HAN, D.W.*; WATSON, R.D.; University of Alabama at Birmingham; University of Alabama at Birmingham: Effect of Cyclic AMP on Protein Synthesis in Crustacean (Callinectes sapidus) Y-Organs

Paired Y-organs secrete ecdysteroid hormones that control cycles of growth and molting in crustaceans. Y-Organs are regulated, at least in part, by molt-inhibiting hormone (MIH), a peptide produced and released by the X-organ/sinus gland complex of the eyestalks. We are investigating cellular signaling pathways involved in regulation of Y-organ function. In the present studies, Y-organs were incubated in vitro in the presence of ³⁵S-methionine and experimental agents that influence the cyclic AMP (cAMP) signaling pathway. In 4-hr incubations, 8-Br-cAMP (a cAMP analog) suppressed incorporation of ³⁵S-met into Y-organ proteins; the effect was concentration-dependent. Addition of cholera toxin (a Gs protein activator), IBMX (a phosphodiesterase inhibitor), or forskolin (a adenylyl cyclase activator) likewise suppressed incorporation of ³⁵S-met into Y-organ proteins. The effect of cholera toxin was antagonized by KT5720 (a protein kinase A inhibitor). Incorporation of ³⁵S-met into Y-organ proteins was also suppressed by an extract of sinus glands. The combined results suggest that cAMP plays an important role in regulation of Y-organ function. We are currently investigating the link of protein synthesis to ecdysteroid production, and the possibility of cross-talk between cAMP and other cellular signaling pathways in Y-organs. Supported by the National Science Foundation (IBN-0213047).