Second messenger pas de deux: the coordinated dance between calcium and cAMP.

Dynamic calcium signaling is a well-established precept in biology. Different cell types exhibit spontaneous as well as stimulus-triggered transient changes in the concentration of intracellular calcium. Does this behavior extend to other second messengers? Optical dissection of various signal transduction pathways with fluorescent reporter molecules that enable visualization of changes in concentration of other second messengers is well under way. Recent research using technologically refined probes provides improved temporal and spatial resolution of adenosine 3',5'-monophosphate (cAMP) dynamics to generate insights into the bidirectional interplay between intracellular fluctuations of cAMP and calcium. cAMP oscillations are generated in response to hormones, and cells can recognize and differentially respond to transient versus sustained changes in this second messenger. Second messenger reporters are now available to track multiple players and so provide a dynamic picture of signaling networks.