Polyubiquitin-dependent recruitment of NEMO/IKKγ into T cell receptor signaling microclusters

The NF-κB essential modulator protein (NEMO) is required for activation of canonical NF-κB by the T cell antigen receptor (TCR). However, the subcellular localization of NEMO during this process is not well understood. By dynamically imaging fluorescent NEMO chimeras in live human T cells, we demonstrate that NEMO is rapidly recruited into TCR microclusters via domains previously implicated in the recognition of linear and K63-linked polyubiquitin. The recruitment of NEMO into TCR microclusters requires the activities of the tyrosine kinases Lck and ZAP-70, but not the adaptor proteins LAT or SLP-76. Thus, our findings reveal that the pathways leading from TCR to NF-κB bifurcate downstream of ZAP-70 to independently control the recruitment and activation of NEMO.