著者

Yoshizawa Yuichi Honda Shin-ichiro Shibuya Akira

出版者

Elsevier

雑誌

Molecular immunology (ISSN:01615890)

巻号頁・発行日

vol.57, no.2, pp.216-219, 2014-02

被引用文献数

4

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Antibody exerts various immune responses via binding to Fc receptors expressed on immune cells. Although several reports have demonstrated that IgM prevents autoantibody production, the role of IgM Fc receptors is largely unknown. To analyze the involvement of Fcα/μR (CD351), an Fc receptor for IgM and IgA expressed on B cells and follicular dendritic cells (FDCs), in IgM-mediated suppression of autoantibody production, we generated mice deficient in Fcα/μR on the background of MRL/MpJ-Faslpr/lpr (Fcamr−/−Faslpr/lpr) mice. Fcamr−/−Faslpr/lpr mice showed significantly lower titers of IgG autoantibodies against double strand (ds) DNA, histone and cardiolipin in the sera than did Fcamr+/+Faslpr/lpr mice. Moreover, Fcamr−/−Faslpr/lpr mice showed higher survival rate at the ages of 28, 32 and 40 weeks old, compared with Fcamr+/+Faslpr/lpr mice. These results suggest that Fcα/μR enhances, rather than suppresses, autoantibody production.

著者

Takagaki Kana Satoh Kazuki Honda Shin-ichiro Shibuya Akira

出版者

Elsevier

雑誌

Molecular immunology (ISSN:01615890)

巻号頁・発行日

vol.56, no.1-2, pp.23-27, 2013-11

被引用文献数

4 1

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Fcα/μR (CD351) is an Fc receptor for both IgA and IgM and forms an atypical dimer that is resistant to reduction by 2-mercaptoethanol or boiling. We previously demonstrated that the cytoplasmic portion of Fcα/μR is required for dimer formation and for its efficient cell-surface expression. However, the biochemical nature of these phenomena has not been determined. By using a BW5147 mouse cell line expressing deletion mutants of the cytoplasmic region of Fcα/μR, we found that the region spanning amino acids 504–523 was required for efficient cell-surface expression, whereas the region spanning amino acids 481–490 was required for dimmer formation. Immunoblotting analyses of transfectants simultaneously expressing Flag-tagged Fcα/μR and hemagglutinin-tagged Fcα/μR suggested that Fcα/μR does not form homodimers. Instead, our data suggest that Fcα/μR forms heterodimers with an as-yet-unknown molecule with a molecular weight of 60–70 kDa.

著者

Mukai Saki Hidaka Yoshihiko Hirota-Kawadobora Masako Matsuda Kazuyuki Fujihara Noriko Takezawa Yuka Kubota Seiko Koike Kenichi Honda Takayuki Yamauchi Kazuyoshi

出版者

Elsevier

雑誌

Molecular immunology (ISSN:01615890)

巻号頁・発行日

vol.49, no.1-2, pp.48-55, 2011-10

被引用文献数

8 1

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Mutations and polymorphisms of factor H gene (FH1) are known to be closely involved in the developmentof atypical hemolytic uremic syndrome (aHUS). Several groups have identified disease risk mutations andpolymorphisms of FH1 for the development of aHUS, and have investigated frequencies of aHUS in a numberof ethnic groups. However, such studies on Japanese populations are limited. In the present study,we analyzed FH1 in Japanese aHUS patients and healthy volunteers, and examined whether those variantsimpacted on a tendency for the development of aHUS in Japanese populations. Similar to previousstudies, we found that a high frequency of FH1 mutations, located in exon 23 of FH1, encodes short consensusrepeat 20 in C-terminal end of factor H molecule in patients with aHUS (40%), but not in healthyvolunteers. Interestingly, no significant differences in frequency of well-known disease risk polymorphismsfor aHUS were observed between healthy volunteers and aHUS patients. Our results suggestedthat although FH1 mutations relates to the development of Japanese aHUS in accordance with other ethnicstudies, other factor may be required for factor H polymorphism to be a risk factor of Japanese aHUS.

著者

Nakano Takako Tahara-Hanaoka Satoko Nakahashi Chigusa Can Ismail Totsuka Naoya Honda Shin-ichiro Shibuya Kazuko Shibuya Akira

出版者

Elsevier

雑誌

Molecular immunology (ISSN:01615890)

巻号頁・発行日

vol.45, no.1, pp.289-294, 2008-01

被引用文献数

18 19

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Neutrophils play a central role in host defenses against infectious microbial pathogens. However, molecular basis for their triggering signals has been incompletely understood. Here, we show molecular and functional characteristics of myeloid-associated immunoglobulin-like receptor (MAIR)-IV. MAIR-IV was preferentially expressed on neutrophils in the peripheral blood, bone marrow, peritoneal cavity and spleen. MAIR-IV physically associates with immunoreceptor tyrosine based activating motif (ITAM)-bearing adaptor FcRγ chain. Cross-linking MAIR-IV with anti-MAIR-IV monoclonal antibody significantly induced secretion of proinflammatory cytokines TNF-α and IL-6 from neutrophils. Thus, MAIR-IV may regulate activation of neutrophils and play an important role for innate immunity.

著者

Kurita Naoki Honda Shin-ichiro Usui Kenta Shimizu Yoshio Miyamoto Akitomo Tahara-Hanaoka Satoko Shibuya Kazuko Shibuya Akira

出版者

Elsevier

雑誌

Molecular immunology (ISSN:01615890)

巻号頁・発行日

vol.46, no.4, pp.749-753, 2009-02

被引用文献数

16 12

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Fcα/μR is expressed not only in lymphoid, but also in non-lymphoid organs, including kidney. However, molecular and functional characteristics of Fcα/μR, particularly expressed in non-lymphoid organs, have remained unclear. Here we identified an isoform of Fcα/μR in the murine kidney on the C57BL/6J background. The kidney expressed only the isoform, which was not expressed in other lymphoid and non-lymphoid organs, and this isoform binds both IgA and IgM. Immunohistochemical analyses suggested that the Fcα/μR isoform was expressed in the tubular epithelial cells, but not in the glomeruli. This was confirmed by flow cytometry analysis of isolated tubular epithelial cells and by RT-PCR analyses using the separately excised glomerular and tubular regions by the laser microdissection system. These results suggest that Fcα/μR may not be involved in IgA deposition in glomerular mesangium cells in IgA nephropathy. Rather, it may play an important role in immunity in the renal tubular regions.