Regulatory
EGSH

Part:BBa_K415507:Experience

Designed by: Laura Deming, Joy Jiao, Adrian Slusarczyk   Group: iGEM10_MIT   (2010-10-27)

This experience page is provided so that any user may enter their experience using this part.
Please enter how you used this part and how it worked out.


Applications

The MIT iGEM 2010 team used this part to produce one of the few existing toggles in mammalian systems. A circuit diagram of this toggle is shown below, along with characterization data.

Figure 1. Circuit diagram of bistable toggle.
Figure 2. Effect of DOX on the system.


Our toggle involves a positive feedback loop between rtTA3+DOX and the promoter TREt. Addition of PonS into the system leads to the activation of EGSH, which then subsequently activates the positive feedback loop, propelling the system into a high output state (Figure 1).

Our system is bistable at a wide range of DOX levels. Figure 2 shows a rate plot (dX/dt vs. X) for rtTA3, where the time lapse dispalys the effect of increasing DOX levels on the system. The system is bistable when three intercepts occur on the ordinate, corresponding to a wide range of DOX levels. However, at high DOX levels the system becomes constitutively high/high for -PonS/+PonS.

Triple calcium phosphate transfections were performed on HEK293FT hEF1a_RxR_VgECR cell lines with constructs of our toggle: EGSH_rtTA3 and TREt_EYFP_rtTA3, as well as hEF1a_mKate serving as a fluorescent transfection efficiency control. Micrographs were obtained at 26 hours post transfection. The mKate fluorescence was converted to a binary mask. This mask was then applied to the EYFP fluorescence micrograph and pixel intensities were calculated. Figures 3 and 4 correspond to our sensitivity analysis performed in Figure 2. Qualitative data can be reviewed in figure 5.

Figure 3. Effect of -/+ PonS on the system under high DOX levels.
Figure 4. Effect of -/+ PonS on the system under low DOX levels.
Figure 5. Fluorescent micrographs showing -/+ PonS for: (left) overlay of mKate and EYFP fluorescence indicating both transfection efficiency and toggle output; (right) EYFP levels.

                                                                                                                                                                                                                                                                                                  

User Reviews

UNIQ588c225059ab8035-partinfo-00000000-QINU UNIQ588c225059ab8035-partinfo-00000001-QINU