Transgenic expression of Cre recombinase in mitral/tufted cells of the olfactory bulb

Olfactory information is conveyed from the periphery to the olfactory cortices through mitral and tufted (M/T) cells in the olfactory bulb. A mouse with a specific expression of Cre recombinase in M/T cells is essential for genetic marking of M/T cells and manipulating their properties. Protocadherin 21 (Pcdh21) expression is highly restricted to M/T cells. Here we report a transgenic mouse line, Pcdh21-Cre, in which ∼10-kb mouse Pcdh21 promoter drives the expression of Cre recombinase. In Pcdh21-Cre mice, Cre recombinase activity is predominantly detected in M/T cells, visualized with the anti-CFP immunostaining in offspring of a cross between Pcdh21-Cre and the reporter Rosa26-loxP-stop-loxP-CFP strain. These results demonstrate that the ∼10-kb Pcdh21 promoter can drive transcription in M/T cells and Pcdh21-Cre mice can be used to excise floxed DNA fragments in M/T cells, which provides a valuable tool to reveal the structure and function of the central olfactory circuits.