Biochemical and biological effects of KN-93, an inhibitor of calmodulin-dependent protein kinase II, on the initial events of mouse egg activation induced by ethanol.
Calmodulin-dependent protein kinase II (CaMKII) is transiently activated in mouse eggs by the increase in calcium that occurs upon activation with ethanol. This study investigated the biological and biochemical effects of KN-93, a reported selective inhibitor of CaMKII, to explore the potential role of this kinase in the initial events of egg activation. Mouse eggs were incubated for 30 min in the presence of different concentrations of KN-93 and induced to activate by 7% ethanol. KN-93 elicited a dose-dependent inhibition of polar body emission that resulted from the failure of the eggs to undergo meiosis resumption and inactivation of maturation-promoting factor (MPF). Furthermore, 15 mumol KN-93 l-1 produced a marked reduction in ethanol-induced loss of cortical granules. In vivo biochemical analysis revealed that 15 mumol KN-93 l-1 was responsible for significant inhibition of ethanol-stimulated CaMKII. The activity of the enzyme remained at a resting value, in spite of the presence of a calcium signal similar to that measured in control activated eggs. The inhibitory effects of KN-93 on the parameters tested in this study could not be mimicked by the inactive analogue KN-92. These results show that in mouse eggs, when ethanol-induced CaMKII activation was prevented, cortical granule exocytosis and meiosis resumption were inhibited. This suggests that CaMKII acts as a switch in the transduction of the calcium signal triggering mammalian egg activation.
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Department of Biomedical Sciences and Technologies, Faculty of Medicine, University of L'Aquila, Italy.
Iorio
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R
Francione
A
A
Gioia
L
L
Colonna
R
R
D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D016200:Maturation-Promoting Factor / Q000378:metabolism; D008540:Meiosis / Q000187:drug effects; D000090204:Mesothelin; D051379:Mice; D008815:Mice, Inbred Strains; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D000096926:Benzenesulfonamides
D001596:Benzylamines; D002118:Calcium; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D000431:Ethanol; D016200:Maturation-Promoting Factor; D000090204:Mesothelin; D013449:Sulfonamides; C000715528:Msln protein, mouse; C072105:KN 93; D000096926:Benzenesulfonamides