Corazonin receptor signaling in ecdysis initiation

Area of Science:

• Neuroendocrinology
• Insect Physiology
• Molecular Biology

Background:

• Corazonin is a conserved insect neuropeptide with an undefined function.
• The corazonin receptor was previously identified in Drosophila.
• Understanding corazonin's role is crucial for insect development studies.

Purpose of the Study:

• To identify and characterize the corazonin receptor in Manduca sexta.
• To investigate the physiological role of corazonin signaling in insect ecdysis.
• To elucidate the mechanism of corazonin action on Inka cells.

Main Methods:

• Corazonin receptor ortholog identification and cDNA sequencing in Manduca sexta.
• Receptor expression and functional analysis in Xenopus oocytes and CHO cells.
• Northern blot analysis for receptor localization.
• In vivo and in vitro experiments involving corazonin injection and Inka cell exposure.
• Hemolymph corazonin concentration measurement using the receptor as a biosensor.

Main Results:

• The Manduca sexta corazonin receptor cDNA encodes a 436-amino acid protein with seven transmembrane domains.
• The receptor demonstrates high sensitivity and selectivity for corazonin (EC50 ~75-200 pM).
• Receptor expression is localized to peripheral endocrine Inka cells.
• Corazonin injection induces precocious preecdysis and ecdysis behaviors.
• Corazonin stimulates preecdysis- and ecdysis-triggering hormone release from Inka cells.
• Hemolymph corazonin levels peak before natural preecdysis onset.

Conclusions:

• Corazonin signaling plays a key role in initiating the insect ecdysis behavioral sequence.
• Corazonin acts on Inka cells to trigger the release of ecdysis-regulating hormones.
• A model of peptide-mediated interactions between Inka cells and the CNS is proposed for insect development.