TetR (tetraccycline Regulator) Expression Lentivirus

TetR (tetraccycline regulator) protein is the key regulatory protein in the Tetraccycline-controlled inducible gene expression system.  When TetR protein is present it binds to the promoter, blocking expression. Induction of expression is accomplished by addition of Tetraccycline (or doxyccycline) which removes TetR from the promoter. 

One type of GenTarget’s expression lentivectors contain a strong constitutive promoter (CMV or H1) integrated with two copies of the TetR binding sequences. This modification does not change the promoter’s constitutive expression; therefore, a gene of interest (GOI) can be expressed either by tetraccycline-dependent induction, or at a high level without induction, so called Optional inducible expresssion. Please see Inducible lentiviral system page for more information. 

The presence of TetR can be achieved by the following methods: 

1. 1. Transduction of TetR expression lentiviral particles
   2. TetR stable cell lines that constitutively express the TetR protein
   3. Transfection of a TetR expression plasmid

GenTarget’s  premade TetR lentivirus is the best method to deliver the TetR protein.  

GenTarget provides TetR expression lentivirus with a variety of anti-biotic markers. TetR is expressed under either a super strong CMV promoter (producing the highest TetR protein level) or an enhanced EF1α promoter (a tissue nonspecific strong promoter with no silencing effects during long-term culture). See the TetR expression vector map scheme below.

 GenTarget TetR Lentiviral Particles can be used as follows: 

1. 1. They can be transduced alone into any host cell of interest to generate a TetR expressing stable cell line. The generated stable cell line can then be transduced with any inducible target expression particle; the double-transduced cells will demonstrate a tetraccycline dose-dependent inducible expression of the target..
   2. They can be co-transduced with into any host cell along with any inducible target expressing lentiviral particles. The resulting double-transduced cells (selected via two antibiotic markers) will demonstrate a tetraccycline dose-dependent inducible expression of the target  

Q: What is the difference between GenTarget’s inducible system and other regulated expression systems? 

A: The GenTarget system is an optional inducible system. 

GenTarget’s inducible lentivectors (shRNA vectors and expression vectors) have TetR binding sequences inserted into their constitutive promoter (H1 or CMV). This modification does not change the promoter’s constitutive expression property. The system becomes inducible only when the TetR protein is present to block expression. Addition of tetraccycline removes TetR from the promoter, inducing expression.  

By comparison, other tetraccycline-inducible expression systems use a silent promoter that has been modified to bind to a transcriptional activator.  Expression is turned on only when the transcriptional activator binds to the promoter, and  this binding is dependent upon the presence (Tet-on system) or absence (Tet-off system) of tetraccycline or Dox.  The Tet-On and Tet-Off systems require a transcriptional activator (tTA or rtTA) along with tetraccycline or Dox for inducible expression, but the Tet-on and Tet-off vector cannot be used alone for constitutive expression. 

Please see each Product’s Manual below: