupt microglial clustering around amyloid β (Aβ) plaques, impair their transcriptional response to Aβ, and worsen neuritic dystrophy. However, the molecular mechanism underlying these phenotypes remains unclear.

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Body temperature in homeothermic animals does not remain constant but displays a regular circadian fluctuation within a physiological range (e.g., 35°C-38.

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(Purpose) Surgical positioning injury (SPI) is a cutaneous, musculoskeletal, neurological, or vascular injury resulting from the position of the patient during surgery. We performed a retrospective study using incident reporting system to examine the incidence of SPI at our hospital. (Materials and methods) Among anesthesiology managed surgical cases, SPI cases reported in the incident reporting system between 2012 and 2017 were examined.

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Planar cell polarity (PCP) regulates the orientation of external structures. A core group of proteins that includes Frizzled forms the heart of the PCP regulatory system. Other PCP mechanisms that are independent of the core group likely exist, but their underlying mechanisms are elusive.

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Introduction: Primary aldosteronism (PA) is a common disease. Especially in unilateral PA (UPA), the risk of cardiovascular disease is high and proper localization is important. Adrenal vein sampling (AVS) is commonly used to localize PA, but its availability is limited.

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Epithelial cells provide cell-cell adhesion that is essential to maintain the integrity of multicellular organisms. Epithelial cell-characterizing proteins, such as epithelial junctional proteins and transcription factors are well defined. However, the role of lipids in epithelial characterization remains poorly understood.

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Aim: Zinc, an essential trace element, has various functions in humans. Zinc deficiency is associated with the elderly, patients with diabetes, and patients with frailty, a common geriatric syndrome. As few studies have reported the effects of anti-diabetic medication on zinc levels, we examined serum zinc concentrations in patients with diabetes and their correlation with anti-diabetic medications, especially in the elderly and patients with frailty, in Japan.

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Phosphoinositides are a family of membrane lipids essential for many biological and pathological processes. Due to the existence of multiple phosphoinositide regioisomers and their low intracellular concentrations, profiling these lipids and linking a specific acyl variant to a change in biological state have been difficult. To enable the comprehensive analysis of phosphoinositide phosphorylation status and acyl chain identity, we develop PRMC-MS (Phosphoinositide Regioisomer Measurement by Chiral column chromatography and Mass Spectrometry).

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Membrane contact sites (MCSs) serve as a zone for nonvesicular lipid transport by oxysterol-binding protein (OSBP)-related proteins (ORPs). ORPs mediate lipid countertransport, in which two distinct lipids are transported counterdirectionally. How such lipid countertransport controls specific biological functions, however, remains elusive.

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The voltage-sensing phosphatase (VSP) is a unique protein that shows voltage-dependent phosphoinositide phosphatase activity. Here we report that VSP is activated in mice sperm flagellum and generates a unique subcellular distribution pattern of PtdIns(4,5)P Sperm from VSP mice show more Ca influx upon capacitation than VSP mice and abnormal circular motion. VSP-deficient sperm showed enhanced activity of Slo3, a PtdIns(4,5)P-sensitive K channel, which selectively localizes to the principal piece of the flagellum and indirectly enhances Ca influx.

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Phosphoinositides (PIPs) participate in many cellular processes, including cancer progression; however, the metabolic features of PIPs associated with prostate cancer (PCa) are unknown. We investigated PIPs profiles in PTEN-deficient prostate cancer cell lines, human prostate tissues obtained from patients with PCa and benign prostate hyperplasia (BPH) specimens using mass spectrometry. In immortalized normal human prostate PNT1B cells, PTEN deficiency increased phosphatidylinositol tris-phosphate (PIP) and decreased phosphatidylinositol mono- and bis-phosphate (PIP and PIP), consistent with PTEN's functional role as a PI(3,4,5)P 3-phosphatase.

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Endocytosis mediates the internalization and ingestion of a variety of endogenous or exogenous substances, including virus particles, under the control of intracellular signaling pathways. We have previously reported that the complex formed between the small GTPase Ras and phosphoinositide 3-kinase (PI3K) translocates from the plasma membrane to endosomes, signaling from which thereby regulates clathrin-independent endocytosis, endosome maturation, influenza virus internalization, and infection. However, the molecular mechanism by which the Ras-PI3K complex is recruited to endosomes remains unclear.

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Article Synopsis
  • Lysophosphatidylinositol-acyltransferase-1 (LPIAT1) plays a crucial role in transferring arachidonoyl-CoA to lysophosphoinositides, with its deficiency causing severe brain and liver issues in mice, though the underlying molecular reasons are unclear.
  • Researchers created LPIAT1-deficient Raw264.7 macrophages using shRNA and CRISPR/Cas9 to study its effects, discovering a significant reduction of specific phosphoinositide species, particularly PtdInsP.
  • The LPIAT1-deficient cells showed abnormal, prolonged calcium oscillations in response to UDP stimulation, suggesting these irregularities might contribute to increased liver inflammation related to LPIAT1
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PIKfyve, VAC14, and FIG4 form a complex that catalyzes the production of PI(3,5)P2, a signaling lipid implicated in process ranging from lysosome maturation to neurodegeneration. While previous studies have identified VAC14 and FIG4 mutations that lead to both neurodegeneration and coat color defects, how PIKfyve regulates melanogenesis is unknown. In this study, we sought to better understand the role of PIKfyve in melanosome biogenesis.

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The PI3K signaling pathway regulates cell growth and movement and is heavily mutated in cancer. Class I PI3Ks synthesize the lipid messenger PI(3,4,5)P. PI(3,4,5)P can be dephosphorylated by 3- or 5-phosphatases, the latter producing PI(3,4)P.

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Objective: Neutrophil extracellular traps (NETs) are peculiar structures composed of the externalized chromatin with intracellular proteins and formed by activated neutrophils in a reactive oxygen species (ROS)-dependent manner. Aberrant NETs are considered to be autoantigens for anti-neutrophil cytoplasmic antibodies (ANCAs) underling the development of microscopic polyangiitis (MPA). However, little is known regarding the therapeutic efficacy of in vivo inhibition of NET formation (NETosis) on MPA pathogenesis.

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Docosahexaenoic acid (DHA) has essential roles in photoreceptor cells in the retina and is therefore crucial to healthy vision. Although the influence of dietary DHA on visual acuity is well known and the retina has an abundance of DHA-containing phospholipids (PL-DHA), the mechanisms associated with DHA's effects on visual function are unknown. We previously identified lysophosphatidic acid acyltransferase 3 (LPAAT3) as a PL-DHA biosynthetic enzyme.

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