Disease relevance of GALNS

• Mucopolysaccharidosis IVA (MPS IVA; OMIM#253000), a lysosomal storage disorder caused by a deficiency of N -acetylgalactosamine-6-sulfate sulfatase (GALNS), has variable clinical phenotypes [1].
• Molecular genetic studies on a severely affected patient with MPSIVA (Morquio disease), without karyotypic abnormality, revealed a partial submicroscopic deletion of 16q24.3 and a single point mutation on the other allele, with no functional GALNS activity [2].
• A strain of Arthrobacter aurescens which secretes a large amount of chondroitinase into a culture broth, was isolated from soil [3].
• The antigen was identified as a chondroitin sulfate type A/C proteoglycan synthesized by melanoma cells on the basis of its sensitivity to chondroitinase ABC digestion and the identification of sulfated glycosaminoglycans released from the antigen immunoprecipitated by 155 [4].
• In a human rhabdomyosarcoma cell line, almost all of the newly synthesized type XV collagen was secreted into the medium and upon chondroitinase digestion just the 250-kDa alpha chain was generated [5].

Psychiatry related information on GALNS

• Animals treated with chondroitinase showed significant improvements in open-field locomotor activity as measured by the Basso, Beattie and Bresnahan scoring system after both severe and moderate SCI (p<0.05 and 0.01, respectively) [6].

High impact information on GALNS

• Chondroitinase ABC promotes functional recovery after spinal cord injury [7].
• Chondroitinase treatment of wild-type CHO cells reduced binding by up to 90% [8].
• The purified NK cell 35S-labeled proteoglycans were degraded by approximately 90% to 35S-labeled disaccharides with either chondroitinase ABC or AC [9].
• The migration activity of heparin and mast cell conditioned medium was blocked by specific antagonists of heparin (protamine and heparinase), but not by chondroitinase ABC [10].
• Pretreatment of HeLa cell monolayers with heparitinase, heparinase, and chondroitinase ABC, but not with chondroitinase AC, reduced borrelial attachment by approximately 50% [11].

Chemical compound and disease context of GALNS

• Mucopolysaccharidosis type IVA (Morquio A) is caused by a deficiency of N-acetylgalactosamine-6-sulfatase (GALNS), an enzyme capable of cleaving the sulfate group from both N-acetylgalactosamine-6-sulfate and galactose-6-sulfate [12].
• Immunocytochemistry, Alcian blue staining of paraffin sections and ruthenium red staining of thin sections (accompanied by Streptomyces hyaluronidase and chondroitinase ABC digestion) were used to identify the composition and distribution of the ECM surrounding the pigment cells at various stages during development [13].
• HPLC of disaccharide products from Arthrobacter chondroitinase AC digests did not reveal any significant changes in sulphate substitution of chondroitin sulphate in Alzheimer brain [14].
• Polysaccharide was isolated from human spleen mastocytoma by proteolytic digestion, precipitation with cetylpyridinium chloride, digestion with chondroitinase ABC, and ion-exchange chromatography on DEAE-cellulose [15].
• Transgenic mice (hGAS) that overexpress human progastrin are more susceptible than wild-type mice (FVB/N) to the induction of colonic aberrant crypt foci (ACF) and adenomas by the chemical carcinogen azoxymethane [16].

Biological context of GALNS

• GALNS and APRT are both located on chromosome 16q24.3, suggesting that the patient had a deletion involving both genes [17].
• This substitution altered the isoleucine at position 113 to phenylalanine (I113F) in the 622 amino acid GALNS protein and was associated with a severe phenotype in a homozygote [18].
• In addition to this common mutation, 10 different point mutations and 2 small deletions were detected, suggesting allelic heterogeneity in GALNS gene [18].
• Transfection experiments in GALNS-deficient fibroblasts revealed that the mutation drastically reduces the enzyme activity of GALNS [18].
• Haplotypes were determined using seven polymorphisms to the GALNS locus in families with the double gene deletion [19].

Anatomical context of GALNS

• Gel filtration analysis of fibroblast extracts of patients deficient in either beta-galactosidase (beta-galactosidosis) or cathepsin A (galactosialidosis), which accumulate KS, demonstrates that the 1.27-MDa complex is disrupted and that GALNS is present only in free homodimeric form [20].
• The GALNS activity and cross-reacting material are reduced in the fibroblasts of patients affected with galactosialidosis, indicating that the complex with cathepsin A may protect GALNS in the lysosome [20].
• There was excessive excretion of keratan sulfate in the urine, and GALNS deficiency was confirmed in leukocytes [17].
• To measure the variability of GALNS expression among different transduced cells, we transduced normal and Morquio lymphoblastoid B cells and PBLs, human keratinocytes, murine myoblasts C2C12, and rabbit synoviocytes HIG-82 with LGSN [21].
• Affected homozygous mice have no detectable GALNS enzyme activity and accumulate glycosaminoglycans in multiple tissues including visceral organs, brain, cornea, bone, ligament and bone marrow [22].

Associations of GALNS with chemical compounds

• The remaining paternal allele had no gene rearrangement but GALNS activity was not encoded as Arginine at 386 was replaced with Cysteine (R386C), suggesting this alteration accounts for the severe phenotype [2].
• 0. The tertiary structural model of the GALNS protein revealed that aspartic acid at position 60 is located on the surface of the molecule, away from the active site [23].
• This was further supported by the fact that exposure to chondroitinase ABC, an enzyme capable of chondroitin sulfate degradation, restored normal production of elastic fibers by fibroblasts from patients with Costello syndrome [24].
• GALNS cleaves the sulfate group from N-acetylgalactosamine 6-sulfate and galactose 6-sulfate, which are specifically found in keratan sulfate and chondroitin 6-sulfate [25].
• The anticoagulant effect was undiminished by its binding to C1q, by increased ionic strength, and by CaCl2, but was abolished by incubation of C1qI with chondroitinase ABC [26].

Physical interactions of GALNS

• Anti-human cathepsin A rabbit antiserum coprecipitates GALNS together with cathepsin A, beta-galactosidase, and alpha-neuraminidase in both a purified preparation of the 1 [20].
• We find that PF4 binds to human CD34+ hematopoietic progenitor cells (HPCs) with a median effective concentration of 1 microg/mL but not after exposure to chondroitinase ABC [27].
• Chondroitinase treatment of the proteoglycans did not affect their binding to either native tenascin-C or to any of the recombinant proteins, demonstrating that these interactions are mediated by the proteoglycan core proteins rather than through the glycosaminoglycan chains [28].
• The M-protein bound to a single GAG band with intermediate mobility which eluted with 1.25 N NaCl on ion-exchange chromatography and was chondroitinase sensitive [29].

Enzymatic interactions of GALNS

• 3) The product of K4 chondroitin polymerase was cleaved by chondroitinase ACII [30].

Regulatory relationships of GALNS

• PF-4 binding has been shown to be independent of interleukin-8 receptors and could be inhibited by soluble chondroitin sulfate type glycosaminoglycans or by pretreatment of cells with chondroitinase ABC [31].
• As expected, chondroitinase ABC had no influence on the accelerating effect of low-Mr rec-TM [32].
• Chondroitinase ABC treatment of the 900 kDa proteoglycan yielded a core protein with a molecular weight of approximately 400 kDa that was recognized by polyclonal antibodies against recombinantly expressed fusion proteins from human versican [33].
• Immunization with chondroitinase ABC-digested fetal human cartilage proteoglycan and Freund's complete adjuvant induced polyarthritis and ankylosing spondylitis in female BALB/c mice [34].
• (3) Insulin also stimulates the incorporation of 35SO4 and (3H)leucine into both chondroitinase-sensitive and chondroitinase-resistant blastemal proteoglycans [35].

Other interactions of GALNS

• A patient with hemizygosity for GALNS deficiency and APRT deficiency has been reported from Japan recently [17].
• GALNS copurifies with the complex by different chromatography techniques: affinity chromatography on both cathepsin A-binding and beta-galactosidase-binding columns, gel filtration, and chromatofocusing [20].
• Thus, a tertiary structural model of human GALNS was constructed from the X-ray crystal structure of N -acetylgalacto-samine-4-sulfatase and arylsulfatase A, using homology modeling, and 32 missense mutations were investigated [1].
• Heteroallelic missense mutations of the galactosamine-6-sulfate sulfatase (GALNS) gene in a mild form of Morquio disease (MPS IVA) [36].
• Leukocytes and fibroblasts of both patients were deficient in acid beta-galactosidase (beta-gal) and normal in N-acetylgalactosamine-6-sulfate sulfatase, the deficient enzyme in classical Morquio syndrome [37].

Analytical, diagnostic and therapeutic context of GALNS

• PCR amplification of genomic DNA indicated that a novel junction was created by the fusion of sequences distal to GALNS exon 2 and proximal to APRT exon 3, and that the size of the deleted region was approximately 100 kb [17].
• Mucopolysaccharidosis IV A: molecular cloning of the human N-acetylgalactosamine-6-sulfatase gene (GALNS) and analysis of the 5'-flanking region [38].
• Mutation screening of the GALNS gene was performed by SSCP and direct sequence analyses using genomic DNA samples from 10 Morquio A patients [39].
• These results provide the first evidence that GALNS may be delivered either locally or systematically by various cells in an ex vivo gene therapy of MPS IVA [21].
• GALNS mRNA was localized in developing teeth by in situ hybridization, Northern blot, and reverse-transcription polymerase chain reaction analyses, while GALNS substrates were localized using immunohistochemistry [25].

References