Weigand Miranda R, Moore Alyssa M, Hu Hang, Angel Peggi M, Drake Richard R, Laskin Julia
Department of Chemistry, College of Science, Purdue University, West Lafayette, Indiana 47907, United States.
Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, United States.
J Am Soc Mass Spectrom. 2023 Nov 1;34(11):2481-2490. doi: 10.1021/jasms.3c00209. Epub 2023 Oct 1.
N-linked glycans are complex biomolecules vital to cellular functions that have been linked to a wide range of pathological conditions. Mass spectrometry imaging (MSI) has been used to study the localization of N-linked glycans in cells and tissues. However, their structural diversity presents a challenge for MSI techniques, which stimulates the development of new approaches. In this study, we demonstrate for the first time spatial mapping of N-linked glycans in biological tissues using nanospray desorption electrospray ionization mass spectrometry imaging (nano-DESI MSI). Nano-DESI MSI is an ambient ionization technique that has been previously used for imaging of metabolites, lipids, and proteins in biological tissue samples without special sample pretreatment. N-linked glycans are released from glycoproteins using an established enzymatic digestion with peptide -glycosidase F, and their spatial localization is examined using nano-DESI MSI. We demonstrate imaging of N-linked glycans in formalin-fixed paraffin-embedded human hepatocellular carcinoma and human prostate tissues in both positive and negative ionization modes. We examine the localization of 38 N-linked glycans consisting of high mannose, hybrid fucosylated, and sialyated glycans. We demonstrate that negative mode nano-DESI MSI is well-suited for imaging of underivatized sialylated N-linked glycans. On-tissue MS/MS of different adducts of N-linked glycans proves advantageous for elucidation of the glycan sequence. This study demonstrates the applicability of liquid extraction techniques for spatial mapping of N-linked glycans in biological samples, providing an additional tool for glycobiology research.
N-连接聚糖是对细胞功能至关重要的复杂生物分子，与多种病理状况相关。质谱成像（MSI）已被用于研究N-连接聚糖在细胞和组织中的定位。然而，它们的结构多样性给MSI技术带来了挑战，这推动了新方法的发展。在本研究中，我们首次使用纳米喷雾解吸电喷雾电离质谱成像（nano-DESI MSI）展示了生物组织中N-连接聚糖的空间图谱。Nano-DESI MSI是一种常压电离技术，此前已用于在无需特殊样品预处理的情况下对生物组织样品中的代谢物、脂质和蛋白质进行成像。使用肽-N-糖苷酶F进行既定的酶促消化从糖蛋白中释放出N-连接聚糖，并使用nano-DESI MSI检查它们的空间定位。我们在正离子和负离子模式下展示了福尔马林固定石蜡包埋的人类肝细胞癌和人类前列腺组织中N-连接聚糖的成像。我们研究了由高甘露糖型、杂交岩藻糖基化型和唾液酸化型聚糖组成的38种N-连接聚糖的定位。我们证明负离子模式的nano-DESI MSI非常适合未衍生化的唾液酸化N-连接聚糖的成像。对N-连接聚糖不同加合物进行组织上的串联质谱分析证明有利于阐明聚糖序列。本研究证明了液体萃取技术在生物样品中N-连接聚糖空间图谱绘制方面的适用性，为糖生物学研究提供了一种额外的工具。
