Molecular cloning and functional characterization of murine toll‑like receptor 8

Li,Tingting; He,Xiaobing; Jia,Huaijie; Chen,Guohua; Zeng,Shuang; Fang,Yongxiang; Jin,Qiwang; Jing,Zhizhong

doi:10.3892/mmr.2015.4668

Molecular cloning and functional characterization of murine toll‑like receptor 8

Authors:
- Tingting Li
- Xiaobing He
- Huaijie Jia
- Guohua Chen
- Shuang Zeng
- Yongxiang Fang
- Qiwang Jin
- Zhizhong Jing
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Affiliations: State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Public Health of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu 730046, P.R. China
Published online on: December 10, 2015 https://doi.org/10.3892/mmr.2015.4668
Pages: 1119-1126
Copyright: © Li et al. This is an open access article distributed under the terms of Creative Commons Attribution License.

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Abstract

Toll‑like receptors (TLRs) are a large family of germ‑line encoded pattern recognition receptors (PRRs) that recognize pathogen‑associated molecular patterns and evoke the relevant innate immune responses. TLR8 is a member of several endosome nucleic acid‑sensing TLRs; however little attention has been paid to murine TLR8 (mTLR8) compared with other endosome nucleic acid‑sensing TLRs. In the present study, mTLR8 was cloned using reverse transcription‑polymerase chain reaction from murine peripheral blood mononuclear cells and its function in regulating innate immune response was characterized. The open reading frame of mTLR8 consists of 3,099 bps and encodes 1,032 amino acids. It contains typical leucine‑rich repeats, a transmembrane domain and a Toll/interleukin‑1 receptor domain, and it shares a high level of identity with other mammalian species. The expression of mTLR8 has been widely observed in different tissues, and higher expression levels of mTLR8 have mainly been detected in the heart, spleen and lung. Overexpression of mTLR8 is required for the activation of transcription factor nuclear factor‑κB and the production of tumor necrosis factor‑α. However, mTLR8 is not able to activate interferon regulatory factor 3 or activator protein 1, nor can it induce interferon‑α in HEK293T cells. These results indicate that mTLR8, as an important PRR, is indeed functional and is vital role in the activation of innate immune responses. This study may aid in determining the molecular basis of the interactions between mTLR8 and pathogens.

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