Glutamate slows axonal transport of neurofilaments in transfected neurons.
Neurofilaments are transported through axons by slow axonal transport. Abnormal accumulations of neurofilaments are seen in several neurodegenerative diseases, and this suggests that neurofilament transport is defective. Excitotoxic mechanisms involving glutamate are believed to be part of the pathogenic process in some neurodegenerative diseases, but there is currently little evidence to link glutamate with neurofilament transport. We have used a novel technique involving transfection of the green fluorescent protein-tagged neurofilament middle chain to measure neurofilament transport in cultured neurons. Treatment of the cells with glutamate induces a slowing of neurofilament transport. Phosphorylation of the side-arm domains of neurofilaments has been associated with a slowing of neurofilament transport, and we show that glutamate causes increased phosphorylation of these domains in cell bodies. We also show that glutamate activates members of the mitogen-activated protein kinase family, and that these kinases will phosphorylate neurofilament side-arm domains. These results provide a molecular framework to link glutamate excitotoxicity with neurofilament accumulation seen in some neurodegenerative diseases.
Ackerley
S
S
Department of Neuroscience, The Institute of Psychiatry, Kings College London, London SE5 8AF United Kingdom.
Grierson
A J
AJ
Brownlees
J
J
Thornhill
P
P
Anderton
B H
BH
Leigh
P N
PN
Shaw
C E
CE
Miller
C C
CC
D001370:Axonal Transport / Q000187:drug effects / Q000502:physiology*; D001693:Biological Transport, Active / Q000187:drug effects; D002478:Cells, Cultured; D018698:Glutamic Acid / Q000378:metabolism* / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016501:Neurites / Q000378:metabolism; D016900:Neurofilament Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D008164:Luminescent Proteins; D016900:Neurofilament Proteins; D011993:Recombinant Fusion Proteins; C051774:neurofilament protein H; C061195:neurofilament protein M; D049452:Green Fluorescent Proteins; D018698:Glutamic Acid; D020928:Mitogen-Activated Protein Kinases