Involvement of caspase-like proteinases in apoptosis of neuronal PC12 cells and primary cultured microglia induced by 6-hydroxydopamine

• Published in: Journal of neuroscience research 1998-10, Vol.54 (2), p.214-222
• Main Authors: Takai, Nobuhiko, Nakanishi, Hiroshi, Tanabe, Kazunari, Nishioku, Tsuyoshi, Sugiyama, Toshihiro, Fujiwara, Michihiro, Yamamoto, Kenji
• Format: Article
• Language: English
• Subjects: 6-hydroxydopamine; Animals; apoptosis; Apoptosis - physiology; caspase; Caspases - metabolism; Cell Survival - drug effects; Cells, Cultured; Enzyme Induction; Genes, bcl-2; In Situ Nick-End Labeling; Ligands; Microglia - cytology; Microglia - drug effects; Microglia - metabolism; Oxidopamine - pharmacology; PC12 cell; PC12 Cells; Piperazines - pharmacology; Protease Inhibitors - pharmacology; rat primary cultured microglia; Rats
• ISSN: 0360-4012; 1097-4547
• DOI: 10.1002/(SICI)1097-4547(19981015)54:2<214::AID-JNR9>3.0.CO;2-H

Activation of proteolytic enzymes, including the caspase family of proteinases, is a feature characteristic of the apoptotic program. In the present study, we examined a potential role of intracellular proteinases in the death of neuronal PC12 and primary cultured rat microglial cells induced by 6‐hydroxydopamine (6‐OHDA). In both neuronal PC12 and microglial cells, 6‐OHDA (10–200 μM) induced apoptosis in a dose‐dependent manner as judged by the DNA break. The 6‐OHDA was ineffective in Bcl‐2‐overexpressing neuronal PC12 cells. Pretreatment of these cells with two caspase inhibitors, acetyl‐Try‐Val‐Ala‐Asp‐aldehyde and acetyl‐Asp‐Glu‐Val‐Asp‐aldehyde, prevented the 6‐OHDA‐induced apoptosis. Pepstatin A and leupeptin, potent inhibitors of aspartic and cysteine proteinases, respectively, partly inhibited the apoptosis of microglia but not neuronal PC12 cells. In contrast, GBR12935, a dopamine uptake inhibitor, significantly inhibited the apoptotic death of neuronal PC12 cells but not microglia. These results suggest that mechanisms by which 6‐OHDA induces apoptosis in these two cell types are distinct; 6‐OHDA incorporated into neuronal PC12 cells and its metabolites may activate the caspase‐like enzymes, whereas oxidative metabolites of the agent produced extracellularly may activate the caspase and the endosomal/lysosomal proteolytic systems in microglia. J. Neurosci. Res. 54:214–222, 1998. © 1998 Wiley‐Liss, Inc.