研究者詳細 - 佐藤　達也

論文 - 佐藤　達也

分割表示 144 件中 101 - 120 件目／全件表示 >>

Nuclear translocation of MLKL enhances necroptosis by a RIP1/RIP3-independent mechanism in H9c2 cardiomyoblasts.

Shoya Ino, Toshiyuki Yano, Atsushi Kuno, Masaya Tanno, Hidemichi Kouzu, Tatsuya Sato, Tomohisa Yamashita, Wataru Ohwada, Arata Osanami, Toshifumi Ogawa, Yuki Toda, Masaki Shimizu, Tetsuji Miura

Journal of pharmacological sciences 151 ( 2 ) 134 - 143 2023年02月 [査読有り] [国内誌]

Accumulating evidence suggests that necroptosis of cardiomyocytes contributes to cardiovascular diseases. Lethal disruption of the plasma membrane in necroptosis is induced by oligomers of mixed lineage kinase domain-like (MLKL) that is translocated to the membrane from the cytosol. However, the role played by cytoplasmic-nuclear shuttling of MLKL is unclear. Here, we tested the hypothesis that translocation of MLKL to the nucleus promotes the necroptosis of cardiomyocytes. Activation of the canonical necroptotic signaling pathway by a combination of TNF-α and zVAD (TNF/zVAD) increased nuclear MLKL levels in a RIP1-activity-dependent manner in H9c2 cells, a rat cardiomyoblast cell line. By use of site-directed mutagenesis, we found a nuclear export signal sequence in MLKL and prepared its mutant (MLKL-L280/283/284A), though a search for a nuclear import signal was unsuccessful. MLKL-L280/283/284A localized to both the cytosol and the nucleus. Expression of MLKL-L280/283/284A induced necroptotic cell death, which was attenuated by GppNHp, an inhibitor of Ran-mediated nuclear import, but not by inhibition of RIP1 activity or knockdown of RIP3 expression. GppNHp partly suppressed H9c2 cell death induced by TNF/zVAD treatment. These results suggest that MLKL that is translocated to the nucleus via RIP1-mediated necroptotic signaling enhances the necroptosis of cardiomyocytes through a RIP1-/RIP3-independent mechanism.

Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts

Toshifumi Ogawa, Hidemichi Kouzu, Arata Osanami, Yuki Tatekoshi, Tatsuya Sato, Atsushi Kuno, Yugo Fujita, Shoya Ino, Masaki Shimizu, Yuki Toda, Wataru Ohwada, Toshiyuki Yano, Masaya Tanno, Takayuki Miki, Tetsuji Miura

Physiological Reports 11 ( 4 ) e15608 2023年02月 [査読有り] [国際誌]

Systemic branched-chain amino acid (BCAA) metabolism is dysregulated in cardiometabolic diseases. We previously demonstrated that upregulated AMP deaminase 3 (AMPD3) impairs cardiac energetics in a rat model of obese type 2 diabetes, Otsuka Long-Evans-Tokushima fatty (OLETF). Here, we hypothesized that the cardiac BCAA levels and the activity of branched-chain α-keto acid dehydrogenase (BCKDH), a rate-limiting enzyme in BCAA metabolism, are altered by type 2 diabetes (T2DM), and that upregulated AMPD3 expression is involved in the alteration. Performing proteomic analysis combined with immunoblotting, we discovered that BCKDH localizes not only to mitochondria but also to the endoplasmic reticulum (ER), where it interacts with AMPD3. Knocking down AMPD3 in neonatal rat cardiomyocytes (NRCMs) increased BCKDH activity, suggesting that AMPD3 negatively regulates BCKDH. Compared with control rats (Long-Evans Tokushima Otsuka [LETO] rats), OLETF rats exhibited 49% higher cardiac BCAA levels and 49% lower BCKDH activity. In the cardiac ER of the OLETF rats, BCKDH-E1α subunit expression was downregulated, while AMPD3 expression was upregulated, resulting in an 80% lower AMPD3-E1α interaction compared to LETO rats. Knocking down E1α expression in NRCMs upregulated AMPD3 expression and recapitulated the imbalanced AMPD3-BCKDH expressions observed in OLETF rat hearts. E1α knockdown in NRCMs inhibited glucose oxidation in response to insulin, palmitate oxidation, and lipid droplet biogenesis under oleate loading. Collectively, these data revealed previously unrecognized extramitochondrial localization of BCKDH in the heart and its reciprocal regulation with AMPD3 and imbalanced AMPD3-BCKDH interactions in OLETF. Downregulation of BCKDH in cardiomyocytes induced profound metabolic changes that are observed in OLETF hearts, providing insight into mechanisms contributing to the development of diabetic cardiomyopathy.

SIRT2 inhibition protects against cardiac hypertrophy and heart failure.

Xiaoyan Yang, Hsiang-Chun Chang, Yuki Tatekoshi, Maryam Balibegloo, Rongxue Wu, Chunlei Chen, Tatsuya Sato, Jason Shapiro, Hossein Ardehali

bioRxiv : the preprint server for biology 2023年01月 [国際誌]

Sirtuins (SIRT) exhibit deacetylation or ADP-ribosyltransferase activity and regulate a wide range of cellular processes in the nucleus, mitochondria and cytoplasm. The role of the only sirtuin that resides in the cytoplasm, SIRT2, in the development of heart failure (HF) and cardiac hypertrophy is not known. In this paper, we show that the hearts of mice with deletion of Sirt2 ( Sirt2 -/- ) display improved cardiac function after ischemia-reperfusion (I/R) and pressure overload (PO), suggesting that SIRT2 exerts maladaptive effects in the heart in response to stress. Similar results were obtained in mice with cardiomyocyte-specific Sirt2 deletion. Mechanistic studies suggest that SIRT2 modulates cellular levels and activity of nuclear factor (erythroid-derived 2)-like 2 (NRF2), which results in reduced expression of antioxidant proteins. Deletion of Nrf2 in the hearts of Sirt2 -/- mice reversed protection after PO. Finally, treatment of mouse hearts with a specific SIRT2 inhibitors reduces cardiac size and attenuates cardiac hypertrophy in response to PO. These data indicate that SIRT2 has detrimental effects in the heart and plays a role in the progression of HF and cardiac hypertrophy, which makes this protein a unique member of the SIRT family. Additionally, our studies provide a novel approach for treatment of cardiac hypertrophy by targeting SIRT2 pharmacologically, providing a novel avenue for the treatment of this disorder.

Unexpected Crosslinking Effects of a Human Thyroid Stimulating Monoclonal Autoantibody, M22, with IGF1 on Adipogenesis in 3T3L-1 Cells

Araya Umetsu, Tatsuya Sato, Megumi Watanabe, Yosuke Ida, Masato Furuhashi, Yuri Tsugeno, Hiroshi Ohguro

International Journal of Molecular Sciences 2023年01月 [査読有り]

G-Protein-Coupled Receptors Mediate Modulations of Cell Viability and Drug Sensitivity by Aberrantly Expressed Recoverin 3 within A549 Cells

Hanae Ichioka, Yoshihiko Hirohashi, Tatsuya Sato, Masato Furuhashi, Megumi Watanabe, Yosuke Ida, Fumihito Hikage, Toshihiko Torigoe, Hiroshi Ohguro

International Journal of Molecular Sciences 24 ( 1 ) 2023年01月 [査読有り] [国際誌]

To elucidate the currently unknown molecular mechanisms responsible for the aberrant expression of recoverin (Rec) within cancerous cells, we examined two-dimensional (2D) and three-dimensional (3D) cultures of Rec-negative lung adenocarcinoma A549 cells which had been transfected with a plasmid containing human recoverin cDNA (A549 Rec) or an empty plasmid as a mock control (A549 MOCK). Using these cells, we measured cytotoxicity by several anti-tumor agents (2D), cellular metabolism including mitochondrial and glycolytic functions by a Seahorse bio-analyzer (2D), the physical properties, size and stiffness of the 3D spheroids, trypsin sensitivities (2D and 3D), and RNA sequencing analysis (2D). Compared with the A549 MOCK, the A549 Rec cells showed (1) more sensitivity toward anti-tumor agents (2D) and a 0.25% solution of trypsin (3D); (2) a metabolic shift from glycolysis to oxidative phosphorylation; and (3) the formation of larger and stiffer 3D spheroids. RNA sequencing analysis and bioinformatic analyses of the differentially expressed genes (DEGs) using Gene Ontology (GO) enrichment analysis suggested that aberrantly expressed Rec is most likely associated with several canonical pathways including G-protein-coupled receptor (GPCR)-mediated signaling and signaling by the cAMP response element binding protein (CREB). The findings reported here indicate that the aberrantly expressed Rec-induced modulation of the cell viability and drug sensitivity may be GPCR mediated.

Elevated circulating level of β-aminoisobutyric acid (BAIBA) in heart failure patients with type 2 diabetes receiving sodium-glucose cotransporter 2 inhibitors.

Satoshi Katano, Toshiyuki Yano, Hidemichi Kouzu, Ryohei Nagaoka, Ryo Numazawa, Kotaro Yamano, Yusuke Fujisawa, Katsuhiko Ohori, Nobutaka Nagano, Takefumi Fujito, Ryo Nishikawa, Wataru Ohwada, Masaki Katayose, Tatsuya Sato, Atsushi Kuno, Masato Furuhashi

Cardiovascular diabetology 21 ( 1 ) 285 - 285 2022年12月 [査読有り] [国際誌]

AIMS: The mechanism by which a sodium-glucose cotransporter inhibitor (SGLT2i) induces favorable effects on diabetes and cardiovascular diseases including heart failure (HF) remains poorly understood. Metabolomics including amino acid profiling enables detection of alterations in whole body metabolism. The aim of this study was to determine whether plasma amino acid profiles are modulated by SGLT2i use in HF patients with type 2 diabetes mellitus (T2DM). METHODS: We retrospectively examined 81 HF patients with T2DM (68 ± 11 years old; 78% male). Plasma amino acid concentrations in a fasting state after stabilization of HF were determined using ultraperformance liquid chromatography. To minimize potential selection bias in the retrospective analyses, the differences in baseline characteristics between patients receiving an SGLT2i and patients not receiving an SGLT2i were controlled by using an inverse probability of treatment weighting (IPTW)-adjusted analysis. RESULTS: Of amino acids measurable in the present assay, plasma β-aminoisobutyric acid (BAIBA), an exercise-induced myokine-like molecule also known as 3-aminoisobutyric acid or 3-amino-2-methyproponic acid, was detected in 77% of all patients and the proportion of patients in whom plasma BAIBA was detected was significantly higher in patients receiving an SGLT2i than in patients not receiving an SGLT2i (93% vs. 67%, p = 0.01). Analyses in patients in whom plasma BAIBA was detected showed that plasma BAIBA concentration was significantly higher in patients receiving an SGLT2i than in patients not receiving an SGLT2i (6.76 ± 4.72 vs. 4.56 ± 2.93 nmol/ml, p = 0.03). In multivariate logistic regression analyses that were adjusted for age and sex, SGLT2i use was independently associated with BAIBA detection. The independent association between BAIBA and SGLT2i use remained after inclusion of body mass index, HF with reduced ejection fraction, ischemic etiology, renal function, NT-proBNP, albumin, hemoglobin, and HbA1c into the Cox proportional hazards model. When the differences in baseline characteristics between patients receiving an SGLT2i and patients not receiving an SGLT2i were controlled by using an IPTW-adjusted analysis, least squares mean of plasma BAIBA concentration was significantly higher in patients receiving an SGLT2i than in patients not receiving an SGLT2i. CONCLUSION: SGLT2i use is closely associated with increased circulating BAIBA concentration in HF patients with T2DM.

The Selective α1 Antagonist Tamsulosin Alters ECM Distributions and Cellular Metabolic Functions of ARPE 19 Cells in a Concentration-Dependent Manner.

Yosuke Ida, Tatsuya Sato, Megumi Watanabe, Araya Umetsu, Yuri Tsugeno, Masato Furuhashi, Fumihito Hikage, Hiroshi Ohguro

Bioengineering (Basel, Switzerland) 9 ( 10 ) 2022年10月 [査読有り] [国際誌]

The purpose of the present study was to examine the effect of the selective α1 antagonist tamsulosin (TAM) on human retinal pigment epithelium cells, ARPE 19. Two-dimension (2D) and three-dimension (3D) cultured ARPE 19 cells were used in the following characterizations: (1) ultrastructure by scanning electron microscopy (SEM) (2D); (2) barrier functions by transepithelial electrical resistance (TEER) measurements, and FITC-dextran permeability (2D); (3) real time cellular metabolisms by Seahorse Bioanalyzer (2D); (4) physical properties, size and stiffness measurements (3D); and (5) expression of extracellular matrix (ECM) proteins, including collagen1 (COL1), COL4, COL6 and fibronectin (FN) by qPCR and immunohistochemistry (2D and 3D). TAM induced significant effects including: (1) alteration of the localization of the ECM deposits; (2) increase and decrease of the TEER values and FITC-dextran permeability, respectively; (3) energy shift from glycolysis into mitochondrial oxidative phosphorylation (OXPHOS); (4) large and stiffened 3D spheroids; and (5) down-regulations of the mRNA expressions and immune labeling of most ECM proteins in a concentration-dependent manner. However, in some ECM proteins, COL1 and COL6, their immunolabeling intensities were increased at the lowest concentration (1 μM) of TAM. Such a discrepancy between the gene expressions and immunolabeling of ECM proteins may support alterations of ECM localizations as observed by SEM. The findings reported herein indicate that the selective α1 antagonist, TAM, significantly influenced ECM production and distribution as well as cellular metabolism levels in a concentration-dependent manner.

All Trans-Retinoic Acids Facilitate the Remodeling of 2D and 3D Cultured Human Conjunctival Fibroblasts.

Yuri Tsugeno, Tatsuya Sato, Megumi Watanabe, Megumi Higashide, Masato Furuhashi, Araya Umetsu, Soma Suzuki, Yosuke Ida, Fumihito Hikage, Hiroshi Ohguro

Bioengineering (Basel, Switzerland) 9 ( 9 ) 2022年09月 [査読有り] [国際誌]

Vitamin A derivative, all-trans-retinoic acid (ATRA), is known to be a potent regulator of the growth and differentiation of various types of cells. In the present study, the unidentified effects of ATRA on superficial and vertical spreading conjunctival scarring were examined. The study involved the use of two-dimensional (2D) and three-dimensional (3D) cultures of human conjunctival fibroblast (HconF) cells in the presence or absence of TGF-β2. The effects of ATRA (1 μM) on superficial or vertical spreading conjunctival scarring were evaluated by the barrier function by trans-endothelial electrical resistance (TEER) and FITC dextran permeability measurements and real-time metabolic analysis, as well as the physical properties, namely, the size and stiffness, of 3D spheroids, respectively. In addition, the expressions of several related molecules, including extracellular matrix (ECM) molecules, ECM modulators including a tissue inhibitor of metalloproteinases (TIMPs), matrix metalloproteinases (MMPs), and ER stress-related factors, were examined. ATRA significantly induced (1) an increase in TEER values and a decrease in FITC dextran permeability, respectively, in the 2D monolayers, and (2) relatively and substantially increased the size and stiffness, respectively, of the 3D spheroids. These ATRA-induced effects were further enhanced in the TGF-β2-treated cells, whereas the TGF-β2-induced enhancement in glycolytic capacity was canceled by the presence of ATRA. Consistent with these physical and morphological effects, the mRNA expressions of several molecules were significantly but differently induced between 2D and 3D cultures by ATRA, although the presence of TGF-β2 did not substantially affect these gene expression levels. The findings reported in this study indicate that ATRA may exacerbate both superficial and vertical conjunctival fibrosis spreading independently of TGF-β2-induced changes.

Benzalkonium Chloride, Even at Low Concentrations, Deteriorates Intracellular Metabolic Capacity in Human Conjunctival Fibroblasts

Yuri Tsugeno, Tatsuya Sato, Megumi Watanabe, Masato Furuhashi, Araya Umetsu, Yosuke Ida, Fumihito Hikage, Hiroshi Ohguro

Biomedicines 2022年09月

All-trans Retinoic Acids Synergistically and Beneficially Affect In Vitro Glaucomatous Trabecular Meshwork (TM) Models Using 2D and 3D Cell Cultures of Human TM Cells.

Megumi Watanabe, Tatsuya Sato, Yuri Tsugeno, Megumi Higashide, Masato Furuhashi, Araya Umetsu, Soma Suzuki, Yosuke Ida, Fumihito Hikage, Hiroshi Ohguro

International journal of molecular sciences 23 ( 17 ) 2022年08月 [査読有り] [国際誌]

We report herein on the effects of all-trans retinoic acid (ATRA) on two-dimensional (2D) and three-dimensional (3D) cultures of human trabecular meshwork (HTM) cells that were treated with transforming growth factor β2 (TGF-β2). In the presence of 5 ng/mL TGF-β2, the effects of ATRA on the following were observed: (1) the barrier function of the 2D HTM monolayers, as determined by trans-endothelial electrical resistance (TEER) and fluorescein isothiocyanate (FITC) dextran permeability measurements; (2) a Seahorse cellular bio-metabolism analysis; (3) physical properties, including the size and stiffness, of 3D spheroids; (4) the gene expression of extracellular matrix (ECM) molecules, ECM modulators including tissue inhibitor of metalloproteinases (TIMPs), matrix metalloproteinases (MMPs), tight junction (TJ)-related molecules, and endoplasmic reticulum (ER)-stress-related factors. ATRA significantly inhibited the TGF-β2-induced increase in the TEER values and FITC dextran permeability of the 2D monolayers, while an ATRA monotreatment induced similar effects as TGF-β2. A real-time metabolic analysis revealed that ATRA significantly inhibited the TGF-β2-induced shift in metabolic reserve from mitochondrial oxidative phosphorylation to glycolysis in 2D HTM cells, whereas ATRA alone did not induce significant metabolic changes. In contrast, ATRA induced the formation of substantially downsized and softer 3D spheroids in the absence and presence of TGF-β2. The different effects induced by ATRA toward 2D and 3D HTM cells were also supported by the qPCR analysis of several proteins as above. The findings reported here indicate that ATRA may induce synergistic and beneficial effects on TGF-β2-treated 2D- and 3D-cultured HTM cells; those effects varied significantly between the 2D and 3D cultures.

Brimonidine Modulates the ROCK1 Signaling Effects on Adipogenic Differentiation in 2D and 3D 3T3-L1 Cells

Araya Umetsu, Yosuke Ida, Tatsuya Sato, Megumi Watanabe, Yuri Tsugeno, Masato Furuhashi, Fumihito Hikage, Hiroshi Ohguro

Bioengineering 2022年07月 [査読有り]

An α2-Adrenergic Agonist, Brimonidine, Beneficially Affects the TGF-β2-Treated Cellular Properties in an In Vitro Culture Model

Megumi Watanabe, Tatsuya Sato, Yuri Tsugeno, Megumi Higashide, Masato Furuhashi, Araya Umetsu, Soma Suzuki, Yosuke Ida, Fumihito Hikage, Hiroshi Ohguro

Bioengineering ( {MDPI} {AG} ) 9 ( 7 ) 310 - 310 2022年07月 [査読有り]

Human Trabecular Meshwork (HTM) Cells Treated with TGF-β2 or Dexamethasone Respond to Compression Stress in Different Manners.

Megumi Watanabe, Tatsuya Sato, Yuri Tsugeno, Araya Umetsu, Soma Suzuki, Masato Furuhashi, Yosuke Ida, Fumihito Hikage, Hiroshi Ohguro

Biomedicines 10 ( 6 ) 2022年06月 [査読有り] [国際誌]

To characterize our recently established in vitro glaucomatous human trabecular meshwork (HTM) models using dexamethasone (DEX)- or TGF-β2-treated HTM cells, (1) two-dimensional (2D) cultured HTM cells were characterized by means of the real-time cellular metabolism analysis using a Seahorse analyzer, and (2) the effects of mechanical compression stresses toward the three-dimensional (3D) HTM spheroids were evaluated by analyzing the gene expression of several ECM proteins, inflammatory cytokines, and ER stress-related factors of those 3D HTM spheroid models. The results indicated that (1) the real-time cellular metabolism analysis indicated that TGF-β2 significantly induced an energy shift from mitochondrial oxidative phosphorylation (OXPHOS) into glycolysis, and DEX induced similar but lesser effects. In contrast, ROCK2 inhibition by KD025 caused a substantial reverse energy shift from glycolysis into OXPHOS. (2) Upon direct compression stresses toward the untreated control 3D HTM spheroids, a bimodal fluctuation of the mRNA expressions of ECM proteins was observed for 60 min, that is, initial significant upregulation (0-10 min) and subsequent downregulation (10-30 min) followed by another upregulation (30-60 min); those of inflammatory cytokines and ER stress-related factors were also bimodally changed. However, such compression stresses for 30 min toward TGF-β2- or DEX-treated 3D HTM spheroids induced downregulation of most of those of inflammatory cytokines and ER stress-related factors in addition to upregulation of COL1 and downregulation of FN. The findings presented herein indicate that (1) OXPHOS of the HTM cells was decreased or increased by TGF-β2 or DEX stimulation or ROCK2 inhibition, and (2) mechanical compression stresses toward 3D HTM spheroids may replicate acute, subacute, and chronic HTM models affected by elevated intraocular pressures.

SIRT1 in the cardiomyocyte counteracts doxorubicin-induced cardiotoxicity via regulating histone H2AX

Atsushi Kuno, Ryusuke Hosoda, Miki Tsukamoto, Tatsuya Sato, Hiromi Sakuragi, Nami Ajima, Yukika Saga, Kouhei Tada, Yoshiki Taniguchi, Naotoshi Iwahara, Yoshiyuki Horio

Cardiovascular Research ( Oxford University Press (OUP) ) 2022年03月 [査読有り] [国際誌]

Abstract Aims Cardiotoxicity by doxorubicin predicts worse prognosis of patients. Accumulation of damaged DNA has been implicated in doxorubicin-induced cardiotoxicity. SIRT1, an NAD+-dependent histone/protein deacetylase, protects cells by deacetylating target proteins. We investigated whether SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating Ser139 phosphorylation of histone H2AX, a critical signal of the DNA damage response. Methods and results Doxorubicin (5 mg/kg per week, x4) was administered to mice with intact SIRT1 (Sirt1f/f) and mice that lack SIRT1 activity in cardiomyocytes (Sirt1f/f; MHCcre/+). Reductions in left ventricular fractional shortening and ejection fraction by doxorubicin treatment were more severe in Sirt1f/f; MHCcre/+ than in Sirt1f/f. Myocardial expression level of type-B natriuretic peptide was 2.5-fold higher in Sirt1f/f; MHCcre/+ than in Sirt1f/f after doxorubicin treatment. Sirt1f/f; MHCcre/+ showed larger fibrotic areas and higher nitrotyrosine levels in the heart after doxorubicin treatment. Although doxorubicin-induced DNA damage evaluated by TUNEL staining was enhanced in Sirt1f/f; MHCcre/+, the myocardium from Sirt1f/f; MHCcre/+ showed blunted Ser139 phosphorylation of H2AX by doxorubicin treatment. In H9c2 cardiomyocytes, SIRT1 knockdown attenuated Ser139 phosphorylation of H2AX, increased DNA damage, and enhanced caspase-3 activation under doxorubicin treatment. Immunostaining revealed that acetylation level of H2AX at Lys5 was higher in hearts from Sirt1f/f; MHCcre/+. In H9c2 cells, acetyl-Lys5-H2AX level was increased by SIRT1 knockdown and reduced by SIRT1 overexpression. Ser139 phosphorylation in response to doxorubicin treatment was blunted in a mutant H2AX with substitution of Lys5 to Gln (K5Q) that mimics acetylated lysine compared with that in wild-type H2AX. Expression of K5Q-H2AX as well as S139A-H2AX, which cannot be phosphorylated at Ser139, augmented doxorubicin-induced caspase-3 activation. Treatment of mice with resveratrol, a SIRT1 activator, attenuated doxorubicin-induced cardiac dysfunction, which was associated with a reduction in acetyl-Lys5-H2AX level and a preserved phospho-Ser139-H2AX level. Conclusion These findings suggest that SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating H2AX phosphorylation through its deacetylation in cardiomyocytes. Translational perspective Doxorubicin-induced cardiotoxicity limits the further use of doxorubicin for cancer treatment and determines prognosis of patients. This work shows for the first time the protective effect of SIRT1, an NAD+-dependent deacetylase, on doxorubicin-induced cardiotoxicity using a genetically modified mouse model. We identified histone H2AX as a target of SIRT1 for proper DNA damage response. Therefore, DNA repair by SIRT1 could be a potential therapeutic target to attenuate doxorubicin cardiotoxicity. SIRT1 activity may also help to predict a risk of developing cardiotoxicity in patients treated with doxorubicin.

Role of Erythropoiesis-Stimulating Agents in Cardiovascular Protection in CKD Patients: Reappraisal of Their Impact and Mechanisms.

Tetsuji Miura, Tatsuya Sato, Toshiyuki Yano, Akira Takaguri, Takayuki Miki, Noritsugu Tohse, Keitaro Nishizawa

Cardiovascular drugs and therapy 2022年02月 [査読有り] [国際誌]

Erythropoiesis-stimulating agents (ESAs) have markedly reduced the need for blood transfusion for renal anemia and are included in standard therapies for patients with chronic kidney disease (CKD). Various protective effects of ESAs on the cardiovascular system have been discovered through basic research, and the effects have received much attention because the rates of cardiovascular events and mortality are high in CKD patients. However, randomized clinical trials did not provide strong evidence that ESAs exert cardioprotection in humans, including CKD patients. It is difficult to assess the cardioprotective effects of ESAs in CKD patients through the clinical data that has been reported to date because the relationship between hemoglobin level rather than ESA dose and cardiovascular event rates was examined in most studies. Interestingly, recent studies using a rat model of CKD showed that the infarct size-limiting effect of an ESA was lost when its dose was increased to a level that normalized blood hemoglobin levels, suggesting that the optimal dose of an ESA for myocardial protection is less than the dose required to normalize hemoglobin levels. Furthermore, animal models of traditional coronary risk factors or comorbidities were resistant to the cardioprotective effects of ESAs because of interruptions in signal-mediated mechanisms downstream of erythropoietin receptors. In this review, we briefly discuss basic and clinical data on the impact of anemia on coronary and systemic circulation, the effects of CKD on the cardiovascular system, and the multiple pharmacological actions of ESAs to examine whether the ESAs that are prescribed for renal anemia exert any cardioprotection in patients with CKD.

Successful therapeutic strategy for a patient with obese end-stage kidney disease by simultaneous laparoscopic sleeve gastrectomy and implantation of a buried peritoneal dialysis catheter: A case report.

Tomohisa Yamashita, Tatsuya Sato, Kazuyuki Yamamoto, Atsuko Abiko, Keitaro Nishizawa, Masahiro Matsuda, Yuma Ebihara, Takeshi Maehana, Toshiaki Tanaka, Toshiyuki Yano, Hironori Kobayashi

Frontiers in medicine 9 926652 - 926652 2022年 [査読有り] [国際誌]

For morbidly obese patients with end-stage kidney disease (ESKD), there are often difficulties in accessing, implementing, and maintaining kidney replacement therapy (KRT). Although recent weight-loss surgery has the potential to solve these problems, its therapeutic strategy and appropriate perioperative management for morbidly obese patients with ESKD have not been established. Here, we describe the case history of a 47-year-old man diagnosed with ESKD due to obesity-related glomerulopathy with an uncorrected estimated glomerular filtration rate (eGFR) of 16.1 ml/min. He hoped for kidney transplantation but was not eligible due to his high body mass index (BMI) (36.9 kg/m2). Therefore, a combination strategy for both attaining weight loss and preparing for KRT was needed. We performed modified laparoscopic sleeve gastrectomy (LSG) combined with a buried catheter for peritoneal dialysis (PD), which resulted in reduction of multiple surgical invasions while simultaneously preparing for PD. After these operations, his body mass dropped to below 30.0 kg/m2, making him a candidate for kidney transplantation, while maintaining PD. Finally, he was able to have kidney transplantation with success. Collectively, in this case, our novel therapeutic approach was able to avoid multiple surgeries, to assist catheter insertion by laparoscopy, and to provide optimal KRT for an obese patient with ESKD. Simultaneous LSG and implantation of a buried PD catheter may be a promising strategy for morbidly obese patients with ESKD.

Larger improvements in fatigue resistance and mitochondrial function with high- than with low-intensity contractions during interval training of mouse skeletal muscle.

Takashi Yamada, Iori Kimura, Yuki Ashida, Katsuyuki Tamai, Hiroyori Fusagawa, Noritsugu Tohse, Håkan Westerblad, Daniel C Andersson, Tatsuya Sato

FASEB journal 35 ( 11 ) e21988 2021年11月 [査読有り] [国際誌]

担当区分：最終著者

Interval training (IT) results in improved fatigue resistance in skeletal muscle mainly due to an increased aerobic capacity, which involves increased muscle mitochondrial content and/or improved mitochondrial function. We hypothesized that IT with high-intensity contractions is more effective in increasing mitochondrial function, and hence fatigue resistance, than low-intensity contractions. To study this hypothesis without interference from differences in muscle fiber recruitment obliged to occur during voluntary contractions, IT was performed with in situ supramaximal electrical stimulation where all muscle fibers are recruited. We compared the effect of IT with repeated low-intensity (20 Hz stimulation, IT20) and high-intensity (100 Hz stimulation, IT100) contractions on fatigue resistance and mitochondrial content and function in mouse plantar flexor muscles. Muscles were stimulated every other day for 4 weeks. The averaged peak torque during IT bouts was 4.2-fold higher with IT100 than with IT20. Both stimulation protocols markedly improved in situ fatigue resistance, although the improvement was larger with IT100. The citrate synthase activity, a biomarker of mitochondrial content, was similarly increased with IT20 and IT100. Conversely, increased expression of mitochondrial respiratory chain (MRC) complexes I, III, and IV was only observed with IT100 and this was accompanied by increases in MRC supercomplex formation and pyruvate-malate-driven state 3 respiration in isolated mitochondria. In conclusion, the IT-induced increase in fatigue resistance is larger with high-intensity than with low-intensity contractions and this is linked to improved mitochondrial function due to increased expression of MRC complexes and assembly of MRC supercomplexes.

Xanthine oxidoreductase-mediated injury is amplified by upregulated AMP deaminase in type 2 diabetic rat hearts under the condition of pressure overload.

Yusuke Igaki, Masaya Tanno, Tatsuya Sato, Hidemichi Kouzu, Toshifumi Ogawa, Arata Osanami, Toshiyuki Yano, Atsushi Kuno, Takayuki Miki, Takashi Nakamura, Tetsuji Miura

Journal of molecular and cellular cardiology 154 21 - 31 2021年05月 [査読有り] [国際誌]

BACKGROUND: We previously reported that upregulated AMP deaminase (AMPD) contributes to diastolic ventricular dysfunction via depletion of the adenine nucleotide pool in a rat model of type 2 diabetes (T2DM), Otsuka Long-Evans-Tokushima Fatty rats (OLETF). Meanwhile, AMPD promotes the formation of substrates of xanthine oxidoreductase (XOR), which produces ROS as a byproduct. Here, we tested the hypothesis that a functional link between upregulated AMPD and XOR is involved in ventricular dysfunction in T2DM rats. METHODS AND RESULTS: Pressure-volume loop analysis revealed that pressure overloading by phenylephrine infusion induced severer left ventricular diastolic dysfunction (tau: 14.7 ± 0.8 vs 12.5 ± 0.7 msec, left ventricular end-diastolic pressure: 18.3 ± 1.5 vs 12.2 ± 1.3 mmHg, p < 0.05) and ventricular-arterial uncoupling in OLETF than in LETO, non-diabetic rats, though the baseline parameters were comparable in the two groups. While the pressure overload did not affect AMPD activity, it increased XOR activity both in OLETF and LETO, with OLETF showing significantly higher XOR activity than that in LETO (347.2 ± 17.9 vs 243.2 ± 6.1 μg/min/mg). Under the condition of pressure overload, myocardial ATP level was lower, and levels of xanthine and uric acid were higher in OLETF than in LETO. Addition of exogenous inosine, a product of AMP deamination, to the heart homogenates augmented XOR activity. OLETF showed 68% higher tissue ROS levels and 47% reduction in mitochondrial state 3 respiration compared with those in LETO. Overexpression of AMPD3 in H9c2 cells elevated levels of hypoxanthine and ROS and reduced the level of ATP. Inhibition of XOR suppressed the production of tissue ROS and mitochondrial dysfunction and improved ventricular function under the condition of pressure overload in OLETF. CONCLUSIONS: The results suggest that increases in the activity of XOR and the formation of XOR substrates by upregulated AMPD contribute to ROS-mediated diastolic ventricular dysfunction at the time of increased cardiac workload in diabetic hearts.

Distinct intra-mitochondrial localizations of pro-survival kinases and regulation of their functions by DUSP5 and PHLPP-1.

Wataru Ohwada, Masaya Tanno, Toshiyuki Yano, Sang-Bing Ong, Koki Abe, Tatsuya Sato, Atsushi Kuno, Takayuki Miki, Hirohito Sugawara, Yusuke Igaki, Tetsuji Miura

Biochimica et biophysica acta. Molecular basis of disease 1866 ( 10 ) 165851 - 165851 2020年10月 [査読有り] [国際誌]

ERK and Akt have been shown to regulate cell sensitivity to death-inducing stress by phosphorylating GSK-3β, a major modulator of the threshold for mitochondrial permeability transition. Here we examined intra-mitochondrial localization of the pro-survival kinases and their regulation by phosphatases. Stepwise trypsin digestion of mitochondria isolated from HEK293 or H9c2 cells was performed, and immunoblotting revealed that GSK-3β and ERK localized dominantly in the outer membrane (OM), while Akt resided at comparable levels in OM, the inner membrane (IM) and the matrix. Treatment with IGF-1 increased the protein level of Akt in the matrix, while ERK and GSK-3β protein levels were increased in OM. Simultaneously, IGF-1 treatment elevated the level of Thr202/Tyr204-phospho-ERK in IM and matrix and levels of Ser473-phospho-Akt and Ser9-phospho-GSK-3β in OM, IM and matrix. Exposing cells to reactive oxygen species (ROS) by using antimycin A increased the levels of DUSP5 and PHLPP-1 mainly in OM and induced dephosphorylation of Akt, ERK and GSK-3β. The mitochondrial localization of DUSP5 was confirmed by experiments with mitochondria purified by Percoll gradient centrifugation and by transfection of cells with GFP-tagged DUSP5. Knockdown of either DUSP5 or PHLPP-1 increased the levels of both Thr202/Tyr204-phospho-ERK and Ser473-phospho-Akt in mitochondria. Cell death induced by antimycin A was suppressed by siRNA-mediated knockdown of DUSP5. The results suggest that Akt and ERK in mitochondria show distinct intra-mitochondrial localization and crosstalk in GSK-3β regulation and that recruitment of DUSP5 as well as PHLPP-1 to mitochondria contributes to ROS-induced termination of the protective signaling.

Empagliflozin attenuates acute kidney injury after myocardial infarction in diabetic rats.

Atsushi Kuno, Yukishige Kimura, Masashi Mizuno, Hiroto Oshima, Tatsuya Sato, Norihito Moniwa, Marenao Tanaka, Toshiyuki Yano, Masaya Tanno, Takayuki Miki, Tetsuji Miura

Scientific reports 10 ( 1 ) 7238 - 7238 2020年04月 [査読有り] [国際誌]

Acute kidney injury (AKI) predicts poor prognosis in patients with acute myocardial infarction (MI) and diabetes mellitus (DM) is an independent risk factor of AKI. Recent clinical studies have shown the beneficial effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on cardiovascular and renal outcomes in patients with DM. We recently reported that canagliflozin normalized susceptibility of diabetic rats to AKI after acute MI via β-hydroxybutyrate-mediated suppression of NOX expression. Here we examined whether the same renoprotective effect is shared by empagliflozin. Serum creatinine levels were not changed by MI induced by coronary artery occlusion in LETO, non-diabetic control rats, and OLETF, obese type 2 diabetic rats. However, immunohistochemistry revealed that MI increased renal expression of NGAL and KIM-1, early markers of tubular injury, by 3.2-fold and 2.6-fold, respectively, in OLETF. These increases in injury markers were not observed in LETO. Pretreatment with empagliflozin of OLETF for 2 weeks improved hyperglycemia, increased blood β-hydroxybutyrate level, and suppressed MI-induced expression of NGAL and KIM-1. Empagliflozin suppressed upregulation of NOX2 and NOX4 in the kidney of OLETF. Taken together with the results of our previous study, it was concluded that treatment with the SGLT2 inhibitor protects the diabetic kidney from MI-induced AKI.

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