The CCHamide1 Neuropeptide Expressed in the Anterior Dorsal Neuron 1 Conveys a Circadian Signal to the Ventral Lateral Neurons in Drosophila melanogaster

Abstract

The fruit fly Drosophila melanogaster possesses approximately 150 brain clock neurons that control circadian behavioral rhythms. Even though individual clock neurons have self-sustaining oscillators, they interact and synchronize with each other through a network. However, little is known regarding the factors responsible for these network interactions. In this study, we investigated the role of CCHamide1 (CCHa1), a neuropeptide expressed in the anterior dorsal neuron 1 (DN1a), in intercellular communication of the clock neurons. We observed that CCHa1 connects the DN1a clock neurons to the ventral lateral clock neurons (LNv) via the CCHa1 receptor, which is a homolog of the gastrin-releasing peptide receptor playing a role in circadian intercellular communications in mammals. CCHa1 knockout or knockdown flies have a generally low activity level with a special reduction of morning activity. In addition, they exhibit advanced morning activity under light-dark cycles and delayed activity under constant dark conditions, which correlates with an advance/delay of PAR domain Protein 1 (PDP1) oscillations in the small-LNv (s-LNv) neurons that control morning activity. The terminals of the s-LNv neurons show rather high levels of Pigment-dispersing factor (PDF) in the evening, when PDF is low in control flies, suggesting that the knockdown of CCHa1 leads to increased PDF release; PDF signals the other clock neurons and evidently increases the amplitude of their PDP1 cycling. A previous study showed that high-amplitude PDP1 cycling increases the siesta of the flies, and indeed, CCHa1 knockout or knockdown flies exhibit a longer siesta than control flies. The DN1a neurons are known to be receptive to PDF signaling from the s-LNv neurons; thus, our results suggest that the DN1a and s-LNv clock neurons are reciprocally coupled via the neuropeptides CCHa1 and PDF, and this interaction fine-tunes the timing of activity and sleep.

A gut-secreted peptide controls arousability through modulation of dopaminergic neurons in the brain

“…To find the relevant CCHa1-producing cells, we raised antibodies against CCHa1 (using a previously validated epitope 21 ) and expressed CCHa1-RNAi with spatially restricted Gal4s. The antibody signal agreed with previous reports 13,16,21 (Fig. 2a) and with the pattern of CCHa1promoter-driven GFP (Extended Data Fig.…”

“…We focused on the neuropeptide CCHamide-1 and its receptor CCHa1R, since both have strong phenotypes and belong to the same pathway. CCHamides (CCHa1 and CCHa2) are recently discovered neuropeptides with functions related to feeding and growth regulation (CCHa2), and olfactory responsiveness and circadian behavior (CCHa1) [11][12][13][14][15][16] . CCHa1R is a G protein-coupled receptor homologous to the mammalian Gastrin-Releasing Peptide Receptor 16 which regulates itch sensation 17 and responsiveness to social interactions 18,19 .…”

Light input pathways to the circadian clock of insects with an emphasis on the fruit fly Drosophila melanogaster

“…2). Nonetheless, the s-LN v do not work in isolation but cooperate with the DN and LN d (see Fujiwara et al 2018 andChatterjee et al 2018 for recent examples). The l-LN v have also excessive dendrites in the ipsilateral AME that extend ventrally into the so-called ventral elongation of the AME.…”

Allatostatin-C/AstC-R2 Is a Novel Pathway to Modulate the Circadian Activity Pattern in Drosophila

“…The activity-promoting E-cells express several different neuropeptides: the 5 th s-LNv and five of the six LNds express a combination of NPF, sNPF, and ion transport peptide (ITP) [8] [9] [10]. Among the DN1s, the two DN1as are anatomically and functionally distinct from the DN1ps, partly due to expression of the neuropeptides IPNamide [11] and CCHamide1 [12] in the DN1as. The neuropeptide diuretic hormone 31 (Dh31) is synthesized in five of the DN1ps to influence sleep [13] and possibly temperature preference [14].…”