Tamoxifen inducible protein kinase/phosphatase mutants – a new logic for reversible control of signaling pathways in vivo

The study of the function of signal transduction pathways requires control activity of a signalling protein in a temporal manner. Signalling processes undergo cycles of activation and repression, such that their manipulation into both directions is of experimental interest. This study is focused on the development and application of a new inducible and reversible switch to modulate the activity of signalling molecules at the protein level with the MAP Kinase (MAPK) pathway as a case study. This switch relied on the posttranslational activation of hyperactive or catalytic dead protein mutants fused with to ER^T2 mutant estrogen receptor ligand binding domain. In mice the ER^T2 technology is routinely applied to induce the activity of Cre recombinase by the synthetic inducer Tamoxifen. Here, by the use of a hyperactive B-RAF, a hyperactive DUSP1, a kinase-dead B-RAF or a wild type DUSP1 fused to the ER^T2domain, we demonstrate that it is possible to achieve the reversible enhancement or repression of an endogenous signalling pathway in mouse fibroblasts and adult mouse brain upon Tamoxifen induction.