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Sachdeva R, Schlotterer A, Schumacher D, Matka C, Mathar I, Dietrich N, Medert R, Kriebs U, Lin J, Nawroth P, Birnbaumer L, Fleming T, Hammes HP, Freichel M. TRPC proteins contribute to development of diabetic retinopathy and regulate glyoxalase 1 activity and methylglyoxal accumulation. Mol Metab 2018; 9:156-167. [PMID: 29373286 PMCID: PMC5870093 DOI: 10.1016/j.molmet.2018.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 12/18/2017] [Accepted: 01/02/2018] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE Diabetic retinopathy (DR) is induced by an accumulation of reactive metabolites such as ROS, RNS, and RCS species, which were reported to modulate the activity of cation channels of the TRPC family. In this study, we use Trpc1/4/5/6-/- compound knockout mice to analyze the contribution of these TRPC proteins to diabetic retinopathy. METHODS We used Nanostring- and qPCR-based analysis to determine mRNA levels of TRPC channels in control and diabetic retinae and retinal cell types. Chronic hyperglycemia was induced by Streptozotocin (STZ) treatment. To assess the development of diabetic retinopathy, vasoregression, pericyte loss, and thickness of individual retinal layers were analyzed. Plasma and cellular methylglyoxal (MG) levels, as well as Glyoxalase 1 (GLO1) enzyme activity and protein expression, were measured in WT and Trpc1/4/5/6-/- cells or tissues. MG-evoked toxicity in cells of both genotypes was compared by MTT assay. RESULTS We find that Trpc1/4/5/6-/- mice are protected from hyperglycemia-evoked vasoregression determined by the formation of acellular capillaries and pericyte drop-out. In addition, Trpc1/4/5/6-/- mice are resistant to the STZ-induced reduction in retinal layer thickness. The RCS metabolite methylglyoxal, which represents a key mediator for the development of diabetic retinopathy, was significantly reduced in plasma and red blood cells (RBCs) of STZ-treated Trpc1/4/5/6-/- mice compared to controls. GLO1 is the major MG detoxifying enzyme, and its activity and protein expression were significantly elevated in Trpc1/4/5/6-deficient cells, which led to significantly increased resistance to MG toxicity. GLO1 activity was also increased in retinal extracts from Trpc1/4/5/6-/- mice. The TRPCs investigated here are expressed at different levels in endothelial and glial cells of the retina. CONCLUSION The protective phenotype in diabetic retinopathy observed in Trpc1/4/5/6-/- mice is suggestive of a predominant action of TRPCs in Müller cells and microglia because of their central position in the retention of a proper homoeostasis of the neurovascular unit.
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Affiliation(s)
- Robin Sachdeva
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Andrea Schlotterer
- Vth Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Dagmar Schumacher
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Christin Matka
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Ilka Mathar
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Nadine Dietrich
- Vth Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Rebekka Medert
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Ulrich Kriebs
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Jihong Lin
- Vth Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Peter Nawroth
- Department of Medicine I and Clinical Chemistry, University Hospital Heidelberg, Germany; German Center for Diabetes Research (DZD), Germany; Institute for Diabetes and Cancer IDC Helmholtz Center Munich, Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Dept. of Medicine I, Heidelberg University Hospital, Heidelberg, Germany
| | - Lutz Birnbaumer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, North Carolina, USA; Institute for Biomedical Research (BIOMED), School of Medical sciences, Catholic University of Argentina, Buenos Aires, Argentina
| | - Thomas Fleming
- Department of Medicine I and Clinical Chemistry, University Hospital Heidelberg, Germany; German Center for Diabetes Research (DZD), Germany
| | - Hans-Peter Hammes
- Vth Department of Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Marc Freichel
- Institute of Pharmacology, Heidelberg University, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
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Abstract
Diabetic retinopathy remains a relevant clinical problem. In parallel with diagnostic and therapeutic improvements, the role of glycaemia and reactive metabolites causing cell stress and biochemical abnormalities as treatment targets needs continuous re-evaluation. Furthermore, the basic mechanisms of physiological angiogenesis, remodelling and pruning give important clues about the origins of vasoregression during the very early stages of diabetic retinopathy and can be modelled in animals. This review summarises evidence supporting a role for the neurovascular unit-composed of neuronal, glial and vascular cells-as a responder to the biochemical changes imposed by reactive metabolites and high glucose. Normoglycaemic animal models developing retinal degeneration, provide valuable information about common pathways downstream of progressive neuronal damage that induce vasoregression, as in diabetic models. These models can serve to assess novel treatments addressing the entire neurovascular unit for the benefit of early diabetic retinopathy.
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Affiliation(s)
- Hans-Peter Hammes
- 5. Med. Department, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, D-68167, Mannheim, Germany.
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