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cAMPr: A single-wavelength fluorescent sensor for cyclic AMP

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Sci. Signal.  06 Mar 2018:
Vol. 11, Issue 520, eaah3738
DOI: 10.1126/scisignal.aah3738

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Live-cell imaging of cAMP

The second messenger cAMP is found in many cell types and organisms. Increases in the cytosolic concentration and localization of cAMP mediate various cellular functions through the activation of the kinase PKA and the transcription factor CREB; thus, the ability to detect and image cAMP in live cells would help to understand its mechanism of action. Hackley et al. developed a genetically encoded fluorescent sensor of cAMP (cAMPr), which was expressed in mammalian neurons and in the Drosophila brain and responded to stimulation of adenylyl cyclase, the enzyme that generates cAMP. Furthermore, cAMPr was used together with a fluorescent Ca2+ sensor to simultaneously detect cAMP and Ca2+ in the Drosophila brain through two-photon imaging, suggesting its potential use to study cAMP signaling in diverse tissues and organisms.


Genetically encoded fluorescent sensors enable cell-specific measurements of ions and small molecules in real time. Cyclic adenosine monophosphate (cAMP) is one of the most important signaling molecules in virtually all cell types and organisms. We describe cAMPr, a new single-wavelength cAMP sensor. We developed cAMPr in bacteria and embryonic stem cells and validated the sensor in mammalian neurons in vitro and in Drosophila circadian pacemaker neurons in intact brains. Comparison with other single-wavelength cAMP sensors showed that cAMPr improved the quantitative detection of cAMP abundance. In addition, cAMPr is compatible with both single-photon and two-photon imaging. This enabled us to use cAMPr together with the red fluorescent Ca2+ sensor RCaMP1h to simultaneously monitor Ca2+ and cAMP in Drosophila brains. Thus, cAMPr is a new and versatile genetically encoded cAMP sensor.

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