Linkage-Specific in Situ Sialic Acid Derivatization for N-Glycan Mass Spectrometry Imaging of Formalin-Fixed Paraffin-Embedded Tissues
Linkage-Specific in Situ Sialic Acid Derivatization for N-Glycan Mass Spectrometry Imaging of Formalin-Fixed Paraffin-Embedded Tissues
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DOI：
10.1021/acs.analchem.6b00819
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发表时间：
2016-06-07
影响因子：
7.4
通讯作者：
Wuhrer, Manfred
中科院分区：
文献类型：
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作者：
Holst, Stephanie;Heijs, Bram;Wuhrer, Manfred
基质辅助激光解吸/电离(MALDI)质谱学成像是一个快速发展的领域，它将质谱学技术直接应用于组织上，以表征各种分子的空间分布，如脂类、蛋白质/肽，最近还包括N-糖链。葡聚糖参与了许多生物过程，几种糖链的变化与不同种类的癌症有关，使它们成为一个有趣的研究靶群。用MALDI质谱仪研究多糖的一个重要的分析挑战是唾液酸基的不稳定特性，这些基团容易在源内/源后衰变，从而对记录的糖链图谱产生偏差。因此，我们开发了一种通过二甲胺化和随后的酰胺化来连接特定的唾液酸衍生物，并将其转移到福尔马林固定的石蜡包埋(FFPE)组织上，用于N-糖链的MALDI成像。我们的结果表明：(I)成功地以连接特异性的方式稳定了唾液酸，从而不仅增加了检测范围，而且增加了生物学意义，(Ii)在样品制备过程中没有引起明显的侧向扩散，(Iii)质谱仪成像在空间上表征N-糖链在不同组织中表达的潜力。
Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging is a rapidly evolving field in which mass spectrometry techniques are applied directly on tissues to characterize the spatial distribution of various molecules such as lipids, protein/peptides, and recently also N-glycans. Glycans are involved in many biological processes and several glycan changes have been associated with different kinds of cancer, making them an interesting target group to study. An important analytical challenge for the study of glycans by MALDI mass spectrometry is the labile character of sialic acid groups which are prone to in-source/postsource decay, thereby biasing the recorded glycan profile. We therefore developed a linkage-specific sialic acid derivatization by dimethylamidation and subsequent amidation and transferred this onto formalin-fixed paraffin-embedded (FFPE) tissues for MALDI imaging of N-glycans. Our results show (i) the successful stabilization of sialic acids in a linkage specific manner, thereby not only increasing the detection range, but also adding biological meaning, (ii) that no noticeable lateral diffusion is induced during to sample preparation, (iii) the potential of mass spectrometry imaging to spatially characterize the N-glycan expression within heterogeneous tissues.