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Updated: Jul 6, 2026
Visualizing Protein Kinase A Activity In Head-fixed Behaving Mice Using In Vivo Two-photon Fluorescence Lifetime Imaging Microscopy
Published on: June 7, 2019
Noninvasive in vivo imaging of protein kinase A activity
Jan Øivind Moskaug1, Harald Carlsen, Rune Blomhoff
1Department of Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway. j.o.moskaug@medisin.uio.no
Abstract:
Protein kinases play pivotal roles in almost all cellular signaling pathways, and modulation of their activity is desirable in both disease and studies of function. Information on the activity of kinases in vivo is scarce owing to a lack of appropriate methods. To obtain such information, we produced mice in which protein kinase A (PKA) activity can be monitored noninvasively in vivo. The model uses luciferase, which has been mutated to contain a target sequence of PKA, thus making luminescence from the enzyme dependent on its state of phosphorylation. The PKA-sensitive luciferase, termed luciferase(PKA), was incorporated into the mouse genome, and transgenic animals exhibited a rapid beta-adrenergic response, that is, reduced luminescence, in various organs, including the pancreas, muscle, liver, and fat, after isoproterenol injection. This study shows that luciferase can be used for in vivo measurements of kinase activity, suggesting that different kinase target sequences in luciferase can monitor kinase activity modulation.
Insights
Researchers developed a novel method to monitor protein kinase A (PKA) activity in living mice. This new model uses a modified luciferase enzyme to track PKA signaling noninvasively, offering insights into cellular pathways.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Protein kinases are crucial regulators of cellular signaling pathways, implicated in numerous physiological and pathological processes.
- Current methods for assessing kinase activity in vivo are limited, hindering a comprehensive understanding of their dynamic roles.
- Protein Kinase A (PKA) is a key enzyme in various signaling cascades, but its real-time activity in living organisms remains challenging to measure.
Purpose of the Study:
- To develop a noninvasive in vivo method for monitoring protein kinase A (PKA) activity.
- To create a transgenic mouse model that allows for real-time visualization of PKA signaling.
- To demonstrate the utility of a modified luciferase reporter system for assessing kinase activity modulation.
Main Methods:
- Engineered a luciferase reporter enzyme with a PKA-specific phosphorylation target sequence, termed luciferase(PKA).
- Generated transgenic mice by incorporating the luciferase(PKA) construct into the mouse genome.
- Administered isoproterenol to transgenic mice to stimulate beta-adrenergic pathways and observed changes in luminescence.
Main Results:
- Transgenic mice expressing luciferase(PKA) exhibited a rapid decrease in luminescence in response to isoproterenol.
- This reduction in luminescence, indicative of PKA activation, was observed across multiple organs, including the pancreas, muscle, liver, and fat.
- The study successfully demonstrated noninvasive, real-time monitoring of PKA activity in vivo.
Conclusions:
- Luciferase reporter systems can be effectively adapted for in vivo measurements of kinase activity.
- This novel model provides a powerful tool for studying PKA function and signaling dynamics in living animals.
- The principle can be extended to develop reporters for other kinases by altering the target phosphorylation sequences within luciferase.
