Functional Dissection of a Neuronal Network Required for Cuticle Tanning and Wing Expansion inDrosophila

Abstract

A subset of Drosophila neurons that expresses crustacean cardioactive peptide (CCAP) has been shown previously to make the hormone bursicon, which is required for cuticle tanning and wing expansion after eclosion. Here we present evidence that CCAP-expressing neurons (N CCAP ) consist of two functionally distinct groups, one of which releases bursicon into the hemolymph and the other of which regulates its release. The first group, which we call N CCAP -c929, includes 14 bursicon-expressing neurons of the abdominal ganglion that lie within the expression pattern of the enhancer-trap line c929-Gal4. We show that suppression of activity within this group blocks bursicon release into the hemolymph together with tanning and wing expansion. The second group, which we call N CCAP -R, consists of N CCAP neurons outside the c929-Gal4 pattern. Because suppression of synaptic transmission and protein kinase A (PKA) activity throughout N CCAP , but not in N CCAP -c929, also blocks tanning and wing expansion, we conclude that neurotransmission and PKA are required in N CCAP -R to regulate bursicon secretion from N CCAP -c929. Enhancement of electrical activity in N CCAP -R by expression of the bacterial sodium channel NaChBac also blocks tanning and wing expansion and leads to depletion of bursicon from central processes. NaChBac expression in N CCAP -c929 is without effect, suggesting that the abdominal bursicon-secreting neurons are likely to be silent until stimulated to release the hormone. Our results suggest that N CCAP form an interacting neuronal network responsible for the regulation and release of bursicon and suggest a model in which PKA-mediated stimulation of inputs to normally quiescent bursicon-expressing neurons activates release of the hormone.

Functional study of hyperpolarization activated channel (I h ) in Drosophila behavior

“…In an effort to reveal the function of those neurons labeled by I h -Gal4 line, the bacterial sodium channel (NaChBac) was over-expressed in such neurons to elevate the level of their neuronal activity [13][14][15]. Such manipulation resulted in wing extension defect.…”

“…The wing phenotype was analyzed as described [13], including normally extended wings (EW), partially extended wings (PEW), or un-extended wings (UW).…”

Mitochondrial retrograde signaling regulates neuronal function

“…S1D) and lethality with mitoXhoI expression. The D42-Gal4 driver is also expressed in the crustacean cardioactive peptide (CCAP) neurons that secrete and regulate the release of the neuropeptide bursicon, which activates wing inflation (14,15). Blocking bursicon release into the hemolymph by inhibition of CCAP neuronal activity causes failure of wing inflation.…”

Combinatorial methods for refined neuronal gene targeting

“…To obtain complete suppression of Gal4 activity, a prerequisite for successful use of the system, the authors used multiple copies of the Gal80 transgenes. Directed expression of Gal80 using other promoters subsequently has been used to restrict expression of several UAS-transgenes to study such issues as learning and memory [37 ] and developmentally programmed behaviors [38 ].…”

“…Lerchner W, Xiao C, Nashmi R, Slimko EM, van Trigt L, Lester HA, Anderson DJ: Reversible silencing of neuronal excitability in behaving mice by a genetically targeted, ivermectin-gated Cl-channel. Neuron 2007, 54: [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]. This paper introduces a technique for reversibly silencing neuronal activity using a glutamate-and ivermectin (IVM)-gated chloride channel encoded by two subunits.…”