To understand how cells communicate in the nervous system, it is essential to define their secretome, which is challenging for primary cells because of large cell numbers being required. Here, we miniaturized secretome analysis by developing the “high‐performance secretome protein enrichment with click sugars” (hiSPECS) method. To demonstrate its broad utility, hiSPECS was used to identify the secretory response of brain slices upon LPS‐induced neuroinflammation and to establish the cell type‐resolved mouse brain secretome resource using primary astrocytes, microglia, neurons, and oligodendrocytes. This resource allowed mapping the cellular origin of CSF proteins and revealed that an unexpectedly high number of secreted proteins in vitro and in vivo are proteolytically cleaved membrane protein ectodomains. Two examples are neuronally secreted ADAM22 and CD200, which we identified as substrates of the Alzheimer‐linked protease BACE1. hiSPECS and the brain secretome resource can be widely exploited to systematically study protein secretion and brain function and to identify cell type‐specific biomarkers for CNS diseases.

中文翻译：

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一种优化的定量蛋白质组学方法可建立细胞类型解析的小鼠脑分泌组。

要了解细胞在神经系统中的通讯方式，必须定义其分泌组，这对于原代细胞是一项挑战，因为需要大量的细胞。在这里，我们通过开发“用点击糖进行高性能分泌蛋白富集”（hiSPECS）方法来使分泌蛋白分析最小化。为了证明其广泛的用途，hiSPECS用于鉴定LPS诱导的神经炎症后脑切片的分泌反应，并使用原代星形胶质细胞，小胶质细胞，神经元和少突胶质细胞建立可分辨细胞类型的小鼠脑分泌组。该资源可以绘制出CSF蛋白的细胞起源图谱，并揭示出体内和体内分泌的蛋白质数量异常高是蛋白水解切割的膜蛋白胞外域。两个例子是神经元分泌的ADAM22和CD200，我们将其鉴定为与阿尔茨海默氏症相关的蛋白酶BACE1的底物。hiSPECS和脑分泌物组资源可广泛用于系统研究蛋白质分泌和脑功能，并鉴定中枢神经系统疾病的细胞类型特异性生物标志物。