During their lives, animals encounter a broad range of stimuli from their surroundings including heat, light and touch. The ability to appropriately respond to such stimuli is crucial for survival as it allows the animals to avoid predators and other dangers, locate food and shelter, and find mates.

Fruit fly larvae are a useful model for studying how animals respond to unpleasant (known as painful) heat stimuli. When something hot touches a larva, the larva rolls away to avoid the stimulus. The heat stimulates electrical activity in a type of neuron known as C4da neurons on the surface of the larva. Ultraviolet light and several other stimuli are also able to activate electrical activity in C4da neurons, resulting in the larvae changing the direction they move to avoid the stimuli.

Only older fly larvae respond to painful heat stimuli and previous studies found that a hormone receptor protein is required for this response. However, it remains unclear how this response develops as the larvae age.

Jaszczak et al. studied the behavior of fly larvae and electrical activities of C4da neurons in response to painful heat and ultraviolet light. The experiments found that painful heat triggered more rolling behavior from older larvae than those of younger larvae. In contrast, ultraviolet light triggered lower levels of electrical activity in the C4da neurons of older larvae than those of younger larvae. The team raised the levels of a hormone known as ecdysone and found that this increased the rolling behavior in younger larvae. They then increased the amount of receptor protein for this hormone in the neurons and found that it decreased the levels of another protein called Subdued in the C4da neurons. This in turn increased the neurons’ response to painful heat and decreased their response to ultraviolet light.

Jaszczak et al. propose that as the larva develops, ecdysone reduces the levels of Subdued, which promotes C4da neurons to switch their sensitivity from detecting ultraviolet light to painful heat. In the future, better understanding of what causes pain sensations in developing animals will help us search for factors that cause long-term pain conditions in humans.

Detection of internal and external stimuli depends on developmental programing of the proper physiological and morphological properties of sensory neurons. It is an intriguing open question as to how the characteristics of sensory transduction arise during development, and which neuronal properties are crucial for the initiation of sensory detection.

Nociception, the ability to detect and escape potentially harmful stimuli, is a highly conserved function of sensory systems present in all animals (Arenas et al., 2017). A nociception system is composed of nociceptors, which are neurons with molecular components that directly sense harmful stimuli; a processing center where the stimuli are interpreted, typically the neural circuits of the central nervous system (CNS); and the reflexive neuromuscular circuit which generates a reaction to escape injury (Baliki and Apkarian, 2015). Development of sensory systems requires the coordination of processes on the cellular, morphogenic, and circuit level.

Thermal nociception generates an avoidance behavior, such as a fast limb retraction or change of movement trajectory. Previous studies of thermal nociception behaviors and neural activity demonstrate a change in nociceptive responses during development of both mice and Drosophila. For example, a mouse paw exhibits low sensitivity to painful heat early in postnatal development, but the rate of reflex gets faster as the animal develops (Jankowski et al., 2014; Ford et al., 2019). A developmental transition is also observed in nociceptor activity, as revealed by the change in the number of heat-sensitive C-fibers with age in mice (Hiura et al., 1992). Likewise, a behavioral transition in heat thermal nociception has been observed in Drosophila melanogaster larvae (Sulkowski et al., 2011). Drosophila third instar larvae exhibit a stereotyped ‘corkscrew’ behavior, when a thermal probe heated above 38°C touches the cuticle (Tracey et al., 2003; Babcock et al., 2009). However, this behavior is not observed in second instar or earlier larval stages, and appears to be acquired only during the last stage of larval development.

The larval nociceptive behavior has been a useful model for dissection of the molecular mechanisms and circuitry of nociception (Himmel et al., 2017). Among the heat-sensitive neurons in the larval cuticle (Liu et al., 2003) are the Class IV dendritic arborization (C4da) neurons, which function as the primary nociceptors for noxious heat-induced escape behavior (Tracey et al., 2003; Hwang et al., 2007). C4da neurons are multimodal sensors for harmful stimuli, with the capacity to respond to multiple forms of sensory information. In addition to responding to temperature, C4da neurons respond to high-intensity blue light (Xiang et al., 2010), noxious UV light (Xiang et al., 2010; Gu et al., 2019), and harsh touch (Zhong et al., 2010).

While noxious heat and touch both elicit the rolling escape behavior, stimulation of C4da neurons with short wavelength (blue or UV) light causes a locomotion trajectory avoidance behavior. These different stimuli cause different electrical signals in C4da neurons. Noxious heat causes high-frequency spike trains interspersed with quiescent periods, in contrast to blue light which elicits lower frequency firing with few quiescent periods in third instar larvae (Terada et al., 2016). Therefore, distinct behaviors appear to be encoded by the C4da neurons according to their differential responses to differing stimuli.

The majority of studies of nociception in Drosophila larvae have focused on the last (i.e., the third) larval instar, where nearly all larvae will perform the behavioral response. However, Sulkowski et al. found that during the first half of larval development (i.e., the first and second instars), larvae exhibited either no or a low rate of thermal nociceptive behavior, leading to the hypothesis that a developmental transition occurs between the second and third larval instars (Sulkowski et al., 2011). The mechanisms which regulate this transition remain unknown. Optogenetic activation of C4da neurons can induce the corkscrew behavior or a locomotion trajectory avoidance behavior in third instar larvae. However, optogenetic activation could only induce a locomotion trajectory avoidance behavior in the second instar. This difference between second and third instars in the optogenetic activation of behavior, taken together with the difference in coding activity in C4da neurons in response to thermal stimulation or light (Terada et al., 2016), raises the possibility that the developmental transition may involve a change in sensory coding. Supporting this possibility, misexpression of low temperature activated TrpA1 (isoform A) channels in the C4da neurons enables second instar larvae to exhibit corkscrew behavior in response to an innocuous temperature stimulus (Luo et al., 2017). It is conceivable that the sensory switch may be caused by a cell autonomous change in the C4da neurons. Whether C4da neurons change in their neural activity during the developmental transition from second to third instar is unknown, and the regulators of such transition are unknown as well.

Transcription factors facilitate the formation of distinct neuronal functions (Parrish et al., 2014) and regulate the dynamic expression profiles of many developmental transitions between and during larval instars (Sullivan and Thummel, 2003). One such transcription factor is the nuclear hormone receptor ecdysone receptor (EcR). EcR forms a heterodimer with ultraspiracle (USP) and binds the ligand ecdysone, a steroid hormone, to coordinate a wide variety of developmental programs (Yamanaka et al., 2013). EcR and USP are required for thermal nociception in the third instar (McParland et al., 2015), but the mechanism and role of ecdysone signaling in the second instar have not been determined.

EcR expression in C4da neurons has been reported at the beginning and end of larval development (Kuo et al., 2005; Ou et al., 2008; Kirilly et al., 2009; McParland et al., 2015). In the absence of ligand, EcR and USP distribute between the cytoplasm and nucleus, while ligand binding increases nuclear localization (Nieva et al., 2007; Nieva et al., 2008). Without ligand binding, EcR and USP recruit nucleosome remodeling proteins to compact the chromatin and locally suppress transcription. When bound to ecdysone, EcR-USP recruit coactivators, such as histone acetylases, to expand the chromatin structure and promote transcription. In this way, steroid hormone signaling can create positive and negative feedback to promote cascades of transcriptional programs at developmentally precise periods (Sullivan and Thummel, 2003; Hill et al., 2013). Whether the ligand-induced activity and transcriptional regulation are involved in EcR-mediated thermal nociception remains to be determined.

In this study, we performed a series of experiments to determine the activity of the C4da neurons during the developmental nociceptive transition as well as the mechanisms which regulate this sensory switch. These experiments demonstrate that steroid hormone signaling in nociceptive neurons regulates the channel composition in C4da neurons to modulate the sensory properties and behavioral response at distinct stages of larval development.

The impact of peripheral nervous system (PNS) development on behavior is underscored by the recent finding that defects in the PNS are sufficient to produce symptoms in mouse models of autism spectrum disorders (Orefice et al., 2016). The role of hormonal regulation of sensory systems during periods of postnatal development has also been highlighted by studies of growth hormone regulation of thermal sensitivity (Liu et al., 2017; Ford et al., 2019). Considering that sensory neurons progress through transcriptionally distinct identities during development (Sharma et al., 2020), characterizing how the specific changes in receptors or channels that produce these developmentally specific outcomes is of prominent importance for understanding the development of neurological disease.

In this study, we address how a nociceptive behavior is temporally acquired during development. We demonstrate how steroid hormone regulation of nociceptor activity in a class of sensory neurons in the PNS adjusts the developing larval response to nociceptive stimuli. Heat-induced nociceptive behavior in D. melanogaster larvae arises during the final (third) instar of development (Sulkowski et al., 2011). Here, we show that this behavioral transition reflects a nociceptive sensory switch through regulation of Subdued by the steroid hormone ecdysone and the EcR isoform EcR-A.

While previous studies have focused on EcR localization in the third instar and pupal stages of C4da neurons, we show EcR is present in both the nucleus and cytoplasm in the second instar, followed with an increase of EcR nuclear localization 8 hr into the third instar (Figure 2). Previous work has shown that loss of EcR-A reduces thermal nociception in the third instar (McParland et al., 2015). While we did not find detectable transcriptional changes in nociceptor genes in third instar C4da neurons during EcR-A RNAi expression, we found broad suppression of nociceptor genes during EcR ligand-binding mutant (W650A) expression (Figure 5—figure supplement 2). Through behavioral and transcriptional analysis, we show that EcR-A nociception regulation is ligand dependent, by demonstrating that increased ecdysone titer and overexpression of ligand-competent EcR both accelerate nociception in the second instar (Figures 3 and 4). Ligand binding of EcR leads to widespread epigenetic changes through release of corepressors and recruitment of coactivators (Uyehara et al., 2017; Uyehara and McKay, 2019). The precocious activation of nociception in the second instar requires the unique A/B domain of the isoform EcR-A, as other isoforms lacking this domain do not increase nociception (Figure 4A). The A/B domain of EcR-A is less activating and more repressive then the EcR-B1 A/B domain (Dela Cruz et al., 2000; Mouillet et al., 2001; Hu et al., 2003). It thus appears that ligand-dependent derepression could be the action which promotes nociception. Moreover, expression of the EcR coactivator mutant (F645A) phenocopies expression of wild-type EcR in its ability to promote nociception (Figure 4B), suggesting that in contrast to coactivator recruitment, preservation of the ability to remove corepressors is required for nociception. This regulation of repression may account for the ability of the EcR ligand-binding mutant (W650A) to suppress multiple nociceptive genes including subdued in the second and third instars. The release of corepressors could allow other transcription factors to gain access to response elements which suppress subdued, or directly promote transcription of a repressor of subdued. How derepression leads to the suppression of subdued is an intriguing open question.

For third instar larval nociception, our data suggest there are both ligand-dependent and -independent EcR-A pathways. We find third instar expression of EcR-A ligand-binding mutant to have a temperature-specific phenotype. Expression of the EcR-A ligand-binding mutant inhibits nociception at 42°C, but does not reduce nociception at 46°C (Figure 3B, D). This temperature-specific effect is reminiscent of the phenotype of TrpA1 mutant larvae, which lose nociceptive behavior at probe temperatures of 44°C and lower, but are still responsive to 46°C stimuli (Gu et al., 2019). We found that expression of EcR-A ligand-binding mutant reduced subdued expression in the third instar even more than during the developmental transition (Figure 5A, C), suggesting that this loss of subdued expression may contribute to the phenotype at 42°C but not at 46°C. Consistent with this possibility, we observed that Subdued-RNAi was able to increase nociception in second instar larvae while Subdued knockout mutation did not increase nociception. Together these results suggest that the amount of subdued expression is important for promoting or inhibiting nociception. Furthermore, there are Subdued and EcR-A ligand-independent pathways which promote nociception in the third instar. We observe alteration of TrpA1, painless, ppk1 and ppk26 expression during development but not as a result of EcR overexpression (Figure 5). These separate pathways may involve mechanisms of regulating temperature specificity in C4da neurons.

Subdued has homology to the Calcium-activated Chloride Channels (CaCC) of the mammalian TMEM16 family, with channel activity similar to both TMEM16A and TMEM16F (Wong et al., 2013; Le et al., 2019). The effect of CaCC on neural activity is dependent on the intracellular Cl⁻ concentration ([Cl⁻]_i) (Berg et al., 2012). When [Cl⁻]_i is high, elevation of internal Ca²⁺ level activates CaCCs and causes Cl⁻ efflux, leading to excitation. In contrast, when [Cl⁻]_i is low, Ca²⁺ activation of CaCCs causes an influx of Cl⁻ which has an inhibitory effect on neuronal excitability. Differential expression of symporters and cotransporters in the CNS and PNS, as well as in immature and mature neurons, is important for creating the inhibitory or excitatory effects of CaCCs. In third instar larvae, Cl⁻ efflux has been observed during thermal nociceptive stimulation of C4da neurons (Onodera et al., 2017). However, Onodera et al. found that loss of Subdued did not significantly change the magnitude of the Cl⁻ efflux during heat stimulus, suggesting other channels are responsible for the Cl⁻ efflux in third instar C4da neurons. The direction of Cl⁻ movement in the second instar remains to be determined, and it is conceivable that Subdued could produce an inhibitory influx of Cl⁻ in the second instar. Characterizing Cl⁻ homeostasis during C4da neuron development and its impact on nociception will be of interest in future studies.

Subdued has previously been found to regulate thermal nociception in third instar larvae (Jang et al., 2015). Jang et al. found the strongest decrease of nociception in the third instar when expression of subdued was reduced in all dendritic arborization neurons. Additionally, when subdued was overexpressed in C4da neurons the number of third instar larvae that responded to nociceptive heat did not significantly change. Interesting, when subdued was overexpressed with a subdued-Gal4, the number of fast responding third instar larvae increased (Jang et al., 2015). This suggests there may be a substantial thermal nociception role for Subdued in dendritic arborization neurons other than C4da neurons during third instar. Our data suggest that as C4da neurons develop from second to third instars, the ability of Subdued to influence detection of stimuli may change. We find that thermal nociception is enhanced by reduction of subdued expression in second instar C4da neurons, via either EcR-A overexpression or Subdued-RNAi knockdown. Additionally, we find that expression of the EcR-A-ligand mutant reduces subdued expression even further in third instar C4da neurons, and that this is associated with a loss of nociception. The greater amount of subdued expression in the second instar may mean that Subdued could have a greater impact on Cl⁻ regulation during the second instar. This mechanism of Subdued activity would be dependent on the intracellular Cl⁻ concentration created by symporters and cotransporters. The importance of Cl⁻ regulation has recently been highlighted in the Class III da neurons, as both Subdued and depolarizing Cl⁻ currents have recently been found to promote cold-evoked nociception (Himmel et al., 2021). Therefore, identifying regulators of Cl⁻ concentration during the development of C4da neurons and their impact on nociception will be of interest in future studies.

Our work adds to the evidence that the developmental transition of thermal nociception represents a shift in sensory state rather than a change in sensory system construction: (1) optogenetics can stimulate aversive behavior in both second and third instar C4da neurons (Sulkowski et al., 2011), (2) TrpA1 misexpression can confer nociceptive behavior in both second and third instar larvae exposed to innocuous temperatures (Luo et al., 2017), (3) UV-A stimulation induces greater Ca²⁺ response in second instar than in third instar C4da neurons (Figure 1), and (4) reduction of subdued expression in second instar renders C4da neurons responsive to thermal nociceptive stimuli (Figure 6). Additional properties of C4da neurons during this developmental transition remain to be determined. These properties include: whether thermally induced calcium activity in C4da neurons (Terada et al., 2016; Gu et al., 2019) also changes over this period of development, whether EcR regulates the ‘burst and pause’ encoding (Terada et al., 2016), and whether EcR regulation alters synaptic connections of C4da neurons (Valdes-Aleman et al., 2021).

Recent findings have highlighted the occurrence of developmentally timed modulation of sensory state in both larvae and adult Drosophila. A sensory switch in thermotaxis behavior of Drosophila larvae is regulated by transcriptional regulation of thermoreceptors (Tyrrell et al., 2021). In adults, male courtship behavior is modulated through olfactory neuron pheromone sensitivity and hormone-mediate chromatin reprograming (Zhao et al., 2020). Our study highlights that temporally programed sensory switches may be a widely used developmental mechanism to match behavioral outcomes with life history events.

We speculate that the nociceptive shift in sensory state is an important mechanism for matching sensory system function with life history transitions. D. melanogaster larvae do not develop robust thermal nociception until the second half of the larval phase. This means that for the first half of larval life, larvae do not have thermal nociception behavior. In contrast, nociceptor activity to UV-A light decreases from the second to third instars, suggesting that nociceptive sensitivity to short wavelength light decreases during the second half of the larval phase. This transition correlates with larval behavioral changes that emerge during the third instar, such as cessation of feeding beneath the surface and wandering above ground (Wegman et al., 2010). Larvae are transitioning from predominantly feeding behavior in the second instar, often shielded from light and high temperatures, to movement away from food in search of pupation sites in the third instar. In a natural habitat, this transition can mean leaving the food source, which necessitates greater exposure to heat, increasing the risk of predation and desiccation (Ballman et al., 2017). This sensory switch may function as a developmental strategy, shaping behavioral outcomes as animals encounter changing environments, thus increasing survival.

All data generated or analyzed during this study are included in the manuscript and supporting files.

1. 1. Ainsley JA
   2. Kim MJ
   3. Wegman LJ
   4. Pettus JM
   5. Johnson WA

   (2008) Sensory mechanisms controlling the timing of larval developmental and behavioral transitions require the Drosophila DEG/ENaC subunit, Pickpocket1

   Developmental Biology 322:46–55.

   https://doi.org/10.1016/j.ydbio.2008.07.003

   • PubMed
   • Google Scholar
2. 1. Almeida-Carvalho MJ
   2. Berh D
   3. Braun A
   4. Chen Y
   5. Eichler K
   6. Eschbach C
   7. Fritsch PMJ
   8. Gerber B
   9. Hoyer N
   10. Jiang X
   11. Kleber J
   12. Klämbt C
   13. König C
   14. Louis M
   15. Michels B
   16. Miroschnikow A
   17. Mirth C
   18. Miura D
   19. Niewalda T
   20. Otto N
   21. Paisios E
   22. Pankratz MJ
   23. Petersen M
   24. Ramsperger N
   25. Randel N
   26. Risse B
   27. Saumweber T
   28. Schlegel P
   29. Schleyer M
   30. Soba P
   31. Sprecher SG
   32. Tanimura T
   33. Thum AS
   34. Toshima N
   35. Truman JW
   36. Yarali A
   37. Zlatic M

   (2017) The Ol1mpiad: Concordance of behavioural faculties of stage 1 and stage 3 Drosophila larvae

   Journal of Experimental Biology 220:2452–2475.

   https://doi.org/10.1242/jeb.156646

   • PubMed
   • Google Scholar
3. 1. Arenas OM
   2. Zaharieva EE
   3. Para A
   4. Vásquez-Doorman C
   5. Petersen CP
   6. Gallio M

   (2017) Activation of planarian TRPA1 by reactive oxygen species reveals a conserved mechanism for animal nociception

   Nature Neuroscience 20:1686–1693.

   https://doi.org/10.1038/s41593-017-0005-0

   • PubMed
   • Google Scholar
4. 1. Babcock DT
   2. Landry C
   3. Galko MJ

   (2009) Cytokine Signaling Mediates UV-Induced Nociceptive Sensitization in Drosophila Larvae

   Current Biology 19:799–806.

   https://doi.org/10.1016/j.cub.2009.03.062

   • PubMed
   • Google Scholar
5. 1. Baliki MN
   2. Apkarian AV

   (2015) Nociception, Pain, Negative Moods, and Behavior Selection

   Neuron 87:474–491.

   https://doi.org/10.1016/j.neuron.2015.06.005

   • PubMed
   • Google Scholar
6. 1. Ballman ES
   2. Collins JA
   3. Drummond FA

   (2017) Pupation Behavior and Predation on Drosophila suzukii (Diptera: Drosophilidae) Pupae in Maine Wild Blueberry Fields

   Journal of Economic Entomology 110:2308–2317.

   https://doi.org/10.1093/jee/tox233

   • PubMed
   • Google Scholar
7. 1. Berg J
   2. Yang HH
   3. Jan LY

   (2012) Ca2+-activated Cl- channels at a glance

   Journal of Cell Science 125:1367–1371.

   https://doi.org/10.1242/jcs.093260

   • PubMed
   • Google Scholar
8. 1. Cherbas L
   2. Hu X
   3. Zhimulev I
   4. Belyaeva E
   5. Cherbas P

   (2003) EcR isoforms in Drosophila: Testing tissue-specific requirements by targeted blockade and rescue

   Development (Cambridge, England) 130:271–284.

   https://doi.org/10.1242/dev.00205

   • PubMed
   • Google Scholar
9. 1. Colombani J
   2. Bianchini L
   3. Layalle S
   4. Pondeville E
   5. Dauphin-Villemant C
   6. Antoniewski C
   7. Carré C
   8. Noselli S
   9. Léopold P

   (2005) Antagonistic actions of ecdysone and insulins determine final size in Drosophila

   Science (New York, N.Y.) 310:667–670.

   https://doi.org/10.1126/science.1119432

   • PubMed
   • Google Scholar
10. 1. Dela Cruz FE
    2. Kirsch DR
    3. Heinrich JN

    (2000) Transcriptional activity of Drosophila melanogaster ecdysone receptor isoforms and ultraspiracle in Saccharomyces cerevisiae

    Journal of Molecular Endocrinology 24:183–191.

    https://doi.org/10.1677/jme.0.0240183

    • PubMed
    • Google Scholar
11. 1. Ford ZK
    2. Dourson AJ
    3. Liu X
    4. Lu P
    5. Green KJ
    6. Hudgins RC
    7. Jankowski MP

    (2019) Systemic growth hormone deficiency causes mechanical and thermal hypersensitivity during early postnatal development

    IBRO Reports 6:111–121.

    https://doi.org/10.1016/j.ibror.2019.02.001

    • PubMed
    • Google Scholar
12. 1. Gorczyca DA
    2. Younger S
    3. Meltzer S
    4. Kim SE
    5. Cheng L
    6. Song W
    7. Lee HY
    8. Jan LY
    9. Jan YN

    (2014) Identification of Ppk26, a DEG/ENaC Channel Functioning with Ppk1 in a Mutually Dependent Manner to Guide Locomotion Behavior in Drosophila

    Cell Reports 9:1446–1458.

    https://doi.org/10.1016/j.celrep.2014.10.034

    • PubMed
    • Google Scholar
13. 1. Gu P
    2. Gong J
    3. Shang Y
    4. Wang F
    5. Ruppell KT
    6. Ma Z
    7. Sheehan AE
    8. Freeman MR
    9. Xiang Y

    (2019) Polymodal Nociception in Drosophila Requires Alternative Splicing of TrpA1

    Current Biology 29:3961–3973.

    https://doi.org/10.1016/j.cub.2019.09.070

    • PubMed
    • Google Scholar
14. 1. Han C
    2. Jan LY
    3. Jan YN

    (2011) Enhancer-driven membrane markers for analysis of nonautonomous mechanisms reveal neuron-glia interactions in Drosophila

    PNAS 108:9673–9678.

    https://doi.org/10.1073/pnas.1106386108

    • PubMed
    • Google Scholar
15. 1. Hill RJ
    2. Billas IML
    3. Bonneton F
    4. Graham LD
    5. Lawrence MC

    (2013) Ecdysone Receptors: From the Ashburner Model to Structural Biology

    Annual Review of Entomology 58:251–271.

    https://doi.org/10.1146/annurev-ento-120811-153610

    • PubMed
    • Google Scholar
16. 1. Himmel NJ
    2. Patel AA
    3. Cox DN
    4. Himmel NJ
    5. Patel AA
    6. Cox DN

    (2017) Invertebrate Nociception

    Oxford Research Encyclopedia of Neuroscience 1:29.

    https://doi.org/10.1093/acrefore/9780190264086.013.166

    • Google Scholar
17. 1. Himmel NJ
    2. Sakurai A
    3. Letcher JM
    4. Patel AA
    5. Bhattacharjee S
    6. Benson MN
    7. Gray TR
    8. Cymbalyuk GS
    9. Cox DN

    (2021) Chloride-dependent mechanisms of multimodal sensory discrimination and neuropathic sensitization in Drosophila

    Neuroscience 10:472093.

    https://doi.org/10.1101/2021.12.10.472093

    • Google Scholar
18. 1. Hiura A
    2. López Villalobos E
    3. Ishizuka H

    (1992) Age-dependent attenuation of the decrease of c fibers by capsaicin and its effects on responses to nociceptive stimuli

    Somatosensory & Motor Research 9:37–43.

    https://doi.org/10.3109/08990229209144761

    • PubMed
    • Google Scholar
19. 1. Honjo K
    2. Mauthner SE
    3. Wang Y
    4. Skene JHP
    5. Tracey WD

    (2016) Nociceptor-Enriched Genes Required for Normal Thermal Nociception

    Cell Reports 16:295–303.

    https://doi.org/10.1016/j.celrep.2016.06.003

    • PubMed
    • Google Scholar
20. 1. Hu X
    2. Cherbas L
    3. Cherbas P

    (2003) Transcription Activation by the Ecdysone Receptor (EcR/USP): Identification of Activation Functions

    Molecular Endocrinology (Baltimore, Md.) 17:716–731.

    https://doi.org/10.1210/me.2002-0287

    • PubMed
    • Google Scholar
21. 1. Hwang RY
    2. Zhong L
    3. Xu Y
    4. Johnson T
    5. Zhang F
    6. Deisseroth K
    7. Tracey WD

    (2007) Nociceptive Neurons Protect Drosophila Larvae from Parasitoid Wasps

    Current Biology 17:2105–2116.

    https://doi.org/10.1016/j.cub.2007.11.029

    • PubMed
    • Google Scholar
22. 1. Jang W
    2. Kim JY
    3. Cui S
    4. Jo J
    5. Lee BCC
    6. Lee Y
    7. Kwon KSS
    8. Park CSS
    9. Kim C

    (2015) The anoctamin family channel subdued mediates thermal nociception in Drosophila

    The Journal of Biological Chemistry 290:2521–2528.

    https://doi.org/10.1074/jbc.M114.592758

    • PubMed
    • Google Scholar
23. 1. Jankowski MP
    2. Ross JL
    3. Weber JD
    4. Lee FB
    5. Shank AT
    6. Hudgins RC

    (2014) Age-dependent sensitization of cutaneous nociceptors during developmental inflammation

    Molecular Pain 10:1–18.

    https://doi.org/10.1186/1744-8069-10-34

    • PubMed
    • Google Scholar
24. 1. Kannangara JR
    2. Mirth CK
    3. Warr CG

    (2021) Regulation of ecdysone production in Drosophila by neuropeptides and peptide hormones

    Open Biology 11:200373.

    https://doi.org/10.1098/rsob.200373

    • PubMed
    • Google Scholar
25. 1. Kim SE
    2. Coste B
    3. Chadha A
    4. Cook B
    5. Patapoutian A

    (2012) The role of Drosophila Piezo in mechanical nociception

    Nature 483:209–212.

    https://doi.org/10.1038/nature10801

    • PubMed
    • Google Scholar
26. 1. Kirilly D
    2. Gu Y
    3. Huang Y
    4. Wu Z
    5. Bashirullah A
    6. Low BC
    7. Kolodkin AL
    8. Wang H
    9. Yu F

    (2009) A genetic pathway composed of Sox14 and Mical governs severing of dendrites during pruning

    Nature Neuroscience 12:1497–1505.

    https://doi.org/10.1038/nn.2415

    • PubMed
    • Google Scholar
27. 1. Kuo CT
    2. Jan LY
    3. Jan YN

    (2005) Dendrite-specific remodeling of Drosophila sensory neurons requires matrix metalloproteases, ubiquitin-proteasome, and ecdysone signaling

    PNAS 102:15230–15235.

    https://doi.org/10.1073/pnas.0507393102

    • PubMed
    • Google Scholar
28. 1. Le T
    2. Le SC
    3. Yang H

    (2019) Drosophila Subdued is a moonlighting transmembrane protein 16 (TMEM16) that transports ions and phospholipids

    The Journal of Biological Chemistry 294:4529–4537.

    https://doi.org/10.1074/jbc.AC118.006530

    • PubMed
    • Google Scholar
29. 1. Liu L
    2. Yermolaieva O
    3. Johnson WA
    4. Abboud FM
    5. Welsh MJ

    (2003) Identification and function of thermosensory neurons in Drosophila larvae

    Nature Neuroscience 6:267–273.

    https://doi.org/10.1038/nn1009

    • PubMed
    • Google Scholar
30. 1. Liu X
    2. Green KJ
    3. Ford ZK
    4. Queme LF
    5. Lu P
    6. Ross JL
    7. Lee FB
    8. Shank AT
    9. Hudgins RC
    10. Jankowski MP

    (2017) Growth hormone regulates the sensitization of developing peripheral nociceptors during cutaneous inflammation

    Pain 158:333–346.

    https://doi.org/10.1097/j.pain.0000000000000770

    • PubMed
    • Google Scholar
31. 1. Luo J
    2. Shen WL
    3. Montell C

    (2017) TRPA1 mediates sensation of the rate of temperature change in Drosophila larvae

    Nature Neuroscience 20:34–41.

    https://doi.org/10.1038/nn.4416

    • PubMed
    • Google Scholar
32. 1. Mauthner SE
    2. Hwang RY
    3. Lewis AH
    4. Xiao Q
    5. Tsubouchi A
    6. Wang Y
    7. Honjo K
    8. Skene J
    9. Grandl J
    10. Tracey WD

    (2014) Balboa binds to pickpocket in vivo and is required for mechanical nociception in Drosophila larvae

    Current Biology 24:2920–2925.

    https://doi.org/10.1016/j.cub.2014.10.038

    • PubMed
    • Google Scholar
33. 1. McParland AL
    2. Follansbee TL
    3. Vesenka GD
    4. Panaitiu AE
    5. Ganter GK

    (2015) Steroid receptor isoform expression in Drosophila nociceptor neurons is required for normal dendritic arbor and sensitivity

    PLOS ONE 10:140785.

    https://doi.org/10.1371/journal.pone.0140785

    • PubMed
    • Google Scholar
34. 1. Mouillet JF
    2. Henrich VC
    3. Lezzi M
    4. Vögtli M

    (2001)

    Differential control of gene activity by isoforms A, B1 and B2 of the Drosophila ecdysone receptor

    European Journal of Biochemistry 268:1811–1819.

    • PubMed
    • Google Scholar
35. 1. Nieva C
    2. Spindler-Barth M
    3. Azoitei A
    4. Spindler KD

    (2007) Influence of hormone on intracellular localization of the Drosophila melanogaster ecdysteroid receptor (EcR)

    Cellular Signalling 19:2582–2587.

    https://doi.org/10.1016/j.cellsig.2007.08.007

    • PubMed
    • Google Scholar
36. 1. Nieva C
    2. Spindler-Barth M
    3. Spindler KD

    (2008) Impact of heterodimerization on intracellular localization of the Ecdysteroid Receptor (EcR)

    Archives of Insect Biochemistry and Physiology 68:40–48.

    https://doi.org/10.1002/arch.20234

    • PubMed
    • Google Scholar
37. 1. Onodera K
    2. Baba S
    3. Murakami A
    4. Uemura T
    5. Usui T

    (2017) Small conductance Ca2+-activated K+ channels induce the firing pause periods during the activation of Drosophila nociceptive neurons

    eLife 6:e29754.

    https://doi.org/10.7554/eLife.29754

    • Google Scholar
38. 1. Orefice LLL
    2. Zimmerman ALL
    3. Chirila AMM
    4. Sleboda SJJ
    5. Head JPP
    6. Ginty DDD

    (2016) Peripheral Mechanosensory Neuron Dysfunction Underlies Tactile and Behavioral Deficits in Mouse Models of ASDs

    Cell 166:299–313.

    https://doi.org/10.1016/j.cell.2016.05.033

    • PubMed
    • Google Scholar
39. 1. Ou Y
    2. Chwalla B
    3. Landgraf M
    4. van Meyel DJ

    (2008) Identification of genes influencing dendrite morphogenesis in developing peripheral sensory and central motor neurons

    Neural Development 3:1–27.

    https://doi.org/10.1186/1749-8104-3-16

    • PubMed
    • Google Scholar
40. 1. Parrish JZ
    2. Kim CC
    3. Tang L
    4. Bergquist S
    5. Wang T
    6. Derisi JL
    7. Jan LY
    8. Jan YN
    9. Davis GW

    (2014) Kruppel Mediates the Selective Rebalancing of Ion Channel Expression

    Neuron 82:537–544.

    https://doi.org/10.1016/j.neuron.2014.03.015

    • PubMed
    • Google Scholar
41. 1. Rewitz KF
    2. Yamanaka N
    3. O’Connor MB

    (2013) Developmental Checkpoints and Feedback Circuits Time Insect Maturation

    Current Topics in Developmental Biology 103:1–33.

    https://doi.org/10.1016/B978-0-12-385979-2.00001-0

    • PubMed
    • Google Scholar
42. 1. Schubiger M
    2. Tomita S
    3. Sung C
    4. Robinow S
    5. Truman JW

    (2003) Isoform specific control of gene activity in vivo by the Drosophila ecdysone receptor

    Mechanisms of Development 120:909–918.

    https://doi.org/10.1016/s0925-4773(03)00134-5

    • PubMed
    • Google Scholar
43. 1. Sharma N
    2. Flaherty K
    3. Lezgiyeva K
    4. Wagner DE
    5. Klein AM
    6. Ginty DD

    (2020) The emergence of transcriptional identity in somatosensory neurons

    Nature 577:392–398.

    https://doi.org/10.1038/s41586-019-1900-1

    • PubMed
    • Google Scholar
44. 1. Sokabe T
    2. Tsujiuchi S
    3. Kadowaki T
    4. Tominaga M

    (2008) Drosophila painless is a Ca2+-requiring channel activated by noxious heat

    The Journal of Neuroscience 28:9929–9938.

    https://doi.org/10.1523/JNEUROSCI.2757-08.2008

    • PubMed
    • Google Scholar
45. 1. Sulkowski MJ
    2. Kurosawa MS
    3. Cox DN

    (2011) Growing pains: Development of the larval nocifensive response in Drosophila

    The Biological Bulletin 221:300–306.

    https://doi.org/10.1086/BBLv221n3p300

    • PubMed
    • Google Scholar
46. 1. Sullivan AA
    2. Thummel CS

    (2003) Temporal Profiles of Nuclear Receptor Gene Expression Reveal Coordinate Transcriptional Responses during Drosophila Development

    Molecular Endocrinology (Baltimore, Md.) 17:2125–2137.

    https://doi.org/10.1210/me.2002-0430

    • PubMed
    • Google Scholar
47. 1. Terada SI
    2. Matsubara D
    3. Onodera K
    4. Matsuzaki M
    5. Uemura T
    6. Usui T

    (2016) Neuronal processing of noxious thermal stimuli mediated by dendritic ca2+ influx in Drosophila somatosensory neurons

    eLife 5:e12959.

    https://doi.org/10.7554/eLife.12959

    • PubMed
    • Google Scholar
48. 1. Tracey WD
    2. Wilson RI
    3. Laurent G
    4. Benzer S

    (2003) painless, a Drosophila gene essential for nociception

    Cell 113:261–273.

    https://doi.org/10.1016/s0092-8674(03)00272-1

    • PubMed
    • Google Scholar
49. 1. Tyrrell JJ
    2. Wilbourne JT
    3. Omelchenko AA
    4. Yoon J
    5. Ni L

    (2021) Ionotropic Receptor-dependent cool cells control the transition of temperature preference in Drosophila larvae ed

    PLOS Genetics 17:e1009499.

    https://doi.org/10.1371/journal.pgen.1009499

    • PubMed
    • Google Scholar
50. 1. Uyehara CM
    2. Nystrom SL
    3. Niederhuber MJ
    4. Leatham-Jensen M
    5. Ma Y
    6. Buttitta LA
    7. McKay DJ

    (2017) Hormone-dependent control of developmental timing through regulation of chromatin accessibility

    Genes & Development 31:862–875.

    https://doi.org/10.1101/gad.298182.117

    • PubMed
    • Google Scholar
51. 1. Uyehara CM
    2. McKay DJ

    (2019) Direct and widespread role for the nuclear receptor EcR in mediating the response to ecdysone in Drosophila

    PNAS 116:9893–9902.

    https://doi.org/10.1073/pnas.1900343116

    • PubMed
    • Google Scholar
52. 1. Valdes-Aleman J
    2. Fetter RD
    3. Sales EC
    4. Heckman EL
    5. Venkatasubramanian L
    6. Doe CQ
    7. Landgraf M
    8. Cardona A
    9. Zlatic M

    (2021) Comparative Connectomics Reveals How Partner Identity, Location, and Activity Specify Synaptic Connectivity in Drosophila

    Neuron 109:105–122.

    https://doi.org/10.1016/j.neuron.2020.10.004

    • PubMed
    • Google Scholar
53. 1. Warren JT
    2. Yerushalmi Y
    3. Shimell MJ
    4. O’Connor MB
    5. Restifo LL
    6. Gilbert LI

    (2006) Discrete pulses of molting hormone, 20-hydroxyecdysone, during late larval development of Drosophila melanogaster: Correlations with changes in gene activity

    Developmental Dynamics 235:315–326.

    https://doi.org/10.1002/dvdy.20626

    • PubMed
    • Google Scholar
54. 1. Wegman LJ
    2. Ainsley JA
    3. Johnson WA

    (2010) Developmental timing of a sensory-mediated larval surfacing behavior correlates with cessation of feeding and determination of final adult size

    Developmental Biology 345:170–179.

    https://doi.org/10.1016/j.ydbio.2010.07.004

    • PubMed
    • Google Scholar
55. 1. Wong XM
    2. Younger S
    3. Peters CJ
    4. Jan YN
    5. Jan LY

    (2013) Subdued, a TMEM16 family Ca2+ -activated Cl− channel in Drosophila melanogaster with an unexpected role in host defense

    eLife 2013:e00862.

    https://doi.org/10.7554/eLife.00862

    • Google Scholar
56. 1. Xiang Y
    2. Yuan Q
    3. Vogt N
    4. Looger LL
    5. Jan LY
    6. Jan YN

    (2010) Light-avoidance-mediating photoreceptors tile the Drosophila larval body wall

    Nature 468:921–926.

    https://doi.org/10.1038/nature09576

    • PubMed
    • Google Scholar
57. 1. Yadav S
    2. Younger SH
    3. Zhang L
    4. Thompson-Peer KL
    5. Li T
    6. Jan LY
    7. Jan YN

    (2019) Glial ensheathment of the somatodendritic compartment regulates sensory neuron structure and activity

    PNAS 116:5126–5134.

    https://doi.org/10.1073/pnas.1814456116

    • PubMed
    • Google Scholar
58. 1. Yamanaka N
    2. Romero NM
    3. Martin FA
    4. Rewitz KF
    5. Sun M
    6. O’Connor MB
    7. Léopold P

    (2013) Neuroendocrine Control of Drosophila Larval Light Preference

    Science (New York, N.Y.) 341:1113–1116.

    https://doi.org/10.1126/science.1241210

    • PubMed
    • Google Scholar
59. 1. Zhao S
    2. Deanhardt B
    3. Barlow GT
    4. Schleske PG
    5. Rossi AM
    6. Volkan PC
    7. Volkan PC

    (2020) Chromatin-based reprogramming of a courtship regulator by concurrent pheromone perception and hormone signaling

    Science Advances 6:eaba6913.

    https://doi.org/10.1126/sciadv.aba6913

    • PubMed
    • Google Scholar
60. 1. Zhong L
    2. Hwang RY
    3. Tracey WD

    (2010) Pickpocket Is a DEG/ENaC Protein Required for Mechanical Nociception in Drosophila Larvae

    Current Biology 20:429–434.

    https://doi.org/10.1016/j.cub.2009.12.057

    • PubMed
    • Google Scholar
61. 1. Zhong L
    2. Bellemer A
    3. Yan H
    4. Ken H
    5. Jessica R
    6. Hwang RY
    7. Pitt GS
    8. Tracey WD

    (2012) Thermosensory and Nonthermosensory Isoforms of Drosophila melanogaster TRPA1 Reveal Heat-Sensor Domains of a ThermoTRP Channel

    Cell Reports 1:43–55.

    https://doi.org/10.1016/j.celrep.2011.11.002

    • PubMed
    • Google Scholar

Author details

1. Jacob S Jaszczak

   1. Department of Physiology, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
   2. Howard Hughes Medical Institute, Chevy Chase, United States

   Contribution

   Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Resources, Validation, Visualization, Writing - original draft, Writing - review and editing

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0003-3752-1152

2. Laura DeVault

   1. Department of Physiology, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
   2. Department of Developmental Biology, Washington University Medical School, Saint Louis, United States

   Contribution

   Data curation, Investigation, Methodology, Validation, Writing - review and editing

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0001-6801-5098

3. Lily Yeh Jan

   1. Department of Physiology, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
   2. Howard Hughes Medical Institute, Chevy Chase, United States

   Contribution

   Funding acquisition, Writing - review and editing

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0003-3938-8498

4. Yuh Nung Jan

   1. Department of Physiology, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
   2. Howard Hughes Medical Institute, Chevy Chase, United States

   Contribution

   Funding acquisition, Methodology, Supervision, Writing - review and editing

   For correspondence

   YuhNung.Jan@ucsf.edu

   Competing interests

   No competing interests declared

   "This ORCID iD identifies the author of this article:" 0000-0003-1367-6299

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