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Dive into the research topics where Takefumi Doi is active.

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Featured researches published by Takefumi Doi.


Cellular and Molecular Life Sciences | 1998

Scavenger receptor family proteins: roles for atherosclerosis, host defence and disorders of the central nervous system

Yoshihiko Yamada; Takefumi Doi; Takao Hamakubo; Tatsuhiko Kodama

Abstract. In this review, we summarize the structure and function of the scavenger receptor family of proteins including class A (type I and II macrophage scavenger receptors, MARCO), class B (CD36, scavenger receptor class BI), mucinlike (CD68/macrosialin, dSR-CI) and endothelial (LOX-1) receptors. Two motifs have been identified as ligand-binding domains a charged collagen structure of type I and II receptors, and an immunodominant domain of CD36. These structures can recognize a wide range of negatively charged macromolecules, including oxidized low-density lipoproteins, damaged or apoptotic cells, and pathogenic microorganisms. After binding, these ligands can be either internalized by endocytosis or phagocytosis, or remain at the cell surface and mediate adhesion or lipid transfer through caveolae. Under physiological conditions, scavenger receptors serve to scavenge or clean up cellular debris and other related materials, and they play a role in host defence. In pathological states, they mediate the recruitment, activation and transformation of macrophages and other cells which may be related to the development of atherosclerosis and to disorders caused by the accumulation of denatured materials, such as Alzheimers disease.


Pharmaceutical Research | 1999

Characterization of plasmid DNA binding and uptake by peritoneal macrophages from class A scavenger receptor knockout mice.

Yoshinobu Takakura; Toshihide Takagi; Miwa Hashiguchi; Makiya Nishikawa; Fumiyoshi Yamashita; Takefumi Doi; Takeshi Imanishi; Hiroshi Suzuki; Tatsuhiko Kodama; Mitsuru Hashida

AbstractPurpose. Plasmid DNA (pDNA) has become an important class of macromolecular agent suitable for non-viral gene therapy as well as DNA vaccination. Our recent study has suggested that pDNA is taken up by mouse peritoneal macrophages via a specific mechanism mediated by a receptor similar to the scavenger receptor (SR). This study was designed to further characterize the pDN A uptake by macrophages in order to elucidate the mechanism. Methods. The binding and uptake of pDNA labeled with 32P or a fluorescent marker were studied in vitro using cultured Chinese hamster ovary (CHO) cells expressing the class A scavenger receptor (SRA) and peritoneal macrophages from SRA-knockout mice. Results. pDNA binding and uptake by CHO(SRA) cells were minimal and almost identical to that by wild-type CHO cells. Macrophages from the knockout mice showed pronounced pDNA binding and uptake as did the control macrophages. In both types of macrophage, pDNA binding was significantly inhibited by cold pDNA, polyinosinic acid and dextran sulfate but not by polycytidylic acid or Ac-LDL. These results provide direct evidence that SRA is not responsible for the significant binding and subsequent uptake of pDNA by mouse peritoneal macrophages. Further binding experiments revealed that, in addition to polyinosinic acid and dextran sulfate, heparin was a potent inhibitor among a variety of polyanionic compounds such as poly-nucleotides, anionic polysaccharides and modified proteins including Ox-LDL. Conclusions. The present study suggest that pDNA binding and uptake by mouse peritoneal macrophages are mediated by a specific mechanism to some defined polyanions not by scavenger receptors. The finding would be an important basis for further studies to elucidate the mechanism(s) of pDNA uptake by macrophages.


Arteriosclerosis, Thrombosis, and Vascular Biology | 1999

Transcriptional Inhibition by Interleukin-6 of the Class A Macrophage Scavenger Receptor in Macrophages Derived From Human Peripheral Monocytes and the THP-1 Monocytic Cell Line

Hai Sun Liao; Akiyo Matsumoto; Hiroshige Itakura; Takefumi Doi; Makoto Honda; Tatsuhiko Kodama; Yong Jian Geng

Expression of the class A macrophage scavenger receptor (MSR) contributes to the uptake of modified low density lipoproteins (LDL) by macrophages and transformation of these cells into lipid-laden foam cells, which characterize atherosclerosis. Many environmental factors, in particular, proinflammatory cytokines and growth factors, can exert regulatory effects on MSR expression, whereas intracellular accumulation of cholesterol itself does not influence MSR levels to any considerable extent. In the present study, by using an in vitro model, we examined whether stimulation with interleukin-6 (IL-6), an immunoregulatory, multipotential cytokine, modulates the expression and activities of the MSR in macrophages. When treated with IL-6, macrophages derived from peripheral monocytes and phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 monocytic cells showed significantly reduced uptake and/or binding of the MSR ligand, acetylated LDL. This effect was paralleled by a reduction in the expression of MSR protein and mRNA. Analysis of MSR promoter activity in THP-1 cells transfected with an MSR promoter-reporter gene construct demonstrated decreased activity of the MSR promoter in IL-6-treated THP-1 macrophages. Electrophoretic mobility gel shift assay also showed a reduction in the binding of a transcription factor to the MSR promoter AP-1/ets elements in IL-6-treated cells. Thus, exposure to IL-6 may inhibit expression of the class A MSR in differentiated macrophages at transcriptional levels. This result suggests that this cytokine may modulate foam cell formation during atherogenesis.


Mechanisms of Ageing and Development | 1999

Structure and function of type I and II macrophage scavenger receptors

H. Shirai; Takeshi Murakami; Yoshihiko Yamada; Takefumi Doi; Takao Hamakubo; Tatsuhiko Kodama

Type I and II macrophage scavenger receptors are implicated in the pathologic deposition of cholesterol during the atherogenesis. There is a charged collagen structure of type I and II receptors identified as a ligand binding domain, which can recognize a wide range of negatively charged macromolecules including oxidized LDL as well as damaged or apoptotic cells and pathogenic micro-organisms. After binding these ligands can be either internalized by endocytosis, phagocytosis, or remain at cell surface and mediate the adhesion. Under physiological condition, scavenger receptors serve to scavenge or clean up cellular debris and other related materials, as well as playing a role in the hosts defence. In pathological condition, they mediate the recruitment, activation and transformation of macrophages and other cells, which may be related to the development of atherosclerosis and to disorders caused by the accumulation of denatured materials, such as Alzheimers disease.


Bioorganic & Medicinal Chemistry | 2001

Symmetrical cationic triglycerides: an efficient synthesis and application to gene transfer

Satoshi Obika; Wei Yu; Atsuko Shimoyama; Takeshi Uneda; Kazuyuki Miyashita; Takefumi Doi; Takeshi Imanishi

Some cationic triglycerides 1Aa-1Cb which have a symmetrical structure were effectively synthesized and formulated into cationic liposomes with the co-lipid dioleoylphosphatidylethanolamine (DOPE) and/or dilauroylphosphatidylcholine (DLPC). The plasmid encoding a luciferase was delivered into CHO cells by using these cationic liposomes. Our symmetrical cationic triglycerides showed high transfection activity when DOPE was used as a co-lipid. Among the symmetrical cationic triglycerides synthesized here, 1Ab and 1Ac, which have an oleoyl group at the 1- and 3-position in the glycerol backbone and also have a relatively long linker connecting the 2-hydroxy group in glycerol with the quaternary ammonium head group, were found to be the most suitable for gene delivery into cells. The transfection activity of the symmetrical cationic triglyceride 1Ab was comparable with that of its asymmetrical congener 6 and several times higher than that of Lipofectin.


American Journal of Pathology | 1991

Tissue distribution, intracellular localization, and in vitro expression of bovine macrophage scavenger receptors.

Makoto Naito; Tatsuhiko Kodama; Akiyo Matsumoto; Takefumi Doi; Kiyoshi Takahashi


Biochemical and Biophysical Research Communications | 1998

Immunohistochemical evidence for a macrophage scavenger receptor in Mato cells and reactive microglia of ischemia and Alzheimer's disease.

Makoto Honda; Haruhiko Akiyama; Yoshihiko Yamada; Hiromi Kondo; Yoshiki Kawabe; Motohiro Takeya; Kiyoshi Takahashi; Hiroshi Suzuki; Takefumi Doi; Atsushi Sakamoto; Shigeo Ookawara; Masao Mato; Peter J. Gough; David R. Greaves; Siamon Gordon; Tatsuhiko Kodama; Masaaki Matsushita


FEBS Journal | 1999

Oligonucleotide aggregates bind to the macrophage scavenger receptor

Kazuo Suzuki; Takefumi Doi; Takeshi Imanishi; Tatsuhiko Kodama; Toshiki Tanaka


Biological & Pharmaceutical Bulletin | 1999

VXFD in the cytoplasmic domain of macrophage scavenger receptors mediates their efficient internalization and cell-surface expression.

Kazunobu Morimoto; Youichiro Wada; Jun-ichi Hinagata; Takeshi Imanishi; Tatsuhiko Kodama; Takefumi Doi


Biological & Pharmaceutical Bulletin | 1999

Properties of cationic liposomes composed of cationic lipid YKS-220 having an ester linkage: adequate stability, high transfection efficiency, and low cytotoxicity.

Satoshi Obika; Wie Yu; Atsuko Shimoyama; Takeshi Uneda; Takeshi Minami; Kazuyuki Miyashita; Takefumi Doi; Takeshi Imanishi

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