Biology subjects

Grimsley, G.

Publications and source records attributed to Grimsley, G..

3 recordsLinked to original sources

bioRxiv2026

Different spatial profiles of aberrant N-glycans in pediatric and adult MOGHE brain tissue

Mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE) is a recently recognized epilepsy-associated lesion frequently linked to brain-restricted somatic variants in SLC35A2, a gene encoding the Golgi UDP-galactose transporter. Although previous studies demonstrated altered glycosylation in SLC35A2-mutated MOGHE tissue, the spatial relationship between glycosylation defects and histopathological abnormalities remains poorly understood. We applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) using formalin-fixed paraffin-embedded brain tissue from six histologically confirmed MOGHE cases (three pediatric and three adult) and three temporal lobe epilepsy with hippocampal sclerosis (TLE-HS). We spatially evaluated N-glycan profiles across diagnostic tissue groups, with particular attention to molecular differences between lesional and perilesional regions and to recurrent abundance trends. All MOGHE cases harboured somatic SLC35A2 variants. Histologically, oligodendroglial hyperplasia and heterotopic neurons were present in all cases, while patchy hypomyelination was restricted to pediatric cases. Unsupervised spatial segmentation, integrated with neuropathological evaluation, revealed marked molecular heterogeneity in pediatric MOGHE. In these cases, lesional and perilesional regions were clearly distinguishable in both white matter (WM) and overlying grey matter (GM) boundaries patterns, whereas adult MOGHE and TLE-HS mainly showed a clearcut separation between WM and GM. Spatial analysis confirmed enrichment of the previously reported aberrant N-glycan species m/z 2094 and, to a lesser extent, m/z 2297 within MOGHE tissue, particularly in pediatric lesional WM. Notably, the distribution of m/z 2094 closely overlapped with areas of hypomyelination. Quantitative trajectory analysis of 151 detected N-glycan ions identified recurrent abundance profiles. Three representative spatial patterns emerged: pediatric lesion-enriched, pediatric perilesion-enriched, and TLE-HS-enriched profiles. Pediatric lesions were characterized by increased abundance of multiantennary glycans lacking terminal galactose residues and reduced abundance of galactosylated biantennary and multiantennary structures, consistent with defective UDP-galactose transport. In contrast, adult lesional and perilesional tissues exhibited largely overlapping glycomic profiles. These findings provide the first spatially resolved evidence that glycosylation abnormalities in SLC35A2-mutated MOGHE are closely associated with lesional pathology, particularly hypomyelination, and are substantially more pronounced in pediatric than adult cases. Spatial glycomics may therefore offer new insights into MOGHE pathophysiology and support the development of targeted therapeutic approaches aimed at correcting galactosylation defects.

neuroscience↗

bioRxiv2025

Application of post glycosylation modifying enzymes for mass spectrometry imaging of modified N-glycans in situ.

Glycans are essential components of cells and are involved in innumerable biological processes. Their structural diversity and complexity present unique analytical challenges. Glycans are comprised of various types of monosaccharides that are linked together at different positions and with varied stereochemistry. In addition, glycans are frequently decorated with a diverse set of chemical modifications, termed post-glycosylation modifications (PGMs). Characterization of PGMs is essential for a thorough understanding of glycans, however, the technical challenges and low throughput of current methodologies have limited our understanding of these modifications. Here we demonstrate a novel approach for rapid visualization of specific PGMs present in tissue N-glycans by applying PGM-targeting enzymes to mass spectrometry imaging (MSI). The method enables in situ investigation of glycans with PGMs en masse, identifying the sugar residue and position modified, as well as visualizing the spatial distribution of each modified N-glycan in tissues. As the repertoire of PGM-targeting enzymes expands, we anticipate this approach will enable a better understanding of PGM distribution within a dynamic N-glycome. This may yield both new biological insights and the potential for identification of novel disease biomarkers.

molecular biology↗

bioRxiv2024

Glycosite Mapping and in situ Mass Spectrometry Imaging of MUC2 Glycopeptides via On-slide Digestion with Mucinase StcE

Many cancers are characterized by altered mucin expression and glycosylation, although the mechanistic relationship between tumor glycosylation and disease progression is not well-defined. Herein, our goal was to map specific mucin glycoforms in diseased tissue, enabling correlation of the tumor glycan profile with malignant features. To this end, we developed a workflow implementing on-tissue digestion with mucinase StcE, followed by matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) and liquid chromatography coupled to mass spectrometry (LC-MS). To optimize our workflow, we analyzed four different mucinous carcinomas derived from colon, esophageal, and salivary gland tissue. Using this technique, we deduced the spatial distribution of StcE-generated O-glycopeptides within mucinous tumors using MALDI-IMS. Subsequent LC-MS analyses revealed the identity of different species detected in imaging experiments, in addition to comprehensively characterizing the mucinome and proteome of each tissue. Our coupled MS approach unveiled a striking mucin 2 (MUC2) expression pattern in two colorectal mucinous adenocarcinomas, in which different glycoforms clearly stratified regions within the tumor. Notably, our LC-MS experiments obtained near-complete sequence coverage over the mucin domains of MUC2, enabling glycoproteomic mapping of this canonical mucin in unprecedented depth. MUC2 glycosylation was dominated by the T and Tn antigens, with surprisingly little sialylation detected. However, O-glycans containing mono- and di-O-acetylated sialic acid were detected in low abundance. Finally, we obtained spectral evidence for an endogenous O-acetylated GalNAc, an O-glycan structure not previously reported in the literature. Overall, this proof-of-concept work underscores the potential of this technique to generate new research avenues in oncology and beyond. Significance StatementAberrant mucin expression and glycosylation are hallmarks of cancer, but how these changes promote malignant processes are not well understood. Solid tumors are highly heterogeneous in their cellular and molecular composition, and many advanced spatial techniques have emerged in recent years to study the tumor microenvironment (TME) for better understanding disease progression. Spatially resolved glycoprotein analyses typically detect either the protein or glycan components, but not both. We developed a workflow using a dual mass spectrometry approach to map the location of intact glycopeptides in mucinous tumors, enabled by on-tissue digestion with the mucin-specific protease StcE. Future applications of this method on larger patient cohorts will enhance our understanding of glycans in malignancy, identify disease biomarkers, and define therapeutic targets.

cancer biology↗