delta Ef1 binds to a far upstream sequence of the mouse pro-alpha 1(I) collagen gene and represses its expression in osteoblasts.
The transcription of type I collagen genes is tightly regulated, but few cis-acting elements have been identified that can modulate the levels of expression of these genes. Generation of transgenic mice harboring various segments of the mouse pro-alpha1(I) collagen promoter led us to suspect that a repressor element was located between -10.5 and -17 kilobase pairs. Stable and transient transfection experiments in ROS17/2.8 osteoblastic cells confirmed the existence of such a repressor element at about -14 kilobase pairs and showed that it consisted in an almost perfect three-time repeat of a 41-base pair sequence. This element, which we named COIN-1, contains three E2-boxes, and a point mutation in at least two of them completely abolished its repressor effect. In gel shift assays, COIN-1 bound a DNA-binding protein named delta EF1/ZEB-1, and mutations that abolished the repressor effect of COIN-1 also suppressed the binding of delta EF1. We also showed that the repressor effect of COIN-1 was not mediated by chromatin compaction. Furthermore, overexpression of delta EF1 in ROS17/2.8 osteoblastic cells enhanced the inhibitory effect of COIN-1 in a dose-dependent manner and repressed the expression of the pro-alpha 1(I) collagen gene. Thus, delta EF1 appears to repress the expression of the mouse pro-alpha 1(I) collagen gene, through its binding to COIN-1.
Terraz
C
C
INSERM U489 and Université Paris VI, Paris, France.
Toman
D
D
Delauche
M
M
Ronco
P
P
Rossert
J
J
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002843:Chromatin / Q000737:chemistry; D024042:Collagen Type I / Q000235:genetics*; D004247:DNA / Q000032:analysis; D017353:Gene Deletion; D020868:Gene Silencing; D017930:Genes, Reporter; D016678:Genome; D018398:Homeodomain Proteins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D010006:Osteoblasts / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000502:physiology*; D051381:Rats; D014157:Transcription Factors; D014162:Transfection; D000071799:Zinc Finger E-box-Binding Homeobox 1
D002843:Chromatin; D024042:Collagen Type I; D004247:DNA; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D000071799:Zinc Finger E-box-Binding Homeobox 1; C000630720:ZEB1 protein, rat; C519422:ZEB1 protein, mouse