title: Phthalic acid diamides activate ryanodine-sensitive Ca2+ release channels in insects.
abstract: Flubendiamide represents a novel chemical family of substituted phthalic acid diamides with potent insecticidal activity. So far, the molecular target and the mechanism of action were not known. Here we present for the first time evidence that phthalic acid diamides activate ryanodine-sensitive intracellular calcium release channels (ryanodine receptors, RyR) in insects. With Ca(2+) measurements, we showed that flubendiamide and related compounds induced ryanodine-sensitive cytosolic calcium transients that were independent of the extracellular calcium concentration in isolated neurons from the pest insect Heliothis virescens as well as in transfected CHO cells expressing the ryanodine receptor from Drosophila melanogaster. Binding studies on microsomal membranes from Heliothis flight muscles revealed that flubendiamide and related compounds interacted with a site distinct from the ryanodine binding site and disrupted the calcium regulation of ryanodine binding by an allosteric mechanism. This novel insecticide mode of action seems to be restricted to specific RyR subtypes because the phthalic acid diamides reported here had almost no effect on mammalian type 1 ryanodine receptors.
authors.affiliation: Bayer CropScience AG, Alfred-Nobel-Strasse 50, D-40789 Monheim, Germany. ulrich.ebbinghaus-kintscher@bayercropscience.com
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ebbinghaus-Kintscher
authors.forename: Peter
authors.initials: P
authors.lastname: Luemmen
authors.forename: Nicole
authors.initials: N
authors.lastname: Lobitz
authors.forename: Thomas
authors.initials: T
authors.lastname: Schulte
authors.forename: Christian
authors.initials: C
authors.lastname: Funke
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Fischer
authors.forename: Takao
authors.initials: T
authors.lastname: Masaki
authors.forename: Noriaki
authors.initials: N
authors.lastname: Yasokawa
authors.forename: Masanori
authors.initials: M
authors.lastname: Tohnishi
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D016466:CHO Cells; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D003600:Cytosol / Q000378:metabolism; D003958:Diamide / Q000494:pharmacology*; D004331:Drosophila melanogaster; D016257:Fura-2; D007425:Intracellular Membranes / Q000737:chemistry; D047028:Macrocyclic Compounds; D051379:Mice; D008856:Microscopy, Fluorescence; D009036:Moths / Q000378:metabolism*; D009132:Muscles / Q000737:chemistry / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D010080:Oxazoles / Q000494:pharmacology; D012433:Ryanodine / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects* / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology; D014162:Transfection; D005466:Fluorocarbons; D010797:Phthalimides
chemical_list: D001549:Benzamides; D002110:Caffeine; D002118:Calcium; D003958:Diamide; D016257:Fura-2; D047028:Macrocyclic Compounds; D010080:Oxazoles; D012433:Ryanodine; D019837:Ryanodine Receptor Calcium Release Channel; D013450:Sulfones; C108644:xestospongin A; C508762:flubendiamide; D005466:Fluorocarbons; D010797:Phthalimides