Keiko Furukawa

Chubu University, Касугай, Aichi, Japan

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Publications (215)878.02 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Paranodal axo-glial junctions are important for ion channel clustering and rapid action potential propagation in myelinated nerve fibers. Paranode formation depends on the cell adhesion molecules neurofascin (NF) 155 in glia, and a Caspr and contactin heterodimer in axons. We found that antibody to ganglioside GM1 labels paranodal regions. Autoantibodies to the gangliosides GM1 and GD1a are thought to disrupt nodes of Ranvier in peripheral motor nerves and cause Guillain-Barré syndrome, an autoimmune neuropathy characterized by acute limb weakness. To elucidate ganglioside function at and near nodes of Ranvier, we examined nodes in mice lacking gangliosides including GM1 and GD1a. In both peripheral and central nervous systems, some paranodal loops failed to attach to the axolemma, and immunostaining of Caspr and NF155 was attenuated. K(+) channels at juxtaparanodes were mislocalized to paranodes, and nodal Na(+) channel clusters were broadened. Abnormal immunostaining at paranodes became more prominent with age. Moreover, the defects were more prevalent in ventral than dorsal roots, and less frequent in mutant mice lacking the b-series gangliosides but with excess GM1 and GD1a. Electrophysiological studies revealed nerve conduction slowing and reduced nodal Na(+) current in mutant peripheral motor nerves. The amounts of Caspr and NF155 in low density, detergent insoluble membrane fractions were reduced in mutant brains. These results indicate that gangliosides are lipid raft components that contribute to stability and maintenance of neuron-glia interactions at paranodes.
    Glia 06/2007; 55(7):746-57. · 5.07 Impact Factor
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    ABSTRACT: Caveolin-1 is a component of lipid rafts, and is considered to be a tumor suppressor molecule. However, the mechanisms by which caveolin-1 functions in cancer cells are not well understood. We generated caveolin-1 transfectant cells (Cav-1(+) cells) using a human melanoma cell line (SK-MEL-28) and investigated the effects of caveolin-1 overexpression on the GD3-mediated malignant properties of melanomas. Cav-1(+) cells had decreased cell growth and motility, and reduced phosphorylation levels of p130Cas and paxillin relative to controls. In floatation analysis, although GD3 was mainly localized in glycolipid-enriched microdomain (GEM)/rafts in control cells, it was dispersed from GEM/rafts in Cav-1(+) cells. Correspondingly, GD3 in Cav-1(+) cells stained uniformly throughout the membrane, whereas control cells showed partial staining of the membrane, probably at the leading edge. p130Cas and paxillin were stained in the leading edges and colocalized with GD3 in the control cells. In contrast, these molecules were diffusely stained and no definite leading edges were detected in Cav-1(+) cells. These results suggest that caveolin-1 regulates GD3-mediated malignant signals by altering GD3 distribution and leading edge formation. These results reveal one of the mechanisms by which caveolin-1 curtails the malignant properties of tumor cells.
    Cancer Science 05/2007; 98(4):512-20. · 3.48 Impact Factor
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    ABSTRACT: Although disialyl glycosphingolipids such as GD3 and GD2 have been considered to be associated with malignant tumours, whether branched-type disialyl glycosphingolipids show such an association is not well understood. We investigated the sialyltransferases responsible for the biosynthesis of DSGG (disialylgalactosylgloboside) from MSGG (monosialylgalactosylgloboside). Among six GalNAc:alpha2,6-sialyltransferases cloned to date, we focused on ST6GalNAc III, V and VI, which utilize sialylglycolipids as substrates. In vitro enzyme analyses revealed that ST6GalNAc III and VI generated DSGG from MSGG with V(max)/K(m) values of 1.91 and 4.16 respectively. Transfection of the cDNA expression vectors for these enzymes resulted in DSGG expression in a renal cancer cell line. Although both ST6GalNAc III and VI genes were expressed in normal kidney cells, the expression profiles of ST6GalNAc VI among 20 renal cancer cell lines correlated clearly with those of DSGG, suggesting that the sialyltransferase involved in the synthesis of DSGG in the kidney is ST6GalNAc-VI. ST6GalNAc-VI and DSGG were found in proximal tubule epithelial cells in normal kidney tissues, while they were downregulated in renal cancer cell lines and cancer tissues. All these findings indicated that DSGG was suppressed during the malignant transformation of the proximal tubules as a maturation arrest of glycosylation.
    Biochemical Journal 04/2007; 402(3):459-70. · 4.65 Impact Factor
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    ABSTRACT: Based on the remodeling of glycosphingolipids on the human tumor cell lines with manipulation of glycosyltransferase genes, roles of sugar moieties in tumor-associated carbohydrate antigens have been analyzed. Two main topics, that is, the roles of ganglioside GD3 in human malignant melanomas and those of GD2 in small cell lung cancer (SCLC) were reported. GD3 enhances tyrosine phosphorylation of two adaptor molecules, p130Cas and paxillin, resulting in the increased cell growth and invasion in melanoma cells. GD2 also enhances the proliferation and invasion of SCLC cells. GD2 also mediates apoptosis with anti-GD2 monoclonal antibodies (mAbs) via dephosphorylation of the focal adhesion kinase. These approaches have promoted further understanding of mechanisms by which gangliosides modulate malignant properties of human cancer, and the results obtained here propose novel targets for cancer therapy.
    Annals of the New York Academy of Sciences 12/2006; 1086:185-98. · 4.38 Impact Factor
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    ABSTRACT: Fucosyl GM1 has been reported to be specifically expressed in small cell lung cancer (SCLC) cells. However, the genetic basis for the synthesis of fucosyl GM1 has not been investigated. We analyzed the glycosyltransferases responsible for the synthesis of fucosyl GM1 in SCLC cell lines. In four SCLC cell lines expressing fucosyl GM1, both FUT1 and FUT2 mRNAs were detected, indicating that either one or both of alpha1,2-fucosyltransferases may be involved in the expression of fucosyl GM1. However, three of these four lines contained function-loss mutations in the FUT2 coding region, suggesting that FUT1 is mainly involved in the alpha1,2-fucosylation of GM1. The expression levels of the GM1 synthase gene showed no correlation with those of fucosyl GM1, whereas the co-transfection of GM1 synthase cDNA with FUT1 or FUT2 into SK-LC-17 clearly enhanced the neo-expression of fucosyl GM1, indicating its essential role. In contrast, the co-transfection of GD3 synthase cDNA reduced the expression levels of fucosyl GM1 with FUT1 or FUT2. Consequently, FUT1 seems to mainly contribute to the expression of fucosyl GM1, although both FUT1 and FUT2 are capable of generating the antigen. These results should promote the functional analysis of fucosyl GM1 leading to the development of novel therapies for SCLC.
    Glycobiology 11/2006; 16(10):916-25. · 3.54 Impact Factor
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    ABSTRACT: In order to analyze molecular mechanisms for cancer metastasis, we established a high-metastatic subline H7-Lu from a subline H7 of mouse Lewis lung cancer (P29) by repeated injection into tail veins. H7-Lu exhibited increased proliferation and invasion activity. Analysis of gene expression profiles between the parent H7 and H7-Lu revealed that several genes were down-regulated in H7-Lu. One of them, caveolin-1, was a component of lipid/rafts. After confirming the down-regulation of caveolin-1 mRNA by real-time RT-PCR and reduction of the protein by immunoblotting, respectively, H7 was transfected with siRNA for caveolin-1 to examine the role of caveolin-1 in H7-Lu. mRNA of the caveolin-1 gene was suppressed to approximately one third of the original level in H7 cells transfected with siRNA. The transfectant cells showed significantly increased cell proliferation and motility when analyzed by MTT assay and scratching wound healing assay, respectively. In the siRNA-transfectant cells, both ERK1/2 and Akt showed stronger phosphorylation than the mock-transfectant cells indicating that both of these signaling pathways were activated in caveolin-1-suppressed cells. These situations seem to reflect some aspects of the cellular changes in the high metastatic subline H7-Lu. Thus, down-regulation of caveolin-1 in a high-metastatic subline of Lewis lung cancer as defined by DNA array is really a causal factor for the increased malignant properties.
    Oncology Reports 09/2006; 16(2):289-94. · 2.30 Impact Factor
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    ABSTRACT: To analyze mechanisms for cancer metastasis, we established high metastatic sublines from mouse Lewis lung cancer (P29) by repeated injection. Sublines established from the two subclones H7 and C4 commonly exhibited increased proliferation and invasion activity and reduced expression of ganglioside GM1, although they showed different preferences in their target organs of metastasis. The high metastatic sublines secreted higher levels of activated matrix metalloprotease (MMP)-9 as well as pro-MMP-9 in the culture medium than the parent lines. Furthermore, they contained MMP-9 at the glycolipid-enriched microdomain (GEM)/rafts fractionated by the sucrose density gradient ultracentrifugation of Triton X-100 extracts, whereas the parent cells showed faint bands at the fraction. When high metastatic sublines were treated with methyl-beta-cyclodextrin, their invasion activities were dramatically suppressed, and the MMP-9 secretion was also suppressed. All these results indicated that GEM/rafts play crucial roles in the increased invasion and high metastatic potential. To clarify the implication of reduced GM1 expression, low GM1-expressing cell lines were established using an RNA interference-expression vector of the GM1 synthase. Low GM1-expressing cell lines showed increased proliferation and invasion, enrichment in the GEM/rafts, and increased secretion of MMP-9. Among adhesion molecules, only integrin beta1 was detected in GEM/rafts with stronger intensity in high metastatic lines and low GM1-expressing cells. Taken together, integrins seemed to be enriched in the GEM/rafts by reduced GM1 levels, and subsequently MMP-9 was recruited to the GEM/rafts, resulting in its efficient secretion and activation, and eventually in the increased invasion and metastatic potentials.
    Journal of Biological Chemistry 07/2006; 281(26):18145-55. · 4.65 Impact Factor
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    ABSTRACT: To examine whether globotriaosylceramide (Gb3/CD77) is a receptor for verotoxins (VTs) in vivo, sensitivity of Gb3/CD77 synthase null mutant mice to VT-2 and VT-1 was analyzed. Although wild-type mice died after administration of 0.02 microg of VT-2 or 1.0 microg of VT-1, the mutant mice showed no reaction to doses as much as 100 times that administered to wild types. Expression analysis of Gb3/CD77 in mouse tissues with antibody revealed that low, but definite, levels of Gb3/CD77 were expressed in the microvascular endothelial cells of the brain cortex and pia mater and in renal tubular capillaries. Corresponding to the Gb3/CD77 expression, tissue damage with edema, congestion, and cytopathic changes was observed, indicating that Gb3/CD77 (and its derivatives) exclusively function as a receptor for VTs in vivo. The lethal kinetics were similar regardless of lipopolysaccharide elimination in VT preparation, suggesting that basal Gb3/CD77 levels are sufficient for lethal effects of VTs.
    Journal of Biological Chemistry 05/2006; 281(15):10230-5. · 4.65 Impact Factor
  • Koichi Furukawa, Tetsuya Okuda, Keiko Furukawa
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    ABSTRACT: Glycoshingolipids are involved in a wide variety of biological events, including cell proliferation, differentiation, development, regeneration, and apoptosis in vertebrates. Expression profiles of glycolipids during the development and cell differentiation or transformation suggest that glycolipids are largely implicated in the determination of cell fates by directly transducing biosignals as receptors and/or modulating receptors' function. Despite of a number of efforts to clarify the molecular functions of glycolipids, no unambiguous results have been obtained until genetic modification of glycolipids became possible. Recent progress in the isolation of cDNAs of glycosphingolipid synthase genes has enabled us to examine roles of glycosphingolipids and strongly promoted further understanding of significances of glycosphingolipids. In particular, knock-out mice of glycosyltransferases showed quite novel aspects of glycolipid function and also redundancy among similar enzymes and glycolipid structures. Here, we summarize analytical methods with which roles of glycolipids in the development and maintenance of nervous tissues, including techniques to establish transgenic mice and gene knock-out mice, to survey fundamental behavior abnormalities, and to examine fine morphological changes lying under abnormal phenotypes of the glycolipids-modified cells and glycolipid-lacking mutant mice.
    Methods in Enzymology 02/2006; 417:37-52. · 2.00 Impact Factor
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    ABSTRACT: Biological functions of globo-series glycosphingolipids are not well understood. In this study, murine cDNAs of two glycosyltransferases responsible for the synthesis of globo-series glycolipids and mRNA expression of those genes were analyzed. Distribution of their products was also analyzed. Murine cDNAs for Gb3/CD77 synthase and Gb4 synthase predicted that both of them are type II membrane proteins with 348 and 331 amino acids, respectively. In northern blotting, Gb3/CD77 synthase gene was mainly expressed in kidney and lung but also detected in many other tissues. Gb4 synthase was expressed in brain, heart, kidney, liver, skin, and testis. In the immunohistological analysis, Gb3/CD77 was mainly expressed in the proximal tubules as revealed with coincidental expression with angiotensin-converting enzyme (ACE). In spleen, it was detected in pre-B cells in the peripheral region of the white pulp, as suggested with coincidental expression with CD10. It was also expressed on the endothelia of the alveolar capillaries in lung and on the sebaceous ducts aside of the hair follicles. Gb4 was also detected mainly on the proximal tubules in kidney and on the endothelia of the alveolar capillaries in lung as Gb3/CD77. But it was also detected on the epithelium of the bronchus, seminiferous tubules and tails of spermatozoa in testis, blood vessels of choroids plexus and endothelial cells in brain, and central and hepatoportal veins in liver. The expression patterns of two genes and their products almost corresponded with some exception. The results would provide essential information for the functional studies of globo-series glycolipids.
    Glycobiology 01/2006; 15(12):1257-67. · 3.54 Impact Factor
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    ABSTRACT: Gangliosides are a family of sialic acid-containing glycosphingolipids that are highly enriched in the mammalian nervous system. In particular, b- and c-series gangliosides, all of which contain alpha-2,8 sialic acids, have been considered to play important roles in adhesion, toxin-binding, neurite extension, cell growth and apoptosis. However, the neurobiological functions of these series of gangliosides remain largely unknown. To clarify the function of b- and c-series gangliosides in pain sensation in vivo, we generated mice in whom the gene for the alpha-2,8-sialyltransferase (GD3 synthase), which is responsible for the generation of all b-series gangliosides as well as c-series gangliosides, was disrupted. Compared to the wild-type mice, the mutant mice exhibited increased sensory responses to thermal and mechanical stimuli as measured by a hot plate test and von Frey test. In contrast, the mutant mice showed decreased responses during the late phase of the formalin test. Paw edema and Fos expression in the spinal cord after formalin injection were significantly decreased in the mutant mice compared to the wild-type mice. No significant differences in the conduction velocity of the sciatic nerve, and no apparent morphologic differences in the spinal cord and the sciatic nerve were detected between the wild-type and the mutant mice. These results suggested that b- and c-series gangliosides are critical in the development and/or maintenance of the sensory nervous system responsible for the transmission of acute pain sensation and pain modulation. Moreover, they play an important role in the development of hyperalgesia induced by inflammation.
    Pain 11/2005; 117(3):271-9. · 5.64 Impact Factor
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    ABSTRACT: We isolated human ST6GalNAc III cDNA clones. The typical cDNA clones predicted a type II membrane protein of 305 amino acids with a short cytoplasmic transmembrane domain of sixteen amino acids and a catalytic domain of 280 amino acids. A short form clone predicted a protein of 240 amino acids lacking 65 amino acids including the transmembrane portion. The alternative usage of the second exon seemed to generate these two transcripts. Both had two common regions found among sialyltransferases cloned so far, i.e. sialyl motif L and sialyl motif S. Alignments of human, mouse and rat orthologs indicated that high homologies, i.e. 85-95% identity among these species at amino acid levels. We analyzed the expression pattern and substrate specificity of the product, demonstrating a very restricted expression pattern and a high substrate specificity. Northern blotting revealed that hST6GalNAc III is expressed in kidney and brain as a single band at 3.2 kb. In enzyme assay of the long form, the transfer of sialic acid onto alpha2,3-sialylated acceptor substrates, i.e. GM1b and sialyl lactotetraosylceramide, was observed. hST6GalNAc III also showed sialyltransferase activity toward O-glycans (but not N-glycans) in fetuin.
    Journal of Biochemistry 10/2005; 138(3):237-43. · 3.07 Impact Factor
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    ABSTRACT: Anti-GD2 ganglioside antibodies could be a promising, novel therapeutic approach to the eradication of human small cell lung cancers, as anti-GD2 monoclonal antibodies (mAbs) induced apoptosis of small cell lung cancer cells in culture. In this study, we analyzed the mechanisms for the apoptosis of these cells by anti-GD2 mAbs and elucidated the mechanisms by which apoptosis signals were transduced via reduction in the phosphorylation levels of focal adhesion kinase (FAK) and the activation of a MAPK family member, p38, upon the antibody binding. Knock down of FAK resulted in apoptosis and p38 activation. The inhibition of p38 activity blocked antibody-induced apoptosis, indicating that p38 is involved in this process. Immunoprecipitation-immunoblotting analysis of immune precipitates with anti-FAK or anti-integrin antibodies using an anti-GD2 mAb revealed that GD2 could be precipitated with integrin and/or FAK. These results suggested that GD2, integrin, and FAK form a huge molecular complex across the plasma membrane. Taken together with the fact that GD2+ cells showed marked detachment from the plate during apoptosis, GD2+ small cell lung cancer cells seemed to undergo anoikis through the conformational changes of integrin molecules and subsequent FAK dephosphorylation.
    Journal of Biological Chemistry 09/2005; 280(33):29828-36. · 4.65 Impact Factor
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    ABSTRACT: Although ganglioside GD3 levels are highly elevated in malignant melanomas, the role of GD3 in melanomas' malignant properties has not been clearly shown. To investigate this problem, we genetically generated GD3-positive (GD3+) transfectant cells from a GD3-negative (GD3-) mutant line SK-MEL-28-N1 and analyzed the phenotypic changes in the transfected cells. GD3+ cells showed markedly increased cell growth and invasive characteristics. Two bands that underwent stronger tyrosine phosphorylation in GD3+ cell lines than in controls after treatment with FCS were found with molecular masses of 130 and 68 kDa. They were identified as p130Cas and paxillin by sequential immunoprecipitation. Their roles in cell growth and invasion were analyzed with a small interfering RNA (siRNA) approach. Cell growth, as analyzed by BrdUrd uptake, was strongly suppressed in GD3+ cells to near the levels of GD3- cells when treated with siRNA for p130Cas but not when treated with siRNA for paxillin. However, treatment with siRNAs of either p130Cas or paxillin resulted in the marked suppression of the invasive activity of GD3+ cells almost to the levels of control cells. These results suggested that these two molecules function as effectors of GD3-mediated signaling, leading to such malignant properties as rapid cell growth and invasion.
    Proceedings of the National Academy of Sciences 09/2005; 102(31):11041-6. · 9.81 Impact Factor
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    ABSTRACT: We assessed the response in knockout mice lacking the b-series (G(D2), G(D1b), G(T1b) and G(Q1b)) gangliosides against Clostridium botulinum (types A, B and E) and tetani toxins. We found that botulinum toxins were fully toxic, while tetanus toxin was much less toxic in the knockout mice. Combining the present results with our previous finding that tetanus toxin and botulinum types A and B toxins showed essentially no toxic activity in the knockout mice lacking both the a-series and b-series gangliosides (complex gangliosides), we concluded that the b-series gangliosides is the major essential substance for tetanus toxin, while b-series gangliosides may be not the essential substance for botulinum toxins, at the initial step during the intoxication process in mouse.
    Biochimica et Biophysica Acta 07/2005; 1741(1-2):1-3. · 4.66 Impact Factor
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    ABSTRACT: To assess the production mechanism of anti-GQ1b autoantibody in Fisher syndrome (FS). The authors conducted a prospective case-control serologic study of five antecedent infections (Campylobacter jejuni, cytomegalovirus, Epstein-Barr virus, Mycoplasma pneumoniae, and Haemophilus influenzae) in 73 patients with FS and 73 sex- and age-matched hospital controls (HCs). Serologic evidence in FS patients of C. jejuni (21%) and H. influenzae (8%) infections was present significantly more often than in the HCs. None of the five pathogens examined was found in the 49 (67%) patients with FS. Anti-GQ1b IgG antibody was detected in most FS patients infected with C. jejuni or H. influenzae. Mass spectrometry analysis identified a C. jejuni strain (CF93-6) carrying a GT1a-like lipo-oligosaccharide (LOS) that had been isolated from an FS patient. Immunization of complex ganglioside-lacking knockout mice with the GT1a-like LOS generated IgG class monoclonal antibodies (mAbs) that reacted with GQ1b and GT1a. Thin-layer chromatography with immunostaining showed that anti-GQ1b mAb bound to the C. jejuni LOS (50% of the 20 FS-related strains) more commonly than in the Guillain-Barré syndrome (GBS)-related (7% of 70) or enteritis-related (20% of 65) strains. Anti-GM1 and anti-GD1a mAbs also reacted with the LOS from some FS-related strains (both 20%), but binding frequencies were higher in the GBS-related strains (74 and 57%). The GQ1b epitope was detected in 4 (40%) of the 10 FS-related H. influenzae strains but was absent in strains from patients with GBS (n = 4) and uncomplicated respiratory infections (n = 10). C. jejuni and H. influenzae are related to Fisher syndrome (FS) development, and production of anti-GQ1b autoantibody is mediated by the GQ1b-mimicking lipo-oligosaccharides on those bacteria. The causative agents remain unclear in the majority of patients with FS.
    Neurology 06/2005; 64(9):1605-11. · 8.25 Impact Factor
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    ABSTRACT: c-H-ras is located in lipid/rafts and undergoes cholesterol dependent regulation. To analyze the regulatory effects of ganglioside GM1 on the proliferation of fibroblasts transformed with mutated ras gene, GM1 synthase cDNA was transfected into NIH3T3/H-ras cells containing mutation. In the transient expression system with EGFP-fused GM1 synthase, the ratio of BrdU-positive cells among EGFP-positive cells was compared between GM1(+) transfectant cells and control cells, indicating that the transient GM1 expression suppresses cell proliferation. Then, established transfectant cells C21 and C34 expressed definite levels of GM1, and analyzed for the cell growth with the control cells D2 and D4 expressing no GM1. GM1(+) cells showed reduced proliferation compared with controls. Phosphorylation levels of ERK1/2 after FCS treatment were examined, showing that those on the GM1(+) transfectant cells increased slowly, while those in the controls rapidly reached the plateau. Fractionation of Triton X-100 extracts with sucrose density gradient ultra-centrifugation revealed that activated H-ras proteins from controls as well as NIH3T3/H-ras were completely localized in non-GEM/raft fraction. On the other hand, some portions of activated H-ras were transferred to GEM/raft fraction, i.e., 32% in C21, and 8% in C34. Since the Ras effector Raf-1 was localized in non-GEM/raft, the growth suppression might be caused, at least partly, by the movement of activated H-ras to GEM/raft fraction.
    International Journal of Oncology 05/2005; 26(4):897-904. · 2.66 Impact Factor
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    ABSTRACT: Anti-GD1a ganglioside antibodies (Abs) are the serological hallmark of the acute motor axonal form of the post-infectious paralysis, Guillain-Barre syndrome. Development of a disease model in mice has been impeded by the weak immunogenicity of gangliosides and the apparent resistance of GD1a-containing neural membranes to anti-GD1a antibody-mediated injury. Here we used mice with altered ganglioside biosynthesis to generate such a model at motor nerve terminals. First, we bypassed immunological tolerance by immunizing GD1a-deficient, beta-1,4-N-acetylgalactosaminyl transferase knock-out mice with GD1a ganglioside-mimicking antigens from Campylobacter jejuni and generated high-titer anti-GD1a antisera and complement fixing monoclonal Abs (mAbs). Next, we exposed ex vivo nerve-muscle preparations from GD1a-overexpressing, GD3 synthase knock-out mice to the anti-GD1a mAbs in the presence of a source of complement and investigated morphological and electrophysiological damage. Dense antibody and complement deposits were observed only over presynaptic motor axons, accompanied by severe ultrastructural damage and electrophysiological blockade of motor nerve terminal function. Perisynaptic Schwann cells and postsynaptic membranes were unaffected. In contrast, normal mice were not only unresponsive to immunization with GD1a but also resistant to neural injury during anti-GD1a Ab exposure, demonstrating the central role of membrane antigen density in modulating both immune tolerance to GD1a and axonal susceptibility to anti-GD1a Abmediated injury. Identical paralyzing effects were observed when testing mouse and human anti-GD1a-positive sera. These data indicate that anti-GD1a Abs arise via molecular mimicry and are likely to be clinically relevant in injuring peripheral nerve axonal membranes containing sufficiently high levels of GD1a.
    Journal of Neuroscience 03/2005; 25(7):1620-8. · 6.91 Impact Factor
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    ABSTRACT: alpha2,8-Sialyltransferase (alpha2,8S-T, GD3 synthase) has been reported to be involved in the enhanced cell proliferation of malignant tumors. Using a cloned cDNA of alpha2,8S-T, transfectant cells were established and the effects of the gene expression on the cell phenotypes were analyzed. In contrast with PC12 cells, in which we reported marked growth enhancement based on the transfection of alpha2,8S-T, Swiss3T3 cells showed no enhancement in either cell proliferation or phosphorylation of MAP kinases after the transfection of alpha2,8S-T when treated with platelet-derived growth factor. Correspondingly, the receptor for platelet-derived growth factor also showed no increased phosphorylation upon the factor stimulation. However, in the wound-healing scratching assay, the Swiss3T3 transfectant cells demonstrated increased mobility as the PC12 transfectant cells. These results suggest that the enhancing effects of alpha2,8S-T on the proliferation and mobility are differential depending on the cell types, and ganglioside-associating molecules in the individual cell types need to be investigated.
    International Journal of Oncology 03/2005; 26(2):337-44. · 2.66 Impact Factor
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    ABSTRACT: Sialic acid-containing glycosphingolipids, gangliosides, are expressed at high levels in the nerve tissues and various tumor cells. Although a number of studies on the roles of gangliosides in the regulation of cell proliferation have been performed, the mechanisms for the regulation are not well understood. We established PC12 transfectant cells over-expressing GM1 using cloned beta1,3-galactosyltransferase (EC: cDNA, and analyzed their growth and growth signals with epidermal growth factor (EGF). Over-expression of GM1 enhanced the cell proliferation with EGF under low serum culture conditions. The phosphorylation levels of EGF receptor and downstream MAP kinases after EGF stimulation were sustained even after 60 min in the transfectant cells. In contrast with Swiss3T3 cells, in which we previously reported growth suppression with GM1 over-expression due to a dramatic change in the intracellular localization of PDGF receptor, PC12 transfectant cells with beta1,3-galactosyltransferase cDNA showed no clear changes in the intracellular localization of EGF receptor in the microdomain/raft fractionation experiments compared with the vector control cells. These results suggested that the effects of GM1 expression on the nature of microdomains and growth signals depend on the cell types and receptors analyzed.
    International Journal of Oncology 02/2005; 26(1):191-9. · 2.66 Impact Factor

Publication Stats

4k Citations
878.02 Total Impact Points


  • 2008–2014
    • Chubu University
      Касугай, Aichi, Japan
  • 1998–2012
    • Nagoya University
      • • Graduate School of Medicine
      • • Graduate School of Bio-Agricultural Sciences
      Nagoya-shi, Aichi-ken, Japan
    • Nagoya Second Red Cross Hospital
      Nagoya, Aichi, Japan
  • 2009
    • University of Glasgow
      • BHF Glasgow Cardiovascular Research Centre
      Glasgow, SCT, United Kingdom
    • Pacific Northwest Diabetes Research Institute
      Seattle, Washington, United States
  • 2005
    • National Institute of Health Sciences, Japan
      • Division of Biomedical Food Research
      Edo, Tōkyō, Japan
  • 2002
    • Leiden University Medical Centre
      • Department of Neurology
      Leiden, South Holland, Netherlands
  • 1992–2002
    • Nagasaki University
      • • Department of Pediatrics
      • • Department of Oral and Maxillofacial Surgery
      • • School of Dentistry
      • • School of Medicine
      • • Department of Periodontology
      Nagasaki-shi, Nagasaki-ken, Japan
  • 2001
    • Johns Hopkins University
      Baltimore, Maryland, United States
    • Japanese Red Cross
      Edo, Tōkyō, Japan
  • 1992–2000
    • Nagasaki University Hospital
      Nagasaki, Nagasaki, Japan
  • 1999
    • National Institute of Infectious Diseases, Tokyo
      Edo, Tōkyō, Japan
  • 1986–1998
    • Memorial Sloan-Kettering Cancer Center
      • Department of Medicine
      New York City, New York, United States
    • Aichi Cancer Center
      Ōsaka, Ōsaka, Japan
  • 1997
    • Mie University
      Tu, Mie, Japan
  • 1994
    • Kyoto University
      Kioto, Kyōto, Japan
  • 1988
    • Tokyo Metropolitan Institute of Medical Science
      Edo, Tōkyō, Japan