Diflubenzuron-induced changes in activities of the cAMP-dependent protein kinase in the newly molted integument of the American cockroach in situ and in cell free conditions

Abstract

Benzoylurea-type compounds are a new class of powerful insecticides/growth regulators known to cause chitin-synthesis inhibition in vivo. We have found by using the isolated integument from the freshly molted American cockroach that diflubenzuron (Dimilin®) and its active analogs cause a rise in cAMP-dependent protein kinase activity, both in intact and homogenized ( cell free) systems. Such a cAMP-dependent protein kinase has been found to be particularly active in the integument during molting. The effect of diflubenzuron in isolated intact epidermis was observed at the 10 nM range, occurring with only active diflubenzuron analogs. At the same time, DFB was found to cause changes in protein phosphorylation on a few specific proteins both in situ and in cell free conditions in the concentration range of 10 nM to 10 μM. The possibility that the action of diflubenzuron on chitin biosynthesis is directly or indirectly mediated through modulation of cAMP-dependent protein kinase system was discussed.