Presence of calbindin D28K and GAD67 mRNAs in both orthotopic and ectopic Purkinje cells of staggerer mice suggests that staggerer acts after the onset of cytodifferentiation.

We used in situ hybridization to study the expression of GAD67 and calbindin D28K mRNAs in developing mouse cerebellar Purkinje cells. Both genes are expressed prenatally; calbindin D28K mRNAs can be detected in Purkinje cells of embryonic day (E) 15 mice, whereas GAD67 mRNAs first appear slightly later, in E16 mice. The stunted Purkinje cells of staggerer (sg/sg) mutant mice maintain calbindin D28K and GAD67 expression. Our data suggest that the sg/sg mutation does not interfere with the transcriptional activation of these two genes, and might therefore act after the induction of specific gene expression in developing Purkinje cells.