Joanna L. Jankowsky

Summary A wide variety of CreER T2 driver lines are available for genetic manipulation of adult‐born neurons in the mouse brain. These tools have been instrumental in studying fate potential, migration, circuit integration, and morphology of the stem cells supporting lifelong neurogenesis. Despite a wealth of tools, genetic manipulation of adult‐born neurons for circuit and behavioral studies has been limited by poor specificity of many driver lines targeting early progenitor cells and by the inaccessibility of lines selective for later stages of neuronal maturation. We sought to address these limitations by creating a new CreER T2 driver line targeted to the endogenous mouse doublecortin locus as a marker of fate‐specified neuroblasts and immature neurons. Our new model places a T2A‐CreER T2 cassette immediately downstream of the Dcx coding sequence on the X chromosome, allowing expression of both Dcx and CreER T2 proteins in the endogenous spatiotemporal pattern for this gene. We demonstrate that the new mouse line drives expression of a Cre‐dependent reporter throughout the brain in neonatal mice and in known neurogenic niches of adult animals. The line has been deposited with the Jackson Laboratory and should provide an accessible tool for studies targeting fate‐restricted neuronal precursors.