Translocation of the IL-1 receptor to focal adhesions is regulated through the C-terminal end of the cytoplasmic domain

The mechanisms of translocation of the IL-1 receptor to focal adhesions were analysed using EGFP reporter constructs and confocal microscopy. In fibronectin-attached cells, the receptor fusion protein was present in distinct punctate areas, co-localizing with the transmembrane-linkage protein vinculin. In migrating cells, the two proteins co-localized at the leading edge in ruffle-like structures. Experiments using a series of receptor mutants revealed that translocation of the IL-1 receptor to focal adhesions was dependent on motifs conserved between members of the TIR family, in the C-terminal end of the receptor. Further, an enhanced level of expression of the wild-type receptor at attachment sites was shown to correlate with an increased severity of IL-1 induced structural effects. This report demonstrates that translocation of the IL-1 receptor to focal adhesions is dependent on conserved domains in the C-terminal end of the protein, and that receptor localization at these sites is important in structural regulation of IL-1 mediated responses.