Activation of NF-κB signalling by fusicoccin-induced dimerization.

Chemically induced dimerization is an important tool in chemical biology for the analysis of protein function in cells. Here we report the use of the natural product fusicoccin (FC) to induce dimerization of 14-3-3-fused target proteins with proteins tagged to the C terminus (CT) of the H(+)-ATPase PMA2. To prevent nonproductive or detrimental interactions of the 14-3-3 proteins and CT fusions with endogenous cell proteins, their interaction surface was engineered to facilitate FC-induced dimerization exclusively between the introduced protein constructs. Live-cell imaging documented the reversible FC-induced translocation of 14-3-3 and CT to different cell compartments depending on localization sequences fused to their dimerization partner protein. The functionality of this system was demonstrated by the FC-induced importation of the NF-κB-CT into the nucleus. In HeLa cells, FC-mediated dimerization of the NF-κB-CT with a constitutively nuclear-localized 14-3-3 protein led to an NF-κB-specific cellular response by inducing IL-8 secretion.