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Death-signalling cascade in mouse cerebellar granule neurons

Authors

  • Hiroki Tanabe,

    1. 1 Department of Molecular Genetics, Biomedical Research Center, Osaka University Medical School, 2–2, Yamadaoka, Suita, Osaka 565 Japan, 21Geneva Biomedical Research Institute, Glaxo Wellcome R&D SA, 1228, Plan-les-Ouates, Geneva, Switzerland
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  • Yutaka Eguchi,

    1. 1 Department of Molecular Genetics, Biomedical Research Center, Osaka University Medical School, 2–2, Yamadaoka, Suita, Osaka 565 Japan, 21Geneva Biomedical Research Institute, Glaxo Wellcome R&D SA, 1228, Plan-les-Ouates, Geneva, Switzerland
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  • Shigeomi Shimizu,

    1. 1 Department of Molecular Genetics, Biomedical Research Center, Osaka University Medical School, 2–2, Yamadaoka, Suita, Osaka 565 Japan, 21Geneva Biomedical Research Institute, Glaxo Wellcome R&D SA, 1228, Plan-les-Ouates, Geneva, Switzerland
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  • Jean-Claude Martinou,

    1. 1 Department of Molecular Genetics, Biomedical Research Center, Osaka University Medical School, 2–2, Yamadaoka, Suita, Osaka 565 Japan, 21Geneva Biomedical Research Institute, Glaxo Wellcome R&D SA, 1228, Plan-les-Ouates, Geneva, Switzerland
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  • Yoshihide Tsujimoto

    1. 1 Department of Molecular Genetics, Biomedical Research Center, Osaka University Medical School, 2–2, Yamadaoka, Suita, Osaka 565 Japan, 21Geneva Biomedical Research Institute, Glaxo Wellcome R&D SA, 1228, Plan-les-Ouates, Geneva, Switzerland
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Correspondence: Dr Yoshihide Tsujimoto, Department of Medical Genetics, Biomedical Research Center, Osaka University Medical School, 2–2, Yamadaoka, Suita, Osaka 565 Japan.

Abstract

Molecular mechanisms of neuronal cell death are still largely unknown. In the present study, the signal transduction pathway of cell death in cerebellar granule neurons was examined by employing various death-preventative agents. When death was induced by the depletion of serum and a depolarizing level of potassium, transient increase in active c-Jun, mitochondrial membrane potential (Δψ) loss, activation of caspase-3 (-like) proteases, and nuclear condensation and fragmentation were observed. The protein synthesis inhibitor cycloheximide blocked all these phenomena, whereas RNA synthesis inhibitor actinomycin-D, survival factor such as insulin-like growth factor-1, brain-derived neurotrophic factor, high K+ (25 mm) and overproduced antiapoptotic protein Bcl-2, prevented Δψ loss, caspase activation, and nuclear change, but not an increase in active c-Jun. The caspase inhibitor z-Asp-CH2-DCB (carbobenzoxy-l-aspartyl-α-[(2,6-dichlorobenzoyl) oxy]methane) only inhibited activation of caspases and nuclear change. These results suggest that the death signal in cerebellar granule neurons is sequentially transduced in the order of c-Jun activation, de novo RNA synthesis, mitochondrial Δψ loss, activation of caspase-3 (-like) proteases and nuclear change.

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