Targeted inactivation of the rickets receptor in muscle compromisesDrosophilaviability

Abstract

Bursicon is a hormone that modulates wing expansion, cuticle hardening and melanization in Drosophila melanogaster. Bursicon activity is mediated through its cognate G protein-coupled receptor (GPCR), rickets. We have developed a membrane-tethered bursicon construct that enables spatial modulation of rickets-mediated physiology in transgenic flies. Ubiquitous expression of tethered bursicon throughout development results in arrest at the pupal stage. The few organisms that eclose fail to undergo wing expansion. These phenotypes suggest that expression of tethered bursicon inhibits rickets-mediated function. Consistent with this hypothesis, we show in vitro that sustained stimulation of rickets by tethered bursicon leads to receptor desensitization. Furthermore, tissue-specific expression of the tethered bursicon inhibitor unraveled a critical role for rickets in a subset of adult muscles. Taken together, our findings highlight the utility of membrane-tethered inhibitors as important genetic/ pharmacological tools to dissect the tissue-specific roles of GPCRs in vivo.

A novel function of bursicon in stimulation of vitellogenin expression in black tiger shrimp, Penaeus monodon

“…Interestingly, a specific bursicon receptor was identified in D. melanogaster to be a leucinerich repeated GPCR type 2, and binding of recombinant bursicon to the receptor triggered cAMP production resulting in cuticle tanning stimulation (Luo et al, 2005). Besides, the expression of the bursiconspecific receptor was found in nervous tissues (Diao and White, 2012), epidermis (Davis et al, 2007) and muscle (Harwood et al, 2014). Similarly, the FlyAtlas database revealed that the bursicon receptor was expressed in several tissues including brain, thoracic ganglia, fat body, ovary and testis in adult D. melanogaster (Chintapalli et al, 2007).…”

The tanning hormone, bursicon, does not act directly on the epidermis to tan the Drosophila exoskeleton

“…Loss of RK function prevents cuticle sclerotization and delays the melanization of the adult fly but eventually results in a darker than normal exoskeleton Flies trans-heterozygous for loss-of-function rk mutations (rk 1 /rk 4 ) do not expand their wings, present an abnormal body shape and fail to melanize properly [9]. A comparable result was obtained when a rk RNAi or a membrane tethered bursicon hormone transgene (here called tBur), which acts as a dominant negative rk allele [16,17], was expressed in all rk-expressing cells using a rk-GAL4 driver ( Fig. 1a,b; results shown for female flies; similar results were obtained with adult male flies, Additional file 1: Figure S1).…”

Novel Probes Establish Mas-Related G Protein-Coupled Receptor X1 Variants as Receptors with Loss or Gain of Function

“…As illustrated, such modified peptide ligands exhibit enhanced effective concentration and thus provide experimental tools that facilitate the pharmacologic characterization of GPCRs. In addition, MTLs can be expressed as transgenic constructs enabling exploration of corresponding receptor function in vivo (Harwood et al, 2014). Complementing such recombinant constructs, lipidated peptides provide additional tools that can be applied in vivo to probe receptor function and validate potential therapeutic targets (Doyle et al, 2014).…”