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1.
Invest Ophthalmol Vis Sci ; 62(14): 5, 2021 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-34730792

RESUMO

Purpose: The arrangement of lens cells is regulated by ocular growth factors. Although the effects of these inductive molecules on lens cell behavior (proliferation, survival, and fiber differentiation) are well-characterized, the precise mechanisms underlying the regulation of growth factor-mediated signaling in lens remains elusive. Increasing evidence highlights the importance of heparan sulfate proteoglycans (HSPGs) for the signaling regulation of growth factors; however, the identity of the different lens HSPGs and the specific roles they play in lens biology are still unknown. Methods: Semiquantitative real-time (RT)-PCR and immunolabeling were used to characterize the spatial distribution of all known HSPG core proteins and their associated glycosaminoglycans (heparan and chondroitin sulfate) in the postnatal rat lens. Fibroblast growth factor (FGF)-2-treated lens epithelial explants, cultured in the presence of Surfen (an inhibitor of heparan sulfate [HS]-growth factor binding interactions) were used to investigate the requirement for HS in FGF-2-induced proliferation, fiber differentiation, and ERK1/2-signaling. Results: The lens expresses all HSPGs. These HSPGs are differentially localized to distinct functional regions of the lens. In vitro, inhibition of HS-sulfation with Surfen blocked FGF-2-mediated ERK1/2-signaling associated with lens epithelial cell proliferation and fiber differentiation, highlighting that these cellular processes are dependent on HS. Conclusions: These findings support a requirement for HSPGs in FGF-2 driven lens cell proliferation and fiber differentiation. The identification of specific HSPG core proteins in key functional lens regions, and the divergent expression patterns of closely related HSPGs, suggests that different HSPGs may differentially regulate growth factor signaling networks leading to specific biological events involved in lens growth and maintenance.


Assuntos
Regulação da Expressão Gênica/fisiologia , Proteoglicanas de Heparan Sulfato/genética , Cristalino/metabolismo , Animais , Animais Recém-Nascidos , Western Blotting , Diferenciação Celular/fisiologia , Proliferação de Células/fisiologia , Sulfatos de Condroitina/metabolismo , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Fator 2 de Crescimento de Fibroblastos/farmacologia , Proteoglicanas de Heparan Sulfato/metabolismo , Heparitina Sulfato/antagonistas & inibidores , Heparitina Sulfato/metabolismo , Cristalino/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/fisiologia , Técnicas de Cultura de Órgãos , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais , Ureia/análogos & derivados , Ureia/farmacologia
2.
Invest Ophthalmol Vis Sci ; 62(12): 3, 2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-34495288

RESUMO

Purpose: Age-related cataract is the leading cause of blindness worldwide. Variants in the EPHA2 gene increase the disease risk, and its knockout in mice causes cataract. We investigated whether age, sex, and genetic background, risk factors for age-related cataract, and Epha2 genotype influence Epha2-related cataract development in mice. Methods: Cataract development was monitored in Epha2+/+, Epha2+/-, and Epha2-/- mice (Epha2Gt(KST085)Byg) on C57BL/6J and FVB:C57BL/6J (50:50) backgrounds. Cellular architecture of lenses, endoplasmic reticulum (ER) stress, and redox state were determined using histological, molecular, and analytical techniques. Results: Epha2-/- and Epha2+/- mice on C57BL/6J background developed severe cortical cataracts by 18 and 38 weeks of age, respectively, compared to development of similar cataract significantly later in Epha2-/- mice and no cataract in Epha2+/- mice in this strain on FVB background, which was previously reported. On FVB:C57BL/6J background, Epha2-/- mice developed severe cortical cataract by 38 weeks and Epha2+/- mice exhibited mild cortical cataract up to 64 weeks of age. Progression of cataract in Epha2-/- and Epha2+/- female mice on C57BL/6J and mixed background, respectively, was slower than in matched male mice. N-cadherin and ß-catenin immunolabeling showed disorganized lens fiber cells and disruption of lens architecture in Epha2-/- and Epha2+/- lenses, coinciding with development of severe cataracts. EPHA2 immunolabeling showed intracellular accumulation of the mutant EPHA2-ß-galactosidase fusion protein that induced a cytoprotective ER stress response and in Epha2+/- lenses was also accompanied by glutathione redox imbalance. Conclusions: Both, Epha2-/- and Epha2+/- mice develop age-related cortical cataract; age as a function of Epha2 genotype, sex, and genetic background influence Epha2-related cataractogenesis in mice.


Assuntos
Catarata/genética , Regulação da Expressão Gênica , Cristalino/metabolismo , RNA/genética , Receptor EphA2/genética , Animais , Catarata/diagnóstico , Catarata/metabolismo , Modelos Animais de Doenças , Genótipo , Cristalino/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor EphA2/biossíntese
3.
PLoS One ; 16(9): e0257098, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34520490

RESUMO

αB-crystallin is a small heat shock protein that forms a heterooligomeric complex with αA-crystallin in the ocular lens. It is also widely distributed in tissues throughout the body and has been linked with neurodegenerative diseases such as Alzheimer's, where it is associated with amyloid fibrils. Crystallins can form amorphous aggregates in cataracts as well as more structured amyloid-like fibrils. The arginine 120 to glycine (R120G) mutation in αB-crystallin (Cryab-R120G) results in high molecular weight crystallin protein aggregates and loss of the chaperone activity of the protein in vitro, and it is associated with human hereditary cataracts and myopathy. Characterizing the amorphous (unstructured) versus the highly ordered (amyloid fibril) nature of crystallin aggregates is important in understanding their role in disease and important to developing pharmacological treatments for cataracts. We investigated protein secondary structure in wild-type (WT) and Cryab-R120G knock-in mutant mouse lenses using two-dimensional infrared (2DIR) spectroscopy, which has been used to detect amyloid-like fibrils in human lenses and measure UV radiation-induced changes in porcine lenses. Our goal was to compare the aggregated proteins in this mouse lens model to human lenses and evaluate the protein structural relevance of the Cryab-R120G knock-in mouse model to general age-related cataract disease. In the 2DIR spectra, amide I diagonal peak frequencies were red-shifted to smaller wavenumbers in mutant mouse lenses as compared to WT mouse lenses, consistent with an increase in ordered secondary structure. The cross peak frequency and intensity indicated the presence of amyloid in the mutant mouse lenses. While the diagonal and cross peak changes in location and intensity from the 2DIR spectra indicated significant structural differences between the wild type and mutant mouse lenses, these differences were smaller than those found in human lenses; thus, the Cryab-R120G knock-in mouse lenses contain less amyloid-like secondary structure than human lenses. The results of the 2DIR spectroscopy study confirm the presence of amyloid-like secondary structure in Cryab-R120G knock-in mice with cataracts and support the use of this model to study age-related cataract.


Assuntos
Amiloide/metabolismo , Catarata/genética , Técnicas de Introdução de Genes , Espectrofotometria Infravermelho , Cadeia B de alfa-Cristalina/química , Cadeia B de alfa-Cristalina/genética , Animais , Modelos Animais de Doenças , Formaldeído , Humanos , Cristalino/metabolismo , Camundongos Endogâmicos C57BL , Proteínas Mutantes/metabolismo , Inclusão em Parafina , Estrutura Secundária de Proteína , Fixação de Tecidos
4.
PLoS One ; 16(9): e0256975, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34499644

RESUMO

Lens and skin fluorescence are related to the systemic accumulation of advanced glycation end products, which is accelerated in diabetes. We have examined lens fluorescence and skin fluorescence in healthy adult twins. The study enrolled twins aged median 59 years from a national population-based registry. Diabetic individuals were excluded from analysis. The interrelatedness between fluorescence parameters and relations between fluorescence and age, current HbA1c and smoking pack years were examined using correlation tests and mixed model linear regression analyses. Broad-sense heritability was analyzed and compared for lens fluorescence, skin fluorescence and HbA1c. Lens fluorescence and skin fluorescence were crudely interrelated (R = 0.38). In linear regression analyses, age explained a larger fraction of the variance in lens fluorescence (R2 = 32%) than in skin fluorescence (R2 = 20%), whereas HbA1c explained smaller variance fractions (R2 = 3% and 8%, respectively) followed by smoking pack years (4% and 3%, respectively). In multivariate analyses, age, HbA1c and smoking pack years combined explained more of the variance in lens fluorescence (R2 = 35%) than in skin fluorescence (R2 = 21%), but the influence of HbA1c on lens fluorescence was not statistically significant (p = .2). Age-adjusted broad-sense heritability was 85% for lens fluorescence, 53% for skin fluorescence and 71% for HbA1c in best fitting heritability models. Both fluorescence parameters increased with age, current glycemia and cumulative smoking. Lens fluorescence was found to be a predominantly heritable trait, whereas skin fluorescence was more influenced by environmental factors and closer related to current glycemia. The results suggest that skin fluorophores have a faster turn-over than lens fluorophores.


Assuntos
Olho/anatomia & histologia , Cristalino/anatomia & histologia , Fenômenos Fisiológicos Oculares/genética , Pele/anatomia & histologia , Pré-Escolar , Estudos de Coortes , Dinamarca/epidemiologia , Feminino , Fluorescência , Humanos , Lactente , Cristalino/metabolismo , Masculino , Pessoa de Meia-Idade , Pele/metabolismo , Estudos em Gêmeos como Assunto , Gêmeos Monozigóticos/genética
5.
Invest Ophthalmol Vis Sci ; 62(12): 25, 2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-34554179

RESUMO

Purpose: The presence of a physical barrier to molecular diffusion through lenticular extracellular space has been repeatedly detected. This extracellular diffusion barrier has been proposed to restrict the movement of solutes into the lens and to direct nutrients into the lens core via the sutures at both poles. The purpose of this study is to characterize the molecular components that could contribute to the formation of this barrier. Methods: Three distinct regions in the bovine lens cortex were captured by laser capture microdissection guided by dye penetration. Proteins were digested by Lys C and trypsin. Mass spectrometry-based proteomic analysis followed by gene ontology and protein interaction network analysis was performed. Results: Dye penetration showed that fiber cells first shrink the extracellular spaces of the broad sides followed by closure of the extracellular space between narrow sides at a normalized lens distance (r/a) of 0.9. Accompanying the closure of extracellular space of the broad sides, dramatic proteomic changes were detected, including upregulation of several cell junctional proteins. AQP0 and its interacting partners, Ezrin and Radixin, were among a few proteins that were upregulated, accompanying the closure of extracellular space of the narrow sides, suggesting a particularly important role for AQP0 in controlling the narrowing of the extracellular spaces between fiber cells. The results also provided important information related to biological processes that occur during fiber cell differentiation such as organelle degradation, cytoskeletal remodeling, and glutathione synthesis. Conclusions: The formation of a lens extracellular diffusion barrier is accompanied by significant membrane and cytoskeletal protein remodeling.


Assuntos
Membrana Celular/metabolismo , Cristalinas/metabolismo , Espaço Extracelular/metabolismo , Cápsula do Cristalino/metabolismo , Cristalino/metabolismo , Animais , Aquaporinas/metabolismo , Transporte Biológico , Bovinos , Cromatografia Líquida , Proteínas do Citoesqueleto/metabolismo , Difusão , Proteínas do Olho/metabolismo , Proteínas de Membrana/metabolismo , Microscopia Confocal , Mapas de Interação de Proteínas , Proteômica , Espectrometria de Massas em Tandem , Xantenos/metabolismo
6.
Sci Rep ; 11(1): 17401, 2021 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-34465795

RESUMO

Cataracts, named for pathological light scattering in the lens, are known to be associated with increased large protein aggregates, disrupted protein phase separation, and/or osmotic imbalances in lens cells. We have applied synchrotron phase contrast X-ray micro-computed tomography to directly examine an age-related nuclear cataract model in Cx46 knockout (Cx46KO) mice. High-resolution 3D X-ray tomographic images reveal amorphous spots and strip-like dense matter precipitates in lens cores of all examined Cx46KO mice at different ages. The precipitates are predominantly accumulated in the anterior suture regions of lens cores, and they become longer and dense as mice age. Alizarin red staining data confirms the presence of calcium precipitates in lens cores of all Cx46KO mice. This study indicates that the spatial and temporal calcium precipitation is an age-related event associated with age-related nuclear cataract formation in Cx46KO mice, and further suggests that the loss of Cx46 promotes calcium precipitates in the lens core, which is a new mechanism that likely contributes to the pathological light scattering in this age-related cataract model.


Assuntos
Cálcio/metabolismo , Catarata/metabolismo , Animais , Catarata/patologia , Cristalino/metabolismo , Camundongos , Camundongos Knockout , Microtomografia por Raio-X
7.
Biomolecules ; 11(8)2021 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-34439816

RESUMO

Cataracts are a leading cause of blindness worldwide. Surgical removal of cataracts is a safe and effective procedure to restore vision. However, a large number of patients later develop vision loss due to regrowth of lens cells and subsequent degradation of the visual axis leading to visual disability. This postsurgical complication, known as posterior capsular opacification (PCO), occurs in up to 30% of cataract patients and has no clinically proven pharmacological means of prevention. Despite the availability of many compounds capable of preventing early steps in PCO development, there is currently no effective means to deliver such therapies into the eye for a suitable duration. To model a solution to this unmet medical need, we fabricated acrylic substrates as intraocular lens (IOL) mimics scaled to place into the capsular bag of the mouse lens following a mock-cataract surgery. Substrates were coated with a hydrophilic crosslinked acrylate nanogel designed to elute Sorbinil, an aldose reductase inhibitor previously shown to suppress PCO. Insertion of the Sorbinil-eluting device into the lens capsule at the time of cataract surgery resulted in substantial prevention of cellular changes associated with PCO development. This model demonstrates that a cataract inhibitor can be delivered into the postsurgical lens capsule at therapeutic levels.


Assuntos
Opacificação da Cápsula/prevenção & controle , Extração de Catarata/efeitos adversos , Portadores de Fármacos , Inibidores Enzimáticos/farmacologia , Imidazolidinas/farmacologia , Lentes Intraoculares , Actinas/genética , Actinas/metabolismo , Animais , Caderinas/genética , Caderinas/metabolismo , Opacificação da Cápsula/etiologia , Opacificação da Cápsula/genética , Opacificação da Cápsula/patologia , Catarata/genética , Catarata/metabolismo , Catarata/patologia , Extração de Catarata/métodos , Modelos Animais de Doenças , Fibronectinas/genética , Fibronectinas/metabolismo , Regulação da Expressão Gênica , Humanos , Cristalino/metabolismo , Cristalino/patologia , Cristalino/cirurgia , Camundongos , Nanogéis/administração & dosagem , Nanogéis/química , Transdução de Sinais , Vimentina/genética , Vimentina/metabolismo
8.
Exp Eye Res ; 210: 108709, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34339681

RESUMO

Lens homeostasis and transparency are dependent on the function and intercellular communication of its epithelia. While the lens epithelium is uniquely equipped with functional repair systems to withstand reactive oxygen species (ROS)-mediated oxidative insult, ROS are not necessarily detrimental to lens cells. Lens aging, and the onset of pathogenesis leading to cataract share an underlying theme; a progressive breakdown of oxidative stress repair systems driving a pro-oxidant shift in the intracellular environment, with cumulative ROS-induced damage to lens cell biomolecules leading to cellular dysfunction and pathology. Here we provide an overview of our current understanding of the sources and essential functions of lens ROS, antioxidative defenses, and changes in the major regulatory systems that serve to maintain the finely tuned balance of oxidative signaling vs. oxidative stress in lens cells. Age-related breakdown of these redox homeostasis systems in the lens leads to the onset of cataractogenesis. We propose eight candidate hallmarks that represent common denominators of aging and cataractogenesis in the mammalian lens: oxidative stress, altered cell signaling, loss of proteostasis, mitochondrial dysfunction, dysregulated ion homeostasis, cell senescence, genomic instability and intrinsic apoptotic cell death.


Assuntos
Envelhecimento/fisiologia , Biomarcadores/metabolismo , Catarata/metabolismo , Cristalino/metabolismo , Animais , Apoptose , Senescência Celular , Homeostase , Humanos , Oxirredução , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo
9.
Exp Eye Res ; 211: 108707, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34332989

RESUMO

The nuclear region of the lens is metabolically quiescent, but it is far from inert chemically. Without cellular renewal and with decades of environmental exposures, the lens proteome, lipidome, and metabolome change. The lens crystallins have evolved exquisite mechanisms for resisting, slowing, adapting to, and perhaps even harnessing the effects of these cumulative chemical modifications to minimize the amount of light-scattering aggregation in the lens over a lifetime. Redox chemistry is a major factor in these damages and mitigating adaptations, and as such, it is likely to be a key component of any successful therapeutic strategy for preserving or rescuing lens transparency, and perhaps flexibility, during aging. Protein redox chemistry is typically mediated by Cys residues. This review will therefore focus primarily on the Cys-rich γ-crystallins of the human lens, taking care to extend these findings to the ß- and α-crystallins where pertinent.


Assuntos
Cisteína/metabolismo , Cristalino/metabolismo , gama-Cristalinas/metabolismo , Envelhecimento/fisiologia , Dissulfetos/metabolismo , Glutationa/metabolismo , Dissulfeto de Glutationa/metabolismo , Humanos , Oxirredução , Compostos de Sulfidrila/metabolismo
10.
Exp Eye Res ; 211: 108721, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34375588

RESUMO

Senile cataract is a common age-related disease in ophthalmology. Hsa_circ_0004058 has been reported to be down-regulated in the lens epithelial cells of senile cataract patients, suggesting that hsa_circ_0004058 is associated with senile cataract. However, the underlying mechanism is still unknown. This study attempted to determine the functional role of hsa_circ_0004058 in senile cataract. We treated human lens epithelial cells (SRA01/04) with H2O2 as senile cataract model, and found that cell viability and autophagy of SRA01/04 cells were severely decreased by H2O2 treatment. Hsa_circ_0004058 was notably down-regulated in H2O2-treated SRA01/04 cells. Moreover, hsa_circ_0004058 overexpression reduced apoptotic cells and the expression of Cleaved-caspase-3 and Bax, and enhanced Bcl-2 expression in H2O2-treated SRA01/04 cells. However, hsa_circ_0004058 silencing caused the opposite results. Hsa_circ_0004058 up-regulation accelerated the expression of autophagy-related proteins LC3-II/LC3-I and Beclin-1 in H2O2-treated SRA01/04 cells, which was partly abolished by 3-Methyladenine (autophagy inhibitor). Additionally, hsa_circ_0004058 functioned as a competing endogenous RNA to competitive binding miR-186, and thus accelerated the expression of its down-stream target, ATG7. Hsa_circ_0004058 promoted autophagy of SRA01/04 cells by regulating miR-186/ATG7 axis. In conclusion, these data demonstrates that hsa_circ_0004058 inhibits apoptosis of SRA01/04 cells by promoting autophagy, which attributes to regulate miR-186/ATG7 axis. Thus, hsa_circ_0004058 may be a potential target for senile cataract treatment.


Assuntos
Apoptose/genética , Proteína 7 Relacionada à Autofagia/genética , Autofagia/fisiologia , Células Epiteliais/efeitos dos fármacos , Cristalino/patologia , MicroRNAs/genética , RNA Circular/fisiologia , Western Blotting , Caspase 3/genética , Sobrevivência Celular , Células Cultivadas , Eletroforese em Gel de Poliacrilamida , Células Epiteliais/metabolismo , Regulação da Expressão Gênica/fisiologia , Humanos , Peróxido de Hidrogênio/toxicidade , Cristalino/metabolismo , Proteínas Associadas aos Microtúbulos/genética , Oxidantes/toxicidade , Proteínas Proto-Oncogênicas c-bcl-2/genética , Reação em Cadeia da Polimerase em Tempo Real , Transfecção
11.
Dev Biol ; 479: 126-138, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34343526

RESUMO

The arthropod compound eye represents one of two major eye types in the animal kingdom and has served as an essential experimental paradigm for defining fundamental mechanisms underlying sensory organ formation, function, and maintenance. One of the most distinguishing features of the compound eye is the highly regular array of lens facets that define individual eye (ommatidial) units. These lens facets are produced by a deeply conserved quartet of cuticle-secreting cells, called Semper cells (SCs). Also widely known as cone cells, SCs were originally identified for their secretion of the dioptric system, i.e. the corneal lens and underlying crystalline cones. Additionally, SCs are now known to execute a diversity of patterning and glial functions in compound eye development and maintenance. Here, we present an integrated account of our current knowledge of SC multifunctionality in the Drosophila compound eye, highlighting emerging gene regulatory modules that may drive the diverse roles for these cells. Drawing comparisons with other deeply conserved retinal glia in the vertebrate single lens eye, this discussion speaks to glial cell origins and opens new avenues for understanding sensory system support programs.


Assuntos
Olho Composto de Artrópodes/fisiologia , Células Fotorreceptoras de Invertebrados/fisiologia , Células Fotorreceptoras Retinianas Cones/fisiologia , Animais , Olho Composto de Artrópodes/metabolismo , Córnea/metabolismo , Córnea/fisiologia , Drosophila/genética , Proteínas de Drosophila/genética , Olho/metabolismo , Proteínas do Olho/genética , Cristalino/metabolismo , Cristalino/fisiologia , Neuroglia/fisiologia , Células Fotorreceptoras de Invertebrados/metabolismo , Células Fotorreceptoras Retinianas Cones/metabolismo , Relação Estrutura-Atividade
12.
Cells ; 10(8)2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34440774

RESUMO

Aquaporin 0 (AQP0) is the most abundant lens membrane protein, and loss of function in human and animal models leads to cataract formation. AQP0 has several functions in the lens including water transport and adhesion. Since lens optics rely on strict tissue architecture achieved by compact cell-to-cell adhesion between lens fiber cells, understanding how AQP0 contributes to adhesion would shed light on normal lens physiology and pathophysiology. We show in an in vitro adhesion assay that one of two closely related zebrafish Aqp0s, Aqp0b, has strong auto-adhesive properties while Aqp0a does not. The difference appears to be largely due to a single amino acid difference at residue 110 in the extracellular C-loop, which is T in Aqp0a and N in Aqp0b. Similarly, P110 is the key residue required for adhesion in mammalian AQP0, highlighting the importance of residue 110 in AQP0 cell-to-cell adhesion in vertebrate lenses as well as the divergence of adhesive and water permeability functions in zebrafish duplicates.


Assuntos
Aquaporinas/metabolismo , Adesão Celular , Proteínas do Olho/metabolismo , Fibroblastos/metabolismo , Cristalino/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Sequência de Aminoácidos , Animais , Aquaporinas/genética , Linhagem Celular , Proteínas do Olho/genética , Camundongos , Mutação , Permeabilidade , Relação Estrutura-Atividade , Proteínas de Peixe-Zebra/genética
13.
Exp Eye Res ; 210: 108705, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34297945

RESUMO

Crystallins, the most prevalent lens proteins, have no turnover throughout the entire human lifespan. These long-lived proteins are susceptible to post-synthetic modifications, including oxidation and glycation, which are believed to be some of the primary mechanisms for age-related cataractogenesis. Thanks to high glutathione (GSH) and ascorbic acid (ASA) levels as well as low oxygen content, the human lens is able to maintain its transparency for several decades. Aging accumulates substantial changes in the human lens, including a decreased glutathione concentration, increased reactive oxygen species (ROS) formation, impaired antioxidative defense capacity, and increased redox-active metal ions, which induce glucose and ascorbic acid degradation and protein glycation. The glycated lens crystallins are either prone to UVA mediated free radical production or they attract metal ion binding, which can trigger additional protein oxidation and modification. This vicious cycle is expected to be exacerbated with older age or diabetic conditions. ASA serves as an antioxidant in the human lens under reducing conditions to protect the human lens from damage, but ASA converts to the pro-oxidative role and causes lens protein damage by ascorbylation in high oxidation or enriched redox-active metal ion conditions. This review is dedicated in honor of Dr. Frank Giblin, a great friend and superb scientist, whose pioneering and relentless work over the past 45 years has provided critical insight into lens redox regulation and glutathione homeostasis during aging and cataractogenesis.


Assuntos
Envelhecimento/fisiologia , Catarata/metabolismo , Glicosilação , Cristalino/metabolismo , Processamento de Proteína Pós-Traducional/fisiologia , Animais , Ácido Ascórbico/farmacologia , Catarata/fisiopatologia , Cristalinas/metabolismo , Glutationa/metabolismo , Humanos , Cristalino/efeitos dos fármacos , Oxirredução , Ligação Proteica , Espécies Reativas de Oxigênio/metabolismo
14.
Invest Ophthalmol Vis Sci ; 62(9): 33, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34293079

RESUMO

Purpose: To use magnetic resonance imaging (MRI) to measure age-dependent changes in total and free water in human lenses in vivo. Methods: Sixty-four healthy adults aged 18 to 86 years were recruited, fitted with a 32-channel head receiver coil, and placed in a 3 Tesla clinical MR scanner. Scans of the crystalline lens were obtained using a volumetric interpolated breath-hold examination sequence with dual flip angles, which were corrected for field inhomogeneity post-acquisition using a B1-map obtained using a turbo-FLASH sequence. The spatial distribution and content of corrected total (ρlens) and free (T1) water along the lens optical axis were extracted using custom-written code. Results: Lens total water distribution and content did not change with age (all P > 0.05). In contrast to total water, a gradient in free water content that was highest in the periphery relative to the center was present in lenses across all ages. However, this initially parabolic free water gradient gradually developed an enhanced central plateau, as indicated by increasing profile shape parameter values (anterior: 0.067/y, P = 0.004; posterior: 0.050/y, P = 0.020) and central free water content (1.932 ms/y, P = 0.022) with age. Conclusions: MRI can obtain repeatable total and free water measurements of in vivo human lenses. The observation that the lens steady-state free, but not total, water gradient is abolished with age raises the possibility that alterations in protein-water interactions are an underlying cause of the degradation in lens optics and overall vision observed with aging.


Assuntos
Envelhecimento/metabolismo , Água Corporal/metabolismo , Cristalino/metabolismo , Imageamento por Ressonância Magnética/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/metabolismo , Feminino , Humanos , Cristalino/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Valores de Referência , Adulto Jovem
15.
Invest Ophthalmol Vis Sci ; 62(7): 23, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-34156426

RESUMO

Purpose: The purpose of this study was to determine the importance of the xCT is a subunit. The cystine/glutamate antiporter is actually system xc-xCT subunit of the cystine/glutamate antiporter in maintaining redox balance by investigating the effects of the loss of xCT on lens transparency and cystine/cysteine balance in the aqueous humour. Methods: C57Bl/6 wild-type and xCT knockout mice at five age groups (6 weeks to 12 months) were used. Lens transparency was examined using a slit-lamp and morphological changes visualized by immunolabelling and confocal microscopy. Quantification of glutathione in lenses and cysteine and cystine levels in the aqueous was conducted by liquid chromatography tandem mass spectrometry (LC-MS/MS). Results: Slit-lamp examinations revealed that 3-month-old wild-type mice and xCT knockout mice lenses exhibited an anterior localized cataract. The frequency of this cataract significantly increased in the knockout mice compared to the wild-type mice. Morphological studies revealed a localized swelling of the lens fiber cells at the anterior pole. Glutathione levels in whole lenses were similar between wild-type and knockout mice. However, glutathione levels were significantly decreased at 3 months in the knockout mice in the lens epithelium compared to the wild-type mice. Aqueous cysteine levels remained similar between wild-type and knockout mice at all age groups, whereas cystine levels were significantly increased in 3-, 9-, and 12-month-old knockout mice compared to wild-type mice. Conclusions: Loss of xCT resulted in the depletion of glutathione in the epithelium and an oxidative shift in the cysteine/cystine ratio of the aqueous. Together, these oxidative changes may contribute to the accelerated development of an anterior cataract in knockout mice, which appears to be a normal feature of aging in wild-type mice.


Assuntos
Envelhecimento/fisiologia , Humor Aquoso , Catarata , Cistina/metabolismo , Ácido Glutâmico/metabolismo , Cristalino , Animais , Antiporters/metabolismo , Humor Aquoso/diagnóstico por imagem , Humor Aquoso/fisiologia , Catarata/diagnóstico , Catarata/metabolismo , Catarata/fisiopatologia , Cristalino/diagnóstico por imagem , Cristalino/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Confocal/métodos , Oxirredução , Estresse Oxidativo , Microscopia com Lâmpada de Fenda/métodos
16.
Aging (Albany NY) ; 13(11): 15674-15687, 2021 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-34118792

RESUMO

Crystallins, the major constituent proteins of mammalian lenses, are significant not only for the maintenance of eye lens stability, transparency, and refraction, but also fulfill various physiopathological functions in extraocular tissues. ßB2-crystallin, for example, is a multifunctional protein expressed in the human retina, brain, testis, ovary, and multiple tumors. Mutations in the ßB2 crystallin gene or denaturation of ßB2-crystallin protein are associated with cataracts, ocular pathologies, and psychiatric disorders. A prominent role for ßB2-crystallins in axonal growth and regeneration, as well as in dendritic outgrowth, has been demonstrated after optic nerve injury. Studies in ßB2-crystallin-null mice revealed morphological and functional abnormalities in testis and ovaries, indicating ßB2-crystallin contributes to male and female fertility in mice. Interestingly, although pathogenic significance remains obscure, several studies identified a clear correlation between ßB2 crystallin expression and the prognosis of patients with breast cancer, colorectal cancer, prostate cancer, renal cell carcinoma, and glioblastoma in the African American population. This review summarizes the physiological and pathological functions of ßB2-crystallin in the eye and other organs and tissues and discusses findings related to the expression and potential role of ßB2-crystallin in tumors.


Assuntos
Especificidade de Órgãos , Cadeia B de beta-Cristalina/fisiologia , Afro-Americanos , Humanos , Cristalino/metabolismo , Neoplasias/metabolismo
17.
Biochem J ; 478(12): 2285-2296, 2021 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-34143864

RESUMO

Transforming growth factor-ß2 (TGFß2)-mediated epithelial to mesenchymal transition (EMT) in lens epithelial cells (LECs) has been implicated in fibrosis associated with secondary cataracts. In this study, we investigated whether the receptor for advanced glycation end products (RAGE) plays a role in TGFß2-mediated EMT in LECs. Unlike in the LECs from wild-type mice, TGFß2 failed to elicit an EMT response in LECs from RAGE knockout mice. The lack of RAGE also diminished TGFß2-mediated Smad signaling. In addition, treatment with TGFß2 increased IL-6 levels in LECs from wild-type mice but not in those from RAGE knockout mice. Treatment of human LECs with the RAGE inhibitor FPS-ZM1 reduced TGFß2-mediated Smad signaling and the EMT response. Unlike that in wild-type lenses, the removal of fiber cell tissue in RAGE knockout lenses did not result in elevated levels of α-smooth muscle actin (α-SMA), fibronectin (FN), and integrin ß1 in capsule-adherent LECs. Taken together, these results suggest that TGFß2 signaling is intricately linked to RAGE. Targeting RAGE could be explored as a therapeutic strategy against secondary cataracts.


Assuntos
Células Epiteliais/patologia , Transição Epitelial-Mesenquimal , Cristalino/patologia , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Fator de Crescimento Transformador beta2/metabolismo , Animais , Células Epiteliais/metabolismo , Fibronectinas/genética , Fibronectinas/metabolismo , Humanos , Cristalino/metabolismo , Cristalino/cirurgia , Camundongos , Receptor para Produtos Finais de Glicação Avançada/genética , Transdução de Sinais , Fator de Crescimento Transformador beta2/genética
19.
Biomed Res Int ; 2021: 6668845, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34055996

RESUMO

Purpose: To investigate and compare the lens phosphoproteomes in patients with highly myopic cataract (HMC) or age-related cataract (ARC). Methods: In this study, we undertook a comparative phosphoproteome analysis of the lenses from patients with HMC or ARC. Intact lenses from ARC and HMC patients were separated into the cortex and nucleus. After protein digestion, the phosphopeptides were quantitatively analyzed with TiO2 enrichment and liquid chromatography-mass spectrometry. The potential functions of different phosphopeptides were assessed by Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Results: In total, 522 phosphorylation sites in 164 phosphoproteins were identified. The number of phosphorylation sites was significantly higher in the cortex than in the nucleus, in both ARC and HMC lenses. The differentially phosphorylated peptides in the lens cortex and nucleus in HMC eyes were significantly involved in the glutathione metabolism pathway. The KEGG pathway enrichment analysis indicated that the differences in phosphosignaling mediators between the ARC and HMC lenses were associated with glycolysis and the level of phosphorylated phosphoglycerate kinase 1 was lower in HMC lenses than in ARC lenses. Conclusions: We provide an overview of the differential phosphoproteomes of HMC and ARC lenses that can be used to clarify the molecular mechanisms underlying their different phenotypes.


Assuntos
Catarata/diagnóstico , Catarata/genética , Cristalinas/metabolismo , Miopia/complicações , Fosfoproteínas/metabolismo , Cromatografia Líquida , Genoma , Humanos , Cristalino/metabolismo , Espectrometria de Massas , Fosfopeptídeos , Fosforilação , Proteoma/metabolismo
20.
Prog Mol Subcell Biol ; 59: 1-11, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34050859

RESUMO

Calreticulin is well known as an ER-resident protein that serves as the major endoplasmic reticulum (ER) Ca2+ binding protein. This protein has been the major topic of discussion in an international workshop that has been meeting for a quarter of a century. In sharing information about this protein, the field also witnessed remarkable insights into the importance of the ER as an organelle and the role of ER Ca2+ in coordinating ER and cellular functions. Recent technological advances have helped to uncover the contributions of calreticulin in maintaining Ca2+ homeostasis in the ER and to unravel its involvement in a multitude of cellular processes as highlighted in this collection of articles. The continuing revelations of unexpected involvement of calreticulin and Ca2+ in many critical aspects of cellular function promises to further improve insights into the significance of this protein in the promotion of physiology as well as prevention of pathology.


Assuntos
Calreticulina , Retículo Endoplasmático , Calreticulina/genética , Calreticulina/metabolismo , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Homeostase , Cristalino/metabolismo
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