MRI biosensor for protein kinase A encoded by a single synthetic gene

作者：Airan Raag D; Bar Shir Amnon; Liu Guanshu; Pelled Galit; McMahon Michael T; van Zijl Peter C M; Bulte Jeff W M; Gilad Assaf A^*

来源：Magnetic Resonance in Medicine, 2012, 68(6): 1919-1923.

DOI：10.1002/mrm.24483

• chemical exchange saturation transfer
• biosensor
• reporter gene
• protein kinase A

Purpose: Protein kinases including protein kinase A (PKA) underlie myriad important signaling pathways. The ability to monitor kinase activity in vivo and in real-time with high spatial resolution in genetically specified cellular populations is a yet unmet need, crucial for understanding complex biological systems as well as for preclinical development and screening of novel therapeutics. Methods: Using the hypothesis that the natural recognition sequences of protein kinases may be detected using chemical exchange saturation transfer magnetic resonance imaging, we designed a genetically encoded biosensor composed of eight tandem repeats of the peptide LRRASLG, a natural target of PKA. Results: This sensor displays a measurable change in chemical exchange saturation transfer signal following phosphorylation by PKA. The natural PKA substrate LRRASLG exhibits a chemical exchange saturation transfer-magnetic resonance imaging contrast at +1.8 and +3.6 ppm, with a >50% change after phosphorylation with minutes-scale temporal resolution. Expression of a synthetic gene encoding eight monomers of LRRASLG yielded two peaks at these chemical exchange saturation transfer frequencies. Conclusion: Taken together, these results suggest that this gene may be used to assay PKA levels in a biologically relevant system. Importantly, the design strategy used for this specific sensor may be adapted for a host of clinically interesting protein kinases. Magn Reson Med, 2012.

• 出版日期2012-11