The blood–brain barrier (BBB) is essential for cerebral homeostasis and controls the selective passage of molecules traveling in and out of the brain. Despite the crucial role of the BBB in a variety of brain diseases and its relevance for the development of drugs, there is little known about its molecular architecture. In particular, the composition of the basal lamina between the astrocytic end-feet and the endothelial cells is only partly known. Here, we present a proteomic analysis of the basal lamina of the human BBB. We combined laser capture microdissection with shotgun proteomics for selective enrichment and identification of specific proteins present in the cerebral microvasculature and arachnoidal vessels collected from normal human brain tissue specimens. Proteins found to be associated with the blood–brain barrier were validated by immunohistochemistry. Expression of membrane protein MLC1 was found in all brain barriers. Phosphoglucomutase-like protein 5 appeared to be variably present along the outer part of intracerebral vessels, and multidrug resistance protein 1 was identified in both intracerebral, as well as arachnoidal blood vessels. The results demonstrate the presence of so far unidentified proteins in the human BBB and illustrate topic differences in their expression. In conclusion, we showed that sample purification by microdissection followed by shotgun proteomics provides a list of proteins identified in the BBB. Subsequent immunohistochemistry detailed the respective expression sites of membrane protein MLC1 and phosphoglucomutase-related protein 5. The role of the identified proteins in the functioning of the BBB needs further investigations.

中文翻译：

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人脑中血脑屏障相关蛋白的鉴定

血脑屏障（BBB）对于大脑动态平衡至关重要，并控制分子进出大脑的选择性通道。尽管血脑屏障在各种脑部疾病中起着关键作用，并且与药物开发相关，但对其分子结构了解甚少。尤其是，星形胶质细胞的末端脚和内皮细胞之间的基底层的组成仅是部分已知的。在这里，我们提出了人类血脑屏障基底层的蛋白质组学分析。我们将激光捕获显微切割技术与shot弹枪蛋白质组学相结合，用于选择性富集和鉴定存在于从正常人脑组织标本中收集的脑微脉管和蛛网膜血管中的特定蛋白质。通过免疫组织化学验证了与血脑屏障有关的蛋白质。在所有脑屏障中均发现了膜蛋白MLC1的表达。似乎在脑血管的外部可变地存在磷酸葡萄糖突变酶样蛋白5，并且在脑血管和蛛网膜血管中均鉴定出了多药耐药蛋白1。结果证明了迄今为止人类BBB中尚未鉴定的蛋白质的存在，并说明了它们表达中的主题差异。总之，我们证明了通过显微解剖和shot弹枪蛋白质组学纯化的样品提供了BBB中鉴定出的蛋白质列表。随后的免疫组织化学详细描述了膜蛋白MLC1和磷酸葡萄糖突变酶相关蛋白5的各自表达位点。