Promyelocytic leukemia protein (PML) functions as a glucocorticoid receptor co-activator by sequestering Daxx to the PML oncogenic domains (PODs) to enhance its transactivation potential.
Daxx has been reported to function as a transcriptional modulator in the nucleus. In the present study, we have explored the role of Daxx in regulating the transcriptional activity of the glucocorticoid receptor (GR). Overexpression of Daxx suppressed GR-mediated activation of the mouse mammary tumor virus promoter in COS-1, HeLa, and 293T cells. In vitro and in vivo studies revealed that Daxx could directly bind to GR. The mapping analysis further demonstrated that the C-terminal region of Daxx-(501-740) mediates the interaction and transcriptional repression of GR. The repressive effect of Daxx and Daxx-(501-740) on GR could be alleviated by co-expression of promyelocytic leukemia protein (PML). Furthermore, immunofluorescence analysis showed that overexpression of wild-type PML results in the translocation of Daxx and Daxx-(501-740) to the PML oncogenic domains (PODs). By contrast, a PML sumoylation-defective mutant failed to recruit Daxx to PODs and to reverse the Daxx repression effect on GR. Accordingly, As(2)O(3) treatment rendered the sequestration of endogenous Daxx to the PODs, leading to an enhancement of GR transactivation in COS-1 cells. Taken together, these findings suggest that recruitment of Daxx into the subnuclear POD structures sequesters it from the GR/co-activators complex, thereby alleviating its repressive effects. Our present studies provide the important link between Daxx/PML interaction and GR transcriptional activation.
Lin
Ding-Yen
DY
Graduate Institute of Life Sciences, National Defense Medical Center, 128 Sec2 Yen-Chiu-Yuan Road, Taipei 11529, Taiwan, Republic of China.
Lai
Ming-Zong
MZ
Ann
David K
DK
Shih
Hsiu-Ming
HM
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000502:physiology*; D056970:Co-Repressor Proteins; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D018832:Molecular Chaperones; D009363:Neoplasm Proteins / Q000502:physiology*; D009687:Nuclear Proteins / Q000737:chemistry / Q000502:physiology*; D010087:Oxides / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D000071156:Promyelocytic Leukemia Protein; D011965:Receptors, Glucocorticoid / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*; D015533:Transcriptional Activation; D025521:Tumor Suppressor Proteins
D048868:Adaptor Proteins, Signal Transducing; D001152:Arsenicals; D002352:Carrier Proteins; D056970:Co-Repressor Proteins; C106985:DAXX protein, human; C491473:Daxx protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010087:Oxides; C513293:Pml protein, mouse; D000071156:Promyelocytic Leukemia Protein; D011965:Receptors, Glucocorticoid; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human; D000077237:Arsenic Trioxide