Publications by authors named "Satoru Koyanagi"

Defects in Aryl hydrocarbon receptor nuclear translocator-like 1 (ARNTL), a central component of the circadian clock mechanism, may promote or inhibit the induction of inflammation by monocytes/macrophages, with varying effects on different diseases. However, ARNTL's role in monocytes/macrophages under chronic kidney disease (CKD), which presents with systemic inflammation, is unclear. Here, we report that the expression of in monocytes promoted CKD-induced cardiac damage.

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Malignant cells exhibit a high demand for amino acids to sustain their abnormal proliferation. Particularly, the intracellular accumulation of cysteine is often observed in cancer cells. Previous studies have shown that deprivation of intracellular cysteine in cancer cells results in the accumulation of lipid peroxides in the plasma membrane and induction of ferroptotic cell death, indicating that cysteine plays a critical role in the suppression of ferroptosis.

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Background: The metabolic reprogramming of amino acids is critical for cancer cell growth and survival. Notably, intracellular accumulation of cysteine is often observed in various cancers, suggesting its potential role in alleviating the oxidative stress associated with rapid proliferation. The liver is the primary organ for cysteine biosynthesis, but much remains unknown about the metabolic alterations of cysteine and their mechanisms in hepatocellular carcinoma cells.

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Among the various RNA modifications, adenosine-to-inosine RNA editing, catalyzed by adenosine deaminase acting on RNA (ADAR) family, ADAR1 and ADAR2, is the most common nucleotide conversion in mammalian cells. The pathological relevance of ADAR expression has been highlighted in recent human genetic studies. Low expression of the ADAR2 gene is correlated with a poor prognosis in breast cancer patients, but the underlying mechanism remains enigmatic.

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The chemotherapeutic agent tegafur, a prodrug that prolongs the half-life of fluorouracil (5-FU), exerts antitumor effects against various cancers. Since tegafur is metabolized to 5-FU by CYP2A6 in the liver, the expression of CYP2A6 determines the effect of tegafur. Here, we report that the expression rhythm of Cyp2a5, a homolog of human CYP2A6, in female mice causes dosing time-dependent differences in tegafur metabolism.

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A problem for patients with diabetes is the rise of complications, such as peripheral neuropathy, nephropathy, and retinopathy. Among them, peripheral neuropathy, characterized by numbness and/or hypersensitivity to pain in the extremities, is likely to develop in the early stages of diabetes. Empagliflozin (EMPA), a sodium-glucose cotransporter-2 inhibitor, exerts hypoglycemic effects by preventing glucose reabsorption in proximal tubular cells.

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Chronic kidney disease (CKD) induces cardiac inflammation and fibrosis and reduces survival. We previously demonstrated that G protein-coupled receptor 68 (GPR68) promotes cardiac inflammation and fibrosis in mice with 5/6 nephrectomy (5/6Nx) and patients with CKD. However, no method of GPR68 inhibition has been found that has potential for therapeutic application.

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Article Synopsis
  • Prostaglandins are compounds that affect biological rhythms by activating specific receptors, but the relationship between the prostaglandin F receptor and these rhythms is not well understood.
  • Research on mutant mice showed that their locomotor period lengths were longer in constant dark conditions compared to normal mice, along with altered expression of clock genes in the suprachiasmatic nucleus and liver.
  • The study suggests that plasma levels of prostaglandin F exhibit a circadian rhythm, which may influence the expression of clock genes, indicating that drugs targeting this pathway could impact biological clock cycles.
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Article Synopsis
  • * In a study, mice lacking a core clock component did not develop heightened sensitivity to pain after nerve injury, unlike typical male mice.
  • * Increased expression of α1D-adrenergic receptors in these clock-deficient mice led to higher production of an endocannabinoid (2-AG), which helped reduce pain sensitivity, indicating a potential interaction between the circadian clock and pain regulation.
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Although vancomycin (VCM)-frequently used to treat drug-resistant bacterial infections-often induces acute kidney injury (AKI), discontinuation of the drug is the only effective treatment; therefore, analysis of effective avoidance methods is urgently needed. Here, we report the differences in the induction of AKI by VCM in 1/2-nephrectomized mice depending on the time of administration. Despite the lack of difference in the accumulation of VCM in the kidney between the light (ZT2) and dark (ZT14) phases, the expression of AKI markers due to VCM was observed only in the ZT2 treatment.

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Mammalians' circadian pacemaker resides in the paired suprachiasmatic nuclei (SCN). SCN control biological rhythms such as the sleep-wake rhythm and homeostatic functions of steroid hormones and their receptors. Alterations in these biological rhythms are implicated in the outcomes of pathogenic conditions such as depression, diabetes, and cancer.

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Proteins localize to their respective organelles in cells. This localization is changed by activation or repression in response to signal transduction. Therefore, the appropriate intracellular localization of proteins is important for their functions to be exerted.

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Chronic kidney disease (CKD) induces an imbalance in the intestinal microbiota, affecting various physiological functions and leading to cardiovascular inflammation and fibrosis. However, the cardiotoxic impact of intestinal microbiota-derived uremic substances in advanced renal dysfunction remains unexplored. Therefore, we developed a 5/6 nephrectomy (5/6Nx) mouse model to investigate the intestinal microbiota and the effects of administering vancomycin (VCM) on the microbiota and the cardiac pathology associated with CKD.

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Neuropathic pain associated with cancers is caused by tumor growth compressing and damaging nerves, which would also be enhanced by inflammatory factors through sensitizing nociceptor neurons. A troublesome hallmark symptom of neuropathic pain is hypersensitivity to innocuous stimuli, a condition known as "tactile allodynia", which is often refractory to NSAIDs and opioids. The involvement of chemokine CCL2 (monocyte chemoattractant protein-1) in cancer-evoked neuropathic pain is well established, but opinions remain divided as to whether CCL2 is involved in the production of tactile allodynia with tumor growth.

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Diurnal oscillations in the expression of several types of cell surface transporters have been demonstrated in the intestinal epithelial cells, which are mainly generated at transcriptional or degradation processes. Concentrative nucleoside transporter-2 (CNT2) is expressed at the apical site of intestinal epithelial cells and contributes to the uptake of nucleosides and their analogs from the intestinal lumen into the epithelial cells. In this study, we demonstrated that the localization of CNT2 protein in the plasma membrane of mouse intestinal epithelial cells exhibited a diurnal oscillation without changing its protein level in the whole cell.

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Renewal of retinal photoreceptor outer segments is conducted through daily shedding of distal photoreceptor outer segment tips and subsequent their phagocytosis by the adjacent retinal pigment epithelium (RPE) monolayer. Dysregulation of the diurnal clearance of photoreceptor outer segment tips has been implicated in age-related retinal degeneration, but it remains to be clarified how the circadian phagocytic activity of RPE cells is modulated by senescence. In this study, we used the human RPE cell line ARPE-19 to investigate whether hydrogen peroxide (HO)-induced senescence in ARPE-19 cells alters the circadian rhythm of their phagocytic activity.

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Detection of metabolic activity enables us to reveal the inherent metabolic state of cells and elucidate mechanisms underlying cellular homeostasis and growth. However, a fluorescence approach for the study of metabolic pathways is still largely unexplored. Herein, we have developed a new chemical probe for the fluorescence-based detection of fatty acid β-oxidation (FAO), a key process in lipid catabolism, in cells and tissues.

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(1) Background: Oxaliplatin is used as first-line chemotherapy not only for colorectal cancer but also for gastric and pancreatic cancers. However, it induces peripheral neuropathy with high frequency as an adverse event, and there is no effective preventive or therapeutic method. (2) Methods: The effects of omeprazole, a proton pump inhibitor (PPI), on oxaliplatin-induced peripheral neuropathy (OIPN) was investigated using an in vivo model and a real-world database.

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Clock genes, circadian pacemaker resides in the paired suprachiasmatic nuclei (SCN), control various circadian rhythms in many biological processes such as physiology and behavior. Clock gene regulates many diseases such as cancer, immunological dysfunction, metabolic syndrome and sleep disorders etc. Chronotherapy is especially relevant, when the risk and/or intensity of the symptoms of disease vary predicably over time as exemplified by allergic rhinitis, arthritis, asthma, myocardial infarction, congestive heart failure, stroke, and peptic ulcer disease.

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Multidrug resistance-associated protein 4 (MRP4), a member of the C subfamily of ATP-binding cassette transporters, is highly expressed in the kidneys of mammals and is responsible for renal elimination of numerous drugs. Adenosine deaminase acting on RNA 1 (ADAR1) has been reported to regulate gene expression by catalyzing adenosine-to-inosine RNA editing reactions; however, potential roles of ADAR1 in the regulation of MRP4 expression have not been investigated. In this study, we found that downregulation of ADAR1 increased the expression of MRP4 in human renal cells at the posttranscriptional level.

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Unlabelled: Cancer cells have acquired several pathways to escape from host immunity in the tumor microenvironment. Programmed death 1 (PD-1) receptor and its ligand PD-L1 are involved in the key pathway of tumor immune escape, and immune checkpoint therapy targeting PD-1 and PD-L1 has been approved for the treatment of patients with certain types of malignancies. Although PD-1 is a well-characterized receptor on T cells, the immune checkpoint receptor is also expressed on tumor-associated macrophages (TAM), a major immune component of the tumor microenvironment.

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In addition to diurnal rhythms in physiology and behavior, a variety of pathological conditions also exhibit marked day-night changes in symptom intensity, exemplified by allergic rhinitis, arthritis, asthma, myocardial infarction, congestive heart failure, stroke and chronic pain disorders. Currently, novel therapeutic approaches are facilitated by the development of chemical compounds targeted to key proteins that cause diurnal exacerbation of pathological events. Neuropathic pain is a chronic condition that occurs by tumor-induced nerve compression, cancer cell infiltration into the nerve, diabetes and herpes virus infection.

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Daily rhythmic variations in biological functions affect the efficacy and/or toxicity of drugs: a large number of drugs cannot be expected to exhibit the same potency at different administration times. The "circadian clock" is an endogenous timing system that broadly regulates metabolism, physiology and behavior. In mammals, this clock governs the oscillatory expression of the majority of genes with a period length of approximately 24 h.

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Dysfunction of the circadian clock has been implicated in the pathogenesis of cardiovascular disease. The CLOCK protein is a core molecular component of the circadian oscillator, so that mice with a mutated Clock gene (Clk/Clk) exhibit abnormal rhythms in numerous physiological processes. However, here we report that chronic kidney disease (CKD)-induced cardiac inflammation and fibrosis are attenuated in Clk/Clk mice even though they have high blood pressure and increased serum angiotensin II levels.

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