A cellular memory module conveys epigenetic inheritance of hedgehog expression during Drosophila wing imaginal disc development.
In Drosophila, the Trithorax-group (trxG) and Polycomb-group (PcG) proteins interact with chromosomal elements, termed Cellular Memory Modules (CMMs). By modifying chromatin, this ensures a stable heritable maintenance of the transcriptional state of developmental regulators, like the homeotic genes, that is defined embryonically. We asked whether such CMMs could also control expression of genes involved in patterning imaginal discs during larval development. Our results demonstrate that expression of the hedgehog gene, once activated, is maintained by a CMM. In addition, our experiments indicate that the switching of such CMMs to an active state during larval stages, in contrast to embryonic stages, may require specific trans-activators. Our results suggest that the patterning of cells in particular developmental fields in the imaginal discs does not only rely on external cues from morphogens, but also depends on the previous history of the cells, as the control by CMMs ensures a preformatted gene expression pattern.
Maurange
Cédric
C
Zentrum für Molekulare Biologie Heidelberg (ZMBH), University of Heidelberg, D-69120 Heidelberg, Germany.
Paro
Renato
R
D000818:Animals; D030801:Animals, Genetically Modified; D002455:Cell Division / Q000502:physiology; D002843:Chromatin / Q000235:genetics*; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development; D004625:Embryo, Nonmammalian; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins; D017403:In Situ Hybridization; D007814:Larva / Q000166:cytology; D008568:Memory / Q000502:physiology; D063150:Polycomb Repressive Complex 1; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors; D015533:Transcriptional Activation; D014921:Wings, Animal / Q000166:cytology
D002843:Chromatin; D017931:DNA Primers; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D053823:Hedgehog Proteins; C066770:Pc protein, Drosophila; D012333:RNA, Messenger; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C077245:hh protein, Drosophila; D063150:Polycomb Repressive Complex 1