Controlled transgene expression by E1-E4-defective adenovirus vectors harbouring a "tet-on" switch system

Area of Science:

• Molecular Biology
• Gene Regulation
• Viral Vector Technology

Background:

• The tetracycline-inducible (tet) switch system is widely used for gene regulation.
• While tet-off systems are common, tet-on systems using viral vectors are less documented.
• This study focuses on advancing tet-on systems within adenovirus vectors.

Purpose of the Study:

• To develop and characterize an E1-E4-defective adenovirus-mediated tet-on system.
• To evaluate the efficiency of tet-on gene induction using single and double virus strategies.
• To compare different minimal inducible promoters for optimal performance.

Main Methods:

• Production of E1-E4-defective adenoviruses encoding rtTA and/or luciferase.
• Utilizing single and double virus strategies for gene delivery.
• Assessing luciferase expression induction in cell lines, mouse muscle, and rat brain.

Main Results:

• Achieved over 400-fold induction in PC12 and NHA cells with a double virus strategy.
• Demonstrated over 600-fold induction in human astrocytes using a single virus strategy.
• Confirmed efficient on/off switching and identified promoter-dependent differences in induction efficiency in vitro and in vivo.

Conclusions:

• The CMV* promoter is susceptible to transcriptional interference in adenovirus vectors, leading to high basal expression.
• The TK* promoter shows lower background activity, making it more suitable for tight regulation.
• Optimizing rtTA expression and promoter choice is crucial for achieving effective tet-on gene induction in vitro and in vivo.