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Yasunobu Miyake,
Kenji Toyonaga,
Daiki Mori,
Shigeru Kakuta,
Yoshihiko Hoshino,
Akiko Oyamada,
Hisakata Yamada,
Ken-Ichiro Ono,
Mikita Suyama,
Yoichiro Iwakura,
Yasunobu Yoshikai, Sho Yamasaki
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ABSTRACT: Cord factor, also called trehalose-6,6'-dimycolate (TDM), is a potent mycobacterial adjuvant. We herein report that the C-type lectin MCL (also called Clec4d) is a TDM receptor that is likely to arise from gene duplication of Mincle (also called Clec4e). Mincle is known to be an inducible receptor recognizing TDM, whereas MCL was constitutively expressed in myeloid cells. To examine the contribution of MCL in response to TDM adjuvant, we generated MCL-deficient mice. TDM promoted innate immune responses, such as granuloma formation, which was severely impaired in MCL-deficient mice. TDM-induced acquired immune responses, such as experimental autoimmune encephalomyelitis (EAE), was almost completely dependent on MCL, but not Mincle. Furthermore, by generating Clec4e(gfp) reporter mice, we found that MCL was also crucial for driving Mincle induction upon TDM stimulation. These results suggest that MCL is an FcRγ-coupled activating receptor that mediates the adjuvanticity of TDM.
Immunity 05/2013; 38(5):1050-1062. · 21.64 Impact Factor
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Tetsuaki Ishikawa,
Fumie Itoh,
Sayumi Yoshida,
Shinobu Saijo,
Tetsuhiro Matsuzawa,
Tohru Gonoi,
Takashi Saito,
Yoshio Okawa,
Nobuyuki Shibata,
Tomofumi Miyamoto, Sho Yamasaki
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ABSTRACT: Various C-type lectin receptors (CLRs), including Mincle and Dectin-2, function as pattern recognition receptors and play a central role in immunity to fungal pathogens. However, the precise structures of the CLR ligands in various pathogenic fungi have yet to be completely defined. Here we report that Malassezia, an opportunistic skin fungal pathogen, is cooperatively recognized by Mincle and Dectin-2 through distinct ligands. Solvent-based fractionation revealed that Mincle and Dectin-2 recognize lipophilic and hydrophilic components of Malassezia, respectively. Mass spectrometry and nuclear magnetic resonance (NMR) revealed glyceroglycolipid and unique mannosyl fatty acids linked to mannitol as two Mincle ligands. An O-linked mannobiose-rich glycoprotein was identified as a Malassezia ligand for Dectin-2. Cytokine production in response to the Mincle ligands and the Dectin-2 ligand was abrogated in Mincle(-/-) and Dectin-2(-/-) dendritic cells, respectively. These results demonstrate that Mincle and Dectin-2 recognize distinct ligands in Malassezia to induce host immune responses.
Cell host & microbe 04/2013; 13(4):477-88. · 13.02 Impact Factor
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ABSTRACT: Multicellular organisms have developed ways to recognize potentially life-threatening events (danger signals). Classically, danger signals have been defined as exogenous, pathogen-associated molecular patterns (PAMPs) such as bacterial cell wall components (e.g., lipopolysaccharide and peptideglycan) or viral DNA/RNA. PAMPs interact with dedicated receptors on immune cells, so-called pattern recognition receptors (PRRs) and activate immune systems. A well-known family of PRRs is the toll-like receptors (TLRs) in which each member recognizes a specific set of PAMPs. However, not only exogenous pathogens but also several endogenous molecules released from necrotic cells (damaged self) also activate immune systems. These endogenous adjuvants are called damage-associated molecular patterns (DAMPs). It has been reported that high-mobility group box 1 protein (HMGB1), uric acid, heat shock proteins (HSPs) and nucleotides act as endogenous adjuvants. DAMPs are recognized by specific receptors (danger receptors) expressed mainly on antigen-presenting cells such as dendritic cells and macrophages and induce cell maturation and the production of inflammatory cytokines by activating the NF-kB pathway. In this chapter, we will review danger signals released from necrotic cells and its recognition receptors.
Advances in experimental medicine and biology 01/2012; 738:144-52. · 1.09 Impact Factor
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Arerugī = [Allergy] 06/2011; 60(6):692-8.
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Kensuke Shibata,
Hisakata Yamada,
Tetsuya Sato,
Takashi Dejima,
Masataka Nakamura,
Tomokatsu Ikawa,
Hiromitsu Hara, Sho Yamasaki,
Ryoichiro Kageyama,
Yoichiro Iwakura,
Hiroshi Kawamoto,
Hiroyuki Toh,
Yasunobu Yoshikai
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ABSTRACT: Unlike conventional T cells, which are exported from the thymus as naive cells and acquire effector functions upon antigen encounter in the periphery, a subset of γδ T cells differentiates into effectors that produce IL-17 within the fetal thymus. We demonstrate here that intrathymic development of the naturally occurring IL-17-producing γδ T cells is independent of STAT3 and partly dependent on RORγt. Comparative gene-expression analysis identified Hes1, one of the basic helix-loop-helix proteins involved in Notch signaling, as a factor specifically expressed in IL-17-producing γδ T cells. Hes1 is critically involved in the development of IL-17-producing γδ T cells, as evidenced by their severe decrease in the thymi of Hes1-deficient fetal mice. Delta-like 4 (Dll4)-expressing stromal cells support the development of IL-17-producing γδ T cells in vitro. In addition, conditional Hes1 ablation in peripheral γδ T cells decreases their IL-17 production but not their IFN-γ production. These results reveal a unique differentiation pathway of IL-17-producing γδ T cells.
Blood 05/2011; 118(3):586-93. · 9.90 Impact Factor
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Sho Yamasaki
Seikagaku. The Journal of Japanese Biochemical Society 04/2011; 83(4):328-30. · 0.04 Impact Factor
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Koji Atarashi,
Takeshi Tanoue,
Tatsuichiro Shima,
Akemi Imaoka,
Tomomi Kuwahara,
Yoshika Momose,
Genhong Cheng, Sho Yamasaki,
Takashi Saito,
Yusuke Ohba,
Tadatsugu Taniguchi,
Kiyoshi Takeda,
Shohei Hori,
Ivaylo I Ivanov,
Yoshinori Umesaki,
Kikuji Itoh,
Kenya Honda
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ABSTRACT: CD4(+) T regulatory cells (T(regs)), which express the Foxp3 transcription factor, play a critical role in the maintenance of immune homeostasis. Here, we show that in mice, T(regs) were most abundant in the colonic mucosa. The spore-forming component of indigenous intestinal microbiota, particularly clusters IV and XIVa of the genus Clostridium, promoted T(reg) cell accumulation. Colonization of mice by a defined mix of Clostridium strains provided an environment rich in transforming growth factor-β and affected Foxp3(+) T(reg) number and function in the colon. Oral inoculation of Clostridium during the early life of conventionally reared mice resulted in resistance to colitis and systemic immunoglobulin E responses in adult mice, suggesting a new therapeutic approach to autoimmunity and allergy.
Science 01/2011; 331(6015):337-41. · 31.20 Impact Factor
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ABSTRACT: The pre-T-cell receptor (TCR) is crucial for the early T-cell development, but the ligand for pre-TCR remains unidentified. We recently proposed a model that pre-TCR complexes oligomerize spontaneously through interactions of the pre-TCRα chain. To investigate the mechanism underlying this ligand-independent signaling in vivo, we established knock-in mice that express a pre-TCRα mutant lacking charged amino acids (D(22)R(24)R(102)R(117) to A(22)A(24)A(102)A(117); 4A). CD4(+)CD8(+) thymocyte number was significantly reduced in invariant pre-TCRα (pTα(4A/4A)) mice, whereas CD4(-)CD8(-) thymocytes were unaffected. The percentages of double-negative 3 (DN3) cells and γδ T cells were increased in the pTα(4A/4A) thymus, indicating that β-selection is impaired in pTα(4A/4A) mice. Pre-TCR-mediated tyrosine phosphorylation and clonal expansion into double-positive thymocytes were also defective in the knock-in mice. Pre-TCR was expressed at higher levels on pTα(4A/4A) cell surfaces than on those of the wild type, suggesting that the charged residues in pTα are critical for autonomous engagement and subsequent internalization of pre-TCR. Pre-TCR-mediated allelic exclusion of the TCRβ gene was also inhibited in pTα(4A/4A) mice, and thereby, dual TCRβs were expressed on pTα(4A/4A) T cells. Furthermore, the TCRβ chain variable region (Vβ) repertoire of mature T cells was significantly altered in pTα(4A/4A) mice. These results suggest that charged residues of pTα are critical for β-selection, allelic exclusion, and TCRβ repertoire formation.
Proceedings of the National Academy of Sciences 10/2010; 107(46):19979-84. · 9.68 Impact Factor
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Shinobu Saijo,
Satoshi Ikeda,
Keiko Yamabe,
Shigeru Kakuta,
Harumichi Ishigame,
Aoi Akitsu,
Noriyuki Fujikado,
Toshimasa Kusaka,
Sachiko Kubo,
Soo-hyun Chung, [......],
Noriko Miura,
Yoshiyuki Adachi,
Naohito Ohno,
Kazutoshi Shibuya,
Natsuo Yamamoto,
Kazuyoshi Kawakami, Sho Yamasaki,
Takashi Saito,
Shizuo Akira,
Yoichiro Iwakura
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ABSTRACT: Dectin-2 (gene symbol Clec4n) is a C-type lectin expressed by dendritic cells (DCs) and macrophages. However, its functional roles and signaling mechanisms remain to be elucidated. Here, we generated Clec4n(-/-) mice and showed that this molecule is important for host defense against Candida albicans (C. albicans). Clec4n(-/-) DCs had virtually no fungal alpha-mannan-induced cytokine production. Dectin-2 signaling induced cytokines through an FcRgamma chain and Syk-CARD9-NF-kappaB-dependent signaling pathway without involvement of MAP kinases. The yeast form of C. albicans induced interleukin-1beta (IL-1beta) and IL-23 secretion in a Dectin-2-dependent manner. In contrast, cytokine production induced by the hyphal form was only partially dependent on this lectin. Both yeast and hyphae induced Th17 cell differentiation, in which Dectin-2, but not Dectin-1, was mainly involved. Because IL-17A-deficient mice were highly susceptible to systemic candida infection, this study suggests that Dectin-2 is important in host defense against C. albicans by inducing Th17 cell differentiation.
Immunity 05/2010; 32(5):681-91. · 21.64 Impact Factor
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ABSTRACT: Mincle (also called as Clec4e or Clecsf9) is a C-type lectin receptor expressed in activated macrophages. Recently, we have reported that Mincle transduces the activation signals through ITAM-containing adaptor protein, FcRγ and induces the secretion of inflammatory cytokines. Furthermore, we and other groups have identified that Mincle recognizes a wide variety of ligands such as damaged cells, fungus, yeast and mycobacteria. These results indicate that Mincle acts as a multi-task danger receptor for both self and nonself ligands. This review summarizes the recent discoveries about the ligands and immunological roles of Mincle.
Self/Nonself - Immune Recognition and Signaling 01/2010; 1(4):310-313.
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ABSTRACT: Tuberculosis remains a fatal disease caused by Mycobacterium tuberculosis, which contains various unique components that affect the host immune system. Trehalose-6,6'-dimycolate (TDM; also called cord factor) is a mycobacterial cell wall glycolipid that is the most studied immunostimulatory component of M. tuberculosis. Despite five decades of research on TDM, its host receptor has not been clearly identified. Here, we demonstrate that macrophage inducible C-type lectin (Mincle) is an essential receptor for TDM. Heat-killed mycobacteria activated Mincle-expressing cells, but the activity was lost upon delipidation of the bacteria; analysis of the lipid extracts identified TDM as a Mincle ligand. TDM activated macrophages to produce inflammatory cytokines and nitric oxide, which are completely suppressed in Mincle-deficient macrophages. In vivo TDM administration induced a robust elevation of inflammatory cytokines in sera and characteristic lung inflammation, such as granuloma formation. However, no TDM-induced lung granuloma was formed in Mincle-deficient mice. Whole mycobacteria were able to activate macrophages even in MyD88-deficient background, but the activation was significantly diminished in Mincle/MyD88 double-deficient macrophages. These results demonstrate that Mincle is an essential receptor for the mycobacterial glycolipid, TDM.
Journal of Experimental Medicine 12/2009; 206(13):2879-88. · 13.85 Impact Factor
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Arata Takeuchi,
Yasushi Itoh,
Akiko Takumi,
Chitose Ishihara,
Noriko Arase,
Tadashi Yokosuka,
Haruhiko Koseki, Sho Yamasaki,
Yoshimi Takai,
Jun Miyoshi,
Kazumasa Ogasawara,
Takashi Saito
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ABSTRACT: In vivo immune response is triggered in the lymph node, where lymphocytes for entry into, retention at, and migration to effector sites are dynamically regulated. The molecular mechanism underlying retention regulation is the key to elucidating in vivo regulation of immune response. In this study, we describe the function of the adhesion molecule class I-restricted T cell-associated molecule (CRTAM) in regulating CD8+ T cell retention within the lymph node and eventually effector function. We previously identified CRTAM as a receptor predominantly expressed on activated CD8+ T cells, and nectin-like molecule-2 (Necl2) as its ligand. In vivo function of CRTAM-Necl2 interaction was analyzed by generating CRTAM(-/-) mice. CRTAM(-/-) mice exhibited reduced protective immunity against viral infection and impaired autoimmune diabetes induction in vivo. Although Ag-specific CRTAM(-/-) CD8+ T cells showed normal CTL functions in vitro, their number in the draining lymph node was reduced. Because CRTAM+ T cells bound efficiently to Necl2-expressing CD8+ dendritic cells (DCs) that reside in T cell area of lymph node, CRTAM may induce retention by binding to CD8+ DCs at the late stage of activation before proliferation. The CRTAM-mediated late interaction with DCs induced retention of activated CD8+ T cells in an Ag-independent fashion, and this possibly resulted in effective CTL development in the draining lymph node.
The Journal of Immunology 10/2009; 183(7):4220-8. · 5.79 Impact Factor
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ABSTRACT: Cytotoxic T lymphocyte antigen 4 (CTLA-4) is a T cell co-stimulation receptor that delivers inhibitory signals upon activation. This inhibitory effect by CTLA-4 requires activation of small GTPase Rap-1. However, the precise mechanism underlying these negative signals remains unclear. Here, we show that CTLA-4-induced suppression of IL-2 production correlates with rapid destabilization of immunological synapse (IS) formation in murine normal T cell clones. Overexpression of Spa-1, a Rap-1-specific GTPase activating protein (GAP), abolished both Rap-1 activation and IL-2 suppression induced by CTLA-4. Although we failed to find any specific inhibition of activation of early signals upon CTLA-4 engagement, we found that CTLA-4 specifically up-regulates cell motility and suppresses prolonged accumulation of Talin at the contact area with antigen presenting cells upon antigen stimulation. These results suggest that Rap-1 is activated upon CTLA-4 ligation and mediates inhibitory signals through prevention of IS formation.
Hematology (Amsterdam, Netherlands) 07/2009; 14(3):150-8. · 1.33 Impact Factor
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ABSTRACT: The serine/threonine kinase MEKK3, also known as mitogen-activated protein kinase kinase kinase 3, is a critical activator of the transcription factor NF-kappaB in innate immunity. However, the physiological function of MEKK3 in adaptive immunity is unclear. Here we report that following TCR signaling, MEKK3 positively regulated the kinase, IkappaB kinase, leading to NF-kappaB activation. T cells lacking MEKK3 were defective in TCR-induced and cytokine-induced responses. Furthermore, T cell-specific deletion of MEKK3 resulted in reduced numbers of thymocytes and peripheral T cells. Thus, our results provide genetic evidence that MEKK3 plays a crucial role in adaptive immunity.
International Immunology 03/2009; 21(4):393-401. · 3.41 Impact Factor
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Kaori Sato,
Kawori Eizumi,
Tomohiro Fukaya,
Shigeharu Fujita,
Yumiko Sato,
Hideaki Takagi,
Mai Yamamoto,
Naohide Yamashita,
Atsushi Hijikata,
Hiroshi Kitamura,
Osamu Ohara, Sho Yamasaki,
Takashi Saito,
Katsuaki Sato
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ABSTRACT: Chronic graft-versus-host disease (cGVHD) is a limiting factor in allogeneic hematopoietic stem cell transplantation (alloHSCT) for the treatment of leukemia and other malignancies. Relative to the process that initiates and promotes cGVHD, the regulation is poorly understood. In this study, we examined the role of naturally occurring regulatory dendritic cells (DC(regs)) in murine major histocompatibility complex (MHC)-compatible and multiple minor histocompatibility antigen (miHAg)-incompatible model of cGVHD in alloHSCT. DC(regs) generated from bone marrow in vitro (BM-DC(regs)) exclusively expressed CD200 receptor 3 (CD200R3), which exerted a suppressive function in the Ag-specific CD4(+) T-cell response. CD49(+)CD200R3(+) cells showed similarities in phenotype and function to BM-DC(regs), which formally distinguishes them from other leukocytes, suggesting that they are the natural counterpart of BM-DC(regs). Treatment of the recipient mice after alloHSCT with the recipient-type CD49(+)CD200R3(+) cells as well as BM-DC(regs) protected against cGVHD, and the protection was associated with the generation of Ag-specific anergic CD4(+) T cells as well as CD4(+)CD25(+)Foxp3(+) regulatory T cells (T(regs)) from donor-derived alloreactive CD4(+)CD25(-)Foxp3(-) T cells. In addition, the depletion of CD49(+)CD200R3(+) cells before alloHSCT enhanced the progression of cGVHD. In conclusion, CD49(+)CD200R3(+) cells act as naturally occurring DC(regs) to regulate the pathogenesis of cGVHD in alloHSCT mediated through the control of the transplanted alloreactive CD4(+) T cells.
Blood 03/2009; 113(19):4780-9. · 9.90 Impact Factor
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Sho Yamasaki,
Makoto Matsumoto,
Osamu Takeuchi,
Tetsuhiro Matsuzawa,
Eri Ishikawa,
Machie Sakuma,
Hiroaki Tateno,
Jun Uno,
Jun Hirabayashi,
Yuzuru Mikami,
Kiyoshi Takeda,
Shizuo Akira,
Takashi Saito
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ABSTRACT: Mincle (also called as Clec4e and Clecsf9) is a C-type lectin receptor expressed in activated phagocytes. Recently, we have demonstrated that Mincle is an FcRgamma-associated activating receptor that senses damaged cells. To search an exogenous ligand(s), we screened pathogenic fungi using cell line expressing Mincle, FcRgamma, and NFAT-GFP reporter. We found that Mincle specifically recognizes the Malassezia species among 50 different fungal species tested. Malassezia is a pathogenic fungus that causes skin diseases, such as tinea versicolor and atopic dermatitis, and fatal sepsis. However, the specific receptor on host cells has not been identified. Mutation of the putative mannose-binding motif within C-type lectin domain of Mincle abrogated Malassezia recognition. Analyses of glycoconjugate microarray revealed that Mincle selectively binds to alpha-mannose but not mannan. Thus, Mincle may recognize specific geometry of alpha-mannosyl residues on Malassezia species and use this to distinguish them from other fungi. Malassezia activated macrophages to produce inflammatory cytokines/chemokines. To elucidate the physiological function of Mincle, Mincle-deficient mice were established. Malassezia-induced cytokine/chemokine production by macrophages from Mincle(-/-) mice was significantly impaired. In vivo inflammatory responses against Malassezia was also impaired in Mincle(-/-) mice. These results indicate that Mincle is the first specific receptor for Malassezia species to be reported and plays a crucial role in immune responses to this fungus.
Proceedings of the National Academy of Sciences 02/2009; 106(6):1897-902. · 9.68 Impact Factor
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ABSTRACT: The Fc receptor common gamma-chain (FcRgamma) is a widely expressed adaptor bearing an immunoreceptor tyrosine-based activation motif (ITAM) that transduces activation signals from various immunoreceptors. We show here that basophils lacking FcRgamma developed normally and proliferated efficiently in response to interleukin 3 (IL-3) but were very impaired in IL-3-induced production of IL-4 and in supporting T helper type 2 differentiation. Through its transmembrane portion, FcRgamma associated constitutively with the common beta-chain of the IL-3 receptor and signaled by recruiting the kinase Syk. Retrovirus-mediated complementation demonstrated the essential function of the ITAM of FcRgamma in IL-3 signal transduction. Our results identify a previously unknown mechanism whereby FcRgamma functions to 'route' selective cytokine-triggered signals into the ITAM-mediated IL-4 production pathway.
Nature Immunology 01/2009; 10(2):214-22. · 26.01 Impact Factor
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ABSTRACT: Macrophage-inducible C-type lectin (Mincle) is expressed mainly in macrophages and is induced after exposure to various stimuli and stresses. Here we show that Mincle selectively associated with the Fc receptor common gamma-chain and activated macrophages to produce inflammatory cytokines and chemokines. Mincle-expressing cells were activated in the presence of dead cells, and we identified SAP130, a component of small nuclear ribonucloprotein, as a Mincle ligand that is released from dead cells. To investigate whether Mincle is required for normal responses to cell death in vivo, we induced thymocyte death by irradiating mice and found that transient infiltration of neutrophils into the thymus could be blocked by injection of Mincle-specific antibody. Our results suggest that Mincle is a receptor that senses nonhomeostatic cell death and thereby induces the production of inflammatory cytokines to drive the infiltration of neutrophils into damaged tissue.
Nature Immunology 10/2008; 9(10):1179-88. · 26.01 Impact Factor
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ABSTRACT: We demonstrate that lck promoter-driven conditional expression of transgenic SPA-1, a Rap GTPase-activation protein, causes a profound defect of alphabeta T-cell development at the CD4/CD8 double-negative (DN) stage due to enhanced cell death without affecting gammadelta T-cell development. The effect was specific to the DN stage, because CD4 promoter-driven SPA-1 expression hardly affected T-cell development. Rap1A17, a dominant-negative Rap mutant, interfered with the generation of double-positive (DP) cells from Rag2(-/-) fetal thymocytes in vitro in the presence of anti-CD3epsilon antibody and Notch ligand. Rap GTPases were activated in a DN cell line by the expression of self-oligomerizing CD3 (CD8:CD3epsilon chimera), which substituted autonomous pre-T-cell receptor (TCR) signal, inducing CD69 expression and CD25 down-regulation. Reciprocally, expression of C3G, a Rap guanine nucleotide exchange factor, in both normal and Rag2(-/-) DN cells markedly enhanced Notch-dependent generation and expansion of DP cells without additional anti-CD3epsilon antibody, thus bypassing pre-TCR. Defective alphabeta T-cell development in the conditional SPA-1-transgenic mice was restored completely by introducing a p53(-/-) mutation. These results suggest that endogenous Rap GTPases downstream of pre-TCR play an essential role in rescuing pre-T cells from the p53-mediated checkpoint response, thus allowing Notch-mediated expansion and differentiation.
Blood 10/2008; 112(12):4565-73. · 9.90 Impact Factor
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ABSTRACT: Gads is a Grb2-like adaptor protein expressed in hematopoietic cells. We demonstrated that mast cells from Gads(-/-) mice have selective functional defects. Bone marrow-derived mast cells from Gads(-/-) mice failed to induce Ca(2+) mobilization, degranulation and cytokine production upon cross-linking of FcepsilonRI. In vivo passive cutaneous anaphylaxis was also greatly impaired in Gads(-/-) mice. In contrast, Gads was dispensable for Toll-like receptor-mediated cytokine production in mast cells. Accordingly, mast cell-dependent resistance to acute peritoneal bacterial infection is not reduced in Gads(-/-) mice in vivo. Moreover, mature T and B cell responses and antibody production upon immunization were apparently normal in Gads(-/-) mice. Thus, inhibition of Gads in vivo would suppress the IgE-mediated allergic reaction with minimum adverse effects on both innate and acquired immune responses, and Gads could be an ideal target for the control of allergic responses.
International Immunology 08/2008; 20(10):1289-97. · 3.41 Impact Factor
