Transcriptional repression of hDaxx enhanced by adenovirus 12 E1B 55-kDa oncoprotein interacting with hDaxx.
BACKGROUND
Daxx has been identified as a nuclear protein that involves in apoptosis and transcriptional repression. Daxx co-localizes with the promyelocytic leukemia (PML) protein and regulates transcription. Human Daxx (hDaxx) is a protein that functions as a transcriptional regulation through its interaction with some DNA-associated proteins. The aim of this study was to explore the transcriptional regulatory effect of hDaxx interacting with adenovirus (Ad) 12 E1B (Ad12E1B) 55-kDa oncoprotein.


METHODS
The co-localization of hDaxx-Ad12E1B or hDaxx-PML protein in the nucleus was observed under a confocal microscope. Interaction of hDaxx and Ad12E1B was analyzed by yeast two-hybrid assay. Direct binding of hDaxx and Ad12E1B was analyzed using coimmunoprecipitation and Western blot in vivo and in vitro. The activity of a luciferase reporter gene, which was regulated by an hDaxx modulated thymidine kinase (TK) promoter, was detected in an automat luminometer.


RESULTS
Ad12E1B, which co-localized with hDaxx in the nuclei of G401-CC3 cells, disrupted the co-localization of hDaxx and PML in the PML oncogenic domains (PODs). hDaxx bound directly to Ad12E1B in vivo and in vitro. hDaxx interacted with Ad12E1B along its full length. Ad12E1B enhanced transcriptional repression activity of hDaxx.


CONCLUSIONS
Ad12E1B disrupts the co-localization of hDaxx with PML in PODs and enhances transcriptional repression activity of hDaxx.
Wan
Yan-ping
YP
Institute of Pathogenic Biology, Nanhua University, Hengyang 421001, China. yanpingwan@hotmail.com
Wu
Yi-mou
YM
Zhu
Cui-ming
CM
Yin
Wei-guo
WG
Cai
Heng-ling
HL
Yu
Min-jun
MJ
D048868:Adaptor Proteins, Signal Transducing; D017501:Adenovirus E1B Proteins / Q000502:physiology*; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics*; D045744:Cell Line, Tumor; D056970:Co-Repressor Proteins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins / Q000032:analysis; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics*; D000071156:Promyelocytic Leukemia Protein; D012097:Repressor Proteins / Q000502:physiology*; D014157:Transcription Factors / Q000032:analysis; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins
D048868:Adaptor Proteins, Signal Transducing; D017501:Adenovirus E1B Proteins; D002352:Carrier Proteins; D056970:Co-Repressor Proteins; C106985:DAXX protein, human; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D012097:Repressor Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human