Pasarow Mass Spectrometry Laboratory, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
PLoS One. 2010 Feb 9;5(2):e9121. doi: 10.1371/journal.pone.0009121.
The central nervous system (CNS) develops from a heterogeneous pool of neural stem and progenitor cells (NSPC), the underlying differences among which are poorly understood. The study of NSPC would be greatly facilitated by the identification of additional proteins that mediate their function and that would distinguish amongst different progenitor populations.
METHODOLOGY/PRINCIPAL FINDINGS: To identify membrane and membrane-associated proteins expressed by NSPC, we used a proteomics approach to profile NSPC cultured as neurospheres (NS) isolated from the murine cortex during a period of neurogenesis (embryonic day 11.5, E11.5), as compared to NSPC isolated at a peak of gliogenesis (postnatal day 1, P0) and to differentiated E11.5 NS. 54 proteins were identified with high expression in E11.5 NS, including the TrkC receptor, several heterotrimeric G proteins, and the Neogenin receptor. 24 proteins were identified with similar expression in E11.5 and P0 NS over differentiated E11.5 NS, and 13 proteins were identified with high expression specifically in P0 NS compared to E11.5 NS. To illustrate the potential relevance of these identified proteins to neural stem cell biology, the function of Neogenin was further studied. Using Fluorescence Activated Cell Sorting (FACS) analysis, expression of Neogenin was associated with a self-renewing population present in both E11.5 and adult subventricular zone (SVZ) NS but not in P0 NS. E11.5 NS expressed a putative Neogenin ligand, RGMa, and underwent apoptosis when exposed to a ligand-blocking antibody.
CONCLUSIONS/SIGNIFICANCE: There are fundamental differences between the continuously self-renewing and more limited progenitors of the developing cortex. We identified a subset of differentially expressed proteins that serve not only as a set of functionally important proteins, but as a useful set of markers for the subsequent analysis of NSPC. Neogenin is associated with the continuously self-renewing and neurogenic cells present in E11.5 cortical and adult SVZ NS, and the Neogenin/RGMa receptor/ligand pair may regulate cell survival during development.
中枢神经系统（CNS）由异质的神经干细胞和祖细胞（NSPC）组成，其基础差异尚不清楚。如果能够鉴定出更多介导 NSPC 功能的蛋白，并将其与不同祖细胞群体区分开来，将极大地促进对 NSPC 的研究。
方法/主要发现：为了鉴定 NSPC 表达的膜和膜相关蛋白，我们使用蛋白质组学方法对从 E11.5 胚胎大脑皮层分离的神经球（NS）中培养的 NSPC 进行了分析，与从 P0 时的分化高峰期分离的 NSPC 相比，与分化后的 E11.5 NS 相比，E11.5 NS 中高表达 54 种蛋白，包括 TrkC 受体、几种异三聚体 G 蛋白和 Neogenin 受体。在 E11.5 和 P0 NS 中鉴定出 24 种与分化后的 E11.5 NS 相似表达的蛋白，在 P0 NS 中鉴定出 13 种高表达的蛋白，与 E11.5 NS 相比。为了说明这些鉴定出的蛋白与神经干细胞生物学的潜在相关性，进一步研究了 Neogenin 的功能。通过荧光激活细胞分选（FACS）分析，E11.5 和成年侧脑室下区（SVZ）NS 中均存在自我更新的 Neogenin 表达群体，但在 P0 NS 中不存在。E11.5 NS 表达一种假定的 Neogenin 配体 RGMa，当暴露于配体阻断抗体时，E11.5 NS 会发生凋亡。
结论/意义：发育中的大脑皮层的持续自我更新和有限的祖细胞之间存在根本差异。我们鉴定出一组差异表达蛋白，它们不仅作为一组功能重要的蛋白，而且作为随后分析 NSPC 的有用标记物。Neogenin 与 E11.5 皮质和成年 SVZ NS 中持续自我更新和神经发生细胞相关，Neogenin/RGMa 受体/配体对可能在发育过程中调节细胞存活。
