Tandem mass spectrometric enzyme assay for simultaneous detection of Tay-Sachs and Sandhoff diseases in dried blood spots for newborn screening.

GM2 gangliosidosis is a group of rare lysosomal storage disorders (LSDs) including Tay-Sachs disease (TSD) and Sandhoff disease (SD), caused by deficiency in activity of either ß-hexosaminidase A (HexA) or both ß-hexosaminidase A and ß-hexosaminidase B (HexB). Methods for screening and diagnosis of TSD and SD include measurement and comparison of the activity of these two enzymes. Here we report a novel method for duplex screening of dried blood spots (DBS) for TSD and SD by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method requires incubation of a single 3 mm DBS punch with the assay cocktail followed by the injection into the LC-MS/MS. The performance of the method was evaluated by comparing the confirmed TSD and SD patient DBS to random healthy newborn DBS which showed easy discrimination between the three cohorts. The method is multiplexable with other LSD MS/MS enzyme assays which is critical to the continued expansion of the NBS panels.

Plasma GM2 ganglioside potential biomarker for diagnosis, prognosis and disease monitoring of GM2-Gangliosidosis.

GM2-Gangliosidosis are a group of inherited lysosomal storage pathologies characterized by a large accumulation of GM2 ganglioside in the lysosome. They are caused by mutation in HEXA or HEXB causing reduced or absent activity of a lysosomal ß-hexosaminidase A, or mutation in GM2A causing defect in GM2 activator protein (GM2AP), an essential protein for the activity of the enzyme. Biochemical diagnosis relies on the measurement of ß-hexosaminidases A and B activities, which is able to detect lysosomal enzyme deficiency but fails to identify defects in GM2AP. We developed a rapid, specific and sensitive liquid chromatography-mass spectrometry-based method to measure simultaneously GM1, GM2, GM3 and GD3 molecular species. Gangliosides were analysed in plasma from 19 patients with GM2-Gangliosidosis: Tay-Sachs (n = 9), Sandhoff (n = 9) and AB variant of GM2-Gangliosidosis (n = 1) and compared to 20 age-matched controls. Among patients, 12 have a late adult-juvenile-onset and 7 have an infantile early-onset of the disease. Plasma GM2 molecular species were increased in all GM2-Gangliosidosis patients (19/19), including the patient with GM2A mutation, compared to control individuals and compared to patients with different other lysosomal storage diseases. GM234:1 and GM234:1/GM334:1 ratio discriminated patients from controls with 100% sensitivity and specificity. GM234:1 and GM234:1/GM334:1 were higher in patients with early-onset compared to those with late-onset of the disease, suggesting a relationship with severity. Longitudinal analysis in one adult with Tay-Sachs disease over 9 years showed a positive correlation of GM234:1 and GM234:1/GM334:1 ratio with age at sampling. We propose that plasma GM2 34:1 and its ratio to GM3 34:1 could be sensitive and specific biochemical diagnostic biomarkers for GM2-Gangliosidosis including AB variant and could be useful as a first line diagnostic test and potential biomarkers for monitoring upcoming therapeutic efficacy.

Hexa-Histidine, a Peptide with Versatile Applications in the Study of Amyloid-ß(1-42) Molecular Mechanisms of Action.

Amyloid ß (Aß) oligomers are the most neurotoxic forms of Aß, and Aß(1-42) is the prevalent Aß peptide found in the amyloid plaques of Alzheimer's disease patients. Aß(25-35) is the shortest peptide that retains the toxicity of Aß(1-42). Aß oligomers bind to calmodulin (CaM) and calbindin-D28k with dissociation constants in the nanomolar Aß(1-42) concentration range. Aß and histidine-rich proteins have a high affinity for transition metal ions Cu2+, Fe3+ and Zn2+. In this work, we show that the fluorescence of Aß(1-42) HiLyteTM-Fluor555 can be used to monitor hexa-histidine peptide (His6) interaction with Aß(1-42). The formation of His6/Aß(1-42) complexes is also supported by docking results yielded by the MDockPeP Server. Also, we found that micromolar concentrations of His6 block the increase in the fluorescence of Aß(1-42) HiLyteTM-Fluor555 produced by its interaction with the proteins CaM and calbindin-D28k. In addition, we found that the His6-tag provides a high-affinity site for the binding of Aß(1-42) and Aß(25-35) peptides to the human recombinant cytochrome b5 reductase, and sensitizes this enzyme to inhibition by these peptides. In conclusion, our results suggest that a His6-tag could provide a valuable new tool to experimentally direct the action of neurotoxic Aß peptides toward selected cellular targets.

N-acetyl-ß-D-hexosaminidases mediate the generation of paucimannosidic proteins via a putative noncanonical truncation pathway in human neutrophils.

We recently discovered that human neutrophils express immunomodulatory glycoproteins carrying unusual and highly truncated paucimannosidic N-glycans (Man1-3GlcNAc2Fuc0-1), but their biosynthesis remains elusive. Guided by the well-characterized truncation pathway in invertebrates and plants in which the N-acetyl-ß-D-hexosaminidase (Hex) isoenzymes catalyze paucimannosidic protein (PMP) formation, we here set out to test if the homologous human Hex α and ß subunits encoded by HEXA and HEXB drive a similar truncation pathway in human neutrophils. To this end, we performed quantitative glycomics and glycoproteomics of several CRISPR-Cas9-edited Hex-disrupted neutrophil-like HL-60 mutants (HEXA-KO and HEXB-KO) and matching unedited cell lines. Hex disruption was validated using next-generation sequencing, enzyme-linked immunosorbent assay (ELISA), quantitative proteomics and Hex activity assays. Excitingly, all Hex-disrupted mutants displayed significantly reduced levels of paucimannosylation, particularly Man2-3GlcNAc2Fuc1, relative to unedited HL-60 suggesting that both HEXA and HEXB contribute to PMP formation via a hitherto unexplored truncation pathway in neutrophils. Quantitative N-glycomics indeed demonstrated reduced utilization of a putative noncanonical truncation pathway in favor of the canonical elongation pathway in all Hex-disrupted mutants relative to unedited controls. Quantitative glycoproteomics recapitulated the truncation-to-elongation switch in all Hex-disrupted mutants and showed a greater switch for N-glycoproteins cotrafficking with Hex to the azurophilic granules of neutrophils such as myeloperoxidase. Finally, we supported the Hex-PMP relationship by documenting that primary neutrophils isolated from an early-onset Sandhoff disease patient (HEXB-/-) displayed dramatically reduced paucimannosylation relative to neutrophils from an age-matched unaffected donor. We conclude that both human Hex α and ß mediate PMP formation via a putative noncanonical truncation pathway in neutrophils.

Hexosaminidase A (HEXA) regulates hepatic sphingolipid and lipoprotein metabolism in mice.

Hexosaminidase A (HexA), a heterodimer consisting of HEXA and HEXB, converts the ganglioside sphingolipid GM2 to GM3 by removing a terminal N-acetyl-d-galactosamine. HexA enzyme deficiency in humans leads to GM2 accumulation in cells, particularly in neurons, and is associated with neurodegeneration. While HexA and sphingolipid metabolism have been extensively investigated in the context of neuronal lipid metabolism, little is known about the metabolic impact of HexA and ganglioside degradation in other tissues. Here, we focussed on the role of HexA in the liver, which is a major regulator of systemic lipid metabolism. We find that hepatic Hexa expression is induced by lipid availability and increased in the presence of hepatic steatosis, which is associated with increased hepatic GM3 content. To assess the impact of HEXA on hepatic lipid metabolism, we used an adeno-associated virus to overexpress HEXA in the livers of high-fat diet fed mice. HEXA overexpression was associated with increased hepatic GM3 content and increased expression of enzymes involved in the degradation of glycated sphingolipids, ultimately driving sphingomyelin accumulation in the liver. In addition, HEXA overexpression led to substantial proteome remodeling in cell surface lipid rafts, which was associated with increased VLDL processing and secretion, hypertriglyceridemia and ectopic lipid accumulation in peripheral tissues. This study established an important role of HEXA in modulating hepatic sphingolipid and lipoprotein metabolism.

Hexa-substituted cyclotriphosphazene derivatives containing hetero-ring chalcones: Synthesis, in vitro cytotoxic activity and their DNA damage determination.

In this study, hetero ring hexasubstituted cyclotriphosphazes were obtained in two steps and these compounds were investigated in terms of in vitro cytotoxicity and genotoxicity. The structural characterizations of the starting compounds 1-4 were defined by FT-IR, elemental analysis, and NMR (1H and 13C) spectroscopy techniques. In addition to these techniques, the 31P NMR spectroscopy technique was also used in the characterization of cyclotriphosphazenes (FSC 1-4). The changes in cell viability at 1, 5, 25, 50, and 100 µM concentrations against human ovarian (A2780) and human prostate (PC-3 and LNCaP) cell lines for 24 h were determined by the MTT assay method. According to MTT assay results, the inhibitory concentration 50 (IC50/LogIC50) value was calculated in Graphpad Prism 6 program. The comet assay was performed to determine whether the effects of compounds on cell viability were through DNA damage. In the comet assay experiments, the highest concentration of compounds (100 µM) was applied to the cells for 24 h and tail length (TL), tail intensity (TI), olive tail moment (OTM) parameters were examined. The results showed that the compound 1-4 and FSC 1-4 compounds reduced the cell viability against all cancer cell lines (p < 0.05). At the same time, different concentrations of these compounds caused DNA damage in all three cell types (p < 0.05). The possible interactions and chemical mechanisms of the synthesized compounds were explained by computational methods with molecular docking. In addition, pharmacological properties of drug candidate molecules have been defined. Experimental and calculated data comply with each other. The study results showed that these compounds have cytotoxic effects against cancer cells and suggested that these effects have occurred through genotoxicity.

sp2-Iminosugars targeting human lysosomal ß-hexosaminidase as pharmacological chaperone candidates for late-onset Tay-Sachs disease.

The late-onset form of Tay-Sachs disease displays when the activity levels of human ß-hexosaminidase A (HexA) fall below 10% of normal, due to mutations that destabilise the native folded form of the enzyme and impair its trafficking to the lysosome. Competitive inhibitors of HexA can rescue disease-causative mutant HexA, bearing potential as pharmacological chaperones, but often also inhibit the enzyme O-glucosaminidase (GlcNAcase; OGA), a serious drawback for translation into the clinic. We have designed sp2-iminosugar glycomimetics related to GalNAc that feature a neutral piperidine-derived thiourea or a basic piperidine-thiazolidine bicyclic core and behave as selective nanomolar competitive inhibitors of human Hex A at pH 7 with a ten-fold lower inhibitory potency at pH 5, a good indication for pharmacological chaperoning. They increased the levels of lysosomal HexA activity in Tay-Sachs patient fibroblasts having the G269S mutation, the highest prevalent in late-onset Tay-Sachs disease.

Collision Detection of a HEXA Parallel Robot Based on Dynamic Model and a Multi-Dual Depth Camera System.

This paper introduces a Hexa parallel robot and obstacle collision detection method based on dynamic modeling and a computer vision system. The processes to deal with the collision issues refer to collision detection, collision isolation, and collision identification applied to the Hexa robot, respectively, in this paper. Initially, the configuration, kinematic and dynamic characteristics during movement trajectories of the Hexa parallel robot are analyzed to perform the knowledge extraction for the method. Next, a virtual force sensor is presented to estimate the collision detection signal created as a combination of the solution to the inverse dynamics and a low-pass filter. Then, a vision system consisting of dual-depth cameras is designed for obstacle isolation and determining the contact point location at the end-effector, an arm, and a rod of the Hexa robot. Finally, a recursive Newton-Euler algorithm is applied to compute contact forces caused by collision cases with the real-Hexa robot. Based on the experimental results, the force identification is compared to sensor forces for the performance evaluation of the proposed collision detection method.

CRISPR/nCas9-Based Genome Editing on GM2 Gangliosidoses Fibroblasts via Non-Viral Vectors.

The gangliosidoses GM2 are a group of pathologies mainly affecting the central nervous system due to the impaired GM2 ganglioside degradation inside the lysosome. Under physiological conditions, GM2 ganglioside is catabolized by the ß-hexosaminidase A in a GM2 activator protein-dependent mechanism. In contrast, uncharged substrates such as globosides and some glycosaminoglycans can be hydrolyzed by the ß-hexosaminidase B. Monogenic mutations on HEXA, HEXB, or GM2A genes arise in the Tay-Sachs (TSD), Sandhoff (SD), and AB variant diseases, respectively. In this work, we validated a CRISPR/Cas9-based gene editing strategy that relies on a Cas9 nickase (nCas9) as a potential approach for treating GM2 gangliosidoses using in vitro models for TSD and SD. The nCas9 contains a mutation in the catalytic RuvC domain but maintains the active HNH domain, which reduces potential off-target effects. Liposomes (LPs)- and novel magnetoliposomes (MLPs)-based vectors were used to deliver the CRISPR/nCas9 system. When LPs were used as a vector, positive outcomes were observed for the ß-hexosaminidase activity, glycosaminoglycans levels, lysosome mass, and oxidative stress. In the case of MLPs, a high cytocompatibility and transfection ratio was observed, with a slight increase in the ß-hexosaminidase activity and significant oxidative stress recovery in both TSD and SD cells. These results show the remarkable potential of CRISPR/nCas9 as a new alternative for treating GM2 gangliosidoses, as well as the superior performance of non-viral vectors in enhancing the potency of this therapeutic approach.

[Lysosomal enzyme analysis of mucolipidosis type II α/ß and type III α/ß in two Chinese pedigrees].

OBJECTIVE: To analyze the characteristics of lysosomal enzymes in mucolipidosis (ML) type II α/ß and type III α/ß for the choice of enzyme evaluating indicators. METHODS: Multiple lysosomal enzymes including α-iduronidase (IDUA), α -N-acetylglucosaminidase (NAGLU), ß-galactosidase-1 (GLB1), ß-glucuronidase (GUSB), α-galactosidase A (GLA), glucocerebrosidase (GBA) and arylsulphatase A (ASA) in plasma and leukocyte of two Chinese pedigrees with ML type II α/ß and type III α/ß and healthy controls were determined. Previous publications on ML type II α/ß and type III α/ß during the last five years were retrieved from PubMed, CNKI and WanFang databases by using "mucolipidosis" as key word. RESULTS: The activities of several lysosomal enzymes were increased in the plasma of both patients: ASA, IDUA (20-fold) > GUSB (10-fold) > GLB1, GLA (5-fold) > NAGLU (2-fold), whilst there was no significant change in GBA. The activities of several lysosomal enzymes in the leukocyte of the two patients were normal. 15 lysosomal enzymes have been used in 22 previous studies, the most frequently used were hexosaminidase A and B (Hex A+B) (12 papers), α-mannosidase (α-man) (11 papers) and GUSB (10 papers). The degree of Hex A+B and α-man elevation was most obvious (24.4-fold and 24.7-fold on average respectively), followed by ASA (22.4-fold on average), GUSB is 18.8-fold on average. CONCLUSION: Based on the lysosomal enzyme analysis of the two cases and literature review, ASA, GUSB, Hex A+B and α-man are recommended as the evaluating indicators for lysosomal enzyme analysis of ML type II α/ß and type III α/ß.

[Clinical characteristics and genetic analysis of a child with infantile Sandhoff disease and eosinophilia].

OBJECTIVE: To explore the genetic basis for a girl featuring epilepsy, developmental delay and regression. METHODS: Clinical data of the patient was collected. Activities of hexosaminidase A (Hex A) and hexosaminidase A&B (Hex A&B) in blood leukocytes were determined by using a fluorometric assay. Peripheral blood samples were collected from the proband and six members from her pedigree. Following extraction of genomic DNA, whole exome sequencing was carried out. Candidate variants were verified by Sanger sequencing. RESULTS: Enzymatic studies of the proband have shown reduced plasma Hex A and Hex A&B activities. Genetic testing revealed that she has carried c.1260_1263del and c.1601G>C heterozygous compound variants of the HEXB gene. Her mother, brother and sister were heterozygous carriers of c.1260_1263del, while her father, mother, three brothers and sister did not carry the c.1601G>C variant, suggesting that it has a de novo origin. Increased eosinophils were discovered upon cytological examination of peripheral blood and bone marrow samples. CONCLUSION: The compound heterozygous variants of c.1260_1263del and c.1601G>C of the HEXB gene probably underlay the Sandhoff disease in this child. Eosinophilia may be noted in infantile Sandhoff disease.

Hexa-Longin domain scaffolds for inter-Rab signalling.

SUMMARY: CPLANE is a protein complex required for assembly and maintenance of primary cilia. It contains several proteins, such as INTU, FUZ, WDPCP, JBTS17 and RSG1 (REM2- and RAB-like small GTPase 1), whose genes are mutated in ciliopathies. Using two contrasting evolutionary analyses, coevolution-based contact prediction and sequence conservation, we first identified the INTU/FUZ heterodimer as a novel member of homologous HerMon (Hermansky-Pudlak syndrome and MON1-CCZ1) complexes. Subsequently, we identified homologous Longin domains that are triplicated in each of these six proteins (MON1A, CCZ1, HPS1, HPS4, INTU and FUZ). HerMon complexes are known to be Rab effectors and Rab GEFs (Guanine nucleotide Exchange Factors) that regulate vesicular trafficking. Consequently, INTU/FUZ, their homologous complex, is likely to act as a GEF during activation of Rab GTPases involved in ciliogenesis. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

A pathogenic HEXA missense variant in wild boars with Tay-Sachs disease.

Gangliosidoses are inherited lysosomal storage disorders caused by reduced or absent activity of either a lysosomal enzyme involved in ganglioside catabolism, or an activator protein required for the proper activity of a ganglioside hydrolase, which results in the intra-lysosomal accumulation of undegraded metabolites. We hereby describe morphological, ultrastructural, biochemical and genetic features of GM2 gangliosidosis in three captive bred wild boar littermates. The piglets were kept in a partially-free range farm and presented progressive neurological signs, starting at 6 months of age. Animals were euthanized at approximately one year of age due to their poor conditions. Neuropathogens were excluded as a possible cause of the signs. Gross examination showed a reduction of cerebral and cerebellar consistency. Central (CNS) and peripheral (PNS) nervous system neurons were enlarged and foamy, with severe and diffuse cytoplasmic vacuolization. Transmission electron microscopy (TEM) of CNS neurons demonstrated numerous lysosomes, filled by parallel or concentric layers of membranous electron-dense material, defined as membranous cytoplasmic bodies (MCB). Biochemical composition of gangliosides analysis from CNS revealed accumulation of GM2 ganglioside; furthermore, Hex A enzyme activity was less than 1% compared to control animals. These data confirmed the diagnosis of GM2 gangliosidosis. Genetic analysis identified, at a homozygous level, the presence of a missense nucleotide variant c.1495C > T (p Arg499Cys) in the hexosaminidase subunit alpha gene (HEXA), located within the GH20 hexosaminidase superfamily domain of the encoded protein. This specific HEXA variant is known to be pathogenic and associated with Tay-Sachs disease in humans, but has never been identified in other animal species. This is the first report of a HEXA gene associated Tay-Sachs disease in wild boars and provides a comprehensive description of a novel spontaneous animal model for this lysosomal storage disease.

Multivalent Tryptophan- and Tyrosine-Containing [60]Fullerene Hexa-Adducts as Dual HIV and Enterovirus A71 Entry Inhibitors.

Unprecedented 3D hexa-adducts of [60]fullerene peripherally decorated with twelve tryptophan (Trp) or tyrosine (Tyr) residues have been synthesized. Studies on the antiviral activity of these novel compounds against HIV and EV71 reveal that they are much more potent against HIV and equally active against EV71 than the previously described dendrimer prototypes AL-385 and AL-463, which possess the same number of Trp/Tyr residues on the periphery but attached to a smaller and more flexible pentaerythritol core. These results demonstrate the relevance of the globular 3D presentation of the peripheral groups (Trp/Tyr) as well as the length of the spacer connecting them to the central core to interact with the viral envelopes, particularly in the case of HIV, and support the hypothesis that [60]fullerene can be an alternative and attractive biocompatible carbon-based scaffold for this type of highly symmetrical dendrimers. In addition, the functionalized fullerenes here described, which display twelve peripheral negatively charged indole moieties on their globular surface, define a new and versatile class of compounds with a promising potential in biomedical applications.

Tay-Sachs Disease: Two Novel Rare HEXA Mutations from Pakistan and Morocco.

BACKGROUND: Tay-Sachs disease (TSD) is a rare autosomalrecessive genetic disorder characterized by progressive destruction of nerve cells in the brain and spinal cord. It is caused by genetic variations in the HEXA gene leading to a deficiency of ß hexosaminidase A (HEXA) isoenzyme activity. This study aimed to identify causative gene variants in 3 unrelated consanguineous families presented with TSD from Pakistan and Morocco. METHODS: Detailed clinical investigations were carried out on probands in 3 unrelated consanguineous families of Pakistani and Moroccan origin. Targeted gene sequencing and Whole Exome Sequencing (WES) were performed for variant identification. Candidate variants were checked for co-segregation with the phenotype using Sanger sequencing. Public databases including ExAC, GnomAD, dbSNP and the 1,000 Genome Project were searched to determine frequencies of the alleles. Conservation of the missense variants was ensured by aligning orthologous protein sequences from diverse vertebrate species. RESULTS: We report on 3 children presented with Tay-Sachs Disease. The ß hexosaminidaseA enzyme activity was reduced in the Pakistani patient in one of the pedigrees. Genetic testing revealed 2 novel homozygous variants (p.Asp386Alafs*13 and p.Trp266Gly) in the gene HEXA in Pakistani and Moroccan patients respectively.The third family of Pakistani origin revealed a previously reported variant (p.Tyr427Ilefs*5) in HEXA. p.Tyr427Ilefs*5 is the most commonly occurring pathogenic variationin Ashkenazi but was not reported in Pakistani population. CONCLUSION: Our study further expands the ethnic and mutational spectrum of Tay-Sachs disease emphasizing the usefulness of WES as a powerful diagnostic tool where enzymatic activity is not performed for Tay-Sachs disease. The study recommends targeted screening for these mutations (p.Tyr427Ilefs5) for cost effective testing of TSD patients. Further, the study would assist in carrier testing and prenatal diagnosis of the affected families.

Atypical presentation of late-onset Sandhoff disease: a case report.

BACKGROUND AND PURPOSE: Sandhoff disease is a rare type of hereditary (autosomal recessive) GM2-gangliosidosis, which is caused by mutation of the HEXB gene. Disruption of the ß subunit of the hexosaminidase (Hex) enzyme affects the function of both the Hex-A and Hex-B isoforms. The severity and the age of onset of the disease (infantile or classic; juvenile; adult) depends on the residual activity of the enzyme. The late-onset form is characterized by diverse symptomatology, comprising motor neuron disease, ataxia, tremor, dystonia, psychiatric symptoms and neuropathy. METHODS: A 36-year-old female patient has been presenting progressive, symmetrical lower limb weakness for 9 years. Detailed neurological examination revealed mild symmetrical weakness in the hip flexors without the involvement of other muscle groups. The patellar reflex was decreased on both sides. Laboratory tests showed no relevant alteration and routine electroencephalography and brain MRI were normal. Nerve conduction studies and electromyography revealed alterations corresponding to sensory neuropathy. Muscle biopsy demonstrated signs of mild neurogenic lesion. Her younger brother (32-year-old) was observed with similar symptoms. RESULTS: Detailed genetic study detected a known pathogenic missense mutation and a 15,088 base pair long known pathogenic deletion in the HEXB gene (NM_000521.4:c.1417G>A; NM_000521:c.-376-5836_669+1473del; double heterozygous state). Segregation analysis and hexosaminidase enzyme assay of the family further confirmed the diagnosis of late-onset Sandhoff disease. CONCLUSION: The purpose of this case report is to draw attention to the significance of late-onset Sandhoff disease amongst disorders presenting with proximal predominant symmetric lower limb muscle weakness in adulthood.

Push-Pull Zinc Phthalocyanine Bearing Hexa-Tertiary Substituted Carbazolyl Donor Groups for Dye-Sensitized Solar Cells.

An asymmetrical, push-pull phthalocyanine bearing bulky tert-butylcarbazolyl moieties as electron donor and carboxylic acid as anchoring group was synthetized and tested as a photosensitizer in dye-sensitized solar cells (DSSC). The new photosensitizer was characterized by 1H and 13C NMR, UV-Vis and mass spectrometry. The bulky tert-butylcarbazolyl moieties avoid the aggregation of the phthalocyanine dye. DFT studies indicate that the HOMO is delocalized throughout the -electron system of the substituted phthalocyanine and the LUMO is located on the core of the molecule with a sizable electron density distribution on carboxyl groups. The new dye has been used as a photosensitizer in transparent and opaque dye-sensitized solar cells, which exhibit poor efficiencies related to a low Jsc.

Lysosomal Proteins as a Therapeutic Target in Neurodegeneration.

Several proteins that are mutated in lysosomal storage diseases are linked to neurodegenerative disease. This review focuses on some of these lysosomal enzymes and transporters, as well as current therapies that have emerged from the lysosomal storage disease field. Given the deeper genetic understanding of lysosomal defects in neurodegeneration, we explore why some of these orphan disease drug candidates are also attractive targets in subpopulations of individuals with neurodegenerative disease.

Phosphorylated Hexa-Acyl Disaccharides Augment Host Resistance Against Common Nosocomial Pathogens.

OBJECTIVES: To determine whether synthetic phosphorylated hexa-acyl disaccharides provide antimicrobial protection in clinically relevant models of bacterial infection. DESIGN: Laboratory study. SETTING: University laboratory. SUBJECTS: BALB/c, C57BL/10J, and C57BL/10ScNJ mice. INTERVENTIONS: Mice were treated with lactated Ringer's (vehicle) solution, monophosphoryl lipid A, or phosphorylated hexa-acyl disaccharides at 48 and 24 hours prior to intraperitoneal Pseudomonas aeruginosa or IV Staphylococcus aureus infection. Leukocyte recruitment, cytokine production, and bacterial clearance were measured 6 hours after P. aeruginosa infection. In the systemic S. aureus infection model, one group of mice was monitored for 14-day survival and another for S. aureus tissue burden at 3 days postinfection. Duration of action for 3-deacyl 6-Acyl phosphorylated hexa-acyl disaccharide was determined at 3, 10, and 14 days using a model of intraperitoneal P. aeruginosa infection. Effect of 3-deacyl 6-Acyl phosphorylated hexa-acyl disaccharide on in vivo leukocyte phagocytosis and respiratory burst was examined. Leukocyte recruitment, cytokine production, and bacterial clearance were measured after P. aeruginosa infection in wild-type and toll-like receptor 4 knockout mice treated with 3-deacyl 6-Acyl phosphorylated hexa-acyl disaccharide or vehicle to assess receptor specificity. MEASUREMENTS AND MAIN RESULTS: During intraperitoneal P. aeruginosa infection, phosphorylated hexa-acyl disaccharides significantly attenuated infection-induced hypothermia, augmented leukocyte recruitment and bacterial clearance, and decreased cytokine production. At 3 days post S. aureus infection, bacterial burden in lungs, spleen, and kidneys was significantly decreased in mice treated with monophosphoryl lipid A or phosphorylated hexa-acyl disaccharides, which was associated with improved survival. Leukocyte phagocytosis and respiratory burst functions were enhanced after treatment with monophosphoryl lipid A or phosphorylated hexa-acyl disaccharides. A time course study showed that monophosphoryl lipid A- and 3-deacyl 6-Acyl phosphorylated hexa-acyl disaccharide-mediated protection against P. aeruginosa lasts for up to 10 days. Partial loss of augmented innate antimicrobial responses was observed in toll-like receptor 4 knockout mice treated with 3-deacyl 6-Acyl phosphorylated hexa-acyl disaccharide. CONCLUSIONS: Phosphorylated hexa-acyl disaccharides significantly augment resistance against clinically relevant Gram-negative and Gram-positive infections via enhanced leukocyte recruitment, phagocytosis, and respiratory burst functions of innate leukocytes. Improved antimicrobial protection persists for up to 10 days and is partially mediated through toll-like receptor 4.

Introduction of a C-terminal hexa-lysine tag increases thermal stability of the LacDiNac binding adhesin (LabA) exodomain from Helicobacter pylori.

Helicobacter pylori is a pathogenic microorganism infecting approximately 50% of the global population, and establishes life-long colonization despite the hostile stomach environment. H. pylori employs a wide range of outer membrane proteins (adhesins) for epithelial attachment, which specifically bind to glycans or non-carbohydrate structures expressed on the gastric epithelium. A recently described adhesin from H. pylori is LabA, named after its ability to bind to a disaccharide present in gastric mucus (LacdiNAc-specific adhesin). Here, we describe the recombinant expression of LabA from H. pylori strains J99 and 26695 in E. coli. High yields of recombinant LabA were obtained using periplasmic expression. We found that the addition of a C-terminal hexalysine (6K) tag enhanced the thermal stability of LabA without affecting its secondary structure, using differential scanning fluorimetry and circular dichroism spectroscopy. In contrast to our previous report for another H. pylori adhesin (BabA), the 6K tag did not enhance recombinant protein yield or solubility. Both versions of LabA, with or without the 6K tag, were expressed and isolated from the periplasmic space of Escherichia coli, with a surprisingly high yield of at least 40 mg/L for each independent preparation, following a two-step purification protocol. The proteins were analyzed with mass spectrometry (MS). Unlike its reported effect on stability of BabA, the 6K tag did not appear to protect the N-term of recombinant LabA from partial periplasmic degradation.