Phosphorylation prevents C/EBPβ from the calpain-dependent degradation

Yuan yuan Zhang, Shu fen Li, Shu wen Qian, You you Zhang, Yuan Liu, Qi Qun Tang, Xi Li

Research output: Contribution to journalArticlepeer-review

Abstract

CCAAT/enhancer-binding protein (C/EBP) β plays an important role in proliferation and differentiation of 3T3-L1 preadipocytes. C/EBPβ is sequentially phosphorylated during the 3T3-L1 adipocyte differentiation program, first by MAPK/Cyclin A/cdk2 on Thr 188 and subsequently by GSK3β on Ser 184 or Thr 179. Dual phosphorylation is critical for the gain of DNA binding activity of C/EBPβ. In this manuscript, we found that phosphorylation also contributed to the stability of C/EBPβ. Both ex vivo and in vitro experiments showed that phosphorylation by MAPK/Cyclin A/cdk2 and GSK3β protected C/EBPβ from μ-calpain-mediated proteolysis, while phosphorylation on Thr 188 by MAPK/Cyclin A/cdk2 contributed more to the stabilization of C/EBPβ, Further studies indicated that phosphorylation mimic C/EBPβ was insensitive to both calpain accelerator and calpain inhibitor. Thus, phosphorylation might contribute to the stability as well as the gain of DNA binding activity of C/EBPβ.

Original languageEnglish (US)
Pages (from-to)550-555
Number of pages6
JournalBiochemical and Biophysical Research Communications
Volume419
Issue number3
DOIs
StatePublished - Mar 16 2012
Externally publishedYes

Keywords

  • C/EBPβ
  • Calpain
  • Degradation
  • Phosphorylation

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Molecular Biology

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