In vitro and in vivo induction and activation of nNOS by LPS in oligodendrocytes.
There are currently four known isoforms of nitric oxide synthase (NOS). Of these, neuronal NOS (nNOS) is known to be present exclusively in neurons, endothelial NOS (eNOS) in vascular endothelium, while the inducible form of NOS (iNOS) is known to be activated in oligodendrocytes, astrocytes and microglia. The fourth isoform, mitochondrial NOS (mtNOS), represents a post-translational modification of nNOS. Using western blotting and real time-PCR, we show induction and activation of nNOS following culture of oligodendrocyte progenitor cells (OPC) with lipopolysaccharide (LPS). Activation of nNOS results in accumulation of peroxynitrite and tyrosine nitration of proteins in oligodendrocytes resulting in reduced cell viability. Injection of LPS in vivo into the corpus callosum of rats leads to the development of extensive demyelination of the white matter tracts. Immunostaining of regions close to the injection site shows the presence of nNOS, but not iNOS, in oligodendrocytes. Neither iNOS nor nNOS was seen in astrocytes in areas of demyelination. These studies suggest that activation of nNOS in oligodendrocytes leads to oligodendrocyte injury resulting in demyelination.
Yao
S Y
SY
Department of Neurology, Multiple Sclerosis Research Center, Nashville, TN 37212, USA.
Ljunggren-Rose
A
A
Chandramohan
N
N
Whetsell
W O
WO
Sriram
S
S
D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001120:Arginine / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D001921:Brain / Q000166:cytology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002956:Citrulline / Q000378:metabolism; D003337:Corpus Callosum / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D007191:Indazoles / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D019081:O Antigens / Q000378:metabolism; D009836:Oligodendroglia / Q000187:drug effects*; D030421:Peroxynitrous Acid / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000187:drug effects*; D014316:Tritium / Q000378:metabolism
D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases; D001120:Arginine; D051792:Basic Helix-Loop-Helix Proteins; D002956:Citrulline; D004791:Enzyme Inhibitors; D007191:Indazoles; D008070:Lipopolysaccharides; D009419:Nerve Tissue Proteins; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D019081:O Antigens; D030421:Peroxynitrous Acid; D014316:Tritium; C498633:Olig1 protein, rat; C080122:7-nitroindazole