Small molecule inhibitors of mammalian glycosylation

Effect of N-Glycan Profiles on Binding Affinity of Diagnostic Antibody Produced by Hybridomas in Serum-Free Suspension

Serum-free suspension culture for hybridomas is one of the important key steps for efficient diagnostic antibody production while maintaining protein quality and function. Based on the importance of N-glycan profiles in therapeutic antibody production in mammalian cells, the effect of changes in the N-glycan profiles on the function of diagnostic antibody must also be validated. To investigate the influence of diagnostic antibodies with different N-glycan profiles on the binding affinity with target antigens, four glycosylation regulators, tunicamycin, Bis-Tris, galactose, and N-acetylmannosamine, were administered separately to diagnostic antibody-producing hybridomas cultures. Supplementation with these four glycosylation modulators inhibited glycosylation and increased mannosylation, galactosylation, and sialylation in serum-free suspended hybridomas. In particular, the diagnostic antibody produced from a culture with tunicamycin exhibited a significant increase in the aglycosylated form compared with those without tunicamycin or with other glycosylation modulators. Surprisingly, diagnostic antibody with different N-glycan compositions did not significantly affect binding affinity with the target antigen and even aglycosylated antibodies did not affect binding affinity. Taken together, the results indicate that the change in the N-glycan profile of the diagnostic antibody produced in serum-free suspension hybridomas in an altered culture environment did not significantly affect their biological function, which provides valuable insight for the production and quality control of diagnostic antibody.

Shear Stress Promotes Remodeling of Platelet Glycosylation via Upregulation of Platelet Glycosidase Activity: One More Thing

Mechanical circulatory support (MCS) is a mainstay of therapy for advanced and end-stage heart failure. Accompanied by systemic anticoagulation, contemporary MCS has become less thrombogenic, with bleeding complications emerging as a major cause of readmission and 1-year mortality. Shear-mediated platelet dysfunction and thrombocytopenia of undefined etiology are primary drivers of MCS-related bleeding. Recently, it has been demonstrated that deprivation of platelet surface glycosylation is associated with the decline of hemostatic function, microvesiculation, and premature apoptosis. We test the hypothesis that shear stress induces remodeling of platelet surface glycosylation via upregulation of glycosidase activity, thus facilitating platelet count decline and intense microvesiculation.Human gel-filtered platelets were exposed to continuous shear stress in vitro. Platelets and platelet-derived microparticles (PDMPs) were quantified via flow cytometry using size standard fluorescent nanobeads. Platelet surface glycosylation and NEU1 expression were evaluated using lectin- or immune-staining and multicolor flow cytometry; lectin blotting was utilized to verify glycosylation of individual glycoproteins. Platelet neuraminidase, galactosidase, hexosaminidase, and mannosidase activities were quantified using 4-methylumbelliferone-based fluorogenic substrates.We demonstrate that shear stress promotes selective remodeling of platelet glycosylation via downregulation of 2,6-sialylation, terminal galactose, and mannose, while 2,3-sialylation remains largely unchanged. Shear-mediated deglycosylation is partially attenuated by neuraminidase inhibitors, strongly suggesting the involvement of platelet neuraminidase in observed phenomena. Shear stress increases platelet NEU1 surface expression and potentiates generation of numerous NEU1+ PDMPs. Platelets exhibit high basal hexosaminidase and mannosidase activities; basal activities of platelet neuraminidase and galactosidase are rather low and are significantly upregulated by shear stress. Shear stress of increased magnitude and duration promotes an incremental decline of platelet count and immense microvesiculation, both being further exacerbated by neuraminidase and partially attenuated by neuraminidase inhibition.Our data indicate that shear stress accumulation, consistent with supraphysiologic conditions of device-supported circulation, promotes remodeling of platelet glycosylation via selective upregulation of platelet glycosidase activity. Shear-mediated platelet deglycosylation is associated with platelet count drop and increased microvesiculation, thus offering a direct link between deglycosylation and thrombocytopenia observed in device-supported patients. Based on our findings, we propose a panel of molecular markers to be used for reliable detection of shear-mediated platelet deglycosylation in MCS.

Swift Universal Glycan Acquisition (SUGA) Enables Quantitative Glycan Profiling across Diverse Sample Types

The ability to rapidly analyze complex mixtures of glycans derived from glycoproteins is important, but techniques are often laborious and require multiple glycan derivatization steps. Here, we describe an approach termed Swift Universal Glycan Acquisition (SUGA) in which the total released, nonreduced N-glycan samples are analyzed following direct injection and electrospray ionization in a mass spectrometer with a rapid 3 min run time for each sample. As electrospray ionization (ESI) can generate multiple charge states and adducts for the same glycan composition (MS1), deconvolution is performed to yield the relative intensity profile for each detected glycan composition; each annotated composition is supported by an annotated MS2 spectrum. This combination of MS1 and MS2 data enables confident glycan identification. The data obtained by SUGA are comparable to those obtained using permethylated N-glycans analyzed by matrix-assisted laser desorption/ionization (MALDI)-MS. The SUGA approach was applied to the analyses of several purified glycoproteins and N-glycans derived from cells and compared to spectra obtained following permethylation and analysis by MALDI-MS. This new approach will facilitate the rapid and high-throughput analysis of N-glycans from diverse biological samples.

Regulation of T Cell Glycosylation by MXene/β-TCP Nanocomposite for Enhanced Mandibular Bone Regeneration

Immune-mediated bone regeneration driven by bone biomaterials offers a therapeutic strategy for repairing bone defects. Among 2D nanomaterials, Ti3C2Tx MXenes have garnered substantial attention for their potential in tissue regeneration. This investigation concentrates on the role of MXene nanocomposites in modulating the immune microenvironment within bone defects to facilitate bone tissue restoration. Ti3C2Tx MXenes are synthetized, incorporated into beta-tricalcium phosphate ceramics (β-TCP) nanocomposites (T-MXene), and their osteoinductive and immunomodulatory effects are evaluated. The effects of T-MXene-treated T-cells on bone marrow stromal cells (BMSCs) are explored. In addition, its therapeutic potential for bone regeneration is assessed in vivo using a critical-sized mandibular bone defect model. The underlying mechanisms by which T-MXene regulates T-cell differentiation and bone regeneration are explored via whole-transcriptome RNA sequencing. The scaffolds activate N-glycosylation in T cells, which possess anti-inflammatory and antioxidant effects, thereby inducing a pro-regenerative response. T-MXene increased the proportion of IL-4+ T cells among primary T cells and mandibular lymph nodes, ultimately promoting osteogenesis in BMSCs and injured mandibles. The distinctive function of MXene-based nanocomposites in osteoimmunomodulation provides a solid foundation for further exploration and application of MXenes as immune response modulators, potentially advancing their use in regenerative medicine.

Lectin-glycan interactions: a comprehensive cataloguing of cancer-associated glycans for biorecognition and bio-alteration: a review

This comprehensive review meticulously compiles data on an array of lectins and their interactions with different cancer types through specific glycans. Crucially, it establishes the link between aberrant glycosylation and cancer types. This repository of lectin-defined glycan signatures, assumes paramount importance in the realm of cancer and its dynamic nature. Cancer, known for its remarkable heterogeneity and individualized behaviour, can be better understood through these glycan signatures. The current review discusses the important lectins and their carbohydrate specificities, especially recognizing glycans of cancer origin. The review also addresses the key aspects of differentially expressed glycans on normal and cancerous cell surfaces. Specific cancer types highlighted in this review include breast cancer, colon cancer, glioblastoma, cervical cancer, lung cancer, liver cancer, and leukaemia. The glycan profiles unveiled through this review hold the key to tailor-made treatment and precise diagnostics. It opens up avenues to explore the potential of targeting glycosyltransferases and glycosidases linked with cancer advancement and metastasis. Armed with knowledge about specific glycan expressions, researchers can design targeted therapies to modulate glycan profiles, potentially hampering the advance of this relentless disease.

A proton channel, Otopetrin 1 (OTOP1) is N-glycosylated at two asparagine residues in third extracellular loop

A proton (H+) channel, Otopetrin 1 (OTOP1) is an acid sensor in the sour taste receptor cells. Although OTOP1 is known to be activated by extracellular acid, no posttranslational modification of OTOP1 has been reported. As one of the posttranslational modifications, glycosylation is known to modulate many ion channels. In this study, we investigated whether OTOP1 is glycosylated and how the glycosylation affects OTOP1 function. Pharmacological and enzymatic examinations (using an N-glycosylation inhibitor, tunicamycin and peptide: N-glycanase F [PNGase F]) revealed that overexpressed mouse OTOP1 was N-glycosylated. As the N-glycans were Endoglycosidase H (Endo H)-sensitive, they were most likely high-mannose type. A site-directed mutagenesis approach revealed that both two asparagine residues (N238 and N251) in the third extracellular loop between the fifth transmembrane region and the sixth transmembrane region (L5-6) were the glycosylation sites. Prevention of the glycosylations by the mutations of the asparagine residues or by tunicamycin treatment diminished the whole-cell OTOP1 current densities. The results of cell surface biotinylation assay showed that the prevention of the glycosylations reduced the surface expression of OTOP1 at the plasma membrane. These results indicate that mouse OTOP1 is N-glycosylated at N238 and N251, and that the glycosylations are necessary for OTOP1 to show the maximum degree of H+ current densities at the plasma membrane through promoting its targeting to the plasma membrane. These findings on glycosylations of OTOP1 will be a part of a comprehensive understanding on the regulations of OTOP1 function.

Tamoxifen metabolites treatment promotes ERα+ transition to triple negative phenotype in vitro, effects of LDL in chemoresistance

OBJECTIVE

Estrogen receptor-positive (ER+) breast cancer represents about 80% of cases, tamoxifen is the election neoadjuvant chemotherapy. However, a large percentage of patients develop chemoresistance, compromising recovery. Clinical evidence suggests that high plasmatic levels of low-density lipoproteins (LDL) could promote cancer progression. The present study analyzed the effect of LDL on the primary plasmatic active Tamoxifen's metabolites resistance acquisition, 4-hydroxytamoxifen (4OH-Tam) and 4-hydroxy-N-desmethyl-tamoxifen (endoxifen), in breast cancer ERα + cells (MCF-7).

METHODS

Two resistant cellular variants, MCF-7Var-H and MCF-7Var-I, were generated by a novel strategy and their phenotype features were evaluated. Phenotypic assessment was performed by MTT assays, cytometry, immunofluorescence microscopy, zymography and protein expression analysis.

RESULTS

MCF-7Var-H, generated only with tamoxifen metabolites, showed a critical down-regulation in hormone receptors, augmented migration capacity, metalloprotease 9 extracellular medium excretion, and a mesenchymal morphology in contrast with native MCF-7, suggesting the transition towards Triple-negative breast cancer (TNBC) phenotype. In contrast, MCF-7Var-I which was generated in a high LDL media, showed only a slight upregulation in ER and other less noticeable metabolic adaptations. Results suggest a potential role of transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in phenotypic differences observed among variants.

CONCLUSION

LDL high or low concentrations during Tamoxifen´s metabolites chemoresistance acquisition leads to different cellular mechanisms related to chemoresistance. A novel adaptative cellular response associated with Nrf2 activity could be implicated.

The Exploitation of the Glycosylation Pattern in Asthma: How We Alter Ancestral Pathways to Develop New Treatments

Asthma has reached epidemic levels, yet progress in developing specific therapies is slow. One of the main reasons for this is the fact that asthma is an umbrella term for various distinct subsets. Due to its high heterogeneity, it is difficult to establish biomarkers for each subset of asthma and to propose endotype-specific treatments. This review focuses on protein glycosylation as a process activated in asthma and ways to utilize it to develop novel biomarkers and treatments. We discuss known and relevant glycoproteins whose functions control disease development. The key role of glycoproteins in processes integral to asthma, such as inflammation, tissue remodeling, and repair, justifies our interest and research in the field of glycobiology. Altering the glycosylation states of proteins contributing to asthma can change the pathological processes that we previously failed to inhibit. Special emphasis is placed on chitotriosidase 1 (CHIT1), an enzyme capable of modifying LacNAc- and LacdiNAc-containing glycans. The expression and activity of CHIT1 are induced in human diseased lungs, and its pathological role has been demonstrated by both genetic and pharmacological approaches. We propose that studying the glycosylation pattern and enzymes involved in glycosylation in asthma can help in patient stratification and in developing personalized treatment.

Protracted molecular dynamics and secondary structure introspection to identify dual-target inhibitors of Nipah virus exerting approved small molecules repurposing

Nipah virus (NiV), with its significantly higher mortality rate compared to COVID-19, presents a looming threat as a potential next pandemic, particularly if constant mutations of NiV increase its transmissibility and transmission. Considering the importance of preventing the facilitation of the virus entry into host cells averting the process of assembly forming the viral envelope, and encapsulating the nucleocapsid, it is crucial to take the Nipah attachment glycoprotein-human ephrin-B2 and matrix protein as dual targets. Repurposing approved small molecules in drug development is a strategic choice, as it leverages molecules with known safety profiles, accelerating the path to finding effective treatments against NiV. The approved small molecules from DrugBank were used for repurposing and were subjected to extra precision docking followed by absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiling. The 4 best molecules were selected for 500 ns molecular dynamics (MD) simulation followed by Molecular mechanics with generalized Born and surface area solvation (MM-GBSA). Further, the free energy landscape, the principal component analysis followed by the defined secondary structure of proteins analysis were introspected. The inclusive analysis proposed that Iotrolan (DB09487) and Iodixanol (DB01249) are effective dual inhibitors, while Rutin (DB01698) and Lactitol (DB12942) were found to actively target the matrix protein only.

Integrating Computational Methods in Network Pharmacology and In Silico Screening to Uncover Multi-targeting Phytochemicals against Aberrant Protein Glycosylation in Lung Cancer

Glycoproteins are an underexploited drug target for cancer therapeutics. In this work, we integrated computational methods in network pharmacology and in silico docking approaches to identify phytochemical compounds that could potentially interact with several cancer-associated glycoproteins. We first created a database of phytochemicals from selected plant species, Manilkara zapota (sapodilla/chico), Mangifera indica (mango), Annona muricata (soursop/guyabano), Artocarpus heterophyllus (jackfruit/langka), Lansium domesticum (langsat/lanzones), and Antidesma bunius (bignay), and performed pharmacokinetic analysis to determine their drug-likeness properties. We then constructed a phytochemical-glycoprotein interaction network and characterized the degree of interactions between the phytochemical compounds and with cancer-associated glycoproteins and other glycosylation-related proteins. We found a high degree of interactions from α-pinene (Mangifera indica), cyanomaclurin (Artocarpus heterophyllus), genistein (Annona muricata), kaempferol (Annona muricata and Antidesma bunius), norartocarpetin (Artocarpus heterophyllus), quercetin (Annona muricata, Antidesma bunius, Manilkara zapota, Mangifera indica), rutin (Annona muricata, Antidesma bunius, Lansium domesticum), and ellagic acid (Antidesma bunius and Mangifera indica). Subsequent docking analysis confirmed that these compounds could potentially bind to EGFR, AKT1, KDR, MMP2, MMP9, ERBB2, IGF1R, MTOR, and HRAS proteins, which are known cancer biomarkers. In vitro cytotoxicity assays of the plant extracts showed that the n-hexane, ethyl acetate, and methanol leaf extracts from A. muricata, L. domesticum and M. indica gave the highest growth inhibitory activity against A549 lung cancer cells. These may help further explain the reported cytotoxic activities of select compounds from these plant species.

Simple, Economic, and Robust Rail-Based Setup for Super-Resolution Localization Microscopy

Research during the past 2 decades has showcased the power of single-molecule localization microscopy (SMLM) as a tool for exploring the nanoworld. However, SMLM systems are typically available in specialized laboratories and imaging facilities, owing to their expensiveness as well as complex assembly and alignment procedure. Here, we lay out the blueprint of a sturdy, rail-based, cost-efficient, multicolor SMLM setup that is easy to construct and align in service of simplifying the accessibility of SMLM. We characterize the optical properties of the design and assess its capabilities, robustness, and stability. The performance of the system is assayed using super-resolution imaging of biological samples. We believe that this design will make SMLM more affordable and broaden its availability.

SERPINA3: Stimulator or Inhibitor of Pathological Changes

SERPINA3, also called α-1-antichymotrypsin (AACT, ACT), is one of the inhibitors of serine proteases, one of which is cathepsin G. As an acute-phase protein secreted into the plasma by liver cells, it plays an important role in the anti-inflammatory response and antiviral response. Elevated levels of SERPINA3 have been observed in heart failure and neurological diseases such as Alzheimer's disease or Creutzfeldt-Jakob disease. Many studies have shown increased expression levels of the SERPINA3 gene in various types of cancer, such as glioblastoma, colorectal cancer, endometrial cancer, breast cancer, or melanoma. In this case, the SERPINA3 protein is associated with an antiapoptotic function implemented by adjusting the PI3K/AKT or MAPK/ERK 1/2 signal pathways. However, the functions of the SERPINA3 protein are still only partially understood, mainly in the context of cancerogenesis, so it seems necessary to summarize the available information and describe its mechanism of action. In particular, we sought to amass the existing body of research focusing on the description of the underlying mechanisms of various diseases not related to cancer. Our goal was to present an overview of the correct function of SERPINA3 as part of the defense system, which unfortunately easily becomes the "Fifth Column" and begins to support processes of destruction.