Generation and characterization of a tamoxifen-inducible Vsx1-CreER line to target V2 interneurons in the mouse developing spinal cord.

In the spinal cord, ventral interneurons regulate the activity of motor neurons, thereby controlling motor activities including locomotion. Interneurons arise during embryonic development from distinct progenitor domains orderly distributed along the dorso-ventral axis of the neural tube. The p2 progenitor domain generates at least five V2 interneuron populations. However, identification and characterization of all V2 populations remain currently incomplete and the mechanisms that control their development remain only partly understood. In this study, we report the generation of a Vsx1-CreER BAC transgenic mouse line that drives CreER recombinase expression mimicking endogenous Vsx1 expression pattern in the developing spinal cord. We showed that the Vsx1-CreER transgene can mediate recombination in V2 precursors with a high efficacy and specificity. Lineage tracing demonstrated that all the V2 interneurons in the mouse developing spinal cord derive from cells expressing Vsx1. Finally, we confirmed that V2 precursors generate additional V2 populations that are not characterized yet. Thus, the Vsx1-CreER line described here is a useful genetic tool for lineage tracing and for functional studies of the mouse spinal V2 interneurons.