Abstract
The Polycomb group (Pc-G) genes encode proteins that assemble into complexes implicated in the epigenetic maintenance of heritable patterns of expression of developmental genes, a function largely conserved from Drosophila to mammals and plants. The Pc-G is thought to act at the chromatin level to silence expression of target genes; however, little is known about the molecular basis of this repression. In keeping with the evidence that Pc-G homologs in higher vertebrates exist in related pairs, we report here the isolation of XPc1, a second Polycomb homolog in Xenopus laevis. We show that XPc1 message is maternally deposited in a translationally masked form in Xenopus oocytes, with XPc1 protein first appearing in embryonic nuclei shortly after the blastula stage. XPc1 acts as a transcriptional repressor in vivo when tethered to a promoter in Xenopus embryos. We find that XPc1-mediated repression can be only partially alleviated by an increase in transcription factor dosage and that inhibition of deacetylase activity by trichostatin A treatment has no effect on XPc1 repression, suggesting that histone deacetylation does not form the basis for Pc-G-mediated repression in our assay.
| Original language | English |
|---|---|
| Pages (from-to) | 3958-68 |
| Number of pages | 11 |
| Journal | Molecular and Cellular Biology |
| Volume | 19 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - Jun 1999 |
Keywords
- Amino Acid Sequence
- Animals
- Blotting, Northern
- Blotting, Western
- Cell Nucleus/metabolism
- Centrifugation, Density Gradient
- Enzyme Inhibitors/pharmacology
- Gene Expression Regulation, Developmental
- Genes, Reporter
- Histone Deacetylases/physiology
- Hydroxamic Acids/pharmacology
- Molecular Sequence Data
- Phosphorylation
- Repressor Proteins/genetics
- Sequence Homology, Amino Acid
- Time Factors
- Tissue Distribution
- Transcription Factors
- Transcription, Genetic
- Xenopus Proteins
- Xenopus laevis/embryology