Part:BBa_K3064012
9XGlucose Sensing Promoter
This composite part is a kind of improved promoter which is sensitive to particular high blood glucose concentration.
Usage and Biology
Because there is high blood glucose concentration in diabetics, in order to get improved gene which is sensitive to diabetics it’s convenient to employ promoter which reacts to high blood glucose. Transcription factor -- ChREBP -- can be effectively expressed with high blood glucose. Meanwhile, heterodimer which consists of ChREBP and Mlx can combine with gene promoter ChoRE to induce gene transcription¹.Therefore, we choose ChoRE as promoter of engineered plasmid and connect it with minP to indicates a transcription start site. In addition, we increase the number of ChoRE to realize that engineered gene will be activated by particular high blood glucose concentration instead of normal blood glucose concentration.
The picture below shows this part's structure.
In this composite part, we used one minP and nine ChoRE and apply luciferase gene as downstream reporter in plasmid PGL3-9XGSP to verify its ability.
Characterization
Materials
PGL3-9XGSP
PGL3-minP
Hepg2 cell line
Dual Luciferase Reporter Gene Assay Kit from from Beyotime company
Method
We separately transfected plasmids PGL3-9XGSP and PGL3-minP into hepg2 cells. After culturing these cells with glucose-free culture, we created low glucose concentration environment for cells and then stimulated cells with 20 mM glucose concentration culture. After 48 hours, these cells were gathered and dissoved for luciferase expression test with Dual Luciferase Reporter Gene Assay Kit of Beyotime company.
Figure 1. Transfection and Test of 9xGSP
Result
When we use luciferase as reporting system.In the histogram below, the left is the result of PGL3-minP and the right is of PGL3-9XGSP. Taking renilla as the internal reference and comparing with the control experiment, we can find that the luciferase expression of PGL3-9XGSP is much higher than the expression of PGL3-minP. This result strong proves that CHoRE can significantly improve minP promoter’s promoting intensity.
Figure 3. The design and results of 9xGSP validation using luciferase.
When we use GFP as reporting system.After 18 hours’ transfection, we conduct experiments to test the function of our part. Photograph of fluorescence microscopy helps make results clear and obvious. Meanwhile, with the set of internal control, we can gain relative fluorescence intensity by Image J. During this process, we set different groups with different glucose concentration, which helps us to detect the relationship between GFP/mcherry and glucose concentration. Besides, test at different times makes the tendency of expression level as time passes much more clearer.
From the figure we can easily discover that the glucose-sensing promoter can sense the glucose concentration and thus modify the expression level according to it. The figure below shows the results.
Figure 4. GFP/mcherry after 6 hours’ transfection(A). GFP/mcherry after 18 hours’ transfection(B). GFP/mcherry after 30 hours’ transfection(C). GFP/mcherry after 42 hours’ transfection(D). GFP/mcherry after 54 hours’ transfection(E).
References
[1] Li Ma,PengFei Gao,JianZhong Shi,et al.Research progress of ChREBP[J].Animal Husbandry and Feed Science,2014,35(09):40-42(Chinese)
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
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