Keiichi Takagaki

Hirosaki University, Khirosaki, Aomori, Japan

Are you Keiichi Takagaki?

Claim your profile

Publications (105)285.4 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Glycosaminoglycans were prepared as salts of different divalent cations and tested as donors in bovine testicular hyaluronidase catalyzed transglycosylation reactions. All of the metal cations examined had similar binding efficiency of divalent cations to hyaluronan. However, cations bound with different efficiencies to chondroitin sulfate species and the differences were marked in the case of chondroitin 6-sulfate; the numbers of cations bound per disaccharide unit were estimated to be 0.075 for Mn, 1.231 for Ba, 0.144 for Zn, and 0.395 for Cu. While barium salt of chondroitin sulfates enhanced transglycosylation, the zinc salt of chondroitin sulfates inhibited transglycosylation. Therefore, by selecting the proper divalent cation salt of chondroitin sulfates as a donor in the transglycosylation reaction it is possible to improve the yields of the products.
    Biochemical and Biophysical Research Communications 02/2011; 406(2):239-44. DOI:10.1016/j.bbrc.2011.02.024 · 2.28 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Proteoglycans consist of a protein core, with one or more glycosaminoglycan chains (i.e., chondroitin sulfate, dermatan sulfate and heparin sulfate) bound covalently to it. The glycosaminoglycan chains account for many of the functions and properties of proteoglycans. The development of proteoglycan glycotechnology to exploit the functionality of glycosaminoglycan chains is an extremely important aspect of glycobiology. Here we describe an efficient and widely applicable method for chemoenzymatic synthesis of conjugate compounds comprising intact long chondroitin sulfate (ChS) chains. An alkyne containing ChS was prepared by an enzymatic transfer reaction and linked with a chemically synthesized core compound containing an azido group using click chemistry. This method enabled highly efficient introduction of ChS into target materials. Furthermore, the ChS-introduced compounds had marked stability against proteolysis, and the chemically linked ChS chain contributed to the stability of these core compounds. We believe the present method will contribute to the development of proteoglycan glycobiology and technology.
    Glycoconjugate Journal 08/2009; 27(1):189-98. DOI:10.1007/s10719-009-9252-y · 1.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: When the products of hyaluronan (HA) digested by bovine testicular hyaluronidase (BTH) were analyzed by high-performance liquid chromatography (HPLC), minor peaks were detected just before the main even-numbered oligosaccharide peaks. The amount of each minor peak was dependent on the reaction conditions for transglycosylation, rather than hydrolysis, by the BTH. Mainly based on HPLC and MS analysis, each minor peak was found to correspond to its oligosaccharide with one N-acetyl group removed from the reducing terminal N-acetylglucosamine. Enzymatic studies showed that the N-deacetylation activity was closely related to reaction temperature, pH, and the concentration of NaCl contained in the buffer, and glycosaminoglycan types and chain lengths of substrates. These findings strongly suggest that the N-deacetylation reaction in minor peaks was due to a novel enzyme contaminant in the BTH, N-deacetylase, that carries out N-deacetylation at the reducing terminal N-acetylglucosamine of oligosaccharides and is dependent on HA hydrolysis by BTH.
    Glycoconjugate Journal 12/2008; 26(5):559-66. DOI:10.1007/s10719-008-9200-2 · 1.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Infection with Plasmodium falciparum during pregnancy results in the adherence of infected red blood cells (IRBCs) in placenta, causing pregnancy-associated malaria with severe health complications in mothers and fetuses. The chondroitin 4-sulfate (C4S) chains of very low sulfated chondroitin sulfate proteoglycans (CSPGs) in placenta mediate the IRBC adherence. While it is known that partially sulfated but not fully sulfated C4S effectively binds IRBCs, structural interactions involved remain unclear and are incompletely understood. In this study, structurally defined C4S oligosaccharides of varying sulfate contents and sizes were evaluated for their ability to inhibit the binding of IRBCs from different P. falciparum strains to CSPG purified from placenta. The results clearly show that, with all parasite strains studied, dodecasaccharide is the minimal chain length required for the efficient adherence of IRBCs to CSPG and two 4-sulfated disaccharides within this minimal structural motif are sufficient for maximal binding. Together, these data demonstrate for the first time that the C4S structural requirement for IRBC adherence is parasite strain-independent. We also show that the carboxyl group on nonreducing end glucuronic acid in dodecasaccharide motif is important for IRBC binding. Thus, in oligosaccharides containing terminal 4,5-unsaturated glucuronic acid, the nonreducing end disaccharide moiety does not interact with IRBCs due to the altered spatial orientation of carboxyl group. In such C4S oligosaccharides, 14-mer but not 12-mer constitutes the minimal motif for inhibition of IRBC binding to placental CSPG. These data have important implications for the development and evaluation of therapeutics and vaccine for placental malaria.
    Biochemistry 12/2008; 47(47):12635-43. DOI:10.1021/bi801643m · 3.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: As a possible approach to the treatment of thrombopocytopenia, the ex vivo expansion of megakaryocytic progenitor cells may be a useful tool to accelerate platelet recovery in vivo. Our objective was to assess the promoting effect of proteoglycans in a serum-free culture condition using human cord blood CD34(+) cells. Highly purified proteoglycan (PG) extracted from the nasal cartilage of salmon heads and the nasal septum cartilage of a whale were applied to the ex vivo expansion of megakaryocytopoiesis and thrombopoiesis from placental and umbilical cord blood CD34(+) cells in serum-free cultures stimulated with a combination of thrombopoietin (TPO) and interleukin-3 (IL-3). Each PG (0.5 and 5 mug) was applied to the culture with three different concentrations of TPO (50, 5 and 0.5 ng/ml) and IL-3 (100, 10 and 1 ng/ml). Both of the PGs showed no promoting effects on the mononuclear cell proliferation rate in any of the cultures. However, the whale-PG promoted the generation of megakaryocytic progenitor cells and megakaryocytes in the culture with a lower dose of cytokines, respectively. In addition, whale-PG led to a significant increase in CD42a(+) particles which seemed to be platelets. While the salmon-PG failed to promote such production in almost all of the cultures. Although whale-PG is an attractive molecule for the ex vivo expansion of human megakaryocytopoiesis, its action may depend on the glycosaminoglycans sulfation pattern and the ability of the binding affinity and the kinetics to interact with the cytokines and hematopoietic stem/progenitor cells.
    Life Sciences 06/2008; 82(19-20):1023-31. DOI:10.1016/j.lfs.2008.03.001 · 2.30 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Proteoglycans (PG) are macromolecules composed of glycosaminoglycan chains covalently attached to a protein core. In this study, we examined the effects of PG on dextran sulfate sodium (DSS)-induced experimental colitis in rats. First, to examine whether PG may ameliorate acute established DSS colitis, PG was administered orally for 5 days to the model animals. We evaluated the effects of PG on the basis of clinical symptoms, hematological analysis, macroscopic observation, and microscopic examination. We then examined whether PG administered orally to rats was detectable in their colonic lumen. After administration of PG, the colonic contents were collected, and the molecular weight of PG in the sample was analyzed by gel filtration high-performance liquid chromatography. Furthermore, we examined whether orally administered PG affected the concentrations of short-chain fatty acids (SCFAs) in the colonic feces. Orally administered PG ameliorated the clinical symptoms of bloody stools and diarrhea, and attenuated the increase in the white blood cell count in rats with established DSS colitis. Histologically, orally administered PG reduced the degree of mucosal erosion and inflammatory cell infiltration into the erosive area induced by DSS. Orally administered PG was detected in rat colon, although its molecular weight was slightly decreased. Orally administered PG significantly increased the concentration of total SCFAs and n-butyrate in rat colonic feces. This is the first study to indicate that exogenous PG ameliorates experimental colitis, suggesting the potential usefulness of PG for clinical treatment of colitis.
    Digestive Diseases and Sciences 06/2008; 53(12):3176-83. DOI:10.1007/s10620-008-0304-0 · 2.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hyaluronan controls keratinocyte proliferation and regeneration. We examined effect of UV on the expression of hyaluronan synthases (HASs) and hyaluronidases in cultured normal human newborn foreskin epidermal keratinocytes, NHEK(F). HAS3 mRNA was expressed predominantly and HAS2 mRNA expressed in lesser amounts and both were up-regulated after a single irradiation with moderate UVB but hyaluronidases was unchanged. Increased accumulation of hyaluronan in the culture medium mirrored the UVB-induced increase in the mRNA levels of HAS3 and HAS2. Unexpectedly, hyaluronan derived from UVB-irradiated and non-irradiated cells had identical size distribution. Increased expression of KGF and IL-1beta was detected just prior to the increase of HAS3 and HAS2 mRNAs after UVB irradiation. Antibody-neutralization study revealed that KGF and/or IL-1beta were at least involved in the up-regulation of HAS3 and HAS2 expressions. UVB-irradiated cells may enhance hyaluronan production to maintain homeostasis through up-regulation of HAS3 and HAS2 genes via cytokine response mechanism.
    Archives of Biochemistry and Biophysics 04/2008; 471(1):85-93. DOI:10.1016/ · 3.04 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hyaluronate plays an important role in the regulation of cervical function during parturition. In our previous study we showed that 4-methylumbelliferone (MU) suppresses hyaluronate synthesis by cultured human skin fibroblasts. The present study investigated the effects of MU on fibroblasts obtained from the human uterine cervix and assessed the possibility of controlling cervical ripening with MU. Human uterine cervical fibroblasts were collected from uterine cervices obtained from the uteri of three patients who had a total hysterectomy for uterine myoma at Hirosaki University Hospital. The fibroblasts were cultured in Dulbecco's modified Eagle's medium until confluence. They were then cultured in medium containing [3H]glucosamine (0.074 MBq/mL) with various MU doses. Hyaluronate synthesis was evaluated by assessing the incorporation of [3H]glucosamine into the soluble fraction of hyaluronate. Three independent studies were carried out on each specimen to clarify whether MU causes compositional changes or promotes hyaluronate degradation, whether the inhibitory effects of MU on hyaluronate synthesis are dose-dependent, and whether the effects of MU are reversible. MU added to the medium of the cultured cells reduced the synthesis of hyaluronate in a dose-dependent manner. After MU was removed from the medium, hyaluronate synthesis recommenced, and the amount of [3H]hyaluronate synthesized was similar to the control level. MU inhibits the synthesis of hyaluronate in human uterine cervical fibroblasts.
    Journal of Obstetrics and Gynaecology Research 01/2008; 33(6):772-6. DOI:10.1111/j.1447-0756.2007.00654.x · 0.93 Impact Factor
  • Ikuko Kakizaki, Keiichi Takagaki
    [Show abstract] [Hide abstract]
    ABSTRACT: Currently established biotechnologies are mainly based on genetic engineering and protein engineering, and they provide a number of valuable recombinant proteins. These technologies have brought benefits to medicine by enabling the production of various drugs. However, genetically produced recombinant proteins often lack entirely or partially their native sugar chains or have sugar chains that are different from the original sugar chains, thus being apt to exert insufficient specific bioactivities or to be unstable. The cause of this lack of sugar chains of recombinant proteins is that, DNA contains genetic information only on amino acid sequences but not on the biosynthesis of sugar chains that link to proteins. This problem could be solved by technologies to attach sugar chains to sugar chain-deficient recombinant protein. Moreover, attaching artificially synthesized bioactive sugar chains to protein would make it possible to create glycoproteins with additional biological activity. We focused on the transglycosylation activity of endoglycosidases acting on proteoglycan and developed methods for the reconstruction of their sugar chains, glycosaminoglycan (GAG), and for attachment of GAGs to protein.
    12/2007: pages 173-176;
  • Ikuo Kashiwakura, Kenji Takahashi, Keiichi Takagaki
    [Show abstract] [Hide abstract]
    ABSTRACT: Highly purified proteoglycan (PG) extracted from the nasal cartilage of salmon heads was applied to the ex vivo expansion of hematopoietic progenitor cells prepared from human umbilical cord blood in serum-free cultures supplemented with the combination of early-acting cytokines, thrombopoietin (TPO), interleukin-3 (IL-3) and stem cell factor (SCF). PG showed no promoting effects on the cell proliferation rate; however, they promoted the generation of progenitor cells for granulocyte-macrophages, erythrocytes and/or megakaryocytes in culture with TPO alone or SCF plus TPO. However, no promoting effect was observed in a combination of IL-3 plus SCF, which showed the highest cell proliferation rate. PG failed to promote the generation of mixed colony-forming units (i.e. the relatively immature cells in hematopoiesis). These results suggest that PG acts on the relatively mature stem/progenitor cells, and may function as a regulatory factor in the differentiation pathway of hematopoiesis.
    Glycoconjugate Journal 08/2007; 24(4-5):251-8. DOI:10.1007/s10719-007-9033-4 · 1.95 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Five isomers with different electric charge were fractionated from human urinary trypsin inhibitor (UTI) by anion exchange HPLC. Intact low-sulfated chondroitin 4-sulfate chains from the isomers were analyzed by HPLC and mass spectrometry. Unsaturated disaccharide composition analysis of the chondroitin sulfate chain revealed that the five isomers differ in the numbers of 4-sulfated disaccharide units. Intriguingly, we detected the presence of multiple novel isomers with different numbers of non-sulfated disaccharide units even in the same charge isomer fraction. Our results demonstrate that UTI can vary in terms of both the degree of sulfation and the length of the low-sulfated chondroitin 4-sulfate chain.
    Biochimica et Biophysica Acta 03/2007; 1770(2):171-7. DOI:10.1016/j.bbagen.2006.09.026 · 4.66 Impact Factor
  • Source
    Hiroshi Sashinami, Keiichi Takagaki, Akio Nakane
    [Show abstract] [Hide abstract]
    ABSTRACT: Proteoglycans (PGs) are complex glycohydrates, which are composed of core proteins and glycosaminoglycans and widely distributed in connective tissues and on the cell surface of mammalian tissues. We investigated the effect of PG extracted from salmon cartilage on cytokine responses to stimulation with heat-killed Escherichia coli (HKEC) in a mouse macrophage cell line, RAW264.7. PG exhibited the suppression of tumor necrosis factor-alpha production compared with chondroitin 4 sulfate (C4S) and chondroitin 6 sulfate (C6S). PG also revealed the up-regulation of interleukin-10 production. HKEC-induced Toll-like receptor 4 (TLR4) and inducible nitric oxide synthase expression was dose-dependently suppressed by treatment with PG, C4S or C6S, and the PG showed the strongest suppressive effect among 3 compounds. Only PG dramatically up-regulated the expression of signal transducer and activator of transcription 3 (STAT3), and the phosphorylation of STAT3 in mouse macrophages. Our results suggested that the novel interaction might exist between the extracellular matrix and immune system.
    Biochemical and Biophysical Research Communications 01/2007; 351(4):1005-10. DOI:10.1016/j.bbrc.2006.10.146 · 2.28 Impact Factor
  • British Journal of Dermatology 10/2006; 155(3):624-6. DOI:10.1111/j.1365-2133.2006.07358.x · 4.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Efficient constructions of two types of neo-proteoglycan are described. Enzymatically prepared alkyne containing chondroitin 6-sulfate chains and chemically synthesized azido group having compounds are linked by utilizing the copper(I) catalyzed 1,3-dipolar cycloaddition.
    Tetrahedron Letters 10/2006; 47(42):7455-7458. DOI:10.1016/j.tetlet.2006.08.041 · 2.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The structure of 4-methylumbelliferone (MU) consists of coumarin with 4-methyl group and 7-hydroxy group. MU inhibits HA synthesis and pericellular HA matrix formation. In this study, we used 10 MU derivatives which have hydroxy groups and methyl groups at various positions of coumarin to investigate a more effective HA inhibitor than MU. First, human pancreatic cancer cell (KP1-NL) growth assay was analyzed by Alamar Blue to determine the non-toxic concentration of MU derivatives, and the inhibitory effect on HA synthesis in the cell cultures was analyzed by HA measuring kit. Next, cell surfaces of cancer cells were analyzed by particle-exclusion assay. In conclusion, both hydroxy and methyl groups are necessary for HA inhibition by MU, and two hydroxy groups inhibited HA synthesis more strongly than MU.
    Biochemical and Biophysical Research Communications 08/2006; 345(4):1454-9. DOI:10.1016/j.bbrc.2006.05.037 · 2.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The extracellular matrix plays an essential role in normal hematopoiesis. Proteoglycans and glycosaminoglycans (GAG) are major components of the matrix. In this study, the effects of various GAG on the proliferation and differentiation of CD34+ megakaryocytic progenitor cells (CFU-Meg) were evaluated in vitro. CD34+ cells were highly purified from steady-state human peripheral blood. The GAG tested were hyaluronic acid (from humans, pigs and roosters), keratan sulfate, heparan sulfate, chondroitin sulfate (from whale, shark or squid cartilage) and dermatan sulfate (DS). When used alone, none of the GAG supported the clonal growth of CFU-Meg; however, in cultures stimulated by recombinant human thrombopoietin, human hyaluronic acid, whale chondroitin sulfate and DS significantly enhanced such growth. In particular, the addition of DS resulted in increases of about 1.3-fold, 1.6-fold and 2.0-fold in the numbers of total cells, megakaryocytes and CFU-Meg, respectively, compared with the control culture stimulated by thrombopoietin alone after 9-12 days of serum-free liquid culture. Furthermore, DS induced the generation of hyperploid megakaryocytes and promoted pro-platelet formation. Chemical fragmentation and desulfation of DS showed that a chain of at least 12 saccharides is required for colony-promoting activity and that the sulfate groups play an essential role. DS acts on an immature population of CD34+ cells, stimulates the proliferation of CFU-Meg, and enhances the terminal maturation of megakaryocytes and thrombopoiesis. These results suggest that DS has a wide spectrum of action in promoting megakaryocytopoiesis and thrombopoiesis.
    Haematologica 05/2006; 91(4):445-51. · 5.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hyaluronan (HA) is a ubiquitous, major component of the pericellular matrix and is necessary for various physiological processes. It plays a very important role in biological barriers. We previously reported that 4-methylumbelliferone (MU) inhibits HA synthesis and pericellular HA matrix formation in cultured human skin fibroblasts, Streptococcus equi FM100, and B16F10 melanoma cells. We hypothesized that MU-mediated inhibition of HA synthesis and pericellular HA matrix formation would increase the efficacy of anticancer drugs. We have already demonstrated in vitro, using a sandwich binding protein assay and a particle exclusion assay, that MU inhibits HA synthesis and formation of the pericellular HA matrix, respectively, in human KP1-NL pancreatic cancer cells. AlamarBlue assay revealed that the anticancer effect of gemcitabine in KP1-NL cells was increased by pretreatment with MU. In vivo simultaneous administration of MU and gemcitabine to tumor-bearing mice with severe combined immunodeficiency disease (SCID) decreased the size of the primary and metastatic tumors more than did gemcitabine alone. These data strongly suggest that a combination of MU and gemcitabine is effective against human pancreatic cancer cells. MU may have potential as a chemosensitizer and may provide us with a new anticancer strategy.
    Cancer Chemotherapy and Pharmacology 02/2006; 57(2):165-70. DOI:10.1007/s00280-005-0016-5 · 2.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background Type VII collagen is the major component of anchoring fibrils, which stabilize the attachment of the basement membrane zone to the dermis. Expression of type VII collagen in epidermal keratinocytes and formation of anchoring fibrils in the basement membrane zone are reduced in photoaged skin, suggesting their involvement in the pathophysiology of photoaging.Objective To investigate the effects of ultraviolet A radiation (UVA) and UVA-inducible cytokines, tumor necrosis factor (TNF)-α and interleukin (IL)-1β on type VII collagen gene (COL7A1) transcription in epidermal keratinocytes.Methods Cultured epidermal and HaCaT keratinocytes were transiently/stably transfected with plasmid constructs containing sequential 5′-end deletions of the COL7A1 promoter, linked to luciferase or the GFP gene. Twenty-four hours after treatment with either UVA, TNF-α or IL-1β, luciferase activity and GFP expression of TNF-α and IL-1β were detected by luminometer or fluorescence microscopy, respectively.ResultsUVA, TNF-α and IL-1β all decreased COL7A1 promoter activity in cultured epidermal keratinocytes as well as GFP expression in HaCaT keratinocytes. Deletion analysis revealed that the UVA- and cytokine-responsive region of COL7A1 lies between nucleotides −524 and −22.ConclusionUVA, TNF-α and IL-1β inhibit COL7A1 expression at the transcriptional level by acting on nucleotides −524 to −22 of the promoter region. These results suggest that UVA-induced downregulation of COL7A1 transcription in epidermal keratinocytes diminishes anchoring fibrils formation, resulting in skin fragility. Additional external factors including physical forces and UVB radiation in the sun-exposed areas may further promote deep wrinkle formation.
    Journal of Dermatological Science Supplement 12/2005; 1(2). DOI:10.1016/j.descs.2005.06.004
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 4-Methylumbelliferone (MU) inhibits the cell surface hyaluronan (HA) formation, and that such inhibition results in suppression of adhesion and locomotion of cultured melanoma cells. Here, we examine the effect of MU on melanoma cell metastasis in vivo. MU-treated melanoma cells showed both decreased cell surface HA formation and suppression of liver metastasis after injection into the mice. Oral administration of MU to mice decreased tissue HA content. These HA knock-down mice displayed suppressed liver metastasis. Thus, both cell surface HA of melanoma cells and recipient liver HA can promote liver metastasis, indicating that MU has potential as an anti-metastatic agent.
    FEBS Letters 06/2005; 579(12):2722-6. DOI:10.1016/j.febslet.2005.03.079 · 3.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Previous studies have shown that pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta up-regulate type VII collagen gene (COL7A1) expression in cultured dermal fibroblasts. The present study was designed to investigate the effects of TNF-alpha and IL-1beta on COL7A1 expression in epidermal keratinocytes. We demonstrated that both TNF-alpha and IL-1beta reduced COL7A1 expression in epidermal keratinocytes in an additive manner, whereas they increased COL7A1 expression in dermal fibroblasts. Thus, regulation of COL7A1 by pro-inflammatory cytokines is cell type specific. In particular, the inhibitory effects of TNF-alpha and IL-1beta occurred, at least in part, at the transcriptional level. Finally, we demonstrated that TNF-alpha and IL-1beta enhanced the TGF-beta-mediated up-regulation of COL7A1 expression in HaCaT keratinocytes, suggesting that the combination of TGF-beta and TNF-alpha or IL-1beta induces a signaling pathway that is completely different from that induced by either pro-inflammatory cytokine alone.
    Experimental Dermatology 05/2005; 14(4):289-94. DOI:10.1111/j.0906-6705.2005.00316.x · 4.12 Impact Factor

Publication Stats

1k Citations
285.40 Total Impact Points


  • 1985–2008
    • Hirosaki University
      • • Department of Biochemistry and Genome Biology
      • • School of Medicine
      • • Department of Science Radiological Technology
      Khirosaki, Aomori, Japan
  • 2006
    • Aomori Prefectural Central Hospital
      Aomori, Aomori Prefecture, Japan
  • 2000
    • Northwestern University
      Evanston, Illinois, United States