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Untangling Appetite Circuits with Optogenetics and Chemogenetics
Published in Ruth B.S. Harris, Appetite and Food Intake, 2017
Chemogenetics is a system to control neuronal activity noninvasively in the mammalian brain by regulating signaling through a G-protein-coupled receptor (GPCR) (Armbruster et al. 2007, Luo, Callaway, and Svoboda 2008) or recently using ligand-activated ion channels (Atasoy et al. 2012, Magnus et al. 2011, Stachniak, Ghosh, and Sternson 2014). These pharmacological approaches to manipulate neuronal activity through GPCR signaling pathways in neurons both in vitro and in vivo include ectopic expression of either GPCRs with engineered binding sites such as receptors activated solely by synthetic ligands (RASSLs) (Redfern et al. 1999, Zhao et al. 2003) or nonnative GPCRs such as the Drosophila allatostatin receptor (AlstR) (Lechner, Lein, and Callaway 2002, Tan et al. 2006).
Pigment-dispersing factor and CCHamide1 in the Drosophila circadian clock network
Published in Chronobiology International, 2023
Riko Kuwano, Maki Katsura, Mai Iwata, Tatsuya Yokosako, Taishi Yoshii
Other neurotransmitters mediating between clock neurons have been identified in the Drosophila circadian clock. For example, glutamate mediates signalling from DN1p, LNd, and 5th s-LNv neurons to s-LNv neurons (Collins et al. 2014; Duhart et al. 2020). Moreover, glycine (Frenkel et al. 2017), acetylcholine (Duhart et al. 2020), diuretic hormone 31 (DH31) (Goda et al. 2018), and allatostatin C (Díaz et al. 2019) play roles in circadian intercellular couplings. Thus, the entire neuronal wiring of the Drosophila clock network comprises neurons that synthesize several different neurotransmitters. The suprachiasmatic nucleus (SCN), the mammalian central clock, is composed of 20,000 neurons, with vasoactive intestinal polypeptide, arginine vasopressin, gastrin-releasing peptide, and gamma-aminobutyric acid as intercellular synchronisers (Mieda 2020; Ono et al. 2021). Thus, the Drosophila clock network consists of a much smaller number of neurons than the mammalian SCN; however, the number of intercellular synchronisers in the Drosophila clock network is abundant.
Spatiotemporal organization of enteroendocrine peptide expression in Drosophila
Published in Journal of Neurogenetics, 2021
Sooin Jang, Ji Chen, Jaekyun Choi, Seung Yeon Lim, Hyejin Song, Hyungjun Choi, Hyung Wook Kwon, Min Sung Choi, Jae Young Kwon
Here, we use peptide antisera and a transgenic reporter system to define the expression of allatostatin C (AstC), CCHamide 2 (CCHa2), diuretic hormone 31 (Dh31), myoinhibiting peptide precursor (MIP or AstB), neuropeptide F (NPF), orcokinin B, short NPF (sNPF), and tachykinin (Tk) in the larval midgut. We also examined expression during the pupa stage to determine when and where peptides are expressed during the development of the adult midgut, and found that enteroendocrine cells expressing AstC and CCHa2 only started to appear when flies are near eclosion whereas other peptides were detected at 96 h APF (after puparium formation). In addition, we found that in the adult anterior midgut, differential Notch signaling defines subtypes of enteroendocrine cells, similar to the posterior midgut, but the peptides expressed are distinct from the subtypes observed in the posterior midgut.
Identification and characterization of GAL4 drivers that mark distinct cell types and regions in the Drosophila adult gut
Published in Journal of Neurogenetics, 2021
Seung Yeon Lim, Hyejin You, Jinhyeong Lee, Jaejin Lee, Yoojin Lee, Kyung-Ah Lee, Boram Kim, Ji-Hoon Lee, JiHyeon Jeong, Sooin Jang, Byoungsoo Kim, Hyungjun Choi, Gayoung Hwang, Min Sung Choi, Sung-Eun Yoon, Jae Young Kwon, Won-Jae Lee, Young-Joon Kim, Greg S. B. Suh
The EEs of the adult midgut can be divided into two subpopulations based on peptide expression with one group expressing allatostatin A, allatostatin C, and orcokinin, and the other expressing tachykinin, neuropeptide F, and diuretic hormone 31 (Chen, Kim, & Kwon, 2016; Veenstra & Ida, 2014). All EE-specific GAL4 lines were expressed in subsets of Prospero-positive cells; none of these lines were expressed in all of the Prospero-positive cells in the gut. This may suggest that EEs can be divided into functionally distinct subpopulations. It is possible that each subpopulation of EE cells acquires a distinct gene expression profile when its fate is decided during the transition from ISCs to EEs. According to single-cell RNA-sequencing data, most EEs in the midgut of adult flies express two to five different types of peptide hormones, and that they can be divided into more than 10 subtypes depending on the combinations of peptide hormones that are present (Guo et al., 2019; Hung et al., 2020). We were not able to identify GAL4 lines that represent small subsets of EEs; however, we were able to show the potential of intersectional analysis using the split-GAL4 system (Beehler-Evans & Micchelli, 2015; Chen et al., 2016). By expanding the split-GAL4 combinations, we should be able to define functionally distinct populations of EEs throughout the entire midgut. These transgenic tools should be useful in such functional analyses in the future. A similar approach should also be informative for other cell types such as ENs or other midgut epithelial cells.