Reference Report

Reference
Citation	Garcia, M., Stathopoulos, A. (2011). Lateral gene expression in Drosophila early embryos is supported by grainyhead-mediated activation and tiers of dorsally-localized repression. PLoS ONE 6(12): e29172. (Export to RIS)
FlyBase ID	FBrf0217082
Publication Type	Research paper
PubMed ID	22216201
PubMed Abstract	The general consensus in the field is that limiting amounts of the transcription factor Dorsal establish dorsal boundaries of genes expressed along the dorsal-ventral (DV) axis of early Drosophila embryos, while repressors establish ventral boundaries. Yet recent studies have provided evidence that repressors act to specify the dorsal boundary of intermediate neuroblasts defective (ind), a gene expressed in a stripe along the DV axis in lateral regions of the embryo. Here we show that a short 12 base pair sequence ("the A-box") present twice within the ind CRM is both necessary and sufficient to support transcriptional repression in dorsal regions of embryos. To identify binding factors, we conducted affinity chromatography using the A-box element and found a number of DNA-binding proteins and chromatin-associated factors using mass spectroscopy. Only Grainyhead (Grh), a CP2 transcription factor with a unique DNA-binding domain, was found to bind the A-box sequence. Our results suggest that Grh acts as an activator to support expression of ind, which was surprising as we identified this factor using an element that mediates dorsally-localized repression. Grh and Dorsal both contribute to ind transcriptional activation. However, another recent study found that the repressor Capicua (Cic) also binds to the A-box sequence. While Cic was not identified through our A-box affinity chromatography, utilization of the same site, the A-box, by both factors Grh (activator) and Cic (repressor) may also support a "switch-like" response that helps to sharpen the ind dorsal boundary. Furthermore, our results also demonstrate that TGF-β signaling acts to refine ind CRM expression in an A-box independent manner in dorsal-most regions, suggesting that tiers of repression act in dorsal regions of the embryo.
DOI	10.1371/journal.pone.0029172
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Language of Publication	English
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Publication Type	Journal
Abbreviation	PLoS ONE
Title	PLoS ONE
Publication Year	2006-
ISBN/ISSN	1932-6203
Data from Reference
Aberrations (1)
	Df(2R)Pcl7B
Alleles (17)
	brk^M68 cic¹ Ecol\lacZ^{Abox.eve.st3.Abox} Ecol\lacZ^{Abox.eve.st3.ind.1.4} Ecol\lacZ^Abox.ind.1.4 Ecol\lacZ^{Abox.SMM.ind.1.4} Ecol\lacZ^dl.ind.1.4 Ecol\lacZ^eve.C Ecol\lacZ^{eve.st3.ind.1.4.eve} Ecol\lacZ^ind.1.4.eve Egfr^f2 grh^B37 grh^IM pip¹ pip² sog^Y506 Tl^r4
Constructs (8)
	P{Abox-eve-st3-Abox-lacZ} P{eve-lacZ.C} P{eve-st3-ind1.4-lacZ.Abox} P{ind1.4-eve-lacZ} P{ind1.4-lacZ.Abox.SMM} P{ind1.4-lacZ.Abox} P{ind1.4-lacZ.dl} P{st3-ind1.4-eve-lacZ}
Genes (29)
	Acf1 bl brk Caf1-180 CG3509 cic dodeca Dsp1 Ecol\lacZ Egfr grh His3 hkb ind pip pont psq Rel rept shn sog Ssrp Su(H) Su(var)3-9 Tl tlk tll vnd zen
Natural transposons (1)
	P-element