PDF neuropeptide levels leading structural plasticity in Drosophila clock neurons

NARA MURARO; M FERNANDA CERIANI; ANASTASIA HERRERO

Colonia del Sacramento

Congreso; XV Latin American Symposium on Chronobiology; 2019

Latin American Symposium on Chronobiology Organizing Committee

A number of years ago we reported that Pigment dispersing factor (PDF) neurons, which are essential in the control of rest-activity cycles in Drosophila, undergo circadian remodeling of their axonal projections, a phenomenon called circadian structural plasticity. Axonal arborizations display higher complexity during the day and less so at night, and this remodeling involves changes in the degree of connectivity. We also demonstrated that this phenomenon depends on the clock present within the ventrolateral neurons (LNvs) as well as that in glia. Here we characterize in detail the role of the PDF neuropeptide and study its contribution to structural plasticity at different times of the day. Using diverse genetic strategies to temporally restrict its downregulation, we demonstrate that subtly altering PDF cycling at the dorsal protocerebrum correlates with impaired remodeling, suggesting its relevance for the characteristic morning spread; both, PDF released from the small LNvs (sLNvs) and the large LNvs (lLNvs) contribute to the process. Moreover, forced depolarization recruits activity-dependent mechanisms to mediate growth only at night, overcoming the restriction imposed by the clock on membrane excitability. Interestingly, the active process of terminal remodeling requires PDFR signaling acting locally through the cyclic nucleotide-gated channel CNGA and not PDF itself. Thus, clock-dependent PDF signaling shapes the connectivityof these essential clock neurons on daily basis.