記述言語：英語   出版者・発行元：PNAS Nexus  

The activation and differentiation of B cells into plasma cells (PCs) play critical roles in the immune response to infections and autoimmune diseases. Toll-like receptor 9 (TLR9) responds to bacterial and viral DNA containing unmethylated CpG motifs and triggers immune responses in B cells; however, abnormal recognition of self-DNA by TLR9 can cause autoimmune diseases. When stimulated with TLR9 agonists, follicular (FO) B cells, a subset of B cells residing in the FO regions of secondary lymphoid organs, exhibit a propensity for activation but fail to give rise to PCs. The factors that enable the transition of TLR9-activated FO B cells from activation to differentiation into PCs remain unclear. In this study, we show that type I interferon-alpha (IFNα) signaling causes FO B cells activated by CpG stimulation to differentiate into PCs. Although CpG stimulation alone only temporarily increased interferon regulatory factor 4 (IRF4) expression in FO B cells, co-stimulation with both CpG and IFNα enhanced and maintained high IRF4 expression levels, ultimately enabling the cells to differentiate into PCs. Overexpression of IRF4 in FO B cells results in CpG-induced PC transition without IFN signaling. Furthermore, co-stimulation of TLR9 and IFNα receptors significantly enhanced mammalian target of rapamycin (mTOR) signaling, which regulates IRF4 expression and PC generation. These findings suggest that IFNα may play a key role in promoting the fate of PC differentiation in FO B cells activated by TLR9 stimulation.

DOI： 10.1093/pnasnexus/pgae152

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

私たちの体をウイルスなどの外敵（抗原※1）から守るために作られる抗体はB細胞によって作られます。B細胞はリンパ組織の中に作られる胚中心と呼ばれる場所で、抗体の性能を高め、生体防御の役割を果たします。胚中心では、より良質な抗体を作ることができる胚中心B細胞が優先的に選択されて抗体産生細胞へと分化していきますが、その仕組みは長らく未解明でした。
　われわれは、より良質な胚中心B細胞が選択される際に、B細胞受容体（※4）のシグナル伝達による細胞の生存を助ける仕組みが存在することを発見しました。B細胞受容体のカルシウム刺激伝達が減弱するB細胞特異的STIM欠損マウスを用いて、B細胞受容体からのカルシウムシグナルが胚中心における良質なB細胞の選択に必要であることを証明しました。さらに、細胞の生存を助けるBcl2a1という遺伝子の発現が、B細胞受容体の刺激によって増加することが、この選択を支える分子メカニズムであることを明らかにしました。
　
従来、胚中心B細胞の選択にはB細胞受容体シグナルは重要視されてきませんでしたが、今回の発見は、胚中心B細胞の選択の新たな機序を明らかにしただけでなく、感染症に対してより効果的なワクチンの開発につながることが期待されます。

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   出版者・発行元：Circulation: Heart Failure  

BACKGROUND: Cardiac autoantibodies (cAAbs) are involved in the progression of adverse cardiac remodeling in heart failure (HF). However, our understanding of cAAbs in HF is limited owing to the absence of relevant animal models. Herein, we aimed to establish and characterize a murine model of cAAb-positive HF after myocardial infarction (MI), thereby facilitating the development of therapeutics targeting cAAbs in post-MI HF. METHODS: MI was induced in BALB/c mice. Plasma cAAbs were evaluated using modified Western blot-based methods. Prognosis, cardiac function, inflammation, and fibrosis were compared between cAAb-positive and cAAb-negative MI mice. Rapamycin was used to inhibit cAAb production. RESULTS: Common cAAbs in BALB/c MI mice targeted cTnI (cardiac troponin I). Herein, 71% (24/34) and 44% (12/27) of the male and female MI mice, respectively, were positive for cAAbs against cTnI (cTnIAAb). Germinal centers were formed in the spleens and mediastinal lymph nodes of cTnIAAb-positive MI mice. cTnIAAb-positive MI mice showed progressive cardiac remodeling with a worse prognosis (P=0.014, by log-rank test), which was accompanied by cardiac inflammation, compared with that in cTnIAAb-negative MI mice. Rapamycin treatment during the first 7 days after MI suppressed cTnIAAb production (cTnIAAb positivity, 59% [29/49] and 7% [2/28] in MI mice treated with vehicle and rapamycin, respectively; P<0.001, by Pearson χ2 test), consequently improving the survival and ameliorating cardiac inflammation, cardiac remodeling, and HF in MI mice. CONCLUSIONS: The present post-MI HF model may accelerate our understanding of cTnIAAb and support the development of therapeutics against cTnIAAbs in post-MI HF.

DOI： 10.1161/CIRCHEARTFAILURE.122.010347

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記述言語：英語   出版者・発行元：Annals of Hematology  

DOI： 10.1007/s00277-023-05391-3

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記述言語：英語   出版者・発行元：Frontiers in Immunology  

B cell anergy plays a critical role in maintaining self-tolerance by inhibiting autoreactive B cell activation to prevent autoimmune diseases. Here, we demonstrated that Fc receptor-like 5 (Fcrl5) upregulation contributes to autoimmune disease pathogenesis by disrupting B cell anergy. Fcrl5—a gene whose homologs are associated with human autoimmune diseases—is highly expressed in age/autoimmunity-associated B cells (ABCs), an autoreactive B cell subset. By generating B cell-specific Fcrl5 transgenic mice, we demonstrated that Fcrl5 overexpression in B cells caused systemic autoimmunity with age. Additionally, Fcrl5 upregulation in B cells exacerbated the systemic lupus erythematosus-like disease model. Furthermore, an increase in Fcrl5 expression broke B cell anergy and facilitated toll-like receptor signaling. Thus, Fcrl5 is a potential regulator of B cell-mediated autoimmunity by regulating B cell anergy. This study provides important insights into the role of Fcrl5 in breaking B cell anergy and its effect on the pathogenesis of autoimmune diseases.

DOI： 10.3389/fimmu.2023.1276014

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記述言語：英語   出版者・発行元：Genes to Cells  

The CARMA1–Bcl10–MALT1 (CBM) signalosome is a crucial module of NF-κB activation in B cell receptor (BCR) signaling. Biophysical studies have shown that the E3 ubiquitin ligase TRAF6 cooperatively modifies the CBM signalosome; however, the specific details regarding how TRAF6 is involved in BCR signal-induced CBM formation remain unclear. In this study, we aimed to reveal the influences of TRAF6 on CBM formation and TAK1 and IKK activities using DT40 B cells which lack all the exons of TRAF6. In TRAF6-null cells we found: (i) attenuation of TAK1 activity and abolishment of IKK activity and (ii) sustained binding of CARMA1 to Bcl10. To account for the molecular mechanism causing these dynamics, we performed a mathematical model analysis. The mathematical model analysis showed that the regulation of IKK activation by TRAF6 can reproduce TAK1 and IKK activities in TRAF6 null cells, and that the TRAF6 related signal-dependent inhibitor suppresses CARMA1 binding to Bcl10 in wild-type cells. These results suggest that TRAF6 contributes to the positive regulation of IKK activation via TAK1, alongside the negative signal-dependent regulation of CARMA1 binding to Bcl10.

DOI： 10.1111/gtc.13022

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記述言語：英語   出版者・発行元：Frontiers in Immunology  

Immune cells have been implicated in interstitial lung diseases (ILDs), although their phenotypes and effector mechanisms remain poorly understood. To better understand these cells, we conducted an exploratory mass cytometry analysis of immune cell subsets in bronchoalveolar lavage fluid (BALF) from patients with idiopathic pulmonary fibrosis (IPF), connective-tissue disease (CTD)-related ILD, and sarcoidosis, using two panels including 64 markers. Among myeloid cells, we observed the expansion of CD14+ CD36hi CD84hiCCR2– monocyte populations in IPF. These CD14+ CD36hi CD84hi CCR2– subsets were also increased in ILDs with a progressive phenotype, particularly in a case of acute exacerbation (AEx) of IPF. Analysis of B cells revealed the presence of cells at various stages of differentiation in BALF, with a higher percentage of IgG memory B cells in CTD-ILDs and a trend toward more FCRL5+ B cells. These FCRL5+ B cells were also present in the patient with AEx-IPF and sarcoidosis with advanced lung lesions. Among T cells, we found increased levels of IL-2R+ TIGIT+ LAG3+ CD4+ T cells in IPF, increased levels of CXCR3+ CD226+ CD4+ T cells in sarcoidosis, and increased levels of PD1+ TIGIT+ CD57+ CD8+ T cells in CTD-ILDs. Together, these findings underscore the diverse immunopathogenesis of ILDs.

DOI： 10.3389/fimmu.2023.1145814

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記述言語：英語   出版者・発行元：European Journal of Immunology  

DOI： 10.1002/eji.202149542

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記述言語：英語   出版者・発行元：International Immunology  

CX3CR1high myeloid cells in the small intestine mediate the induction of oral tolerance by driving regulatory T (Treg) cells. Bacterial metabolites, e.g. pyruvate and lactate, induce a dendrite extension of CX3CR1high myeloid cells into the intestinal lumen via GPR31. However, it remains unclear whether the pyruvate-GPR31 axis is involved in the induction of oral tolerance. Here, we show that pyruvate enhances oral tolerance in a GPR31-dependent manner. In ovalbumin (OVA)-fed Gpr31-deficient mice, an OVA-induced delayed-type hypersensitivity response was substantially induced, demonstrating the defective induction of oral tolerance in Gpr31-deficient mice. The percentage of RORγt+ Treg cells in the small intestine was reduced in Gpr31-deficient mice. In pyruvate-treated wild-type mice, a low dose of OVA efficiently induced oral tolerance. IL-10 production from intestinal CX3CR1high myeloid cells was increased by OVA ingestion in wild-type mice, but not in Gpr31-deficient mice. CX3CR1high myeloid cell-specific IL-10-deficient mice showed a defective induction of oral tolerance to OVA and a decreased accumulation of OVA-specific Treg cells in the small intestine. These findings demonstrate that pyruvate enhances oral tolerance through a GPR31-dependent effect on intestinal CX3CR1high myeloid cells.

DOI： 10.1093/intimm/dxac010

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1111/imr.13053.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： J Biochem .

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41598-021-84786-6.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41590-020-0700-y.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.celrep.2020.107755.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/978-981-15-3532-1_2.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The long-chain fatty acid receptor GPR40 plays an important role in potentiation of glucose-induced insulin secretion (GIIS) from pancreatic β-cells. Previous studies demonstrated that GPR40 activation enhances Ca²⁺ release from the endoplasmic reticulum (ER) by activating inositol 1,4,5-triphosphate (IP3) receptors. However, it remains unknown how ER Ca²⁺ release via the IP3 receptor is linked to GIIS potentiation. Recently, stromal interaction molecule (STIM) 1 was identified as a key regulator of store-operated Ca²⁺ entry (SOCE), but little is known about its contribution in GPR40 signaling. We show that GPR40-mediated potentiation of GIIS is abolished by knockdown of IP3 receptor 1 (IP3R1), STIM1 or Ca²⁺-channel Orai1 in insulin-secreting MIN6 cells. STIM1 and Orai1 knockdown significantly impaired SOCE and the increase of intracellular Ca²⁺ by the GPR40 agonist, fasiglifam. Furthermore, β-cell-specific STIM1 knockout mice showed impaired fasiglifam-mediated GIIS potentiation not only in isolated islets but also in vivo. These results indicate that the IP3R1/STIM1/Orai1 pathway plays an important role in GPR40-mediated SOCE initiation and GIIS potentiation in pancreatic β-cells.

DOI： 10.1038/s41598-019-52048-1

記述言語：英語   掲載種別：研究論文（学術雑誌）  

B cells represent a key cellular component of humoral immunity. Besides antigen presentation and antibody production, B cells also play a role in immune regulation and induction of tolerance through several mechanisms. Our understanding of B-lineage cells with regulatory ability has been revolutionized by the delineation of heterogeneous subsets of these cells. Specific environmental signals may further determine the polarization and function of B-lineage regulatory cells. With the availability of new genetic, molecular and pharmacological tools, considerable advances have been made toward our understanding of the surface phenotype, developmental processes and functions of these cells. These exciting discoveries, some of which are still controversial, also raise many new questions, which makes the inhibitory function of B cells a rapidly growing field in immunopathology. Here we review highlights of the regulatory activity of B cells and the recent advances in the function and phenotype of these B-cell subsets in healthy and diseased states.

DOI： 10.1093/intimm/dxz068

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Lymphocyte migration is mediated by G protein–coupled receptors (GPCRs) that respond to chemoattractive molecules. After their activation, GPCRs are phosphorylated by different GPCR kinases (GRKs), which produces distinct functional outcomes through b-arrestins. However, the molecular machinery that targets individual GRKs to activated GPCRs remains elusive. Here, we identified a protein complex consisting of copper metabolism MURR1 domain–containing (COMMD) 3 and COMMD8 (COMMD3/8 complex) as an adaptor that selectively recruits a specific GRK to chemoattractant receptors and promotes lymphocyte chemotaxis. COMMD8, whose stability depended on COMMD3, was recruited to multiple chemoattractant receptors. Deficiency of COMMD8 or COMMD3 impaired B cell migration and humoral immune responses. Using CXC-chemokine receptor 4 (CXCR4) as a model, we demonstrated that the COMMD3/8 complex selectively recruited GRK6 and induced GRK6-mediated phosphorylation of the receptor and activation of b-arrestin–mediated signaling. Thus, the COMMD3/8 complex is a specificity determinant of GRK targeting to GPCRs and represents a point of regulation for immune responses.

DOI： 10.1084/jem.20181494

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The western blotting technique is widely used to analyze protein expression levels and protein molecular weight. The chemiluminescence method is mainly used for detection due to its high sensitivity and ease of manipulation, but it is unsuitable for detailed analyses because it cannot be used to detect multiple proteins simultaneously. Recently, more attention has been paid to the fluorescence detection method because it is more quantitative and is suitable for the detection of multiple proteins simultaneously. However, fluorescence detection can be limited by poor image resolution and low detection sensitivity. Here, we describe a method to detect fluorescence in western blots using fluorescence microscopy to obtain high-resolution images. In this method, filters and fluorescent dyes are optimized to enhance detection sensitivity to a level similar to that of the chemiluminescence method.

DOI： 10.1371/journal.pone.0191532

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Stromal interaction molecule 1 (STIM1), an endo/sarcoplasmic reticulum Ca²⁺ sensor, has been shown to control a Ca²⁺-dependent signal that promotes cardiac hypertrophy. However, whether STIM1 has adaptive role that helps to protect against cardiac overload stress remains unknown. We hypothesized that STIM1 deficiency causes a maladaptive response to pressure overload stress. We investigated STIM1 heterozygous KO (STIM1^+/–) mice hearts, in which STIM1 protein levels decreased to 27% of wild-type (WT) with no compensatory increase in STIM2. Under stress-free conditions, no significant differences were observed in electrocardiographic and echocardiographic parameters or blood pressure between STIM1^+/– and WT mice. However, when STIM1^+/– mice were subjected to transverse aortic constriction (TAC), STIM1^+/– mice had a higher mortality rate than WT mice. The TAC-induced increase in the heart weight to body weight ratio (mean mg/g ± standard error of the mean) was significantly inhibited in STIM1^+/– mice (WT sham, 4.12 ± 0.14; WT TAC, 6.23 ± 0.40; STIM1^+/– sham, 4.53 ± 0.16; STIM1^+/– TAC, 4.63 ± 0.08). Reverse transcription-polymerase chain reaction analysis of the left ventricles of TAC-treated STIM1^+/– mice showed inhibited induction of cardiac fetal genes, including those encoding brain and atrial natriuretic proteins. Western blot analysis showed upregulated expression of transient receptor potential channel 1 (TRPC1) in TAC-treated WT mice, but suppressed expression in TAC-treated STIM1^+/– mice. Taken together, the hearts of STIM1 haploinsufficient mice had a superficial resemblance to the WT phenotype under stress-free conditions; however, STIM1 haploinsufficient mice showed a maladaptive response to cardiac pressure overload.

DOI： 10.1371/journal.pone.0187950

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Cancer-specific cell-surface antigens are ideal targets for monoclonal antibody (mAb)-based immunotherapy but are likely to have previously been identified in transcriptome or proteome analyses. Here, we show that the active conformer of an integrin can serve as a specific therapeutic target for multiple myeloma (MM). We screened >10,000 anti-MM mAb clones and identified MMG49 as an MM-specific mAb specifically recognizing a subset of integrin β₇7 molecules. The MMG49 epitope, in the N-terminal region of the β₇7 chain, is predicted to be inaccessible in the resting integrin conformer but exposed in the active conformation. Elevated expression and constitutive activation of integrin β₇7 conferred high MMG49 reactivity on MM cells, whereas MMG49 binding was scarcely detectable in other cell types including normal integrin β₇7 + lymphocytes. T cells transduced with MMG49-derived chimeric antigen receptor (CAR) exerted anti-MM effects without damaging normal hematopoietic cells. Thus, MMG49 CAR T cell therapy is promising for MM, and a receptor protein with a rare but physiologically relevant conformation can serve as a cancer immunotherapy target.

DOI： 10.1038/nm.4431

記述言語：英語   掲載種別：研究論文（学術雑誌）  

STIM1 is the only currently known intracellular calcium sensor that functions as the calcium influx regulator controlling immune cell activation. STIM1 function in immune cell calcium signalling has been studied extensively; however, its role in microglia, innate immune cells in brain, has not been fully understood. Here, we report that STIM1^-/- murine microglia lost store-operated calcium influx and displayed aberrant immunological functions. Microglial functions regulated by chronic and global Ca2+i changes were reduced significantly, including cytokine releases and opsonin-dependent phagocytosis. More dramatically, cellular functions governed by Ca²⁺ regulation in local microdomains at the cell periphery, such as UDP-induced phagocytosis and ATP-stimulated chemotactic migration, were severely reduced in STIM1^-/- microglia. Interestingly, UDP-induced Orai1 mobilization to the peripheral region was greatly attenuated in STIM1^-/- microglia. Their chemotactic migration defect was reproduced in vivo in embryonic brain; the aggregated number of STIM1^-/- microglia in LPS- (lipopolysaccharide-) injected lesions was much smaller than that in wild-type microglia. Furthermore, the neuron phagoptosis activities of activated microglia were significantly diminished in the STIM1^-/- microglia. These in vitro and in vivo results suggest that STIM1-mediated store-operated calcium entry is important for the regulation of global Ca²⁺i changes which differentiates into active immune state of microglia, but it is more crucial for the regulation of local [Ca²⁺] microdomains which mediates the acute motility of murine microglia.

DOI： 10.1155/2017/8158514

記述言語：英語   掲載種別：研究論文（学術雑誌）  

B-cell receptor (BCR) signaling plays a critical role in B-cell activation and humoral immunity. In this study, we discovered a critical function of leucine-rich repeat kinase 1 (LRRK1) in BCR-mediated immune responses. Lrrk1 mice exhibited altered B1a-cell development and basal immunoglobulin production. In addition, these mice failed to produce IgG3 antibody in response to T cell-independent type 2 antigen due to defects in IgG3 class-switch recombination. Concomitantly, B cells lacking LRRK1 exhibited a profound defect in proliferation and survival upon BCR stimulation, which correlated with impaired BCR-mediated NF-κB activation and reduced expression of NF-κB target genes including Bcl-x L, cyclin D2, and NFATc1/αA. Furthermore, LRRK1 physically interacted and potently synergized with CARMA1 to enhance NF-κB activation. Our results reveal a critical role of LRRK1 in NF-κB signaling in B cells and the humoral immune response.

DOI： 10.1038/srep25738

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/ncomms11205

記述言語：英語  

The activation and differentiation of B cells are pivotal processes with major implications for host defense and the pathogenesis of immune-mediated diseases. During an immune response, B cells respond to cognate antigen by undergoing massive expansion and class switch recombination during the differentiation of B cells into plasma cells. This differentiation can take place either in follicles where they form germinal centers or in extrafollicular foci. With respect to these responses, B cells are exquisitely regulated by their microenvironment and various factors including cytokines. Cytokines represent a diverse group of soluble mediators that can have multifaceted function. It has been shown that many cytokines act on B cells as B cell growth and differentiation factors. This article focuses on the contribution of cytokines to B cell physiological function, including IL-2, IL-4, IL-10, IL-13, IL-21, IL-35, transforming growth factor γ, and interferons, and discusses their implications for the establishment of humoral immunity. We will also focus on the roles of IL-6 and how these contribute to human diseases.

DOI： 10.1016/B978-0-12-374279-7.09017-2

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/82_2015_477

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Cytosolic Ca²⁺ signals, generated through the coordinated translocation of Ca²⁺ across the plasma membrane (PM) and endoplasmic reticulum (ER) membrane, mediate diverse cellular responses. Mitochondrial Ca²⁺ is important for mitochondrial function, and when cytosolic Ca²⁺ concentration becomes too high, mitochondria function as cellular Ca²⁺ sinks. By measuring mitochondrial Ca²⁺ currents, we found that mitochondrial Ca²⁺ uptake was reduced in chicken DT40 B lymphocytes lacking either the ER-localized inositol trisphosphate receptor (IP3R), which releases Ca²⁺ from the ER, or Orai1 or STIM1, components of the PM-localized Ca²⁺-permeable channel complex that mediates store-operated calcium entry (SOCE) in response to depletion of ER Ca²⁺ stores. The abundance of MCU, the pore-forming subunit of the mitochondrial Ca²⁺ uniporter, was reduced in cells deficient in IP3R, STIM1, or Orai1. Chromatin immunoprecipitation and promoter reporter analyses revealed that the Ca²⁺-regulated transcription factor CREB (cyclic adenosine monophosphate response element-binding protein) directly bound the MCU promoter and stimulated expression. Lymphocytes deficient in IP3R, STIM1, or Orai1 exhibited altered mitochondrial metabolism, indicating that Ca²⁺ released from the ER and SOCE-mediated signals modulates mitochondrial function. Thus, our results showed that a transcriptional regulatory circuit involving Ca²⁺-dependent activation of CREB controls the Ca²⁺ uptake capability of mitochondria and hence regulates mitochondrial metabolism.

DOI： 10.1126/scisignal.2005673

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The fundamental concepts surrounding B cells with inhibitory function (regulatory B cells) are now being established. In the context of autoimmune and inflammatory animal models, B cells play an immunomodulatory role via IL-10 production and contribute to limitation of the pathogenesis. Recent studies have notably identified the human counterparts of these cells, which have been suggested to be relevant to the pathophysiology of disease. Clear criteria to identify these cell subsets and the key molecular mechanisms underlying their physiological features are required for understanding the big picture of regulatory B cells. Plasmablasts have recently been identified as a major IL-10-producing regulatory B-cell subset and Ca²⁺ signaling has furthermore been found to contribute to B-cell IL-10 expression. In this review, the signaling components controlling IL-10-dependent B-cell regulatory function and the development of IL-10-competent/-producing B cells and plasmablasts are discussed.

DOI： 10.1093/intimm/dxv027

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.immuni.2014.10.016

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Calcium signals are crucial for diverse cellular functions including adhesion, differentiation, proliferation, effector functions and gene expression. After engagement of the B cell receptor, the intracellular calcium ion (Ca²⁺) concentration is increased promoting the activation of various signaling cascades. While elevated Ca²⁺ in the cytosol initially comes from the endoplasmic reticulum (ER), a continuous influx of extracellular Ca²⁺ is required to maintain the increased level of cytosolic Ca²⁺. Store-operated Ca²⁺ entry manages this process, which is regulated by an ER calcium sensor, stromal interaction molecule (STIM). STIM proteins sense changes in the levels of Ca²⁺ stored within the ER lumen and regulates the Ca²⁺-release activated Ca²⁺ channel in the plasma membrane. This review focuses on the signaling pathways leading to Ca²⁺ influx and the role of Ca²⁺ signals in B cell functions.

DOI： 10.1016/j.molimm.2013.10.006

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.ceca.2014.10.005

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Intrinsically disordered domains have been reported to play important roles in signal transduction networks by introducing cooperativity into protein-protein interactions. Unlike intrinsically disordered domains that become ordered upon binding, the EF-SAM domain in the stromal interaction molecule (STIM) 1 is distinct in that it is ordered in the monomeric state and partially unfolded in its oligomeric state, with the population of the two states depending on the local Ca^{2 +} concentration. The oligomerization of STIM1, which triggers extracellular Ca^{2 +} influx, exhibits cooperativity with respect to the local endoplasmic reticulum Ca ^{2 +} concentration. Although the physiological importance of the oligomerization reaction is well established, the mechanism of the observed cooperativity is not known. Here, we examine the response of the STIM1 EF-SAM domain to changes in Ca^{2 +} concentration using mathematical modeling based on in vitro experiments. We find that the EF-SAM domain partially unfolds and dimerizes cooperatively with respect to Ca^{2 +} concentration, with Hill coefficients and half-maximal activation concentrations very close to the values observed in vivo for STIM1 redistribution and extracellular Ca ^{2 +} influx. Our mathematical model of the dimerization reaction agrees quantitatively with our analytical ultracentrifugation-based measurements and previously published free energies of unfolding. A simple interpretation of these results is that Ca^{2 +} loss effectively acts as a denaturant, enabling cooperative dimerization and robust signal transduction. We present a structural model of the Ca^{2 +}-unbound EF-SAM domain that is consistent with a wide range of evidence, including resistance to proteolytic cleavage of the putative dimerization portion.

DOI： 10.1016/j.jmb.2014.03.006

記述言語：英語   掲載種別：研究論文（学術雑誌）  

In central mammalian neurons, activation of metabotropic glutamate receptor type1 (mGluR1) evokes a complex synaptic response consisting of IP₃ receptor-dependent Ca²⁺ release from internal Ca²⁺ stores and a slow depolarizing potential involving TRPC3 channels. It is largely unclear how mGluR1 is linked to its downstream effectors. Here, we explored the role of stromal interaction molecule 1 (STIM1) in regulating neuronal Ca²⁺ signaling and mGluR1-dependent synaptic transmission. By analyzing mouse cerebellar Purkinje neurons, we demonstrate that STIM1 is an essential regulator of the Ca²⁺ level in neuronal endoplasmic reticulum Ca²⁺ stores. Both mGluR1-dependent synaptic potentials and IP₃ receptor-dependent Ca²⁺ signals are strongly attenuated in the absence of STIM1. Furthermore, the Purkinje neuron-specific deletion of Stim1 causes impairments in cerebellar motor behavior. Together, our results demonstrate that in the mammalian nervous system STIM1 is a key regulator of intracellular Ca²⁺ signaling, metabotropic glutamate receptor-dependent synaptic transmission, and motor coordination.

DOI： 10.1016/j.neuron.2014.03.027

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/ncomms4704

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The stromal-interactingmolecule 1 (STIM1) is a potent sensor of intracellular calcium, which in turn regulates entry of external calcium through plasmamembrane channels to affect immune cell activation. Although the contribution of STIM1 to calcium signaling in lymphocytes has been well studied, the role of this protein in neutrophil-mediated inflammation and host defense is unknown. We report that STIM1-deficient murine neutrophils show loss of store-operated calcium entry (SOCE) in response to both soluble ligands that activate G-proteins as well as Fcγ-receptor or integrin ligation that activates tyrosine kinase signaling. This results in modest defects in phagocytosis and degranulation responses but a profound block in superoxide production by the phagocyte oxidase. We trace the primary intracellular target of calcium to be protein kinase C isoforms α and β (PKCα and PKCβ), which in turn phosphorylate subunits of the oxidase leading to superoxide production. In vivo the loss of SOCE in stim1^-/- chimeric mice results in marked susceptibility to bacterial infections but also protection from tissue injury in hepatic ischemia/reperfusion injury. These results demonstrate the critical role of STIM1-mediated SOCE and define major protein targets of calcium signaling in neutrophil activation during inflammatory disease.

DOI： 10.1182/blood-2012-08-450403

記述言語：英語   掲載種別：研究論文（学術雑誌）  

B cells positively regulate immune responses through antibody production and ešector T cell dišerentiation. In addition to such protective roles against pathogenesis, B cells also serve as negative regulators of autoimmunity by secreting an anti-inflammatory cytokine, interleukin-10 (IL-10). These B cell functions are caused by encountering their cognate antigens through their B cell receptors (BCR). A central response of BCR stimulation is intracellular Ca²+ elevation, which is derived mainly from two pathways, Ca²+ release from endoplasmic reticulum (ER) stores and Ca²+ influx from the extracellular space across the plasma membrane. Although a chief Ca²+ entry pathway in immune cells is store-operated Ca²+ (SOC) influx, which is triggered by depletion of Ca²+ from ER, its physiological role in B cells remains elusive. Stromal interaction molecules (STIM), which consist of STIM1 and its homolog, STIM2, serve as ER calcium sensors and are essential for SOC influx after antigen stimulation. We have recently found that STIM1- and STIM2-in-duced SOC influx is critical for regulatory B cell function required to limit experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Even through several B cell populations have been reported to suppress inflammation of autoimmune diseases through production of IL-10, which subset of them exerts their regulatory function during EAE is not fully understood. This review focuses on our recent progress in the role of STIM-dependent SOC influx as a key signal for B cell regulatory function and the latest & findings for understanding how regulatory B cells suppress the development of EAE.

DOI： 10.1248/yakushi.12-00227-2

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.bbrc.2012.05.037

記述言語：英語   掲載種別：研究論文（学術雑誌）  

In B cells, changes in intracellular concentration of Ca²⁺ drive signal transduction to initiate changes in gene expression and various cellular events, including apoptosis and differentiation. B cell receptor engagement causes a transient Ca²⁺ flux from the endoplasmic reticulum Ca²⁺ store, followed by a continuous increase in intracellular Ca²⁺ concentration, mainly resulting from store-operated Ca²⁺ entry (SOCE). The recent identification of stromal interaction molecule (STIM) and Orai as essential components for SOCE has allowed researchers to probe further the role of Ca²⁺ signals in B cell biology. Here, we summarize the B cell signaling pathways that lead to SOCE, the role of Ca²⁺ signals in B cell regulatory function, and how a breakdown in the balance of Ca²⁺ signals is associated with immune-related disease.

DOI： 10.1016/j.it.2011.09.004

記述言語：英語   掲載種別：研究論文（学術雑誌）  

A chief Ca²⁺ entry pathway in immune cells is store-operated Ca²⁺ (SOC) influx, which is triggered by depletion of Ca²⁺ from the endoplasmic reticulum (ER). However, its physiological role in B cells remains elusive. Here, we show that ER calcium sensors STIM1- and STIM2-induced SOC influx is critical for B cell regulatory function. B cell-specific deletion of STIM1 and STIM2 in mice caused a profound defect in B cell receptor (BCR)-induced SOC influx and proliferation. However, B cell development and antibody responses were unaffected. Remarkably, B cells lacking both STIM proteins failed to produce the anti-inflammatory cytokine IL-10 because of defective activation of nuclear factor of activated T cells (NFAT) after BCR stimulation. This resulted in exacerbation of experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis. Our data establish STIM-dependent SOC influx as a key signal for B cell regulatory function required to limit autoimmunity.

DOI： 10.1016/j.immuni.2011.03.016

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.pbiomolbio.2010.02.004

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1083/jcb.201004152

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Antigen receptors on the surface of B lymphocytes trigger adaptive immune responses after encountering their cognate antigens but also control a series of antigen-independent checkpoints during B cell development. These physiological processes are regulated by the expression and function of cell surface receptors, intracellular signaling molecules, and transcription factors. The function of these proteins can be altered by a dynamic array of post-translational modifications, using two interconnected mechanisms. These modifications can directly induce an altered conformational state in the protein target of the modification itself. In addition, they can create new binding sites for other protein partners, thereby contributing to where and when such multiple protein assemblies are activated within cells. As a new type of post-transcriptional regulator, microRNAs have emerged to luence the development and function of B cells by affecting the expression of target mRNAs.

DOI： 10.1146/annurev.immunol.021908.132541

記述言語：英語   掲載種別：研究論文（学術雑誌）  

In most non-excitable cells, the depletion of intracellular Ca²⁺ stores activates capacitative Ca²⁺ entry (CCE), which is a Ca ²⁺-selective and La³⁺-sensitive entry pathway. Here, we report a novel mechanism of La³⁺-resistant Ca²⁺ entry that is synergistically regulated by B cell receptor (BCR) stimulation and Ca ²⁺ store depletion (B-SOC). In the wildtype (WT) DT40 cells, BCR stimulation with anti-IgM antibodies induced Ca²⁺ release and subsequent Ca²⁺ entry in the presence of 0.3 μMLa³⁺ which blocks CCE completely. In the inositol 1,4,5-trisphosphate receptor-deficient (IP₃R-KO) cells, BCR stimulation elicited neither Ca²⁺ release nor Ca²⁺ entry. However, under pretreatment of thapsigargin (ThG), BCR stimulation induced La³⁺-resistant Ca ²⁺ entry into both WT and IP₃R-KO cells. These results indicate that BCR stimulation and Ca²⁺ store depletion work in concert to activate the La³⁺-resistant Ca²⁺ entry pathway. B-SOC was inhibited by tyrosine kinase inhibitor, genistein. In addition, B-SOC was completely abolished in Stim1-deficient cells and was restored by overexpression of yellow fluorescent protein (YFP)-tagged Stim1, but was unaffected by double knockdown of Orai1/Orai2. These results demonstrate a unique non-CCE pathway, in which Ca²⁺ entry depends on Stim1 and tyrosine kinase activation. It is likely that similar regulation of Ca2+ entry occurs in other cell types including salivary gland cells.

DOI： 10.2152/jmi.56.383

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Calcium signals in immune cells regulate a variety of physiological responses such as cell activation, differentiation, gene transcription, and effector functions. Surface receptor stimulation induces an increase in the concentration of cytosolic calcium ions (Ca²⁺), which are derived mainly from two sources, intracellular endoplasmic reticulum (ER) Ca ²⁺ stores and the extracellular space. The major cascade for Ca ²⁺ entry in immune cells is through store-operated Ca²⁺ entry (SOCE) and Ca²⁺ release-activated Ca²⁺ (CRAC) channels. Activation of SOCE is triggered by depletion of intracellular ER Ca²⁺ stores, but the molecular mechanism was a long-standing issue. With the recent molecular identification of the ER Ca²⁺ sensor [stromal interacting molecule-1 (STIM1)] and a pore-forming subunit of the CRAC channel (Orai1), our understanding of the SOCE activation pathway has increased dramatically. These advances have now made it possible to shed some light on important questions: what is the physiological significance of SOCE, and what is its molecular basis? This review focuses on the recent progress in the field and the exciting opportunities for understanding how SOCE influences diverse immune functions.

DOI： 10.1111/j.1600-065X.2009.00813.x

記述言語：英語   掲載種別：研究論文（学術雑誌）  

STIM proteins are sensors of endoplasmic reticulum (ER) luminal Ca ²⁺ changes and rapidly translocate into near plasma membrane (PM) junctions to activate Ca ²⁺ entry through the Orai family of highly Ca ²⁺-selective "store-operated" channels (SOCs). Dissecting the STIM-Orai coupling process is restricted by the abstruse nature of the ER-PM junctional domain. To overcome this problem, we studied coupling by using STIM chimera and cytoplasmic C-terminal domains of STIM1 and STIM2 (S1ct and S2ct) and identifying a fundamental action of the powerful SOC modifier, 2-aminoethoxy- diphenyl borate (2-APB), the mechanism of which has eluded recent scrutiny. We reveal that 2-APB induces profound, rapid, and direct interactions between S1ct or S2ct and Orai1, effecting full Ca ²⁺ release-activated Ca ²⁺ (CRAC) current activation. The short 235-505 S1ct coiled-coil region was sufficient for functional Orail coupling. YFP-tagged S1ct or S2ct fragments cleared from the cytosol seconds after 2-APB addition, binding avidly to Orai1-CFP with a rapid increase in FRET and transiently increasing CRAC current 200-fold above basal levels. Functional S1ct-Orai1 coupling occurred in STIM1/STIM2-/" DT40 chicken B cells, indicating ct fragments operate independently of native STIM proteins. The 2-APB-induced S1ct-Orai1 and S2-ct-Orai1 complexes undergo rapid reorganization into discrete colocalized PM clusters, which remain stable for >100 s, well beyond CRAC activation and subsequent deactivation. In addition to defining 2-APB's action, the locked STIMct-Orai complex provides a potentially useful probe to structurally examine coupling.

DOI： 10.1073/pnas.0900293106

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The depletion of intracellular Ca²⁺ stores activates capacitative Ca²⁺ entry (CCE), which is a Ca²⁺-selective and La³⁺-sensitive entry pathway. Here, we report a novel mechanism of La³⁺-resistant Ca²⁺ entry that is synergistically regulated by B-cell-receptor (BCR) stimulation and Ca²⁺ store depletion. In DT40 cells, stimulation of BCRs with anti-IgM antibodies induced Ca²⁺ release and subsequent Ca²⁺ entry in the presence of 0.3 μM La³⁺, a condition in which CCE is completely blocked. This phenomenon was not observed in inositol 1,4,5-trisphosphate receptor-deficient DT40 (IP3R-KO) cells. However, in response to thapsigargin pretreatment, BCR stimulation induced La³⁺- resistant Ca²⁺ entry into both wild-type and IP3R-KO cells. These results indicate that BCR stimulation alone does not activate Ca²⁺ entry, whereas BCR stimulation and depleted Ca²⁺ stores (either due to IP3R-mediated Ca²⁺ release or Ca²⁺ uptake inhibition) work in concert to activate La³⁺-resistant Ca²⁺ entry. This Ca²⁺ entry was inhibited by genistein. In addition, BCR-mediated Ca²⁺ entry was completely abolished in Stim1-deficient DT40 cells and was restored by overexpression of YFP-Stim1, but was unaffected by double knockdown of Orai1 and Orai2. These results demonstrate a unique non-CCE pathway, in which Ca²⁺ entry depends on Stim1- and BCR-mediated activation of tyrosine kinases.

DOI： 10.1242/jcs.041640

記述言語：英語   掲載種別：研究論文（学術雑誌）  

The Wnt family of secreted glycoproteins has been implicated in many aspects of development, but its contribution to blood cell formation is controversial. We overexpressed Wnt3a, Wnt5a, and Dickkopf 1 in stromal cells from osteopetrotic mice and used them in coculture experiments with highly enriched stem and progenitor cells. The objective was to learn whether and how particular stages of B lymphopoiesis are responsive to these Wnt family ligands. We found that canonical Wnt signaling, through Wnt3a, inhibited B and plasmacytoid dendritic cell, but not conventional dendritic cell development. Wnt5a, which can oppose canonical signaling or act through a different pathway, increased B lymphopoiesis. Responsiveness to both Wnt ligands diminished with time in culture and stage of development. That is, only hematopoietic stem cells and very primitive progenitors were affected. Although Wnt3a promoted retention of hematopoietic stem cell markers, cell yields and dye dilution experiments indicated it was not a growth stimulus. Other results suggest that lineage instability results from canonical Wnt signaling. Lymphoid progenitors rapidly down-regulated RAG-1, and some acquired stem cell-staining characteristics as well as myeloid and erythroid potential when exposed to Wnt3a-producing stromal cells. We conclude that at least two Wnt ligands can differentially regulate early events in B lymphopoiesis, affecting entry and progression in distinct differentiation lineages.

DOI： 10.4049/jimmunol.181.6.3955

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/ni1546

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1073/pnas.0608358103

記述言語：英語   掲載種別：研究論文（学術雑誌）  

This study was designed to investigate one component of the Wnt/β-catenin signaling pathway that has been implicated in stem cell self-renewal. Retroviral-mediated introduction of stable β-catenin to primitive murine bone marrow cells allowed the expansion of multipotential c-Kit^lowSca-1^low/-CD19^- CD11b/Mac-1 ^-Flk^-2^-CD43⁺AA4.1 ⁺NK1.1⁺CD3^-CD11c^-Gr-1 ^-CD45R/B220⁺ cells in the presence of stromal cells and cytokines. They generated myeloid, T, and B lineage lymphoid cells in culture, but had no T lymphopoietic potential when transplanted. Stem cell factor and IL-6 were found to be minimal requirements for long-term, stromal-free propagation, and a β-catenin-transduced cell line was maintained for 5 mo with these denned conditions. Although multipotential and responsive to many normal stimuli in culture, it was unable to engraft several types of irradiated recipients. These findings support previous studies that have implicated the canonical Wnt pathway signaling in regulation of multipotent progenitors. In addition, we demonstrate how it may be experimentally manipulated to generate valuable cell lines.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Levels of the nuclear factor-kappa B (NF-κB)/Rel family of proteins are carefully modulated in differentiating lymphocytes, where these transcription factors are thought to be important for survival and fate decisions. In contrast, gene-targeting experiments have not revealed clear roles for these transcription factors in lymphopoiesis within bone marrow. Inhibition of NF-κB by introduction of mutated IκBα, a 'superinhibitor' of NF-κB, into hematopoietic stem cells or early progenitors suppressed B as well as T lymphopoiesis following transplantation into immunodeficient mice. Furthermore, a NF-κB essential modifier-binding domain (NBD) peptide that blocks IKB kinase (IKK) activity selectively impaired the generation of adult B lineage cells. However, this suppression did not occur when a neutralizing antibody to tumor necrosis factor α (TNFα) was added to the cultures, or in circumstances where few non-lymphoid cells were present. We conclude that while NF-κB plays a survival-promoting role in lymphoid progenitors, this may only be significant in circumstances such as transplantation when levels of TNFα are high.

DOI： 10.1093/intimm/dxl002

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.immuni.2005.10.009

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1182/blood-2005-02-0456

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.coi.2005.01.012

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.it.2004.09.010

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/sj.leu.2403330

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Activation of phospholipase C-γ2 (PLCγ2) is the critical step in B cell antigen receptor (BCR)-coupled calcium signaling. Although genetic dissection experiments on B cells have demonstrated that Bruton's tyrosine kinase (Btk) and Syk are required for activating PLCγ2, the exact activation mechanism of PLCγ2 by these kinases has not been established. We identify the tyrosine residues 753, 759, 1197 and 1217 in rat PLCγ2 as Btk-dependent phosphorylation sites by using an in vitro kinase assay. To evaluate the role of these tyrosine residues in phosphorylation-dependent activation of PLCγ2, PLCγ2-deficient DT40 cells were reconstituted with a series of mutant PLCγ2s in which the phenylalanine was substituted for tyrosine. Substitution of all four tyrosine residues almost completely eliminated the BCR-induced PLCγ2 phosphorylation, indicating that these residues include the major phosphorylation sites upon BCR engagement. Cells expressing PLCγ2 with a single substitution exhibited some extent of reduction in calcium mobilization, whereas those expressing quadruple mutant PLCγ2 showed greatly reduced calcium response. These findings indicate that the phosphorylations of the tyrosine residues 753, 759, 1197, and 1217, which have been identified as Btk-dependent phosphorylation sites in vitro, coordinately contribute to BCR-induced activation of PLCγ2.

DOI： 10.1074/jbc.M103675200

記述言語：英語   掲載種別：研究論文（学術雑誌）  

X-linked agammaglobulinaemia (XLA) is a primary immunodeficiency caused by mutations in the gene coding for Bruton's tyrosine kinase (Btk) and is characterized by an arrest of B-cell development. We analysed Btk protein expression in platelets using flow cytometry and found that normal platelets express large amounts of Btk. Assessment of affected males from 45 unrelated XLA families revealed that platelets of the majority of the patients (37 out of 45 families) had decreased or absent Btk expression, and that platelets from carrier females of these families had both normal and mutated Btk expression, indicating that megakaryocytes in XLA carriers undergo random X-chromosome inactivation. These observations demonstrate that Btk is not crucial for maturation of megakaryocytes and the production of platelets. No correlation between Btk expression in platelets and clinical phenotype was observed in this study. Flow cytometric evaluation using platelets is a simple and rapid method to test Btk expression. It may be used as a screening test for XLA and for carrier detection, followed, if necessary, by more expensive mutation analyses.

DOI： 10.1046/j.1365-2141.2001.02905.x

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Btk is a critical molecule in B cell antigen receptor (BCR)-coupled signaling, and its activity is regulated by Lyn and Syk. Although the molecular mechanism of Lyn-dependent Btk activation has been investigated, that of Syk-dependent Btk activation has remained unidentified. We have demonstrated that BLNK mediates Syk-dependent Btk activation. In a reconstitution cell system, coexpression of BLNK allows Syk to phosphorylate Btk on its tyrosine 551, leading to the enhancement of Btk activity. This phosphorylation depends on the interaction of Btk and BLNK by means of the Btk-Src homology 2 domain. The existence of such an activation mechanism is supported by the observation that the BCR-induced Btk phosphorylation and activation are significantly reduced in BLNK-deficient B cells as well as in Syk-deficient B cells. Although previous observations have identified the function of BLNK as the linker that integrates the action of Btk and Syk into downstream effectors such as phospholipase Cγ2, our present study indicates another function of BLNK that connects the activity of Syk to that of Btk.

DOI： 10.1073/pnas.051626198

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/S0065-2776(01)77016-2

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Bruton's tyrosine kinase (Btk) is a critical component in the B-cell antigen receptor (BCR)-coupled signaling pathway. Its deficiency in B cells leads to loss or marked reduction in the BCR-induced calcium signaling. It is known that this BCR-induced calcium signaling depends on the activation of phospholipase Cγ (PLCγ), which is mediated by Btk and another tyrosine kinase Syk and that the SH2 and pleckstrin homology (PH) domains of Btk play important roles in this activation process. Although the importance of the PH domain of Btk has been explained by its role in the membrane targeting of Btk, the functional significance of the SH2 domain in the calcium signaling has remained merely a matter of speculation. In this report, we identify that one of the major Btk-SH2 domain-binding proteins in B cells is BLNK (B-cell linker protein) and present evidences that the interaction of BLNK and the SH2 domain of Btk contributes to the complete tyrosine phosphorylation of PLCγ.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Bruton's tyrosine kinase (Btk) is a cytoplasmic tyrosine kinase that is crucial for human and murine B cell development, and its deficiency causes human X-linked agammaglobulinemia and murine X-linked immunodeficiency. In this report, we describe the function of the Btk-binding protein Sab (SH3- domain binding protein that preferentially associates with Btk), which we reported previously as a newly identified Src homology 3 domain-binding protein. Sab was shown to inhibit the auto- and transphosphorylation activity of Btk, which prompted us to propose that Sab functions as a transregulator of Btk. Forced overexpression of Sab in B cells led to the reduction of B cell antigen receptor-induced tyrosine phosphorylation of Btk and significantly reduced both early and late B cell antigen receptor-mediated events, including calcium mobilization, inositol 1,4,5-trisphosphate production, and apoptotic cell death, where the involvement of Btk activity has been demonstrated previously. Together, these results indicate the negative regulatory role of Sab in the B cell cytoplasmic tyrosine kinase pathway.

DOI： 10.1073/pnas.96.11.6341

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Bruton's tyrosine kinase (Btk) has been shown to play a role in normal B-lymphocyte development. Defective expression of Btk leads to human and murine immunodeficiencies. However, the exact role of Btk in the cytoplasmic signal transduction in B cells is still unclear. This study represents a search for the substrate for Btk in vivo. We identified one of the major phosphoproteins associated with Btk in the preB cell line NALM6 as the Wiskott-Aldrich syndrome protein (WASP), the gene product responsible for Wiskott-Aldrich syndrome, which is another hereditary immunodeficiency with distinct abnormalities in hematopoietic cells. We demonstrated that WASP was transiently tyrosine-phosphorylated after B-cell antigen receptor cross- linking on B cells, suggesting that WASP is located downstream of cytoplasmic tyrosine kinases. An in vivo reconstitution system demonstrated that WASP is physically associated with Btk and can serve as the substrate for Btk. A protein binding assay suggested that the tyrosine-phosphorylation of WASP alters the association between WASP and a cellular protein. Furthermore, identification of the phosphorylation site of WASP in reconstituted cells allowed us to evaluate the catalytic specificity of Btk, the exact nature of which is still unknown.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Platelets contain substantial amounts of Btk that can be readily demonstrated by staining permeabilized platelets with monoclonal antibody 48-2H followed by flow cytometry. To test the usefulness of this technique for establishing the diagnosis of XLA and to identify carrier females, we quantified Btk by staining platelets from normal controls, XLA patients with known Btk mutations, and female relatives of XLA patients with ascertained carrier status. Platelets isolated from fresh or up-to-two-day-old citrated blood were permeabilized with Saponin, incubated with mAb 48-2H, and staining intensity measured by flow cytometry. The staining patterns observed identified affected boys and carrier females in 12 of 14 XLA families studied. In eight families, patient platelets failed to bind mAb 48-2H (A) and carrier platelets showed two distinct peaks (D); in four families the mAb binding by XLA platelets was decreased (B) and carrier females showed two peaks forming a shoulder (E); two families showed a normal pattern (C, F). These results suggest that the majority (∼ 85%) of Btk mutations observed in XLA families result in the absence of Btk or in a mutated protein that is poorly recognized by mAb 48-2H, and that megakaryocytes from female carriers for XLA undergo random X-inactivation. (Graph Presented).

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Protein interaction cloning method was used to identify a novel molecule, Sab, which binds to the SH3 domain of Bruton's tyrosine kinase (Btk), the deficient cytoplasmic tyrosine kinase in human X-linked agammaglobulinemia and murine X-linked immunodeficiency. Immunoprecipitation using the anti-Sab antibody identified the protein product of the gene as a 70 kDa molecule. While Sab does not have a proline-rich sequence, it was shown to bind to Btk through the commonly conserved structure among SH3 domains. Remarkably, Sab exhibited a high preference for binding to Btk rather than to other cytoplasmic tyrosine kinases, which suggests a unique role of Sab in the Btk signal transduction pathway.

DOI： 10.1006/bbrc.1998.8420

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Bruton's tyrosine kinase (Btk) is a cytoplasmic tyrosine kinase which is involved in the pathogenesis of human and murine B cell deficiencies. In this study, we attempted to identify the downstream molecule in the Btk signaling pathway. We showed that WASP physically associated with Btk in B-lineage cells and was constitutively phosphorylated on its tyrosine in a preB cell line in which the tyrosine-phosphorylation of Btk was also prominent WASP was shown to be phosphorylated by Btk in cotransfection system. The phosphotyrosine motif of WASP was distinctly similar to that of the autophosphorylation site of Btk. Furthermore, WASP was shown to be tyrosine-phosphorylated upon B cell antigen receptor crosslinking. These results indicate a physical and functional link of Btk and WASP, and also suggest a possible involvement of WASP in the antigen receptor signaling pathway in B-lineage cells together with Btk.

記述言語：英語   掲載種別：研究論文（学術雑誌）  

In our monoclonal antibody (MAb) stocks prepared against the BHK-21 cell antigens, two (11875 and 28276) recognized a 21-kDa polypeptide (referred to as VAP21) which is efficiently incorporated into the rabies virion. By using these MAbs, we isolated the cDNA clones that encoded a polypeptide of 144 amino acids from our BHK-21 cell cDNA library. Based on the following evidence, the cDNA was assumed to encode a full-length sequence of VAP21 antigen: i) expression of the eDNA in animal cells resulted in the production of a polypeptide recognized by the two MAbs, and its electrophoretic mobility was the same as that of authentic VAP21 antigen; and ii) immunization with the products from the cDNA-transformed E. coli cells raised specific antibodies in rabbits that recognized a 21-kDa polypeptide in the virion. From the deduced amino acid sequence, it is suggested that the VAP21 antigen has a molecular structure of type-I transmembrane protein containing characteristic proline-rich and glycine-rich regions in its ectodomain. Homology searches resulted in finding homologous sequences (totally about 40 % homology) in the human MIC2 gene product (CD99; 32-kDa) of T lymphocytes. These results suggest that the VAP21 antigen in the rabies virion is a cellular CD99-related transmembrane protein.

DOI： 10.1111/j.1348-0421.1998.tb02285.x

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開催年月日： 2023年6月

記述言語：日本語  

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開催年月日： 2023年6月

記述言語：日本語  

国名：日本国  

開催年月日： 2023年6月

記述言語：日本語  

国名：日本国  

開催年月日： 2023年6月 - 2023年3月

記述言語：日本語  

国名：日本国  

開催年月日： 2022年2月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：web開催   国名：日本国  

開催年月日： 2021年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：web開催   国名：日本国  

開催年月日： 2021年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：web開催   国名：日本国  

開催年月日： 2020年12月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：web開催   国名：日本国  

開催年月日： 2020年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：web開催   国名：日本国  

開催年月日： 2019年6月

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催地：千葉   国名：日本国  

開催年月日： 2019年6月

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催地：東京   国名：日本国  

開催年月日： 2019年6月

記述言語：日本語   会議種別：公開講演，セミナー，チュートリアル，講習，講義等  

開催地：鳥取県米子市   国名：日本国  

開催年月日： 2018年12月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2018年12月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡国際会議場   国名：日本国  

開催年月日： 2018年7月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2017年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：神戸   国名：日本国  

開催年月日： 2017年8月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：京都   国名：日本国  

開催年月日： 2017年7月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡   国名：日本国  

開催年月日： 2016年1月

記述言語：英語   会議種別：シンポジウム・ワークショップ パネル（公募）  

開催地：Osaka   国名：日本国  

開催年月日： 2015年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：神戸学院大学、神戸   国名：日本国  

開催年月日： 2012年12月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：福岡国際会議場，福岡   国名：日本国  

開催年月日： 2012年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：京王プラザホテル，東京   国名：日本国  

開催年月日： 2012年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：札幌   国名：日本国  

開催年月日： 2011年12月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：大阪大学銀杏会館, 大阪   国名：日本国  

開催年月日： 2011年7月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2010年7月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2010年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：大阪国際会議場, 大阪   国名：日本国  

開催年月日： 2009年12月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：大阪国際会議場, 大阪   国名：日本国  

開催年月日： 2009年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：東京ステーションコンファレンス, 東京   国名：日本国  

開催年月日： 2009年8月

記述言語：日本語   会議種別：口頭発表（一般）  

国名：日本国  

開催年月日： 2009年2月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：大阪大学銀杏会館, 大阪   国名：日本国  

開催年月日： 2009年1月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：神戸セミナーハウス, 兵庫   国名：日本国  

開催年月日： 2008年6月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：岡崎コンファレンスセンター, 愛知   国名：日本国  

開催年月日： 2008年5月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：慶応大学医学部, 東京   国名：日本国  

開催年月日： 2008年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：東京大学医科学研究所, 東京   国名：日本国  

開催年月日： 2007年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：岡崎コンファレンスセンター, 愛知   国名：日本国  

開催年月日： 2006年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：岡崎コンファレンスセンター, 愛知   国名：日本国  

記述言語：英語   会議種別：口頭発表（一般）  

国名：日本国  

記述言語：日本語  

国名：日本国  

記述言語：日本語  

開催地：浜松   国名：日本国  

記述言語：日本語  

開催地：浜松市   国名：日本国  

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：浜松   国名：日本国  

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

記述言語：日本語   掲載種別：記事・総説・解説・論説等（学術雑誌）  

種別：査読等 

外国語雑誌　査読論文数：10

種別：大会・シンポジウム等 

種別：大会・シンポジウム等 

種別：大会・シンポジウム等 

種別：大会・シンポジウム等 

『アレルギーの元』引き込む細胞内たんぱく質

タンパク質STIM1 アレルギー反応を制御

アレルギー起こすたんぱく質を発見

アレルギー発症の原因　たんぱく質特定

アレルギー原因たんぱく質解明

アレルギー反応誘発　必須たんぱく質発見

アレルギー反応の制御因子　たん白質『STIM1』特定