Lineage Tracing Mediated by Cre-Recombinase Activity

Abstract

INTRODUCTION Clinical research aims to unravel mechanisms leading to disease. Looking at a disease state, frequently asked questions are when and how did cells change their native behavior and how do these cells circumvent regulation by the healthy environment? Answers to these questions can often be identified through the use of a powerful technique called lineage tracing. A cell lineage describes a single stem or progenitor cell that gives rise to progeny that can adopt differential cell fates. This cellular fate is represented through differential cell properties or migration to specific regions within an organ or the organism. Lineage tracing allows us to study these dynamic processes through visualization of the cell lineage within an organism. Lineage tracing originated in the field of developmental biology. In the early twentieth century, Walter Vogt and his colleagues developed a novel method by injection of “vital dyes” into single cells of an amphibian embryo to trace the cells’ fate during gastrulation using light microscopy (Vogt, 1929). This technique was restricted by dilution of the dye following each cell division, and ultimately it was lost from the cell lineage. Although various ways to trace cells were described in past decades, advances in mouse transgenesis led to genetic lineage tracing techniques, which are now the preferred approaches. We will discuss how the Cre–loxP system can circumvent the problem of label dilution through induction of reporter gene expression in specific cell populations and how these reporter genes can be used to visualize cell lineages and analyze their behavior in vivo.