User:Joannaluo176/sandbox

New findings have shown that PDF synchronizes circadian clock neurons by increasing levels of cAMP and cAMP-mediated protein kinase A (PKA). Increasing cAMP and PKA stabilized levels of the period protein PER in Drosophila, which slows the clock speed in PDF receptor (PDFR) containing neurons. A light pulse caused more PER degradation in flies with pdf-null neurons than flies with wild-type neurons, indicating that PDF inhibits light-induced PER degradation. These experiments demonstrated that PDF interacts with secondary messenger components to coordinate circadian output.

(place under homolog) The neuropeptide VIP is a homolog of PDF instrumental for cellular and behavioral 24 hour rhythms in mammals. It expressed in 10 percent of neurons in the SCN. VIP plays a role in synchronizing and supporting rhythmicity by diverse SCN pacemakers. Similar behavioral phenotypes were seen in VIP and VIP receptor 2 (VIPR2) knockout mice: both models displayed entrained activity rhythms in light dark condition. However, in constant darkness both models displayed poor rhythmicity (very short period), and half of the animals tested were arrhythmic.