1
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Puddu A, Maggi DC. Klotho: A new therapeutic target in diabetic retinopathy? World J Diabetes 2023; 14:1027-1036. [PMID: 37547589 PMCID: PMC10401458 DOI: 10.4239/wjd.v14.i7.1027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/12/2023] [Accepted: 05/22/2023] [Indexed: 07/12/2023] Open
Abstract
Klotho (Kl) is considered an antiaging gene, mainly for the inhibition of the insulin-like growth factor-1 signaling. Kl exists as full-length transmembrane, which acts as co-receptor for fibroblast growth factor receptor, and in soluble forms (sKl). The sKl may exert pleiotropic effects on organs and tissues by regulating several pathways involved in the pathogenesis of diseases associated with oxidative and inflammatory state. In diabetic Patients, serum levels of Kl are significantly decreased compared to healthy subjects, and are related to duration of diabetes. In diabetic retinopathy (DR), one of the most common microvascular complications of type 2 diabetes, serum Kl levels are negatively correlated with progression of the disease. A lot of evidences showed that Kl regulates several mechanisms involved in maintaining homeostasis and functions of retinal cells, including phagocytosis, calcium signaling, secretion of vascular endothelial growth factor A (VEGF-A), maintenance of redox status, and melanin biosynthesis. Experimental data have been shown that Kl exerts positive effects on several mechanisms involved in onset and progression of DR. In particular, treatment with Kl: (1) Prevents apoptosis induced by oxidative stress in human retinal endothelial cells and in retinal pigment epithelium (RPE) cells; (2) reduces secretion of VEGF-A by RPE cells; and (3) decreases subretinal fibrosis and preserves autophagic activity. Therefore, Kl may become a novel biomarker and a good candidate for the treatment of DR.
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Affiliation(s)
- Alessandra Puddu
- Department of Internal Medicine and Medical Specialties, University of Genova, Genova 16132, Italy
| | - Davide Carlo Maggi
- Department of Internal Medicine and Medical Specialties, University of Genova, Genova 16132, Italy
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2
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Hashikawa KI, Tsuruta A, Yamakawa W, Yasukochi S, Koyanagi S, Ohdo S. Senescence-induced alteration of circadian phagocytic activity of retinal pigment epithelium cell line ARPE-19. Biochem Biophys Res Commun 2023; 658:88-96. [PMID: 37027909 DOI: 10.1016/j.bbrc.2023.03.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 03/29/2023] [Indexed: 03/31/2023]
Abstract
Renewal of retinal photoreceptor outer segments is conducted through daily shedding of distal photoreceptor outer segment tips and subsequent their phagocytosis by the adjacent retinal pigment epithelium (RPE) monolayer. Dysregulation of the diurnal clearance of photoreceptor outer segment tips has been implicated in age-related retinal degeneration, but it remains to be clarified how the circadian phagocytic activity of RPE cells is modulated by senescence. In this study, we used the human RPE cell line ARPE-19 to investigate whether hydrogen peroxide (H2O2)-induced senescence in ARPE-19 cells alters the circadian rhythm of their phagocytic activity. After synchronization of the cellular circadian clock by dexamethasone treatment, the phagocytic activity of normal ARPE-19 cells exhibited significant 24-h oscillation, but this oscillation was modulated by senescence. The phagocytic activity of senescent ARPE-19 cells increased constantly throughout the 24-h period, which still exhibited blunted circadian oscillation, accompanied by an alteration in the rhythmic expression of circadian clock genes and clock-controlled phagocytosis-related genes. The expression levels of REV-ERBα, a molecular component of the circadian clock, were constitutively increased in senescent ARPE-19 cells. Furthermore, pharmacological activation of REV-ERBα by its agonist SR9009 enhanced the phagocytic activity of normal ARPE-19 cells and increased the expression of clock-controlled phagocytosis-related genes. Our present findings extend to understand the role of circadian clock in the alteration of phagocytic activity in RPE during aging. Constitutive enhancement of phagocytic activity of senescent RPE may contribute to age-related retinal degeneration.
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Affiliation(s)
- Ken-Ichi Hashikawa
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Akito Tsuruta
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan; Department of Glocal Healthcare Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Wakaba Yamakawa
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Sai Yasukochi
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Satoru Koyanagi
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan; Department of Glocal Healthcare Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
| | - Shigehiro Ohdo
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
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3
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Karema-Jokinen V, Koskela A, Hytti M, Hongisto H, Viheriälä T, Liukkonen M, Torsti T, Skottman H, Kauppinen A, Nymark S, Kaarniranta K. Crosstalk of protein clearance, inflammasome, and Ca 2+ channels in retinal pigment epithelium derived from age-related macular degeneration patients. J Biol Chem 2023:104770. [PMID: 37137441 DOI: 10.1016/j.jbc.2023.104770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 04/21/2023] [Accepted: 04/23/2023] [Indexed: 05/05/2023] Open
Abstract
Degeneration and/or dysfunction of retinal pigment epithelium (RPE) is generally detected as the formation of intra- and extracellular protein aggregates, called lipofuscin and drusen, respectively, in patients with age-related macular degeneration (AMD), the leading cause of blindness in the elderly population. These clinical hallmarks are linked to dysfunctional protein homeostasis and inflammation, and furthermore, are both regulated by changes in intracellular Ca2+ concentration. While many other cellular mechanisms have been considered in the investigations of AMD-RPE, there has been relatively little work on understanding the interactions of protein clearance, inflammation, and Ca2+ dynamics in disease pathogenesis. Here we established induced pluripotent stem cell-derived RPE from two patients with advanced AMD and from an age- and gender-matched control subject. We studied autophagy and inflammasome activation under disturbed proteostasis in these cell lines and investigated changes in their intracellular Ca2+ concentration and L-type voltage-gated Ca2+ channels. Our work demonstrated dysregulated autophagy and inflammasome activation in AMD-RPE accompanied by reduced intracellular free Ca2+ levels. Interestingly, we found currents through L-type voltage-gated Ca2+ channels to be diminished and showed these channels to be significantly localized to intracellular compartments in AMD-RPE. Taken together, the alterations in Ca2+ dynamics in AMD-RPE together with dysregulated autophagy and inflammasome activation indicate an important role for Ca2+ signaling in AMD pathogenesis, providing new avenues for the development of therapeutic approaches.
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Affiliation(s)
| | - Ali Koskela
- Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland
| | - Maria Hytti
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Heidi Hongisto
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland; Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland
| | - Taina Viheriälä
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Mikko Liukkonen
- Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland
| | - Tommi Torsti
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Heli Skottman
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Anu Kauppinen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Soile Nymark
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
| | - Kai Kaarniranta
- Department of Ophthalmology, University of Eastern Finland, Kuopio, Finland; Department of Ophthalmology, Kuopio University Hospital, Finland, Immuno-Ophthalmology, School of Pharmacy, University of Eastern Finland, Kuopio, Finland; Department of Molecular Genetics, University of Lodz, Lodz, Poland.
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4
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Ignatova I, Frolov R, Nymark S. The retinal pigment epithelium displays electrical excitability and lateral signal spreading. BMC Biol 2023; 21:84. [PMID: 37069561 PMCID: PMC10111697 DOI: 10.1186/s12915-023-01559-5] [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: 04/01/2022] [Accepted: 03/10/2023] [Indexed: 04/19/2023] Open
Abstract
BACKGROUND The non-neuronal retinal pigment epithelium (RPE) functions in intimate association with retinal photoreceptors, performing a multitude of tasks critical for maintaining retinal homeostasis and collaborating with retinal glial cells to provide metabolic support and ionic buffering. Accordingly, the RPE has recently been shown to display dynamic properties mediated by an array of ion channels usually more characteristic of astrocytes and excitable cells. The recent discovery of canonical voltage-activated Na+ channels in the RPE and their importance for phagocytosis of photoreceptor outer segments raises a question about their electrogenic function. Here, we performed a detailed electrophysiological analysis related to the functioning of these channels in human embryonic stem cell (hESC)-derived RPE. RESULTS Our studies examining the electrical properties of the hESC-RPE revealed that its membrane mainly displays passive properties in a broad voltage range, with the exception of depolarization-induced spikes caused by voltage-activated Na+ current (INa). Spike amplitude depended on the availability of INa and spike kinetics on the membrane time constant, and the spikes could be largely suppressed by TTX. Membrane resistance fluctuated rapidly and strongly, repeatedly changing over the course of recordings and causing closely correlated fluctuations in resting membrane potential. In a minority of cells, we found delayed secondary INa-like inward currents characterized by comparatively small amplitudes and slow kinetics, which produced secondary depolarizing spikes. Up to three consecutive delayed inward current waves were detected. These currents could be rapidly and reversibly augmented by applying L-type Ca2+ channel blocker nifedipine to diminish influx of calcium and thus increase gap junctional conductance. CONCLUSIONS This work shows, for the first time, that INa and INa-mediated voltage spikes can spread laterally through gap junctions in the monolayer of cells that are traditionally considered non-excitable. Our findings support a potential role of the RPE that goes beyond giving homeostatic support to the retina.
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Affiliation(s)
- Irina Ignatova
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | | | - Soile Nymark
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
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5
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Cellular and Molecular Mechanisms of Pathogenesis Underlying Inherited Retinal Dystrophies. Biomolecules 2023; 13:biom13020271. [PMID: 36830640 PMCID: PMC9953031 DOI: 10.3390/biom13020271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/23/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Inherited retinal dystrophies (IRDs) are congenital retinal degenerative diseases that have various inheritance patterns, including dominant, recessive, X-linked, and mitochondrial. These diseases are most often the result of defects in rod and/or cone photoreceptor and retinal pigment epithelium function, development, or both. The genes associated with these diseases, when mutated, produce altered protein products that have downstream effects in pathways critical to vision, including phototransduction, the visual cycle, photoreceptor development, cellular respiration, and retinal homeostasis. The aim of this manuscript is to provide a comprehensive review of the underlying molecular mechanisms of pathogenesis of IRDs by delving into many of the genes associated with IRD development, their protein products, and the pathways interrupted by genetic mutation.
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6
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Fadjukov J, Wienbar S, Hakanen S, Aho V, Vihinen-Ranta M, Ihalainen TO, Schwartz GW, Nymark S. Gap junctions and connexin hemichannels both contribute to the electrical properties of retinal pigment epithelium. J Gen Physiol 2022; 154:213064. [PMID: 35275193 PMCID: PMC8922333 DOI: 10.1085/jgp.202112916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 02/17/2022] [Indexed: 12/13/2022] Open
Abstract
Gap junctions are intercellular channels that permit the transfer of ions and small molecules between adjacent cells. These cellular junctions are particularly dense in the retinal pigment epithelium (RPE), and their contribution to many retinal diseases has been recognized. While gap junctions have been implicated in several aspects of RPE physiology, their role in shaping the electrical properties of these cells has not been characterized in mammals. The role of gap junctions in the electrical properties of the RPE is particularly important considering the growing appreciation of RPE as excitable cells containing various voltage-gated channels. We used a whole-cell patch clamp to measure the electrical characteristics and connectivity between RPE cells, both in cultures derived from human embryonic stem cells and in the intact RPE monolayers from mouse eyes. We found that the pharmacological blockade of gap junctions eliminated electrical coupling between RPE cells, and that the blockade of gap junctions or Cx43 hemichannels significantly increased their input resistance. These results demonstrate that gap junctions function in the RPE not only as a means of molecular transport but also as a regulator of electrical excitability.
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Affiliation(s)
- Julia Fadjukov
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Sophia Wienbar
- Department of Ophthalmology, Northwestern University, Chicago, IL.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL.,Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL
| | - Satu Hakanen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Vesa Aho
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Maija Vihinen-Ranta
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Teemu O Ihalainen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Gregory W Schwartz
- Department of Ophthalmology, Northwestern University, Chicago, IL.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL.,Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL
| | - Soile Nymark
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
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7
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Hu L, Xu G. Potential Protective Role of TRPM7 and Involvement of PKC/ERK Pathway in Blue Light-Induced Apoptosis in Retinal Pigment Epithelium Cells in Vitro. Asia Pac J Ophthalmol (Phila) 2021; 10:572-578. [PMID: 34789674 PMCID: PMC8673846 DOI: 10.1097/apo.0000000000000447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/15/2021] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Blue light triggers apoptosis of retinal pigment epithelium (RPE) cells and causes retinal damage. The aim of this study was to elucidate the protective role of transient receptor potential melastatin 7 (TRPM7) in photodamaged RPE cells. METHODS RPE cells were isolated from Sprague-Dawley (SD) rats and exposed to varying intensities of blue light (500-5000 lux) in vitro. Cell proliferation and metabolic activity were respectively assessed by bromodeoxyuridine (BrdU) incorporation and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. Real-time polymerase chain reaction (RT-PCR) and western blotting were used to analyze the TRPM7, protein kinase C (PKC), extracellular signal-regulated kinase (ERK) and Bcl2-associated x/B-cell lymphoma 2 (Bax/Bcl-2) messenger RNA (mRNA) and protein expression levels. The cells were transfected with TRPM7 small interfering RNA (siRNA) or transduced with TRPM7-overexpressing lentiviruses and cultured with or without the pigment epithelium-derived factor (PEDF). RESULTS Blue light inhibited the proliferation and metabolic activity of RPE cells in an intensity-dependent manner when compared to nonirradiated controls (P < 0.05). Compared to the control, photodamaged RPE cells showed decreased levels of TRPM7, PKC, ERK, and Bax, and an increase in Bcl-2 levels (P < 0.01). Forced expression of TRPM7 partially rescued the proliferative capacity of RPE cells (P < 0.01) and restored the levels of TRPM7, PKC, ERK, and Bax (P < 0.01), whereas TRPM7 knockdown had the opposite effects (P < 0.01). TRPM7 and PEDF synergistically alleviated the damaging effects of blue light. CONCLUSIONS Blue light triggers apoptosis of RPE cells, and its deleterious effects can be partially attenuated by the synergistic action of TRPM7 and PEDF via the PKC/ERK signaling pathway.
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Affiliation(s)
- Luping Hu
- First Affiliated Hospital of Fujian Medical University, 20 Chazhong Road, Fuzhou City 350005, China
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8
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Acute RhoA/Rho Kinase Inhibition Is Sufficient to Restore Phagocytic Capacity to Retinal Pigment Epithelium Lacking the Engulfment Receptor MerTK. Cells 2021; 10:cells10081927. [PMID: 34440696 PMCID: PMC8394172 DOI: 10.3390/cells10081927] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 12/27/2022] Open
Abstract
The diurnal phagocytosis of spent photoreceptor outer segment fragments (POS) by retinal pigment epithelial (RPE) cells is essential for visual function. POS internalization by RPE cells requires the assembly of F-actin phagocytic cups beneath surface-tethered POS and Mer tyrosine kinase (MerTK) signaling. The activation of the Rho family GTPase Rac1 is necessary for phagocytic cup formation, and Rac1 is activated normally in MerTK-deficient RPE. We show here that mutant RPE lacking MerTK and wild-type RPE deprived of MerTK ligand both fail to form phagocytic cups regardless of Rac1 activation. However, in wild-type RPE in vivo, a decrease in RhoA activity coincides with the daily phagocytosis burst, while RhoA activity in MerTK-deficient RPE is constant. Elevating RhoA activity blocks phagocytic cup formation and phagocytosis by wild-type RPE. Conversely, inhibiting RhoA effector Rho kinases (ROCKs) rescues both F-actin assembly and POS internalization of primary RPE if MerTK or its ligand are lacking. Most strikingly, acute ROCK inhibition is sufficient to induce the formation and acidification of endogenous POS phagosomes by MerTK-deficient RPE ex vivo. Altogether, RhoA pathway inactivation is a necessary and sufficient downstream effect of MerTK phagocytic signaling such that the acute manipulation of cytosolic ROCK activity suffices to restore phagocytic capacity to MerTK-deficient RPE.
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9
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Kilicarslan I, Zanetti L, Novelli E, Schwarzer C, Strettoi E, Koschak A. Knockout of Ca V1.3 L-type calcium channels in a mouse model of retinitis pigmentosa. Sci Rep 2021; 11:15146. [PMID: 34312410 PMCID: PMC8313562 DOI: 10.1038/s41598-021-94304-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/09/2021] [Indexed: 11/09/2022] Open
Abstract
Retinitis Pigmentosa is a genetically heterogeneous, degenerative retinal disorder characterized by gradual dysfunction and death of photoreceptors, first rods and later cones, and progressive blindness. Studies suggested that application of L-type calcium channel blockers rescues photoreceptors in paradigms related to Ca2+ overflow. To investigate whether Cav1.3 L-type channels have protective effects in the retina, we established a new mouse model by crossing rd10, modeling autosomal-recessive RP, with Cav1.3 deficient mice (rd10/Cav1.3KO). Our immunohistochemical analyses revealed an influence of Cav1.3 channels on the degenerative process of photoreceptors. The absence of Cav1.3 delayed the centre-to-periphery degeneration of rods indicated by a significantly higher number of photoreceptor rows and, consequently, of cones. In accordance with a preserved number of cones we observed a regular row of cone somas in rd10/Cav1.3-KO retinas. Surviving rod photoreceptors maintained synaptic contacts with rod bipolar cells. However, the delay in degeneration was only observed up to postnatal day 45. Although we observed a reduction in the spontaneous oscillatory retinal activity during multielectrode array analyses, measurable functional preservation was lacking in behavioural tests. In conclusion, Cav1.3 channels contribute to photoreceptor degeneration in rd10 retinas but photoreceptor temporary rescue might rather be achieved indirectly through other retinal cell layers.
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Affiliation(s)
- Irem Kilicarslan
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria
| | - Lucia Zanetti
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria
| | | | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, 6020, Innsbruck, Austria
| | - Enrica Strettoi
- CNR Neuroscience Institute, 56124, Pisa, Italy. .,Istituto Di Neuroscienze CNR, Area della Ricerca, Via Giuseppe Moruzzi 1, 56100, Pisa, Italy.
| | - Alexandra Koschak
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
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10
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Milićević N, Ait-Hmyed Hakkari O, Bagchi U, Sandu C, Jongejan A, Moerland PD, Ten Brink JB, Hicks D, Bergen AA, Felder-Schmittbuhl MP. Core circadian clock genes Per1 and Per2 regulate the rhythm in photoreceptor outer segment phagocytosis. FASEB J 2021; 35:e21722. [PMID: 34160105 DOI: 10.1096/fj.202100293rr] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/13/2021] [Accepted: 05/24/2021] [Indexed: 02/07/2023]
Abstract
Retinal photoreceptors undergo daily renewal of their distal outer segments, a process indispensable for maintaining retinal health. Photoreceptor outer segment (POS) phagocytosis occurs as a daily peak, roughly about 1 hour after light onset. However, the underlying cellular and molecular mechanisms which initiate this process are still unknown. Here we show that, under constant darkness, mice deficient for core circadian clock genes (Per1 and Per2) lack a daily peak in POS phagocytosis. By qPCR analysis, we found that core clock genes were rhythmic over 24 hours in both WT and Per1, Per2 double mutant whole retinas. More precise transcriptomics analysis of laser capture microdissected WT photoreceptors revealed no differentially expressed genes between time points preceding and during the peak of POS phagocytosis. In contrast, we found that microdissected WT retinal pigment epithelium (RPE) had a number of genes that were differentially expressed at the peak phagocytic time point compared to adjacent ones. We also found a number of differentially expressed genes in Per1, Per2 double mutant RPE compared to WT ones at the peak phagocytic time point. Finally, based on STRING analysis, we found a group of interacting genes that potentially drive POS phagocytosis in the RPE. This potential pathway consists of genes such as: Pacsin1, Syp, Camk2b, and Camk2d among others. Our findings indicate that Per1 and Per2 are necessary clock components for driving POS phagocytosis and suggest that this process is transcriptionally driven by the RPE.
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Affiliation(s)
- Nemanja Milićević
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.,Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Ouafa Ait-Hmyed Hakkari
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Udita Bagchi
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.,Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Cristina Sandu
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Aldo Jongejan
- Bioinformatics Laboratory, Department of Epidemiology and Data Science, Amsterdam Public Health Research Institute, Amsterdam UMC, Amsterdam, the Netherlands
| | - Perry D Moerland
- Bioinformatics Laboratory, Department of Epidemiology and Data Science, Amsterdam Public Health Research Institute, Amsterdam UMC, Amsterdam, the Netherlands
| | - Jacoline B Ten Brink
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - David Hicks
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| | - Arthur A Bergen
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.,Department of Ophthalmology, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.,Netherlands Institute for Neuroscience (NIN-KNAW), Amsterdam, the Netherlands
| | - Marie-Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
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11
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Mamaeva D, Jazouli Z, DiFrancesco ML, Erkilic N, Dubois G, Hilaire C, Meunier I, Boukhaddaoui H, Kalatzis V. Novel roles for voltage-gated T-type Ca 2+ and ClC-2 channels in phagocytosis and angiogenic factor balance identified in human iPSC-derived RPE. FASEB J 2021; 35:e21406. [PMID: 33724552 DOI: 10.1096/fj.202002754r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/13/2021] [Accepted: 01/19/2021] [Indexed: 01/26/2023]
Abstract
Human-induced pluripotent stem cell (hiPSC)-derived retinal pigment epithelium (RPE) is a powerful tool for pathophysiological studies and preclinical therapeutic screening, as well as a source for clinical cell transplantation. Thus, it must be validated for maturity and functionality to ensure correct data readouts and clinical safety. Previous studies have validated hiPSC-derived RPE as morphologically characteristic of the tissue in the human eye. However, information concerning the expression and functionality of ion channels is still limited. We screened hiPSC-derived RPE for the polarized expression of a panel of L-type (CaV 1.1, CaV 1.3) and T-type (CaV 3.1, CaV 3.3) Ca2+ channels, K+ channels (Maxi-K, Kir4.1, Kir7.1), and the Cl- channel ClC-2 known to be expressed in native RPE. We also tested the roles of these channels in key RPE functions using specific inhibitors. In addition to confirming the native expression profiles and function of certain channels, such as L-type Ca2+ channels, we show for the first time that T-type Ca2+ channels play a role in both phagocytosis and vascular endothelial growth factor (VEGF) secretion. Moreover, we demonstrate that Maxi-K and Kir7.1 channels are involved in the polarized secretion of VEGF and pigment epithelium-derived factor (PEDF). Furthermore, we show a novel localization for ClC-2 channel on the apical side of hiPSC-derived RPE, with an overexpression at the level of fluid-filled domes, and demonstrate that it plays an important role in phagocytosis, as well as VEGF and PEDF secretion. Taken together, hiPSC-derived RPE is a powerful model for advancing fundamental knowledge of RPE functions.
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Affiliation(s)
- Daria Mamaeva
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France
| | - Zhour Jazouli
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France
| | - Mattia L DiFrancesco
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France
| | - Nejla Erkilic
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France.,National Reference Centre for Inherited Sensory Diseases, Montpellier University, CHU, Montpellier, France
| | - Gregor Dubois
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France
| | - Cecile Hilaire
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France
| | - Isabelle Meunier
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France.,National Reference Centre for Inherited Sensory Diseases, Montpellier University, CHU, Montpellier, France
| | - Hassan Boukhaddaoui
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France
| | - Vasiliki Kalatzis
- Institute for Neurosciences of Montpellier, Inserm, Montpellier University, Montpellier, France
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12
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A Human Retinal Pigment Epithelium-Based Screening Platform Reveals Inducers of Photoreceptor Outer Segments Phagocytosis. Stem Cell Reports 2020; 15:1347-1361. [PMID: 33242397 PMCID: PMC7724476 DOI: 10.1016/j.stemcr.2020.10.013] [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: 08/21/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 11/20/2022] Open
Abstract
Phagocytosis is a key function in various cells throughout the body. A deficiency in photoreceptor outer segment (POS) phagocytosis by the retinal pigment epithelium (RPE) causes vision loss in inherited retinal diseases and possibly age-related macular degeneration. To date, there are no effective therapies available aiming at recovering the lost phagocytosis function. Here, we developed a high-throughput screening assay based on RPE derived from human embryonic stem cells (hRPE) to reveal enhancers of POS phagocytosis. One of the hits, ramoplanin (RM), reproducibly enhanced POS phagocytosis and ensheathment in hRPE, and enhanced the expression of proteins known to regulate membrane dynamics and ensheathment in other cell systems. Additionally, RM rescued POS internalization defect in Mer receptor tyrosine kinase (MERTK) mutant hRPE, derived from retinitis pigmentosa patient induced pluripotent stem cells. Our platform, including a primary phenotypic screening phagocytosis assay together with orthogonal assays, establishes a basis for RPE-based therapy discovery aiming at a broad patient spectrum.
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13
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Phosphoinositides in Retinal Function and Disease. Cells 2020; 9:cells9040866. [PMID: 32252387 PMCID: PMC7226789 DOI: 10.3390/cells9040866] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 02/06/2023] Open
Abstract
Phosphatidylinositol and its phosphorylated derivatives, the phosphoinositides, play many important roles in all eukaryotic cells. These include modulation of physical properties of membranes, activation or inhibition of membrane-associated proteins, recruitment of peripheral membrane proteins that act as effectors, and control of membrane trafficking. They also serve as precursors for important second messengers, inositol (1,4,5) trisphosphate and diacylglycerol. Animal models and human diseases involving defects in phosphoinositide regulatory pathways have revealed their importance for function in the mammalian retina and retinal pigmented epithelium. New technologies for localizing, measuring and genetically manipulating them are revealing new information about their importance for the function and health of the vertebrate retina.
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14
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Cordes M, Bucichowski P, Alfaar AS, Tsang SH, Almedawar S, Reichhart N, Strauß O. Inhibition of Ca 2+ channel surface expression by mutant bestrophin-1 in RPE cells. FASEB J 2020; 34:4055-4071. [PMID: 31930599 DOI: 10.1096/fj.201901202rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 12/09/2019] [Accepted: 12/31/2019] [Indexed: 01/11/2023]
Abstract
The BEST1 gene product bestrophin-1, a Ca2+ -dependent anion channel, interacts with CaV 1.3 Ca2+ channels in the retinal pigment epithelium (RPE). BEST1 mutations lead to Best vitelliform macular dystrophy. A common functional defect of these mutations is reduced trafficking of bestrophin-1 into the plasma membrane. We hypothesized that this defect affects the interaction partner CaV 1.3 channel affecting Ca2+ signaling and altered RPE function. Thus, we investigated the protein interaction between CaV 1.3 channels and bestrophin-1 by immunoprecipitation, CaV 1.3 activity in the presence of mutant bestrophin-1 and intracellular trafficking of the interaction partners in confluent RPE monolayers. We selected four BEST1 mutations, each representing one mutational hotspot of the disease: T6P, F80L, R218C, and F305S. Heterologously expressed L-type channels and mutant bestrophin-1 showed reduced interaction, reduced CaV 1.3 channel activity, and changes in surface expression. Transfection of polarized RPE (porcine primary cells, iPSC-RPE) that endogenously express CaV 1.3 and wild-type bestrophin-1, with mutant bestrophin-1 confirmed reduction of CaV 1.3 surface expression. For the four selected BEST1 mutations, presence of mutant bestrophin-1 led to reduced CaV 1.3 activity by modulating pore-function or decreasing surface expression. Reduced CaV 1.3 activity might open new ways to understand symptoms of Best vitelliform macular dystrophy such as reduced electro-oculogram, lipofuscin accumulation, and vision impairment.
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Affiliation(s)
- Magdalena Cordes
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
| | - Piotr Bucichowski
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
| | - Ahmad S Alfaar
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
| | - Stephen H Tsang
- Jonas Children's Vision Care, and Bernard & Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, Columbia Stem Cell Initiative, Departments of Ophthalmology Pathology & Cell Biology, Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY, USA.,Edward S. Harkness Eye Institute, New York-Presbyterian Hospital, New York, NY, USA
| | - Seba Almedawar
- Center for Molecular and Cellular Bioengineering (CMCB), Center for Regenerative Therapies, Dresden (CRTD), Technische Universität Dresden, Dresden, Germany
| | - Nadine Reichhart
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
| | - Olaf Strauß
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a corporate member of Freie Universität, Humboldt-University, the Berlin Institute of Health, Berlin, Germany
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15
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Ko GYP. Circadian regulation in the retina: From molecules to network. Eur J Neurosci 2020; 51:194-216. [PMID: 30270466 PMCID: PMC6441387 DOI: 10.1111/ejn.14185] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022]
Abstract
The mammalian retina is the most unique tissue among those that display robust circadian/diurnal oscillations. The retina is not only a light sensing tissue that relays light information to the brain, it has its own circadian "system" independent from any influence from other circadian oscillators. While all retinal cells and retinal pigment epithelium (RPE) possess circadian oscillators, these oscillators integrate by means of neural synapses, electrical coupling (gap junctions), and released neurochemicals (such as dopamine, melatonin, adenosine, and ATP), so the whole retina functions as an integrated circadian system. Dysregulation of retinal clocks not only causes retinal or ocular diseases, it also impacts the circadian rhythm of the whole body, as the light information transmitted from the retina entrains the brain clock that governs the body circadian rhythms. In this review, how circadian oscillations in various retinal cells are integrated, and how retinal diseases affect daily rhythms.
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Affiliation(s)
- Gladys Y-P Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
- Texas A&M Institute for Neuroscience, Texas A&M University, College Station, Texas
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16
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Martins JR, Reichhart N, Kociok N, Stindl J, Foeckler R, Lachmann P, Todorov V, Castrop H, Strauß O. Systemic ß adrenergic stimulation/ sympathetic nerve system stimulation influences intraocular RAS through cAMP in the RPE. Exp Eye Res 2019; 189:107828. [PMID: 31589840 DOI: 10.1016/j.exer.2019.107828] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 10/02/2019] [Accepted: 10/03/2019] [Indexed: 10/25/2022]
Abstract
Several lines of evidence support the existence of a renin-angiotensin system (RAS) in the retina that is separated from the blood stream by the retinal pigment epithelium (RPE). Under physiological conditions, increased activity of intraretinal RAS regulates neuronal activity of the retina but patho-physiologically participates in retinal degeneration such as hypertensive or diabetic retinopathy. Interestingly, the RPE appears to be a modulator of intraretinal RAS in response to changes in systemic RAS. As increased systemic RAS activity is associated with increased sympathetic tonus, we investigated whether systemic β-adrenergic stimulation of the RPE also modulates renin expression in the RPE. In vivo, the mouse RPE expresses the β-adrenergic receptor subtypes 1 and 2. Staining of retina sagittal sections showed tyrosine hydroxylase positive nerve endings in the choroid indicating adrenaline/noradrenaline production sites in close proximity to the RPE. Systemic infusion of isoproterenol increased renin expression in the RPE but not in the retina. This increase was sensitive to concomitant systemic application of the angiotensin-2 receptor-type-1 blocker losartan. In vitro analysis of renin gene expression using polarized porcine RPE showed that the activity of the renin promoter can be increased by cAMP stimulation (IBMX/forskolin) but was not influenced by angiotensin-2. Thus, with the identification of the β-adrenergic system we added a new regulator of the retinal RAS with relevance for retinal function and pathology. Furthermore, it appears that the RPE is not only a close interaction partner of the photoreceptors but also a regulator or retinal activity in general.
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Affiliation(s)
- Joana Raquel Martins
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Nadine Reichhart
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany
| | - Nobert Kociok
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany
| | - Julia Stindl
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Renate Foeckler
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Peter Lachmann
- Laboratory for Experimental Nephrology, Dresden University of Technology, Dresden, Germany
| | - Vladimir Todorov
- Laboratory for Experimental Nephrology, Dresden University of Technology, Dresden, Germany
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Olaf Strauß
- Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, a Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany.
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17
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Milićević N, Duursma A, Ten Asbroek ALMA, Felder-Schmittbuhl MP, Bergen AA. Does the circadian clock make RPE-mediated ion transport "tick" via SLC12A2 (NKCC1)? Chronobiol Int 2019; 36:1592-1598. [PMID: 31441327 DOI: 10.1080/07420528.2019.1653317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The presence of a circadian clock in the retinal pigment epithelium (RPE) was discovered recently. However, little is known about mechanisms or processes regulated by the RPE clock. We cultured ARPE-19 monolayers in a transwell culture system, and we found rhythmic mRNA expression of the sodium-potassium-chloride co-transporter SLC12A2. We localized the corresponding protein product, NKCC1, on the apical membrane of ARPE-19 cells. We found that concentrations of sodium, potassium, and chloride oscillated in apical supernatants. The ion concentration gradients between supernatants strongly correlated with SLC12A2 mRNA expression. Our results suggest that the circadian clock regulates ion transport by the RPE via NKCC1 expression.
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Affiliation(s)
- Nemanja Milićević
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives , F-67000 Strasbourg , France.,Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9 , 1105 AZ, Amsterdam , the Netherlands
| | - Angelica Duursma
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9 , 1105 AZ, Amsterdam , the Netherlands
| | - Anneloor L M A Ten Asbroek
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9 , 1105 AZ, Amsterdam , the Netherlands
| | - Marie-Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives , F-67000 Strasbourg , France
| | - Arthur A Bergen
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9 , 1105 AZ, Amsterdam , the Netherlands.,Department of Ophthalmology, Amsterdam UMC, University of Amsterdam, Meibergdreef 9 , 1105 AZ, Amsterdam , the Netherlands.,Department of Retinal Signal Processing, Netherlands Institute for Neuroscience (NIN-KNAW) , 1105 BA, Amsterdam , the Netherlands
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18
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Johansson JK, Karema-Jokinen VI, Hakanen S, Jylhä A, Uusitalo H, Vihinen-Ranta M, Skottman H, Ihalainen TO, Nymark S. Sodium channels enable fast electrical signaling and regulate phagocytosis in the retinal pigment epithelium. BMC Biol 2019; 17:63. [PMID: 31412898 PMCID: PMC6694495 DOI: 10.1186/s12915-019-0681-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 07/11/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Voltage-gated sodium (Nav) channels have traditionally been considered a trademark of excitable cells. However, recent studies have shown the presence of Nav channels in several non-excitable cells, such as astrocytes and macrophages, demonstrating that the roles of these channels are more diverse than was previously thought. Despite the earlier discoveries, the presence of Nav channel-mediated currents in the cells of retinal pigment epithelium (RPE) has been dismissed as a cell culture artifact. We challenge this notion by investigating the presence and possible role of Nav channels in RPE both ex vivo and in vitro. RESULTS Our work demonstrates that several subtypes of Nav channels are found in human embryonic stem cell (hESC)-derived and mouse RPE, most prominently subtypes Nav1.4, Nav1.6, and Nav1.8. Whole cell patch clamp recordings from the hESC-derived RPE monolayers showed that the current was inhibited by TTX and QX-314 and was sensitive to the selective blockers of the main Nav subtypes. Importantly, we show that the Nav channels are involved in photoreceptor outer segment phagocytosis since blocking their activity significantly reduces the efficiency of particle internalization. Consistent with this role, our electron microscopy results and immunocytochemical analysis show that Nav1.4 and Nav1.8 accumulate on phagosomes and that pharmacological inhibition of Nav channels as well as silencing the expression of Nav1.4 with shRNA impairs the phagocytosis process. CONCLUSIONS Taken together, our study shows that Nav channels are present in RPE, giving this tissue the capacity of fast electrical signaling. The channels are critical for the physiology of RPE with an important role in photoreceptor outer segment phagocytosis.
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Affiliation(s)
- Julia K Johansson
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Viivi I Karema-Jokinen
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Satu Hakanen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Antti Jylhä
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Hannu Uusitalo
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Tays Eye Centre, Tampere University Hospital, Tampere, Finland
| | - Maija Vihinen-Ranta
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Heli Skottman
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Teemu O Ihalainen
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Soile Nymark
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
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19
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Milićević N, Mazzaro N, de Bruin I, Wils E, Ten Brink J, Asbroek AT, Mendoza J, Bergen A, Felder-Schmittbuhl MP. Rev-Erbα and Photoreceptor Outer Segments modulate the Circadian Clock in Retinal Pigment Epithelial Cells. Sci Rep 2019; 9:11790. [PMID: 31409842 PMCID: PMC6692399 DOI: 10.1038/s41598-019-48203-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 07/30/2019] [Indexed: 12/24/2022] Open
Abstract
Retinal photoreceptor outer segments (POS) are renewed daily through phagocytosis by the adjacent retinal pigment epithelial (RPE) monolayer. Phagocytosis is mainly driven by the RPE circadian clock but the underlying molecular mechanisms remain elusive. Using ARPE-19 (human RPE cell-line) dispersed and monolayer cell cultures, we investigated the influence of cellular organization on the RPE clock and phagocytosis genes. PCR analysis revealed rhythmic expression of clock and phagocytosis genes in all ARPE-19 cultures. Monolayers had a tendency for higher amplitudes of clock gene oscillations. In all conditions ARNTL, CRY1, PER1-2, REV-ERBα, ITGB5, LAMP1 and PROS1 were rhythmically expressed with REV-ERBα being among the clock genes whose expression showed most robust rhythms in ARPE-19 cells. Using RPE-choroid explant preparations of the mPer2Luc knock-in mice we found that Rev-Erbα deficiency induced significantly longer periods and earlier phases of PER2-bioluminescence oscillations. Furthermore, early phagocytosis factors β5-Integrin and FAK and the lysosomal marker LAMP1 protein levels are rhythmic. Finally, POS incubation affects clock and clock-controlled phagocytosis gene expression in RPE monolayers in a time-dependent manner suggesting that POS can reset the RPE clock. These results shed some light on the complex interplay between POS, the RPE clock and clock-controlled phagocytosis machinery which is modulated by Rev-Erbα.
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Affiliation(s)
- Nemanja Milićević
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), 67000, Strasbourg, France.,Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Nadia Mazzaro
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), 67000, Strasbourg, France
| | - Ivanka de Bruin
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Esmée Wils
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Jacoline Ten Brink
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Anneloor Ten Asbroek
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Jorge Mendoza
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), 67000, Strasbourg, France
| | - Arthur Bergen
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.,Department of Ophthalmology, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.,Netherlands Institute for Neuroscience (NIN-KNAW), Amsterdam, The Netherlands
| | - Marie-Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives (UPR 3212), 67000, Strasbourg, France.
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20
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Liu Y, Liu M, Chen Q, Liu GM, Cao MJ, Sun L, Lu Z, Guo C. Blueberry Polyphenols Ameliorate Visible Light and Lipid-Induced Injury of Retinal Pigment Epithelial Cells. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:12730-12740. [PMID: 30411897 DOI: 10.1021/acs.jafc.8b05272] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Although dietary polyphenols are known to be beneficial to vision, the protective distinctions among different types of polyphenols are unclear. In this work, the visual benefits of various blueberry polyphenols were evaluated using an in vitro model of visible light-lipid-induced injury of retinal pigment epithelial cells. Results showed that, at 10.0 μg/mL, the phenolic acid-rich fraction was superior in inhibiting cell death (93.6% ± 2.8% of cell viability). Anthocyanin- and flavonoid-rich fractions shared similar advantages in preventing the expression of senescence-associated β-galactosidase (34.8% ± 11.1% and 32.2% ± 9.7% of aged cells, respectively) and overexpression of vascular endothelial growth factor (51.8 ± 3.5 and 54.1 ± 6.5 pg/mL, respectively). The flavonoid-rich fraction also showed high activity in ameliorating phagocytosis (70.3% ± 12.6%) and cellular oxidative stress. These results were further confirmed by using the corresponding polyphenol standards. Improved inhibitory effects of polyphenol mixture on cell death and senescence-associated β-galactosidase expression were also observed. Therefore, various polyphenols play diverse roles and exert synergistic effects in nourishing the retina.
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Affiliation(s)
- Yixiang Liu
- College of Food and Biological Engineering , Jimei University , Xiamen 361021 , Fujian People's Republic of China
- Xiamen Key Laboratory of Marine Functional Food , Jimei University , Xiamen 361021 , Fujian People's Republic of China
- Fujian Provincial Engineering Technology Research Center of Marine Functional Food , Jimei University , Xiamen 361021 , Fujian People's Republic of China
| | - Ming Liu
- Academy of State Administration of Grain , Beijing 100037 , People's Republic of China
| | - Qingchou Chen
- College of Food and Biological Engineering , Jimei University , Xiamen 361021 , Fujian People's Republic of China
| | - Guang-Ming Liu
- College of Food and Biological Engineering , Jimei University , Xiamen 361021 , Fujian People's Republic of China
- Xiamen Key Laboratory of Marine Functional Food , Jimei University , Xiamen 361021 , Fujian People's Republic of China
- Fujian Provincial Engineering Technology Research Center of Marine Functional Food , Jimei University , Xiamen 361021 , Fujian People's Republic of China
| | - Min-Jie Cao
- College of Food and Biological Engineering , Jimei University , Xiamen 361021 , Fujian People's Republic of China
- Xiamen Key Laboratory of Marine Functional Food , Jimei University , Xiamen 361021 , Fujian People's Republic of China
- Fujian Provincial Engineering Technology Research Center of Marine Functional Food , Jimei University , Xiamen 361021 , Fujian People's Republic of China
| | - Lechang Sun
- College of Food and Biological Engineering , Jimei University , Xiamen 361021 , Fujian People's Republic of China
- Xiamen Key Laboratory of Marine Functional Food , Jimei University , Xiamen 361021 , Fujian People's Republic of China
- Fujian Provincial Engineering Technology Research Center of Marine Functional Food , Jimei University , Xiamen 361021 , Fujian People's Republic of China
| | - Zhenhua Lu
- College of Food and Biological Engineering , Jimei University , Xiamen 361021 , Fujian People's Republic of China
| | - Caihua Guo
- College of Food and Biological Engineering , Jimei University , Xiamen 361021 , Fujian People's Republic of China
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21
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Korkka I, Viheriälä T, Juuti-Uusitalo K, Uusitalo-Järvinen H, Skottman H, Hyttinen J, Nymark S. Functional Voltage-Gated Calcium Channels Are Present in Human Embryonic Stem Cell-Derived Retinal Pigment Epithelium. Stem Cells Transl Med 2018; 8:179-193. [PMID: 30394009 PMCID: PMC6344904 DOI: 10.1002/sctm.18-0026] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 08/24/2018] [Accepted: 09/07/2018] [Indexed: 11/25/2022] Open
Abstract
Retinal pigment epithelium (RPE) performs important functions for the maintenance of photoreceptors and vision. Malfunctions within the RPE are implicated in several retinal diseases for which transplantations of stem cell‐derived RPE are promising treatment options. Their success, however, is largely dependent on the functionality of the transplanted cells. This requires correct cellular physiology, which is highly influenced by the various ion channels of RPE, including voltage‐gated Ca2+ (CaV) channels. This study investigated the localization and functionality of CaV channels in human embryonic stem cell (hESC)‐derived RPE. Whole‐cell patch‐clamp recordings from these cells revealed slowly inactivating L‐type currents comparable to freshly isolated mouse RPE. Some hESC‐RPE cells also carried fast transient T‐type resembling currents. These findings were confirmed by immunostainings from both hESC‐ and mouse RPE that showed the presence of the L‐type Ca2+ channels CaV1.2 and CaV1.3 as well as the T‐type Ca2+ channels CaV3.1 and CaV3.2. The localization of the major subtype, CaV1.3, changed during hESC‐RPE maturation co‐localizing with pericentrin to the base of the primary cilium before reaching more homogeneous membrane localization comparable to mouse RPE. Based on functional assessment, the L‐type Ca2+ channels participated in the regulation of vascular endothelial growth factor secretion as well as in the phagocytosis of photoreceptor outer segments in hESC‐RPE. Overall, this study demonstrates that a functional machinery of voltage‐gated Ca2+ channels is present in mature hESC‐RPE, which is promising for the success of transplantation therapies. stem cells translational medicine2019;8:179&15
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Affiliation(s)
- Iina Korkka
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
| | - Taina Viheriälä
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland.,Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Kati Juuti-Uusitalo
- Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Hannele Uusitalo-Järvinen
- Eye Centre, Tampere University Hospital, Tampere, Finland.,Faculty of Medicine and Life Sciences, Department of Ophthalmology, University of Tampere, Tampere, Finland
| | - Heli Skottman
- Faculty of Medicine and Life Sciences, BioMediTech, University of Tampere, Tampere, Finland
| | - Jari Hyttinen
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
| | - Soile Nymark
- Faculty of Biomedical Sciences and Engineering, BioMediTech, Tampere University of Technology, Tampere, Finland
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22
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Kim SH, Park YR, Lee B, Choi B, Kim H, Kim CH. Reduction of Cav1.3 channels in dorsal hippocampus impairs the development of dentate gyrus newborn neurons and hippocampal-dependent memory tasks. PLoS One 2017; 12:e0181138. [PMID: 28715454 PMCID: PMC5513490 DOI: 10.1371/journal.pone.0181138] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 06/27/2017] [Indexed: 12/12/2022] Open
Abstract
Cav1.3 has been suggested to mediate hippocampal neurogenesis of adult mice and contribute to hippocampal-dependent learning and memory processes. However, the mechanism of Cav1.3 contribution in these processes is unclear. Here, roles of Cav1.3 of mouse dorsal hippocampus during newborn cell development were examined. We find that knock-out (KO) of Cav1.3 resulted in the reduction of survival of newborn neurons at 28 days old after mitosis. The retroviral eGFP expression showed that both dendritic complexity and the number and length of mossy fiber bouton (MFB) filopodia of newborn neurons at ≥ 14 days old were significantly reduced in KO mice. Both contextual fear conditioning (CFC) and object-location recognition tasks were impaired in recent (1 day) memory test while passive avoidance task was impaired only in remote (≥ 20 days) memory in KO mice. Results using adeno-associated virus (AAV)-mediated Cav1.3 knock-down (KD) or retrovirus-mediated KD in dorsal hippocampal DG area showed that the recent memory of CFC was impaired in both KD mice but the remote memory was impaired only in AAV KD mice, suggesting that Cav1.3 of mature neurons play important roles in both recent and remote CFC memory while Cav1.3 in newborn neurons is selectively involved in the recent CFC memory process. Meanwhile, AAV KD of Cav1.3 in ventral hippocampal area has no effect on the recent CFC memory. In conclusion, the results suggest that Cav1.3 in newborn neurons of dorsal hippocampus is involved in the survival of newborn neurons while mediating developments of dendritic and axonal processes of newborn cells and plays a role in the memory process differentially depending on the stage of maturation and the type of learning task.
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Affiliation(s)
- Su-Hyun Kim
- Center for Neuroscience, Korea Institute of Science and Technology, Seoul, Korea
- Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology, Seoul, Korea
| | - Ye-Ryoung Park
- Center for Neuroscience, Korea Institute of Science and Technology, Seoul, Korea
- Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology, Seoul, Korea
| | - Boyoung Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, Korea
| | - Byungil Choi
- Department of Anatomy and Division of Brain Korea 21 Biomedical Science, College of Medicine, Korea University, Seoul, Korea
| | - Hyun Kim
- Department of Anatomy and Division of Brain Korea 21 Biomedical Science, College of Medicine, Korea University, Seoul, Korea
| | - Chong-Hyun Kim
- Center for Neuroscience, Korea Institute of Science and Technology, Seoul, Korea
- Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology, Seoul, Korea
- * E-mail:
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23
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Klingeborn M, Dismuke WM, Skiba NP, Kelly U, Stamer WD, Bowes Rickman C. Directional Exosome Proteomes Reflect Polarity-Specific Functions in Retinal Pigmented Epithelium Monolayers. Sci Rep 2017; 7:4901. [PMID: 28687758 PMCID: PMC5501811 DOI: 10.1038/s41598-017-05102-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 05/30/2017] [Indexed: 01/09/2023] Open
Abstract
The retinal pigmented epithelium (RPE) forms the outer blood-retinal barrier in the eye and its polarity is responsible for directional secretion and uptake of proteins, lipoprotein particles and extracellular vesicles (EVs). Such a secretional division dictates directed interactions between the systemic circulation (basolateral) and the retina (apical). Our goal is to define the polarized proteomes and physical characteristics of EVs released from the RPE. Primary cultures of porcine RPE cells were differentiated into polarized RPE monolayers on permeable supports. EVs were isolated from media bathing either apical or basolateral RPE surfaces, and two subpopulations of small EVs including exosomes, and dense EVs, were purified and processed for proteomic profiling. In parallel, EV size distribution and concentration were determined. Using protein correlation profiling mass spectrometry, a total of 631 proteins were identified in exosome preparations, 299 of which were uniquely released apically, and 94 uniquely released basolaterally. Selected proteins were validated by Western blot. The proteomes of these exosome and dense EVs preparations suggest that epithelial polarity impacts directional release. These data serve as a foundation for comparative studies aimed at elucidating the role of exosomes in the molecular pathophysiology of retinal diseases and help identify potential therapeutic targets and biomarkers.
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Affiliation(s)
- Mikael Klingeborn
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA.
| | - W Michael Dismuke
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA
| | - Nikolai P Skiba
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA
| | - Una Kelly
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA.,Department of Biomedical Engineering, Duke University, Durham, NC, 27710, USA
| | - Catherine Bowes Rickman
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, 27710, USA. .,Department of Cell Biology, Duke University, Durham, NC, 27710, USA.
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24
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Seitter H, Koschak A. Relevance of tissue specific subunit expression in channelopathies. Neuropharmacology 2017; 132:58-70. [PMID: 28669898 DOI: 10.1016/j.neuropharm.2017.06.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/22/2017] [Accepted: 06/28/2017] [Indexed: 12/27/2022]
Abstract
Channelopathies are a diverse group of human disorders that are caused by mutations in genes coding for ion channels or channel-regulating proteins. Several dozen channelopathies have been identified that involve both non-excitable cells as well as electrically active tissues like brain, skeletal and smooth muscle or the heart. In this review, we start out from the general question which ion channel genes are expressed tissue-selectively. We mined the human gene expression database Human Protein Atlas (HPA) for tissue-enriched ion channel genes and found 85 genes belonging to the ion channel families. Most of these genes were enriched in brain, testis and muscle and a complete list of the enriched ion channel genes is provided. We further focused on the tissue distribution of voltage-gated calcium channel (VGCC) genes including different brain areas and the retina based on the human gene expression from the FANTOM5 dataset. The expression data is complemented by an overview of the tissue-dependent aspects of L-type calcium channel (LTCC) function, dysfunction and pharmacology, as well as of their splice variants. Finally, we focus on the pathology of tissue-restricted LTCC channelopathies and their treatment options. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Hartwig Seitter
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, Innrain 80-82/III, 6020 Innsbruck, Austria
| | - Alexandra Koschak
- University of Innsbruck, Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, Innrain 80-82/III, 6020 Innsbruck, Austria.
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25
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Ikarashi R, Akechi H, Kanda Y, Ahmad A, Takeuchi K, Morioka E, Sugiyama T, Ebisawa T, Ikeda M, Ikeda M. Regulation of molecular clock oscillations and phagocytic activity via muscarinic Ca 2+ signaling in human retinal pigment epithelial cells. Sci Rep 2017; 7:44175. [PMID: 28276525 PMCID: PMC5343479 DOI: 10.1038/srep44175] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 02/06/2017] [Indexed: 12/12/2022] Open
Abstract
Vertebrate eyes are known to contain circadian clocks, however, the intracellular mechanisms regulating the retinal clockwork remain largely unknown. To address this, we generated a cell line (hRPE-YC) from human retinal pigmental epithelium, which stably co-expressed reporters for molecular clock oscillations (Bmal1-luciferase) and intracellular Ca2+ concentrations (YC3.6). The hRPE-YC cells demonstrated circadian rhythms in Bmal1 transcription. Also, these cells represented circadian rhythms in Ca2+-spiking frequencies, which were canceled by dominant-negative Bmal1 transfections. The muscarinic agonist carbachol, but not photic stimulation, phase-shifted Bmal1 transcriptional rhythms with a type-1 phase response curve. This is consistent with significant M3 muscarinic receptor expression and little photo-sensor (Cry2 and Opn4) expression in these cells. Moreover, forskolin phase-shifted Bmal1 transcriptional rhythm with a type-0 phase response curve, in accordance with long-lasting CREB phosphorylation levels after forskolin exposure. Interestingly, the hRPE-YC cells demonstrated apparent circadian rhythms in phagocytic activities, which were abolished by carbachol or dominant-negative Bmal1 transfection. Because phagocytosis in RPE cells determines photoreceptor disc shedding, molecular clock oscillations and cytosolic Ca2+ signaling may be the driving forces for disc-shedding rhythms known in various vertebrates. In conclusion, the present study provides a cellular model to understand molecular and intracellular signaling mechanisms underlying human retinal circadian clocks.
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Affiliation(s)
- Rina Ikarashi
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama city, Toyama 930-8555, Japan
| | - Honami Akechi
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama city, Toyama 930-8555, Japan
| | - Yuzuki Kanda
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama city, Toyama 930-8555, Japan
| | - Alsawaf Ahmad
- Graduate School of Innovative Life Science, University of Toyama, 3190 Gofuku, Toyama city, Toyama 930-8555, Japan
| | - Kouhei Takeuchi
- Graduate School of Innovative Life Science, University of Toyama, 3190 Gofuku, Toyama city, Toyama 930-8555, Japan
| | - Eri Morioka
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama city, Toyama 930-8555, Japan
| | - Takashi Sugiyama
- Advanced Core Technology Department, Research and Development Division, Olympus Co. Ltd., 2-3 Kuboyama, Hachioji, Tokyo 192-8512, Japan
| | - Takashi Ebisawa
- Department of Psychiatry, Tokyo Metropolitan Police Hospital, 4-22-1 Nakano, Nakano-ku, Tokyo 164-8541, Japan
| | - Masaaki Ikeda
- Department of Physiology, Saitama Medical University, 38 Morohongo, Moroyama, Iruma-gun, Saitama 350-0495, Japan.,Molecular Clock Project, Project Research Division, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka city, Saitama, 350-1241, Japan
| | - Masayuki Ikeda
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama city, Toyama 930-8555, Japan.,Graduate School of Innovative Life Science, University of Toyama, 3190 Gofuku, Toyama city, Toyama 930-8555, Japan
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26
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Abstract
Large conductance Ca(2+)- and voltage-activated K(+) (BK) channels are widely distributed in the postnatal central nervous system (CNS). BK channels play a pleiotropic role in regulating the activity of brain and spinal cord neural circuits by providing a negative feedback mechanism for local increases in intracellular Ca(2+) concentrations. In neurons, they regulate the timing and duration of K(+) influx such that they can either increase or decrease firing depending on the cellular context, and they can suppress neurotransmitter release from presynaptic terminals. In addition, BK channels located in astrocytes and arterial myocytes modulate cerebral blood flow. Not surprisingly, both loss and gain of BK channel function have been associated with CNS disorders such as epilepsy, ataxia, mental retardation, and chronic pain. On the other hand, the neuroprotective role played by BK channels in a number of pathological situations could potentially be leveraged to correct neurological dysfunction.
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27
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Strauß O, Reichhart N, Gomez NM, Müller C. Contribution of Ion Channels in Calcium Signaling Regulating Phagocytosis: MaxiK, Cav1.3 and Bestrophin-1. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:739-44. [PMID: 26427483 DOI: 10.1007/978-3-319-17121-0_98] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mutations in the BEST1 gene lead to a variety of retinal degenerations including Best's vitelliforme macular degeneration. The BEST1 gene product, bestrophin-1, is expressed in the retinal pigment epithelium (RPE). It is likely that mutant bestrophin-1 impairs functions of the RPE which support photoreceptor function and will thus lead to retinal degeneration. However, the RPE function which is influenced by bestrophin-1 is so far not identified. Previously we showed that bestrophin-1 interacts with L-type Ca²⁺ channels of the CaV1.3 subtype and that the endogenously expressed bestrophin-1 is required for intracellular Ca²⁺ regulation. A hallmark of Best's disease is the fast lipofuscin accumulation occurring already at young ages. Therefore, we addressed the hypothesis that bestrophin-1 might influence phagocytosis of photoreceptor outer segments (POS) by the RPE. Here, siRNA knock-down of bestrophin-1 expression as well as inhibition of L-type Ca²⁺ channel activity modulated the POS phagocytosis in vitro. In vivo CaV1.3 expression appeared to be diurnal regulated with a higher expression rate in the afternoon. Compared to wild-type littermates, Ca V 1.3 (-/-) mice showed a shift in the circadian POS phagocytosis with an increased activity in the afternoon. Thus we suggest that mutant bestrophin-1 leads to an impaired regulation of the POS phagocytosis by the RPE which would explain the fast lipofuscin accumulation in Best patients.
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Affiliation(s)
- Olaf Strauß
- Experimental Ophthalmology, Department of Ophthalmology, Charite University Medicine Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
| | - Nadine Reichhart
- Experimental Ophthalmology, Department of Ophthalmology, Charite University Medicine Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
| | - Nestor Mas Gomez
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania, Augustenburger Platz 1, 240 South 40th Street, 19104-6030, Philadelphia, PA, USA.
| | - Claudia Müller
- Department of Biological Sciences, Center for Cancer, Genetic Diseases and Gene Regulation, Fordham University Bronx, 10458, Bronx, NY, USA.
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28
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Giblin JP, Comes N, Strauss O, Gasull X. Ion Channels in the Eye: Involvement in Ocular Pathologies. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:157-231. [PMID: 27038375 DOI: 10.1016/bs.apcsb.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The eye is the sensory organ of vision. There, the retina transforms photons into electrical signals that are sent to higher brain areas to produce visual sensations. In the light path to the retina, different types of cells and tissues are involved in maintaining the transparency of avascular structures like the cornea or lens, while others, like the retinal pigment epithelium, have a critical role in the maintenance of photoreceptor function by regenerating the visual pigment. Here, we have reviewed the roles of different ion channels expressed in ocular tissues (cornea, conjunctiva and neurons innervating the ocular surface, lens, retina, retinal pigment epithelium, and the inflow and outflow systems of the aqueous humor) that are involved in ocular disease pathophysiologies and those whose deletion or pharmacological modulation leads to specific diseases of the eye. These include pathologies such as retinitis pigmentosa, macular degeneration, achromatopsia, glaucoma, cataracts, dry eye, or keratoconjunctivitis among others. Several disease-associated ion channels are potential targets for pharmacological intervention or other therapeutic approaches, thus highlighting the importance of these channels in ocular physiology and pathophysiology.
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Affiliation(s)
- Jonathan P Giblin
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Comes
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Xavier Gasull
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
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29
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Singh R, Kuai D, Guziewicz KE, Meyer J, Wilson M, Lu J, Smith M, Clark E, Verhoeven A, Aguirre GD, Gamm DM. Pharmacological Modulation of Photoreceptor Outer Segment Degradation in a Human iPS Cell Model of Inherited Macular Degeneration. Mol Ther 2015; 23:1700-1711. [PMID: 26300224 DOI: 10.1038/mt.2015.141] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/23/2015] [Indexed: 12/16/2022] Open
Abstract
Degradation of photoreceptor outer segments (POS) by retinal pigment epithelium (RPE) is essential for vision, and studies have implicated altered POS processing in the pathogenesis of some retinal degenerative diseases. Consistent with this concept, a recently established hiPSC-RPE model of inherited macular degeneration, Best disease (BD), displayed reduced rates of POS breakdown. Herein we utilized this model to determine (i) if disturbances in protein degradation pathways are associated with delayed POS digestion and (ii) whether such defect(s) can be pharmacologically targeted. We found that BD hiPSC-RPE cultures possessed increased protein oxidation, decreased free-ubiquitin levels, and altered rates of exosome secretion, consistent with altered POS processing. Application of valproic acid (VPA) with or without rapamycin increased rates of POS degradation in our model, whereas application of bafilomycin-A1 decreased such rates. Importantly, the negative effect of bafilomycin-A1 could be fully reversed by VPA. The utility of hiPSC-RPE for VPA testing was further evident following examination of its efficacy and metabolism in a complementary canine disease model. Our findings suggest that disturbances in protein degradation pathways contribute to the POS processing defect observed in BD hiPSC-RPE, which can be manipulated pharmacologically. These results have therapeutic implications for BD and perhaps other maculopathies.
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Affiliation(s)
- Ruchira Singh
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin, USA
| | - David Kuai
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Karina E Guziewicz
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jackelyn Meyer
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Molly Wilson
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jianfeng Lu
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Molly Smith
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Eric Clark
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Amelia Verhoeven
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Gustavo D Aguirre
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - David M Gamm
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA; McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin, USA; Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, USA.
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30
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Zhao PY, Gan G, Peng S, Wang SB, Chen B, Adelman RA, Rizzolo LJ. TRP Channels Localize to Subdomains of the Apical Plasma Membrane in Human Fetal Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2015; 56:1916-23. [PMID: 25736794 DOI: 10.1167/iovs.14-15738] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Calcium regulates many functions of the RPE. Its concentration in the subretinal space and RPE cytoplasm is closely regulated. Transient receptor potential (TRP) channels are a superfamily of ion channels that are moderately calcium-selective. This study investigates the subcellular localization and potential functions of TRP channels in a first-passage culture model of human fetal RPE (hfRPE). METHODS The RPE isolated from 15- to 16-week gestation fetuses were maintained in serum-free media. Cultures were treated with barium chloride (BaCl2) in the absence and presence of TRP channel inhibitors and monitored by the transepithelial electrical resistance (TER). The expression of TRP channels was determined using quantitative RT-PCR, immunoblotting, and immunofluorescence confocal microscopy. RESULTS Barium chloride substantially decreased TER and disrupted cell-cell contacts when added to the apical surface of RPE, but not when added to the basolateral surface. The effect could be partially blocked by the general TRP inhibitor, lanthanum chloride (LaCl3, ~75%), or an inhibitor of calpain (~25%). Family member-specific inhibitors, ML204 (TRPC4) and HC-067047 (TRPV4), had no effect on basal channel activity. Expression of TRPC4, TRPM1, TRPM3, TRPM7, and TRPV4 was detected by RT-PCR and immunoblotting. The TRPM3 localized to the base of the primary cilium, and TRPC4 and TRPM3 localized to apical tight junctions. The TRPV4 localized to apical microvilli in a small subset of cells. CONCLUSIONS The TRP channels localized to subdomains of the apical membrane, and BaCl2 was only able to dissociate tight junctions when presented to the apical membrane. The data suggest a potential role for TRP channels as sensors of [Ca(2+)] in the subretinal space.
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Affiliation(s)
- Peter Y Zhao
- Department of Surgery, Yale University, New Haven, Connecticut, United States
| | - Geliang Gan
- Department of Surgery, Yale University, New Haven, Connecticut, United States
| | - Shaomin Peng
- Department of Surgery, Yale University, New Haven, Connecticut, United States
| | - Shao-Bin Wang
- Department of Surgery, Yale University, New Haven, Connecticut, United States Department of Ophthalmology & Visual Science, Yale University, New Haven, Connecticut, United States
| | - Bo Chen
- Department of Ophthalmology & Visual Science, Yale University, New Haven, Connecticut, United States
| | - Ron A Adelman
- Department of Ophthalmology & Visual Science, Yale University, New Haven, Connecticut, United States
| | - Lawrence J Rizzolo
- Department of Surgery, Yale University, New Haven, Connecticut, United States Department of Ophthalmology & Visual Science, Yale University, New Haven, Connecticut, United States
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31
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Ion channels and transporters of the retinal pigment epithelium. Exp Eye Res 2014; 126:27-37. [DOI: 10.1016/j.exer.2014.05.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 05/02/2014] [Accepted: 05/12/2014] [Indexed: 12/19/2022]
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32
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Toops KA, Tan LX, Lakkaraju A. A detailed three-step protocol for live imaging of intracellular traffic in polarized primary porcine RPE monolayers. Exp Eye Res 2014; 124:74-85. [PMID: 24861273 DOI: 10.1016/j.exer.2014.05.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 04/23/2014] [Accepted: 05/02/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Kimberly A Toops
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA
| | - Li Xuan Tan
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA; Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA
| | - Aparna Lakkaraju
- Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA; Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA.
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