title: Modulation of calcium/calmodulin kinase-II provides partial neuroprotection against beta-amyloid peptide toxicity.
abstract: Beta-amyloid (Abeta) peptide-induced neurotoxicity has been implicated in the pathogenesis of Alzheimer's disease (AD). The exact mechanism by which Abeta peptides trigger neuronal death is not well defined and may be related to an abrupt increase in intracellular calcium, leading to the activation of many pro-apoptotic pathways. While modulation of intracellular calcium increase receives much attention for pharmaceutical intervention, Ca2+-mediated pro-apoptotic signalling pathways have not been systematically studied. We have reported our study on the roles of calcium/calmodulin-dependent protein kinase II (CaMKII) in Abeta peptide neurotoxicity. By treating the primary cortical neurons exposed to Abeta peptides (Abeta(25-35) and Abeta(1-42)) with two selective CaMKII inhibitors, autocamtide-related inhibitory peptide (AIP) and KN93, Abeta peptide neurotoxicity was significantly reduced. Release of LDH and DNA fragmentation/condensation (by DAPI staining) in neurons exposed to Abeta peptides were significantly decreased in the presence of AIP and KN93. While these inhibitors significantly attenuated Abeta peptide-triggered activation of caspase-2 and caspase-3, and AIP significantly decreased the degree of tau phosphorylation of the Abeta peptide-treated neurons at early time, they could elicit partial neuroprotection only. Pharmacological inhibitor targeting calmodulin, W7, did not provide neuroprotection. Morphine, which activates CaMKII via micro receptors, augments Abeta-induced LDH release, caspase-2 and caspase-3 activities and neuronal apoptosis. Taken together, although CaMKII plays a role in Abeta peptide neurotoxicity, pharmacological inhibition cannot afford complete neuroprotection.
authors.affiliation: Laboratory of Neurodegenerative Disease, Department of Anatomy, Faculty of Medicine, and Central Laboratory of Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, Hong Kong SAR.
authors.forename: Kim-Fung
authors.initials: KF
authors.lastname: Lin
authors.forename: Raymond Chuen-Chung
authors.initials: RC
authors.lastname: Chang
authors.forename: Ka-Chun
authors.initials: KC
authors.lastname: Suen
authors.forename: Kwok-Fai
authors.initials: KF
authors.lastname: So
authors.forename: Jacques
authors.initials: J
authors.lastname: Hugon
mesh_terms: D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology; D018696:Neuroprotective Agents / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010446:Peptide Fragments / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016229:Amyloid beta-Peptides; D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); C074636:amyloid beta-protein (25-35); D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020169:Caspases