Engineered arylsulfatase A with increased activity, stability and brain delivery for therapy of metachromatic leukodystrophy.

A deficiency of human arylsulfatase A (hASA) causes metachromatic leukodystrophy (MLD), a lysosomal storage disease characterized by sulfatide accumulation and central nervous system (CNS) demyelination. Efficacy of enzyme replacement therapy (ERT) is increased by genetic engineering of hASA to elevate its activity and transfer across the blood-brain barrier (BBB), respectively. To further improve the enzyme's bioavailability in the CNS, we mutated a cathepsin cleavage hot spot and obtained hASAs with substantially increased half-lives. We then combined the superstabilizing exchange E424A with the activity-promoting triple substitution M202V/T286L/R291N and the ApoEII-tag for BBB transfer in a trimodal modified neoenzyme called SuPerTurbo-ASA. Compared with wild-type hASA, half-life, activity, and M6P-independent uptake were increased more than 7-fold, about 3-fold, and more than 100-fold, respectively. ERT of an MLD-mouse model with immune tolerance to wild-type hASA did not induce antibody formation, indicating absence of novel epitopes. Compared with wild-type hASA, SuPerTurbo-ASA was 8- and 12-fold more efficient in diminishing sulfatide storage of brain and spinal cord. In both tissues, storage was reduced by ∼60%, roughly doubling clearance achieved with a 65-fold higher cumulative dose of wild-type hASA previously. Due to its enhanced therapeutic potential, SuPerTurbo-ASA might be a decisive advancement for ERT and gene therapy of MLD.

Biochemical and molecular analysis of pediatric patients with metachromatic leukodystrophy in South China: functional characterization of five novel ARSA variants.

Metachromatic leukodystrophy (MLD) is a rare hereditary neurodegenerative disease caused by deficiency of the lysosomal enzyme arylsulfatase A (ARSA). This study described the clinical and molecular characteristics of 24 Chinese children with MLD and investigated functional characterization of five novel ARSA variants. A retrospective analysis was performed in 24 patients diagnosed with MLD at Guangzhou Women and Children's Medical Center in South China. Five novel mutations were further characterized by transient expression studies. We recruited 17 late-infantile, 3 early-juvenile, 4 late-juvenile MLD patients. In late-infantile patients, motor developmental delay and gait disturbance were the most frequent symptoms at onset. In juvenile patients, cognitive regression and gait disturbance were the most frequent chief complaints. Overall, 25 different ARSA mutations were identified with 5 novel mutations.The most frequent alleles were p.W320* and p.G449Rfs. The mutation p.W320*, p.Q155=, p.P91L, p.G156D, p.H208Mfs*46 and p.G449Rfs may link to late-infantile type. The novel missense mutations were predicted damaging in silico. The bioinformatic structural analysis of the novel missense mutations showed that these amino acid replacements would cause severe impairment of protein structure and function. In vitro functional analysis of the six mutants, showing a low ARSA enzyme activity, clearly demonstrated their pathogenic nature. The mutation p.D413N linked to R alleles. In western blotting analysis of the ARSA protein, the examined mutations retained reduced amounts of ARSA protein compared to the wild type. This study expands the spectrum of genotype of MLD. It helps to the future studies of genotype-phenotype correlations to estimate prognosis and develop new therapeutic approach.

N-Acetylgalactosamine-4-sulfatase (Arylsulfatase B) Regulates PD-L1 Expression in Melanoma by an HDAC3-Mediated Epigenetic Mechanism.

The effects of the enzyme N-acetylgalactosamine-4-sulfatase (Arylsulfatase B, ARSB), which removes the 4-sulfate group at the non-reducing end of chondroitin 4-sulfate, on the expression of PD-L1 were determined, and the underlying mechanism of PD-L1 expression was elucidated. Initial experiments in human melanoma cells (A375) showed that PD-L1 expression increased from 357 ± 31 to 796 ± 50 pg/mg protein (p < 10-11) when ARSB was silenced in A375 cells. In subcutaneous B16F10 murine melanomas, PD-L1 declined from 1227 ± 189 to 583 ± 110 pg/mg protein (p = 1.67 × 10-7), a decline of 52%, following treatment with exogenous, bioactive recombinant ARSB. This decline occurred in association with reduced tumor growth and prolongation of survival, as previously reported. The mechanism of regulation of PD-L1 expression by ARSB is attributed to ARSB-mediated alteration in chondroitin 4-sulfation, leading to changes in free galectin-3, c-Jun nuclear localization, HDAC3 expression, and effects of acetyl-H3 on the PD-L1 promoter. These findings indicate that changes in ARSB contribute to the expression of PD-L1 in melanoma and can thereby affect the immune checkpoint response. Exogenous ARSB acted on melanoma cells and normal melanocytes through the IGF2 receptor. The decline in PD-L1 expression by exogenous ARSB may contribute to the impact of ARSB on melanoma progression.

Neurofilament light chain and glial fibrillary acidic protein levels in metachromatic leukodystrophy.

Metachromatic leukodystrophy is a lethal metabolic leukodystrophy, with emerging treatments for early disease stages. Biomarkers to measure disease activity are required for clinical assessment and treatment follow-up. This retrospective study compared neurofilament light chain and glial fibrillary acidic protein (GFAP) levels in CSF (n = 11) and blood (n = 92) samples of 40 patients with metachromatic leukodystrophy (aged 0-42 years) with 38 neurologically healthy children (aged 0-17 years) and 38 healthy adults (aged 18-45 years), and analysed the associations between these levels with clinical phenotype and disease evolution in untreated and transplanted patients. Metachromatic leukodystrophy subtype was determined based on the (expected) age of symptom onset. Disease activity was assessed by measuring gross motor function deterioration and brain MRI. Longitudinal analyses with measurements up to 23 years after diagnosis were performed using linear mixed models. CSF and blood neurofilament light chain and GFAP levels in paediatric controls were negatively associated with age (all P < 0.001). Blood neurofilament light chain level at diagnosis (median, interquartile range; picograms per millilitre) was significantly increased in both presymptomatic (14.7, 10.6-56.7) and symptomatic patients (136, 40.8-445) compared to controls (5.6, 4.5-7.1), and highest among patients with late-infantile (456, 201-854) or early-juvenile metachromatic leukodystrophy (291.0, 104-445) and those ineligible for treatment based on best practice (291, 57.4-472). GFAP level (median, interquartile range; picogram per millilitre) was only increased in symptomatic patients (591, 224-1150) compared to controls (119, 78.2-338) and not significantly associated with treatment eligibility (P = 0.093). Higher blood neurofilament light chain and GFAP levels at diagnosis were associated with rapid disease progression in late-infantile (P = 0.006 and P = 0.051, respectively) and early-juvenile patients (P = 0.048 and P = 0.039, respectively). Finally, blood neurofilament light chain and GFAP levels decreased during follow-up in untreated and transplanted patients but remained elevated compared with controls. Only neurofilament light chain levels were associated with MRI deterioration (P < 0.001). This study indicates that both proteins may be considered as non-invasive biomarkers for clinical phenotype and disease stage at clinical assessment, and that neurofilament light chain might enable neurologists to make better informed treatment decisions. In addition, neurofilament light chain holds promise assessing treatment response. Importantly, both biomarkers require paediatric reference values, given that their levels first decrease before increasing with advancing age.

Comparing the Ability of Secretory Signal Peptides for Heterologous Expression of Anti-Lipopolysaccharide Factor 3 in Chlamydomonas reinhardtii.

Anti-lipopolysaccharide factor 3 (ALFPm3) possesses a wide antimicrobial spectrum and high antibacterial and viral activities for broad application prospects in the aquaculture industry. However, the application of ALFPm3 is limited by its low production in nature, as well as its low activity when expressed in Escherichia coli and yeast. Although it has been proven that its secretory expression can be used to produce antimicrobial peptides with strong antimicrobial activity, there is no study on the high-efficiency secretory expression of ALFPm3 in Chlamydomonas reinhardtii. In this study, signal peptides ARS1 and CAH1 were fused with ALFPm3 and inserted into the pESVH vector to construct pH-aALF and pH-cALF plasmids, respectively, that were transformed to C. reinhardtii JUV using the glass bead method. Subsequently, through antibiotic screening, DNA-PCR, and RT-PCR, transformants expressing ALFPm3 were confirmed and named T-JaA and T-JcA, respectively. The peptide ALFPm3 could be detected in algal cells and culture medium by immunoblot, meaning that ALFPm3 was successfully expressed in C. reinhardtii and secreted into the extracellular environment. Moreover, ALFPm3 extracts from the culture media of T-JaA and T-JcA showed significant inhibitory effects on the growth of V. harveyi, V. alginolyticus, V. anguillarum, and V. parahaemolyticus within 24 h. Interestingly, the inhibitory rate of c-ALFPm3 from T-JcA against four Vibrio was 2.77 to 6.23 times greater than that of a-ALFPm3 from T-JaA, indicating that the CAH1 signal peptide was more helpful in enhancing the secreted expression of the ALFPm3 peptide. Our results provided a new strategy for the secretory production of ALFPm3 with high antibacterial activity in C. reinhardtii, which could improve the application potentiality of ALFPm3 in the aquaculture industry.

Safety and Efficacy of Intravenous and Intrathecal Delivery of AAV9-Mediated ARSA in Minipigs.

Metachromatic leukodystrophy (MLD) is a hereditary neurodegenerative disease characterized by demyelination and motor and cognitive impairments due to deficiencies of the lysosomal enzyme arylsulfatase A (ARSA) or the saposin B activator protein (SapB). Current treatments are limited; however, gene therapy using adeno-associated virus (AAV) vectors for ARSA delivery has shown promising results. The main challenges for MLD gene therapy include optimizing the AAV dosage, selecting the most effective serotype, and determining the best route of administration for ARSA delivery into the central nervous system. This study aims to evaluate the safety and efficacy of AAV serotype 9 encoding ARSA (AAV9-ARSA) gene therapy when administered intravenously or intrathecally in minipigs, a large animal model with anatomical and physiological similarities to humans. By comparing these two administration methods, this study contributes to the understanding of how to improve the effectiveness of MLD gene therapy and offers valuable insights for future clinical applications.

Increase in Chondroitin Sulfate and Decline in Arylsulfatase B May Contribute to Pathophysiology of COVID-19 Respiratory Failure.

INTRODUCTION: The potential role of accumulation of chondroitin sulfates (CSs) in the pathobiology of COVID-19 has not been examined. Accumulation may occur by increased synthesis or by decline in activity of the enzyme arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) which requires oxygen for activity. METHODS: Immunostaining of lung tissue from 28 patients who died due to COVID-19 infection was performed for CS, ARSB, and carbohydrate sulfotransferase (CHST)15. Measurements of mRNA expression of CHST15 and CHST11, sulfotransferase activity, and total sulfated glycosaminoglycans (GAGs) were determined in human vascular smooth muscle cells following angiotensin (Ang) II treatment. RESULTS: CS immunostaining showed increase in intensity and distribution, and immunostaining of ARSB was diminished in COVID-19 compared to normal lung tissue. CHST15 immunostaining was prominent in vascular smooth muscle cells associated with diffuse alveolar damage due to COVID-19 or other causes. Expression of CHST15 and CHST11 which are required for synthesis of CSE and chondroitin 4-sulfate, total sulfated GAGs, and sulfotransferase activity was significantly increased following AngII exposure in vascular smooth muscle cells. Expression of Interleukin-6 (IL-6), a mediator of cytokine storm in COVID-19, was inversely associated with ARSB expression. DISCUSSION/CONCLUSION: Decline in ARSB and resulting increases in CS may contribute to the pathobiology of COVID-19, as IL-6 does. Increased expression of CHSTs following activation of Ang-converting enzyme 2 may lead to buildup of CSs.

Plasma arylsulfatase A levels are associated with cognitive function in Parkinson's disease.

BACKGROUND: Arylsulfatase A (ARSA), a lysosomal enzyme, has been shown to inhibit the aggregation and propagation of α-synuclein (α-syn) through its molecular chaperone function. The relationship between ARSA levels and Parkinson's disease (PD) in the Chinese Han population remains controversial, and few quantitative research studies have investigated the relationship between plasma ARSA levels and PD. OBJECTIVES: The purpose of this study was to investigate the relationships between ARSA levels and cognitive function in PD patients and to evaluate the association of ARSA and α-syn levels with nonmotor symptoms. METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to measure the plasma ARSA and α-syn levels in 50 healthy controls, 120 PD patients (61 PD patients with no cognitive impairment (PD-NCI) and 59 PD patients with cognitive impairment (PD-CI)). Motor symptoms and nonmotor symptoms (cognitive function, Unified Parkinson's Disease Rating Scale (UPDRS) score, depression, anxiety, constipation, olfactory dysfunction, sleep disruption, and other symptoms) were assessed with the relevant scales. The Kruskal-Wallis H test was used for comparison between groups, and Pearson/Spearman analysis was used for correlation analysis. RESULTS: The plasma ARSA concentrations were lower in the PD-CI group than in the PD-NCI group. The plasma α-syn levels in the PD-CI group were higher than those in the healthy control group, and the plasma ARSA levels were correlated with the Mini-Mental State Examination (MMSE scores) and Hoehn and Yahr (H-Y) stage. CONCLUSION: We used a quantitative assessment method to show that low plasma ARSA levels and high α-syn levels are related to cognitive impairment in PD patients. Plasma ARSA levels gradually decrease with PD progression.

Decoding the consecutive lysosomal degradation of 3-O-sulfate containing heparan sulfate by Arylsulfatase G (ARSG).

The lysosomal degradation of heparan sulfate is mediated by the concerted action of nine different enzymes. Within this degradation pathway, Arylsulfatase G (ARSG) is critical for removing 3-O-sulfate from glucosamine, and mutations in ARSG are causative for Usher syndrome type IV. We developed a specific ARSG enzyme assay using sulfated monosaccharide substrates, which reflect derivatives of its natural substrates. These sulfated compounds were incubated with ARSG, and resulting products were analyzed by reversed-phase HPLC after chemical addition of the fluorescent dyes 2-aminoacridone or 2-aminobenzoic acid, respectively. We applied the assay to further characterize ARSG regarding its hydrolytic specificity against 3-O-sulfated monosaccharides containing additional sulfate-groups and N-acetylation. The application of recombinant ARSG and cells overexpressing ARSG as well as isolated lysosomes from wild-type and Arsg knockout mice validated the utility of our assay. We further exploited the assay to determine the sequential action of the different sulfatases involved in the lysosomal catabolism of 3-O-sulfated glucosamine residues of heparan sulfate. Our results confirm and extend the characterization of the substrate specificity of ARSG and help to determine the sequential order of the lysosomal catabolic breakdown of (3-O-)sulfated heparan sulfate.

Profound Impact of Decline in N-Acetylgalactosamine-4-Sulfatase (Arylsulfatase B) on Molecular Pathophysiology and Human Diseases.

The enzyme N-acetylgalactosamine-4-sulfatase (Arylsulfatase B; ARSB) was originally identified as a lysosomal enzyme which was deficient in Mucopolysaccharidosis VI (MPS VI; Maroteaux-Lamy Syndrome). The newly directed attention to the impact of ARSB in human pathobiology indicates a broader, more pervasive effect, encompassing roles as a tumor suppressor, transcriptional mediator, redox switch, and regulator of intracellular and extracellular-cell signaling. By controlling the degradation of chondroitin 4-sulfate and dermatan sulfate by removal or failure to remove the 4-sulfate residue at the non-reducing end of the sulfated glycosaminoglycan chain, ARSB modifies the binding or release of critical molecules into the cell milieu. These molecules, such as galectin-3 and SHP-2, in turn, influence crucial cellular processes and events which determine cell fate. Identification of ARSB at the cell membrane and in the nucleus expands perception of the potential impact of decline in ARSB activity. The regulation of availability of sulfate from chondroitin 4-sulfate and dermatan sulfate may also affect sulfate assimilation and production of vital molecules, including glutathione and cysteine. Increased attention to ARSB in mammalian cells may help to integrate and deepen our understanding of diverse biological phenomenon and to approach human diseases with new insights.

Purification, Characterization, and Structural Studies of a Sulfatase from Pedobacter yulinensis.

Sulfatases are ubiquitous enzymes that hydrolyze sulfate from sulfated organic substrates such as carbohydrates, steroids, and flavones. These enzymes can be exploited in the field of biotechnology to analyze sulfated metabolites in humans, such as steroids and drugs of abuse. Because genomic data far outstrip biochemical characterization, the analysis of sulfatases from published sequences can lead to the discovery of new and unique activities advantageous for biotechnological applications. We expressed and characterized a putative sulfatase (PyuS) from the bacterium Pedobacter yulinensis. PyuS contains the (C/S)XPXR sulfatase motif, where the Cys or Ser is post-translationally converted into a formylglycine residue (FGly). His-tagged PyuS was co-expressed in Escherichia coli with a formylglycine-generating enzyme (FGE) from Mycobacterium tuberculosis and purified. We obtained several crystal structures of PyuS, and the FGly modification was detected at the active site. The enzyme has sulfatase activity on aromatic sulfated substrates as well as phosphatase activity on some aromatic phosphates; however, PyuS did not have detectable activity on 17α-estradiol sulfate, cortisol 21-sulfate, or boldenone sulfate.

Delayed Post-hypoxic Leukoencephalopathy with Neuroradiological Recovery.

Manjunath V, Nadaf S, Chakor RT. Delayed Post-hypoxic Leukoencephalopathy with Neuroradiological Recovery. Indian J Crit Care Med 2021;25(11):1326-1328.

Metachromatic leukodystrophy genotypes in The Netherlands reveal novel pathogenic ARSA variants in non-Caucasian patients.

Metachromatic leukodystrophy (MLD) is an autosomal recessively inherited sulfatide storage disease caused by deficient activity of the lysosomal enzyme arylsulfatase A (ASA). Genetic analysis of the ARSA gene is important in MLD diagnosis and screening of family members. In addition, more information on genotype prevalence will help interpreting MLD population differences between countries. In this study, we identified 31 different ARSA variants in the patient cohort (n = 67) of the Dutch expertise center for MLD. The most frequently found variant, c.1283C > T, p.(Pro428Leu), was present in 43 (64%) patients and resulted in a high prevalence of the juvenile MLD type (58%) in The Netherlands. Furthermore, we observed in five out of six patients with a non-Caucasian ethnic background previously unreported pathogenic ARSA variants. In total, we report ten novel variants including four missense, two nonsense, and two frameshift variants and one in-frame indel, which were all predicted to be disease causing in silico. In addition, one silent variant was found, c.1200C > T, that most likely resulted in erroneous exonic splicing, including partial skipping of exon 7. The c.1200C > T variant was inherited in cis with the pseudodeficiency allele c.1055A > G, p.(Asn352Ser) + ∗96A > G. With this study we provide a genetic base of the unique MLD phenotype distribution in The Netherlands. In addition, our study demonstrated the importance of genetic analysis in MLD diagnosis and the increased likelihood of unreported, pathogenic ARSA variants in patients with non-Caucasian ethnic backgrounds.

Safety of intrathecal delivery of recombinant human arylsulfatase A in children with metachromatic leukodystrophy: Results from a phase 1/2 clinical trial.

BACKGROUND: Metachromatic leukodystrophy (MLD) is an autosomal recessive disorder caused by deficient arylsulfatase A (ASA) activity and characterized by neurological involvement that results in severe disability and premature death. We examined the safety and tolerability of intrathecally delivered recombinant human ASA (rhASA; SHP611, now TAK-611) in children with MLD (NCT01510028). Secondary endpoints included change in cerebrospinal fluid (CSF) sulfatide and lysosulfatide levels, and motor function (assessed by Gross Motor Function Measure-88 total score). METHODS: Twenty-four children with MLD who experienced symptom onset aged ≤ 30 months were enrolled. Patients received rhASA every other week (EOW) for 38 weeks at 10, 30, or 100 mg (cohorts 1-3; n = 6 per cohort), or 100 mg manufactured using a revised process (cohort 4; n = 6). RESULTS: No rhASA-related serious adverse events (SAEs) were observed; 25% of patients experienced an SAE related to the intrathecal device or drug delivery method. Mean CSF sulfatide and lysosulfatide levels fell to within normal ranges in both 100 mg cohorts following treatment. Although there was a general decline in motor function over time, there was a tendency towards a less pronounced decline in patients receiving 100 mg. CONCLUSION: Intrathecal rhASA was generally well tolerated at doses up to 100 mg EOW. These preliminary data support further development of rhASA as a therapy for patients with MLD.

Reciprocal surface expression of arylsulfatase A and ubiquitin in normal and defective mammalian spermatozoa.

Defective mammalian spermatozoa are marked on their surface by proteolytic chaperone ubiquitin. To identify potential ubiquitinated substrates in the defective spermatozoa, we resolved bull sperm protein extracts on a two-dimensional gel and isolated a 64-65-kDa spot (p64) corresponding to one of the major ubiquitin-immunoreactive bands observed in the one-dimensional Western blots. Immune serum raised against this protein recognized a prominent, possibly glycosylated band/spot in the range of 55-68 kDa, consistent with the original spot used for immunization. Internal sequences obtained by Edman degradation of this spot matched the sequence of arylsulfatase A (ARSA), the sperm acrosomal enzyme thought to be important for fertility. By immunofluorescence, a prominent signal was detected on the acrosomal surface (boar and bull) and on the sperm tail principal piece (bull). A second immune serum raised against a synthetic peptide corresponding to an immunogenic internal sequence (GTGKSPRRTL) of the porcine ARSA also labeled sperm acrosome and principal piece. Both sera showed diminished immunoreactivity in the defective bull spermatozoa co-labeled with an anti-ubiquitin antibody. Western blotting and image-based flow cytometry (IBFC) confirmed a reduced ARSA immunoreactivity in the immotile sperm fraction rich in ubiquitinated spermatozoa. Larger than expected ARSA-immunoreactive bands were found in sperm protein extracts immunoprecipitated with anti-ubiquitin antibodies and affinity purified with matrix-bound, recombinant ubiquitin-binding UBA domain. These bands did not show the typical pattern of ARSA glycosylation but overlapped with bands preferentially binding the Lens culinaris agglutinin (LCA) lectin. By both epifluorescence microscopy and IBFC, the LCA binding was increased in the ubiquitinated spermatozoa with diminished ARSA immunoreactivity. ARSA was also found in the epididymal fluid suggesting that in addition to intrinsic ARSA expression in the testis, epididymal spermatozoa take up ARSA on their surface during the epididymal passage. We conclude that sperm surface ARSA is one of the ubiquitinated sperm surface glycoproteins in defective bull spermatozoa. Defective sperm surface thus differs from normal sperm surface by increased ubiquitination, reduced ARSA binding, and altered glycosylation.

Arylsulfatase A, a genetic modifier of Parkinson's disease, is an α-synuclein chaperone.

Mutations in lysosomal genes increase the risk of neurodegenerative diseases, as is the case for Parkinson's disease. Here, we found that pathogenic and protective mutations in arylsulfatase A (ARSA), a gene responsible for metachromatic leukodystrophy, a lysosomal storage disorder, are linked to Parkinson's disease. Plasma ARSA protein levels were changed in Parkinson's disease patients. ARSA deficiency caused increases in α-synuclein aggregation and secretion, and increases in α-synuclein propagation in cells and nematodes. Despite being a lysosomal protein, ARSA directly interacts with α-synuclein in the cytosol. The interaction was more extensive with protective ARSA variant and less with pathogenic ARSA variant than wild-type. ARSA inhibited the in vitro fibrillation of α-synuclein in a dose-dependent manner. Ectopic expression of ARSA reversed the α-synuclein phenotypes in both cell and fly models of synucleinopathy, the effects correlating with the extent of the physical interaction between these molecules. Collectively, these results suggest that ARSA is a genetic modifier of Parkinson's disease pathogenesis, acting as a molecular chaperone for α-synuclein.

Lysosomal Proteome and Secretome Analysis Identifies Missorted Enzymes and Their Nondegraded Substrates in Mucolipidosis III Mouse Cells.

Targeting of soluble lysosomal enzymes requires mannose 6-phosphate (M6P) signals whose formation is initiated by the hexameric N-acetylglucosamine (GlcNAc)-1-phosphotransferase complex (α2ß2γ2). Upon proteolytic cleavage by site-1 protease, the α/ß-subunit precursor is catalytically activated but the functions of γ-subunits (Gnptg) in M6P modification of lysosomal enzymes are unknown. To investigate this, we analyzed the Gnptg expression in mouse tissues, primary cultured cells, and in Gnptg reporter mice in vivo, and found high amounts in the brain, eye, kidney, femur, vertebra and fibroblasts. Consecutively we performed comprehensive quantitative lysosomal proteome and M6P secretome analysis in fibroblasts of wild-type and Gnptgko mice mimicking the lysosomal storage disorder mucolipidosis III. Although the cleavage of the α/ß-precursor was not affected by Gnptg deficiency, the GlcNAc-1-phosphotransferase activity was significantly reduced. We purified lysosomes and identified 29 soluble lysosomal proteins by SILAC-based mass spectrometry exhibiting differential abundance in Gnptgko fibroblasts which was confirmed by Western blotting and enzymatic activity analysis for selected proteins. A subset of these lysosomal enzymes show also reduced M6P modifications, fail to reach lysosomes and are secreted, among them α-l-fucosidase and arylsulfatase B. Low levels of these enzymes correlate with the accumulation of non-degraded fucose-containing glycostructures and sulfated glycosaminoglycans in Gnptgko lysosomes. Incubation of Gnptgko fibroblasts with arylsulfatase B partially rescued glycosaminoglycan storage. Combinatorial treatments with other here identified missorted enzymes of this degradation pathway might further correct glycosaminoglycan accumulation and will provide a useful basis to reveal mechanisms of selective, Gnptg-dependent formation of M6P residues on lysosomal proteins.

A Possible Role for Arylsulfatase G in Dermatan Sulfate Metabolism.

Perturbations of glycosaminoglycan metabolism lead to mucopolysaccharidoses (MPS)-lysosomal storage diseases. One type of MPS (type VI) is associated with a deficiency of arylsulfatase B (ARSB), for which we previously established a cellular model using pulmonary artery endothelial cells with a silenced ARSB gene. Here, we explored the effects of silencing the ARSB gene on the growth of human pulmonary artery smooth muscle cells in the presence of different concentrations of dermatan sulfate (DS). The viability of pulmonary artery smooth muscle cells with a silenced ARSB gene was stimulated by the dermatan sulfate. In contrast, the growth of pulmonary artery endothelial cells was not affected. As shown by microarray analysis, the expression of the arylsulfatase G (ARSG) in pulmonary artery smooth muscle cells increased after silencing the arylsulfatase B gene, but the expression of genes encoding other enzymes involved in the degradation of dermatan sulfate did not. The active site of arylsulfatase G closely resembles that of arylsulfatase B, as shown by molecular modeling. Together, these results lead us to propose that arylsulfatase G can take part in DS degradation; therefore, it can affect the functioning of the cells with a silenced arylsulfatase B gene.

Identification of Novel ARSB Genes Necessary for p-Benzoquinone Biosynthesis in the Larval Oral Secretion Participating in External Immune Defense in the Red Palm Weevil.

External secretions, composed of a variety of chemical components, are among the most important traits that endow insects with the ability to defend themselves against predators, parasites, or other adversities, especially pathogens. Thus, these exudates play a crucial role in external immunity. Red palm weevil larvae are prolific in this regard, producing large quantities of p-benzoquinone, which is present in their oral secretion. Benzoquinone with antimicrobial activity has been proven to be an active ingredient and key factor for external immunity in a previous study. To obtain a better understanding of the genetic and molecular basis of external immune secretions, we identify genes necessary for p-benzoquinone synthesis. Three novel ARSB genes, namely, RfARSB-0311, RfARSB-11581, and RfARSB-14322, are screened, isolated, and molecularly characterized on the basis of transcriptome data. To determine whether these genes are highly and specifically expressed in the secretory gland, we perform tissue/organ-specific expression profile analysis. The functions of these genes are further determined by examining the antimicrobial activity of the secretions and quantification of p-benzoquinone after RNAi. All the results reveal that the ARSB gene family can regulate the secretory volume of p-benzoquinone by participating in the biosynthesis of quinones, thus altering the host's external immune inhibitory efficiency.

Decline in arylsulfatase B expression increases EGFR expression by inhibiting the protein-tyrosine phosphatase SHP2 and activating JNK in prostate cells.

Epidermal growth factor receptor (EGFR) has a crucial role in cell differentiation and proliferation and cancer, and its expression appears to be up-regulated when arylsulfatase B (ARSB or GalNAc-4-sulfatase) is reduced. ARSB removes 4-sulfate groups from the nonreducing end of dermatan sulfate and chondroitin 4-sulfate (C4S), and its decreased expression has previously been reported to inhibit the activity of the ubiquitous protein-tyrosine phosphatase, nonreceptor type 11 (SHP2 or PTPN11). However, the mechanism by which decline in ARSB leads to decline in SHP2 activity is unclear. Here, we show that SHP2 binds preferentially C4S, rather than chondroitin 6-sulfate, and confirm that SHP2 activity declines when ARSB is silenced. The reduction in ARSB activity, and the resultant increase in C4S, increased the expression of EGFR (Her1/ErbB1) in human prostate stem and epithelial cells. The increased expression of EGFR occurred after 1) the decline in SHP2 activity, 2) enhanced c-Jun N-terminal kinase (JNK) activity, 3) increased nuclear DNA binding by c-Jun and c-Fos, and 4) EGFR promoter activation. In response to exogenous EGF, there was increased bromodeoxyuridine incorporation, consistent with enhanced cell proliferation. These findings indicated that ARSB and chondroitin 4-sulfation affect the activation of an important dual phosphorylation threonine-tyrosine kinase and the mRNA expression of a critical tyrosine kinase receptor in prostate cells. Restoration of ARSB activity with the associated reduction in C4S may provide a new therapeutic approach for managing malignancies in which EGFR-mediated tyrosine kinase signaling pathways are active.