Calcium-dependent action of hypertrehalosemic hormone on activation of glycogen phosphorylase in cockroach fat body.
Signaling mechanisms for Blaberus discoidalis hypertrehalosemic hormone (Bld-HrTH)-dependent glycogen phosphorylase activation were investigated in vitro using fat body of the tropical cockroach, B. discoidalis. Brief treatment of fat bodies with Bld-HrTH in the absence of extracellular Ca2+ showed a significant activation of phosphorylase. Although extracellular Ca2+ was required for a full activation of phosphorylase by Bld-HrTH, stimulation in the absence of extracellular Ca2+ suggested that intracellular Ca2+ was also involved in Bld-HrTH signal transduction. Thapsigargin and thimerosal mobilize Ca2+ from intracellular stores by different mechanisms, and both chemicals stimulated phosphorylase activities as effectively as a maximum dose of Bld-HrTH. Bld-HrTH likely induces intracellular Ca2+ release followed by extracellular Ca2+ entry across the plasma membrane. Inositol-1,4,5-trisphosphate (InsP3) levels were greatly increased by Bld HrTH in a time- and dose-dependent manner, suggesting that InsP3 might be a Ca(2+)-mobilizing intracellular second messenger for Bld-HrTH.
Park
J H
JH
Department of Entomology, Texas A&M University Texas Agricultural Experimental Station, College Station 77843, USA.
Keeley
L L
LL
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D003058:Cockroaches; D004789:Enzyme Activation / Q000187:drug effects; D005216:Fat Body / Q000201:enzymology*; D006003:Glycogen / Q000378:metabolism; D007301:Insect Hormones / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology*; D006005:Phosphorylases / Q000378:metabolism*; D015290:Second Messenger Systems
D007301:Insect Hormones; D009479:Neuropeptides; C084112:hypertrehalosemic hormone; D000001:Calcimycin; D006003:Glycogen; D006005:Phosphorylases; D002118:Calcium