Investigating the TLR3 Signaling Dynamics
Along with TLR-7, -8, and -9, TLR3 is an intracellular member of the Toll-like receptor (TLR) superfamily (see Chap. 3). It plays a crucial role in the mammalian innate immune response against viral attacks by recognizing double-stranded RNA (dsRNA) or its synthetic analogue polyinosinic-polycytidylic acid (poly (I:C)). TLR3 is expressed in several cell types including macrophages, murine embryonic fibroblasts (MEFs), and dendritic cells; however, it has not been detected in B cells, T cells, and NK cells. In contrast to all other TLRs, the TLR3 response is independent of the adaptor protein MyD88. The specificity of the TLR3 response possibly results from the occurrence of an alanine residue in a critical region of its cytoplasmic domain, in contrast to the proline residue utilized by MyD88 found in other TLRs. Thus, TLR3 initiates its response depending only on the adaptor protein TRIF and does not involve TRAM.
KeywordsProline Interferon Alanine TRIL
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