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Hung WC, Cheng HC, Wang AG. Melanoma-associated retinopathy with anti-TRPM1 autoantibodies showing concomitant Off-bipolar cell dysfunction. Doc Ophthalmol 2022; 145:263-270. [PMID: 36173494 DOI: 10.1007/s10633-022-09901-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/20/2022] [Indexed: 12/29/2022]
Abstract
BACKGROUND To report the clinical features of a patient with melanoma-associated retinopathy (MAR) with anti-transient receptor potential cation channel, subfamily M, member 1 (TRPM1) autoantibodies showing concomitant Off-bipolar cell dysfunction. METHODS We evaluated a patient with a past history of scalp melanoma presented with sudden-onset shimmering photopsia in both eyes. MAR was confirmed with complete ophthalmic examinations, electronegative electroretinogram (ERG), and the presence of anti-TRPM1 autoantibodies by Western blot analysis. S-cone ERG and photopic On-Off ERG were studied in this patient as well. RESULTS The patient's best-corrected visual acuity was 6/30 in the right eye and 6/8.6 in the left eye. Fundus and OCT findings were unremarkable. Visual field test showed severe constriction in both eyes. His full-field ERG was electronegative. S-cone ERG recorded preservation of L/M-cone-mediated response and undetectable S-cone-mediated response. Photopic On-Off ERG disclosed attenuated On- and Off-response. Western blot analysis confirmed immunoreactivity of the patient's serum to a 30 kDa TRPM1 recombinant protein. Whole-body positron emission tomography scan detected lymph node metastases in the neck. CONCLUSIONS Anti-TRPM1 autoantibody-positive MAR varies greatly in its presentation and clinical course. We present a case of anti-TRPM1 autoantibody-positive MAR with atypical feature of Off-bipolar cell involvement. A complete electroretinographic study together with identification of the pathogenic antiretinal autoantibodies may help better understand and subclassify the disease in the future.
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Affiliation(s)
- Wei-Che Hung
- Department of Ophthalmology, Taipei Veterans General Hospital, 201 Sec. 2, Shih-Pai Rd., Taipei, 11217, Taiwan
| | - Hui-Chen Cheng
- Department of Ophthalmology, Taipei Veterans General Hospital, 201 Sec. 2, Shih-Pai Rd., Taipei, 11217, Taiwan.,Department of Ophthalmology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Program in Molecular Medicine, College of Life Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Department of Life Sciences and Institute of Genome Sciences, College of Life Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan.,Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - An-Guor Wang
- Department of Ophthalmology, Taipei Veterans General Hospital, 201 Sec. 2, Shih-Pai Rd., Taipei, 11217, Taiwan. .,Department of Ophthalmology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan.
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2
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Gyoten D, Ueno S, Okado S, Chaya T, Yasuda S, Morimoto T, Kondo M, Kimura K, Hayashi T, Leroy BP, Woo SJ, Mukai R, Joo K, Furukawa T. Broad locations of antigenic regions for anti-TRPM1 autoantibodies in paraneoplastic retinopathy with retinal ON bipolar cell dysfunction. Exp Eye Res 2021; 212:108770. [PMID: 34562437 DOI: 10.1016/j.exer.2021.108770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 08/06/2021] [Accepted: 09/13/2021] [Indexed: 11/24/2022]
Abstract
PURPOSE Cancer-associated retinal ON bipolar cell dysfunction (CARBD), which includes melanoma-associated retinopathy (MAR), has been reported to be caused by autoantibodies against the molecules expressed in ON bipolar cells, including TRPM1. The purpose of this study was to determine the antigenic regions of the autoantibodies against TRPM1 in the sera of CARBD patients, in whom we previously detected anti-TRPM1 autoantibodies. METHODS The antigenic regions against TRPM1 in the sera of eight CARBD patients were examined by Western blots using HEK293T cells transfected with the plasmids expressing FLAG-tagged TRPM1 fragments. The clinical course of these patients was also documented. RESULTS The clinical course differed among the patients. The electroretinograms (ERGs) and symptoms were improved in three patients, deteriorated in one patient, remained unchanged for a long time in one patient, and were not followable in three patients. Seven of the eight sera possessed multiple antigenic regions: two sera contained at least four antigen recognition regions, and three sera had at least three regions. The antigen regions were spread over the entire TRPM1 protein: five sera in the N-terminal intracellular domain, six sera in the transmembrane-containing region, and six sera in the C-terminal intracellular domain. No significant relationship was observed between the location of the antigen epitope and the patients' clinical course. CONCLUSIONS The antigenic regions of anti-TRPM1 autoantibodies in CARBD patients were present not only in the N-terminal intracellular domain, which was reported in an earlier report, but also in the transmembrane-containing region and in the C-terminal intracellular domain. In addition, the antigenic regions for TRPM1 were found to vary among the CARBD patients examined, and most of the sera had multiple antigenic regions.
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Affiliation(s)
- Daichi Gyoten
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Shinji Ueno
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Aichi, Japan.
| | - Satoshi Okado
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Aichi, Japan
| | - Taro Chaya
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Shunsuke Yasuda
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Aichi, Japan
| | - Takeshi Morimoto
- Department of Advanced Visual Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Mineo Kondo
- Department of Ophthalmology, Mie University Graduate School of Medicine, Mie, Japan
| | - Kazuhiro Kimura
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Takaaki Hayashi
- Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan
| | - Bart P Leroy
- Department of Ophthalmology, Ghent University Hospital, Ghent University, Ghent, Belgium; Department of Ophthalmology, Center for Medical Genetics, Ghent University Hospital, Ghent University, Ghent, Belgium; Division of Ophthalmology and CCMT, The Children's Hospital of Philadelphia, Philadelphia, USA
| | - Se Joon Woo
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea
| | - Ryo Mukai
- Department of Ophthalmology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Kwangsic Joo
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, South Korea
| | - Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
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Retinal Diseases that Can Masquerade as Neurological Causes of Vision Loss. Curr Neurol Neurosci Rep 2020; 20:51. [PMID: 32930896 DOI: 10.1007/s11910-020-01071-1] [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: 10/23/2022]
Abstract
PURPOSE OF REVIEW This review aims to discuss retinal diseases that may masquerade as neurological causes of vision loss and highlights modern ophthalmic ancillary testing that can help to establish these diagnoses. RECENT FINDINGS Retinal diseases with signs and symptoms overlapping with neurological causes of vision loss include central serous chorioretinopathy, retinal ischemia, acute macular neuroretinopathy, Acute zonal occult outer retinopathy (AZOOR) complex diseases, paraneoplastic retinopathy, retinal dystrophy, and toxic retinopathy. Diagnosis is facilitated by electrophysiologic studies and multimodal ophthalmic imaging including optical coherence tomography and fundus autofluorescence imaging. Looking into the future, translation of adaptive optics ophthalmoscopy into clinical practice may facilitate early detection of microscopic retinal abnormalities that characterize these conditions. With conventional methods of physical examination, diagnosis of retinal diseases that may masquerade as neurological causes of vision loss can be challenging. Current advance in multimodal ophthalmic imaging along with electrophysiologic studies enhances the provider's ability to make early diagnosis and monitor progression of these conditions.
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CLINICAL COURSE OF PARANEOPLASTIC RETINOPATHY WITH ANTI-TRPM1 AUTOANTIBODY IN JAPANESE COHORT. Retina 2020; 39:2410-2418. [PMID: 30260920 DOI: 10.1097/iae.0000000000002329] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE To report the clinical course of eyes with paraneoplastic retinopathy caused by an autoantibody against transient receptor potential cation channel, subfamily M, member 1 (TRPM1). METHODS Ten paraneoplastic retinopathy patients with retinal ON-bipolar cell dysfunction, including six melanoma-associated retinopathy, from eight institutions in Japan were evaluated for the presence of an anti-TRPM1 antibody. The results of ophthalmic examinations and the presence of anti-TRPM1 antibody were analyzed. RESULTS Five patients were positive for the anti-TRPM1 antibody. These patients had similar clinical findings in both eyes at the time of diagnosis; relatively preserved best-corrected visual acuity, absence of fundus and optical coherence tomography abnormalities, and specific abnormalities of the electroretinography (ERG); and negative-type ERGs with bright stimulus flashes. One patient whose retinal ON-bipolar cells remained dysfunctional for the entire testing period, although the anti-TRPM1 antibody had disappeared. On the other hand, the ERGs recovered in 2 cases within 2 years after the onset. One case progressed to additional impairment of the photoreceptors with deterioration of ERGs. One case died and the clinical course was unavailable. CONCLUSION Paraneoplastic retinopathy patients with retinal ON-bipolar cell dysfunction possess autoantibodies against TRPM1 at the onset of the disease process; however, the clinical course of these eyes can be different.
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Varin J, Reynolds MM, Bouzidi N, Tick S, Wohlschlegel J, Becquart O, Michiels C, Dereure O, Duvoisin RM, Morgans CW, Sahel JA, Samaran Q, Guillot B, Pulido JS, Audo I, Zeitz C. Identification and characterization of novel TRPM1 autoantibodies from serum of patients with melanoma-associated retinopathy. PLoS One 2020; 15:e0231750. [PMID: 32324760 PMCID: PMC7179873 DOI: 10.1371/journal.pone.0231750] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 03/31/2020] [Indexed: 12/15/2022] Open
Abstract
Melanoma-associated retinopathy (MAR) is a rare paraneoplastic retinal disorder usually occurring in the context of metastatic melanoma. Patients present with night blindness, photopsias and a constriction of the visual field. MAR is an auto-immune disorder characterized by the production of autoantibodies targeting retinal proteins, especially autoantibodies reacting to the cation channel TRPM1 produced in melanocytes and ON-bipolar cells. TRPM1 has at least three different isoforms which vary in the N-terminal region of the protein. In this study, we report the case of three new MAR patients presenting different anti-TRPM1 autoantibodies reacting to the three isoforms of TRPM1 with variable binding affinity. Two sera recognized all isoforms of TRPM1, while one recognized only the two longest isoforms upon immunolocalization studies on overexpressing cells. Similarly, the former two sera reacted with all TRPM1 isoforms on western blot, but an immunoprecipitation enrichment step was necessary to detect all isoforms with the latter serum. In contrast, all sera labelled ON-bipolar cells on Tprm1+/+ but not on Trpm1-/- mouse retina as shown by co-immunolocalization. This confirms that the MAR sera specifically detect TRPM1. Most likely, the anti-TRPM1 autoantibodies of different patients vary in affinity and concentration. In addition, the binding of autoantibodies to TRPM1 may be conformation-dependent, with epitopes being inaccessible in some constructs (truncated polypeptides versus full-length TRPM1) or applications (western blotting versus immunohistochemistry). Therefore, we propose that a combination of different methods should be used to test for the presence of anti-TRPM1 autoantibodies in the sera of MAR patients.
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Affiliation(s)
- Juliette Varin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Margaret M. Reynolds
- Department of Ophthalmology, Washington University, Saint Louis, MO, United States of America
| | - Nassima Bouzidi
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Sarah Tick
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France
| | | | - Ondine Becquart
- Department of Dermatology and INSERM U1058 “Pathogenesis and control of chronic infections”, University of Montpellier, Montpellier, France
| | | | - Olivier Dereure
- Department of Dermatology and INSERM U1058 “Pathogenesis and control of chronic infections”, University of Montpellier, Montpellier, France
| | - Robert M. Duvoisin
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, OR, United States of America
| | - Catherine W. Morgans
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, OR, United States of America
| | - José-Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France
- Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
- Académie des Sciences, Institut de France, Paris, France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Quentin Samaran
- Department of Dermatology and INSERM U1058 “Pathogenesis and control of chronic infections”, University of Montpellier, Montpellier, France
| | - Bernard Guillot
- Department of Dermatology and INSERM U1058 “Pathogenesis and control of chronic infections”, University of Montpellier, Montpellier, France
| | - José S. Pulido
- Department of Ophthalmology, Mayo Clinic, Rochester, MN, United States of America
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN, United States of America
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France
- Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Christina Zeitz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- * E-mail:
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Duvoisin RM, Ren G, Haley TL, Taylor MH, Morgans CW. TRPM1 Autoantibodies in Melanoma Patients Without Self-Reported Visual Symptoms. Invest Ophthalmol Vis Sci 2019; 60:2330-2335. [PMID: 31117125 PMCID: PMC6532695 DOI: 10.1167/iovs.19-26775] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/29/2019] [Indexed: 01/12/2023] Open
Abstract
Purpose Melanoma-associated retinopathy (MAR) is a paraneoplastic syndrome associated with cutaneous malignant melanoma (CMM). Visual symptoms include night blindness, photopsia, and reduced-contrast sensitivity. An abnormal ERG b-wave and the presence of anti-bipolar cell autoantibodies, including autoantibodies reacting with the ON-bipolar cell TRPM1 channel, help to confirm the diagnosis. The goal of this study was to determine if CMM patients without visual symptoms also express anti-TRPM1 autoantibodies. Methods Serum samples from 15 CMM patients were tested using three assays: immunofluorescent labeling of TRPM1-transfected HEK cells, immunofluorescent labeling of retinal sections from wild-type and TRPM1 knockout mice, and immunoblot detection of a bacterially produced recombinant TRPM1 peptide. Results Serum specimens from 5 of the 15 CMM patients without declared visual symptoms were positive for anti-TRPM1 autoantibodies in at least one of the three assays. One of 50 control sera from patients not known to have cancer was also weakly reactive with the TRPM1 peptide. Conclusions Autoantibodies against TRPM1 are present in CMM patient sera without self-reported visual symptoms. Most patients had advanced (stage III and IV) disease and were undergoing aggressive treatments, including immunotherapy. It is unknown if immunotherapy affects the expression of TRPM1 autoantibodies. The presence of TRPM1 autoantibodies may predispose patients for MAR.
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Affiliation(s)
- Robert M. Duvoisin
- Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States
| | - Gaoying Ren
- Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States
| | - Tammie L. Haley
- Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States
| | - Matthew H. Taylor
- Hematology and Oncology, Oregon Health and Science University, Portland, Oregon, United States
- Knight Cancer Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Catherine W. Morgans
- Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, United States
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Bentea G, Sculier C, Grigoriu B, Meert AP, Durieux V, Berghmans T, Sculier JP. Autoimmune paraneoplastic syndromes associated to lung cancer: A systematic review of the literature: Part 3: Neurological paraneoplastic syndromes, involving the central nervous system. Lung Cancer 2017; 106:83-92. [PMID: 28285700 DOI: 10.1016/j.lungcan.2017.01.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The development of new immune treatment in oncology and particularly for lung cancer may induce new complications, particularly activation or reactivation of auto-immune diseases. In this context, a systematic review on the auto-immune paraneoplastic syndromes that can complicate lung cancer appears useful. This article is the third of a series of five and deals mainly with neurological paraneoplastic syndromes involving the central nervous system.
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Affiliation(s)
- Georgiana Bentea
- Service des Soins Intensifs et Urgences Oncologiques & Thoracic Oncology, Institut Jules Bordet, Centre des Tumeurs de l'Université Libre de Bruxelles (ULB), Belgium
| | - Claudine Sculier
- Service des Soins Intensifs et Urgences Oncologiques & Thoracic Oncology, Institut Jules Bordet, Centre des Tumeurs de l'Université Libre de Bruxelles (ULB), Belgium
| | - Bogdan Grigoriu
- Service des Soins Intensifs et Urgences Oncologiques & Thoracic Oncology, Institut Jules Bordet, Centre des Tumeurs de l'Université Libre de Bruxelles (ULB), Belgium
| | - Anne-Pascale Meert
- Service des Soins Intensifs et Urgences Oncologiques & Thoracic Oncology, Institut Jules Bordet, Centre des Tumeurs de l'Université Libre de Bruxelles (ULB), Belgium; Laboratoire facultaire de Médecine factuelle (ULB), Belgium
| | - Valérie Durieux
- Bibliothèque des Sciences de la Santé, Université libre de Bruxelles (ULB), Belgium; Laboratoire facultaire de Médecine factuelle (ULB), Belgium
| | - Thierry Berghmans
- Service des Soins Intensifs et Urgences Oncologiques & Thoracic Oncology, Institut Jules Bordet, Centre des Tumeurs de l'Université Libre de Bruxelles (ULB), Belgium; Laboratoire facultaire de Médecine factuelle (ULB), Belgium
| | - Jean-Paul Sculier
- Service des Soins Intensifs et Urgences Oncologiques & Thoracic Oncology, Institut Jules Bordet, Centre des Tumeurs de l'Université Libre de Bruxelles (ULB), Belgium; Laboratoire facultaire de Médecine factuelle (ULB), Belgium.
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Reinach PS, Mergler S, Okada Y, Saika S. Ocular transient receptor potential channel function in health and disease. BMC Ophthalmol 2015; 15 Suppl 1:153. [PMID: 26818117 PMCID: PMC4895786 DOI: 10.1186/s12886-015-0135-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Transient receptor potential (TRP) channels sense and transduce environmental stimuli into Ca(2+) transients that in turn induce responses essential for cell function and adaptation. These non-selective channels with variable Ca(2+) selectivity are grouped into seven different subfamilies containing 28 subtypes based on differences in amino acid sequence homology. Many of these subtypes are expressed in the eye on both neuronal and non-neuronal cells where they affect a host of stress-induced regulatory responses essential for normal vision maintenance. This article reviews our current knowledge about the expression, function and regulation of TRPs in different eye tissues. We also describe how under certain conditions TRP activation can induce responses that are maladaptive to ocular function. Furthermore, the possibility of an association between TRP mutations and disease is considered. These findings contribute to evidence suggesting that drug targeting TRP channels may be of therapeutic benefit in a clinical setting. We point out issues that must be more extensively addressed before it will be possible to decide with certainty that this is a realistic endeavor. Another possible upshot of future studies is that disease process progression can be better evaluated by profiling changes in tissue specific functional TRP subtype activity as well as their gene and protein expression.
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Affiliation(s)
- Peter S Reinach
- Department of Ophthalmology and Optometry, Wenzhou Medical University, 270 Xuejuan Road, Wenzhou, Zhejiang, 325027, P. R. China.
| | - Stefan Mergler
- Department of Ophthalmology, Charité-University Medicine Berlin, Campus Virchow-Clinic, Augustenburger Platz 1, 13353, Berlin, Germany.
| | - Yuka Okada
- Department of Ophthalmology, Wakayama Medical University School of Medicine, Wakayama, Japan.
| | - Shizuya Saika
- Department of Ophthalmology, Wakayama Medical University School of Medicine, Wakayama, Japan.
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Schneider FM, Mohr F, Behrendt M, Oberwinkler J. Properties and functions of TRPM1 channels in the dendritic tips of retinal ON-bipolar cells. Eur J Cell Biol 2015; 94:420-7. [PMID: 26111660 DOI: 10.1016/j.ejcb.2015.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
An increase in light intensity induces a depolarization in retinal ON-bipolar cells via a reduced glutamate release from presynaptic photoreceptor cells. The underlying transduction cascade in the dendritic tips of ON-bipolar cells involves mGluR6 glutamate receptors signaling to TRPM1 proteins that are an indispensable part of the transduction channel. Several other proteins are recognized to participate in the transduction machinery. Deficiency in many of these leads to congenital stationary night blindness, because rod bipolar cells, a subgroup of ON-bipolar cells, constitute the main route for sensory information under scotopic conditions. Here, we review the current knowledge about TRPM1 ion channels and how their activity is regulated within the postsynaptic compartment of ON-bipolar cells. The functional properties of TRPM1 channels in the dendritic compartment are not well understood as they differ substantially from those of recombinant TRPM1 channels. Critical evaluation of possible explanations of these discrepancies indicates that some key components of this transduction pathway might still not be known. The continued exploration of this pathway will yield further clinically useful insights.
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Affiliation(s)
- Franziska M Schneider
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Deutschhausstr. 1-2, D-35037 Marburg, Germany
| | - Florian Mohr
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Deutschhausstr. 1-2, D-35037 Marburg, Germany
| | - Marc Behrendt
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Deutschhausstr. 1-2, D-35037 Marburg, Germany
| | - Johannes Oberwinkler
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Deutschhausstr. 1-2, D-35037 Marburg, Germany.
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Reinach PS, Chen W, Mergler S. Polymodal roles of transient receptor potential channels in the control of ocular function. EYE AND VISION 2015; 2:5. [PMID: 26605361 PMCID: PMC4655450 DOI: 10.1186/s40662-015-0016-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/15/2015] [Indexed: 12/05/2022]
Abstract
Maintenance of intracellular Ca2+ levels at orders of magnitude below those in the extracellular environment is a requisite for preserving cell viability. Membrane channels contribute to such control through modulating their time-dependent opening and closing behaviour. Such regulation requires Ca2+ to serve as a second messenger mediating receptor control of numerous life-sustaining responses. Transient receptor potential (TRP) channels signal transduce a wide variety of different sensory stimuli to induce responses modulating cellular function. These channels are non-selective cation channels with variable Ca2+ selectivity having extensive sequence homology. They constitute a superfamily made up of 28 different members that are subdivided into 7 different subfamilies based on differences in sequence homology. Some of these TRP channel isotypes are expressed in the eye and localized to both neuronal and non-neuronal cell membranes. Their activation generates intracellular Ca2+ transients and other downstream-linked signalling events that affect numerous responses required for visual function. As there is an association between changes in functional TRP expression in various ocular diseases, there are efforts underway to determine if these channels can be used as drug targets to reverse declines in ocular function. We review here our current knowledge about the expression, function and regulation of TRPs in different eye tissues in health and disease. Furthermore, some of the remaining hurdles are described to developing safe and efficacious TRP channel modulators for use in a clinical setting.
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Affiliation(s)
- Peter S Reinach
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325027 P.R. China
| | - Weiwei Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325027 P.R. China
| | - Stefan Mergler
- Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Klinik für Augenheilkunde, Augustenburger Platz 1, D-13353 Berlin, Germany
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