Jump-or-die-System
The Jump-or-Die-system facilitates the integration of a gene of interest into cellular genome and selects the cells successfully integrated with the gene of interest by apoptosis. Therefore three constructs are needed.
Construct 1
Construct 1 contains a tet-on promoter, bacterial attachment site (attB), human bak (bak) and SV40 polyadenylation site (SV40PA). It has to be integrated to the genome of the cellline. The selection of the cells stably transfected with this construct is realized by co-transfection with hygromycine resistance.
Construct 2
Construct 2 consists of the following parts: phage attachment site (attP), eGFP (our gene of interest), doubled stop codon and SV40PA.
Construct 3
This Biobrick contains CMV-promoter, PhiC31o (mouse-codon optimized integrase) and SV40PA. It will be transfected to the cellline and read-off so that PhiC31o can catalyze the integration of Construct 2 into the attB site in genome.
Transfection possibilities
A cellline which has construct 1 integrated into the genome will be co-transfected with construct 2 and 3. Construct 3 will be read-off instantly, in contrast to construct 1 which has to be induced by doxycycline and because of the lack of a promoter, construct 2 will at the beginning not be translated.
The outgoing of this co-transfection has the following possibilities:
a) neither constructs enter the cell
b) only construct 2 enters the cell
c) only construct 3 enters the cell
d) both construct 2 and 3 enter the cell
a) neither constructs enter the cell
If neither constructs are taken in by the cell, at the induction of the tet-on promoter, bak will be translated, the protein inserted to mitochandrial membrane and the cell will undergo apoptosis.
b) only construct 2 enters the cell
Induction of tet-on promoter will cause translation of bak and so induce apoptosis. The gene of interest will not be read off, because there is no promoter in construct 2.
c) only construct 3 enters the cell
PhiC31o will be translated because of the CMV promoter. But after tet-on induction bak will also be read-off and therefore cause cell death.
d) both constructs 2 and 3 enter the cell
PhiC31o will be read off because of CMV promoter. Now the integrase will combine attB and attP site and integrate construct 2 into the genome by a specific rate. All cells where PhiC31o doesn't integrate contruct 2 will also die due to Bak after doxycycline induction Now the gene of interest is integrated between the tet-on promoter and bak in the cellular genome. This complex will be translated after doxycycline induction. The doubled stop codon and polyadenylation site directly after eGFP (the gene of interest) will efficiently prevent the translation of bak. Thus such cells will express the gene of interest and survive.
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