Bacterial CpG-DNA and lipopolysaccharides activate Toll-like receptors at distinct cellular compartments.
TLDR
The need to characterize individual TLR at the very beginning of signal initiation in order to understand their diverse biological functions is stressed.Abstract:
Recognition by innate immune cells of the pathogen associated molecular patterns (PAMP) lipopolysaccharide (LPS) from Gram-negative bacteria and bacterial CpG-DNA depends on Toll-like receptor4 (TLR4) and TLR9, respectively. To define differences in the response to these distinct PAMP we compared a key intracellular event, namely recruitment of myeloid differentiation marker 88 (MyD88) to the respective PAMP-initiated TLR signaling. Using MyD88-GFP fusion protein expressing macrophages we demonstrate that LPS and CpG-DNA trigger signaling from two different cellular locations: theformer at the cell membrane and the latter at the lysosomal compartment. While LPS does not require endocytosis to functionally associate with the membrane expressed TLR4/MD2 complex, internalization and endosomal maturation is conditional for CpG-DNA to activate TLR9. In support of these data TLR9 is not localized at the cell surface, but intracellularily. These data stress the need to characterize individual TLR at the very beginning of signal initiation in order to understand their diverse biological functions.read more
Citations
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References
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Defective LPS Signaling in C3H/HeJ and C57BL/10ScCr Mice: Mutations in Tlr4 Gene
Alexander Poltorak,Xiaolong He,Irina Smirnova,Mu Ya Liu,Christophe Van Huffel,Xin Du,Dale Birdwell,E. Alejos,M. Silva,Chris Galanos,Marina Freudenberg,Paola Ricciardi-Castagnoli,Betsy Layton,Bruce Beutler +13 more
TL;DR: The mammalian Tlr4 protein has been adapted primarily to subserve the recognition of LPS and presumably transduces the LPS signal across the plasma membrane.
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Defective LPS signaling in C3 H/HeJ and C57 BL/10 ScCr mice: Mutations in Tlr4 Gene
Alexander Poltorak,Xiaolong He,Irina Smirnova,Mu Ya Liu,C. Van Huffel,Xin Du,Dale Birdwell,E. Alejos,M. Suva,Chris Galanos,Marina Freudenberg,Paola Ricciardi-Castagnoli,B. Layton,Bruce Beutler +13 more
Journal ArticleDOI
A Toll-like receptor recognizes bacterial DNA.
Hiroaki Hemmi,Osamu Takeuchi,Taro Kawai,Tsuneyasu Kaisho,Shintaro Sato,Hideki Sanjo,Makoto Matsumoto,Katsuaki Hoshino,Hermann Wagner,Kiyoshi Takeda,Shizuo Akira +10 more
TL;DR: It is shown that cellular response to CpG DNA is mediated by a Toll-like receptor, TLR9, and vertebrate immune systems appear to have evolved a specific Toll- like receptor that distinguishes bacterial DNA from self-DNA.
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A human homologue of the Drosophila Toll protein signals activation of adaptive immunity
TL;DR: The cloning and characterization of a human homologue of the Drosophila toll protein (Toll) is reported, which has been shown to induce the innate immune response in adult Dosophila.
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The innate immune response to bacterial flagellin is mediated by Toll-like receptor 5.
Fumitaka Hayashi,Kelly D. Smith,Adrian Ozinsky,Thomas R. Hawn,Thomas R. Hawn,Eugene C. Yi,David R. Goodlett,Jimmy K. Eng,Shizuo Akira,David M. Underhill,Alan Aderem +10 more
TL;DR: It is reported that mammalian TLR5 recognizes bacterial flagellin from both Gram-positive and Gram-negative bacteria, and that activation of the receptor mobilizes the nuclear factor NF-κB and stimulates tumour necrosis factor-α production, and the data suggest thatTLR5, a member of the evolutionarily conserved Toll-like receptor family, has evolved to permit mammals specifically to detect flageLLated bacterial pathogens.