1
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Lerebours A, Regini J, Quinlan RA, Wada T, Pierscionek B, Devonshire M, Kalligeraki AA, Uwineza A, Young L, Girkin JM, Warwick P, Smith K, Hoshino M, Uesugi K, Yagi N, Terrill N, Shebanova O, Snow T, Smith JT. Evaluation of cataract formation in fish exposed to environmental radiation at Chernobyl and Fukushima. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 902:165957. [PMID: 37543314 DOI: 10.1016/j.scitotenv.2023.165957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/05/2023] [Accepted: 07/30/2023] [Indexed: 08/07/2023]
Abstract
Recent studies apparently finding deleterious effects of radiation exposure on cataract formation in birds and voles living near Chernobyl represent a major challenge to current radiation protection regulations. This study conducted an integrated assessment of radiation exposure on cataractogenesis using the most advanced technologies available to assess the cataract status of lenses extracted from fish caught at both Chernobyl in Ukraine and Fukushima in Japan. It was hypothesised that these novel data would reveal positive correlations between radiation dose and early indicators of cataract formation. The structure, function and optical properties of lenses were analysed from atomic to millimetre length scales. We measured the short-range order of the lens crystallin proteins using Small Angle X-Ray Scattering (SAXS) at both the SPring-8 and DIAMOND synchrotrons, the profile of the graded refractive index generated by these proteins, the epithelial cell density and organisation and finally the focal length of each lens. The results showed no evidence of a difference between the focal length, the epithelial cell densities, the refractive indices, the interference functions and the short-range order of crystallin proteins (X-ray diffraction patterns) in lens from fish exposed to different radiation doses. It could be argued that animals in the natural environment which developed cataract would be more likely, for example, to suffer predation leading to survivor bias. But the cross-length scale study presented here, by evaluating small scale molecular and cellular changes in the lens (pre-cataract formation) significantly mitigates against this issue.
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Affiliation(s)
- Adélaïde Lerebours
- School of the Environment, Geography and Geosciences, University of Portsmouth, Portsmouth PO1 3QL, United Kingdom; School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Justyn Regini
- School of Optometry and Vision Sciences, University of Cardiff, Cardiff CA10 3AT, United Kingdom
| | - Roy A Quinlan
- Department of Biosciences, University of Durham, Upper Mountjoy, Stockton Road, Durham DH1 3LE, United Kingdom
| | - Toshihiro Wada
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima City, Japan
| | - Barbara Pierscionek
- Medical Technology Research Centre, Anglia Ruskin University, Bishop Hall Lane, Chelmsford CM1 1SQ, United Kingdom
| | - Martin Devonshire
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Alexia A Kalligeraki
- Department of Biosciences, University of Durham, Upper Mountjoy, Stockton Road, Durham DH1 3LE, United Kingdom
| | - Alice Uwineza
- Department of Biosciences, University of Durham, Upper Mountjoy, Stockton Road, Durham DH1 3LE, United Kingdom
| | - Laura Young
- Department of Biosciences, University of Durham, Upper Mountjoy, Stockton Road, Durham DH1 3LE, United Kingdom
| | - John M Girkin
- Department of Physics, University of Durham, South Road, Durham DH1 3LE, United Kingdom
| | - Phil Warwick
- GAU-Radioanalytical, University of Southampton, NOCS, European way, SO14 6HT Southampton,United Kingdom
| | - Kurt Smith
- Centre for Radiochemistry Research, School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Masato Hoshino
- Japan Synchrotron Radiation Research Institute (Spring-8), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Kentaro Uesugi
- Japan Synchrotron Radiation Research Institute (Spring-8), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Naoto Yagi
- Japan Synchrotron Radiation Research Institute (Spring-8), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Nick Terrill
- Diamond Light Source, Harwell Science & Innovation Campus, Didcot OX11 0DE, UK
| | - Olga Shebanova
- Diamond Light Source, Harwell Science & Innovation Campus, Didcot OX11 0DE, UK
| | - Tim Snow
- Diamond Light Source, Harwell Science & Innovation Campus, Didcot OX11 0DE, UK
| | - Jim T Smith
- School of the Environment, Geography and Geosciences, University of Portsmouth, Portsmouth PO1 3QL, United Kingdom.
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2
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Zhu M, Hu W, Lin L, Yang Q, Zhang L, Xu J, Xu Y, Liu J, Zhang M, Tong X, Zhu K, Feng K, Feng Y, Su J, Huang X, Li J. Single-cell RNA sequencing reveals new subtypes of lens superficial tissue in humans. Cell Prolif 2023; 56:e13477. [PMID: 37057399 PMCID: PMC10623935 DOI: 10.1111/cpr.13477] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/27/2023] [Accepted: 04/01/2023] [Indexed: 04/15/2023] Open
Abstract
Although the cell atlas of the human ocular anterior segment of the human eye was revealed by single-nucleus RNA sequencing, whether subtypes of lens stem/progenitor cells exist among epithelial cells and the molecular characteristics of cell differentiation of the human lens remain unclear. Single-cell RNA sequencing is a powerful tool to analyse the heterogeneity of tissues at the single cell level, leading to a better understanding of the processes of cell differentiation. By profiling 18,596 cells in human lens superficial tissue through single-cell sequencing, we identified two subtypes of lens epithelial cells that specifically expressed C8orf4 and ADAMTSL4 with distinct spatial localization, a new type of fibre cells located directly adjacent to the epithelium, and a subpopulation of ADAMTSL4+ cells that might be lens epithelial stem/progenitor cells. We also found two trajectories of lens epithelial cell differentiation and changes of some important genes during differentiation.
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Affiliation(s)
- Meng‐Chao Zhu
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Wei Hu
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, State Key Laboratory of Medical Neurobiology, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative MedicineFudan UniversityShanghaiChina
| | - Lei Lin
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Qing‐Wen Yang
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Lu Zhang
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Jia‐Lin Xu
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Yi‐Tong Xu
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Jia‐Sheng Liu
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Meng‐Di Zhang
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Xiao‐Yu Tong
- Zhejiang Provincial Clinical Research Center for Pediatric DiseaseThe Second Affiliated Hospital of Wenzhou Medical UniversityWenzhouZhejiangChina
| | - Kai‐Yi Zhu
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Ke Feng
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Yi Feng
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, Brain Science Collaborative Innovation Center, State Key Laboratory of Medical Neurobiology, Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative MedicineFudan UniversityShanghaiChina
| | - Jian‐Zhong Su
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
| | - Xiu‐Feng Huang
- Zhejiang Provincial Clinical Research Center for Pediatric DiseaseThe Second Affiliated Hospital of Wenzhou Medical UniversityWenzhouZhejiangChina
| | - Jin Li
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye HospitalWenzhou Medical UniversityWenzhouChina
- National Clinical Research Center for Ocular Diseases, Eye HospitalWenzhou Medical UniversityWenzhouChina
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3
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Ma DY, Liu JX, Wang LD, Zhi XY, Luo L, Zhao JY, Qin Y. GSK-3β-dependent Nrf2 antioxidant response modulates ferroptosis of lens epithelial cells in age-related cataract. Free Radic Biol Med 2023; 204:161-176. [PMID: 37156294 DOI: 10.1016/j.freeradbiomed.2023.04.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 04/05/2023] [Accepted: 04/29/2023] [Indexed: 05/10/2023]
Abstract
Oxidative stress-induced lens epithelial cells (LECs) death plays a pivotal role in age-related cataract (ARC) with severe visual impairment, in which ferroptosis is gradually receiving numerous attention resulting from lipid peroxide accumulation and reactive oxygen species (ROS) overproduction. However, the essential pathogenic factors and the targeted medical strategies still remain skeptical and indistinct. In this work, by transmission electron microscopy (TEM) analysis, the major pathological courses in the LECs of ARC patients have been identified as ferroptosis, which was manifested with remarkable mitochondrial alterations, and similar results were found in aged mice (24-month-old). Furthermore, the primary pathological processes in the NaIO3-induced mice and HLE-B3 cell model have also been verified to be ferroptosis with an irreplaceable function of Nrf2, proved by the increased sensitivity to ferroptosis when Nrf2 was blocked in Nrf2-KO mice and si-Nrf2-treated HLE-B3 cells. Importantly, it has been found that an increased expression of GSK-3β was indicated in low-Nrf2-expressed tissues and cells. Subsequently, the contributions of abnormal GSK-3β expression to NaIO3-induced mice and HLE-B3 cell model were further evaluated, inhibition of GSK-3β utilizing SB216763 significantly alleviated LECs ferroptosis with less iron accumulation and ROS generation, as well as reversed expression alterations of ferroptosis markers, including GPX4, SLC7A11, SLC40A1, FTH1 and TfR1, in vitro and in vivo. Collectively, our findings conclude that targeting GSK-3β/Nrf2 balance might be a promising therapeutic strategy to mitigate LECs ferroptosis and thus probably delay the pathogenesis and development of ARC.
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Affiliation(s)
- Dong-Yue Ma
- Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Eye Hospital of China Medical University, Key Lens Research Laboratory of Liaoning Province, Shenyang City, Liaoning Province, 110005, PR China
| | - Jin-Xia Liu
- Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Eye Hospital of China Medical University, Key Lens Research Laboratory of Liaoning Province, Shenyang City, Liaoning Province, 110005, PR China
| | - Lu-di Wang
- Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Eye Hospital of China Medical University, Key Lens Research Laboratory of Liaoning Province, Shenyang City, Liaoning Province, 110005, PR China
| | - Xin-Yu Zhi
- Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Eye Hospital of China Medical University, Key Lens Research Laboratory of Liaoning Province, Shenyang City, Liaoning Province, 110005, PR China
| | - Li Luo
- Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Eye Hospital of China Medical University, Key Lens Research Laboratory of Liaoning Province, Shenyang City, Liaoning Province, 110005, PR China
| | - Jiang-Yue Zhao
- Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Eye Hospital of China Medical University, Key Lens Research Laboratory of Liaoning Province, Shenyang City, Liaoning Province, 110005, PR China
| | - Yu Qin
- Department of Ophthalmology, The Fourth Affiliated Hospital of China Medical University, Eye Hospital of China Medical University, Key Lens Research Laboratory of Liaoning Province, Shenyang City, Liaoning Province, 110005, PR China.
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4
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Quinlan RA, Clark JI. Insights into the biochemical and biophysical mechanisms mediating the longevity of the transparent optics of the eye lens. J Biol Chem 2022; 298:102537. [PMID: 36174677 PMCID: PMC9638808 DOI: 10.1016/j.jbc.2022.102537] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/20/2022] [Accepted: 09/22/2022] [Indexed: 11/18/2022] Open
Abstract
In the human eye, a transparent cornea and lens combine to form the "refracton" to focus images on the retina. This requires the refracton to have a high refractive index "n," mediated largely by extracellular collagen fibrils in the corneal stroma and the highly concentrated crystallin proteins in the cytoplasm of the lens fiber cells. Transparency is a result of short-range order in the spatial arrangement of corneal collagen fibrils and lens crystallins, generated in part by post-translational modifications (PTMs). However, while corneal collagen is remodeled continuously and replaced, lens crystallins are very long-lived and are not replaced and so accumulate PTMs over a lifetime. Eventually, a tipping point is reached when protein aggregation results in increased light scatter, inevitably leading to the iconic protein condensation-based disease, age-related cataract (ARC). Cataracts account for 50% of vision impairment worldwide, affecting far more people than other well-known protein aggregation-based diseases. However, because accumulation of crystallin PTMs begins before birth and long before ARC presents, we postulate that the lens protein PTMs contribute to a "cataractogenic load" that not only increases with age but also has protective effects on optical function by stabilizing lens crystallins until a tipping point is reached. In this review, we highlight decades of experimental findings that support the potential for PTMs to be protective during normal development. We hypothesize that ARC is preventable by protecting the biochemical and biophysical properties of lens proteins needed to maintain transparency, refraction, and optical function.
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Affiliation(s)
- Roy A Quinlan
- Department of Biosciences, Durham University, South Road Science Site, Durham, United Kingdom; Department of Biological Structure, University of Washington, Seattle, Washington, USA.
| | - John I Clark
- Department of Biological Structure, University of Washington, Seattle, Washington, USA.
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5
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Parreno J, Emin G, Vu MP, Clark JT, Aryal S, Patel SD, Cheng C. Methodologies to unlock the molecular expression and cellular structure of ocular lens epithelial cells. Front Cell Dev Biol 2022; 10:983178. [PMID: 36176273 PMCID: PMC9514789 DOI: 10.3389/fcell.2022.983178] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 08/16/2022] [Indexed: 01/25/2023] Open
Abstract
The transparent ocular lens in the anterior chamber of the eye is responsible for fine focusing of light onto the retina. The lens is entirely cellular with bulk of the tissue composed of fiber cells, and the anterior hemisphere of the lens is covered by a monolayer of epithelial cells. Lens epithelial cells are important for maintaining fiber cell homeostasis and for continual growth of the lens tissue throughout life. Cataracts, defined as any opacity in the lens, remain the leading cause of blindness in the world. Following cataract surgery, lens epithelial cells can undergo a process of epithelial-to-mesenchymal transition (EMT), leading to secondary cataracts due to posterior capsular opacification (PCO). Since the epithelial cells make up only a small fraction of the lens, specialized techniques are required to study lens epithelial cell biology and pathology. Studies using native lens epithelial cells often require pooling of samples to obtain enough cells to make sufficient samples for traditional molecular biology techniques. Here, we provide detailed protocols that enable the study of native mouse lens epithelial cells, including immunostaining of the native lens epithelium in flat mounts, extraction of RNA and proteins from pairs of lens epithelial monolayers, and isolation of lens epithelial cells for primary culture. These protocols will enable researchers to gain better insight on representative molecular expression and cellular structure of lens epithelial cells. We also provide comparative data between native, primary culture, and immortalized lens epithelial cells and discuss the advantages and disadvantages of each technique presented.
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Affiliation(s)
- Justin Parreno
- Department of Biological Sciences, University of Delaware, Newark, DE, United States
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States
- *Correspondence: Justin Parreno, ; Catherine Cheng,
| | - Grace Emin
- Department of Biological Sciences, University of Delaware, Newark, DE, United States
| | - Michael P. Vu
- School of Optometry and Vision Science Program, Indiana University, Bloomington, IN, United States
| | - Jackson T. Clark
- School of Optometry and Vision Science Program, Indiana University, Bloomington, IN, United States
| | - Sandeep Aryal
- Department of Biological Sciences, University of Delaware, Newark, DE, United States
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Shaili D. Patel
- Department of Biological Sciences, University of Delaware, Newark, DE, United States
| | - Catherine Cheng
- School of Optometry and Vision Science Program, Indiana University, Bloomington, IN, United States
- *Correspondence: Justin Parreno, ; Catherine Cheng,
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6
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Zahraei A, Guo G, Varnava KG, Demarais NJ, Donaldson PJ, Grey AC. Mapping Glucose Uptake, Transport and Metabolism in the Bovine Lens Cortex. Front Physiol 2022; 13:901407. [PMID: 35711316 PMCID: PMC9194507 DOI: 10.3389/fphys.2022.901407] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022] Open
Abstract
Purpose: To spatially correlate the pattern of glucose uptake to glucose transporter distributions in cultured lenses and map glucose metabolism in different lens regions. Methods: Ex vivo bovine lenses were incubated in artificial aqueous humour containing normoglycaemic stable isotopically-labelled (SIL) glucose (5 mM) for 5 min-20 h. Following incubations, lenses were frozen for subsequent matrix-assisted laser desorption/ionisation (MALDI) imaging mass spectrometry (IMS) analysis using high resolution mass spectrometry. Manually dissected, SIL-incubated lenses were subjected to gas chromatography-mass spectrometry (GC-MS) to verify the identity of metabolites detected by MALDI-IMS. Normal, unincubated lenses were manually dissected into epithelium flat mounts and fibre cell fractions and then subjected to either gel-based proteomic analysis (Gel-LC/MS) to detect facilitative glucose transporters (GLUTs) by liquid chromatography tandem mass spectrometry (LC-MS/MS). Indirect immunofluorescence and confocal microscopy of axial lens sections from unincubated fixed lenses labelled with primary antibodies specific for GLUT 1 or GLUT 3 were utilised for protein localisation. Results: SIL glucose uptake at 5 min was concentrated in the equatorial region of the lens. At later timepoints, glucose gradually distributed throughout the epithelium and the cortical lens fibres, and eventually the deeper lens nucleus. SIL glucose metabolites found in glycolysis, the sorbitol pathway, the pentose phosphate pathway, and UDP-glucose formation were mapped to specific lens regions, with distinct regional signal changes up to 20 h of incubation. Spatial proteomic analysis of the lens epithelium detected GLUT1 and GLUT3. GLUT3 was in higher abundance than GLUT1 throughout the epithelium, while GLUT1 was more abundant in lens fibre cells. Immunohistochemical mapping localised GLUT1 to epithelial and cortical fibre cell membranes. Conclusion: The major uptake site of glucose in the bovine lens has been mapped to the lens equator. SIL glucose is rapidly metabolised in epithelial and fibre cells to many metabolites, which are most abundant in the metabolically more active cortical fibre cells in comparison to central fibres, with low levels of metabolic activity observed in the nucleus.
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Affiliation(s)
- Ali Zahraei
- Department of Physiology in the School of Medical Sciences, Auckland, New Zealand
| | - George Guo
- Department of Physiology in the School of Medical Sciences, Auckland, New Zealand.,Mass Spectrometry Hub, Auckland, New Zealand
| | - Kyriakos G Varnava
- Department of Physiology in the School of Medical Sciences, Auckland, New Zealand.,Mass Spectrometry Hub, Auckland, New Zealand
| | - Nicholas J Demarais
- Mass Spectrometry Hub, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J Donaldson
- Department of Physiology in the School of Medical Sciences, Auckland, New Zealand
| | - Angus C Grey
- Department of Physiology in the School of Medical Sciences, Auckland, New Zealand.,Mass Spectrometry Hub, Auckland, New Zealand
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7
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Autophagy facilitates age-related cell apoptosis-a new insight from senile cataract. Cell Death Dis 2022; 13:37. [PMID: 35013122 PMCID: PMC8748728 DOI: 10.1038/s41419-021-04489-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/23/2021] [Accepted: 12/14/2021] [Indexed: 12/15/2022]
Abstract
Age-related cell loss underpins many senescence-associated diseases. Apoptosis of lens epithelial cells (LECs) is the important cellular basis of senile cataract resulted from prolonged exposure to oxidative stress, although the specific mechanisms remain elusive. Our data indicated the concomitance of high autophagy activity, low SQSTM1/p62 protein level and apoptosis in the same LEC from senile cataract patients. Meanwhile, in primary cultured LECs model, more durable autophagy activation and more obvious p62 degradation under oxidative stress were observed in LECs from elder healthy donors, compared with that from young healthy donors. Using autophagy-deficiency HLE-B3 cell line, autophagy adaptor p62 was identified as the critical scaffold protein sustaining the pro-survival signaling PKCι-IKK-NF-κB cascades, which antagonized the pro-apoptotic signaling. Moreover, the pharmacological inhibitor of autophagy, 3-MA, significantly inhibited p62 degradation and rescued oxidative stress-induced apoptosis in elder LECs. Collectively, this study demonstrated that durable activation of autophagy promoted age-related cell death in LECs. Our work contributes to better understanding the pathogenesis of senescence-associated diseases.
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8
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Barnard S, Uwineza A, Kalligeraki A, McCarron R, Kruse F, Ainsbury EA, Quinlan RA. Lens Epithelial Cell Proliferation in Response to Ionizing Radiation. Radiat Res 2022; 197:92-99. [PMID: 33984857 DOI: 10.1667/rade-20-00294.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 04/20/2021] [Indexed: 11/03/2022]
Abstract
Lens epithelial cell proliferation and differentiation are naturally well regulated and controlled, a characteristic essential for lens structure, symmetry and function. The effect of ionizing radiation on lens epithelial cell proliferation has been demonstrated in previous studies at high acute doses, but the effect of dose and dose rate on proliferation has not yet been considered. In this work, mice received single acute doses of 0.5, 1 and 2 Gy of radiation, at dose rates of 0.063 and 0.3 Gy/min. Eye lenses were isolated postirradiation at 30 min up until 14 days and flat-mounted. Then, cell proliferation rates were determined using biomarker Ki67. As expected, radiation increased cell proliferation 2 and 24 h postirradiation transiently (undetectable 14 days postirradiation) and was dose dependent (changes were very significant at 2 Gy; P = 0.008). A dose-rate effect did not reach significance in this study (P = 0.054). However, dose rate and lens epithelial cell region showed significant interactions (P < 0.001). These observations further our mechanistic understanding of how the lens responds to radiation.
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Affiliation(s)
- S Barnard
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
- Department of Biosciences, University of Durham, Mountjoy Science Site, Durham DH13LE, United Kingdom
| | - A Uwineza
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
- Department of Biosciences, University of Durham, Mountjoy Science Site, Durham DH13LE, United Kingdom
| | - A Kalligeraki
- Department of Biosciences, University of Durham, Mountjoy Science Site, Durham DH13LE, United Kingdom
| | - R McCarron
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - F Kruse
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - E A Ainsbury
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - R A Quinlan
- Department of Biosciences, University of Durham, Mountjoy Science Site, Durham DH13LE, United Kingdom
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9
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Sugiyama Y, Nakazawa Y, Sakagami T, Kawata S, Nagai N, Yamamoto N, Funakoshi-Tago M, Tamura H. Capsaicin attenuates TGFβ2-induced epithelial-mesenchymal-transition in lens epithelial cells in vivo and in vitro. Exp Eye Res 2021; 213:108840. [PMID: 34798144 DOI: 10.1016/j.exer.2021.108840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 11/04/2021] [Accepted: 11/09/2021] [Indexed: 01/09/2023]
Abstract
Posterior capsule opacification (PCO), the most common complication of cataract surgery occurring in 20-50% of patients after 2-5 years of cataract surgery, is a major problem in the aging society. The epithelial-mesenchymal transition (EMT) of lens epithelial cells after cataract surgery has been proposed as a major cause of PCO. Capsaicin, widely used as a food additive and analgesic agent, is a major pungent ingredient in red pepper. Although the effect of capsaicin on EMT has been reported in cancer cells, the biological reaction of capsaicin was unique in each cell type, and there have been no reports describing its effects on EMT earlier. In this study, we demonstrated that treatment with capsaicin inhibited TGFβ2-induced EMT in vitro lens epithelial cells and ex vivo explant lens epithelial cells. Furthermore, eye drops of capsaicin inhibited the PCO model mice in vivo. Finally, we showed that capsaicin inhibited non-canonically induced Smad2/3 activation via suppression of EGFR activation and ERK phosphorylation. Our findings indicate that capsaicin and its derivatives are good candidate compounds for preventing PCO after cataract surgery.
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Affiliation(s)
| | | | | | - Sara Kawata
- Faculty of Pharmacy, Keio University, Tokyo, Japan
| | - Noriaki Nagai
- Faculty of Pharmacy, Kindai University, Osaka, Japan
| | - Naoki Yamamoto
- Research Promotion and Support Headquarters, Fujita Health University, Japan
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10
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Wu W, Lois N, Prescott AR, Brown AP, Van Gerwen V, Tassignon MJ, Richards SA, Saunter CD, Jarrin M, Quinlan RA. The importance of the epithelial fibre cell interface to lens regeneration in an in vivo rat model and in a human bag-in-the-lens (BiL) sample. Exp Eye Res 2021; 213:108808. [PMID: 34762932 DOI: 10.1016/j.exer.2021.108808] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 12/13/2022]
Abstract
Human lens regeneration and the Bag-in-the-Lens (BIL) surgical treatment for cataract both depend upon lens capsule closure for their success. Our studies suggest that the first three days after surgery are critical to their long-term outcomes. Using a rat model of lens regeneration, we evidenced lens epithelial cell (LEC) proliferation increased some 50 fold in the first day before rapidly declining to rates observed in the germinative zone of the contra-lateral, un-operated lens. Cell multi-layering at the lens equator occurred on days 1 and 2, but then reorganised into two discrete layers by day 3. E- and N-cadherin expression preceded cell polarity being re-established during the first week. Aquaporin 0 (AQP0) was first detected in the elongated cells at the lens equator at day 7. Cells at the capsulotomy site, however, behaved very differently expressing the epithelial mesenchymal transition (EMT) markers fibronectin and alpha-smooth muscle actin (SMA) from day 3 onwards. The physical interaction between the apical surfaces of the anterior and posterior LECs from day 3 after surgery preceded cell elongation. In the human BIL sample fibre cell formation was confirmed by both histological and proteome analyses, but the cellular response is less ordered and variable culminating in Soemmerring's ring (SR) formation and sometimes Elschnig's pearls. This we evidence for lenses from a single patient. No bow region or recognisable epithelial-fibre cell interface (EFI) was evident and consequently the fibre cells were disorganised. We conclude that lens cells require spatial and cellular cues to initiate, sustain and produce an optically functional tissue in addition to capsule integrity and the EFI.
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Affiliation(s)
- Weiju Wu
- Department of Biosciences, South Road, Durham University, Durham, DH1 3LE, England, UK
| | - Noemi Lois
- Wellcome-Wolfson Institute for Experimental Medicine, Queens University Belfast, 97 Lisburn Rd, Belfast, BT9 7BL, Northern Ireland, UK.
| | - Alan R Prescott
- Dundee Imaging Facility & Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK
| | - Adrian P Brown
- Department of Biosciences, South Road, Durham University, Durham, DH1 3LE, England, UK
| | - Veerle Van Gerwen
- Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Marie-José Tassignon
- Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium
| | - Shane A Richards
- School of Natural Sciences, University of Tasmania, Hobart TAS, Australia
| | | | - Miguel Jarrin
- Department of Biosciences, South Road, Durham University, Durham, DH1 3LE, England, UK
| | - Roy A Quinlan
- Department of Biosciences, South Road, Durham University, Durham, DH1 3LE, England, UK.
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11
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Three-dimensional data capture and analysis of intact eye lenses evidences emmetropia-associated changes in epithelial cell organization. Sci Rep 2020; 10:16898. [PMID: 33037268 PMCID: PMC7547080 DOI: 10.1038/s41598-020-73625-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/17/2020] [Indexed: 01/16/2023] Open
Abstract
Organ and tissue development are highly coordinated processes; lens growth and functional integration into the eye (emmetropia) is a robust example. An epithelial monolayer covers the anterior hemisphere of the lens, and its organization is the key to lens formation and its optical properties throughout all life stages. To better understand how the epithelium supports lens function, we have developed a novel whole tissue imaging system using conventional confocal light microscopy and a specialized analysis software to produce three-dimensional maps for the epithelium of intact mouse lenses. The open source software package geometrically determines the anterior pole position, the equatorial diameter, and three-dimensional coordinates for each detected cell in the epithelium. The user-friendly cell maps, which retain global lens geometry, allow us to document age-dependent changes in the C57/BL6J mouse lens cell distribution characteristics. We evidence changes in epithelial cell density and distribution in C57/BL6J mice during the establishment of emmetropia between postnatal weeks 4-6. These epithelial changes accompany a previously unknown spheroid to lentoid shape transition of the lens as detected by our analyses. When combined with key findings from previous mouse genetic and cell biological studies, we suggest a cytoskeleton-based mechanism likely underpins these observations.
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12
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Kumar B, Chandler HL, Plageman T, Reilly MA. Lens Stretching Modulates Lens Epithelial Cell Proliferation via YAP Regulation. Invest Ophthalmol Vis Sci 2019; 60:3920-3929. [PMID: 31546253 PMCID: PMC7043215 DOI: 10.1167/iovs.19-26893] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 08/13/2019] [Indexed: 01/13/2023] Open
Abstract
Purpose The continuous growth of the lens throughout life may contribute to the onset of age-related conditions in the lens (i.e., presbyopia and cataract). Volumetric growth is the result of continuous proliferation of lens epithelial cells (LECs). The driving factors controlling LEC proliferation are not well understood. This study tested the hypothesis that mechanical stretching modulates LEC proliferation. Methods Biomechanical regulation of LEC proliferation was investigated by culturing whole porcine lenses and connective tissues ex vivo under varying physiologically relevant stretching conditions using a bespoke lens stretching device. Additionally, some lenses were treated with a YAP function inhibitor to determine the Hippo signaling pathway's role in regulating lens growth. Resulting changes in LEC labeling index were analyzed using EdU incorporation and flow cytometry for each lens. Results LEC proliferation was found to be modulated by mechanical strain. Increasing both the magnitude of static stretching and the stretching frequency in cyclic stretching resulted in a proportional increase in the labeling indices of the LECs. Additionally, treatment with the YAP function inhibitor effectively eliminated this relationship. Conclusions These data demonstrate that LEC proliferation is regulated in part, by the mechanotransduction of stresses induced in the lens capsule and that YAP plays an important role in mechanosensing. These results have important implications for understanding lens growth and morphogenesis. The model may also be used to identify and evaluate targets for modulating lens growth.
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Affiliation(s)
- Bharat Kumar
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, United States
| | - Heather L. Chandler
- College of Optometry, The Ohio State University, Columbus, Ohio, United States
- College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States
| | - Timothy Plageman
- College of Optometry, The Ohio State University, Columbus, Ohio, United States
| | - Matthew A. Reilly
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, United States
- Department of Ophthalmology and Visual Science, The Ohio State University, Columbus, Ohio, United States
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13
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Sakashita T, Sato T, Hamada N. A biologically based mathematical model for spontaneous and ionizing radiation cataractogenesis. PLoS One 2019; 14:e0221579. [PMID: 31442279 PMCID: PMC6707595 DOI: 10.1371/journal.pone.0221579] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 08/04/2019] [Indexed: 12/20/2022] Open
Abstract
Cataracts have long been known, but a biomathematical model is still unavailable for cataratogenesis. There has been a renewed interest in ionizing radiation cataracts because the recent international recommendation of the reduced lens dose limit stimulated the discussion toward its regulatory implementation in various countries. Nevertheless, a relationship between radiation (dose and dose rate) and response (e.g., incidence, onset and progression) remains incompletely understood, raising the need for a risk-predictive mathematical model. We here report for the first time an in silico model for cataractogenesis. First, a simplified cell proliferation model was developed for human lens growth based on stem and progenitor cell proliferation as well as epithelial-fiber cell differentiation. Then, a model for spontaneous cataractogenesis was developed to reproduce the human data on a relationship between age and cataract incidence. Finally, a model for radiation cataractogenesis was developed that can reproduce the human data on a relationship between dose and cataract onset at various ages, which was further applied to estimate cataract incidence following chronic lifetime exposure. The model can serve as the foundation for further development of the risk-predictive model for cataractogenesis along with additional considerations of various biological mechanisms and epidemiological datasets.
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Affiliation(s)
- Tetsuya Sakashita
- Department of Radiation-Applied Biology Research, Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology (QST), Watanuki, Takasaki, Gunma, Japan
| | - Tatsuhiko Sato
- Research Group for Radiation Transport Analysis, Nuclear Science and Engineering Center, Japan Atomic Energy Agency (JAEA), Shirakata, Tokai, Ibaraki, Japan
| | - Nobuyuki Hamada
- Radiation Safety Research Center, Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), Iwado-kita, Komae, Tokyo, Japan
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14
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Barnard SGR, McCarron R, Moquet J, Quinlan R, Ainsbury E. Inverse dose-rate effect of ionising radiation on residual 53BP1 foci in the eye lens. Sci Rep 2019; 9:10418. [PMID: 31320710 PMCID: PMC6639373 DOI: 10.1038/s41598-019-46893-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 07/02/2019] [Indexed: 12/25/2022] Open
Abstract
The influence of dose rate on radiation cataractogenesis has yet to be extensively studied. One recent epidemiological investigation suggested that protracted radiation exposure increases radiation-induced cataract risk: cumulative doses of radiation mostly <100 mGy received by US radiologic technologists over 5 years were associated with an increased excess hazard ratio for cataract development. However, there are few mechanistic studies to support and explain such observations. Low-dose radiation-induced DNA damage in the epithelial cells of the eye lens (LECs) has been proposed as a possible contributor to cataract formation and thus visual impairment. Here, 53BP1 foci was used as a marker of DNA damage. Unexpectedly, the number of 53BP1 foci that persisted in the mouse lens samples after γ-radiation exposure increased with decreasing dose-rate at 4 and 24 h. The C57BL/6 mice were exposed to 0.5, 1 and 2 Gy ƴ-radiation at 0.063 and 0.3 Gy/min and also 0.5 Gy at 0.014 Gy/min. This contrasts the data we obtained for peripheral blood lymphocytes collected from the same animal groups, which showed the expected reduction of residual 53BP1 foci with reducing dose-rate. These findings highlight the likely importance of dose-rate in low-dose cataract formation and, furthermore, represent the first evidence that LECs process radiation damage differently to blood lymphocytes.
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Affiliation(s)
- Stephen G R Barnard
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, Oxon, UK.
- Durham University, Department of Biosciences, Durham, UK.
| | - Roisin McCarron
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, Oxon, UK
| | - Jayne Moquet
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, Oxon, UK
| | - Roy Quinlan
- Durham University, Department of Biosciences, Durham, UK.
| | - Elizabeth Ainsbury
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, Oxon, UK
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15
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Cataractogenic load – A concept to study the contribution of ionizing radiation to accelerated aging in the eye lens. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2019; 779:68-81. [DOI: 10.1016/j.mrrev.2019.02.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 02/12/2019] [Accepted: 02/14/2019] [Indexed: 12/11/2022]
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16
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Barnard SGR, Moquet J, Lloyd S, Ellender M, Ainsbury EA, Quinlan RA. Dotting the eyes: mouse strain dependency of the lens epithelium to low dose radiation-induced DNA damage. Int J Radiat Biol 2018; 94:1116-1124. [PMID: 30359158 DOI: 10.1080/09553002.2018.1532609] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE Epidemiological evidence regarding the radiosensitivity of the lens of the eye and radiation cataract development has led to changes in the EU Basic Safety Standards for protection of the lens against ionizing radiation. However, mechanistic details of lens radiation response pathways and their significance for cataractogenesis remain unclear. Radiation-induced DNA damage and the potential impairment of repair pathways within the lens epithelium, a cell monolayer that covers the anterior hemisphere of the lens, are likely to be involved. MATERIALS AND METHODS In this work, the lens epithelium has been analyzed for its DNA double-strand break (DSB) repair response to ionizing radiation. The responses of epithelial cells located at the anterior pole (central region) have been compared to at the very periphery of the monolayer (germinative and transitional zones). Described here are the different responses in the two regions and across four strains (C57BL/6, 129S2, BALB/c and CBA/Ca) over a low dose (0-25 mGy) in-vivo whole body X-irradiation range up to 24 hours post exposure. RESULTS DNA damage and repair as visualized through 53BP1 staining was present across the lens epithelium, although repair kinetics appeared non-uniform. Epithelial cells in the central region have significantly more 53BP1 foci. The sensitivities of different mouse strains have also been compared. CONCLUSIONS 129S2 and BALB/c showed higher levels of DNA damage, with BALB/c showing significantly less inter-individual variability and appearing to be a more robust model for future DNA damage and repair studies. As a result of this study, BALB/c was identified as a suitable radiosensitive lens strain to detect and quantify early low dose ionizing radiation DNA damage effects in the mouse eye lens specifically, as an indicator of cataract formation.
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Affiliation(s)
- S G R Barnard
- a Centre for Radiation, Chemical and Environmental Hazards , Public Health England , Chilton , Oxon, UK.,b Department of Biosciences , Durham University , Durham , UK
| | - J Moquet
- a Centre for Radiation, Chemical and Environmental Hazards , Public Health England , Chilton , Oxon, UK
| | - S Lloyd
- a Centre for Radiation, Chemical and Environmental Hazards , Public Health England , Chilton , Oxon, UK.,c School of Biosciences , The University of Birmingham , Edgbaston , UK
| | - M Ellender
- a Centre for Radiation, Chemical and Environmental Hazards , Public Health England , Chilton , Oxon, UK
| | - E A Ainsbury
- a Centre for Radiation, Chemical and Environmental Hazards , Public Health England , Chilton , Oxon, UK
| | - R A Quinlan
- b Department of Biosciences , Durham University , Durham , UK
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17
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Bassnett S, Šikić H. The lens growth process. Prog Retin Eye Res 2017; 60:181-200. [PMID: 28411123 DOI: 10.1016/j.preteyeres.2017.04.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 01/17/2023]
Abstract
The factors that regulate the size of organs to ensure that they fit within an organism are not well understood. A simple organ, the ocular lens serves as a useful model with which to tackle this problem. In many systems, considerable variance in the organ growth process is tolerable. This is almost certainly not the case in the lens, which in addition to fitting comfortably within the eyeball, must also be of the correct size and shape to focus light sharply onto the retina. Furthermore, the lens does not perform its optical function in isolation. Its growth, which continues throughout life, must therefore be coordinated with that of other tissues in the optical train. Here, we review the lens growth process in detail, from pioneering clinical investigations in the late nineteenth century to insights gleaned more recently in the course of cell and molecular studies. During embryonic development, the lens forms from an invagination of surface ectoderm. Consequently, the progenitor cell population is located at its surface and differentiated cells are confined to the interior. The interactions that regulate cell fate thus occur within the obligate ellipsoidal geometry of the lens. In this context, mathematical models are particularly appropriate tools with which to examine the growth process. In addition to identifying key growth determinants, such models constitute a framework for integrating cell biological and optical data, helping clarify the relationship between gene expression in the lens and image quality at the retinal plane.
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Affiliation(s)
- Steven Bassnett
- Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, USA.
| | - Hrvoje Šikić
- Department of Mathematics, Faculty of Science, University of Zagreb, Croatia
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18
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Šikić H, Shi Y, Lubura S, Bassnett S. A full lifespan model of vertebrate lens growth. ROYAL SOCIETY OPEN SCIENCE 2017; 4:160695. [PMID: 28280571 PMCID: PMC5319337 DOI: 10.1098/rsos.160695] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 12/05/2016] [Indexed: 06/06/2023]
Abstract
The mathematical determinants of vertebrate organ growth have yet to be elucidated fully. Here, we utilized empirical measurements and a dynamic branching process-based model to examine the growth of a simple organ system, the mouse lens, from E14.5 until the end of life. Our stochastic model used difference equations to model immigration and emigration between zones of the lens epithelium and included some deterministic elements, such as cellular footprint area. We found that the epithelial cell cycle was shortened significantly in the embryo, facilitating the rapid growth that marks early lens development. As development progressed, epithelial cell division becomes non-uniform and four zones, each with a characteristic proliferation rate, could be discerned. Adjustment of two model parameters, proliferation rate and rate of change in cellular footprint area, was sufficient to specify all growth trajectories. Modelling suggested that the direction of cellular migration across zonal boundaries was sensitive to footprint area, a phenomenon that may isolate specific cell populations. Model runs consisted of more than 1000 iterations, in each of which the stochastic behaviour of thousands of cells was followed. Nevertheless, sequential runs were almost superimposable. This remarkable degree of precision was attributed, in part, to the presence of non-mitotic flanking regions, which constituted a path by which epithelial cells could escape the growth process. Spatial modelling suggested that clonal clusters of about 50 cells are produced during migration and that transit times lengthen significantly at later stages, findings with implications for the formation of certain types of cataract.
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Affiliation(s)
- Hrvoje Šikić
- Department of Ophthalmology and Visual Sciences, Washington University, St Louis, MO 63130, USA
- Department of Mathematics, University of Zagreb, Zagreb, Croatia
| | - Yanrong Shi
- Department of Ophthalmology and Visual Sciences, Washington University, St Louis, MO 63130, USA
| | - Snježana Lubura
- Department of Mathematics, University of Zagreb, Zagreb, Croatia
| | - Steven Bassnett
- Department of Ophthalmology and Visual Sciences, Washington University, St Louis, MO 63130, USA
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19
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Ainsbury EA, Barnard S, Bright S, Dalke C, Jarrin M, Kunze S, Tanner R, Dynlacht JR, Quinlan RA, Graw J, Kadhim M, Hamada N. Ionizing radiation induced cataracts: Recent biological and mechanistic developments and perspectives for future research. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2016; 770:238-261. [DOI: 10.1016/j.mrrev.2016.07.010] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/27/2016] [Accepted: 07/28/2016] [Indexed: 02/06/2023]
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20
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Bassnett S, Costello MJ. The cause and consequence of fiber cell compaction in the vertebrate lens. Exp Eye Res 2016; 156:50-57. [PMID: 26992780 DOI: 10.1016/j.exer.2016.03.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 03/02/2016] [Accepted: 03/11/2016] [Indexed: 01/02/2023]
Abstract
Fiber cells of the ocular lens are arranged in a series of concentric shells. New growth shells are added continuously to the lens surface and, as a consequence, the preexisting shells are buried. To focus light, the refractive index of the lens cytoplasm must exceed that of the surrounding aqueous and vitreous humors, and to that end, lens cells synthesize high concentrations of soluble proteins, the crystallins. To correct for spherical aberration, it is necessary that the crystallin concentration varies from shell-to-shell, such that cellular protein content is greatest in the center of the lens. The radial variation in protein content underlies the critical gradient index (GRIN) structure of the lens. Only the outermost shells of lens fibers contain the cellular machinery necessary for protein synthesis. It is likely, therefore, that the GRIN (which spans the synthetically inactive, organelle-free zone of the lens) does not result from increased levels of protein synthesis in the core of the lens but is instead generated through loss of volume by inner fiber cells. Because volume is lost primarily in the form of cell water, the residual proteins in the central lens fibers can be concentrated to levels of >500 mg/ml. In this short review, we describe the process of fiber cell compaction, its relationship to lens growth and GRIN formation, and offer some thoughts on the likely nature of the underlying mechanism.
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Affiliation(s)
- Steven Bassnett
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, USA.
| | - M Joseph Costello
- Department of Cell Biology and Physiology, University of North Carolina School of Medicine, USA
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21
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Cheng C, Nowak RB, Fowler VM. The lens actin filament cytoskeleton: Diverse structures for complex functions. Exp Eye Res 2016; 156:58-71. [PMID: 26971460 DOI: 10.1016/j.exer.2016.03.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 03/01/2016] [Accepted: 03/07/2016] [Indexed: 01/05/2023]
Abstract
The eye lens is a transparent and avascular organ in the front of the eye that is responsible for focusing light onto the retina in order to transmit a clear image. A monolayer of epithelial cells covers the anterior hemisphere of the lens, and the bulk of the lens is made up of elongated and differentiated fiber cells. Lens fiber cells are very long and thin cells that are supported by sophisticated cytoskeletal networks, including actin filaments at cell junctions and the spectrin-actin network of the membrane skeleton. In this review, we highlight the proteins that regulate diverse actin filament networks in the lens and discuss how these actin cytoskeletal structures assemble and function in epithelial and fiber cells. We then discuss methods that have been used to study actin in the lens and unanswered questions that can be addressed with novel techniques.
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Affiliation(s)
- Catherine Cheng
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Roberta B Nowak
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Velia M Fowler
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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22
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Jarrin M, Young L, Wu W, Girkin JM, Quinlan RA. In vivo, Ex Vivo, and In Vitro Approaches to Study Intermediate Filaments in the Eye Lens. Methods Enzymol 2016; 568:581-611. [DOI: 10.1016/bs.mie.2015.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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23
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Affiliation(s)
- Roy A Quinlan
- Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK.
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