Targeting mammary epithelial cells using a bacterial artificial chromosome

Area of Science:

• * Molecular Biology
• * Genetics
• * Developmental Biology

Background:

• * Mammary gland development and function are complex processes requiring precise genetic regulation.
• * Tools for targeted genetic manipulation in specific cell types are crucial for studying these processes.
• * Existing methods may lack specificity or efficiency in mammary epithelial cells.

Purpose of the Study:

• * To generate transgenic mouse lines for efficient Cre recombinase expression in mammary epithelial cells.
• * To utilize the whey acidic protein (WAP) gene promoter for cell-specific expression.
• * To establish a reliable system for studying mammary gland biology through targeted recombination.

Main Methods:

• * Construction of a bacterial artificial chromosome (PAC) containing the WAP gene and an improved Cre recombinase (iCre) coding sequence.
• * Modification of the PAC using homologous recombination in E. coli.
• * Generation and characterization of transgenic mouse lines (WAPiCre).

Main Results:

• * Three out of four generated transgenic lines exhibited high-efficiency Cre recombinase expression.
• * Expression was targeted to the majority of mammary epithelial cells during lactation.
• * Efficient recombination of LoxP-flanked DNA sequences was observed in nearly all epithelial cells by lactation day 3.

Conclusions:

• * The WAPiCre transgenic mouse lines provide a powerful tool for studying mammary gland biology.
• * These mice allow for efficient, lactation-specific, and cell-type-specific genetic manipulation.
• * This system facilitates research into gene function and developmental processes within the mammary epithelium.