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Heparan sulfates (HSs) 1 are highly sulfated polysaccharides, present on the surface of mammalian cells and in the extracellular matrix in large quantities. HSs play critical roles in a variety of important biological processes, including assisting viral infection, regulating blood coagulation and embryonic development, suppressing tumor growth, and controlling the eating behavior of mice by interacting with specific regulatory proteins (1-5). HS polysaccharides carry negative charges under physiological pH, and the disaccharide repeating units consist of 134-linked sulfated glucosamine and uronic acid. The unique sequences determine to which specific proteins HSs bind, thereby regulating biological processes.The biosynthesis of HS occurs in the Golgi apparatus. It is initially synthesized as a copolymer of glucuronic acid and N-acetylated glucosamine by D-glucuronyl and N-acetyl-D-glucosaminyltransferase, followed by various modifications (6). These modifications include N-deacetylation and N-sulfation of glucosamine, C 5 epimerization of glucuronic acid to form iduronic acid residues, 2-O-sulfation of iduronic and glucuronic acid, as well as 6-O-sulfation and 3-O-sulfation of glucosamine. Several enzymes that are responsible for the biosynthesis of HS have been cloned and characterized (see review by Esko and Lindahl (7). These enzymes have become essential tools for investigating the relationship between the structures and functions of HS.What is still unknown is the detailed mechanism for regulating the biosynthesis of HS with a defined saccharide sequence. A recent report (8) suggests that the expression levels of various HS biosynthetic enzyme isoforms contribute to the synthesis of specific saccharide sequences in specific tissues. HS N-deacetylase/N-sulfotransferase, 3-O-sulfotransferase, and 6-O-sulfotransferase are present in multiple isoforms. Each isoform is believed to recognize a saccharide sequence around the modification site in order to generate a specific sulfated saccharide sequence (8 -10). For instance, HS D-glucosaminyl 3-O-sulfotransferase (3-OST) isoforms generate 3-Osulfated glucosamine residues that are linked to different sulfated uronic acid residues. 3-OST-1 transfers sulfate to the 3-OH position of an N-sulfated glucosamine residue that is linked to a glucuronic acid residue at the nonreducing end

On March 11, 2020, the World Health Organization declared its assessment of coronavirus disease 2019 (COVID-19) as a global pandemic. However, specific anti-severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) drugs are still under development, and patients are managed by multiple complementary treatments. We performed a retrospective analysis to compare and evaluate the effect of low molecular weight heparin (LMWH) treatment on disease progression. For this purpose, the clinical records and laboratory indicators were extracted from electronic medical records of 42 patients with COVID-19 (21 of whom were treated with LMWH, and 21 without LMWH) hospitalized (Union Hospital of Huazhong University of Science and Technology) from February 1 to March 15, 2020. Changes in the percentage of lymphocytes before and after LMWH treatment were significantly different from those in the control group (P = 0.011). Likewise, changes in the levels of D-dimer and fibrinogen degradation products in the LMWH group before and after treatment were significantly different from those in the control group (P = 0.035). Remarkably, IL-6 levels were significantly reduced after LMWH treatment (P = 0.006), indicating that, besides other beneficial properties, LMWH may exert an anti-inflammatory effect and attenuate in part the "cytokine storm" induced by the virus. Our results support the use of LMWH as a potential therapeutic drug for the treatment of COVID-19, paving the way for a subsequent well-controlled clinical study. On March 11, 2020, the World Health Organization (WHO) declared its assessment of coronavirus disease 2019 (COVID-19) as a global pandemic. Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is characterized by a long incubation period, high infectivity, and multiple routes of transmission. 1,2 However, no effective medicines are currently available, so patients are treated symptomatically. A better understanding of the mechanisms of pathological changes will help to screen potential drugs out of the currently available medications. Several clinical studies revealed that cytokine storms are important mechanisms underlying disease exacerbation and death of patients with COVID-19. 3-5 Particularly, IL-6 levels in severely ill patients were significantly higher than in mild cases. 6 IL-6 is one of the core cytokines, 7 contributing to many of the key symptoms of cytokine storm, such

Heparan sulfate (HS) is a structurally complex polysaccharide that interacts with a broad spectrum of extracellular effector ligands and thereby is thought to regulate a diverse array of biologic processes. The specificity of HS-ligand interactions is determined by the arrangement of sulfate groups on HS, which creates distinct binding motifs. Biologically important HS motifs are expected to exhibit regulated expression, yet there is a profound lack of tools to identify such motifs; consequently, little is known of their structures and functions. We have identified a novel phage display-derived antibody (NS4F5) that recognizes a highly regulated HS motif (HS NS4F5 ), which we have rigorously identified as (GlcNS6S-IdoA2S) 3 . HS NS4F5 exhibits a restricted expression in healthy adult tissues. Blocking HS NS4F5 on cells in culture resulted in reduced proliferation and enhanced sensitivity to apoptosis. HS NS4F5 is up-regulated in tumor endothelial cells, consistent with a role in endothelial cell activation. Indeed, TNF-␣ stimulated endothelial expression of HS NS4F5 , which contributed to leukocyte adhesion. In a mouse model of severe systemic amyloid protein A amyloidosis, HS NS4F5 was expressed within amyloid deposits, which were successfully detected by microSPECT imaging using NS4F5 as a molecularly targeted probe. Combined, our results demonstrate that NS4F5 is a powerful tool for elucidating the biological function of HS NS4F5 and can be exploited as a probe to detect novel polysaccharide biomarkers of disease processes.Heparan sulfate proteoglycans (HSPGs), 3 major components of the cell surface and the extracellular matrix, are involved in a variety of biological phenomena, including cell adhesion, proliferation, differentiation, and inflammation as well as being associated with pathologic events such as atherosclerosis and amyloidosis. Because of their high negative charge, HS chains interact with a variety of proteins, including growth factors/ morphogens and their receptors, the amyloid precursor protein serum amyloid protein A (AA), chemokines, and extracellular matrix proteins. HS-protein interactions vary with regard to specificity and may depend on charge density in addition to strict sequence motifs of HS.The interaction of heparin and HS with FGFs and their receptors has been characterized in great detail. Specific HS structures are predominantly determined by the regulated positioning of N-, 2-, 6-, and 3-O-sulfate groups along HS chains (1). For example, FGF-2 requires both N-and 2-O-sulfate groups for binding to HS. The 6-O-sulfate group is not essential for binding to FGF-2 but is critical for activation of the FGF receptor (2). In contrast, binding of hepatocyte growth factor, platelet-derived growth factor, lipoprotein lipase, and herpes simplex virus glycoprotein C to HS is dependent on 6-O-sulfation (3). The activation of antithrombin III by HS/heparin is mediated by a specific pentasaccharide in which a 3-O-sulfate group is crucial (4). Thus, the biological functions of HSPGs are contro...

The rapid discovery of novel viruses using next generation sequencing (NGS) technologies including DNA-Seq and RNA-Seq, has greatly expanded our understanding of viral diversity in recent years. The timely identification of novel viruses using NGS technologies is also important for us to control emerging infectious diseases caused by novel viruses. In this study, we identified a novel duck coronavirus (CoV), distinct with chicken infectious bronchitis virus (IBV), using RNA-Seq. The novel duck-specific CoV was a potential novel species within the genus Gammacoronavirus, as indicated by sequences of three regions in the viral 1b gene. We also performed a survey of CoVs in domestic fowls in China using reverse-transcription polymerase chain reaction (RT-PCR), targeting the viral nucleocapsid (N) gene. A total of 102 CoV positives were identified through the survey. Phylogenetic analysis of the viral N sequences suggested that CoVs in domestic fowls have diverged into several region-specific or host-specific clades or subclades in the world, and IBVs can infect ducks, geese and pigeons, although they mainly circulate in chickens. Moreover, this study provided novel data supporting the notion that some host-specific CoVs other than IBVs circulate in ducks, geese and pigeons, and indicated that the novel duck-specific CoV identified through RNA-Seq in this study is genetically closer to some CoVs circulating in wild water fowls. Taken together, this study shed new insight into the diversity, distribution, evolution and control of avian CoVs.

Our results imply that heparanase is clinically relevant in mesothelioma development. Given these preclinical and clinical data, heparanase appears to be an important mediator of mesothelioma, and heparanase inhibitors are worthy of investigation as a new therapeutic modality in mesothelioma clinical trials.

Background: D-Glucuronyl C5-epimerase is a crucial modifying enzyme in the heparan sulfate biosynthesis pathway. Results: We determined the Glce apo-structure and the structure of Glce complexed with a heparin hexasaccharide. Conclusion: Glce forms a dimer with the active sites located at both C-terminal ␣-helical domains. Significance: This work advances understanding of the key epimerization step in heparan sulfate biosynthesis.

Biosynthesis of heparin, a mast cell-derived glycosaminoglycan with widespread importance in medicine, has not been fully elucidated. In biosynthesis of heparan sulfate (HS), a structurally related polysaccharide, HS glucuronyl C5-epimerase (Hsepi) converts D-glucuronic acid (GlcA) to L-iduronic acid (IdoA) residues. We have generated Hsepi-null mouse mutant mast cells, and we show that the same enzyme catalyzes the generation of IdoA in heparin and that 'heparin' lacking IdoA shows a distorted O-sulfation pattern.