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.

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.

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.

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.

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.

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.