Transcriptional expression of bursicon and novel bursicon-regulated genes in the house fly Musca domestica.

Bursicon is a neuropeptide that regulates cuticle sclerotization (hardening and tanning) via a G protein-coupled receptor. It consists of two subunits, an alpha and a beta. In the present study, we investigated the transcriptional expression and in situ localization of bursicon alpha and beta in the central nerve system of the house fly Musca domestica. Most importantly, we identified two novel bursicon-regulated genes using recombinant bursicon (rbursicon) heterodimer in a neck-ligated house fly assay. RT-PCR analysis revealed that both bursicon alpha and beta subunits were present in the central nerve system of larval and pupal stages, reached the maximal level in pharate adults, and declined sharply after adult emergence, suggesting the release of the hormone upon adult emergence. In situ localization of bursicon transcripts showed that both bursicon alpha and beta transcripts were expressed in a set of neurosecretory cells (NSCs) in the thoracic-abdominal ganglia of M. domestica. Two Drosophila melanogaster homologous genes, designated CG7985hh and CG30287hh, were up-regulated by rbursicon in a time-dependent manner and verified by real-time PCR, implying their involvement in the cuticle tanning process.