Sirtuins, as classic NAD⁺-dependent class III histone deacetylases (HDACs), have been the focus of extensive research since their discovery, primarily centered on the mechanisms by which their deacetylase activity mediates the pathogenesis of various diseases and regulates key biological processes. With the rapid advancement of epigenetics, numerous novel acylation modifications, including lysine malonylation (Kma), lysine β-hydroxybutyrylation (Kbhb), lysine succinylation (Ksucc), and have been identified to date. Notably, the recently discovered lysine lactylation (Kla) modification has fundamentally revised long-held perception of lactic acid as a mere "metabolic waste". Importantly, SIRT1-3 have been shown to possess robust delactylase activity. To date, SIRT1-7 have been discovered to exert over ten distinct novel enzymatic functions. Herein, we summarized the functions of SIRT1-7 and their associated metabolic regulatory pathways in the context of post-translational modifications.
Previous study demonstrated that Hypnea cervicornis lectin (HCA) reduces inflammation and nociception via interaction with the lectin carbohydrate-binding site, modulating gene expression of the interleukins IL-1β, TNF-α and of iNOS. This study evaluated the effect of HCA in the rat model of arthritis induced by zymosan in the tibiotarsal joint and the involvement of macrophage-derived mediators. In vitro, macrophages were stimulated with zymosan before being incubated with HCA and the supernatant was injected into the joint. In vivo, HCA was administered by intravenous route after intra-articular injection of zymosan, fMLP, or macrophages supernatant. Hypernociception, edema and leukocyte influx were evaluated in the joints, and inflammatory mediators in the macrophage supernatant or periarticular tissue. In vitro, HCA (100 µg/ml) reduced NO2− and IL-1β in the supernatant of macrophages. In vivo, HCA (3 mg/kg) reduced articular hypernociception, edema and leukocyte influx elicited by zymosan, fMLP or by the supernatant of zymosan activated macrophages, as well as the zymosan-induced rolling and adhesion, and gene expression of iNOS and IL-1. HCA attenuated edema and leukocyte influx in the periarticular tissue, revealing preserved chondrocytes in the cartilage. In conclusion, HCA exerts anti-inflammatory effect in the arthritis induced by zymosan in rat tibio-tarsal joints, involving NO and IL-1 released by resident macrophages.
Sialidase Neu4 is a glycosidase that removes sialic acids from nonreducing ends of sugar chains. Recently, Mexican tetra Neu4 (AmNeu4) was identified as a nuclear-localized sialidase. However, the subnuclear localization and biological functions of AmNeu4 have remained unclear. This study demonstrated that AmNeu4 localized in the nucleolus and investigated the significance of its nuclear localization signal (NLS) for the nucleolar localization. Green fluorescent protein (GFP) fused to NLS localized to the nucleolus. Additionally, deletion of the NLS in AmNeu4 abolished its nucleolar localization, and insertion of additional lysine/arginine residues into AmNeu4’s NLS induced exclusive nucleolar localization. These results indicated that the nucleolar localization of AmNeu4 was mediated by its NLS. The proliferation of AmNeu4-overexpressing HeLa cells was significantly reduced compared with that of the mock-transfected cells. Moreover, enzymatically inactive AmNeu4 also suppressed cell growth, indicating that the enzymatic activity of AmNeu4 is not required for the suppression of cell growth. We hypothesized that the suppressed cell proliferation is mediated by protein-protein interactions involving AmNeu4. By immunoprecipitation assay, ribosomal proteins L5 and L11 (RPL5 and RPL11, respectively) were identified as AmNeu4 interacting partners. C-MYC protein levels were lower in AmNeu4-overexpressing cells than in mock cells, and these reduced levels were restored by RPL11 knockdown. Coimmunoprecipitation assay further revealed that RPL11 bound to C-MYC in AmNeu4-overexpressing cells. These results suggest that the interaction between AmNeu4 and RPL5/RPL11 delays cell growth through destabilizing C-MYC.
Malignant melanoma has a high mortality rate and is aggressive. The development, metastasis, and angiogenesis of melanoma have all been connected to toll-like receptor 4 (TLR4). However, signal transduction mediated by TLR4 for accelerating melanoma progression is fully unclear. Because of this, the current research has been carried out to explore drug candidate possibility using 3'-Sialyllactose (3'-SL). We investigated the inhibitory effect of 3'-SL on migration and invasion, which are associated with treatment difficulty and mortality. The suppression of matrix metalloproteinases 9 (MMP-9) expression and activity by 3'-SL in B16F10 murine melanoma cells and concurrently downregulated the MAPK signaling pathway involved in this regulation. Therefore, our results demonstrate that 3'-SL may be a good candidate for the development of therapeutic agents to suppress malignancy associated with metastasis and invasion.
Optimizing non-viral vectors for gene therapy requires elucidating the molecular mechanisms underlying vector uptake and intracellular delivery. In this study, cell transfection using pDNA/polysaccharide complexes was investigated to develop a gene delivery system specific for gastric tumor cells that express hyaluronic acid (HA) receptors such as CD44 variant 9 (CD44v9) and receptor for hyaluronan-mediated motility (RHAMM). pDNA/chitosan/HA complexes showed specific transgene expression activity in CD44v9(+) cells, mediated by CD44v9-dependent cell uptake and microtubule-dependent transport. Particularly, RHAMM was involved in intracellular transport of pDNA/chitosan/HA complexes. We demonstrated that HA drives CD44v9-mediated internalization, RHAMM-mediated, and microtubule-dependent intracellular transport, which are essential for enhanced pDNA complex-driven gene expression in gastric cancer cells co-expressing CD44v9 and RHAMM.
α-Gal syndrome (AGS) is a type of allergy to red meat and other mammalian products that develops after a tick bite. Symptoms may include urticaria, angioedema, gastrointestinal and respiratory symptoms, and, most dangerously, anaphylactic shock. Among food allergies, it is considered unusual because: (i) the major allergen is not a protein, but a carbohydrate moiety Galα-1,3-Gal, which humans do not synthesize; (ii) it is caused by α-Gal-containing glycoconjugates injected during a tick bite; (iii) the hypersensitivity is effected by IgE antibodies which arise after a class switch from IgG and IgM-class antibodies; (iv) it seems to be triggered by α-Gal-containing glycolipids present in red meat, with delayed onset. Here, we evaluate glycans that may cause AGS, review the data about glycosyltransferases that synthesize α-Gal and related antigens and describe the immune mechanism behind AGS: sensitization and host response to ticks’ saliva. In addition, we consider future research avenues that may lead to a better understanding and management of AGS as a modern dietary affliction rooted in an old evolutionary trade-off.
Glycated hemoglobin (HbA1c) is a well-established biomarker reflecting chronic glycemic control in diabetes. It accumulates through non-enzymatic glycation of hemoglobin under sustained hyperglycemia and serves as a surrogate of metabolic memory. Emerging in parallel, glycosylated RNA (glycoRNA), small noncoding RNAs bearing covalently attached N-linked glycans, has revealed unexpected roles in immune signaling and glycoimmunomodulation. While glycation and glycosylation represent distinct biochemical processes, both are modulated by glucose availability and cellular stress. This opinion paper aimed to explore the conceptual parallels between HbA1c and glycoRNA, proposing that hyperglycemia-induced metabolic changes may simultaneously influence both processes. In light of these, glycoRNA represents an emerging biomarker as a functional effector in metabolic disease, mirroring the hyperglycemia-driven immunological dimensions of HbA1c with a further advantage of a defined metabolic sequence, which can deepen diagnostics towards disease progression patterns. Though direct experimental evidence is currently limited, we outline plausible mechanistic intersections and suggest methodological frameworks for future research. Therefore, this perspective aims to stimulate interdisciplinary investigation into glycoRNA biology within the broader context of glycemic dysregulation and immune modulation in diabetes.
Protein glycosylation has been implicated in the pathogenesis of cancer, with colorectal cancer (CRC) strongly associated with serum N-glycosylation and IgG N-glycosylation. However, the N-glycosylation profile of non-immunoglobulin serum proteins (IgS-D) in CRC progression remains largely unexplored. Serum IgS-D was isolated using affinity chromatography, followed by the release of N-glycans, methylamidation, and MALDI-MS analysis. The potential of the IgS-D N-glycome profile to reflect CRC progression was assessed through Mann-Whitney U tests and multivariate analysis. A total of 43 distinct N-glycans were identified in IgS-D. Notably, a significant reduction in serum IgS-D mannosylated N-glycans was observed in CRC patients compared to healthy controls. Further analysis of individual N-glycans revealed significant differences and diagnostic potential in five specific N-glycans: H5N2 (AUC = 0.868), H6N2 (AUC = 0.73), H5N4S1 (AUC = 0.800), H5N5S1F1 (AUC = 0.713), and H5N4S2F1 (AUC = 0.689). A panel comprising these five N-glycans demonstrated high diagnostic accuracy for CRC (AUC = 0.924). The N-glycosylation profile of serum IgS-D is closely associated with CRC progression. Specific N-glycan signatures provide robust discrimination between CRC patients and healthy controls, warranting further investigation into the underlying molecular mechanisms.
Avidities and intensities of the Structural units, Glycotopes and their polyvalencies in the LFuc Recognition Protein (FRP)-glycan interactions have not been well defined and organized. This is due to the absence of the special glycan reagents and insufficient experiences. In this report, one of the best LFuc Recognition Proteins (FRPs) was analyzed by the enzyme-linked lectinosorbent and inhibition assays. From the data provided, it is found that the polyvalencies of the Fucα1→2Gal related structural units and their glycotopes are the dominant ones, especially these units of the human blood group H, Leb/Ley-tetra saccharide and AB-Leb/Ley-penta active glycans, but not the Lea/Lex-tri ligands and Man related units. When their intensities are expressed by Mass Relative Potency (Mass R.P.), it can be up to 5.0×105 fold higher than their key monomer (LFuc). In addition to this FRP can be a used as a powerful tool to detect the presence of the H, Leb/Ley-tetra and AB-Leb/Ley-penta glycotopes in the mammalian glycoconjugates, the theme of this report is the first constructive work of its structural units and codes for the LFuc Recognition Protein (FRP) system. It is expected to expand to reveal more others in the future.
N-linked glycosylation is one of the most important post-translational modification of proteins. Fucosylated N-glycans are related to many biological processes and they are commonly used as biomarkers. However, determining fucose linkages in N-glycans remains challenging. Most of the fucose linkages, particularly the linkages in the antennas of N-glycans, remain unidentified. In this work, a simple multi-stage tandem mass spectrometry based on dissociation mechanisms, namely logically derived sequence tandem mass spectrometry, was developed for the de novo determination of fucose linkages in N-glycans. Using the N-glycans extracted from pine nuts, human milk, and bee venom, we demonstrated that fucose linkages in intact N-glycans, including the 1→3 or 1→6 linkage in the core and the linkage in the α(1→3) or α(1→6) antenna were identified. The procedure does not require the N-glycan standards, and the entire process is summarized in a flowchart for automation. The CID mass spectra acquired with low resolution linear ion trap mass spectrometer (peak width 0.3 Da) are very similar to those obtained with high resolution Orbitrap mass spectrometer (R = 100,000 FWHM at m/z 400), indicating that the choice of mass analyzer does not affect carbohydrate structural elucidation.
Plant lectins derived from a variety of plant sources can inhibit the proliferation of certain types of human cancer cells and have been studied extensively. In the present study, the effects of Jacalin, a Thomsen–Friedenreich disaccharide-binding lectin isolated from jackfruit seeds, on the triple-negative breast cancer (TNBC) cell line MDA-MB-468 was investigated in combination with Taxol. It was observed that Jacalin inhibited the proliferation of these cancer cells. The antiproliferative effect of Jacalin on MDA-MB-468 was found to be reversible. However, when Jacalin was removed from the cell culture after the treatment for the given time, the cancer cells recovered back and started proliferating again. Importantly, Jacalin has minimum effect on PBMCs proliferation taken as primary cell line control. Additionally, MDA-MB-468 cells were treated with a combination of Taxol (25 µM) and Jacalin (40 µg/mL). This shows that Jacalin and Taxol work better when used together, leading to a stronger inhibition in cancer cell growth. These results suggest that Jacalin shows in-vitro potential and requires further mechanistic and in-vivo evaluation before therapeutic relevance can be established.
Chondroitin sulfate (CS) and CS proteoglycans (CSPGs) are increasingly used in nutritional and biomedical applications. Although their functional benefits have traditionally been attributed to their translocation into the bloodstream after oral administration, their poor bioavailability, due to high molecular weight and strong negative charge, has prompted substantial debate. In this study, we examined the possibility that CS and CSPG act directly on intestinal epithelial cells, thereby providing an alternative explanation for their physiological effects under non-absorptive conditions. Differentiated Caco-2 cells (human enterocyte) were employed as an in vitro model of the intestinal epithelium. Administration of CS and CSPG modulated tissue inhibitor of metalloproteinase gene expression and altered gelatinase activity in the basolateral compartment. While the two glycans shared some overlapping actions, each also exerted distinct effects reflective of their structural features. These findings suggest that CS and CSPG directly modulate epithelial signaling and reshape the basement membrane microenvironment. Overall, this study suggests a mechanism by which CS/CSPG exerts physiological actions in the intestinal tract independent of systemic absorption, providing a new perspective on the functional outcomes of oral administration.
The aim of our research was to explore and validate the diagnostic value of mitochondria-related genes (MRGs) in basal cell carcinoma (BCC). The differentially expressed MRGs in BCC were identified based on the GSE39612, GSE42109 and GSE7553 training sets and the GSE53462 validation set, and the PPI network was drawn. The potential signature genes in BCC were screened by LASSO, RF and SVM-RFE. Besides, the performance of the signature genes was evaluated and a nomogram was constructed. Moreover, immunoinfiltration, drug prediction and transcriptional regulation of these signature genes were also analyzed. Finally, qRT-PCR was employed to measure the expression of signature genes in clinical tissues and BCC cells. 1699 DEGs were obtained from the training set. Then, taking the intersection of DEGs, WGCNA module genes and MRGs, 36 DEGs-MRGs were obtained. Six potential signature genes in BCC, including ACADL, BCL2L2, CHCHD7, LDHB, NT5DC2, and PDK4, were obtained through LASSO, RF, and SVM-RFE. Nomogram and validation analysis confirmed that these 6 genes have ideal predictive power in BCC. In addition, 6 signature genes were significantly associated with macrophages and interacted with pyruvic acid, sodium chromate, perfluoroheptanoic acid and other drugs. Finally, qRT-PCR analysis showed that the expression trend of these 6 signature genes in clinical tissues and BCC cells was consistent with the results of bioinformatics analysis. ACADL, BCL2L2, CHCHD7, LDHB, NT5DC2 and PDK4 are potential diagnostic signature genes of BCC.
Total plasma N-glycans alter in disease states, with few studies focused on COVID-19. A discovery cohort of 310 COVID-19 patients, replicated with 97 COVID-19 patients and tested with 100 COVID-19 patients, was used to unearth the N-glycans capable of distinguishing infection, as well as prognosis of intensive care unit (ICU) admission and mortality. All significant bisected glycans were decreased in patients compared to controls, whilst fucosylated tri-antennary glycans and sialylated tetra-antennary glycans were increased in patients. For both those admitted to the ICU and those who died, Peak 61 (A4G4S4F) was elevated in the more severe disease course, while Peak 29 (FA2G2S2) was lowered. Pinpointing specific glycosylation changes has alluded to a potential story of glycoprotein pathways in response to SARS-CoV-2 infection. This study could be further explored through deriving the glycoproteins associated with the glycans of interest and the glycosylation changes experienced on these proteins.
Six oligosaccharides with the degree of polymerization (DP) 2 to 7 were isolated from the active fraction of Trillium tschonoskii using a high-temperature semi-preparative porous graphitic carbon (PGC) column based on high-performance liquid chromatography coupled with a charged aerosol detector and vanquish fraction collector (HPLC-CAD-VFC) system. The structures of DP2 − 7 were determined as maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, and maltoheptaose with (1→4)-α-d-glucopyranose residues by relative quantitative 1H nuclear magnetic resonance (qHNMR) spectroscopy with anomeric protons integration and NMR structural-reporter-group resonances. The immunomodulatory activities of this series of maltooligosaccharides (MOS) were tested on RAW264.7 cells. All samples on cells had no cytotoxicity, and the oligosaccharide fraction (TOS1) could increase the phagocytic capacity and production of nitric oxide (NO) and cytokines to a much higher level than monomers. In particular, maltopentaose (DP5) showed a relatively higher capacity for stimulating proliferation, NO, and cytokine production than other purified oligosaccharides. The immunomodulatory activity of MOS investigated in this study is beneficial for utilizing MOS as a functional ingredient in novel product development.
Visceral Leishmaniasis is one of the neglected vector-borne tropical disease escalating resistance against available drugs which have toxicity beyond therapeutic level leading to the requirement of alternative therapy. Macrophages, the primary cells of the immune system, being the host cells for the Leishmanial parasite undergo functional phenotypic changes based on its infected or uninfected states leading to release of specific cytokines. The M2 functional phenotype is suitable for parasite survival, while, M1 phenotype boosts the immune system leading to release of superoxide responsible for parasite clearance. Natural isolates i.e. peptides and glycoproteins isolated from various origin have been found to possess antileishmanial activities enhancing the chances to be used as a curative agent. Among them, plant glycoproteins have been found to possess immunostimulatory, antibacterial, antifungal, antiviral, anticancerous, as well as, antileishmanial activity attracting focus of researchers towards it as an alternating treating compound. This review highlights the drawbacks of existing drugs, route of development of the disease, mechanism of macrophage polarization as well as the overview of different isolated peptides and glycoproteins acting as an antileishmanial agent, having immunomodulating activity and an indication that glycoproteins can be presumed as an alternative therapy against the fatal noxious disease, if left untreated.
Integrins are heterodimeric receptors involved in cell adhesion and bidirectional signaling. Ganglioside GM3 in the outer leaflet of cell membranes possibly regulates integrin activity via direct interactions; however, its specific binding mode with integrins remains unclear. Therefore, in this study, we focused on the GM3 glycan moiety, which encounters the integrin ectodomain on the cell surface, and synthesized a soluble GM3 probe without hydrocarbon chains using a chemoenzymatic approach. Binding analysis using surface plasmon resonance (SPR) indicated that the synthetic GM3 probe interacts with the integrin α5β1 ectodomain with a significantly higher affinity than the lactosylceramide probe. Saturation transfer difference (STD) NMR spectra suggested that the integrin α5β1 ectodomain interacts with N-acetylneuraminic acid (Neu5Ac) at the GM3 terminal and α2-3Gal linkage. Notably, RGD peptide, an integrin ligand interacting with the heterodimer interface, competed with GM3 to bind to integrin α5β1 on the SPR sensor chip. Consistent with these results, the GM3-binding site predicted by Chai-1 partially overlapped with the RGD peptide-binding groove on integrin α5β1; however, the binding mode was different. RGD peptide bridged the α and β subunits of the integrin head moiety, whereas the GM3 probe found at the cleft between the subunits. The Neu5Ac-Gal moiety primarily interacts with the metal ion-dependent adhesion site and nearby residues in the β1 subunit. Overall, our findings suggest that gangliosides directly interact with integrin α5β1 at a previously unknown binding site, revealing a novel regulatory mechanism for the integrin activity.
