Gene Regulation Systems for Gene Therapy Applications in the Central Nervous System

Figure 2

Different configurations the tetracycline system has been incorporated into viral vectors for use in the brain. (1) Two right-facing cistrons direct transactivator and transgene expression in a single vector [4–7]. (2) One bidirectional promoter driving expression of the transgene and transactivators in a single construct [5, 6, 8–10]. (3) Two vectors are used: one bidirectional construct directing expression of two transgenes and one driving expression of transactivators [11, 12]. ITR: inverted terminal repeats; PolyA: polyadenylation signal; TetO: tetracycline operator sequence; CMV: cytomegalovirus; tTA: tetracycline transactivator; rtTA: reverse tetracycline transactivator.