High Glucose Impairs Expression and Activation of MerTK in ARPE-19 Cells
MerTK (Mer Tyrosine Kinase) is a cell surface receptor that regulates phagocytosis of photoreceptor outer segments (POS) in retinal pigment epithelial (RPE) cells. POS phagocytosis is impaired in several pathologies, including diabetes. In this study, we investigate whether hyperglycemic conditions...
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MDPI AG
2022-01-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/23/3/1144 |
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| author | Alessandra Puddu Silvia Ravera Isabella Panfoli Nadia Bertola Davide Maggi |
| author_facet | Alessandra Puddu Silvia Ravera Isabella Panfoli Nadia Bertola Davide Maggi |
| author_sort | Alessandra Puddu |
| collection | DOAJ |
| description | MerTK (Mer Tyrosine Kinase) is a cell surface receptor that regulates phagocytosis of photoreceptor outer segments (POS) in retinal pigment epithelial (RPE) cells. POS phagocytosis is impaired in several pathologies, including diabetes. In this study, we investigate whether hyperglycemic conditions may affect MerTK expression and activation in ARPE-19 cells, a retinal pigment epithelial cellular model. ARPE-19 cells were cultured in standard (CTR) or high-glucose (HG) medium for 24 h. Then, we analyzed: mRNA levels and protein expression of MerTK and ADAM9, a protease that cleaves the extracellular region of MerTK; the amount of cleaved Mer (sMer); and the ability of GAS6, a MerTK ligand, to induce MerTK phosphorylation. Since HG reduces miR-126 levels, and ADAM9 is a target of miR-126, ARPE-19 cells were transfected with miR-126 inhibitor or mimic; then, we evaluated ADAM9 expression, sMer, and POS phagocytosis. We found that HG reduced expression and activation of MerTK. Contextually, HG increased expression of ADAM9 and the amount of sMer. Overexpression of miR-126 reduced levels of sMer and improved phagocytosis in ARPE-19 cells cultured with HG. In this study, we demonstrate that HG compromises MerTK expression and activation in ARPE-19 cells. Our results suggest that HG up-regulates ADAM9 expression, leading to increased shedding of MerTK. The consequent rise in sMer coupled to reduced expression of MerTK impairs binding and internalization of POS in ARPE-19 cells. |
| first_indexed | 2024-03-09T23:50:25Z |
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| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-09T23:50:25Z |
| publishDate | 2022-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | International Journal of Molecular Sciences |
| spelling | doaj.art-3040106d0a0d4077ab59bba4eb44f9b02023-11-23T16:35:42ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-01-01233114410.3390/ijms23031144High Glucose Impairs Expression and Activation of MerTK in ARPE-19 CellsAlessandra Puddu0Silvia Ravera1Isabella Panfoli2Nadia Bertola3Davide Maggi4Department of Internal Medicine and Medical Specialties, University of Genova, 16132 Genova, ItalyDipartimento di Medicina Sperimentale, Università di Genoa, Via De Toni 14, 16132 Genova, ItalyDipartimento di Farmacia (DIFAR), Università di Genova, V.le Benedetto XV 3, 16132 Genova, ItalyDipartimento di Medicina Sperimentale, Università di Genoa, Via De Toni 14, 16132 Genova, ItalyDepartment of Internal Medicine and Medical Specialties, University of Genova, 16132 Genova, ItalyMerTK (Mer Tyrosine Kinase) is a cell surface receptor that regulates phagocytosis of photoreceptor outer segments (POS) in retinal pigment epithelial (RPE) cells. POS phagocytosis is impaired in several pathologies, including diabetes. In this study, we investigate whether hyperglycemic conditions may affect MerTK expression and activation in ARPE-19 cells, a retinal pigment epithelial cellular model. ARPE-19 cells were cultured in standard (CTR) or high-glucose (HG) medium for 24 h. Then, we analyzed: mRNA levels and protein expression of MerTK and ADAM9, a protease that cleaves the extracellular region of MerTK; the amount of cleaved Mer (sMer); and the ability of GAS6, a MerTK ligand, to induce MerTK phosphorylation. Since HG reduces miR-126 levels, and ADAM9 is a target of miR-126, ARPE-19 cells were transfected with miR-126 inhibitor or mimic; then, we evaluated ADAM9 expression, sMer, and POS phagocytosis. We found that HG reduced expression and activation of MerTK. Contextually, HG increased expression of ADAM9 and the amount of sMer. Overexpression of miR-126 reduced levels of sMer and improved phagocytosis in ARPE-19 cells cultured with HG. In this study, we demonstrate that HG compromises MerTK expression and activation in ARPE-19 cells. Our results suggest that HG up-regulates ADAM9 expression, leading to increased shedding of MerTK. The consequent rise in sMer coupled to reduced expression of MerTK impairs binding and internalization of POS in ARPE-19 cells.https://www.mdpi.com/1422-0067/23/3/1144MerTKARPE-19 cellsdiabetesADAM9miR-126phagocytosis |
| spellingShingle | Alessandra Puddu Silvia Ravera Isabella Panfoli Nadia Bertola Davide Maggi High Glucose Impairs Expression and Activation of MerTK in ARPE-19 Cells International Journal of Molecular Sciences MerTK ARPE-19 cells diabetes ADAM9 miR-126 phagocytosis |
| title | High Glucose Impairs Expression and Activation of MerTK in ARPE-19 Cells |
| title_full | High Glucose Impairs Expression and Activation of MerTK in ARPE-19 Cells |
| title_fullStr | High Glucose Impairs Expression and Activation of MerTK in ARPE-19 Cells |
| title_full_unstemmed | High Glucose Impairs Expression and Activation of MerTK in ARPE-19 Cells |
| title_short | High Glucose Impairs Expression and Activation of MerTK in ARPE-19 Cells |
| title_sort | high glucose impairs expression and activation of mertk in arpe 19 cells |
| topic | MerTK ARPE-19 cells diabetes ADAM9 miR-126 phagocytosis |
| url | https://www.mdpi.com/1422-0067/23/3/1144 |
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