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Murata E, Yoshida T, Tomaru U, Yamamoto S, Fukui-Miyazaki A, Ishizu A, Kasahara M. Decreased proteasome function increases oxidative stress in the early stage of pressure ulcer development. Exp Mol Pathol 2024; 137:104891. [PMID: 38462206 DOI: 10.1016/j.yexmp.2024.104891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/08/2024] [Accepted: 03/07/2024] [Indexed: 03/12/2024]
Abstract
The aging process in the elderly results in heightened skin fragility associated with various disorders, including pressure ulcers (PUs). Despite the high incidence of PUs in the elderly population, there is a limited body of research specifically examining the impact of aging on the development of pressure ulcers. Therefore, investigating age-related physiological abnormalities is essential to elucidate the pathogenesis of PUs. Ischemia-reperfusion (I/R) injury and the subsequent oxidative stress caused by reactive oxygen species (ROS) play essential roles in the early stage of PUs. In this study, we used a mouse model of proteasomal dysfunction with an age-related phenotype to examine the role of proteasome activity in cutaneous I/R injury in vivo. Decreased proteasome function did not affect the expression of inflammatory cytokines and adhesion molecules in the I/R area in transgenic mice; however, proteasome inhibition increased oxidative stress that was not attenuated by activation of the oxidative stress response mediated by NF-E2-related factor 2 (Nrf2). In dermal fibroblasts (FCs) subjected to hypoxia-reoxygenation (H/R), proteasome inhibition induced oxidative stress and ROS production, and Nrf2 activation did not adequately upregulate antioxidant enzyme expression, possibly leading to antioxidant/oxidant imbalance. The free radical scavenger edaravone had protective effects against I/R injury in vivo and decreased oxidative stress in FCs treated with a proteasome inhibitor and subjected to H/R in vitro. The results suggest that the age-related decline in proteasome activity promotes cutaneous I/R injury-induced oxidative stress, and free radical scavengers may exert protective effects by preventing oxidative stress in the early stage of PUs.
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Affiliation(s)
- Eri Murata
- Department of Pathology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita-ku, Sapporo, Japan; Department of Fundamental Nursing, Yamagata University Graduate School of Nursing, Yamagata, Yamagata, Japan
| | - Takuma Yoshida
- Department of Pathology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Utano Tomaru
- Department of Pathology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita-ku, Sapporo, Japan; Department of Surgical Pathology, Hokkaido University Hospital, Sapporo 060-8648, Japan.
| | - Saaki Yamamoto
- Department of Pathology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Aya Fukui-Miyazaki
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Akihiro Ishizu
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Kita-ku, Sapporo, Japan
| | - Masanori Kasahara
- Department of Pathology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita-ku, Sapporo, Japan
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2
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Zegeye Y, Aredo B, Yuksel S, Kirman DC, Kumar A, Chen B, Turpin E, Shresta S, He YG, Gautron L, Tang M, Li X, DiCesare SM, Hulleman JD, Xing C, Ludwig S, Moresco EMY, Beutler BA, Ufret-Vincenty RL. E3 ubiquitin ligase Herc3 deficiency leads to accumulation of subretinal microglia and retinal neurodegeneration. Sci Rep 2024; 14:3010. [PMID: 38321224 PMCID: PMC10847449 DOI: 10.1038/s41598-024-53731-8] [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: 08/01/2023] [Accepted: 02/04/2024] [Indexed: 02/08/2024] Open
Abstract
Activated microglia have been implicated in the pathogenesis of age-related macular degeneration (AMD), diabetic retinopathy, and other neurodegenerative and neuroinflammatory disorders, but our understanding of the mechanisms behind their activation is in infant stages. With the goal of identifying novel genes associated with microglial activation in the retina, we applied a semiquantitative fundus spot scoring scale to an unbiased, state-of-the-science mouse forward genetics pipeline. A mutation in the gene encoding the E3 ubiquitin ligase Herc3 led to prominent accumulation of fundus spots. CRISPR mutagenesis was used to generate Herc3-/- mice, which developed prominent accumulation of fundus spots and corresponding activated Iba1 + /CD16 + subretinal microglia, retinal thinning on OCT and histology, and functional deficits by Optomotory and electrophysiology. Bulk RNA sequencing identified activation of inflammatory pathways and differentially expressed genes involved in the modulation of microglial activation. Thus, despite the known expression of multiple E3 ubiquitin ligases in the retina, we identified a non-redundant role for Herc3 in retinal homeostasis. Our findings are significant given that a dysregulated ubiquitin-proteasome system (UPS) is important in prevalent retinal diseases, in which activated microglia appear to play a role. This association between Herc3 deficiency, retinal microglial activation and retinal degeneration merits further study.
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Affiliation(s)
- Yeshumenesh Zegeye
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Bogale Aredo
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Seher Yuksel
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Dogan Can Kirman
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Ashwani Kumar
- McDermott Center for Human Growth and Development, UT Southwestern Medical Center, Dallas, TX, USA
| | - Bo Chen
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Emily Turpin
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sangita Shresta
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Yu-Guang He
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Laurent Gautron
- Center for Hypothalamic Research and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Miao Tang
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xiaohong Li
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Sophia M DiCesare
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - John D Hulleman
- Department of Ophthalmology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Chao Xing
- McDermott Center for Human Growth and Development, UT Southwestern Medical Center, Dallas, TX, USA
- Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sara Ludwig
- Center for Hypothalamic Research and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Eva Marie Y Moresco
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bruce A Beutler
- Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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3
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Chew LA, Iannaccone A. Gene-agnostic approaches to treating inherited retinal degenerations. Front Cell Dev Biol 2023; 11:1177838. [PMID: 37123404 PMCID: PMC10133473 DOI: 10.3389/fcell.2023.1177838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/31/2023] [Indexed: 05/02/2023] Open
Abstract
Most patients with inherited retinal degenerations (IRDs) have been waiting for treatments that are "just around the corner" for decades, with only a handful of seminal breakthroughs happening in recent years. Highlighting the difficulties in the quest for curative therapeutics, Luxturna required 16 years of development before finally obtaining United States Food and Drug Administration (FDA) approval and its international equivalents. IRDs are both genetically and phenotypically heterogeneous. While this diversity offers many opportunities for gene-by-gene precision medicine-based approaches, it also poses a significant challenge. For this reason, alternative (or parallel) strategies to identify more comprehensive, across-the-board therapeutics for the genetically and phenotypically diverse IRD patient population are very appealing. Even when gene-specific approaches may be available and become approved for use, many patients may have reached a disease stage whereby these approaches may no longer be viable. Thus, alternate visual preservation or restoration therapeutic approaches are needed at these stages. In this review, we underscore several gene-agnostic approaches that are being developed as therapeutics for IRDs. From retinal supplementation to stem cell transplantation, optogenetic therapy and retinal prosthetics, these strategies would bypass at least in part the need for treating every individual gene or mutation or provide an invaluable complement to them. By considering the diverse patient population and treatment strategies suited for different stages and patterns of retinal degeneration, gene agnostic approaches are very well poised to impact favorably outcomes and prognosis for IRD patients.
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Affiliation(s)
- Lindsey A. Chew
- Duke Center for Retinal Degenerations and Ophthalmic Genetic Diseases, Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, NC, United States
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, United States
| | - Alessandro Iannaccone
- Duke Center for Retinal Degenerations and Ophthalmic Genetic Diseases, Department of Ophthalmology, Duke Eye Center, Duke University School of Medicine, Durham, NC, United States
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Peng H, Ramadurgum P, Woodard DR, Daniel S, Nakahara E, Renwick M, Aredo B, Datta S, Chen B, Ufret-Vincenty R, Hulleman JD. Utility of the DHFR-based destabilizing domain across mouse models of retinal degeneration and aging. iScience 2022; 25:104206. [PMID: 35521529 PMCID: PMC9062244 DOI: 10.1016/j.isci.2022.104206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 02/16/2022] [Accepted: 04/04/2022] [Indexed: 11/25/2022] Open
Abstract
The Escherichia coli dihydrofolate reductase (DHFR) destabilizing domain (DD) serves as a promising approach to conditionally regulate protein abundance in a variety of tissues. To test whether this approach could be effectively applied to a wide variety of aged and disease-related ocular mouse models, we evaluated the DHFR DD system in the eyes of aged mice (up to 24 months), a light-induced retinal degeneration (LIRD) model, and two genetic models of retinal degeneration (rd2 and Abca4−/− mice). The DHFR DD was effectively degraded in all model systems, including rd2 mice, which showed significant defects in chymotrypsin proteasomal activity. Moreover, trimethoprim (TMP) administration stabilized the DHFR DD in all mouse models. Thus, the DHFR DD-based approach allows for control of protein abundance in a variety of mouse models, laying the foundation to use this strategy for the conditional control of gene therapies to potentially treat multiple eye diseases. Destabilizing domains (DDs) confer conditional control of ocular protein abundance The DHFR DD is effectively turned over and stabilized in aged mouse’s retina DHFR DDs perform well in environmental and genetic retinal degenerative models
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Ye Q, Wang J, Liu X, Liu Z, BaZong L, Ma J, Shen R, Ye W, Zhang W, Wang D. The Role of RAD6B and PEDF in Retinal Degeneration. Neuroscience 2021; 480:19-31. [PMID: 34774969 DOI: 10.1016/j.neuroscience.2021.11.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 12/11/2022]
Abstract
RAD6B is an E2 ubiquitin-conjugating enzyme, playing an important role in DNA damage repair, gene expression, senescence, apoptosis and protein degradation. However, the specific mechanism between ubiquitin and retinal degeneration requires more investigation. Pigment epithelium-derived factor (PEDF) has a potent neurotrophic effect on the retina, protecting retinal neurons and photoreceptors from cell death caused by pathological damage. In this study, we found that loss of RAD6B leads to retinal degeneration in mice, especially in old age. Affymetrix microarray analysis showed that the PEDF signal was changed in RAD6B deficient groups. The expression of γ-H2AX, β-Gal, P53, Caspase-3, P21 and P16 was increased significantly in retinas of RAD6B knockout (KO) mice. Our studies suggest that RAD6B and PEDF play an important role in the health of retina, whereas the absence of RAD6B accelerates the degeneration.
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Affiliation(s)
- Qiang Ye
- Institute of Human Anatomy and Histoembryology, Basic Medical College, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, China; Department of Ophthalmology, The Second Hospital of Lanzhou University, 82 Cuiying Door, Lanzhou 730000, China
| | - Jiaqi Wang
- Institute of Human Anatomy and Histoembryology, Basic Medical College, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, China
| | - Xiangwen Liu
- Institute of Human Anatomy and Histoembryology, Basic Medical College, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, China
| | - Zihua Liu
- Institute of Human Anatomy and Histoembryology, Basic Medical College, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, China
| | - LuoSong BaZong
- Department of Ophthalmology, The Second Hospital of Lanzhou University, 82 Cuiying Door, Lanzhou 730000, China
| | - Jinhai Ma
- Department of Ophthalmology, The Second Hospital of Lanzhou University, 82 Cuiying Door, Lanzhou 730000, China
| | - Rong Shen
- Institute of Human Anatomy and Histoembryology, Basic Medical College, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, China.
| | - Weichun Ye
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou 730000, China.
| | - Wenfang Zhang
- Department of Ophthalmology, The Second Hospital of Lanzhou University, 82 Cuiying Door, Lanzhou 730000, China.
| | - Degui Wang
- Institute of Human Anatomy and Histoembryology, Basic Medical College, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, China.
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6
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Gunawan M, Low C, Neo K, Yeo S, Ho C, Barathi VA, Chan AS, Sharif NA, Kageyama M. The Role of Autophagy in Chemical Proteasome Inhibition Model of Retinal Degeneration. Int J Mol Sci 2021; 22:ijms22147271. [PMID: 34298888 PMCID: PMC8303873 DOI: 10.3390/ijms22147271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/25/2021] [Accepted: 06/30/2021] [Indexed: 01/27/2023] Open
Abstract
We recently demonstrated that chemical proteasome inhibition induced inner retinal degeneration, supporting the pivotal roles of the ubiquitin–proteasome system in retinal structural integrity maintenance. In this study, using beclin1-heterozygous (Becn1-Het) mice with autophagic dysfunction, we tested our hypothesis that autophagy could be a compensatory retinal protective mechanism for proteasomal impairment. Despite the reduced number of autophagosome, the ocular tissue morphology and intraocular pressure were normal. Surprisingly, Becn1-Het mice experienced the same extent of retinal degeneration as was observed in wild-type mice, following an intravitreal injection of a chemical proteasome inhibitor. Similarly, these mice equally responded to other chemical insults, including endoplasmic reticulum stress inducer, N-methyl-D-aspartate, and lipopolysaccharide. Interestingly, in cultured neuroblastoma cells, we found that the mammalian target of rapamycin-independent autophagy activators, lithium chloride and rilmenidine, rescued these cells against proteasome inhibition-induced death. These results suggest that Becn1-mediated autophagy is not an effective intrinsic protective mechanism for retinal damage induced by insults, including impaired proteasomal activity; furthermore, autophagic activation beyond normal levels is required to alleviate the cytotoxic effect of proteasomal inhibition. Further studies are underway to delineate the precise roles of different forms of autophagy, and investigate the effects of their activation in rescuing retinal neurons under various pathological conditions.
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Affiliation(s)
- Merry Gunawan
- Santen-SERI Open Innovation Centre, 20 College Road, The Academia, Singapore 169856, Singapore; (M.G.); (C.L.); (K.N.)
| | - Choonbing Low
- Santen-SERI Open Innovation Centre, 20 College Road, The Academia, Singapore 169856, Singapore; (M.G.); (C.L.); (K.N.)
| | - Kurt Neo
- Santen-SERI Open Innovation Centre, 20 College Road, The Academia, Singapore 169856, Singapore; (M.G.); (C.L.); (K.N.)
| | - Siawey Yeo
- Translational Pre-Clinical Model Platform, Singapore Eye Research Institute, 20 College Road, The Academia, Singapore 169856, Singapore; (S.Y.); (V.A.B.)
| | - Candice Ho
- Singapore Eye Research Institute, 20 College Road, The Academia, Singapore 169856, Singapore; (C.H.); (A.S.C.)
| | - Veluchamy A. Barathi
- Translational Pre-Clinical Model Platform, Singapore Eye Research Institute, 20 College Road, The Academia, Singapore 169856, Singapore; (S.Y.); (V.A.B.)
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, 21 Lower Kent Ridge Road, Singapore 119077, Singapore
- Academic Clinical Program in Ophthalmology, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Anita Sookyee Chan
- Singapore Eye Research Institute, 20 College Road, The Academia, Singapore 169856, Singapore; (C.H.); (A.S.C.)
| | - Najam A. Sharif
- Global Alliance and External Research, Santen Inc., Emeryville, CA 94608, USA;
| | - Masaaki Kageyama
- Santen-SERI Open Innovation Centre, 20 College Road, The Academia, Singapore 169856, Singapore; (M.G.); (C.L.); (K.N.)
- Correspondence:
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7
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Kasahara M. Role of immunoproteasomes and thymoproteasomes in health and disease. Pathol Int 2021; 71:371-382. [PMID: 33657242 DOI: 10.1111/pin.13088] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/11/2021] [Indexed: 12/14/2022]
Abstract
The proteasome is a multisubunit protease that degrades intracellular proteins into small peptides. Besides playing a pivotal role in many cellular processes indispensable for survival, it is involved in the production of peptides presented by major histocompatibility complex class I molecules. In addition to the standard proteasome shared in all eukaryotes, jawed vertebrates have two specialized forms of proteasome known as immunoproteasomes and thymoproteasomes. The immunoproteasome, which contains cytokine-inducible catalytic subunits with distinct cleavage specificities, produces peptides presented by class I molecules more efficiently than the standard proteasome. The thymoproteasome, which contains a unique catalytic subunit β5t, is a tissue-specific proteasome expressed exclusively in cortical thymic epithelial cells. It plays a critical role in CD8+ cytotoxic T cell development via positive selection. This review provides a brief overview on the structure and function of these specialized forms of proteasome and their involvement in human disease.
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Affiliation(s)
- Masanori Kasahara
- Department of Pathology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Hokkaido, Japan
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8
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Tomaru U, Ito T, Ohmura Y, Higashikawa K, Miyajima S, Tomatsu R, Higashi T, Ishizu A, Kuge Y, Yoshioka M, Kasahara M. Decreased Proteasomal Function Induces Neuronal Loss and Memory Impairment. THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:144-156. [PMID: 33339546 DOI: 10.1016/j.ajpath.2020.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 09/20/2020] [Accepted: 10/06/2020] [Indexed: 12/31/2022]
Abstract
Alzheimer disease (AD) is a progressive neurodegenerative disorder and the most common type of dementia worldwide. There is considerable evidence of age-related disruption of proteostasis being responsible for the development of AD. The proteasome is a multicatalytic enzyme complex that degrades both normal and damaged proteins, and an age-related decline in its activity has been implicated in age-related pathologies. Although proteasomal dysfunction is assumed to be a key AD hallmark, it remains unclear whether its role in disease onset is causative or secondary. In this study, we demonstrate that mice with proteasomal dysfunction exhibited memory impairment with associated neuronal loss, accumulation of phosphorylated tau, and activation of endoplasmic reticulum (ER) stress-related apoptosis pathways. Impaired proteasomal activity also activated ER stress-related apoptosis pathways in HT-22, a murine hippocampal neuronal cell line. HT-22 cell death, caused by proteasomal inhibition, was prevented by an inhibitor of c-Jun N-terminal kinase, an ER stress-related molecule. Collective evidence suggests that impaired proteasomal activity alters proteostasis, and subsequent ER stress-mediated pathways play pivotal roles in neuronal loss. Because aging decreases proteasomal function, age-related impairment of proteasomes may be involved in the development and progression of AD in elderly patients.
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Affiliation(s)
- Utano Tomaru
- Department of Pathology, Hokkaido University, Sapporo, Japan.
| | - Tomoki Ito
- Department of Pathology, Hokkaido University, Sapporo, Japan
| | - Yu Ohmura
- Department of Neuropharmacology, Hokkaido University, Sapporo, Japan
| | - Kei Higashikawa
- Central Institute of Isotope Science, Hokkaido University, Sapporo, Japan
| | - Syota Miyajima
- Department of Pathology, Hokkaido University, Sapporo, Japan
| | - Ruka Tomatsu
- Department of Pathology, Hokkaido University, Sapporo, Japan
| | - Tsunehito Higashi
- Department of Cellular Pharmacology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Akihiro Ishizu
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Yuji Kuge
- Central Institute of Isotope Science, Hokkaido University, Sapporo, Japan
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Xu H, Enemchukwu N, Zhong X, Zhang O, Fu Y. Deletion of M-Opsin Prevents M Cone Degeneration in a Mouse Model of Leber Congenital Amaurosis. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:1059-1067. [PMID: 32084365 PMCID: PMC7237827 DOI: 10.1016/j.ajpath.2020.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/24/2019] [Accepted: 01/07/2020] [Indexed: 12/15/2022]
Abstract
Mutations in retinoid isomerase (RPE65) or lecithin-retinol acyltransferase (LRAT) disrupt 11-cis-retinal synthesis and cause Leber congenital amaurosis (LCA). Despite the success of recent RPE65 gene therapy, follow-up studies show that patients continue to experience photoreceptor degeneration and lose vision benefit over time. In Lrat-/- mouse model, mislocalized medium (M)-wavelength opsin was degraded, whereas mislocalized short (S)-wavelength opsin accumulated before the onset of cone degeneration. The mechanism for the foveal M/long-wavelength cone photoreceptor degeneration in LCA is unknown. By crossing Lrat-/- mice with a proteasome reporter mouse strain, this study showed that M-opsin-enriched dorsal cones in Lrat-/- mice exhibit proteasome stress because of the degradation of large amounts of M-opsin. Deletion of M-opsin relieves the proteasome stress and completely prevents M cone degeneration in Lrat-/-Opn1sw-/- mice (a pure M cone LCA model, Opn1sw encoding S-opsin) for at least 12 months. These results suggest that M-opsin degradation-associated proteasome stress plays a major role in M cone degeneration in Lrat-/- model. This finding may represent a general mechanism for M cone degeneration in multiple forms of cone degeneration because of M-opsin mislocalization and degradation. These results have important implications for the current gene therapy strategy for LCA that emphasizes the need for combinatorial therapies to both improve vision and slow photoreceptor degeneration.
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Affiliation(s)
- Hui Xu
- Interdepartmental Program in Neuroscience, Department of Ophthalmology, University of Utah, Salt Lake City, Utah; Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas; Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Nduka Enemchukwu
- Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas; Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Xiaoyue Zhong
- Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas; Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas; Rice University, Houston, Texas
| | - Olivia Zhang
- Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas; Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas; Rice University, Houston, Texas
| | - Yingbin Fu
- Interdepartmental Program in Neuroscience, Department of Ophthalmology, University of Utah, Salt Lake City, Utah; Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas; Departments of Ophthalmology and Neuroscience, Baylor College of Medicine, Houston, Texas.
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10
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Probing Proteostatic Stress in Degenerating Photoreceptors Using Two Complementary In Vivo Reporters of Proteasomal Activity. eNeuro 2019; 7:ENEURO.0428-19.2019. [PMID: 31826915 PMCID: PMC6948925 DOI: 10.1523/eneuro.0428-19.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/02/2019] [Accepted: 12/04/2019] [Indexed: 12/01/2022] Open
Abstract
Inherited retinal degenerations originate from mutations in >300 genes, many of which cause the production of misfolded mutant photoreceptor proteins that are ultimately degraded by the ubiquitin-proteasome system (UPS). It was previously shown that rod photoreceptors in multiple mouse models of retinal degeneration suffer from proteostatic stress consisting of an insufficient cellular capacity for degrading UPS substrates. In this study, we focused on a specific UPS component required for the degradation of a subset of proteasome targets: the substrate-processing complex formed by the AAA+ ATPase P97/VCP and associated cofactors. To assess whether P97 capacity may be insufficient in degenerating rods, we employed two complementary in vivo proteasomal activity reporters whose degradation is either P97-dependent or P97-independent. Retinal accumulation of each reporter was measured in two models of retinal degeneration: the transducin γ-subunit knock-out (Gγ1-/-) and P23H rhodopsin knock-in (P23H) mice. Strikingly, the patterns of reporter accumulation differed between these models, indicating that the proteostatic stress observed in Gγ1-/- and P23H rods likely originates from different pathobiological mechanisms, in which UPS substrate degradation may or may not be limited by P97-dependent substrate processing. Further, we assessed whether P97 overexpression could ameliorate pathology in Gγ1-/- mice, in which proteostatic stress appears to result from P97 insufficiency. However, despite P97 overexpression being aphenotypic in other tissues, the ∼2.4-fold increase in retinal P97 content was toxic to rods, which complicated the interpretation of the observed phenotype. Our results highlight the complexity of pathophysiological mechanisms related to degrading misfolded proteins in mutant photoreceptors.
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11
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Kageyama M, Ota T, Sasaoka M, Katsuta O, Shinomiya K. Chemical proteasome inhibition as a novel animal model of inner retinal degeneration in rats. PLoS One 2019; 14:e0217945. [PMID: 31150519 PMCID: PMC6544319 DOI: 10.1371/journal.pone.0217945] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 05/21/2019] [Indexed: 12/14/2022] Open
Abstract
Chemical proteasome inhibition has been a valuable animal model of neurodegeneration to uncover roles for the ubiquitin-proteasome system in the central nervous system. However, little is known about the effects of chemical proteasome inhibitors on retinal integrity. Therefore, we characterized the effects of structurally different chemical proteasome inhibitors on the retinal morphology and the mechanisms of their action in the normal adult rat eyes. Intravitreal injection of MG-262 and other proteasome inhibitors led to inner retinal degeneration. MG-262-induced inner retinal degeneration was accompanied by reduced proteasome activity, increased poly-ubiquitinated protein levels, and increased positive immunostaining of ubiquitin, 20S proteasome subunit and GADD153/CHOP in the retina. Its retinal degenerative effect was also associated with reduced retinal neurofilament light chain gene expression, reflecting retinal ganglion cell death. MG-262-induced neurofilament light chain downregulation was largely resistant to pharmacological modulation including endoplasmic reticulum stress, apoptosis or MAP kinase inhibitors. Thus, this study provides further evidence of roles for the ubiquitin-proteasome system in the maintenance of the retinal structural integrity. Chemical proteasome inhibition may be used as a novel animal model of inner retinal degeneration, including retinal ganglion cell loss, which warrants further analysis of the molecular mechanisms underlying its retinal degenerative effect.
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Affiliation(s)
- Masaaki Kageyama
- Global Alliances and External Research, Santen Pharmaceutical Co., Ltd., Nara, Japan
- * E-mail:
| | - Takashi Ota
- Global Alliances and External Research, Santen Pharmaceutical Co., Ltd., Nara, Japan
| | - Masaaki Sasaoka
- Global Alliances and External Research, Santen Pharmaceutical Co., Ltd., Nara, Japan
| | - Osamu Katsuta
- Research and Development Center, Santen Pharmaceutical Co., Ltd., Nara, Japan
| | - Katsuhiko Shinomiya
- Research and Development Center, Santen Pharmaceutical Co., Ltd., Nara, Japan
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Interplay between Autophagy and the Ubiquitin-Proteasome System and Its Role in the Pathogenesis of Age-Related Macular Degeneration. Int J Mol Sci 2019; 20:ijms20010210. [PMID: 30626110 PMCID: PMC6337628 DOI: 10.3390/ijms20010210] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 12/21/2018] [Accepted: 01/02/2019] [Indexed: 12/20/2022] Open
Abstract
Age-related macular degeneration (AMD) is a complex eye disease with many pathogenesis factors, including defective cellular waste management in retinal pigment epithelium (RPE). Main cellular waste in AMD are: all-trans retinal, drusen and lipofuscin, containing unfolded, damaged and unneeded proteins, which are degraded and recycled in RPE cells by two main machineries—the ubiquitin-proteasome system (UPS) and autophagy. Recent findings show that these systems can act together with a significant role of the EI24 (etoposide-induced protein 2.4 homolog) ubiquitin ligase in their action. On the other hand, E3 ligases are essential in both systems, but E3 is degraded by autophagy. The interplay between UPS and autophagy was targeted in several diseases, including Alzheimer disease. Therefore, cellular waste clearing in AMD should be considered in the context of such interplay rather than either of these systems singly. Aging and oxidative stress, two major AMD risk factors, reduce both UPS and autophagy. In conclusion, molecular mechanisms of UPS and autophagy can be considered as a target in AMD prevention and therapeutic perspective. Further work is needed to identify molecules and effects important for the coordination of action of these two cellular waste management systems.
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Increased proteasomal activity supports photoreceptor survival in inherited retinal degeneration. Nat Commun 2018; 9:1738. [PMID: 29712894 PMCID: PMC5928105 DOI: 10.1038/s41467-018-04117-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 04/04/2018] [Indexed: 12/14/2022] Open
Abstract
Inherited retinal degenerations, affecting more than 2 million people worldwide, are caused by mutations in over 200 genes. This suggests that the most efficient therapeutic strategies would be mutation independent, i.e., targeting common pathological conditions arising from many disease-causing mutations. Previous studies revealed that one such condition is an insufficiency of the ubiquitin–proteasome system to process misfolded or mistargeted proteins in affected photoreceptor cells. We now report that retinal degeneration in mice can be significantly delayed by increasing photoreceptor proteasomal activity. The largest effect is observed upon overexpression of the 11S proteasome cap subunit, PA28α, which enhanced ubiquitin-independent protein degradation in photoreceptors. Applying this strategy to mice bearing one copy of the P23H rhodopsin mutant, a mutation frequently encountered in human patients, quadruples the number of surviving photoreceptors in the inferior retina of 6-month-old mice. This striking therapeutic effect demonstrates that proteasomes are an attractive target for fighting inherited blindness. Proteasomal overload can be found in a broad spectrum of mouse models of retinal degeneration. Here the authors find that overexpressing the PA28α subunit of the 11S proteasome cap increased the number of surviving functional photoreceptor cells in a mouse model of retinal degeneration bearing the P23H mutation in rhodopsin.
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Shruthi K, Reddy SS, Reddy GB. Ubiquitin-proteasome system and ER stress in the retina of diabetic rats. Arch Biochem Biophys 2017; 627:10-20. [PMID: 28606465 DOI: 10.1016/j.abb.2017.06.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/02/2017] [Accepted: 06/08/2017] [Indexed: 12/29/2022]
Abstract
PURPOSE Diabetic retinopathy (DR) is the most frequently occurring complication of diabetes. Alterations in ubiquitin-proteasome system (UPS) have been associated with several degenerative disorders. Hence, in this study, we investigated the status and role of UPS and ER stress in the retina of diabetic rats. METHODS Diabetes was induced in rats by streptozotocin. Retinal markers, ER stress markers, components of UPS, ERAD, and autophagy were analyzed after 2- and 4-months of diabetes. Apoptosis was analyzed by TUNEL Assay. RESULTS There were increased acellular capillaries and pericyte loss in diabetic rat retina. Decreased protein expression of UPS components - ubiquitin activating enzyme (E1), deubiquitinating enzymes (UCHL1 and UCHL5), SIAH1 (E3 ligase) and free ubiquitin were observed in the diabetic rats. Increased ER stress markers (ATF6, XBP1, and CHOP), decreased expression of HRD1, declined autophagy (LC3B) and increased apoptosis were observed in diabetic rats. Interestingly, treatment of diabetic rats with a chemical chaperone (4-PBA) restored the levels of DUBs and ameliorated ER stress-induced retinal cell death in type 1 diabetic rats. CONCLUSION The declined UPS components: E1 and HRD1 in the retina of diabetic rats could elicit ER stress, and the prolonged ER stress may trigger CHOP-mediated neuronal apoptosis.
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Affiliation(s)
- Karnam Shruthi
- Biochemistry Division, National Institute of Nutrition, Hyderabad, India
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Abstract
The review intends to draw the attention of researchers working in retinal degenerations on the fact that classical apoptosis, for example, apoptosis triggering caspase activation, may not be the main pathway of cellular demise in this tissue.Former work already showed the difficulty of proving the activation of apoptosis effectors in different models of retinal degeneration. However, these results were not really considered because of the lack of an alternative explanation for cell death. Nowadays, the description of many pathways of cellular demise is filling the gap and other forms of cell death are now described in the retina.The knowledge on the molecular mechanisms of cell death is very important for the development of new therapeutic strategies, as well as for the evaluation of cell death onset in retinal degeneration.
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16
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Li S, Hu J, Jin RJ, Aiyar A, Jacobson SG, Bok D, Jin M. Temperature-sensitive retinoid isomerase activity of RPE65 mutants associated with Leber Congenital Amaurosis. J Biochem 2015; 158:115-25. [PMID: 25752820 DOI: 10.1093/jb/mvv028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 01/26/2015] [Indexed: 12/22/2022] Open
Abstract
RPE65 is a membrane-associated retinoid isomerase involved in the visual cycle responsible for sustaining vision. Many mutations in the human RPE65 gene are associated with distinct forms of retinal degenerative diseases. The pathogenic mechanisms for most of these mutations remain poorly understood. Here, we show that three Leber congenital amaurosis -associated RPE65 mutants (R91W, Y249C and R515W) undergo rapid proteasomal degradation mediated by the 26 S proteasome non-ATPase regulatory subunit 13 (PSMD13) in cultured human retinal pigment epithelium (RPE) cells. These mutant proteins formed cytosolic inclusion bodies or high molecular weight complexes via disulfide bonds. The mutations are mapped on non-active sites but severely reduced isomerase activity of RPE65. At 30°C, however, the enzymatic function and membrane-association of the mutant RPE65s are significantly rescued possibly due to proper folding. In addition, PSMD13 displayed a drastically decreased effect on degradation of the mutant proteins in the cells grown at 30°C. These results suggest that PSMD13 plays a critical role in regulating pathogenicity of the mutations and the molecular basis for the PSMD13-mediated rapid degradation and loss of function of the mutants is misfolding of RPE65.
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Affiliation(s)
- Songhua Li
- Department of Ophthalmology and Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112 USA
| | - Jane Hu
- Jules Stein Eye Institute and Department of Neurobiology, University of California, Los Angeles, CA 90095 USA
| | - Robin J Jin
- State University of New York at Buffalo, Buffalo, NY 14214 USA
| | - Ashok Aiyar
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112 USA; and
| | - Samuel G Jacobson
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Dean Bok
- Jules Stein Eye Institute and Department of Neurobiology, University of California, Los Angeles, CA 90095 USA
| | - Minghao Jin
- Department of Ophthalmology and Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112 USA;
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