Papers - YOKOTA Shinichi

Anti-HSP auto-antibodies enhance HSP-induced pro-inflammatory cytokine production in human monocytic cells via Toll-like receptors

S Yokota, S Minota, N Fujii

INTERNATIONAL IMMUNOLOGY ( OXFORD UNIV PRESS )  18 ( 4 ) 573 - 580  2006.04  [Refereed]

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Auto-antibodies against heat shock proteins (HSPs) are frequently found in the sera of patients with rheumatic and other autoimmune diseases. However, it is unclear whether these auto-antibodies play a role in the pathophysiology and etiology of these diseases. We found that a murine anti-HSP60 mAb enhanced the production of IL-8 and tumor necrosis factor-alpha induced by human HSP60 in the human monocytic cell lines THP-1 and U937, and human peripheral blood monocytes. Similar enhancement was observed with the combination of human HSP70 protein and a murine anti-HSP70 mAb. The enhancing effects were also observed for F(ab')(2) fragment, but not for monovalent Fab fragment. This suggests that the enhancement is due to cross-linking of HSP by the anti-HSP antibodies. The induction of IL-8 was dramatically suppressed by the transfection of a dominant-negative mutant of Toll-like receptor 4. We also found that sera from patients with rheumatic autoimmune diseases, which contained higher anti-HSP60 auto-antibody titers than sera from healthy donors, significantly enhanced the IL-8 production induced by human HSP60 in THP-1 cells. We propose that auto-antibodies against HSPs have the potential to play a pathogenic role in rheumatic autoimmune diseases by enhancing inflammatory reactions.

DOI

[Molecular epidemiology of fluoroquinolone-resistant Streptococcus pneumoniae in Japan].

Yokota S, Sato K, Yoshida S, Fujii N

Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases ( 5 )  78 ( 5 ) 428 - 434  2004.05  [Refereed]

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1999年から2003年までに,北海道内で分離したS.pneumoniae 670株を対象とし,ペニシリン結合蛋白質(PBP)遺伝子の変異およびマクロライド耐性遺伝子の有無をあわせて解析した.また,random amplified polymorphic DNA-polymerase chain reaction(RAPD-PCR)によって耐性分離株間の異同についても検討した.11株の耐性株を認め,さらに10株はtosufloxacin,sparfloxacin,gatifloxacinにも耐性を示した.耐性度の高い8株で2つの遺伝子に耐性に関与する変異,残り3株は1つの遺伝子に耐性変異を認めた.RAPD-PCRによる遺伝子解析の結果から,耐性株は,特定の株が広がっているのではなく,散発的に発生していることが示唆された

DOI PubMed CiNii

Growth arrest of epithelial cells during measles virus infection is caused by upregulation of interferon regulatory factor 1

S Yokota, T Okabayashi, N Yokosawa, N Fujii

JOURNAL OF VIROLOGY ( AMER SOC MICROBIOLOGY )  78 ( 9 ) 4591 - 4598  2004.05  [Refereed]

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Natural infection with measles virus (MeV) is initiated when the virus reaches epithelial cells in the respiratory tract, oropharynx, or conjunctivae. Human epithelial cells infected with MeV frequently show growth suppression. In this study, we investigated the possible mechanisms for this suppression. The bronchiolar epithelial cell A549 showed growth arrest in G(0)/G(1) following MeV infection or treatment with gamma interferon (IFN-gamma). IFN regulatory factor-1 (IRF-1) was upregulated during MeV infection, although A549 did not produce IFN-gamma. Cells of the cervical squamous cell line SiHa persistently infected with various strains of MeV displayed slower growth than uninfected SiHa cells, although the growth rates varied depending on the MeV strain. Transfection of antisense-oriented IRF-1 cDNA released the MeV-infected SiHa cells from growth suppression. Although these infected cells did not produce IFN-gamma and suppressed IFN-alpha/beta-induced Jak1 phosphorylation, Jak1 was constitutively phosphorylated. The growth rates negatively correlated with levels of both IRF-1 expression and constitutively phosphoryllated Jak1. These results indicate that MeV upregullates IRF-1 in a manner that is independent of IFN but dependent on the JAK/STAT pathway. This induction of IRF-1 appears to suppress cell growth, although the extent seems to vary among MeV strains.

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Herpes simplex virus type 1 suppresses the interferon signaling pathway by inhibiting phosphorylation of STATs and janus kinases during an early infection stage

S Yokota, N Yokosawa, T Kubota, T Suzutani, Yoshida, I, S Miura, K Jimbow, N Fujii

VIROLOGY ( ACADEMIC PRESS INC )  286 ( 1 ) 119 - 124  2001.07  [Refereed]

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We examined the influence on the interferon (IFN) signaling pathway of infection with herpes simplex virus type 1 (HSV-1 strain VR3. Data from reporter gene assays showed that expression of both type I and type II IFN-inducible genes was dramatically suppressed during the early stage of HSV-1 infection (2 to 3 h postinfection). During these periods, phosphorylation levels of janus kinases (JAKs) and STATs did not increase after treatment of HSV-1-infected FL cells with IFN-alpha or IFN-gamma, although cellular protein levels of the JAKs and the sTATs were not significantly changed. In contrast, the inhibitory effect of HSV-1 on phosphorylation of STAT1 was not observed in U937 cells, which show resistance to steady-state accumulation of RNA for HSV-1 immediate-early genes. The phosphorylation of STAT1 in FL cells was not inhibited by infection with a UV-inactivated virus. These results indicate that Viral gene expression or viral protein production is necessary for the inhibition of phosphorylation by HSV-1. (C) 2001 Academic Press.

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Intracellular interaction of collagen-specific stress protein HSP47 with newly synthesized procollagen

Mamoru Satoh, Kazunori Hirayoshi, Shin-Ichi Yokota, Nobuko Hosokawa, Kazuhiro Nagata

Journal of Cell Biology   133 ( 2 ) 469 - 483  1996.04  [Refereed]

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Heat shock protein 47 (HSP47), a collagen-specific stress protein, has been postulated to be a collagen-specific molecular chaperone localized in the ER. We previously demonstrated that HSP47 transiently associated with newly synthesized procollagen in the ER (Nakai, A., M. Satoh, K. Hirayoshi, and K. Nagata. 1992. J. Cell Biol. 117:903-914). In the present work, we examined the location where HSP47 binds to and dissociates from newly synthesized procollagen within the cells, and whether HSP47 associates with nascent single procollagen polypeptide chains and/or with mature triple- helix procollagen. This was accomplished by biochemical coprecipitation with anti-HSP47 and anticollagen antibodies, combined with pulse-label and chase experiments in the presence or absence of various inhibitors for protein secretion, as well as by confocal laser microscopic observation of the cells double stained with both antibodies. We further examined whether the RDEL (Arg-Asp-Glu-Leu) sequence at the COOH terminus of HSP47 can act as an ER- retention signal, as the KDEL sequence does. When the secretion of procollagen was inhibited by the presence of α, α'-dipyridyl, an iron chelator that inhibits procollagen triple-helix formation, or by the presence of brefeldin A, which inhibits protein transport between the ER and the Golgi apparatus, procollagen was found to be bound to HSP47 during the chase period in the intermediate compartment. In contrast, the dissociation of procollagen chains from HSP47 was not inhibited when procollagen secretion was inhibited by monensin or bafilomycin A1, both of which are known to be inhibitors of post-cis-Golgi transport. These findings suggest that HSP47 and procollagen dissociated between the post-ER and the cis-Golgi compartments. HSP47 was shown to bind to nascent, single-polypeptide chains of newly synthesized procollagen, as well as to the mature triple-helix form of procollagen. HSP47 with the RDEL sequence deleted was secreted out of the cells, which suggests that the RDEL sequence actually acts as an ER-retention signal, as the KDEL sequence does. This secreted HSP47 did not acquire endogycosidase H resistance. The biological significance of the interaction between HSP47 and procollagen in the central secretory pathway, as well as possible mechanisms for this pathway, will be discussed.

DOI PubMed

DIVERSITY OF CORE ANTIGEN OF PSEUDOMONAS-AERUGINOSA LIPOPOLYSACCHARIDE

S YOKOTA, H NOGUCHI

JAPANESE JOURNAL OF MEDICAL SCIENCE & BIOLOGY ( NATL INST HEALTH )  45 ( 5-6 ) 270 - 271  1992.10  [Refereed]

INHIBITORY ACTIVITY ON BACTERIAL MOTILITY AND INVIVO PROTECTIVE ACTIVITY OF HUMAN MONOCLONAL-ANTIBODIES AGAINST FLAGELLA OF PSEUDOMONAS-AERUGINOSA

H OCHI, H OHTSUKA, S YOKOTA, UEZUMI, I, M TERASHIMA, K IRIE, H NOGUCHI

INFECTION AND IMMUNITY ( AMER SOC MICROBIOLOGY )  59 ( 2 ) 550 - 554  1991.02  [Refereed]

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Three stable hybridoma cell lines, IN-2A8, IN-5D6, and ZI-3A8, that secrete human monoclonal antibodies (MAbs) specific for b-type flagella of Pseudomonas aeruginosa were established by fusing peripheral blood lymphocytes from healthy volunteers with murine myeloma P3X63-Ag8.653 cells. The immunoglobulin M MAbs reacted specifically with flagellin (M(r), 52,000) by Western blotting (immunoblotting) analysis and bound specifically to clinical isolates belonging to Homma serotypes A, B, H, I, and M at frequencies of 58, 50, 46, 30, and 35%, respectively, but did not bind to any serotype E or G isolates. Overall, the MAbs bound to 31% of the clinical isolates. MAb IN-2A8 strongly protected burned mice challenged with P. aeruginosa bearing b-type flagella from death following parenteral administration of 0.1-mu-g per mouse. This MAb also inhibited P. aeruginosa colony spreading in soft agar at a concentration of more than 1-mu-g/ml but only slightly enhanced opsonophagocytosis by human polymorphonuclear leukocytes. A line of evidence suggests that the potent in vivo activity of MAb IN-2A8 in the burned-mouse model is likely to be caused by its inhibition of bacterial motility after binding to flagella.

CHARACTERIZATION OF A POLYSACCHARIDE COMPONENT OF LIPOPOLYSACCHARIDE FROM PSEUDOMONAS-AERUGINOSA IID-1008 (ATCC-27584) AS D-RHAMNAN

S YOKOTA, S KAYA, S SAWADA, T KAWAMURA, Y ARAKI, E ITO

EUROPEAN JOURNAL OF BIOCHEMISTRY ( SPRINGER VERLAG )  167 ( 2 ) 203 - 209  1987.09  [Refereed]

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THE STRUCTURE OF THE O-SPECIFIC CHAIN OF LIPOPOLYSACCHARIDE FROM PSEUDOMONAS-AERUGINOSA IID-1008 (ATCC-27584)

S YOKOTA, S KAYA, T KAWAMURA, Y ARAKI, E ITO

JOURNAL OF BIOCHEMISTRY ( JAPANESE BIOCHEMICAL SOC )  99 ( 6 ) 1551 - 1561  1986.06  [Refereed]