Phosphorylation and proteasome-dependent degradation of Bcl-2 in mitotic-arrested cells after microtubule damage.
Treatment of NIH-OVCAR-3 cells with paclitaxel, a microtubule-stabilizing agent, induces mitotic arrest and apoptosis, but also Bcl-2 phosphorylation. We report here that Bcl-2 phosphorylation precedes Bcl-2 down-regulation and that both events are closely associated with mitotic arrest, but are not sufficient for paclitaxel to trigger apoptosis. Indeed, when paclitaxel-treated cells were induced to exit mitosis in the presence of 2-aminopurine, Bcl-2 phosphorylation and Bcl-2 down-regulation were both inhibited. In contrast, when apoptosis was inhibited by a caspase inhibitor or Bcl-2 over-expression, Bcl-2 phosphorylation and down-regulation still occurred. Furthermore, we show that Bcl-2 is degraded in mitosis by the proteasome-dependent pathway since Bcl-2 down-regulation is inhibited by proteasome inhibitors such as MG132, Lactacystin and LLnL. Taken together these results indicate that mitotic spindle damage results in post-translational modifications of Bcl-2 by phosphorylation and degradation.
Chadebech
P
P
LBCMCP, EP CNRS 2079, Université Paul Sabatier, 118 Route de Narbonne, Toulouse Cedex, 31062, France.
Brichese
L
L
Baldin
V
V
Vidal
S
S
Valette
A
A
D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019254:Genes, bcl-2; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D008870:Microtubules / Q000187:drug effects / Q000502:physiology*; D008938:Mitosis; D009097:Multienzyme Complexes / Q000378:metabolism*; D010051:Ovarian Neoplasms; D017239:Paclitaxel / Q000633:toxicity; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000590:Amino Acid Chloromethyl Ketones; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D009097:Multienzyme Complexes; D019253:Proto-Oncogene Proteins c-bcl-2; D010566:Virulence Factors, Bordetella; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C067713:lactacystin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D017239:Paclitaxel; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D000111:Acetylcysteine