The natural bioactive glycerophospholipid lysophosphatidic acid (LPA) binds to its cognate G protein-coupled receptors (GPCRs) on the cell surface to promote the activation of several transcription factors, including NF-κB. LPA-mediated activation of NF-κB relies on the formation of a signalosome that contains the scaffold CARMA3, the adaptor BCL10 and the paracaspase MALT1 (CBM complex). The CBM complex has been extensively studied in lymphocytes, where it links antigen receptors to NF-κB activation via the recruitment of the linear ubiquitin assembly complex (LUBAC), a tripartite complex of HOIP, HOIL1 and SHARPIN. Moreover, MALT1 cleaves the LUBAC subunit HOIL1 to further enhance NF-κB activation. However, the contribution of the LUBAC downstream of GPCRs has not been investigated. By using murine embryonic fibroblasts from mice deficient for HOIP, HOIL1 and SHARPIN, we report that the LUBAC is crucial for the activation of NF-κB in response to LPA. Further echoing the situation in lymphocytes, LPA unbridles the protease activity of MALT1, which cleaves HOIL1 at the Arginine 165. The expression of a MALT1-insensitive version of HOIL1 reveals that this processing is involved in the optimal production of the NF-κB target cytokine interleukin-6. Lastly, we provide evidence that the guanine exchange factor GEF-H1 favors MALT1-mediated cleavage of HOIL1 and NF-κB signaling in this context. Together, our results unveil a critical role for the LUBAC as a positive regulator of NF-κB signaling downstream of LPA receptors.

天然的生物活性甘油磷脂溶血磷脂酸（LPA）与细胞表面的相关G蛋白偶联受体（GPCR）结合，从而促进包括NF-κB在内的多种转录因子的激活。LPA介导的NF-κB活化依赖于包含支架CARMA3，衔接子BCL10和半胱天冬酶MALT1（CBM复合物）的信号小体的形成。CBM复合物已在淋巴细胞中进行了广泛的研究，其中通过募集线性泛素装配复合物（LUBAC），HOIP，HOIL1和SHARPIN的三重复合物，将抗原受体与NF-κB活化联系起来。此外，MALT1切割LUBAC亚基HOIL1以进一步增强NF-κB激活。但是，尚未调查LUBAC在GPCR下游的贡献。通过使用来自小鼠的HOIP，HOIL1和SHARPIN缺陷的小鼠胚胎成纤维细胞，我们报道LUBAC对于响应LPA激活NF-κB至关重要。LPA进一步激化了淋巴细胞的情况，它解散了MALT1的蛋白酶活性，该酶在精氨酸165处裂解HOIL1。MALT1不敏感的HOIL1版本的表达表明该过程与NF-κB目标细胞因子的最佳产生有关。白介素-6。最后，我们提供证据表明鸟嘌呤交换因子GEF-H1在这种情况下有利于MALT1介导的HOIL1和NF-κB信号的裂解。总之，我们的结果揭示了LUBAC作为LPA受体下游的NF-κB信号转导的正调节剂的关键作用。LPA进一步激化了淋巴细胞的情况，它解散了MALT1的蛋白酶活性，该酶在精氨酸165处裂解HOIL1。MALT1不敏感的HOIL1版本的表达表明该过程与NF-κB目标细胞因子的最佳产生有关。白介素-6。最后，我们提供证据表明鸟嘌呤交换因子GEF-H1在这种情况下有利于MALT1介导的HOIL1和NF-κB信号的裂解。总之，我们的结果揭示了LUBAC作为LPA受体下游的NF-κB信号转导的正调节剂的关键作用。LPA进一步激化了淋巴细胞的情况，它解散了MALT1的蛋白酶活性，该酶在精氨酸165处裂解HOIL1。MALT1不敏感的HOIL1版本的表达表明该过程与NF-κB目标细胞因子的最佳产生有关。白介素-6。最后，我们提供证据表明鸟嘌呤交换因子GEF-H1在这种情况下有利于MALT1介导的HOIL1和NF-κB信号的裂解。总之，我们的结果揭示了LUBAC作为LPA受体下游的NF-κB信号转导的正调节剂的关键作用。MALT1不敏感的HOIL1版本的表达表明该过程与NF-κB目标细胞因子白介素6的最佳产生有关。最后，我们提供证据表明鸟嘌呤交换因子GEF-H1在这种情况下有利于MALT1介导的HOIL1和NF-κB信号的裂解。总之，我们的结果揭示了LUBAC作为LPA受体下游的NF-κB信号转导的正调节剂的关键作用。MALT1不敏感的HOIL1版本的表达表明该过程与NF-κB目标细胞因子白介素6的最佳产生有关。最后，我们提供证据表明鸟嘌呤交换因子GEF-H1在这种情况下有利于MALT1介导的HOIL1和NF-κB信号的裂解。总之，我们的结果揭示了LUBAC作为LPA受体下游的NF-κB信号转导的正调节剂的关键作用。