Document Detail


Cdk1/cyclin B-mediated phosphorylation stabilizes SREBP1 during mitosis.
MedLine Citation:
PMID:  16880739     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Members of the sterol regulatory element-binding protein (SREBP) family of transcription factors control the biosynthesis of cholesterol and other lipids, and lipid synthesis is critical for cell growth and proliferation. We recently found that the mature forms of SREBP1a and SREBP1c are hyperphosphorylated in mitotic cells, giving rise to a phosphoepitope recognized by the mitotic protein monoclonal-2 (MPM-2) antibody. In addition, we found that mature SREBP1 was stabilized in a phosphorylation-dependent manner during mitosis. We have now mapped the major MPM-2 epitope to a serine residue, S439, in the C terminus of mature SREBP1. Using phosphorylation-specific antibodies, we demonstrate that endogenous SREBP1 is phosphorylated on S439 specifically during mitosis. Mature SREBP1 interacts with the Cdk1/cyclin B complex in mitotic cells and we demonstrate that Cdk1 phosphorylates S439, both in vitro and in vivo. Our results suggest that Cdk1-mediated phosphorylation of S439 stabilizes mature SREBP1 during mitosis, thereby preserving a critical pool of active transcription factors to support lipid synthesis. Taken together with our previous work, the current study suggests that SREBP1 may provide a link between lipid synthesis, proliferation and cell growth. This hypothesis was supported by our observation that siRNA-mediated inactivation of SREBP1 arrested cells in the G(1) phase of the cell cycle, thereby attenuating cell growth.
Authors:
Maria T Bengoechea-Alonso; Johan Ericsson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-08-01
Journal Detail:
Title:  Cell cycle (Georgetown, Tex.)     Volume:  5     ISSN:  1551-4005     ISO Abbreviation:  Cell Cycle     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-08-24     Completed Date:  2007-01-03     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  101137841     Medline TA:  Cell Cycle     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1708-18     Citation Subset:  IM    
Affiliation:
Ludwig Institute for Cancer Research, Uppsala University, Uppsala, Sweden.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
CDC2 Protein Kinase / metabolism*
Cells, Cultured
Cyclin B / metabolism*
Epitopes / immunology
G1 Phase
Hela Cells
Humans
Mitosis*
Molecular Sequence Data
Phosphorylation
Phosphoserine / metabolism
Protein Interaction Mapping
S Phase
Sterol Regulatory Element Binding Protein 1 / chemistry,  genetics,  metabolism*
Thermodynamics*
Transcription, Genetic
Chemical
Reg. No./Substance:
0/Cyclin B; 0/Epitopes; 0/Sterol Regulatory Element Binding Protein 1; 17885-08-4/Phosphoserine; EC 2.7.11.22/CDC2 Protein Kinase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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