Tracking kinase activity in living cells with molecular recorder

The molecular tool named Kinprola enables spatial and temporal monitoring of kinase activity in living cells, including in complex tissues and heterogeneous cell populations. 

The Kinprola system is based on a molecular switch mechanism involving HaloTag, a self-labeling protein: 

• Two split HaloTag fragments rejoin only when a specific kinase is activated. 

• When a fluorescent HaloTag substrate is present, the system marks active kinase events. 

• The intensity of the fluorescence reflects the strength of kinase activity, while the duration of substrate exposure determines the time window of the recording. 

The Max Planck team designed Kinprola variants for four different kinases, with a focus on protein kinase A (PKA) in the current study. 

“We wanted to find a way to record kinase activities in a scalable and high-resolution manner, without the restrictions of optical imaging. Under the microscope, observations are typically limited to real-time imaging of a relatively small number of cells and are not readily applicable to deep tissues,” explains project lead De-en Sun. 

By relying on a phosphorylation-dependent molecular switch, Kinprola allows kinase activity to be recorded as a stable fluorescent signal, decoupling the timing of observation from the moment of activity. 

Once activated and labeled, Kinprola proteins remain stably fluorescent, allowing later analysis via: 

• Various microscopy techniques 

• Flow cytometry, which enables high-throughput analysis and sorting of cells based on physical and chemical properties 

This makes the method highly versatile, scalable, and applicable to different experimental setups. In live animal models, Kinprola has successfully recorded drug-induced PKA activation in the brains of mice. 

MEDICA-tradefair.com; Source: Max-Planck-Institut für medizinische Forschung