Overexpression of HA-Bax but not Bcl-2 or Bcl-XL attenuates 6-hydroxydopamine-induced neuronal apoptosis.
Bax, a member of the Bcl-2 gene family, is known to promote apoptosis in many cases but to block cell death under certain conditions. To investigate the potential role of Bax in 6-hydroxydopamine (6-OHDA)-induced cell death, we first established and characterized a dopaminergic neuronal cell line (MN9D) stably overexpressing hemagglutinin epitope-tagged Bax (MN9D/HA-Bax) as well as control clones (MN9D/Neo). Treatment of MN9D/Neo cells with 6-OHDA induced typical apoptotic cell death accompanied by shrinkage of the cell, nuclear condensation, and DNA fragmentation as demonstrated by light microscopy and agarose gel analysis. Overexpression of HA-Bax in MN9D cells was shown to attenuate 6-OHDA-induced cell death as determined by the MTT reduction assay and agarose gel analysis for DNA fragmentation. Western blot analysis revealed that cleavage of poly(ADP-ribose)polymerase induced by 6-OHDA was attenuated in MN9D/HA-Bax cells. In contrast, overexpression of a well-known cell death-inhibiting protein such as Bcl-2 or Bcl-XL did not attenuate 6-OHDA-induced cell death. Interestingly, cell death induced by hydrogen peroxide (0.25-2.0 mM) was significantly accelerated, whereas the rate of cell death induced by menadione (10-50 microM) was not affected in MN9D/HA-Bax cells. Thus, our present data suggest that the functionally diverse roles of Bax may be determined by the type of stress applied to the cell.
Oh
J H
JH
Department of Biology, Yonsei University College of Science, Seoul, Korea.
Choi
W S
WS
Kim
J E
JE
Seo
J W
JW
O'Malley
K L
KL
Oh
Y J
YJ
D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D053938:DNA Fragmentation / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D016627:Oxidopamine / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics; D013997:Time Factors; D014162:Transfection; D014812:Vitamin K / Q000494:pharmacology; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494826:BAX protein, human; C494811:BCL2L1 protein, human; C494827:Bax protein, mouse; C494812:Bcl2l1 protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D014812:Vitamin K; D016627:Oxidopamine; D006861:Hydrogen Peroxide