TRIF/TICAM1 and mitochondrial dynamics in the innate immune response

Fri, 08/26/2016 - 13:10

TRIF, also known as toll like receptor adaptor molecule 1 or TICAM1, is known for its role in invading foreign pathogens as part of our innate immune response. TRIF/TICAM1 is a TIR-domain adaptor protein (toll/interleukin-1 receptor) that interacts with the Toll-like receptors (TLRs) through intracellular signaling and recognition of its TIR site.  TLRs are expressed on a variety of cell types, including macrophages, mast cells, endothelial cells, and more.  In addition to TRIF/TICAM1, another universal adaptor for TLRs is myeloid differentiation factor-88 (MyD88).  The activation of both MyD88 and TRIF/TICAM1 results in subsequent activation of the nuclear factor kappa beta pathway (NF-κB). The NF-κB then influences a large range of biological processes, including immunity, inflammation and stress response.  One way that TRIF/TICAM1 defends a host from foreign pathogens is to initiate autophagy or apoptosis in order to clear the intracellular space from these particles.  Therefore, interaction of TRIF/TICAM1 with Beclin 1, a major promoter of autophagy localized to mitochondria is of interest. 

TRIF/TICAM1 antibody

TRIF/TICAM1 Antibody [NB120-13810] - TRIF antibody was tested in A431 cells with Dylight 488 (green). Nuclei and alpha-tubulin were counterstained with DAPI (blue) and Dylight 550 (red). Image objective 40x. An antibody dilution of 1:10 was used.

The first study using a TRIF/TICAM1 antibody sought out to determine the molecular behavior of Beclin 1 and TRIF/TICAM1.  As stated above, Beclin 1 is a major player in autophagy, and is the mammalian homologue of yeast Atg6 which helps to form the autophagosome complex via recruitment of the necessary proteins to the autophagosomal membrane.  To begin, Chong-Shan Shi et al established that TLR proteins induce autophagy in macrophages using an LC3 primary antibody to detect autophagosome formation. Subsequently, they also established the involvement of MyD88 and TRIF/TICAM1in the mediation of autophagosome formation via GFP-LC3 in RAW 264.7 cells.  In fact, they found that levels of GFP-LC3 increased to 70% in cells that expressed TRIF/TICAM1 or MyD88.  This finding mimicked the overexpression of Beclin 1 as well.  Next, using a TRIF/TICAM1 antibody in co-immunoprecipitation study, they determined that MyD88 and TRIF/TICAM1 modulated the interaction between Bcl2 and Beclin 1.  Their hypothesis concluded that Bcl2 inhibits TLR induced autophagy all together, or that MyD88 or TRIF/TICAM1 actually compete with Beclin-1 to interfere with autophagy by recruiting Beclin 1 to the TLR4 signaling complex. 

Microglia are additional members of the central nervous system that use pattern recognition to detect and expel foreign pathogens.  Typically, these immune responses are regulated by a nuclear factor of activated T-cells, or NFAT.  Bo Ma et al sought to discover if there was indeed an interaction between NFAT and the broad immune response elicited by TLRs.  Through immunofluorescent analysis and the use of primary antibodies, Bo Ma et al saw that increased LPS-induced NFAT1 induction correlated with the mitochondrial marker COXIV.  The obvious next question would be to determine the mechanism of the pathway that translocates NFAT to the mitochondria.  Using a TRIF/TICAM1 antibody they saw that translocation of NFAT into mitochondria was inhibited in TRIF/TICAM1 siRNA, however not with a knockout MyD88 approach.  Furthermore, downstream functions of TRIF were reduced after removal of NFAT1. 

Overall, using a TRIF/TICAM1 antibody as an experimental tool is proven in studying the localization, function, and possible pathways of action for TLR proteins and autophagic proteins in our innate immune response. 

Novus Biologicals offers TRIF/TICAM1 reagents for your research needs including:

PMID: 18772134
PMID: 26224862

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