Conditional liver-specific expression of simian virus 40 T antigen leads to regulatable development of hepatic...

Area of Science:

• Genetics and Molecular Biology
• Transgenic Technology
• Mammalian Genetics

Background:

• Constitutive transgene expression or gene knockout in mice can lead to adaptive epigenetic changes and toxicity, limiting in vivo gene function studies.
• Conditional gene expression technology offers a solution for temporal and tissue-specific gene manipulation in vivo.

Purpose of the Study:

• To establish a binary transgenic mouse model for conditional, liver-specific gene expression using the tetracycline regulatory system.
• To demonstrate the ability to tightly regulate and reverse the expression of transgenes (SV40 T antigen and lacZ) in the liver.

Main Methods:

• Developed a binary transgenic system based on the tetracycline-responsive transcriptional activator (tTA).
• Utilized liver-specific promoters (mouse albumin or mouse major urinary protein) to drive tTA expression.
• Crossed tTA transgenic mice with mice carrying transgenes (TAg or lacZ) under tTA control.
• Administered tetracycline to regulate transgene expression.

Main Results:

• Achieved suppressed, undetectable liver-specific transgene expression that was reversible upon tetracycline administration and withdrawal.
• Demonstrated that continuous tetracycline administration prevented hepatocellular adenomas and hyperplasia in mice expressing tTA and TAg transgenes.

Conclusions:

• The developed binary transgenic model enables precise, liver-specific, and reversible control of gene expression in vivo.
• This model is valuable for studying the physiological functions of genes in a liver-specific context, overcoming limitations of constitutive expression systems.