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Cancer Discovery Aug 2023Diffuse large B-cell lymphoma (DLBCL) can be subdivided into the activated B-cell (ABC) and germinal center B cell-like (GCB) subtypes. Self-antigen engagement of B-cell...
UNLABELLED
Diffuse large B-cell lymphoma (DLBCL) can be subdivided into the activated B-cell (ABC) and germinal center B cell-like (GCB) subtypes. Self-antigen engagement of B-cell receptors (BCR) in ABC tumors induces their clustering, thereby initiating chronic active signaling and activation of NF-κB and PI3 kinase. Constitutive BCR signaling is essential in some GCB tumors but primarily activates PI3 kinase. We devised genome-wide CRISPR-Cas9 screens to identify regulators of IRF4, a direct transcriptional target of NF-κB and an indicator of proximal BCR signaling in ABC DLBCL. Unexpectedly, inactivation of N-linked protein glycosylation by the oligosaccharyltransferase-B (OST-B) complex reduced IRF4 expression. OST-B inhibition of BCR glycosylation reduced BCR clustering and internalization while promoting its association with CD22, which attenuated PI3 kinase and NF-κB activation. By directly interfering with proximal BCR signaling, OST-B inactivation killed models of ABC and GCB DLBCL, supporting the development of selective OST-B inhibitors for the treatment of these aggressive cancers.
SIGNIFICANCE
DLBCL depends on constitutive BCR activation and signaling. There are currently no therapeutics that target the BCR directly and attenuate its pathologic signaling. Here, we unraveled a therapeutically exploitable, OST-B-dependent glycosylation pathway that drives BCR organization and proximal BCR signaling. This article is highlighted in the In This Issue feature, p. 1749.
Topics: Humans; NF-kappa B; Glycosylation; Signal Transduction; Lymphoma, Large B-Cell, Diffuse; Phosphatidylinositol 3-Kinases; Cell Line, Tumor
PubMed: 37141112
DOI: 10.1158/2159-8290.CD-22-1401 -
Cell Death and Differentiation Aug 2023Pancreatic ductal adenocarcinoma (PDAC) remains a highly fatal malignancy partially due to the acquired alterations related to aberrant protein glycosylation that...
Pancreatic ductal adenocarcinoma (PDAC) remains a highly fatal malignancy partially due to the acquired alterations related to aberrant protein glycosylation that pathologically remodel molecular biological processes and protect PDAC cells from death. Ferroptosis driven by lethal lipid peroxidation provides a targetable vulnerability for PDAC. However, the crosstalk between glycosylation and ferroptosis remains unclear. Here, we identified 4F2hc, a subunit of the glutamate-cystine antiporter system X, and its asparagine (N)-glycosylation is involved in PDAC ferroptosis by N- and O-linked glycoproteomics. Knockdown of SLC3A2 (gene name of 4F2hc) or blocking the N-glycosylation of 4F2hc potentiates ferroptosis sensitization of PDAC cells by impairing the activity of system X manifested by a marked decrease in intracellular glutathione. Mechanistically, we found that the glycosyltransferase B3GNT3 catalyzes the glycosylation of 4F2hc, stabilizes the 4F2hc protein, and enhances the interaction between 4F2hc and xCT. Knockout of B3GNT3 or deletion of enzymatically active B3GNT3 sensitizes PDAC cells to ferroptosis. Reconstitution of 4F2hc-deficient cells with wildtype 4F2hc restores ferroptosis resistance while glycosylation-mutated 4F2hc does not. Additionally, upon combination with a ferroptosis inducer, treatment with the classical N-glycosylation inhibitor tunicamycin (TM) markedly triggers the overactivation of lipid peroxidation and enhances the sensitivity of PDAC cells to ferroptosis. Notably, we confirmed that genetic perturbation of SLC3A2 or combination treatment with TM significantly augments ferroptosis-induced inhibition of orthotopic PDAC. Clinically, high expression of 4F2hc and B3GNT3 contributes to the progression and poor survival of PDAC patients. Collectively, our findings reveal a previously unappreciated function of N-glycosylation of 4F2hc in ferroptosis and suggest that dual targeting the vulnerabilities of N-glycosylation and ferroptosis may be an innovative therapeutic strategy for PDAC.
Topics: Humans; Glycosylation; Ferroptosis; Glycosyltransferases; Cell Line, Tumor; Pancreatic Neoplasms; Carcinoma, Pancreatic Ductal; N-Acetylglucosaminyltransferases
PubMed: 37479744
DOI: 10.1038/s41418-023-01188-z -
Cell Dec 2023Transfer RNA (tRNA) modifications are critical for protein synthesis. Queuosine (Q), a 7-deaza-guanosine derivative, is present in tRNA anticodons. In vertebrate tRNAs...
Transfer RNA (tRNA) modifications are critical for protein synthesis. Queuosine (Q), a 7-deaza-guanosine derivative, is present in tRNA anticodons. In vertebrate tRNAs for Tyr and Asp, Q is further glycosylated with galactose and mannose to generate galQ and manQ, respectively. However, biogenesis and physiological relevance of Q-glycosylation remain poorly understood. Here, we biochemically identified two RNA glycosylases, QTGAL and QTMAN, and successfully reconstituted Q-glycosylation of tRNAs using nucleotide diphosphate sugars. Ribosome profiling of knockout cells revealed that Q-glycosylation slowed down elongation at cognate codons, UAC and GAC (GAU), respectively. We also found that galactosylation of Q suppresses stop codon readthrough. Moreover, protein aggregates increased in cells lacking Q-glycosylation, indicating that Q-glycosylation contributes to proteostasis. Cryo-EM of human ribosome-tRNA complex revealed the molecular basis of codon recognition regulated by Q-glycosylations. Furthermore, zebrafish qtgal and qtman knockout lines displayed shortened body length, implying that Q-glycosylation is required for post-embryonic growth in vertebrates.
Topics: Animals; Humans; Rats; Anticodon; Cell Line; Codon; Glycosylation; Nucleoside Q; RNA, Transfer; Swine; Zebrafish; Nucleic Acid Conformation
PubMed: 37992713
DOI: 10.1016/j.cell.2023.10.026 -
The Journal of Biological Chemistry Nov 2023O-linked N-acetylglucosamine (O-GlcNAc) glycosylation, a prevalent protein post-translational modification (PTM) that occurs intracellularly, has been shown to crosstalk...
O-linked N-acetylglucosamine (O-GlcNAc) glycosylation, a prevalent protein post-translational modification (PTM) that occurs intracellularly, has been shown to crosstalk with phosphorylation and ubiquitination. However, it is unclear whether it interplays with other PTMs. Here we studied its relationship with ADP-ribosylation, which involves decorating target proteins with the ADP-ribose moiety. We discovered that the poly(ADP-ribosyl)ation "eraser", ADP-ribose glycohydrolase (PARG), is O-GlcNAcylated at Ser26, which is in close proximity to its nuclear localization signal. O-GlcNAcylation of PARG promotes nuclear localization and chromatin association. Upon DNA damage, O-GlcNAcylation augments the recruitment of PARG to DNA damage sites and interacting with proliferating cell nuclear antigen (PCNA). In hepatocellular carcinoma (HCC) cells, PARG O-GlcNAcylation enhances the poly(ADP-ribosyl)ation of DNA damage-binding protein 1 (DDB1) and attenuates its auto-ubiquitination, thereby stabilizing DDB1 and allowing it to degrade its downstream targets, such as c-Myc. We further demonstrated that PARG-S26A, the O-GlcNAc-deficient mutant, promoted HCC in mouse xenograft models. Our findings thus reveal that PARG O-GlcNAcylation inhibits HCC, and we propose that O-GlcNAc glycosylation may crosstalk with many other PTMs.
Topics: Animals; Humans; Mice; Acetylglucosamine; ADP-Ribosylation; Carcinoma, Hepatocellular; Glycoside Hydrolases; Liver Neoplasms; Poly Adenosine Diphosphate Ribose; Glycosylation; Protein Processing, Post-Translational
PubMed: 37858678
DOI: 10.1016/j.jbc.2023.105354 -
Bone Research Oct 2023Glycans, either alone or in complex with glycan-binding proteins, are essential structures that can regulate cell biology by mediating protein stability or receptor... (Review)
Review
Glycans, either alone or in complex with glycan-binding proteins, are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions. Certain glycans are ligands for lectins, which are carbohydrate-specific receptors. Bone is a complex tissue that provides mechanical support for muscles and joints, and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells, called osteoblasts, and bone-resorbing cells, called osteoclasts. Bone erosion occurs when bone resorption notably exceeds bone formation. Osteoclasts may be activated during cancer, leading to a range of symptoms, including bone pain, fracture, and spinal cord compression. Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases. The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology. Moreover, we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.
Topics: Animals; Humans; Osteoclasts; Glycomics; Bone Resorption; Carrier Proteins; Cell Differentiation; Polysaccharides; Mammals
PubMed: 37884496
DOI: 10.1038/s41413-023-00293-6 -
Biotechnology Advances Sep 2023Glycosylation-mediated post-translational modification is critical for regulating many fundamental processes like cell division, differentiation, immune response, and... (Review)
Review
Glycosylation-mediated post-translational modification is critical for regulating many fundamental processes like cell division, differentiation, immune response, and cell-to-cell interaction. Alterations in the N-linked or O-linked glycosylation pattern of regulatory proteins like transcription factors or cellular receptors lead to many diseases, including cancer. These alterations give rise to micro- and macro-heterogeneity in tumor cells. Here, we review the role of O- and N-linked glycosylation and its regulatory function in autoimmunity and aberrant glycosylation in cancer. The change in cellular glycome could result from a change in the expression of glycosidases or glycosyltransferases like N-acetyl-glucosaminyl transferase V, FUT8, ST6Gal-I, DPAGT1, etc., impact the glycosylation of target proteins leading to transformation. Moreover, the mutations in glycogenes affect glycosylation patterns on immune cells leading to other related manifestations like pro- or anti-inflammatory effects. In recent years, understanding the glycome to cancer indicates that it can be utilized for both diagnosis/prognosis as well as immunotherapy. Studies involving mass spectrometry of proteome, site- and structure-specific glycoproteomics, or transcriptomics/genomics of patient samples and cancer models revealed the importance of glycosylation homeostasis in cancer biology. The development of emerging technologies, such as the lectin microarray, has facilitated research on the structure and function of glycans and glycosylation. Newly developed devices allow for high-throughput, high-speed, and precise research on aberrant glycosylation. This paper also discusses emerging technologies and clinical applications of glycosylation.
Topics: Humans; Glycosylation; Neoplasms; Glycosyltransferases; Lectins; Immunotherapy; Polysaccharides
PubMed: 37030554
DOI: 10.1016/j.biotechadv.2023.108149 -
Frontiers in Endocrinology 2023As a metabolic disease, diabetes often leads to health complications such as heart failure, nephropathy, neurological disorders, and vision loss. Diabetic retinopathy...
INTRODUCTION
As a metabolic disease, diabetes often leads to health complications such as heart failure, nephropathy, neurological disorders, and vision loss. Diabetic retinopathy (DR) affects as many as 100 million people worldwide. The mechanism of DR is complex and known to impact both neural and vascular components in the retina. While recent advances in the field have identified major cellular signaling contributing to DR pathogenesis, little has been reported on the protein post-translational modifications (PTM) - known to define protein localization, function, and activity - in the diabetic retina overall. Protein glycosylation is the enzymatic addition of carbohydrates to proteins, which can influence many protein attributes including folding, stability, function, and subcellular localization. -linked glycosylation is the addition of sugars to an oxygen atom in amino acids with a free oxygen atom in their side chain (i.e., threonine, serine). To date, more than 100 congenital disorders of glycosylation have been described. However, no studies have identified the retinal -linked glycoproteome in health or disease. With a critical need to expedite the discovery of PTMomics in diabetic retinas, we identified both global changes in protein levels and the retinal -glycoproteome of control and diabetic mice.
METHODS
We used liquid chromatography/mass spectrometry-based proteomics and high throughput screening to identify proteins differentially expressed and proteins differentially -glycosylated in the retinas of wildtype and diabetic mice.
RESULTS
Changes in both global expression levels of proteins and proteins differentially glycosylated in the retinas of wild-type and diabetic mice have been identified. We provide evidence that diabetes shifts both global expression levels and -glycosylation of metabolic and synaptic proteins in the retina.
DISCUSSION
Here we report changes in the retinal proteome of diabetic mice. We highlight alterations in global proteins involved in metabolic processes, maintaining cellular structure, trafficking, and neuronal processes. We then showed changes in -linked glycosylation of individual proteins in the diabetic retina.
Topics: Animals; Mice; Diabetes Mellitus, Experimental; Proteomics; Diabetic Retinopathy; Retina; Glycosylation; Proteome
PubMed: 37693346
DOI: 10.3389/fendo.2023.1229089 -
Cell Host & Microbe Jul 2023Glycosylation of eukaryotic virus particles is common and influences their uptake, trafficking, and immune recognition. In contrast, glycosylation of bacteriophage...
Glycosylation of eukaryotic virus particles is common and influences their uptake, trafficking, and immune recognition. In contrast, glycosylation of bacteriophage particles has not been reported; phage virions typically do not enter the cytoplasm upon infection, and they do not generally inhabit eukaryotic systems. We show here that several genomically distinct phages of Mycobacteria are modified with glycans attached to the C terminus of capsid and tail tube protein subunits. These O-linked glycans influence antibody production and recognition, shielding viral particles from antibody binding and reducing production of neutralizing antibodies. Glycosylation is mediated by phage-encoded glycosyltransferases, and genomic analysis suggests that they are relatively common among mycobacteriophages. Putative glycosyltransferases are also encoded by some Gordonia and Streptomyces phages, but there is little evidence of glycosylation among the broader phage population. The immune response to glycosylated phage virions in mice suggests that glycosylation may be an advantageous property for phage therapy of Mycobacterium infections.
Topics: Animals; Mice; Mycobacteriophages; Glycosylation; Bacteriophages; Virion; Glycosyltransferases; Polysaccharides
PubMed: 37329881
DOI: 10.1016/j.chom.2023.05.028 -
The Journal of Biological Chemistry Nov 2023Recent advances in the understanding of the molecular mechanisms underlying cancer progression have led to the development of novel therapeutic targeting strategies.... (Review)
Review
Recent advances in the understanding of the molecular mechanisms underlying cancer progression have led to the development of novel therapeutic targeting strategies. Aberrant glycosylation patterns and their implication in cancer have gained increasing attention as potential targets due to the critical role of glycosylation in regulating tumor-specific pathways that contribute to cancer cell survival, proliferation, and progression. A special type of glycosylation that has been gaining momentum in cancer research is the modification of nuclear, cytoplasmic, and mitochondrial proteins, termed O-GlcNAcylation. This protein modification is catalyzed by an enzyme called O-GlcNAc transferase (OGT), which uses the final product of the Hexosamine Biosynthetic Pathway (HBP) to connect altered nutrient availability to changes in cellular signaling that contribute to multiple aspects of tumor progression. Both O-GlcNAc and its enzyme OGT are highly elevated in cancer and fulfill the crucial role in regulating many hallmarks of cancer. In this review, we present and discuss the latest findings elucidating the involvement of OGT and O-GlcNAc in cancer.
Topics: Humans; Acetylglucosamine; Biosynthetic Pathways; Glycosylation; N-Acetylglucosaminyltransferases; Neoplasms; Protein Processing, Post-Translational
PubMed: 37838167
DOI: 10.1016/j.jbc.2023.105344 -
Acta Pharmaceutica Sinica. B Mar 2024Despite advances in understanding the development and progression of cancer in recent years, there remains a lack of comprehensive characterization of the cancer... (Review)
Review
Despite advances in understanding the development and progression of cancer in recent years, there remains a lack of comprehensive characterization of the cancer glycoproteome. Glycoproteins play an important role in medicine and are involved in various human disease conditions including cancer. Glycan-moieties participate in fundamental cancer processes like cell signaling, invasion, angiogenesis, and metastasis. Aberrant -glycosylation significantly impacts cancer processes and targeted therapies in clinic. Therefore, understanding -glycosylation in a tumor is essential for comprehending disease progression and discovering anti-cancer targets and biomarkers for therapy monitoring and diagnosis. This review presents the fundamental process of protein -glycosylation and summarizes glycosylation changes in tumor cells, including increased terminal sialylation, -glycan branching, and core-fucosylation. Also, the role of -glycosylation in tumor signaling pathways, migration, and metabolism are discussed. Glycoproteins and glycopeptides as potential biomarkers for early detection of cancer based on site specificity have been introduced. Collectively, understanding and exploring the cancer glycoproteome, along with its role in medicine, implication in cancer and other human diseases, highlights the significance of -glycosylation in tumor processes, necessitating further research for potential anti-cancer targets and biomarkers.
PubMed: 38486989
DOI: 10.1016/j.apsb.2023.10.014