Characterization of the Frizzled10-CreER transgenic mouse: an inducible Cre line for the study of Cajal-Retzius cell development.

Cajal-Retzius cells are an enigmatic class of neurons located in the most superficial layer of the cerebral cortex, and they play an important role in cortical development. Although many studies have indicated that CR cells are involved in regulating cell migration and cortical maturation, the function of these cells is still not fully understood. Here we describe an inducible Cre mouse line in which CreER is driven by the promoter for the Wnt receptor Frizzled10. Consistent with our previous studies on Frizzled10 expression and transgenic mouse lines using the Frizzled10 promoter, we found that in the developing telencephalon, Cre was mainly detected at the cortical hem, the largest source of CR cells. By crossing the Cre line to R26R reporter mice and injecting tamoxifen at different time points, we were able to detect via X-gal staining CR cells produced from the cortical hem at distinct stages during development. Thus, this transgenic Cre mouse line is a valuable tool for studying the molecular and cellular mechanisms of CR cell development.