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Karigane D, Haraguchi M, Toyama-Sorimachi N, Nishimura EK, Takubo K. Mitf is required for T cell maturation by regulating dendritic cell homing to the thymus. Biochem Biophys Res Commun 2022; 596:29-35. [PMID: 35108651 DOI: 10.1016/j.bbrc.2022.01.091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 11/24/2022]
Abstract
Thymic dendritic cells (DCs) promote immune tolerance by regulating negative selection of autoreactive T cells in the thymus. How DC homing to the thymus is transcriptionally regulated is still unclear. Microphthalmia-associated transcription factor (Mitf) is broadly expressed and plays essential roles in the hematopoietic system. Here, we used Mitf-mutated mice (Mitfvit/vit) and found enlargement of the thymus and expansion of CD4/CD8 double-positive T cells. Mitf was highly expressed in a subset of thymic DCs among the hematopoietic system. Genetic mutation or pharmacological inhibition of Mitf in DCs decreased the expression levels of Itga4, which are critical molecules for the homing of DCs to the thymus. Further, inhibition of Mitf decreased thymic DC number. These results suggest a pivotal role of Mitf in the maintenance of T cell differentiation by regulating the homing of DC subsets within the thymus.
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Affiliation(s)
- Daiki Karigane
- Department of Stem Cell Biology, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan; Research Fellow of Japan Society for the Promotion of Science, Japan.
| | - Miho Haraguchi
- Department of Stem Cell Biology, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Noriko Toyama-Sorimachi
- Department of Molecular Immunology and Inflammation, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Emi K Nishimura
- Department of Stem Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan; Division of Aging and Regeneration, Institute of Medical Science, the University of Tokyo, Tokyo, Japan
| | - Keiyo Takubo
- Department of Stem Cell Biology, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
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Ma X, Li H, Chen Y, Yang J, Chen H, Arnheiter H, Hou L. The transcription factor MITF in RPE function and dysfunction. Prog Retin Eye Res 2019; 73:100766. [DOI: 10.1016/j.preteyeres.2019.06.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 06/17/2019] [Accepted: 06/21/2019] [Indexed: 12/18/2022]
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Wolkow N, Li Y, Maminishkis A, Song Y, Alekseev O, Iacovelli J, Song D, Lee JC, Dunaief JL. Iron upregulates melanogenesis in cultured retinal pigment epithelial cells. Exp Eye Res 2014; 128:92-101. [PMID: 25277027 DOI: 10.1016/j.exer.2014.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 09/12/2014] [Accepted: 09/26/2014] [Indexed: 12/20/2022]
Abstract
The purpose of our studies was to examine the relationship between iron and melanogenesis in retinal pigment epithelial cells, as prior observations had suggested that iron may promote melanogenesis. This relationship has potential clinical importance, as both iron overload and hyperpigmentation are associated with age-related macular degeneration (AMD). Human fetal retinal pigment epithelial cells and ARPE-19 cells were treated with iron in the form of ferric ammonium citrate, after which quantitative RT-PCR and electron microscopy were performed. Melanogenesis genes tyrosinase, tyrosinase-related protein 1, Hermansky-Pudlak Syndrome 3, premelanosome protein and dopachrome tautomerase were upregulated, as was the melanogenesis-controlling transcription factor, microphthalmia-associated transcription factor (MITF). Iron-treated cells had increased pigmentation and melanosome number. Multiple transcription factors upstream of MITF were upregulated by iron.
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Affiliation(s)
- Natalie Wolkow
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Yafeng Li
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Arvydas Maminishkis
- Section of Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bldg. 10, Rm. 10B04, MSC 1861, 10 Center Drive, Bethesda, MD 20892, USA
| | - Ying Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Oleg Alekseev
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Jared Iacovelli
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Delu Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Jennifer C Lee
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratories, 422 Curie Blvd, Philadelphia, PA 19104, USA.
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Reinisalo M, Putula J, Mannermaa E, Urtti A, Honkakoski P. Regulation of the human tyrosinase gene in retinal pigment epithelium cells: the significance of transcription factor orthodenticle homeobox 2 and its polymorphic binding site. Mol Vis 2012; 18:38-54. [PMID: 22259223 PMCID: PMC3258524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 01/05/2012] [Indexed: 12/02/2022] Open
Abstract
PURPOSE Tyrosinase is the rate-limiting enzyme responsible for melanin biosynthesis in the retinal pigment epithelium (RPE) of the eye. Melanin has an important role in retinal development, function, and protection against light-induced oxidative stress, and melanin levels are associated with age-related macular degeneration (AMD). Because the levels of and protection afforded by melanin seem to decline with increasing age, proper regulation of the human tyrosinase gene (TYR) in the RPE is an important but insufficiently understood process. Our purpose was to obtain detailed information on regulation of the TYR gene promoter in the human RPE and to specify the role of orthodenticle homeobox 2 (OTX2) and microphthalmia-associated transcription factor (MITF). METHODS We used luciferase reporter constructs to study regulation of the human TYR gene promoter in cultured human RPE cells. We further studied the role of OTX2 and MITF, their binding sites, and endogenous expression by using mutagenesis, electrophoretic mobility shift assay, yeast two-hybrid assay, RNA interference, and gene expression analyses. RESULTS In the RPE, OTX2 activated the human TYR gene promoter via direct trans-activation of novel OTX2 binding elements. In addition, we found that indirect activation by OTX2 via more proximal MITF binding sites, even in the absence of OTX2 sites, took place. These results are consistent with the physical interaction observed between OTX2 and MITF. Overexpression or knockdown of OTX2 in RPE cells resulted in corresponding changes in tyrosinase mRNA expression. Finally, we found that a single nucleotide polymorphism (SNP rs4547091) at the most proximal OTX2 binding site is associated with altered nuclear protein binding and a remarkable decrease in TYR promoter activity in RPE cells. This single nucleotide polymorphism (SNP) is more common in the European population in which AMD is also more prevalent. CONCLUSIONS In the RPE, OTX2 activates the human TYR gene promoter by direct DNA binding and by interaction with MITF. Such synergistic interaction highlights the role of OTX2 as a potential coregulator of numerous MITF target genes in the eye. Genetic differences in OTX2 binding sites affect tyrosinase regulation. Collectively, these findings emphasize the role of OTX2 in regulating the human TYR gene, with implications for inter-individual differences in melanin synthesis, retinal development, and function as well as susceptibility to retinal degeneration associated with aging.
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Affiliation(s)
- Mika Reinisalo
- School of Pharmacy and Biocenter Kuopio, University of Eastern Finland, Finland
| | - Jaana Putula
- School of Pharmacy and Biocenter Kuopio, University of Eastern Finland, Finland
| | - Eliisa Mannermaa
- School of Pharmacy and Biocenter Kuopio, University of Eastern Finland, Finland
| | - Arto Urtti
- Centre for Drug Research, University of Helsinki, Finland
| | - Paavo Honkakoski
- School of Pharmacy and Biocenter Kuopio, University of Eastern Finland, Finland
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Hoek KS, Schlegel NC, Eichhoff OM, Widmer DS, Praetorius C, Einarsson SO, Valgeirsdottir S, Bergsteinsdottir K, Schepsky A, Dummer R, Steingrimsson E. Novel MITF targets identified using a two-step DNA microarray strategy. Pigment Cell Melanoma Res 2009; 21:665-76. [PMID: 19067971 DOI: 10.1111/j.1755-148x.2008.00505.x] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Malignant melanoma is a chemotherapy-resistant cancer with high mortality. Recent advances in our understanding of the disease at the molecular level have indicated that it shares many characteristics with developmental precursors to melanocytes, the mature pigment-producing cells of the skin and hair follicles. The development of melanocytes absolutely depends on the action of the microphthalmia-associated transcription factor (MITF). MITF has been shown to regulate a broad variety of genes, whose functions range from pigment production to cell-cycle regulation, migration and survival. However, the existing list of targets is not sufficient to explain the role of MITF in melanocyte development and melanoma progression. DNA microarray analysis of gene expression offers a straightforward approach to identify new target genes, but standard analytical procedures are susceptible to the generation of false positives and require additional experimental steps for validation. Here, we introduce a new strategy where two DNA microarray-based approaches for identifying transcription factor targets are combined in a cross-validation protocol designed to help control false-positive generation. We use this two-step approach to successfully re-identify thirteen previously recorded targets of MITF-mediated upregulation, as well as 71 novel targets. Many of these new targets have known relevance to pigmentation and melanoma biology, and further emphasize the critical role of MITF in these processes.
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Affiliation(s)
- Keith S Hoek
- Department of Dermatology, University Hospital of Zürich, Zürich, Switzerland.
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