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Yanardag S, Rhodes S, Saravanan T, Guan T, Ramamurthy V. Prominin 1 is crucial for the early development of photoreceptor outer segments. Sci Rep 2024; 14:10498. [PMID: 38714794 PMCID: PMC11076519 DOI: 10.1038/s41598-024-60989-5] [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: 03/12/2024] [Accepted: 04/30/2024] [Indexed: 05/10/2024] Open
Abstract
Prominin 1 (PROM1) is a pentaspan transmembrane glycoprotein localized on the nascent photoreceptor discs. Mutations in PROM1 are linked to various retinal diseases. In this study, we assessed the role of PROM1 in photoreceptor biology and physiology using the PROM1 knockout murine model (rd19). Our study found that PROM1 is essential for vision and photoreceptor development. We found an early reduction in photoreceptor response beginning at post-natal day 12 (P12) before eye opening in the absence of PROM1 with no apparent loss in photoreceptor cells. However, at this stage, we observed an increased glial cell activation, indicative of cell damage. Contrary to our expectations, dark rearing did not mitigate photoreceptor degeneration or vision loss in PROM1 knockout mice. In addition to physiological defects seen in PROM1 knockout mice, ultrastructural analysis revealed malformed outer segments characterized by whorl-like continuous membranes instead of stacked disks. In parallel to the reduced rod response at P12, proteomics revealed a significant reduction in the levels of protocadherin, a known interactor of PROM1, and rod photoreceptor outer segment proteins, including rhodopsin. Overall, our results underscore the indispensable role of PROM1 in photoreceptor development and maintenance of healthy vision.
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Affiliation(s)
- Sila Yanardag
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
| | - Scott Rhodes
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Thamaraiselvi Saravanan
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Tongju Guan
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Visvanathan Ramamurthy
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA.
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA.
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2
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Goswami MT, Weh E, Subramanya S, Weh KM, Durumutla HB, Hager H, Miller N, Chaudhury S, Andren A, Sajjakulnukit P, Besirli CG, Lyssiotis CA, Wubben TJ. Glutaminase deficiency in rod photoreceptors disrupts nonessential amino acid levels to activate the integrated stress response and induce rapid degeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.26.582525. [PMID: 38586045 PMCID: PMC10996599 DOI: 10.1101/2024.03.26.582525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The bioenergetic demand of photoreceptors rivals that of cancer cells, and numerous metabolic similarities exist between these cells. Glutamine (Gln) anaplerosis via the tricarboxylic acid (TCA) cycle provides biosynthetic intermediates and is a hallmark of cancer metabolism. In this process, Gln is first converted to glutamate via glutaminase (GLS), which is a crucial pathway in many cancer cells. To date, no study has been undertaken to examine the role of Gln metabolism in vivo in photoreceptors. Here, mice lacking GLS in rod photoreceptors were generated. Animals lacking GLS experienced rapid photoreceptor degeneration with concomitant functional loss. Gln has multiple roles in metabolism including redox balance, biosynthesis of nucleotides and amino acids, and supplementing the TCA cycle. Few alterations were noted in redox balance. Unlabeled targeted metabolomics demonstrated few changes in glycolytic and TCA cycle intermediates, which corresponded with a lack of significant changes in mitochondrial function. GLS deficiency in rod photoreceptors did decrease the fractional labelling of TCA cycle intermediates when provided uniformly labeled 13C-Gln in vivo. However, supplementation with alpha-ketoglutarate provided only marginal rescue of photoreceptor degeneration. Nonessential amino acids, glutamate and aspartate, were decreased in the retina of mice lacking GLS in rod photoreceptors. In accordance with this amino acid deprivation, the integrated stress response (ISR) was found to be activated with decreased global protein synthesis. Importantly, supplementation with asparagine delayed photoreceptor degeneration to a greater degree than alpha-ketoglutarate. These data show that GLS-mediated Gln catabolism is essential for rod photoreceptor amino acid biosynthesis, function, and survival.
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Affiliation(s)
- Moloy T. Goswami
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Eric Weh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Shubha Subramanya
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Katherine M. Weh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Hima Bindu Durumutla
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
- Molecular and Developmental Biology Graduate Program, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Heather Hager
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Nicholas Miller
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Sraboni Chaudhury
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Anthony Andren
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109
| | - Peter Sajjakulnukit
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109
| | - Cagri G. Besirli
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Costas A. Lyssiotis
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of Michigan, Ann Arbor, MI 48109
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109
| | - Thomas J. Wubben
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
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Subramanya S, Goswami MT, Miller N, Weh E, Chaudhury S, Zhang L, Andren A, Hager H, Weh KM, Lyssiotis CA, Besirli CG, Wubben TJ. Rod photoreceptor-specific deletion of cytosolic aspartate aminotransferase, GOT1, causes retinal degeneration. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1306019. [PMID: 38725581 PMCID: PMC11081273 DOI: 10.3389/fopht.2023.1306019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/12/2024]
Abstract
Photoreceptor cell death is the cause of vision loss in many forms of retinal disease. Metabolic dysfunction within the outer retina has been shown to be an underlying factor contributing to photoreceptor loss. Therefore, a comprehensive understanding of the metabolic pathways essential to photoreceptor health and function is key to identifying novel neuroprotective strategies. Glutamic-oxaloacetic transaminase 1 (Got1) encodes for a cytosolic aspartate aminotransferase that reversibly catalyzes the transfer of an amino group between glutamate and aspartate and is an important aspect of the malate-aspartate shuttle (MAS), which transfers reducing equivalents from the cytosol to the mitochondrial matrix. Previous work has demonstrated that the activity of this enzyme is highest in photoreceptor inner segments. Furthermore, ex vivo studies have demonstrated that the retina relies on aspartate aminotransferase for amino acid metabolism. Importantly, aspartate aminotransferase has been suggested to be an early biomarker of retinal degeneration in retinitis pigmentosa and a possible target for neuroprotection. In the present study, we characterized the effect of Got1 deletion on photoreceptor metabolism, function, and survival in vivo by using a rod photoreceptor-specific, Got1 knockout mouse model. Loss of the GOT1 enzyme from rod photoreceptors resulted in age-related photoreceptor degeneration with an accumulation of retinal aspartate and NADH and alterations in the expression of genes involved in the MAS, the tricarboxylic acid (TCA) cycle, and redox balance. Hence, GOT1 is critical to in vivo photoreceptor metabolism, function, and survival.
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Affiliation(s)
- Shubha Subramanya
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Moloy T. Goswami
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Nicholas Miller
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Eric Weh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Sraboni Chaudhury
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Li Zhang
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Anthony Andren
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Heather Hager
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Katherine M. Weh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Costas A. Lyssiotis
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI, United States
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of Michigan, Ann Arbor, MI, United States
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI, United States
| | - Cagri G. Besirli
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
| | - Thomas J. Wubben
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
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4
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Xia CH, Liu H, Li M, Zhang H, Xing X, Gong X. Identification and Characterization of Retinitis Pigmentosa in a Novel Mouse Model Caused by PDE6B-T592I. Biomedicines 2023; 11:3173. [PMID: 38137394 PMCID: PMC10740990 DOI: 10.3390/biomedicines11123173] [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: 10/28/2023] [Revised: 11/24/2023] [Accepted: 11/27/2023] [Indexed: 12/24/2023] Open
Abstract
The cGMP-phosphodiesterase 6 beta subunit (PDE6B) is an essential component in the phototransduction pathway for light responses in photoreceptor cells. PDE6B gene mutations cause the death of rod photoreceptors, named as hereditary retinitis pigmentosa (RP) in humans and retinal degeneration (RD) in rodents. Here, we report a new RD model, identified from a phenotypic screen of N-ethyl-N-nitrosourea (ENU)-induced mutant mice, which displays retinal degeneration caused by a point mutation in the Pde6b gene that results in PDE6B-T592I mutant protein. The homozygous mutant mice show an extensive loss of rod photoreceptors at the age of 3 weeks; unexpectedly, the loss of rod photoreceptors can be partly rescued by dark rearing. Thus, this RD mutant model displays a light-dependent loss of rod photoreceptors. Both western blot and immunostaining results show very low level of mutant PDE6B-T592I protein in the retina. Structure modeling suggests that the T592I mutation probably affects the function and stability of PDE6B protein by changing intramolecular interactions. We further demonstrate that the expression of wild-type PDE6B delivered by subretinally injected adeno-associated virus (rAAV) prevents photoreceptor cell death in this RD model in vivo. The PDE6B-T592I mutant is, therefore, a valuable RD model for evaluating rAAV-mediated treatment and for investigating the molecular mechanism of light-dependent rod photoreceptor cell death that is related to impaired PDE6B function.
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Affiliation(s)
| | | | | | | | | | - Xiaohua Gong
- Herbert Wertheim School of Optometry and Vision Science Program, University of California, Berkeley, CA 94720, USA; (C.-H.X.); (H.L.); (M.L.); (H.Z.); (X.X.)
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5
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Wu Y, Wan X, Zhao D, Chen X, Wang Y, Tang X, Li J, Li S, Sun X, Bi C, Zhang X. AAV-mediated base-editing therapy ameliorates the disease phenotypes in a mouse model of retinitis pigmentosa. Nat Commun 2023; 14:4923. [PMID: 37582961 PMCID: PMC10427680 DOI: 10.1038/s41467-023-40655-6] [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: 10/08/2022] [Accepted: 08/07/2023] [Indexed: 08/17/2023] Open
Abstract
Base editing technology is an ideal solution for treating pathogenic single-nucleotide variations (SNVs). No gene editing therapy has yet been approved for eye diseases, such as retinitis pigmentosa (RP). Here, we show, in the rd10 mouse model, which carries an SNV identified as an RP-causing mutation in human patients, that subretinal delivery of an optimized dual adeno-associated virus system containing the adenine base editor corrects the pathogenic SNV in the neuroretina with up to 49% efficiency. Light microscopy showed that a thick and robust outer nuclear layer (photoreceptors) was preserved in the treated area compared with the thin, degenerated outer nuclear layer without treatment. Substantial electroretinogram signals were detected in treated rd10 eyes, whereas control treated eyes showed minimal signals. The water maze experiment showed that the treatment substantially improved vision-guided behavior. Together, we construct and validate a translational therapeutic solution for the treatment of RP in humans. Our findings might accelerate the development of base-editing based gene therapies.
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Affiliation(s)
- Yidong Wu
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- National Clinical Research Center for Eye Diseases, Shanghai, China
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai, China
| | - Xiaoling Wan
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- National Clinical Research Center for Eye Diseases, Shanghai, China.
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai, China.
| | - Dongdong Zhao
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, China
| | - Xuxu Chen
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, China
| | - Yujie Wang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, China
| | - Xinxin Tang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, China
| | - Ju Li
- College of Life Science, Tianjin Normal University, Tianjin, China
| | - Siwei Li
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- National Technology Innovation Center of Synthetic Biology, Tianjin, China
| | - Xiaodong Sun
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
- National Clinical Research Center for Eye Diseases, Shanghai, China.
- Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai, China.
| | - Changhao Bi
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, China.
| | - Xueli Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China.
- National Technology Innovation Center of Synthetic Biology, Tianjin, China.
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6
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Weh E, Goswami M, Chaudhury S, Fernando R, Miller N, Hager H, Sheskey S, Sharma V, Wubben TJ, Besirli CG. Metabolic Alterations Caused by Simultaneous Loss of HK2 and PKM2 Leads to Photoreceptor Dysfunction and Degeneration. Cells 2023; 12:2043. [PMID: 37626853 PMCID: PMC10453858 DOI: 10.3390/cells12162043] [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: 06/20/2023] [Revised: 08/04/2023] [Accepted: 08/08/2023] [Indexed: 08/27/2023] Open
Abstract
HK2 and PKM2 are two main regulators of aerobic glycolysis. Photoreceptors (PRs) use aerobic glycolysis to produce the biomass necessary for the daily renewal of their outer segments. Previous work has shown that HK2 and PKM2 are important for the normal function and long-term survival of PRs but are dispensable for PR maturation, and their individual loss has opposing effects on PR survival during acute nutrient deprivation. We generated double conditional (dcKO) mice lacking HK2 and PKM2 expression in rod PRs. Western blotting, immunofluorescence, optical coherence tomography, and electroretinography were used to characterize the phenotype of dcKO animals. Targeted and stable isotope tracing metabolomics, qRT-PCR, and retinal oxygen consumption were performed. We show that dcKO animals displayed early shortening of PR inner/outer segments, followed by loss of PRs with aging, much more rapidly than either knockout alone without functional loss as measured by ERG. Significant alterations to central glucose metabolism were observed without any apparent changes to mitochondrial function, prior to PR degeneration. Finally, PR survival following experimental retinal detachment was unchanged in dcKO animals as compared to wild-type animals. These data suggest that HK2 and PKM2 have differing roles in promoting PR neuroprotection and identifying them has important implications for developing therapeutic options for combating PR loss during retinal disease.
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Affiliation(s)
- Eric Weh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA; (M.G.); (S.C.); (R.F.); (N.M.); (H.H.); (S.S.); (V.S.); (T.J.W.)
| | | | | | | | | | | | | | | | | | - Cagri G. Besirli
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA; (M.G.); (S.C.); (R.F.); (N.M.); (H.H.); (S.S.); (V.S.); (T.J.W.)
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7
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Munezero D, Aliff H, Salido E, Saravanan T, Sanzhaeva U, Guan T, Ramamurthy V. HSP90α is needed for the survival of rod photoreceptors and regulates the expression of rod PDE6 subunits. J Biol Chem 2023; 299:104809. [PMID: 37172722 PMCID: PMC10250166 DOI: 10.1016/j.jbc.2023.104809] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 04/19/2023] [Accepted: 04/20/2023] [Indexed: 05/15/2023] Open
Abstract
Heat shock protein 90 (HSP90) is an abundant molecular chaperone that regulates the stability of a small set of proteins essential in various cellular pathways. Cytosolic HSP90 has two closely related paralogs: HSP90α and HSP90β. Due to the structural and sequence similarities of cytosolic HSP90 paralogs, identifying the unique functions and substrates in the cell remains challenging. In this article, we assessed the role of HSP90α in the retina using a novel HSP90α murine knockout model. Our findings show that HSP90α is essential for rod photoreceptor function but was dispensable in cone photoreceptors. In the absence of HSP90α, photoreceptors developed normally. We observed rod dysfunction in HSP90α knockout at 2 months with the accumulation of vacuolar structures, apoptotic nuclei, and abnormalities in the outer segments. The decline in rod function was accompanied by progressive degeneration of rod photoreceptors that was complete at 6 months. The deterioration in cone function and health was a "bystander effect" that followed the degeneration of rods. Tandem mass tag proteomics showed that HSP90α regulates the expression levels of <1% of the retinal proteome. More importantly, HSP90α was vital in maintaining rod PDE6 and AIPL1 cochaperone levels in rod photoreceptor cells. Interestingly, cone PDE6 levels were unaffected. The robust expression of HSP90β paralog in cones likely compensates for the loss of HSP90α. Overall, our study demonstrated the critical need for HSP90α chaperone in the maintenance of rod photoreceptors and showed potential substrates regulated by HSP90α in the retina.
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Affiliation(s)
- Daniella Munezero
- Department of Pharmaceutical and Pharmacological Sciences, West Virginia University, Morgantown, West Virginia, USA; Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA
| | - Hunter Aliff
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Ezequiel Salido
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Thamaraiselvi Saravanan
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Urikhan Sanzhaeva
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Tongju Guan
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Visvanathan Ramamurthy
- Department of Pharmaceutical and Pharmacological Sciences, West Virginia University, Morgantown, West Virginia, USA; Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA.
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