Department of Molecular Cell Biology and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, South Korea.
Division of Rheumatology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA, United States.
Front Immunol. 2019 Sep 18;10:2203. doi: 10.3389/fimmu.2019.02203. eCollection 2019.
Cereblon (CRBN) as a multifunctional protein has been extensively studied. Here, we show that CRBN is a negative regulator of bactericidal activity and autophagy activation. Mitochondrial localization of CRBN was significantly increased in response to Toll-like receptor 4 (TLR4) stimulation. CRBN interrupted the association of evolutionarily conserved signaling intermediate in Toll pathways (ECSIT)-TNF-receptor associated factor 6 (TRAF6) complex, thereby inhibiting the ubiquitination of ECSIT, which plays a pivotal role for the production of mitochondrial reactive oxygen species (mROS). Subsequently, mROS levels were markedly elevated in CRBN-knockdown (CRBN) THP-1 cells, and that led to resistance against S. typhimurium infection, indicating CRBN is a negative regulator of bactericidal activity through the regulation of mROS. Additionally, CRBN inhibited TRAF6-induced ubiquitination of BECN1 (Beclin 1), and that induced autophagy activation in CRBN THP-1, CRBN-knockout (CRBN) H1299, and CRBN MCF7 cancer cells in response to TLR4 stimulation. Notably, we found that the ability of cancer migration and invasion was significantly enhanced in CRBN H1299 and CRBN MCF7 cancer cells, as compared with those of control cancer cells. Collectively, these results suggest that CRBN is a negative regulator of bactericidal activity and autophagy activation through inhibiting the TRAF6-induced ubiquitination of ECSIT and BECN1, respectively.
cereblon (CRBN) 作为一种多功能蛋白，已得到广泛研究。在这里，我们表明 CRBN 是杀菌活性和自噬激活的负调节剂。在对 Toll 样受体 4 (TLR4) 刺激的反应中，CRBN 的线粒体定位显著增加。CRBN 中断了进化保守的 Toll 途径信号中间体 (ECSIT)-TNF 受体相关因子 6 (TRAF6) 复合物的关联，从而抑制 ECSIT 的泛素化，这对线粒体活性氧物质 (mROS) 的产生起着关键作用。随后，CRBN 敲低 (CRBN) THP-1 细胞中的 mROS 水平显著升高，导致对 S. typhimurium 感染的抗性增加，表明 CRBN 通过调节 mROS 作为杀菌活性的负调节剂。此外，CRBN 抑制了 TRAF6 诱导的 BECN1（Beclin 1）泛素化，并且在 CRBN THP-1、CRBN 敲除 (CRBN) H1299 和 CRBN MCF7 癌细胞中，在 TLR4 刺激下诱导自噬激活。值得注意的是，我们发现 CRBN H1299 和 CRBN MCF7 癌细胞的癌症迁移和侵袭能力明显增强，与对照癌细胞相比。总之，这些结果表明，CRBN 通过分别抑制 TRAF6 诱导的 ECSIT 和 BECN1 的泛素化，作为杀菌活性和自噬激活的负调节剂。
