Strain Detail: Balb/c.lox-tdKeima-PKAchu mice

The Balb/c.lox-tdKeima-PKAchu mice are congenic mice of lox-PKAchu mice (nbio208) with the BALB/c genetic background. The Balb/c.lox-tdKeima-PKAchu mice are transgenic mice expressing the probe which consists of cytoplasm-localized förster (or fluorescence) resonance energy transfer (FRET) biosensor monitoring PKA kinase activity with lox-tdKeima. Protein kinases A (PKA, also known as the cyclic AMP-dependent protein kinases) are activated by the elevated intracellular cAMP in response to stimuli from hormone or bioactive substance, and relay signal transductions from hormones. This strain expresses Keima fluorescent protein under the control of CAG promoter in almost all tissues. Mating with tissue-specific Cre-expressed mice induces tissue-specific switching in the expression from Keima fluorescent proteins to FRET biosensors. With the biosensor, PKA kinase activity can be measured spatially and temporally in various fetal and adult tissues by the live-image observation of this strain under the two-photon microscopy. This strain is useful not only for analyses of the signal transduction cascade in live animals, but also for drug development such as the pharmacodynamic analysis targeting signal molecules, because these mice show rich expression in primary cultured cells derived from various tissues. In the developmental stage, biosensor expression was observable in most cells. FRET biosensors are not applicable for fixed samples.