Publications by authors named "Shuji Mizumoto"

71 Publications

Knock-Out Zebrafish Recapitulate β3GalT6-Deficiency Disorders in Human and Reveal a Trisaccharide Proteoglycan Linkage Region.

Front Cell Dev Biol 2020 10;8:597857. Epub 2020 Dec 10.

Department of Biomolecular Medicine, Center for Medical Genetics Ghent, Ghent University Hospital, Ghent University, Ghent, Belgium.

Proteoglycans are structurally and functionally diverse biomacromolecules found abundantly on cell membranes and in the extracellular matrix. They consist of a core protein linked to glycosaminoglycan chains via a tetrasaccharide linkage region. Here, we show that CRISPR/Cas9-mediated knock-out zebrafish, lacking galactosyltransferase II, which adds the third sugar in the linkage region, largely recapitulate the phenotypic abnormalities seen in human β3GalT6-deficiency disorders. These comprise craniofacial dysmorphism, generalized skeletal dysplasia, skin involvement and indications for muscle hypotonia. In-depth TEM analysis revealed disturbed collagen fibril organization as the most consistent ultrastructural characteristic throughout different affected tissues. Strikingly, despite a strong reduction in glycosaminoglycan content, as demonstrated by anion-exchange HPLC, subsequent LC-MS/MS analysis revealed a small amount of proteoglycans containing a unique linkage region consisting of only three sugars. This implies that formation of glycosaminoglycans with an immature linkage region is possible in a pathogenic context. Our study, therefore unveils a novel rescue mechanism for proteoglycan production in the absence of galactosyltransferase II, hereby opening new avenues for therapeutic intervention.
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http://dx.doi.org/10.3389/fcell.2020.597857DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758351PMC
December 2020

Hyaluronan degradation and release of a hyaluronan-aggrecan complex from perineuronal nets in the aged mouse brain.

Biochim Biophys Acta Gen Subj 2021 Feb 28;1865(2):129804. Epub 2020 Nov 28.

Graduate School of Bioagricultural Sciences, Nagoya University, Furocho, Chikusa-Ku, Nagoya 464-8601, Japan; Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan. Electronic address:

Background: Perineuronal nets (PNNs) are insoluble aggregates of extracellular matrix molecules in the brain that consist of hyaluronan (HA) and chondroitin sulfate proteoglycans (CSPGs). PNNs promote the acquisition and storage of memories by stabilizing the formation of synapses in the adult brain. Although the deterioration of PNNs has been suggested to contribute to the age-dependent decline in brain function, the molecular mechanisms underlying age-related changes in PNNs remain unclear.

Methods: The amount and solubility of PNN components were investigated by sequential extraction followed by a disaccharide analysis and immunoblotting. We examined the interaction between HA and aggrecan, a major HA-binding CSPG, by combining mass spectrometry and pull-down assays.

Results: The solubility and amount of HA increased in the brain with age. Among several CSPGs, the solubility of aggrecan was selectively elevated during aging. In contrast to alternations in biochemical properties, the expression of PNN components at the transcript level was not markedly changed by aging. The increased solubility of aggrecan was not due to the loss of HA-binding properties. Our results indicated that the degradation of high-molecular-mass HA induced the release of the HA-aggrecan complex from PNNs in the aged brain.

Conclusion: The present study revealed a novel mechanism underlying the age-related deterioration of PNNs in the brain.
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http://dx.doi.org/10.1016/j.bbagen.2020.129804DOI Listing
February 2021

Dermatan sulphate promotes neuronal differentiation in mouse and human stem cells.

J Biochem 2021 Feb;169(1):55-64

Department of Bioinformatics, Graduate School of Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, Japan.

Dermatan sulphate (DS), a glycosaminoglycan, is present in the extracellular matrix and on the cell surface. Previously, we showed that heparan sulphate plays a key role in the maintenance of the undifferentiated state in mouse embryonic stem cells (mESCs) and in the regulation of their differentiation. Chondroitin sulphate has also been to be important for pluripotency and differentiation of mESCs. Keratan sulphate is a marker of human pluripotent stem cells. To date, however, the function of DS in mESCs has not been clarified. Dermatan 4 sulfotransferase 1, which transfers sulphate to the C-4 hydroxyl group of N-acetylgalactosamine of DS, contributes to neuronal differentiation of mouse neural progenitor cells. Therefore, we anticipated that neuronal differentiation would be induced in mESCs in culture by the addition of DS. To test this expectation, we investigated neuronal differentiation in mESCs and human neural stem cells (hNSCs) cultures containing DS. In mESCs, DS promoted neuronal differentiation by activation of extracellular signal-regulated kinase 1/2 and also accelerated neurite outgrowth. In hNSCs, DS promoted neuronal differentiation and neuronal migration, but not neurite outgrowth. Thus, DS promotes neuronal differentiation in both mouse and human stem cells, suggesting that it offers a novel method for efficiently inducing neuronal differentiation.
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http://dx.doi.org/10.1093/jb/mvaa087DOI Listing
February 2021

Systematic investigation of the skin in Chst14-/- mice: A model for skin fragility in musculocontractural Ehlers-Danlos syndrome caused by CHST14 variants (mcEDS-CHST14).

Glycobiology 2021 Feb;31(2):137-150

Laboratory of Veterinary Anatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.

Loss-of-function variants in CHST14 cause a dermatan 4-O-sulfotransferase deficiency named musculocontractural Ehlers-Danlos syndrome-CHST14 (mcEDS-CHST14), resulting in complete depletion of the dermatan sulfate moiety of decorin glycosaminoglycan (GAG) chains, which is replaced by chondroitin sulfate. Recently, we uncovered structural alteration of GAG chains in the skin of patients with mcEDS-CHST14. Here, we conducted the first systematic investigation of Chst14 gene-deleted homozygote (Chst14-/-) mice. We used skin samples of wild-type (Chst14+/+) and Chst14-/- mice. Mechanical fragility of the skin was measured with a tensile test. Pathology was observed using light microscopy, decorin immunohistochemistry and electron microscopy (EM) including cupromeronic blue (CB) staining. Quantification of chondroitin sulfate and dermatan sulfate was performed using enzymatic digestion followed by anion-exchange HPLC. In Chst14-/- mice, skin tensile strength was significantly decreased compared with that in Chst14+/+ mice. EM showed that collagen fibrils were oriented in various directions to form disorganized collagen fibers in the reticular layer. Through EM-based CB staining, rod-shaped linear GAG chains were found to be attached at one end to collagen fibrils and protruded outside of the fibrils, in contrast to them being round and wrapping the collagen fibrils in Chst14+/+ mice. A very low level of dermatan sulfate disaccharides was detected in the skin of Chst14-/- mice by anion-exchange chromatography. Chst14-/- mice, exhibiting similar abnormalities in the GAG structure of decorin and collagen networks in the skin, could be a reasonable model for skin fragility of patients with mcEDS-CHST14, shedding light on the role of dermatan sulfate in maintaining skin strength.
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http://dx.doi.org/10.1093/glycob/cwaa058DOI Listing
February 2021

Delineation of musculocontractural Ehlers-Danlos Syndrome caused by dermatan sulfate epimerase deficiency.

Mol Genet Genomic Med 2020 05 4;8(5):e1197. Epub 2020 Mar 4.

Center for Medical Genetics, Shinshu University Hospital, Matsumoto, Japan.

Background: Musculocontractural Ehlers-Danlos Syndrome (mcEDS) is a rare connective tissue disorder caused by biallelic loss-of-function variants in CHST14 (mcEDS-CHST14) or DSE (mcEDS-DSE), both of which result in defective dermatan sulfate biosynthesis. Forty-one patients with mcEDS-CHST14 and three patients with mcEDS-DSE have been described in the literature.

Methods: Clinical, molecular, and glycobiological findings in three additional patients with mcEDS-DSE were investigated.

Results: Three patients from two families shared craniofacial characteristics (hypertelorism, blue sclera, midfacial hypoplasia), skeletal features (pectus and spinal deformities, characteristic finger shapes, progressive talipes deformities), skin features (fine or acrogeria-like palmar creases), and ocular refractive errors. Homozygous pathogenic variants in DSE were found: c.960T>A/p.Tyr320* in patient 1 and c.996dupT/p.Val333Cysfs*4 in patients 2 and 3. No dermatan sulfate was detected in the urine sample from patient 1, suggesting a complete depletion of DS.

Conclusion: McEDS-DSE is a congenital multisystem disorder with progressive symptoms involving craniofacial, skeletal, cutaneous, and cardiovascular systems, similar to the symptoms of mcEDS-CHST14. However, the burden of symptoms seems lower in patients with mcEDS-DSE.
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http://dx.doi.org/10.1002/mgg3.1197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216804PMC
May 2020

Pseudodiastrophic dysplasia expands the known phenotypic spectrum of defects in proteoglycan biosynthesis.

J Med Genet 2020 07 27;57(7):454-460. Epub 2020 Jan 27.

Department of Genetics and Molecular Pathology, Centre for Cancer Biology, An alliance between SA Pathology and the University of South Australia, Adelaide, South Australia, Australia

Background: Pseudodiastrophic dysplasia (PDD) is a severe skeletal dysplasia associated with prenatal manifestation and early lethality. Clinically, PDD is classified as a 'dysplasia with multiple joint dislocations'; however, the molecular aetiology of the disorder is currently unknown.

Methods: Whole exome sequencing (WES) was performed on three patients from two unrelated families, clinically diagnosed with PDD, in order to identify the underlying genetic cause. The functional effects of the identified variants were characterised using primary cells and human cell-based overexpression assays.

Results: WES resulted in the identification of biallelic variants in the established skeletal dysplasia genes, (family 1) and (family 2). Mutations in these genes have previously been reported to cause 'multiple joint dislocations, short stature, and craniofacial dysmorphism with or without congenital heart defects' ('JDSCD'; B3GAT3) and Desbuquois dysplasia 1 (CANT1), disorders in the same nosological group as PDD. Follow-up of the variants demonstrated significantly reduced B3GAT3/GlcAT-I expression. Downstream functional analysis revealed abolished biosynthesis of glycosaminoglycan side chains on proteoglycans. Functional evaluation of the variant showed impaired nucleotidase activity, which results in inhibition of glycosaminoglycan synthesis through accumulation of uridine diphosphate.

Conclusion: For the families described in this study, the PDD phenotype was caused by mutations in the known skeletal dysplasia genes and , demonstrating the advantage of genomic analyses in delineating the molecular diagnosis of skeletal dysplasias. This finding expands the phenotypic spectrum of B3GAT3-related and CANT1-related skeletal dysplasias to include PDD and highlights the significant phenotypic overlap of conditions within the proteoglycan biosynthesis pathway.
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http://dx.doi.org/10.1136/jmedgenet-2019-106700DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7361035PMC
July 2020

Recent Advances in the Pathophysiology of Musculocontractural Ehlers-Danlos Syndrome.

Genes (Basel) 2019 12 29;11(1). Epub 2019 Dec 29.

Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, Nagoya 468-8503, Japan.

Musculocontractural Ehlers-Danlos Syndome (mcEDS) is a type of EDS caused by biallelic pathogenic variants in the gene for carbohydrate sulfotransferase 14/dermatan 4--sulfotransferase 1 (/, mcEDS-), or in the gene for dermatan sulfate epimerase (, mcEDS-). Thus far, 41 patients from 28 families with mcEDS- and five patients from four families with mcEDS- have been described in the literature. Clinical features comprise multisystem congenital malformations and progressive connective tissue fragility-related manifestations. This review outlines recent advances in understanding the pathophysiology of mcEDS. Pathogenic variants in or lead to reduced activities of relevant enzymes, resulting in a negligible amount of dermatan sulfate (DS) and an excessive amount of chondroitin sulfate. Connective tissue fragility is presumably attributable to a compositional change in the glycosaminoglycan chains of decorin, a major DS-proteoglycan in the skin that contributes to collagen fibril assembly. Collagen fibrils in affected skin are dispersed in the papillary to reticular dermis, whereas those in normal skin are regularly and tightly assembled. Glycosaminoglycan chains are linear in affected skin, stretching from the outer surface of collagen fibrils to adjacent fibrils; glycosaminoglycan chains are curved in normal skin, maintaining close contact with attached collagen fibrils. Homozygous () mice have been shown perinatal lethality, shorter fetal length and vessel-related placental abnormalities. Milder phenotypes in mcEDS- might be related to a smaller fraction of decorin DS, potentially through residual DSE activity or compensation by DSE2 activity. These findings suggest critical roles of DS and DS-proteoglycans in the multisystem development and maintenance of connective tissues, and provide fundamental evidence to support future etiology-based therapies.
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http://dx.doi.org/10.3390/genes11010043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7017038PMC
December 2019

[Hereditary Skeletal and Skin Disorders Caused by Defects in the Biosynthesis of Chondroitin/Dermatan Sulfate, and Molecular Mechanisms of Pulmonary Metastasis].

Authors:
Shuji Mizumoto

Yakugaku Zasshi 2019 ;139(12):1495-1500

Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University.

The roles of chondroitin sulfate (CS) and dermatan sulfate (DS) have been demonstrated in various biological events such as the construction of the extracellular matrix, tissue development, and cell signaling through interactions with extracellular matrix components, morphogens, and growth factors. Human genetic diseases, including skeletal abnormalities, connective tissue diseases, and heart defects, were reported to be caused by mutations in the genes encoding glycosyltransferases, epimerases, and sulfotransferases that are responsible for the biosynthesis of CS and DS. Glycobiological approaches revealed that mutations in CS- and DS-biosynthetic enzymes led to reductions in their enzymatic activities and in the levels of CS and DS. Furthermore, CS at the surface of tumor cells plays a key role in pulmonary metastasis. A receptor for advanced glycation end-products (RAGE) was predominantly expressed in the lung, and was identified as a functional receptor for CS chains. CS and anti-RAGE antibodies inhibited the pulmonary metastasis of not only Lewis lung carcinoma but also B16 melanoma cells. Hence, RAGE and CS are potential targets of drug discovery for pulmonary metastasis and a number of other pathological conditions involving RAGE in the pathogenetic mechanism. This review provides an overview of glycobiological studies on characterized genetic disorders caused by the impaired biosynthesis of CS, as well as DS, and on the pulmonary metastasis of Lewis lung carcinoma cells involving CS and RAGE.
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http://dx.doi.org/10.1248/yakushi.19-00140DOI Listing
February 2020

CSGALNACT1-congenital disorder of glycosylation: A mild skeletal dysplasia with advanced bone age.

Hum Mutat 2020 03 3;41(3):655-667. Epub 2019 Dec 3.

Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria.

Congenital disorders of glycosylation (CDGs) comprise a large number of inherited metabolic defects that affect the biosynthesis and attachment of glycans. CDGs manifest as a broad spectrum of disease, most often including neurodevelopmental and skeletal abnormalities and skin laxity. Two patients with biallelic CSGALNACT1 variants and a mild skeletal dysplasia have been described previously. We investigated two unrelated patients presenting with short stature with advanced bone age, facial dysmorphism, and mild language delay, in whom trio-exome sequencing identified novel biallelic CSGALNACT1 variants: compound heterozygosity for c.1294G>T (p.Asp432Tyr) and the deletion of exon 4 that includes the start codon in one patient, and homozygosity for c.791A>G (p.Asn264Ser) in the other patient. CSGALNACT1 encodes CSGalNAcT-1, a key enzyme in the biosynthesis of sulfated glycosaminoglycans chondroitin and dermatan sulfate. Biochemical studies demonstrated significantly reduced CSGalNAcT-1 activity of the novel missense variants, as reported previously for the p.Pro384Arg variant. Altered levels of chondroitin, dermatan, and heparan sulfate moieties were observed in patients' fibroblasts compared to controls. Our data indicate that biallelic loss-of-function mutations in CSGALNACT1 disturb glycosaminoglycan synthesis and cause a mild skeletal dysplasia with advanced bone age, CSGALNACT1-CDG.
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http://dx.doi.org/10.1002/humu.23952DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7027858PMC
March 2020

Hyaluronidase-4 is produced by mast cells and can cleave serglycin chondroitin sulfate chains into lower molecular weight forms.

J Biol Chem 2019 07 7;294(30):11458-11472. Epub 2019 Jun 7.

Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052 Australia.

Mast cells represent a heterogeneous cell population that is well-known for the production of heparin and the release of histamine upon activation. Serglycin is a proteoglycan that within mast cell α-granules is predominantly decorated with the glycosaminoglycans heparin or chondroitin sulfate (CS) and has a known role in granule homeostasis. Heparanase is a heparin-degrading enzyme, is present within the α-granules, and contributes to granule homeostasis, but an equivalent CS-degrading enzyme has not been reported previously. In this study, using several approaches, including epitope-specific antibodies, immunohistochemistry, and EM analyses, we demonstrate that human HMC-1 mast cells produce the CS-degrading enzymes hyaluronidase-1 (HYAL1) and HYAL4. We observed that treating the two model CS proteoglycans aggrecan and serglycin with HYAL1 and HYAL4 cleaves the CS chains into lower molecular weight forms with nonreducing end oligosaccharide structures similar to CS stub neoepitopes generated after digestion with the bacterial lyase chondroitinase ABC. We found that these structures are associated with both the CS linkage region and with structures more distal toward the nonreducing end of the CS chain. Furthermore, we noted that HYAL4 cleaves CS chains into lower molecular weight forms that range in length from tetra- to dodecasaccharides. These results provide first evidence that mast cells produce HYAL4 and that this enzyme may play a specific role in maintaining α-granule homeostasis in these cells by cleaving CS glycosaminoglycan chains attached to serglycin.
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http://dx.doi.org/10.1074/jbc.RA119.008647DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6663876PMC
July 2019

Compositional analysis of the glycosaminoglycan family in velvet antlers of Sika deer (Cervus nippon) at different growing stages.

Glycoconj J 2019 04 24;36(2):127-139. Epub 2019 Jan 24.

Department of Life and Environmental Agricultural Sciences, Faculty of Agriculture, Tottori University, Tottori, 680-8551, Japan.

Glycosaminoglycans (GAG) from the velvet antlers of Sika deer (Cervus nippon) at the different growing stages (Fukurozuno, Anshi, and Santajo) of bred and wild deer were isolated and their concentrations and sulfation patterns were analyzed. GAG were digested with chondroitinase ABC, ACI, heparinase-I and -III, and keratanase-II into the corresponding repeating disaccharides of chondroitin sulfate (CS), dermatan sulfate (DS), hyaluronan, heparan sulfate (HS), and keratan sulfate. Cartilaginous tissues contained CS-DS at high concentrations with an almost equal ratio of 4- and 6-sulfates, while 4-sulfate-type CS-DS predominantly occupied ossified tissues, but at low concentrations. High O- and N-sulfation degrees of HS correspond to high ossification. Dynamic quantitative changes in CS-DS and compositional changes in CS-DS and HS were closely associated with the mineralization of deer antlers.
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http://dx.doi.org/10.1007/s10719-019-09859-1DOI Listing
April 2019

Structural alteration of glycosaminoglycan side chains and spatial disorganization of collagen networks in the skin of patients with mcEDS-CHST14.

Biochim Biophys Acta Gen Subj 2019 03 13;1863(3):623-631. Epub 2018 Dec 13.

Laboratory of Anatomy, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan. Electronic address:

Musculocontractural Ehlers-Danlos syndrome (mcEDS) due to CHST14/D4ST1 deficiency (mcEDS-CHST14) is a recently delineated type of EDS caused by biallelic loss-of-function mutations in CHST14, which results in the depletion of dermatan sulfate (DS). Clinical characteristics of mcEDS-CHST14 consist of multiple malformations and progressive fragility-related manifestations, including skin hyperextensibility and fragility. Skin fragility is suspected to result from the impaired assembly of collagen fibrils caused by alteration of the glycosaminoglycan (GAG) chain of decorin-proteoglycan (PG) from DS to chondroitin sulfate (CS). This systematic investigation of the skin pathology of patients with mcEDS-CHST14 comprised both immunostaining of decorin and transmission electron microscopy-based cupromeronic blue staining to visualize GAG chains. Collagen fibrils were dispersed in the affected papillary to reticular dermis; in contrast, they were regularly and tightly assembled in controls. Moreover, the fibrils exhibited a perpendicular arrangement to the affected epidermis, whereas fibrils were parallel to control epidermis. Affected GAG chains were linear, stretching from the outer surface of collagen fibrils to adjacent fibrils; in contrast, those of controls were curved, maintaining close contact with attached collagen fibrils. This is the first observation of compositional alteration, from DS to CS, of GAG side chains, which caused structural alteration of GAG side chains and resulted in spatial disorganization of collagen networks; this presumably disrupted the ring-mesh structure of GAG side chains surrounding collagen fibrils. McEDS-CHST14 provides a critical example of the importance of DS in GAG side chains of decorin-PG during assembly of collagen fibrils in maintenance of connective tissues.
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http://dx.doi.org/10.1016/j.bbagen.2018.12.006DOI Listing
March 2019

Identification of novel LFNG mutations in spondylocostal dysostosis.

J Hum Genet 2019 Mar 10;64(3):261-264. Epub 2018 Dec 10.

Laboratory of Bone and Joint Diseases, Center for Integrative Medical Sciences RIKEN, Tokyo, Japan.

Spondylocostal dysostosis (SCDO) is a heterogeneous group of skeletal disorders characterized by multiple segmentation defects involving vertebrae and ribs. Seven disease genes have been reported as causal genes for SCDO: DLL3, MESP2, TBX6, HES7, RIPPLY2, DMRT2, and LFNG. Here we report a Japanese SCDO case with multiple severe vertebral anomalies from cervical to sacral spine. The patient was a compound heterozygote for c.372delG (p.K124Nfs*) and c.601G>A (p.D201N) variants of LFNG, which encodes a glycosyltransferase (O-fucosylpeptide 3-beta-N-acetylglucosaminyltransferase). The missense variant was in the DxD motif, an active-site motif of the glycosyltransferase, and its loss of the enzyme function was confirmed by an in vitro enzyme assay. This is the second report of LFNG mutations in SCDO.
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http://dx.doi.org/10.1038/s10038-018-0548-2DOI Listing
March 2019

Screening of known disease genes in congenital scoliosis.

Mol Genet Genomic Med 2018 11 9;6(6):966-974. Epub 2018 Sep 9.

Laboratory of Bone and Joint Diseases, Center for Integrative Medical Sciences, RIKEN, Tokyo, Japan.

Background: Congenital scoliosis (CS) is defined as a lateral curvature of the spine due to the vertebral malformations and has an incidence of 0.5-1/1,000 births. We previously examined TBX6 in Japanese CS patients and revealed that approximately 10% of CS was caused by TBX6 mutations. However, the genetic cause of remaining CS is unknown.

Methods: We recruited 78 CS patients without TBX6 mutations and major comorbidities, and investigated the genes previously reported to be associated with CS and congenital vertebral malformations by whole-exome sequencing.

Results: We identified the compound heterozygous missense variants in LFNG in one patient. No likely disease-causing variants were identified in other patients, however. LFNG encodes a GlcNAc-transferase. The LFNG variants showed loss of their enzyme function.

Conclusions: A LFNG mutation is reported in a case of spondylocostal dysostosis (SCD), a skeletal dysplasia with severe malformations of vertebra and rib. The CS patient with LFNG mutations had multiple vertebral malformations including hemivertebrae, butterfly vertebrae, and block vertebrae, and rib malformations. LFNG mutations may cause a spectrum of phenotypes including CS and SCD. The current list of known disease genes could explain only a small fraction of genetic cause of CS.
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http://dx.doi.org/10.1002/mgg3.466DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6305645PMC
November 2018

Impaired proteoglycan glycosylation, elevated TGF-β signaling, and abnormal osteoblast differentiation as the basis for bone fragility in a mouse model for gerodermia osteodysplastica.

PLoS Genet 2018 03 21;14(3):e1007242. Epub 2018 Mar 21.

Institut für Medizinische Genetik und Humangenetik, Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.

Gerodermia osteodysplastica (GO) is characterized by skin laxity and early-onset osteoporosis. GORAB, the responsible disease gene, encodes a small Golgi protein of poorly characterized function. To circumvent neonatal lethality of the GorabNull full knockout, Gorab was conditionally inactivated in mesenchymal progenitor cells (Prx1-cre), pre-osteoblasts (Runx2-cre), and late osteoblasts/osteocytes (Dmp1-cre), respectively. While in all three lines a reduction in trabecular bone density was evident, only GorabPrx1 and GorabRunx2 mutants showed dramatically thinned, porous cortical bone and spontaneous fractures. Collagen fibrils in the skin of GorabNull mutants and in bone of GorabPrx1 mutants were disorganized, which was also seen in a bone biopsy from a GO patient. Measurement of glycosaminoglycan contents revealed a reduction of dermatan sulfate levels in skin and cartilage from GorabNull mutants. In bone from GorabPrx1 mutants total glycosaminoglycan levels and the relative percentage of dermatan sulfate were both strongly diminished. Accordingly, the proteoglycans biglycan and decorin showed reduced glycanation. Also in cultured GORAB-deficient fibroblasts reduced decorin glycanation was evident. The Golgi compartment of these cells showed an accumulation of decorin, but reduced signals for dermatan sulfate. Moreover, we found elevated activation of TGF-β in GorabPrx1 bone tissue leading to enhanced downstream signalling, which was reproduced in GORAB-deficient fibroblasts. Our data suggest that the loss of Gorab primarily perturbs pre-osteoblasts. GO may be regarded as a congenital disorder of glycosylation affecting proteoglycan synthesis due to delayed transport and impaired posttranslational modification in the Golgi compartment.
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http://dx.doi.org/10.1371/journal.pgen.1007242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880397PMC
March 2018

Chondroitin sulfate protects vascular endothelial cells from toxicities of extracellular histones.

Eur J Pharmacol 2018 May 6;826:48-55. Epub 2018 Mar 6.

Department of Analytical Pharmacology, Meijo University, 150, Yagotoyama, Tenpaku-ku, Nagoya 468-8503, Japan.

Extracellular histones induce lethal thrombosis by promoting platelet aggregation, neutrophil migration, and cell injuries. Heparin, which has negative charges, can bind to extracellular histones; however, heparin strongly inhibits the activation of coagulation. Since chondroitin sulfate (CS) shows less effect on the coagulation system than heparin does, CS has the potential to become an effective drug for lethal thrombosis with high risk of bleeding. To elucidate the therapeutic mechanisms of CS in lethal thrombosis, we investigated the interaction between CS and extracellular histones. Mouse vascular endothelial cells were incubated with histones in the presence of heparin or CS, and the expression of caspase-3/7 was measured. The interactions between histones and heparin or CS were measured by surface plasmon resonance analysis. Vascular permeability, platelet counts, liver and renal functions, and coagulation times were evaluated in an in vivo assay. The apoptosis induced by histones was inhibited by treatment with heparin or CS. Heparin and CS showed strong binding to histones and inhibited vascular hyperpermeability. The platelet counts as well as liver and renal functions were not decreased by the treatment with heparin or CS. Moreover, CS showed less effect on the coagulation system than heparin did. These results suggested that CS can be a novel agent for lethal thrombosis with the risk for hemorrhage. Since vascular endothelial cell injuries occur at an early stage of lethal thrombosis, administration of CS might be a useful approach.
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http://dx.doi.org/10.1016/j.ejphar.2018.02.043DOI Listing
May 2018

Roles of two types of heparan sulfate clusters in Wnt distribution and signaling in Xenopus.

Nat Commun 2017 12 7;8(1):1973. Epub 2017 Dec 7.

Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

Wnt proteins direct embryonic patterning, but the regulatory basis of their distribution and signal reception remain unclear. Here, we show that endogenous Wnt8 protein is distributed in a graded manner in Xenopus embryo and accumulated on the cell surface in a punctate manner in association with "N-sulfo-rich heparan sulfate (HS)," not with "N-acetyl-rich HS". These two types of HS are differentially clustered by attaching to different glypicans as core proteins. N-sulfo-rich HS is frequently internalized and associated with the signaling vesicle, known as the Frizzled/Wnt/LRP6 signalosome, in the presence of Wnt8. Conversely, N-acetyl-rich HS is rarely internalized and accumulates Frzb, a secreted Wnt antagonist. Upon interaction with Frzb, Wnt8 associates with N-acetyl-rich HS, suggesting that N-acetyl-rich HS supports Frzb-mediated antagonism by sequestering Wnt8 from N-sulfo-rich HS. Thus, these two types of HS clusters may constitute a cellular platform for the distribution and signaling of Wnt8.
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http://dx.doi.org/10.1038/s41467-017-02076-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5719454PMC
December 2017

Vascular abnormalities in the placenta of Chst14-/- fetuses: implications in the pathophysiology of perinatal lethality of the murine model and vascular lesions in human CHST14/D4ST1 deficiency.

Glycobiology 2018 02;28(2):80-89

Center for Medical Genetics.

Collagen is one of the most important components of the extracellular matrix that is involved in the strength of tissues, cell adhesion and cell proliferation. Mutations in several collagen and post-translational modification enzyme genes cause Ehlers-Danlos syndrome (EDS) characterized by joint and skin hyperextensibility as well as fragility of various organs. Carbohydrate sulfotransferase 14/dermatan 4-O-sulfotransferase-1 (CHST14/D4ST1) is a critical enzyme for biosynthesis of dermatan sulfate, a side chain of various proteoglycans including biglycan that regulates collagen fibrils through their interaction. Mutations in CHST14 were found to cause a new form of EDS, named musculocontractural type EDS (mcEDS-CHST14). Large subcutaneous hematomas are one of the most serious complications accompanied by decreased quality of life and potential lethality. In this study, Chst14 gene-deleted mice were expected to be an animal model of the vascular abnormalities of mcEDS-CHST14. However, only limited numbers of adult mice were generated because of perinatal lethality in most Chst14 gene-deleted homozygote (Chst14-/-) mice. Therefore, we investigated the placentas of these fetuses. The placentas of Chst14-/- fetuses showed a reduced weight, alterations in the vascular structure, and ischemic and/or necrotic-like changes. Electron microscopy demonstrated an abnormal structure of the basement membrane of capillaries in the placental villus. These findings suggest that Chst14 is essential for placental vascular development and perinatal survival of fetuses. Furthermore, placentas of Chst14-/- fetuses could be a useful model for vascular manifestations in mcEDS-CHST14, such as the large subcutaneous hematomas.
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http://dx.doi.org/10.1093/glycob/cwx099DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5993096PMC
February 2018

The reduction of heparan sulphate in the glomerular basement membrane does not augment urinary albumin excretion.

Nephrol Dial Transplant 2018 Jan;33(1):26-33

Department of Molecular Endocrinology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.

Background: Heparan sulphate proteoglycan (HSPG) is present in the glomerular basement membrane (GBM) and is thought to play a major role in the glomerular charge barrier. Reductions and structural alterations of HSPG are observed in different types of kidney diseases accompanied by proteinuria. However, their causal relations remain unknown.

Methods: We generated podocyte-specific exostosin-like 3 gene (Extl3) knockout mice (Extl3KO) using a Cre-loxP recombination approach. A reduction of HSPG was expected in the GBM of these mice, because EXTL3 is involved in its synthesis. Mice were separated into three groups, according to the loads on the glomeruli: a high-protein diet group, a high-protein and high-sodium diet group and a hyperglycaemic group induced by streptozotocin treatment in addition to maintenance on a high-protein and high-sodium diet. The urinary albumin:creatinine ratio was measured at 7, 11, 15 and 19 weeks of age. Renal histology was also investigated.

Results: Podocyte-specific expression of Cre recombinase was detected by immunohistochemistry. Moreover, immunofluorescent staining demonstrated a significant reduction of HSPG in the GBM. Electron microscopy showed irregularities in the GBM and effacement of the foot processes in Extl3KO. The values of the urinary albumin:creatinine ratio were within the range of microalbuminuria in all groups and did not significantly differ between the control mice and Extl3KO.

Conclusions: The reduction of HSPG in the GBM did not augment urinary albumin excretion. HSPG's anionic charge appears to contribute little to the glomerular charge barrier.
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http://dx.doi.org/10.1093/ndt/gfx218DOI Listing
January 2018

Pathophysiological Significance of Dermatan Sulfate Proteoglycans Revealed by Human Genetic Disorders.

Pharmaceuticals (Basel) 2017 Mar 27;10(2). Epub 2017 Mar 27.

Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan.

The indispensable roles of dermatan sulfate-proteoglycans (DS-PGs) have been demonstrated in various biological events including construction of the extracellular matrix and cell signaling through interactions with collagen and transforming growth factor-β, respectively. Defects in the core proteins of DS-PGs such as decorin and biglycan cause congenital stromal dystrophy of the cornea, spondyloepimetaphyseal dysplasia, and Meester-Loeys syndrome. Furthermore, mutations in human genes encoding the glycosyltransferases, epimerases, and sulfotransferases responsible for the biosynthesis of DS chains cause connective tissue disorders including Ehlers-Danlos syndrome and spondyloepimetaphyseal dysplasia with joint laxity characterized by skin hyperextensibility, joint hypermobility, and tissue fragility, and by severe skeletal disorders such as kyphoscoliosis, short trunk, dislocation, and joint laxity. Glycobiological approaches revealed that mutations in DS-biosynthetic enzymes cause reductions in enzymatic activities and in the amount of synthesized DS and also disrupt the formation of collagen bundles. This review focused on the growing number of glycobiological studies on recently reported genetic diseases caused by defects in the biosynthesis of DS and DS-PGs.
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http://dx.doi.org/10.3390/ph10020034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5490391PMC
March 2017

Identification of biallelic EXTL3 mutations in a novel type of spondylo-epi-metaphyseal dysplasia.

J Hum Genet 2017 Aug 23;62(8):797-801. Epub 2017 Mar 23.

Laboratory for Bone and Joint Diseases, RIKEN Center for Integrative Medical Sciences, Tokyo, Japan.

Spondylo-epi-metaphyseal dysplasia (SEMD) is a group of inherited skeletal diseases characterized by the anomalies in spine, epiphyses and metaphyses. SEMD is highly heterogeneous and >20 distinct entities have been identified. Here we describe a novel type of SEMD in two unrelated Turkish patients who presented with severe platyspondyly, kyphoscoliosis, pelvic distortion, constriction of the proximal femora and brachydactyly. Although these phenotypes overlap considerably with some known SEMDs, they had a novel causal gene, exostosin-like glycosyltransferase 3 (EXTL3), that encodes a glycosyltransferase involved in the synthesis of heparin and heparan sulfate. The EXTL3 mutation identified in the patients was a homozygous missense mutation (c.953C>T) that caused a substitution in a highly conserved amino acid (p.P318L). The enzyme activity of the mutant EXTL3 protein was significantly decreased compared to the wild-type protein. Both patients had spinal cord compression at the cranio-vertebral junction and multiple liver cysts since early infancy. One of the patients showed severe immunodeficiency, which is considered non-fortuitous association. Our findings would help define a novel type of SEMD caused by EXTL3 mutations.
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http://dx.doi.org/10.1038/jhg.2017.38DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537416PMC
August 2017

Defect in dermatan sulfate in urine of patients with Ehlers-Danlos syndrome caused by a CHST14/D4ST1 deficiency.

Clin Biochem 2017 Aug 24;50(12):670-677. Epub 2017 Feb 24.

Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan; Laboratory of Proteoglycan Signaling and Therapeutics, Graduate School of Life Science Hokkaido University, Sapporo 001-0021, Japan. Electronic address:

Purpose: Dermatan sulfate (DS) plays a number of roles in a wide range of biological activities such as cell signaling and tissue morphogenesis through interactions with various extracellular matrix proteins including collagen. Mutations in the carbohydrate sulfotransferase 14 gene (CHST14) encoding CHST14/dermatan 4-O-sulfotransferase-1 (D4ST1), which is responsible for the biosynthesis of DS, cause a recently delineated form of Ehlers-Danlos syndrome (EDS, musculocontractural type 1), an autosomal recessive connective tissue disorder characterized by congenital malformations (specific craniofacial features, and congenital multiple contractures) and progressive fragility-related complications (skin hyperextensibility, bruisability, and fragility with atrophic scars; recurrent dislocations; progressive talipes or spinal deformities; and large subcutaneous hematomas). In an attempt to develop a diagnostic screening method for this type of EDS, the amount of DS in the urine of patients was analyzed.

Methods: Urinary DS was quantified by an anion-exchange chromatography after treatment with DS-specific degrading enzyme.

Results: DS was not detected in the urine of patients with homo- or compound heterozygous mutations in CHST14. These results suggest that the quantification of DS in urine is applicable to an initial diagnosis of DS-defective EDS.

Conclusions: This is the first study to perform a urinary disaccharide compositional analysis of chondroitin sulfate (CS)/DS chains in patients with EDS caused by a CHST14/D4ST1 deficiency, and demonstrated the absence of DS chains. This result suggests systemic DS depletion in this disorder, and also proposes the usefulness of a urinary disaccharide compositional analysis of CS/DS chains as a non-invasive screening method for this disorder.
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http://dx.doi.org/10.1016/j.clinbiochem.2017.02.018DOI Listing
August 2017

Functional validation of novel compound heterozygous variants in B3GAT3 resulting in severe osteopenia and fractures: expanding the disease phenotype.

BMC Med Genet 2016 Nov 21;17(1):86. Epub 2016 Nov 21.

Department of Pediatrics, Children's Mercy Hospitals and Clinics, Kansas City, MO, USA.

Background: A new disease class of syndromes, described as linkeropathies, which are derived from defects in the glycosaminoglycan-linker region as well as glycosaminoglycan-side chains of proteoglycans is increasingly being recognized as a cause of human disease. Proteoglycans are an essential component of the extracellular matrix. Defects in the enzymatic process of proteoglycan synthesis broadly occur due to the incorrect addition of side chains. Previously, homozygous missense variants within the B3GAT3 gene encoding beta 1,3 glucuronyltransferase 3(GlcAT-I) responsible for the biosynthesis of glycosaminoglycans have been described in 7 individuals.

Case Presentation: In this study, a 4-year-old patient with a severe phenotype of osteoporosis, hypotonia, joint laxity, fractures, scoliosis, biscuspid aortic valve and myopia was referred for next generation sequencing after extensive negative clinical testing. Whole exome sequencing was performed on the proband and his unaffected parents to identify the molecular basis of his disease. Sequencing revealed compound heterozygous variants in B3GAT3: c.1A > G (p.Met1?) and c.671 T > A (p.L224Q). Clinical and in vitro functional studies were then completed to verify the pathogenicity of the genotype and further characterize the functional basis of the patient's disease demonstrating the patient had a decrease both in the protein level of B3GAT3 and in the glucuronyltransferase activity when compared to control samples. Independent in vitro assessment of each variant confirmed the B3GAT3: c.1A > G (p.Met1?) variant is functionally null and the c.671 T > A (p.L224Q) missense variant has significantly reduced glucuronyltransferase activity (~3% of control).

Conclusions: This is the first report of a patient with compound heterozygosity for a null variant in trans with a missense in B3GAT3 resulting in a severe phenotype, expanding both the genotypic and phenotypic spectrum of B3GAT3-related disease.
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http://dx.doi.org/10.1186/s12881-016-0344-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5117547PMC
November 2016

Chondroitin Sulfate N-acetylgalactosaminyltransferase-1 (CSGalNAcT-1) Deficiency Results in a Mild Skeletal Dysplasia and Joint Laxity.

Hum Mutat 2017 01 22;38(1):34-38. Epub 2016 Sep 22.

Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria.

Mutations in genes encoding enzymes responsible for the biosynthesis and structural diversity of glycosaminoglycans (GAGs) cause a variety of disorders affecting bone and connective tissues, including Desbuquois dysplasia (DD). In an infant with prenatal-onset disproportionate short stature, joint laxity, and radiographic findings typical for DD compound-heterozygosity for a large intragenic deletion, and a p.Pro384Arg missense mutation in CSGALNACT1 was found. CSGALNACT1 encodes chondroitin sulfate N-acetylgalactosaminyltransferase-1 (CSGalNAcT-1, ChGn-1), which initiates chondroitin sulfate (CS) chain biosynthesis on the so-called GAG-protein linker region tetrasaccharide. Biochemical studies revealed a reduced GalNAc-transferase activity of the Arg-384 mutant protein, whereas no differences in proteoglycan synthesis in fibroblasts and the GAG content in the urine were found between patient and controls. This is the first description of bi-allelic loss-of-function mutations in CSGALNACT1 that produce a skeletal dysplasia reminiscent of the skeletal dysplasia of Csgalnact1 mice, and adds to the genetic heterogeneity of DD.
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http://dx.doi.org/10.1002/humu.23070DOI Listing
January 2017

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

PLoS One 2016 13;11(7):e0158967. Epub 2016 Jul 13.

Department of Gastroenterology, Niigata University Medical and Dental Hospital, Niigata city, Niigata, Japan.

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.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0158967PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4943596PMC
July 2017

Mutations in Biosynthetic Enzymes for the Protein Linker Region of Chondroitin/Dermatan/Heparan Sulfate Cause Skeletal and Skin Dysplasias.

Biomed Res Int 2015 25;2015:861752. Epub 2015 Oct 25.

Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan ; Laboratory of Proteoglycan Signaling and Therapeutics, Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan.

Glycosaminoglycans, including chondroitin, dermatan, and heparan sulfate, have various roles in a wide range of biological events such as cell signaling, cell proliferation, tissue morphogenesis, and interactions with various growth factors. Their polysaccharides covalently attach to the serine residues on specific core proteins through the common linker region tetrasaccharide, -xylose-galactose-galactose-glucuronic acid, which is produced through the stepwise addition of respective monosaccharides by four distinct glycosyltransferases. Mutations in the human genes encoding the glycosyltransferases responsible for the biosynthesis of the linker region tetrasaccharide cause a number of genetic disorders, called glycosaminoglycan linkeropathies, including Desbuquois dysplasia type 2, spondyloepimetaphyseal dysplasia, Ehlers-Danlos syndrome, and Larsen syndrome. This review focused on recent studies on genetic diseases caused by defects in the biosynthesis of the common linker region tetrasaccharide.
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http://dx.doi.org/10.1155/2015/861752DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4637088PMC
August 2016

Molecular interactions between chondroitin-dermatan sulfate and growth factors/receptors/matrix proteins.

Curr Opin Struct Biol 2015 Oct 9;34:35-42. Epub 2015 Jul 9.

Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, Nagoya, Japan; Laboratory of Proteoglycan Signaling and Therapeutics, Graduate School of Life Science, Hokkaido University, Sapporo, Japan. Electronic address:

Recent functional studies on chondroitin sulfate-dermatan sulfate (CS-DS) demonstrated its indispensable roles in various biological events including brain development and cancer. CS-DS proteoglycans exert their physiological activity through interactions with specific proteins including growth factors, cell surface receptors, and matrix proteins. The characterization of these interactions is essential for regulating the biological functions of CS-DS proteoglycans. Although amino acid sequences on the bioactive proteins required for these interactions have already been elucidated, the specific saccharide sequences involved in the binding of CS-DS to target proteins have not yet been sufficiently identified. In this review, recent findings are described on the interaction between CS-DS and some proteins which are especially involved in the central nervous system and cancer development/metastasis.
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http://dx.doi.org/10.1016/j.sbi.2015.06.004DOI Listing
October 2015

Skeletal dysplasia in a consanguineous clan from the island of Nias/Indonesia is caused by a novel mutation in B3GAT3.

Hum Genet 2015 Jul 19;134(7):691-704. Epub 2015 Apr 19.

Cologne Center for Genomics (CCG), University of Cologne, Cologne, Germany.

We describe a large family with disproportionate short stature and bone dysplasia from Nias in which we observed differences in severity when comparing the phenotypes of affected individuals from two remote branches. We conducted a linkage scan in the more severely affected family branch and determined a critical interval of 4.7 cM on chromosome 11. Sequencing of the primary candidate gene TBX10 did not reveal a disease-causing variant. When performing whole exome sequencing we noticed a homozygous missense variant in B3GAT3, c.419C>T [p.(Pro140Leu)]. B3GAT3 encodes β-1,3-glucuronyltransferase-I (GlcAT-I). GlcAT-I catalyzes an initial step of proteoglycan synthesis and the mutation p. (Pro140Leu) lies within the donor substrate-binding subdomain of the catalytic domain. In contrast to the previously published mutation in B3GAT3, c.830G>A [p.(Arg277Gln)], no heart phenotype could be detected in our family. Functional studies revealed a markedly reduced GlcAT-I activity in lymphoblastoid cells from patients when compared to matched controls. Moreover, relative numbers of glycosaminoglycan (GAG) side chains were decreased in patient cells. We found that Pro140Leu-mutant GlcAT-I cannot efficiently transfer GlcA to the linker region trisaccharide. This failure results in a partial deficiency of both chondroitin sulfate and heparan sulfate chains. Since the phenotype of the Nias patients differs from the Larsen-like syndrome described for patients with mutation p.(Arg277Gln), we suggest mutation B3GAT3:p.(Pro140Leu) to cause a different type of GAG linkeropathy showing no involvement of the heart.
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http://dx.doi.org/10.1007/s00439-015-1549-2DOI Listing
July 2015

Receptor protein tyrosine phosphatase beta/zeta is a functional binding partner for vascular endothelial growth factor.

Mol Cancer 2015 Feb 3;14:19. Epub 2015 Feb 3.

Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, GR, 26504, Patras, Greece.

Background: Receptor protein tyrosine phosphatase beta/zeta (RPTPβ/ζ) is a chondroitin sulphate (CS) transmembrane protein tyrosine phosphatase and is a receptor for pleiotrophin (PTN). RPTPβ/ζ interacts with ανβ₃ on the cell surface and upon binding of PTN leads to c-Src dephosphorylation at Tyr530, β₃ Tyr773 phosphorylation, cell surface nucleolin (NCL) localization and stimulation of cell migration. c-Src-mediated β₃ Tyr773 phosphorylation is also observed after vascular endothelial growth factor 165 (VEGF₁₆₅) stimulation of endothelial cells and is essential for VEGF receptor type 2 (VEGFR2) - ανβ₃ integrin association and subsequent signaling. In the present work, we studied whether RPTPβ/ζ mediates angiogenic actions of VEGF.

Methods: Human umbilical vein endothelial, human glioma U87MG and stably transfected Chinese hamster ovary cells expressing different β₃ subunits were used. Protein-protein interactions were studied by a combination of immunoprecipitation/Western blot, immunofluorescence and proximity ligation assays, properly quantified as needed. RPTPβ/ζ expression was down-regulated using small interference RNA technology. Migration assays were performed in 24-well microchemotaxis chambers, using uncoated polycarbonate membranes with 8 μm pores.

Results: RPTPβ/ζ mediates VEGF₁₆₅-induced c-Src-dependent β₃ Tyr773 phosphorylation, which is required for VEGFR2-ανβ₃ interaction and the downstream activation of phosphatidylinositol 3-kinase (PI3K) and cell surface NCL localization. RPTPβ/ζ directly interacts with VEGF165, and this interaction is not affected by bevacizumab, while it is interrupted by both CS-E and PTN. Down-regulation of RPTPβ/ζ by siRNA or administration of exogenous CS-E abolishes VEGF₁₆₅-induced endothelial cell migration, while PTN inhibits the migratory effect of VEGF₁₆₅ to the levels of its own effect.

Conclusions: These data identify RPTPβ/ζ as a cell membrane binding partner for VEGF that regulates angiogenic functions of endothelial cells and suggest that it warrants further validation as a potential target for development of additive or alternative anti-VEGF therapies.
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http://dx.doi.org/10.1186/s12943-015-0287-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4323219PMC
February 2015