Drosophila HP1c is regulated by an auto-regulatory feedback loop through its binding partner Woc.
HP1 is a major component of chromatin and regulates gene expression through its binding to methylated histone H3. Most eukaryotes express at least three isoforms of HP1 with similar domain architecture. However, despite the common specificity for methylated histone H3, the three HP1 isoforms bind to different regions of the genome. Most of the studies so far focused on the HP1a isoform and its role in transcriptional regulation. As HP1a requires additional factors to bind methylated chromatin in vitro, we wondered whether another isoform might also require additional targeting factors. Indeed, we found that HP1c interacts with the DNA binding factors Woc and Row and requires Woc to become targeted to chromatin in vivo. Moreover, we show that the interaction between HP1c and Woc constitutes a transcriptional feedback loop that operates to balance the concentration of HP1c within the cell. This regulation may prevent HP1c from binding to methylated heterochromatin.
Munich Centre of Integrated Protein Science and Adolf-Butenandt Institute, Ludwig Maximilians University of Munich, Munich, Germany.
Jochen
J
Abel
Ragnhild
R
Eskeland
Grazia D
GD
Raffa
Elisabeth
E
Kremmer
Axel
A
Imhof
D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D047468:Immunoprecipitation; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C423364:HP1c protein, Drosophila; D020033:Protein Isoforms; D014157:Transcription Factors; C414987:WOC protein, Drosophila