Double knockin mice show NF-κB trajectories in immune signaling and aging
Shah Md Toufiqur Rahman, Mohammad Aqdas, Erik W. Martin, Francesco Tomassoni‐Ardori, Preeyaporn Songkiatisak, Kyu‐Seon Oh, Stefan Uderhardt, Sangwon Yun, Quia Claybourne, Ross A. McDevitt, Valentina Greco, Ronald N. Germain, Lino Tessarollo, Myong‐Hee Sung
Abstract
In vitro studies suggest that mapping the spatiotemporal complexity of nuclear factor κB (NF-κB) signaling is essential to understanding its function. The lack of tools to directly monitor NF-κB proteins in vivo has hindered such efforts. Here, we introduce reporter mice with the endogenous RelA (p65) or c-Rel labeled with distinct fluorescent proteins and a double knockin with both subunits labeled. Overcoming hurdles in simultaneous live-cell imaging of RelA and c-Rel, we show that quantitative features of signaling reflect the identity of activating ligands, differ between primary and immortalized cells, and shift toward c-Rel in microglia from aged brains. RelA:c-Rel heterodimer is unexpectedly depleted in the nuclei of stimulated cells. Trajectories of subunit co-expression in immune lineages reveal a reduction at key cell maturation stages. These results demonstrate the power of these reporters in gaining deeper insights into NF-κB biology, with the spectral complementarity of the labeled NF-κB proteins enabling diverse applications.