Description:
<jats:p>
Calbindin D28 encodes a calcium binding protein that is expressed in the cerebellum exclusively in Purkinje cells. We have used biolistic transfection of organotypic slices of P12 cerebellum to identify a 40-bp element from the calbindin promoter that is necessary and sufficient for Purkinje cell specific expression in this transient
<jats:italic>in situ</jats:italic>
assay. This element (PCE1) is also present in the calmodulin II promoter, which regulates expression of a second Purkinje cell Ca
<jats:sup>2+</jats:sup>
binding protein. Expression of high levels of exogenous calbindin or calretinin decreased transcription mediated by PCE1 in Purkinje cells 2.5- to 3-fold, whereas the presence of 1 μM ionomycin in the extracellular medium increased expression. These results demonstrate that PCE1 is a component of a cell-specific and Ca
<jats:sup>2+</jats:sup>
-sensitive transcriptional regulatory mechanism that may play a key role in setting the Ca
<jats:sup>2+</jats:sup>
buffering capacity of Purkinje cells.
</jats:p>