Loss of 3-O-sulfotransferase enzymes, Hs3st3a1 and Hs3st3b1, reduces kidney and glomerular size and disrupts glomerular architecture

Heparan sulfate (HS) is an important component of the kidney anionic filtration barrier, the glomerular basement membrane (GBM). HS chains attached to proteoglycan protein cores are modified by sulfotransferases in a highly ordered series of biosynthetic steps resulting in immense structural diversity due to negatively charged sulfate modifications. 3-O-sulfation is the least abundant modification generated by a family of seven isoforms but creates the most highly sulfated HS domains. We analyzed the kidney phenotypes in the Hs3st3a1, Hs3st3b1 and Hs3st6 -knockout (KO) mice, the isoforms enriched in kidney podocytes. Individual KO mice show no overt kidney phenotype, although Hs3st3b1 kidneys were smaller than wildtype (WT). Furthermore, Hs3st3a1-/-; Hs3st3b1-/- double knockout (DKO) kidneys were smaller but also had a reduction in glomerular size relative to wildtype (WT). Mass spectrometry analysis of kidney HS showed reduced 3-O-sulfation in Hs3st3a1-/- and Hs3st3b1-/-, but not in Hs3st6-/- kidneys. Glomerular HS showed reduced HS staining and reduced ligand-and-carbohydrate engagement (LACE) assay, a tool that detects changes in binding of growth factor receptor-ligand complexes to HS. Interestingly, DKO mice have increased levels of blood urea nitrogen, although no differences were detected in urinary levels of albumin, creatinine and nephrin. Finally, transmission electron microscopy showed irregular and thickened GBM and podocyte foot process effacement in the DKO compared to WT. Together, our data suggest that loss of 3-O-HS domains disrupts the kidney glomerular architecture without affecting the glomerular filtration barrier and overall kidney function.

GAL3ST1 Deficiency Reduces Epithelial-Mesenchymal Transition and Tumorigenic Capacity in a Cholangiocarcinoma Cell Line

Cholangiocarcinoma (CCA), or bile duct cancer, is the second most common liver malignancy, with an increasing incidence in Western countries. The lack of effective treatments associated with the absence of early symptoms highlights the need to search for new therapeutic targets for CCA. Sulfatides (STs), a type of sulfoglycosphingolipids, have been found in the biliary tract, with increased levels in CCA and other types of cancer. STs are involved in protein trafficking and cell adhesion as part of the lipid rafts of the plasma membrane. We aimed to study the role of STs in CCA by the genetic targeting of GAL3ST1, an enzyme involved in ST synthesis. We used the CRISPR-Cas9 system to generate GAL3ST1-deficient TFK1 cells. GAL3ST1 KO cells showed lower proliferation and clonogenic activity and reduced glycolytic activity compared to TFK1 cells. Polarized TFK1 GAL3ST1 KO cells displayed increased transepithelial resistance and reduced permeability compared to TFK1 wt cells. The loss of GAL3ST1 showed a negative effect on growth in 30 out of 34 biliary tract cancer cell lines from the DepMap database. GAL3ST1 deficiency partially restored epithelial identity and barrier function and reduced proliferative activity in CCA cells. Sulfatide synthesis may provide a novel therapeutic target for CCA.

Adult-onset CNS myelin sulfatide deficiency is sufficient to cause Alzheimer's disease-like neuroinflammation and cognitive impairment

BACKGROUND

Human genetic association studies point to immune response and lipid metabolism, in addition to amyloid-beta (Aβ) and tau, as major pathways in Alzheimer's disease (AD) etiology. Accumulating evidence suggests that chronic neuroinflammation, mainly mediated by microglia and astrocytes, plays a causative role in neurodegeneration in AD. Our group and others have reported early and dramatic losses of brain sulfatide in AD cases and animal models that are mediated by ApoE in an isoform-dependent manner and accelerated by Aβ accumulation. To date, it remains unclear if changes in specific brain lipids are sufficient to drive AD-related pathology.

METHODS

To study the consequences of CNS sulfatide deficiency and gain insights into the underlying mechanisms, we developed a novel mouse model of adult-onset myelin sulfatide deficiency, i.e., tamoxifen-inducible myelinating glia-specific cerebroside sulfotransferase (CST) conditional knockout mice (CSTfl/fl/Plp1-CreERT), took advantage of constitutive CST knockout mice (CST-/-), and generated CST/ApoE double knockout mice (CST-/-/ApoE-/-), and assessed these mice using a broad range of methodologies including lipidomics, RNA profiling, behavioral testing, PLX3397-mediated microglia depletion, mass spectrometry (MS) imaging, immunofluorescence, electron microscopy, and Western blot.

RESULTS

We found that mild central nervous system (CNS) sulfatide losses within myelinating cells are sufficient to activate disease-associated microglia and astrocytes, and to increase the expression of AD risk genes (e.g., Apoe, Trem2, Cd33, and Mmp12), as well as previously established causal regulators of the immune/microglia network in late-onset AD (e.g., Tyrobp, Dock, and Fcerg1), leading to chronic AD-like neuroinflammation and mild cognitive impairment. Notably, neuroinflammation and mild cognitive impairment showed gender differences, being more pronounced in females than males. Subsequent mechanistic studies demonstrated that although CNS sulfatide losses led to ApoE upregulation, genetically-induced myelin sulfatide deficiency led to neuroinflammation independently of ApoE. These results, together with our previous studies (sulfatide deficiency in the context of AD is mediated by ApoE and accelerated by Aβ accumulation) placed both Aβ and ApoE upstream of sulfatide deficiency-induced neuroinflammation, and suggested a positive feedback loop where sulfatide losses may be amplified by increased ApoE expression. We also demonstrated that CNS sulfatide deficiency-induced astrogliosis and ApoE upregulation are not secondary to microgliosis, and that astrogliosis and microgliosis seem to be driven by activation of STAT3 and PU.1/Spi1 transcription factors, respectively.

CONCLUSION

Our results strongly suggest that sulfatide deficiency is an important contributor and driver of neuroinflammation and mild cognitive impairment in AD pathology.

Analysis of A4gnt Knockout Mice Reveals an Essential Role for Gastric Sulfomucins in Preventing Gastritis Cystica Profunda

Gastric adenocarcinoma cells secrete sulfomucins, but their role in gastric tumorigenesis remains unclear. To address that question, we generated A4gnt/Chst4 double-knockout (DKO) mice by crossing A4gnt knockout (KO) mice, which spontaneously develop gastric adenocarcinoma, with Chst4 KO mice, which are deficient in the sulfotransferase GlcNAc6ST-2. A4gnt/Chst4 DKO mice lack gastric sulfomucins but developed gastric adenocarcinoma. Unexpectedly, severe gastric erosion occurred in A4gnt/Chst4 DKO mice at as early as 3 weeks of age, and with aging these lesions were accompanied by gastritis cystica profunda (GCP). Cxcl1, Cxcl5, Ccl2, and Cxcr2 transcripts in gastric mucosa of 5-week-old A4gnt/Chst4 DKO mice exhibiting both hyperplasia and severe erosion were significantly upregulated relative to age-matched A4gnt KO mice, which showed hyperplasia alone. However, upregulation of these genes disappeared in 50-week-old A4gnt/Chst4 DKO mice exhibiting high-grade dysplasia/adenocarcinoma and GCP. Moreover, Cxcl1 and Cxcr2 were downregulated in A4gnt/Chst4 DKO mice relative to age-matched A4gnt KO mice exhibiting adenocarcinoma alone. These combined results indicate that the presence of sulfomucins prevents severe gastric erosion followed by GCP in A4gnt KO mice by transiently regulating a set of inflammation-related genes, Cxcl1, Cxcl5, Ccl2, and Cxcr2 at 5 weeks of age, although sulfomucins were not directly associated with gastric cancer development.

HS6ST1 Insufficiency Causes Self-Limited Delayed Puberty in Contrast With Other GnRH Deficiency Genes

CONTEXT

Self-limited delayed puberty (DP) segregates in an autosomal-dominant pattern, but the genetic basis is largely unknown. Although DP is sometimes seen in relatives of patients with hypogonadotropic hypogonadism (HH), mutations in genes known to cause HH that segregate with the trait of familial self-limited DP have not yet been identified.

OBJECTIVE

To assess the contribution of mutations in genes known to cause HH to the phenotype of self-limited DP.

DESIGN, PATIENTS, AND SETTING

We performed whole-exome sequencing in 67 probands and 93 relatives from a large cohort of familial self-limited DP, validated the pathogenicity of the identified gene variant in vitro, and examined the tissue expression and functional requirement of the mouse homolog in vivo.

RESULTS

A potentially pathogenic gene variant segregating with DP was identified in 1 of 28 known HH genes examined. This pathogenic variant occurred in HS6ST1 in one pedigree and segregated with the trait in the six affected members with heterozygous transmission (P = 3.01 × 10-5). Biochemical analysis showed that this mutation reduced sulfotransferase activity in vitro. Hs6st1 mRNA was expressed in peripubertal wild-type mouse hypothalamus. GnRH neuron counts were similar in Hs6st1+/- and Hs6st1+/+ mice, but vaginal opening was delayed in Hs6st1+/- mice despite normal postnatal growth.

CONCLUSIONS

We have linked a deleterious mutation in HS6ST1 to familial self-limited DP and show that heterozygous Hs6st1 loss causes DP in mice. In this study, the observed overlap in potentially pathogenic mutations contributing to the phenotypes of self-limited DP and HH was limited to this one gene.

Airway glycomic and allergic inflammatory consequences resulting from keratan sulfate galactose 6-O-sulfotransferase (CHST1) deficiency

Siglec-F is a pro-apoptotic receptor on mouse eosinophils that recognizes 6'-sulfated sialyl Lewis X and 6'-sulfated sialyl N-acetyl-lactosamine as well as multivalent sialyl N-acetyl-lactosamine structures on glycan arrays. We hypothesized that attenuation of the carbohydrate sulfotransferase 1 (CHST1) gene encoding keratan sulfate galactose 6-O-sulfotransferase, an enzyme likely required for 6'-sulfation of some of these putative Siglec-F glycan ligands, would result in decreased Siglec-F lung ligand levels and enhanced allergic eosinophilic airway inflammation. Tissue analysis detected CHST1 expression predominantly not only in parenchymal cells but not in airway epithelium, the latter being a location where Siglec-F ligands are located. Western blotting of lung extracts with Siglec-F-Fc fusion proteins detected ≈500 kDa and ≈200 kDa candidate Siglec-F ligands that were not appreciably altered in CHST1-/- lungs compared with normal mouse lungs. Characterization of the O-linked glycans of lung tissue and bronchoalveolar lavage fluid detected altered sialylation but minimal change in sulfation. Eosinophilic airway inflammation was induced in wild-type (WT) and CHST1-/- mice via sensitization to ovalbumin (OVA) and repeated airway challenge. After OVA sensitization and challenge, Siglec-F ligands on airway cells, and numbers of eosinophils and neutrophils accumulating in the airways, both increased to a similar degree in WT and CHST1-/- mouse lungs, while macrophages and lymphocytes increased significantly more in CHST1-/- mouse airway compared with normal mouse lungs. Therefore, keratan sulfate galactose 6-O-sulfotransferase does not contribute to the synthesis of glycan ligands for Siglec-F in the airways, although its absence results in exaggerated accumulation of airway macrophages and lymphocytes.

Pivotal Role of Carbohydrate Sulfotransferase 15 in Fibrosis and Mucosal Healing in Mouse Colitis

Induction of mucosal healing (MH) is an important treatment goal in inflammatory bowel disease (IBD). Although the molecular mechanisms underlying MH in IBD is not fully explored, local fibrosis would contribute to interfere mucosal repair. Carbohydrate sulfotransferase 15 (CHST15), which catalyzes sulfation of chondroitin sulfate to produce rare E-disaccharide units, is a novel mediator to create local fibrosis. Here we have used siRNA-based approach of silencing CHST15 in dextran sulfate sodium (DSS) induced colitis in mice, human colon fibroblasts and cancer cell lines. In a DSS-induced acute colitis model, CHST15 siRNA reduced CHST15 mRNA in the colon, serum IL-6, disease activity index (DAI) and accumulation of F4/80+ macrophages and ER-TR7+ fibroblasts, while increased Ki-67+ epithelial cells. In DSS-induced chronic colitis models, CHST15 siRNA reduced CHST15 mRNA in the colon, DAI, alpha-smooth muscle actin+ fibroblasts and collagen deposition, while enhanced MH as evidenced by reduced histological and endoscopic scores. We also found that endoscopic submucosal injection achieved effective pancolonic delivery of CHST15 siRNA in mice. In human CCD-18 Co cells, CHST15 siRNA inhibited the expression of CHST15 mRNA and selectively reduced E-units, a specific product biosynthesized by CHST15, in the culture supernatant. CHST15 siRNA significantly suppressed vimentin in both TGF-ß-stimulated CCD18-Co cells and HCT116 cells while up-regulated BMP7 and E-cadherin in HCT116 cells. The present study demonstrated that blockade CHST15 represses colonic fibrosis and enhances MH partly though reversing EMT pathway, illustrating a novel therapeutic opportunity to refractory and fibrotic lesions in IBD.

SERPINI1 regulates epithelial-mesenchymal transition in an orthotopic implantation model of colorectal cancer

An increasingly accepted concept is that the progression of colorectal cancer is accompanied by epithelial-mesenchymal transition (EMT). In our study, in order to characterize the properties of EMT in 16 colorectal cancer cell lines, the cells were first orthotopically implanted into nude mice, and the tumors in vivo, as well as cells cultured in vitro, were immunostained for EMT markers. The immunostaining revealed that seven of the cells had an epithelial phenotype with a high expression of E-cadherin, whereas other cells showed opposite patterns, such as a high expression of vimentin (CX-1, COLO205, CloneA, HCT116, and SW48). Among the cells expressing vimentin, some expressed vimentin in the orthotopic tumors but not in the cultured cells (SW480, SW620, and COLO320). We evaluated these findings in combination with microarray analyses, and selected five genes: CHST11, SERPINI1, AGR2, FBP1, and FOXA1. Next, we downregulated the expression of SERPINI1 with siRNA in the cells, the results of which showed reverse-EMT changes at the protein level and in the cellular morphology. Along with immunohistochemical analyses, we confirmed the effect of the intracellular and secreted SERPINI1 protein of SW620 cells, which supported the importance of SERPINI1 in EMT. The development of therapeutic strategies targeting EMT is ongoing, including methods targeting the transforming growth factor-β signaling pathway as well as the Wnt pathway. SERPINI1 is an important regulator of EMT. Our findings help to elucidate the signaling pathways of EMT, hopefully clarifying therapeutic pathways as well.

Germline ablation of dermatan-4O-sulfotransferase1 reduces regeneration after mouse spinal cord injury

Chondroitin/dermatan sulfate proteoglycans (CSPGs/DSPGs) are major components of the extracellular matrix. Their expression is generally upregulated after injuries to the adult mammalian central nervous system, which is known for its low ability to restore function after injury. Several studies support the view that CSPGs inhibit regeneration after injury, whereas the functions of DSPGs in injury paradigms are less certain. To characterize the functions of DSPGs in the presence of CSPGs, we studied young adult dermatan-4O-sulfotransferase1-deficient (Chst14(-/-)) mice, which express chondroitin sulfates (CSs), but not dermatan sulfates (DSs), to characterize the functional outcome after severe compression injury of the spinal cord. In comparison to their wild-type (Chst14(+/+)) littermates, regeneration was reduced in Chst14(-/-) mice. No differences between genotypes were seen in the size of spinal cords, numbers of microglia and astrocytes neither in intact nor injured spinal cords after injury. Monoaminergic innervation and re-innervation of the spinal cord caudal to the lesion site as well as expression levels of glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) were similar in both genotypes, independent of whether they were injured and examined 6weeks after injury or not injured. These results suggest that, in contrast to CSPGs, DSPGs, being the products of Chst14 enzymatic activity, promote regeneration after injury of the adult mouse central nervous system.

Keratan sulfate exacerbates experimental autoimmune encephalomyelitis

Proteoglycans (PGs) are the components of extracellular matrices in the central nervous system (CNS). Keratan sulfate (KS) is a glycosaminoglycan that is included in the KSPG that acts as an inhibitory factor in nerve regeneration after CNS injury. To investigate the role of KS in immune diseases, we induced experimental autoimmune encephalomyelitis (EAE) in mice that were deficient in the N-acetylglucosamine (GlcNAc)-6-O-sulfotransferase 1 (GlcNAc6ST1) gene (KS-KO). KS-KO mice developed less severe EAE and showed repressed recall response in the induction phase. Furthermore, GlcNAc6ST1 might have roles in the passage of the pathogenic lymphocytes through the blood-brain barrier via adhesion molecules. Thus, modulation of KS may become a treatment for neuroimmunological diseases.

Requirement of keratan sulfate proteoglycan phosphacan with a specific sulfation pattern for critical period plasticity in the visual cortex

Proteoglycans play important roles in regulating the development and functions of the brain. They consist of a core protein and glycosaminoglycans, which are long sugar chains of repeating disaccharide units with sulfation. A recent study demonstrated that the sulfation pattern of chondroitin sulfate on proteoglycans contributes to regulation of the critical period of experience-dependent plasticity in the mouse visual cortex. In the present study, we investigated the role of keratan sulfate (KS), another glycosaminoglycan, in critical period plasticity in the mouse visual cortex. Immunohistochemical analyses demonstrated the presence of KS containing disaccharide units of N-acetylglucosamine (GlcNAc)-6-sulfate and nonsulfated galactose during the critical period, although KS containing disaccharide units of GlcNAc-6-sulfate and galactose-6-sulfate was already known to disappear before that period. The KS chains were distributed diffusely in the extracellular space and densely around the soma of a large population of excitatory and inhibitory neurons. Electron microscopic analysis revealed that the KS was localized within the perisynaptic spaces and dendrites but not in presynaptic sites. KS was mainly located on phosphacan. In mice deficient in GlcNAc-6-O-sulfotransferase 1, which is one of the enzymes necessary for the synthesis of KS chains, the expression of KS was one half that in wild-type mice. In the knockout mice, monocular deprivation during the critical period resulted in a depression of deprived-eye responses but failed to produce potentiation of nondeprived-eye responses. In addition, T-type Ca(2+) channel-dependent long-term potentiation (LTP), which occurs only during the critical period, was not observed. These results suggest that regulation by KS-phosphacan with a specific sulfation pattern is necessary for the generation of LTP and hence the potentiation of nondeprived-eye responses after monocular deprivation.

Keratan sulfate: biosynthesis, structures, and biological functions

Keratan sulfate is a glycosaminoglycan that has been investigated in the cornea and skeletal tissues for decades. Endoglycosidases and monoclonal antibodies specific for keratan sulfate have been developed. These materials have facilitated the analysis of keratan sulfate biosynthesis and structures. Likewise, they have expedited study of the biological roles of keratan sulfate in vitro and in vivo. It has been shown that keratan sulfate is also expressed in the central nervous system and functions as a regulator of neuronal regeneration/sprouting. Here, we describe methods to determine the enzymatic activity of GlcNAc6ST, which is involved in keratan sulfate biosynthesis, and to extract and prepare ocular keratan sulfate for a disaccharide composition analysis. Immunohistochemistry for an anti-keratan sulfate epitope in the brain is also described.

Vascular biomechanical properties in mice with smooth muscle specific deletion of Ndst1

Heparan sulfate proteoglycans act as co-receptors for many chemokines and growth factors. The sulfation pattern of the heparan sulfate chains is a critical regulatory step affecting the binding of chemokines and growth factors. N-deacetylase-N-sulfotransferase1 (Ndst1) is one of the first enzymes to catalyze sulfation. Previously published work has shown that HSPGs alter tangent moduli and stiffness of tissues and cells. We hypothesized that loss of Ndst1 in smooth muscle would lead to significant changes in heparan sulfate modification and the elastic properties of arteries. In line with this hypothesis, the axial tangent modulus was significantly decreased in aorta from mice lacking Ndst1 in smooth muscle (SM22αcre(+)Ndst1(-/-), p < 0.05, n = 5). The decrease in axial tangent modulus was associated with a significant switch in myosin and actin types and isoforms expressed in aorta and isolated aortic vascular smooth muscle cells. In contrast, no changes were found in the compliance of smaller thoracodorsal arteries of SM22αcre(+)Ndst1(-/-) mice. In summary, the major findings of this study were that targeted ablation of Ndst1 in smooth muscle cells results in altered biomechanical properties of aorta and differential expression of myosin and actin types and isoforms.

Heparan sulfate deficiency disrupts developmental angiogenesis and causes congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth malformation with a heterogeneous etiology. In this study, we report that ablation of the heparan sulfate biosynthetic enzyme NDST1 in murine endothelium (Ndst1ECKO mice) disrupted vascular development in the diaphragm, which led to hypoxia as well as subsequent diaphragm hypoplasia and CDH. Intriguingly, the phenotypes displayed in Ndst1ECKO mice resembled the developmental defects observed in slit homolog 3 (Slit3) knockout mice. Furthermore, introduction of a heterozygous mutation in roundabout homolog 4 (Robo4), the gene encoding the cognate receptor of SLIT3, aggravated the defect in vascular development in the diaphragm and CDH. NDST1 deficiency diminished SLIT3, but not ROBO4, binding to endothelial heparan sulfate and attenuated EC migration and in vivo neovascularization normally elicited by SLIT3-ROBO4 signaling. Together, these data suggest that heparan sulfate presentation of SLIT3 to ROBO4 facilitates initiation of this signaling cascade. Thus, our results demonstrate that loss of NDST1 causes defective diaphragm vascular development and CDH and that heparan sulfate facilitates angiogenic SLIT3-ROBO4 signaling during vascular development.

Epigenetic inactivation of heparan sulfate (glucosamine) 3-O-sulfotransferase 2 in lung cancer and its role in tumorigenesis

Background

This study was aimed at investigating the functional significance of heparan sulfate (glucosamine) 3-O-sulfotransferase 2 (HS3ST2) hypermethylation in non-small cell lung cancer (NSCLC).

Methodology/ Principal Findings

HS3ST2 hypermethylation was characterized in six lung cancer cell lines, and its clinical significance was analyzed using 298 formalin-fixed paraffin-embedded tissues and 26 fresh-frozen tissues from 324 NSCLC patients. MS-HRM (methylation-specific high-resolution melting) and EpiTYPER^TM assays showed substantial hypermethylation of CpG island at the promoter region of HS3ST2 in six lung cancer cell lines. The silenced gene was demethylated and re-expressed by treatment with 5-aza-2′-deoxycytidine (5-Aza-dC). A promoter assay also showed the core promoter activity of HS3ST2 was regulated by methylation. Exogenous expression of HS3ST2 in lung cancer cells H460 and H23 inhibited cell migration, invasion, cell proliferation and whereas knockdown of HS3ST2 in NHBE cells induced cell migration, invasion, and cell proliferation invitro. A negative correlation was observed between mRNA and methylation levels of HS3ST2 in 26 fresh-frozen tumors tissues (ρ = -0.51, P = 0.009; Spearman’s rank correlation). HS3ST2 hypermethylation was found in 95 (32%) of 298 primary NSCLCs. Patients with HS3ST2 hypermethylation in 193 node-negative stage I-II NSCLCs with a median follow-up period of 5.8 years had poor overall survival (hazard ratio = 2.12, 95% confidence interval = 1.25–3.58, P = 0.005) compared to those without HS3ST2 hypermethylation, after adjusting for age, sex, tumor size, adjuvant therapy, recurrence, and differentiation.

Conclusions/ Significance

The present study suggests that HS3ST2 hypermethylation may be an independent prognostic indicator for overall survival in node-negative stage I-II NSCLC.

Dermatan 4-O-sulfotransferase1 ablation accelerates peripheral nerve regeneration

Chondroitin sulfate (CS) and dermatan sulfate (DS) proteoglycans are major components of the extracellular matrix implicated in neural development, plasticity and regeneration. While it is accepted that CS are major inhibitors of neural regeneration, the contributions of DS to regeneration have not been assessed. To enable a novel approach in studies on DS versus CS roles during development and regeneration, we generated a mouse deficient in the dermatan 4-O-sulfotransferase1 (Chst14(-/-)), a key enzyme in the synthesis of iduronic acid-containing modules found in DS but not CS. In wild-type mice, Chst14 is expressed at high levels in the skin and in the nervous system, and is enriched in astrocytes and Schwann cells. Ablation of Chst14, and the assumed failure to produce DS, resulted in smaller body mass, reduced fertility, kinked tail and increased skin fragility compared with wild-type (Chst14(+/+)) littermates, but brain weight and gross anatomy were unaffected. Neurons and Schwann cells from Chst14(-/-) mice formed longer processes in vitro, and Chst14(-/-) Schwann cells proliferated more than Chst14(+/+) Schwann cells. After femoral nerve transection/suture, functional recovery and axonal regrowth in Chst14(-/-) mice were initially accelerated but the final outcome 3months after injury was not better than that in Chst14(+/+) littermates. These results suggest that while Chst14 and its enzymatic products might be of limited importance for neural development, they may contribute to the regeneration-restricting environment in the adult mammalian nervous system.

Ablation of keratan sulfate accelerates early phase pathogenesis of ALS

Biopolymers consist of three major classes, i.e., polynucleotides (DNA, RNA), polypeptides (proteins) and polysaccharides (sugar chains). It is widely accepted that polynucleotides and polypeptides play fundamental roles in the pathogenesis of neurodegenerative diseases. But, sugar chains have been poorly studied in this process, and their biological/clinical significance remains largely unexplored. Amyotrophic lateral sclerosis (ALS) is a motoneuron-degenerative disease, the pathogenesis of which requires both cell autonomous and non-cell autonomous processes. Here, we investigated the role of keratan sulfate (KS), a sulfated long sugar chain of proteoglycan, in ALS pathogenesis. We employed ALS model SOD1(G93A) mice and GlcNAc6ST-1(-/-) mice, which are KS-deficient in the central nervous system. Unexpectedly, SOD1(G93A)GlcNAc6ST-1(-/-) mice exhibited a significantly shorter lifespan than SOD1(G93A) mice and an accelerated appearance of clinical symptoms (body weight loss and decreased rotarod performance). KS expression was induced exclusively in a subpopulation of microglia in SOD1(G93A) mice, and became detectable around motoneurons in the ventral horn during the early disease phase before body weight loss. During this phase, the expression of M2 microglia markers was transiently enhanced in SOD1(G93A) mice, while this enhancement was attenuated in SOD1(G93A)GlcNAc6ST-1(-/-) mice. Consistent with this, M2 microglia were markedly less during the early disease phase in SOD1(G93A)GlcNAc6ST-1(-/-) mice. Moreover, KS expression in microglia was also detected in some human ALS cases. This study suggests that KS plays an indispensable, suppressive role in the early phase pathogenesis of ALS and may represent a new target for therapeutic intervention.

NDST4 is a novel candidate tumor suppressor gene at chromosome 4q26 and its genetic loss predicts adverse prognosis in colorectal cancer

Background

Genomic deletion at tumor suppressor loci is a common genetic aberration in human cancers. The study aimed to explore candidate tumor suppressor genes at chromosome 4q25-q28.2 and to delineate novel prognostic biomarkers associated with colorectal cancer (CRC).

Methods

Deletion mapping of chromosome 4q25-q28.2 was conducted in 114 sporadic CRC by loss of heterozygosity study with 11 microsatellite markers. A novel candidate tumor suppressor gene, namely NDST4, was identified at 4q26. Gene expression of NDST4 was investigated in 52 pairs of primary CRC tissues by quantitative reverse transcription-polymerase chain reaction. Allelic loss of NDST4 gene was further determined in 174 colorectal carcinomas by loss of heterozygosity analysis, and then was assessed for clinical relevance.

Results

One minimal deletion region was delineated between D4S2297 and D4S2303 loci at 4q26, where NDST4 was the only gene that had markedly been downregulated in CRC tumors. By laser capture microdissection, NDST4 RNA expression was demonstrated in colonic epithelial cells, but was undetectable in tumor cells. In total, 30 (57.7%) of 52 colorectal carcinomas showed a dramatic reduction in NDST4 gene expression compared with matched normal mucosae. The genetic loss of NDST4 was significantly associated with advanced pathological stage (P = 0.039) and poorer overall survival of patients (P = 0.036).

Conclusions

NDST4 gene is a novel candidate tumor suppressor gene in human cancer, and the loss of its function might be involved in CRC progression. In addition, the loss of heterozygosity assay, which was established to determine the allelic loss of NDST4 gene, could be a cost-effective tool for providing a useful biomarker of adverse prognosis in CRC.

6-Sulphated chondroitins have a positive influence on axonal regeneration

Chondroitin sulphate proteoglycans (CSPGs) upregulated in the glial scar inhibit axon regeneration via their sulphated glycosaminoglycans (GAGs). Chondroitin 6-sulphotransferase-1 (C6ST-1) is upregulated after injury leading to an increase in 6-sulphated GAG. In this study, we ask if this increase in 6-sulphated GAG is responsible for the increased inhibition within the glial scar, or whether it represents a partial reversion to the permissive embryonic state dominated by 6-sulphated glycosaminoglycans (GAGs). Using C6ST-1 knockout mice (KO), we studied post-injury changes in chondroitin sulphotransferase (CSST) expression and the effect of chondroitin 6-sulphates on both central and peripheral axon regeneration. After CNS injury, wild-type animals (WT) showed an increase in mRNA for C6ST-1, C6ST-2 and C4ST-1, but KO did not upregulate any CSSTs. After PNS injury, while WT upregulated C6ST-1, KO showed an upregulation of C6ST-2. We examined regeneration of nigrostriatal axons, which demonstrate mild spontaneous axon regeneration in the WT. KO showed many fewer regenerating axons and more axonal retraction than WT. However, in the PNS, repair of the median and ulnar nerves led to similar and normal levels of axon regeneration in both WT and KO. Functional tests on plasticity after the repair also showed no evidence of enhanced plasticity in the KO. Our results suggest that the upregulation of 6-sulphated GAG after injury makes the extracellular matrix more permissive for axon regeneration, and that the balance of different CSs in the microenvironment around the lesion site is an important factor in determining the outcome of nervous system injury.

Increased numbers of oligodendrocyte lineage cells in the optic nerves of cerebroside sulfotransferase knockout mice

Sulfatide is a myelin glycolipid that functions in the formation of paranodal axo-glial junctions in vivo and in the regulation of oligodendrocyte differentiation in vitro. Cerebroside sulfotransferase (CST) catalyzes the production of two sulfated glycolipids, sulfatide and proligodendroblast antigen, in oligodendrocyte lineage cells. Recent studies have demonstrated significant increases in oligodendrocytes from the myelination stage through adulthood in brain and spinal cord under CST-deficient conditions. However, whether these result from excess migration or in situ proliferation during development is undetermined. In the present study, CST-deficient optic nerves were used to examine migration and proliferation of oligodendrocyte precursor cells (OPCs) under sulfated glycolipid-deficient conditions. In adults, more NG2-positive OPCs and fully differentiated cells were observed. In developing optic nerves, the number of cells at the leading edge of migration was similar in CST-deficient and wild-type mice. However, BrdU(+) proliferating OPCs were more abundant in CST-deficient mice. These results suggest that sulfated glycolipids may be involved in proliferation of OPCs in vivo.

Phenotypic features of carbohydrate sulfotransferase 3 (CHST3) deficiency in 24 patients: congenital dislocations and vertebral changes as principal diagnostic features

We recently reported on the deficiency of carbohydrate sulfotransferase 3 (CHST3; chondroitin-6-sulfotransferase) in six subjects diagnosed with recessive Larsen syndrome or humero-spinal dysostosis [Hermanns et al. (2008); Am J Hum Genet 82:1368-1374]. Since then, we have identified 17 additional families with CHST3 mutations and we report here on a series of 24 patients in 23 families. The diagnostic hypothesis prior to molecular analysis had been: Larsen syndrome (15 families), humero-spinal dysostosis (four cases), chondrodysplasia with multiple dislocations (CDMD "Megarbane type"; two cases), Desbuquois syndrome (one case), and spondylo-epiphyseal dysplasia (one case). In spite of the different diagnostic labels, the clinical features in these patients were similar and included dislocation of the knees and/or hips at birth, clubfoot, elbow joint dysplasia with subluxation and limited extension, short stature, and progressive kyphosis developing in late childhood. The most useful radiographic clues were the changes of the lumbar vertebrae. Twenty-four different CHST3 mutations were identified; 16 patients had homozygous mutations. We conclude that CHST3 deficiency presents at birth with congenital dislocations of knees, hips, and elbows, and is often diagnosed initially as Larsen syndrome, humero-spinal dysostosis, or chondrodysplasia with dislocations. The incidence of CHST3 deficiency seems to be higher than assumed so far. The clinical and radiographic pattern (joint dislocations, vertebral changes, normal carpal age, lack of facial flattening, and recessive inheritance) is characteristic and distinguishes CHST3 deficiency from other disorders with congenital dislocations such as filamin B-associated dominant Larsen syndrome and Desbuquois syndrome.

Loss of the heparan sulfate sulfotransferase, Ndst1, in mammary epithelial cells selectively blocks lobuloalveolar development in mice

BACKGROUND

Considerable evidence indicates that heparan sulfate is essential for the development of tissues consisting of branching ducts and tubules. However, there are few examples where specific sulfate residues regulate a specific stage in the formation of such tissues.

METHODOLOGY/PRINCIPAL FINDINGS

We examined the role of heparan sulfation in mammary gland branching morphogenesis, lactation and lobuloalveolar development by inactivation of heparan sulfate GlcNAc N-deacetylase/N-sulfotransferase genes (Ndst) in mammary epithelial cells using the Cre-loxP system. Ndst1 deficiency resulted in an overall reduction in glucosamine N-sulfation and decreased binding of FGF to mammary epithelial cells in vitro and in vivo. Mammary epithelia lacking Ndst1 underwent branching morphogenesis, filling the gland with ductal tissue by sexual maturity to the same extent as wildtype epithelia. However, lobuloalveolar expansion did not occur in Ndst1-deficient animals, resulting in insufficient milk production to nurture newly born pups. Lactational differentiation of isolated mammary epithelial cells occurred appropriately via stat5 activation, further supporting the notion that the lack of milk production was due to lack of expansion of the lobuloalveoli.

CONCLUSIONS/SIGNIFICANCE

These findings demonstrate a selective, highly penetrant, cell autonomous effect of Ndst1-mediated sulfation on lobuloalveolar development.

Inhibition of chemokine-glycosaminoglycan interactions in donor tissue reduces mouse allograft vasculopathy and transplant rejection

BACKGROUND

Binding of chemokines to glycosaminoglycans (GAGs) is classically described as initiating inflammatory cell migration and creating tissue chemokine gradients that direct local leukocyte chemotaxis into damaged or transplanted tissues. While chemokine-receptor binding has been extensively studied during allograft transplantation, effects of glycosaminoglycan (GAG) interactions with chemokines on transplant longevity are less well known. Here we examine the impact of interrupting chemokine-GAG interactions and chemokine-receptor interactions, both locally and systemically, on vascular disease in allografts.

METHODOLOGY/PRINCIPAL FINDINGS

Analysis of GAG or CC chemokine receptor 2 (CCR2) deficiency were coupled with the infusion of viral chemokine modulating proteins (CMPs) in mouse aortic allograft transplants (n = 239 mice). Inflammatory cell invasion and neointimal hyperplasia were significantly reduced in N-deacetylase-N-sulfotransferase-1 (Ndst1(f/f)TekCre(+)) heparan sulfate (GAG)-deficient (Ndst1(-/-), p<0.044) and CCR2-deficient (Ccr2(-/-), p<0.04) donor transplants. Donor tissue GAG or CCR2 deficiency markedly reduced inflammation and vasculopathy, whereas recipient deficiencies did not. Treatment with three CMPs was also investigated; Poxviral M-T1 blocks CC chemokine receptor binding, M-T7 blocks C, CC, and CXC GAG binding, and herpesviral M3 binds receptor and GAG binding for all classes. M-T7 reduced intimal hyperplasia in wild type (WT) (Ccr2(+/+), p< or =0.003 and Ccr2(-/-), p

CONCLUSIONS/SIGNIFICANCE

Interruption of chemokine-GAG interactions, even in the absence of chemokine-receptor blockade, is a highly effective approach to reduction of allograft rejection, reducing vascular inflammation and prolonging allograft survival. Although chemokines direct both local and systemic cell migration, interruption of inherent chemokine responses in the donor tissue unexpectedly had a greater therapeutic impact on allograft vasculopathy.

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MESH Headings

• Animals
• Aorta/drug effects
• Aorta/pathology
• Aorta/transplantation
• Cell Movement/drug effects
• Cell Proliferation/drug effects
• Chemokines/metabolism
• Chemokines/pharmacology
• Disease Models, Animal
• Glycosaminoglycans/metabolism
• Graft Rejection/complications
• Graft Rejection/enzymology
• Graft Rejection/immunology
• Hyperplasia
• Inflammation/complications
• Inflammation/pathology
• Kidney Transplantation
• Mice
• Mice, Inbred BALB C
• Mice, Inbred C57BL
• Receptors, CCR2/deficiency
• Receptors, CCR2/metabolism
• Sulfotransferases/deficiency
• Sulfotransferases/metabolism
• Survival Analysis
• Tissue Donors
• Transplantation, Homologous
• Tunica Intima/drug effects
• Tunica Intima/pathology
• Vascular Diseases/complications
• Vascular Diseases/enzymology
• Vascular Diseases/immunology
• Vascular Diseases/pathology
• Viral Proteins/pharmacology

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Grants

• RC1 HL100202 NHLBI NIH HHS
• 1RC1HL100202-01 NHLBI NIH HHS
• MOP 577578 CIHR

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