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Paraoan L, Sharif U, Carlsson E, Supharattanasitthi W, Mahmud NM, Kamalden TA, Hiscott P, Jackson M, Grierson I. Secretory proteostasis of the retinal pigmented epithelium: Impairment links to age-related macular degeneration. Prog Retin Eye Res 2020; 79:100859. [PMID: 32278708 DOI: 10.1016/j.preteyeres.2020.100859] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/24/2020] [Accepted: 03/26/2020] [Indexed: 12/19/2022]
Abstract
Secretory proteostasis integrates protein synthesis, processing, folding and trafficking pathways that are essential for efficient cellular secretion. For the retinal pigment epithelium (RPE), secretory proteostasis is of vital importance for the maintenance of the structural and functional integrity of apical (photoreceptors) and basal (Bruch's membrane/choroidal blood supply) sides of the environment it resides in. This integrity is achieved through functions governed by RPE secreted proteins, which include extracellular matrix modelling/remodelling, angiogenesis and immune response modulation. Impaired RPE secretory proteostasis affects not only the extracellular environment, but leads to intracellular protein aggregation and ER-stress with subsequent cell death. Ample recent evidence implicates dysregulated proteostasis as a key factor in the development of age-related macular degeneration (AMD), the leading cause of blindness in the developed world, and research aiming to characterise the roles of various proteins implicated in AMD-associated dysregulated proteostasis unveiled unexpected facets of the mechanisms involved in degenerative pathogenesis. This review analyses cellular processes unveiled by the study of the top 200 transcripts most abundantly expressed by the RPE/choroid in the light of the specialised secretory nature of the RPE. Functional roles of these proteins and the mechanisms of their impaired secretion, due to age and genetic-related causes, are analysed in relation to AMD development. Understanding the importance of RPE secretory proteostasis in relation to maintaining retinal health and how it becomes impaired in disease is of paramount importance for the development and assessment of future therapeutic advancements involving gene and cell therapies.
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Affiliation(s)
- Luminita Paraoan
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom.
| | - Umar Sharif
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Emil Carlsson
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Wasu Supharattanasitthi
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom; Department of Physiology, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand
| | - Nur Musfirah Mahmud
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Tengku Ain Kamalden
- Eye Research Centre, Department of Ophthalmology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Paul Hiscott
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Malcolm Jackson
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Ian Grierson
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
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Dewing JM, Carare RO, Lotery AJ, Ratnayaka JA. The Diverse Roles of TIMP-3: Insights into Degenerative Diseases of the Senescent Retina and Brain. Cells 2019; 9:cells9010039. [PMID: 31877820 PMCID: PMC7017234 DOI: 10.3390/cells9010039] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/18/2019] [Accepted: 12/19/2019] [Indexed: 12/11/2022] Open
Abstract
Tissue inhibitor of metalloproteinase-3 (TIMP-3) is a component of the extracellular environment, where it mediates diverse processes including matrix regulation/turnover, inflammation and angiogenesis. Rare TIMP-3 risk alleles and mutations are directly linked with retinopathies such as age-related macular degeneration (AMD) and Sorsby fundus dystrophy, and potentially, through indirect mechanisms, with Alzheimer's disease. Insights into TIMP-3 activities may be gleaned from studying Sorsby-linked mutations. However, recent findings do not fully support the prevailing hypothesis that a gain of function through the dimerisation of mutated TIMP-3 is responsible for retinopathy. Findings from Alzheimer's patients suggest a hitherto poorly studied relationship between TIMP-3 and the Alzheimer's-linked amyloid-beta (A) proteins that warrant further scrutiny. This may also have implications for understanding AMD as aged/diseased retinae contain high levels of A. Findings from TIMP-3 knockout and mutant knock-in mice have not led to new treatments, particularly as the latter does not satisfactorily recapitulate the Sorsby phenotype. However, recent advances in stem cell and in vitro approaches offer novel insights into understanding TIMP-3 pathology in the retina-brain axis, which has so far not been collectively examined. We propose that TIMP-3 activities could extend beyond its hitherto supposed functions to cause age-related changes and disease in these organs.
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Affiliation(s)
- Jennifer M. Dewing
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (J.M.D.); (R.O.C.); (A.J.L.)
| | - Roxana O. Carare
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (J.M.D.); (R.O.C.); (A.J.L.)
| | - Andrew J. Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (J.M.D.); (R.O.C.); (A.J.L.)
- Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton SO16 6YD, UK
| | - J. Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton SO16 6YD, UK; (J.M.D.); (R.O.C.); (A.J.L.)
- Correspondence: ; Tel.: +44-238120-8183
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Lynn SA, Keeling E, Munday R, Gabha G, Griffiths H, Lotery AJ, Ratnayaka JA. The complexities underlying age-related macular degeneration: could amyloid beta play an important role? Neural Regen Res 2017; 12:538-548. [PMID: 28553324 PMCID: PMC5436342 DOI: 10.4103/1673-5374.205083] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Age-related macular degeneration (AMD) causes irreversible loss of central vision for which there is no effective treatment. Incipient pathology is thought to occur in the retina for many years before AMD manifests from midlife onwards to affect a large proportion of the elderly. Although genetic as well as non-genetic/environmental risks are recognized, its complex aetiology makes it difficult to identify susceptibility, or indeed what type of AMD develops or how quickly it progresses in different individuals. Here we summarize the literature describing how the Alzheimer's-linked amyloid beta (Aβ) group of misfolding proteins accumulate in the retina. The discovery of this key driver of Alzheimer's disease in the senescent retina was unexpected and surprising, enabling an altogether different perspective of AMD. We argue that Aβ fundamentally differs from other substances which accumulate in the ageing retina, and discuss our latest findings from a mouse model in which physiological amounts of Aβ were subretinally-injected to recapitulate salient features of early AMD within a short period. Our discoveries as well as those of others suggest the pattern of Aβ accumulation and pathology in donor aged/AMD tissues are closely reproduced in mice, including late-stage AMD phenotypes, which makes them highly attractive to study dynamic aspects of Aβ-mediated retinopathy. Furthermore, we discuss our findings revealing how Aβ behaves at single-cell resolution, and consider the long-term implications for neuroretinal function. We propose Aβ as a key element in switching to a diseased retinal phenotype, which is now being used as a biomarker for late-stage AMD.
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Affiliation(s)
- Savannah A Lynn
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Rosie Munday
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Gagandeep Gabha
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Helen Griffiths
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.,Eye Unit, University Southampton NHS Trust, Southampton, United Kingdom
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
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Scavelli K, Chatterjee A, Rhee DJ. Secreted Protein Acidic and Rich in Cysteine in Ocular Tissue. J Ocul Pharmacol Ther 2015; 31:396-405. [PMID: 26167673 DOI: 10.1089/jop.2015.0057] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Secreted protein acidic and rich in cysteine (SPARC), also known as osteonectin or BM-40, is the prototypical matricellular protein. Matricellular proteins are nonstructural secreted proteins that provide an integration between cells and their surrounding extracellular matrix (ECM). Regulation of the ECM is important in maintaining the physiologic function of tissues. Elevated levels of SPARC have been identified in a variety of diseases involving pathologic tissue remodeling, such as hepatic fibrosis, systemic sclerosis, and certain carcinomas. Within the eye, SPARC has been identified in the trabecular meshwork, lens, and retina. Studies have begun to show the role of SPARC in these tissues and its possible role, specifically in primary open-angle glaucoma, cataracts, and proliferative vitreoretinopathy. SPARC may, therefore, be a therapeutic target in the treatment of certain ocular diseases. Further investigation into the mechanism of action of SPARC will be necessary in the development of SPARC-targeted therapy.
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Affiliation(s)
- Kurt Scavelli
- Department of Ophthalmology and Visual Sciences, University Hospitals Eye Institute, Case Western Reserve University School of Medicine , Cleveland, Ohio
| | - Ayan Chatterjee
- Department of Ophthalmology and Visual Sciences, University Hospitals Eye Institute, Case Western Reserve University School of Medicine , Cleveland, Ohio
| | - Douglas J Rhee
- Department of Ophthalmology and Visual Sciences, University Hospitals Eye Institute, Case Western Reserve University School of Medicine , Cleveland, Ohio
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Paterson A, Ashtari M, Ribé D, Stenbeck G, Tucker A. Intelligent data analysis to model and understand live cell time-lapse sequences. Methods Inf Med 2012; 51:332-40. [PMID: 22814575 DOI: 10.3414/me11-02-0041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 04/27/2012] [Indexed: 01/10/2023]
Abstract
BACKGROUND One important aspect of cellular function, which is at the basis of tissue homeostasis, is the delivery of proteins to their correct destinations. Significant advances in live cell microscopy have allowed tracking of these pathways by following the dynamics of fluorescently labelled proteins in living cells. OBJECTIVES This paper explores intelligent data analysis techniques to model the dynamic behavior of proteins in living cells as well as to classify different experimental conditions. METHODS We use a combination of decision tree classification and hidden Markov models. In particular, we introduce a novel approach to "align" hidden Markov models so that hidden states from different models can be cross-compared. RESULTS Our models capture the dynamics of two experimental conditions accurately with a stable hidden state for control data and multiple (less stable) states for the experimental data recapitulating the behaviour of particle trajectories within live cell time-lapse data. CONCLUSIONS In addition to having successfully developed an automated framework for the classification of protein transport dynamics from live cell time-lapse data our model allows us to understand the dynamics of a complex trafficking pathway in living cells in culture.
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Affiliation(s)
- Allan Paterson
- School of Information Systems Computing and Mathematics, Brunel University, West London, UK.
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Abstract
SPARC (secreted protein acidic and rich in cysteine, also known as osteonectin or BM-40) is a widely expressed profibrotic protein with pleiotropic roles, which have been studied in a variety of conditions. Notably, SPARC is linked to human obesity; SPARC derived from adipose tissue is associated with insulin resistance and secretion of SPARC by adipose tissue is increased by insulin and the adipokine leptin. Furthermore, SPARC is associated with diabetes complications such as diabetic retinopathy and nephropathy, conditions that are ameliorated in the Sparc-knockout mouse model. As a regulator of the extracellular matrix, SPARC also contributes to adipose-tissue fibrosis. Evidence suggests that adipose tissue becomes increasingly fibrotic in obesity. Fibrosis of subcutaneous adipose tissue may restrict accumulation of triglycerides in this type of tissue. These triglycerides are, therefore, diverted and deposited as ectopic lipids in other tissues such as the liver or as intramyocellular lipids in skeletal muscle, which predisposes to insulin resistance. Hence, SPARC may represent a novel and important link between obesity and diabetes mellitus. This Review is focused on whether SPARC could be a key player in the pathology of obesity and its related metabolic complications.
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Affiliation(s)
- Katarina Kos
- Department of Diabetes and Vascular Medicine, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter EX2 5DW, UK.
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