Institute of Molecular Medicine and Cell Research, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-University of Freiburg, 79104 Freiburg, Germany; University of Freiburg, Faculty of Biology, 79104 Freiburg, Germany.
Institute of Molecular Immunology and Experimental Oncology, TUM School of Medicine, Technical University of Munich, 81675 Munich, Germany.
Cell Rep. 2023 Jan 31;42(1):111961. doi: 10.1016/j.celrep.2022.111961. Epub 2023 Jan 12.
SPATA2 mediates the recruitment of CYLD to immune receptor complexes by bridging the interaction of CYLD with the linear ubiquitylation assembly complex (LUBAC) component HOIP. Whether SPATA2 exhibits functions independently of CYLD is unclear. Here, we show that, while Cyld and Spata2 mice are viable, double mutants exhibit highly penetrant perinatal lethality, indicating independent functions of SPATA2 and CYLD. CyldSpata2 fibroblasts show increased M1-linked TNFR1-SC ubiquitylation and, similar to CyldSpata2 macrophages and intestinal epithelial cells, elevated pro-inflammatory gene expression compared with Cyld or Spata2 cells. We show that SPATA2 competes with OTULIN for binding to HOIP via its PUB-interacting motif (PIM) and its zinc finger domain, thereby promoting autoubiquitylation of LUBAC. Consistently, increased pro-inflammatory signaling in CyldSpata2 cells depends on the presence of OTULIN. Our data therefore indicate that SPATA2 counteracts, independently of CYLD, the deubiquitylation of LUBAC by OTULIN and thereby attenuates LUBAC activity and pro-inflammatory signaling.
SPATA2 通过桥接 CYLD 与线性泛素连接酶组装复合物（LUBAC）成分 HOIP 的相互作用，介导 CYLD 募集到免疫受体复合物。SPATA2 是否独立于 CYLD 发挥功能尚不清楚。在这里，我们表明，虽然 Cyld 和 Spata2 小鼠具有活力，但双突变体表现出高度外显的围产期致死性，表明 SPATA2 和 CYLD 具有独立的功能。CyldSpata2 成纤维细胞显示出增加的 M1 连接的 TNFR1-SC 泛素化，并且与 CyldSpata2 巨噬细胞和肠上皮细胞类似，与 Cyld 或 Spata2 细胞相比，促炎基因表达升高。我们表明，SPATA2 通过其 PUB 相互作用基序（PIM）和锌指结构域与 OTULIN 竞争结合 HOIP，从而促进 LUBAC 的自泛素化。一致地，CyldSpata2 细胞中增加的促炎信号取决于 OTULIN 的存在。因此，我们的数据表明，SPATA2 独立于 CYLD 拮抗 OTULIN 对 LUBAC 的去泛素化作用，从而减弱 LUBAC 活性和促炎信号。
