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Hashimi M, Amin HA, Zagkos L, Day AC, Drenos F. Using genetics to investigate the association between lanosterol and cataract. Front Genet 2024; 15:1231521. [PMID: 38440190 PMCID: PMC10910428 DOI: 10.3389/fgene.2024.1231521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 02/06/2024] [Indexed: 03/06/2024] Open
Abstract
Background: Cataract is one of the most prevalent causes of blindness worldwide. Whilst surgery is the primary treatment for cataracts, it is not always an available option, particularly in developing countries. Non-surgical methods of treatment would increase treatment availability for more patients. Several studies have investigated how topical application of oxysterols, such as lanosterol, may break down aggregated proteins and restore lens transparency. However, the results are conflicting and inconclusive. Aim: In this study, we focus on combining genetic evidence for associations between lanosterol related genetic variation and cataract to explore whether lanosterol is a potentially suitable drug treatment option. Method: Using data from 45,449 available cataract cases from the UK Biobank, with participant ages ranging from 40-69, we conducted a genetic association study (GWAS) to assess the risk of cataract. Cataract cases were defined using diagnostic and operation codes. We focused on genetic variants in the lanosterol synthase gene region. We also compared our results with previously published genetic associations of phytosterol-to-lanosterol ratios. Finally, we performed a genetic risk score analysis to test the association between lanosterol within the cholesterol synthesis pathway and the risk of cataract. Results: No statistically significant single nucleotide polymorphisms (SNPs) associations with cataract were observed in the gene region of lanosterol synthase at a multiple testing adjusted significance threshold of p < 0.05/13. The comparison between cataract risk and genetic association of 8 phytosterol-to-lanosterol GWAS results also showed no evidence to support lanosterol's protective properties for cataract risk. No statistically significant association was found between the lanosterol within the cholesterol synthesis pathway genetic risk score and cataract outcomes (OR = 1.002 p = 0.568). Conclusion: There was no evidence observed for genetic associations between lanosterol and cataract risk. Our results do not support lanosterol's potential role in treating cataracts. Further research may be needed to address the effect of lanosterol on specific cataract subtypes.
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Affiliation(s)
- Munisa Hashimi
- Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Hasnat A. Amin
- Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Loukas Zagkos
- Department of Epidemiology and Biostatistics, Imperial College London, London, United Kingdom
| | - Alexander C. Day
- Moorfields Eye Hospital, London, United Kingdom
- UCL Institute of Ophthalmology, London, United Kingdom
| | - Fotios Drenos
- Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge, United Kingdom
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Li Z, Quan Y, Gu S, Jiang JX. Beyond the Channels: Adhesion Functions of Aquaporin 0 and Connexin 50 in Lens Development. Front Cell Dev Biol 2022; 10:866980. [PMID: 35465319 PMCID: PMC9022433 DOI: 10.3389/fcell.2022.866980] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/18/2022] [Indexed: 12/04/2022] Open
Abstract
Lens, an avascular tissue involved in light transmission, generates an internal microcirculatory system to promote ion and fluid circulation, thus providing nutrients to internal lens cells and excreting the waste. This unique system makes up for the lack of vasculature and distinctively maintains lens homeostasis and lens fiber cell survival through channels of connexins and other transporters. Aquaporins (AQP) and connexins (Cx) comprise the majority of channels in the lens microcirculation system and are, thus, essential for lens development and transparency. Mutations of AQPs and Cxs result in abnormal channel function and cataract formation. Interestingly, in the last decade or so, increasing evidence has emerged suggesting that in addition to their well-established channel functions, AQP0 and Cx50 play pivotal roles through channel-independent actions in lens development and transparency. Specifically, AQP0 and Cx50 have been shown to have a unique cell adhesion function that mediates lens development and transparency. Precise regulation of cell-matrix and cell-cell adhesion is necessary for cell migration, a critical process during lens development. This review will provide recent advances in basic research of cell adhesion mediated by AQP0 and Cx50.
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Affiliation(s)
- Zhen Li
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yumeng Quan
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
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Abstract
Cataracts, the leading cause of vision impairment worldwide, arise from abnormal aggregation of lens proteins. According to the World Health Organization, cataracts cause more than 40% of blindness cases. As the population ages, the prevalence of cataracts will increase rapidly. Although cataract surgery is regarded as effective, it still suffers from complications and high cost, and could not meet the increasingly surgery demand. Therefore, pharmacological treatment for cataracts is a cheaper and more readily available option for patients, which is also a hot topic for years. Anti-cataract drug screening was previously mainly based on the specific pathogenic factors: oxidative stress, excess of quinoid substances, and aldose reductase (AR) activation. And several anti-cataract drugs have been applied in the clinic, while the effect is still unsatisfied. Makley and Zhao recently identified two kinds of novel pharmacological substances (25-hydroxycholesterol, lanosterol) that can reverse lens opacity by dissolving the aggregation of crystallin proteins, indicating that protein aggregation is not an endpoint and could be reversed with specific small-molecule drugs, significantly boosting the development of the cataract pharmacopeia and being regarded as a new dawn for cataract treatment. Our team built a novel optimized platform and had screened several potential therapeutic agents from a collection of lanosterol derivatives. In this review, we would mainly focus on the advancement of cataract pharmacotherapy based on the targets for anti-cataract drugs.
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Affiliation(s)
- Jingjie Xu
- Eye Center of the Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, China
| | - Qiuli Fu
- Eye Center of the Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, China
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Ke Yao
- Eye Center of the Second Affiliated Hospital, Medical College of Zhejiang University, Hangzhou, China
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Heruye SH, Maffofou Nkenyi LN, Singh NU, Yalzadeh D, Ngele KK, Njie-Mbye YF, Ohia SE, Opere CA. Current Trends in the Pharmacotherapy of Cataracts. Pharmaceuticals (Basel) 2020; 13:E15. [PMID: 31963166 PMCID: PMC7168925 DOI: 10.3390/ph13010015] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 12/23/2022] Open
Abstract
Cataracts, one of the leading causes of preventable blindness worldwide, refers to lens degradation that is characterized by clouding, with consequent blurry vision. As life expectancies improve, the number of people affected with cataracts is predicted to increase worldwide, especially in low-income nations with limited access to surgery. Although cataract surgery is considered safe, it is associated with some complications such as retinal detachment, warranting a search for cheap, pharmacological alternatives to the management of this ocular disease. The lens is richly endowed with a complex system of non-enzymatic and enzymatic antioxidants which scavenge reactive oxygen species to preserve lens proteins. Depletion and/or failure in this primary antioxidant defense system contributes to the damage observed in lenticular molecules and their repair mechanisms, ultimately causing cataracts. Several attempts have been made to counteract experimentally induced cataract using in vitro, ex vivo, and in vivo techniques. The majority of the anti-cataract compounds tested, including plant extracts and naturally-occurring compounds, lies in their antioxidant and/or free radical scavenging and/or anti-inflammatory propensity. In addition to providing an overview of the pathophysiology of cataracts, this review focuses on the role of various categories of natural and synthetic compounds on experimentally-induced cataracts.
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Affiliation(s)
- Segewkal H. Heruye
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
| | - Leonce N. Maffofou Nkenyi
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
| | - Neetu U. Singh
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
| | | | - Kalu K. Ngele
- Department of Biology/Microbiology/Biotechnology, Federal University Ndufu Alike Ikwo, Abakaliki, Nigeria
| | - Ya-Fatou Njie-Mbye
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX 77004, USA
| | - Sunny E. Ohia
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX 77004, USA
| | - Catherine A. Opere
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
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Varadaraj K, Gao J, Mathias RT, Kumari S. C-Terminal End of Aquaporin 0 Regulates Lens Gap Junction Channel Function. Invest Ophthalmol Vis Sci 2019; 60:2525-2531. [PMID: 31195409 PMCID: PMC6568327 DOI: 10.1167/iovs.19-26787] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/09/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose We reported previously that aquaporin 0 (AQP0) modulates lens fiber cell gap junction (GJ) channel function. The present study was conducted to find out whether the C-terminal end of AQP0 is involved in this regulation. Methods A mouse model, AQP0ΔC/ΔC, was genetically engineered to express AQP0 with 1-246 amino acids, without the normal intact AQP0 (1-263 amino acids) in the lens. Transparency and focusing of the lens were assessed. Intracellular impedance was measured to determine GJ coupling resistance. Intracellular hydrostatic pressure (HP) was also determined. Western blotting was performed to determine connexin (Cx46 and Cx50) expression levels. Results At postnatal day 10, AQP0ΔC/ΔC mouse lenses relative to age-matched wild-type lenses showed loss of transparency and abnormal optical distortion; GJ coupling resistance increased in the differentiating (1.6-fold) and mature (8-fold) fiber cells; lens HP increased approximately 1.5-fold at the junction between the differentiating and mature fiber cells and approximately 2.0-fold in the center; there was no significant change (P > 0.05) in expression levels of Cx46 or Cx50. Conclusions The increase in GJ coupling resistance was not associated with reduced connexin expression, suggesting either a reduction in the open probability or some physical change in plaque location. The increase in resistance was significantly greater than the increase in HP, suggesting less pressure-driven water flow through each open GJ channel. These changes may lead to a loss of transparency and abnormal optical distortion. Overall, our data demonstrate the C-terminal end of AQP0 is involved in modulating GJ coupling to maintain lens transparency and homeostasis.
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Affiliation(s)
- Kulandaiappan Varadaraj
- Physiology and Biophysics, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Junyuan Gao
- Physiology and Biophysics, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Richard T. Mathias
- Physiology and Biophysics, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Sindhu Kumari
- Physiology and Biophysics, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, United States
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Abstract
Visual impairment leads to a decrease in quality of life. Cataract is the most commonly
observed ocular disease in humans that causes vision disorders. The risk factors
associated with cataract development include aging, infections, eye injuries,
environmental causes, such as radiation and exposure to ultraviolet rays in sunlight, and
genetic mutations. Additionally, several cataract patients display phenotypic
heterogeneity, suggesting the role of genetic modifiers in the modulation of severity and
onset time of cataractogenesis. However, the genetic modifiers associated with cataract
have not been identified in humans yet. In contrast, the identification and mapping of
genetic modifiers have been successfully carried out in mice and rats. In this review, we
focus on the genetic modifiers of cataract in the rodent models.
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Affiliation(s)
- Kenta Wada
- Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido 099-2493, Japan.,Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Shumpei P Yasuda
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | - Yoshiaki Kikkawa
- Mammalian Genetics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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Abstract
Cataract is the most common cause of blindness and a major cause of visual impairment worldwide. As the world's population ages, cataract-induced visual impairment is of increasing prevalence, and treatment is limited to those with access to surgical care. While cataracts are mainly a disease of the elderly, infantile cataracts lead to lifelong visual impairment if untreated. Even in those with surgical treatment early in life, visual prognosis is often guarded. Consequently, there is an increasing impetus for alternative therapeutic modalities. Makley and Zhao utilize two different experimental approaches to identify novel pharmacological substances able to improve lens transparency by reducing aggregation of crystalline proteins. These data support an alternative to surgical correction that may be applied to adult patients without access to surgical care as well as address the unique challenges of infantile cataracts.
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Affiliation(s)
- Cassandra Skinner
- a University of Cincinnati College of Medicine , Cincinnati , Ohio , USA
| | - Virginia Miraldi Utz
- a University of Cincinnati College of Medicine , Cincinnati , Ohio , USA.,b Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center , Cincinnati , Ohio , USA.,c Department of Ophthalmology , University of Cincinnati , Cincinnati , Ohio , USA
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