Acute Csk inhibition hinders B cell activation by constraining the PI3 kinase pathway.
Acute Csk inhibition hinders B cell activation by constraining the PI3 kinase pathway.
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DOI：
10.1073/pnas.2108957118
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发表时间：
2021-10-26
影响因子：
11.1
通讯作者：
Weiss A
中科院分区：
文献类型：
--
作者：
Lu W;Skrzypczynska KM;Weiss A
B淋巴细胞识别致病抗原，并通过其B细胞受体(BCR)被激活。这种依赖于bcr的激活是由src家族激酶(Sfk)控制的。目前尚不清楚B细胞如何耐受SFK活性的波动，并在没有外来抗原的情况下保持无反应性。利用化学遗传系统，我们强烈地抑制C-末端的Src激酶以增强小鼠B细胞中SFK的活性。令人惊讶的是，我们观察到由于相关的磷脂酰肌醇-三磷酸途径的损伤，bcr下游信号的显著抑制。这些结果揭示了在静止的B细胞中保持适量的SFK活性对于适当的bcr依赖反应至关重要，这可能是幼稚B细胞对自身抗原无反应以维持外周耐受的关键。T细胞抗原受体(TCR)和B细胞抗原受体(BCR)信号是由Src家族激酶(SFKs)启动和严格调控的。SFK对幼稚T细胞的TCR信号有正向调节作用，而对幼稚B细胞的BCR信号有正向和负向调节作用。其活性的适当调节依赖于受体酪氨酸磷酸酶CD45和CD148以及细胞质酪氨酸激酶C末端的Src激酶CSK的相反作用。CSK是SFK的主要负性调节因子。利用PP1类似物敏感的CSK(CskAS)系统，我们先前已经证明，抑制CskAS会增加SFK的活性，导致T细胞对弱TCR刺激的反应增强。然而，CSK对B细胞的抑制作用尚不清楚。在这项研究中，我们惊讶地发现，抑制Cskas导致显著抑制BCR刺激的胞浆游离钙增加和ERK激活，尽管B细胞中的SFK激活增加，这与在T细胞中观察到的效果相反。进一步研究发现，Cskas的急性抑制抑制了BCR介导的B细胞磷脂酰肌醇3，4，5-三磷酸(PIP3)的产生。通过CD19交联或SHIP1缺失恢复B细胞PIP3水平可消除Cskas抑制的负性调节作用。这揭示了CSK在维持适当水平的SFK活性和调节PIP3数量方面的关键作用，作为一种补偿SFK波动的手段，以防止不适当的B细胞激活。这种控制PIP3含量的调节机制也可能有助于B细胞无能和自我耐受。
B lymphocytes recognize pathogenic antigens and become activated via their B cell receptors (BCR). This BCR-dependent activation is controlled by Src-family kinases (SFKs). It is unclear how B cells tolerate the fluctuations of SFK activities and maintain unresponsiveness in the absence of foreign antigens. Using a chemical-genetic system, we acutely inhibited C-terminal Src kinase to enhance the SFK activity in mouse B cells. Surprisingly, we observed marked inhibition of BCR-downstream signaling due to associated impairment of the phosphatidylinositol-trisphosphate pathway. These results reveal the critical importance of maintaining a proper amount of SFK activity in quiescent B cells for appropriate BCR-dependent responses, which may be critical for naïve B cell unresponsiveness to self-antigens to maintain peripheral tolerance. T cell antigen receptor (TCR) and B cell antigen receptor (BCR) signaling are initiated and tightly regulated by Src-family kinases (SFKs). SFKs positively regulate TCR signaling in naïve T cells but have both positive and negative regulatory roles in BCR signaling in naïve B cells. The proper regulation of their activities depends on the opposing actions of receptor tyrosine phosphatases CD45 and CD148 and the cytoplasmic tyrosine kinase C-terminal Src kinase Csk. Csk is a major negative regulator of SFKs. Using a PP1-analog-sensitive Csk (CskAS) system, we have previously shown that inhibition of CskAS increases SFK activity, leading to augmentation of responses to weak TCR stimuli in T cells. However, the effects of Csk inhibition in B cells were not known. In this study, we surprisingly found that inhibition of CskAS led to marked inhibition of BCR-stimulated cytoplasmic free calcium increase and Erk activation despite increased SFK activation in B cells, contrasting the effects observed in T cells. Further investigation revealed that acute CskAS inhibition suppressed BCR-mediated phosphatidylinositol 3,4,5-trisphosphate (PIP3) production in B cells. Restoring PIP3 levels in B cells by CD19 cross-linking or SHIP1 deficiency eliminated the negative regulatory effect of CskAS inhibition. This reveals the critical role of Csk in maintaining an appropriate level of SFK activity and regulating PIP3 amounts as a means of compensating for SFK fluctuations to prevent inappropriate B cell activation. This regulatory mechanism controlling PIP3 amounts may also contribute to B cell anergy and self-tolerance.
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DOI：
10.1084/jem.20020515
发表时间：
2002-12-16
期刊：
The Journal of experimental medicine
影响因子：
--
作者：
Hibbs ML;Harder KW;Armes J;Kountouri N;Quilici C;Casagranda F;Dunn AR;Tarlinton DM
通讯作者：
Tarlinton DM
B细胞受体的单价和多价连接表现出对SYK和SRC家族激酶的差异依赖性。
影响因子：
7.3
作者：
Mukherjee S;Zhu J;Zikherman J;Parameswaran R;Kadlecek TA;Wang Q;Au-Yeung B;Ploegh H;Kuriyan J;Das J;Weiss A
通讯作者：
Weiss A
影响因子：
30.5
作者：
Chang VT;Fernandes RA;Ganzinger KA;Lee SF;Siebold C;McColl J;Jönsson P;Palayret M;Harlos K;Coles CH;Jones EY;Lui Y;Huang E;Gilbert RJC;Klenerman D;Aricescu AR;Davis SJ
通讯作者：
Davis SJ
影响因子：
20.3
作者：
Cordoba, Shaun-Paul;Choudhuri, Kaushik;van der Merwe, P. Anton
通讯作者：
van der Merwe, P. Anton
影响因子：
5.3
作者：
Dobenecker, MW;Schmedt, C;Tarakhovsky, A
通讯作者：
Tarakhovsky, A