Comparing active and repressed expression states of genes controlled by the Polycomb/Trithorax group proteins.
Drosophila Polycomb group (PcG) and Trithorax group (TrxG) proteins are responsible for the maintenance of stable transcription patterns of many developmental regulators, such as the homeotic genes. We have used ChIP-on-chip to compare the distribution of several PcG/TrxG proteins, as well as histone modifications in active and repressed genes across the two homeotic complexes ANT-C and BX-C. Our data indicate the colocalization of the Polycomb repressive complex 1 (PRC1) with Trx and the DNA binding protein Pleiohomeotic (Pho) at discrete sequence elements as well as significant chromatin assembly differences in active and inactive regions. Trx binds to the promoters of active genes and noncoding transcripts. Most strikingly, in the active state, Pho covers extended chromatin domains over many kilobases. This feature of Pho, observed on many polytene chromosome puffs, reflects a previously undescribed function. At the hsp70 gene, we demonstrate in mutants that Pho is required for transcriptional recovery after heat shock. Besides its presumptive function in recruiting PcG complexes to their site of action, our results now uncover that Pho plays an additional role in the repression of already induced genes.
Beisel
Christian
C
Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany.
Buness
Andreas
A
Roustan-Espinosa
Ian M
IM
Koch
Britta
B
Schmitt
Sabine
S
Haas
Stefan A
SA
Hild
Marc
M
Katsuyama
Tomonori
T
Paro
Renato
R
D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D020868:Gene Silencing; D017344:Genes, Insect; D020411:Oligonucleotide Array Sequence Analysis; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C113295:pho protein, Drosophila