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Wen Y, Chen X, Feng H, Wang X, Kang X, Zhao P, Zhao C, Wei Y. Kdm6a deficiency in microglia/macrophages epigenetically silences Lcn2 expression and reduces photoreceptor dysfunction in diabetic retinopathy. Metabolism 2022; 136:155293. [PMID: 35995279 DOI: 10.1016/j.metabol.2022.155293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 11/26/2022]
Abstract
Diabetic retinopathy (DR) is one of the leading causes of severe visual impairment worldwide. However, the role of adaptive immune inflammation driven by microglia/macrophages in DR is not yet well elucidated. Kdm6a is a histone demethylase that removes the trimethyl groups of histones H3K27 and plays important biological roles in activating target genes. To elucidate the role of Kdm6a in microglia/macrophages in diabetic retinas, we established diabetic animal models with conditional knockout mice to investigate the impacts of Kdm6a deficiency. The RNA-seq analysis, mass spectrum examination, immunohistochemistry and detection of enzyme activities were used to elucidate the effect of Kdm6a deletion on gene transcription in microglia/macrophages. The expression of Kdm6a was increased in the retinas of diabetic mice compared to the control group. Loss of Kdm6a in microglia/macrophages ameliorated the diabetes-induced retinal thickness decrease, inflammation, and visual impairment. Kdm6a in microglia/macrophages regulated Lcn2 expression in a demethylase activity-dependent manner and inhibited glycolysis progression in photoreceptor cells through Lcn2. These results suggest that Kdm6a in microglia/macrophages aggravated diabetic retinopathy by promoting the expression of Lcn2 and impairing glycolysis progression in photoreceptor cells.
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Affiliation(s)
- Yanjun Wen
- Department of Ophthalmology, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China; Department of Ophthalmology, Shanghai Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai 200032, China
| | - Xin Chen
- Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China; National Clinical Research Center for Oral Disease, Shanghai, 200011, China; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, 200011, China
| | - Huazhang Feng
- Department of Ophthalmology, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China; Department of Ophthalmology, Shanghai Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China
| | - Xu Wang
- Department of Oral and Maxillofacial-Head and Neck Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China; National Clinical Research Center for Oral Disease, Shanghai, 200011, China; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai, 200011, China
| | - Xiaoli Kang
- Department of Ophthalmology, Shanghai Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China
| | - Peiquan Zhao
- Department of Ophthalmology, Shanghai Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China
| | - Chen Zhao
- Department of Ophthalmology, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai 200032, China
| | - Yan Wei
- Department of Ophthalmology, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai 200032, China.
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2
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Zeng S, Zhang T, Madigan MC, Fernando N, Aggio-Bruce R, Zhou F, Pierce M, Chen Y, Huang L, Natoli R, Gillies MC, Zhu L. Interphotoreceptor Retinoid-Binding Protein (IRBP) in Retinal Health and Disease. Front Cell Neurosci 2020; 14:577935. [PMID: 33328889 PMCID: PMC7710524 DOI: 10.3389/fncel.2020.577935] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/21/2020] [Indexed: 02/05/2023] Open
Abstract
Interphotoreceptor retinoid-binding protein (IRBP), also known as retinol binding protein 3 (RBP3), is a lipophilic glycoprotein specifically secreted by photoreceptors. Enriched in the interphotoreceptor matrix (IPM) and recycled by the retinal pigment epithelium (RPE), IRBP is essential for the vision of all vertebrates as it facilitates the transfer of retinoids in the visual cycle. It also helps to transport lipids between the RPE and photoreceptors. The thiol-dependent antioxidant activity of IRBP maintains the delicate redox balance in the normal retina. Thus, its dysfunction is suspected to play a role in many retinal diseases. We have reviewed here the latest research on IRBP in both retinal health and disease, including the function and regulation of IRBP under retinal stress in both animal models and the human retina. We have also explored the therapeutic potential of targeting IRBP in retinal diseases. Although some technical barriers remain, it is possible that manipulating the expression of IRBP in the retina will rescue or prevent photoreceptor degeneration in many retinal diseases.
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Affiliation(s)
- Shaoxue Zeng
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Ting Zhang
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
| | - Michele C Madigan
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,School of Optometry and Vision Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Nilisha Fernando
- The John Curtin School of Medical Research, The Australian National University, Acton, ACT, Australia
| | - Riemke Aggio-Bruce
- The John Curtin School of Medical Research, The Australian National University, Acton, ACT, Australia.,The Australian National University Medical School, The Australian National University, Acton, ACT, Australia
| | - Fanfan Zhou
- Sydney Pharmacy School, The University of Sydney, Sydney, NSW, Australia
| | - Matthew Pierce
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
| | - Yingying Chen
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Lianlin Huang
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia.,School of Optometry and Vision Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Riccardo Natoli
- The John Curtin School of Medical Research, The Australian National University, Acton, ACT, Australia.,The Australian National University Medical School, The Australian National University, Acton, ACT, Australia
| | - Mark C Gillies
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
| | - Ling Zhu
- Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
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Selective knockdown of hexokinase 2 in rods leads to age-related photoreceptor degeneration and retinal metabolic remodeling. Cell Death Dis 2020; 11:885. [PMID: 33082308 PMCID: PMC7576789 DOI: 10.1038/s41419-020-03103-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022]
Abstract
Photoreceptors, the primary site of phototransduction in the retina, require energy and metabolites to constantly renew their outer segments. They preferentially consume most glucose through aerobic glycolysis despite possessing abundant mitochondria and enzymes for oxidative phosphorylation (OXPHOS). Exactly how photoreceptors balance aerobic glycolysis and mitochondrial OXPHOS to regulate their survival is still unclear. We crossed rhodopsin-Cre mice with hexokinase 2 (HK2)-floxed mice to study the effect of knocking down HK2, the first rate-limiting enzyme in glycolysis, on retinal health and metabolic remodeling. Immunohistochemistry and Western blots were performed to study changes in photoreceptor-specific proteins and key enzymes in glycolysis and the tricarboxylic acid (TCA) cycle. Changes in retinal structure and function were studied by optical coherence tomography and electroretinography. Mass spectrometry was performed to profile changes in 13C-glucose-derived metabolites in glycolysis and the TCA cycle. We found that knocking down HK2 in rods led to age-related photoreceptor degeneration, evidenced by reduced expression of photoreceptor-specific proteins, age-related reductions of the outer nuclear layer, photoreceptor inner and outer segments and impaired electroretinographic responses. Loss of HK2 in rods led to upregulation of HK1, phosphorylation of pyruvate kinase muscle isozyme 2, mitochondrial stress proteins and enzymes in the TCA cycle. Mass spectrometry found that the deletion of HK2 in rods resulted in accumulation of 13C-glucose along with decreased pyruvate and increased metabolites in the TCA cycle. Our data suggest that HK2-mediated aerobic glycolysis is indispensable for the maintenance of photoreceptor structure and function and that long-term inhibition of glycolysis leads to photoreceptor degeneration.
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Zhang T, Gillies M, Wang Y, Shen W, Bahrami B, Zeng S, Zhu M, Yao W, Zhou F, Murray M, Wang K, Zhu L. Simvastatin protects photoreceptors from oxidative stress induced by all-trans-retinal, through the up-regulation of interphotoreceptor retinoid binding protein. Br J Pharmacol 2019; 176:2063-2078. [PMID: 30825184 DOI: 10.1111/bph.14650] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 02/10/2019] [Accepted: 02/14/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND PURPOSE Simvastatin is a 3-hydroxy-3-methylglutaryl CoA reductase inhibitor with multiple targets and effects. It protects neurons in the brain, but its protective effects on photoreceptors are unclear. In this study, we evaluated the neuroprotective effect of simvastatin on photoreceptors exposed to stress induced by all-trans-retinal (atRAL). EXPERIMENTAL APPROACH AlamarBlue and LDH assays were used to evaluate the viability and metabolic activity of Y79 cells (a retinoblastoma cell line) exposed to atRAL-induced stress with or without simvastatin pretreatment. Changes in cellular ROS were evaluated using flow cytometry and mitochondrial stress markers JC-1 and HSP60. Changes in levels of two photoreceptor-specific markers, cone-rod homeobox protein (CRX) and interphotoreceptor retinoid binding protein (IRBP), were evaluated with western blot. The results were validated in ex vivo human retinal explants and a mouse model of photoreceptor degeneration. KEY RESULTS Simvastatin improved mitochondrial function, alleviated oxidative stress and up-regulated the photoreceptor-specific markers IRBP and its upstream regulator CRX in Y79 cells and ex vivo human retinal explants under atRAL-induced stress. Simvastatin attenuated photoreceptor degeneration in association with up-regulation of IRBP and CRX expression after knockdown of IRBP in a murine model. CONCLUSION AND IMPLICATIONS Our findings suggest that simvastatin has a novel role in protecting photoreceptors from atRAL-induced stress. Simvastatin treatment resulted in up-regulation of IRBP and its upstream transcription factor CRX in Y79 cells, ex vivo human retinal explants, and murine retinas in vivo. Further studies of simvastatin to treat photoreceptor degeneration are warranted.
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Affiliation(s)
- Ting Zhang
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Mark Gillies
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Ying Wang
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Weiyong Shen
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Bobak Bahrami
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Shaoxue Zeng
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia.,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Meidong Zhu
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia.,New South Wales Organ and Tissue Donation Service, New South Wales Tissue Bank, Sydney Eye Hospital, Sydney, New South Wales, Australia
| | - Wenjuan Yao
- School of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia.,Department of Pharmacology, Nantong University Medical College, Nantong, Jiangsu, China
| | - Fanfan Zhou
- School of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
| | - Michael Murray
- Discipline of Pharmacology, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Ke Wang
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China
| | - Ling Zhu
- Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia
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Zhang T, Zhu L, Madigan MC, Liu W, Shen W, Cherepanoff S, Zhou F, Zeng S, Du J, Gillies MC. Human macular Müller cells rely more on serine biosynthesis to combat oxidative stress than those from the periphery. eLife 2019; 8:43598. [PMID: 31036157 PMCID: PMC6533082 DOI: 10.7554/elife.43598] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/08/2019] [Indexed: 11/18/2022] Open
Abstract
The human macula is more susceptible than the peripheral retina to developing blinding conditions such as age-related macular degeneration, diabetic retinopathy. A key difference between them may be the nature of their Müller cells. We found primary cultured Müller cells from macula and peripheral retina display significant morphological and transcriptomic differences. Macular Müller cells expressed more phosphoglycerate dehydrogenase (PHGDH, a rate-limiting enzyme in serine synthesis) than peripheral Müller cells. The serine synthesis, glycolytic and mitochondrial function were more activated in macular than peripheral Müller cells. Serine biosynthesis is critical in defending against oxidative stress. Intracellular reactive oxygen species and glutathione levels were increased in primary cultured macular Müller cells which were more susceptible to oxidative stress after inhibition of PHGDH. Our findings indicate serine biosynthesis is a critical part of the macular defence against oxidative stress and suggest dysregulation of this pathway as a potential cause of macular pathology.
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Affiliation(s)
- Ting Zhang
- Save Sight Institute, Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Ling Zhu
- Save Sight Institute, Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Michele C Madigan
- Save Sight Institute, Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia.,School of Optometry and Vision Sciences, University of New South Wales, Sydney, Australia
| | - Wei Liu
- Clinical Genomics Laboratory, Sidra Medicine, Doha, Qatar
| | - Weiyong Shen
- Save Sight Institute, Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Svetlana Cherepanoff
- Department of Anatomical Pathology, St Vincent's Hospital, Darlinghurst, Australia
| | - Fanfan Zhou
- Faculty of Pharmacy, The University of Sydney, Sydney, Australia
| | - Shaoxue Zeng
- Save Sight Institute, Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Jianhai Du
- Department of Ophthalmology, West Virginia University, Morgantown, United States.,Department of Biochemistry, West Virginia University, Morgantown, United States
| | - Mark C Gillies
- Save Sight Institute, Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
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Sluch VM, Banks A, Li H, Crowley MA, Davis V, Xiang C, Yang J, Demirs JT, Vrouvlianis J, Leehy B, Hanks S, Hyman AM, Aranda J, Chang B, Bigelow CE, Rice DS. ADIPOR1 is essential for vision and its RPE expression is lost in the Mfrp rd6 mouse. Sci Rep 2018; 8:14339. [PMID: 30254279 PMCID: PMC6156493 DOI: 10.1038/s41598-018-32579-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 09/10/2018] [Indexed: 12/15/2022] Open
Abstract
The knockout (KO) of the adiponectin receptor 1 (AdipoR1) gene causes retinal degeneration. Here we report that ADIPOR1 protein is primarily found in the eye and brain with little expression in other tissues. Further analysis of AdipoR1 KO mice revealed that these animals exhibit early visual system abnormalities and are depleted of RHODOPSIN prior to pronounced photoreceptor death. A KO of AdipoR1 post-development either in photoreceptors or the retinal pigment epithelium (RPE) resulted in decreased expression of retinal proteins, establishing a role for ADIPOR1 in supporting vision in adulthood. Subsequent analysis of the Mfrprd6 mouse retina demonstrated that these mice are lacking ADIPOR1 in their RPE layer alone, suggesting that loss of ADIPOR1 drives retinal degeneration in this model. Moreover, we found elevated levels of IRBP in both the AdipoR1 KO and the Mfrprd6 models. The spatial distribution of IRBP was also abnormal. This dysregulation of IRBP hypothesizes a role for ADIPOR1 in retinoid metabolism.
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Affiliation(s)
- Valentin M Sluch
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States.
| | - Angela Banks
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Hui Li
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Maura A Crowley
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Vanessa Davis
- Global Scientific Operations, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Chuanxi Xiang
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Junzheng Yang
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - John T Demirs
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Joanna Vrouvlianis
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Barrett Leehy
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Shawn Hanks
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Alexandra M Hyman
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Jorge Aranda
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine, United States
| | - Chad E Bigelow
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States
| | - Dennis S Rice
- Department of Ophthalmology, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, United States.
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Characterization of canonical Wnt signalling changes after induced disruption of Müller cell in murine retina. Exp Eye Res 2018; 175:173-180. [PMID: 29913166 DOI: 10.1016/j.exer.2018.06.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 06/06/2018] [Accepted: 06/14/2018] [Indexed: 02/05/2023]
Abstract
Müller cells are the primary glia in the retina, playing a critical role in retinal homeostasis and retinal pathology. This study evaluated the canonical Wnt signalling pathway and its downstream effects on retinal degeneration in a transgenic mouse model of inducible Müller cell disruption. Increased expression of the LacZ reporter gene in the retina suggested Wnt signalling had been activated after induced Müller cell disruption. Activation was validated by observing nuclear translocation of β-Catenin. The mRNA expression of 80 Wnt related genes were assessed using real-time PCR. The Wnt signalling inhibitors Dkk1, Dkk3 and sFRP3 were significantly downregulated. Furthermore, the ubiquitin-mediated β-Catenin proteolysis genes β-TrCP and SHFM3, were also significantly downregulated. The downstream target genes of the Wnt signalling, including Fra1, CyclinD2 and C-Myc were upregulated. The changes of these genes at the protein level were validated by Western blot. Their distributions in the retina were evaluated by immunofluorescent staining. Our findings indicate that Müller cells are involved in retinal Wnt signalling. Activation of Wnt signalling and its downstream target genes may play important roles in photoreceptor degeneration and neovascularization occurring in the retina after induced disruption of Müller cells.
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Zhang T, Gillies MC, Madigan MC, Shen W, Du J, Grünert U, Zhou F, Yam M, Zhu L. Disruption of De Novo Serine Synthesis in Müller Cells Induced Mitochondrial Dysfunction and Aggravated Oxidative Damage. Mol Neurobiol 2018; 55:7025-7037. [PMID: 29383682 DOI: 10.1007/s12035-017-0840-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 12/12/2017] [Indexed: 02/05/2023]
Abstract
De novo serine synthesis plays important roles in normal mitochondrial function and cellular anti-oxidative capacity. It is reported to be mainly activated in glial cells of the central nervous system, but its role in retinal Müller glia remains unclear. In this study, we inhibited de novo serine synthesis using CBR-5884, a specific inhibitor of phosphoglycerate dehydrogenase (PHGDH, a rate limiting enzyme in de novo serine metabolism) in MIO-M1 cells (immortalized human Müller cells) and huPMCs (human primary Müller cells) under mild oxidative stress. Alamar blue and LDH (lactate dehydrogenase) assays showed significantly reduced metabolic activities and increased cellular damage of Müller cells, when exposed to CBR-5884 accompanied by mild oxidative stress; however, CBR-5884 alone had little effect. The increased cellular damage was partially reversed by supplementation with exogenous serine/glycine. HSP72 (an oxidative stress marker) and reactive oxygen species (ROS) levels were significantly increased; glutathione and NADPH/NADP+ levels were pronouncedly reduced under PHGDH inhibition accompanied by oxidative stress. JC-1 staining and Seahorse respiration experiments showed that inhibition of de novo serine synthesis in Müller cells can also increase mitochondrial stress and decrease mitochondrial ATP production. qPCR and Western blot demonstrated an increased expression of HSP60 (a key mitochondrial stress-related gene), and this was further validated in human retinal explants. Our study suggests that de novo serine synthesis is important for Müller cell survival, particularly when they are exposed to mild oxidative stress, possibly by maintaining mitochondrial function and generating glutathione and NADPH to counteract ROS.
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Affiliation(s)
- Ting Zhang
- State Key Laboratory of Biotherapy and Cancer Center, Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China.,Save Sight Institute, The University of Sydney, 8 Macquarie Street, Sydney, NSW, 2000, Australia
| | - Mark C Gillies
- Save Sight Institute, The University of Sydney, 8 Macquarie Street, Sydney, NSW, 2000, Australia
| | - Michele C Madigan
- Save Sight Institute, The University of Sydney, 8 Macquarie Street, Sydney, NSW, 2000, Australia.,School of Optometry and Vision Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Weiyong Shen
- Save Sight Institute, The University of Sydney, 8 Macquarie Street, Sydney, NSW, 2000, Australia
| | - Jianhai Du
- West Virginia University Health Sciences Center, Morgantown, WV, USA
| | - Ulrike Grünert
- Save Sight Institute, The University of Sydney, 8 Macquarie Street, Sydney, NSW, 2000, Australia
| | - Fanfan Zhou
- Faculty of Pharmacy, The University of Sydney, Sydney, NSW, Australia
| | - Michelle Yam
- Save Sight Institute, The University of Sydney, 8 Macquarie Street, Sydney, NSW, 2000, Australia
| | - Ling Zhu
- Save Sight Institute, The University of Sydney, 8 Macquarie Street, Sydney, NSW, 2000, Australia.
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