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Transcription through enhancers suppresses their activity in Drosophila.

Erokhin M, Davydova A, Parshikov A, Studitsky VM, Georgiev P, Chetverina D - Epigenetics Chromatin (2013)

Bottom Line: A number of experiments suggest that transcription can have both positive and negative effects on regulatory elements.In this study, we performed direct tests for the effect of transcription on enhancer activity.Our findings suggest a role for pass-through transcription in negative regulation of enhancer activity.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Enhancer elements determine the level of target gene transcription in a tissue-specific manner, providing for individual patterns of gene expression in different cells. Knowledge of the mechanisms controlling enhancer action is crucial for understanding global regulation of transcription. In particular, enhancers are often localized within transcribed regions of the genome. A number of experiments suggest that transcription can have both positive and negative effects on regulatory elements. In this study, we performed direct tests for the effect of transcription on enhancer activity.

Results: Using a transgenic reporter system, we investigated the relationship between the presence of pass-through transcription and the activity of Drosophila enhancers controlling the expression of the white and yellow genes. The results show that transcription from different promoters affects the activity of enhancers, counteracting their ability to activate the target genes. As expected, the presence of a transcriptional terminator between the inhibiting promoter and the affected enhancer strongly reduces the suppression. Moreover, transcription leads to dislodging of the Zeste protein that is responsible for the enhancer-dependent regulation of the white gene, suggesting a 'transcription interference' mechanism for this regulation.

Conclusions: Our findings suggest a role for pass-through transcription in negative regulation of enhancer activity.

No MeSH data available.


Related in: MedlinePlus

Transcription initiated on the Ef1 promoter suppresses the enhancer activity, while the SV40 transcriptional terminator protects the enhancers from the repressive effect of transcription. (A) (EF1)Ey(e)YW, the Ef1 promoter drives transcription through eye enhancer. (B) (EF1)(Ey)∆W∆Y, the Ef1 promoter drives transcription through yellow enhancers. (C) UAS(Ts)Ey(e)∆YtsW, the 702-bp SV40 terminator (Ts) is inserted between the UAS promoter and the eye enhancer. (D) (UAS)Ts(Ey)∆W∆Y, the 702-bp SV40 terminator is inserted between the UAS promoter and yellow enhancers. For other designations, see Figures 1 and2.
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Figure 4: Transcription initiated on the Ef1 promoter suppresses the enhancer activity, while the SV40 transcriptional terminator protects the enhancers from the repressive effect of transcription. (A) (EF1)Ey(e)YW, the Ef1 promoter drives transcription through eye enhancer. (B) (EF1)(Ey)∆W∆Y, the Ef1 promoter drives transcription through yellow enhancers. (C) UAS(Ts)Ey(e)∆YtsW, the 702-bp SV40 terminator (Ts) is inserted between the UAS promoter and the eye enhancer. (D) (UAS)Ts(Ey)∆W∆Y, the 702-bp SV40 terminator is inserted between the UAS promoter and yellow enhancers. For other designations, see Figures 1 and2.

Mentions: The (EF1)Ey(e)YW construct was made for the eye enhancer (Figure 4A). In these transgenic lines, all flies had the weak eye pigmentation indicative of strong suppression of the enhancer. Deletion of enhancer ((EF1)Ey(∆)YW) did not change pigmentation, indicating that the enhancer is completely inactivated in the presence of Ef1 promoter, while deletion of the promoter ((∆)Ey(e)YW) resulted in darker pigmentation, restoring the ability of the enhancer to stimulate transcription. Thus, the Ef1 promoter was also found to effectively inhibit the activity of eye enhancer.


Transcription through enhancers suppresses their activity in Drosophila.

Erokhin M, Davydova A, Parshikov A, Studitsky VM, Georgiev P, Chetverina D - Epigenetics Chromatin (2013)

Transcription initiated on the Ef1 promoter suppresses the enhancer activity, while the SV40 transcriptional terminator protects the enhancers from the repressive effect of transcription. (A) (EF1)Ey(e)YW, the Ef1 promoter drives transcription through eye enhancer. (B) (EF1)(Ey)∆W∆Y, the Ef1 promoter drives transcription through yellow enhancers. (C) UAS(Ts)Ey(e)∆YtsW, the 702-bp SV40 terminator (Ts) is inserted between the UAS promoter and the eye enhancer. (D) (UAS)Ts(Ey)∆W∆Y, the 702-bp SV40 terminator is inserted between the UAS promoter and yellow enhancers. For other designations, see Figures 1 and2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852481&req=5

Figure 4: Transcription initiated on the Ef1 promoter suppresses the enhancer activity, while the SV40 transcriptional terminator protects the enhancers from the repressive effect of transcription. (A) (EF1)Ey(e)YW, the Ef1 promoter drives transcription through eye enhancer. (B) (EF1)(Ey)∆W∆Y, the Ef1 promoter drives transcription through yellow enhancers. (C) UAS(Ts)Ey(e)∆YtsW, the 702-bp SV40 terminator (Ts) is inserted between the UAS promoter and the eye enhancer. (D) (UAS)Ts(Ey)∆W∆Y, the 702-bp SV40 terminator is inserted between the UAS promoter and yellow enhancers. For other designations, see Figures 1 and2.
Mentions: The (EF1)Ey(e)YW construct was made for the eye enhancer (Figure 4A). In these transgenic lines, all flies had the weak eye pigmentation indicative of strong suppression of the enhancer. Deletion of enhancer ((EF1)Ey(∆)YW) did not change pigmentation, indicating that the enhancer is completely inactivated in the presence of Ef1 promoter, while deletion of the promoter ((∆)Ey(e)YW) resulted in darker pigmentation, restoring the ability of the enhancer to stimulate transcription. Thus, the Ef1 promoter was also found to effectively inhibit the activity of eye enhancer.

Bottom Line: A number of experiments suggest that transcription can have both positive and negative effects on regulatory elements.In this study, we performed direct tests for the effect of transcription on enhancer activity.Our findings suggest a role for pass-through transcription in negative regulation of enhancer activity.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Enhancer elements determine the level of target gene transcription in a tissue-specific manner, providing for individual patterns of gene expression in different cells. Knowledge of the mechanisms controlling enhancer action is crucial for understanding global regulation of transcription. In particular, enhancers are often localized within transcribed regions of the genome. A number of experiments suggest that transcription can have both positive and negative effects on regulatory elements. In this study, we performed direct tests for the effect of transcription on enhancer activity.

Results: Using a transgenic reporter system, we investigated the relationship between the presence of pass-through transcription and the activity of Drosophila enhancers controlling the expression of the white and yellow genes. The results show that transcription from different promoters affects the activity of enhancers, counteracting their ability to activate the target genes. As expected, the presence of a transcriptional terminator between the inhibiting promoter and the affected enhancer strongly reduces the suppression. Moreover, transcription leads to dislodging of the Zeste protein that is responsible for the enhancer-dependent regulation of the white gene, suggesting a 'transcription interference' mechanism for this regulation.

Conclusions: Our findings suggest a role for pass-through transcription in negative regulation of enhancer activity.

No MeSH data available.


Related in: MedlinePlus