The Polycomb-group homolog Bmi-1 is a regulator of murine Hox gene expression.
Drosophila homeotic genes and vertebrate Hox genes are involved in the anteroposterior organization of the developing embryo. In Drosophila, the Polycomb- and trithorax-group genes are required to maintain the homeotic genes throughout development in the repressed or activated state, respectively. The murine Bmi-1 proto-oncogene was shown to exhibit homology to the Polycomb-group gene Posteior sex combs. Mice lacking the Bmi-1 gene revealed posterior transformations along the axial skeleton, whereas transgenic mice overexpressing Bmi-1 display anterior transformations. We have analysed the expression patterns of several Hox genes by RNA in situ hybridization on serial sections of 11.5- and 12.5-day Bmi-1 null mutant embryos. Furthermore, we have analysed the expression of a Hoxc-8/LacZ fusion gene in younger embryos. Our analyses show that Bmi-1 is involved in the repression of a subset of Hox genes from different clusters from at least day 9.5 onwards. We discuss the possibility that members of the murine Polycomb-group can form multimeric protein complexes of different compositions with varying affinity or specificity for different subsets of Hox genes.
van der Lugt
N M
NM
Division of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Alkema
M
M
Berns
A
A
Deschamps
J
J
D000367:Age Factors; D000818:Animals; D004622:Embryo, Mammalian / Q000737:chemistry; D005786:Gene Expression Regulation; D005801:Genes, Homeobox / Q000502:physiology*; D017403:In Situ Hybridization; D051379:Mice; D008815:Mice, Inbred Strains; D009024:Morphogenesis / Q000187:drug effects; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology*; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology*; D012313:RNA / Q000032:analysis; D012097:Repressor Proteins; D014018:Tissue Distribution
C489421:Bmi1 protein, mouse; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D012313:RNA; D063150:Polycomb Repressive Complex 1