TitleRegulation of Hox gene activity by transcriptional elongation in Drosophila.
Publication TypeJournal Article
Year of Publication2009
AuthorsChopra, VS, Hong, J-W, Levine, M
JournalCurr Biol
Date Published2009 Apr 28
KeywordsAnimals, Body Patterning, Cyclin-Dependent Kinase 9, Drosophila melanogaster, Drosophila Proteins, Gene Expression Regulation, Developmental, Genes, Homeobox, Homeodomain Proteins, Mutation, Phenotype, Promoter Regions, Genetic, Transcription Factors, Transcription, Genetic, Transcriptional Elongation Factors, Wing

Hox genes control the anterior-posterior patterning of most metazoan embryos. Their sequential expression is initially established by the segmentation gene cascade in the early Drosophila embryo [1]. The maintenance of these patterns depends on the Polycomb group (PcG) and trithorax group (trxG) complexes during the remainder of the life cycle [2]. We provide both genetic and molecular evidence that the Hox genes are subject to an additional tier of regulation, i.e., at the level of transcription elongation. Both Ultrabithorax (Ubx) and Abdominal-B (Abd-B) genes contain stalled or paused RNA polymerase II (Pol II) even when silent [3, 4]. The Pol II elongation factors Elongin-A and Cdk9 are essential for optimal Ubx and Abd-B expression. Mitotic recombination assays suggest that these elongation factors are also important for the regulation of Notch-, EGF-, and Dpp-signaling genes. Stalled Pol II persists in tissues where Ubx and Abd-B are silenced by the PcG complex. We propose that stalling fosters both the rapid induction and precise silencing of Hox gene expression during development.

Alternate JournalCurr. Biol.