Cleavage of Mcl-1 by caspases impaired its ability to counteract Bim-induced apoptosis.
Mcl-1 is an antiapoptotic member of the Bcl-2 family that can promote cell viability. We report here that Mcl-1 is a new substrate for caspases during induction of apoptosis. Mcl-1 cleavage occurs after Asp127 and Asp157 and generates four fragments of 24, 19, 17 and 12 kDa in both intact cells and in vitro, an effect prevented by selective caspase inhibitors. As a consequence, the resulting protein that lacks the first 127 or 157 amino acids contains only the BH1-BH3 domains of Bcl-2 family members. Mutation of Asp127 and Asp157 abolishes the generation of the 24 and 12 kDa fragments and that of the 19 and 17 kDa fragments, respectively. Interestingly, when expressed in HeLa cells Mcl-1 wt and Mcl-1 Delta127 showed a markedly different intracellular distribution. Mcl-1 wt colocalized with alpha-Tubulin near the internal face of the plasma membrane, while Mcl-1 Delta127 coassociated with Bim-EL at the mitochondrial level. Coimmunoprecipitation experiments also demonstrated that Mcl1 Delta127 exhibited increased binding to Bim when compared to Mcl-1 wt. Finally, Mcl-1 wt unlike Mcl-1 Delta127 inhibited Bim-EL-induced caspase activation. Altogether, our findings demonstrate that cleavage of Mcl-1 by caspases modifies its subcellular localization, increases its association with Bim and inhibits its antiapoptotic function.
Herrant
Magali
M
INSERM U526, Physiopathologie de la Survie et de la Mort Cellulaires et Infections Virales, Equipe Labellisée par la Ligue Nationale contre le Cancer, IFR50, Faculté de Médecine, Avenue de Valombrose, 06107 Nice Cedex 2, France.
Jacquel
Arnaud
A
Marchetti
Sandrine
S
Belhacène
Nathalie
N
Colosetti
Pascal
P
Luciano
Frédéric
F
Auberger
Patrick
P
D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism*; D017931:DNA Primers; D005434:Flow Cytometry; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D020014:K562 Cells; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D014176:Protein Biosynthesis; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013379:Substrate Specificity; D014158:Transcription, Genetic; D014162:Transfection
D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins; D017931:DNA Primers; D008565:Membrane Proteins; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D020169:Caspases