Disease relevance of NAGA

• The newly identified patient is consanguineous with the first patients reported with alpha-NAGA deficiency and neuroaxonal dystrophy and they all had the alpha-NAGA genotype E325K/E325K [1].
• The remarkable findings in this patient were her normal intelligence, Ménière's syndrome, disturbance of peripheral sensory nerves, hearing loss and cardiac hypertrophy. alpha-NAGA enzyme activity in her plasma was 0.77% of the normal value [2].
• alpha-N-acetylgalactosaminidase (alpha-NAGA) deficiency is a rare hereditary lysosomal storage disease, and only three alpha-NAGA-deficient patients with angiokeratoma corporis diffusum (Kanzaki) have been described [2].
• We also conclude that neither NAGA nor SREBP2 are likely to be mutated in ovarian carcinomas [3].
• Results are to be interpreted in view of the role played by synovial cells and by the lysosomal enzymes they release in inflammatory joint diseases and it would be worthwhile in the future to check for secreted NAGA in various body fluids, such as the synovial fluid of the inflamed joint [4].

High impact information on NAGA

• As is the case with HA, fibronectin also acts as a necessary cofactor to NAGA when incubations are made in the absence of whole blood or serum [5].
• NAGA is one of the components from which HA is built up; the other component glucuronic acid was without effect, and so were the other glycosaminoglycans, N-acetyl-D-mannosamine, N-acetyl-D-galactosamine, and D-glucosamine [5].
• We conclude that the stimulatory action of HA on granulocyte functions is mediated through one of its two structural components, i.e., NAGA [5].
• Human alpha-N-acetylgalactosaminidase (alpha-NAGA) deficiency: new mutations and the paradox between genotype and phenotype [1].
• Refinement of an ovarian cancer tumour suppressor gene locus on chromosome arm 22q and mutation analysis of CYP2D6, SREBP2 and NAGA [3].

Biological context of NAGA

• Regional localization of the genes coding for human ACO2, ARSA, and NAGA on chromosome 22 [6].
• GalNAcalpha1-O-Ser/Thr fit tightly in a narrow space of the active site pocket of alpha-NAGA [7].
• CONCLUSION: Our findings suggest that the association of alpha-NAGA with its substrates is strongly affected by the amino acid substitution at R329 and that the association with GalNAcalpha1-O-Thr is more highly susceptible to structural changes [7].
• Three dimensional structural studies of alpha-N-acetylgalactosaminidase (alpha-NAGA) in alpha-NAGA deficiency (Kanzaki disease): different gene mutations cause peculiar structural changes in alpha-NAGAs resulting in different substrate specificities and clinical phenotypes [7].
• In vivo, 10 inhibits PAF-induced plasma extravasation and elevated N-acetyl-beta-D-glucosaminidase (NAGA) levels in male rats with ED50 values of 60 micrograms/kg, po and 4 micrograms/kg, iv respectively, and inhibits PAF-induced bronchoconstriction in guinea pigs with an ED50 value of 15 micrograms/kg after intraduodenal administration [8].

Anatomical context of NAGA

• To define the biochemical basis of this interaction, we examined the binding of two acrosomal hydrolase, proacrosin and N-acetylglucosaminidase (NAGA), to a purified acrosomal matrix fraction of hamster spermatozoa [9].
• To identify the site of ir-EGF in platelets we exposed washed platelets to collagen or thrombin and compared the kinetics of releases of ir-EGF, beta-thromboglobulin (bTG, an alfa-granule marker), ATP (dense granule marker), N-acetyl-beta-D-glucosaminidase (NAGA, a lysosome marker) and lactate dehydrogenase (LDH, a cytoplasmic marker) [10].
• RESULTS: NAGA activity was detected on sperm membranes isolated from human ejaculates [11].
• The lysates of the hybrid cells were treated with Sepharose-coupled antihuman alpha-galactosidase B and the activity of the adsorbed enzyme was measured on the Sepharose beads as N-acetyl-alpha-galactosaminidase [12].
• The alpha-galactosidase A activity from fibroblasts of five Fabry patients and five controls has been separated from alpha-galactosidase B through small DEAE-cellulose columns and in some experiments by treatment of the fibroblast extracts with Sepharose coupled to anti-alpha-galactosidase B antibodies [13].

Associations of NAGA with chemical compounds

• GalNAcalpha1-O-Thr requires a larger space to associate with alpha-NAGA because of the side chain (CH3) of the threonine residue [7].
• Further investigations demonstrated that N-acetyl-D-glucosamine (NAGA) was the smallest active fragment of HA [5].
• Neither proacrosin nor NAGA were solubilized when sperm were permeabilized with Triton X-100 under low ionic strength conditions; however, both hydrolases were releases by extraction with Triton X-100 containing 0.5 M NaCl [9].
• However, glibenclamide treatment produced an increased urinary NAGA excretion in the whole group, and in about twice as many patients as in the pre-treatment period [14].
• Metformin and gliclazide treatment did not change significantly the group levels of NAGA excretion [14].

Other interactions of NAGA

• The results suggest the assignment of ARSA and NAGA to the region 22q13 leads to 22qter and of ACO2 to the region 22q11 leads to 22q13 [6].
• In patients with primary glomerulonephritis, urinary excretion of PC-1 was significantly decreased and that of NAGA significantly increased compared with the excretion in healthy controls [15].
• Excretion of aminopeptidase N (APN) activity before acetaminophen treatment was significantly higher in patients with GN, however, NAGA excretion was higher in both GN and BEN patients than in healthy controls [16].
• Human synovial cells were cultured in vitro and tested for the activities of two lysosomal enzymes, cathepsin B and N-acetyl-beta-D-glucosaminidase (NAGA) under various conditions [4].
• We describe methods for the assay of acid beta-D-glucosidase, acid sphingomyelinase, chitotriosidase, and alpha-N-acetyl-galactosaminidase (NAGA) as a control enzyme in blood spots that were dried onto filter paper [17].

Analytical, diagnostic and therapeutic context of NAGA

• Molecular cloning of a full-length cDNA for human alpha-N-acetylgalactosaminidase (alpha-galactosidase B) [18].
• Solubilized receptors were purified by affinity chromatography using either Naga naja siamensis toxin III or concanavalin A coupled to agarose [19].
• Comment on: Seewald S, Sriram PVJ, Naga M, et al. Cyanoacrylate glue in gastric variceal bleeding. Endoscopy 2002; 34: 926-932 [20].
• A total of eighty six blood samples (17, 19 & 50 of nasopharyngeal carcinoma, oesophageal cancer and normal healthy control respectively) were collected from Naga Hospital, Kohima, Nagaland and B. Barooah Cancer Institute, Guwahati, Assam and were processed for the detection of EBV-IgG antibody using Elisa test [21].

References