Premium
Stimulation of trehalose efflux from cockroach ( Periplaneta americana ) fat body by hypertrehalosemic hormone is dependent on protein kinase C and calmodulin
Author(s) -
Garcha D. Sun, K.,
Steele J.E.
Publication year - 2002
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.10028
Subject(s) - trehalose , efflux , biology , thapsigargin , periplaneta , calmodulin , biochemistry , trehalase , protein kinase a , kinase , cockroach , extracellular , enzyme , ecology
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 Ca 2+ is prerequisite for enhanced activity of protein kinase C and calmodulin. Chelation of Ca 2+ i with BAPTA blocks HTH‐II‐induced trehalose efflux from the fat body whereas thapsigargin, which raises [Ca 2+ ] 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. Arch. Insect Biochem. Physiol. 50:41–51, 2002. © 2002 Wiley‐Liss, Inc.