Compartmentalized cAMP Generation by Engineered Photoactivated Adenylyl Cyclases

Area of Science:

• Cell Biology
• Molecular Signaling
• Biochemistry

Background:

• Small-molecule adenylyl cyclase (AC) activators impact cells globally, hindering the study of localized AC activity.
• Understanding compartmentalized cyclic AMP (cAMP) signaling is crucial for deciphering complex cellular processes.
• Optogenetic tools offer precise spatial and temporal control over enzyme activity.

Purpose of the Study:

• To investigate the spatial and temporal consequences of localized adenylyl cyclase (AC) activation.
• To explore cAMP signaling dynamics originating from specific intracellular compartments using optogenetics.
• To elucidate the role of phosphodiesterases in modulating localized and distal cAMP signals.

Main Methods:

• Engineered optogenetic, photoactivable adenylyl cyclases (PACs) localized to the plasma membrane (PM), outer mitochondrial membrane (OMM), and nucleus (Nu).
• Photostimulation of PACs to induce localized cAMP production.
• Biochemical assays to measure cAMP levels, protein kinase A (PKA) activity, and PKA subunit localization.
• Pharmacological inhibition of phosphodiesterases (PDEs) 3 and 4.

Main Results:

• Brief photostimulation of PACs resulted in localized biochemical effects.
• Sustained photostimulation led to distal cAMP signaling, demonstrating signal propagation.
• Prolonged cAMP generation at the OMM significantly activated nuclear PKA.
• Phosphodiesterases 3 (at OMM and PM) and 4 (at PM) modulated local cAMP activity.
• Phosphodiesterase 4 regulated distal cAMP signaling and PKA catalytic subunit nuclear translocation.

Conclusions:

• Optogenetic PACs provide a powerful tool to dissect compartmentalized cAMP signaling.
• Sustained, localized cAMP production can trigger distal signaling events and nuclear responses.
• Specific phosphodiesterases play distinct roles in controlling both local and long-range cAMP effects.