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Leal AF, Inci OK, Seyrantepe V, Rintz E, Celik B, Ago Y, León D, Suarez DA, Alméciga-Díaz CJ, Tomatsu S. Molecular Trojan Horses for treating lysosomal storage diseases. Mol Genet Metab 2023; 140:107648. [PMID: 37598508 DOI: 10.1016/j.ymgme.2023.107648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 08/22/2023]
Abstract
Lysosomal storage diseases (LSDs) are caused by monogenic mutations in genes encoding for proteins related to the lysosomal function. Lysosome plays critical roles in molecule degradation and cell signaling through interplay with many other cell organelles, such as mitochondria, endoplasmic reticulum, and peroxisomes. Even though several strategies (i.e., protein replacement and gene therapy) have been attempted for LSDs with promising results, there are still some challenges when hard-to-treat tissues such as bone (i.e., cartilages, ligaments, meniscus, etc.), the central nervous system (mostly neurons), and the eye (i.e., cornea, retina) are affected. Consistently, searching for novel strategies to reach those tissues remains a priority. Molecular Trojan Horses have been well-recognized as a potential alternative in several pathological scenarios for drug delivery, including LSDs. Even though molecular Trojan Horses refer to genetically engineered proteins to overcome the blood-brain barrier, such strategy can be extended to strategies able to transport and deliver drugs to specific tissues or cells using cell-penetrating peptides, monoclonal antibodies, vesicles, extracellular vesicles, and patient-derived cells. Only some of those platforms have been attempted in LSDs. In this paper, we review the most recent efforts to develop molecular Trojan Horses and discuss how this strategy could be implemented to enhance the current efficacy of strategies such as protein replacement and gene therapy in the context of LSDs.
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Affiliation(s)
- Andrés Felipe Leal
- Institute for the Study of Inborn Errors of Metabolism, Faculty of Science, Pontificia Universidad Javeriana, Bogotá, Colombia; Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Orhan Kerim Inci
- Department of Molecular Biology and Genetics, Izmir Institute of Technology, 35430 Izmir, Turkey
| | - Volkan Seyrantepe
- Department of Molecular Biology and Genetics, Izmir Institute of Technology, 35430 Izmir, Turkey
| | - Estera Rintz
- Department of Molecular Biology, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Betul Celik
- Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA; Department of Molecular Biology, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | - Yasuhiko Ago
- Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Daniel León
- Institute for the Study of Inborn Errors of Metabolism, Faculty of Science, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Diego A Suarez
- Institute for the Study of Inborn Errors of Metabolism, Faculty of Science, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Carlos Javier Alméciga-Díaz
- Institute for the Study of Inborn Errors of Metabolism, Faculty of Science, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Shunji Tomatsu
- Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA; Department of Molecular Biology, Faculty of Biology, University of Gdansk, Gdansk, Poland; Faculty of Arts and Sciences, University of Delaware, Newark, DE, USA; Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan; Department of Pediatrics, Thomas Jefferson University, Philadelphia, PA, USA.
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2
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Gurler G, Belder N, Beker MC, Sever-Bahcekapili M, Uruk G, Kilic E, Yemisci M. Reduced folate carrier 1 is present in retinal microvessels and crucial for the inner blood retinal barrier integrity. Fluids Barriers CNS 2023; 20:47. [PMID: 37328777 DOI: 10.1186/s12987-023-00442-3] [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: 12/24/2022] [Accepted: 05/18/2023] [Indexed: 06/18/2023] Open
Abstract
BACKGROUND Reduced folate carrier 1 (RFC1; SLC19a1) is the main responsible transporter for the B9 family of vitamins named folates, which are essential for normal tissue growth and development. While folate deficiency resulted in retinal vasculopathy, the expression and the role of RFC1 in blood-retinal barrier (BRB) are not well known. METHODS We used whole mount retinas and trypsin digested microvessel samples of adult mice. To knockdown RFC1, we delivered RFC1-targeted short interfering RNA (RFC1-siRNA) intravitreally; while, to upregulate RFC1 we delivered lentiviral vector overexpressing RFC1. Retinal ischemia was induced 1-h by applying FeCl3 to central retinal artery. We used RT-qPCR and Western blotting to determine RFC1. Endothelium (CD31), pericytes (PDGFR-beta, CD13, NG2), tight-junctions (Occludin, Claudin-5 and ZO-1), main basal membrane protein (Collagen-4), endogenous IgG and RFC1 were determined immunohistochemically. RESULTS Our analyses on whole mount retinas and trypsin digested microvessel samples of adult mice revealed the presence of RFC1 in the inner BRB and colocalization with endothelial cells and pericytes. Knocking down RFC1 expression via siRNA delivery resulted in the disintegration of tight junction proteins and collagen-4 in twenty-four hours, which was accompanied by significant endogenous IgG extravasation. This indicated the impairment of BRB integrity after an abrupt RFC1 decrease. Furthermore, lentiviral vector-mediated RFC1 overexpression resulted in increased tight junction proteins and collagen-4, confirming the structural role of RFC1 in the inner BRB. Acute retinal ischemia decreased collagen-4 and occludin levels and led to an increase in RFC1. Besides, the pre-ischemic overexpression of RFC1 partially rescued collagen-4 and occludin levels which would be decreased after ischemia. CONCLUSION In conclusion, our study clarifies the presence of RFC1 protein in the inner BRB, which has recently been defined as hypoxia-immune-related gene in other tissues and offers a novel perspective of retinal RFC1. Hence, other than being a folate carrier, RFC1 is an acute regulator of the inner BRB in healthy and ischemic retinas.
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Affiliation(s)
- Gokce Gurler
- The Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Nevin Belder
- Biotechnology Institute, Ankara University, Ankara, Turkey
| | | | | | - Gokhan Uruk
- The Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey
| | - Ertugrul Kilic
- Neuroscience and Neurotechnology Center of Excellence (NÖROM), Ankara, Turkey
- Physiology, Istanbul Medeniyet University, Istanbul, Turkey
| | - Muge Yemisci
- The Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara, Turkey.
- Faculty of Medicine, Department of Neurology, Hacettepe University, Ankara, Turkey.
- Neuroscience and Neurotechnology Center of Excellence (NÖROM), Ankara, Turkey.
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Müller GA, Müller TD. (Patho)Physiology of Glycosylphosphatidylinositol-Anchored Proteins I: Localization at Plasma Membranes and Extracellular Compartments. Biomolecules 2023; 13:biom13050855. [PMID: 37238725 DOI: 10.3390/biom13050855] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/11/2023] [Accepted: 05/13/2023] [Indexed: 05/28/2023] Open
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins (APs) are anchored at the outer leaflet of plasma membranes (PMs) of all eukaryotic organisms studied so far by covalent linkage to a highly conserved glycolipid rather than a transmembrane domain. Since their first description, experimental data have been accumulating for the capability of GPI-APs to be released from PMs into the surrounding milieu. It became evident that this release results in distinct arrangements of GPI-APs which are compatible with the aqueous milieu upon loss of their GPI anchor by (proteolytic or lipolytic) cleavage or in the course of shielding of the full-length GPI anchor by incorporation into extracellular vesicles, lipoprotein-like particles and (lyso)phospholipid- and cholesterol-harboring micelle-like complexes or by association with GPI-binding proteins or/and other full-length GPI-APs. In mammalian organisms, the (patho)physiological roles of the released GPI-APs in the extracellular environment, such as blood and tissue cells, depend on the molecular mechanisms of their release as well as the cell types and tissues involved, and are controlled by their removal from circulation. This is accomplished by endocytic uptake by liver cells and/or degradation by GPI-specific phospholipase D in order to bypass potential unwanted effects of the released GPI-APs or their transfer from the releasing donor to acceptor cells (which will be reviewed in a forthcoming manuscript).
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Affiliation(s)
- Günter A Müller
- Institute for Diabetes and Obesity (IDO), Helmholtz Diabetes Center (HDC) at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Oberschleissheim, Germany
- German Center for Diabetes Research (DZD), 85764 Oberschleissheim, Germany
| | - Timo D Müller
- Institute for Diabetes and Obesity (IDO), Helmholtz Diabetes Center (HDC) at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Oberschleissheim, Germany
- German Center for Diabetes Research (DZD), 85764 Oberschleissheim, Germany
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Cambieri C, Marenco M, Colasanti T, Mancone C, Corsi A, Riminucci M, Libonati L, Moret F, Chimenti C, Lambiase A, Conti F, Garibaldi M, Inghilleri M, Ceccanti M. Does Patisiran Reduce Ocular Transthyretin Synthesis? A Pilot Study of Two Cases. Curr Neuropharmacol 2023; 21:2543-2549. [PMID: 37357518 PMCID: PMC10616919 DOI: 10.2174/1570159x21666230623094710] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 01/21/2023] [Accepted: 01/23/2023] [Indexed: 06/27/2023] Open
Abstract
BACKGROUND Variant transthyretin-mediated amyloidosis (ATTR-v) is a well-characterized disease affecting the neurologic and cardiovascular systems. Patisiran has been approved for neurologic involvement as it reduces hepatic synthesis of transthyretin (TTR). Eye involvement is a lateonset feature increasing the risk of glaucoma and cataracts in patients. AIMS The aim of this case series was to assess whether patisiran can effectively reduce TTR synthesis in such a barrier-protected organ as the eye. METHODS Two patisiran-treated ATTR-v patients underwent serum and aqueous humor sampling to measure TTR levels detected by SDS-PAGE and immunoblotting. Serum samples were compared to healthy control (HC), whereas aqueous humor samples were compared to non-amyloidotic subjects affected by cataracts and glaucoma. RESULTS Serum TTR levels representative of hepatic synthesis were sharply lower in treated patients if compared to the HC (-87.5% and -93.75%, respectively). Aqueous humor TTR levels showed mild-tono reduction in treated patients compared to non-amyloidotic subjects with cataracts (-34.9% and +8.1%, respectively) and glaucoma (-41.1% and -2.1%). CONCLUSION Patisiran does not seem to be as effective in inhibiting ocular TTR synthesis as it is in inhibiting hepatic synthesis. Re-engineering the envelope could allow the drug to target RPE cells thus avoiding any ocular involvement.
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Affiliation(s)
- Chiara Cambieri
- Department of Human Neuroscience, Centre for Rare Neuromuscular Disease, Sapienza University of Rome, Rome, Italy
| | - Marco Marenco
- Department of Sense Organs, Sapienza University of Rome, Rome, Italy
| | - Tania Colasanti
- Department of Clinical Internal, Rheumatology Unit, Anesthetic and Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy
| | - Carmine Mancone
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Alessandro Corsi
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Mara Riminucci
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Laura Libonati
- Department of Human Neuroscience, Centre for Rare Neuromuscular Disease, Sapienza University of Rome, Rome, Italy
| | - Federica Moret
- Department of Human Neuroscience, Centre for Rare Neuromuscular Disease, Sapienza University of Rome, Rome, Italy
| | - Cristina Chimenti
- Department of Clinical, Internal, Anesthesiologist and Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy
- Cellular and Molecular Cardiology Lab, IRCCS L. Spallanzani, Rome, Italy
| | | | - Fabrizio Conti
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Matteo Garibaldi
- Department of Neuroscience, Mental Health, and Sensory Organs (NESMOS), Sant’Andrea Hospital, Sapienza University, Rome, Italy
| | - Maurizio Inghilleri
- Department of Human Neuroscience, Centre for Rare Neuromuscular Disease, Sapienza University of Rome, Rome, Italy
| | - Marco Ceccanti
- Department of Human Neuroscience, Centre for Rare Neuromuscular Disease, Sapienza University of Rome, Rome, Italy
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Inoue M, Muta K, Mohammed AFA, Onodera R, Higashi T, Ouchi K, Ueda M, Ando Y, Arima H, Jono H, Motoyama K. Feasibility Study of Dendrimer-Based TTR-CRISPR pDNA Polyplex for Ocular Amyloidosis <i>in Vitro</i>. Biol Pharm Bull 2022; 45:1660-1668. [DOI: 10.1248/bpb.b22-00452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Masamichi Inoue
- Department of Physical Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Kyosuke Muta
- Department of Physical Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kumamoto University
| | | | - Risako Onodera
- Department of Physical Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Taishi Higashi
- Priority Organization for Innovation and Excellence, Kumamoto University
| | - Kenta Ouchi
- Department of Clinical Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Mitsuharu Ueda
- Department of Neurology, Graduate School of Medical Sciences, Kumamoto University
| | - Yukio Ando
- Department of Amyloidosis Research, Nagasaki International University
| | - Hidetoshi Arima
- Laboratory of Evidence-Based Pharmacotherapy, Daiichi University of Pharmacy
| | - Hirofumi Jono
- Department of Clinical Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Keiichi Motoyama
- Department of Physical Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kumamoto University
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6
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How liposomes pave the way for ocular drug delivery after topical administration. J Drug Deliv Sci Technol 2022. [DOI: 10.1016/j.jddst.2021.103045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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7
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Effects of ultraviolet radiation on mole rats kidney: A histopathologic and ultrastructural study. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2019. [DOI: 10.1016/j.jrras.2014.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Sijilmassi O, López-Alonso JM, Del Río Sevilla A, Murillo González J, Barrio Asensio MDC. Biometric Alterations of Mouse Embryonic Eye Structures Due to Short-Term Folic Acid Deficiency. Curr Eye Res 2018; 44:428-435. [PMID: 30403890 DOI: 10.1080/02713683.2018.1545911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE Folic acid (FA) is an essential nutrient for normal embryonic development. FA deficiency (FAD) in maternal diet increases the risk of several defects among the progeny, especially, neural tube defects. The eye begins its development from the neural tube; however, the relationship between FAD and ocular development in the offspring has been little explored and it isn't known how the FAD affects the formation of the eye. Our objective was to analyze the effect of maternal FAD on mouse embryos ocular biometry. METHODS Female mice C57/BL/6J were distributed into three different groups, according to the assigned diet: control group fed a standard FA diet (2 mg FA/kg), FAD group for short term fed (0 mg FA/kg + 1% succinylsulfathiazole) from the day after mating until day 14.5 of gestation, and FAD group for long term fed the same FA-deficient diet for 6 weeks prior mating and continued with this diet during gestation. A total of 57 embryos (19 embryos of each dietary group) at 14.5 gestational days were evaluated. As indicators of changes in ocular biometry, we analyze two parameters: area and circularity of the lens and whole eye, and the area of the retina. The program used in the treatment and selection of the areas of interest was ImageJ. The statistical analysis was performed by IBM SPSS Statistics 19. RESULTS Regarding the measures of the area, FA-deficient lenses and eyes were smaller than that of controls. We have also observed increase in the size of the neural retina, spatially, in embryos from females fed FAD diet during long term. On the other hand, as regard to circularity measures, we have seen that eyes and lenses were more circular than control. CONCLUSION Maternal FAD diet for a very short term generates morphological changes in ocular structures to the offspring.
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Affiliation(s)
- Ouafa Sijilmassi
- a Faculty of Optics and Optometry, Anatomy and Human Embryology Department , Universidad Complutense De Madrid , Madrid , Spain.,b Faculty of Optics and Optometry, Optics Department , Universidad Complutense De Madrid , Madrid , Spain
| | - José Manuel López-Alonso
- b Faculty of Optics and Optometry, Optics Department , Universidad Complutense De Madrid , Madrid , Spain
| | - Aurora Del Río Sevilla
- a Faculty of Optics and Optometry, Anatomy and Human Embryology Department , Universidad Complutense De Madrid , Madrid , Spain
| | - Jorge Murillo González
- c Faculty of medicine, Anatomy and Human Embryology Department , Universidad Complutense De Madrid , Madrid , Spain
| | - María Del Carmen Barrio Asensio
- a Faculty of Optics and Optometry, Anatomy and Human Embryology Department , Universidad Complutense De Madrid , Madrid , Spain
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Kelley RA, Al-Ubaidi MR, Sinha T, Genc AM, Makia MS, Ikelle L, Naash MI. Ablation of the riboflavin-binding protein retbindin reduces flavin levels and leads to progressive and dose-dependent degeneration of rods and cones. J Biol Chem 2017; 292:21023-21034. [PMID: 29079576 DOI: 10.1074/jbc.m117.785105] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 10/26/2017] [Indexed: 11/06/2022] Open
Abstract
The interface between the neural retina and the retinal pigment epithelium (RPE) is critical for several processes, including visual pigment regeneration and retinal attachment to the RPE. One of its most important functions is the exchange of metabolites between the photoreceptors and RPE because photoreceptor cells have very high energy demands, largely satisfied by oxidative metabolism. The riboflavin (RF) cofactors, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), are two key cofactors involved in oxidative metabolism. We have previously shown that retbindin is a photoreceptor-specific RF-binding protein exclusively expressed in the rods and present in the interphotoreceptor matrix at the interface between the RPE and photoreceptor outer segments. Here, we show that retbindin ablation in mice causes a retinal phenotype characterized by time- and dose-dependent declines in rod and cone photoreceptor functions as early as 120 days of age. Whereas minor retinal ultrastructural defects were observed at all ages examined, a significant decline occurred in photoreceptor nuclei at 240 days of age (∼36.8% rods and ∼19.9% cones). Interestingly, significant reductions in FAD and FMN levels were observed before the onset of degeneration (∼46.1% FAD and ∼45% FMN). These findings suggest that the reduced levels of these flavins result in the disruption of intracellular mechanisms, leading to photoreceptor cell death. Altogether, our results suggest that retbindin is a key player in the acquisition and retention of flavins in the neural retina, warranting future investigation into retbindin's role in photoreceptor cell death in models of retinal degenerative disorders.
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Affiliation(s)
- Ryan A Kelley
- From the Department of Biomedical Engineering, University of Houston, Houston, Texas 77204
| | - Muayyad R Al-Ubaidi
- From the Department of Biomedical Engineering, University of Houston, Houston, Texas 77204
| | - Tirthankar Sinha
- From the Department of Biomedical Engineering, University of Houston, Houston, Texas 77204
| | - Ayse M Genc
- From the Department of Biomedical Engineering, University of Houston, Houston, Texas 77204
| | - Mustafa S Makia
- From the Department of Biomedical Engineering, University of Houston, Houston, Texas 77204
| | - Larissa Ikelle
- From the Department of Biomedical Engineering, University of Houston, Houston, Texas 77204
| | - Muna I Naash
- From the Department of Biomedical Engineering, University of Houston, Houston, Texas 77204
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Pelkonen L, Sato K, Reinisalo M, Kidron H, Tachikawa M, Watanabe M, Uchida Y, Urtti A, Terasaki T. LC–MS/MS Based Quantitation of ABC and SLC Transporter Proteins in Plasma Membranes of Cultured Primary Human Retinal Pigment Epithelium Cells and Immortalized ARPE19 Cell Line. Mol Pharm 2017; 14:605-613. [DOI: 10.1021/acs.molpharmaceut.6b00782] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Laura Pelkonen
- School
of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Kazuki Sato
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Sendai, Japan
| | - Mika Reinisalo
- School
of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Heidi Kidron
- Centre
for Drug Research, Division of Pharmaceutical Biosciences, Faculty
of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 Helsinki, Finland
| | - Masanori Tachikawa
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Sendai, Japan
| | - Michitoshi Watanabe
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Sendai, Japan
| | - Yasuo Uchida
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Sendai, Japan
| | - Arto Urtti
- School
of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70210 Kuopio, Finland
- Centre
for Drug Research, Division of Pharmaceutical Biosciences, Faculty
of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 Helsinki, Finland
| | - Tetsuya Terasaki
- Division
of Membrane Transport and Drug Targeting, Graduate School of Pharmaceutical
Sciences, Tohoku University, Sendai, Japan
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Naggar H, Van Ells TK, Ganapathy V, Smith SB. Regulation of Reduced-Folate Transporter-1 in Retinal Pigment Epithelial Cells by Folate. Curr Eye Res 2015. [DOI: 10.1080/02713680490894559a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Vellonen KS, Malinen M, Mannermaa E, Subrizi A, Toropainen E, Lou YR, Kidron H, Yliperttula M, Urtti A. A critical assessment of in vitro tissue models for ADME and drug delivery. J Control Release 2014; 190:94-114. [DOI: 10.1016/j.jconrel.2014.06.044] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/22/2014] [Accepted: 06/23/2014] [Indexed: 12/22/2022]
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13
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Suen WLL, Chau Y. Specific uptake of folate-decorated triamcinolone-encapsulating nanoparticles by retinal pigment epithelium cells enhances and prolongs antiangiogenic activity. J Control Release 2013; 167:21-8. [DOI: 10.1016/j.jconrel.2013.01.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 12/19/2012] [Accepted: 01/02/2013] [Indexed: 12/24/2022]
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Abstract
The eye is a highly protected organ, and designing an effective therapy is often considered a challenging task. The anatomical and physiological barriers result in low ocular bioavailability of drugs. Due to these constraints, less than 5% of the administered dose is absorbed from the conventional ophthalmic dosage forms. Further, physicochemical properties such as lipophilicity, molecular weight and charge modulate the permeability of drug molecules. Vision-threatening diseases such as glaucoma, diabetic macular edema, cataract, wet and dry age-related macular degeneration, proliferative vitreoretinopathy, uveitis, and cytomegalovirus retinitis alter the pathophysiological and molecular mechanisms. Understanding these mechanisms may result in the development of novel treatment modalities. Recently, transporter/receptor targeted prodrug approach has generated significant interest in ocular drug delivery. These transporters and receptors are involved in the transport of essential nutrients, vitamins, and xenobiotics across biological membranes. Several influx transporters (peptides, amino acids, glucose, lactate and nucleosides/nucleobases) and receptors (folate and biotin) have been identified on conjunctiva, cornea, and retina. Structural and functional delineation of these transporters will enable more drugs targeting the posterior segment to be successfully delivered topically. Prodrug derivatization targeting transporters and receptors expressed on ocular tissues has been the subject of intense research. Several prodrugs have been designed to target these transporters and enhance the absorption of poorly permeating parent drug. Moreover, this approach might be used in gene delivery to modify cellular function and membrane receptors. This review provides comprehensive information on ocular drug delivery, with special emphasis on the use of transporters and receptors to improve drug bioavailability.
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Tomi M, Hosoya KI. The role of blood–ocular barrier transporters in retinal drug disposition: an overview. Expert Opin Drug Metab Toxicol 2010; 6:1111-24. [DOI: 10.1517/17425255.2010.486401] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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16
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Bozard BR, Ganapathy PS, Duplantier J, Mysona B, Ha Y, Roon P, Smith R, Goldman ID, Prasad P, Martin PM, Ganapathy V, Smith SB. Molecular and biochemical characterization of folate transport proteins in retinal Müller cells. Invest Ophthalmol Vis Sci 2010; 51:3226-35. [PMID: 20053979 DOI: 10.1167/iovs.09-4833] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
PURPOSE To analyze the mechanisms of folate uptake in retinal Müller cells. METHODS RT-PCR and Western blot analysis were performed in freshly isolated neural retina and RPE/eyecup, primary mouse Müller cells, and rMC-1 cells for the three known folate transport proteins folate receptor alpha (FRalpha), proton-coupled folate transporter (PCFT), and reduced folate carrier (RFC). Laser scanning confocal microscopy (LSCM) and immunoelectron microscopy were used to determine the subcellular location of FRalpha and PCFT in primary Müller cells. The pH dependence of the uptake of [(3)H]-methyltetrahydrofolate ([(3)H]-MTF) was assayed in Müller cells in the presence/absence of thiamine pyrophosphate, an inhibitor of RFC. RESULTS FRalpha and PCFT are expressed abundantly in the retina in several cell layers, including the inner nuclear layer; they are present in primary mouse Müller cells and rMC-1 cells. LSCM localized these proteins to the plasma membrane, nuclear membrane, and perinuclear region. Immunoelectron microscopic studies revealed the colocalization of FRalpha and PCFT on the plasma membrane and nuclear membrane and within endosomal structures. Müller cell uptake of [(3)H]-MTF was robust at pH 5.0 to 6.0, consistent with PCFT activity, but also at neutral pH, reflecting RFC function. RFC was expressed in mouse Müller cells that had been allowed to proliferate in culture, but not in freshly isolated primary cells. CONCLUSIONS FRalpha and PCFT are expressed in retinal Müller cells and colocalize in the endosomal compartment, suggesting that the two proteins may work coordinately to mediate folate uptake. The unexpected finding of RFC expression and activity in cultured Müller cells may reflect the upregulation of this protein under proliferative conditions.
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Affiliation(s)
- B Renee Bozard
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, Georgia 30912-2000, USA
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Akanuma SI, Yamamoto A, Okayasu S, Tachikawa M, Hosoya KI. High-density lipoprotein-associated alpha-tocopherol uptake by human retinal pigment epithelial cells (ARPE-19 Cells): the irrelevance of scavenger receptor class B, type I. Biol Pharm Bull 2009; 32:1131-4. [PMID: 19483330 DOI: 10.1248/bpb.32.1131] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to determine the high-density lipoprotein (HDL)-associated alpha-tocopherol (alpha-tocopherol-HDL) transport and clarify the contribution of scavenger receptor class B, type I (SR-BI) to the uptake in the human retinal pigment epithelial cell line (ARPE-19 cells). [(3)H]alpha-Tocopherol-HDL uptake into ARPE-19 cells seeded onto a transwell from both the apical (apical-to-cell) and basal compartment (basal-to-cell) exhibited a time-dependent increase for 90 min and there was a reduction at 4 degrees C. These results indicate the involvement of carrier-mediated process in alpha-tocopherol-HDL uptake in ARPE-19 cells. Immunoblot analysis revealed that SR-BI protein was expressed in ARPE-19 cells. However, the uptake of [(3)H]alpha-tocopherol from the apical or basal compartment was hardly inhibited by block lipid transport-1 (BLT-1), a specific inhibitor of the SR-BI-mediated lipid transfer. In conclusion, ARPE-19 cells have a carrier-mediated transport mechanism of [(3)H]alpha-tocopherol-HDL regardless of any SR-BI-mediated process.
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Affiliation(s)
- Shin-ichi Akanuma
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
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18
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Majumdar S, Macha S, Pal D, Mitra AK. Mechanism of ganciclovir uptake by rabbit retina and human retinal pigmented epithelium cell line ARPE-19. Curr Eye Res 2009; 29:127-36. [PMID: 15512959 DOI: 10.1080/02713680490504678] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE The objective of this study was to elucidate the mechanism of ganciclovir uptake by the rabbit retina and the human retinal pigmented epithelium cell line ARPE-19. MATERIALS AND METHODS [(3)H]Adenine, [(3)H]adenosine, [(3)H]thymidine, and [(3)H]ganciclovir were used to elucidate the mechanism of ganciclovir uptake by the ARPE-19 cell line and the isolated rabbit retinal tissue. Uptake studies using ARPE-19 cell line and isolated rabbit retina were carried out at 37 degrees C and 25 degrees C, respectively, for 5 min. RESULTS Uptake of [(3)H]adenine by ARPE-19 cells decreased by 95% in the presence of unlabeled adenine. Other nucleobases such as guanine, thymine, and uracil and the nucleosides adenosine, guanosine, thymidine, uridine, and inosine also reduced uptake of [(3)H]adenine by the ARPE-19 cells. Although [(3)H]adenosine and [(3)H]thymidine uptake was inhibited by nucleosides, nucleobases did not demonstrate any inhibitory effect, indicating that nucleosides can only bind to the nucleobase transporter but are not translocated by it. Uptake of the nucleosides and nucleobases by the ARPE-19 cells was sodium and pH independent. [(3)H]adenosine and [(3)H]thymidine uptake by the ARPE-19 cells was inhibited by nanomolar quantities of nitrobenzylthioinosine. Uptake of [(3)H]adenine by the isolated rabbit retina was drastically reduced in the presence of unlabeled adenine. Unlabeled thymidine and guanosine, and removal of sodium from the uptake medium, inhibited uptake of [(3)H]thymidine by the rabbit retina. Nucleosides, nucleobases, and unlabeled ganciclovir did not exhibit any inhibitory effect on [(3)H]ganciclovir uptake by the isolated rabbit retina or ARPE-19 cells. CONCLUSIONS Our results indicate that although the rabbit retina and the ARPE-19 cell line express nucleoside and nucleobase transporters, translocation of ganciclovir does not involve any carrier-mediated transport process. Rather, ganciclovir uptake by the rabbit retina and ARPE-19 cells is governed primarily by passive diffusion.
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Affiliation(s)
- Soumyajit Majumdar
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, Kansas City, MO 64110-2499, USA
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19
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Kansara V, Mitra AK. Evaluation of anEx VivoModel Implication for Carrier-Mediated Retinal Drug Delivery. Curr Eye Res 2009; 31:415-26. [PMID: 16714233 DOI: 10.1080/02713680600646890] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE The purpose of this study was to evaluate the implication of an ex vivo model for carrier-mediated retinal drug delivery using an Ussing chamber system. METHODS Dutch Belted Pigmented rabbits weighing 2-2.5 kg were used in these studies. Excised posterior segment tissues (RPE-choroid-sclera and sclera), mounted on the Ussing chamber, were used as an ex vivo model. Transport studies were carried out across sclera and RPE-choroid-sclera (RCS) tissue preparations in the sclera to retina (S --> R) and retina to sclera (R --> S) directions for 3 hr at 37 degrees C. The model was validated by permeability studies with paracellular and transcellular markers ([(3)H]mannitol and [(14)C]diazepam, respectively), tissue viability studies (bioelectrical and biochemical assays), and tissue histology and electron microscopy studies. Functional presence of a carrier-mediated transport system for folic acid (folate receptor alpha) was investigated on the basolateral side of the rabbit retina. RESULTS Results from bioelectrical, biochemical, and histological evaluation of tissue provide evidence that the RCS tissue preparation remains viable during the period of transport study. Permeability values of [(3)H]mannitol across sclera were 4.18 +/- 1.09 x 10(- 5) cm/s (R --> S) and 4.11 +/- 1.09 x 10(- 5) cm/s (S --> R) and across RCS were 1.77 +/- 0.31 x 10(- 5) cm/s (S --> R) and 1.60 +/- 0.19 x 10(- 5) cm/s (R --> S). Permeability values of [(14)C]diazepam across sclera were 2.37 +/- 0.38 x 10(- 5) cm/s (R --> S) and 2.70 +/- 0.70 x 10(- 5) cm/s (S --> R) and across RCS were 3.12 +/- 0.12 x 10(- 5) cm/s (R --> S) and 2.77 +/- 0.25 x 10(- 5)cm/s (S --> R). The rate of [(3)H]folic acid transport across RCS was found to be significantly higher in the S -->R direction (16.34 +/- 0.94 fmoles min(-1) cm(-2)) as compared with R --> S direction (9.38 +/- 1.44 fmoles min(-1) cm(-2)) and nearly 10-fold higher across sclera as compared with RCS in both directions. Transport of [(3)H]folic acid was found to be pH and temperature dependent and was inhibited by 44.5%, 35.1%, and 50.3% in the presence of unlabeled folic acid, 5-methyltetrahydrofolate (MTF), and Methotrexate (MTX). CONCLUSIONS The RCS tissue preparation mounted on the Ussing chamber system, an ex vivo model, can be a useful tool for identification and characterization of carrier-mediated systems present on RPE (a major barrier for retinal drug delivery) and to study carrier-mediated retinal drug delivery via prodrug derivatization.
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Affiliation(s)
- Viral Kansara
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 5005 Rockhill Road, Kansas City, MO 64112, USA
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20
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Kansara V, Paturi D, Luo S, Gaudana R, Mitra AK. Folic acid transport via high affinity carrier-mediated system in human retinoblastoma cells. Int J Pharm 2007; 355:210-9. [PMID: 18207340 DOI: 10.1016/j.ijpharm.2007.12.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 12/07/2007] [Accepted: 12/10/2007] [Indexed: 12/21/2022]
Abstract
The primary objective of this study was to investigate the expression of a specialized carrier-mediated system for folic acid and to delineate its uptake mechanism and intracellular trafficking in a human derived retinoblastoma cell line (Y-79). Uptake of [3H]Folic acid was determined at various concentrations, pH, temperatures, in the absence of sodium and chloride ions and in the presence of structural analogs, methyltetrahydro folate (MTF) and methotrexate (MTX), vitamins, membrane transport and metabolic inhibitors to delineate the mechanism of uptake. Kinetics of uptake was studied in the presence of various intracellular regulatory pathways; protein kinases A and C (PKA and PKC), protein tyrosine kinase (PTK) and calcium-calmodulin modulators. Reverse transcription polymerase chain reaction (RT-PCR) was performed to confirm the molecular identity of folate carrier systems. The uptake was found to be linear up to 30min. The rate of uptake followed saturation kinetics with apparent Km of 8.29+/-0.74nM, 17.03+/-1.98nM and 563.23+/-115.2nM and Vmax of 393.47+/-9.33, 757.58+/-26.21 and 653.17+/-31.7fmol/(minmg) protein for folic acid, MTF and MTX, respectively. The process was chloride, temperature and energy dependent but sodium and pH independent; inhibited by the structural analogs MTF and MTX but not by structurally unrelated vitamins. Membrane transport inhibitors did not affect the uptake of [3H]Folic acid, however endocytic inhibitor, colchicine, significantly inhibited the [3H]Folic acid uptake indicating the involvement of receptor mediated endocytosis process. PKC, PTK and Ca2+/calmodulin pathways appeared to play important roles in the regulation of folic acid uptake. Molecular evidence of the presence of folate receptor (FR) precursor was identified by RT-PCR analysis. This research work demonstrated, for the first time, the functional and molecular existence of a specialized high affinity carrier-mediated system for folic acid uptake, in human retinoblastoma cells.
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Affiliation(s)
- Viral Kansara
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 5005 Rockhill Road, Kansas City, MO 64110-2499, USA
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21
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Umapathy NS, Gnana-Prakasam JP, Martin PM, Mysona B, Dun Y, Smith SB, Ganapathy V, Prasad PD. Cloning and functional characterization of the proton-coupled electrogenic folate transporter and analysis of its expression in retinal cell types. Invest Ophthalmol Vis Sci 2007; 48:5299-305. [PMID: 17962486 DOI: 10.1167/iovs.07-0288] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE In a prior study the cellular uptake of folate was investigated in the retina. Recently, a new proton-coupled folate transporter (PCFT) in human intestine was reported. In the present study, the expression of this novel transporter in the retina was determined, the mouse orthologue was cloned from retinal tissue, and its transport function was characterized. METHODS RT-PCR and folate uptake measurements were used to detect the expression of PCFT in mouse retina and in retinal cell types. The expression of PCFT mRNA in intact retina was investigated by in situ hybridization. Mouse PCFT cDNA was cloned, and its transport characteristics were analyzed by electrophysiological methods after expression of the cloned transporter in Xenopus laevis oocytes. RESULTS RT-PCR showed expression of PCFT mRNA in both neural retina and RPE eye cup. In situ hybridization detected PCFT mRNA in all retinal cell layers. Proton-coupled folate uptake was detectable in primary cultures of ganglion, Müller, and RPE cells of mouse retina and in RPE, ganglion, and Müller cells of human or rat origin. In X. laevis oocytes expressing the cloned mouse PCFT, folate and its derivatives methotrexate and 5-methyltetrahydrofolate induced H(+)-coupled inward currents with K(t) values of 1.2 +/- 0.1, 4.6 +/- 0.5, and 3.5 +/- 0.8 microM, respectively. The transport process showed an H(+)-folate stoichiometry of 1:1, suggesting that PCFT transports the zwitterionic form of folate. CONCLUSIONS This is the first report on the expression of PCFT in the retina. All cell layers of the retina express this transporter. Mouse PCFT, cloned from retina, mediates H(+)-coupled electrogenic transport of folate and its derivatives.
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Affiliation(s)
- Nagavedi S Umapathy
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, GA 30912, USA
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22
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Mannermaa E, Vellonen KS, Urtti A. Drug transport in corneal epithelium and blood-retina barrier: emerging role of transporters in ocular pharmacokinetics. Adv Drug Deliv Rev 2006; 58:1136-63. [PMID: 17081648 DOI: 10.1016/j.addr.2006.07.024] [Citation(s) in RCA: 219] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Accepted: 07/31/2006] [Indexed: 12/12/2022]
Abstract
Corneal epithelium and blood-retina barrier (i.e. retinal capillaries and retinal pigment epithelium (RPE)) are the key membranes that regulate the access of xenobiotics into the ocular tissues. Corneal epithelium limits drug absorption from the lacrimal fluid into the anterior chamber after eyedrop administration, whereas blood-retina barrier restricts the entry of drugs from systemic circulation to the posterior eye segment. Like in general pharmacokinetics, the role of transporters has been considered to be quite limited as compared to the passive diffusion of drugs across the membranes. As the functional role of transporters is being revealed it has become evident that the transporters are widely important in pharmacokinetics. This review updates the current knowledge about the transporters in the corneal epithelium and blood-retina barrier and demonstrates that the information is far from complete. We also show that quite many ocular drugs are known to interact with transporters, but the studies about the expression and function of those transporters in the eye are still sparse. Therefore, the transporters probably have greater role in ocular pharmacokinetics than we currently realise.
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Affiliation(s)
- Eliisa Mannermaa
- Department of Pharmaceutics, University of Kuopio, FIN-70211 Kuopio, Finland
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23
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Hornof M, Toropainen E, Urtti A. Cell culture models of the ocular barriers. Eur J Pharm Biopharm 2005; 60:207-25. [PMID: 15939234 DOI: 10.1016/j.ejpb.2005.01.009] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Revised: 12/28/2004] [Accepted: 01/10/2005] [Indexed: 12/21/2022]
Abstract
The presence of tight barriers, which regulate the environment of ocular tissues in the anterior and posterior part of the eye, is essential for normal visual function. The development of strategies to overcome these barriers for the targeted ocular delivery of drugs, e.g. to the retina, remains a major challenge. During the last years numerous cell culture models of the ocular barriers (cornea, conjunctiva, blood-retinal barrier) have been established. They are considered to be promising tools for studying the drug transport into ocular tissues, and for numerous other purposes, such as the investigation of pathological ocular conditions, and the toxicological screening of compounds as alternative to in vivo toxicity tests. The further development of these in vitro models will require more detailed investigations of the barrier properties of both the cell culture models and the in vivo ocular barriers. It is the aim of this review to describe the current status in the development of cell culture models of the ocular barriers, and to discuss the applicability of these models in pharmaceutical research.
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Affiliation(s)
- Margit Hornof
- Department of Pharmaceutics, University of Kuopio, Kuopio, Finland
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Majumdar S, Gunda S, Pal D, Mitra AK. Functional activity of a monocarboxylate transporter, MCT1, in the human retinal pigmented epithelium cell line, ARPE-19. Mol Pharm 2005; 2:109-17. [PMID: 15804185 DOI: 10.1021/mp0499050] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The purpose of this study was to identify and characterize the functional activity of monocarboxylic acid transporter 1 (MCT1) on the human retinal pigmented epithelium (RPE) cell line, ARPE-19, and to evaluate whether the cell line can function as an in vitro screening tool for intravitreally administered drugs/prodrugs targeted to the MCT1 expressed in RPE. Uptake studies were carried out at 37 degrees C, for 30 s, with ARPE-19 cells. [(14)C]l-Lactic acid was selected as a substrate for this transporter. Uptake of [(14)C]L-lactic acid by ARPE-19 cells was found to exhibit saturable kinetics (K(m) = 3.1 +/- 0.6 mM and V(max) = 63.1 +/- 4.1 pmol/min/mg of protein). Monocarboxylic acids, such as benzoic acid, salicylic acid, and pyruvic acid, inhibited the uptake of [(14)C]L-lactic acid whereas di- and tricarboxylic acids, such as phthalic, succinic, and citric acids, did not demonstrate any inhibitory effect. Uptake was stereospecific where D-lactic acid was less effective in inhibiting [(14)C]L-lactic acid uptake than unlabeled L-lactic acid. ELISA indicated the expression of only MCT1, MCT4, and MCT8 isoforms by ARPE-19 cells. Increase in [(14)C]L-lactic acid uptake was observed as the uptake medium pH was lowered from 7.4 to 5.0. Moreover, inhibition of [(14)C]L-lactic acid uptake was observed in the presence of the protonophore 2,4-dinitrophenol. Uptake was significantly decreased in the presence of sodium azide, ouabain, p-chloromercuribenzoic acid (pCMBA), N-ethylmaleamide, dithiothreitol, and p-chloromercuribenzene sulfonate (pCMBS). However, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and L-thyroxine did not inhibit [(14)C]L-lactic acid. RT-PCR studies and sequence analysis of the PCR product confirmed the expression of MCT1 by ARPE-19 cells. Our results indicate that MCT1 is functionally active and is the only MCT isoform involved in the apical uptake of monocarboxylates by ARPE-19 cells. This cell line may thus be used as an effective screening tool for intravitreally administered drugs/prodrugs targeted toward MCT1 expressed on the RPE.
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Affiliation(s)
- Soumyajit Majumdar
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 5005 Rockhill Road, Kansas City, MO 64110, USA
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25
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Majumdar S, Duvvuri S, Mitra AK. Membrane transporter/receptor-targeted prodrug design: strategies for human and veterinary drug development. Adv Drug Deliv Rev 2004; 56:1437-52. [PMID: 15191791 DOI: 10.1016/j.addr.2004.02.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2003] [Accepted: 02/18/2004] [Indexed: 01/12/2023]
Abstract
The bioavailability of drugs is often severely limited due to the presence of biological barriers in the form of epithelial tight junctions, efflux proteins and enzymatic degradation. Physicochemical properties, such as lipophilicity, molecular weight, charge, etc., also play key roles in determining the permeation properties of drug candidates. As a result, many potential drug candidates may be dropped from the initial screening portfolio. Prodrug derivatization targeting transporters and receptors expressed on mammalian cells holds tremendous potential. Enhanced cellular delivery can significantly improve drug absorption. Such approaches of drug targeting and delivery have been the subject of intense research. Various prodrugs have been designed that demonstrate enhanced bioavailability and tissue specificity. This approach is equally applicable to human and veterinary pharmaceuticals since most of the transporters and receptors expressed by human tissues are also expressed in animals. This review highlights studies conducted on the use of transporters and receptors in an effort to improve drug bioavailability and to develop targeted drug delivery systems.
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Affiliation(s)
- Soumyajit Majumdar
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 5005 Rockhill Road, Kansas City, MO 64110, USA
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26
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Boulware MJ, Subramanian VS, Said HM, Marchant JS. Polarized expression of members of the solute carrier SLC19A gene family of water-soluble multivitamin transporters: implications for physiological function. Biochem J 2003; 376:43-8. [PMID: 14602044 PMCID: PMC1223768 DOI: 10.1042/bj20031220] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Humans lack biochemical pathways for the synthesis of the micro-nutrients thiamine and folate. Cellular requirements are met through membrane transport activity, which is mediated by proteins of the SLC19A gene family. By using live-cell confocal imaging methods to resolve the localization of all SLC19A family members, we show that the two human thiamine transporters are differentially targeted in polarized cells, establishing a vectorial transport system. Such polarization decreases functional redundancy between transporter isoforms and allows for independent regulation of thiamine import and export pathways in cells.
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Affiliation(s)
- Michael J Boulware
- Department of Pharmacology, 321 Church Street SE, University of Minnesota Medical School, MN 55455, USA
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Naggar H, Fei YJ, Ganapathy V, Smith SB. Regulation of reduced-folate transporter-1 (RFT-1) by homocysteine and identity of transport systems for homocysteine uptake in retinal pigment epithelial (RPE) cells. Exp Eye Res 2003; 77:687-97. [PMID: 14609557 DOI: 10.1016/j.exer.2003.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reduced-folate transporter-1 (RFT-1) transports reduced-folates, such as N5-methyltetrahydrofolate (MTF), the predominant circulating form of folate. In RPE, RFT-1 is localized to the apical membrane and is thought to transport folate from RPE to photoreceptor cells. Folate is required for DNA, RNA, protein synthesis and the conversion of homocysteine (Hcy) to methionine. Decreased folate levels are associated with increased Hcy levels. In the present study, we asked whether RFT-1 activity in RPE is altered under high Hcy conditions and examined the transport mechanism for Hcy in RPE. Treatment of ARPE-19 cells, a human RPE cell line, with Hcy at concentrations higher than 50 microM led to a significant decrease in RFT-1 activity. This effect increased as the treatment time increased. The inhibitory effect of Hcy on RFT-1 activity was not non-specific, as the activities of several other nutrient transporters were not affected under identical conditions. The effect of Hcy on RFT-1 was associated primarily with a decrease in the maximal velocity with no detectable change in substrate affinity. The decrease in RFT-1 activity was accompanied by parallel changes in RFT-1 mRNA and protein. Uptake of Hcy in ARPE-19 cells occurred via several transport systems, including Na+-independent systems L and b(0,+) and the Na+-dependent systems B0, ATB(0,+) and A. Studies of the interaction of Hcy with one of the cloned transporters (ATB(0,+)) provided direct evidence for the translocation of Hcy across the membrane via the transporter. We conclude that several transport systems operate in ARPE-19 cells for the entry of Hcy and that high levels of Hcy have deleterious effects on the expression and activity of RFT-1 in these cells.
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Affiliation(s)
- Hany Naggar
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912-2000, USA
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