scholarly journals A native chemical chaperone in the human eye lens

2020 ◽  
Author(s):  
Eugene Serebryany ◽  
Sourav Chowdhury ◽  
Christopher N. Woods ◽  
David C. Thorn ◽  
Nicki E Watson ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Vision Loss ◽  
Human Lens ◽  
Lens Crystallins ◽  
Chemical Chaperone ◽  
Negative Stain ◽  
Molecular Mechanism Of Action ◽  
Redox Buffers ◽  
Rate Limiting

Cataract is one of the most prevalent protein aggregation disorders and still the most common cause of vision loss worldwide. The metabolically quiescent core region of the human lens lacks cellular or protein turnover; it has therefore evolved remarkable mechanisms to resist light-scattering protein aggregation for a lifetime. We now report that one such mechanism involves an unusually abundant lens metabolite, myo-inositol, suppressing aggregation of lens crystallins. We quantified aggregation suppression using our previously well-characterized in vitro aggregation assays of oxidation-mimicking human γD-crystallin variants and investigated myo-inositol's molecular mechanism of action using solution NMR, negative-stain TEM, differential scanning fluorometry, thermal scanning Raman spectroscopy, turbidimetry in redox buffers, and free thiol quantitation. Unlike many known chemical chaperones, myo-inositol's primary target was neither the native nor the unfolded state of the protein, nor the final aggregated state, but rather the rate-limiting bimolecular step on the aggregation pathway. Given recent metabolomic evidence that it is severely depleted in human cataractous lenses compared to age-matched controls, we suggest that maintaining or restoring healthy levels of myo-inositol in the lens may be a simple, safe, and globally accessible strategy to prevent or delay lens opacification due to age-onset cataract.

scholarly journals P 207 Bendazac decreases in vitro glycation of human lens crystallins

1995 ◽  
Vol 35 ◽  
pp. S194
Author(s):  
C. Marques ◽  
J.S. Ramalho ◽  
P. Pereira ◽  
M.C. Mota
Keyword(s):  
Human Lens ◽  
Lens Crystallins

scholarly journals The Chemical Chaperone Proline Relieves the Thermosensitivity of a dnaK Deletion Mutant at 42°C

2004 ◽  
Vol 186 (23) ◽  
pp. 8149-8152 ◽  
Author(s):  
Madhab K. Chattopadhyay ◽  
Renée Kern ◽  
Michel-Yves Mistou ◽  
Abhaya M. Dandekar ◽  
Sandra L. Uratsu ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Citrate Synthase ◽  
Feedback Inhibition ◽  
Single Mutation ◽  
Two Dimensional Gel Electrophoresis ◽  
Chemical Chaperone ◽  
E Coli ◽  
Amino Acid Biosynthetic Pathway

ABSTRACT Since, like other osmolytes, proline can act as a protein stabilizer, we investigated the thermoprotectant properties of proline in vitro and in vivo. In vivo, elevated proline pools in Escherichia coli (obtained by altering the feedback inhibition by proline of γ-glutamylkinase, the first enzyme of the proline biosynthesis pathway) restore the viability of a dnaK-deficient mutant at 42°C, suggesting that proline can act as a thermoprotectant for E. coli cells. Furthermore, analysis of aggregated proteins in the dnaK-deficient strain at 42°C by two-dimensional gel electrophoresis shows that high proline pools reduce the protein aggregation defect of the dnaK-deficient strain. In vitro, like other “chemical chaperones,” and like the DnaK chaperone, proline protects citrate synthase against thermodenaturation and stimulates citrate synthase renaturation after urea denaturation. These results show that a protein aggregation defect can be compensated for by a single mutation in an amino acid biosynthetic pathway and that an ubiquitously producible chemical chaperone can compensate for a defect in one of the major chaperones involved in protein folding and aggregation.

scholarly journals Arginine is a disease modifier for polyQ disease models that stabilizes polyQ protein conformation

Brain ◽  
2020 ◽  
Vol 143 (6) ◽  
pp. 1811-1825 ◽  
Author(s):  
Eiko N Minakawa ◽  
Helena Akiko Popiel ◽  
Masayoshi Tada ◽  
Toshiaki Takahashi ◽  
Hiroshi Yamane ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Protein Conformation ◽  
Conformational Transition ◽  
Therapeutic Effects ◽  
Chemical Chaperone ◽  
Polyq Protein ◽  
Disease Modifier ◽  
Polyq Diseases ◽  
Β Sheet

Abstract The polyglutamine (polyQ) diseases are a group of inherited neurodegenerative diseases that include Huntington’s disease, various spinocerebellar ataxias, spinal and bulbar muscular atrophy, and dentatorubral pallidoluysian atrophy. They are caused by the abnormal expansion of a CAG repeat coding for the polyQ stretch in the causative gene of each disease. The expanded polyQ stretches trigger abnormal β-sheet conformational transition and oligomerization followed by aggregation of the polyQ proteins in the affected neurons, leading to neuronal toxicity and neurodegeneration. Disease-modifying therapies that attenuate both symptoms and molecular pathogenesis of polyQ diseases remain an unmet clinical need. Here we identified arginine, a chemical chaperone that facilitates proper protein folding, as a novel compound that targets the upstream processes of polyQ protein aggregation by stabilizing the polyQ protein conformation. We first screened representative chemical chaperones using an in vitro polyQ aggregation assay, and identified arginine as a potent polyQ aggregation inhibitor. Our in vitro and cellular assays revealed that arginine exerts its anti-aggregation property by inhibiting the toxic β-sheet conformational transition and oligomerization of polyQ proteins before the formation of insoluble aggregates. Arginine exhibited therapeutic effects on neurological symptoms and protein aggregation pathology in Caenorhabditis elegans, Drosophila, and two different mouse models of polyQ diseases. Arginine was also effective in a polyQ mouse model when administered after symptom onset. As arginine has been safely used for urea cycle defects and for mitochondrial myopathy, encephalopathy, lactic acid and stroke syndrome patients, and efficiently crosses the blood–brain barrier, a drug-repositioning approach for arginine would enable prompt clinical application as a promising disease-modifier drug for the polyQ diseases.

Bendazac decreases in vitro glycation of human lens crystallins

1995 ◽  
Vol 35 (1) ◽  
pp. S194
Author(s):  
C Marques
Keyword(s):  
Human Lens ◽  
Lens Crystallins

scholarly journals P 229 Growth of human lens epithelial cells on the anterior lens capsule in vitro

1995 ◽  
Vol 35 ◽  
pp. S199
Author(s):  
J.H. Meyer ◽  
J. Schmidt ◽  
F. Eppinger ◽  
B. Flügel ◽  
K.U. Löffler ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Lens Capsule ◽  
Human Lens ◽  
Lens Epithelial Cells ◽  
Human Lens Epithelial Cells ◽  
Anterior Lens Capsule

scholarly journals Assembly of the B subunit pentamer of Escherichia coli heat-labile enterotoxin. Kinetics and molecular basis of rate-limiting steps in vitro.

1996 ◽  
Vol 271 (43) ◽  
pp. 27188
Author(s):  
Lloyd W. Ruddock ◽  
Jeremy J.F. Coen ◽  
Caroline Cheesman ◽  
Robert B. Freedman ◽  
Timothy R. Hirst
Keyword(s):  
Escherichia Coli ◽  
Molecular Basis ◽  
B Subunit ◽  
Heat Labile ◽  
Rate Limiting

scholarly journals Nanoceria Prevents Glucose-Induced Protein Glycation in Eye Lens Cells

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1473
Author(s):  
Belal I. Hanafy ◽  
Gareth W. V. Cave ◽  
Yvonne Barnett ◽  
Barbara K. Pierscionek
Keyword(s):  
Protein Glycation ◽  
Human Lens ◽  
Lens Epithelial Cells ◽  
Oxide Nanoparticles ◽  
Lens Protein ◽  
Oxygen Species ◽  
Human Lens Epithelial Cells ◽  
Age Related ◽  
Age Related Changes

Cerium oxide nanoparticles (nanoceria) are generally known for their recyclable antioxidative properties making them an appealing biomaterial for protecting against physiological and pathological age-related changes that are caused by reactive oxygen species (ROS). Cataract is one such pathology that has been associated with oxidation and glycation of the lens proteins (crystallins) leading to aggregation and opacification. A novel coated nanoceria formulation has been previously shown to enter the human lens epithelial cells (HLECs) and protect them from oxidative stress induced by hydrogen peroxide (H2O2). In this work, the mechanism of nanoceria uptake in HLECs is studied and multiple anti-cataractogenic properties are assessed in vitro. Our results show that the nanoceria provide multiple beneficial actions to delay cataract progression by (1) acting as a catalase mimetic in cells with inhibited catalase, (2) improving reduced to oxidised glutathione ratio (GSH/GSSG) in HLECs, and (3) inhibiting the non-enzymatic glucose-induced glycation of the chaperone lens protein α-crystallin. Given the multifactorial nature of cataract progression, the varied actions of nanoceria render them promising candidates for potential non-surgical therapeutic treatment.

scholarly journals Intermediate filaments in non-neuronal cells of invertebrates: isolation and biochemical characterization of intermediate filaments from the esophageal epithelium of the mollusc Helix pomatia.

1985 ◽  
Vol 101 (2) ◽  
pp. 427-440 ◽  
Author(s):  
E Bartnik ◽  
M Osborn ◽  
K Weber
Keyword(s):  
Positive Reaction ◽  
Intermediate Filaments ◽  
Biochemical Characterization ◽  
Helix Pomatia ◽  
Molar Ratio ◽  
Negative Stain ◽  
Epithelial Morphology ◽  
Lower Chordate

To screen invertebrate tissues for the possible expression of intermediate filaments (IFs), immunofluorescence microscopy with the monoclonal antibody anti-IFA known to detect all mammalian IF proteins was used (Pruss, R. M., R. Mirsky, M. C. Raff, R. Thorpe, A. J. Dowding, and B. H. Anderton. 1981. Cell, 27:419-428). In a limited survey, the lower chordate Branchiostoma as well as the invertebrates Arenicola, Lumbricus, Ascaris, and Helix pomatia revealed a positive reaction primarily on epithelia and on nerves, whereas certain other invertebrates appeared negative. To assess the nature of the positive reaction, Helix pomatia was used since a variety of epithelia was strongly stained by anti-IFA. Fixation-extraction procedures were developed that preserve in electron micrographs of esophagus impressive arrays of IFs as tonofilament bundles. Fractionation procedures performed on single cell preparations document large meshworks of long and curvilinear IF by negative stain. These structures can be purified. One- and two-dimensional gels show three components, all of which are recognized by anti-IFA in immunoblotting: 66 kD/pl 6.35, 53 kD/pl 6.05, and 52 kD/pl 5.95. The molar ratio between the larger and more basic polypeptide and the sum of the two more acidic forms is close to 1. After solubilization in 8.5 M urea, in vitro filament reconstitution is induced when urea is removed by dialysis against 2-50 mM Tris buffer at pH 7.8. The reconstituted filaments contain all three polypeptides. The results establish firmly the existence of invertebrate IFs outside neurones and demonstrate that the esophagus of Helix pomatia displays IFs which in line with the epithelial morphology of the tissue could be related to keratin IF of vertebrates.

scholarly journals Uric Acid Is a Genuine Metabolite of Penicillium cyclopium and Stimulates the Expression of Alkaloid Biosynthesis in This Fungus

2002 ◽  
Vol 68 (4) ◽  
pp. 1524-1533 ◽  
Author(s):  
Florian Helbig ◽  
Jörg Steighardt ◽  
Werner Roos
Keyword(s):  
Uric Acid ◽  
Low Molecular Weight ◽  
Alkaloid Production ◽  
Alkaloid Biosynthesis ◽  
Penicillium Cyclopium ◽  
Measurable Activity ◽  
Reduced Rate ◽  
Rate Limiting

ABSTRACT On searching for endogenous, low-molecular-weight effectors of benzodiazepine alkaloid biosynthesis in Penicillium cyclopium uric acid was isolated from ethanolic or autoclaved mycelial extracts of this fungus. The isolation was based on a three-step high-pressure liquid chromatography procedure guided by a microplate bioassay, and uric acid was identified by mass spectrometry and the uricase reaction. Conidiospore suspensions that were treated with this compound during the early phase of outgrowth developed emerged cultures with an enhanced rate of alkaloid production. Uric acid treatment did not increase the in vitro measurable activity of the rate-limiting biosynthetic enzyme, cyclopeptine synthetase. However, these cultures displayed a reduced rate of uptake of the alkaloid precursor l-phenylalanine into the vacuoles of the hyphal cells as assayed in situ. It is suggested that the depressed capacity of vacuolar uptake caused by the contact of outgrowing spores with uric acid liberated from hyphal cells results in an enhanced availability of the precursor l-phenylalanine in the cytoplasm and thus accounts at least in part for the increase in alkaloid production.

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