Optical mapping of cAMP signaling at the nanometer scale

Andreas Bock*, Paolo Annibale, Charlotte Konrad, Annette Hannawacker, Selma E. Anton, Isabella Maiellaro, Ulrike Zabel, Sivaraj Sivaramakrishnan, Martin Falcke, Martin J. Lohse

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

103 Citations (Scopus)

Abstract

Cells relay a plethora of extracellular signals to specific cellular responses by using only a few second messengers, such as cAMP. To explain signaling specificity, cAMP-degrading phosphodiesterases (PDEs) have been suggested to confine cAMP to distinct cellular compartments. However, measured rates of fast cAMP diffusion and slow PDE activity render cAMP compartmentalization essentially impossible. Using fluorescence spectroscopy, we show that, contrary to earlier data, cAMP at physiological concentrations is predominantly bound to cAMP binding sites and, thus, immobile. Binding and unbinding results in largely reduced cAMP dynamics, which we term “buffered diffusion.” With a large fraction of cAMP being buffered, PDEs can create nanometer-size domains of low cAMP concentrations. Using FRET-cAMP nanorulers, we directly map cAMP gradients at the nanoscale around PDE molecules and the areas of resulting downstream activation of cAMP-dependent protein kinase (PKA). Our study reveals that spatiotemporal cAMP signaling is under precise control of nanometer-size domains shaped by PDEs that gate activation of downstream effectors.

Original languageEnglish
Pages (from-to)1519-1530.e17
Number of pages30
JournalCell
Volume182
Issue number6
Early online date25 Aug 2020
DOIs
Publication statusPublished - 17 Sept 2020

Keywords

  • Buffered diffusion
  • Cell signaling
  • Compartmentation
  • Cyclic AMP
  • Fluorescence fluctuation spectroscopy
  • FRET biosensors
  • G protein-coupled receptors
  • Nanodomains
  • Phosphodiesterase
  • Protein kinase A4

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