A Cre-dependent reporter mouse for quantitative real-time imaging of Protein Kinase A activity dynamics.

Intracellular signaling dynamics play a crucial role in cell function. Protein kinase A (PKA) is a key signaling molecule that has diverse functions, from regulating metabolism and brain activity to guiding development and cancer progression. We previously developed an optical reporter, FLIM-AKAR, that allows for quantitative imaging of PKA activity via fluorescence lifetime imaging microscopy and photometry. However, using viral infection or electroporation for the delivery of FLIM-AKAR is invasive, cannot easily target sparse or hard-to-transfect/infect cell types, and results in variable expression. Here, we developed a reporter mouse, , which expresses FLIM-AKAR in a -dependent manner from the locus. provides robust and consistent expression of FLIM-AKAR over time. Functionally, the mouse line reports an increase in PKA activity in response to activation of both G and G-coupled receptors in brain slices. , reports PKA phosphorylation in response to neuromodulator receptor activation. Thus, provides a quantitative, robust, and flexible method to reveal the dynamics of PKA activity in diverse cell types.