Johanna G. Flyer-Adams

Griffith Lab

“Pigment dispersing factor (PDF) signaling: A novel pathway for memory regulation by the circadian clock”

The mental fuzziness and unreal feelings of jetlag are familiar to anyone who has traveled across time zones. But why do these changes to our circadian clocks lead to such problems? Ms. Flyer-Adams is exploring the molecular factors involved in the circadian clock and memory formation, using fruit flies as a model organism.

The behavioral link between your circadian clock and memory is clear: disruptions to your clock, such as jetlag and shiftwork, generate cognitive deficits which scale with the severity and duration of the disruption. However, the neural circuits involved in regulation of memory by the clock are unknown. In Drosophila, both the circadian clock and memory circuitry are individually well-described, providing a starting point to investigate their linkage. We find that the clock-specific signaling neuropeptide pigment dispersing factor (PDF) and its only known receptor PDFR are both required for normal appetitive olfactory short term memory (STM). Within the core clock, PDF canonically signals through PDFR to entrain the circadian clock and regulate daily patterns of locomotor activity. We show that PDF/PDFR signaling either within the clock or in the ellipsoid body (EB) can support circadian locomotor behavior independently from STM. Taken together, our data show that PDF from within the clock can regulate distinct behavioral outputs based on PDFR localization, and that PDF acts on a target outside of the clock to regulate memory.