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TRIM38 Negatively Regulates TLR3-Mediated IFN-beta Signaling by Targeting TRIF for Degradation

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posted on 26.11.2013 by Qinghua Xue, Zhuo Zhou, Xiaobo Lei, Xinlei Liu, Bin He, Jianwei Wang, Tao Hung
Toll-like receptors (TLRs) mediated immune response is crucial for combating pathogens and must be tightly controlled. Tripartite motif (TRIM) proteins are a family of proteins that is involved in a variety of biological and physiological processes. Some members of the TRIM family are important in the regulation of innate immunity. Although it has been shown that TRIM38 negatively regulates innate immunity, the mechanisms by which it does so have not been fully addressed. In this study, we demonstrated that TRIM38 negatively regulates Toll-like receptor 3 (TLR3)-mediated type I interferon signaling by targeting TIR domain-containing adaptor inducing IFN-b (TRIF). We found that overexpression of TRIM38 inhibits TLR3- mediated type I interferon signaling, whereas knockdown of TRIM38 has the reverse effects. We further showed that TRIM38 targets TRIF, a critical adaptor protein downstream of TLR3. TRIF is co-immunoprecipitated with TRIM38, and domain mapping experiments show that PRYSPRY of TRIM38 interacts with the N-terminus of TRIF. Overexpression of TRIM38 decreased expression of overexpressed and endogenous TRIF. This effect could be inhibited by MG132 treatment. Furthermore, the RING/B-box domain of TRIM38 is critical for K48-linked polyubiquitination and proteasomal degradation of TRIF. Collectively, our results suggest that TRIM38 may act as a novel negative regulator for TLR3-mediated type I interferon signaling by targeting TRIF for degradation.

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This work was supported by grants from the Chinese Ministry of Education Grant for New Century Talents (NCET-07-0506) (http://www.dost.moe.edu. cn) and the National Basic Research Program of China (973 Project, 2011CB504903) (http://www.973.gov.cn).

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© 2012 Xue et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The original version is available through Public Library of Science at DOI: 10.1371/journal.pone.0046825.

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Public Library of Science

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en_US

issn

1932-6203

Issue date

01/10/2012

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