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Kocherlakota S, Baes M. Benefits and Caveats in the Use of Retinal Pigment Epithelium-Specific Cre Mice. Int J Mol Sci 2024; 25:1293. [PMID: 38279294 PMCID: PMC10816505 DOI: 10.3390/ijms25021293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/16/2024] [Accepted: 01/18/2024] [Indexed: 01/28/2024] Open
Abstract
The retinal pigment epithelium (RPE) is an important monolayer of cells present in the outer retina, forming a major part of the blood-retina barrier (BRB). It performs many tasks essential for the maintenance of retinal integrity and function. With increasing knowledge of the retina, it is becoming clear that both common retinal disorders, like age-related macular degeneration, and rare genetic disorders originate in the RPE. This calls for a better understanding of the functions of various proteins within the RPE. In this regard, mice enabling an RPE-specific gene deletion are a powerful tool to study the role of a particular protein within the RPE cells in their native environment, simultaneously negating any potential influences of systemic changes. Moreover, since RPE cells interact closely with adjacent photoreceptors, these mice also provide an excellent avenue to study the importance of a particular gene function within the RPE to the retina as a whole. In this review, we outline and compare the features of various Cre mice created for this purpose, which allow for inducible or non-inducible RPE-specific knockout of a gene of interest. We summarize the various benefits and caveats involved in the use of such mouse lines, allowing researchers to make a well-informed decision on the choice of Cre mouse to use in relation to their research needs.
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Affiliation(s)
| | - Myriam Baes
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
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2
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Bhattacharya S, Yin J, Huo W, Chaum E. Loss of Prom1 impairs autophagy and promotes epithelial-mesenchymal transition in mouse retinal pigment epithelial cells. J Cell Physiol 2023; 238:2373-2389. [PMID: 37610047 DOI: 10.1002/jcp.31094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/15/2023] [Accepted: 07/20/2023] [Indexed: 08/24/2023]
Abstract
Mutations in the Prominin-1 (Prom1) gene disrupt photoreceptor disk morphogenesis, leading to macular dystrophies. We have shown that human retinal pigment epithelial (RPE) homeostasis is under the control of Prom1-dependent autophagy, demonstrating that Prom1 plays different roles in the photoreceptors and RPE. It is unclear if retinal and macular degeneration caused by the loss of Prom1 function is a cell-autonomous feature of the RPE or a generalized disease of photoreceptor degeneration. In this study, we investigated whether Prom1 is required for mouse RPE (mRPE) autophagy and phagocytosis, which are cellular processes essential for photoreceptor survival. We found that Prom1-KO decreases autophagy flux, activates mTORC1, and concomitantly decreases transcription factor EB (TFEB) and Cathepsin-D activities in mRPE cells. In addition, Prom1-KO reduces the clearance of bovine photoreceptor outer segments in mRPE cells due to increased mTORC1 and reduced TFEB activities. Dysfunction of Prom1-dependent autophagy correlates with both a decrease in ZO-1 and E-cadherin and a concomitant increase in Vimentin, SNAI1, and ZEB1 levels, consistent with induction of epithelial-mesenchymal transition (EMT) in Prom1-KO mRPE cells. Our results demonstrate that Prom1-mTORC1-TFEB signaling is a central driver of cell-autonomous mRPE homeostasis. We show that Prom1-KO in mRPE leads to RPE defects similar to that seen in atrophic age-related macular degeneration and opens new avenues of investigation targeting Prom1 in retinal degenerative diseases.
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Affiliation(s)
- Sujoy Bhattacharya
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jinggang Yin
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Weihong Huo
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Edward Chaum
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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3
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Nwagbo U, Bernstein PS. Understanding the Roles of Very-Long-Chain Polyunsaturated Fatty Acids (VLC-PUFAs) in Eye Health. Nutrients 2023; 15:3096. [PMID: 37513514 PMCID: PMC10383069 DOI: 10.3390/nu15143096] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/06/2023] [Accepted: 07/08/2023] [Indexed: 07/30/2023] Open
Abstract
Lipids serve many roles in the neural system, from synaptic stabilization and signaling to DNA regulation and neuroprotection. They also regulate inflammatory responses, maintain cellular membrane structure, and regulate the homeostatic balance of ions and signaling molecules. An imbalance of lipid subgroups is implicated in the progression of many retinal diseases, such as age-related macular degeneration (AMD), retinitis pigmentosa, and diabetic retinopathy, and diet can play a key role in influencing these diseases' onset, progression, and severity. A special class of lipids termed very-long-chain polyunsaturated fatty acids (VLC-PUFAs) is found exclusively in mammalian vertebrate retinas and a few other tissues. They comprise <2% of fatty acids in the retina and are depleted in the retinas of patients with diseases like diabetic retinopathy and AMD. However, the implications of the reduction in VLC-PUFA levels are poorly understood. Dietary supplementation studies and ELOVL4 transgene studies have had positive outcomes. However, much remains to be understood about their role in retinal health and the potential for targeted therapies against retinal disease.
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Affiliation(s)
- Uzoamaka Nwagbo
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT 84132, USA;
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Paul S. Bernstein
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT 84132, USA;
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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4
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Loss of Hes1 in embryonic stem cells caused developmental disorders in retinal pigment epithelium morphogenesis and specification. Biochem Biophys Res Commun 2022; 632:76-84. [DOI: 10.1016/j.bbrc.2022.09.080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 08/23/2022] [Accepted: 09/21/2022] [Indexed: 11/20/2022]
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5
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Vargas JA, Finnemann SC. Probing Photoreceptor Outer Segment Phagocytosis by the RPE In Vivo: Models and Methodologies. Int J Mol Sci 2022; 23:ijms23073661. [PMID: 35409021 PMCID: PMC8998817 DOI: 10.3390/ijms23073661] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 01/27/2023] Open
Abstract
In the vertebrate retina, the light-sensitive photoreceptor rods and cones constantly undergo renewal by generating new portions of the outer segment and shedding their distal, spent tips. The neighboring RPE provides the critical function of engulfing the spent material by phagocytosis. RPE phagocytosis of shed rod outer segment fragments is a circadian process that occurs in a burst of activity shortly after daily light onset with low activity at other times, a rhythm that has been reported for many species and over 50 years. In this review, we compare studies on the rhythm and quantity of RPE phagocytosis using different in vivo model systems and assessment methods. We discuss how measurement methodology impacts the observation and analysis of RPE phagocytosis. Published studies on RPE phagocytosis investigating mice further suggest that differences in genetic background and housing conditions may affect results. Altogether, a comparison between RPE phagocytosis studies performed using differing methodology and strains of the same species is not as straightforward as previously thought.
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6
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Lewandowski D, Foik AT, Smidak R, Choi EH, Zhang J, Hoang T, Tworak A, Suh S, Leinonen H, Dong Z, Pinto AF, Tom E, Luu JC, Lee JY, Ma X, Bieberich E, Blackshaw S, Saghatelian A, Lyon DC, Skowronska-Krawczyk D, Tabaka M, Palczewski K. Inhibition of ceramide accumulation in AdipoR1-/- mice increases photoreceptor survival and improves vision. JCI Insight 2022; 7:156301. [PMID: 35015730 PMCID: PMC8876453 DOI: 10.1172/jci.insight.156301] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 01/05/2022] [Indexed: 11/20/2022] Open
Abstract
Adiponectin receptor 1 (ADIPOR1) is a lipid and glucose metabolism regulator that possesses intrinsic ceramidase activity. Mutations of the ADIPOR1 gene have been associated with nonsyndromic and syndromic retinitis pigmentosa. Here, we show that the absence of AdipoR1 in mice leads to progressive photoreceptor degeneration, significant reduction of electroretinogram amplitudes, decreased retinoid content in the retina, and reduced cone opsin expression. Single-cell RNA-Seq results indicate that ADIPOR1 encoded the most abundantly expressed ceramidase in mice and one of the 2 most highly expressed ceramidases in the human retina, next to acid ceramidase ASAH1. We discovered an accumulation of ceramides in the AdipoR1–/– retina, likely due to insufficient ceramidase activity for healthy retina function, resulting in photoreceptor death. Combined treatment with desipramine/L-cycloserine (DC) lowered ceramide levels and exerted a protective effect on photoreceptors in AdipoR1–/– mice. Moreover, we observed improvement in cone-mediated retinal function in the DC-treated animals. Lastly, we found that prolonged DC treatment corrected the electrical responses of the primary visual cortex to visual stimuli, approaching near-normal levels for some parameters. These results highlight the importance of ADIPOR1 ceramidase in the retina and show that pharmacological inhibition of ceramide generation can provide a therapeutic strategy for ADIPOR1-related retinopathy.
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Affiliation(s)
- Dominik Lewandowski
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Andrzej T Foik
- International Center for Translational Eye Research, Institute of Physical Chemistry PAS, Warsaw, Poland
| | - Roman Smidak
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Elliot H Choi
- Department of Pharmacology, Case Western Reserve University, Cleveland, United States of America
| | - Jianye Zhang
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Thanh Hoang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States of America
| | - Aleksander Tworak
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Susie Suh
- Department of Pharmacology, Case Western Reserve University, Cleveland, United States of America
| | - Henri Leinonen
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Zhiqian Dong
- Department of Medical Devices, Polgenix Inc., Cleveland, United States of America
| | - Antonio Fm Pinto
- Clayton Foundation Laboratories for Peptide Biology, Salk Institute for Biological Studies, La Jolla, United States of America
| | - Emily Tom
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Jennings C Luu
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
| | - Joan Y Lee
- MetroHealth Medical Center, Case Western Reserve University, Cleveland, United States of America
| | - Xiuli Ma
- Department of Medical Devices, Polgenix Inc, Cleveland, United States of America
| | - Erhard Bieberich
- Department of Physiology, University of Kentucky, Lexington, United States of America
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, John Hopkins School of Medicine, Baltimore, United States of America
| | - Alan Saghatelian
- Clayton Foundation Laboratories for Peptide Biology, Salk Institute for Biological Studies, La Jolla, United States of America
| | - David C Lyon
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, United States of America
| | | | - Marcin Tabaka
- International Center for Translational Eye Research, Institute of Physical Chemistry PAS, Warsaw, Poland
| | - Krzysztof Palczewski
- Department of Ophthalmology, University of California, Irvine, Irvine, United States of America
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7
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A Novel Method of Mouse RPE Explant Culture and Effective Introduction of Transgenes Using Adenoviral Transduction for In Vitro Studies in AMD. Int J Mol Sci 2021; 22:ijms222111979. [PMID: 34769409 PMCID: PMC8584596 DOI: 10.3390/ijms222111979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/02/2021] [Indexed: 12/04/2022] Open
Abstract
Degeneration of retinal pigment epithelium (RPE) is one of the most critical phenotypic changes of age-related macular degeneration (AMD), the leading cause of vision loss in the elderly. While cultured polarized RPE cells with original properties are valuable in in vitro models to study RPE biology and the consequences of genetic and/or pharmacological manipulations, the procedure to establish mouse primary PRE cell culture or pluripotent stem cell-derived RPE cells is time-consuming and yields a limited number of cells. Thus, establishing a mouse in situ RPE culture system is highly desirable. Here we describe a novel and efficient method for RPE explant culture that allows for obtaining biologically relevant RPE cells in situ. These RPE explants (herein referred to as RPE flatmounts) are viable in culture for at least 7 days, can be efficiently transduced with adenoviral constructs, and/or treated with a variety of drugs/chemicals followed by downstream analysis of the signaling pathways/biological processes of interest, such as assessment of the autophagy flux, inflammatory response, and receptor tyrosine kinases stimulation. This method of RPE explant culture is highly beneficial for pharmacological and mechanistic studies in the field of RPE biology and AMD research.
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8
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Piotter E, McClements ME, MacLaren RE. Therapy Approaches for Stargardt Disease. Biomolecules 2021; 11:1179. [PMID: 34439845 PMCID: PMC8393614 DOI: 10.3390/biom11081179] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/27/2021] [Accepted: 08/05/2021] [Indexed: 12/14/2022] Open
Abstract
Despite being the most prevalent cause of inherited blindness in children, Stargardt disease is yet to achieve the same clinical trial success as has been achieved for other inherited retinal diseases. With an early age of onset and continual progression of disease over the life course of an individual, Stargardt disease appears to lend itself to therapeutic intervention. However, the aetiology provides issues not encountered with the likes of choroideremia and X-linked retinitis pigmentosa and this has led to a spectrum of treatment strategies that approach the problem from different aspects. These include therapeutics ranging from small molecules and anti-sense oligonucleotides to viral gene supplementation and cell replacement. The advancing development of CRISPR-based molecular tools is also likely to contribute to future therapies by way of genome editing. In this we review, we consider the most recent pre-clinical and clinical trial data relating to the different strategies being applied to the problem of generating a treatment for the large cohort of Stargardt disease patients worldwide.
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Affiliation(s)
- Elena Piotter
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
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9
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Yeboah GK, Lobanova ES, Brush RS, Agbaga MP. Very long chain fatty acid-containing lipids: a decade of novel insights from the study of ELOVL4. J Lipid Res 2021; 62:100030. [PMID: 33556440 PMCID: PMC8042400 DOI: 10.1016/j.jlr.2021.100030] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 01/12/2021] [Accepted: 01/27/2021] [Indexed: 11/18/2022] Open
Abstract
Lipids play essential roles in maintaining cell structure and function by modulating membrane fluidity and cell signaling. The fatty acid elongase-4 (ELOVL4) protein, expressed in retina, brain, Meibomian glands, skin, testes and sperm, is an essential enzyme that mediates tissue-specific biosynthesis of both VLC-PUFA and VLC-saturated fatty acids (VLC-SFA). These fatty acids play critical roles in maintaining retina and brain function, neuroprotection, skin permeability barrier maintenance, and sperm function, among other important cellular processes. Mutations in ELOVL4 that affect biosynthesis of these fatty acids cause several distinct tissue-specific human disorders that include blindness, age-related cerebellar atrophy and ataxia, skin disorders, early-childhood seizures, mental retardation, and mortality, which underscores the essential roles of ELOVL4 products for life. However, the mechanisms by which one tissue makes VLC-PUFA and another makes VLC-SFA, and how these fatty acids exert their important functional roles in each tissue, remain unknown. This review summarizes research over that last decade that has contributed to our current understanding of the role of ELOVL4 and its products in cellular function. In the retina, VLC-PUFA and their bioactive "Elovanoids" are essential for retinal function. In the brain, VLC-SFA are enriched in synaptic vesicles and mediate neuronal signaling by determining the rate of neurotransmitter release essential for normal neuronal function. These findings point to ELOVL4 and its products as being essential for life. Therefore, mutations and/or age-related epigenetic modifications of fatty acid biosynthetic gene activity that affect VLC-SFA and VLC-PUFA biosynthesis contribute to age-related dysfunction of ELOVL4-expressing tissues.
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Affiliation(s)
- Gyening Kofi Yeboah
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Ekaterina S Lobanova
- Department of Ophthalmology Research, University of Florida, Gainesville, FL, USA
| | - Richard S Brush
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean A. McGee Eye Institute, Oklahoma City, OK, USA
| | - Martin-Paul Agbaga
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean A. McGee Eye Institute, Oklahoma City, OK, USA.
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10
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Starace V, Battista M, Brambati M, Pederzolli M, Viganò C, Arrigo A, Cicinelli MV, Bandello F, Parodi MB. Genotypic and phenotypic factors influencing the rate of progression in ABCA-4-related Stargardt disease. EXPERT REVIEW OF OPHTHALMOLOGY 2020. [DOI: 10.1080/17469899.2021.1860753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Vincenzo Starace
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Marco Battista
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Maria Brambati
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Matteo Pederzolli
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Chiara Viganò
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Alessandro Arrigo
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Maria Vittoria Cicinelli
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
| | - Maurizio Battaglia Parodi
- Department of Ophthalmology, IRCCS San Raffaele Scientific Institute, Milan, Italy
- School of Medicine, Vita-Salute San Raffaele University, Milan, Italy
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11
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Lakkaraju A, Umapathy A, Tan LX, Daniele L, Philp NJ, Boesze-Battaglia K, Williams DS. The cell biology of the retinal pigment epithelium. Prog Retin Eye Res 2020; 78:100846. [PMID: 32105772 PMCID: PMC8941496 DOI: 10.1016/j.preteyeres.2020.100846] [Citation(s) in RCA: 185] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/19/2020] [Accepted: 02/23/2020] [Indexed: 02/07/2023]
Abstract
The retinal pigment epithelium (RPE), a monolayer of post-mitotic polarized epithelial cells, strategically situated between the photoreceptors and the choroid, is the primary caretaker of photoreceptor health and function. Dysfunction of the RPE underlies many inherited and acquired diseases that cause permanent blindness. Decades of research have yielded valuable insight into the cell biology of the RPE. In recent years, new technologies such as live-cell imaging have resulted in major advancement in our understanding of areas such as the daily phagocytosis and clearance of photoreceptor outer segment tips, autophagy, endolysosome function, and the metabolic interplay between the RPE and photoreceptors. In this review, we aim to integrate these studies with an emphasis on appropriate models and techniques to investigate RPE cell biology and metabolism, and discuss how RPE cell biology informs our understanding of retinal disease.
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Affiliation(s)
- Aparna Lakkaraju
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Ankita Umapathy
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Li Xuan Tan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, CA, USA
| | - Lauren Daniele
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Nancy J Philp
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David S Williams
- Department of Ophthalmology and Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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12
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Scavuzzo CJ, LeBlancq MJ, Nargang F, Lemieux H, Hamilton TJ, Dickson CT. The amnestic agent anisomycin disrupts intrinsic membrane properties of hippocampal neurons via a loss of cellular energetics. J Neurophysiol 2019; 122:1123-1135. [PMID: 31291154 PMCID: PMC6766744 DOI: 10.1152/jn.00370.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/08/2019] [Accepted: 07/08/2019] [Indexed: 12/20/2022] Open
Abstract
The nearly axiomatic idea that de novo protein synthesis is necessary for long-term memory consolidation is based heavily on behavioral studies using translational inhibitors such as anisomycin. Although inhibiting protein synthesis has been shown to disrupt the expression of memory, translational inhibitors also have been found to profoundly disrupt basic neurobiological functions, including the suppression of ongoing neural activity in vivo. In the present study, using transverse hippocampal brain slices, we monitored the passive and active membrane properties of hippocampal CA1 pyramidal neurons using intracellular whole cell recordings during a brief ~30-min exposure to fast-bath-perfused anisomycin. Anisomycin suppressed protein synthesis to 46% of control levels as measured using incorporation of radiolabeled amino acids and autoradiography. During its application, anisomycin caused a significant depolarization of the membrane potential, without any changes in apparent input resistance or membrane time constant. Anisomycin-treated neurons also showed significant decreases in firing frequencies and spike amplitudes, and showed increases in spike width across spike trains, without changes in spike threshold. Because these changes indicated a loss of cellular energetics contributing to maintenance of ionic gradients across the membrane, we confirmed that anisomycin impaired mitochondrial function by reduced staining with 2,3,5-triphenyltetrazolium chloride and also impaired cytochrome c oxidase (complex IV) activity as indicated through high-resolution respirometry. These findings emphasize that anisomycin-induced alterations in neural activity and metabolism are a likely consequence of cell-wide translational inhibition. Critical reevaluation of studies using translational inhibitors to promote the protein synthesis dependent idea of long-term memory is absolutely necessary.NEW & NOTEWORTHY Memory consolidation is thought to be dependent on the synthesis of new proteins because translational inhibitors produce amnesia when administered just after learning. However, these agents also disrupt basic neurobiological functions. We show that blocking protein synthesis disrupts basic membrane properties of hippocampal neurons that correspond to induced disruptions of mitochondrial function. It is likely that translational inhibitors cause amnesia through their disruption of neural activity as a result of dysfunction of intracellular energetics.
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Affiliation(s)
- C. J. Scavuzzo
- Department of Psychology, University of Alberta, Edmonton, Alberta, Canada
| | - M. J. LeBlancq
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - F. Nargang
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - H. Lemieux
- Faculty Saint-Jean, Department of Medicine, Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - T. J. Hamilton
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Department of Psychology, MacEwan University, Edmonton, Alberta, Canada
| | - C. T. Dickson
- Department of Psychology, University of Alberta, Edmonton, Alberta, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
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13
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Hopiavuori BR, Anderson RE, Agbaga MP. ELOVL4: Very long-chain fatty acids serve an eclectic role in mammalian health and function. Prog Retin Eye Res 2018; 69:137-158. [PMID: 30982505 PMCID: PMC6688602 DOI: 10.1016/j.preteyeres.2018.10.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 10/17/2018] [Accepted: 10/22/2018] [Indexed: 11/30/2022]
Abstract
ELOngation of Very Long chain fatty acids-4 (ELOVL4) is an elongase responsible for the biosynthesis of very long chain (VLC, ≥C28) saturated (VLC-SFA) and polyunsaturated (VLC-PUFA) fatty acids in brain, retina, skin, Meibomian glands, and testes. Fascinatingly, different mutations in this gene have been reported to cause vastly different phenotypes in humans. Heterozygous inheritance of seven different mutations in the coding sequence and 5' untranslated region of ELOVL4 causes autosomal dominant Stargardt-like macular dystrophy (STGD3), while homozygous inheritance of three more mutant variants causes severe seizures with ichthyosis, hypertonia, and even death. Some recent studies have described heterozygous inheritance in yet another three mutant ELOVL4 variants, two that cause spinocerebellar ataxia-34 (SCA34) with erythrokeratodermia (EKV) and one that causes SCA34 without EKV. We identified the specific enzymatic reactions catalyzed by ELOVL4 and, using a variety of genetically engineered mouse models, have actively searched for the mechanisms by which ELOVL4 impacts neural function and health. In this review, we critically compare and contrast the various animal model and case studies involving ELOVL4 deficiency via either mutation or deletion, and the resulting consequences on neuronal health and function in both the retina and central nervous system.
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Affiliation(s)
- Blake R Hopiavuori
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Robert E Anderson
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Martin-Paul Agbaga
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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Lynn SA, Keeling E, Dewing JM, Johnston DA, Page A, Cree AJ, Tumbarello DA, Newman TA, Lotery AJ, Ratnayaka JA. A convenient protocol for establishing a human cell culture model of the outer retina. F1000Res 2018; 7:1107. [PMID: 30271583 PMCID: PMC6137423 DOI: 10.12688/f1000research.15409.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/28/2018] [Indexed: 12/12/2022] Open
Abstract
The retinal pigment epithelium (RPE) plays a key role in the pathogenesis of several blinding retinopathies. Alterations to RPE structure and function are reported in Age-related Macular Degeneration, Stargardt and Best disease as well as pattern dystrophies. However, the precise role of RPE cells in disease aetiology remains incompletely understood. Many studies into RPE pathobiology have utilised animal models, which only recapitulate limited disease features. Some studies are also difficult to carry out in animals as the ocular space remains largely inaccessible to powerful microscopes. In contrast, in-vitro models provide an attractive alternative to investigating pathogenic RPE changes associated with age and disease. In this article we describe the step-by-step approach required to establish an experimentally versatile in-vitro culture model of the outer retina incorporating the RPE monolayer and supportive Bruch's membrane (BrM). We show that confluent monolayers of the spontaneously arisen human ARPE-19 cell-line cultured under optimal conditions reproduce key features of native RPE. These models can be used to study dynamic, intracellular and extracellular pathogenic changes using the latest developments in microscopy and imaging technology. We also discuss how RPE cells from human foetal and stem-cell derived sources can be incorporated alongside sophisticated BrM substitutes to replicate the aged/diseased outer retina in a dish. The work presented here will enable users to rapidly establish a realistic in-vitro model of the outer retina that is amenable to a high degree of experimental manipulation which will also serve as an attractive alternative to using animals. This in-vitro model therefore has the benefit of achieving the 3Rs objective of reducing and replacing the use of animals in research. As well as recapitulating salient structural and physiological features of native RPE, other advantages of this model include its simplicity, rapid set-up time and unlimited scope for detailed single-cell resolution and matrix studies.
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Affiliation(s)
- Savannah A. Lynn
- Clinical and Experimental Sciences, Faculty of Medicine, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
| | - Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
| | - Jennifer M. Dewing
- Clinical and Experimental Sciences, Faculty of Medicine, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
| | - David A. Johnston
- Biomedical Imaging Unit, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
| | - Anton Page
- Biomedical Imaging Unit, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
| | - Angela J. Cree
- Clinical and Experimental Sciences, Faculty of Medicine, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
| | - David A. Tumbarello
- Biological Sciences, Faculty of Natural & Environmental Sciences, Life Sciences Building 85, University of Southampton, Southampton, Hampshire, SO17 1BJ, UK
| | - Tracey A. Newman
- Clinical and Experimental Sciences, Faculty of Medicine, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
| | - Andrew J. Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
- Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton, Hampshire, SO16 6YD, UK
| | - J. Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, MP 806, Tremona Road, University of Southampton, Southampton, Hampshire, SO16 6YD, UK
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