摘要
Tripartite motif-containing protein 27 (TRIM27/also called RFP) is a multifunctional ubiquitin E3 ligase involved in numerous cellular functions, such as proliferation, apoptosis, regulation of the NF-kB pathway, endosomal recycling and the innate immune response. TRIM27 interacts directly with TANK-binding kinase 1 (TBK1) and regulates its stability. TBK1 in complex with autophagy receptors is recruited to ubiquitin chains assembled on the mitochondrial outer membrane promoting mitophagy. Here, we identify TRIM27 as an autophagy substrate, depending on ATG7, ATG9 and autophagy receptors for its lysosomal degradation. We show that TRIM27 forms ubiquitylated cytoplasmic bodies that co-localize with autophagy receptors. Surprisingly, we observed that induced expression of EGFP-TRIM27 in HEK293 FlpIn TRIM27 knockout cells mediates mitochondrial clustering. TRIM27 interacts with autophagy receptor SQSTM1/p62, and the TRIM27-mediated mitochondrial clustering is facilitated by SQSTM/p62. We show that phosphorylated TBK1 is recruited to the clustered mitochondria. Moreover, induced mitophagy activity is reduced in HEK293 FlpIn TRIM27 knockout cells, while re-introduction of EGFP-TRIM27 completely restores the mitophagy activity. Inhibition of TBK1 reduces mitophagy in HEK293 FlpIn cells and in the reconstituted EGFP-TRIM27-expressing cells, but not in HEK293 FlpIn TRIM27 knockout cells. Altogether, these data reveal novel roles for TRIM27 in mitophagy, facilitating mitochondrial clustering via SQSTM1/p62 and mitophagy via stabilization of phosphorylated TBK1 on mitochondria.
摘要译文
含三方基序的蛋白27（TRIM27/也称为RFP）是一种多功能的泛素E3连接酶，参与了许多细胞功能，例如增殖，凋亡，NF-KB途径的调节，内体回收和固有免疫反应。TRIM27与储罐结合激酶1（TBK1）直接相互作用，并调节其稳定性。与自噬受体复合物中的TBK1被募集到聚集在促进线粒体的线粒体外膜上的泛素链中。在这里，我们将TRIM27识别为自噬底物，具体取决于ATG7，ATG9和自噬受体的溶酶体降解。我们表明，TRIM27形成了与自噬受体共定位的泛素化细胞质体。令人惊讶的是，我们观察到HEK293 FLPIN TRIM27基因敲除细胞诱导EGFP-TRIM27的表达介导了线粒体聚类。TRIM27与自噬受体SQSTM1/p62相互作用，并且SQSTM/p62促进了TRIM27介导的线粒体聚类。我们表明，将磷酸化的TBK1募集到簇的线粒体。此外，在HEK293 FLPIN TRIM27敲除细胞中诱导的线粒能活性降低，而EGFP-TRIM27的重新引入完全恢复了线粒体活性。TBK1的抑制可降低HEK293 FLPIN细胞中的线粒体和重组的EGFP-TRIM27表达细胞，但在HEK293 FLPIN TRIM27敲除细胞中却不会发生线粒体。总的来说，这些数据揭示了TRIM27在线粒体中的新作用，通过SQSTM1/P62促进线粒体聚类，并通过稳定线粒体上的磷酸化TBK1稳定线粒体。
Juncal Garcia-Garcia[1];Anne Kristin McLaren Berge[1];Katrine Stange Overå[1];Kenneth Bowitz Larsen[1];Zambarlal Bhujabal[1];Andreas Brech[2];Yakubu Princely Abudu[1];Trond Lamark[1];Terje Johansen[1];Eva Sjøttem[1]. TRIM27 is an autophagy substrate facilitating mitochondria clustering and mitophagy via phosphorylated TBK1[J]. FEBS Journal, 2023,290(4): 1096-1116