The Pax3-FKHR oncoprotein is unresponsive to the Pax3-associated repressor hDaxx.
The Pax3-FKHR fusion protein is present in alveolar rhabdomyosarcoma and results from the t(2;13) (q35;q14) chromosomal translocation. Its oncogenic activity is dependent on a combination of protein-DNA and protein-protein interactions mediated by the Pax3 homeodomain recognition helix. In this report we demonstrate that human Daxx (hDaxx) interacts with Pax3 in vivo and with DNA-bound Pax3 in vitro. This interaction is mediated primarily through the homeodomain recognition helix with the additional involvement of the octapeptide domain and its N-terminal flanking amino acids. Through this interaction hDaxx represses the transcriptional activity of Pax3 by approximately 80%. The Pax3-FKHR fusion is unresponsive to this repressive effect despite an observed endogenous interaction with hDaxx in a rhabdomyosarcoma tumor cell line. Therefore, these data support the model that fusion of FKHR to Pax3 not only adds a strong transactivation domain, but also deregulates transcriptional control of Pax3 by overriding the natural repressive effect of hDaxx.
Departments of Genetics, St Jude Children's Research Hospital, 332 North Lauderdale, Memphis, TN 38105, USA.
A D
AD
Hollenbach
J E
JE
Sublett
C J
CJ
McPherson
G
G
Grosveld
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D056970:Co-Repressor Proteins; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion / Q000737:chemistry / Q000378:metabolism*; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012208:Rhabdomyosarcoma / Q000235:genetics; D017384:Sequence Deletion; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D014178:Translocation, Genetic / Q000235:genetics; D015003:Yeasts / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D056970:Co-Repressor Proteins; C106985:DAXX protein, human; D004268:DNA-Binding Proteins; C491473:Daxx protein, mouse; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D000072041:PAX3 Transcription Factor; C489409:PAX3 protein, human; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors; C068686:Pax3 protein, mouse; D004247:DNA