Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium.
Center for Inflammation Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Ghent, Belgium.
FEBS J. 2021 Mar;288(5):1630-1647. doi: 10.1111/febs.15522. Epub 2020 Sep 1.
Signal transduction typically displays a so-called bow-tie topology: Multiple receptors lead to multiple cellular responses but the signals all pass through a narrow waist of central signaling nodes. One such signaling node for several inflammatory and oncogenic signaling pathways is the CARD-CC/BCL10/MALT1 (CBM) complexes, which get activated by protein kinase C (PKC)-mediated phosphorylation of the caspase activation and recruitment domain (CARD)-coiled-coil domain (CC) component. In humans, there are four CARD-CC family proteins (CARD9, CARD10, CARD11, and CARD14) and 9 true PKC isozymes (α to ι). At this moment, less than a handful of PKC::CARD-CC relationships are known. In order to explore the biologically relevant combinatorial space out of all 36 potential permutations in this two-component signaling event, we made use of CARD10-deficient human embryonic kidney 293T cells for subsequent pairwise cotransfections of all CARD-CC family members and all activated PKCs. Upon analysis of NF-κB-dependent reporter gene expression, we could define specific PKC::CARD-CC relationships. Surprisingly, as many as 21 PKC::CARD-CC functional combinations were identified. CARD10 was responsive to most PKCs, while CARD14 was mainly activated by PKCδ. The CARD11 activation profile was most similar to that of CARD9. We also discovered the existence of mixed protein complexes between different CARD-CC proteins, which was shown to influence their PKC response profile. Finally, multiple PKCs were found to use a common phosphorylation site to activate CARD9, while additional phosphorylation sites contribute to CARD14 activation. Together, these data reveal the combinatorial space of PKC::CARD-CC signal transduction nodes, which will be valuable for future studies on the regulation of CBM signaling.
多个受体导致多种细胞反应，但所有信号都通过中央信号节点的狭窄腰部传递。几种炎症和致癌信号通路的一个这样的信号节点是 CARD-CC/BCL10/MALT1（CBM）复合物，它通过蛋白激酶 C（PKC）介导的半胱氨酸天冬氨酸蛋白酶激活和募集结构域（CARD）卷曲螺旋结构域（CC）成分的磷酸化而被激活。在人类中，有四种 CARD-CC 家族蛋白（CARD9、CARD10、CARD11 和 CARD14）和 9 种真正的 PKC 同工酶（α 到 ι）。目前，仅知道不到少数的 PKC::CARD-CC 关系。为了探索在这个双组分信号事件中的所有 36 种潜在排列组合中具有生物学相关性的组合空间，我们利用 CARD10 缺陷型人胚肾 293T 细胞进行随后的所有 CARD-CC 家族成员和所有激活的 PKC 的成对共转染。在分析 NF-κB 依赖性报告基因表达后，我们可以定义特定的 PKC::CARD-CC 关系。令人惊讶的是，鉴定出多达 21 种 PKC::CARD-CC 功能组合。CARD10 对大多数 PKC 有反应，而 CARD14 主要被 PKCδ激活。CARD11 的激活谱与 CARD9 的激活谱最相似。我们还发现不同 CARD-CC 蛋白之间存在混合蛋白复合物，这表明它们影响其 PKC 反应谱。最后，发现多个 PKC 使用共同的磷酸化位点激活 CARD9，而其他磷酸化位点有助于 CARD14 的激活。总之，这些数据揭示了 PKC::CARD-CC 信号转导节点的组合空间，这对于未来研究 CBM 信号转导的调节将非常有价值。
