Regulation of a blood-brain barrier-specific enzyme expressed by cerebral pericytes (pericytic aminopeptidase N pAPN) under cell culture conditions
Regulation of a blood-brain barrier-specific enzyme expressed by cerebral pericytes (pericytic aminopeptidase N pAPN) under cell culture conditions
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DOI：
10.1097/00004647-199811000-00014
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发表时间：
1998-11-01
影响因子：
6.3
通讯作者：
Dermietzel, R
中科院分区：
文献类型：
--
作者：
Ramsauer, M;Kunz, J;Dermietzel, R
在这项研究中，我们表明，与血脑屏障（BBB）相关的脑周细胞（pAPN）的氨肽酶N在周细胞培养下调。这一观察结果与先前描述的对内皮或细胞周来源的BBB特异性酶（如γ-谷氨酰转肽酶或碱性磷酸酶）的体外效应相当的数据一致。通过聚合酶链反应和原位杂交，我们能够确定pAPN的下调发生在转录后水平。发现即使当蛋白质不再可检测时，pAPN的mRNA仍组成型表达。在内皮细胞条件培养基中培养周细胞允许pAPN重新表达。然而，再表达效果在很大程度上取决于周细胞的培养条件。虽然纯化的周细胞剥夺内皮细胞没有显示再表达的效果，周细胞保持与内皮细胞接触能够获得pAPN阳性表型，表明内皮细胞构成的pAPN在体外再表达的基本要求。然而，星形胶质细胞不足以发挥任何再表达作用。
In this study we show that the aminopeptidase N of cerebral pericytes (pAPN) associated with the blood-brain barrier (BBB) is downregulated in pericytic cell cultures. This observation is in accordance with previous data describing comparable in vitro, effects for BBB-specific enzymes of endothelial or pericytic origin, such as gamma-glutamyl transpeptidase or alkaline phosphatase. By polymerase chain reaction and in situ hybridization we were able to determine that the downregulation of pAPN occurs at the posttranscriptional level. The mRNA of pAPN was found to be constitutively expressed even when the protein is no longer detectable. Culturing the pericytes in an endothelial cell-conditioned medium allowed pAPN to be reexpressed. However, the reexpression effect depended largely on the culturing conditions of the pericytes. Although purified pericytes deprived of endothelial cells did not reveal a reexpression effect, pericytes that were kept in contact with endothelial cells were able to acquire a pAPN-positive phenotype, indicating that endothelial cells constitute an essential requirement for the in vitro reexpression of pAPN. Astrocytes, however, were insufficient in exerting any reexpression effect.