Inheritance of Polycomb-dependent chromosomal interactions in Drosophila
Abstract
Maintenance of cell identity is a complex task that involves multiple layers of regulation, acting at all levels of chromatin packaging, from nucleosomes to folding of chromosomal domains in the cell nucleus. Polycomb-group (PcG) and trithorax-group (trxG) proteins maintain memory of chromatin states through binding at cis-regulatory elements named PcG response elements or cellular memory modules. Fab-7 is a well-defined cellular memory module involved in regulation of the homeotic gene Abdominal-B (Abd-B). In addition to its action in cis, we show here by three-dimensional FISH that the Fab-7 element leads to association of transgenes with each other or with the endogenous Fab-7, even when inserted in different chromosomes. These long-distance interactions enhance PcG-mediated silencing. They depend on PcG proteins, on DNA sequence homology, and on developmental progression. Once long-distance pairing is abolished by removal of the endogenous Fab-7, the derepressed chromatin state induced at the transgene locus can be transmitted through meiosis into a large fraction of the progeny, even after reintroduction of the endogenous Fab-7. Strikingly, meiotic inheritance of the derepressed state involves loss of pairing between endogenous and transgenic Fab-7. This suggests that transmission of nuclear architecture through cell division might contribute to inheritance of chromatin states in eukaryotes.
Keywords
Footnotes
-
Supplemental material is available at http://www.genesdev.org.
-
Article and publication are at http://www.genesdev.org/cgi/doi/10.1101/gad.269503.
-
↵2 Present address: DMGC, Institute of Molecular Genetics, RAS, 2, Kurchatovsq., Moscow, 123182, Russia
-
↵3 Present address: Institute of Molecular Genetics, CNRS, UMR-5535, 1919, Route de Mende, 34293 Montpellier, France.
-
↵4 Corresponding author. E-MAIL Giacomo.Cavalli{at}igh.cnrs.fr; FAX 33-499-61-99-01.
-
- Accepted July 14, 2003.
- Received April 22, 2003.
- Cold Spring Harbor Laboratory Press