Neuronal nitric oxide synthase and calmodulin-dependent protein kinase IIalpha undergo neurotoxin-induced proteolysis.
Calpain (calcium-activated neutral protease) has been implicated as playing a role of neuronal injury in cerebral ischemia and excitotoxicity. Here we report that, in addition to extreme excitotoxic conditions [N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and kainate challenges], other neurotoxins such as maitotoxin, A23187, and okadaic acid also induce calpain activation, as detected by m-calpain autolytic fragmentation and nonerythroid alpha-spectrin breakdown. Under the same conditions, calmodulin-dependent protein kinase II-alpha (CaMPK-IIalpha) and neuronal nitric oxide synthase (nNOS) are both proteolytically cleaved by calpain. Such fragmentation can be reduced by calpain inhibitors (acetyl-Leu-Leu-Nle-CHO and PD151746). In vitro digestion of protein extract from cortical cultures with purified mu- and m-calpain produced fragmentation patterns for CaMPK-IIalpha and nNOS similar to those produced in situ. Also, several other calpain-sensitive calmodulin-binding proteins (plasma membrane calcium pump, microtubule-associated protein 2, and calcineurin A) and protein kinase C-alpha are also degraded in neurotoxin-treated cultures. Lastly, in a rat pup model of acute excitotoxicity, intrastriatal injection of NMDA resulted in breakdown of CaMPK-IIalpha and nNOS. The degradation of CaMPK-IIalpha, nNOS, and other endogenous calpain substrates may contribute to the neuronal injury associated with various neurotoxins.
Hajimohammadreza
I
I
Department of Neuroscience Therapeutics, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, Michigan 48105, U.S.A.
Raser
K J
KJ
Nath
R
R
Nadimpalli
R
R
Scott
M
M
Wang
K K
KK
D000818:Animals; D000831:Animals, Newborn; D000001:Calcimycin / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002154:Calpain / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000201:enzymology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D005333:Fetus; D007608:Kainic Acid / Q000633:toxicity; D007700:Kinetics; D008387:Marine Toxins / Q000633:toxicity; D016202:N-Methylaspartate / Q000633:toxicity*; D009474:Neurons / Q000201:enzymology*; D009498:Neurotoxins / Q000633:toxicity*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D019319:Okadaic Acid / Q000633:toxicity; D035964:Oxocins; D051381:Rats; D017207:Rats, Sprague-Dawley; D013049:Spectrin / Q000378:metabolism; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000633:toxicity; D000095702:Polyether Toxins
D000001:Calcimycin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002154:Calpain; D015853:Cysteine Proteinase Inhibitors; D007608:Kainic Acid; D008387:Marine Toxins; D016202:N-Methylaspartate; D009498:Neurotoxins; D019001:Nitric Oxide Synthase; D019319:Okadaic Acid; D035964:Oxocins; D013049:Spectrin; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C020394:maitotoxin; D000095702:Polyether Toxins; C517675:Camk2a protein, rat