The ENL moiety of the childhood leukemia-associated MLL-ENL oncoprotein recruits human Polycomb 3.
The translocation t(11;19) is frequently found in acute leukemia in infants. This event truncates the proto-oncogene MLL and fuses the 5' end of MLL in frame with the ENL gene. ENL contributes a crucial protein-protein interaction domain to the resulting oncoprotein MLL-ENL. Here we show by yeast two-hybrid assays, GST-pull-down experiments and in a far western blot analysis that this domain is necessary and sufficient to recruit a novel member of the human Polycomb protein family (hPc3). hPc3 RNA was detected throughout the human hematopoietic system. Similar to other Polycomb proteins hPc3 acts as a transcriptional repressor. The ENL-hPc3 interaction was verified by mutual co-precipitation of the proteins from cell extracts. ENL and hPc3 tagged with fluorescent proteins co-localized in living cells in a nuclear dot pattern. An internal region of hPc3 was responsible for binding to ENL. Finally, hPc3 binds to the C-terminus of AF9, another common MLL fusion partner. The recruitment of a repressive function by ENL opens up a new insight into a possible mechanism of leukemogenesis by the fusion protein MLL-ENL.
García-Cuéllar
M P
MP
Department of Genetics, University of Erlangen, Staudtstrasse 5, 91058 Erlangen, Germany.
Zilles
O
O
Schreiner
S A
SA
Birke
M
M
Winkler
T H
TH
Slany
R K
RK
D000595:Amino Acid Sequence; D001665:Binding Sites; D015153:Blotting, Western; D002451:Cell Compartmentation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D007223:Infant; D007938:Leukemia / Q000209:etiology*; D008969:Molecular Sequence Data; D051788:Myeloid-Lymphoid Leukemia Protein; D009363:Neoplasm Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D015514:Oncogene Proteins, Fusion / Q000378:metabolism*; D063146:Polycomb-Group Proteins; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D000090063:Proto-Oncogene Mas; D011519:Proto-Oncogenes; D012097:Repressor Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D014178:Translocation, Genetic; D020798:Two-Hybrid System Techniques
D004268:DNA-Binding Proteins; C497422:KMT2A protein, human; C000715470:MAS1 protein, human; C425207:MLL-ENL oncoprotein, human; C081448:MLLT1 protein, human; C489901:MLLT3 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D063146:Polycomb-Group Proteins; D000090063:Proto-Oncogene Mas; D012097:Repressor Proteins; D014157:Transcription Factors; D051788:Myeloid-Lymphoid Leukemia Protein; D011495:Histone-Lysine N-Methyltransferase