TY - JOUR
T1 - Daxx mediates the small ubiquitin-like modifier-dependent transcriptional repression of Smad4
AU - Chang, Che Chang
AU - Lin, Ding Yen
AU - Fang, Hsin I.
AU - Chen, Ruey Hwa
AU - Shih, Hsiu Ming
PY - 2005/3/18
Y1 - 2005/3/18
N2 - Daxx has been shown to function as an apoptosis regulator and transcriptional represser via its interaction with various cytoplasmic and nuclear proteins. Here, we showed that Daxx interacts with Smad4 and represses its transcriptional activity via the C-terminal domain of Daxx. In vitro and in vivo interaction studies indicated that the binding of Smad4 to Daxx depends on Smad4 sumoylation. Substitution of Smad4 SUMO conjugation residue lysine 159, but not 113, to arginine not only disrupted Smad4-Daxx interaction but also relieved Daxx-elicited repression of Smad4 transcriptional activity. Furthermore, chromatin immunoprecipitation analyses revealed the recruitment of Daxx to an endogenous, Smad4-targeted promoter in a Lys159 sumoylation-dependent manner. Finally, down-regulation of Daxx expression by RNA interference enhanced transforming growth factor β-induced transcription of reporter and endogenous genes through a Smad4-dependent, but not K159R-Smad4-dependent, manner. Together, these results indicate that Daxx suppresses Smad4-mediated transcriptional activity by direct interaction with the sumoylated Smad4 and identify a novel role of Daxx in regulating transforming growth factor β signaling.
AB - Daxx has been shown to function as an apoptosis regulator and transcriptional represser via its interaction with various cytoplasmic and nuclear proteins. Here, we showed that Daxx interacts with Smad4 and represses its transcriptional activity via the C-terminal domain of Daxx. In vitro and in vivo interaction studies indicated that the binding of Smad4 to Daxx depends on Smad4 sumoylation. Substitution of Smad4 SUMO conjugation residue lysine 159, but not 113, to arginine not only disrupted Smad4-Daxx interaction but also relieved Daxx-elicited repression of Smad4 transcriptional activity. Furthermore, chromatin immunoprecipitation analyses revealed the recruitment of Daxx to an endogenous, Smad4-targeted promoter in a Lys159 sumoylation-dependent manner. Finally, down-regulation of Daxx expression by RNA interference enhanced transforming growth factor β-induced transcription of reporter and endogenous genes through a Smad4-dependent, but not K159R-Smad4-dependent, manner. Together, these results indicate that Daxx suppresses Smad4-mediated transcriptional activity by direct interaction with the sumoylated Smad4 and identify a novel role of Daxx in regulating transforming growth factor β signaling.
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U2 - 10.1074/jbc.M409161200
DO - 10.1074/jbc.M409161200
M3 - Article
C2 - 15637079
AN - SCOPUS:15444380557
SN - 0021-9258
VL - 280
SP - 10164
EP - 10173
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 11
ER -