Arnold D B, Heintz N
The Rockefeller University, New York, NY 10021, USA.
Proc Natl Acad Sci U S A. 1997 Aug 5;94(16):8842-7. doi: 10.1073/pnas.94.16.8842.
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 in situ assay. This element (PCE1) is also present in the calmodulin II promoter, which regulates expression of a second Purkinje cell Ca2+ 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 microM ionomycin in the extracellular medium increased expression. These results demonstrate that PCE1 is a component of a cell-specific and Ca2+-sensitive transcriptional regulatory mechanism that may play a key role in setting the Ca2+ buffering capacity of Purkinje cells.
钙结合蛋白D28编码一种钙结合蛋白，该蛋白仅在小脑的浦肯野细胞中表达。我们利用生物弹道转染P12小脑的器官型切片，从小脑钙结合蛋白启动子中鉴定出一个40碱基对的元件，在这种瞬时原位分析中，该元件对于浦肯野细胞特异性表达是必需且充分的。该元件（PCE1）也存在于钙调蛋白II启动子中，后者调节另一种浦肯野细胞钙结合蛋白的表达。在浦肯野细胞中，高水平的外源性钙结合蛋白或钙视网膜蛋白的表达使PCE1介导的转录降低了2.5至3倍，而细胞外培养基中存在1微摩尔离子霉素则增加了表达。这些结果表明，PCE1是细胞特异性和钙敏感转录调控机制的一个组成部分，可能在设定浦肯野细胞的钙缓冲能力方面起关键作用。
