Difference between revisions of "Part:BBa K1440000"

Latest revision as of 06:36, 27 October 2014

Part2_pTRE promoter with cFP and ribozyme

this part is one of the regulatory parts in our whole design, it consists of pTRE promoter and cFP and ribozyme.The system can work in mammalian cells.

This part originates from BBa_K812032. This part is used to test the cre-TM system and pTRE system. It consists of loxp sites and pTRE promoter. both pTRE and cre-TM parts have not been used before in iGEM competition. So we introduce these two parts in this new part. In this part, although we use mCFP as the reporter gene, we find that the efficiency of mCFP reporter gene can not even work. So we replace the mCFP reporter gene with the EGFP to test the cre-TM system. And because it is a really big part, we also replace the mCFP with OSKM (four transcription factors) binding with T2A linkers to prove that using the pTRE promoter we found ourselves, we can successfully make fibroblast reprogram to iPSc.

We will only show the result with EGFP and OSKM. Firstly, we show the data about Cre-TM system, we cotransfect the Cre_ERT2 (BBa_K1440001) plasmid and this part (mCFP replaced with EGFP).We choose HEK293 cells to do transfection. We plant the cells in a 24-wells dish. Before transfection, we make sure the density of the cell is about 50-70%. We use lipofectamine 2000 as the transfection reagent. After 24hr, we dose each dish with certain concentration of tamoxifen. And at 36hr, we get the result.

We analyze the data by cell counting with the help of blood cell counting chamber. We use "GFP-positive cells numbers/total cell numbers" to indicate the transfection efficiency（= 0.327） in "Control-GFP" cell plate. We use the same method to count the tamoxifen (0umol/ml, 1umol/ml, 2umol/ml, 5umol/ml, 10umol/ml ) induced GFP expression.(See figure below)

Then we construct the concept "REU"(Relative expression unit) that ((Cell density of GFP-positive cells by tamoxifen inducing/ total cells)/(Cell density of GFP-positive cells of control-GFP/ total control-GFP cells) to indicate the efficiency of tamoxifen system. The data show that Conc. tamoxifen 5umol/ml is the best condition for this system to work, and the inducing efficiency is more than 60%. Besides, the leakage of this system is only 0.9%, which indicates that it is a quite controllable system.

Sequence and Features