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Yukiko Yoshida

Publications and source records attributed to Yukiko Yoshida.

At least 19 recordsLinked to original sources
PubMed2007

A neural-specific F-box protein Fbs1 functions as a chaperone suppressing glycoprotein aggregation.

Fbs1 is an F-box protein present abundantly in the nervous system. Similar to the ubiquitously expressed Fbs2, Fbs1 recognizes N-glycans at the innermost position as a signal for unfolded glycoproteins, probably in the endoplasmic reticulum-associated degradation pathway. Here, we show that the in vivo majority of Fbs1 is present as Fbs1-Skp1 heterodimers or Fbs1 monomers but not SCF(Fbs1) complex. The inefficient SCF complex formation of Fbs1 and the restricted presence of SCF(Fbs1) bound on the endoplasmic reticulum membrane were due to the short linker sequence between the F-box domain and the sugar-binding domain. In vitro, Fbs1 prevented the aggregation of the glycoprotein through the N-terminal unique sequence of Fbs1. Our results suggest that Fbs1 assists clearance of aberrant glycoproteins in neuronal cells by suppressing aggregates formation, independent of ubiquitin ligase activity, and thus functions as a unique chaperone for those proteins.

Animals↗
PubMed2006

Prediction of preservative sensitization potential using surface marker CD86 and/or CD54 expression on human cell line, THP-1.

Preservatives are important components in many products, but have a history of purported allergy. Several assays [e.g., guinea pig maximization test (GPMT), local lymph node assay (LLNA)] are used to evaluate allergy potential of preservatives. We recently developed the human Cell Line Activation Test (h-CLAT), an in vitro skin sensitization test using human THP-1 cells. This test evaluates the augmentation of CD86 and CD54 expression, which are key events in the sensitization process, as an indicator of allergy following treatment with test chemical. Earlier, we found that a sub-toxic concentration was needed for the up-regulation of surface marker expression. In this study, we further evaluate the capability of h-CLAT to predict allergy potential using eight preservatives. Cytotoxicity was determined using propidium iodide with flow cytometry analysis and five doses that produce a 95, 85, 75, 65, and 50% cell viability were selected. If a material did not have any cytotoxicity at the highest technical dose (HTD), five doses are set using serial 1.3 dilutions of the HTD. The test materials used were six known allergic preservatives (e.g., methylchloroisothiazolinone/methylisothiazolinone, formaldehyde), and two non-allergic preservatives (methylparaben and 4-hydroxybenzoic acid). All allergic preservatives augmented CD86 and/or CD54 expression, indicating h-CLAT correctly identified the allergens. No augmentation was observed with the non-allergic preservatives; also correctly identified by h-CLAT. In addition, we report two threshold concentrations that may be used to categorize skin sensitization potency like the LLNA estimated concentration that yield a three-fold stimulation (EC3) value. These corresponding values are the estimated concentration which gives a relative fluorescence intensity (RFI) = 150 for CD86 and an RFI = 200 for CD54. These data suggest that h-CLAT, using THP-1 cells, may be able to predict the allergy potential of preservatives and possibility classify the potency of an allergen.

Allergens↗
PubMed2006

Development of air conditioning technologies to reduce CO2 emissions in the commercial sector.

BACKGROUND: Architectural methods that take into account global environmental conservation generally concentrate on mitigating the heat load of buildings. Here, we evaluate the reduction of carbon dioxide (CO2) emissions that can be achieved by improving heating, ventilating, and air conditioning (HVAC) technologies. RESULTS: The Climate Change Research Hall (CCRH) of the National Institute for Environmental Studies (NIES) is used as a case study. CCRH was built in line with the "Green Government Buildings" program of the Government Buildings Department at the Ministry of Land, Infrastructure and Transport in Japan. We have assessed the technology used in this building, and found that there is a possibility to reduce energy consumption in the HVAC system by 30%. CONCLUSION: Saving energy reduces CO2 emissions in the commercial sector, although emission factors depend on the country or region. Consequently, energy savings potential may serve as a criterion in selecting HVAC technologies with respect to emission reduction targets.

Journal Article↗
PubMed2006

Phenotypic alterations and cytokine production in THP-1 cells in response to allergens.

In the induction phase of allergic contact hypersensitivity, dendritic cells (DCs), including Langerhans cells (LCs) present in epidermis, can trigger an efficient T cell response once they have matured in response to an allergen. Upon maturation, DCs have been shown to induce expression of several surface molecules and the up-regulation of cytokine production. We have previously shown that THP-1 cells, human acute monocytic leukemia cell line, can discriminate between allergens and irritants by measuring expression of surface markers, CD86 and CD54, following chemical exposure. At the same time, we have also reported that augmented expression of HLA and CD80, and production of IL-1beta were up-regulated in THP-1 cells when treated with an allergen, 2,4-dinitrochlorobenzene (DNCB). In the present study, we first evaluated whether THP-1 cells induced the phenotypic changes and the production of cytokines, which are observed in the process of DC maturation, when treated with two known allergens, DNCB and nickel sulfate (NiSO(4)), and one irritant (sodium lauryl sulfate (SLS)). Exposure to DNCB and NiSO(4) induced significant augmentation of CD40 and CD83 expression as well as CD86 and CD54. Also, TNF-alpha and IL-8 secretion were markedly induced by DNCB and NiSO(4) in a dose-dependent manner. In addition, DNCB and NiSO(4) augmented CD1a expression and production of IL-6, respectively. On the contrary, SLS did not change any of these markers. We then evaluated a series of chemicals, including six known allergens (e.g., hydroquinone (HQ)) and two non-allergens (e.g., methyl paraben (MP)), in order to investigate the potential increase of CD86, CD54, CD40, and CD83 expression on THP-1 cells, and production of TNF-alpha and IL-8. Indeed, all tested allergens, except eugenol (EU), caused significant increased changes in at least four of the analyzed six markers, while non-allergens did not induce any changes. EU significantly augmented CD86, CD54 and CD40 expression. These results revealed that the wide variety of responses to allergens in THP-1 cells may emulate allergen-induced maturation processes of DCs. It is suggested that THP-1 cells, which could develop several DC-like properties, are suitable for identifying sensitizing potential of chemicals.

Allergens↗
PubMed2006

[A case of normal-tension glaucoma with impaired eye movements in a young patient].

BACKGROUND: We report a case of normal-tension glaucoma(NTG) with impaired eye movements in a young patient. CASE: A 22-year-old man with enlarged optic disc cuppings and visual field defects was suspected to have NTG, and was found, upon examination, to have impaired eye movements. Intraocular pressure recordings, including diurnal variation, were under 21 mmHg. Gonioscopic findings were normal. Magnetic resonance image(MRI) showed no particular findings. The patient was diagnosed with NTG. Using the 123I-iodoamphetamine single photon emission computed tomography (123I-IMP SPECT), decreased cerebral blood flow was detected in the patient's occipital lobe and an electro-oculogram showed impaired eye movements during smooth pursuit. The patient's visual field defects have increased over the last two years, but, no accompanying change in his eye movements has been observed. CONCLUSION: The patient in this case has NTG with impaired eye movements and decreased cerebral blood flow suggesting that some disorder of the central nervous system may be one of the causative mechanisms of NTG.

Adult↗
PubMed2005

Expression and assay of glycoprotein-specific ubiquitin ligases.

N-linked glycosylation of proteins that takes place in the endoplasmic reticulum (ER) plays a key role in protein quality control. Misfolded proteins or unassembled protein complexes that fail to achieve their functional states in the ER are retrotranslocated into the cytosol and degraded by the ubiquitin-proteasome system in a process called ER-associated degradation (ERAD). N-linked glycoprotein-specific ubiquitin ligase complexes, SCF(Fbs1) and SCF(Fbs2), appear to participate in ERAD for selective elimination of aberrant glycoproteins in the cytosol. This chapter describes methods employed for the isolation and oligosaccharide-binding assay of Fbs proteins that are the substrate-recognition components of the SCF(Fbs) complex and the in vitro ubiquitylation assay of the SCF(Fbs) ubiquitin ligase complexes.

Animals↗
PubMed2005

Glycoprotein-specific ubiquitin ligases recognize N-glycans in unfolded substrates.

Misfolded or unassembled polypeptides in the endoplasmic reticulum (ER) are retro-translocated into the cytosol and degraded by the ubiquitin-proteasome system. We reported previously that the SCF(Fbs1,2) ubiquitin-ligase complexes that contribute to ubiquitination of glycoproteins are involved in the ER-associated degradation pathway. Here we investigated how the SCF(Fbs1,2) complexes interact with unfolded glycoproteins. The SCF(Fbs1) complex was associated with p97/VCP AAA ATPase and bound to integrin-beta1, one of the SCF(Fbs1) substrates, in the cytosol in a manner dependent on p97 ATPase activity. Both Fbs1 and Fbs2 proteins interacted with denatured glycoproteins, which were modified with not only high-mannose but also complex-type oligosaccharides, more efficiently than native proteins. Given that Fbs proteins interact with innermost chitobiose in N-glycans, we propose that Fbs proteins distinguish native from unfolded glycoproteins by sensing the exposed chitobiose structure.

Adenosine Triphosphatases↗
PubMed2004

Structural basis of sugar-recognizing ubiquitin ligase.

SCF(Fbs1) is a ubiquitin ligase that functions in the endoplasmic reticulum (ER)-associated degradation pathway. Fbs1/Fbx2, a member of the F-box proteins, recognizes high-mannose oligosaccharides. Efficient binding to an N-glycan requires di-N-acetylchitobiose (chitobiose). Here we report the crystal structures of the sugar-binding domain (SBD) of Fbs1 alone and in complex with chitobiose. The SBD is composed of a ten-stranded antiparallel beta-sandwich. The structure of the SBD-chitobiose complex includes hydrogen bonds between Fbs1 and chitobiose and insertion of the methyl group of chitobiose into a small hydrophobic pocket of Fbs1. Moreover, NMR spectroscopy has demonstrated that the amino acid residues adjoining the chitobiose-binding site interact with the outer branches of the carbohydrate moiety. Considering that the innermost chitobiose moieties in N-glycans are usually involved in intramolecular interactions with the polypeptide moieties, we propose that Fbs1 interacts with the chitobiose in unfolded N-glycoprotein, pointing the protein moiety toward E2 for ubiquitination.

Amino Acid Sequence↗
PubMed2003

Fbs2 is a new member of the E3 ubiquitin ligase family that recognizes sugar chains.

F-box proteins are substrate recognition components of Skp1-Cullin1-F-box protein-Roc1 (SCF) E3 ubiquitin-protein ligases. We reported previously that Fbs1 (F-box protein that recognizes sugar chains; equivalent to Fbx2 or NFB42) binds specifically to proteins attached with high mannose oligosaccharides and subsequently contributes to elimination of N-glycoproteins in cytosol (Yoshida, Y., Chiba, T., Tokunaga, F., Kawasaki, H., Iwai, K., Suzuki, T., Ito, Y., Matsuoka, K., Yoshida, M., Tanaka, K., and Tai, T. (2002) Nature 418, 438-442). Here we report the identification of another F-box protein that recognizes N-glycan, Fbs2 (called Fbx6b or FBG2 previously). Although the expression of Fbs1 was restricted to the adult brain and testis, the Fbs2 transcript was widely expressed. The Fbs2 protein forms an SCFFbs2 ubiquitinligase complex that targets sugar chains in N-glycoproteins for ubiquitylation. Only glycoproteins bound to concanavalin A lectin and not to wheat germ agglutinin or Ricinus communis agglutinin interacted with Fbs2 in various tissues and cell lines. Pull-down analysis using various oligosaccharides revealed that Man3-9GlcNAc2 glycans were required for efficient Fbs2 binding, whereas modifications of mannose residues by other sugars or deletion of inner GlcNAc reduced Fbs2 binding. Fbs2 interacted with N-glycans of T-cell receptor alpha-subunit (TCRalpha), a typical substrate of the endoplasmic reticulum-associated degradation (ERAD) pathway, and the forced expression of mutant Fbs2DeltaF, which lacks the F-box domain essential for forming the SCF complex, and decrease of endogenous Fbs2 by small interfering RNA led to inhibition of TCRalpha degradation in cells. Thus, Fbs2 is a novel member of F-box protein family that recognizes N-glycans and plays a role in ERAD.

Animals↗
PubMed2003

Newly designed soft prelooped cap for endoscopic mucosal resection of gastric lesions.

BACKGROUND: Endoscopic mucosal resection with a cap-fitted panendoscope is a useful, effective, and safe technique. The effectiveness and safety of a newly designed larger but softer cap was compared in this study with the conventional hard cap. The soft cap has a significantly larger diameter (18 mm) compared with that of the hard cap (16.5 mm). METHODS: Eighty-three patients who underwent mucosal resection of gastric lesions were included in analysis. The diameter, resection specimen depth, and the rate of en bloc resection were compared. The operability of the endoscope with the cap attached, patient tolerance, and safety of the procedure were analyzed. RESULTS: Mean diameter (+/- SEM) of specimens resected with the soft cap was larger: 22.1 (+/- 0.7) versus 15.8 (+/- 0.3) mm (p < 0.001). The specimen was also thicker: 1.54 (+/- 0.10) versus 1.08 (+/- 0.11) mm (p < 0.001). Use of the soft cap led to higher rate of en bloc resection: 66.7% versus 43.2% (p < 0.05). The operability of the endoscope with the larger, softer cap attached was similar to that when the hard cap was used. Both caps were equally safe. CONCLUSION: The soft cap is safe and useful for mucosal resection of larger gastric lesions. Its use increases the rate of en bloc resection.

Aged↗
PubMed2003

A novel role for N-glycans in the ERAD system.

The endoplasmic reticulum (ER) provides a quality-control system for newly synthesized secretory and membrane proteins. Any improperly folded or incompletely assembled oligomers are retained in the ER, and they are retro-translocated into the cytosol when misfolding persists, where they are destroyed by the proteasome through ubiquitylation. This disposal process is called ER-associated degradation (ERAD). Although much is known about the fate of ERAD substrates near the point of degradation, little information is available about how these proteins are recognized, retained, and targeted for translocation and ubiquitylation machinery. Recent studies indicate that N-linked oligosaccharides attached to nascent proteins function as tags for several processes of a quality-control system, such as individual steps of ER-retention, selection for ERAD substrates, and ubiquitylation. In this review, I describe recent advances in the molecular basis of the ERAD system, particularly those mediated by N-glycan recognition molecules.

Animals↗
PubMed2003

Expansion of natural killer cells in mice transgenic for IgM antibody to ganglioside GD2: demonstration of prolonged survival after challenge with syngeneic tumor cells.

IgM antibodies to gangliosides, sialic acid-containing glycosphingolipids, have been shown to mediate anti-tumor effects in cancer patients with melanoma and neuroblastoma and to correlate with survival. Mechanisms by which the antibodies induce tumor suppression, however, have not been systematically studied. To investigate this point, we produced and characterized C57BL/6 mice transgenic for IgM antibody to ganglioside GD2. The transgenic (TG) mice showed high IgM, but not IgG antibody titers against GD2 in their sera. No significant clinical symptoms were observed. When EL4 cells, syngeneic T lymphoma that express ganglioside GD2, were injected into TG mice, prolonged survival was observed. Complement-dependent cytotoxicity (CDC) of EL4 cells was mediated with TG mice sera. Neither antibody-dependent cellular cytotoxicity with their sera nor cytotoxic T lymphocyte activity to EL4 cells was shown in TG mice. Spleen lymphocytes from TG mice had increased numbers of natural killer (NK) cells, but not T cells, B cells, or macrophages compared with wild-type mice. Depletion of NK cells with anti-asialo GM1 rabbit serum reduced or abrogated the observed anti-tumor effects, suggesting that NK cells play a major role in tumor eradication or suppression. NK cell activity in TG mice was much higher than wild-type mice. Moreover, TG mice showed prolonged survival after injection with syngeneic B16 melanoma cells, which express GM3, but not GD2 or GD3. Taking these results together, our studies demonstrate that the TG mice have significant anti-tumor characteristics, probably due to CDC and NK cell expansion and activation with anti-ganglioside GD2 antibody.

Animals↗
PubMed2002

E3 ubiquitin ligase that recognizes sugar chains.

N-glycosylation of proteins in the endoplasmic reticulum (ER) has a central role in protein quality control. Here we report that N-glycan serves as a signal for degradation by the Skp1-Cullin1-Fbx2-Roc1 (SCF(Fbx2)) ubiquitin ligase complex. The F-box protein Fbx2 (ref. 4) binds specifically to proteins attached to N-linked high-mannose oligosaccharides and subsequently contributes to ubiquitination of N-glycosylated proteins. Pre-integrin beta 1 is a target of Fbx2; these two proteins interact in the cytosol after inhibition of the proteasome. In addition, expression of the mutant Fbx2 Delta F, which lacks the F-box domain that is essential for forming the SCF complex, appreciably blocks degradation of typical substrates of the ER-associated degradation pathway. Our results indicate that SCF(Fbx2) ubiquitinates N-glycosylated proteins that are translocated from the ER to the cytosol by the quality control mechanism.

Animals↗
PubMed2002

Expression of glomerular plasminogen activator inhibitor type 1 in glomerulonephritis.

Plasminogen activator inhibitor type 1 (PAI-1) and tissue plasminogen activator (tPA) are the major regulators of plasmin generation. Glomerular PAI-1/tPA balance is involved in extracellular matrix turnover, as well as fibrin deposition in glomeruli. Renal biopsy specimens were obtained from 80 patients with either primary or secondary glomerulonephritis (10 patients, minimal change nephrotic syndrome; 6 patients, focal segmental glomerulosclerosis [FSGS]; 10 patients, membranous nephropathy [MN]; 24 patients, mesangial proliferative glomerulonephritis; 15 patients, lupus nephritis; 14 patients, diabetic nephropathy; and 1 patient, membranoproliferative glomerulonephritis). We quantified glomerular PAI-1 and tPA messenger RNA (mRNA) by competitive polymerase chain reaction. We also determined PAI-1 mRNA localization by in situ hybridization. Glomerular PAI-1 mRNA levels in patients with FSGS and MN were significantly greater than those of controls. There was a sixfold increase in PAI-1-tPA mRNA ratio in patients with MN compared with the control group. In addition, glomerular PAI-1 mRNA level correlated with level of proteinuria. Conversely, there was no difference in tPA mRNA levels among types of glomerulonephritis. These results suggest that suppressed glomerular fibrinolytic and proteolytic activity may be associated with the pathogenesis of glomerulonephritis, especially in FSGS and MN.

Adolescent↗