A population of neurons that produce hugin and express the diuretic hormone 44 receptor gene projects to the corpora allata in Drosophila melanogaster

Yosuke Mizuno, Eisuke Imura, Yoshitomo Kurogi, Yuko Shimada-Niwa, Shu Kondo, Hiromu Tanimoto, Sebastian Hückesfeld, Michael J. Pankratz, Ryusuke Niwa

Research output: Contribution to journalArticlepeer-review

Abstract

The corpora allata (CA) are essential endocrine organs that biosynthesize and secrete the sesquiterpenoid hormone, namely juvenile hormone (JH), to regulate a wide variety of developmental and physiological events in insects. CA are directly innervated with neurons in many insect species, implying the innervations to be important for regulating JH biosynthesis. Although this is also true for the model organism Drosophila melanogaster, neurotransmitters produced in the CA-projecting neurons are yet to be identified. In this study on D. melanogaster, we aimed to demonstrate that a subset of neurons producing the neuropeptide hugin, the invertebrate counterpart of the vertebrate neuromedin U, directly projects to the adult CA. A synaptic vesicle marker in the hugin neurons was observed at their axon termini located on the CA, which were immunolabeled with a newly-generated antibody to the JH biosynthesis enzyme JH acid O-methyltransferase. We also found the CA-projecting hugin neurons to likely express a gene encoding the specific receptor for diuretic hormone 44 (Dh44). Moreover, our data suggest that the CA-projecting hugin neurons have synaptic connections with the upstream neurons producing Dh44. Unexpectedly, the inhibition of CA-projecting hugin neurons did not significantly alter the expression levels of the JH-inducible gene Krüppel-homolog 1, which implies that the CA-projecting neurons are not involved in JH biosynthesis but rather in other known biological processes. This is the first study to identify a specific neurotransmitter of the CA-projecting neurons in D. melanogaster, and to anatomically characterize a neuronal pathway of the CA-projecting neurons and their upstream neurons.

Original languageEnglish
Pages (from-to)249-261
Number of pages13
JournalDevelopment Growth and Differentiation
Volume63
Issue number4-5
DOIs
Publication statusPublished - 2021 May 1

Keywords

  • Drosophila melanogaster
  • corpora allata
  • diuretic hormone 44
  • hugin
  • juvenile hormone

ASJC Scopus subject areas

  • Developmental Biology
  • Cell Biology

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