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J Leukoc Biol. 2015 May;97(5):887-900. doi: 10.1189/jlb.2A0714-320R. Epub 2015 Mar 4.

A negative-feedback function of PKCβ in the formation and accumulation of signaling-active B cell receptor microclusters within B cell immunological synapse.

Author information

1
*MOE Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing, China; Collaborative Innovation Center for Infectious Diseases, Hangzhou, China; Department of Immunology, Bio-therapeutic Department, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China; Department of Rheumatology and Clinical Immunology, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China; Key Laboratory of Rheumatology and Clinical Immunology, Ministry of Education, Beijing, China; and **State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
2
*MOE Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing, China; Collaborative Innovation Center for Infectious Diseases, Hangzhou, China; Department of Immunology, Bio-therapeutic Department, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China; Department of Rheumatology and Clinical Immunology, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China; Key Laboratory of Rheumatology and Clinical Immunology, Ministry of Education, Beijing, China; and **State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China liuwanli@biomed.tsinghua.edu.cn.

Abstract

Advanced live cell imaging studies suggested that B cell activation is initiated by the formation of BCR microclusters and subsequent B cell IS upon BCR and antigen recognition. PKC family member PKCβ is highly expressed in B cells and plays an important role in the initiation of B cell activation. Here, we reported an inhibitory function of PKCβ through a negative-feedback manner in B cell activation. Compared with WT (PKCβ-WT) or the constitutively active (PKCβ-ΔNPS) form of PKCβ, DN PKCβ (PKCβ-DN) unexpectedly enhanced the accumulation of BCR microclusters into the B cell IS, leading to the recruitment of an excessive amount of pSyk, pPLC-γ2, and pBLNK signaling molecules into the membrane-proximal BCR signalosome. Enhanced calcium mobilization responses in the decay phase were also observed in B cells expressing PKCβ-DN. Mechanistic studies showed that this negative-feedback function of PKCβ works through the induction of an inhibitory form of pBtk at S180 (pBtk-S180). Indeed, the capability of inducing the formation of an inhibitory pBtk-S180 is in the order of PKCβ-ΔNPS > PKCβ-WT > PKCβ-DN. Thus, these results improve our comprehensive understanding on the positive and negative function of PKCβ in the fine tune of B cell activation.

KEYWORDS:

Btk; activation

PMID:
25740961
DOI:
10.1189/jlb.2A0714-320R

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