Dataset Information

Quantitative metabolomic analysis of changes in the lens and aqueous humor under development of age-related nuclear cataract

ABSTRACT:

INTRODUCTION: Metabolites are essential for the proper functioning of the eye lens, they either enter the lens from the aqueous humor (AH), or are synthesized in the lens epithelium. Antioxidants, osmolytes and UV filters are especially important for the lens protection, and their lack may cause the development of ophthalmic diseases.

OBJECTIVES: Comparison of the metabolomic compositions of lenses and AH taken from cataract patients with that taken from human cadavers without cataract can shed light onto molecular mechanisms underlying onset of age-related nuclear cataract.

METHODS: Combined use of 1H nuclear magnetic resonance and high performance liquid chromatography with optical and high-resolution mass spectrometric detection for the identification and quantification of metabolites in the lens and AH extracts.

RESULTS: The concentrations of 86 metabolites were determined for four groups of samples, including lenses and AH from cataract patients and from human cadavers. In cataractous lens the most abundant metabolites are (in descending order): myo-inositol, lactate, acetate, glutamate, glutathione; in AH-lactate, glucose, glutamine, alanine, valine. The concentrations of the majority of metabolites in normal post-mortem samples of both lens and AH are higher than that in samples from the cataract patients.

CONCLUSIONS: Comparison of metabolite concentrations in lens and corresponding AH reveal that the most important for the lens protection metabolites are synthesized in the lens epithelial cells. The reduced levels of antioxidants, UV filters, and osmolytes were found in the cataractous lenses what cannot be explained by post-mortem changes in normal lens; that indicates that the age-related nuclear cataract development may originate from the dysfunction of the lens epithelial cells.

INSTRUMENT(S): Nuclear Magnetic Resonance (NMR)

SUBMITTER: Vadim Yanshole

PROVIDER: MTBLS740 | MetaboLights | 2022-11-07

REPOSITORIES: MetaboLights

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Publications

Quantitative metabolomic analysis of changes in the lens and aqueous humor under development of age-related nuclear cataract.

Yanshole Vadim V VV Yanshole Lyudmila V LV Snytnikova Olga A OA Tsentalovich Yuri P YP

Metabolomics : Official journal of the Metabolomic Society 20190226 3

<h4>Introduction</h4>Metabolites are essential for the proper functioning of the eye lens, they either enter the lens from the aqueous humor (AH), or are synthesized in the lens epithelium. Antioxidants, osmolytes and UV filters are especially important for the lens protection, and their lack may cause the development of ophthalmic diseases.<h4>Objectives</h4>Comparison of the metabolomic compositions of lenses and AH taken from cataract patients with that taken from human cadavers without catar ...[more]

PMID: 30830501

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Project description:Introduction: The optical elements of the eye – cornea, lens, and vitreous humor – are avascular tissues, and their nutrition and waste removal are provided by aqueous humor (AH). The AH production occurs through the active secretion and the passive diffusion/ultrafiltration of blood plasma. The comparison of the metabolomic profiles of aqueous humor (AH) and plasma is important for understanding of the mechanisms of biochemical processes and metabolite transport taking place in vivo in ocular tissues. Objectives: The work is aimed at the determination of concentrations of a wide range of most abundant metabolites in the human AH, the comparison of the metabolomic profiles of AH and serum, and the analysis of the post-mortem metabolomic changes in these two biological fluids. Methods: The quantitative metabolomic profiling was carried out with the use of two independent methods – high-frequency 1H NMR spectroscopy and HPLC with high-resolution ESI-MS detection (LC-MS). Results: The concentrations of 71 most abundant metabolites in blood serum and AH from living patients and human cadavers have been measured. It has been found that the level of ascorbate in AH is by two orders of magnitude higher than that in serum; the levels of other metabolites are either similar to that in serum, or differ from that by a factor of 2-5. The post-mortem metabolomic composition of both serum and AH undergoes rapid and strong changes. Conclusion: The differences between the metabolomic profiles of AH and serum for majority of metabolites can be attributed to the metabolic activity of the ocular tissues leading to the lack or excess of some metabolites, while the high concentration of ascorbate in AH demonstrates the activity of ascorbate-specific pumps at the blood-aqueous border. The post-mortem metabolomic changes are caused by the disruption of the major biochemical cycles and cell lysis. These changes should be taken into account in the analysis of disease-induced changes in post-mortem samples of the ocular tissues.

Project description:Mutations of the RNA-granule component TDRD7 (OMIM: 611258) cause pediatric cataract in humans. Here, we applied an integrated approach to elucidate the molecular pathology of cataract in Tdrd7 targeted-knockout (Tdrd7-/-) mice. Tdrd7-/- animals precipitously develop lens fiber cell abnormalities early in life, suggesting a global-level breakdown/mis-regulation of key cellular processes. High-throughput RNA-sequencing followed by iSyTE-integrated bioinformatics-based analysis identified the molecular chaperone and cytoskeletal-modulator, HSPB1 (HSP27), among the high-priority down-regulated candidates in Tdrd7-/- lens. Moreover, a protein 2-D fluorescence difference gel electrophoresis-coupled mass spectrometry screen also identified HSPB1 to be reduced in Tdrd7-/- lens, offering independent support for focusing efforts on this factor to explain Tdrd7-/- cataract. Reduction of HSPB1 preceded lens morphological abnormalities, suggesting that cytoskeletal defects underlie the Tdrd7-/- cataract phenotype. In agreement, scanning electron microscopy revealed abnormal fiber cell membrane protrusions in Tdrd7-/- lenses. Significantly, abnormal F-actin staining was detected specifically in Tdrd7-/- fiber cells that exhibit nuclear degradation, thereby revealing that there are distinct mechanisms based on pre- or post-nuclear degradation differentiation stage for F-actin cytoskeletal maintenance in fiber cells. Further, RNA-immunoprecipitation identified Hspb1 mRNA in wild-type lens lysate TDRD7-pulldowns, and single-molecule RNA-imaging showed co-localization of TDRD7 protein with cytoplasmic Hspb1 mRNA in a specific pre-nuclear degradation area of differentiating fiber cells, indicating that TDRD7-ribonucleoprotein complexes are necessary for controlling optimal levels of key factors in lens development. Together, these data uncover a novel role for TDRD7 in regulating elevation of stress-responsive chaperones for cytoskeletal maintenance in post-nuclear degradation lens fiber cells, perturbation of which causes early-onset cataracts.

Dataset Information

Quantitative metabolomic analysis of changes in the lens and aqueous humor under development of age-related nuclear cataract

Publications

Quantitative metabolomic analysis of changes in the lens and aqueous humor under development of age-related nuclear cataract.

Similar Datasets

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