Abstract
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.
Original language | English (US) |
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Pages (from-to) | 688-693 |
Number of pages | 6 |
Journal | Current Biology |
Volume | 19 |
Issue number | 8 |
DOIs | |
State | Published - Apr 28 2009 |
Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Agricultural and Biological Sciences(all)
- Biochemistry, Genetics and Molecular Biology(all)
Keywords
- DEVBIO
- DNA