| Mikako Yagi | Last modified date：2023.12.06 |
Assistant Professor /
section of medical science and technology /
Department of Health Sciences /
Faculty of Medical Sciences
Papers
| 1. | Kenji Miki, Mikako Yagi, Koji Yoshimoto, Dongchon Kang, Takeshi Uchiumi, Mitochondrial dysfunction and impaired growth of glioblastoma cell lines caused by antimicrobial agents inducing ferroptosis under glucose starvation, ONCOGENESIS, 10.1038/s41389-022-00437-z, 11, 1, 2022.10. |
| 2. | Masakazu Fujii, Daiki Setoyama, Kazuhito Gotoh, Yushi Dozono, Mikako Yagi, Masataka Ikeda, Tomomi Ide, Takeshi Uchiumi, Dongchon Kang, TFAM expression in brown adipocytes confers obesity resistance by secreting extracellular vesicles that promote self-activation, ISCIENCE, 10.1016/j.isci.2022.104889, 25, 9, 2022.09. |
| 3. | Shigehiro Tsukahara, Masaki Shiota, Dai Takamatsu, Shohei Nagakawa, Takashi Matsumoto, Ryo Kiyokoba, Mikako Yagi, Daiki Setoyama, Nozomi Noda, Shinya Matsumoto, Tetsutaro Hayashi, Alberto Contreras-Sanz, Peter C. Black, Junichi Inokuchi, Kenichi Kohashi, Yoshinao Oda, Takeshi Uchiumi, Masatoshi Eto, Dongchon Kang, Cancer genomic profiling identified dihydropyrimidine dehydrogenase deficiency in bladder cancer promotes sensitivity to gemcitabine, SCIENTIFIC REPORTS, 10.1038/s41598-022-12528-3, 12, 1, 2022.05. |
| 4. | Ryo Kiyokoba, Takeshi Uchiumi, Mikako Yagi, Takahiro Toshima, Shigehiro Tsukahara, Yasuyuki Fujita, Kiyoko Kato, Dongchon Kang, Mitochondrial dysfunction-induced high hCG associated with development of fetal growth restriction and pre-eclampsia with fetal growth restriction, Scientific reports, doi.org/10.1038/s41598-022-07893-y, 2022.03, Fetal growth restriction (FGR) and pre-eclampsia with fetal growth restriction (PE/FGR) are high-risk perinatal diseases that may involve high levels of human chorionic gonadotropin (hCG) and mitochondrial dysfunction. However, little is known about how these factors affect placental function. We investigated how mitochondrial dysfunction and high hCG expression affected placental function in unexplained FGR and PE/FGR. We observed elevated expression of hCGβ and growth differentiation factor 15 mRNA and protein levels in the placenta with both diseases. Likewise, antiangiogenic factors, such as Ang2, IP10, sFlt1, IL8, IL1B, and TNFα, were also upregulated at the mRNA level. In addition, the expression of COXI and COXII which encoded by mitochondrial DNA were significantly decreased in both diseases, suggesting that mitochondrial translation was impaired. Treatment with hCG increased Ang2, IP10, IL8, and TNFα mRNA levels in a dose-dependent manner via the p38 and JNK pathways. Mitochondrial translation inhibitors increased hCGβ expression through stabilization of HIF1α, and increased IL8 and TNFα mRNA expression. These results revealed that high expression of hCG due to mitochondrial translational dysfunction plays an important role in the pathogenesis of FGR and PE/FGR.. |
| 5. | Mikako Yagi, Takahiro Toshima, Rie Amamoto, Yura Do, Haruka Hirai, Daiki Setoyama, Dongchon Kang, Takeshi Uchiumi, Mitochondrial translation deficiency impairs NAD(+)-mediated lysosomal acidification, EMBO JOURNAL, 10.15252/embj.2020105268, 40, 8, 2021.04, Mitochondrial translation dysfunction is associated with neurodegenerative and cardiovascular diseases. Cells eliminate defective mitochondria by the lysosomal machinery via autophagy. The relationship between mitochondrial translation and lysosomal function is unknown. In this study, mitochondrial translation-deficient hearts from p32-knockout mice were found to exhibit enlarged lysosomes containing lipofuscin, suggesting impaired lysosome and autolysosome function. These mice also displayed autophagic abnormalities, such as p62 accumulation and LC3 localization around broken mitochondria. The expression of genes encoding for nicotinamide adenine dinucleotide (NAD+) biosynthetic enzymes—Nmnat3 and Nampt—and NAD+ levels were decreased, suggesting that NAD+ is essential for maintaining lysosomal acidification. Conversely, nicotinamide mononucleotide (NMN) administration or Nmnat3 overexpression rescued lysosomal acidification. Nmnat3 gene expression is suppressed by HIF1α, a transcription factor that is stabilized by mitochondrial translation dysfunction, suggesting that HIF1α-Nmnat3-mediated NAD+ production is important for lysosomal function. The glycolytic enzymes GAPDH and PGK1 were found associated with lysosomal vesicles, and NAD+ was required for ATP production around lysosomal vesicles. Thus, we conclude that NAD+ content affected by mitochondrial dysfunction is essential for lysosomal maintenance.. |
| 6. | Kazuhito Gotoh, Yuya Kunisaki, Soichi Mizuguchi, Daiki Setoyama, Kentaro Hosokawa, Hisayuki Yao, Yuya Nakashima, Mikako Yagi, Takeshi Uchiumi, Yuichiro Semba, Jumpei Nogami, Koichi Akashi, Fumio Arai, Dongchon Kang, Mitochondrial Protein Synthesis Is Essential for Terminal Differentiation of CD45– TER119–Erythroid and Lymphoid Progenitors, iScience, 23, 11, 2020.09, [URL]. |
| 7. | Kazuhito Gotoh, Takafumi Morisaki, Daiki Setoyama, Katsuhiko Sasaki, Mikako Yagi, Ko Igami, Soichi Mizuguchi, Takeshi Uchiumi, Yoshinori Fukui, Dongchon Kang, Mitochondrial p32/C1qbp Is a Critical Regulator of Dendritic Cell Metabolism and Maturation, Cell Reports, 10.1016/j.celrep.2018.10.057, 25, 7, 1800-1815.e4, 2018.11, Dendritic cell (DC) maturation induced by Toll-like receptor agonists requires activation of downstream signal transduction and metabolic changes. The endogenous metabolite citrate has recently emerged as a modulator of DC activation. However, the metabolic requirements that support citrate production remain poorly defined. Here, we demonstrate that p32/C1qbp, which functions as a multifunctional chaperone protein in mitochondria, supports mitochondrial metabolism and DC maturation. Metabolic analysis revealed that the citrate increase induced by lipopolysaccharide (LPS) is impaired in p32-deficient DCs. We also found that p32 interacts with dihydrolipoamide S-acetyltransferase (E2 component of pyruvate dehydrogenase [PDH] complex) and positively regulates PDH activity in DCs. Therefore, we suggest that DC maturation is regulated by citrate production via p32-dependent PDH activity. p32-null mice administered a PDH inhibitor show decreased DC maturation and ovalbumin-specific IgG production in vivo, suggesting that p32 may serve as a therapeutic target for DC-related autoimmune diseases. Although mitochondrial metabolic pathways are essential for DC activation, the precise molecular mechanism remains poorly understood. Gotoh et al. show that mitochondrial p32/C1qbp supports dendritic cell metabolism and maturation. In addition, mitochondrial p32 and pyruvate dehydrogenase activity are necessary for DC maturation in vitro and in vivo.. |
| 8. | Mikako Yagi, Takeshi Uchiumi, Noriaki Sagata, Daiki Setoyama, Rie Amamoto, Yuichi Matsushima, Dongchon Kang, Neural-specific deletion of mitochondrial p32/C1qbp leads to leukoencephalopathy due to undifferentiated oligodendrocyte and axon degeneration, Scientific reports, 10.1038/s41598-017-15414-5, 7, 1, 2017.12, Mitochondrial dysfunction is a critical step in the pathogenesis of many neurodegenerative diseases. The p32/ C1qbp gene functions as an essential RNA and protein chaperone in mitochondrial translation, and is indispensable for embryonic development. However, little is known about the consequences of mitochondrial dysfunction of p32 deletion in the brain development. Here, we found that mice lacking p32 in the central nervous system (p32cKO mice) showed white matter degeneration accompanied by progressive oligodendrocyte loss, axon degeneration and vacuolation in the mid brain and brain stem regions. Furthermore, p32cKO mice died within 8 weeks of birth. We also found that p32-deficient oligodendrocytes and neurons showed reduced oligodendrocyte differentiation and axon degeneration in primary culture. We show that mitochondrial disruption activates an adaptive program known as the integrated stress response (ISR). Mitochondrial respiratory chain function in oligodendrocytes and neurons is, therefore, essential for myelination and axon maintenance, respectively, suggesting that mitochondrial respiratory chain dysfunction in the central nervous system contributes to leukoencephalopathy.. |
| 9. | Takashi Matsumoto, Takeshi Uchiumi, Keisuke Monji, Mikako Yagi, Daiki Setoyama, Rie Amamoto, Yuichi Matsushima, Masaki Shiota, Masatoshi Eto, Dongchon Kang, Doxycycline induces apoptosis via ER stress selectively to cells with a cancer stem cell-like properties Importance of stem cell plasticity, Oncogenesis, 10.1038/s41389-017-0009-3, 6, 11, 2017.11, Tumor heterogeneity can be traced back to a small subset of cancer stem cells (CSCs), which can be derived from a single stem cell and show chemoresistance. Recent studies showed that CSCs are sensitive to mitochondrial targeting antibiotics such as doxycycline. However, little is known about how cancer cells undergo sphere formation and how antibiotics inhibit CSC proliferation. Here we show that under sphere-forming assay conditions, prostate cancer cells acquired CSC-like properties: promoted mitochondrial respiratory chain activity, expression of characteristic CSC markers and resistance to anticancer agents. Furthermore, those CSC-like properties could reversibly change depending on the culture conditions, suggesting some kinds of CSCs have plasticity in tumor microenvironments. The sphere-forming cells (i.e. cancer stem-like cells) showed increased contact between mitochondria and mitochondrial associated-endoplasmic reticulum (ER) membranes (MAM). Mitochondrial targeting doxycycline induced activating transcription factor 4 (ATF4) mediated expression of ER stress response and led to p53-upregulated modulator of apoptosis (PUMA)-dependent apoptosis only in the cancer stem-like cells. We also found that doxycycline effectively suppressed the sphere formation in vitro and blocked CD44v9-expressing tumor growth in vivo. In summary, these data provide new molecular findings that monolayer cancer cells acquire CSC-like properties in a reversible manner. These findings provide important insights into CSC biology and a potential new treatment of targeting mitochondria dependency.. |
| 10. | René G. Feichtinger, Monika Oláhová, Yoshihito Kishita, Caterina Garone, Laura S. Kremer, Mikako Yagi, Takeshi Uchiumi, Alexis A. Jourdain, Kyle Thompson, Aaron R. D'Souza, Robert Kopajtich, Charlotte L. Alston, Johannes Koch, Wolfgang Sperl, Elisa Mastantuono, Tim M. Strom, Saskia B. Wortmann, Thomas Meitinger, Germaine Pierre, Patrick F. Chinnery, Zofia M. Chrzanowska-Lightowlers, Robert N. Lightowlers, Salvatore DiMauro, Sarah E. Calvo, Vamsi K. Mootha, Maurizio Moggio, Monica Sciacco, Giacomo P. Comi, Dario Ronchi, Kei Murayama, Akira Ohtake, Pedro Rebelo-Guiomar, Masakazu Kohda, Dongchon Kang, Johannes A. Mayr, Robert W. Taylor, Yasushi Okazaki, Michal Minczuk, Holger Prokisch, Biallelic C1QBP Mutations Cause Severe Neonatal-, Childhood-, or Later-Onset Cardiomyopathy Associated with Combined Respiratory-Chain Deficiencies, American journal of human genetics, 10.1016/j.ajhg.2017.08.015, 101, 4, 525-538, 2017.10, Complement component 1 Q subcomponent-binding protein (C1QBP; also known as p32) is a multi-compartmental protein whose precise function remains unknown. It is an evolutionary conserved multifunctional protein localized primarily in the mitochondrial matrix and has roles in inflammation and infection processes, mitochondrial ribosome biogenesis, and regulation of apoptosis and nuclear transcription. It has an N-terminal mitochondrial targeting peptide that is proteolytically processed after import into the mitochondrial matrix, where it forms a homotrimeric complex organized in a doughnut-shaped structure. Although C1QBP has been reported to exert pleiotropic effects on many cellular processes, we report here four individuals from unrelated families where biallelic mutations in C1QBP cause a defect in mitochondrial energy metabolism. Infants presented with cardiomyopathy accompanied by multisystemic involvement (liver, kidney, and brain), and children and adults presented with myopathy and progressive external ophthalmoplegia. Multiple mitochondrial respiratory-chain defects, associated with the accumulation of multiple deletions of mitochondrial DNA in the later-onset myopathic cases, were identified in all affected individuals. Steady-state C1QBP levels were decreased in all individuals’ samples, leading to combined respiratory-chain enzyme deficiency of complexes I, III, and IV. C1qbp−/− mouse embryonic fibroblasts (MEFs) resembled the human disease phenotype by showing multiple defects in oxidative phosphorylation (OXPHOS). Complementation with wild-type, but not mutagenized, C1qbp restored OXPHOS protein levels and mitochondrial enzyme activities in C1qbp−/− MEFs. C1QBP deficiency represents an important mitochondrial disorder associated with a clinical spectrum ranging from infantile lactic acidosis to childhood (cardio)myopathy and late-onset progressive external ophthalmoplegia.. |
| 11. | Toshiro Saito, Takeshi Uchiumi, Mikako Yagi, Rie Amamoto, Daiki Setoyama, Yuichi Matsushima, Dongchon Kang, Cardiomyocyte-specific loss of mitochondrial p32/C1qbp causes cardiomyopathy and activates stress responses, Cardiovascular research, 10.1093/cvr/cvx095, 113, 10, 1173-1185, 2017.08, Aims Mitochondria are important organelles, dedicated to energy production. Mitochondrial p32/C1qbp, which functions as an RNA and protein chaperone, interacts with mitochondrial mRNA and is indispensable for mitochondrial function through its regulation of mitochondrial translation in cultured cell lines. However, the precise role of p32/C1qbp in vivo is poorly understood because of embryonic lethality in the systemic p32-deficient mouse. The goal of this study was to examine the physiological function of mitochondrial p32/C1qbp in the heart. Methods and results We investigated the role of p32 in regulating cardiac function in mice using a Cre-loxP recombinase technology against p32 with tamoxifen-inducible knockdown or genetic ablation during postnatal periods. Cardiomyocyte-specific deletion of p32 resulted in contractile dysfunction, cardiac dilatation and cardiac fibrosis, compared with hearts of control mice. We also found decreased COX1 expression, decreased rates of oxygen consumption and increased oxidative stress, indicating that these mice had cardiac mitochondrial dysfunction provoked by p32-deficiency at early stage. Next, we investigated lifespan in cardiac-specific p32-deficient mice. The mice died beginning at 12 months and their median lifespan was ∼14 months. Cardiac mitochondria in the p32-deficient mice showed disordered alignment, enlargement and abnormalities in their internal structure by electron microscopy. We observed that, in p32-deficient compared with control myocytes, AMPKI' was constitutively phosphorylated and 4EBP-1 and ribosomal S6K were less phosphorylated, suggesting impairment of mammalian target of rapamycin signalling. Finally, we found that expression levels of mitokines such as FGF21 and of integrated stress response genes were significantly increased. Metabolic analysis demonstrated that the urea cycle was impaired in the p32-deficient hearts. Conclusion These findings support a key role for mitochondrial p32 protein in cardiac myocytes modulating mitochondrial translation and function, and thereby survival.. |
| 12. | Katsuhiko Sasaki, Kazuhito Gotoh, Sho Miake, Daiki Setoyama, Mikako Yagi, Ko Igami, Takeshi Uchiumi, Donchon Kang, p32 is Required for Appropriate Interleukin-6 Production Upon LPS Stimulation and Protects Mice from Endotoxin Shock, EBioMedicine, 10.1016/j.ebiom.2017.05.018, 20, 161-172, 2017.06, Sepsis is a major cause of morbidity and mortality in seriously ill patients and mitochondrial dysfunction is associated with poor outcomes in septic patients. Although interleukin-6 (IL-6) is a good prognostic marker for sepsis, the relationship between mitochondrial dysfunction and IL-6 remains poorly understood. We identified p32/C1QBP/HABP1 as a regulator of IL-6 production in response to lipopolysaccharide (LPS). LPS induced IL-6 overproduction in p32 deficient mouse embryonic fibroblasts (MEFs) through NF-κB independent but activating transcription factor (ATF) 4 dependent pathways. Short hairpin RNA-based knockdown of ATF4 in p32 deficient MEFs markedly inhibited LPS-induced IL-6 production. Furthermore, MEFs treated with chloramphenicol, an inhibitor of mitochondrial translation, produced excessive IL-6 via ATF4 pathways. Using a LPS-induced endotoxin shock model, mice with p32 ablation in myeloid cells showed increased lethality and overproduction of IL-6. Thus, this study provides a molecular link how mitochondrial dysfunction leads to IL-6 overproduction and poor prognosis of sepsis.. |
| 13. | Hideya Ando, Yoshiaki Ohagi, Moemi Yoshida, Satoshi Yoshimoto, Yusuke Higashi, Masayuki Yagi, Keisuke Monji, Mikako Yagi, Takeshi Uchiumi, Dongchon Kang, Masamitsu Ichihashi, Melanin pigment interrupts the fluorescence staining of mitochondria in melanocytes, Journal of Dermatological Science, 10.1016/j.jdermsci.2016.08.533, 84, 3, 349-351, 2016.12. |
| 14. | Keisuke Monji, Takeshi Uchiumi, Saki Hoshizawa, Mikako Yagi, Takashi Matsumoto, Daiki Setoyama, Yuichi Matsushima, Kazuhito Gotoh, Rie Amamoto, Donchon Kang, Serum depletion induced cancer stem cell-like phenotype due to nitric oxide synthesis in oncogenic HRas transformed cells, Oncotarget, 10.18632/oncotarget.12117, 7, 46, 75221-75234, 2016.01, Cancer cells rewire their metabolism and mitochondrial oxidative phosphorylation (OXPHOS) to promote proliferation and maintenance. Cancer cells use multiple adaptive mechanisms in response to a hypo-nutrient environment. However, little is known about how cancer mitochondria are involved in the ability of these cells to adapt to a hypo-nutrient environment. Oncogenic HRas leads to suppression of the mitochondrial oxygen consumption rate (OCR), but oxygen consumption is essential for tumorigenesis. We found that in oncogenic HRas transformed cells, serum depletion reversibly increased the OCR and membrane potential. Serum depletion promoted a cancer stem cell (CSC)-like phenotype, indicated by an increase in CSC markers expression and resistance to anticancer agents. We also found that nitric oxide (NO) synthesis was significantly induced after serum depletion and that NO donors modified the OCR. An NOS inhibitor, SEITU, inhibited the OCR and CSC gene expression. It also reduced anchorage-independent growth by promoting apoptosis. In summary, our data provide new molecular findings that serum depletion induces NO synthesis and promotes mitochondrial OXPHOS, leading to tumor progression and a CSC phenotype. These results suggest that mitochondrial OCR inhibitors can be used as therapy against CSC.. |
| 15. | Rie Amamoto, Takeshi Uchiumi, Mikako Yagi, Keisuke Monji, Yoo Hyun Song, Yoshinao Oda, Masaki Shiota, Akira Yokomizo, Seiji Naito, Dongchon Kang, The expression of ubiquitous mitochondrial creatine kinase is downregulated as prostate cancer progressionz, Journal of Cancer, 10.7150/jca.13207, 7, 1, 50-59, 2016.01, Background: Mitochondria play crucial roles in cell signaling events, interorganellar communication, aging, cell proliferation and apoptosis, and mitochondrial impairment has been shown to accelerate or modulate cancer progression. Ubiquitous mitochondrial creatine kinase (uMtCK) is predominantly localized in the intermembrane space of mitochondria and catalyzes the reversible exchange of high-energy phosphate between adenosine tri-phosphate (ATP) and phosphocreatine. However, little is known about its expression and function in human prostate cancer progression. Method: We investigated the expression of uMtCK in 148 prostate carcinoma tissues and matched normal tissue by immunohistochemistry. The expression and localization of uMtCK and hexokinase II, a marker of glycolysis, were examined in prostate carcinoma cell lines using western blot and immunofluorescence. Results: MtCK expression was significantly lower in high Gleason grade carcinoma compared with normal prostate or low grade carcinoma. Western blot further revealed that uMtCK was highly expressed in LNCaP and 22Rv1 cell lines, as well as in the normal prostate cell line RWPE-1. However, uMtCK expression was almost absent in PC3 and DU145 cell lines, in correlation with absent or mutant p53 expression, respectively. In contrast, hexokinase II was overexpressed in PC3 cells. Moreover, in the low uMtCK expressing cell lines, glycolytic ATP production was increased, whereas mitochondrial ATP production was decreased. Conclusions: These data suggest that uMtCK is downregulated as prostate cancer progresses in correlation with a metabolic switch in ATP usage.. |
| 16. | Takashi Baba, Hiroyuki Otake, Tetsuya Sato, Kanako Miyabayashi, Yurina Shishido, Chia Yih Wang, Yuichi Shima, Hiroshi Kimura, Mikako Yagi, Yasuhiro Ishihara, Shinjiro Hino, Hidesato Ogawa, Mitsuyoshi Nakao, Takeshi Yamazaki, Dongchon Kang, Yasuyuki Ohkawa, Mikita Suyama, Bon Chu Chung, Ken Ichirou Morohashi, Glycolytic genes are targets of the nuclear receptor Ad4BP/SF-1, Nature communications, 10.1038/ncomms4634, 5, 2014.04, Genetic deficiencies in transcription factors can lead to the loss of certain types of cells and tissue. The steroidogenic tissue-specific nuclear receptor Ad4BP/SF-1 (NR5A1) is one such gene, because mice in which this gene is disrupted fail to develop the adrenal gland and gonads. However, the specific role of Ad4BP/SF-1 in these biological events remains unclear. Here we use chromatin immunoprecipitation sequencing to show that nearly all genes in the glycolytic pathway are regulated by Ad4BP/SF-1. Suppression of Ad4BP/SF-1 by small interfering RNA reduces production of the energy carriers ATP and nicotinamide adenine dinucleotide phosphate, as well as lowers expression of genes involved in glucose metabolism. Together, these observations may explain tissue dysgenesis as a result of Ad4BP/SF-1 gene disruption in vivo. Considering the function of estrogen-related receptor α, the present study raises the possibility that certain types of nuclear receptors regulate sets of genes involved in metabolic pathways to generate energy carriers.. |
| 17. | Takeshi Uchiumi, Hiroyuki Tanamachi, Kajiyo Kuchiwaki, Mitsuharu Kajita, Shinya Matsumoto, Mikako Yagi, Tomotake Kanki, Dongchon Kang, Mutation and functional analysis of ABCC2/multidrug resistance protein 2 in a Japanese patient with Dubin-Johnson syndrome, HEPATOLOGY RESEARCH, 10.1111/j.1872-034X.2012.01103.x, 43, 5, 569-575, 2013.05, Dubin-Johnson syndrome (DJS) is a recessive inherited disorder characterized by conjugated hyperbilirubinemia. It is caused by dysfunction of adenosine triphosphate-binding cassette, sub-family C, member 2 (ABCC2/MRP2) on the canalicular membrane of hepatocytes. We performed mutational analysis of the ABCC2/MRP2 gene in a Japanese female with DJS. Furthermore, we investigated the effects of the two identified DJS-associated mutations on MRP2 function. We found a compound heterozygous mutation in the patient: W709R (c.2124T>C), a missense mutation in exon 17, and R1310X (c.3928C>T), a nonsense mutation in exon 28. DJS-associated mutations have been shown to impair the protein maturation and transport activity of ABCC2/MRP2. We established HEK293 cell lines stably expressing one of the two identified DJS-associated mutations. Expressed W709R MRP2 was mainly core-glycosylated, predominantly retained in the endoplasmic reticulum, and exhibited no transport activity, suggesting that this mutation causes deficient maturation and impaired protein sorting. No MRP2 protein was expressed from HEK293 cells transfected with an R1310X-containing construct. This compound heterozygous mutation of the MRP2 gene causes dysfunction of the MRP2 protein and the hyperbilirubinemia seen in DJS.. |
| 18. | Jing Xian Fang, Takeshi Uchiumi, Mikako Yagi, Shinya Matsumoto, Rie Amamoto, Shinya Takazaki, Haruyoshi Yamaza, Kazuaki Nonaka, Dongchon Kang, Dihydro-orotate dehydrogenase is physically associated with the respiratory complex and its loss leads to mitochondrial dysfunction, BIOSCIENCE REPORTS, 10.1042/BSR20120097, 33, 217-227, 2013.02, Some mutations of the DHODH (dihydro-orotate dehydrogenase) gene lead to postaxial acrofacial dysostosis or Miller syndrome. Only DHODH is localized at mitochondria among enzymes of the de novo pyrimidine biosynthesis pathway. Since the pyrimidine biosynthesis pathway is coupled to the mitochondrial RC (respiratory chain) via DHODH, impairment of DHODH should affect the RC function. To investigate this, we used siRNA (small interfering RNA)-mediated knockdown and observed that DHODH knockdown induced cell growth retardation because of G2/M cell-cycle arrest, whereas pyrimidine deficiency usually causes G1/S arrest. Inconsistent with this, the cell retardation was not rescued by exogenous uridine, which should bypass the DHODH reaction for pyrimidine synthesis. DHODH depletion partially inhibited the RC complex III, decreased the mitochondrial membrane potential, and increased the generation of ROS (reactive oxygen species). We observed that DHODH physically interacts with respiratory complexes II and III by IP (immunoprecipitation) and BN (blue native)/SDS/PAGE analysis. Considering that pyrimidine deficiency alone does not induce craniofacial dysmorphism, the DHODH mutations may contribute to the Miller syndrome in part through somehow altered mitochondrial function.. |
| 19. | Jing Xian Fang, Takeshi Uchiumi, Mikako Yagi, Shinya Matsumoto, Rie Amamoto, Toshiro Saito, Shinya Takazaki, Tomotake Kanki, Haruyoshi Yamaza, Kazuaki Nonaka, Dongchon Kang, Protein instability and functional defects caused by mutations of dihydro-orotate dehydrogenase in Miller syndrome patients, BIOSCIENCE REPORTS, 10.1042/BSR20120046, 32, 6, 631-639, 2012.12, Miller syndrome is a recessive inherited disorder characterized by postaxial acrofacial dysostosis. It is caused by dysfunction of the DHODH (dihydroorotate dehydrogenase) gene, which encodes a key enzyme in the pyrimidine de novo biosynthesis pathway and is localized at mitochondria intermembrane space. We investigated the consequence of three missense mutations, G202A, R346W and R135C of DHODH, which were previously identified in patients with Miller syndrome. First, we established HeLa cell lines stably expressing DHODH with Miller syndrome-causative mutations: G202A, R346W and R135C. These three mutant proteins retained the proper mitochondrial localization based on immunohistochemistry and mitochondrial subfractionation studies. The G202A, R346W DHODH proteins showed reduced protein stability. On the other hand, the third one R135C, in which the mutation lies at the ubiquinone-binding site, was stable but possessed no enzymatic activity. In conclusion, the G202A and R346W mutation causes deficient protein stability, and the R135C mutation does not affect stability but impairs the substrate-induced enzymatic activity, suggesting that impairment of DHODH activity is linked to the Miller syndrome phenotype.. |
| 20. | Mikako Yagi, Takeshi Uchiumi, Shinya Takazaki, Bungo Okuno, Masatoshi Nomura, Shin Ichi Yoshida, Tomotake Kanki, Dongchon Kang, p32/gC1qR is indispensable for fetal development and mitochondrial translation: importance of its RNA-binding ability, NUCLEIC ACIDS RESEARCH, 10.1093/nar/gks774, 40, 19, 9717-9737, 2012.10, p32 is an evolutionarily conserved and ubiquitously expressed multifunctional protein. Although p32 exists at diverse intra and extracellular sites, it is predominantly localized to the mitochondrial matrix near the nucleoid associated with mitochondrial transcription factor A. Nonetheless, its function in the matrix is poorly understood. Here, we determined p32 function via generation of p32-knockout mice. p32-deficient mice exhibited midgestation lethality associated with a severe developmental defect of the embryo. Primary embryonic fibroblasts isolated from p32-knockout embryos showed severe dysfunction of the mitochondrial respiratory chain, because of severely impaired mitochondrial protein synthesis. Recombinant p32 binds RNA, not DNA, and endogenous p32 interacts with all mitochondrial messenger RNA species in vivo. The RNA-binding ability of p32 is well correlated with the mitochondrial translation. Coimmunoprecipitation revealed the close association of p32 with the mitoribosome. We propose that p32 is required for functional mitoribosome formation to synthesize proteins within mitochondria.. |
| 21. | Shinya Matsumoto, Takeshi Uchiumi, Toshiro Saito, Mikako Yagi, Shinya Takazaki, Tomotake Kanki, Dongchon Kang, Localization of mRNAs encoding human mitochondrial oxidative phosphorylation proteins, MITOCHONDRION, 10.1016/j.mito.2012.02.004, 12, 3, 391-398, 2012.05, The mitochondrial oxidative phosphorylation (OXPHOS) proteins are encoded by both nuclear and mitochondrial DNA. The nuclear-encoded OXPHOS mRNAs have specific subcellular localizations, but little is known about which localize near mitochondria. Here, we compared mRNAs in mitochondria-bound polysome fractions with those in cytosolic, free polysome fractions. mRNAs encoding hydrophobic OXPHOS proteins, which insert into the inner membrane, were localized near mitochondria. Conversely, OXPHOS gene which mRNAs were predominantly localized in cytosol had less than one transmembrane domain. The RNA-binding protein Y-box binding protein-1 is localized at the mitochondrial outer membrane and bound to the OXPHOS mRNAs. Our findings offer new insight into mitochondrial co-translational import in human cells.. |
| 22. | Shinya Matsumoto, Takeshi Uchiumi, Hiroyuki Tanamachi, Toshiro Saito, Mikako Yagi, Shinya Takazaki, Tomotake Kanki, Dongchon Kang, Ribonucleoprotein Y-box-binding protein-1 regulates mitochondrial oxidative phosphorylation (OXPHOS) protein expression after serum stimulation through binding to OXPHOS mRNA, Biochem J , 10.1042/BJ20111728, 443, 2, 573-584, 2012.04, Mitochondria play key roles in essential cellular functions, such as energy production, metabolic pathways and aging. Growth factor-mediated expression of the mitochondrial OXPHOS (oxidative phosphorylation) complex proteins has been proposed to play a fundamental role in metabolic homoeostasis. Although protein translation is affected by general RNA-binding proteins, very little is known about the mechanism involved in mitochondrial OXPHOS protein translation. In the present study, serum stimulation induced nuclear-encoded OXPHOS protein expression, such as NDUFA9 [NADH dehydrogenase (ubiquinone) 1α subcomplex, 9, 39 kDa], NDUFB8 [NADH dehydrogenase (ubiquinone) 1β subcomplex, 8, 19 kDa], SDHB [succinate dehydrogenase complex, subunit B, iron sulfur (Ip)] and UQCRFS1 (ubiquinol-cytochrome c reductase, Rieske iron-sulfur polypeptide 1), and mitochondrial ATP production, in a translation-dependent manner. We also observed that the major ribonucleoprotein YB-1 (Y-box-binding protein-1) preferentially bound to these OXPHOS mRNAs and regulated the recruitment of mRNAs from inactivemRNPs (messenger ribonucleoprotein particles) to active polysomes. YB-1 depletion led to up-regulation of mitochondrial function through induction of OXPHOS protein translation from inactive mRNP release. In contrast, YB-1 overexpression suppressed the translation of these OXPHOS mRNAs through reduced polysome formation, suggesting that YB-1 regulated the translation of mitochondrial OXPHOS mRNAs through mRNA binding. Taken together, our findings suggest that YB-1 is a critical factor for translation that may control OXPHOS activity.. |
| 23. | Shinya Takazaki, Yoshito Abe, Tomohiro Yamaguchi, Mikako Yagi, Tadashi Ueda, Dongchon Kang, Naotaka Hamasaki, Arg 901 in the AE1 C-terminal tail is involved in conformational change but not in substrate binding, Biochim Biophys Acta, 10.1016/j.bbamem.2011.11.019, 658-665, 2012.03. |
| 24. | Amamoto, R., Yagi, M., Song, Y. H., Oda, Y., Tsuneyoshi, M., Naito, S., Yokomizo, A., Kuroiwa, K., Tokunaga, S., Kato, S., Hiura, H., Samori, T., Kang, D. & Uchiumi, T.,, Mitochondrial p32/C1QBP is highly expressed in prostate cancer and is associated with shorter prostate-specific antigen relapse time after radical prostatectomy, CANCER SCIENCE, 10.1111/j.1349-7006.2010.01828.x, 102, 3, 639-647, 2011.03. |
| 25. | Uchiumi, T., Ohgaki, K., Yagi, M., Aoki, Y., Sakai, A., Matsumoto, S. & Kang, D., , ERAL1 is associated with mitochondrial ribosome and elimination of ERAL1 leads to mitochondrial dysfunction and growth retardation, NUCLEIC ACIDS RESEARCH, 10.1093/nar/gkq305, 38, 16, 5554-5568, 2010.09, ERAL1, a homologue of Era protein in Escherichia coli, is a member of conserved GTP-binding proteins with RNA-binding activity. Depletion of prokaryotic Era inhibits cell division without affecting chromosome segregation. Previously, we isolated ERAL1 protein as one of proteins which were associated with mitochondrial transcription factor A by using immunoprecipitation. In this study, we analysed the localization and function of ERAL1 in mammalian cells. ERAL1 was localized in mitochondrial matrix and associated with mitoribosomal proteins including the 12S rRNA. siRNA knockdown of ERAL1 decreased mitochondrial translation, caused redistribution of ribosomal small subunits and reduced 12S rRNA. The knockdown of ERAL1 in human HeLa cells elevated mitochondrial superoxide production and slightly decreased mitochondrial membrane potential. The knockdown inhibited the growth of HeLa cells with an accumulation of apoptotic cells. These results suggest that ERAL1 is localized in a small subunit of the mitochondrial ribosome, plays an important role in the small ribosomal constitution, and is also involved in cell viability.. |
| 26. | Shinya Takazaki, Yoshito Abe, Tomohiro Yamaguchi, Mikako Yagi, Tadashi Ueda, Dongchon Kang, Naotaka Hamasaki, Mutation of His 834 in human anion exchanger 1 affects substrate binding, BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES, 10.1016/j.bbamem.2010.01.019, 1798, 5, 903-908, 2010.05, Anion exchanger 1 (AE1 or band 3) is responsible for Cl--HCO3- exchange on erythrocyte membrane. Previously, we showed that band 3 is fixed in an inward-facing conformation by specific modification of His 834 with DEPC, resulting in a strong inhibition of its anion transport activity. To clarify the physiological role of His 834, we evaluated the sulfate transport activities of various band 3 mutants: different mutants at His 834 and alanine mutants of peripheral residues around 834 (Lys 829-Phe 836) in yeast cell membranes. The Km values of the His 834 mutants were 4-10 times higher than that of the wild type, while their Vmax values were barely lower than that of wild type. Meanwhile, the Km values of the peripheral alanine mutants were only slightly increased. These data suggest that His 834 is critically important for the efficient binding of sulfate anion, but not for the conformational change induced by substrate binding.. |
| 27. | Takayuki Ohnuma, Mikako Yagi, Takeshi Yamagami, Toki Taira, Yoichi Aso, Masatsune Ishiguro, Molecular cloning, functional expression, and mutagenesis of cDNA encoding rye (Secale cereale) seed chitinase-c, BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 66, 2, 277-284, 2002.02, We cloned a complete cDNA encoding rye seed chitinase-c, designated RSC-c, by rapid amplification of cDNA end and PCR procedures. The cDNA of RSC-c consists of 1,018 nucleotides and includes an open reading frame encoding a polypeptide of 266 amino acid residues. A recombinant RSC-c was produced by expression in Escherichia coli Origami(DE3) and purified. rRSC-c had almost the same chitinase activity toward glycolchitin and antifungal activity against Trichoderma sp. as the authentic RSC-c did. RSC-c mutants were subsequently constructed and characterized with respect to their chitinase and antifungal activities. Mutation of Glu67 to Gln completely abolished the chitinase activity and diminished the antifungal activity. Considerable decreases in both activities were observed in the mutations of Trp72 and Ser120 to Ala, and Glu89 to Gln. The roles of these residues in the catalytic event of RSC-c are discussed.. |
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