Cdk1/cyclin B-mediated phosphorylation stabilizes SREBP1 during mitosis

Maria T. Bengoechea-Alonso, Johan Ericsson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)

Abstract

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 G1 phase of the cell cycle, thereby attenuating cell growth.

Original languageEnglish
Pages (from-to)1708-1718
Number of pages11
JournalCell Cycle
Volume5
Issue number15
DOIs
Publication statusPublished - 1 Aug 2006
Externally publishedYes

Keywords

  • Cdk1
  • Cell cycle
  • Cholesterol
  • Lipids
  • Phosphorylation
  • Proliferation
  • SREBP
  • Transcription

Fingerprint

Dive into the research topics of 'Cdk1/cyclin B-mediated phosphorylation stabilizes SREBP1 during mitosis'. Together they form a unique fingerprint.

Cite this