Down-regulation of Bcl-2, activation of caspases, and involvement of reactive oxygen species in 6-hydroxydopamine-induced thymocyte apoptosis

Chiung Wen Tsao, Juei Tang Cheng, Yee-Shin Lin

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Objective: Our previous work showed that 6-hydroxydopamine (6-OHDA) induced mouse thymocytes to undergo apoptosis both in vivo and in vitro. In the present study, we further investigated the mechanisms of 6-OHDA-induced apoptosis in vitro. Methods: Naive mouse thymocytes were cultured with 6-OHDA. The percentages of apoptotic cells were quantified by propidium iodide staining, and DNA fragmentation was detected by agarose gel electrophoresis. Intracellular Bcl-2 was analyzed by immunofluorescence staining. Cu/Zn superoxide dismutase (Cu/Zn-SOD) activities were measured by the SOD-525 method. Results: The apoptotic effect of 6-OHDA was blocked by desipramine, a catecholamine uptake blocker. Treatment with 6-OHDA caused a reduction in Bcl-2 expression. VAD-FMK, a broad-spectrum caspase inhibitor, and DEVD-CHO, a potent inhibitor of caspase-3, could block 6-OHDA-induced thymocyte apoptosis. However, the specific caspase-1 (ICE) inhibitor YVAD-CMK had no effect. This cell death process was prevented by the protein synthesis inhibitor cycloheximide and by antioxidants. The level of Cu/Zn-SOD activities also decreased after cells were exposed to 6-OHDA. Conclusion: These results suggest an apoptotic effect of 6-OHDA via the uptake of this neurotoxin by thymocytes, and that down-regulation of Bcl-2, activation of caspases, such as caspase-3 but not caspase-1, generation of reactive oxygen species, and new synthesis of proteins are involved in this process.

Original languageEnglish
Pages (from-to)328-336
Number of pages9
JournalNeuroImmunoModulation
Volume10
Issue number6
DOIs
Publication statusPublished - 2002 Dec 1

All Science Journal Classification (ASJC) codes

  • Immunology
  • Endocrinology
  • Neurology
  • Endocrine and Autonomic Systems

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