LM-GlycomeAtlas Ver. 2.0: An Integrated Visualization for Lectin Microarray-based Mouse Tissue Glycome Mapping Data with Lectin Histochemistry

Global characterization of mouse testis O-glycoproteome landscape during spermatogenesis

Protein O-glycosylation plays critical roles in sperm formation and maturation. However, detailed knowledge on the mechanisms involved is limited due to lacking characterization of O-glycoproteome of testicular germ cells. Here, we performed a systematic analysis of site-specific O-glycosylation in mouse testis, and established an O-glycoproteome map with 349 O-glycoproteins and 799 unambiguous O-glycosites. Moreover, we comprehensively investigated the distribution properties of O-glycosylation in testis and identified a region near the N-terminal of peptidase S1 domain that is susceptible to O-glycosylation. Interestingly, we found dynamic changes with an increase Tn and a decrease T structure from early to mature developmental stages. Notably, the importance of O-glycosylation was supported by its effects on the stability, cleavage, and interaction of acrosomal proteins. Collectively, these data illustrate the global properties of O-glycosylation in testis, providing insights and resources for future functional studies targeting O-glycosylation dysregulation in male infertility.

The minimum information required for a glycomics experiment (MIRAGE) project: improving the standards for reporting lectin microarray data

The MIRAGE (Minimum Information Required for a Glycomics Experiment) project has been established by experts in glycobiology, glycoanalytics, and glycoinformatics under the auspieces of the Beilstein-Institut. The working group aims to develop guidelines for reporting results from various experiments and analyses conducted in structural and functional studies of glycans in the scientific literature. Previous guidelines have been established for glycomic analytics, including mass spectrometry and glycan microarrays. Lectin microarrays are used worldwide for glycan profiling of various biological samples, but there are often insufficient reports on information about experimental methods such as sample preparation and fluorescence labeling. Here, we propose guidelines specifically designed to improve the standards for reporting data from lectin microarray analyses. For each of the seven areas in the workflow of a lectin microarray experiment, we provide recommendations for the minimum information that should be included when reporting results. When adopted by the scientific community the MIRAGE lectin microarray guidelines are expected to enhance data interpretation, facilitate comparison of data between laboratories and encourage the deposition of lectin microarray data in international databases.

Toward spatial glycomics and glycoproteomics: Innovations and applications

In this mini review, we provide an overview of the challenging field of spatial glycomics/glycoproteomics. Owing to their complexity, sophisticated analytical methods and innovative technologies are needed to advance this field. An agile development approach enables unraveling aberrant glycosylations, glycobiomarkers, and glycotargets for spatial imaging, diagnosis, and therapeutic purposes. We discuss glycopathology and tissue glycomic profiling using highly sensitive lectin-based analyses and introduce deep visual proteomics for glycomic/glycoproteomic sample preparation. Additionally, we highlight the importance of leveraging laser microdissection and artificial intelligence-driven visual software for cell-type assignment and automation techniques, which are crucial for advancing glycomics/glycoproteomics.

Inter-tissue glycan heterogeneity: site-specific glycoform analysis of mouse tissue N-glycoproteomes using MS1-based glycopeptide detection method assisted by lectin microarray

To understand the biological and pathological functions of protein glycosylation, the glycan heterogeneities for each glycosite in a single glycoprotein need to be elucidated depending on the type and status of cells. For this aim, a reliable strategy is needed to compare site-specific glycoforms of multiple glycoprotein samples in a comprehensive manner. To analyze this "inter-heterogeneity" of samples, we previously introduced an MS1-based glycopeptide detection method, "Glyco-RIDGE." Here, to elucidate inter-tissue glycan heterogeneities, this estimation method was applied to site-specific N-glycoforms of glycoproteins from six normal mouse tissues (liver, kidney, spleen, pancreas, stomach, and testis). The analyses of desialylated glycopeptides estimated 11,325 site-specific N-glycoforms with 239 glycan compositions at 1260 sites (1122 non-redundant core peptides) in 800 glycoproteins, revealing inter-tissue differences in macro-, micro-, and meta-glycan heterogeneities. To obtain detailed information on their glycan features and tissue distribution, the Glyco-RIDGE results were compared with laser microdissection-assisted lectin microarray (LMD-LMA)-based mouse tissue glycome mapping data deposited on LM-GlycomeAtlas, as well as MS-based mouse tissue glycome data deposited on GlycomeAtlas. This integrated approach supported the certainty of Glyco-RIDGE results and suggested that inter-tissue differences exist in glycan motifs, such as alpha-galactose and bisecting N-acetylglucosamine, in both whole tissue glycomes and specific glycoproteins, Anpep and Lamc1. In addition, the comparison with LMD-LMA-based tissue glycome mapping data suggested the possibility of estimating the tissue distribution of the assigned glycans and glycopeptides. Taken together, these findings demonstrate the utility of an integrated approach using MS assisted by LMA for large-scale analyses.

Expanding the recognition of monosaccharides and glycans: A comprehensive analytical approach using chemical-nose/tongue technology and a comparison to lectin microarrays

Chemical-nose/tongue technologies are emerging as promising analytical tools for glycan analysis. After briefly introducing the importance of glycans and their analytical methods, including the lectin microarray (LMA) as one of the gold standards, the fundamental principles underlying chemical noses/tongues are explained and various applications for monosaccharides and glycans are introduced. Then, the similarities and differences of these two approaches are discussed. While both technologies aim to comprehensively profile biospecimens based on 'interaction patterns' between multiple recognition probes and analytes, each has its own strengths. LMAs excel at specific, targeted analysis based on defined lectin-glycan interactions, whereas chemical nose/tongue offers greater flexibility and expandability in terms of system design, making it well-suited for discovering unknown glycan profiles and detecting broader differences in glycan mixtures. In the future, chemical-nose/tongue technologies may be applied to niche areas in glycan analysis and become powerful tools that complement LMA techniques.

Non-targeted N-glycome profiling reveals multiple layers of organ-specific diversity in mice

N-glycosylation is one of the most common protein modifications in eukaryotes, with immense importance at the molecular, cellular, and organismal level. Accurate and reliable N-glycan analysis is essential to obtain a systems-wide understanding of fundamental biological processes. Due to the structural complexity of glycans, their analysis is still highly challenging. Here we make publicly available a consistent N-glycome dataset of 20 different mouse tissues and demonstrate a multimodal data analysis workflow that allows for unprecedented depth and coverage of N-glycome features. This highly scalable, LC-MS/MS data-driven method integrates the automated identification of N-glycan spectra, the application of non-targeted N-glycome profiling strategies and the isomer-sensitive analysis of glycan structures. Our delineation of critical sub-structural determinants and glycan isomers across the mouse N-glycome uncovered tissue-specific glycosylation patterns, the expression of non-canonical N-glycan structures and highlights multiple layers of N-glycome complexity that derive from organ-specific regulations of glycobiological pathways.

Non-targeted isomer-sensitive N-glycome analysis reveals new layers of organ-specific diversity in mice

N-glycosylation is one of the most common protein modifications in eukaryotes, with immense importance at the molecular, cellular, and organismal level. Accurate and reliable N-glycan analysis is essential to obtain a systems-wide understanding of fundamental biological processes. Due to the structural complexity of glycans, their analysis is still highly challenging. Here we make publicly available a consistent N-glycome dataset of 20 different mouse tissues and demonstrate a multimodal data analysis workflow that allows for unprecedented depth and coverage of N-glycome features. This highly scalable, LC-MS/MS data-driven method integrates the automated identification of N-glycan spectra, the application of non-targeted N-glycome profiling strategies and the isomer-sensitive analysis of glycan structures. Our delineation of critical sub-structural determinants and glycan isomers across the mouse N-glycome uncovered tissue-specific glycosylation patterns, the expression of non-canonical N-glycan structures and highlights multiple layers of N-glycome complexity that derive from organ-specific regulations of glycobiological pathways.

An improved evanescent fluorescence scanner suitable for high-resolution glycome mapping of formalin-fixed paraffin-embedded tissue sections

Lectin microarray (LMA) is a high-throughput platform that enables the rapid and sensitive analysis of N- and O-glycans attached to glycoproteins in biological samples, including formalin-fixed paraffin-embedded (FFPE) tissue sections. Here, we evaluated the sensitivity of the advanced scanner based on the evanescent-field fluorescence principle, which is equipped with a 1× infinity correction optical system and a high-end complementary metal-oxide semiconductor (CMOS) image sensor in digital binning mode. Using various glycoprotein samples, we estimated that the mGSR1200-CMOS scanner has at least fourfold higher sensitivity for the lower limit of linearity range than that of a previous charge-coupled device scanner (mGSR1200). A subsequent sensitivity test using HEK293T cell lysates demonstrated that cell glycomic profiling could be performed with only three cells, which has the potential for the glycomic profiling of cell subpopulations. Thus, we examined its application in tissue glycome mapping, as indicated in the online LM-GlycomeAtlas database. To achieve fine glycome mapping, we refined the laser microdissection-assisted LMA procedure to analyze FFPE tissue sections. In this protocol, it was sufficient to collect 0.1 mm2 of each of the tissue fragments from 5-μm-thick sections, which differentiated the glycomic profile between the glomerulus and renal tubules of a normal mouse kidney. In conclusion, the improved LMA enables high-resolution spatial analysis, which expands the possibilities of its application classifying cell subpopulations in clinical FFPE tissue specimens. This will be used in the discovery phase for the development of novel glyco-biomarkers and therapeutic targets, and to expand the range of target diseases.

Tissue Glycome Mapping: Lectin Microarray-Based Differential Glycomic Analysis of Formalin-Fixed Paraffin-Embedded Tissue Sections

Lectin microarray (LMA) is a high-sensitive glycan analysis technology used to obtain global glycomic profiles of both N- and O-glycans attached not only to purified glycoproteins but also to crude glycoprotein samples. Through additional use of laser microdissection (LMD) for tissue collection, we developed an LMA-based glycomic profiling technique for a specific type of cells in a tiny area of formalin-fixed paraffin-embedded (FFPE) tissue sections. This LMD-LMA method makes it possible to obtain reproducible tissue glycomic profiles that can be compared with each other, using a unified protocol for all procedures, including FFPE tissue preparation, tissue staining, protein extraction and labeling, and LMA analysis. Here, we describe the standardized LMD-LMA procedure for a "tissue glycome mapping" approach, which facilitates an in-depth understanding of region- and tissue-specific protein glycosylation. We also describe potential applications of the spatial tissue glycomic profiles, including histochemical analysis for evaluating distribution of lectin ligands and a fluorescence LMD-LMA method for cell type-selective glycomic profiling using a cell type-specific probe, composed of a lectin and an antibody. The protocols presented here will accelerate the effective utilization of FFPE tissue specimens by providing tissue glycome maps for the discovery of the biological roles and disease-related alterations of protein glycosylation.