p300-dependent acetylation of activating transcription factor 5 enhances C/EBPβ transactivation of C/EBPα during 3T3-L1 differentiation.
Adipogenesis is a multistep process by which 3T3-L1 preadipocytes differentiate into mature adipocytes through mitotic clonal expansion (MCE) and terminal differentiation. The CCAAT/enhancer-binding protein β (C/EBPβ) is an important transcription factor that takes part in both of these processes. C/EBPβ not only transactivates C/EBPα and the peroxisome proliferator-activated receptor γ (PPARγ), which cause 3T3-L1 preadipocytes to enter terminal adipocyte differentiation, but also is required to activate cell cycle genes necessary for MCE. The identification of potential cofactors of C/EBPβ will help to explain how C/EBPβ undertakes these specialized roles during the different stages of adipogenesis. In this study, we found that activating transcription factor 5 (ATF5) can bind to the promoter of C/EBPα via its direct interaction with C/EBPβ (which is mediated via the p300-dependent acetylation of ATF5), leading to enhanced C/EBPβ transactivation of C/EBPα. We also show that p300 is important for the interaction of ATF5 with C/EBPβ as well as for the binding activity of this complex on the C/EBPα promoter. Consistent with these findings, overexpression of ATF5 and an acetylated ATF5 mimic both promoted 3T3-L1 adipocyte differentiation, whereas short interfering RNA-mediated ATF5 downregulation inhibited this process. Furthermore, we show that the elevated expression of ATF5 is correlated with an obese phenotype in both mice and humans. In summary, we have identified ATF5 as a new cofactor of C/EBPβ and examined how C/EBPβ and ATF5 (acetylated by a p300-dependent mechanism) regulate the transcription of C/EBPα.
Key Laboratory of Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai, People's Republic of China.
Yue
Y
Zhao
Ya-Dong
YD
Zhang
You-You
YY
Zhang
Shu-Wen
SW
Qian
Zhi-Chun
ZC
Zhang
Shu-Fen
SF
Li
Liang
L
Guo
Yuan
Y
Liu
Bo
B
Wen
Qun-Ying
QY
Lei
Qi-Qun
QQ
Tang
Xi
X
Li
D041721:3T3-L1 Cells; D000107:Acetylation; D051696:Activating Transcription Factors / Q000235:genetics / Q000378:metabolism*; D050156:Adipogenesis / Q000235:genetics / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics / Q000378:metabolism*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D050881:E1A-Associated p300 Protein / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation
D051696:Activating Transcription Factors; C471855:Atf5 protein, mouse; D022763:CCAAT-Enhancer-Binding Protein-alpha; D022782:CCAAT-Enhancer-Binding Protein-beta; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse