Stimulation of trehalose efflux from cockroach (Periplaneta americana) fat body by hypertrehalosemic hormone is dependent on protein kinase C and calmodulin.
Protein kinase C and calmodulin play key roles in cockroach fat body during activation of phosphorylase and trehalose efflux by HTH-II. The data support the view that an increase in cytosolic Ca2+ is prerequisite for enhanced activity of protein kinase C and calmodulin. Chelation of Ca2+ (i) with BAPTA blocks HTH-II-induced trehalose efflux from the fat body whereas thapsigargin, which raises [Ca2+]i to the same level as HTH-II, produces only a small, yet significant increase in trehalose efflux. Sphingosine, an inhibitor of protein kinase C, inhibits HTH-II-induced trehalose efflux in a concentration-dependent manner. Trehalose efflux is not activated by the protein kinase C activators OAG or PMA alone but in the presence of thapsigargin both agents increase trehalose efflux to a level comparable to that obtained with HTH-II. Thapsigargin has only a moderate activating effect on phosphorylase but in combination with OAG produces an activation indistinguishable from that provoked by HTH-II. Each of the structurally different calmodulin inhibitors, trifluoperazine, W-7, and calmidazolium, blocks completely the action of HTH-II on trehalose efflux, thus confirming the importance of calmodulin in HTH-II initiated trehalose efflux.
Sun
D
D
Department of Zoology, The University of Western Ontario, London, Ontario, Canada.
Garcha
K
K
Steele
J E
JE
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology; D004075:Diglycerides / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005216:Fat Body / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D009479:Neuropeptides / Q000378:metabolism*; D010526:Periplaneta / Q000201:enzymology / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013110:Sphingosine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014199:Trehalose / Q000096:biosynthesis / Q000378:metabolism*; D014268:Trifluoperazine / Q000494:pharmacology
D002147:Calmodulin; D002614:Chelating Agents; D004075:Diglycerides; D004791:Enzyme Inhibitors; D009479:Neuropeptides; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D014268:Trifluoperazine; D004533:Egtazic Acid; D019284:Thapsigargin; C038237:1-oleoyl-2-acetylglycerol; C043191:glutamyl-leucyl-threonyl-phenylalanyl-threonyl-prolyl-asparaginyl-tryptophanamide; D014199:Trehalose; D006005:Phosphorylases; D011493:Protein Kinase C; D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium