Alpha B-crystallin in C6 glioma cells supports their survival in elevated extracellular K+: the implication of a protective role of alpha B-crystallin accumulation in reactive glia.
It has been shown by immunohistochemical studies that alpha B-crystallin accumulates in the reactive and neoplastic glial cells in a variety of pathologic situations. However, the molecular mechanism for the induction of alpha B-crystallin in diseased brains is still unknown. Since any destructive brain lesions cause an abnormal elevation in the potassium (K+) concentration of the extracellular space, which disturbs the regulatory mechanism of glial cell volume, we investigated the influence of elevated extracellular K+ on the expression of alpha B-crystallin in glial cells. The treatment of rat C6 glioma cells with augmented K+ in the culture media induced an accumulation of alpha B-crystallin mRNA in a dose-dependent manner and an accumulation of the alpha B-crystallin as well. Furthermore, an overexpression of alpha B-crystallin in the C6 transformant transfected with a rat alpha B-crystallin cDNA conferred a resistant phenotype against the insult of elevated extracellular K+ on the glioma cells. Thus, alpha B-crystallin may contribute to the survival of reactive glia in the presence of a high extracellular K+ concentration.
Iwaki
T
T
Department of Neuropathology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Iwaki
A
A
Fukumaki
Y
Y
Tateishi
J
J
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects*; D003459:Crystallins / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005910:Glioma / Q000737:chemistry; D006360:Heat-Shock Proteins / Q000494:pharmacology; D006947:Hyperkalemia; D009457:Neuroglia / Q000187:drug effects*; D011188:Potassium / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D013997:Time Factors; D014407:Tumor Cells, Cultured
D003459:Crystallins; D006360:Heat-Shock Proteins; D011188:Potassium