Galectin-14 promotes hepatocellular carcinoma tumor growth via enhancing heparan sulfate proteoglycan modification

Hepatocellular carcinoma(HCC)is a highly heterogeneous malignancy and lacks effective treatment.Bulk-sequencing of different gene transcripts by comparing HCC tissues and adjacent normal tissues provides some clues for investigating the mechanisms or identifying potential targets for tumor progression.However,genes that are exclusively expressed in a subpopulation of HCC may not be enriched or detected through such a screening.In the current study,we performed a single cell-clone-based screening and identified galectin-14 as an essential molecule in the regulation of tumor growth.The aberrant expression of galectin-14 was significantly associated with a poor overall survival of liver cancer patients with database analysis.Knocking down galectin-14 inhibited the proliferation of tumor growth,whereas overexpressing galectin-14 promoted tumor growth in vivo.Non-targeted metabolomics analysis indicated that knocking down galectin-14 decreased glycometabolism;specifically that glycoside synthesis was significantly changed.Further study found that galectin-14 promoted the expression of cell surface heparan sulfate proteoglycans(HSPGs)that functioned as co-receptors,thereby increasing the responsiveness of HCC cells to growth factors,such as epidermal growth factor and transforming growth factor-alpha.In conclusion,the current study identifies a novel HCC-specific molecule galectin-14,which increases the expression of cell surface HSPGs and the uptake of growth factors to promote HCC cell proliferation.

Collagen/heparan sulfate porous scaffolds loaded with neural stem cells improve neurological function in a rat model of traumatic brain injury

One reason for the poor therapeutic effects of stem cell transplantation in traumatic brain injury is that exogenous neural stem cells cannot effectively migrate to the local injury site,resulting in poor adhesion and proliferation of neural stem cells at the injured area.To enhance the targeted delivery of exogenous stem cells to the injury site,cell therapy combined with neural tissue engineering technology is expected to become a new strategy for treating traumatic brain injury.Collagen/heparan sulfate porous scaffolds,prepared using a freeze-drying method,have stable physical and chemical properties.These scaffolds also have good cell biocompatibility because of their high porosity,which is suitable for the proliferation and migration of neural stem cells.In the present study,collagen/heparan sulfate porous scaffolds loaded with neural stem cells were used to treat a rat model of traumatic brain injury,which was established using the controlled cortical impact method.At 2 months after the implantation of collagen/heparan sulfate porous scaffolds loaded with neural stem cells,there was significantly improved regeneration of neurons,nerve fibers,synapses,and myelin sheaths in the injured brain tissue.Furthermore,brain edema and cell apoptosis were significantly reduced,and rat motor and cognitive functions were markedly recovered.These findings suggest that the novel collagen/heparan sulfate porous scaffold loaded with neural stem cells can improve neurological function in a rat model of traumatic brain injury.This study was approved by the Institutional Ethics Committee of Characteristic Medical Center of Chinese People’s Armed Police Force,China(approval No.2017-0007.2)on February 10,2019.

Role of duck plague virus glycoprotein C in viral adsorption:Absence of specific interactions with cell surface heparan sulfate

Many mammalian herpes viruses utilize heparan sulfate （HS） moieties present on cell surface proteoglycans as receptors for cell entry, and this process also requires viral glycoprotein C （gC） homologues. However, our understanding of the role of gC in facilitating attachment of other alpha-herpes viruses such as the duck plague virus （DPV） remains preliminary. To study the role of gC during DPV infection, we used a gC-deleted mutant virus （DPV-AgC-EGFP）. Examination of the viral copy number by real-time PCR, as well as time course studies of viral adsorption and proliferation revealed that gC was involved in the viral binding to the cell surface. The affinity of viral glycoproteins （gB-DPV, gC-DPV, and gE-DPV） to HS was assessed using a prokaryotic expression system and HJTrapTM HeparJn HP column chromatography. In addition, to confirm that gC played a role in the interaction between DPV and HS, viruses were treated with the HS analogue heparin and host cells were treated with its inhibitors heparinase prior to exposure to DPV-△gC-EGFP or wild-type strain Chinese virulent duck plague virus （DPV-CHv）. The effects of heparin and heparinase on virus infectivity demonstrated that function of gC on Viral adsorption is independent of interactions between gC and heparin sulfate on cell surface. All in all, this study demonstrated that the gC of DPV can mediate viral adsorption in an HS-independent manner, which distinguish it from the gC of some other alpha-herpes viruses. Future studies will be required to identify the receptors involved in gC protein binding to cells. This work provides us a foundation for further studies of examining the roles of gC in the adsorption during duck plague virus infection.

The Importance of Heparan Sulfate in Herpesvirus Infection

Herpes simplex virus type-1 (HSV-1) is one of many pathogens that use the cell surface glycosaminoglycan heparan sulfate as a receptor. Heparan sulfate is highly expressed on the surface and extracellular matrix of virtually all cell types making it an ideal receptor. Heparan sulfate interacts with HSV-1 envelope glycoproteins gB and gC during the initial attachment step during HSV-1 entry. In addition,a modified form of heparan sulfate,known as 3-O-sulfated heparan sulfate,interacts with HSV-1 gD to induce fusion between the viral envelope and host cell membrane. The 3-O-sulfation of heparan sulfate is a rare modification which occurs during the biosynthesis of heparan sulfate that is carried out by a family of enzymes known as 3-O-sulfotransferases. Due to its involvement in multiple steps of the infection process,heparan sulfate has been a prime target for the development of agents to inhibit HSV entry. Understanding how heparan sulfate functions during HSV-1 infection may not only be critical for inhibiting infection by this virus,but it may also be crucial in the fight against many other pathogens as well.

How does Cellular Heparan Sulfate Function in Viral Pathogenicity?

Heparan sulfate （HS） is ubiquitously expressed on the surfaces and in the extracellular matrix of virtually all cell types, making it an ideal receptor for viral infection. Compared with wild‐type viruses, cell culture‐adapted laboratory strains exhibit more efficient binding to cellular HS receptors. HS‐binding viruses are typically cleared faster from the circulation and cause lower viremia than their non‐HS‐binding counterparts, suggesting that the HS‐binding phenotype is a tissue culture adaptation that lowers virus fitness in vivo. However, when inoculated intracranially, efficient cell attachment through HS binding can contribute to viral neurovirulence. The primary aim of this review is to discuss the roles of HS binding in viral pathogenicity, including peripheral virulence and neurovirulence. Understanding how heparan sulfate functions during virus infection in vivo may prove critical for elucidating the molecular mechanism of viral pathogenesis, and may contribute to the development of therapeutics targeting HS.

Effects of Ligustrazine on Expression of Bone Marrow Heparan Sulfates in Syngeneic Bone Marrow Transplantation Mice

To explore the effects of ligustrazine on bone marrow heparan sulfates (HS) expression in bone marrow transplantation (BMT) mice, the syngeneic BMT mice were orally given 2 mg ligustrazine twice a day. On the 7th, 10th, 14th, 18th day after BMT, peripheral blood cells and bone marrow nuclear cells (BMNC) were counted, and the expression levels of HS in bone marrow and on the stromal cell surfaces were detected by immunohistochemistry and flow cytometry assay respectively. In ligustrazine-treated group, the white blood cells (WBC) and BMNC on the 7th, 10th, 14th, 18th day and platelets (PLT) on the 7th, 10th day were all significantly more than those in control group (P<0.05). The bone marrow HS expression levels in ligustrazine-treated group were higher than those in control group (P<0.05) on the 7th, 10th, 14th, 18th day. However, the HS expression levels on the stromal cell surfaces showed no significant difference between the two groups on the 18th day (P>0.05). It was concluded that ligustrazine could up-regulate HS expression in bone marrow, which might be one of the mechanisms contributing to ligustrazine promoting hematopoietic reconstitution after BMT.

Effects of Platelet Factor 4 on Expression of Bone Marrow Heparan Sulfate in Syngenic Bone Marrow Transplantation Mice

To explore the effects of platelet factor 4(PF4) on hematopoietic reconstitution and its mechanism in syngenic bone marrow transplantation (BMT). The syngenic B MT mice models were established. 20 and 26 h before irradiation, the mice were injected 20 μg/kg PF4 or PBS twice into abdominal cavity, then the donor bone marrow nuclear cells (BMNC) were transplanted. On the 7th day, spleen clone forming units (CFU S) were counted. On the 7th, 14th and 21st day after BMT, the BMNC and megakaryoryocytes in bone marrow tissue were counted and the percentage of hematopoietic tissue and expression level of heparan sulfate in bone marrow tissue were assessed. In PF4 treated groups, the CFU S counts on the 7th day were higher than those in BMT groups after BMT. The BMNC and megakaryoryocyte counts and the percentage of hematopoietic tissue and heparan sulfate expression level were higher than those in BMT group on the 7th, 14th and 21st day after BMT ( P <0.01 or P <0.05). PF4 could accelerate hematopoietic reconstitution of syngenic bone marrow transplantation. The promotion of the heparan sulfate expression in bone marrow may be one of mechanisms of PF4.

Propolis modulates vitronectin,laminin,and heparan sulfate/heparin expression during experimental burn healing

Objective:This study was aimed at assessing the dynamics of vitronectin (VN), laminin (LN), and heparan sulfate/heparin (HS/HP) content changes during experimental burn healing. Methods:VN, LN, and HS/HP were isolated and purified from normal and injured skin of domestic pigs, on the 3rd, 5th, 10th, 15th, and 21st days following thermal damage. The wounds were treated with apitherapeutic agent (propolis), silver sulfadiazine (SSD), physiological salt solution, and propolis vehicle. VN and LN were quantified using an immunoenzymatic assay and HS/HP was estimated by densitometric analysis. Results:Propolis treatment stimulated significant increases in VN, LN, and HS/HP contents during the initial phase of study, followed by a reduction in the estimated extracellular matrix molecules. Similar patterns, although less extreme, were observed after treatment with SSD. Conclusions:The beneficial effects of propolis on experimental wounds make it a potential apitherapeutic agent in topical burn management.

Structural basis of heparan sulfate-specific degradation by heparinase Ⅲ

Heparinase Ⅲ(HepⅢ)is a 73-kDa polysaccharide lyase(PL)that degrades the heparan sulfate(HS)polysaccharides at sulfate-rare regions,which are important co-factors for a vast array of functional distinct proteins including the well-characterized antithrombin and the FGF/FGFR signal transduction system.It functions in cleaving metazoan heparan sulfate(HS)and providing carbon,nitrogen and sulfate sources for host microorganisms.It has long been used to deduce the structure of HS and heparin motifs;however,the structure of its own is unknown.Here we report the crystal structure of the HepⅢ from Bacteroides thetaiotaomicron at a resolution of 1.6Å.The overall architecture of HepⅢ belongs to the(α/α)5 toroid subclass with an N-terminal toroid-like domain and a C-terminal β-sandwich domain.Analysis of this high-resolution structure allows us to identify a potential HS substrate binding site in a tunnel between the two domains.A tetrasaccharide substrate bound model suggests an elimination mechanism in the HS degradation.Asn260 and His464 neutralize the carboxylic group,whereas Tyr314 serves both as a general base in C-5 proton abstraction,and a general acid in a proton donation to reconstitute the terminal hydroxyl group,respectively.The structure of HepⅢ and the proposed reaction model provide a molecular basis for its potential practical utilization and the mechanism of its eliminative degradation for HS polysaccarides.

Polymorphisms in ghrelin and heparan sulfate proteoglycan genes and their association with diabetic nephropathy in Pakistani population

Diabetic nephropathy(DN),a long term complication of diabetes,is the most common cause of end-stage renal disease,increasing the risk of death.Genetic predispositions play an important role in determining the susceptibility of the development of DN.Heparan sulphate proteoglycan(HSPG) and ghrelin(GH) gene polymorphisms are associated with the risk of DN.T allele frequency of the HSPG gene determined by BamHI polymorphism located in intron 6 may be a risk factor for the development of renal dysfunction in DN(Fisher two tailed test,CI = 95%,d.f.= 29,P = 0.016).The ghrelin gene polymorphism is caused by a cytosine-to-adenine transition in exon 2 of the preproghrelin gene forming Leu72Met variant.In Pakistani population,the preproghrelin Leu72Met polymorphism was observed to be not associated with diabetic nephropathy in patients as indicated by statistical analysis(CI = 95%,d.f.= 29,P = 0.691).The allelic frequencies of HSPG genetic polymorphism has the potential to be used as diagnostic markers for diabetic nephropathy disease.

Drosophila heparan sulfate 3-0 sulfotransferase B Null Mutant Is Viable and Exhibits No Defects in Notch Signaling

Heparan sulfate proteoglycans （HSPGs） are critically involved in a variety of biological events. The functions of HSPGs are determined by the nature of the core proteins and modifications of heparan sulfate （HS） glycosaminoglycan （GAG） chains. The distinct O-sulfo- transferases are important for nonrandom modifications at specific positions. Two HS 3-0 sulfotransferase （Hs3st） genes, Hs3st-A and Hs3st-B, were identified in Drosophila. Previous experiments using RNA interference （RNAi） suggested that Hs3st-B was required for Notch signaling. Here, we generated a null mutant of Hs3st-B via ends-out gene targeting and examined its role（s） in development. We found that homozygous Hs3st-B mutants have no neurogenic defects or alterations in the expression of Notch signaling target gene. Thus, our results strongly argue against an essential role for Hs3st-B in Notch signaling. Moreover, we have generated two independent Hs3st-A RNAi lines which worked to deplete Hs3st-A. Importantly, Hs3st-A RNAi combined with Hs3st-B mutant flies did not alter the expression of Notch signaling components, arguing that both Hs3st-A and Hs3st-B were not essential for Notch signaling. The establishment of Hs3st-B mutant and effective Hs3st-A RNAi lines provides essential tools for further studies of the physiological roles of Hs3st-A and Hs3st-B in development and homeostasis.

Mucopolysaccharidosis typeⅢB:a current review and exploration of the AAV therapy landscape

Mucopolysaccharidoses typeⅢB is a rare genetic disorder caused by mutations in the gene that encodes for N-acetyl-alpha-glucosaminidase.This results in the aggregation of heparan sulfate polysaccharides within cell lysosomes that leads to progressive and severe debilitating neurological dysfunction.Current treatment options are expensive,limited,and presently there are no approved cures for mucopolysaccharidoses typeⅢB.Adeno-associated virus gene therapy has significantly advanced the field forward,allowing researchers to successfully design,enhance,and improve potential cures.Our group recently published an effective treatment using a codon-optimized triple mutant adeno-associated virus 8 vector that restores N-acetyl-alpha-glucosaminidase levels,auditory function,and lifespan in the murine model for mucopolysaccharidoses typeⅢB to that seen in healthy mice.Here,we review the current state of the field in relation to the capsid landscape,adeno-associated virus gene therapy and its successes and challenges in the clinic,and how novel adenoassociated virus capsid designs have evolved research in the mucopolysaccharidoses typeⅢB field.

Inhibition of BACE1, the β-secretase implicated in Alzheimer’s disease, by a chondroitin sulfate extract from Sardina pilchardus

The pharmaceutical and anticoagulant agent heparin,a member of the glycosaminoglycan family of carbohydrates,has previously been identified as a potent inhibitor of a key Alzheimer’s disease drug target,the primary neuronalβ-secretase,β-site amyloid precursor protein cleaving enzyme 1(BACE1).The anticoagulant activity of heparin has,however,precluded the repurposing of this widely used pharmaceutical as an Alzheimer’s disease therapeutic.Here,a glycosaminoglycan extract,composed predominantly of 4-sulfated chondroitin sulfate,has been isolated from Sardina pilchardus,which possess the ability to inhibit BACE1(IC50[half maximal inhibitory concentration]=4.8μg/mL),while displaying highly attenuated anticoagulant activities(activated partial thromboplastin time EC50[median effective concentration]=403.8μg/mL,prothrombin time EC50=1.3 mg/mL).The marine-derived,chondroitin sulfate extract destabilizes BACE1,determined via differential scanning fluorimetry(ΔTm–5°C),to a similar extent as heparin,suggesting that BACE1 inhibition by glycosaminoglycans may occur through a common mode of action,which may assist in the screening of glycan-based BACE1 inhibitors for Alzheimer’s disease.

Proteoglycans: Road Signs for Neurite Outgrowth

Proteoglycans in the central nervous system play integral roles as ＂traffic signals＂ for the direction of neurite outgrowth. This attribute of proteoglycans is a major factor in regeneration of the injured central nervous system. In this review, the structures of proteoglycans and the evidence suggesting their involvement in the response following spinal cord injury are presented. The review further describes the methods routinely used to determine the effect proteoglycans have on neurite outgrowth. The effects of proteoglycans on neurite outgrowth are not completely understood as there is disagreement on what component of the molecule is interacting with growing neurites and this ambiguity is chronicled in an historical context. Finally, the most recent findings suggesting possible receptors, interactions, and sulfation patterns that may be important in eliciting the effect of proteoglycans on neurite outgrowth are discussed. A greater understanding of the proteoglycan-neurite interaction is necessary for successfully promoting regeneration in the iniured central nervous system.

Characterization of a new monoclonal anti-glypican-3 antibody specific to the hepatocellular carcinoma cell line, HepG2

AIM To characterize the antigen on HepG2 cell that is specifically recognized by a new monoclonal antibody raised against human liver heparan sulfate proteoglycan(HSPG), clone 1E4-1D9.METHODS The antigen recognized by m Ab 1E4-1D9 was immunoprecipitated and its amino acid sequence was analyzed LC/MS. The transmembrane domain, number of cysteine residues, and glycosylation sites were predicted from these entire sequences. Data from amino acid analysis was aligned with glypican-3(https://www.ebi.ac.uk/Tools/msa/clustalo/). The competitive reaction of mA b 1E4-1D9 and anti-glypican-3 on HepG2 cells was demonstrated by indirect immunofluorescence and analyzed by flow cytometry. Moreover, co-immunoprecipitation of mA b 1E4-1D9 and anti-glypican-3 was performed in HepG2 cells by Western immunoblotting. The recognition by mA b 1E4-1D9 of a specific epitope on solid tumor and hematopoietic cell lines was studied using indirect immunofluorescence and analyzed by flow cytometry.RESULTS Monoclonal antibody 1E4-1D9 reacted with an HSPG isolated from human liver and a band of 67 kD was detected under both reducing and non-reducing conditions. The specific antigen pulled down by m Ab 1E4-1D9, having a MW of 135 kD, was analyzed. The results showed two sequences of interest, gi30722350(1478 amino acid) and gi60219551(1378 amino acid). In both sequences no transmembrane regions were observed. Sequence number gi30722350 was 99.7% showed a match to FYCO1, a molecule involved in induction of autophagy. Sequence number gi60219551 contained 15 cysteines and 11 putative glycosylation sites with 6 predicted N-glycosylation sites. It was also matched with all PDZ domain proteins. Moreover, it showed an 85.7% match to glypican-3. Glypican-3 on HepG2 cells competitively reacted with both phycoerythrin-conjugated anti-glypican-3 and mA b 1E4-1C2 and resulted in an increase of double-stained cell population when higher concentration of m Ab 1E4-1D9 was used. Moreover, antigens precipitated from HepG2 cell by anti-glypican-3 could be detected by mA b 1E4-1D9 and vice versa. The recognition of antigens, on other solid tumor cell lines, by m Ab 1E4-1D9 was studied. The results demonstrated that m Ab 1E4-1D9 reacted with Huh7, HepG2, HT29, MCF7, SW620, Caco2, B16F1, U937, K562 and Molt4 cells. It was also found to be weakly positive to SW1353 and HL60 and negative to H460 and Hela cell lines. CONCLUSION All findings show that mA b 1E4-1D9 specifically recognizes glypican-3. Moreover, a new partner molecule of glypican-3, FYCO1 is proposed based on the results from co-precipitation studies.

Traffic lights for axon growth: proteoglycans and their neuronal receptors

Axon growth is a central event in the development and post-injury plasticity of the nervous system. Growing axons encounter a wide variety of environmental instructions. Much like traffic lights in controlling the migrating axons, chondroitin sulfate proteoglycans （CSPGs） and heparan sulfate proteoglycans （HSPGs） often lead to ＂stop＂ and ＂go＂ growth responses in the axons, respectively. Recently, the LAR family and NgR family molecules were identified as neuronal receptors for CSPGs and HSPGs. These discoveries provided molecular tools for further study of mechanisms underlying axon growth regulation. More importantly, the identification of these proteoglycan receptors offered potential therapeutic targets for promoting post-injury axon regeneration.

EXTRACTION AND ISOLATION OF PROTEOGLYCANS FROM RAT BRAIN

This paper reports a comparative study of the extraction rate of rat brain proteoglycans (PGs) by three different methods, with chromatography, papain digestion and electrophoretic technique. The results showed: ① The extraction rate of brain PGs by 4mol/L guanidine HCl (GuHCl)was higher than that by phosphate-buffered saline (PBS) In any method, however the protein/PGs ratio in the GuHCl-extract was lower than that in the PBS-extract. ② PBS mainly extracted the soluble chondroitin sulfate proteoglycan (CSPG), whereas the 4mol/L GuHCl could extracted both soluble CSPG and insoluble heparan sulfate proteoglycan (HSPG). ③ After delipidation of brain by organic reagents, the extraction rate of delipidized brain PGs either by the PBS or by the 4mol/L GuHCl decreased obviously. ④ By direct extraction with PBS, GuHCl seguentially, few amount of PGs in the residue from brain was found.

The contribution of proteoglycans to heterogeneity and temozolomide resistance of glioblastoma cells

Aim:Heterogeneity of glioblastoma(GB)cells significantly contributes to tumor resistance against temozolomide(TMZ)and the development of disease relapse.Multiple molecular mechanisms are involved in this process,yet the contribution of proteoglycans(PGs)remains unknown.This study aimed to investigate the potential involvement of PGs(both at core proteins and polysaccharide chains)in the heterogeneity and TMZ resistance of GB cells.Methods:Seven human GB cell lines were characterized for TMZ sensitivity,cell phenotypic traits,gene expression for glucocorticoid receptor(GR,NR3C1),PG core proteins-and heparan sulfate(HS)biosynthesis-related genes and content of their chondroitin sulfate(CS)and HS chains.Results:Although the studied cell lines have similar proliferation rates,they significantly differ in their migration activity,clonogenicity,and TMZ resistance(IC508.51-369.59µM in the line of U343,LN215,HS683,U87,LN71,LN405,LN18),creating a specific phenotype for each cell line.Some PGs(NG2/CSPG4,CSPG5,and versican)contributed to the molecular heterogeneity of these cells being cell line-specifically expressed in all cell lines,which also differed in terms of the CS/HS content.Transcriptional activity of the HS metabolic system was low in these GB cell lines,expressing mainly EXT1/2 and NDST1/2,while expression levels of sulfotransferases and SULF2 were cell line-specific.TMZ resistance of these cells was correlated with the expression of stem-cell marker CD44(+3.5-fold,r=0.73)and GR(-3-fold,r=-0.81).TMZ treatment of the resistant(LN405)and sensitive(LN215)cells resulted in complex changes in cell migration as well as NG2/CSPG4 expression and CS/HS content.Conclusion:Differential expression of PGs and CS/HS content contribute to the heterogeneity of GB cells,and CD44 and NR3C1 might be informative biomarkers for TMZ resistance.

Binding of the SARS-CoV-2 spike protein to glycans

The pandemic of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has caused a high number of deaths in the world.To combat it,it is necessary to develop a better understanding of how the virus infects host cells.Infection normally starts with the attachment of the virus to cell-surface glycans like heparan sulfate(HS)and sialic acid-containing glycolipids/glycoproteins.In this study,we examined and compared the binding of the subunits and spike(S)proteins of SARS-CoV-2,SARS-Co V,and Middle East respiratory disease(MERS)-Co V to these glycans.Our results revealed that the S proteins and subunits can bind to HS in a sulfation-dependent manner and no binding with sialic acid residues was detected.Overall,this work suggests that HS binding may be a general mechanism for the attachment of these coronaviruses to host cells,and supports the potential importance of HS in infection and in the development of antiviral agents against these viruses.

Inhaled heparin polysaccharide nanodecoy against SARS-CoV-2 and variants

To the Editor:As of January 27,2022,there were 363,062,293 cases and 5,645,884deaths from the COVID-19 pandemic1.The prevalent mutated strains have aggravated the global pandemic2.SARS-Co V-2 is highly mutable,and the mutations on the spike(S)protein resulted in a high transmission of COVID-19 and vaccine breakthrough infection3.For example,there is a notable decrease in neutralizing ability of BNT162b2 vaccination-elicited antibodies against the Delta and other variants4,5,and attenuation of peak viral burden and vaccine effectiveness are reduced with Delta variant6.