In vivo activation of kainate receptors induces dephosphorylation of the heavy neurofilament subunit.
Injection of kainic acid (KA) into the rat hippocampus reduced the phosphorylation-related immunoreactivity of the heavy subunit of neurofilament proteins (NF-H). The effect was demonstrated quantitatively with a dot-immunobinding assay and qualitatively by immunoblotting with monoclonal antibodies against phosphorylation-dependent and nonphosphorylation-related epitopes of NF-H. The KA-induced reduction affected 50% of the phosphorylated NF-H in half of the hippocampus after 48 h. At the same time, the nonphosphorylation-related NF-H immunoreactivity increased as revealed by immunoblotting, indicating a shift from phosphorylated to nonphosphorylated NF-H. The effects on NF-H preceded a decrease in content of the neuron-specific enolase, a soluble neuronal cytoplasmic protein. No alterations of the light subunit of neurofilament proteins occurred, suggesting that KA has a preferential effect on NF-H phosphorylation. N-Methyl-D-aspartate administered similarly did not lead to a rapid dephosphorylation of NF-H. We propose that kainate receptor-mediated dephosphorylation in NF-H is involved in the signal transduction of excitatory amino acids with consequences for neuronal functions dependent on intermediary filament phosphorylation.
Wang
S
S
Institute of Neurobiology, University of Göteborg, Sweden.
Hamberger
A
A
Ding
M
M
Haglid
K G
KG
D000818:Animals; D007608:Kainic Acid / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D016900:Neurofilament Proteins / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction
D007608:Kainic Acid; D016900:Neurofilament Proteins; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter