Biomedical subjects

Yuko Okazaki

Publications and source records attributed to Yuko Okazaki.

6 recordsLinked to original sources

PubMed2006

Identification of citrullinated eukaryotic translation initiation factor 4G1 as novel autoantigen in rheumatoid arthritis.

Antibodies against citrullinated proteins are highly specific for rheumatoid arthritis. We previously reported that functional variants of the gene encoding peptidylarginine deiminase type 4 were closely associated with RA. The purpose of this study was to investigate the citrullinated autoantigens recognized by serum samples from patients with RA. The human chondrocyte cDNA expression library was citrullinated by PADI4 and was immunoscreened with anti-modified citrulline antibodies and sera from patients with rheumatoid arthritis. One immunoreactive cDNA clone containing a 2480-base pair insert was isolated and sequence analysis revealed that the cDNA included a part of the eukaryotic translation initiation factor 4G1. Immunoreactivity against a recombinant citrullinated eIF4G1 fragment was observed with high specificity in 50.0% of RA patients. The levels of antibodies against citrullinated eIF4G1 were correlated with those of anti-CCP antibodies. Citrullinated eIF4G1 was identified as a candidate citrullinated autoantigen in RA patients. Citrullination of eIF4G1 may thus be involved in the pathogenesis of RA.

Adult↗

PubMed2006

QSNPlite, a software system for quantitative analysis of SNPs based on capillary array SSCP analysis.

We present a newly developed software called "QSNPlite" that comprehensively interprets the data of SSCP and sequencing analyses obtained from capillary array electrophoresis systems used in the quantitative characterization of SNPs. QSNPlite assists in the genotyping of individuals with SNPs and in estimating the allele frequencies of SNPs using pooled DNA. We show that this estimation is accurate (mean absolute error, 1.4%) by comparing the results of the pooled analysis using QSNPlite with the true frequencies based on the allele counting after performing individual genotypings. The QSNPlite program runs on Windows XP and can be used to determine the allele frequencies of SNPs among a large number of individuals, such as in association studies of disease-responsible genes using the candidate gene approach.

Electrophoresis, Capillary↗

PubMed2005

Anti-citrullinated collagen type I antibody is a target of autoimmunity in rheumatoid arthritis.

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases, but its autoimmune mechanisms are not clearly understood. Recently, anti-citrullinated peptide antibodies have been specifically observed in sera of RA patients. Furthermore, we identified RA-susceptible variant in a gene encoding citrullinating enzyme, peptidylarginine deiminase type 4 (PADI4). Therefore, we hypothesized that proteins which are modified in RA synovium by PADI4 act as autoantigens. Subsequently, we obtained human collagen type I (huCI) as one of the autoantigens using a RA synoviocyte cDNA library by immunoscreening. We also investigated that the levels of anti-citrullinated huCI were significantly higher in RA patient sera than in normal control sera with high specificity (99%) and positively correlated with the levels of anti-cyclic citrullinated peptide (anti-CCP) antibodies. We concluded that huCI is a novel substrate protein of PADIs and that citrullinated huCI is a candidate autoantigen of RA.

Adult↗

PubMed2005

Protein photo-cross-linking in mammalian cells by site-specific incorporation of a photoreactive amino acid.

We report a method of photo-cross-linking proteins in mammalian cells, which is based on site-specific incorporation of a photoreactive amino acid, p-benzoyl-L-phenylalanine (pBpa), through the use of an expanded genetic code. To analyze the cell signaling interactions involving the adaptor protein Grb2, pBpa was incorporated in its Src homology 2 (SH2) domain. The human GRB2 gene with an amber codon was introduced into Chinese hamster ovary (CHO) cells, together with the genes for the Bacillus stearothermophilus suppressor tRNA(Tyr) and a pBpa-specific variant of Escherichia coli tyrosyl-tRNA synthetase (TyrRS). The Grb2 variant with pBpa in the amber position was synthesized when pBpa was included in the growth medium. Upon exposure of cells to 365-nm light, protein variants containing pBpa in the positions proximal to the ligand-binding pocket were cross-linked with the transiently expressed epidermal growth factor (EGF) receptor in the presence of an EGF stimulus. Cross-linked complexes with endogenous proteins were also detected. In vivo photo-cross-linking with pBpa incorporated in proteins will be useful for studying protein-protein interactions in mammalian cells.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Clinical characteristics of Pneumocystis carinii pneumonia in patients with connective tissue diseases.

The characteristics of Pneumocystis carinii pneumonia (PCP) in patients with connective tissue diseases (CTDs) were examined retrospectively. Nine patients were enrolled in this study. Their mean age was 57.1 years. All the patients received a high-dose steroid or immunosuppressant. The onset (mean 6.6 days) of fever, cough, breathlessness, and geographical ground-glass opacities revealed by chest computed tomography was acute. The serum beta-D: -glucan level increased with a simultaneous increase in the Krebs von den Lungen (KL)-6 or surfactant protein D level. The serum immunoglobulin G (IgG) and albumin levels and the peripheral blood lymphocyte count at the onset of PCP were low, but only the serum IgG level decreased significantly. The patients were treated with trimethoprim-sulfamethoxazole or pentamidine isetionate. Six patients died eventually: two patients of progressive respiratory failure, two probably due to a recurrence of the PCP, and two with microbial respiratory infections other than PCP. Five of the six patients required mechanical ventilation. Three patients received secondary prophylaxis and survived. In conclusion, the acute onset was characteristic of PCP in patients with CTDs. High-dose steroids, immunosuppressants, and hypogammaglobulinemia are risk factors; and respiratory failure requiring mechanical ventilation, severe secondary infections, and a lack of secondary prophylaxis are poor prognostic factors. Secondary prophylaxis is recommended for all of these patients.

Journal Article↗

PubMed2005

Effect of nuclear factor-kappaB inhibition on rheumatoid fibroblast-like synoviocytes and collagen induced arthritis.

OBJECTIVE: The nuclear factor-kB (NF-kB) signaling pathway has been implicated as a molecular target for the treatment of various inflammatory diseases, such as rheumatoid arthritis (RA). In particular, IkB kinase (IKK) is considered an important molecular target because the majority of inflammatory signaling pathways mediated by NF-kB involve IKK activation. We investigated the effect of NF-kB inhibition on rheumatoid fibroblast-like synoviocytes (FLS) and collagen induced arthritis. METHODS: We evaluated the effect of IMD-0560, an inhibitor of IKK, on rheumatoid FLS in vitro and on collagen type II induced arthritis in mice. RESULTS: IMD-0560 suppressed the nuclear translocation of NF-kB and phosphorylation of IkBa induced by tumor necrosis factor-a in FLS. In addition, this compound suppressed the production of inflammatory cytokines, including interleukin 6 (IL-6), IL-8, and monocyte chemoattractant protein-1. IMD-0560 also inhibited the proliferation of FLS without showing cellular toxicity. Finally, this compound was effective against collagen induced arthritis in mice. CONCLUSION: Based on these results, IMD-0560 could be a new therapeutic agent for RA.

Animals↗