Discovery of novel differentiation markers in the early stage of chondrogenesis by glycoform-focused reverse proteomics and genomics

Glycosphingolipids in Osteoarthritis and Cartilage-Regeneration Therapy: Mechanisms and Therapeutic Prospects Based on a Narrative Review of the Literature

Glycosphingolipids (GSLs), a subtype of glycolipids containing sphingosine, are critical components of vertebrate plasma membranes, playing a pivotal role in cellular signaling and interactions. In human articular cartilage in osteoarthritis (OA), GSL expression is known notably to decrease. This review focuses on the roles of gangliosides, a specific type of GSL, in cartilage degeneration and regeneration, emphasizing their regulatory function in signal transduction. The expression of gangliosides, whether endogenous or augmented exogenously, is regulated at the enzymatic level, targeting specific glycosyltransferases. This regulation has significant implications for the composition of cell-surface gangliosides and their impact on signal transduction in chondrocytes and progenitor cells. Different levels of ganglioside expression can influence signaling pathways in various ways, potentially affecting cell properties, including malignancy. Moreover, gene manipulations against gangliosides have been shown to regulate cartilage metabolisms and chondrocyte differentiation in vivo and in vitro. This review highlights the potential of targeting gangliosides in the development of therapeutic strategies for osteoarthritis and cartilage injury and addresses promising directions for future research and treatment.

Analysis of N-glycosylation protein of Kashin-Beck disease chondrocytes derived from induced pluripotent stem cells based on label-free strategies with LC-MS/MS

We aimed to compare N-glycosylation proteins in Kashin-Beck disease (KBD) chondrocytes and normal chondrocytes derived from induced pluripotent stem cells (iPSCs). KBD and normal iPSCs were reprogrammed from human KBD and normal dermal fibroblasts, respectively. Subsequently, chondrocytes were differentiated from KBD and normal iPSCs separately. Immunofluorescence was utilized to assay the protein markers of iPSCs and chondrocytes. Differential N-glycosylation proteins were screened using label-free strategies with LC-MS/MS. Bioinformatics analyses were utilized to interpret the functions of differential N-glycosylation proteins. Immunofluorescence staining revealed that both KBD-iPSCs and normal-iPSCs strongly expressed pluripotency markers OCT4 and NANOG. Meanwhile, chondrocyte markers collagen II and SOX9 are presented in KBD-iPSC-chondrocytes and normal-iPSC-chondrocytes. We obtained 87 differential N-glycosylation sites which corresponded to 68 differential proteins, which were constructed into 1 cluster. We obtained collagen type I trimer and 9 other biological processes; polysaccharide binding and 9 other molecular functions; regulation of transcription by RNA polymerase II and 9 other cellular components from GO; the Pl3K-Akt signaling pathway and 9 other KEGG pathways; peroxisome and 7 other subcellular locations; and integrin alpha chain, C-terminal cytoplasmic region, conserved site and 9 other classifications of domain annotations, and 2 networks. FGFR3 and LRP1 are expressed at higher levels in KBD-iPSC-chondrocytes, while the expressions of COL2A1, TIMP1, UNC5B, NOG, LEPR, and ITGA1 were down-regulated in KBD-iPSC-chondrocytes. The differential expressions of these N-glycosylation proteins may lead to the abnormal function of KBD chondrocytes.

Mouse tissue glycome atlas 2022 highlights inter-organ variation in major N-glycan profiles

This study presents "mouse tissue glycome atlas" representing the profiles of major N-glycans of mouse glycoproteins that may define their essential functions in the surface glycocalyx of mouse organs/tissues and serum-derived extracellular vesicles (exosomes). Cell surface glycocalyx composed of a variety of N-glycans attached covalently to the membrane proteins, notably characteristic "N-glycosylation patterns" of the glycocalyx, plays a critical role for the regulation of cell differentiation, cell adhesion, homeostatic immune response, and biodistribution of secreted exosomes. Given that the integrity of cell surface glycocalyx correlates significantly with maintenance of the cellular morphology and homeostatic immune functions, dynamic alterations of N-glycosylation patterns in the normal glycocalyx caused by cellular abnormalities may serve as highly sensitive and promising biomarkers. Although it is believed that inter-organs variations in N-glycosylation patterns exist, information of the glycan diversity in mouse organs/tissues remains to be elusive. Here we communicate for the first-time N-glycosylation patterns of 16 mouse organs/tissues, serum, and serum-derived exosomes of Slc:ddY mice using an established solid-phase glycoblotting platform for the rapid, easy, and high throughput MALDI-TOFMS-based quantitative glycomics. The present results elicited occurrence of the organ/tissue-characteristic N-glycosylation patterns that can be discriminated to each other. Basic machine learning analysis using this N-glycome dataset enabled classification between 16 mouse organs/tissues with the highest F1 score (69.7-100%) when neural network algorithm was used. A preliminary examination demonstrated that machine learning analysis of mouse lung N-glycome dataset by random forest algorithm allows for the discrimination of lungs among the different mouse strains such as the outbred mouse Slc:ddY, inbred mouse DBA/2Crslc, and systemic lupus erythematosus model mouse MRL-lpr/lpr with the highest F1 score (74.5-83.8%). Our results strongly implicate importance of "human organ/tissue glycome atlas" for understanding the crucial and diversified roles of glycocalyx determined by the organ/tissue-characteristic N-glycosylation patterns and the discovery research for N-glycome-based disease-specific biomarkers and therapeutic targets.

Effectiveness of Selenium on Chondrocyte Glycoprotein Glycosylation Which Play Important Roles in the Pathogenesis of an Endemic Osteoarthritis, Kashin-Beck Disease

In this study, we aimed to explore the effectiveness of selenium on the chondrocyte glycoprotein glycosylation which plays important roles in the pathogenesis of Kashin-Beck disease (KBD). Cartilage samples were collected from KBD patients after total knee replacement surgery. Chondrocytes were cultured with sodium selenium. The group of chondrocytes which were cultured without adding sodium selenium was considered as control group. Lectin microarray was used to screen the differences in lectin levels between KBD and KBD with selenium groups. Stronger signals for Bandeiraea simplicifolia (BS-I), Hippeastrum hybrid lectin (HHL), Pisum sativum agglutinin (PSA), Psophocarpus tetragonolobus lectin I (PTL-I), Psophocarpus tetragonolobus lectin II (PTL-II), Sophora japonica agglutinin (SJA), Lotus tetragonolobus lectin (LTL), and Triticum vulgaris (WGA) were observed in the KBD group. Meanwhile, Aleuria aurantia lectin (AAL), Lens culinaris agglutinin (LCA), Lycopersicon esculentum (tomato) lectin (LEL), Peanut agglutinin (PNA), and Sambucus nigra lectin (SNA) signals were lower in the KBD group. Selenium may have the function of influence the expression levels of carbohydrate chains Galα1,3-Gal, high mannose, and GlcNAc.

Alterations of Glycosphingolipid Glycans and Chondrogenic Markers during Differentiation of Human Induced Pluripotent Stem Cells into Chondrocytes

Due to the limited intrinsic healing potential of cartilage, injury to this tissue may lead to osteoarthritis. Human induced pluripotent stem cells (iPSCs), which can be differentiated into chondrocytes, are a promising source of cells for cartilage regenerative therapy. Currently, however, the methods for evaluating chondrogenic differentiation of iPSCs are very limited; the main techniques are based on the detection of chondrogenic genes and histological analysis of the extracellular matrix. The cell surface is coated with glycocalyx, a layer of glycoconjugates including glycosphingolipids (GSLs) and glycoproteins. The glycans in glycoconjugates play important roles in biological events, and their expression and structure vary widely depending on cell types and conditions. In this study, we performed a quantitative GSL-glycan analysis of human iPSCs, iPSC-derived mesenchymal stem cell like cells (iPS-MSC like cells), iPS-MSC-derived chondrocytes (iPS-MSC-CDs), bone marrow-derived mesenchymal stem cells (BMSCs), and BMSC-derived chondrocytes (BMSC-CDs) using glycoblotting technology. We found that GSL-glycan profiles differed among cell types, and that the GSL-glycome underwent a characteristic alteration during the process of chondrogenic differentiation. Furthermore, we analyzed the GSL-glycome of normal human cartilage and found that it was quite similar to that of iPS-MSC-CDs. This is the first study to evaluate GSL-glycan structures on human iPS-derived cartilaginous particles under micromass culture conditions and those of normal human cartilage. Our results indicate that GSL-glycome analysis is useful for evaluating target cell differentiation and can thus support safe regenerative medicine.

Roles of glycoprotein glycosylation in the pathogenesis of an endemic osteoarthritis, Kashin–Beck disease, and effectiveness evaluation of sodium hyaluronate treatment

Background/aim

We aimed to explore the roles of glycoprotein glycosylation in the pathogenesis of Kashin–Beck disease (KBD), and evaluated the effectiveness of sodium hyaluronate treatment.

Materials and methods

Blood and saliva were collected from KBD patients before and after the injection of sodium hyaluronate. Normal healthy subjects were included as controls. Saliva and serum lectin microarrays and saliva and serum microarray verifications were used to screen and confirm the differences in lectin levels among the three groups.

Results

In saliva lectin microarray, bindings to Sophora japonica agglutinin (SJA), Griffonia (Bandeiraea) simplicifolia lectin I (GSL-I), Euonymus europaeus lectin (EEL), Maackia amurensis lectin II (MAL-II), Sambucus nigra lectin (SNA), Hippeastrum hybrid lectin (HHL), and Aleuria aurantia lectin (AAL) were higher in the untreated KBD patients than in the control group. Increased levels of HHL, MAL-II, and GSL-I in the untreated KBD patients discriminated them in particular from the treated ones. Jacalin was lower in the untreated KBD patients compared to the treated KBD and control groups. In serum lectin microarray, HHL and peanut agglutinin (PNA) were increased in the untreated KBD group in comparison to the control one. AAL, Phaseolus vulgaris agglutinin (E+L) (PHA-E+L), and Psophocarpus tetragonolobus lectin I (PTL-I) were lower in the untreated KBD patients compared to the treated KBD and control groups. Hyaluronate treatment appeared to normalize SNA, AAL, and MAL-II levels in saliva, and HHL, PNA, AAL, PTL-I, and PHA-E+L levels in serum. Saliva reversed microarray verification confirmed significant differences between the groups in SNA and Jacalin, in particular for GSL-I levels, while serum reversed microarray verification indicated that HHL, PNA, and AAL levels returned to normal levels after the hyaluronate treatment. Lectin blot confirmed significant differences in HHL, AAL, and Jacalin in saliva, and HHL, PNA, PHA-E+L, and AAL in serum.

Conclusion

HHL in saliva and serum may be a valuable diagnostic biomarker of KBD, and it may be used as follow-up for the hyaluronate treatment.

Molecular Insights Into Lysyl Oxidases in Cartilage Regeneration and Rejuvenation

Articular cartilage remains among the most difficult tissues to regenerate due to its poor self-repair capacity. The lysyl oxidase family (LOX; also termed as protein-lysine 6-oxidase), mainly consists of lysyl oxidase (LO) and lysyl oxidase-like 1-4 (LOXL1-LOXL4), has been traditionally defined as cuproenzymes that are essential for stabilization of extracellular matrix, particularly cross-linking of collagen and elastin. LOX is essential in the musculoskeletal system, particularly cartilage. LOXs-mediated collagen cross-links are essential for the functional integrity of articular cartilage. Appropriate modulation of the expression or activity of certain LOX members selectively may become potential promising strategy for cartilage repair. In the current review, we summarized the advances of LOX in cartilage homeostasis and functioning, as well as copper-mediated activation of LOX through hypoxia-responsive signaling axis during recent decades. Also, the molecular signaling network governing LOX expression has been summarized, indicating that appropriate modulation of hypoxia-responsive-signaling-directed LOX expression through manipulation of bioavailability of copper and oxygen is promising for further clinical implications of cartilage regeneration, which has emerged as a potential therapeutic approach for cartilage rejuvenation in tissue engineering and regenerative medicine. Therefore, targeted regulation of copper-mediated hypoxia-responsive signalling axis for selective modulation of LOX expression may become potential effective therapeutics for enhanced cartilage regeneration and rejuvenation in future clinical implications.

Alteration of the Total Cellular Glycome during Late Differentiation of Chondrocytes

In normal articular cartilage, chondrocytes do not readily proliferate or terminally differentiate, and exhibit a low level of metabolism. Hypertrophy-like changes of chondrocytes have been proposed to play a role in the pathogenesis of osteoarthritis by inducing protease-mediated cartilage degradation and calcification; however, the molecular mechanisms underlying these changes are unclear. Glycans are located on the outermost cell surface. Dynamic cellular differentiation can be monitored and quantitatively characterized by profiling the glycan structures of total cellular glycoproteins. This study aimed to clarify the alterations in glycans upon late differentiation of chondrocytes, during which hypertrophy-like changes occur. Primary mouse chondrocytes were differentiated using an insulin-induced chondro-osteogenic differentiation model. Comprehensive glycomics, including N-glycans, O-glycans, free oligosaccharides, glycosaminoglycan, and glycosphingolipid, were analyzed for the chondrocytes after 0-, 10- and 20-days cultivation. The comparison and clustering of the alteration of glycans upon hypertrophy-like changes of primary chondrocytes were performed. Comprehensive glycomic analyses provided complementary alterations in the levels of various glycans derived from glycoconjugates during hypertrophic differentiation. In addition, expression of genes related to glycan biosynthesis and metabolic processes was significantly correlated with glycan alterations. Our results indicate that total cellular glycan alterations are closely associated with chondrocyte hypertrophy and help to describe the glycophenotype by chondrocytes and their hypertrophic differentiation. our results will assist the identification of diagnostic and differentiation biomarkers in the future.

Proteome analysis of human mesenchymal stem cells undergoing chondrogenesis when exposed to the products of various magnesium-based materials degradation

Treatment of physeal fractures (15%–30% of all paediatric fractures) remains a challenge as in approximately 10% of the cases, significant growth disturbance may occur. Bioresorbable Magnesium-based implants represent a strategy to minimize damage (i.e., load support until bone healing without second surgery). Nevertheless, the absence of harmful effects of magnesium-implants and their degradation products on the growth plate should be confirmed. Here, the proteome of human mesenchymal stem cells undergoing chondrogenesis was evaluated when exposed to the products of various Magnesium-based materials degradation. The results of this study indicate that the materials induced regulation of proteins associated with cell chondrogenesis and cartilage formation, which should be beneficial for cartilage regeneration.

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Degradation products from Mg-based materials generated changes in protein expression.

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Relevant proteins involved in cartilage formation were upregulated.

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Potential application of especially Pure-Mg and Mg-10Gd for cartilage regeneration.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

MALDI mass spectrometry imaging of N-glycans on tibial cartilage and subchondral bone proteins in knee osteoarthritis

Magnetic resonance imaging (MRI) is a non-invasive technique routinely used to investigate pathological changes in knee osteoarthritis (OA) patients. MRI uniquely reveals zones of the most severe change in the subchondral bone (SCB) in OA, called bone marrow lesions (BMLs). BMLs have diagnostic and prognostic significance in OA, but MRI does not provide a molecular understanding of BMLs. Multiple N-glycan structures have been observed to play a pivotal role in the OA disease process. We applied matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) of N-glycans to formalin-fixed paraffin-embedded (FFPE) SCB tissue sections from patients with knee OA, and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) was conducted on consecutive sections to structurally characterize and correlate with the N-glycans seen by MALDI-MSI. The application of this novel MALDI-MSI protocol has enabled the first steps to spatially investigate the N-glycome in the SCB of knee OA patients.

Aquaporin 1 and 5 expression decreases during human intervertebral disc degeneration: Novel HIF-1-mediated regulation of aquaporins in NP cells

Objectives of this study were to investigate whether AQP1 and AQP5 expression is altered during intervertebral disc degeneration and if hypoxia and HIF-1 regulate their expression in NP cells. AQP expression was measured in human tissues from different degenerative grades; regulation by hypoxia and HIF-1 was studied using promoter analysis and gain- and loss-of-function experiments. We show that both AQPs are expressed in the disc and that mRNA and protein levels decline with human disease severity. Bioinformatic analyses of AQP promoters showed multiple evolutionarily conserved HREs. Surprisingly, hypoxia failed to induce promoter activity or expression of either AQP. While genomic chromatin immunoprecipitation showed limited binding of HIF-1α to conserved HREs, their mutation did not suppress promoter activities. Stable HIF-1α suppression significantly decreased mRNA and protein levels of both AQPs, but HIF-1α failed to induce AQP levels following accumulation. Together, our results demonstrate that AQP1 and AQP5 expression is sensitive to human disc degeneration and that HIF-1α uniquely maintains basal expression of both AQPs in NP cells, independent of oxemic tension and HIF-1 binding to promoter HREs. Diminished HIF-1 activity during degeneration may suppress AQP levels in NP cells, compromising their ability to respond to extracellular osmolarity changes.

Glycoblotting method allows for rapid and efficient glycome profiling of human Alzheimer's disease brain, serum and cerebrospinal fluid towards potential biomarker discovery

BACKGROUND

Understanding of the significance of posttranslational glycosylation in Alzheimer's disease (AD) is of growing importance for the investigation of the pathogenesis of AD as well as discovery research of the disease-specific serum biomarkers.

METHODS

We designed a standard protocol for the glycoblotting combined with MALDI-TOFMS to perform rapid and quantitative profiling of the glycan parts of glycoproteins (N-glycans) and glycosphingolipids (GSLs) using human AD's post-mortem samples such as brain tissues (dissected cerebral cortices such as frontal, parietal, occipital, and temporal domains), serum and cerebrospinal fluid (CSF).

RESULTS

The structural profiles of the major N-glycans released from glycoproteins and the total expression levels of the glycans were found to be mostly similar between the brain tissues of the AD patients and those of the normal control group. In contrast, the expression levels of the serum and CSF protein N-glycans such as bisect-type and multiply branched glycoforms were increased significantly in AD patient group. In addition, the levels of some gangliosides such as GM1, GM2 and GM3 appeared to alter in the AD patient brain and serum samples when compared with the normal control groups.

CONCLUSION

Alteration of the expression levels of major N- and GSL-glycans in human brain tissues, serum and CSF of AD patients can be monitored quantitatively by means of the glycoblotting-based standard protocols.

GENERAL SIGNIFICANCE

The changes in the expression levels of the glycans derived from the human post-mortem samples uncovered by the standardized glycoblotting method provides potential serum biomarkers in central nervous system disorders and can contribute to the insight into the molecular mechanisms in the pathogenesis of neurodegenerative diseases and future drug discovery. Most importantly, the present preliminary trials using human post-mortem samples of AD patients suggest that large-scale serum glycomics cohort by means of various-types of human AD patients as well as the normal control sera can facilitate the discovery research of highly sensitive and reliable serum biomarkers for an early diagnosis of AD. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.

Proteomic Analysis of Mesenchymal Stem Cells

Mesenchymal stem or stromal cells (MSCs) are of great interest in biomedical sciences and disease treatment because of their multipotency and wide range of applications for tissue repair and suppression of the immune system. Proteomic analysis of these unique cells has contributed to the identification of important pathways utilized by MSCs to differentiate into distinct tissues as well as important proteins responsible for their special function in vivo and in vitro. However, comparison of proteomic studies in MSCs still suffers from the heterogeneity of MSC preparations. In addition, as proteomics technology advances, several studies can be revisited in order to increase the depth of analysis and, therefore, elucidate more refined mechanisms involved in MSC functionalities. Here, we present detailed protocols to obtain MSCs, as well as protocols to perform in-depth profiling and quantification of alterations in MSC proteomes.

Large-Scale Glycomics of Livestock: Discovery of Highly Sensitive Serum Biomarkers Indicating an Environmental Stress Affecting Immune Responses and Productivity of Holstein Dairy Cows

Because various stresses strongly influence the food productivity of livestock, biomarkers to indicate unmeasurable environmental stress in domestic animals are of increasing importance. Thermal comfort is one of the basic principles of dairy cow welfare that enhances productivity. To discover sensitive biomarkers that monitor such environmental stresses in dairy cows, we herein performed, for the first time, large-scale glycomics on 336 lactating Holstein cow serum samples over 9 months between February and October. Glycoblotting combined with MALDI-TOF/MS and DMB/HPLC allowed for comprehensive glycomics of whole serum glycoproteins. The results obtained revealed seasonal alterations in serum N-glycan levels and their structural characteristics, such as an increase in high-mannose type N-glycans in spring, the occurrence of di/triantennary complex type N-glycans terminating with two or three Neu5Gc residues in summer and autumn, and N-glycans in winter dominantly displaying Neu5Ac. A multivariate analysis revealed a correlation between the serum expression levels of these season-specific glycoforms and productivity.

Cells and secretome--towards endogenous cell re-activation for cartilage repair

Regenerative medicine approaches to cartilage tissue repair have mainly been concerned with the implantation of a scaffold material containing monolayer expanded cells into the defect, with the aim to differentiate the cells into chondrocytes. While this may be a valid approach, the secretome of the implanted cells and its effects on the endogenous resident cells, is gaining in interest. This review aims to summarize the knowledge on the secretome of mesenchymal stem cells, including knowledge from other tissues, in order to indicate how these mechanisms may be of value in repairing articular cartilage defects. Potential therapies and their effects on the repair of articular cartilage defects will be discussed, with a focus on the transition from classical cell therapy to the implantation of cell free matrices releasing specific cytokines.