Toll-like receptor 4 is a sensor for autophagy associated with innate immunity
Toll-like receptor 4 is a sensor for autophagy associated with innate immunity
Immunity 27, 135-144 (2007)
Speaker: 李婉綺 Place: Room 601
Commentator: 林以行 老師 Date: 07.11.2007
Abstract:
Under starvation conditions, cells degrade its own proteins and organelles in order to recycle the nutrient through the lysosomal machinery. This process is the most well known mechanism of autophagy. Autophagy is a newly recognized innate and adaptive immunity defense against intracellular pathogens. In the activation of innate immunity, Toll-like receptors (TLRs) play an essential role in the activation of innate immunity by recognizing specific patterns of microbial components. The patterns such as LPS or single strand viral RNA is recognized by TLR4 and TLR7 respectively. It has been revealed that TLR7 relays on autophagy to deliver viral constituents for the detection (Lee et al., 2007). In this study (Xu et al., 2007), TLR4 is shown to serve as a previously unrecognized sensor for autophagy. By applying lipopolysaccharide (LPS), autophagy was induced in both primary human alveolar macrophages and the murine macrophage RAW264.7 cell line. TLR4 has two signaling pathways: MyD88-dependent and MyD88-independent, it has been demonstrated that autophagy was regulated through a TRIF-dependent (TIR domain-containing adaptors), MyD88-independent signaling pathway followed by RIP1 and p38 MAPK downstream components. In addition, it is known that induction of autophagy is able to eliminate intracellular Mycobacterial tuberculosis (Gutierrez et al., 2004; Singh et al., 2006). The author further showed that LPS-induced autophagy could overcome the mycobacterial phagosome by promoting mycobacterial phagosome to colocalize with the autophagosomes. By sharing the same signaling pathway through TLR4, this study has discovered a new linkage between autophagy and innate immunity.
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4. Xu, Y., Jagannath, C., Liu, X.D., Sharafkhaneh, A., Kolodziejska, K. E. (2007). Toll-like receptor 4 is a sensor for autophagy associated with innate immunity. Immunity 27,135-144.