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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

Pass-through transcription is responsible for suppression of the eye enhancer. (A) (UAS)EyeRYW transgenic lines; the eye enhancer is inserted in the opposite orientation. (B) (UASR)EyeYW transgenic lines; the UAS promoter drives transcription in the direction from the enhancers. (C) (UAS)Ey(e)∆YtsW transgenic lines with deletion of the yellow gene promoter (indicated by the absence of an upstream arrow and by parentheses in front of the gene on the scheme); “ts” is the core 222-bp SV40 terminator. (D) Quantification of (UAS)Ey(e)∆YtsW transcripts by RT-qPCR. Positions of primer pairs (1-2, 3-4, 5-6, 9-10) are indicated. RT-qPCR was conducted on mRNAs isolated from transgenic lines at the mid-late pupae stage. Error bars indicate standard deviations. For other designations, see Figure 1.
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Figure 2: Pass-through transcription is responsible for suppression of the eye enhancer. (A) (UAS)EyeRYW transgenic lines; the eye enhancer is inserted in the opposite orientation. (B) (UASR)EyeYW transgenic lines; the UAS promoter drives transcription in the direction from the enhancers. (C) (UAS)Ey(e)∆YtsW transgenic lines with deletion of the yellow gene promoter (indicated by the absence of an upstream arrow and by parentheses in front of the gene on the scheme); “ts” is the core 222-bp SV40 terminator. (D) Quantification of (UAS)Ey(e)∆YtsW transcripts by RT-qPCR. Positions of primer pairs (1-2, 3-4, 5-6, 9-10) are indicated. RT-qPCR was conducted on mRNAs isolated from transgenic lines at the mid-late pupae stage. Error bars indicate standard deviations. For other designations, see Figure 1.

Mentions: Next, we tested the importance of eye enhancer orientation in the construct for its sensitivity to transcription from the UAS promoter ((UAS)EyeRYW) (Figure 2A). Eye pigmentation in transgenic flies increased after deletion of this promoter ((∆)EyeRYW); at the same time, induction of transcription resulted in complete inactivation of the eye enhancer. Thus, the enhancer orientation proved to be not important for the observed suppressive effect of transcription.


Transcription through enhancers suppresses their activity in Drosophila.

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

Pass-through transcription is responsible for suppression of the eye enhancer. (A) (UAS)EyeRYW transgenic lines; the eye enhancer is inserted in the opposite orientation. (B) (UASR)EyeYW transgenic lines; the UAS promoter drives transcription in the direction from the enhancers. (C) (UAS)Ey(e)∆YtsW transgenic lines with deletion of the yellow gene promoter (indicated by the absence of an upstream arrow and by parentheses in front of the gene on the scheme); “ts” is the core 222-bp SV40 terminator. (D) Quantification of (UAS)Ey(e)∆YtsW transcripts by RT-qPCR. Positions of primer pairs (1-2, 3-4, 5-6, 9-10) are indicated. RT-qPCR was conducted on mRNAs isolated from transgenic lines at the mid-late pupae stage. Error bars indicate standard deviations. For other designations, see Figure 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Pass-through transcription is responsible for suppression of the eye enhancer. (A) (UAS)EyeRYW transgenic lines; the eye enhancer is inserted in the opposite orientation. (B) (UASR)EyeYW transgenic lines; the UAS promoter drives transcription in the direction from the enhancers. (C) (UAS)Ey(e)∆YtsW transgenic lines with deletion of the yellow gene promoter (indicated by the absence of an upstream arrow and by parentheses in front of the gene on the scheme); “ts” is the core 222-bp SV40 terminator. (D) Quantification of (UAS)Ey(e)∆YtsW transcripts by RT-qPCR. Positions of primer pairs (1-2, 3-4, 5-6, 9-10) are indicated. RT-qPCR was conducted on mRNAs isolated from transgenic lines at the mid-late pupae stage. Error bars indicate standard deviations. For other designations, see Figure 1.
Mentions: Next, we tested the importance of eye enhancer orientation in the construct for its sensitivity to transcription from the UAS promoter ((UAS)EyeRYW) (Figure 2A). Eye pigmentation in transgenic flies increased after deletion of this promoter ((∆)EyeRYW); at the same time, induction of transcription resulted in complete inactivation of the eye enhancer. Thus, the enhancer orientation proved to be not important for the observed suppressive effect of transcription.

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