title: The N terminus of the anti-apoptotic BCL-2 homologue MCL-1 regulates its localization and function.
abstract: The BCL-2 homologue MCL-1 plays an important role in the regulation of cell fate by blocking apoptosis as well as regulating cell cycle. MCL-1 has an unusual N-terminal extension, which contains a PEST domain and several phosphorylation sites that have been suggested to regulate its turnover. Here we report that the first 79 amino acids of MCL-1 regulate its subcellular localization. Deletion of this domain impairs both its mitochondrial localization and its anti-apoptotic activity. Conversely, expression of the N terminus of MCL-1 promotes both the association of MCL-1 with mitochondria and cell survival in a fashion that is dependent on the presence of endogenous MCL-1. In addition, the N terminus of MCL-1 has an antagonistic effect on proliferation. Although MCL-1 decreases proliferation through binding to proliferating cell nuclear antigen and cyclin-dependent kinase 1 in the nucleus, the N terminus of MCL-1 accelerates cell division. On the other hand, deletion of this region further increases the anti-proliferative activity of MCL-1. These results suggest that the N terminus of MCL-1 plays a major regulatory role, regulating coordinately the mitochondrial (anti-apoptotic) and nuclear (anti-proliferative) functions of MCL-1.
authors.affiliation: Department of Medicine, University of British Columbia and Vancouver Coastal Health Research Institute, Jack Bell Research Centre, Vancouver, British Columbia V6H 3Z6, Canada. mgermain@interchange.ubc.ca
authors.forename: Marc
authors.initials: M
authors.lastname: Germain
authors.forename: Vincent
authors.initials: V
authors.lastname: Duronio
mesh_terms: D017209:Apoptosis; D002467:Cell Nucleus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry* / Q000378:metabolism*; D014466:Ultraviolet Rays