Journal Article

Conditional control of gene expression in the mouse

Lewandoski, Mark

2001

Overview

Key Points Temporal and spatial control of gene expression in the mouse can be achieved using binary transgenic systems, in which gene expression is controlled by the interaction of an effector protein product on a target transgene. These interactions are controlled by crossing mouse lines, or by adding or removing an exogenous inducer. Binary transgenic systems fall into two categories. One is based on transcriptional transactivation and is well suited for activating transgenes in gain-of-function experiments. The other is based on site-specific DNA recombination and can be used to activate transgenes or to generate tissue-specific gene knockouts and cell-lineage markers. The most commonly used transcriptional systems are based on the tetracycline resistance operon of Escherichia coli . The effectors of these systems fall into two categories defined by whether transcription activation occurs upon the administration or depletion of a tetracycline compound (usually doxycycline). The Gal4-based system is a transactivation system that does not require an inducer, but Gal4 transcriptional activation can be controlled by synthetic steroids when a mutated ligand-binding domain is incorporated into a Gal4 chimeric transactivator. The most widely used site-specific DNA recombination system uses the Cre recombinase from bacteriophage P1. The Flp recombinase from Saccharomyces cerevisiae has also been adapted for use in mice. By using gene-targeting techniques to produce mice with modified endogenous genes that can be acted on by Cre or Flp recombinases expressed under the control of tissue-specific promoters, site-specific recombination can be used to inactivate endogenous genes in a spatially controlled manner. Cre/Flp activity can also be controlled temporally by delivering cre / FLP -encoding transgenes in viral vectors, by administering exogenous steroids to mice that carry a chimeric transgene consisting of the cre gene fused to a mutated ligand-binding domain, or by using transcriptional transactivation to control cre / FLP expression. The irreversibility of site-specific recombination makes this technique uniquely suited for a new type of analysis in which the transient tissue-specific expression of cre / FLP is used to permanently activate a reporter target gene for cell-lineage studies. One of the most powerful tools that the molecular biology revolution has given us is the ability to turn genes on and off at our discretion. In the mouse, this has been accomplished by using binary systems in which gene expression is dependent on the interaction of two components, resulting in either transcriptional transactivation or DNA recombination. During recent years, these systems have been used to analyse complex and multi-staged biological processes, such as embryogenesis and cancer, with unprecedented precision. Here, I review these systems and discuss certain studies that exemplify the advantages and limitations of each system.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: Agriculture / Animal Genetics and Genomics / Animals / Biology / Biomedical and Life Sciences / Biomedicine / Cancer / Cancer Research / Cell Lineage / DNA Nucleotidyltransferases - physiology / DNA-Binding Proteins / Embryonic and Fetal Development - genetics / Escherichia coli / Flp recombinase / Forecasting / Fungal Proteins - genetics / Gal4 protein / Gene expression / Gene Expression Regulation - genetics / Gene Expression Regulation - physiology / Gene Expression Regulation, Developmental / Gene Function / Genetic Techniques / Genotype & phenotype / Human Genetics / Integrases - physiology / Mice - genetics / Mice, Knockout / Mice, Transgenic / Organ Specificity / Phage P1 / Promoter Regions, Genetic / Recombination, Genetic / Repressor Proteins - genetics / review-article / Saccharomyces cerevisiae - genetics / Saccharomyces cerevisiae Proteins / Tetracycline - pharmacology / Transcription Factors - genetics / Transcriptional Activation / Transgenes / Transgenic animals / Viral Proteins - physiology