Mnt: a novel Max-interacting protein and Myc antagonist.
We have identified a novel Max-binding protein, Mnt, which belongs to neither the Myc nor the Mad families (Hurlin et al. 1997). Mnt interacts with Max in vivo and functions as a transcriptional repressor of reporter genes containing promoter-proximal CACGTG sites. Mnt:Max complexes also efficiently suppress Myc-dependent activation from the same promoter. Transcription repression by Mnt maps to a 13 amino acid N-terminal region related to the Sin3 interaction domain (SID) of Mad proteins. This region of Mnt mediates interaction with mSin3 corepressor proteins and its deletion converts Mnt from a repressor to an activator and from a suppressor of Myc-dependent transformation to a cooperating oncogene. This latter result suggests that Mnt and Myc regulate an overlapping set of target genes in vivo. Expression of mnt RNA is observed in many tissues and in both proliferating and differentiating cells. Likewise, Mnt protein is expressed in many proliferating cell types in culture where both Myc:Max and Mnt:Max complexes are detected. An exception is P19 embryonal carcinoma cells, where Mnt is expressed and in a complex with Max, but Myc proteins are not detected. Mnt is likely to be a key regulator of Myc activities in vivo and, in addition, may possess Myc-independent functions.
Hurlin
P J
PJ
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98104, USA.
Qúeva
C
C
Eisenman
R N
RN
D000818:Animals; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D001665:Binding Sites / Q000235:genetics; D002455:Cell Division; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051379:Mice; D016271:Proto-Oncogene Proteins c-myc / Q000037:antagonists & inhibitors*; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; C067850:Myc associated factor X; D016271:Proto-Oncogene Proteins c-myc; D012097:Repressor Proteins; D014157:Transcription Factors; C068422:Max protein, mouse; D004247:DNA