On the frequency of protein glycosylation, as deduced from analysis of the SWISS-PROT database

Identification and characterization of emGalaseE, a β-1,4 galactosidase from Elizabethkingia meningoseptica, and its application on living cell surface

The biological function of terminal galactose on glycoprotein is an open field of research. Although progress had being made on enzymes that can remove the terminal galactose on glycoproteins, there is a lack of report on galactosidases that can work directly on living cells. In this study, a unique beta 1,4 galactosidase was isolated from Elizabethkingia meningoseptica (Em). It exhibited favorable stability at various temperatures (4-37 °C) and pH (5-8) levels and can remove β-1, 4 linked galactoses directly from glycoproteins. Using Alanine scanning, we found that two acidic residues (Glu-468, and Glu-531) in the predicted active pocket are critical for galactosidase activity. In addition, we also demonstrated that it could cleave galactose residues present on living cell surface. As this enzyme has a potential application for living cell glycan editing, we named it emGalaseE or glycan-editing galactosidase I (csgeGalaseI). In summary, our findings lay the groundwork for further investigation by presenting a simple and effective approach for the removal of galactose moieties from cell surface.

Glycosphingolipids in congenital disorders of glycosylation (CDG)

Congenital disorders of glycosylation (CDG) are a large family of rare disorders affecting the different glycosylation pathways. Defective glycosylation can affect any organ, with varying symptoms among the different CDG. Even between individuals with the same CDG there is quite variable severity. Associating specific symptoms to deficiencies of certain glycoproteins or glycolipids is thus a challenging task. In this review, we focus on the glycosphingolipid (GSL) synthesis pathway, which is still rather unexplored in the context of CDG, and outline the functions of the main GSLs, including gangliosides, and their role in the central nervous system. We provide an overview of GSL studies that have been performed in CDG and show that abnormal GSL levels are not only observed in CDG directly affecting GSL synthesis, but also in better known CDG, such as PMM2-CDG. We highlight the importance of studying GSLs in CDG in order to better understand the pathophysiology of these disorders.

Comparative Analysis of Site-Specific N-glycosylation of LAMP1 from Breast Cancer Tissues

Glycosylation changes in cancer proteins have been associated with malignant transformation. However, techniques for analyzing site-specific glycosylation changes in target proteins obtained from clinical tissue samples are insufficient. To overcome these problems, we developed a targeted N-glycoproteomic approach consisting of immunoprecipitation, glycopeptide enrichment, LC/MS/MS and structural assignment using commercially available analytical software followed by manual confirmation. This approach was applied to the comparative site-specific glycosylation analysis of lysosome-associated membrane glycoprotein 1 (LAMP1) between breast cancer (BC) tumors and normal tissues adjacent to tumors. Extensive determination of glycan heterogeneity from four N-glycosylation sites (Asn84/103/249/261) in LAMP1 identified 262 glycoforms and revealed remarkable diversity in tumor glycan structures. A significant increase in N-glycoforms with multiple fucoses and sialic acids at Asn84/249 and high-mannose-type glycans at Asn103/261 were observed in the tumor. Principal component analysis revealed that tumors of different subtypes have independent distributions. This approach enables site-specific glycopeptide analysis of target glycoprotein in breast cancer tissue and become a powerful tool for characterizing tumors with different pathological features by their glycan profiles.

Development of Glycosylation-Modified DPPA-1 Compounds as Innovative PD-1/PD-L1 Blockers: Design, Synthesis, and Biological Evaluation

In the context of peptide drug development, glycosylation plays a pivotal role. Accordingly, L-type peptides were synthesized predicated upon the PD-1/PD-L1 blocker DPPA-1. Subsequent glycosylation resulted in the production of two distinct glycopeptides, D-glu-LPPA-1 and D-gal-LPPA-1, by using D-glucose (D-glu) and D-galactose (D-gal), respectively, during glycosylation. Both glycopeptides significantly inhibited the interaction between PD-1 and PD-L1, and the measured half maximal inhibitory concentrations (IC50s) were 75.5 μM and 101.9 μM for D-glu-LPPA-1 and D-gal-LPPA-1, respectively. Furthermore, D-gal-LPPA-1 displayed a pronounced ability to restore T-cell functionality. In an MC38 tumor-bearing mouse model, D-gal-LPPA-1 demonstrated a significant inhibitory effect. Notably, D-gal-LPPA-1 substantially augmented the abundance and functionality of CD8+ T cells in the tumor microenvironment. Additionally, in the lymph nodes and spleens, D-gal-LPPA-1 significantly increased the proportion of CD8+ T cells secreting interferon-gamma (IFN-γ). These strong findings position D-gal-LPPA-1 as a potent enhancer of the antitumor immune response in MC38 tumor-bearing mice, underscoring its potential as a formidable PD-1/PD-L1 blocking agent.

Labeling of Mucin-Type O-Glycans for Quantification Using Liquid Chromatography and Fluorescence Detection

O-glycosylation is a common post-translational modification that is essential for the defensive properties of mucus barriers. Incomplete and altered O-glycosylation is often linked to severe diseases, such as cancer, cystic fibrosis, and chronic obstructive pulmonary disease. Originating from a nontemplate-driven biosynthesis, mucin-type O-glycan structures are very complex. They are often present as heterogeneous mixtures containing multiple isomers. Therefore, the analysis of complex O-glycan mixtures usually requires hyphenation of orthogonal techniques such as liquid chromatography (LC), ion mobility spectrometry, and mass spectrometry (MS). However, MS-based techniques are mainly qualitative. Moreover, LC separation of O-glycans often lacks reproducibility and requires sophisticated data treatment and analysis. Here we present a mucin-type O-glycomics analysis workflow that utilizes hydrophilic interaction liquid chromatography for separation and fluorescence labeling for detection and quantification. In combination with mass spectrometry, a detailed analysis on the relative abundance of specific mucin-type O-glycan compositions and features, such as fucose, sialic acids, and sulfates, is performed. Furthermore, the average number of monosaccharide units of O-glycans in different samples was determined. To demonstrate universal applicability, the method was tested on mucins from different tissue types and mammals, such as bovine submaxillary mucins, porcine gastric mucins, and human milk mucins. To account for day-to-day retention time shifts in O-glycan separations and increase the comparability between different instruments and laboratories, we included fluorescently labeled dextran ladders in our workflow. In addition, we set up a library of glucose unit values for all identified O-glycans, which can be used to simplify the identification process of glycans in future analyses.

A quest for cytosolic sequons and their functions

Evolution shapes protein sequences for their functions. Here, we studied the moonlighting functions of the N-linked sequon NXS/T, where X is not P, in human nucleocytosolic proteins. By comparing membrane and secreted proteins in which sequons are well known for N-glycosylation, we discovered that cyto-sequons can participate in nucleic acid binding, particularly in zinc finger proteins. Our global studies further discovered that sequon occurrence is largely proportional to protein length. The contribution of sequons to protein functions, including both N-glycosylation and nucleic acid binding, can be regulated through their density as well as the biased usage between NXS and NXT. In proteins where other PTMs or structural features are rich, such as phosphorylation, transmembrane ɑ-helices, and disulfide bridges, sequon occurrence is scarce. The information acquired here should help understand the relationship between protein sequence and function and assist future protein design and engineering.

Effects of Cold Plasma Pretreatment on the Synthesis of Polysaccharide from Pleurotus ostreatus

Fungal polysaccharides have attracted wide attention because of their medical pharmaceutical and health care value. So far, many efforts have been made in strain improvement to produce polysaccharides on a large scale at low cost. Here, a novel cold plasma-induced strain improvement technology was employed to pretreat Pleurotus ostreatus CGMCC 5.374 by radio-frequency (RF) low-vacuum cold plasma (LVCP) for the purpose of obtaining a high-yield polysaccharide strain. The optimum pretreatment conditions including discharge power, treatment time, and working pressure were determined by single factor and orthogonal experiment in succession. Furthermore, transcriptome analysis was conducted to study the effects of RF-LVCP on cell metabolism and proliferation. Results showed that under the optimal condition of discharge power of 130 W, treatment time of 25 s and working pressure of 140 Pa, polysaccharide content in mycelium was increased by 3.16% after 6 days in comparison to the original strain. Transcriptome analysis showed that RF-LVCP is helpful for specific gene transcription profiles, Gene Ontology (GO) and KEGG pathways, of which the differentially expressed genes (DEGs) were mainly involve with the up-regulation of polysaccharide transport, physiology, synthesis and metabolism, as well as the down-regulation of polysaccharide hydrolysis and macromolecular degradation.

Early-life perfluorooctanoic acid exposure disrupts the function of dopamine transporter protein with glycosylation changes implicating the links between decreased dopamine levels and disruptive behaviors in larval zebrafish

Exposure to perfluorooctanoic acid (PFOA) during early embryonic development is associated with the increased risk of developmental neurotoxicity and neurobehavioral disorders in children. In our previous study, we demonstrated that exposure to PFOA affected locomotor activity and disrupted dopamine-related gene expression in zebrafish larvae. Consequently, we continue to study the dopaminergic system with a focus on dopamine levels and dopamine's effect on behaviors in relation to PFOA exposure. In the present study, we found a decrease in dopamine levels in larval zebrafish. We studied the dopamine transporter (DAT) protein, which is responsible for regulating dopamine levels through the reuptake of dopamine in neuronal cells. We demonstrated that exposure to PFOA disrupted the glycosylation process of DAT, inhibited its uptake function, and induced endoplasmic reticulum (ER) stress in dopaminergic cells. Besides, we conducted a light-dark preference test on larval zebrafish and observed anxiety/depressive-like behavioral changes following exposure to PFOA. Dopamine is one of the most prominent neurotransmitters that significantly influences human behavior, with low dopamine levels being associated with impairments such as anxiety and depression. The anxiety-like response in zebrafish larvae exposure to PFOA implies the link with the reduced dopamine levels. Taken together, we can deduce that glycosylation changes in DAT lead to dysfunction of DAT to regulate dopamine levels, which in turn alters behavior in larval zebrafish. Therefore, alternation in dopamine levels may play a pivotal role in the development of anxiety/depressive-like behavioral changes induced by PFOA.

N-glycomic profiling of capsid proteins from Adeno-Associated Virus serotypes

Adeno-associated virus (AAV) vector has become the leading platform for gene delivery. Each serotype exhibits a different tissue tropism, immunogenicity, and in vivo transduction performance. Therefore, selecting the most suitable AAV serotype is critical for efficient gene delivery to target cells or tissues. Genome divergence among different serotypes is due mainly to the hypervariable regions of the AAV capsid proteins. However, the heterogeneity of capsid glycosylation is largely unexplored. In the present study, the N-glycosylation profiles of capsid proteins of AAV serotypes 1 to 9 have been systemically characterized and compared using a previously developed high-throughput and high-sensitivity N-glycan profiling platform. The results showed that all 9 investigated AAV serotypes were glycosylated, with comparable profiles. The most conspicuous feature was the high abundance mannosylated N-glycans, including FM3, M5, M6, M7, M8, and M9, that dominated the chromatograms within a range of 74 to 83%. Another feature was the relatively lower abundance of fucosylated and sialylated N-glycan structures, in the range of 23%-40% and 10%-17%, respectively. However, the exact N-glycan composition differed. These differences may be utilized to identify potential structural relationships between the 9 AAV serotypes. The current research lays the foundation for gaining better understanding of the importance of N-glycans on the AAV capsid surface that may play a significant role in tissue tropism, interaction with cell surface receptors, cellular uptake, and intracellular processing.

Orthogonal Translation for Site-Specific Installation of Post-translational Modifications

Post-translational modifications (PTMs) endow proteins with new properties to respond to environmental changes or growth needs. With the development of advanced proteomics techniques, hundreds of distinct types of PTMs have been observed in a wide range of proteins from bacteria, archaea, and eukarya. To identify the roles of these PTMs, scientists have applied various approaches. However, high dynamics, low stoichiometry, and crosstalk between PTMs make it almost impossible to obtain homogeneously modified proteins for characterization of the site-specific effect of individual PTM on target proteins. To solve this problem, the genetic code expansion (GCE) strategy has been introduced into the field of PTM studies. Instead of modifying proteins after translation, GCE incorporates modified amino acids into proteins during translation, thus generating site-specifically modified proteins at target positions. In this review, we summarize the development of GCE systems for orthogonal translation for site-specific installation of PTMs.

Direct Formation of Amide-Linked C-Glycosyl Amino Acids and Peptides via Photoredox/Nickel Dual Catalysis

Glycoproteins account for numerous biological processes including those associated with diseases and infections. The advancement of glycopeptides has emerged as a promising strategy for unraveling biological pathways and discovering novel medicines. In this arena, a key challenge arises from the absence of efficient synthetic strategies to access glycopeptides and glycoproteins. Here, we present a highly concise approach to bridging saccharides with amino acids and peptides through an amide linkage. Our amide-linked C-glycosyl amino acids and peptides are synthesized through cooperative Ni-catalyzed and photoredox processes. The catalytic process generates a glycosyl radical and an amide carbonyl radical, which subsequently combine to yield the C-glycosyl products. The saccharide reaction partners encompass mono-, di-, and trisaccharides. All 20 natural amino acids, peptides, and their derivatives can efficiently undergo glycosylations with yields ranging from acceptable to high, demonstrating excellent stereoselectivities. As a substantial expansion of applications, we have shown that simple C-glycosyl amino acids can function as versatile building units for constructing C-glycopeptides with intricate spatial complexities.

N-Glycosylation as a Modulator of Protein Conformation and Assembly in Disease

Glycosylation, a prevalent post-translational modification, plays a pivotal role in regulating intricate cellular processes by covalently attaching glycans to macromolecules. Dysregulated glycosylation is linked to a spectrum of diseases, encompassing cancer, neurodegenerative disorders, congenital disorders, infections, and inflammation. This review delves into the intricate interplay between glycosylation and protein conformation, with a specific focus on the profound impact of N-glycans on the selection of distinct protein conformations characterized by distinct interactomes-namely, protein assemblies-under normal and pathological conditions across various diseases. We begin by examining the spike protein of the SARS virus, illustrating how N-glycans regulate the infectivity of pathogenic agents. Subsequently, we utilize the prion protein and the chaperone glucose-regulated protein 94 as examples, exploring instances where N-glycosylation transforms physiological protein structures into disease-associated forms. Unraveling these connections provides valuable insights into potential therapeutic avenues and a deeper comprehension of the molecular intricacies that underlie disease conditions. This exploration of glycosylation's influence on protein conformation effectively bridges the gap between the glycome and disease, offering a comprehensive perspective on the therapeutic implications of targeting conformational mutants and their pathologic assemblies in various diseases. The goal is to unravel the nuances of these post-translational modifications, shedding light on how they contribute to the intricate interplay between protein conformation, assembly, and disease.

Glycan-specific molecularly imprinted polymers towards cancer diagnostics: merits, applications, and future perspectives

Aberrant glycans are a hallmark of cancer states. Notably, emerging evidence has demonstrated that the diagnosis of cancers with tumour-specific glycan patterns holds great potential to address unmet medical needs, especially in improving diagnostic sensitivity and selectivity. However, despite vast glycans having been identified as potent markers, glycan-based diagnostic methods remain largely limited in clinical practice. There are several reasons that prevent them from reaching the market, and the lack of anti-glycan antibodies is one of the most challenging hurdles. With the increasing need for accelerating the translational process, numerous efforts have been made to find antibody alternatives, such as lectins, boronic acids and aptamers. However, issues concerning affinity, selectivity, stability and versatility are yet to be fully addressed. Molecularly imprinted polymers (MIPs), synthetic antibody mimics with tailored cavities for target molecules, hold the potential to revolutionize this dismal progress. MIPs can bind a wide range of glycan markers, even those without specific antibodies. This capacity effectively broadens the clinical applicability of glycan-based diagnostics. Additionally, glycoform-resolved diagnosis can also be achieved through customization of MIPs, allowing for more precise diagnostic applications. In this review, we intent to introduce the current status of glycans as potential biomarkers and critically evaluate the challenges that hinder the development of in vitro diagnostic assays, with a particular focus on glycan-specific recognition entities. Moreover, we highlight the key role of MIPs in this area and provide examples of their successful use. Finally, we conclude the review with the remaining challenges, future outlook, and emerging opportunities.

A tick saliva serpin, IxsS17 inhibits host innate immune system proteases and enhances host colonization by Lyme disease agent

Lyme disease (LD) caused by Borrelia burgdorferi is among the most important human vector borne diseases for which there is no effective prevention method. Identification of tick saliva transmission factors of the LD agent is needed before the highly advocated tick antigen-based vaccine could be developed. We previously reported the highly conserved Ixodes scapularis (Ixs) tick saliva serpin (S) 17 (IxsS17) was highly secreted by B. burgdorferi infected nymphs. Here, we show that IxsS17 promote tick feeding and enhances B. burgdorferi colonization of the host. We show that IxsS17 is not part of a redundant system, and its functional domain reactive center loop (RCL) is 100% conserved in all tick species. Yeast expressed recombinant (r) IxsS17 inhibits effector proteases of inflammation, blood clotting, and complement innate immune systems. Interestingly, differential precipitation analysis revealed novel functional insights that IxsS17 interacts with both effector proteases and regulatory protease inhibitors. For instance, rIxsS17 interacted with blood clotting proteases, fXII, fX, fXII, plasmin, and plasma kallikrein alongside blood clotting regulatory serpins (antithrombin III and heparin cofactor II). Similarly, rIxsS17 interacted with both complement system serine proteases, C1s, C2, and factor I and the regulatory serpin, plasma protease C1 inhibitor. Consistently, we validated that rIxsS17 dose dependently blocked deposition of the complement membrane attack complex via the lectin complement pathway and protected complement sensitive B. burgdorferi from complement-mediated killing. Likewise, co-inoculating C3H/HeN mice with rIxsS17 and B. burgdorferi significantly enhanced colonization of mouse heart and skin organs in a reverse dose dependent manner. Taken together, our data suggests an important role for IxsS17 in tick feeding and B. burgdorferi colonization of the host.

Label-Free Liquid Chromatography-Mass Spectrometry Quantitation of Relative N- and O-Glycan Concentrations in Human Milk in Japan

Human milk is abundant in carbohydrates and includes human milk oligosaccharides (HMOs) and N/O-glycans conjugated to proteins. HMO compositions and concentrations vary in individuals according to the maternal secretor status based on the fucosyltransferase 2 genotype; however, the profile of N/O-glycans remains uninvestigated because of the analytical complexity. Herein, we applied a label-free chromatography-mass spectrometry (LC-MS) technique to elucidate the variation in the composition and concentration of N/O-glycans in human milk. We used label-free LC-MS to relatively quantify 16 N-glycans and 12 O-glycans in 200 samples of Japanese human milk (1-2 months postpartum) and applied high performance anion exchange chromatography with pulsed amperometric detection to absolutely quantify the concentrations of 11 representative HMOs. Cluster analysis of the quantitative data revealed that O-glycans and several HMOs were classified according to the presence or absence of fucose linked to galactose while N-glycans were classified into a different group from O-glycans and HMOs. O-glycans and HMOs with fucose linked to galactose were more abundant in human milk from secretor mothers than from nonsecretor mothers. Thus, secretor status influenced the composition and concentration of HMOs and O-glycans but not those of N-glycans in human milk.

Noninvasive serum N-glycans associated with ovarian cancer diagnosis and precancerous lesion prediction

BACKGROUND

Ovarian cancer (OC) is one of the most common gynecological tumors with high morbidity and mortality. Altered serum N-glycome has been observed in many diseases, while the association between serum protein N-glycosylation and OC progression remains unclear, particularly for the onset of carcinogenesis from benign neoplasms to cancer.

METHODS

Herein, a mass spectrometry based high-throughput technique was applied to characterize serum N-glycome profile in individuals with healthy controls, benign neoplasms and different stages of OC. To elucidate the alterations of glycan features in OC progression, an orthogonal strategy with lectin-based ELISA was performed.

RESULTS

It was observed that the initiation and development of OC was associated with increased high-mannosylationand agalactosylation, concurrently with decreased total sialylation of serum, each of which gained at least moderately accurate merits. The most important individual N-glycans in each glycan group was H7N2, H3N5 and H5N4S2F1, respectively. Notably, serum N-glycome could be used to accurately discriminate OC patients from benign cohorts, with a comparable or even higher diagnostic score compared to CA125 and HE4. Furthermore, bioinformatics analysis based discriminative model verified the diagnostic performance of serum N-glycome for OC in two independent sets.

CONCLUSIONS

These findings demonstrated the great potential of serum N-glycome for OC diagnosis and precancerous lesion prediction, paving a new way for OC screening and monitoring.

SIRAH Late Harvest: Coarse-Grained Models for Protein Glycosylation

Glycans constitute one of the most complex families of biological molecules. Despite their crucial role in a plethora of biological processes, they remain largely uncharacterized because of their high complexity. Their intrinsic flexibility and the vast variability associated with the many combination possibilities have hampered their experimental determination. Although theoretical methods have proven to be a valid alternative to the study of glycans, the large size associated with polysaccharides, proteoglycans, and glycolipids poses significant challenges to a fully atomistic description of biologically relevant glycoconjugates. On the other hand, the exquisite dependence on hydrogen bonds to determine glycans' structure makes the development of simplified or coarse-grained (CG) representations extremely challenging. This is particularly the case when glycan representations are expected to be compatible with CG force fields that include several molecular types. We introduce a CG representation able to simulate a wide variety of polysaccharides and common glycosylation motifs in proteins, which is fully compatible with the CG SIRAH force field. Examples of application to N-glycosylated proteins, including antibody recognition and calcium-mediated glycan-protein interactions, highlight the versatility of the enlarged set of CG molecules provided by SIRAH.

Glycan Shape, Motions, and Interactions Explored by NMR Spectroscopy

Glycans in the form of oligosaccharides, polysaccharides, and glycoconjugates are ubiquitous in nature, and their structures range from linear assemblies to highly branched and decorated constructs. Solution state NMR spectroscopy facilitates elucidation of preferred conformations and shapes of the saccharides, motions, and dynamic aspects related to processes over time as well as the study of transient interactions with proteins. Identification of intermolecular networks at the atomic level of detail in recognition events by carbohydrate-binding proteins known as lectins, unraveling interactions with antibodies, and revealing substrate scope and action of glycosyl transferases employed for synthesis of oligo- and polysaccharides may efficiently be analyzed by NMR spectroscopy. By utilizing NMR active nuclei present in glycans and derivatives thereof, including isotopically enriched compounds, highly detailed information can be obtained by the experiments. Subsequent analysis may be aided by quantum chemical calculations of NMR parameters, machine learning-based methodologies and artificial intelligence. Interpretation of the results from NMR experiments can be complemented by extensive molecular dynamics simulations to obtain three-dimensional dynamic models, thereby clarifying molecular recognition processes involving the glycans.

Proteome Analysis of Serum Purified Using Solanum tuberosum and Lycopersicon esculentum Lectins

Serum and plasma exhibit a broad dynamic range of protein concentrations, posing challenges for proteome analysis. Various technologies have been developed to reduce this complexity, including high-abundance depletion methods utilizing antibody columns, extracellular vesicle enrichment techniques, and trace protein enrichment using nanobead cocktails. Here, we employed lectins to address this, thereby extending the scope of biomarker discovery in serum or plasma using a novel approach. We enriched serum proteins using 37 different lectins and subjected them to LC-MS/MS analysis with data-independent acquisition. Solanum tuberosum lectin (STL) and Lycopersicon esculentum lectin (LEL) enabled the detection of more serum proteins than the other lectins. STL and LEL bind to N-acetylglucosamine oligomers, emphasizing the significance of capturing these oligomer-binding proteins when analyzing serum trace proteins. Combining STL and LEL proved more effective than using them separately, allowing us to identify over 3000 proteins from serum through single-shot proteome analysis. We applied the STL/LEL trace-protein enrichment method to the sera of systemic lupus erythematosus model mice. This revealed differences in >1300 proteins between the systemic lupus erythematosus model and control mouse sera, underscoring the utility of this method for biomarker discovery.

Utilizing multimodal mass spectrometry imaging for profiling immune cell composition and N-glycosylation across colorectal carcinoma disease progression

Colorectal cancer (CRC) stands as a leading cause of death worldwide, often arising from specific genetic mutations, progressing from pre-cancerous adenomas to adenocarcinomas. Early detection through regular screening can result in a 90% 5-year survival rate for patients. However, unfortunately, only a fraction of CRC cases are identified at pre-invasive stages, allowing progression to occur silently over 10-15 years. The intricate interplay between the immune system and tumor cells within the tumor microenvironment plays a pivotal role in the progression of CRC. Immune cell clusters can either inhibit or facilitate tumor initiation, growth, and metastasis. To gain a better understanding of this relationship, we conducted N-glycomic profiling using matrix-assisted laser desorption-ionization mass spectrometry imaging (MALDI-MSI). We detected nearly 100 N-glycan species across all samples, revealing a shift in N-glycome profiles from normal to cancerous tissues, marked by a decrease in high mannose N-glycans. Further analysis of precancerous to invasive carcinomas showed an increase in pauci-mannose biantennary, and tetraantennary N-glycans with disease progression. Moreover, a distinct stratification in the N-glycome profile was observed between non-mucinous and mucinous CRC tissues, driven by pauci-mannose, high mannose, and bisecting N-glycans. Notably, we identified immune clusters of CD20+ B cells and CD3/CD44+ T cells distinctive and predictive with signature profiles of bisecting and branched N-glycans. These spatial N-glycan profiles offer potential biomarkers and therapeutic targets throughout the progression of CRC.

Changes in tissue protein N-glycosylation and associated molecular signature occur in the human Parkinsonian brain in a region-specific manner

Parkinson's disease (PD) associated state of neuroinflammation due to the aggregation of aberrant proteins is widely reported. One type of post-translational modification involved in protein stability is glycosylation. Here, we aimed to characterize the human Parkinsonian nigro-striatal N-glycome, and related transcriptome/proteome, and its correlation with endoplasmic reticulum (ER) stress and unfolded protein response (UPR), providing a comprehensive characterization of the PD molecular signature. Significant changes were seen upon a PD: a 3% increase in sialylation and 5% increase in fucosylation in both regions, and a 2% increase in oligomannosylated N-glycans in the substantia nigra. In the latter, a decrease in the mRNA expression of sialidases and an upregulation in the UPR pathway were also seen. To show the correlation between these, we also describe a small in vitro study where changes in specific glycosylation trait enzymes (inhibition of sialyltransferases) led to impairments in cell mitochondrial activity, changes in glyco-profile, and upregulation in UPR pathways. This complete characterization of the human nigro-striatal N-glycome provides an insight into the glycomic profile of PD through a transversal approach while combining the other PD "omics" pieces, which can potentially assist in the development of glyco-focused therapeutics.

Hydrophilic Interaction Liquid Chromatography (HILIC) Enrichment of Glycopeptides Using PolyHYDROXYETHYL A

Glycosylation of proteins is an important post-translational modification that plays a role in a wide range of biological processes, including immune response, intercellular signaling, inflammation, and host-pathogen interaction. Abnormal protein glycosylation has been correlated with various diseases. However, the study of protein glycosylation remains challenging due to its low abundance, microheterogeneity of glycosylation sites, and low ionization efficiency. During the past decade, several methods for enrichment and for isolation of glycopeptides from biological samples have been developed and successfully employed in glycoproteomics research. In this chapter, we discuss the sample preparation protocol and the strategies for effectively isolating and enriching glycopeptides from biological samples, using PolyHYDROXYETHYL A as a hydrophilic interaction liquid chromatography (HILIC) enrichment technique.

Analysis of Native and Permethylated N-Glycan Isomers Using MGC-LC-MS Techniques

Glycosylation is an important post-translational modification that affects many critical cellular functions such as adhesion, signaling, protein stability, and function, among others. Abnormal glycosylation has been linked to many diseases. As such, the investigation of glycans and their roles in disease pathway and progression is important. Glycan analysis can be challenging, however, due to such factors as the heterogeneity of glycans and isomers as well as the poor ionization efficiency provided by mass spectrometry analyses. This chapter presents efficient methods that overcome these and other challenges for the analysis of native and permethylated N-glycan isomers in biological samples. Instructions regarding the packing of the MGC column, the N-glycan sample prep, and the LC-MS conditions are also provided.

Modification of N-Linked Glycan Sites in Viral Glycoproteins

Post-translational modification of proteins by the addition of sugar chains, or glycans, is a functionally important hallmark of proteins trafficked through the secretory system. These proteins are termed glycoproteins. Glycans are known to be important for initiating signaling through binding of cell surface receptors, facilitating protein folding, and maintaining protein stability. For pathogens, glycans can also mask vulnerable protein regions from neutralizing antibodies. Thus, there is a need to develop methods to decipher the role of specific glycans attached to proteins in order to understand their biological role. Here, we describe established methods for identifying glycosylated residues and understanding their role in protein synthesis and function using viral glycoproteins as a model.

ER chaperones use a protein folding and quality control glyco-code

N-glycans act as quality control tags by recruiting lectin chaperones to assist protein maturation in the endoplasmic reticulum. The location and composition of N-glycans (glyco-code) are key to the chaperone-selection process. Serpins, a class of serine protease inhibitors, fold non-sequentially to achieve metastable active states. Here, the role of the glyco-code in assuring successful maturation and quality control of two human serpins, alpha-1 antitrypsin (AAT) and antithrombin III (ATIII), is described. We find that AAT, which has glycans near its N terminus, is assisted by early lectin chaperone binding. In contrast, ATIII, which has more C-terminal glycans, is initially helped by BiP and then later by lectin chaperones mediated by UGGT reglucosylation. UGGT action is increased for misfolding-prone disease variants, and these clients are preferentially glucosylated on their most C-terminal glycan. Our study illustrates how serpins utilize N-glycan presence, position, and composition to direct their proper folding, quality control, and trafficking.

Protein glycosylation: bridging maternal-fetal crosstalk during embryo implantation†

Infertility is a challenging health problem that affects 8-15% of couples worldwide. Establishing pregnancy requires successful embryo implantation, but about 85% of unsuccessful pregnancies are due to embryo implantation failure or loss soon after. Factors crucial for successful implantation include invasive blastocysts, receptive endometrium, invasion of trophoblast cells, and regulation of immune tolerance at the maternal-fetal interface. Maternal-fetal crosstalk, which relies heavily on protein-protein interactions, is a critical factor in implantation that involves multiple cellular communication and molecular pathways. Glycosylation, a protein modification process, is closely related to cell growth, adhesion, transport, signal transduction, and recognition. Protein glycosylation plays a crucial role in maternal-fetal crosstalk and can be divided into N-glycosylation and O-glycosylation, which are often terminated by sialylation or fucosylation. This review article examines the role of protein glycosylation in maternal-fetal crosstalk based on two transcriptome datasets from the GEO database (GSE139087 and GSE113790) and existing research, particularly in the context of the mechanism of protein glycosylation and embryo implantation. Dysregulation of protein glycosylation can lead to adverse pregnancy outcomes, such as missed abortion and recurrent spontaneous abortion, underscoring the importance of a thorough understanding of protein glycosylation in the diagnosis and treatment of female reproductive disorders. This knowledge could have significant clinical implications, leading to the development of more effective diagnostic and therapeutic approaches for these conditions.

Pyridinium-Based Strategy for a Bioorthogonal Conjugation-Assisted Purification Method for Profiling Cell Surface Proteome

Cell surface proteins (CSPs) are valuable targets for therapeutic agents, but achieving highly selective CSP enrichment in cellular physiology remains a technical challenge. To address this challenge, we propose a newly developed sulfo-pyridinium ester (SPE) cross-linking probe, followed by two-step imaging and enrichment. The SPE probe showed higher efficiency in labeling proteins than similar NHS esters at the level of cell lysates and demonstrated specificity for Lys in competitive experiments. More importantly, this probe could selectively label the cell membranes in cell imaging with only negligible labeling of the intracellular compartment. Moreover, we successfully performed this strategy on MCF-7 live cells to label 425 unique CSPs from 1162 labeled proteins. Finally, we employed our probe to label the CSPs of insulin-cultured MCF-7, revealing several cell surface targets of key functional biomarkers and insulin-associated pathogenesis. The above results demonstrate that the SPE method provides a promising tool for the selective labeling of cell surface proteins and monitoring transient cell surface events.

Discovery and Visualization of the Hidden Relationships among N-Glycosylation, Disulfide Bonds, and Membrane Topology

Membrane proteins (MPs) are functionally important but structurally complex. In particular, MPs often carry three structural features, i.e., transmembrane domains (TMs), disulfide bonds (SSs), and N-glycosylation (N-GLYCO). All three features have been intensively studied; however, how the three features potentially correlate has been less addressed in the literature. With the growing accuracy from computational prediction, we used publicly available information on SSs and N-GLYCO and analyzed the potential relationships among post-translational modifications (PTMs) and the predicted membrane topology in the human proteome. Our results suggested a very close relationship between SSs and N-GLYCO that behaved similarly, whereas a complementary relation between the TMs and the two PTMs was also revealed, in which the high SS and/or N-GLYCO presence is often accompanied by a low TM occurrence in a protein. Furthermore, the occurrence of SSs and N-GLYCO in a protein heavily relies on the protein length; however, TMs seem not to possess such length dependence. Finally, SSs exhibits larger potential dynamics than N-GLYCO, which is confined by the presence of sequons. The special classes of proteins possessing extreme or unique patterns of the three structural features are comprehensively identified, and their structural features and potential dynamics help to identify their susceptibility to different physiological and pathophysiological insults, which could help drug development and protein engineering.

Glycosylation and Crowded Membrane Effects on Influenza Neuraminidase Stability and Dynamics

All protein simulations are conducted with varying degrees of simplification, oftentimes with unknown ramifications about how these simplifications affect the interpretability of the results. In this work, we investigated how protein glycosylation and lateral crowding effects modulate an array of properties characterizing the stability and dynamics of influenza neuraminidase. We constructed three systems: (1) glycosylated neuraminidase in a whole virion (i.e., crowded membrane) environment, (2) glycosylated neuraminidase in its own lipid bilayer, and (3) unglycosylated neuraminidase in its own lipid bilayer. We saw that glycans tend to stabilize the protein structure and reduce its conformational flexibility while restricting the solvent movement. Conversely, a crowded membrane environment encouraged exploration of the free energy landscape and a large-scale conformational change, while making the protein structure more compact. Understanding these effects informs what factors one must consider in attempting to recapture the desired level of physical accuracy.

Glycan/Protein-Stable Isotope Labeling in Cell Culture for Enabling Concurrent Quantitative Glycomics/Proteomics/Glycoproteomics

The complexity and heterogeneity of protein glycosylation present an analytical challenge to the studies of characterization and quantitation. Various LC-MS-based quantitation strategies have emerged in recent decades. Metabolic stable isotope labeling has been developed to enhance the accurate LC/MS-based quantitation between different cell lines. Stable isotope labeling by amino acids in a cell culture (SILAC) is the most widely used metabolic labeling method in proteomic analysis. However, it can only label the peptide backbone and is thus limited in glycomic studies. Here, we present a metabolic isotope labeling strategy, named GlyProSILC (Glycan Protein Stable Isotope Labeling in Cell Culture), that can label both the glycan motif and peptide backbone from the same batch of cells. It was performed by feeding cells with a heavy medium containing amide-15N-glutamine, 13C6-arginine (Arg6), and 13C6-15N2-lysine (Lys8). No significant change of cell line metabolism after GlyProSILC labeling was observed based on transcriptomic, glycomic, and proteomic data. The labeling conditions, labeling efficiency, and quantitation accuracy were investigated. After quantitation correction, we simultaneously quantified 62 N-glycans, 574 proteins, and 344 glycopeptides using the same batch of mixed 231BR/231 cell lines. So far, GlyProSILC provides an accurate and effective quantitation approach for glycomics, proteomics, and glycoproteomics in a cell culture system.

A Critical Analysis of the FDA's Omics-Driven Pharmacodynamic Biomarkers to Establish Biosimilarity

Demonstrating biosimilarity entails comprehensive analytical assessment, clinical pharmacology profiling, and efficacy testing in patients for at least one medical indication, as required by the U.S. Biologics Price Competition and Innovation Act (BPCIA). The efficacy testing can be waived if the drug has known pharmacodynamic (PD) markers, leaving most therapeutic proteins out of this concession. To overcome this, the FDA suggests that biosimilar developers discover PD biomarkers using omics technologies such as proteomics, glycomics, transcriptomics, genomics, epigenomics, and metabolomics. This approach is redundant since the mode-action-action biomarkers of approved therapeutic proteins are already available, as compiled in this paper for the first time. Other potential biomarkers are receptor binding and pharmacokinetic profiling, which can be made more relevant to ensure biosimilarity without requiring biosimilar developers to conduct extensive research, for which they are rarely qualified.

Polyol recognition in catalysis: toward selective modification of glycosylated polypeptides with boronic acid-rhodium(II) catalysts

Proximity-induced methodologies for peptide and protein modification have been developed using recognition elements like inhibitors, antibodies, or affinity tags on amino acids. However, the recognition of saccharides for chemical modification remains widely unexplored. Studies exploring boronic acids and their derivatives have shown their alluring capabilities as selective molecular recognition elements for saccharides, and in this study we describe the application of these ideas to the discovery of a catalytic proximity-induced methodology for covalent modification of glycopeptides using boronic acids as a saccharide recognition element.

LC-MS/MS Quantitation of HILIC-Enriched N-glycopeptides Derived from Low-Abundance Serum Glycoproteins in Patients with Narcolepsy Type 1

Glycoproteomic analysis is always challenging because of low abundance and complex site-specific heterogeneity. Glycoproteins are involved in various biological processes such as cell signaling, adhesion, and cell-cell communication and may serve as potential biomarkers when analyzing different diseases. Here, we investigate glycoproteins in narcolepsy type 1 (NT1) disease, a form of narcolepsy characterized by cataplexy-the sudden onset of muscle paralysis that is typically triggered by intense emotions. In this study, 27 human blood serum samples were analyzed, 16 from NT1 patients and 11 from healthy individuals serving as controls. We quantified hydrophilic interaction liquid chromatography (HILIC)-enriched glycopeptides from low-abundance serum samples of controls and NT1 patients via LC-MS/MS. Twenty-eight unique N-glycopeptides showed significant changes between the two studied groups. The sialylated N-glycopeptide structures LPTQNITFQTESSVAEQEAEFQSPK HexNAc6, Hex3, Neu5Ac2 (derived from the ITIH4 protein) and the structure IVLDPSGSMNIYLVLDGSDSIGASNFTGAK HexNAc5, Hex4, Fuc1 (derived from the CFB protein), with p values of 0.008 and 0.01, respectively, were elevated in NT1 samples compared with controls. In addition, the N-glycopeptide protein sources Ceruloplasmin, Complement factor B, and ITH4 were observed to play an important role in the complement activation and acute-phase response signaling pathways. This may explain the possible association between the biomarkers and pathophysiological effects.

Beta-1,4-galactosyltransferase-3 deficiency suppresses the growth of immunogenic tumors in mice

Background

Beta-1,4-galactosyltransferase-3 (B4GALT3) belongs to the family of beta-1,4-galactosyltransferases (B4GALTs) and is responsible for the transfer of UDP-galactose to terminal N-acetylglucosamine. B4GALT3 is differentially expressed in tumors and adjacent normal tissues, and is correlated with clinical prognosis in several cancers, including neuroblastoma, cervical cancer, and bladder cancer. However, the exact role of B4GALT3 in the tumor immune microenvironment (TIME) remains unclear. Here, we aimed to elucidate the function of B4GALT3 in the TIME.

Methods

To study the functions of B4GALT3 in cancer immunity, either weakly or strongly immunogenic tumor cells were subcutaneously transplanted into wild-type (WT) and B4galt3 knockout (KO) mice. Bone marrow transplantation and CD8+ T cell depletion experiments were conducted to elucidate the role of immune cells in suppressing tumor growth in B4galt3 KO mice. The cell types and gene expression in the tumor region and infiltrating CD8+ T cells were analyzed using flow cytometry and RNA sequencing. N-glycosylated proteins from WT and B4galt3 KO mice were compared using the liquid chromatography tandem mass spectrometry (LC-MS/MS)-based glycoproteomic approach.

Results

B4galt3 KO mice exhibited suppressed growth of strongly immunogenic tumors with a notable increase in CD8+ T cell infiltration within tumors. Notably, B4galt3 deficiency led to changes in N-glycan modification of several proteins, including integrin alpha L (ITGAL), involved in T cell activity and proliferation. In vitro experiments suggested that B4galt3 KO CD8+ T cells were more susceptible to activation and displayed increased downstream phosphorylation of FAK linked to ITGAL.

Conclusion

Our study demonstrates that B4galt3 deficiency can potentially boost anti-tumor immune responses, largely through enhancing the influx of CD8+ T cells. B4GALT3 might be suppressing cancer immunity by synthesizing the glycan structure of molecules on the CD8+ T cell surface, as evidenced by the changes in the glycan structure of ITGAL in immune cells. Importantly, B4galt3 KO mice showed no adverse effects on growth, development, or reproduction, underscoring the potential of B4GALT3 as a promising and safe therapeutic target for cancer treatment.

Computational design of N-linked glycans for high throughput epitope profiling

Efficient identification of epitopes is crucial for drug discovery and design as it enables the selection of optimal epitopes, expansion of lead antibody diversity, and verification of binding interface. Although high-resolution low throughput methods like x-ray crystallography can determine epitopes or protein-protein interactions accurately, they are time-consuming and can only be applied to a limited number of complexes. To overcome these limitations, we have developed a rapid computational method that incorporates N-linked glycans to mask epitopes or protein interaction surfaces, thereby providing a mapping of these regions. Using human coagulation factor IXa (fIXa) as a model system, we computationally screened 158 positions and expressed 98 variants to test experimentally for epitope mapping. We were able to delineate epitopes rapidly and reliably through the insertion of N-linked glycans that efficiently disrupted binding in a site-selective manner. To validate the efficacy of our method, we conducted ELISA experiments and high-throughput yeast surface display assays. Furthermore, x-ray crystallography was employed to verify the results, thereby recapitulating through the method of N-linked glycans a coarse-grained mapping of the epitope.

Glycosylation and Crowded Membrane Effects on Influenza Neuraminidase Stability and Dynamics

All protein simulations are conducted with varying degrees of simplifications, oftentimes with unknown ramifications on how these simplifications affect the interpretability of the results. In this work we investigated how protein glycosylation and lateral crowding effects modulate an array of properties characterizing the stability and dynamics of influenza neuraminidase. We constructed three systems: 1) Glycosylated neuraminidase in a whole virion (i.e. crowded membrane) environment 2) Glycosylated neuraminidase in its own lipid bilayer 3) Unglycosylated neuraminidase in its own lipid bilayer. We saw that glycans tend to stabilize the protein structure and reduce its conformational flexibility while restricting solvent movement. Conversely, a crowded membrane environment encouraged exploration of the free energy landscape and a large scale conformational change while making the protein structure more compact. Understanding these effects informs what factors one must consider while attempting to recapture the desired level of physical accuracy.

Proximity-inducing modalities: the past, present, and future

Living systems use proximity to regulate biochemical processes. Inspired by this phenomenon, bifunctional modalities that induce proximity have been developed to redirect cellular processes. An emerging example of this class is molecules that induce ubiquitin-dependent proteasomal degradation of a protein of interest, and their initial development sparked a flurry of discovery for other bifunctional modalities. Recent advances in this area include modalities that can change protein phosphorylation, glycosylation, and acetylation states, modulate gene expression, and recruit components of the immune system. In this review, we highlight bifunctional modalities that perform functions other than degradation and have great potential to revolutionize disease treatment, while also serving as important tools in basic research to explore new aspects of biology.

Emerging glyco-risk prediction model to forecast response to immune checkpoint inhibitors in colorectal cancer

BACKGROUND

Aberrant glycosylation is one of the most common post-translational modifications leading to heterogeneity in colorectal cancer (CRC). This study aims to construct a risk prediction model based on glycosyltransferase to forecast the response to immune checkpoint inhibitors in CRC patients.

METHODS

Based on the TCGA dataset and glycosyltransferase genes, the NMF algorithm and WGCNA were used to identify molecular subtypes and co-expressed genes, respectively. Lasso and multivariate COX regression were used to identify prognostic glycosyltransferase genes and construct a glyco-risk prediction model in CRC patients. Univariate and multivariate Cox regression, Kaplan-Meier, and ROC curves were applied to further verify the prognostic performance of the model in CRC patients in the training and validation sets. We compared the responsiveness of immunotherapy and chemotherapy between the two groups. In vitro experiments and clinical specimens verified the specific function of the key glycosyltransferase genes in CRC.

RESULTS

The CRC cohort was divided into two subtypes with prominent differences in survival based on the well-robust seven-gene glyco-risk prediction model (composed of ALG1L2, HAS1, PYGL, COLGALT2, B3GNT4, POFUT2, and GALNT7). The nomograms based on the risk model could predict the prognosis of CRC patients independently of other clinicopathologic characteristics. Our prediction model showed a better overall prediction performance than other models. Compared with the low-risk group, the high-risk CRC patients showed a lower immune infiltration state, but a higher TMB and a lower response to anti-PD-1, anti-PD-L1, and anti-CTLA-4 therapy. Clinical specimen validation showed an obvious difference in the expression of seven glycosyltransferase genes between the low- and high-risk groups. Significant reduction in POFUT2 expression in high-risk groups was associated with reduced N-glycans production.

CONCLUSION

Our study constructed a robust glyco-risk prediction model that could provide direction for immunotherapy and chemotherapy in CRC patients, which could help clinicians make personalized treatment decisions.

Enhanced Detection of Charged N-Glycans in the Brain by Infrared Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometric Imaging

N-linked glycosylation represents a structurally diverse, complex, co- and posttranslational protein modification that bridges metabolism and cellular signaling. Consequently, aberrant protein glycosylation is a hallmark of most pathological scenarios. Due to their complex nature and non-template-driven synthesis, the analysis of glycans is faced with several challenges, underlining the need for new and improved analytical technologies. Spatial profiling of N-glycans through direct imaging on tissue sections reveals the regio-specific and/or disease pathology correlating tissue N-glycans that serve as a disease glycoprint for diagnosis. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is a soft hybrid ionization technique that has been used for diverse mass spectrometry imaging (MSI) applications. Here, we report the first spatial analysis of the brain N-linked glycans by IR-MALDESI MSI, leading to a significant increase in the detection of the brain N-sialoglycans. A formalin-fixed paraffin-embedded mouse brain tissue was analyzed in negative ionization mode after tissue washing, antigen retrieval, and pneumatic application of PNGase F for enzymatic digestion of N-linked glycans. We report a comparative analysis of section thickness on the N-glycan detection using IR-MALDESI. One hundred thirty-six unique N-linked glycans were confidently identified in the brain tissue (with an additional 132 unique N-glycans, not reported in GlyConnect), where more than 50% contained sialic acid residues, which is approximately 3-fold higher than the previous reports. This work demonstrates the first application of IR-MALDESI in N-linked glycan imaging of the brain tissue, leading to a 2.5-fold increase in the in situ total brain N-glycan detection compared to the current gold standard of positive-mode matrix-assisted laser desorption/ionization mass spectrometry imaging. This is also the first report of the application of the MSI toward the identification of sulfoglycans in the rodent brain. Overall, IR-MALDESI-MSI presents a sensitive glycan detection platform to identify tissue-specific and/or disease-specific glycosignature in the brain while preserving the sialoglycans without any chemical derivatization.

Development of an Antibody-Based Platform for the Analysis of Immune Cell-Specific N-linked Glycosylation

N-linked glycosylation plays an important role in both the innate and adaptive immune response through the modulation of cell surface receptors as well as general cell-to-cell interactions. The study of immune cell N-glycosylation is gaining interest but is hindered by the complexity of cell-type-specific N-glycan analysis. Analytical techniques such as chromatography, LC-MS/MS, and the use of lectins are all currently used to analyze cellular glycosylation. Issues with these analytical techniques include poor throughput, which is often limited to a single sample at a time, lack of structural information, the need for a large amount of starting materials, and the requirement for cell purification, thereby reducing their feasibility for N-glycan study. Here, we report the development of a rapid antibody array-based approach for the capture of specific nonadherent immune cells coupled with MALDI-IMS to analyze cellular N-glycosylation. This workflow is adaptable to multiple N-glycan imaging approaches such as the removal or stabilization and derivatization of terminal sialic acid residues providing unique avenues of analysis that have otherwise not been explored in immune cell populations. The reproducibility, sensitivity, and versatility of this assay provide an invaluable tool for researchers and clinical applications, significantly expanding the field of glycoimmunology.

Dynamic profiling of medulloblastoma surfaceome

Medulloblastoma (MB) is the most common type of malignant pediatric brain cancer. The current standard of care (SOC) involves maximal safe resection and chemoradiotherapy in individuals older than 3 years, often leading to devastating neurocognitive and developmental deficits. Out of the four distinct molecular subgroups, Group 3 and 4 have the poorest patient outcomes due to the aggressive nature of the tumor and propensity to metastasize and recur post therapy. The toxicity of the SOC and lack of response in specific subtypes to the SOC underscores the urgent need for developing and translating novel treatment options including immunotherapies. To identify differentially enriched surface proteins that could be evaluated for potential future immunotherapeutic interventions, we leveraged N-glycocapture surfaceome profiling on Group 3 MB cells from primary tumor, through therapy, to recurrence using our established therapy-adapted patient derived xenograft model. Integrin 𝛼5 (ITGA5) was one of the most differentially enriched targets found at recurrence when compared to engraftment and untreated timepoints. In addition to being enriched at recurrence, shRNA-mediated knockdown and small molecule inhibition of ITGA5 have resulted in marked decrease in proliferation and self-renewal in vitro and demonstrated a survival advantage in vivo. Together, our data highlights the value of dynamic profiling of cells as they evolve through therapy and the identification of ITGA5 as a promising therapeutic target for recurrent Group 3 MB.

Warning Signs From the Crypt: Aberrant Protein Glycosylation Marks Opportunities for Early Colorectal Cancer Detection

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths despite being the most preventable and treatable forms of cancer when caught early through screening. There is an unmet need for novel screening approaches with improved accuracy, less invasiveness, and reduced costs. In recent years, evidence has accumulated around particular biological events that happen during the adenoma-to-carcinoma transition, especially focusing on precancerous immune responses in the colonic crypt. Protein glycosylation plays a central role in driving those responses, and recently, numerous reports have been published on how aberrant protein glycosylation both in colonic tissue and on circulating glycoproteins reflects these precancerous developments. The complex field of glycosylation, which exceeds complexity of proteins by several orders of magnitude, can now be studied primarily because of the availability of new high-throughput technologies such as mass spectrometry and artificial intelligence-powered data processing. This has now opened new avenues for studying novel biomarkers for CRC screening. This review summarizes the early events taking place from the normal colon mucosa toward adenoma and adenocarcinoma formation and associated critical protein glycosylation phenomena, both on the tissue level and in the circulation. These insights will help establish an understanding in the interpretation of novel CRC detection modalities that involve high-throughput glycomics.

Glycans as Potential Diagnostic Markers of Traumatic Brain Injury in Children

Diagnosing mild traumatic brain injury (TBI) in the acute setting is challenging due to the nonspecific and often transient or delayed symptoms. Further, the criteria for acute head imaging are frequently not fulfilled, which may lead to a missed diagnosis. A rapid test to diagnose TBI using body fluids would be highly useful. Urine and saliva samples were collected from 28 pediatric patients (mean [SD] age, eight years two months [four years three months]) with acute, clinically diagnosed mild TBI and 30 healthy volunteers at Satasairaala Hospital, Pori, Finland, over 11 months. The mean (SD) time from trauma to first sampling was 3 h 56 min (1 h 14 min). Samples were analyzed to determine the number of lectin-binding glycan molecules, indicating nerve tissue damage. The relative levels of several lectin-bound glycans were measured by fluorescence. Compared with healthy controls, the TBI group showed significant increases (p < 0.05, Wilcoxon rank-sum two-sided test) in nine glycans in the saliva, one glycan in the urine, and a significant decrease in seven glycans in the urine. These findings of potentially diagnostic glycans in body fluids after TBI warrant further research and may enable the development of a rapid body fluid-based point-of-care test to identify pediatric patients with TBI after a head injury.

Deciphering Protein O-GalNAcylation: Method Development and Disease Implication

Mucin-type O-glycosylation is an important protein post-translational modification that is abundantly expressed on cell surface proteins. Protein O-glycosylation plays a variety of roles in cellular biological functions including protein structure and signal transduction to the immune response. Cell surface mucins are highly O-glycosylated and are the main substance of the mucosal barrier that protects the gastrointestinal or respiratory tract from infection by pathogens or microorganisms. Dysregulation of mucin O-glycosylation may impair mucosal protection against pathogens that can invade cells to trigger infection or immune evasion. Truncated O-glycosylation, also known as Tn antigen or O-GalNAcylation, is highly upregulated in diseases such cancer, autoimmune disorders, neurodegenerative diseases, and IgA nephropathy. Characterization of O-GalNAcylation helps decipher the role of Tn antigen in physiopathology and therapy. However, the analysis of O-glycosylation, specifically the Tn antigen, remains challenging due to the lack of reliable enrichment and identification assays compared to N-glycosylation. Here, we summarize recent advances in analytical methods for O-GalNAcylation enrichment and identification and highlight the biological role of the Tn antigen in various diseases and the clinical implications of identifying aberrant O-GalNAcylation.

Application of bioanalytical and computational methods in decoding the roles of glycans in host-pathogen interactions

Host-pathogen interactions (HPIs) are complex processes that require tight regulation. A common regulatory mechanism of HPIs is through glycans of either host cells or pathogens. Due to their diverse sequences, complex structures, and conformations, studies of glycans require highly sensitive and powerful tools. Recent improvements in technology have enabled the application of many bioanalytical techniques and modeling methods to investigate glycans and their mechanisms in HPIs. This mini-review highlights how these advances have been used to understand the role glycans play in HPIs in the past 2 years.

Not-So-Sweet Dreams: Plasma and IgG N-Glycome in the Severe Form of the Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a prevalent disease associated with increased risk for cardiovascular and metabolic diseases and shortened lifespan. The aim of this study was to explore the possibility of using N-glycome as a biomarker for the severe form of OSA. Seventy subjects who underwent a whole-night polysomnography/polygraphy and had apnea-hypopnea index (AHI) over 30 were compared to 23 controls (AHI under 5). Plasma samples were used to extract 39 glycan peaks using ultra-high-performance liquid chromatography (UPLC) and 27 IgG peaks using capillary gel electrophoresis (CGE). We also measured glycan age, a molecular proxy for biological aging. Three plasma and one IgG peaks were significant in a multivariate model controlling for the effects of age, sex, and body mass index. These included decreased GP24 (disialylated triantennary glycans as major structure) and GP28 (trigalactosylated, triantennary, disialylated, and trisialylated glycans), and increased GP32 (trisialylated triantennary glycan). Only one IgG glycan peak was significantly increased (P26), which contains biantennary digalactosylated glycans with core fucose. Patients with severe OSA exhibited accelerated biological aging, with a median of 6.9 years more than their chronological age (p < 0.001). Plasma N-glycome can be used as a biomarker for severe OSA.

N-glycosylomic analysis provides new insight into the molecular mechanism of firmness of fish fillet

Post-translational protein modification affects muscle physiochemistry. To understand the roles of N-glycosylation in this process, the muscle N-glycoproteomes of crisp grass carp (CGC) and ordinary grass carp (GC) were analyzed and compared. We identified 325 N-glycosylated sites with the NxT motif, classified 177 proteins, and identified 10 upregulated and 19 downregulated differentially glycosylated proteins (DGPs). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes annotations revealed that these DGPs participate in myogenesis, extracellular matrix content formation, and muscle function. The DGPs partially accounted for the molecular mechanisms associated with the relatively smaller fiber diameter and higher collagen content observed in CGC. Though the DGPs diverged from the identified differentially phosphorylated proteins and differentially expressed proteins detected in previous study, they all shared similar metabolic and signaling pathways. Thus, they might independently alter fish muscle texture. Overall, the present study provides novel insights into the mechanisms underlying fillet quality.

Mining glycosylation-related prognostic lncRNAs and constructing a prognostic model for overall survival prediction in glioma: A study based on bioinformatics analysis

Dysregulation of protein glycosylation plays a crucial role in the development of glioma. Long noncoding RNA (lncRNAs), functional RNA molecules without protein-coding ability, regulate gene expression and participate in malignant glioma progression. However, it remains unclear how lncRNAs are involved in glycosylation glioma malignancy. Identification of prognostic glycosylation-related lncRNAs in gliomas is necessary. We collected RNA-seq data and clinicopathological information of glioma patients from the cancer genome atlas and Chinese glioma genome atlas. We used the "limma" package to explore glycosylation-related gene and screened related lncRNAs from abnormally glycosylated genes. Using univariate Cox analyses Regression and least absolute shrinkage and selection operator analyses, we constructed a risk signature with 7 glycosylation-related lncRNAs. Based on the median risk score (RS), patients with gliomas were divided into low- and high-risk subgroups with different overall survival rates. Univariate and multivariate Cox analyses regression analyses were performed to assess the independent prognostic ability of the RS. Twenty glycosylation-related lncRNAs were identified by univariate Cox regression analyses. Two glioma subgroups were identified using consistent protein clustering, with the prognosis of the former being better than that of the latter. Least absolute shrinkage and selection operator analysis identified 7 survival RSs for glycosylation-related lncRNAs, which were identified as independent prognostic markers and predictors of glioma clinicopathological features. Glycosylation-related lncRNAs play an important role in the malignant development of gliomas and may help guide treatment options.

Advances in protein glycosylation and its role in tissue repair and regeneration

After tissue damage, a series of molecular and cellular events are initiated to promote tissue repair and regeneration to restore its original structure and function. These events include inter-cell communication, cell proliferation, cell migration, extracellular matrix differentiation, and other critical biological processes. Glycosylation is the crucial conservative and universal post-translational modification in all eukaryotic cells [1], with influential roles in intercellular recognition, regulation, signaling, immune response, cellular transformation, and disease development. Studies have shown that abnormally glycosylation of proteins is a well-recognized feature of cancer cells, and specific glycan structures are considered markers of tumor development. There are many studies on gene expression and regulation during tissue repair and regeneration. Still, there needs to be more knowledge of complex carbohydrates' effects on tissue repair and regeneration, such as glycosylation. Here, we present a review of studies investigating protein glycosylation in the tissue repair and regeneration process.

Unlocking the magic in mycelium: Using synthetic biology to optimize filamentous fungi for biomanufacturing and sustainability

Filamentous fungi drive carbon and nutrient cycling across our global ecosystems, through its interactions with growing and decaying flora and their constituent microbiomes. The remarkable metabolic diversity, secretion ability, and fiber-like mycelial structure that have evolved in filamentous fungi have been increasingly exploited in commercial operations. The industrial potential of mycelial fermentation ranges from the discovery and bioproduction of enzymes and bioactive compounds, the decarbonization of food and material production, to environmental remediation and enhanced agricultural production. Despite its fundamental impact in ecology and biotechnology, molds and mushrooms have not, to-date, significantly intersected with synthetic biology in ways comparable to other industrial cell factories (e.g. Escherichia coli,Saccharomyces cerevisiae, and Komagataella phaffii). In this review, we summarize a suite of synthetic biology and computational tools for the mining, engineering and optimization of filamentous fungi as a bioproduction chassis. A combination of methods across genetic engineering, mutagenesis, experimental evolution, and computational modeling can be used to address strain development bottlenecks in established and emerging industries. These include slow mycelium growth rate, low production yields, non-optimal growth in alternative feedstocks, and difficulties in downstream purification. In the scope of biomanufacturing, we then detail previous efforts in improving key bottlenecks by targeting protein processing and secretion pathways, hyphae morphogenesis, and transcriptional control. Bringing synthetic biology practices into the hidden world of molds and mushrooms will serve to expand the limited panel of host organisms that allow for commercially-feasible and environmentally-sustainable bioproduction of enzymes, chemicals, therapeutics, foods, and materials of the future.