Metallothionein-III prevents glutamate and nitric oxide neurotoxicity in primary cultures of cerebellar neurons.
Metallothionein (MT)-III, a member of the MT family of metal-binding proteins, is mainly expressed in the CNS and is abundant in glutamatergic neurons. Results in genetically altered mice indicate that MT-III may play neuroprotective roles in the brain, but the mechanisms through which this protein functions have not been elucidated. The aim of this work was to assess whether MT-III is able to prevent glutamate neurotoxicity and to identify the step of the neurotoxic process interfered with by MT-III. Glutamate neurotoxicity in cerebellar neurons in culture is mediated by excessive activation of glutamate receptors, increased intracellular calcium, and increased nitric oxide. It is shown that MT-III prevented glutamate- and nitric oxide-induced neurotoxicity in a dose-dependent manner, with nearly complete protection at 0.3-1 microgram/ml. MT-III did not prevent the glutamate-induced rise of intracellular calcium level but reduced significantly the nitric oxide-induced formation of cyclic GMP. Circular dichroism analysis revealed that nitric oxide triggers the release of the metals coordinated to the cysteine residues of MT-III, indicative of the S(Cys)-nitrosylation of the protein. Therefore, the present results indicate that MT-III can quench pathological levels of nitric oxide, thus preventing glutamate and nitric oxide neurotoxicity.
Montoliu
C
C
Instituto de Investigaciones Citológicas, Fundación Valenciana de Investigaciones Biomédicas, Valencia Biologia Celular, de Fisiología y de Immunología, Barcelona, Spain.
Monfort
P
P
Carrasco
J
J
Palacios
O
O
Capdevila
M
M
Hidalgo
J
J
Felipo
V
V
D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology* / Q000187:drug effects; D002942:Circular Dichroism; D006152:Cyclic GMP / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology / Q000633:toxicity*; D000090023:Metallothionein 3; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology / Q000633:toxicity*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D000090023:Metallothionein 3; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents; D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; D002104:Cadmium; D009569:Nitric Oxide; D018698:Glutamic Acid; D010396:Penicillamine; D006152:Cyclic GMP; D002118:Calcium