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Glazier AN. Proposed Role for Internal Lens Pressure as an Initiator of Age-Related Lens Protein Aggregation Diseases. Clin Ophthalmol 2022; 16:2329-2340. [PMID: 35924184 PMCID: PMC9342656 DOI: 10.2147/opth.s369676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/13/2022] [Indexed: 11/23/2022] Open
Abstract
The process that initiates lens stiffness evident in age-related lens protein aggregation diseases is thought to be mainly the result of oxidation. While oxidation is a major contributor, the exposure of lens proteins to physical stress over time increases susceptibility of lens proteins to oxidative damage, and this is believed to play a significant role in initiating these diseases. Accordingly, an overview of key physical stressors and molecular factors known to be implicated in the development of age-related lens protein aggregation diseases is presented, paying particular attention to the consequence of persistent increase in internal lens pressure.
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Affiliation(s)
- Alan N Glazier
- Optometry, KeplrVision, Rockville, MD, USA
- Correspondence: Alan N Glazier, Email
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Rocha MA, Sprague-Piercy MA, Kwok AO, Roskamp KW, Martin RW. Chemical Properties Determine Solubility and Stability in βγ-Crystallins of the Eye Lens. Chembiochem 2021; 22:1329-1346. [PMID: 33569867 PMCID: PMC8052307 DOI: 10.1002/cbic.202000739] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/17/2020] [Indexed: 11/10/2022]
Abstract
βγ-Crystallins are the primary structural and refractive proteins found in the vertebrate eye lens. Because crystallins are not replaced after early eye development, their solubility and stability must be maintained for a lifetime, which is even more remarkable given the high protein concentration in the lens. Aggregation of crystallins caused by mutations or post-translational modifications can reduce crystallin protein stability and alter intermolecular interactions. Common post-translational modifications that can cause age-related cataracts include deamidation, oxidation, and tryptophan derivatization. Metal ion binding can also trigger reduced crystallin solubility through a variety of mechanisms. Interprotein interactions are critical to maintaining lens transparency: crystallins can undergo domain swapping, disulfide bonding, and liquid-liquid phase separation, all of which can cause opacity depending on the context. Important experimental techniques for assessing crystallin conformation in the absence of a high-resolution structure include dye-binding assays, circular dichroism, fluorescence, light scattering, and transition metal FRET.
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Affiliation(s)
- Megan A. Rocha
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Marc A. Sprague-Piercy
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
| | - Ashley O. Kwok
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Kyle W. Roskamp
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
| | - Rachel W. Martin
- Department of Chemistry, University of California, Irvine, 1102 Natural Sciences 2, Irvine, CA 92697-2025 (USA)
- Department of Molecular Biology and Biochemistry, University of California Irvine, 3205 McGaugh Hall, Irvine, CA 92697-2525
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Wang KJ, Liao XY, Lin K, Xi YB, Wang S, Wan XH, Yan YB. A novel F30S mutation in γS-crystallin causes autosomal dominant congenital nuclear cataract by increasing susceptibility to stresses. Int J Biol Macromol 2021; 172:475-482. [PMID: 33454329 DOI: 10.1016/j.ijbiomac.2021.01.079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/03/2021] [Accepted: 01/12/2021] [Indexed: 01/14/2023]
Abstract
Despite of increasingly accumulated genetic variations of autosomal dominant congenital cataracts (ADCC), the causative genes of many ADCC patients remains unknown. In this research, we identified a novel F30S mutation in γS-crystallin from a three-generation Chinese family with ADCC. The patients possessing the F30S mutation exhibited nuclear cataract phenotype. The potential molecular mechanism underlying ADCC by the F30S mutation was investigated by comparing the structural features, stability and aggregatory potency of the mutated protein with the wild type protein. Spectroscopic experiments indicated that the F30S mutation did not affect γS-crystallin secondary structure compositions, but modified the microenvironments around aromatic side-chains. Thermal and chemical denaturation studies indicated that the mutation destabilized the protein and increased its aggregatory potency. The mutation altered the two-state unfolding of γS-crystallin to a three-state unfolding with the accumulation of an unfolding intermediate. The almost identical values in the changes of Gibbs free energies for transitions from the native state to intermediate and from the intermediate to unfolded state suggested that the mutation probably disrupted the cooperativity between the two domains during unfolding. Our results expand the genetic variation map of ADCC and provide novel insights into the molecular mechanism underlying ADCC caused by mutations in β/γ-crystallins.
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Affiliation(s)
- Kai-Jie Wang
- Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China
| | - Xiao-Yan Liao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Kunxia Lin
- Ophthalmology Department, Fujian Provincial Hospital, Fuzhou, 350001, China
| | - Yi-Bo Xi
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Sha Wang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiu-Hua Wan
- Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China.
| | - Yong-Bin Yan
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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Bari KJ. The structural biology of crystallin aggregation: challenges and outlook. FEBS J 2021; 288:5888-5902. [DOI: 10.1111/febs.15684] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/11/2020] [Accepted: 12/21/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Khandekar Jishan Bari
- Center for Interdisciplinary Sciences Tata Institute of Fundamental Research Hyderabad India
- Department of Chemical Sciences Indian Institute of Science Education and Research Berhampur India
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Bari KJ, Sharma S. A Perspective on Biophysical Studies of Crystallin Aggregation and Implications for Cataract Formation. J Phys Chem B 2020; 124:11041-11054. [PMID: 33297682 DOI: 10.1021/acs.jpcb.0c07449] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Lens crystallins are subject to various types of damage during their lifetime which triggers protein misfolding and aggregation, ultimately causing cataracts. There are several models for crystallin aggregation, but a comprehensive picture of the mechanism of cataract is still underway. The complex biomolecular interactions underlying crystallin aggregation have motivated major efforts to resolve the structural details and mechanism of aggregation using multiple biophysical techniques at different resolutions. Together, experimental and computational approaches identify and characterize both amyloidogenic and amorphous aggregates leading to an improved understanding of crystallin aggregation. A rigorous characterization of the aggregation-prone intermediates is crucial in cataract-mediated drug discovery. This Perspective summarizes recent biophysical studies on lens crystallin aggregation. We evaluate the outstanding challenges, future outlook, and rewards in this fertile field of research. With lessons learned from protein folding and multiple pathways of aggregation, we highlight the differences in the overall mechanisms of age-related and congenital cataracts. We expect that a correlation between the existing and developing biophysical techniques would provide a platform to study amyloid architecture in the eye lens and reduce the existing gaps in our understanding of crystallin biophysics.
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Affiliation(s)
- Khandekar Jishan Bari
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Gopanpally, Hyderabad 500107, India.,Department of Chemical Sciences, Indian Institute of Science Education and Research, Berhampur, Odisha 760010, India
| | - Shrikant Sharma
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Gopanpally, Hyderabad 500107, India.,Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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Bari KJ, Dube D, Sharma S, Chary KVR. A Molecular Dynamics Perspective To Identify Precursors to Aggregation in Human γS-Crystallin Unravels the Mechanism of Childhood Cataracts. J Phys Chem B 2019; 123:10384-10393. [DOI: 10.1021/acs.jpcb.9b08195] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Khandekar Jishan Bari
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad, Telangana 500107, India
| | - Dheeraj Dube
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad, Telangana 500107, India
| | - Shrikant Sharma
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad, Telangana 500107, India
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Kandala V. R. Chary
- Indian Institute of Science Education and Research, Berhampur, Odisha 760010, India
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