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Abstract
B cells are essential to the adaptive immune system for providing the humoral immunity against cohorts of pathogens. The presentation of antigen to the B cell receptor (BCR) leads to the initiation of B cell activation, which is a process sensitive to the stiffness features of the substrates presenting the antigens. Mechanosensing of the B cells, potentiated through BCR signaling and the adhesion molecules, efficiently regulates B cell activation, proliferation and subsequent antibody responses. Defects in sensing of the antigen-presenting substrates can lead to the activation of autoreactive B cells in autoimmune diseases. The use of high-resolution, high-speed live-cell imaging along with the sophisticated biophysical materials, has uncovered the mechanisms underlying the initiation of B cell activation within seconds of its engagement with the antigen presenting substrates. In this chapter, we reviewed studies that have contributed to uncover the molecular mechanisms of B cell mechanosensing during the initiation of B cell activation.
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Affiliation(s)
- Samina Shaheen
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Zhengpeng Wan
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Kabeer Haneef
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Yingyue Zeng
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Wang Jing
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China
| | - Wanli Liu
- Center for life sciences, MOE Key Laboratory of Protein Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing Key Lab for Immunological Research on Chronic Diseases, School of Life Sciences, Institute for Immunology, Tsinghua University, Beijing, China.
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Unperturbed Immune Function despite Mutation of C-Terminal Tyrosines in Syk Previously Implicated in Signaling and Activity Regulation. Mol Cell Biol 2017; 37:MCB.00216-17. [PMID: 28760774 DOI: 10.1128/mcb.00216-17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/26/2017] [Indexed: 11/20/2022] Open
Abstract
The nonreceptor tyrosine kinase Syk, a central regulator of immune cell differentiation and activation, is a promising drug target for treatment of leukemia and allergic and inflammatory diseases. The clinical failure of Syk inhibitors underscores the importance of understanding the regulation of Syk function and activity. A series of previous studies emphasized the importance of three C-terminal tyrosines in Syk for kinase activity regulation, as docking sites for downstream effector molecules, and for Ca2+ mobilization. Here, we investigated the roles of these C-terminal tyrosines in the mouse. Surprisingly, expression of a triple tyrosine-to-phenylalanine human Syk mutant, SYK(Y3F), was not associated with discernible signaling defects either in reconstituted DT40 cells or in B or mast cells from mice expressing SYK(Y3F) instead of wild-type Syk. Remarkably, lymphocyte differentiation, calcium mobilization, and 2,4,6-trinitrophenyl (TNP)-specific immune responses were unperturbed in SYK(Y3F) mice. These results emphasize the capacity of immune cells to compensate for specific molecular defects, likely using redundant intermolecular interactions, and highlight the importance of in vivo analyses for understanding cellular signaling mechanisms.
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Bojarczuk K, Bobrowicz M, Dwojak M, Miazek N, Zapala P, Bunes A, Siernicka M, Rozanska M, Winiarska M. B-cell receptor signaling in the pathogenesis of lymphoid malignancies. Blood Cells Mol Dis 2015; 55:255-65. [PMID: 26227856 DOI: 10.1016/j.bcmd.2015.06.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 06/21/2015] [Indexed: 11/17/2022]
Abstract
B-cell receptor (BCR) signaling pathway plays a central role in B-lymphocyte development and initiation of humoral immunity. Recently, BCR signaling pathway has been shown as a major driver in the pathogenesis of B-cell malignancies. As a result, a vast array of BCR-associated kinases has emerged as rational therapeutic targets changing treatment paradigms in B cell malignancies. Based on high efficacy in early-stage clinical trials, there is rapid clinical development of inhibitors targeting BCR signaling pathway. Here, we describe the essential components of BCR signaling, their function in normal and pathogenic signaling and molecular effects of their inhibition in vitro and in vivo.
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Affiliation(s)
- Kamil Bojarczuk
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland; Postgraduate School of Molecular Medicine, Medical University of Warsaw, Zwirki I Wigury 61, 02-091 Warsaw, Poland
| | - Malgorzata Bobrowicz
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland; Postgraduate School of Molecular Medicine, Medical University of Warsaw, Zwirki I Wigury 61, 02-091 Warsaw, Poland
| | - Michal Dwojak
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland; Postgraduate School of Molecular Medicine, Medical University of Warsaw, Zwirki I Wigury 61, 02-091 Warsaw, Poland
| | - Nina Miazek
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Piotr Zapala
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Anders Bunes
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Marta Siernicka
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland; Postgraduate School of Molecular Medicine, Medical University of Warsaw, Zwirki I Wigury 61, 02-091 Warsaw, Poland
| | - Maria Rozanska
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland
| | - Magdalena Winiarska
- Department of Immunology, Center for Biostructure Research, Medical University of Warsaw, Banacha 1A, 02-097 Warsaw, Poland.
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Abstract
B cells differentiate from pluripotent hematopoietic stem cells (pHSCs) in a series of distinct stages. During early embryonic development, pHSCs migrate into the fetal liver, where they develop and mature to B cells in a transient wave, which preferentially populates epithelia and lung as well as gut-associated lymphoid tissues. This is followed by continuous B cell development throughout life in the bone marrow to immature B cells that migrate to secondary lymphoid tissues, where they mature. At early stages of development, before B cell maturation, the gene loci encoding the heavy and light chains of immunoglobulin that determine the B cell receptor composition undergo stepwise rearrangements of variable region-encoding gene segments. Throughout life, these gene rearrangements continuously generate B cell repertoires capable of recognizing a plethora of self-antigens and non-self-antigens. The microenvironment in which these B cell repertoires develop provide signaling molecules that play critical roles in promoting gene rearrangements, proliferation, survival, or apoptosis, and that help to distinguish self-reactive from non-self-reactive B cells at four distinct checkpoints. This refinement of the B cell repertoire directly contributes to immunity, and defects in the process contribute to autoimmune disease.
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Zeng Y, Yi J, Wan Z, Liu K, Song P, Chau A, Wang F, Chang Z, Han W, Zheng W, Chen YH, Xiong C, Liu W. Substrate stiffness regulates B-cell activation, proliferation, class switch, and T-cell-independent antibody responses in vivo. Eur J Immunol 2015; 45:1621-34. [PMID: 25756957 DOI: 10.1002/eji.201444777] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 01/30/2015] [Accepted: 03/06/2015] [Indexed: 12/17/2022]
Abstract
B cells use B-cell receptors (BCRs) to sense antigens that are usually presented on substrates with different stiffness. However, it is not known how substrate stiffness affects B-cell proliferation, class switch, and in vivo antibody responses. We addressed these questions using polydimethylsiloxane (PDMS) substrates with different stiffness (20 or 1100 kPa). Live cell imaging experiments suggested that antigens on stiffer substrates more efficiently trigger the synaptic accumulation of BCR and phospho-Syk molecules compared with antigens on softer substrates. In vitro expansion of mouse primary B cells shows different preferences for substrate stiffness when stimulated by different expansion stimuli. LPS equally drives B-cell proliferation on stiffer or softer substrates. Anti-CD40 antibodies enhance B-cell proliferation on stiffer substrates, while antigens enhance B-cell proliferation on softer substrates through a mechanism involving the enhanced phosphorylation of PI3K, Akt, and FoxO1. In vitro class switch differentiation of B cells prefers softer substrates. Lastly, NP67-Ficoll on softer substrates accounted for an enhanced antibody response in vivo. Thus, substrate stiffness regulates B-cell activation, proliferation, class switch, and T cell independent antibody responses in vivo, suggesting its broad application in manipulating the fate of B cells in vitro and in vivo.
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Affiliation(s)
- Yingyue Zeng
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China.,Collaborative Innovation Center for Infectious Diseases, Hangzhou, China
| | - Junyang Yi
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China.,Collaborative Innovation Center for Infectious Diseases, Hangzhou, China
| | - Zhengpeng Wan
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Kai Liu
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Ping Song
- College of Engineering, Peking University, Beijing, China
| | - Alicia Chau
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Fei Wang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Zai Chang
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Weidong Han
- Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
| | - Wenjie Zheng
- Department of Rheumatology and Clinical Immunology, Peking Union Medical College Hospital, Beijing, China
| | - Ying-Hua Chen
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Chunyang Xiong
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.,College of Engineering, Peking University, Beijing, China
| | - Wanli Liu
- MOE Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China.,Collaborative Innovation Center for Infectious Diseases, Hangzhou, China
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