Ion channels that regulate neuronal physiology and circadian behavior in Drosophila melanogaster

NARA I MURARO; CARINA C. COLQUE; LIA FRENKEL; FLORENCIA FERNANDEZ; BRYAN HAHM; M. FERNANDA CERIANI

Palm Harbor, Florida

Congreso; 15th Biennial Meeting, Society for Research on Biological Rhythms; 2016

Society for Research on Biological Rhythms

Circadianrhythms have been extensively studied in the fruit fly where many clock genesthat interlock through negative feedback loops and generate daily oscillationshave been described. Clock genes are expressed in approximately 150 clockneurons in the Drosophila brain.Among them, the pigment dispersing factor (PDF)-expressing lateral neurons (LNvs)have been found to play central roles as pacemaker (the small-LNvs) and arousal(the large-LNvs) neurons.Still, littleis known on how the electrical properties of Drosophila clock neurons are specified, and what mechanisms allowthem to change their firing rate on a daily basis. We have performed a behavioral genetic screenthrough the downregulation of candidate voltage-gated ion channels using RNA-interferencespecifically in LNvs. Among the positive hits we focused our attention on the hyperpolarisation-activated cation current Ih. In mammalianneurons, this channel is involved in complex neuronal behaviors such asbursting, the same firing pattern that LNvs display. Here, we show that Ihexpression is important for the behaviors that LNvs command. Moreover, usinggenetics and pharmacology coupled to whole-cell patch clamp electrophysiologyin ex vivo Drosophila brains, we show that Ih is necessary toachieve the high frequency bursting firing pattern of LNvs. Since burstingfiring has been associated to neuropeptide release, we hypothesized that Ihwould be important for PDF-mediated communication. This is indeed the case; we foundthat constitutive downregulation of Ih affects sLNvs development andadult-specific downregulation of Ih affects PDF levels andstructural plasticity of sLNvs dorsal projections.