Effective post-insult neuroprotection by a novel Ca(2+)/ calmodulin-dependent protein kinase II (CaMKII) inhibitor.
Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII) is a major mediator of physiological glutamate signaling involved in higher brain functions. Here, we show CaMKII involvement in pathological glutamate signaling relevant in stroke. The novel inhibitor tatCN21 was neuroprotective even when added hours after glutamate insults. By contrast, the "traditional" inhibitor KN93 attenuated excitotoxicity only when present during the insult. Both inhibitors efficiently blocked Ca(2+)/CaM-stimulated CaMKII activity, CaMKII interaction with NR2B and aggregation of CaMKII holoenzymes. However, only tatCN21 but not KN93 blocked the Ca(2+)-independent "autonomous" activity generated by Thr-286 autophosphorylation, the hallmark feature of CaMKII regulation. Mutational analysis further validated autonomous CaMKII activity as the drug target crucial for post-insult neuroprotection. Overexpression of CaMKII wild type but not the autonomy-deficient T286A mutant significantly increased glutamate-induced neuronal death. Maybe most importantly, tatCN21 also significantly reduced infarct size in a mouse stroke model (middle cerebral arterial occlusion) when injected (1 mg/kg intravenously) 1 h after onset of arterial occlusion. Together, these data demonstrate that inhibition of autonomous CaMKII activity provides a promising therapeutic avenue for post-insult neuro-protection after stroke.
Vest
Rebekah S
RS
Department of Pharmacology, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA.
O'Leary
Heather
H
Coultrap
Steven J
SJ
Kindy
Mark S
MS
Bayer
K Ulrich
KU
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001596:Benzylamines / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002147:Calmodulin / Q000494:pharmacology; D016923:Cell Death; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D015696:Gene Products, tat / Q000737:chemistry / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology; D020521:Stroke / Q000188:drug therapy; D013449:Sulfonamides / Q000494:pharmacology; D000096926:Benzenesulfonamides
D001596:Benzylamines; D002118:Calcium; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002147:Calmodulin; D015696:Gene Products, tat; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D047428:Protein Kinase Inhibitors; D016194:Receptors, N-Methyl-D-Aspartate; D013449:Sulfonamides; C072105:KN 93; D000096926:Benzenesulfonamides