HES6 acts as a transcriptional repressor in myoblasts and can induce the myogenic differentiation program.
HES6 is a novel member of the family of basic helix-loop-helix mammalian homologues of Drosophila Hairy and Enhancer of split. We have analyzed the biochemical and functional roles of HES6 in myoblasts. HES6 interacted with the corepressor transducin-like Enhancer of split 1 in yeast and mammalian cells through its WRPW COOH-terminal motif. HES6 repressed transcription from an N box-containing template and also when tethered to DNA through the GAL4 DNA binding domain. On N box-containing promoters, HES6 cooperated with HES1 to achieve maximal repression. An HES6-VP16 activation domain fusion protein activated the N box-containing reporter, confirming that HES6 bound the N box in muscle cells. The expression of HES6 was induced when myoblasts fused to become differentiated myotubes. Constitutive expression of HES6 in myoblasts inhibited expression of MyoR, a repressor of myogenesis, and induced differentiation, as evidenced by fusion into myotubes and expression of the muscle marker myosin heavy chain. Reciprocally, blocking endogenous HES6 function by using a WRPW-deleted dominant negative HES6 mutant led to increased expression of MyoR and completely blocked the muscle development program. Our results show that HES6 is an important regulator of myogenesis and suggest that MyoR is a target for HES6-dependent transcriptional repression.
Gao
X
X
Genetics Unit, Shriners Hospital for Children, Montréal H3G 1A6, Québec, Canada.
Chandra
T
T
Gratton
M O
MO
Quélo
I
I
Prud'homme
J
J
Stifani
S
S
St-Arnaud
R
R
D021581:Active Transport, Cell Nucleus; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D056970:Co-Repressor Proteins; D018398:Homeodomain Proteins; D006801:Humans; D051379:Mice; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000187:drug effects; D009124:Muscle Proteins / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development; D009687:Nuclear Proteins / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000494:pharmacology* / Q000502:physiology; D000072056:Transcription Factor HES-1; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D020798:Two-Hybrid System Techniques; D015003:Yeasts
D051792:Basic Helix-Loop-Helix Proteins; D056970:Co-Repressor Proteins; D018398:Homeodomain Proteins; D009124:Muscle Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D000072056:Transcription Factor HES-1; D014157:Transcription Factors; C411859:HES6 protein, human; C489734:Hes1 protein, mouse; C486570:Hes6 protein, mouse; C480236:OSTN protein, human; C498449:Ostn protein, mouse; C499043:TLE1 protein, human; C434946:Tle1 protein, mouse; C078493:HES1 protein, human