Previously we have shown that human serum- and glucocorticoid- inducible kinase SGK promotes cell survival in phosphorylating and inactivating the forkhead transcription factor FOXO in cell culture (Brunet et al., 2001). Recently, it has been shown that the C.elegans serum- and glucocorticoid-inducible kinase SGK-1 acts in the DAF-2 insulin signaling pathway converging on the transcription factor DAF-16/ FOXO and constitutes to the control of longevity and stress response (Hertweck et al., 2004). Now, we want to understand the dynamics of SGK-1 in controlling development, stress response and life-span. To identify inputs and outputs of
sgk-1 for pathways in which
sgk-1 is involved, we performed a split-ubiquitin yeast two hybrid interactor screen with human SGK1 against a human cDNA library. The advantage of this approach compared to the classical yeast two hybrid interactor screen is the detection of proteins present not only in the nucleus, but also for those originating from organelles, cytoplasma and membranes.The screen was repeated two times and yielded interactors from several cellular pathways, including endocytosis, apoptosis and protein folding stability under stress conditions. We have chosen to investigate the four most interesting ones. First, we are validating the physical relationship of human SGK1 and its interactors in vitro. Second, we plan to approach the genetic interaction of C.elegans SGK-1 and the C.elegans homologs of the identified interactors using deletion mutants and RNAi mutants.