Maitotoxin-induced nerve growth factor production accompanied by the activation of a voltage-insensitive Ca2+ channel in C6-BU-1 glioma cells.
1. The aim of the present study was to determine the effects of maitotoxin on nerve growth factor production and the Ca2+ influx in clonal rat glioma cells (C6-BU-1). 2. Maitotoxin (1 - 10 ng ml-1) induced a profound increase in 45Ca2+ influx in an extracellular Ca2+-dependent manner. However, high KCl had no effect at all. These effects were supported by the results from the analysis of intracellular Ca2+ concentration using fura 2. 3. The maitotoxin-induced 45Ca2+ influx was inhibited by inorganic Ca2+ antagonists, such as Mg2+, Mn2+ and Co2+. The inhibitory effect of Co2+ was antagonized by increasing the extracellular Ca2+ concentrations. 4. Maitotoxin (3 ng ml-1) as well as A-23187 (1microM) and dibutyryl cyclic AMP (0.5 mM) caused an acceleration of nerve growth factor (NGF) production in C6-BU-1 cells, as determined by NGF enzyme immunoassay. 5. Reverse transcription polymerase chain reaction (RT - PCR) analysis showed that maitotoxin (10 ng ml-1) enhanced the expression of NGF mRNA, which was abolished by the removal of extracellular Ca2+. A-23187 also accelerated its expression. 6. These results suggest that maitotoxin activates a voltage-insensitive Ca2+ channel and accelerates NGF production mediated through a Ca2+ signalling pathway in C6-BU-1 glioma cells.
Obara
Y
Y
Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
Takahashi
M
M
Nakahata
N
N
Ohizumi
Y
Y
D000818:Animals; D001932:Brain Neoplasms / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects*; D002460:Cell Line; D005456:Fluorescent Dyes; D016257:Fura-2; D005910:Glioma / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D008387:Marine Toxins / Q000494:pharmacology*; D009363:Neoplasm Proteins / Q000096:biosynthesis; D009414:Nerve Growth Factors / Q000096:biosynthesis*; D035964:Oxocins; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013268:Stimulation, Chemical; D014407:Tumor Cells, Cultured; D000095702:Polyether Toxins
D003994:Bucladesine; D000001:Calcimycin; D002120:Calcium Channel Agonists; D015220:Calcium Channels; D005456:Fluorescent Dyes; D016257:Fura-2; D008387:Marine Toxins; D009363:Neoplasm Proteins; D009414:Nerve Growth Factors; D035964:Oxocins; D012333:RNA, Messenger; C020394:maitotoxin; D000095702:Polyether Toxins