The Polycomb group protein CRAMPED is involved with TRF2 in the activation of the histone H1 gene
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CRAMPED (CRM), conserved from plants to animals, was previously characterized genetically as a repressive factor involved in the formation of facultative and constitutive heterochromatin (Polycomb silencing, position effect variegation). We show that crm is dynamically regulated during replication and identify the Histone gene cluster (His-C) as a major CRM target. Surprisingly, CRM is specifically required for the expression of the Histone H1 gene, like the promoter-bound transcription factor TRF2. Consistently with this, CRM genetically interacts and co-immunoprecipitates with TRF2. However, the Polycomb phenotypes observed in crm mutants are not observed in TRF2 hypomorphic mutants, suggesting that they correspond to independent roles of CRM. CRM is thus a highly pleiotropic factor involved in both activation and repression.
KeywordsSalivary Gland TATA Binding Protein Polycomb Group Protein Position Effect Variegation PhiC31 Integrase
We would like to thank all members of the Spierer, Pauli and Karch laboratories for stimulating discussions, in particular, Rob Maeda. We thank the Bloomington Drosophila Stock Center for the TRF2 G0039 and H2Av–RFP lines, Joseph Gall for the UAS–DLsm11–Venus line, Walter Gehring for the anti-CRM antibody, Frédérique Peronnet for the anti-PCNA antibody, and Robert Tjian for the anti-TRF2 antibody. We thank Mylène Docquier and Didier Chollet for their assistance at the genomic platform, Geneva.
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