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Stary D, Bajda M. Structural Studies of the Taurine Transporter: A Potential Biological Target from the GABA Transporter Subfamily in Cancer Therapy. Int J Mol Sci 2024; 25:7339. [PMID: 39000444 PMCID: PMC11242302 DOI: 10.3390/ijms25137339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/28/2024] [Accepted: 07/02/2024] [Indexed: 07/16/2024] Open
Abstract
The taurine transporter (TauT, SLC6A6) is a member of the solute carrier 6 (SLC6) family, which plays multiple physiological roles. The SLC6 family is divided into four subfamilies: GABA (γ-aminobutyric acid), monoamine, glycine and neutral amino acid transporters. Proteins from the GABA group, including the taurine transporter, are primarily considered therapeutic targets for treating central nervous system disorders. However, recent studies have suggested that inhibitors of SLC6A6 could also serve as anticancer agents. Overexpression of TauT has been associated with the progression of colon and gastric cancer. The pool of known ligands of this transporter is limited and the exact spatial structure of taurine transporter remains unsolved. Understanding its structure could aid in the development of novel inhibitors. Therefore, we utilized homology modelling techniques to create models of TauT. Docking studies and molecular dynamics simulations were conducted to describe protein-ligand interactions. We compared the obtained information for TauT with literature data on other members of the GABA transporter group. Our in silico analysis allowed us to characterize the transporter structure and point out amino acids crucial for ligand binding: Glu406, Gly62 and Tyr138. The significance of selected residues was confirmed through structural studies of mutants. These results will aid in the development of novel taurine transporter inhibitors, which can be explored as anticancer agents.
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Affiliation(s)
- Dorota Stary
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Cracow, Poland
- Doctoral School of Medical and Health Sciences, Jagiellonian University Medical College, św. Łazarza 16, 31-530 Cracow, Poland
| | - Marek Bajda
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Cracow, Poland
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2
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Bejarano E, Domenech-Bendaña A, Avila-Portillo N, Rowan S, Edirisinghe S, Taylor A. Glycative stress as a cause of macular degeneration. Prog Retin Eye Res 2024; 101:101260. [PMID: 38521386 DOI: 10.1016/j.preteyeres.2024.101260] [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: 01/05/2024] [Revised: 03/08/2024] [Accepted: 03/11/2024] [Indexed: 03/25/2024]
Abstract
People are living longer and rates of age-related diseases such as age-related macular degeneration (AMD) are accelerating, placing enormous burdens on patients and health care systems. The quality of carbohydrate foods consumed by an individual impacts health. The glycemic index (GI) is a kinetic measure of the rate at which glucose arrives in the blood stream after consuming various carbohydrates. Consuming diets that favor slowly digested carbohydrates releases sugar into the bloodstream gradually after consuming a meal (low glycemic index). This is associated with reduced risk for major age-related diseases including AMD, cardiovascular disease, and diabetes. In comparison, consuming the same amounts of different carbohydrates in higher GI diets, releases glucose into the blood rapidly, causing glycative stress as well as accumulation of advanced glycation end products (AGEs). Such AGEs are cytotoxic by virtue of their forming abnormal proteins and protein aggregates, as well as inhibiting proteolytic and other protective pathways that might otherwise selectively recognize and remove toxic species. Using in vitro and animal models of glycative stress, we observed that consuming higher GI diets perturbs metabolism and the microbiome, resulting in a shift to more lipid-rich metabolomic profiles. Interactions between aging, diet, eye phenotypes and physiology were observed. A large body of laboratory animal and human clinical epidemiologic data indicates that consuming lower GI diets, or lower glycemia diets, is protective against features of early AMD (AMDf) in mice and AMD prevalence or AMD progression in humans. Drugs may be optimized to diminish the ravages of higher glycemic diets. Human trials are indicated to determine if AMD progression can be retarded using lower GI diets. Here we summarized the current knowledge regarding the pathological role of glycative stress in retinal dysfunction and how dietary strategies might diminish retinal disease.
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Affiliation(s)
- Eloy Bejarano
- Department of Biomedical Sciences, School of Health Sciences and Veterinary School, Universidad Cardenal Herrera-CEU, CEU Universities, Valencia, Spain
| | - Alicia Domenech-Bendaña
- Department of Biomedical Sciences, School of Health Sciences and Veterinary School, Universidad Cardenal Herrera-CEU, CEU Universities, Valencia, Spain
| | | | - Sheldon Rowan
- JM USDA Human Nutrition Research Center on Aging at Tufts University, United States
| | - Sachini Edirisinghe
- Tufts University Friedman School of Nutrition Science and Policy, United States
| | - Allen Taylor
- Tufts University Friedman School of Nutrition Science and Policy, United States.
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Shimada H, Powell TL, Jansson T. Regulation of placental amino acid transport in health and disease. Acta Physiol (Oxf) 2024; 240:e14157. [PMID: 38711335 PMCID: PMC11162343 DOI: 10.1111/apha.14157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/19/2024] [Accepted: 04/23/2024] [Indexed: 05/08/2024]
Abstract
Abnormal fetal growth, i.e., intrauterine growth restriction (IUGR) or fetal growth restriction (FGR) and fetal overgrowth, is associated with increased perinatal morbidity and mortality and is strongly linked to the development of metabolic and cardiovascular disease in childhood and later in life. Emerging evidence suggests that changes in placental amino acid transport may contribute to abnormal fetal growth. This review is focused on amino acid transport in the human placenta, however, relevant animal models will be discussed to add mechanistic insights. At least 25 distinct amino acid transporters with different characteristics and substrate preferences have been identified in the human placenta. Of these, System A, transporting neutral nonessential amino acids, and System L, mediating the transport of essential amino acids, have been studied in some detail. Importantly, decreased placental Systems A and L transporter activity is strongly associated with IUGR and increased placental activity of these two amino acid transporters has been linked to fetal overgrowth in human pregnancy. An array of factors in the maternal circulation, including insulin, IGF-1, and adiponectin, and placental signaling pathways such as mTOR, have been identified as key regulators of placental Systems A and L. Studies using trophoblast-specific gene targeting in mice have provided compelling evidence that changes in placental Systems A and L are mechanistically linked to altered fetal growth. It is possible that targeting specific placental amino acid transporters or their upstream regulators represents a novel intervention to alleviate the short- and long-term consequences of abnormal fetal growth in the future.
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Affiliation(s)
- Hiroshi Shimada
- Department of Obstetrics and Gynecology University of Colorado, Anschutz Medical Campus, Aurora, CO, US
- Departments of Obstetrics & Gynecology, Sapporo Medical University, Sapporo, Japan
| | - Theresa L Powell
- Department of Obstetrics and Gynecology University of Colorado, Anschutz Medical Campus, Aurora, CO, US
- Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, CO, US
| | - Thomas Jansson
- Department of Obstetrics and Gynecology University of Colorado, Anschutz Medical Campus, Aurora, CO, US
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Frascatani R, Mattogno A, Iannucci A, Marafini I, Monteleone G. Reduced Taurine Serum Levels in Inflammatory Bowel Disease. Nutrients 2024; 16:1593. [PMID: 38892527 PMCID: PMC11173840 DOI: 10.3390/nu16111593] [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: 05/09/2024] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 06/21/2024] Open
Abstract
Taurine is a semi-essential micronutrient that acts as an anti-inflammatory molecule. The oral administration of taurine to colitic mice attenuates ongoing mucosal inflammation. This study aimed to determine whether inflammatory bowel diseases (IBDs) are marked by changes in the circulating levels of taurine. We measured the serum concentrations of taurine in 92 IBD patients [46 with ulcerative colitis (UC) and 46 with Crohn's disease (CD)] and 33 healthy controls with a commercial ELISA kit. The taurine levels were significantly decreased in both patients with UC and patients with CD compared to the controls, while there was no difference between CD and UC. Taurine levels declined with age in healthy controls but not in IBDs. IBD patients younger than 50 years had levels of taurine reduced compared to their age-matched controls. In the IBD group, taurine levels were not influenced by the body mass index of the patients and the consumption of taurine-rich nutrients, while they were significantly reduced in UC patients with clinically active disease compared to those in clinical remission. These findings indicate that IBDs are marked by serum taurine deficiency, which would seem to reflect the activity of the disease, at least in UC.
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Affiliation(s)
- Rachele Frascatani
- Department of Systems Medicine, University of Rome “Tor Vergata”, 00133 Rome, Italy;
| | | | - Andrea Iannucci
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy;
| | - Irene Marafini
- Policlinico Universitario Tor Vergata, 00133 Rome, Italy (I.M.)
| | - Giovanni Monteleone
- Department of Systems Medicine, University of Rome “Tor Vergata”, 00133 Rome, Italy;
- Policlinico Universitario Tor Vergata, 00133 Rome, Italy (I.M.)
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Lee D, Fu Z, Hellstrom A, Smith LEH. Therapeutic Effects of Anti-Inflammatory and Anti-Oxidant Nutritional Supplementation in Retinal Ischemic Diseases. Int J Mol Sci 2024; 25:5503. [PMID: 38791541 PMCID: PMC11122288 DOI: 10.3390/ijms25105503] [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: 04/17/2024] [Revised: 05/15/2024] [Accepted: 05/16/2024] [Indexed: 05/26/2024] Open
Abstract
Appropriate nutrients are essential for cellular function. Dietary components can alter the risk of systemic metabolic diseases, including cardiovascular diseases, cancer, diabetes, and obesity, and can also affect retinal diseases, including age-related macular degeneration, diabetic retinopathy, and glaucoma. Dietary nutrients have been assessed for the prevention or treatment of retinal ischemic diseases and the diseases of aging. In this article, we review clinical and experimental evidence concerning the potential of some nutritional supplements to prevent or treat retinal ischemic diseases and provide further insights into the therapeutic effects of nutritional supplementation on retinopathies. We will review the roles of nutrients in preventing or protecting against retinal ischemic diseases.
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Affiliation(s)
- Deokho Lee
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Zhongjie Fu
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ann Hellstrom
- The Sahlgrenska Centre for Pediatric Ophthalmology Research, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, 416 85 Gothenburg, Sweden
| | - Lois E. H. Smith
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
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Zhang C, Wang J, Wu H, Fan W, Li S, Wei D, Song Z, Tao Y. Hydrogel-Based Therapy for Age-Related Macular Degeneration: Current Innovations, Impediments, and Future Perspectives. Gels 2024; 10:158. [PMID: 38534576 DOI: 10.3390/gels10030158] [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: 12/29/2023] [Revised: 01/20/2024] [Accepted: 01/23/2024] [Indexed: 03/28/2024] Open
Abstract
Age-related macular degeneration (AMD) is an ocular disease that leads to progressive photoreceptor death and visual impairment. Currently, the most common therapeutic strategy is to deliver anti-vascular endothelial growth factor (anti-VEGF) agents into the eyes of patients with wet AMD. However, this treatment method requires repeated injections, which potentially results in surgical complications and unwanted side effects for patients. An effective therapeutic approach for dry AMD also remains elusive. Therefore, there is a surge of enthusiasm for the developing the biodegradable drug delivery systems with sustained release capability and develop a promising therapeutic strategy. Notably, the strides made in hydrogels which possess intricate three-dimensional polymer networks have profoundly facilitated the treatments of AMD. Researchers have established diverse hydrogel-based delivery systems with marvelous biocompatibility and efficacy. Advantageously, these hydrogel-based transplantation therapies provide promising opportunities for vision restoration. Herein, we provide an overview of the properties and potential of hydrogels for ocular delivery. We introduce recent advances in the utilization of hydrogels for the delivery of anti-VEGF and in cell implantation. Further refinements of these findings would lay the basis for developing more rational and curative therapies for AMD.
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Affiliation(s)
- Chengzhi Zhang
- Department of Ophthalmology, Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital (People's Hospital of Zheng Zhou University), Zhengzhou 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou 450001, China
| | - Jiale Wang
- Department of Ophthalmology, Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital (People's Hospital of Zheng Zhou University), Zhengzhou 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou 450001, China
| | - Hao Wu
- Department of Ophthalmology, Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital (People's Hospital of Zheng Zhou University), Zhengzhou 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou 450001, China
| | - Wenhui Fan
- Department of Ophthalmology, Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital (People's Hospital of Zheng Zhou University), Zhengzhou 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou 450001, China
| | - Siyu Li
- Department of Ophthalmology, Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital (People's Hospital of Zheng Zhou University), Zhengzhou 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou 450001, China
| | - Dong Wei
- Department of Ophthalmology, Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital (People's Hospital of Zheng Zhou University), Zhengzhou 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou 450001, China
| | - Zongming Song
- Department of Ophthalmology, Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital (People's Hospital of Zheng Zhou University), Zhengzhou 450003, China
| | - Ye Tao
- Department of Ophthalmology, Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital (People's Hospital of Zheng Zhou University), Zhengzhou 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou 450001, China
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Rozanowska M, Edge R, Land EJ, Navaratnam S, Sarna T, Truscott TG. Scavenging of Cation Radicals of the Visual Cycle Retinoids by Lutein, Zeaxanthin, Taurine, and Melanin. Int J Mol Sci 2023; 25:506. [PMID: 38203675 PMCID: PMC10779001 DOI: 10.3390/ijms25010506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/26/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
In the retina, retinoids involved in vision are under constant threat of oxidation, and their oxidation products exhibit deleterious properties. Using pulse radiolysis, this study determined that the bimolecular rate constants of scavenging cation radicals of retinoids by taurine are smaller than 2 × 107 M-1s-1 whereas lutein scavenges cation radicals of all three retinoids with the bimolecular rate constants approach the diffusion-controlled limits, while zeaxanthin is only 1.4-1.6-fold less effective. Despite that lutein exhibits greater scavenging rate constants of retinoid cation radicals than other antioxidants, the greater concentrations of ascorbate in the retina suggest that ascorbate may be the main protectant of all visual cycle retinoids from oxidative degradation, while α-tocopherol may play a substantial role in the protection of retinaldehyde but is relatively inefficient in the protection of retinol or retinyl palmitate. While the protection of retinoids by lutein and zeaxanthin appears inefficient in the retinal periphery, it can be quite substantial in the macula. Although the determined rate constants of scavenging the cation radicals of retinol and retinaldehyde by dopa-melanin are relatively small, the high concentration of melanin in the RPE melanosomes suggests they can be scavenged if they are in proximity to melanin-containing pigment granules.
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Affiliation(s)
- Malgorzata Rozanowska
- Cardiff Institute of Tissue Engineering and Repair, Cardiff University, Cardiff CF10 3AX, UK
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Ruth Edge
- Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row, Cumbria CA24 3HA, UK;
| | - Edward J. Land
- The Paterson Institute, The University of Manchester, Wilmslow Road, Manchester M20 4BX, UK;
| | - Suppiah Navaratnam
- Biomedical Sciences Research Institute, University of Salford, Manchester M5 4WT, UK;
| | - Tadeusz Sarna
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland;
| | - T. George Truscott
- School of Chemical and Physical Sciences, Lennard-Jones Building, Keele University, Staffordshire ST5 5BG, UK;
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