Phosphorylation prevents C/EBP尾 from the calpain-dependent degradation

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• 作者：Yuan-yuan Zhang ; Shu-fen Li ; Shu-wen Qian ; You-you Zhang ; Yuan Liu ; Qi-Qun Tang ; Xi Li ; ^{lixi@shmu.edu.cn}
• 关键词：cdk2 ; cyclin-dependent kinase 2 ; C/EBP ; CCAAT/enhancer-binding protein ; GSK3尾 ; glycogen synthase kinase-3尾 ; PPAR ; peroxisome proliferator-activated receptor ; rC/EBP尾 ; recombinant C/EBP尾
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2012
• 期刊代码：159_0006291x
• 类别：bio
• 出版时间：16 March, 2012
• 卷：419
• 期：3
• 页码：550-555
• 文件大小：472 K

摘要

CCAAT/enhancer-binding protein (C/EBP) 尾 plays an important role in proliferation and differentiation of 3T3-L1 preadipocytes. C/EBP尾 is sequentially phosphorylated during the 3T3-L1 adipocyte differentiation program, first by MAPK/Cyclin A/cdk2 on Thr₁₈₈ and subsequently by GSK3尾 on Ser₁₈₄ or Thr₁₇₉. Dual phosphorylation is critical for the gain of DNA binding activity of C/EBP尾. In this manuscript, we found that phosphorylation also contributed to the stability of C/EBP尾. Both ex vivo and in vitro experiments showed that phosphorylation by MAPK/Cyclin A/cdk2 and GSK3尾 protected C/EBP尾 from 渭-calpain-mediated proteolysis, while phosphorylation on Thr₁₈₈ by MAPK/Cyclin A/cdk2 contributed more to the stabilization of C/EBP尾, Further studies indicated that phosphorylation mimic C/EBP尾 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/EBP尾.