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TSUJITA Maki

    Graduate School of Medical Sciences Department of Biochemistry　Lecturer
Contact： mtsujitamed.nagoya-cu.ac.jp
Last Updated :2024/04/24

Researcher Information

Degree

  • Doctor of Philosophy in Medical Science（Kagawa Medical School）
  • Doctor of Philosophy in Science（Konan University）

URL

J-Global ID

Profile

  • Biography
    Dr. Tsujita received her Bachelor of Science in biology from Konan University in 1984, a Master of Science in biology from Kobe University in 1989, and Ph.D. (Doctor of Medical Science) in biochemistry from Kagawa Medical School in 1993. In the same year, Dr. Tsujita became an Assistant Professor in the Department of Biochemistry, Kagawa Medical School. She took a concurrent position as a postdoctoral fellow in the Lipids and Lipoprotein Research Group at the University of Alberta, Canada. Dr. Tsujita started working as an Assistant Professor in the 1st Department of Biochemistry at Nagoya City University Graduate School of Medical Sciences in 1996. She received a Young Scientific Research Award in 1999, International Collaboration Journals Award in 2019 from Nagoya City University, and Paul Dudley White International Scholar Award in 2021 from The American Heart Association. She also received a second Ph.D. (Doctor of Science) from Konan University in 2003. Dr. Tsujita became an Associate Professor of Biochemistry in Nagoya City University Graduate School of Medical Sciences in 2008. She started her English education early in her life as an elementary school student in the USA. Her and her families were residents of Los Angeles and Irvine California from 1974 to 1976 where her father was a graduate student in computer sciences during his sabbatical. Dr. Tsujita taught medical English to students at Nagoya City University and presented her research at many international meetings. Dr. Tsujita is a member of the organizers and a scientific advisory board member of the FEBS-ABC meeting. A member of the International Committee of the Japan Atherosclerosis Society, a member of the Council of the Japan Biochemistry Society, and an International Fellow, conferred by ATVB, of the American Heart Association(FAHA).

    Research Program
    Dr. Tsujita has studied the molecular mechanism of nascent HDL, nanodisc HDL, generation for many years. She discovered that the drug probucol is an inhibitor of the ATP binding cassette A1 (ABCA1) transporter, revealing that ABCA1 is responsible for plasma HDL assembly. Dr. Tsujita measured HDL assembly in hepatocytes, the major tissue where most apolipoprotein A-I is synthesized. ApoA-I secretion is responsible for the initiation of the assembly of the nanodisc HDL, preb-HDL. Currently, Dr. Tsujita is interested in the function of ApoA-I, generated in the liver and small intestine, on cholesterol metabolism in humans and in mouse models. The nanodisc-HDL is the 10 nm disc that can be a carrier of hydrophobic vitamins and other compounds through the blood into tissues. Maintenance ABCA1 and ApoA-I expression provide the nanodisc HDL functionality associated with health and longevity. Dr. Tsujita is a co-inventor of oxidized probucol compound which raises plasma HDL through stabilizing ABCA1 protein for nanodisc HDL synthesis.

Research Interests

  • primary culture, in vivo study in mice   Lipoprotein metabolism, HDL   

Research Areas

  • Life sciences / Medical biochemistry / Lipids and lipoproteins metabolism

Academic & Professional Experience

  • 2019 - Today  Associate Professor, Biochemistry, Nagoya City University Graduate School of Medical Sciences
  • 2008 - 2019  Associate Professor, Biochemistry, Nagoya City University Graduate School of Medical Sciences
  • 1996 - 2008  Assistant Professor, Biochemistry 1, Nagoya City University Medical School (Nagoya, Japan)
  • 1993 - 1996  Postdoctoral fellow, Lipid and Lipoprotein Research Group, University of Alberta, Canada.
  • 1993 - 1996  Assistant Professor, Biochemistry, Kagawa Medical School

Education

  •        - 1993  Kagawa Medical School  Graduate School of Medicine  Biochemistry
  •        - 1989  University of Kobe  Graduate School of Science  Biology
  •        - 1987  Konan University  Faculty of Science  Biology

Association Memberships

  • Japan Society for Dementia Research   Japan Transporter Research Association   P450_UGT_SULT   European Atherosclerosis Society   American Heart Association, ATVB (International Fellow of AHA)   The Japanese Circulation Society, Delegate (R6-R7)   Japan Atherosclerosis Society(International committee member, and Council member)   The Japanese Biochemical Society (Counsil member)   The Japanese Society for Neurochemistry   

Published Papers

Books etc

  • Maki Tsujita (Single work)Science Impact Ltd 2023/09
  • Molecular Basis of Cellular Cholesterol Efflux and Regulation of Plasma HDL level
    Springer 2000 
    Lipoprotein Metabolism and Atherosclerosis (ED. Toru Kita and Masayuki Yokode)
  • Molecular Basis for cellular cholesterol efflux and regulation of plasma HDL levels.
    Elsevier Secience B.V 1999 
    Common Disease: Genetic and pthogenetic Aspects of Multifactorial Diseases, (Ed. Imura I, Kasuga M and Nakao K.
  • An essential amino acid sequence of the substrate (amine)-binding region of porcine FAD-containing monooxygenase.
    University of Calgary Press 1996 
    Flavins and Flavoproteins (Ed. Stevenson KJ, Massey V, Williams, Jr CH)
  • Cholesterol-binding region of cytochrome P450scc(P450XIA1): identification and amino acid sequence of the cholesterol binding domain.
    John Libbey Eurotext 1994 
    Cytochrome P450 Biochemistry, Biophysics and Molecular Biology (Ed Lechner MC)
  • Physicochemical Properties of Retinal Oxidase Purified from Rabbit Hepatic Cytosol.
    1993

Conference Activities & Talks

  • Maki Tsujita
    UCSF Cardiac Electrophysiology research conference  2024/05
    Download
  • Apolipoprotein A-I in the brain  [Invited]
    Maki Tsujita
    HDL workshop 2024  2024/05
  • Maki Tsujita
    Brigham and Women’s Hospital Genetics Division Seminar, Harvard New Research Building (NRB), room 457  2023/05
    Download
  • Maki Tsujita
    Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstrasse 13a, 1090 Vienna, "Gr. HS Pharmakologie"  2023/02
    Download
  • MAKI TSUJITA
    Special seminar (virtual), Building 37 Room 3106, NCI, NIH, Bethesda, MD, USA  2022/11
  • Maki Tsujita
    Research Seminar, Building 10 6F, NHLBI, NIH, Bethesda, MD, USA  2022/11
  • Maki Tsujita; Juniki Yamamoto; Rinka Maehashi; Alan T Remaley; Chieko Mineo; Philip W Shaul; Shinji Yokoyama; Keiichiro Okuhira
    19th International Symposium on Atherosclerosis(ISA2021)  2021/10
  • Story of my favorite ABC transporters: ABCA1 and ABCG1  [Invited]
    Maki Tsujita
    Biochemistry program, Aston University, college of health & Life Sciences, School of Biosciences, Birmingham, UK,  2021
  • Hepatocyte and intestinal apoA-I generation are the origin of mouse CSF apoA-I mainly dependent to ABCA1  [Invited]
    Maki Tsujita; Boris Vaisman; Kasey C Vickers; Marina Tachinbana; Kei-ichiro Okuhira; Sten Braesch-Andersen; Alan T Remaley
    ABC2020 - 8th FEBS Special Meeting ATP-Binding Cassette (ABC) Proteins: From Multidrug Resistance to Genetic Diseases, Innsbruck  2020/03
  • Liver and small intestine derived apoA-I in CSF: A conditional knockout mouse study  [Invited]
    Maki Tsujita
    Impromptu Seminar, Medical University of Vienna  2020/02
  • Maki Tsujita
    Research presentation, University of Cincinnati Metabolic Diseases Institute  2019/05
  • Bioinspired nanodisc-HDL with many unexpected applications  [Invited]
    Maki Tsujita
    UK ABC Meeting, Queen Mary University of London  2019
  • ABCG1 modulates Amyloid beta generation in CNS  [Invited]
    Maki Tsujita
    Seminar, J.A.B. School of Medicine, University of Hawaii at Manoa  2018
  • ABCG1/ABCG4 Modulates Amyloid Beta Production in the Central Nervous System  [Invited]
    Maki Tsujita; Alan T Remaley; Michinori Matsuo
    Gordon conference, Lipoprotein Metabolism in the Brain and Circulation and Its Role in Disease.  2018  Waterville Valley, NH, USA
  • Probucol Increased Adrenal CYP11a1, HMGCoAR and VKORC1 Expression and Rescued LCAT Null Male Mice Propagation  [Not invited]
    Maki Tsujita; Hiroshi Takase; Naohisa Hosomi; Nobukatsu Akita; Nobuyuki Ohte; Takashi Yamazaki; Shinji Yokoyama
    The 20th International Conference on Cytochrome P450, Dusseldorf  2017  D?sseldorf, Germany
  • Multiple functions of Scavenger Receptor class B type I: From taste cells to plasma apoA-I recycling  [Not invited]
    Tsujita M
    Seminar, Department of medicine, UT southwestern medical center  2017  Dallas, USA
  • SR-BI involved on plasma HDL2-apoA-I recirculation to preβHDL in mice  [Not invited]
    Maki Tsujita; Tomo Yokota; Nobukatsu Akita; Frank J Gonzalez; Shinji Yokoyama
    The 84th EAS Congress, Innsbruck  2016  Innsbruck, Austria
  • ABCA1/G1/G4 transporters in pre-beta-HDL and beta-amyloid assembly/biosynthesis in mice  [Invited]
    Tsujita M
    Lecture, Department of Medicine, Harvard University,  2016  Boston, USA
  • Hyperglycemia modulates HDL biogenesis: Implication for diabetic atherosclerosis  [Invited]
    Tsujita M
    Lecture, Cardiovascular Medicine, Vanderbilt University  2016  317PRB Vanderbilt University, Nashville, Tennessee, USA
  • Lipoprotein Characterization using Transmission Electron Microscopy and the Developer Toobox(R)  [Not invited]
    Tsujita M
    Lecture, Lipoprotein Metabolism Section, NHLBI, NIH  2015  10/8N212, NHLBI, NIH, Bethesda, USA
  • Hyperglycemia modulates HDL biogenesis: Implication for diabetic Atherosclerosis.  [Invited]
    Tsujita M
    DOCE seminar Diabetes and Metabolism Seminar Series, University of Washington  2015  Orin Smith Auditorium, SLU Campus, University of Washington, Seattle USA
  • Probucol, an anti-lipidemic drug, rescued reproduction of hypo-lipoproteinemia model mice.  [Not invited]
    Tsujita M
    Department of Chemistry and Biochemistry, California State University, Long Beach Seminar  2015  CSULB, Long Beach, USA
  • Probucol rescued litter size and genome type ratio in reproduction of hypolipoprteinemia model mice  [Invited]
    Tsujita M
    Children's Hospital Oakland Research Institute (CHORI) Research Seminar,  2015  the Little Theatre in Room 2319 CHORI, Oakland, USA.
  • Role of PPAR alpha in cardiovascular disease.  [Not invited]
    Tsujita M
    Special Seminar, NCI, NIH  2009  Laboratory of Metabolism, NCI, NIH, Bethesda, USA
  • Study of the non-specific pathway(s) dependent cellular cholesterol efflux.  [Invited]
    Tsujita M
    iCAPTURE Center for Cardiovascular and Pulmonary Research seminar, University of British Columbia  2008  University of British Columbia, Vancouver, Canada
  • Contribution of non-apoAI:ABCA1 pathways for cholesterol homeostasis.  [Invited]
    Tsujita M
    Lecture, NHLBI, NIH  2007  Lipoprotein Metabolism Section, NHLBI, NIH, Bethesda, USA
  • Apolipoprotein AI-dissociated from HDL and react with ABCA1 protein to generate HDL particles.  [Not invited]
    Maki Tsujita; Kei-ichiro Okuhira; Cheng-ai Wu; Shinji Yokoyama
    FEBS Special Meeting: ATP-Binding Cassette(ABC) Proteins: From Multidrug Resistance to Genetic Disease  2006  Innsbruck, Austria
  • The risk of Atherosclerosis reduce by elevation of HDL?  [Not invited]
    TSUJITA Maki
    Lecture, The Heart Research Institute  2005  Sydney, Australia
  • Does elevations of HDL reduce the risk of Atherosclerosis.  [Invited]
    Tsujita M
    CSIRO lecture, CSIRO Health Sciences and Nutrition  2005  CSIRO Health Sciences and Nutrition, Adelaide, Australia
  • HDL generation by the ABCA1/apoAI mediated pathway.  [Invited]
    Tsujita M
    CHORI Seminar Series, Children's Hospital Oakland Research Institute (CHORI) Research Seminar,  2005  Oakland, USA
  • Apolipoprotein-mediated cellular cholesterol efflux is a major source of plasma high density lipoprotein in mice.  [Not invited]
    Tsujita M; Tomimoto S; Okumura-Noji K; Usui S; Okazaki M; Yokoyama S
    High Density Lipoproteins and Atherosclerosis IAS Satellite Symposum  2000  Helsinki, Finland
  • Apolipoprotein A-I mediated cellular cholesterol efflux.  [Not invited]
    Tsujita M
    Eli Lilly and Company, Lilly Corporate Center,  2000  Indianapolis, USA
  • Apolipoprotein mediated cellulat cholesterol release  [Invited]
    Tsujita M
    Lipid and Lipoprotein Research Group seminar, University of Edmonton  1999  Edmonton, Canada
  • Modulation of Apolipoprotein-mediated cellular cholesterol efflux  [Not invited]
    Maki Tsujita; Shinji Yokoyama
    The Molecular Basis of HDL Antiatherogenicity  1994  Halifax, Canada

MISC

Awards & Honors

  • 2021/09 The American Heart Association Paul Dudley White International Scholar Award
     
    受賞者: Maki Tsujita;Hiroshi Takase;Natsuko Kumamoto;Shinya Ugawa;Yoshito Furuie;Motonari Tsubaki
  • 2019/10 Nagoya City University International Collaboration Journals Award
     
    受賞者: Maki Tsujita
  • 2019/05 the American Heart Association International Fellow, conferred by ATVB
     
    受賞者: Maki Tsujita
  • 1999/12 Nagoya City University Medical Research Award
     
    受賞者: Maki Tsujita

Research Grants & Projects

  • Japan Agency for Medical Research and Development：難治性疾患実用化研究事業
    Date (from‐to) : 2023/04 -2026/03
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2022/04 -2025/03 
    Author : 辻田 麻紀; 横山 信治; 奥平 桂一郎
  • Japan Health & Research Institute：The 46th Research Grant
    Date (from‐to) : 2020/05 -2021/03 
    Author : Maki Tsujita
  • The Watanabe Foundation：The 26th Magnetic Research Grant
    Date (from‐to) : 2020/04 -2021/03 
    Author : Maki Tsujita
  • Takahashi Industrial and Economic Research Foundation：Research Grant
    Date (from‐to) : 2018 -2019 
    Author : Maki Tsujita
  • The Great Britain Sasakawa Foundation：Butterfield Awards for UK-Japan collaboration in medical research and public health practice
    Date (from‐to) : 2018 -2019 
    Author : Kenneth J. Linton; Maki Tsujita
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2015/04 -2018/03 
    Author : Hosomi Naohisa
     
    We have tried to evaluate associations of transmembrane protein 95 on neuronal physiological function and ischemic neuronal cell death for elucidating a part of mechanism of neuronal cell death in ischemic stroke, And, we aimed to develop a hemodiagnosis in acute ischemic stroke with developing quantitive assay of transmembrane protein 95. We have created several antibodies against transmembrane protein 95 to construct ELISA system. Specificity and sensitivity of those antibodies were still on analysis.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2015/04 -2018/03 
    Author : TSUJITA MAKI
     
    The TICE is alternative pathway for reverse cholesterol transport. Acceleration of TICE pathway may become one of the new strategies without causing cholesterol polypus leading cholecystolithiasis, or gallbladder inflammation. We aim to evaluate SR-BI function on TICE which SR-BI receptor also localized at basolateral membrane in intestinal absorptive cell. In the project, SR-BI flox and CAG-Cre mice were obtained. The SR-BI fx/fx-CAG+ mice was created. The plasma analysis indicated accumulation of large HDL. This result proved the quality of the SR-BI flox mice and current propagation system. Vil-Cre mice and Alb-Cre mice have arrived from the collaborator to create intestinal- and liver-specific SR-BI KO mic for the future study. WT mice plasma was harvested and the isolated mouse LDL, HDL, and mouse apoA-I were shipped to the company and the rat monoclonal antibodies were successfully ready. They will be also useful tool for mouse lipoprotein analyses for up-coming experiments.
  • Takahashi Industrial and Economic Research Foundation：平成29年度助成金
    Date (from‐to) : 2017 -2018 
    Author : Maki Tsujita
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2011/04 -2015/03 
    Author : TSUJITA Maki; YOKOYAMA Shinji; UGAWA Shinya
     
    Transintestiinal cholesterol efflux (TICE) is the alternative cholesterol secretion pathway which has been focus for some years. To evaluate the fate of HDL-cholesterol in mice plasma, we injected 3H-labeled cholesterylether in HDL. SR-BI is known for HDL-cholesterylester receptor. In SR-BI null mice, the uptake of chosteryleter from injected HDL was significantly reduced liver and adrenalas well as in small intestine. Next, wild type mouse was perfused with PBS followed by the fixation solution (4%PFA/0.1M PB).SR-BI was detected by primary antibody and streptavidin bound Alexa Fluor594. The Nicon A1RS1 confocal microscope system was used for detection. SR-BI was stained at basolateral surface of some small intestinal absorptive epithelial cells. As control, intestinal cholesterol receptor, NPC1L1 was localized only in the apical surface in this experimental condition. This result suggests plasma HDL-cholesterol may uptake into small intestinal cells through SR-BI in mice.
  • 日本学術振興会：科学研究費助成事業 特定領域研究
    Date (from‐to) : 2004 -2004 
    Author : 伊藤 仁一; 横山 信治; 堂前 純子; 辻田 麻紀
     
    脳内HDLが中枢神経組織構築や障害修復機転に重要な役割をもつことが次第に明らかになり、アストロサイトの分泌するapoEによって新生されるHDL(apoE/HDL)の脳内コレステロールホメオスタシスおよび中枢神経系組織構築や損傷修復における役割は多大であると思われる.血液脳関門により体循環から隔てられた中枢神経組織という特殊な環境下にあって、アストロサイトによって新生されるapoE/HDLの多岐にわたる機能の作用機序の解明はアルツハイマー病や脳損傷などに限定されず脳全般に渡る機能障害とその修復機構解明に大きく寄与する.われわれは、正常マウス、apoE欠損マウスを用い、脳損傷(凍傷)後のFGF-1産生、apoE産生を解析し、様々な障害におけるFGF-1/apoE-HDL系の傷害修復機転に於ける特異性を検討した。 apoE欠損マウスと正常マウスの大脳にドライアイスで凍傷損傷を作成し、経時的にfibroblast growth factor-1(FGF-1)とapoEの産生を観察した.正常マウス大脳では、損傷後2日でFGF-1の産生が認められ、損傷後4日以降にapoEの産生が認められた.一方、apoE損傷マウス大脳ではapoE産生は認められなかったものの、FGF-1産生は正常マウス大脳と同様に損傷後2日後に認められた.脳損傷後2週間において、脳損傷部位の半径は見かけ上apoE欠損マウス大脳に比べ、正常マウス大脳では著しく退縮しており、apoE欠損マウス大脳の損傷修復に遅延が認められた.以上のことから、損傷後の脳においてFGF-1の産生は、apoEのそれに先行し、FGF-1を介したapoE産生亢進システムは、脳損傷修復において大きな役割をもつことが示唆された.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2003 -2004 
    Author : TSUJITA Maki; YOKOYAMA Shinji; DOHMAE Sumiko; OKAZAKI Mitsuyo
     
    The mechanism for the assembly of HDL with cellular lipid by ABCA1 and helical apolipoprotein was investigated in hepatocytes. Both HepG2 cells and mouse primary culture hepatocytes produced HDL with apolipoprotein A-I whether endogenously synthesized or exogenously provided. Probucol, an ABCA1 inactivator, inhibited these reactions, as well as the reversible binding of apoAI to HepG2. Primary cultured hepatocytes of ABCA1-deficient mice also lacked HDL production regardless of the presenceof exogenous apoAI. HepG2 cells secreted apoAI into the medium even when ABCA1 was inactivated by probucol, but it was all in a free form as HDL production was inhibited. When a lipid-free apoAI-specific monoclonal antibody, 725-1E2, was present in the culture medium, production of HDL was suppressed, whether with endogenous or exogenously added apoAI, and the antibody did not influence HDL already produced by HepG2 cells. We concluded that the main mechanism for HDL assembly by endogenous apoAl in HepG2 cells is an autocrine-like reaction in which apoAI is secreted and then interacts with cellular ABCA1 to generate HDL.
  • 日本学術振興会：科学研究費助成事業 特定領域研究
    Date (from‐to) : 2003 -2003 
    Author : 伊藤 仁一; 辻田 麻紀; 堂前 純子; 横山 信治
     
    中枢神経組織におけるコレステロールホメオスタシスを理解するため、脳内での細胞間コレステロール輸送を主要に担う脳内HDLについて、その主たる供給細胞であるアストロサイトに於ける産生機構とその病態生理を検討した。その結果、ラットアストロサイトは自らapoEを合成・分泌しコレステロールに富んだHDLを産生する一方、外来性のapoA-Iに反応してコレステロールに乏しいHDLを新生することを見い出した。 本研究において、わたしたちはラット脳を1ヵ月間primary cultureしてストレスを負荷することにより、acidicFGF(aFGF)様因子が産生・分泌され、これがアストロサイトのapoEおよびコレステロールの産生と分泌を強く促進することを見い出した.acidicFGF(aFGF)様因子の産生細胞を検討した結果、RT-PCRによりラット脳1ヵ月primary cultureから調製されたアストロサイトがacidicFGF-mRNAを強く発現することがわかった.また、組織免疫染色により長期間primary cultureされたアストロサイトは抗acidicFGF抗体で強く染色された.さらに35S-Methionineでアストロサイトをラベルすると、アストロサイト細胞内および培養ろ液中に16.5kDaの抗acidicFGF抗体で認識されるタンパク質が認められた.これらの結果より、アストロサイト自身がacidicFGFを産生し、オートクリン形式でアストロサイトに作用して、apoEおよびコレステロールの産生分泌を高め、細胞のストレスに対する保護作用を発揮することが考えられる.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2002 -2003 
    Author : YOKOYAMA Shinji; TSUJITA Maki; ABE Sumiko; ITO Jinichi
     
    1)ABCA1 is phosphorylated by RKCa activated by diacylglycerol generated in the reactions to replenish sphingomyelin that is removed by apoA-I to generate HDL. This reaction is generally observed with helical apolipoproteins that are capable of generating HDL, as well as the model peptides mimicking amphiphilic helices of apolipoprotein. 2)Human ABCA7 that is highly homologous to ABCA1mediates generation of HDL is stabilized by apolipoproteins in a similar manner to that of ABCA1 when expressed in HEK293. 3)Release of cellular cholesterol to HDL is mediated by two distinct mechanism ; non-specific exchange and an apolipoprotein/ABCA1 mediated pathway. The latter reaction was investigated by using an anti-apoA-I monoclonal antibody that recognizes only lipid free apoA-I. This antibody inhibited the ABCA1-dependent part of the cholesterol release reaction. The ABCA1-dependent HDL abiding to cells is only its protein moiety but not the lipid part. Thus, apoA-I dissociates from HDL and interacts with the cells to generate new HDL.
  • Japan Society for the Promotion of Science：Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2001 -2002 
    Author : Maki Tsujita
     
    HepG2細胞にプロブコール含有LDLを投与し、アポAIによる特異的な細胞脂質の搬出機構を阻害してHepG2細胞からのリポタンパク質新生反応における本経路の寄与を検討した。 培養上清をTSKゲルLIPOPROPAK-XLで分離し、それをオンラインで脂質定量を行なった。コントロールLDLを投与したHepG2細胞からはLDL粒子サイズに相当するコレステロール/リン脂質のピークがと大型のHDLに相当するコレステロール/リン脂質のピークが観察された。一方プロブコール含有LDLを投与したHepG2細胞の培養上清を分析すると、LDL粒子の産生量は変化しないがHDL産生が顕著に減少していた。このことからHepG2細胞が産生するHDL粒子はプロブコールによって阻害される機構によってその大部分が産生されることが示唆される。プロブコールを投与したマクロファージ細胞ではアポAIによる細胞コレステロールの搬出のみが特異的に阻害されることは既に報告している。この結果よりプロブコールがアポAIによる細胞コレステロールの特異的な搬出機構の阻害剤であると考えられるので、ここでも同様な阻害効果が期待され、それによりHepG2細胞でのHDLの新生反応はそのほとんどがアポAIによる細胞コレステロールの搬出経路によることが示唆された。 タンジール病患者の細胞はアポAIによる細胞コレステロール搬出を消失している。この原因となるタンパク質は細胞表面のABCA1タンパク質である。プロブコールがこのABCA1タンパク質に与える影響を調べる目的で細胞全体のABCA1タンパク質をウエスタンブロッティング法で測定した。その結果ABCA1タンパク質量はHDL新生の阻害されているプロブコール投与HepG2細胞でもコントロールと差が無く、プロブコールがABCA1量へは影響を与えない事が明らかになった。
  • 日本学術振興会：科学研究費助成事業 特定領域研究(C)
    Date (from‐to) : 2001 -2001 
    Author : 横山 信治; 辻田 麻紀; 堂前 純子; 伊藤 仁一
     
    脳内のコレステロール代謝平衡は血漿リポタンパク質からは独立し、脳内で独自に産生されたHDLにより担われ、HDL欠損症においても中枢神経系の障害を認めない。これまでに我々は、脳独自のHDL新生機構として、アストロサイトは自ら合成する内因性のアポEによりコレステロールに富むHDLを産生する一方で、外因性のアポA-l等に反応してコレステロールの乏しいHDLを産生することを明らかにしてきたており、更にその制御機構の検討を行っている。脳細胞を長期間(4週間)培養した後アストロサイトを分離すると、内因性アポEによるHDL産生は、アストロサイト自身が産生する酸性FGFによるauto crine機序によって刺激を受け、これによるHDL新生とコレステロール放出の増加によりアストロサイト内のコレステロール代謝が更新することが認められた(Ueno et al.BBA in press)。現在、酸性FGFの合成が高まる病態をin vivoにおいて検討している。また、アストロサイトと外因性アポリポ蛋白質による反応によりHDLが新生するとき、ERで新規に合成されたコレステロールがcaveolin-1とともに細胞質に移動して脂質・蛋白質複合体をつくり、この後HDL中に現れてくることが見いだされた。これらの結果は、アストロサイトの2種類のHDLの分別産生機構が脳の障害修復機転と関連があることを示唆した(Ito et al.JBC 277: 7929-7935,2002)。
  • 日本学術振興会：科学研究費助成事業 特定領域研究(C)
    Date (from‐to) : 2000 -2001 
    Author : 横山 信治; 辻田 麻紀; 堂前 純子; 伊藤 仁一
     
    脳内のコレステロール代謝平衡は血漿リポタンパク質からは独立し、脳内で独自に産生されたHDLにより担われ、HDL欠損症においても中枢神経系の障害を認めない。脳独自のHDL新生機構の探索の結果、アストロサイトは自ら合成する内因性のアポEによりコレステロールに富むHDLを産生する一方で、外因性のアポA-I等に反応してコレステロールの乏しいHDLを産生することが分かった。さらにこの仕分けは形質膜のraft domainのスフインゴミエリンによるコレステロール分子の拘束により制御されていることが示された(Ito J,Nagayasu Y,Yokoyama S.J.Lipid Res.2000,41:894-904.)。また、アストロサイトは未分化型ではアポE合成を行わず外因性のアポリポ蛋白質によってコレステロールに富んだHDLを新生する事から、このような特徴は細胞の分化とそれによる内因性のアポEの生合成能によって調節されることが示唆された(Zhang LY,Ito JI,Kato T,Yokoyama S.J.Biochem.2000,128:837-845.)。アストロサイトには神経細胞との共培養で強いアポE産生とコレステロールに富んだHDL放出が見られ、これは神経細胞からの液性因子によるアストロサイト自身からの酸性FGFの放出によるものであることが分かった。これらの結果は、アストロサイトの2種類のHDLの分別産生機構は脳の障害修復機転と関連があることを示した。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2000 -2001 
    Author : YOKOYAMA Shiniji; TSUJITA Maki; DOHMAE Sumiko; ITO Jinichi; AOTSUKA Tomoshi
     
    During the current grant term, research accomplishment is summarized below for the mechanism and physiological relevance of HDL assembly by apolipoprotein-cell interaction. Inhibition of the HDL assembly reaction by an HDL-lowering drug probucol was reproduced in mice in vivo, and demonstrated the this reaction is a main source of plasma HDL (BBA 1485 : 199, 2000) and the main organ for the reaction is the liver (ATVB 21, 394, 2001). Assembly of HDL in mouse monocytic leukemia cell RAW 264 is induced by cAMP in parallel with physical binding of apolipoprotein to the cell, and with 10-tome increase of abca1 mRNA (Biochemistry 39, 11092, 2000). From the experiments with THP-1 cells and fibroblasts, it was revealed that ABCA1 is not absolute requirement for the HDL assembly, that caveolin-1 plays an important role in incorporation of cholesterol into the HDL, and that progesterone inhibits this pathway by an unknown mechanism (JLR 41, 1952, 2000 ; JBC277, 7929, 2002 ; BBA 1532, 173, 2001). Membrane raft was suggested to be a site for the HDL assembly (JLR41, 894, 2000). When ABCA1 is transfected and functionally expressed in HEK293, the protein was shown with a signal peptide cleaved and the N-terminal exposed to outside (BBRC 283, 1019, 2001). A part of the results above is summarized in a review article (BBA 1529, 231, 2000).
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A).
    Date (from‐to) : 1998 -1999 
    Author : YOKOYAMA Shinji; TSUJITA Maki; DOHMAE Sumiko; ITO Junichi
     
    We studied the HDL assembly system mediated by apolipoprotein-cell interaction by using three model systems. 1) Study on the apolipoprotein interaction site in mouse leukemic cell line cells RAW 264. A kinase must be activated for this cell to express the binding site with apolipoprotein and to gegerate HDL with cellular lipid. It takes several hours for the full expression which is suppressed by various metabolic inhibitors for protein synthesis. Therefore, contribution of a membrane protein(s) is suggested. Interestingly, there was no apparent difference in expression of ABC1 which has been shown as a mutation site in familial HDL deficiencies. 2) Study on intracellular cholesterol trafficking linked to the HDL assembly system in human leukemic cell line cells THP-1. While THP-1 cells gegerate HDL only with cellular phospholipid by apolipoprotein before differentiation, HDL is enriched with cholesterol after PMA induces differentiation. Both ABC1 and caveolin-1 are induced by PMA, and the antisense DNA selectively reduces cholesterol content in the HDL generated. Therefore, caveolin-1 is responsible for incorporation of cholesterol into the HDL. 3) Study on physiological relevance of the HDL assembly system in a mouse model by using an inhibitor of the apolipoprotein-cell interaction, probucol. Mouse HDL is rapidly and remarkably decreased by probucol, while no significant change is demonstrated in the massages of HDL-relating proteins including ABC1 and in the HDL clearance. The HDL assembly by apolipoprotein and the peritoneal macrophage is markedly decreased by probucol, showing that this is a major source of plasma HDL in mice.
  • Japan Society for the Promotion of Science：Grant-in-Aid for Encouragement of Young Scientists (A)
    Date (from‐to) : 1998 -1999 
    Author : Maki Tsujita
     
    研究目的: Lecithin:cholesterol acyltransferase(LCAT)はHDL上でcholesterolをアシル化し、cholesterylester transfer protein(CETP)はこれをリポ蛋白質中に分配する。元来CETPを欠くマウスにこれを導入してヒトに近づけ、LCATをノックアウトする事によってヒトLCAT欠損症のモデルを作成して、その病態を研究する。特に我々が報告したアポリポ蛋白質によるcholesterol搬出の産物であるpreβ-HDLに注目する。 研究計画・結果: 1.CETP transgenic LCAT knockout mouseの作成。 現在我々が所有するヒトCETP trancgenic miceはヒトCETP遺伝子をβ-アクチンプロモーターに連結した発現ベクターを用いて形成され、またLCAT knockout miceはLCATのexon1の部位をneo遺伝子に置き換えて作成されている。これらを掛け合わせ、CETP transgenic/LCAT knockout mouseのコロニーを作成する。遺伝子型はtailDNAより同定し、最終的にCETP(+/+)、LCAT(-/-)の遺伝子型を持つマウス群を作成した。 2.血漿中リポ蛋白質の解析。 血漿中リポ蛋白質の解析は高速液体クロマトグラフィーを用い、CETP transgenic mouse、LCAT knockout mouse、並びにCETP transgenic LCAT knockout mouseのVLDL、LDL、HDLのcholesterol、リン脂質、トリグリセライドをオンラインで測定、分析した。LCAT(-/-)マウスではCETPの発現の有無に関わらずHDLは観察されず、低HDL血症を示した。LCAT(+/-)ではCETPの発現していないマウスでは野生型とほぼ同値のHDLが見られたが、CETP発現マウスではその発現量によりHDLが大きく低下していた。このことより血中HDL量はLCATとCETPの発現量の比により変化する事が観察された。 3.血漿中preβ-HDLの測定システムの開発。 現在HDLの新生源として注目されているpreβ-HDLは主に2次元電気泳動によって測定されているが、我々の研究室ではpreβHDLにのみ反応するペプチド抗体を用いて血漿中に微量に存在するpreβ-HDLを測定する系を確立中である。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 1997 -1998 
    Author : YOKOYAMA Sinji; TSUJITA Maki; ABE-DOHMAE Sumiko; ITO Jinichi
     
    Two independent mechanisms are known for cellular cholesterol removal ; physicochemical diffusion and apolipoprotein-cell interaction that causes HDL neogenesis. This research project focused on the latter pathway to achieve the results as follows. 1) First year. In mouse peritoneal macrophages, PKC inhibitors suppressed the incorporation of cell cholesterol into the HDL generated with apolipoproteins though apolipoprotein binding to the cell and generation of HDL itself are uninfluenced, showing that this is due to inhibition of specific intracellular cholesterol trafficking. Mouse monocytic leukemia cell line cells RAW264 do not interact with apolipoprotein for HDL generation until cAMP induces the expression of the interaction site. 2) Second year. The induction of the interaction site by cAMP in RAW264 was suppressed by inhibition of transcription, protein synthesis and protein transport, showing the involvement of membrane protein in the interaction site. Human monocytic leukemia cell line cells THP1 generate cholesterol-poor HDL with apolipoprotein, and differentiation by PMA results in the specific increase of cholesterol content in HDL.This cells line have therefore been shown to be a good model for induction of specific intracellular cholesterol trafficking.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 1997 -1998 
    Author : YOKOYAMA Sinji; TSUJITA Maki; ABE-DOHMAE Sumiko; ITO Jinichi
     
    Two independent mechanisms are known for cellular cholesterol removal ; physicochemical diffusion and apolipoprotein-cell interaction that causes HDL neogenesis. This research project focused on the latter pathway to achieve the results as follows. 1) Mouse monocytic leukemia cell line cells RAW264 require cAMP for apolipoprotein-mediated HDL generation, and naphthalene sulfonamides known as calmodulin inhibitors enhanced the HDL generation in this condition. This effect was unique to these compounds, being not shared with other calmodulin inhibitors. 2) In vivo regulation of plasma HDL level by the apolipoprotein-mediated HDL generation was studied by using the mice fed with probucol that inhibits the cell/apolipoprotein interaction. Probucol remarkably reduces the HDL level within 2 weeks without changing apoA-I biosynthesis and the plasma HDL clearance rate. Peritoneal macrophages obtained from these animals lost the apoA-I binding, HDL generation and the reactive intracellular cholesterol trafficking. Therefore, reduction of HDL cholesterol was shown to be due to the lack of apolipoprotein/cell interaction, a model for Tangier disease. 3) When the apolipoprotein-mediated HDL generation was blocked by probucol in the LCAT knock-out mice in which non-specific diffusion mediated efflux of cell cholesterol is impaired, cholesterol accumulated in certain organs as the liver and thymus.
  • Canada Alberta Heritage Foundation for medical research：奨学金
    Date (from‐to) : 1993 -1996 
    Author : Maki Tsujita

Teaching Experience

  • Student Lab Course at the Basic Medical DepartmentsStudent Lab Course at the Basic Medical Departments Nagoya City University Graduate School of Medical Sciences
  • Guidance for Freshman; Protection from HarassmentsGuidance for Freshman; Protection from Harassments Nagoya City University Graduate School of Medical Sciences
  • Problem Based LearningProblem Based Learning Nagoya City University Graduate School of Medical Sciences
  • Biochemistry Laboratory, Protein isolation and analysis of Alcohol dehydrogenase (Student Lab)Biochemistry Laboratory, Protein isolation and analysis of Alcohol dehydrogenase (Student Lab) Nagoya City University Graduate School of Medical Sciences
  • Clinical Interview (English)Clinical Interview (English) Nagoya City University Graduate School of Medical Sciences
  • Introduction to scientific articles Unit (Medical English)Introduction to scientific articles Unit (Medical English) Nagoya City University Graduate School of Medical Sciences
  • Journal seminar (Medical English)Journal seminar (Medical English) Nagoya City University Graduate School of Medical Sciences
  • Scientific Writing and Presentation (Medical English)Scientific Writing and Presentation (Medical English) Nagoya City University Graduate School of Medical Sciences
  • Human Biology (Medical English)Human Biology (Medical English) Nagoya City University Graduate School of Medical Sciences
  • Protein: Metabolism of Heme and PorphyrinProtein: Metabolism of Heme and Porphyrin Nagoya City University Graduate School of Medical Sciences
  • BiooxidationBiooxidation Nagoya City University Graduate School of Medical Sciences
  • LipidLipid Nagoya City University Graduate School of Medical Sciences
  • Cell biologyCell biology Nagoya City University Graduate School of Medical Sciences
  • VitaminVitamin Nagoya City University Graduate School of Medical Sciences
  • Biochemistry of Lipids and LipoproteinsBiochemistry of Lipids and Lipoproteins Nagoya City University Graduate School of Medical Sciences、University of Tokushima, Kyoto Women's College

Committee Membership

  • 2023/03 - Today   The ABC transporter FEBS Special Meeting   Organizer
  • 2022/11 - Today   The Japanese Biochemical Society   Council member
  • 2018/07 - Today   Japan Atheroscleosis Society   International comittee member, Council member
  • 2018/03 - Today   ABC2020-8th FEBS Special Meeting   ABC2020 Scientific Advisory Board
  • 2024/04 -2026/03   Japanese Circulation Society   Delegate member

Social Contribution

  • International examiner: The academic reputation surveys by QS Intelligence Unit(QSIU) and Times Higher Education(THE) team in United Kingdom
    Date (from-to) : 2022/12-Today
    Role : Commentator
    Category : Investigation
  • Public-Private Partnership Collaboration Support System for Studying Abroad, Special selection committee
    Date (from-to) : 2019/03/01-Today
    Role : Advisor
    Category : Others
    Sponser, Organizer, Publisher  : Japan Student Services Organization
  • Thesis examiner, Faculty of Medicine and Health, THE UNIVERSITY OF SYDNEY, Australia
    Date (from-to) : 2022
    Role : Advisor

Academic Contribution

  • Associate Editor in the Lipids in Cardiovascular Disease section of Frontiers in Cardiovascular Medicine
    Date (from-to) :2023/07-Today
    Role: Peer review
    Type: Peer review etc
  • Editorial Board Member of Nature Cell and Science
    Date (from-to) :2023/08-2024/12
    Role: Peer review
    Type: Peer review etc
  • Review Editor in the Lipids in Cardiovascular Disease section of Frontiers in Cardiovascular Medicine
    Date (from-to) :2022/02-2023/06
    Role: Peer review
    Type: Peer review etc

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