Chondroitin Sulfate Synthesis Research Articles

Solid‐Phase‐Supported Chemoenzymatic Synthesis and Analysis of Chondroitin Sulfate Proteoglycan Glycopeptides

Proteoglycans (PGs), consisting of glycosaminoglycans (GAGs) linked with the core protein through a tetrasaccharide linkage region, play roles in many important biological events. The chemical synthesis of PG glycopeptides is extremely challenging. In this work, the enzymes required for synthesis of chondroitin sulfate (CS) PG (CSPG) have been expressed and the suitable sequence of enzymatic reactions has been established. To expedite CSPG synthesis, the peptide acceptor was immobilized on solid phase and the glycan units were directly installed enzymatically onto the peptide. Subsequent enzymatic chain elongation and sulfation led to the successful synthesis of CSPG glycopeptides. The CS dodecasaccharide glycopeptide was the longest homogeneous CS glycopeptide synthesized to date. The enzymatic synthesis was much more efficient than the chemical synthesis of the corresponding CS glycopeptides, which could reduce the total number of synthetic steps by 80%. The structures of the CS glycopeptides were confirmed by mass spectrometry analysis and NMR studies. In addition, the interactions between the CS glycopeptides and cathepsin G were studied. The sulfation of glycan chain was found to be important for binding with cathepsin G. This efficient chemoenzymatic strategy opens new avenues to investigate the structures and functions of PGs.

Solid-Phase-Supported Chemoenzymatic Synthesis and Analysis of Chondroitin Sulfate Proteoglycan Glycopeptides.

Proteoglycans (PGs), consisting of glycosaminoglycans (GAGs) linked with the core protein through a tetrasaccharide linkage region, play roles in many important biological events. The chemical synthesis of PG glycopeptides is extremely challenging. In this work, the enzymes required for synthesis of chondroitin sulfate (CS) PG (CSPG) have been expressed and the suitable sequence of enzymatic reactions has been established. To expedite CSPG synthesis, the peptide acceptor was immobilized on solid phase and the glycan units were directly installed enzymatically onto the peptide. Subsequent enzymatic chain elongation and sulfation led to the successful synthesis of CSPG glycopeptides. The CS dodecasaccharide glycopeptide was the longest homogeneous CS glycopeptide synthesized to date. The enzymatic synthesis was much more efficient than the chemical synthesis of the corresponding CS glycopeptides, which could reduce the total number of synthetic steps by 80%. The structures of the CS glycopeptides were confirmed by mass spectrometry analysis and NMR studies. In addition, the interactions between the CS glycopeptides and cathepsin G were studied. The sulfation of glycan chain was found to be important for binding with cathepsin G. This efficient chemoenzymatic strategy opens new avenues to investigate the structures and functions of PGs.

Enhancing the expression of chondroitin 4-O-sulfotransferase for one-pot enzymatic synthesis of chondroitin sulfate A

Chondroitin sulfate (CS) stands as a pivotal compound in dietary supplements for osteoarthritis treatment, propelling significant interest in the biotechnological pursuit of environmentally friendly and safe CS production. Enzymatic synthesis of CS for instance CSA has been considered as one of the most promising methods. However, the bottleneck consistently encountered is the active expression of chondroitin 4-O-sulfotransferase (C4ST) during CSA biosynthesis. This study meticulously delved into optimizing C4ST expression through systematic enhancements in transcription, translation, and secretion mechanisms via modifications in the 5′ untranslated region, the N-terminal encoding sequence, and the Komagataella phaffii chassis. Ultimately, the active C4ST expression escalated to 2713.1 U/L, representing a striking 43.7-fold increase. By applying the culture broth supernatant of C4ST and integrating the 3′-phosphoadenosine-5′-phosphosulfate (PAPS) biosynthesis module, we constructed a one-pot enzymatic system for CSA biosynthesis, achieving a remarkable sulfonation degree of up to 97.0 %. The substantial enhancement in C4ST expression and the development of an engineered one-pot enzymatic synthesis system promises to expedite large-scale CSA biosynthesis with customizable sulfonation degrees.

Detoxification of Hyperglycemia-induced Glucose Toxicity by the Hexosamine Biosynthetic Pathway.

The abnormal intermediate glucose metabolic pathways induced by elevated intracellular glucose levels during hyperglycemia often establish the metabolic abnormality that leads to cellular and structural changes in development and to progression of diabetic pathologies. Glucose toxicity generally refers to the hyperglycemia-induced irreversible cellular dysfunctions over time. These irreversible cellular dysfunctions in diabetic nephropathy include: (1) inflammatory responses, (2) mesangial expansion, and (3) podocyte dysfunction. Using these three cellular events in diabetic nephropathy as examples of glucose toxicity in the diabetic complications, this review focuses on: (1) the molecular and cellular mechanisms associated with the hexosamine biosynthetic pathway that underly glucose toxicity; and (2) the potential therapeutic tools to inhibit hyperglycemia induced pathologies. We propose novel therapeutic strategies that directly shunts intracellular glucose buildup under hyperglycemia by taking advantage of intracellular glucose metabolic pathways to dampen it by normal synthesis and secretion of hyaluronan, and/or by intracellular chondroitin sulfate synthesis and secretion. This could be a useful way to detoxify the glucose toxicity in hyperglycemic dividing cells, which could mitigate the hyperglycemia induced pathologies in diabetes.

Molecular mechanism of decision-making in glycosaminoglycan biosynthesis

Two major glycosaminoglycan types, heparan sulfate (HS) and chondroitin sulfate (CS), control many aspects of development and physiology in a type-specific manner. HS and CS are attached to core proteins via a common linker tetrasaccharide, but differ in their polymer backbones. How core proteins are specifically modified with HS or CS has been an enduring mystery. By reconstituting glycosaminoglycan biosynthesis in vitro, we establish that the CS-initiating N-acetylgalactosaminyltransferase CSGALNACT2 modifies all glycopeptide substrates equally, whereas the HS-initiating N-acetylglucosaminyltransferase EXTL3 is selective. Structure-function analysis reveals that acidic residues in the glycopeptide substrate and a basic exosite in EXTL3 are critical for specifying HS biosynthesis. Linker phosphorylation by the xylose kinase FAM20B accelerates linker synthesis and initiation of both HS and CS, but has no effect on the subsequent polymerisation of the backbone. Our results demonstrate that modification with CS occurs by default and must be overridden by EXTL3 to produce HS.

Reduction of lysosome abundance and GAG accumulation after odiparcil treatment in MPS I and MPS VI models

Deficiencies of lysosomal enzymes responsible for the degradation of glycosaminoglycans (GAG) cause pathologies commonly known as the mucopolysaccharidoses (MPS). Each type of MPS is caused by a deficiency in a specific GAG-degrading enzyme and is characterized by an accumulation of disease-specific GAG species. Previously, we have shown the potential of the beta-D-xyloside, odiparcil, as an oral GAG clearance therapy for Maroteaux-Lamy syndrome (MPS VI), an MPS characterized by an accumulation of chondroitin sulphate (CS) and dermatan sulphate (DS). This work suggested that odiparcil acts via diverting the synthesis of CS and DS into odiparcil-bound excretable GAG. Here, we investigated the effect of odiparcil on lysosomal abundance in fibroblasts from patients with MPS I and MPS VI. In MPS VI fibroblasts, odiparcil reduced the accumulation of a lysosomal-specific lysotracker dye. Interestingly, a reduction of the lysotracker dye was also observed in odiparcil-treated fibroblasts from patients with MPS I, a disorder characterized by an accumulation of DS and heparan sulphate (HS). Furthermore, odiparcil was shown to be effective in reducing CS, DS, and HS concentrations in liver and eye, as representative organs, in MPS VI and MPS I mice treated with 3 doses of odiparcil over 3 and 9 months, respectively. In conclusion, our data demonstrates odiparcil efficiently reduced lysosome abundance and tissue GAG concentrations in in vitro and in vivo models of MPS VI and MPS I and has potential as a treatment for these disorders.

Genetic manipulation resulting in decreased donor chondroitin sulfate synthesis mitigates hepatic GVHD via suppression of T cell activity

Donor T cell activation, proliferation, differentiation, and migration are the major steps involved in graft-versus-host disease (GVHD) development following bone marrow transplantation. Chondroitin sulfate (CS) proteoglycan is a major component of the extracellular matrix and causes immune modulation by interacting with cell growth factors and inducing cell adhesion. However, its precise effects on immune function are unclear than those of other proteoglycan families. Thus, we investigated the significance of CS within donor cells in acute GVHD development utilizing CSGalNAc T1-knockout (T1KO) mice. To determine the effects of T1KO, the mice underwent allogenic bone marrow transplantation from major histocompatibility complex-mismatched donors. While transplantation resulted in hepatic GVHD with inflammatory cell infiltration of both CD4+ and CD8+ effector memory T cells, transplantation in T1KO-donors showed milder cell infiltration and improved survival with fewer splenic effector T cells. In vitro T-cell analyses showed that the ratio of effector memory T cells was significantly lower via phorbol myristate acetate/ionomycin stimulation. Moreover, quantitative PCR analyses showed significantly less production of inflammatory cytokines, such as IFN-γ and CCL-2, in splenocytes of T1KO mice. These results suggest that reduction of CS in donor blood cells may suppress the severity of acute GVHD after hematopoietic stem cell transplantation.

Abstract 3899: CHST11 mediated SEMA7A expression contributes to TKI resistant in lung cancer

Abstract An extracellular matrix has been demonstrated to be one of the substances that promote tumor cells to become driven by external stimuli to change their biology or malignancy. The main component of extracellular matrix, chondroitin sulfate, has been confirmed as a factor in the progression of tumors. Nevertheless, a great deal remains unknown regarding the precise mechanisms that drive Chondroitin sulfate production and how these details are communicated to cancer cells. According to our previous studies, the main enzyme responsible for Chondroitin sulfate synthesis, carbohydrate sulfotransferase 11 (CHST11), plays a crucial role in lung cancer cell metastatic spread. Nevertheless, the relationship between CHST11 expression and regulatory mechanism in response to lung cancer treatment is unclear, especially for tyrosine kinase inhibitor (TKI). A clinical correlation analysis was used in this study to identify molecules which were highly correlated with the overexpression of CHST11 and identified GPI-anchored protein semaphorin 7A (SEMA7A) as a candidate. According to the TCGA database, expression of upregulated SEMA7A is correlated with poor prognosis and cellular malignancy in lung cancer patients. A SEMA7A-based gene correlation analysis finds that the affected gene ontology is highly similar to CHST11, particularly integrin signaling, which may contribute to Gefitinib resistance. A GSEA analysis reveals a significant effect of CHST11 overexpression on mitotic spindle processes, some of which molecules are clinically relevant to CHST11 or SEMA7A. These molecules have been reported to be involved in TKI resistance events such as MARCKS, MYO1E, and PDLIM5. Based on the TCGA database, these molecules and integrins also display significant clinical relevance in lung cancer patients. A CHST11-mediated increase in SEMA7A in the mitotic spindle process of cells may serve as one of the possible means of reducing TKI-induced mitotic cell death, and thereby promoting the ability of lung cancer cells to become resistant to TKIs. Hence, targeting the CHST11-SEMA7A axis may offer a therapeutic strategy option that could be used to target drug resistance in lung cancers. [Keywords: CHST11, SEMA7A, Integrin, Drug resistant, Lung cancer] (Reference: https://pubmed.ncbi.nlm.nih.gov/35985204/; https://pubmed.ncbi.nlm.nih.gov/36181245/) Citation Format: Chien-Hsiu Chris Li, Ming-Hsien Chan, Yu-Chan Chang, Michael Hsiao. CHST11 mediated SEMA7A expression contributes to TKI resistant in lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3899.

Sensory Nerve Maintains Intervertebral Disc Extracellular Matrix Homeostasis Via CGRP/CHSY1 Axis.

Sensory nerves are long being recognized as collecting units of various outer stimuli; recent advances indicate that the sensory nerve also plays pivotal roles in maintaining organ homeostasis. Here, this study shows that sensory nerve orchestrates intervertebral disc (IVD) homeostasis by regulating its extracellular matrix (ECM) metabolism. Specifically, genetical sensory denervation of IVD results in loss of IVD water preserve molecule chondroitin sulfate (CS), the reduction of CS bio‐synthesis gene chondroitin sulfate synthase 1 (CHSY1) expression, and dysregulated ECM homeostasis of IVD. Particularly, knockdown of sensory neuros calcitonin gene‐related peptide (CGRP) expression induces similar ECM metabolic disorder compared to sensory nerve denervation model, and this effect is abolished in CHSY1 knockout mice. Furthermore, in vitro evidence shows that CGRP regulates nucleus pulposus cell CHSY1 expression and CS synthesis via CGRP receptor component receptor activity‐modifying protein 1 (RAMP1) and cyclic AMP response element‐binding protein (CREB) signaling. Therapeutically, local injection of forskolin significantly attenuates IVD degeneration progression in mouse annulus fibrosus puncture model. Overall, these results indicate that sensory nerve maintains IVD ECM homeostasis via CGRP/CHSY1 axis and promotes IVD repair, and this expands the understanding concerning how IVD links to sensory nerve system, thus shedding light on future development of novel therapeutical strategy to IVD degeneration.

One-pot synthesis of chondroitin sulfate A by engineered Pichia pastoris

Chondroitin sulfate (CS) is a linear polysaccharide, which is widely used in medical, health care and other fields. Compared with the traditional animal tissue extraction method, microbial synthesis of CS has the advantages of controllability and easiness of scaling-up. In order to achieve an efficient synthesis of chondroitin sulfate A (CSA), we constructed a recombinant Pichia pastoris GS115 strain capable of synthesizing chondroitin (Ch) from glycerol by introducing the Ch synthase coding genes kfoC, kfoA and UDP-glucose dehydrogenase coding gene tuaD into the P. pastoris chromosome. The titer of Ch reached 2.6 g/L in fed-batch cultures upon optimizing the synthesis pathway of Ch. After further expressing the chondroitin-4-O-sulfotransferase (C4ST), we developed a one-pot biosynthesis system for CSA production by directly adding 3'-adenosine-5'-phosphoryl sulfate and C4ST into the high-pressure homogenized recombinant P. pastoris cells. Eventually, controllable synthesis of 0-40% CSA with different sulfation degrees were achieved by optimizing the catalytic conditions. The one-pot biosynthesis system constructed here is easy to operate and easy to scale up for industrial production of CSA. The idea of the present study may also facilitate the biosynthesis of other glycosaminoglycan, for instance, heparin.

Chsy1 deficiency reduces extracellular matrix productions and aggravates cartilage injury in osteoarthritis.

Osteoarthritis (OA) is a kind of degenerative joint disease marked by the destruction of articular cartilage due to the degeneration of chondrocytes. CHSY1, one of the glycosyltransferases, is involved in the synthesis of chondroitin sulfate. Herein, we found that the expression of Chsy1 was decreased in the knee cartilage of OA rats. In order to investigate the role of CHSY1 in chondrogenesis and OA, we established a Chsy1 stable knockdown cell line in mouse ATDC5 chondrocytes by lentivirus. It was found that Chsy1 deficiency resulted in a reduction of extracellular matrix production in chondrocytes and a promotion of endochondral osteogenesis, which was indicated by the decreased expression of early chondrocytes genes (Col2a1, Sox9), and the increased expression of cartilage hypertrophy genes (Col10a1, Runx2, Mmp13, Mmp3). The expression trend of these genes is considered to be the characteristic of osteoarthritis. In addition, knockdown of Chsy1 could upregulate BMP signaling in differentiated chondrocytes, whereas Chsy1 overexpression had opposite effects. The reduction of extracellular matrix production and the promotion of endochondral osteogenesis by Chsy1 knockdown could be rescued by BMP signaling inhibitor LDN193189. Furthermore, the abnormally enhanced BMP signaling and the high expression of OA biomarker Mmp3 in primary cells of OA rats could be rescued by either LDN193189 or Chsy1 overexpression. These results implicate a role for Chsy1 in regulating extracellular matrix production and endochondral osteogenesis through BMP signaling; and a lack of Chsy1 could aggravate the cartilage damage of osteoarthritis.

CHST11‐mediated microenvironment events contribute to pulmonary fibrosis and cancer progression

The Carbohydrate sulfotransferase (CHST) family is essential for Chondroitin Sulfate synthesis and is associated with cancer progression. Comparing all CHST families, we found that CHST11 has prognostic value than other families. CHST11 is related to the overall survival rate in the pan‐cancer profile, among which lung adenocarcinoma is the most significant. From pulmonary fibrosis to lung cancer, the expression of CHST11 showed a linear increase. We analyzed the CHST11 interactome, and the results indicated that CHST11 contributes to diverse canonical pathways, including immune microenvironment, fibrosis, and cancer progression. Based on the prediction results of Ingenuity Pathway Analysis (IPA), we speculate that CHST11 can secrete IL1B and IL6 signals to activate the upstream regulator IRF8. This is also the key to the fact that IRF8 has contributed to cystic fibrosis and lung cancer progression. In addition, IRF8 can also transactivate CD80 and CD86 to reform the tumor microenvironments and immune response. By reversing the CHST11‐IL6/IL1B‐IRF8‐CD80/CD86 mediated axis, we confirmed that VE821 and LY2603618 have the value of drug repurposing. Our study proves novel insight into how CHST11 contributes to cystic fibrosis and lung cancer by reprogramming the immune microenvironment.

GRASP depletion-mediated Golgi fragmentation impairs glycosaminoglycan synthesis, sulfation, and secretion.

Synthesis of glycosaminoglycans, such as heparan sulfate (HS) and chondroitin sulfate (CS), occurs in the lumen of the Golgi, but the relationship between Golgi structural integrity and glycosaminoglycan synthesis is not clear. In this study, we disrupted the Golgi structure by knocking out GRASP55 and GRASP65 and determined its effect on the synthesis, sulfation, and secretion of HS and CS. We found that GRASP depletion increased HS synthesis while decreasing CS synthesis in cells, altered HS and CS sulfation, and reduced both HS and CS secretion. Using proteomics, RNA-seq and biochemical approaches, we identified EXTL3, a key enzyme in the HS synthesis pathway, whose level is upregulated in GRASP knockout cells; while GalNAcT1, an essential CS synthesis enzyme, is robustly reduced. In addition, we found that GRASP depletion decreased HS sulfation via the reduction of PAPSS2, a bifunctional enzyme in HS sulfation. Our study provides the first evidence that Golgi structural defect may significantly alter the synthesis and secretion of glycosaminoglycans.

Rational design of a highly efficient catalytic system for the production of PAPS from ATP and its application in the synthesis of chondroitin sulfate

The compound 3'-phosphoadenosine-5'-phosphosulfate (PAPS) serves as a sulfate group donor in the production of valuable sulfated compounds. However, elevated costs and low conversion efficiency limit the industrial applicability of PAPS. Here, we designed and constructed an efficient and controllable catalytic system for the conversion of adenosine triphosphate (ATP) (disodium salt) into PAPS without inhibition from by-products. In vitro and in vivo testing in Escherichia coli identified adenosine-5'-phosphosulfate kinase from Penicillium chrysogenum (PcAPSK) as the rate-limiting enzyme. Based on analysis of the catalytic steps and molecular dynamics simulations, a mechanism-guided "ADP expulsion" strategy was developed to generate an improved PcAPSK variant (L7), with a specific activity of 48.94 U·mg-1 and 73.27-fold higher catalytic efficiency (kcat/Km) that of the wild-type enzyme. The improvement was attained chiefly by reducing the ADP-binding affinity of PcAPSK, as well as by changing the enzyme's flexibility and lid structure to a more open conformation. By introducing PcAPSK L7 in an in vivo catalytic system, 73.59 mM (37.32 g·L-1 ) PAPS was produced from 150 mM ATP in 18.5 h using a 3-L bioreactor, and achieved titer is the highest reported to date and corresponds to a 98.13% conversion rate. Then, the PAPS catalytic system was combined with the chondroitin 4-sulfotransferase using a one-pot method. Finally, chondroitin sulfate was transformed from chondroitin at a conversion rate of 98.75%. This strategy has great potential for scale biosynthesis of PAPS and chondroitin sulfate.

Genetic Manipulation Resulting in Decreased Donor Chondroitin sulfate Synthesis Mitigates Gvhd Following Allogeneic Hematopoietic Cell Transplantation in a Murine Model.

Introduction: Severe acute graft versus host disease (GVHD) represents a major risk associated with allogeneic hematopoietic cell transplantation (HSCT). Both acute and progressive GVHD following HSCT are in large part attributable to responses of donor T cells to host allo-antigens. Alloreactive T cell activation can be modulated by signals from the tissue microenvironment (TME). Glycosaminoglycans (GAGs) in the TME or modifying T cell surface proteoglycans are known to regulate T cell function. However, the roles of GAGs in acute GVHD following allogeneic HSCT remain to be elucidated, since a suitable murine model has not been available. We previously established a unique mouse model (T1KO), in which knockout of the chondroitin sulfate (CS) N-acetylgalactosaminyltransferase-1 (T1) gene - encoding the rate-limiting CS-synthesizing enzyme - decreases CS production. We also reported a role for CS in murine hematopoietic stem cells. In the present study, we focus on donor T cell CS levels to assess the role of T cell CS in acute GVHD following allogeneic HSCT. We were able to mitigate the clinical features of GVHD in a murine model using T1KO donors. Methods: Eight- to 12-week-old T1KO mice were generated from a C57BL/6N (WT) strain as donors (H-2b) for allogeneic bone marrow transplantation (BMT). Donor BM cells were then transplanted into eight- to 12-week-old BALB/c recipients (H-2d). Prior to transplantation, recipients were irradiated at a dose of 7 Gy. They then received 5 x 106 BM cells and splenocytes of identical genotype, as well as low (5 x 105), intermediate (1 x 106), or high (4 x 106) doses of CD90.2+ cells from either WT or T1KO donors. For five weeks following BMT, survival was monitored daily and clinical GVHD scores (incorporating body weight, activity, fur condition, alopecia, and tortoiseshell-like mucosae) were calculated three times per week. Results: The peripheral blood CD4+/CD8+ T cell ratio of T1KO mice was equivalent to that of WT mice. Following allogeneic BMT, histopathologic analysis confirmed onset of acute recipient GVHD on day 49 when donors were WT mice. As a result, significant lymphocyte infiltration was observed in target organs (liver, colon, and skin). High-dose transplantation of splenocytes from T1KO rather than WT mice significantly prolonged recipient median survival (27.0 versus 20.5 days, p = 0.02). A similar trend was observed for low- and intermediate-dose transplantation (low: 53.0 versus 29.0 days, p = 0.09; intermediate: 50.5 versus 30.5 days, p = 0.13. Similarly, a significant improvement in day 11 GVHD score was observed following high-dose splenocyte transplantation when donors were T1KO mice (mean scores: 1.00 versus 2.75, p < 0.01). However, no significant differences in GVHD score were observed following low- and intermediate-dose transplantation. Taken together, our results suggest that donor T cells producing lower CS levels alleviate acute GVHD following allogeneic HSCT in a murine model. Conclusion: Alloreactive T cell activation following allogeneic HSCT may be down-regulated by lower CS levels, thereby mitigating GVHD severity. Figure 1 Disclosures No relevant conflicts of interest to declare.

Chondroitin sulfate N-acetylgalactosyltransferase-1 knockout shows milder phenotype in experimental autoimmune encephalomyelitis than in wild type.

Proteoglycans (PGs) are one of the main components in the extracellular matrix of the central nervous system. Chondroitin sulfate (CS) is a glycosaminoglycan (GAG), which is composed of major PGs. Similar to keratin sulfate (KS), another GAG, CS inhibits axon regeneration. However, the influence of these GAGs on the pathogenicity of neuroimmunological diseases is unclear. Here, we induced experimental autoimmune encephalomyelitis (EAE) in mice lacking CS N-acetylgalactosaminyltransferase-1 (CSGalNAcT1-KO), an important enzyme for CS synthesis. In our study, CSGalNAcT1-KO mice showed milder EAE symptoms than those in wild-type (WT) mice. The recall response of antigen-specific lymphocytes showed that CSGalNAcT1-KO-derived lymphocytes had a milder cell proliferation response than that in WT-derived lymphocytes. These results suggest that CS contributes toward the induction phase of EAE. We previously performed EAE experiments in GlcNAc-6-O-sulfotransferase KO (GlcNAc6ST-KO) and C6ST1-KO mice, which had reduced KS and reduced CS-C, respectively. EAE in CSGalNAcT1-KO mice was more similar to that in GlcNAc6ST-KO mice than in C6ST1-KO mice. In conclusion, the distinct GAG sugar chains are associated with severe or mild phenotypes of EAE and are therefore potential new therapeutic targets for neuroimmunological diseases, including multiple sclerosis.

Enzymatic Synthesis of Chondroitin Sulfate E to Attenuate Bacteria Lipopolysaccharide-Induced Organ Damage.

Chondroitin sulfate E (CS-E) is a sulfated polysaccharide that contains repeating disaccharides of 4,6-disulfated N-acetylgalactosamine and glucuronic acid residues. Here, we report the enzymatic synthesis of three homogeneous CS-E oligosaccharides, including CS-E heptasaccharide (CS-E 7-mer), CS-E tridecasaccharide (CS-E13-mer), and CS-E nonadecasaccharide (CS-E 19-mer). The anti-inflammatory effect of CS-E 19-mer was investigated in this study. CS-E 19-mer neutralizes the cytotoxic effect of histones in a cell-based assay and in mice. We also demonstrate that CS-E 19-mer treatment improves survival and protects against organ damage in a mouse model of endotoxemia induced by bacterial lipopolysaccharide (LPS). CS-E19-mer directly interacts with circulating histones in the plasma from LPS-challenged mice. CS-E 19-mer does not display anticoagulant activity nor react with heparin-induced thrombocytopenia antibodies isolated from patients. The successful synthesis of CS-E oligosaccharides provides structurally defined carbohydrates for advancing CS-E research and offers a potential therapeutic agent to treat life-threatening systemic inflammation.

Altered Expression of Aggrecan, FAM20B, B3GALT6, and EXTL2 in Patients with Osteoarthritis and Kashin-Beck Disease

The objective of this study was to investigate the expression of enzymes involved in synthesis and modification of chondroitin sulfate (CS) in knee cartilage tissue of patients with osteoarthritis (OA) and Kashin-Beck disease (KBD). The knee articular cartilage samples were obtained from 18 age- and gender-matched donors with 6 each in KBD, OA, and control groups. Hematoxylin and eosin (HE) staining, toluidine blue (TB) staining, and immunohistochemical (IHC) staining were performed to estimate the expression level and localization of aggrecan, along with FAM20B, GalT-II, and EXTL2, which are associated with CS synthesis and modification. Rank-based analyses of variance test was used for the multiple comparisons of discrepancy in the positive staining rate among the 3 groups. In HE and TB staining results, damaged morphology, decreased chondrocyte numbers and proteoglycans were observed in OA and KBD groups compared with the control group. In line with these trends, the positive staining rates of aggrecan were lower in KBD and OA groups than in the control group. Meanwhile, the positive staining rates of CS chain modifying enzymes FAM20B, GalT-II, and EXTL2 decreased in OA and KBD groups. In conclusion, it was demonstrated that altered expression of CS chain modifying enzymes in OA and KBD groups influenced the synthesis procession of CS and could contribute to the damage of cartilage. Further investigation of these enzymes can provide new theoretical and experimental targets for OA and KBD pathogenesis studies.

O-GlcNAcylation Dampens Dpp/BMP Signaling to Ensure Proper Drosophila Embryonic Development.

BMP (bone morphogenetic protein) signaling activity is precisely controlled by both pathway agonists andantagonists. Here, we identify a previously unrecognized BMP signaling antagonist. We demonstrate that the Drosophila BMP type I receptor Sax(Saxophone) functions as a Dpp (Decapentaplegic) receptor in Drosophila embryos, but that its activity is normally inhibited by the O-linked glycosyltransferase Sxc (Super sex combs). In wild-type embryos, Sax activity is inhibited, and the BMP type I receptor Tkv (Thickveins) is the sole conduit for Dpp. In contrast, in sxc mutants, the Dpp signal istransduced by both Tkv and Sax, and elevated Dpp signaling results in embryonic lethality. We also demonstrate that Sxc O-glycosylates Sax andobserve elevated Dpp signaling in response to maternal restriction of dietary sugar. These findings link fertility to nutritive environment and point to Sax signaling as the nutrient-sensitive branch of BMP signaling.

The role of the chondroitin sulfate synthase-1 gene in the immune response of the pearl oyster Pinctada fucata

Chondroitin sulfate synthase-1 (ChSy-1) plays an important role in the synthesis and chain extension of chondroitin sulfate (CS). CS, a linear polysaccharide with high structural diversity, plays crucial roles in cell adhesion, morphogenesis and cell division in response to viral and bacterial infections. However, the role of ChSy-1 in the immune response remains unknown. In the present study, ChSy-1 from Pinctada fucata was identified. The deduced amino acid sequence of ChSy-1 contains a conserved domain, CHGN, which belongs to glycosyltransferase family A, and multiple sequence alignment revealed that CHGN shows evolutionary differences. Phylogenetic analysis indicated that ChSy-1 may be conserved evolutionarily. The nucleus grafting experiment showed that ChSy-1 possibly participates in wound repair and immune response to the graft. Lipopolysaccharide or polyinosinic:polycytidylic acid challenge and gene expression analysis especially suggested that ChSy-1 is involved in the immune response. The results of the present study indicate that ChSy-1 plays a role in the protection of the pearl oyster against infectious diseases.