E3 ligase RNF99 negatively regulates TLR-mediated inflammatory immune response via K48-linked ubiquitination of TAB2
E3 ligase RNF99 negatively regulates TLR-mediated inflammatory immune response via K48-linked ubiquitination of TAB2
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DOI：
10.1038/s41418-023-01115-2
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发表时间：
2023-01
影响因子：
12.4
通讯作者：
Jie Zhang;Lei Cao;Amy Gao;Ruiqing Ren;Liwen Yu;Qian Li;Ya-peng Liu;Wenqian Qi;Yonghao Hou;Wenhai Sui;G. Su;Yun Zhang;Cheng Zhang;Meng Zhang
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文献类型：
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作者：
Jie Zhang;Lei Cao;Amy Gao;Ruiqing Ren;Liwen Yu;Qian Li;Ya-peng Liu;Wenqian Qi;Yonghao Hou;Wenhai Sui;G. Su;Yun Zhang;Cheng Zhang;Meng Zhang
先天免疫是抵御病原微生物的第一道防线，toll样受体（TLR）介导的炎症反应是先天免疫的重要组成部分。然而，tlr在先天免疫中的调控机制尚不完善。我们发现，在感染革兰氏阴性菌（G-）的患者外周血单核细胞和TLRs配体刺激的巨噬细胞中，E3连接酶环指蛋白99 （RNF99）的表达显著降低，提示RNF99的作用。我们还首次通过RNF99敲除小鼠（RNF99 - / -）和骨髓移植小鼠，证明了RNF99对lps诱导的脓毒性休克和葡聚糖硫酸钠（DSS）诱导的结肠炎的保护作用。体外实验显示，RNF99缺失显著促进巨噬细胞tlr介导的炎症细胞因子表达，激活NF-κB和MAPK通路。机制上，在TLR4稳定转染的巨噬细胞和HEK293细胞系中，RNF99通过TAB2赖氨酸611上的赖氨酸(K)48连接的泛素-蛋白酶体途径，与TAK1激酶的调节蛋白TAK1结合蛋白（TAB） 2相互作用并降解，进一步调节tlr介导的炎症反应。综上所述，这些发现表明巨噬细胞中RNF99在调节tlr介导的炎症反应中的生理意义。它为TLRs信号转导提供了新的认识，并为预防细菌感染、内毒素休克和其他炎症疾病提供了新的途径。
Innate immunity is the first line to defend against pathogenic microorganisms, and Toll-like receptor (TLR)-mediated inflammatory responses are an essential component of innate immunity. However, the regulatory mechanisms of TLRs in innate immunity remain unperfected. We found that the expression of E3 ligase Ring finger protein 99 (RNF99) decreased significantly in peripheral blood monocytes from patients infected with Gram negative bacteria (G-) and macrophages stimulated by TLRs ligands, indicating the role of RNF99. We also demonstrated for the first time, the protective role of RNF99 against LPS-induced septic shock and dextran sodium sulfate (DSS)-induced colitis using RNF99 knockout mice (RNF99–/–) and bone marrow-transplanted mice. In vitro experiments revealed that RNF99 deficiency significantly promoted TLR-mediated inflammatory cytokine expression and activated the NF-κB and MAPK pathways in macrophages. Mechanistically, in both macrophages and HEK293 cell line with TLR4 stably transfection, RNF99 interacted with and degraded TAK1-binding protein (TAB) 2, a regulatory protein of the kinase TAK1, via the lysine (K)48-linked ubiquitin-proteasomal pathway on lysine 611 of TAB2, which further regulated the TLR-mediated inflammatory response. Overall, these findings indicated the physiological significance of RNF99 in macrophages in regulating TLR-mediated inflammatory reactions. It provided new insight into TLRs signal transduction, and offered a novel approach for preventing bacterial infections, endotoxin shock, and other inflammatory ills.