Visual Cognition Laboratory, Department of Medicine, University of Fribourg , Chemin de Musee 5, Fribourg, CH-1700, Switzerland.
J Proteome Res. 2012 Feb 3;11(2):886-96. doi: 10.1021/pr200709j. Epub 2011 Dec 2.
Neuropeptidomics is used to characterize endogenous peptides in the brain of tree shrews (Tupaia belangeri). Tree shrews are small animals similar to rodents in size but close relatives of primates, and are excellent models for brain research. Currently, tree shrews have no complete proteome information available on which direct database search can be allowed for neuropeptide identification. To increase the capability in the identification of neuropeptides in tree shrews, we developed an integrated mass spectrometry (MS)-based approach that combines methods including data-dependent, directed, and targeted liquid chromatography (LC)-Fourier transform (FT)-tandem MS (MS/MS) analysis, database construction, de novo sequencing, precursor protein search, and homology analysis. Using this integrated approach, we identified 107 endogenous peptides that have sequences identical or similar to those from other mammalian species. High accuracy MS and tandem MS information, with BLAST analysis and chromatographic characteristics were used to confirm the sequences of all the identified peptides. Interestingly, further sequence homology analysis demonstrated that tree shrew peptides have a significantly higher degree of homology to equivalent sequences in humans than those in mice or rats, consistent with the close phylogenetic relationship between tree shrews and primates. Our results provide the first extensive characterization of the peptidome in tree shrews, which now permits characterization of their function in nervous and endocrine system. As the approach developed fully used the conservative properties of neuropeptides in evolution and the advantage of high accuracy MS, it can be portable for identification of neuropeptides in other species for which the fully sequenced genomes or proteomes are not available.
神经肽组学用于研究树鼩（Tupaia belangeri）脑中的内源性肽。树鼩是一种与啮齿类动物大小相似，但与灵长类动物亲缘关系密切的小型动物，是脑研究的优秀模型。目前，树鼩没有完整的蛋白质组信息，无法进行直接的数据库搜索来鉴定神经肽。为了提高树鼩中神经肽鉴定的能力，我们开发了一种集成的质谱（MS）方法，该方法结合了包括数据依赖、定向和靶向液相色谱（LC）-傅里叶变换（FT）-串联 MS（MS/MS）分析、数据库构建、从头测序、前体蛋白搜索和同源性分析等方法。使用这种集成方法，我们鉴定了 107 种内源性肽，其序列与其他哺乳动物物种的序列相同或相似。高准确度的 MS 和 MS/MS 信息，以及 BLAST 分析和色谱特征，用于确认所有鉴定肽的序列。有趣的是，进一步的序列同源性分析表明，树鼩肽与人类的等效序列具有更高的同源性，而与小鼠或大鼠的同源性较低，这与树鼩与灵长类动物之间密切的系统发育关系一致。我们的结果提供了树鼩肽组的首次广泛特征描述，现在可以对其在神经和内分泌系统中的功能进行研究。由于所开发的方法充分利用了神经肽在进化中的保守特性和高准确度 MS 的优势，因此可用于鉴定其他尚未测序的基因组或蛋白质组的物种中的神经肽。
