Stimulation of trehalose efflus from cockroach(periplaneta americana)fat body by hypertrehalosemic hormone is dependent on protein kinase C and calmodulin

摘要

Protein kinase C and calmodulin play key roles in cockroach fat body during activation of phosphorylase and trehalose afflux by HTH-ll.The data support the view that an increase in cytosolic Ca~(2+) is prerequistite for enhanced activity of protein kinase C and calmodulin.Chelation of Ca~(2+),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,and inhibitor of protein kinase C,inhibits HTH-II-induced trehalose efflux in a concentration-dependent manner.Trehalose efflus 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 indistinngishable from that provoked by HTH-II.Each of the structurally different calmodulin inhibitors,trifuoperazine,W-7,nd calmidazolium,blocks completely the actionof HTH-II on trehalose efflux,thus confirming the importance of calmodulin in HTH-II initiated trehalose efflux.