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Vessey KA, Jobling AI, Greferath U, Fletcher EL. Pharmaceutical therapies targeting autophagy for the treatment of age-related macular degeneration. Curr Opin Pharmacol 2024; 76:102463. [PMID: 38788268 DOI: 10.1016/j.coph.2024.102463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 04/29/2024] [Accepted: 05/03/2024] [Indexed: 05/26/2024]
Abstract
Age-related macular degeneration (AMD) is a major cause of irreversible vision loss in the elderly. Although new therapies have recently emerged, there are currently no ways of preventing the development of the disease. Changes in intracellular recycling processes. Changes in intracellular recycling processes, called autophagy, lead to debris accumulation and cellular dysfunction in AMD models and AMD patients. Drugs that enhance autophagy hold promise as therapies for slowing AMD progression in preclinical models; however, more studies in humans are required. While a definitive cure for AMD will likely hinge on a personalized medicine approach, treatments that enhance autophagy hold promise for slowing vision loss.
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Affiliation(s)
- Kirstan A Vessey
- Department of Anatomy and Physiology, The University of Melbourne, VIC 3010, Australia; School of Science and Technology, The University of New England, NSW 2350, Australia
| | - Andrew I Jobling
- Department of Anatomy and Physiology, The University of Melbourne, VIC 3010, Australia
| | - Ursula Greferath
- Department of Anatomy and Physiology, The University of Melbourne, VIC 3010, Australia
| | - Erica L Fletcher
- Department of Anatomy and Physiology, The University of Melbourne, VIC 3010, Australia.
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2
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Ertuğrul A, Özkaya D, Nazıroğlu M. Curcumin attenuates hydroxychloroquine-mediated apoptosis and oxidative stress via the inhibition of TRPM2 channel signalling pathways in a retinal pigment epithelium cell line. Graefes Arch Clin Exp Ophthalmol 2023; 261:2829-2844. [PMID: 37099129 PMCID: PMC10131512 DOI: 10.1007/s00417-023-06082-5] [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: 01/05/2023] [Revised: 04/10/2023] [Accepted: 04/15/2023] [Indexed: 04/27/2023] Open
Abstract
PURPOSE Hydroxychloroquine (HCQ) is used in the treatment of several diseases, such as malaria, Sjögren's disease, Covid-19, and rheumatoid arthritis. However, HCQ induces retinal pigment epithelium death via the excessive increase of cytosolic (cROS) and mitochondrial (mROS) free oxygen radical production. The transient receptor potential melastatin 2 (TRPM2) cation channel is stimulated by ADP-ribose (ADPR), cROS, and mROS, although it is inhibited by curcumin (CRC). We aimed to investigate the modulating action of CRC on HCQ-induced TRPM2 stimulation, cROS, mROS, apoptosis, and death in an adult retinal pigment epithelial 19 (ARPE19) cell line model. MATERIAL AND METHODS ARPE19 cells were divided into four groups: control (CNT), CRC (5 µM for 24 h), HCQ (60 µM for 48 h), and CRC + HCQ groups. RESULTS The levels of cell death (propidium iodide positive cell numbers), apoptosis markers (caspases -3, -8, and -9), oxidative stress (cROS and mROS), mitochondria membrane depolarization, TRPM2 current density, and intracellular free Ca2+ and Zn2+ fluorescence intensity were upregulated in the HCQ group after stimulation with hydrogen peroxide and ADPR, but their levels were downregulated by treatments with CRC and TRPM2 blockers (ACA and carvacrol). The HCQ-induced decrease in retinal live cell count and cell viability was counteracted by treatment with CRC. CONCLUSION HCQ-mediated overload Ca2+ influx and retinal oxidative toxicity were induced in an ARPE19 cell line through the stimulation of TRPM2, although they were attenuated by treatment with CRC. Hence, CRC may be a potential therapeutic antioxidant for TRPM2 activation and HCQ treatment-induced retinal oxidative injury and apoptosis.
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Affiliation(s)
- Alper Ertuğrul
- Department of Ophthalmology, Faculty of Medicine, Suleyman Demirel University, TR-32260, Isparta, Turkey
| | - Dilek Özkaya
- Department of Ophthalmology, Faculty of Medicine, Suleyman Demirel University, TR-32260, Isparta, Turkey
| | - Mustafa Nazıroğlu
- Neuroscience Research Center, Suleyman Demirel University, TR-32260, Isparta, Turkey.
- Drug Discovery Unit, BSN Health, Analyses, Innov., Consult., Org., Agricul., Ltd., TR-32260, Isparta, Turkey.
- Department of Biophysics, Faculty of Medicine, Suleyman Demirel University, Isparta, TR-32260, Turkey.
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3
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Markitantova Y, Simirskii V. Endogenous and Exogenous Regulation of Redox Homeostasis in Retinal Pigment Epithelium Cells: An Updated Antioxidant Perspective. Int J Mol Sci 2023; 24:10776. [PMID: 37445953 DOI: 10.3390/ijms241310776] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
The retinal pigment epithelium (RPE) performs a range of necessary functions within the neural layers of the retina and helps ensure vision. The regulation of pro-oxidative and antioxidant processes is the basis for maintaining RPE homeostasis and preventing retinal degenerative processes. Long-term stable changes in the redox balance under the influence of endogenous or exogenous factors can lead to oxidative stress (OS) and the development of a number of retinal pathologies associated with RPE dysfunction, and can eventually lead to vision loss. Reparative autophagy, ubiquitin-proteasome utilization, the repair of damaged proteins, and the maintenance of their conformational structure are important interrelated mechanisms of the endogenous defense system that protects against oxidative damage. Antioxidant protection of RPE cells is realized as a result of the activity of specific transcription factors, a large group of enzymes, chaperone proteins, etc., which form many signaling pathways in the RPE and the retina. Here, we discuss the role of the key components of the antioxidant defense system (ADS) in the cellular response of the RPE against OS. Understanding the role and interactions of OS mediators and the components of the ADS contributes to the formation of ideas about the subtle mechanisms in the regulation of RPE cellular functions and prospects for experimental approaches to restore RPE functions.
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Affiliation(s)
- Yuliya Markitantova
- Koltsov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
| | - Vladimir Simirskii
- Koltsov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
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4
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Si Z, Zheng Y, Zhao J. The Role of Retinal Pigment Epithelial Cells in Age-Related Macular Degeneration: Phagocytosis and Autophagy. Biomolecules 2023; 13:901. [PMID: 37371481 DOI: 10.3390/biom13060901] [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: 03/08/2023] [Revised: 05/11/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023] Open
Abstract
Age-related macular degeneration (AMD) causes vision loss in the elderly population. Dry AMD leads to the formation of Drusen, while wet AMD is characterized by cell proliferation and choroidal angiogenesis. The retinal pigment epithelium (RPE) plays a key role in AMD pathogenesis. In particular, helioreceptor renewal depends on outer segment phagocytosis of RPE cells, while RPE autophagy can protect cells from oxidative stress damage. However, when the oxidative stress burden is too high and homeostasis is disturbed, the phagocytosis and autophagy functions of RPE become damaged, leading to AMD development and progression. Hence, characterizing the roles of RPE cell phagocytosis and autophagy in the pathogenesis of AMD can inform the development of potential therapeutic targets to prevent irreversible RPE and photoreceptor cell death, thus protecting against AMD.
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Affiliation(s)
- Zhibo Si
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun 130000, China
| | - Yajuan Zheng
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun 130000, China
| | - Jing Zhao
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun 130000, China
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5
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Ma JY, Greferath U, Wong JH, Fothergill LJ, Jobling AI, Vessey KA, Fletcher EL. Aging induces cell loss and a decline in phagosome processing in the mouse retinal pigment epithelium. Neurobiol Aging 2023; 128:1-16. [PMID: 37130462 DOI: 10.1016/j.neurobiolaging.2023.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 02/10/2023] [Accepted: 03/03/2023] [Indexed: 03/14/2023]
Abstract
Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss and dysfunction in the retinal pigment epithelium (RPE) with age is known to contribute to disease development. The aim of this study was to investigate how the C57BL/6J mouse RPE changes with age. RPE structure was found to change with age and eccentricity, with cell size increasing, nuclei lost, and tight junctions altered in the peripheral retina. Phagocytosis of photoreceptor outer segments (POS) by the RPE was investigated using gene expression analysis and histology. RNA-Seq transcriptomic gene profiling of the RPE showed a downregulation of genes involved in phagosome processing and histological analysis showed a decline in phagosome-lysosome association in the aged tissue. In addition, failures in the autophagy pathway that modulates intracellular waste degradation were observed in the aged RPE tissue. These findings highlight that RPE cell loss and slowing of POS processing contribute to RPE dysfunction with age and may predispose the aging eye to AMD development.
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6
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Intartaglia D, Giamundo G, Conte I. Autophagy in the retinal pigment epithelium: a new vision and future challenges. FEBS J 2022; 289:7199-7212. [PMID: 33993621 PMCID: PMC9786786 DOI: 10.1111/febs.16018] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/07/2021] [Accepted: 05/12/2021] [Indexed: 01/13/2023]
Abstract
The retinal pigment epithelium (RPE) is a highly specialized monolayer of polarized, pigmented epithelial cells that resides between the vessels of the choriocapillaris and the neural retina. The RPE is essential for the maintenance and survival of overlying light-sensitive photoreceptors, as it participates in the formation of the outer blood-retinal barrier, phagocytosis, degradation of photoreceptor outer segment (POS) tips, maintenance of the retinoid cycle, and protection against light and oxidative stress. Autophagy is an evolutionarily conserved 'self-eating' process, designed to maintain cellular homeostasis. The daily autophagy demands in the RPE require precise gene regulation for the digestion and recycling of intracellular and POS components in lysosomes in response to light and stress conditions. In this review, we discuss selective autophagy and focus on the recent advances in our understanding of the mechanism of cell clearance in the RPE for visual function. Understanding how this catabolic process is regulated by both transcriptional and post-transcriptional mechanisms in the RPE will promote the recognition of pathological pathways in genetic disease and shed light on potential therapeutic strategies to treat visual impairments in patients with retinal disorders associated with lysosomal dysfunction.
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Affiliation(s)
| | | | - Ivan Conte
- Telethon Institute of Genetics and MedicinePozzuoli (Naples)Italy,Department of BiologyUniversity of Naples Federico IINaplesItaly
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7
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A Re-Appraisal of Pathogenic Mechanisms Bridging Wet and Dry Age-Related Macular Degeneration Leads to Reconsider a Role for Phytochemicals. Int J Mol Sci 2020; 21:ijms21155563. [PMID: 32756487 PMCID: PMC7432893 DOI: 10.3390/ijms21155563] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 07/31/2020] [Accepted: 08/01/2020] [Indexed: 12/14/2022] Open
Abstract
Which pathogenic mechanisms underlie age-related macular degeneration (AMD)? Are they different for dry and wet variants, or do they stem from common metabolic alterations? Where shall we look for altered metabolism? Is it the inner choroid, or is it rather the choroid–retinal border? Again, since cell-clearing pathways are crucial to degrade altered proteins, which metabolic system is likely to be the most implicated, and in which cell type? Here we describe the unique clearing activity of the retinal pigment epithelium (RPE) and the relevant role of its autophagy machinery in removing altered debris, thus centering the RPE in the pathogenesis of AMD. The cell-clearing systems within the RPE may act as a kernel to regulate the redox homeostasis and the traffic of multiple proteins and organelles toward either the choroid border or the outer segments of photoreceptors. This is expected to cope with the polarity of various domains within RPE cells, with each one owning a specific metabolic activity. A defective clearance machinery may trigger unconventional solutions to avoid intracellular substrates’ accumulation through unconventional secretions. These components may be deposited between the RPE and Bruch’s membrane, thus generating the drusen, which remains the classic hallmark of AMD. These deposits may rather represent a witness of an abnormal RPE metabolism than a real pathogenic component. The empowerment of cell clearance, antioxidant, anti-inflammatory, and anti-angiogenic activity of the RPE by specific phytochemicals is here discussed.
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Saito Y, Yako T, Otsu W, Nakamura S, Inoue Y, Muramatsu A, Nakagami Y, Shimazawa M, Hara H. A triterpenoid Nrf2 activator, RS9, promotes LC3-associated phagocytosis of photoreceptor outer segments in a p62-independent manner. Free Radic Biol Med 2020; 152:235-247. [PMID: 32217192 DOI: 10.1016/j.freeradbiomed.2020.03.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 03/19/2020] [Indexed: 12/13/2022]
Abstract
Daily phagocytosis of shed photoreceptor outer segments (POS) by the retinal pigment epithelium (RPE) is required to sustain the visual function. Recent reports revealed that POS phagocytosis is progressed with LC3-associated manner. Patients with age-related macular degeneration (AMD) had impaired autophagic degradation in the RPE. Nrf2 is a key antioxidant transcriptional regulator that ameliorates oxidative stress which is another contributor to AMD pathogenesis. Nrf2 activation also induces the autophagy receptor protein, p62. However, the role of the Nrf2-p62 pathway in LC3-associated phagocytosis of POS is poorly understood. Here, we investigated the relationships between Nrf2 activation and POS phagocytosis progression. A triterpenoid Nrf2 activator, RS9, facilitated POS uptake into phagolysosomes in RPE cells. RS9 also induced the expression of the autophagy-related proteins, LC3-II and p62, as well as phase-2 antioxidant enzymes. The effect of RS9 on POS phagocytosis was abolished by autophagy inhibition. Unexpectedly, p62 knockdown did not inhibit the effect of RS9 on POS phagocytosis, although, RS9-mediated LC3-II induction by RS9 was inhibited in p62 knockdown RPE cells. We also found that RS9 activated the AMPKα-mTOR signaling pathway earlier than p62 induction. Knockdown of AMPKα1, but not α2, inhibited the RS9-mediated activation of LC3-associated phagocytosis and RS9-mediated induction of LC3-II. Furthermore, intravitreal treatment of RS9 to adult mice decreased the size of POS phagolysosomes after light exposure. Collectively, these results showed that RS9-mediated activation of POS phagocytosis was mainly ascribed to the enhancement of autophagy via AMPKα1 activation. Our findings reveal novel effects of Nrf2 and AMPK α1 activation that contribute to the maintenance of the RPE function via LC3-associated POS phagocytosis.
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Affiliation(s)
- Yuichi Saito
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
| | - Tomohiro Yako
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
| | - Wataru Otsu
- Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan.
| | - Shinsuke Nakamura
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
| | - Yuki Inoue
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
| | - Aomi Muramatsu
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan.
| | | | - Masamitsu Shimazawa
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan; Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan.
| | - Hideaki Hara
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan; Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan.
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9
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Olchawa M, Krzysztynska-Kuleta O, Duda M, Pawlak A, Pabisz P, Czuba-Pelech B, Sarna T. In vitro phototoxicity of rhodopsin photobleaching products in the retinal pigment epithelium (RPE). Free Radic Res 2019; 53:456-471. [DOI: 10.1080/10715762.2019.1603377] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Magdalena Olchawa
- Faculty of Biochemistry, Biophysics and Biotechnology, Department of Biophysics, Jagiellonian University, Kraków, Poland
| | - Olga Krzysztynska-Kuleta
- Faculty of Biochemistry, Biophysics and Biotechnology, Department of Biophysics, Jagiellonian University, Kraków, Poland
- Laboratory of Imaging and Atomic Force Spectroscopy, Malopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland
| | - Mariusz Duda
- Faculty of Biochemistry, Biophysics and Biotechnology, Department of Biophysics, Jagiellonian University, Kraków, Poland
- Laboratory of Imaging and Atomic Force Spectroscopy, Malopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland
| | - Anna Pawlak
- Faculty of Biochemistry, Biophysics and Biotechnology, Department of Biophysics, Jagiellonian University, Kraków, Poland
| | - Pawel Pabisz
- Faculty of Biochemistry, Biophysics and Biotechnology, Department of Biophysics, Jagiellonian University, Kraków, Poland
| | - Barbara Czuba-Pelech
- Faculty of Biochemistry, Biophysics and Biotechnology, Department of Biophysics, Jagiellonian University, Kraków, Poland
| | - Tadeusz Sarna
- Faculty of Biochemistry, Biophysics and Biotechnology, Department of Biophysics, Jagiellonian University, Kraków, Poland
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10
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Inana G, Murat C, An W, Yao X, Harris IR, Cao J. RPE phagocytic function declines in age-related macular degeneration and is rescued by human umbilical tissue derived cells. J Transl Med 2018. [PMID: 29534722 PMCID: PMC5851074 DOI: 10.1186/s12967-018-1434-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Background Age-related macular degeneration (AMD) is a leading cause of blindness among the elderly characterized by retinal pigment epithelium (RPE) degeneration with accumulation of abnormal intracellular deposits (lipofuscin) and photoreceptor death. RPE is vital for the retina and integrity of photoreceptors through its phagocytic function which is closely linked to formation of lipofuscin through daily phagocytosis of discarded photoreceptor outer segments (POS). Although phagocytosis has been implicated in AMD, it has not been directly shown to be altered in AMD. RPE phagocytic defect was previously shown to be rescued by subretinal injection of human umbilical tissue derived cells (hUTC) in a rodent model of retinal degeneration (RCS rat) through receptor tyrosine kinase (RTK) ligands and bridge molecules. Here, we examined RPE phagocytic function directly in the RPE from AMD patients and the ability and mechanisms of hUTC to affect phagocytosis in the human RPE. Methods Human RPE was isolated from the post-mortem eyes of normal and AMD-affected subjects and cultured. RPE phagocytic function was measured in vitro using isolated POS. The effects of hUTC conditioned media, recombinant RTK ligands brain-derived neurotrophic factor (BDNF), hepatocyte growth factor (HGF), and glial cell-derived neurotrophic factor (GDNF), as well as bridge molecules milk-fat-globule-EGF-factor 8 (MFG-E8), thrombospondin (TSP)-1, and TSP-2 on phagocytosis were also examined in phagocytosis assays using isolated POS. RNA was isolated from normal and AMD RPE treated with hUTC conditioned media and subjected to transcriptome profiling by RNA-Seq and computational analyses. Results RPE phagocytosis, while showing a moderate decline with age, was significantly reduced in AMD RPE, more than expected for age. hUTC conditioned media stimulated phagocytosis in the normal human RPE and significantly rescued the phagocytic dysfunction in the AMD RPE. RTK ligands and bridge molecules duplicated the rescue effect. Moreover, multiple molecular pathways involving phagocytosis, apoptosis, oxidative stress, inflammation, immune activation, and cholesterol transport were affected by hUTC in the RPE. Conclusions We demonstrated for the first time RPE phagocytic dysfunction in AMD, highlighting its likely importance in AMD, and the ability of hUTC to correct this dysfunction, providing insights into the therapeutic potential of hUTC for AMD. Electronic supplementary material The online version of this article (10.1186/s12967-018-1434-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- George Inana
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, 1638 N.W. 10th Avenue, Miami, FL, 33136, USA.
| | - Christopher Murat
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, 1638 N.W. 10th Avenue, Miami, FL, 33136, USA
| | - Weijun An
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, 1638 N.W. 10th Avenue, Miami, FL, 33136, USA
| | - Xiang Yao
- Janssen Research & Development, LLC, San Diego, CA, 92121, USA
| | - Ian R Harris
- Janssen Research & Development, LLC, Spring House, PA, 19477, USA
| | - Jing Cao
- Janssen Research & Development, LLC, Spring House, PA, 19477, USA.
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11
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Feng Y, Wang S, Zhang Y, Xiao H. Metformin attenuates renal fibrosis in both AMPKα2-dependent and independent manners. Clin Exp Pharmacol Physiol 2017; 44:648-655. [PMID: 28273365 DOI: 10.1111/1440-1681.12748] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 01/08/2023]
Affiliation(s)
- Yenan Feng
- Institute of Vascular Medicine; Peking University Third Hospital; Beijing China
- Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides; Ministry of Health; Beijing China
- Key Laboratory of Molecular Cardiovascular Sciences; Ministry of Education; Beijing China
- Beijing Key Laboratory of Cardiovascular Receptors Research; Beijing China
| | - Shuaixing Wang
- Institute of Vascular Medicine; Peking University Third Hospital; Beijing China
- Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides; Ministry of Health; Beijing China
- Key Laboratory of Molecular Cardiovascular Sciences; Ministry of Education; Beijing China
- Beijing Key Laboratory of Cardiovascular Receptors Research; Beijing China
| | - Youyi Zhang
- Institute of Vascular Medicine; Peking University Third Hospital; Beijing China
- Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides; Ministry of Health; Beijing China
- Key Laboratory of Molecular Cardiovascular Sciences; Ministry of Education; Beijing China
- Beijing Key Laboratory of Cardiovascular Receptors Research; Beijing China
| | - Han Xiao
- Institute of Vascular Medicine; Peking University Third Hospital; Beijing China
- Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides; Ministry of Health; Beijing China
- Key Laboratory of Molecular Cardiovascular Sciences; Ministry of Education; Beijing China
- Beijing Key Laboratory of Cardiovascular Receptors Research; Beijing China
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12
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Autophagy Regulates Proteasome Inhibitor-Induced Pigmentation in Human Embryonic Stem Cell-Derived Retinal Pigment Epithelial Cells. Int J Mol Sci 2017; 18:ijms18051089. [PMID: 28534814 PMCID: PMC5454998 DOI: 10.3390/ijms18051089] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/11/2017] [Accepted: 05/12/2017] [Indexed: 02/06/2023] Open
Abstract
The impairment of autophagic and proteasomal cleansing together with changes in pigmentation has been documented in retinal pigment epithelial (RPE) cell degeneration. However, the function and co-operation of these mechanisms in melanosome-containing RPE cells is still unclear. We show that inhibition of proteasomal degradation with MG-132 or autophagy with bafilomycin A1 increased the accumulation of premelanosomes and autophagic structures in human embryonic stem cell (hESC)-derived RPE cells. Consequently, upregulation of the autophagy marker p62 (also known as sequestosome-1, SQSTM1) was confirmed in Western blot and perinuclear staining. Interestingly, cells treated with the adenosine monophosphatedependent protein kinase activator, AICAR (5-Aminoimidazole-4-carboxamide ribonucleotide), decreased the proteasome inhibitor-induced accumulation of premelanosomes, increased the amount of autophagosomes and eradicated the protein expression of p62 and LC3 (microtubule-associated protein 1A/1B-light chain 3). These results revealed that autophagic machinery is functional in hESC-RPE cells and may regulate cellular pigmentation with proteasomes.
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13
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Teussink MM, Lambertus S, de Mul FF, Rozanowska MB, Hoyng CB, Klevering BJ, Theelen T. Lipofuscin-associated photo-oxidative stress during fundus autofluorescence imaging. PLoS One 2017; 12:e0172635. [PMID: 28235055 PMCID: PMC5325292 DOI: 10.1371/journal.pone.0172635] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/07/2017] [Indexed: 11/24/2022] Open
Abstract
Purpose Current standards and guidelines aimed at preventing retinal phototoxicity during intentional exposures do not specifically evaluate the contribution of endogenous photosensitizers. However, certain retinal diseases are characterized by abnormal accumulations of potential photosensitizers such as lipofuscin bisretinoids in the retinal pigment epithelium (RPE). We sought to determine these contributions by a numerical assessment of in-vivo photo-oxidative stress during irradiation of RPE lipofuscin. Methods Based on the literature, we calculated the retinal exposure levels, optical filtering of incident radiation by the ocular lens, media, photoreceptors, and RPE melanin, light absorption by lipofuscin, and photochemical effects in the RPE in two situations: exposure to short-wavelength (λ = 488 nm) fundus autofluorescence (SW-AF) excitation light and exposure to indirect (diffuse) sunlight. Results In healthy persons at age 20, 40, and 60, respectively, the rate of oxygen photoconsumption by lipofuscin increases by 1.3, 1.7, and 2.4 fold during SW-AF-imaging as compared to diffuse sunlight. In patients with STGD1 below the age of 30, this rate was 3.3-fold higher compared to age-matched controls during either sunlight or SW-AF imaging. Conclusions Our results suggest that the RPE of patients with STGD1 is generally at increased risk of photo-oxidative stress, while exposure during SW-AF-imaging amplifies this risk. These theoretical results have not yet been verified with in-vivo data due to a lack of sufficiently sensitive in-vivo measurement techniques.
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Affiliation(s)
- Michel M. Teussink
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Stanley Lambertus
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Frits F. de Mul
- Department of Applied Physics, University of Twente, Enschede, the Netherlands
| | | | - Carel B. Hoyng
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - B. Jeroen Klevering
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Thomas Theelen
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
- * E-mail:
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14
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Miller JW, Bagheri S, Vavvas DG. Advances in Age-related Macular Degeneration Understanding and Therapy. ACTA ACUST UNITED AC 2017; 10:119-130. [PMID: 29142592 PMCID: PMC5683729 DOI: 10.17925/usor.2017.10.02.119] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
While the development of anti-vascular endothelial growth factor (anti-VEGF) as a therapy for neovascular age-related macular degeneration (AMD) was a great success, the pathologic processes underlying dry AMD that eventually leads to photoreceptor dysfunction, death, and vision loss remain elusive to date, with a lack of effective therapies and increasing prevalence of the disease. There is an overwhelming need to improve the classification system of AMD, to increase our understanding of cell death mechanisms involved in both neovascular and non-neovascular AMD, and to develop better biomarkers and clinical endpoints to eventually be able to identify better therapeutic targets—especially early in the disease process. There is no doubt that it is a matter of time before progress will be made and better therapies will be developed for non-neovascular AMD.
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Affiliation(s)
- Joan W Miller
- Retina Service, Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, US
| | - Saghar Bagheri
- Retina Service, Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, US
| | - Demetrios G Vavvas
- Retina Service, Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, US
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Role of AMP-activated protein kinase α1 in angiotensin-II-induced renal Tgfß-activated kinase 1 activation. Biochem Biophys Res Commun 2016; 476:267-272. [DOI: 10.1016/j.bbrc.2016.05.111] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 05/22/2016] [Indexed: 01/12/2023]
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16
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Voelkl J, Alesutan I, Primessnig U, Feger M, Mia S, Jungmann A, Castor T, Viereck R, Stöckigt F, Borst O, Gawaz M, Schrickel JW, Metzler B, Katus HA, Müller OJ, Pieske B, Heinzel FR, Lang F. AMP-activated protein kinase α1-sensitive activation of AP-1 in cardiomyocytes. J Mol Cell Cardiol 2016; 97:36-43. [PMID: 27106803 DOI: 10.1016/j.yjmcc.2016.04.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 04/13/2016] [Accepted: 04/18/2016] [Indexed: 01/12/2023]
Abstract
AMP-activated protein kinase (Ampk) regulates myocardial energy metabolism and plays a crucial role in the response to cell stress. In the failing heart, an isoform shift of the predominant Ampkα2 to the Ampkα1 was observed. The present study explored possible isoform specific effects of Ampkα1 in cardiomyocytes. To this end, experiments were performed in HL-1 cardiomyocytes, as well as in Ampkα1-deficient and corresponding wild-type mice and mice following AAV9-mediated cardiac overexpression of constitutively active Ampkα1. As a result, in HL-1 cardiomyocytes, overexpression of constitutively active Ampkα1 increased the phosphorylation of Pkcζ. Constitutively active Ampkα1 further increased AP-1-dependent transcriptional activity and mRNA expression of the AP-1 target genes c-Fos, Il6 and Ncx1, effects blunted by Pkcζ silencing. In HL-1 cardiomyocytes, angiotensin-II activated AP-1, an effect blunted by silencing of Ampkα1 and Pkcζ, but not of Ampkα2. In wild-type mice, angiotensin-II infusion increased cardiac Ampkα1 and cardiac Pkcζ protein levels, as well as c-Fos, Il6 and Ncx1 mRNA expression, effects blunted in Ampkα1-deficient mice. Pressure overload by transverse aortic constriction (TAC) similarly increased cardiac Ampkα1 and Pkcζ abundance as well as c-Fos, Il6 and Ncx1 mRNA expression, effects again blunted in Ampkα1-deficient mice. AAV9-mediated cardiac overexpression of constitutively active Ampkα1 increased Pkcζ protein abundance and the mRNA expression of c-Fos, Il6 and Ncx1 in cardiac tissue. In conclusion, Ampkα1 promotes myocardial AP-1 activation in a Pkcζ-dependent manner and thus contributes to cardiac stress signaling.
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Affiliation(s)
- Jakob Voelkl
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany
| | - Ioana Alesutan
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany
| | - Uwe Primessnig
- Department of Cardiology, Charité, Campus Virchow & German Centre for Cardiovascular Research (DZHK), Charite & Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Martina Feger
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany
| | - Sobuj Mia
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany
| | - Andreas Jungmann
- Department of Internal Medicine III, University of Heidelberg, Im Neuenheimer Feld 410, Heidelberg, Germany, and DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Germany
| | - Tatsiana Castor
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany
| | - Robert Viereck
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany
| | - Florian Stöckigt
- Department of Medicine - Cardiology, University Hospital Bonn, Sigmund-Freud-Str.25, 53127 Bonn, Germany
| | - Oliver Borst
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany
| | - Meinrad Gawaz
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany
| | - Jan Wilko Schrickel
- Department of Medicine - Cardiology, University Hospital Bonn, Sigmund-Freud-Str.25, 53127 Bonn, Germany
| | - Bernhard Metzler
- Department of Medicine - Cardiology, Medical University Innsbruck, Anichstr.35, 6020 Innsbruck, Austria
| | - Hugo A Katus
- Department of Internal Medicine III, University of Heidelberg, Im Neuenheimer Feld 410, Heidelberg, Germany, and DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Germany
| | - Oliver J Müller
- Department of Internal Medicine III, University of Heidelberg, Im Neuenheimer Feld 410, Heidelberg, Germany, and DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Germany
| | - Burkert Pieske
- Department of Cardiology, Charité, Campus Virchow & German Centre for Cardiovascular Research (DZHK), Charite & Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany; Department of Cardiology, University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
| | - Frank R Heinzel
- Department of Cardiology, Charité, Campus Virchow & German Centre for Cardiovascular Research (DZHK), Charite & Berlin Institute of Health, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Florian Lang
- Department of Physiology & Cardiology and Cardiovascular Medicine, University of Tübingen, Gmelinstr.5/Otfried-Mueller-Str. 10, 72076, Tübingen, Germany.
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Qin S. Blockade of MerTK Activation by AMPK Inhibits RPE Cell Phagocytosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:773-8. [PMID: 26427488 DOI: 10.1007/978-3-319-17121-0_103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Timely removal of shed photoreceptor outer segments by retinal pigment epithelial cells (RPE) plays a key role in biological renewal of these highly peroxidizable structures and in maintenance of retina health. How environmental stress cause RPE cell dysfunction is undefined however. AMP-activated protein kinase (AMPK), a heterotrimer of a catalytic α subunit and regulatory β and γ subunits, maintains energy homeostasis by limiting energy utilization and/or promoting energy production when energy supply is compromised. Intriguingly, AMPK has been shown to be important in functions of RPE cells. In this mini-review, the role and mechanisms of AMPK in controlling RPE cell phagocytosis are discussed.
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Affiliation(s)
- Suofu Qin
- Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., RD3-2D, 92612, Irvine, CA, USA.
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18
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The Role of AMPK Pathway in Neuroprotection. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:425-30. [DOI: 10.1007/978-3-319-17121-0_56] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Rogosnitzky M, Isakov I, Wlassoff W, Ingram A, Barishak YR. Ocular Applications of Dipyridamole: A Review of Indications and Routes of Administration. J Ocul Pharmacol Ther 2015; 32:83-9. [PMID: 26696547 PMCID: PMC4779994 DOI: 10.1089/jop.2015.0128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Dipyridamole was introduced decades ago as a treatment for angina, subsequently found to inhibit platelet aggregation. It is most commonly used, and approved for use in thromboembolism prevention, following surgery. Some of its recognized effects such as adenosine uptake inhibition, elevation of cAMP and cGMP levels, vasodilation, and tissue perfusion are important in various ocular disorders. For this reason, dipyridamole represents an interesting candidate as a therapeutic target for the treatment of eye disorders affecting different ocular structures. The aim of this article is to review the evidence and current understanding of the mechanisms by which dipyridamole exerts its effects on different ocular tissues, discuss the role of dipyridamole in clinical practice, and highlight areas of use and routes of administration.
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Affiliation(s)
- Moshe Rogosnitzky
- 1 Ocular Research Department, Center for Drug Repurposing, Ariel University , Ariel, Israel .,2 Eye Research Program, MedInsight Research Institute , Hampshire, United Kingdom
| | - Itzhak Isakov
- 1 Ocular Research Department, Center for Drug Repurposing, Ariel University , Ariel, Israel
| | | | - April Ingram
- 2 Eye Research Program, MedInsight Research Institute , Hampshire, United Kingdom
| | - Y Robert Barishak
- 1 Ocular Research Department, Center for Drug Repurposing, Ariel University , Ariel, Israel
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Impact of AMP-Activated Protein Kinase α1 Deficiency on Tissue Injury following Unilateral Ureteral Obstruction. PLoS One 2015; 10:e0135235. [PMID: 26285014 PMCID: PMC4540418 DOI: 10.1371/journal.pone.0135235] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 07/20/2015] [Indexed: 12/22/2022] Open
Abstract
Background AMP-activated protein kinase (Ampk) is a sensor of the cellular energy status and a powerful regulator of metabolism. Activation of Ampk was previously shown to participate in monocyte-to-fibroblast transition and matrix protein production in renal tissue. Thus, the present study explored whether the catalytic Ampkα1 isoform participates in the regulation of the renal fibrotic response following unilateral ureteral obstruction (UUO). Methods UUO was induced in gene-targeted mice lacking functional Ampkα1 (Ampkα1-/-) and in corresponding wild-type mice (Ampkα1+/+). In the obstructed kidney and, for comparison, in the non-obstructed control kidney, quantitative RT-PCR, Western blotting and immunostaining were employed to determine transcript levels and protein abundance, respectively. Results In Ampkα1+/+ mice, UUO significantly up-regulated the protein abundance of the Ampkα1 isoform, but significantly down-regulated the Ampkα2 isoform in renal tissue. Phosphorylated Ampkα protein levels were significantly increased in obstructed kidney tissue of Ampkα1+/+ mice but not of Ampkα1-/- mice. Renal expression of α-smooth muscle actin was increased following UUO, an effect again less pronounced in Ampkα1-/- mice than in Ampkα1+/+ mice. Histological analysis did not reveal a profound effect of Ampkα1 deficiency on collagen 1 protein deposition. UUO significantly increased phosphorylated and total Tgf-ß-activated kinase 1 (Tak1) protein, as well as transcript levels of Tak1-downstream targets c-Fos, Il6, Pai1 and Snai1 in Ampkα1+/+ mice, effects again significantly ameliorated in Ampkα1-/- mice. Moreover, Ampkα1 deficiency inhibited the UUO-induced mRNA expression of Cd206, a marker of M2 macrophages and of Cxcl16, a pro-fibrotic chemokine associated with myeloid fibroblast formation. The effects of Ampkα1 deficiency during UUO were, however, paralleled by increased tubular injury and apoptosis. Conclusions Renal obstruction induces an isoform shift from Ampkα2 towards Ampkα1, which contributes to the signaling involved in cell survival and fibrosis.
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AMPK-α1 functions downstream of oxidative stress to mediate neuronal atrophy in Huntington's disease. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1668-80. [DOI: 10.1016/j.bbadis.2014.06.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 05/27/2014] [Accepted: 06/09/2014] [Indexed: 01/29/2023]
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22
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Lin D, He H, Ji H, Willis J, Willard L, Jiang Y, Medeiros DM, Wark L, Han J, Liu Y, Lu B. Wolfberries potentiate mitophagy and enhance mitochondrial biogenesis leading to prevention of hepatic steatosis in obese mice: the role of AMP-activated protein kinase α2 subunit. Mol Nutr Food Res 2014; 58:1005-15. [PMID: 24449471 DOI: 10.1002/mnfr.201300186] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 11/10/2013] [Accepted: 11/14/2013] [Indexed: 01/22/2023]
Abstract
SCOPE The aim of this study is to investigate whether AMP-activated protein kinase α2 (AMPKα2) is essential for wolfberry's protective effects on mitochondrial dysfunction and subsequent hepatic steatosis in mice. METHODS AND RESULTS Six-week-old male AMPKα2 knockout mice and genetic background C57BL/6J (B6) mice were fed a control, high-fat diet (HD, 45% (kilocalorie) fat), and/or HD with 5% (kilocalarie) wolfberry diets for 18 wk. At termination, blood and liver tissues were sampled for analysis by ELISA, HPLC, microscopy, real-time PCR, and Western blot. HD lowered hepatic lutein and zeaxanthin contents, inhibited protein expression of β,β-carotene 9',10'-oxygenase 2 (BCO2) and heat shock protein 60 in mitochondria, increased reactive oxygen species level, and suppressed mitophagy and mitochondrial biogenesis as determined by accumulation of p62, inhibited phosphorylation of Unc-51-like kinase 1 on Ser555, and declined expression of peroxisome proliferator-activated receptor γ coactivator 1 α, resulting in hepatic steatosis in B6 and knockout mice. Dietary wolfberry elevated the xanthophyll concentrations and enhanced expression of BCO2 and heat shock protein 60, attenuated mitochondrial oxidative stress, activated AMPKα2, potentiated mitophagy and mitochondrial biogenesis, and enhanced lipid oxidation and secretion in the liver of B6 mice. CONCLUSION Dietary wolfberry selectively activated AMPKα2, which resulted in enhanced mitochondrial biogenesis and potentiated mitophagy, leading to the prevention of hepatic steatosis in obese mice.
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Affiliation(s)
- Dingbo Lin
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK, USA
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Qin S, Lu Y, Rodrigues GA. Resveratrol protects RPE cells from sodium iodate by modulating PPARα and PPARδ. Exp Eye Res 2013; 118:100-8. [PMID: 24309288 DOI: 10.1016/j.exer.2013.11.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 10/01/2013] [Accepted: 11/20/2013] [Indexed: 11/29/2022]
Abstract
Selective killing of RPE cells in vivo by sodium iodate develops cardinal phenotypes of atrophic age-related macular degeneration. However, the molecular mechanisms are elusive. We tried to search for small cyto-protective molecules against sodium iodate and explore their mechanisms of action. Sodium iodate-mediated RPE cell death was associated with increased levels of reactive oxygen species (ROS) and IL-8. Resveratrol, a natural occurring polyphenol compound, was found to strongly protect RPE cells from sodium iodate with inhibition of production of ROS and IL-8. Resveratrol activated all isoforms of PPARs. Treatment with PPARα and PPARδ agonists inhibited sodium iodate-induced ROS production and protected RPE cells from sodium iodate. A PPARα antagonist significantly reduced resveratrol's protection of RPE cells from sodium iodate. Paradoxically, knocking down PPARδ also rendered RPE cells resistant to sodium iodate. Moreover, PPAR agonists reversed sodium iodate-induced production of IL-8. However, neutralizing extracellular IL-8 failed to protect RPE cells from sodium iodate. Taken together, these observations show that resveratrol protects RPE cells from sodium iodate injury through the activation of PPARα and alteration of PPARδ conformation. PPARα and δ modulators might ameliorate stress-induced RPE degeneration in vivo.
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Affiliation(s)
- Suofu Qin
- Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, USA.
| | - Yimin Lu
- Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, USA
| | - Gerard A Rodrigues
- Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, USA
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Autophagy regulating kinases as potential therapeutic targets for age-related macular degeneration. Future Med Chem 2013. [PMID: 23190104 DOI: 10.4155/fmc.12.169] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of central vision loss in the elderly in the developed countries. The number of AMD patients will double during the next decades due to increasing number of aged people. Chronic oxidative stress, inflammation and accumulation of protein-rich deposits both in the retinal pigment epithelium lysosomes and under the retinal pigment epithelium herald the onset of AMD. The disease can be divided into dry and wet AMD forms. The dry form of the disease is more prevalent accounting for up to 90% of all cases. Continued intraocular injections are the current treatment strategy to prevent progression of wet AMD. It is a major challenge to develop new drugs that could prevent or at least ease the symptoms of the increasing population of AMD patients. Since AMD pathology is clearly associated with accumulated protein deposits, the autophagy clearance system might represent a potential future therapeutic target for AMD as is thoroughly discussed here.
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Kaarniranta K, Sinha D, Blasiak J, Kauppinen A, Veréb Z, Salminen A, Boulton ME, Petrovski G. Autophagy and heterophagy dysregulation leads to retinal pigment epithelium dysfunction and development of age-related macular degeneration. Autophagy 2013; 9:973-84. [PMID: 23590900 PMCID: PMC3722332 DOI: 10.4161/auto.24546] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Age-related macular degeneration (AMD) is a complex, degenerative and progressive eye disease that usually does not lead to complete blindness, but can result in severe loss of central vision. Risk factors for AMD include age, genetics, diet, smoking, oxidative stress and many cardiovascular-associated risk factors. Autophagy is a cellular housekeeping process that removes damaged organelles and protein aggregates, whereas heterophagy, in the case of the retinal pigment epithelium (RPE), is the phagocytosis of exogenous photoreceptor outer segments. Numerous studies have demonstrated that both autophagy and heterophagy are highly active in the RPE. To date, there is increasing evidence that constant oxidative stress impairs autophagy and heterophagy, as well as increases protein aggregation and causes inflammasome activation leading to the pathological phenotype of AMD. This review ties together these crucial pathological topics and reflects upon autophagy as a potential therapeutic target in AMD.
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Affiliation(s)
- Kai Kaarniranta
- Department of Ophthalmology; Institute of Clinical Medicine; University of Eastern Finland; Kuopio, Finland; Department of Ophthalmology; Kuopio University Hospital; Kuopio, Finland
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Yu H, Wark L, Ji H, Willard L, Jaing Y, Han J, He H, Ortiz E, Zhang Y, Medeiros DM, Lin D. Dietary wolfberry upregulates carotenoid metabolic genes and enhances mitochondrial biogenesis in the retina of db/db diabetic mice. Mol Nutr Food Res 2013; 57:1158-69. [PMID: 23505020 DOI: 10.1002/mnfr.201200642] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 01/16/2013] [Accepted: 01/16/2013] [Indexed: 12/25/2022]
Abstract
SCOPE Our aim was to investigate whether dietary wolfberry altered carotenoid metabolic gene expression and enhanced mitochondrial biogenesis in the retina of diabetic mice. METHODS AND RESULTS Six-week-old male db/db and wild-type mice were fed the control or wolfberry diets for 8 weeks. At study termination, liver and retinal tissues were collected for analysis by transmission electron microscopy, real-time PCR, immunoprecipitation, Western blot, and HPLC. Wolfberry elevated zeaxanthin and lutein levels in the liver and retinal tissues and stimulated expression of retinal scavenger receptor class B type I, glutathione S-transferase Pi 1, and β,β-carotene 9',10'-oxygenase 2, and induced activation and nuclear enrichment of retinal AMP-activated protein kinase α2 (AMPK-α2). Furthermore, wolfberry attenuated hypoxia and mitochondrial stress as demonstrated by declined expression of hypoxia-inducible factor-1-α, vascular endothelial growth factor, and heat shock protein 60. Wolfberry enhanced retinal mitochondrial biogenesis in diabetic retinas as demonstrated by reversed mitochondrial dispersion in the retinal pigment epithelium, increased mitochondrial copy number, elevated citrate synthase activity, and upregulated expression of peroxisome proliferator-activated receptor γ co-activator 1α, nuclear respiratory factor 1, and mitochondrial transcription factor A. CONCLUSION Consumption of dietary wolfberry could be beneficial to retinoprotection through reversal of mitochondrial function in diabetic mice.
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Affiliation(s)
- Huifeng Yu
- Department of Human Nutrition, Kansas State University, Manhattan, KS, USA
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Qin S. Roles for AMP-Activated Protein Kinase in RPE Cell Function. RETINAL DEGENERATIVE DISEASES 2012; 723:745-51. [DOI: 10.1007/978-1-4614-0631-0_95] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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Hyttinen JMT, Petrovski G, Salminen A, Kaarniranta K. 5'-Adenosine monophosphate-activated protein kinase--mammalian target of rapamycin axis as therapeutic target for age-related macular degeneration. Rejuvenation Res 2011; 14:651-60. [PMID: 22007913 DOI: 10.1089/rej.2011.1220] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Age-related macular degeneration (AMD) is the most common reason for blindness in developed countries. AMD essentially involves chronic oxidative stress, increased accumulation of lipofuscin in retinal pigment epithelial (RPE) cells, and extracellular drusen formation, as well as presence of chronic inflammation in the retina. The capacity to prevent the accumulation of cellular cytotoxic protein aggregates is decreased in senescent cells, which may evoke lipofuscin accumulation into lysosomes in postmitotic RPE cells. The formation of lipofuscin, in turn, decreases the lysosomal enzyme activity and impairs the autophagic clearance of damaged proteins destined for cellular removal. 5'-Adenosine monophosphate-activated protein kinase (AMPK) is a well-known inhibitor of mammalian target of rapamycin (mTOR) that subsequently evokes induction of autophagy. This review examines the novel potential therapeutic targets on the AMPK-mTOR axis and the ways in which autophagy clearance can suppress or prevent RPE degeneration and development of AMD.
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Affiliation(s)
- Juha M T Hyttinen
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O.Box 1627, FI-70211 Kuopio, Finland.
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Chavali VRM, Khan NW, Cukras CA, Bartsch DU, Jablonski MM, Ayyagari R. A CTRP5 gene S163R mutation knock-in mouse model for late-onset retinal degeneration. Hum Mol Genet 2011; 20:2000-14. [PMID: 21349921 DOI: 10.1093/hmg/ddr080] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Late-onset retinal macular degeneration (L-ORD) is an autosomal dominant inherited disorder caused by a single missense mutation (S163R) in the CTRP5/C1QTNF5 protein. Early phenotypic features of L-ORD include: dark adaptation abnormalities, nyctalopia, and drusen deposits in the peripheral macular region. Apart from posterior segment abnormalities, these patients also develop abnormally long anterior lens zonules. In the sixth decade of life the rod and cone function declines, accompanied by electroretinogram (ERG) abnormalities. Some patients also develop choroidal neovascularization and glaucoma. In order to understand the disease pathology and mechanisms involved in retinal dystrophy, we generated a knock-in (Ctrp5(+/-)) mouse model carrying the disease-associated mutation in the mouse Ctrp5/C1QTNF5 gene. These mice develop slower rod-b wave recovery consistent with early dark adaptation abnormalities, accumulation of hyperautofluorescence spots, retinal pigment epithelium abnormalities, drusen, Bruch's membrane abnormalities, loss of photoreceptors, and retinal vascular leakage. The Ctrp5(+/-) mice, which have most of the pathological features of age-related macular degeneration, are unique and may serve as a valuable model both to understand the molecular pathology of late-onset retinal degeneration and to evaluate therapies.
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Qin S. Suofu Qin’s work on studies of cell survival signaling in cancer and epithelial cells. World J Biol Chem 2010; 1:369-76. [PMID: 21537472 PMCID: PMC3083942 DOI: 10.4331/wjbc.v1.i12.369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/21/2010] [Accepted: 10/28/2010] [Indexed: 02/05/2023] Open
Abstract
Reactive oxygen species (ROS) encompass a variety of diverse chemical species including superoxide anions, hydrogen peroxide, hydroxyl radicals and peroxynitrite, which are mainly produced via mitochondrial oxidative metabolism, enzymatic reactions, and light-initiated lipid peroxidation. Over-production of ROS and/or decrease in the antioxidant capacity cause cells to undergo oxidative stress that damages cellular macromolecules such as proteins, lipids, and DNA. Oxidative stress is associated with ageing and the development of age-related diseases such as cancer and age-related macular degeneration. ROS activate signaling pathways that promote cell survival or lead to cell death, depending on the source and site of ROS production, the specific ROS generated, the concentration and kinetics of ROS generation, and the cell types being challenged. However, how the nature and compartmentalization of ROS contribute to the pathogenesis of individual diseases is poorly understood. Consequently, it is crucial to gain a comprehensive understanding of the molecular bases of cell oxidative stress signaling, which will then provide novel therapeutic opportunities to interfere with disease progression via targeting specific signaling pathways. Currently, Dr. Qin’s work is focused on inflammatory and oxidative stress responses using the retinal pigment epithelial (RPE) cells as a model. The study of RPE cell inflammatory and oxidative stress responses has successfully led to a better understanding of RPE cell biology and identification of potential therapeutic targets.
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Affiliation(s)
- Suofu Qin
- Suofu Qin, Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612-1599, United States
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Hien TT, Kim HG, Han EH, Kang KW, Jeong HG. Molecular mechanism of suppression of MDR1 by puerarin from Pueraria lobata via NF-kappaB pathway and cAMP-responsive element transcriptional activity-dependent up-regulation of AMP-activated protein kinase in breast cancer MCF-7/adr cells. Mol Nutr Food Res 2010; 54:918-28. [PMID: 20077420 DOI: 10.1002/mnfr.200900146] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Multidrug resistance (MDR) is a major obstacle in cancer chemotherapy and its inhibition is an effective way to reverse cancer drug resistance. In the present study, we investigated that puerarin, a natural isoflavonoid from Pueraria lobata, down-regulated MDR1 expression in MCF-7/adriamycin (MCF-7/adr), a human breast MDR cancer cell line. Puerarin treatment significantly inhibited MDR1 expression, MDR1 mRNA and MDR1 promoter activity in MCF-7/adr cells. The suppression of MDR1 was accompanied by partial recovery of intracellular drug accumulation, leading to increased toxicity of adriamycin and fluorescence of rhodamine 123, indicating that puerarin reversed the MDR phenotype by inhibiting the drug efflux function of MDR1. Moreover, nuclear factor kappa-B activity and IkappaB degradation were inhibited by puerarin. Puerarin stimulated AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase and glycogen synthase kinase-3beta phosphorylation, but puerarin decreased cAMP-responsive element-binding protein phosphorylation. The puerarin-induced suppression of MDR1 expression was reduced by AMPK inhibitor (compound C). Furthermore, both MDR1 protein expression and the transcriptional activity of cAMP-responsive element (CRE) were inhibited by puerarin and protein kinase A/CRE inhibitor (H89). Taken together, our results suggested that puerarin down-regulated MDR1 expression via nuclear factor kappa-B and CRE transcriptional activity-dependent up-regulation of AMPK in MCF-7/adr cells.
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Affiliation(s)
- Tran Thi Hien
- College of Pharmacy, Chosun University, Gwangju, Republic of Korea
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Qin S, Rodrigues GA. Differential roles of AMPKα1 and AMPKα2 in regulating 4-HNE-induced RPE cell death and permeability. Exp Eye Res 2010; 91:818-24. [PMID: 21029733 DOI: 10.1016/j.exer.2010.10.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 09/18/2010] [Accepted: 10/18/2010] [Indexed: 11/30/2022]
Abstract
Lipid peroxidation products such as 4-hydroxy-2-nonenal (4-HNE) cause dysfunction and death of retinal pigmented epithelial (RPE) cells, thereby leading to retinal degeneration. The molecular mechanisms underlying their action remain elusive however. In this study, the roles of AMP-activated protein kinase (AMPK) in 4-HNE-induced RPE cell dysfunction and viability were addressed. 4-HNE caused RPE cell death and down-regulated basal activity of AMPK as evidenced by decreased Thr(172) phosphorylation of AMPKα. Exposure of RPE cells to the AMPK inhibitor, compound C also led to cell death, indicating that RPE cell death is correlated with 4-HNE modulation of AMPK activity. ARPE19 cells express both AMPKα1 and AMPKα2 with predominant expression of the AMPKα1 isoform. siRNA studies revealed that knockdown of AMPKα1 expression sensitized RPE cells to 4-HNE. Intriguingly, knockdown of AMPKα2 protected RPE cells from 4-HNE injury. Sub-lethal doses of 4-HNE induced an increase in RPE monolayer permeability, as measured by reduction in trans-epithelial resistance (TER). Knockdown of AMPKα2 but not AMPKα1 significantly restored RPE cell barrier function. No further protection was observed by knockdown of both AMPKα1 and AMPKα2. In contrast, knockdown of AMPKα1 and/or AMPKα2 did not reverse the 4-HNE's inhibitory effects on production of IL-8 and MCP-1. These data demonstrate that AMPKα1 and AMPKα2 play distinct roles in regulating 4-HNE effects on RPE function and viability. Therefore, selective modulation of AMPKα activity may benefit patients with retinal degeneration associated with RPE cell atrophy.
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Affiliation(s)
- Suofu Qin
- Retinal Disease Research, Department of Biological Sciences, Allergan, Inc., 2525 Dupont Drive, Irvine, CA 92612, USA.
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Kaczara P, Sarna T, Burke JM. Dynamics of H2O2 availability to ARPE-19 cultures in models of oxidative stress. Free Radic Biol Med 2010; 48:1064-70. [PMID: 20100568 PMCID: PMC2839027 DOI: 10.1016/j.freeradbiomed.2010.01.022] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 12/14/2009] [Accepted: 01/15/2010] [Indexed: 11/23/2022]
Abstract
Oxidative injury to cells such as the retinal pigment epithelium (RPE) is often modeled using H(2)O(2)-treated cultures, but H(2)O(2) concentrations are not sustained in culture medium. Here medium levels of H(2)O(2) and cytotoxicity were analyzed in ARPE-19 cultures after H(2)O(2) delivery as a single pulse or with continuous generation using glucose oxidase (GOx). When added as a pulse, H(2)O(2) is rapidly depleted (within 2 h); cytotoxicity at 24 h, determined by the MTT assay for mitochondrial function, is unaffected by medium replacement at 2 h. Continuous generation of H(2)O(2) produces complex outcomes. At low GOx concentrations, H(2)O(2) levels are sustained by conditions under which generation matches depletion, but when GOx concentrations produce cytotoxic levels of H(2)O(2), oxidant depletion accelerates. Acceleration results partly from the release of contents from oxidant-damaged cells as indicated by testing depletion after controlled membrane disruption with detergents. Cytotoxicity analyses show that cells can tolerate short exposure to high H(2)O(2) doses delivered as a pulse but are susceptible to lower chronic doses. The results provide broadly applicable guidance for using GOx to produce sustained H(2)O(2) levels in cultured cells. This approach will be specifically useful for modeling chronic stress relevant to RPE aging and have a wider value for studying cellular effects of sublethal oxidant injury and for evaluating antioxidants that may protect significantly against mild but not lethal stress.
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Affiliation(s)
- Patrycja Kaczara
- Department of Biophysics, Jagiellonian University, Kraków, Poland
| | - Tadeusz Sarna
- Department of Biophysics, Jagiellonian University, Kraków, Poland
| | - Janice M. Burke
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI
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Tomlinson ML, Rejzek M, Fidock M, Field RA, Wheeler GN. Chemical genomics identifies compounds affecting Xenopus laevis pigment cell development. MOLECULAR BIOSYSTEMS 2009; 5:376-84. [DOI: 10.1039/b818695b] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Iriyama A, Iriyama T, Tamaki Y, Yanagi Y. Effects of white light on β-catenin signaling pathway in retinal pigment epithelium. Biochem Biophys Res Commun 2008; 375:173-7. [DOI: 10.1016/j.bbrc.2008.07.158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 07/31/2008] [Indexed: 10/21/2022]
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Thors B, Halldórsson H, Jónsdóttir G, Thorgeirsson G. Mechanism of thrombin mediated eNOS phosphorylation in endothelial cells is dependent on ATP levels after stimulation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1893-902. [PMID: 18687367 DOI: 10.1016/j.bbamcr.2008.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Revised: 07/04/2008] [Accepted: 07/08/2008] [Indexed: 10/21/2022]
Abstract
Conflicting results have been reported concerning the role of AMP-activated protein kinase (AMPK) in mediating thrombin stimulation of endothelial NO-synthase (eNOS). We examined the involvement of two upstream kinases in AMPK activation in cultured human umbilical endothelial cells, LKB1 stimulated by a rise in intracellular AMP/ATP ratio, and Ca(+2)/CaM kinase kinase (CaMKK) responding to elevation of intracellular Ca(+2). We also studied the effects of AMPK activation on the downstream target eNOS. In culture medium 1640 the level of intracellular ATP was unchanged after thrombin stimulation and the CaMKK inhibitor STO-609 totally inhibited phosphorylation of AMPK and acetyl coenzyme A carboxylase (ACC) but not eNOS. In Morgan's medium 199 thrombin caused a significant lowering of intracellular ATP and STO-609 only partially inhibited the phosphorylation of AMPK, ACC and eNOS. Inhibition of AMPK by Compound C or AMPK downregulation using siRNA partially inhibited the phosphorylation of eNOS in medium 199 but not in 1640, underscoring a clear difference in the pathways mediating thrombin-stimulated eNOS phosphorylation in different culture media. Thus, conditions subjecting endothelial cells to a fall in ATP after thrombin stimulation facilitate activation of pathways partly dependent on AMPK causing downstream phosphorylation of eNOS. In contrast, under culture conditions that do not facilitate a fall in ATP after stimulation, AMPK activation is exclusively mediated by CaMKK and does not contribute to the phosphorylation of eNOS.
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Affiliation(s)
- Brynhildur Thors
- Institute of Pharmacy, Pharmacology and Toxicology, University of Iceland, Hagi Hofsvallagotu 53, Reykjavik, Iceland
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