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Lateral Gene Expression in Drosophila Early Embryos Is Supported by Grainyhead-Mediated Activation and Tiers of Dorsally-Localized Repression

Garcia, Mayra and Stathopoulos, Angelike (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. ISSN 1932-6203. PMCID PMC3245246.

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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.

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Stathopoulos, Angelike0000-0001-6597-2036
Additional Information:© 2011 Garcia, Stathopoulos. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Received: August 8, 2011; Accepted: November 22, 2011; Published: December 22, 2011. This study was supported by a predoctoral NSF fellowship to M.G. and grant R01GM077668 from the NIH to A.S. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We are grateful to Carl Parker for helping to make the nuclear extract and for general advice and guidance on the affinity chromatography. We also thank Sonja Hess and the Proteome Exploration Laboratory at the Beckman Institute of the California Institute of Technology for their assistance with the mass spectrometry. Author Contributions: Conceived and designed the experiments: MG AS. Performed the experiments: MG. Analyzed the data: MG AS. Contributed reagents/ materials/analysis tools: MG AS. Wrote the paper: MG AS.
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NSF Predoctoral Fellowship UNSPECIFIED
Issue or Number:12
PubMed Central ID:PMC3245246
Record Number:CaltechAUTHORS:20120306-111145338
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Official 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. doi:10.1371/journal.pone.0029172
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29592
Deposited By: Jason Perez
Deposited On:14 Mar 2012 15:40
Last Modified:03 Oct 2019 03:42

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