Limits...
Genomic analysis of the ecdysone steroid signal at metamorphosis onset using ecdysoneless and EcR Drosophila melanogaster mutants.

Davis MB, Li T - Genes Genomics (2013)

Bottom Line: Around 12 % of the genome responds to the ecdysone hormone signal at the onset of metamorphosis and over half of these are independent of the receptor.In addition, a significant portion of receptor regulated genes are differentially regulated by the receptor, depending on its ligand state.Gene ontology enrichment analyses confirm known ecdysone regulated biological functions and also validate implicated pathways that have been indirectly associated with ecdysone signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Coverdell Biomedical Research Center, University of Georgia, 500 DW Brooks Dr S 270C, Athens, GA 30602 USA.

ABSTRACT
Steroid hormone gene regulation is often depicted as a linear transduction of the signal, from molecule release to the gene level, by activation of a receptor protein after being bound by its steroid ligand. Such an action would require that the hormone be present and bound to the receptor in order to have target gene response. Here, we present data that presents a novel perspective of hormone gene regulation, where the hormone molecule and its receptor have exclusive target gene regulation function, in addition to the traditional direct target genes. Our study is the first genome-wide analysis of conditional mutants simultaneously modeling the steroid and steroid receptor gene expression regulation. We have integrated classical genetic mutant experiments with functional genomics techniques in the Drosophila melanogaster model organism, where we interrogate the 20-hydroxyecdysone signaling response at the onset of metamorphosis. Our novel catalog of ecdysone target genes illustrates the separable transcriptional responses among the hormone, the pre-hormone receptor and the post-hormone receptor. We successfully detected traditional ecdysone target genes as common targets and also identified novel sets of target genes which where exclusive to each mutant condition. Around 12 % of the genome responds to the ecdysone hormone signal at the onset of metamorphosis and over half of these are independent of the receptor. In addition, a significant portion of receptor regulated genes are differentially regulated by the receptor, depending on its ligand state. Gene ontology enrichment analyses confirm known ecdysone regulated biological functions and also validate implicated pathways that have been indirectly associated with ecdysone signaling.

No MeSH data available.


Related in: MedlinePlus

A subset of common EcR-target genes show opposing polarity of regulation. a Scatter plot of BG-EcR-and WPP-EcR- common target genes’ fold changes. The fold change of BG-EcR-relative to BG-CS expression is plotted on the X axis. The fold change WPP-EcR- relative to WPP-CS expression is plotted on the Y axis. b A line graph displaying the normal expression pattern of a set of opposing polarity response targets, the sgs gene cluster, at the onset of metamorphosis in CS. These genes are first upregulated at BG and CG and then are actively repressed across the onset of metamorphosis at WPP. c A bar graph showing the opposing response of these genes upon the removal of the pre-pulse EcR (BG-EcR-) causes a downregulation of the gene cluster at a time point they are normally activated. Conversely, removal of the post-pulse EcR (WPP-EcR-) causes upregulation of the gene cluster at a time point they are normally repressed. These data indicate that the ligand binding status of the receptor can impact whether specific target genes are repressed or activated, albeit regulated by the receptor in both bound and unbound states
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3585846&req=5

Fig8: A subset of common EcR-target genes show opposing polarity of regulation. a Scatter plot of BG-EcR-and WPP-EcR- common target genes’ fold changes. The fold change of BG-EcR-relative to BG-CS expression is plotted on the X axis. The fold change WPP-EcR- relative to WPP-CS expression is plotted on the Y axis. b A line graph displaying the normal expression pattern of a set of opposing polarity response targets, the sgs gene cluster, at the onset of metamorphosis in CS. These genes are first upregulated at BG and CG and then are actively repressed across the onset of metamorphosis at WPP. c A bar graph showing the opposing response of these genes upon the removal of the pre-pulse EcR (BG-EcR-) causes a downregulation of the gene cluster at a time point they are normally activated. Conversely, removal of the post-pulse EcR (WPP-EcR-) causes upregulation of the gene cluster at a time point they are normally repressed. These data indicate that the ligand binding status of the receptor can impact whether specific target genes are repressed or activated, albeit regulated by the receptor in both bound and unbound states

Mentions: While there are some distinct targets exclusive to the ligand bound or unliganded receptor, there is also a large overlap between the two EcR-categories (Fig. 2), indicating the receptor regulates many of the same genes pre-hormone pulse (unliganded) as post-hormone pulse (ligand bound). An investigation of the common EcR target genes reveals that the polarity of transcriptional response is not always the same between the unliganded and ligand bound receptors for these common target genes (Fig. 7). Specifically, 531 genes are common targets between the pre and post-hormone EcR, 134 are shared up-regulated and 123 are down-regulated. The remaining 274 genes have opposite polarity in gene expression changes. We anticipate such a finding, as an example of genes that are actively repressed by the receptor and then become actively stimulated upon ligand binding, and vice versa. Figure 8b, c show a subset of classical ecdysone targets (SGS genes) that are known to be actively transcribed, under regulation of EcR, and then repressed at the onset of metamorphosis.Fig. 7


Genomic analysis of the ecdysone steroid signal at metamorphosis onset using ecdysoneless and EcR Drosophila melanogaster mutants.

Davis MB, Li T - Genes Genomics (2013)

A subset of common EcR-target genes show opposing polarity of regulation. a Scatter plot of BG-EcR-and WPP-EcR- common target genes’ fold changes. The fold change of BG-EcR-relative to BG-CS expression is plotted on the X axis. The fold change WPP-EcR- relative to WPP-CS expression is plotted on the Y axis. b A line graph displaying the normal expression pattern of a set of opposing polarity response targets, the sgs gene cluster, at the onset of metamorphosis in CS. These genes are first upregulated at BG and CG and then are actively repressed across the onset of metamorphosis at WPP. c A bar graph showing the opposing response of these genes upon the removal of the pre-pulse EcR (BG-EcR-) causes a downregulation of the gene cluster at a time point they are normally activated. Conversely, removal of the post-pulse EcR (WPP-EcR-) causes upregulation of the gene cluster at a time point they are normally repressed. These data indicate that the ligand binding status of the receptor can impact whether specific target genes are repressed or activated, albeit regulated by the receptor in both bound and unbound states
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585846&req=5

Fig8: A subset of common EcR-target genes show opposing polarity of regulation. a Scatter plot of BG-EcR-and WPP-EcR- common target genes’ fold changes. The fold change of BG-EcR-relative to BG-CS expression is plotted on the X axis. The fold change WPP-EcR- relative to WPP-CS expression is plotted on the Y axis. b A line graph displaying the normal expression pattern of a set of opposing polarity response targets, the sgs gene cluster, at the onset of metamorphosis in CS. These genes are first upregulated at BG and CG and then are actively repressed across the onset of metamorphosis at WPP. c A bar graph showing the opposing response of these genes upon the removal of the pre-pulse EcR (BG-EcR-) causes a downregulation of the gene cluster at a time point they are normally activated. Conversely, removal of the post-pulse EcR (WPP-EcR-) causes upregulation of the gene cluster at a time point they are normally repressed. These data indicate that the ligand binding status of the receptor can impact whether specific target genes are repressed or activated, albeit regulated by the receptor in both bound and unbound states
Mentions: While there are some distinct targets exclusive to the ligand bound or unliganded receptor, there is also a large overlap between the two EcR-categories (Fig. 2), indicating the receptor regulates many of the same genes pre-hormone pulse (unliganded) as post-hormone pulse (ligand bound). An investigation of the common EcR target genes reveals that the polarity of transcriptional response is not always the same between the unliganded and ligand bound receptors for these common target genes (Fig. 7). Specifically, 531 genes are common targets between the pre and post-hormone EcR, 134 are shared up-regulated and 123 are down-regulated. The remaining 274 genes have opposite polarity in gene expression changes. We anticipate such a finding, as an example of genes that are actively repressed by the receptor and then become actively stimulated upon ligand binding, and vice versa. Figure 8b, c show a subset of classical ecdysone targets (SGS genes) that are known to be actively transcribed, under regulation of EcR, and then repressed at the onset of metamorphosis.Fig. 7

Bottom Line: Around 12 % of the genome responds to the ecdysone hormone signal at the onset of metamorphosis and over half of these are independent of the receptor.In addition, a significant portion of receptor regulated genes are differentially regulated by the receptor, depending on its ligand state.Gene ontology enrichment analyses confirm known ecdysone regulated biological functions and also validate implicated pathways that have been indirectly associated with ecdysone signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Coverdell Biomedical Research Center, University of Georgia, 500 DW Brooks Dr S 270C, Athens, GA 30602 USA.

ABSTRACT
Steroid hormone gene regulation is often depicted as a linear transduction of the signal, from molecule release to the gene level, by activation of a receptor protein after being bound by its steroid ligand. Such an action would require that the hormone be present and bound to the receptor in order to have target gene response. Here, we present data that presents a novel perspective of hormone gene regulation, where the hormone molecule and its receptor have exclusive target gene regulation function, in addition to the traditional direct target genes. Our study is the first genome-wide analysis of conditional mutants simultaneously modeling the steroid and steroid receptor gene expression regulation. We have integrated classical genetic mutant experiments with functional genomics techniques in the Drosophila melanogaster model organism, where we interrogate the 20-hydroxyecdysone signaling response at the onset of metamorphosis. Our novel catalog of ecdysone target genes illustrates the separable transcriptional responses among the hormone, the pre-hormone receptor and the post-hormone receptor. We successfully detected traditional ecdysone target genes as common targets and also identified novel sets of target genes which where exclusive to each mutant condition. Around 12 % of the genome responds to the ecdysone hormone signal at the onset of metamorphosis and over half of these are independent of the receptor. In addition, a significant portion of receptor regulated genes are differentially regulated by the receptor, depending on its ligand state. Gene ontology enrichment analyses confirm known ecdysone regulated biological functions and also validate implicated pathways that have been indirectly associated with ecdysone signaling.

No MeSH data available.


Related in: MedlinePlus