Interaction of mouse polycomb-group (Pc-G) proteins Enx1 and Enx2 with Eed: indication for separate Pc-G complexes.
The Polycomb group (Pc-G) constitutes an important, functionally conserved group of proteins, required to stably maintain inactive homeobox genes repressed during development. Drosophila extra sex combs (esc) and its mammalian homolog embryonic ectoderm development (eed) are special Pc-G members, in that they are required early during development when Pc-G repression is initiated, a process that is still poorly understood. To get insight in the molecular function of Eed, we searched for Eed-interacting proteins, using the yeast two-hybrid method. Here we describe the specific in vivo binding of Eed to Enx1 and Enx2, two mammalian homologs of the essential Drosophila Pc-G gene Enhancer-of-zeste [E(z)]. No direct biochemical interactions were found between Eed/Enx and a previously characterized mouse Pc-G protein complex, containing several mouse Pc-G proteins including mouse polyhomeotic (Mph1). This suggests that different Pc-G complexes with distinct functions may exist. However, partial colocalization of Enx1 and Mph1 to subnuclear domains may point to more transient interactions between these complexes, in support of a bridging role for Enx1.
van Lohuizen
M
M
Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands. Lohuizen@NKI.NL
Tijms
M
M
Voncken
J W
JW
Schumacher
A
A
Magnuson
T
T
Wientjens
E
E
D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism; D004330:Drosophila / Q000378:metabolism; D029721:Drosophila Proteins; D018507:Gene Expression Regulation, Developmental; D015723:Gene Library; D019476:Insect Proteins / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism; D010449:Peptide Mapping; D063150:Polycomb Repressive Complex 1; D063151:Polycomb Repressive Complex 2; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D029721:Drosophila Proteins; C107275:Eed protein, mouse; D019476:Insect Proteins; D009687:Nuclear Proteins; C103827:Phc1 protein, mouse; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C083329:E(z) protein, Drosophila; D063151:Polycomb Repressive Complex 2; D063150:Polycomb Repressive Complex 1