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Ultraspiracle-independent anti-apoptotic function of ecdysone receptors is required for the survival of larval peptidergic neurons via suppression of grim expression in Drosophila melanogaster

  • Gyunghee Lee
  • Ritika Sehgal
  • Zixing Wang
  • Jae H. ParkEmail author


In Drosophila melanogaster a significant number of heterogenous larval neurons in the central nervous system undergo metamorphosis-associated programmed cell death, termed metamorphoptosis. Interestingly distinct groups of doomed larval neurons are eliminated at different metamorphic phases. Although ecdysone hormonal signaling via nuclear ecdysone receptors (EcRs) is known to orchestrate the neuronal metamorphoptosis, little is known about how this signaling controls such diverse neuronal responses. Crustacean cardioactive peptide (CCAP)-producing neurons in the ventral nerve cord are developmentally programmed to die shortly after adult emergence. In this study, we show that disruption of endogenous EcR function by ectopic expression of dominant negative forms of EcRs (EcRDN) causes premature death of larval CCAP neurons in a caspase-dependent manner. This event is rescued by co-expression of individual EcR isoforms. Furthermore, larval CCAP neurons are largely normal in ecr mutants lacking either EcR-A or EcR-B isoforms, suggesting that EcR isoforms redundantly function to protect larval CCAP neurons. Of surprise, a role of Ultraspiracle (Usp), a canonical partner of EcR, is dispensable in the protection of CCAP neurons, whereas both EcR and Usp are required for inducing metamorphoptosis of vCrz neurons shortly after prepupal formation. As a downstream, grim is an essential cell death gene for the EcRDN-mediated CCAP neuronal death, while either hid or rpr function is dispensable. Together, our results suggest that Usp-independent EcR actions protect CCAP neurons from their premature death by repressing grim expression until their normally scheduled apoptosis at post-emergence. Our studies highlight two opposite roles played by EcR function for metamorphoptosis of two different peptidergic neuronal groups, proapoptotic (vCrz) versus antiapoptotic (CCAP), and propose that distinct death timings of doomed larval neurons are determined by differential signaling mechanisms involving EcR.


Metamorphoptosis Ultraspiracle Ecdysone receptor Central nervous system Peptidergic neurons Grim Apoptosis 



After eclosion


After puparium formation


Central nervous system


Programmed cell death


Ventral nerve cord


Crustacean cardioactive peptide




Ecdysone receptor





We want to express our gratitude to many people for their kind donation of various research materials; B. White (NIH) for the anti-bursicon, K. White (Mass General Hospital) for hid mutants, T. Lee (Janelia Farm) for UAS-miusp line, M. Bender (Univ. of Georgia) for ecr mutants, S. Robinow (Univ. of Hawaii) for UAS-EcR, P. Cherbas (Indiana Univ.) for UAS-EcRDN lines, B. Hay (Caltech) for UAS-miRGH and UAS-migrim lines, T. Lee (Janelia farm) for usp3 MARCM lines. This work was supported by an NIH Grant (R15-GM114741) and by Hunsicker research incentive Grant (Univ. of Tennessee).

Supplementary material

10495_2019_1514_MOESM1_ESM.pdf (2.7 mb)
Supplemental Fig. 1 Developmental phenotypes by A9-gal4 driven expression of EcRW650A or Usp3. a–eEcRW650A expression caused various developmental defects in larval stages (a–b) and in pupal stages (c–e), whereas Usp3 expression did not affect larval growth but led to death of pharate adults inside the pupal case (f) (PDF 2791 KB)


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Biochemistry and Cellular and Molecular Biology and NeuroNet Research CenterUniversity of TennesseeKnoxvilleUSA
  2. 2.UT-ORNL Graduate School of Genome Science and Technology ProgramUniversity of TennesseeKnoxvilleUSA

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