The LUBAC participates in lysophosphatidic acid-induced NF-κB activation

• Published in: Cellular immunology 2020-07, Vol.353, p.104133-104133, Article 104133
• Main Authors: Douanne, Tiphaine, Chapelier, Sarah, Rottapel, Robert, Gavard, Julie, Bidère, Nicolas
• Format: Article
• Language: English
• Subjects: Animals; B-Cell CLL-Lymphoma 10 Protein - metabolism; CARD Signaling Adaptor Proteins - metabolism; CBM complex; Cell Culture Techniques; Cellular Biology; Fibroblasts - metabolism; GEF-H1; Glycerophospholipids - metabolism; HEK293 Cells; Humans; Intracellular Signaling Peptides and Proteins - metabolism; Life Sciences; LPA; LUBAC; Lysophospholipids - metabolism; Lysophospholipids - pharmacology; MALT1; Mice; Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein - metabolism; Multiprotein Complexes - metabolism; NF-kappa B - metabolism; NF-κB; Receptors, G-Protein-Coupled - metabolism; Signal Transduction - physiology; Ubiquitin - metabolism; Ubiquitin-Protein Ligases - metabolism; Ubiquitination
• ISSN: 0008-8749; 1090-2163
• DOI: 10.1016/j.cellimm.2020.104133

•Activation of NF-κB by the GPCR ligand LPA requires the LUBAC in mouse embryonic fibroblasts.•LPA drives MALT1-mediated cleavage of the LUBAC subunit HOIL1 to allow optimal signaling.•The guanine exchange factor GEF-H1 promotes HOIL1 proteolysis and NF-κB activation. 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.