Trif-related adapter molecule is phosphorylated by PKC{epsilon} during Toll-like receptor 4 signaling.
PKCepsilon has been shown to play a key role in the effect of the Gram-negative bacterial product LPS; however, the target for PKCepsilon in LPS signaling is unknown. LPS signaling is mediated by Toll-like receptor 4, which uses four adapter proteins, MyD88, MyD88 adapter-like (Mal), Toll/IL-1R domain-containing adapter inducing IFN-beta (Trif), and Trif-related adapter molecule (TRAM). Here we show that TRAM is transiently phosphorylated by PKCepsilon on serine-16 in an LPS-dependent manner. Activation of IFN regulatory factor 3 and induction of the chemokine RANTES, which are both TRAM-dependent, were attenuated in PKCepsilon-deficient cells. TRAMS16A is inactive when overexpressed and is attenuated in its ability to reconstitute signaling in TRAM-deficient cells. We have therefore uncovered a key process in Toll-like receptor 4 signaling, identifying TRAM as the target for PKCepsilon.
McGettrick
Anne F
AF
School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland.
Brint
Elizabeth K
EK
Palsson-McDermott
Eva M
EM
Rowe
Daniel C
DC
Golenbock
Douglas T
DT
Gay
Nicholas J
NJ
Fitzgerald
Katherine A
KA
O'Neill
Luke A J
LA
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D051744:Protein Kinase C-epsilon / Q000235:genetics / Q000378:metabolism*; D018123:Receptors, Interleukin / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D007527:Isoenzymes; D008070:Lipopolysaccharides; D051744:Protein Kinase C-epsilon; D018123:Receptors, Interleukin; D011993:Recombinant Fusion Proteins; D051197:Toll-Like Receptor 4; C476286:Ticam1 protein, mouse; C476416:Ticam2 protein, mouse; C493487:Tlr4 protein, mouse