Perl Lab
Pioneering Tet-Inducible Gene Control and Lineage Tracing in the Lung

Tetracycline-Inducible Systems for Gene Activation, Deletion, and Lineage Tracing in the Lung Epithelium

Dr. Anne-Karina Perl’s early work on embryonic lung development laid the groundwork for the use of tetracycline-inducible systems to manipulate gene expression specifically in the lung epithelium.

By characterizing the pharmacokinetics of doxycycline and the onset of gene activation during development (Perl et al., Transgenic Res., 2002), she helped refine a system that provides spatial and temporal control of gene function—avoiding the pitfalls of embryonic lethality and systemic off-target effects.

Two widely used activator lines—SPCrtTA (Sftpc-rtTA, line 1) and CCSPrtTA (Scgb1a1-rtTA, line 1)—enable researchers to activate transgenes in the distal and proximal lung epithelium of both embryonic and adult mice. These models have become essential tools in the lung biology community and are now used by hundreds of researchers worldwide.

To enable conditional gene deletion and lineage tracing, Dr. Perl generated tetO-Cre–based systems by crossing these rtTA drivers with tetO-Cre responder mice. Upon doxycycline administration, Cre recombinase is expressed in a tissue-specific manner, allowing precise deletion of floxed genes and permanent labeling of targeted cell lineages. The fidelity and localization of Cre activity were characterized using the Z/AP reporter system (Perl et al., PNAS, 2002).

This tetracycline-inducible Cre approach has become a cornerstone for lineage tracing and functional genomics in lung epithelial biology. For example, CCSPrtTA line 1 mediates recombination in the trachea, bronchi, bronchioles, and a subset of alveolar type II cells (Perl et al., Am J Respir Cell Mol Biol, 2005), while line 2 provides an alternative expression pattern (Perl et al., Am J Respir Crit Care Med, 2011).

All of these mouse lines are available through The Jackson Laboratory, facilitating broad use and reproducibility across the field.

In addition to generating these tools, Dr. Perl and Dr. Emma Rawlins co-authored the seminal review on inducible transgenic tools for the lung epithelium, fondly referred to as the “aMAZEing” review (PMID: 22180870), which provides guidance through the often complex landscape of transgenic strategies. More recently, the mesenchymal complexity of the lung was revisited and clarified in “The Elephant in the Lung” (PMID: 32442602), offering an updated view on fibroblast and mesenchymal lineage hierarchies.

Together, these contributions continue to support mechanistic discoveries in lung development, repair, and disease.

Correlation of GFP with epithelial cell markers in the peripheral lung of CCSPrtTA/ tetO-Cre / ZEG transgenic mice.

Correlation of GFP with epithelial cell markers in the peripheral lung of CCSPrtTA/ tetO-Cre / ZEG transgenic mice

Dams were treated with doxycycline from E6.5 to PN7. At PN7, frozen sections of CCSPrtTA / tetO-Cre / ZEG lungs were stained for -tubulin, CCSP, pro-SPC or CGRP (red) and visualized for dual fluorescence with GFP (green). Some ciliated (-tubulin positive) cells expressed GFP. In the bronchioles, some Clara cells (CCSP positive) expressed GFP; however, not all non-ciliated, GFP expressing cells expressed CCSP. A subset of alveolar type II cells (pro-SPC) expressed GFP. GFP was not detected in squamous type I epithelial cells. GFP expression (green) was not co-localized with CGRP.

Patterns of GFP labeling in the trachea.

Patterns of GFP labeling in the trachea

Dams were treated with doxycycline from E6.5 to PN7. Whole mount of the proximal trachea of a triple transgenic CCSPrtTA / tetO-Cre / ZEG mouse was visualized using an inverted microscope with fluorescence optics. Labeled cells were present in a dorsal ventral pattern with increased density of labeled cells overlaying the cartilage rings.