Abstract

O-Glycans on cell surfaces play important roles in cell–cell, cell–matrix and receptor–ligand interaction. Therefore, glycan-based interactions are important for tissue regeneration and homeostasis. Free-living flatworm Schmidtea mediterranea, because of its robust regenerative potential, is of great interest in the field of stem cell biology and tissue regeneration. Nevertheless, information on the composition and structure of O-glycans in planaria is unknown. Using mass spectrometry and in silico approaches, we characterized the glycome and the related transcriptome of mucin-type O-glycans of planarian S. mediterranea. Mucin-type O-glycans were composed of multiple isomeric, methylated, and unusually extended mono- and disubstituted O-N-acetylgalactosamine structures. Extensions made of hexoses and 3-O-methyl hexoses were the glycoforms observed. From glycotranscriptomic analysis, 60 genes belonging to five distinct enzyme classes were identified to be involved in mucin-type O-glycan biosynthesis. These genes shared homology with those in other invertebrate systems. Although a majority of the genes involved in mucin-type O-glycan biosynthesis were highly expressed during organogenesis and in differentiated cells, a few select genes in each enzyme class were specifically enriched during early embryogenesis. Our results indicate a unique temporal and spatial role for mucin-type O-glycans during embryogenesis and organogenesis and in adulthood. In summary, this is the first report on O-glycans in planaria. This study expands the structural and biosynthetic possibilities in cellular glycosylation in the invertebrate glycome and provides a framework towards understanding the biological role of mucin-type O-glycans in tissue regeneration using planarians.

中文翻译：

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涡虫 Schmidtea mediterranea 粘蛋白型 O-聚糖的糖组学和糖转录组学分析

摘要

细胞表面的O-聚糖在细胞-细胞、细胞-基质和受体-配体相互作用中发挥重要作用。因此，基于聚糖的相互作用对于组织再生和体内平衡很重要。自由生活的扁虫Schmidtea mediterranea由于其强大的再生潜力，在干细胞生物学和组织再生领域引起了极大的兴趣。然而，关于涡虫中O-聚糖的组成和结构的信息尚不清楚。使用质谱和计算机方法，我们对涡虫S. mediterranea的粘蛋白型O-聚糖的糖组和相关转录组进行了表征。粘蛋白O型-聚糖由多种异构、甲基化和异常延伸的单取代和双取代O - N -乙酰半乳糖胺结构组成。由己糖和 3- O-甲基己糖制成的延伸是观察到的糖型。根据糖转录组学分析，属于五种不同酶类的 60 个基因被鉴定为参与粘蛋白型O-聚糖的生物合成。这些基因与其他无脊椎动物系统中的基因具有同源性。尽管大多数与粘蛋白O型有关的基因-聚糖生物合成在器官发生过程和分化细胞中高度表达，每个酶类中的一些选择基因在早期胚胎发生过程中特异性富集。我们的结果表明粘蛋白型O-聚糖在胚胎发生和器官发生期间以及成年期具有独特的时间和空间作用。总之，这是关于涡虫中O-聚糖的第一份报告。本研究扩展了无脊椎动物糖组中细胞糖基化的结构和生物合成可能性，并为了解粘蛋白型O-聚糖在使用涡虫的组织再生中的生物学作用提供了一个框架。