Progressive loss of a glial potassium channel (KCNJ10) in the spinal cord of the SOD1 (G93A) transgenic mouse model of amyotrophic lateral sclerosis.
Transgenic mice expressing the superoxide dismutase G93A mutation (SOD1(G93A)) were used to investigate the role of glial inwardly rectifying K(+) (Kir)4.1 channels, which buffer extracellular K(+) increases in response to neuronal excitation. A progressive decrease in Kir4.1 immunoreactivity was observed predominantly in the ventral horn of SOD1(G93A) mutants. Immunoblotting of spinal cord extracts mirrored these changes by showing a loss of Kir4.1 channels from presymptomatic stages onwards. Kir4.1 channels were found to be expressed in the spinal cord grey matter, targetting astrocytes and clustering around capillaries, supporting their role in clearance of extracellular K(+). To understand the functional implications of extracellular K(+) increases, we challenged the NSC34 motor neurone cell line with increasing extracellular K(+) concentrations. Exposure to high extracellular K(+) induced progressive motor neurone cell death. We suggest that loss of Kir4.1 impairs perineural K(+) homeostasis and may contribute to motor neurone degeneration in SOD1(G93A) mutants by K(+) excitotoxic mechanisms.
Kaiser
Melanie
M
Department of Neurology, Georg-August University Göttingen, Göttingen, Germany.
Maletzki
Iris
I
Hülsmann
Swen
S
Holtmann
Bettina
B
Schulz-Schaeffer
Walter
W
Kirchhoff
Frank
F
Bähr
Mathias
M
Neusch
Clemens
C
D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D051401:Aquaporin 4 / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism; D015153:Blotting, Western; D002196:Capillaries / Q000166:cytology / Q000378:metabolism; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D005110:Extracellular Space / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008822:Mice, Transgenic; D009046:Motor Neurons / Q000378:metabolism / Q000502:physiology; D009457:Neuroglia / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D000072105:Superoxide Dismutase-1; D000098854:Kcnj10 Channel
D051401:Aquaporin 4; D005904:Glial Fibrillary Acidic Protein; D000098854:Kcnj10 Channel; D024661:Potassium Channels, Inwardly Rectifying; C000606290:SOD1 protein, human; D049452:Green Fluorescent Proteins; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D011188:Potassium