Strain Detail: lox-S6K mice

The lox-S6K mice are transgenic mice expressing a probe containing lox-tdKeima and förster (or fluorescence) resonance energy transfer (FRET) biosensor Eevee-S6K for monitoring S6K activity. S6K (ribosomal protein S6 kinase) is a protein kinase, which phosphorylates ribosomal protein S6. In a downstream of PI3 kinase, S6K is activated by the phosphorylation by mTOR complex 1 and promotes translation, involving the regulation of cell cycles and protein synthesis. With this strain, S6K activity can be measured spatially and temporally in various tissues of fetuses and adults by live image observation of this strain under the two-photon microscopy. This strain is useful not only for analysis of the signal transduction cascade in live animals, but also for the application of drug development, such as the pharmacodynamic analysis targeting signal molecules, because rich expression of FRET biosensors can be observed even in primary cultured cells derived from various tissues.