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Garcia-Sanchez J, Lin D, Liu WW. Mechanosensitive ion channels in glaucoma pathophysiology. Vision Res 2024; 223:108473. [PMID: 39180975 PMCID: PMC11398070 DOI: 10.1016/j.visres.2024.108473] [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: 06/17/2024] [Revised: 08/05/2024] [Accepted: 08/07/2024] [Indexed: 08/27/2024]
Abstract
Force sensing is a fundamental ability that allows cells and organisms to interact with their physical environment. The eye is constantly subjected to mechanical forces such as blinking and eye movements. Furthermore, elevated intraocular pressure (IOP) can cause mechanical strain at the optic nerve head, resulting in retinal ganglion cell death (RGC) in glaucoma. How mechanical stimuli are sensed and affect cellular physiology in the eye is unclear. Recent studies have shown that mechanosensitive ion channels are expressed in many ocular tissues relevant to glaucoma and may influence IOP regulation and RGC survival. Furthermore, variants in mechanosensitive ion channel genes may be associated with risk for primary open angle glaucoma. These findings suggest that mechanosensitive channels may be important mechanosensors mediating cellular responses to pressure signals in the eye. In this review, we focus on mechanosensitive ion channels from three major channel families-PIEZO, two-pore potassium and transient receptor potential channels. We review the key properties of these channels, their effects on cell function and physiology, and discuss their possible roles in glaucoma pathophysiology.
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Affiliation(s)
- Julian Garcia-Sanchez
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Danting Lin
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Wendy W Liu
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA.
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2
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Long Y, Kozhemyakin M, Wu SM, Pang JJ. TRPV4 affects visual signals in photoreceptors and rod bipolar cells. Front Cell Neurosci 2024; 18:1404929. [PMID: 38903773 PMCID: PMC11188360 DOI: 10.3389/fncel.2024.1404929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 05/17/2024] [Indexed: 06/22/2024] Open
Abstract
Introduction Mechanical sensitive channels expressed in mammalian retinas are effectors of elevated pressure stresses, but it is unclear how their activation affects visual function in pressure-related retinal disorders. Methods This study investigated the role of the transient potential channel vanilloid TRPV4 in photoreceptors and rod bipolar cells (RBCs) with immunohistochemistry, confocal microscopy, electroretinography (ERG), and patch-clamp techniques. Results TRPV4 immunoreactivity (IR) was found in the outer segments of photoreceptors, dendrites and somas of PKCα-positive RBCs and other BCs, plexiform layers, and retinal ganglion cells (RGCs) in wild-type mice. TRPV4-IR was largely diminished in the retinas of homozygous TRPV4 transgenic mice. Genetically suppressing TRPV4 expression moderately but significantly enhanced the amplitude of ERG a- and b-waves evoked by scotopic and mesopic lights (0.55 to 200 Rh*rod-1 s-1) and photopic lights (105-106 Rh*rod-1 s-1) compared to wild-type mice in fully dark-adapted conditions. The implicit time evoked by dim lights (0.55 to 200 Rh*rod-1 s-1) was significantly decreased for b-waves and elongated for a-waves in the transgenic mice. ERG b-wave evoked by dim lights is primarily mediated by RBCs, and under voltage-clamp conditions, the latency of the light-evoked cation current in RBCs of the transgenic mice was significantly shorter compared to wild-type mice. About 10% of the transgenic mice had one eye undeveloped, and the percentage was significantly higher than in wild-type mice. Conclusions The data indicates that TRPV4 involves ocular development and is expressed and active in outer retinal neurons, and interventions of TRPV4 can variably affect visual signals in rods, cones, RBCs, and cone ON BCs.
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Affiliation(s)
| | | | | | - Ji-Jie Pang
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
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3
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Pang JJ. The Variety of Mechanosensitive Ion Channels in Retinal Neurons. Int J Mol Sci 2024; 25:4877. [PMID: 38732096 PMCID: PMC11084373 DOI: 10.3390/ijms25094877] [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: 02/27/2024] [Revised: 04/16/2024] [Accepted: 04/20/2024] [Indexed: 05/13/2024] Open
Abstract
Alterations in intraocular and external pressure critically involve the pathogenesis of glaucoma, traumatic retinal injury (TRI), and other retinal disorders, and retinal neurons have been reported to express multiple mechanical-sensitive channels (MSCs) in recent decades. However, the role of MSCs in visual functions and pressure-related retinal conditions has been unclear. This review will focus on the variety and functional significance of the MSCs permeable to K+, Na+, and Ca2+, primarily including the big potassium channel (BK); the two-pore domain potassium channels TRAAK and TREK; Piezo; the epithelial sodium channel (ENaC); and the transient receptor potential channels vanilloid TRPV1, TRPV2, and TRPV4 in retinal photoreceptors, bipolar cells, horizontal cells, amacrine cells, and ganglion cells. Most MSCs do not directly mediate visual signals in vertebrate retinas. On the other hand, some studies have shown that MSCs can open in physiological conditions and regulate the activities of retinal neurons. While these data reasonably predict the crossing of visual and mechanical signals, how retinal light pathways deal with endogenous and exogenous mechanical stimulation is uncertain.
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Affiliation(s)
- Ji-Jie Pang
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA
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Liu W, Zhang W, Wang C, Song J, Li K, Zhang X, Wu X, Guo H. TRPV4 antagonist suppresses retinal ganglion cell apoptosis by regulating the activation of CaMKII and TNF-α expression in a chronic ocular hypertension rat model. Int Immunopharmacol 2024; 130:111811. [PMID: 38457929 DOI: 10.1016/j.intimp.2024.111811] [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: 01/13/2024] [Revised: 02/24/2024] [Accepted: 03/04/2024] [Indexed: 03/10/2024]
Abstract
Glaucoma is characterized by a progressive loss of retinal ganglion cells (RGCs), leading to irreversible visual function impairment. Sustained increase in intraocular pressure represents a major risk factor for glaucoma, yet the underlying mechanisms of RGC apoptosis induced by intraocular pressure remains unclear. This study aims to investigate the role of TRPV4 in RGC apoptosis in a rat model of chronic ocular hypertension (COH) and the underlying molecular mechanism. In the COH rat models, we evaluated the visual function, retinal pathological changes and RGC apoptosis. TRPV4 expression and downstream signaling molecules were also detected. We found that RGC density decreased and RGC apoptosis was induced in COH eyes compared with control eyes. TRPV4 expression increased significantly in response to elevated IOP. TRPV4 inhibition by the TRPV4 antagonist HC-067047 (HC-067) suppressed RGC apoptosis and protected visual function. HC-067 treatment upregulated the phosphorylation of CaMKII in both control and COH eyes. Finally, HC-067 treatment suppressed the production of TNF-α induced by ocular hypertension. The TRPV4 antagonist HC-067 might suppress RGC apoptosis by regulating the activation of CaMKII and inhibiting the production of TNF-α in the COH model. This indicated that TRPV4 antagonists may be a potential and novel therapeutic strategy for glaucoma.
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Affiliation(s)
- Wenhui Liu
- Department of Ophthalmology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Wenzhe Zhang
- Department of Ophthalmology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Chen Wang
- Department of Ophthalmology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Jiarun Song
- Department of Ophthalmology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Kaiyue Li
- Department of Nuclear Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Xia Zhang
- First Clinical Medical College, Shandong University of Traditional Chinese Medicine, Jinan 250014, China
| | - Xinyi Wu
- Department of Ophthalmology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China.
| | - Hui Guo
- Department of Ophthalmology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China.
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Zhang X, Wang F, Su Y. TRPV: An emerging target in glaucoma and optic nerve damage. Exp Eye Res 2024; 239:109784. [PMID: 38199261 DOI: 10.1016/j.exer.2024.109784] [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: 08/23/2023] [Revised: 11/30/2023] [Accepted: 01/06/2024] [Indexed: 01/12/2024]
Abstract
Transient receptor potential vanilloid (TRPV) channels are members of the TRP channel superfamily, which are ion channels that sense mechanical and osmotic stimuli and participate in Ca2+ signalling across the cell membrane. TRPV channels play important roles in maintaining the normal functions of an organism, and defects or abnormalities in TRPV channel function cause a range of diseases, including cardiovascular, neurological and urological disorders. Glaucoma is a group of chronic progressive optic nerve diseases with pathological changes that can occur in the tissues of the anterior and posterior segments of the eye, including the ciliary body, trabecular meshwork, Schlemm's canal, and retina. TRPV channels are expressed in these tissues and play various roles in glaucoma. In this article, we review various aspects of the pathogenesis of glaucoma, the structure and function of TRPV channels, the relationship between TRPV channels and systemic diseases, and the relationship between TRPV channels and ocular diseases, especially glaucoma, and we suggest future research directions. This information will help to further our understanding of TRPV channels and provide new ideas and targets for the treatment of glaucoma and optic nerve damage.
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Affiliation(s)
- Xiaotong Zhang
- Department of Ophthalmology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Feng Wang
- Department of Ophthalmology, The Fourth Affiliated Hospital, Harbin Medical University, Harbin, China.
| | - Ying Su
- Eye Hospital, The First Affiliated Hospital, Harbin Medical University, Harbin, China.
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6
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Tempone MH, Borges-Martins VP, César F, Alexandrino-Mattos DP, de Figueiredo CS, Raony Í, dos Santos AA, Duarte-Silva AT, Dias MS, Freitas HR, de Araújo EG, Ribeiro-Resende VT, Cossenza M, P. Silva H, P. de Carvalho R, Ventura ALM, Calaza KC, Silveira MS, Kubrusly RCC, de Melo Reis RA. The Healthy and Diseased Retina Seen through Neuron-Glia Interactions. Int J Mol Sci 2024; 25:1120. [PMID: 38256192 PMCID: PMC10817105 DOI: 10.3390/ijms25021120] [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: 12/21/2023] [Revised: 01/10/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
The retina is the sensory tissue responsible for the first stages of visual processing, with a conserved anatomy and functional architecture among vertebrates. To date, retinal eye diseases, such as diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa, glaucoma, and others, affect nearly 170 million people worldwide, resulting in vision loss and blindness. To tackle retinal disorders, the developing retina has been explored as a versatile model to study intercellular signaling, as it presents a broad neurochemical repertoire that has been approached in the last decades in terms of signaling and diseases. Retina, dissociated and arranged as typical cultures, as mixed or neuron- and glia-enriched, and/or organized as neurospheres and/or as organoids, are valuable to understand both neuronal and glial compartments, which have contributed to revealing roles and mechanisms between transmitter systems as well as antioxidants, trophic factors, and extracellular matrix proteins. Overall, contributions in understanding neurogenesis, tissue development, differentiation, connectivity, plasticity, and cell death are widely described. A complete access to the genome of several vertebrates, as well as the recent transcriptome at the single cell level at different stages of development, also anticipates future advances in providing cues to target blinding diseases or retinal dysfunctions.
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Affiliation(s)
- Matheus H. Tempone
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
| | - Vladimir P. Borges-Martins
- Department of Physiology and Pharmacology, Biomedical Institute and Program of Neurosciences, Federal Fluminense University, Niterói 24020-150, Brazil; (V.P.B.-M.); (A.A.d.S.); (M.C.); (R.C.C.K.)
| | - Felipe César
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
| | - Dio Pablo Alexandrino-Mattos
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
| | - Camila S. de Figueiredo
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Ícaro Raony
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (Í.R.); (H.R.F.)
| | - Aline Araujo dos Santos
- Department of Physiology and Pharmacology, Biomedical Institute and Program of Neurosciences, Federal Fluminense University, Niterói 24020-150, Brazil; (V.P.B.-M.); (A.A.d.S.); (M.C.); (R.C.C.K.)
| | - Aline Teixeira Duarte-Silva
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Mariana Santana Dias
- Laboratory of Gene Therapy and Viral Vectors, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.S.D.); (H.P.S.)
| | - Hércules Rezende Freitas
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (Í.R.); (H.R.F.)
| | - Elisabeth G. de Araújo
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
- National Institute of Science and Technology on Neuroimmunomodulation—INCT-NIM, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro 21040-360, Brazil
| | - Victor Tulio Ribeiro-Resende
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
| | - Marcelo Cossenza
- Department of Physiology and Pharmacology, Biomedical Institute and Program of Neurosciences, Federal Fluminense University, Niterói 24020-150, Brazil; (V.P.B.-M.); (A.A.d.S.); (M.C.); (R.C.C.K.)
| | - Hilda P. Silva
- Laboratory of Gene Therapy and Viral Vectors, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.S.D.); (H.P.S.)
| | - Roberto P. de Carvalho
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Ana L. M. Ventura
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Karin C. Calaza
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Mariana S. Silveira
- Laboratory for Investigation in Neuroregeneration and Development, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil;
| | - Regina C. C. Kubrusly
- Department of Physiology and Pharmacology, Biomedical Institute and Program of Neurosciences, Federal Fluminense University, Niterói 24020-150, Brazil; (V.P.B.-M.); (A.A.d.S.); (M.C.); (R.C.C.K.)
| | - Ricardo A. de Melo Reis
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
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Spurlock M, An W, Reshetnikova G, Wen R, Wang H, Braha M, Solis G, Kurtenbach S, Galindez OJ, de Rivero Vaccari JP, Chou TH, Porciatti V, Shestopalov VI. The Inflammasome-Dependent Dysfunction and Death of Retinal Ganglion Cells after Repetitive Intraocular Pressure Spikes. Cells 2023; 12:2626. [PMID: 37998361 PMCID: PMC10670000 DOI: 10.3390/cells12222626] [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: 09/27/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/25/2023] Open
Abstract
The dysfunction and selective loss of retinal ganglion cells (RGCs) is a known cause of vision loss in glaucoma and other neuropathies, where ocular hypertension (OHT) is the major risk factor. We investigated the impact of transient non-ischemic OHT spikes (spOHT) on RGC function and viability in vivo to identify cellular pathways linking low-grade repetitive mechanical stress to RGC pathology. We found that repetitive spOHT had an unexpectedly high impact on intraocular homeostasis and RGC viability, while exposure to steady OHT (stOHT) of a similar intensity and duration failed to induce pathology. The repetitive spOHT induced the rapid activation of the inflammasome, marked by the upregulation of NLRP1, NLRP3, AIM2, caspases -1, -3/7, -8, and Gasdermin D (GSDMD), and the release of interleukin-1β (IL-1β) and other cytokines into the vitreous. Similar effects were also detected after 5 weeks of exposure to chronic OHT in an induced glaucoma model. The onset of these immune responses in both spOHT and glaucoma models preceded a 50% deficit in pattern electroretinogram (PERG) amplitude and a significant loss of RGCs 7 days post-injury. The inactivation of inflammasome complexes in Nlrp1-/-, Casp1-/-, and GsdmD-/- knockout animals significantly suppressed the spOHT-induced inflammatory response and protected RGCs. Our results demonstrate that mechanical stress produced by acute repetitive spOHT or chronic OHT is mechanistically linked to inflammasome activation, which leads to RGC dysfunction and death.
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Affiliation(s)
- Markus Spurlock
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA;
| | - Weijun An
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Galina Reshetnikova
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Rong Wen
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Hua Wang
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Michelle Braha
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Gabriela Solis
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Stefan Kurtenbach
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Orlando J. Galindez
- Department of Neurological Surgery and The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL 33136, USA;
| | - Juan Pablo de Rivero Vaccari
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA;
- Department of Neurological Surgery and The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL 33136, USA;
| | - Tsung-Han Chou
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Vittorio Porciatti
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
| | - Valery I. Shestopalov
- Bascom Palmer Eye Institute Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (M.S.); (W.A.); (G.R.); (R.W.); (H.W.); (M.B.); (G.S.); (S.K.); (V.P.)
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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Wang Y, Zhang W, Xu G, Shi C, Wang X, Qu J, Wang H, Liu C. The role of TRPV4 in the regulation of retinal ganglion cells apoptosis in rat and mouse. Heliyon 2023; 9:e17583. [PMID: 37456002 PMCID: PMC10338314 DOI: 10.1016/j.heliyon.2023.e17583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 06/18/2023] [Accepted: 06/21/2023] [Indexed: 07/18/2023] Open
Abstract
Retinal ganglion cell (RGC) damages are common in glaucoma, causing atrophy of the optic papilla, visual field damage, and visual loss. Transient receptor potential vanilloid 4 (TRPV4) is significantly expressed in the eyeball and is sensitive to mechanical and osmotic pressure. However, the specific role and mechanism of TRPV4 in glaucoma and RGC progression remain unclear. TRPV4 expression was detected in RGCs under different pressure culture conditions. We also explored the pressure effect on TRPV4 expression and the role and mechanism behind the functional regulation of RGCs. Immunofluorescence staining, western blotting, and TUNEL were utilized in this study. Our results established that TRPV4 was expressed in RGCs. TRPV4 expression was decreased at 40 mmHg and 60 mmHg, and the expression of BAX at 40 mmHg, 60 mmHg. Additionally, the expression of caspase 9 protein increased at 40 mmHg with the pressure increase compared with the conventional culture group. TUNEL staining revealed that the apoptosis rate of RGCs was elevated at 40 mmHg and 60 mmHg, compared with the traditional culture group. Therefore, the expression of BAX and caspase 9 increased, along with the apoptosis rate of RGCs compared with the control group. However, after TRPV4 antagonist treatment, the expression of BAX and caspase 9 decreased, and the apoptosis rate of RGCs decreased. Thus, TRPV4 may affect the mitochondrial apoptosis pathway, such as BAX and caspase 9, leading to the apoptosis of RGCs. The antagonists of TRPV4 could provide a new idea for clinically treating acute glaucoma.
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Affiliation(s)
- Yi Wang
- Department of Ophthalmology, The Second Affiliated Hospital of Shandong First Medical University, Taian, Shandong, 271000, China
| | - Wei Zhang
- School of Medicine, Southeast University, Nanjing, 210009, China
| | - Guozheng Xu
- Department of Physiology and Neurobiology, Functional Laboratory, Shandong First Medical University, Jinan, Shandong, 250117, China
| | - Changwei Shi
- Department of Physiology and Neurobiology, Functional Laboratory, Shandong First Medical University, Jinan, Shandong, 250117, China
| | - Xiang Wang
- School of Clinical Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, Shandong, 271016, China
| | - Jianfeng Qu
- Medical Engineering and Technology Research Center, Shandong First Medical University, Taian, Shandong, 271000, China
| | - Hongmei Wang
- School of Medicine, Southeast University, Nanjing, 210009, China
| | - Chunhua Liu
- Department of Physiology and Neurobiology, Functional Laboratory, Shandong First Medical University, Jinan, Shandong, 250117, China
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9
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O’Hare M, Esquiva G, McGahon MK, Hombrebueno JMR, Augustine J, Canning P, Edgar KS, Barabas P, Friedel T, Cincolà P, Henry J, Mayne K, Ferrin H, Stitt AW, Lyons TJ, Brazil DP, Grieve DJ, McGeown JG, Curtis TM. Loss of TRPV2-mediated blood flow autoregulation recapitulates diabetic retinopathy in rats. JCI Insight 2022; 7:e155128. [PMID: 36134661 PMCID: PMC9675469 DOI: 10.1172/jci.insight.155128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 08/10/2022] [Indexed: 11/17/2022] Open
Abstract
Loss of retinal blood flow autoregulation is an early feature of diabetes that precedes the development of clinically recognizable diabetic retinopathy (DR). Retinal blood flow autoregulation is mediated by the myogenic response of the retinal arterial vessels, a process that is initiated by the stretch‑dependent activation of TRPV2 channels on the retinal vascular smooth muscle cells (VSMCs). Here, we show that the impaired myogenic reaction of retinal arterioles from diabetic animals is associated with a complete loss of stretch‑dependent TRPV2 current activity on the retinal VSMCs. This effect could be attributed, in part, to TRPV2 channel downregulation, a phenomenon that was also evident in human retinal VSMCs from diabetic donors. We also demonstrate that TRPV2 heterozygous rats, a nondiabetic model of impaired myogenic reactivity and blood flow autoregulation in the retina, develop a range of microvascular, glial, and neuronal lesions resembling those observed in DR, including neovascular complexes. No overt kidney pathology was observed in these animals. Our data suggest that TRPV2 dysfunction underlies the loss of retinal blood flow autoregulation in diabetes and provide strong support for the hypothesis that autoregulatory deficits are involved in the pathogenesis of DR.
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Affiliation(s)
- Michael O’Hare
- Wellcome-Wolfson Institute for Experimental Medicine and
| | - Gema Esquiva
- Wellcome-Wolfson Institute for Experimental Medicine and
| | - Mary K. McGahon
- Wellcome-Wolfson Institute for Experimental Medicine and
- Centre for Biomedical Sciences Education, Queen’s University Belfast, Belfast, United Kingdom
| | | | - Josy Augustine
- Wellcome-Wolfson Institute for Experimental Medicine and
| | - Paul Canning
- Wellcome-Wolfson Institute for Experimental Medicine and
| | - Kevin S. Edgar
- Wellcome-Wolfson Institute for Experimental Medicine and
| | - Peter Barabas
- Wellcome-Wolfson Institute for Experimental Medicine and
| | - Thomas Friedel
- Wellcome-Wolfson Institute for Experimental Medicine and
| | | | - Jennifer Henry
- Wellcome-Wolfson Institute for Experimental Medicine and
- Centre for Biomedical Sciences Education, Queen’s University Belfast, Belfast, United Kingdom
| | - Katie Mayne
- Wellcome-Wolfson Institute for Experimental Medicine and
- Centre for Biomedical Sciences Education, Queen’s University Belfast, Belfast, United Kingdom
| | - Hannah Ferrin
- Wellcome-Wolfson Institute for Experimental Medicine and
- Centre for Biomedical Sciences Education, Queen’s University Belfast, Belfast, United Kingdom
| | - Alan W. Stitt
- Wellcome-Wolfson Institute for Experimental Medicine and
| | | | | | | | | | - Tim M. Curtis
- Wellcome-Wolfson Institute for Experimental Medicine and
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10
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Lapajne L, Rudzitis CN, Cullimore B, Ryskamp D, Lakk M, Redmon SN, Yarishkin O, Krizaj D. TRPV4: Cell type-specific activation, regulation and function in the vertebrate eye. CURRENT TOPICS IN MEMBRANES 2022; 89:189-219. [PMID: 36210149 PMCID: PMC9879314 DOI: 10.1016/bs.ctm.2022.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The architecture of the vertebrate eye is optimized for efficient delivery and transduction of photons and processing of signaling cascades downstream from phototransduction. The cornea, lens, retina, vasculature, ciliary body, ciliary muscle, iris and sclera have specialized functions in ocular protection, transparency, accommodation, fluid regulation, metabolism and inflammatory signaling, which are required to enable function of the retina-light sensitive tissue in the posterior eye that transmits visual signals to relay centers in the midbrain. This process can be profoundly impacted by non-visual stimuli such as mechanical (tension, compression, shear), thermal, nociceptive, immune and chemical stimuli, which target these eye regions to induce pain and precipitate vision loss in glaucoma, diabetic retinopathy, retinal dystrophies, retinal detachment, cataract, corneal dysfunction, ocular trauma and dry eye disease. TRPV4, a polymodal nonselective cation channel, integrate non-visual inputs with homeostatic and signaling functions of the eye. The TRPV4 gene is expressed in most if not all ocular tissues, which vary widely with respect to the mechanisms of TRPV4 channel activation, modulation, oligomerization, and participation in protein- and lipid interactions. Under- and overactivation of TRPV4 may affect intraocular pressure, maintenance of blood-retina barriers, lens accommodation, neuronal function and neuroinflammation. Because TRPV4 dysregulation precipitates many pathologies across the anterior and posterior eye, the channel could be targeted to mitigate vision loss.
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Affiliation(s)
- Luka Lapajne
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, United States; Department of Ophthalmology, University Medical Centre, University of Ljubljana, Ljubljana, Slovenia
| | - Christopher N Rudzitis
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, United States
| | - Brenan Cullimore
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, United States
| | - Daniel Ryskamp
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, United States
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, United States
| | - Sarah N Redmon
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, United States
| | - Oleg Yarishkin
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, United States
| | - David Krizaj
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, United States; Department of Neurobiology, University of Utah, Salt Lake City, UT, United States; Department of Bioengineering, University of Utah, Salt Lake City, UT, United States.
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11
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CB 1R, CB 2R and TRPV1 expression and modulation in in vivo, animal glaucoma models: A systematic review. Biomed Pharmacother 2022; 150:112981. [PMID: 35468582 DOI: 10.1016/j.biopha.2022.112981] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/06/2022] [Accepted: 04/14/2022] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The endocannabinoid system (ECS) is a complex biological regulatory system. Its expression and functionality have been widely investigated in ocular tissues. Recent data have reported its modulation to be valid in determining an ocular hypotensive and a neuroprotective effect in preclinical animal models of glaucoma. AIM This study aimed to explore the available literature on cannabinoid receptor 1 (CB1R), cannabinoid receptor 2 (CB2R), and transient receptor potential vanilloid 1 (TRPV1) expression in the trabecular meshwork (TM), ciliary body (CB), and retina as well as their ocular hypotensive and neuroprotective effects in preclinical, in vivo, animal glaucoma models. MATERIALS AND METHODS The study adhered to both PRISMA and SYRCLE guidelines. Sixty-nine full-length articles were included in the final analysis. RESULTS Preclinical studies indicated a widespread distribution of CB1R, CB2R, and TRPV1 in the TM, CB, and retina, although receptor-, age-, and species-dependent differences were observed. CB1R and CB2R modulation have been shown to exert ocular hypotensive effects in preclinical models via the regulation of inflow and outflow pathways. Retinal cell neuroprotection has been achieved in several experimental models, mediated by agonists and antagonists of CB1R, CB2R, and TRPV1. DISCUSSION Despite the growing body of preclinical data regarding the expression and modulation of ECS in ocular tissues, the mechanisms responsible for the hypotensive and neuroprotective efficacy exerted by this system remain largely elusive. Research on this topic is advocated to further substantiate the hypothesis that the ECS is a new potential therapeutic target in the context of glaucoma.
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12
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Sundberg CA, Lakk M, Paul S, Figueroa KP, Scoles DR, Pulst SM, Križaj D. The RNA-binding protein and stress granule component ATAXIN-2 is expressed in mouse and human tissues associated with glaucoma pathogenesis. J Comp Neurol 2022; 530:537-552. [PMID: 34350994 PMCID: PMC8716417 DOI: 10.1002/cne.25228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/06/2021] [Indexed: 02/03/2023]
Abstract
Polyglutamine repeat expansions in the Ataxin-2 (ATXN2) gene were first implicated in Spinocerebellar Ataxia Type 2, a disease associated with degeneration of motor neurons and Purkinje cells. Recent studies linked single nucleotide polymorphisms in the gene to elevated intraocular pressure in primary open angle glaucoma (POAG); yet, the localization of ATXN2 across glaucoma-relevant tissues of the vertebrate eye has not been thoroughly examined. This study characterizes ATXN2 expression in the mouse and human retina, and anterior eye, using an antibody validated in ATXN2-/- retinas. ATXN2-ir was localized to cytosolic sub compartments in retinal ganglion cell (RGC) somata and proximal dendrites in addition to GABAergic, glycinergic, and cholinergic amacrine cells in the inner plexiform layer (IPL) and displaced amacrine cells. Human, but not mouse retinas showed modest immunolabeling of bipolar cells. ATXN2 immunofluorescence was prominent in the trabecular meshwork and pigmented and nonpigmented cells of the ciliary body, with analyses of primary human trabecular meshwork cells confirming the finding. The expression of ATXN2 in key POAG-relevant ocular tissues supports the potential role in autophagy and stress granule formation in response to ocular hypertension.
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Affiliation(s)
- Chad A. Sundberg
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Sharan Paul
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Karla P. Figueroa
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Daniel R. Scoles
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Stefan M. Pulst
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
- Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, Utah, USA
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13
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Nisembaum LG, Loentgen G, L’Honoré T, Martin P, Paulin CH, Fuentès M, Escoubeyrou K, Delgado MJ, Besseau L, Falcón J. Transient Receptor Potential-Vanilloid (TRPV1-TRPV4) Channels in the Atlantic Salmon, Salmo salar. A Focus on the Pineal Gland and Melatonin Production. Front Physiol 2022; 12:784416. [PMID: 35069244 PMCID: PMC8782258 DOI: 10.3389/fphys.2021.784416] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
Fish are ectotherm, which rely on the external temperature to regulate their internal body temperature, although some may perform partial endothermy. Together with photoperiod, temperature oscillations, contribute to synchronizing the daily and seasonal variations of fish metabolism, physiology and behavior. Recent studies are shedding light on the mechanisms of temperature sensing and behavioral thermoregulation in fish. In particular, the role of some members of the transient receptor potential channels (TRP) is being gradually unraveled. The present study in the migratory Atlantic salmon, Salmo salar, aims at identifying the tissue distribution and abundance in mRNA corresponding to the TRP of the vanilloid subfamilies, TRPV1 and TRPV4, and at characterizing their putative role in the control of the temperature-dependent modulation of melatonin production-the time-keeping hormone-by the pineal gland. In Salmo salar, TRPV1 and TRPV4 mRNA tissue distribution appeared ubiquitous; mRNA abundance varied as a function of the month investigated. In situ hybridization and immunohistochemistry indicated specific labeling located in the photoreceptor cells of the pineal gland and the retina. Additionally, TRPV analogs modulated the production of melatonin by isolated pineal glands in culture. The TRPV1 agonist induced an inhibitory response at high concentrations, while evoking a bell-shaped response (stimulatory at low, and inhibitory at high, concentrations) when added with an antagonist. The TRPV4 agonist was stimulatory at the highest concentration used. Altogether, the present results agree with the known widespread distribution and role of TRPV1 and TRPV4 channels, and with published data on trout (Oncorhynchus mykiss), leading to suggest these channels mediate the effects of temperature on S. salar pineal melatonin production. We discuss their involvement in controlling the timing of daily and seasonal events in this migratory species, in the context of an increasing warming of water temperatures.
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Affiliation(s)
- Laura Gabriela Nisembaum
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Guillaume Loentgen
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Thibaut L’Honoré
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Patrick Martin
- Conservatoire National du Saumon Sauvage, Chanteuges, France
| | - Charles-Hubert Paulin
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Michael Fuentès
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Karine Escoubeyrou
- SU, CNRS Fédération 3724, Observatoire Océanologique, Banyuls-sur-Mer, France
| | - María Jesús Delgado
- Departamento de Genética, Fisiología y Microbiologia, Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain
| | - Laurence Besseau
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
| | - Jack Falcón
- Sorbonne Université (SU), CNRS, Biologie Intégrative des Organismes Marins (BIOM), Banyuls-sur-Mer, France
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14
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Thébault S. Minireview: Insights into the role of TRP channels in the retinal circulation and function. Neurosci Lett 2021; 765:136285. [PMID: 34634394 DOI: 10.1016/j.neulet.2021.136285] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 08/25/2021] [Accepted: 08/28/2021] [Indexed: 12/17/2022]
Abstract
Consistent with their wide distribution throughout the CNS, transcripts of all transient receptor potential (TRP) cation channel superfamily members have been detected in both neuronal and non-neuronal cells of the mammalian retina. Evidence shows that members of the TRPC (canonical, TRPC1/4/5/6), TRPV (vanilloid, TRPV1/2/4), TRPM (melastatin, TRPM1/2/3/5), TRPA (ankyrin, TRPA1), and TRPP (polycystin, TRPP2) subfamilies contribute to retinal function and circulation in health and disease, but the relevance of most TRPs has yet to be determined. Their principal role in light detection is far better understood than their participation in the control of intraocular pressure, retinal blood flow, oxidative stress, ion homeostasis, and transmitter signaling for retinal information processing. Moreover, if the therapeutic potential of targeting some TRPs to treat various retinal diseases remains speculative, recent studies highlight that vision restoration strategies are very likely to benefit from the thermo- and mechanosensitive properties of TRPs. This minireview focuses on the evidence of the past 5 years about the role of TRPs in the retina and retinal circulation, raises some possibilities about the function of TRPs in the retina, and discusses the potential sources of endogenous stimuli for TRPs in this tissue, as a reflection for future studies.
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Affiliation(s)
- Stéphanie Thébault
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Campus UNAM-Juriquilla, 76230 Querétaro, Mexico.
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15
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The Vertical and Horizontal Pathways in the Monkey Retina Are Modulated by Typical and Atypical Cannabinoid Receptors. Cells 2021; 10:cells10113160. [PMID: 34831383 PMCID: PMC8622302 DOI: 10.3390/cells10113160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 11/04/2021] [Accepted: 11/11/2021] [Indexed: 12/11/2022] Open
Abstract
The endocannabinoid (eCB) system has been found in all visual parts of the central ner-vous system and plays a role in the processing of visual information in many species, including monkeys and humans. Using anatomical methods, cannabinoid receptors are present in the monkey retina, particularly in the vertical glutamatergic pathway, and also in the horizontal GABAergic pathway. Modulating the eCB system regulates normal retinal function as demonstrated by electrophysiological recordings. The characterization of the expression patterns of all types of cannabinoid receptors in the retina is progressing, and further research is needed to elucidate their exact role in processing visual information. Typical cannabinoid receptors include G-protein coupled receptor CB1R and CB2R, and atypical cannabinoid receptors include the G-protein coupled receptor 55 (GPR55) and the ion channel transient receptor potential vanilloid 1 (TRPV1). This review focuses on the expression and localization studies carried out in monkeys, but some data on other animal species and humans will also be reported. Furthermore, the role of the endogenous cannabinoid receptors in retinal function will also be presented using intraocular injections of known modulators (agonists and antagonists) on electroretinographic patterns in monkeys. The effects of the natural bioactive lipid lysophosphatidylglucoside and synthetic FAAH inhibitor URB597 on retinal function, will also be described. Finally, the potential of typical and atypical cannabinoid receptor acti-vity regulation in retinal diseases, such as age-related macular degeneration, diabetic retinopathy, glaucoma, and retinitis pigmentosa will be briefly explored.
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16
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Lakk M, Hoffmann GF, Gorusupudi A, Enyong E, Lin A, Bernstein PS, Toft-Bertelsen T, MacAulay N, Elliott MH, Križaj D. Membrane cholesterol regulates TRPV4 function, cytoskeletal expression, and the cellular response to tension. J Lipid Res 2021; 62:100145. [PMID: 34710431 PMCID: PMC8633027 DOI: 10.1016/j.jlr.2021.100145] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 10/08/2021] [Accepted: 10/19/2021] [Indexed: 02/06/2023] Open
Abstract
Despite the association of cholesterol with debilitating pressure-related diseases such as glaucoma, heart disease, and diabetes, its role in mechanotransduction is not well understood. We investigated the relationship between mechanical strain, free membrane cholesterol, actin cytoskeleton, and the stretch-activated transient receptor potential vanilloid isoform 4 (TRPV4) channel in human trabecular meshwork (TM) cells. Physiological levels of cyclic stretch resulted in time-dependent decreases in membrane cholesterol/phosphatidylcholine ratio and upregulation of stress fibers. Depleting free membrane cholesterol with m-β-cyclodextrin (MβCD) augmented TRPV4 activation by the agonist GSK1016790A, swelling and strain, with the effects reversed by cholesterol supplementation. MβCD increased membrane expression of TRPV4, caveolin-1, and flotillin. TRPV4 did not colocalize or interact with caveolae or lipid rafts, apart from a truncated ∼75 kDa variant partially precipitated by a caveolin-1 antibody. MβCD induced currents in TRPV4-expressing Xenopus laevis oocytes. Thus, membrane cholesterol regulates trabecular transduction of mechanical information, with TRPV4 channels mainly located outside the cholesterol-enriched membrane domains. Moreover, the biomechanical milieu itself shapes the lipid content of TM membranes. Diet, cholesterol metabolism, and mechanical stress might modulate the conventional outflow pathway and intraocular pressure in glaucoma and diabetes in part by modulating TM mechanosensing.
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Affiliation(s)
- Monika Lakk
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Grace F Hoffmann
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Aruna Gorusupudi
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Eric Enyong
- Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Amy Lin
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Paul S Bernstein
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
| | | | - Nanna MacAulay
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Michael H Elliott
- Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA; Department of Bioengineering, University of Utah, Salt Lake City, UT, USA; Department of Neurobiology, University of Utah, Salt Lake City, UT, USA.
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17
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Gladkikh IN, Sintsova OV, Leychenko EV, Kozlov SA. TRPV1 Ion Channel: Structural Features, Activity Modulators, and Therapeutic Potential. BIOCHEMISTRY (MOSCOW) 2021; 86:S50-S70. [PMID: 33827400 DOI: 10.1134/s0006297921140054] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Although TRPV1 ion channel has been attracting researchers' attention for many years, its functions in animal organisms, the principles of regulation, and the involvement in pathological processes have not yet been fully clarified. Mutagenesis experiments and structural studies have identified the structural features of the channel and binding sites for its numerous ligands; however, these studies are far from conclusion. This review summarizes recent achievements in the TRPV1 research with special focus on structural and functional studies of the channel and on its ligands, which are extremely diverse in their nature and interaction specificity to TRPV1. Particular attention was given to the effects of numerous endogenous agonists and antagonists that can fine-tune the channel sensitivity to its usual activators, such as capsaicin, heat, acids, or their combination. In addition to the pain sensing not covered in this review, the TRPV1 channel was found to be involved in the regulation of many important physiological and pathological processes and, therefore, can be considered as a promising therapeutic target in the treatment of various diseases, such as pneumonia, ischemia, diabetes, epilepsy, schizophrenia, psoriasis, etc.
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Affiliation(s)
- Irina N Gladkikh
- Elyakov Pacific Institute of Bioorganic Chemistry, Far East Branch of the Russian Academy of Sciences, Vladivostok, 690022, Russia
| | - Oksana V Sintsova
- Elyakov Pacific Institute of Bioorganic Chemistry, Far East Branch of the Russian Academy of Sciences, Vladivostok, 690022, Russia
| | - Elena V Leychenko
- Elyakov Pacific Institute of Bioorganic Chemistry, Far East Branch of the Russian Academy of Sciences, Vladivostok, 690022, Russia
| | - Sergey A Kozlov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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18
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Lakk M, Križaj D. TRPV4-Rho signaling drives cytoskeletal and focal adhesion remodeling in trabecular meshwork cells. Am J Physiol Cell Physiol 2021; 320:C1013-C1030. [PMID: 33788628 PMCID: PMC8285634 DOI: 10.1152/ajpcell.00599.2020] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Intraocular pressure (IOP) is dynamically regulated by the trabecular meshwork (TM), a mechanosensitive tissue that protects the eye from injury through dynamic regulation of aqueous humor flow. TM compensates for mechanical stress impelled by chronic IOP elevations through increased actin polymerization, tissue stiffness, and contractility. This process has been associated with open angle glaucoma; however, the mechanisms that link mechanical stress to pathological cytoskeletal remodeling downstream from the mechanotransducers remain poorly understood. We used fluorescence imaging and biochemical analyses to investigate cytoskeletal and focal adhesion remodeling in human TM cells stimulated with physiological strains. Mechanical stretch promoted F-actin polymerization, increased the number and size of focal adhesions, and stimulated the activation of the Rho-associated protein kinase (ROCK). Stretch-induced activation of the small GTPase Ras homolog family member A (RhoA), and tyrosine phosphorylations of focal adhesion proteins paxillin, focal adhesion kinase (FAK), vinculin, and zyxin were time dependently inhibited by ROCK inhibitor trans-4-[(1R)-1-aminoethyl]-N-4-pyridinylcyclohexanecarboxamide dihydrochloride (Y-27632), and by HC-067047, an antagonist of transient receptor potential vanilloid 4 (TRPV4) channels. Both TRPV4 and ROCK activation were required for zyxin translocation and increase in the number/size of focal adhesions in stretched cells. Y-27632 blocked actin polymerization without affecting calcium influx induced by membrane stretch and the TRPV4 agonist GSK1016790A. These results reveal that mechanical tuning of TM cells requires parallel activation of TRPV4, integrins, and ROCK, with chronic stress leading to sustained remodeling of the cytoskeleton and focal complexes.
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Affiliation(s)
- Monika Lakk
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah
| | - David Križaj
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah.,Department of Bioengineering, University of Utah, Salt Lake City, Utah.,Department of Neurobiology, University of Utah, Salt Lake City, Utah
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Chaigne S, Cardouat G, Louradour J, Vaillant F, Charron S, Sacher F, Ducret T, Guinamard R, Vigmond E, Hof T. Transient receptor potential vanilloid 4 channel participates in mouse ventricular electrical activity. Am J Physiol Heart Circ Physiol 2021; 320:H1156-H1169. [PMID: 33449852 DOI: 10.1152/ajpheart.00497.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 01/06/2021] [Indexed: 12/25/2022]
Abstract
The TRPV4 channel is a calcium-permeable channel (PCa/PNa ∼ 10). Its expression has been reported in ventricular myocytes, where it is involved in several cardiac pathological mechanisms. In this study, we investigated the implication of TRPV4 in ventricular electrical activity. Left ventricular myocytes were isolated from trpv4+/+ and trpv4-/- mice. TRPV4 membrane expression and its colocalization with L-type calcium channels (Cav1.2) was confirmed using Western blot biotinylation, immunoprecipitation, and immunostaining experiments. Then, electrocardiograms (ECGs) and patch-clamp recordings showed shortened QTc and action potential (AP) duration in trpv4-/- compared with trpv4+/+ mice. Thus, TRPV4 activator GSK1016790A produced a transient and dose-dependent increase in AP duration at 90% of repolarization (APD90) in trpv4+/+ but not in trpv4-/- myocytes or when combined with TRPV4 inhibitor GSK2193874 (100 nM). Hence, GSK1016790A increased calcium transient (CaT) amplitude in trpv4+/+ but not in trpv4-/- myocytes, suggesting that TRPV4 carries an inward Ca2+ current in myocytes. Conversely, TRPV4 inhibitor GSK2193874 (100 nM) alone reduced APD90 in trpv4+/+ but not in trpv4-/- myocytes, suggesting that TRPV4 prolongs AP duration in basal condition. Finally, introducing TRPV4 parameters in a mathematical model predicted the development of an inward TRPV4 current during repolarization that increases AP duration and CaT amplitude, in accord with what was found experimentally. This study shows for the first time that TRPV4 modulates AP and QTc durations. It would be interesting to evaluate whether TRPV4 could be involved in long QT-mediated ventricular arrhythmias.NEW & NOTEWORTHY Transient receptor potential vanilloid 4 (TRPV4) is expressed at the membrane of mouse ventricular myocytes and colocalizes with non-T-tubular L-type calcium channels. Deletion of trpv4 gene in mice results in shortened QT interval on electrocardiogram and reduced action potential duration of ventricular myocytes. Pharmacological activation of TRPV4 channel leads to increased action potential duration and increased calcium transient amplitude in trpv4-/- but not in trpv4-/- ventricular myocytes. To the contrary, TRPV4 channel pharmacological inhibition reduces action potential duration in trpv4+/+ but not in trpv4-/- myocytes. Integration of TRPV4 channel in a computational model of mouse action potential shows that the channel carries an inward current contributing to slowing down action potential repolarization and to increase calcium transient amplitude, similarly to what is observed experimentally. This study highlights for the first time the involvement of TRPV4 channel in ventricular electrical activity.
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Affiliation(s)
- Sebastien Chaigne
- Instituts hospitalo-universitaires, L'Institut de Rythmologie et Modélisation Cardiaque, Fondation Bordeaux Université, Bordeaux, France
- Electrophysiology and Ablation Unit, Bordeaux University Hospital, Pessac, France
| | - Guillaume Cardouat
- Centre de recherche Cardio-Thoracique de Bordeaux, Institut national de la santé et de la recherche médicale, Bordeaux, France
- Centre de recherche Cardio-Thoracique de Bordeaux, Université Bordeaux, Bordeaux, France
| | - Julien Louradour
- Instituts hospitalo-universitaires, L'Institut de Rythmologie et Modélisation Cardiaque, Fondation Bordeaux Université, Bordeaux, France
| | - Fanny Vaillant
- Instituts hospitalo-universitaires, L'Institut de Rythmologie et Modélisation Cardiaque, Fondation Bordeaux Université, Bordeaux, France
| | - Sabine Charron
- Instituts hospitalo-universitaires, L'Institut de Rythmologie et Modélisation Cardiaque, Fondation Bordeaux Université, Bordeaux, France
- Centre de recherche Cardio-Thoracique de Bordeaux, Institut national de la santé et de la recherche médicale, Bordeaux, France
| | - Frederic Sacher
- Centre de recherche Cardio-Thoracique de Bordeaux, Université Bordeaux, Bordeaux, France
| | - Thomas Ducret
- Centre de recherche Cardio-Thoracique de Bordeaux, Institut national de la santé et de la recherche médicale, Bordeaux, France
- Centre de recherche Cardio-Thoracique de Bordeaux, Université Bordeaux, Bordeaux, France
| | - Romain Guinamard
- Signalisation, Electrophysiologie et Imagerie des lésions d'Ischémie-Reperfusion Myocardique, EA4650 Université Caen Normandie, Caen, France
| | - Edward Vigmond
- Instituts hospitalo-universitaires, L'Institut de Rythmologie et Modélisation Cardiaque, Fondation Bordeaux Université, Bordeaux, France
- Centre de recherche Cardio-Thoracique de Bordeaux, Université Bordeaux, Bordeaux, France
| | - Thomas Hof
- Instituts hospitalo-universitaires, L'Institut de Rythmologie et Modélisation Cardiaque, Fondation Bordeaux Université, Bordeaux, France
- Centre de recherche Cardio-Thoracique de Bordeaux, Université Bordeaux, Bordeaux, France
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Retinal ganglion cell dysfunction in mice following acute intraocular pressure is exacerbated by P2X7 receptor knockout. Sci Rep 2021; 11:4184. [PMID: 33603067 PMCID: PMC7893065 DOI: 10.1038/s41598-021-83669-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 12/22/2020] [Indexed: 12/21/2022] Open
Abstract
There is increasing evidence for the vulnerability of specific retinal ganglion cell (RGC) types in those with glaucoma and in animal models. In addition, the P2X7-receptor (P2X7-R) has been suggested to contribute to RGC death following stimulation and elevated IOP, though its role in RGC dysfunction prior to death has not been examined. Therefore, we examined the effect of an acute, non-ischemic intraocular pressure (IOP) insult (50 mmHg for 30 min) on RGC function in wildtype mice and P2X7-R knockout (P2X7-KO) mice. We examined retinal function using electroretinogram recordings and individual RGC responses using multielectrode arrays, 3 days following acute IOP elevation. Immunohistochemistry was used to examine RGC cell death and P2X7-R expression in several RGC types. Acute intraocular pressure elevation produced pronounced dysfunction in RGCs; whilst other retinal neuronal responses showed lesser changes. Dysfunction at 3 days post-injury was not associated with RGC loss or changes in receptive field size. However, in wildtype animals, OFF-RGCs showed reduced spontaneous and light-elicited activity. In the P2X7-KO, both ON- and OFF-RGC light-elicited responses were reduced. Expression of P2X7-R in wildtype ON-RGC dendrites was higher than in other RGC types. In conclusion, OFF-RGCs were vulnerable to acute IOP elevation and their dysfunction was not rescued by genetic ablation of P2X7-R. Indeed, knockout of P2X7-R also caused ON-RGC dysfunction. These findings aid our understanding of how pressure affects RGC function and suggest treatments targeting the P2X7-R need to be carefully considered.
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Abstract
Mechanosensing is a key feature through which organisms can receive inputs from the environment and convert them into specific functional and behavioral outputs. Mechanosensation occurs in many cells and tissues, regulating a plethora of molecular processes based on the distribution of forces and stresses both at the cell membrane and at the intracellular organelles levels, through complex interactions between cells’ microstructures, cytoskeleton, and extracellular matrix. Although several primary and secondary mechanisms have been shown to contribute to mechanosensation, a fundamental pathway in simple organisms and mammals involves the presence of specialized sensory neurons and the presence of different types of mechanosensitive ion channels on the neuronal cell membrane. In this contribution, we present a review of the main ion channels which have been proven to be significantly involved in mechanotransduction in neurons. Further, we discuss recent studies focused on the biological mechanisms and modeling of mechanosensitive ion channels’ gating, and on mechanotransduction modeling at different scales and levels of details.
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22
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Risner ML, McGrady NR, Boal AM, Pasini S, Calkins DJ. TRPV1 Supports Axogenic Enhanced Excitability in Response to Neurodegenerative Stress. Front Cell Neurosci 2021; 14:603419. [PMID: 33505248 PMCID: PMC7829306 DOI: 10.3389/fncel.2020.603419] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 12/15/2020] [Indexed: 01/24/2023] Open
Abstract
Early progression in neurodegenerative disease involves challenges to homeostatic processes, including those controlling axonal excitability and dendritic organization. In glaucoma, the leading cause of irreversible blindness, stress from intraocular pressure (IOP) causes degeneration of retinal ganglion cells (RGC) and their axons which comprise the optic nerve. Previously, we discovered that early progression induces axogenic, voltage-gated enhanced excitability of RGCs, even as dendritic complexity in the retina reduces. Here, we investigate a possible contribution of the transient receptor potential vanilloid type 1 (TRPV1) channel to enhanced excitability, given its role in modulating excitation in other neural systems. We find that genetic deletion of Trpv1 (Trpv1−/−) influences excitability differently for RGCs firing continuously to light onset (αON-Sustained) vs. light offset (αOFF-Sustained). Deletion drives excitability in opposing directions so that Trpv1−/− RGC responses with elevated IOP equalize to that of wild-type (WT) RGCs without elevated IOP. Depolarizing current injections in the absence of light-driven presynaptic excitation to directly modulate voltage-gated channels mirrored these changes, while inhibiting voltage-gated sodium channels and isolating retinal excitatory postsynaptic currents abolished both the differences in light-driven activity between WT and Trpv1−/− RGCs and changes in response due to IOP elevation. Together, these results support a voltage-dependent, axogenic influence of Trpv1−/− with elevated IOP. Finally, Trpv1−/− slowed the loss of dendritic complexity with elevated IOP, opposite its effect on axon degeneration, supporting the idea that axonal and dendritic degeneration follows distinctive programs even at the level of membrane excitability.
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Affiliation(s)
- Michael L Risner
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Nolan R McGrady
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Andrew M Boal
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Silvia Pasini
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
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Yarishkin O, Phuong TTT, Baumann JM, De Ieso ML, Vazquez-Chona F, Rudzitis CN, Sundberg C, Lakk M, Stamer WD, Križaj D. Piezo1 channels mediate trabecular meshwork mechanotransduction and promote aqueous fluid outflow. J Physiol 2021; 599:571-592. [PMID: 33226641 PMCID: PMC7849624 DOI: 10.1113/jp281011] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 11/17/2020] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Trabecular meshwork (TM) is a highly mechanosensitive tissue in the eye that regulates intraocular pressure through the control of aqueous humour drainage. Its dysfunction underlies the progression of glaucoma but neither the mechanisms through which TM cells sense pressure nor their role in aqueous humour outflow are understood at the molecular level. We identified the Piezo1 channel as a key TM transducer of tensile stretch, shear flow and pressure. Its activation resulted in intracellular signals that altered organization of the cytoskeleton and cell-extracellular matrix contacts and modulated the trabecular component of aqueous outflow whereas another channel, TRPV4, mediated a delayed mechanoresponse. This study helps elucidate basic mechanotransduction properties that may contribute to intraocular pressure regulation in the vertebrate eye. ABSTRACT Chronic elevations in intraocular pressure (IOP) can cause blindness by compromising the function of trabecular meshwork (TM) cells in the anterior eye, but how these cells sense and transduce pressure stimuli is poorly understood. Here, we demonstrate functional expression of two mechanically activated channels in human TM cells. Pressure-induced cell stretch evoked a rapid increase in transmembrane current that was inhibited by antagonists of the mechanogated channel Piezo1, Ruthenium Red and GsMTx4, and attenuated in Piezo1-deficient cells. The majority of TM cells exhibited a delayed stretch-activated current that was mediated independently of Piezo1 by TRPV4 (transient receptor potential cation channel, subfamily V, member 4) channels. Piezo1 functions as the principal TM transducer of physiological levels of shear stress, with both shear and the Piezo1 agonist Yoda1 increasing the number of focal cell-matrix contacts. Analysis of TM-dependent fluid drainage from the anterior eye showed significant inhibition by GsMTx4. Collectively, these results suggest that TM mechanosensitivity utilizes kinetically, regulatory and functionally distinct pressure transducers to inform the cells about force-sensing contexts. Piezo1-dependent control of shear flow sensing, calcium homeostasis, cytoskeletal dynamics and pressure-dependent outflow suggests potential for a novel therapeutic target in treating glaucoma.
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Affiliation(s)
- Oleg Yarishkin
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Tam T T Phuong
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Jackson M Baumann
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
| | - Michael L De Ieso
- Duke Eye Center, Duke University School of Medicine, Durham, NC, USA
| | - Felix Vazquez-Chona
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Christopher N Rudzitis
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Chad Sundberg
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - Monika Lakk
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
| | - W Daniel Stamer
- Duke Eye Center, Duke University School of Medicine, Durham, NC, USA
| | - David Križaj
- Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA
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Guarino BD, Paruchuri S, Thodeti CK. The role of TRPV4 channels in ocular function and pathologies. Exp Eye Res 2020; 201:108257. [PMID: 32979394 DOI: 10.1016/j.exer.2020.108257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/15/2022]
Abstract
Transient potential receptor vanilloid 4 (TRPV4) is an ion channel responsible for sensing osmotic and mechanical signals, which in turn regulates calcium signaling across cell membranes. TRPV4 is widely expressed throughout the body, and plays an important role in normal physiological function, as well as different pathologies, however, its role in the eye is not well known. In the eye, TRPV4 is expressed in various tissues, such as the retina, corneal epithelium, ciliary body, and the lens. In this review, we provide an overview on TRPV4 structure, activation, mutations, and summarize the current knowledge of TRPV4 function and signaling mechanisms in various locations throughout the eye, as well as its role in ocular diseases, such as glaucoma and diabetic retinopathy. Based on the available data, we highlight the therapeutic potential of TRPV4 as well as the shortcomings of current research. Finally, we provide future perspectives on the implications of targeting TRPV4 to treat various ocular pathologies.
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Affiliation(s)
- Brianna D Guarino
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | | | - Charles K Thodeti
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.
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25
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Febrile temperature change modulates CD4 T cell differentiation via a TRPV channel-regulated Notch-dependent pathway. Proc Natl Acad Sci U S A 2020; 117:22357-22366. [PMID: 32839313 DOI: 10.1073/pnas.1922683117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Fever is a conserved and prominent response to infection. Yet, the issue of how CD4 T cell responses are modulated if they occur at fever temperatures remains poorly addressed. We have examined the priming of naive CD4 T cells in vitro at fever temperatures, and we report notable fever-mediated modulation of their cytokine commitment. When naive CD4 T cells were primed by plate-bound anti-CD3 and anti-CD28 monoclonal antibodies at moderate fever temperature (39 °C), they enhanced commitment to IL4/5/13 (Th2) and away from IFNg (Th1). This was accompanied by up-regulation of the Th2-relevant transcription factor GATA3 and reduction in the Th1-relevant transcription factor Tbet. Fever sensing by CD4 T cells involved transient receptor potential vanilloid cation channels (TRPVs) since TRPV1/TRPV4 antagonism blocked the febrile Th2 switch, while TRPV1 agonists mediated a Th2 switch at 37 °C. The febrile Th2 switch was IL4 independent, but a γ-secretase inhibitor abrogated it, and it was not found in Notch1-null CD4 T cells, identifying the Notch pathway as a major mediator. However, when naive CD4 T cells were primed via antigen and dendritic cells (DCs) at fever temperatures, the Th2 switch was abrogated via increased production of IL12 from DCs at fever temperatures. Thus, immune cells directly sense fever temperatures with likely complex physiological consequences.
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26
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Lapajne L, Lakk M, Yarishkin O, Gubeljak L, Hawlina M, Križaj D. Polymodal Sensory Transduction in Mouse Corneal Epithelial Cells. Invest Ophthalmol Vis Sci 2020; 61:2. [PMID: 32271891 PMCID: PMC7401707 DOI: 10.1167/iovs.61.4.2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Purpose Contact lenses, osmotic stressors, and chemical burns may trigger severe discomfort and vision loss by damaging the cornea, but the signaling mechanisms used by corneal epithelial cells (CECs) to sense extrinsic stressors are not well understood. We therefore investigated the mechanisms of swelling, temperature, strain, and chemical transduction in mouse CECs. Methods Intracellular calcium imaging in conjunction with electrophysiology, pharmacology, transcript analysis, immunohistochemistry, and bioluminescence assays of adenosine triphosphate (ATP) release were used to track mechanotransduction in dissociated CECs and epithelial sheets isolated from the mouse cornea. Results The transient receptor potential vanilloid (TRPV) transcriptome in the mouse corneal epithelium is dominated by Trpv4, followed by Trpv2, Trpv3, and low levels of Trpv1 mRNAs. TRPV4 protein was localized to basal and intermediate epithelial strata, keratocytes, and the endothelium in contrast to the cognate TRPV1, which was confined to intraepithelial afferents and a sparse subset of CECs. The TRPV4 agonist GSK1016790A induced cation influx and calcium elevations, which were abolished by the selective blocker HC067047. Hypotonic solutions, membrane strain, and moderate heat elevated [Ca2+]CEC with swelling- and temperature-, but not strain-evoked signals, sensitive to HC067047. GSK1016790A and swelling evoked calcium-dependent ATP release, which was suppressed by HC067027 and the hemichannel blocker probenecid. Conclusions These results demonstrate that cation influx via TRPV4 transduces osmotic and thermal but not strain inputs to CECs and promotes hemichannel-dependent ATP release. The TRPV4-hemichannel-ATP signaling axis might modulate corneal pain induced by excessive mechanical, osmotic, and chemical stimulation.
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27
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Transient receptor potential vanilloid type 1 is expressed in the horizontal pathway of the vervet monkey retina. Sci Rep 2020; 10:12116. [PMID: 32694518 PMCID: PMC7374716 DOI: 10.1038/s41598-020-68937-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 07/03/2020] [Indexed: 01/04/2023] Open
Abstract
The ubiquitous distribution of the classic endocannabinoid system (cannabinoid receptors CB1 and CB2) has been demonstrated within the monkey nervous system, including the retina. Transient receptor potential vanilloid type 1 (TRPV1) is a cannabinoid-like non-selective cation channel receptor that is present in the retina and binds to endovannilloids and endocannabinoids, like anandamide, 2-arachidonoylglycerol and N-arachidonoyl dopamine. Retinal expression patterns of TRPV1 are available for rodents and data in higher mammals like humans and monkeys are scarce. We therefore thoroughly examined the expression and localization of TRPV1 in the retina, at various eccentricities, of the vervet (Chlorocebus sabeus) monkey, using Western blots and immunohistochemistry. Our results demonstrate that TRPV1 is found mainly in the outer and inner plexiform layers, and in the retinal ganglion cell (RGC) layer with a higher density in the periphery. Co-immunolabeling of TRPV1 with parvalbumin, a primate horizontal cell marker, revealed a clear overlap of expression throughout the entire cell structure with most prominent staining in the cell body membrane and synaptic terminals. Furthermore, double labeling of TRPV1 and syntaxin was found throughout amacrine cells in the inner plexiform layer. Finally, double staining of TRPV1 and Brn3a allowed us to confirm its previously reported expression in the cell bodies and dendrites of RGCs. The presence of TRPV1 in the horizontal pathway suggests a function of this receptor in lateral inhibition between photoreceptors through the horizontal cells, and between bipolar cells through amacrine cells.
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28
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Hu W, Ding Y, Li Q, shi R, He Y. Transient receptor potential vanilloid 4 channels as therapeutic targets in diabetes and diabetes-related complications. J Diabetes Investig 2020; 11:757-769. [PMID: 32129549 PMCID: PMC7378409 DOI: 10.1111/jdi.13244] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/21/2020] [Accepted: 02/27/2020] [Indexed: 12/12/2022] Open
Abstract
With an estimated 425 million diabetes patients worldwide in 2019, type 2 diabetes has reached a pandemic proportion and represents a major unmet medical need. A key determinant of the development and progression of type 2 diabetes is pancreatic -cell dysfunction, including the loss of cell mass, the impairment of insulin biosynthesis and inadequate exocytosis. Recent studies have shown that transient receptor potential vanilloid 4 (TRPV4), a Ca2+ -permeable non-selective cation channel, is involved in -cell replication, insulin production and secretion. TRPV4 agonists have insulinotropic activity in pancreatic -cell lines, but the prolonged activation of TRPV4 leads to -cell dysfunction and death. In addition, TRPV4 is involved in a wide variety of pathophysiological activities, and has been reported to play an important role in diabetes-related complications, such as obesity, cardiovascular diseases, diabetic retinopathy, nephropathy and neuropathy. In a rodent type 2 diabetes model, Trpv4 agonists promote vasodilation and improve cardiovascular function, whereas Trpv4 antagonists reduce high-fat diet-induced obesity, insulin resistance, diabetic nephropathy, retinopathy and neuropathy. These findings raise interest in using TRPV4 as a therapeutic target for type 2 diabetes. In this review, we intend to summarize the latest findings regarding the role of TRPV4 in diabetes as well as diabetes-related conditions, and to evaluate its potential as a therapeutic target for diabetes and diabetes-related diseases.
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Affiliation(s)
- Wei Hu
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
| | - Yuanlin Ding
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
| | - Qingqing Li
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
| | - Rou shi
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
| | - Yuqing He
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
- Liaobu HospitalGuangdong Medical UniversityDongguanChina
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29
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Nelidova D, Morikawa RK, Cowan CS, Raics Z, Goldblum D, Scholl HPN, Szikra T, Szabo A, Hillier D, Roska B. Restoring light sensitivity using tunable near-infrared sensors. Science 2020; 368:1108-1113. [DOI: 10.1126/science.aaz5887] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Accepted: 04/09/2020] [Indexed: 12/29/2022]
Abstract
Enabling near-infrared light sensitivity in a blind human retina may supplement or restore visual function in patients with regional retinal degeneration. We induced near-infrared light sensitivity using gold nanorods bound to temperature-sensitive engineered transient receptor potential (TRP) channels. We expressed mammalian or snake TRP channels in light-insensitive retinal cones in a mouse model of retinal degeneration. Near-infrared stimulation increased activity in cones, ganglion cell layer neurons, and cortical neurons, and enabled mice to perform a learned light-driven behavior. We tuned responses to different wavelengths, by using nanorods of different lengths, and to different radiant powers, by using engineered channels with different temperature thresholds. We targeted TRP channels to human retinas, which allowed the postmortem activation of different cell types by near-infrared light.
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Affiliation(s)
- Dasha Nelidova
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Rei K. Morikawa
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Cameron S. Cowan
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Zoltan Raics
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - David Goldblum
- Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Hendrik P. N. Scholl
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Tamas Szikra
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Arnold Szabo
- Department of Anatomy, Semmelweis University, Budapest, Hungary
| | - Daniel Hillier
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- Deutsches Primatzentrum, Leibniz Institute for Primate Research, Göttingen, Germany
- Research Centre for Natural Sciences, Budapest, Hungary
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Botond Roska
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
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30
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Wei J, Lin J, Zhang J, Tang D, Xiang F, Cui L, Zhang Q, Yuan H, Song H, Lv Y, Jia J, Zhang D, Huang Y. TRPV1 activation mitigates hypoxic injury in mouse cardiomyocytes by inducing autophagy through the AMPK signaling pathway. Am J Physiol Cell Physiol 2020; 318:C1018-C1029. [PMID: 32293932 DOI: 10.1152/ajpcell.00161.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Autophagy is a highly conserved self-protection mechanism that plays a crucial role in cardiovascular diseases. Cardiomyocyte hypoxic injury promotes oxidative stress and pathological alterations in the heart, although the interplay between these effects remains elusive. The transient receptor potential vanilloid 1 (TRPV1) ion channel is a nonselective cation channel that is activated in response to a variety of exogenous and endogenous physical and chemical stimuli. Here, we investigated the effects and mechanisms of action of TRPV1 on autophagy in hypoxic cardiomyocytes. In this study, primary cardiomyocytes isolated from C57 mice were subjected to hypoxic stress, and their expression of TRPV1 and adenosine 5'-monophosphate-activated protein kinase (AMPK) was regulated. The autophagy flux was assessed by Western blotting and immunofluorescence staining, and the cell viability was determined through Cell counting kit-8 assay and Lactate dehydrogenase assays. In addition, the calcium influx after the upregulation of TRPV1 expression in cardiomyocytes was examined. The results showed that the number of autophagosomes in cardiomyocytes was higher under hypoxic stress and that the blockade of autophagy flux aggravated hypoxic damage to cardiomyocytes. Moreover, the expression of TRPV1 was induced under hypoxic stress, and its upregulation by capsaicin improved the autophagy flux and protected cardiomyocytes from hypoxic damage, whereas the silencing of TRPV1 significantly attenuated autophagy. Our observations also revealed that AMPK signaling was activated and involved in TRPV1-induced autophagy in cardiomyocytes under hypoxic stress. Overall, this study demonstrates that TRPV1 activation mitigates hypoxic injury in cardiomyocytes by improving autophagy flux through the AMPK signaling pathway and highlights TRPV1 as a novel therapeutic target for the treatment of hypoxic cardiac disease.
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Affiliation(s)
- Jinyu Wei
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Department of Dermatology, the 920th Hospital of Joint Logistics Support Force of PLA, Kunming, China
| | - Jiezhi Lin
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Military Burn Center, the 963th (224th) Hospital of Joint Logistics Support Force of PLA, Jiamusi, China
| | - Junhui Zhang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Di Tang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Fei Xiang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Lin Cui
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Qiong Zhang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Hongping Yuan
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Huapei Song
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Yanling Lv
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Jiezhi Jia
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Dongxia Zhang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Yuesheng Huang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
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31
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McGrady NR, Risner ML, Vest V, Calkins DJ. TRPV1 Tunes Optic Nerve Axon Excitability in Glaucoma. Front Physiol 2020; 11:249. [PMID: 32273850 PMCID: PMC7113399 DOI: 10.3389/fphys.2020.00249] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/05/2020] [Indexed: 12/23/2022] Open
Abstract
The transient receptor potential vanilloid member 1 (TRPV1) in the central nervous system may contribute to homeostatic plasticity by regulating intracellular Ca2+, which becomes unbalanced in age-related neurodegenerative diseases, including Alzheimer’s and Huntington’s. Glaucomatous optic neuropathy – the world’s leading cause of irreversible blindness – involves progressive degeneration of retinal ganglion cell (RGC) axons in the optic nerve through sensitivity to stress related to intraocular pressure (IOP). In models of glaucoma, genetic deletion of TRPV1 (Trpv1–/–) accelerates RGC axonopathy in the optic projection, whereas TRPV1 activation modulates RGC membrane polarization. In continuation of these studies, here, we found that Trpv1–/– increases the compound action potential (CAP) of optic nerves subjected to short-term elevations in IOP. This IOP-induced increase in CAP was not directly due to TRPV1 channels in the optic nerve, because the TRPV1-selective antagonist iodoresiniferatoxin had no effect on the CAP for wild-type optic nerve. Rather, the enhanced CAP in Trpv1–/– optic nerve was associated with increased expression of the voltage-gated sodium channel subunit 1.6 (NaV1.6) in longer nodes of Ranvier within RGC axons, rendering Trpv1–/– optic nerve relatively insensitive to NaV1.6 antagonism via 4,9-anhydrotetrodotoxin. These results indicate that with short-term elevations in IOP, Trpv1–/– increases axon excitability through greater NaV1.6 localization within longer nodes. In neurodegenerative disease, native TRPV1 may tune NaV expression in neurons under stress to match excitability to available metabolic resources.
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Affiliation(s)
- Nolan R McGrady
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Michael L Risner
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Victoria Vest
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
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O'Leary C, McGahon MK, Ashraf S, McNaughten J, Friedel T, Cincolà P, Barabas P, Fernandez JA, Stitt AW, McGeown JG, Curtis TM. Involvement of TRPV1 and TRPV4 Channels in Retinal Angiogenesis. Invest Ophthalmol Vis Sci 2019; 60:3297-3309. [PMID: 31369032 DOI: 10.1167/iovs.18-26344] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We investigate the contribution of TRPV1 and TRPV4 channels to retinal angiogenesis. Methods Primary retinal microvascular endothelial cells (RMECs) were used for RT-PCR, Western blotting, immunolabeling, Ca2+ signaling, and whole-cell patch-clamp studies while localization of TRPV1 also was assessed in retinal endothelial cells using whole mount preparations. The effects of pharmacologic blockers of TRPV1 and TRPV4 on retinal angiogenic activity was evaluated in vitro using sprout formation, cell migration, proliferation, and tubulogenesis assays, and in vivo using the mouse model of oxygen-induced retinopathy (OIR). Heteromultimerization of TRPV1 and TRPV4 channels in RMECs was assessed using proximity ligation assays (PLA) and electrophysiologic recording. Results TRPV1 mRNA and protein expression were identified in RMECs. TRPV1 labelling was found to be mainly localized to the cytoplasm with some areas of staining colocalizing with the plasma membrane. Staining patterns for TRPV1 were broadly similar in endothelial cells of intact vessels within retinal flat mounts. Functional expression of TRPV1 and TRPV4 in RMECs was confirmed by patch-clamp recording. Pharmacologic inhibition of TRPV1 or TRPV4 channels suppressed in vitro retinal angiogenesis through a mechanism involving the modulation of tubulogenesis. Blockade of these channels had no effect on VEGF-stimulated angiogenesis or Ca2+ signals in vitro. PLA and patch-clamp studies revealed that TRPV1 and TRPV4 form functional heteromeric channel complexes in RMECs. Inhibition of either channel reduced retinal neovascularization and promoted physiologic revascularization of the ischemic retina in the OIR mouse model. Conclusions TRPV1 and TRPV4 channels represent promising targets for therapeutic intervention in vasoproliferative diseases of the retina.
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Affiliation(s)
- Caitriona O'Leary
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Mary K McGahon
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Sadaf Ashraf
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Jennifer McNaughten
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Thomas Friedel
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Patrizia Cincolà
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Peter Barabas
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Jose A Fernandez
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Alan W Stitt
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - J Graham McGeown
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
| | - Tim M Curtis
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University of Belfast, Belfast, United Kingdom
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33
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Wang AY, Lee PY, Bui BV, Jobling AI, Greferath U, Brandli A, Dixon MA, Findlay Q, Fletcher EL, Vessey KA. Potential mechanisms of retinal ganglion cell type-specific vulnerability in glaucoma. Clin Exp Optom 2019; 103:562-571. [PMID: 31838755 DOI: 10.1111/cxo.13031] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 10/17/2019] [Accepted: 11/16/2019] [Indexed: 12/22/2022] Open
Abstract
Glaucoma is a neurodegenerative disease characterised by progressive damage to the retinal ganglion cells (RGCs), the output neurons of the retina. RGCs are a heterogenous class of retinal neurons which can be classified into multiple types based on morphological, functional and genetic characteristics. This review examines the body of evidence supporting type-specific vulnerability of RGCs in glaucoma and explores potential mechanisms by which this might come about. Studies of donor tissue from glaucoma patients have generally noted greater vulnerability of larger RGC types. Models of glaucoma induced in primates, cats and mice also show selective effects on RGC types - particularly OFF RGCs. Several mechanisms may contribute to type-specific vulnerability, including differences in the expression of calcium-permeable receptors (for example pannexin-1, P2X7, AMPA and transient receptor potential vanilloid receptors), the relative proximity of RGCs and their dendrites to blood supply in the inner plexiform layer, as well as differing metabolic requirements of RGC types. Such differences may make certain RGCs more sensitive to intraocular pressure elevation and its associated biomechanical and vascular stress. A greater understanding of selective RGC vulnerability and its underlying causes will likely reveal a rich area of investigation for potential treatment targets.
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Affiliation(s)
- Anna Ym Wang
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Pei Ying Lee
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Alice Brandli
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Michael A Dixon
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Quan Findlay
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
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34
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Nakazawa Y, Donaldson PJ, Petrova RS. Verification and spatial mapping of TRPV1 and TRPV4 expression in the embryonic and adult mouse lens. Exp Eye Res 2019; 186:107707. [PMID: 31229503 DOI: 10.1016/j.exer.2019.107707] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/18/2019] [Accepted: 06/19/2019] [Indexed: 01/10/2023]
Abstract
The transient receptor protein vanilloid channels, TRPV1 and TRPV4, have recently been shown to be mechanosensors in the ocular lens that act to transduce physical changes in lens volume and internal hydrostatic pressure into the activation of signalling pathways in lens epithelial cells. These pathways in turn regulate ion and water transport to ensure that the optical properties of the lens remain constant. Despite the functional evidence that implicate the roles of TRPV1 and TRPV4 in the lens, their respective cellular expression patterns in the different regions of the lens has to date not been fully characterised. Using Western blotting we have confirmed that TRPV1 and TRPV4 are expressed throughout all regions (epithelium, outer cortex, inner cortex/core) of the adult mouse lens. Subsequent immunolabeling of lens cryosections confirmed that TRPV1 and TRPV4 are expressed throughout all regions of the lens, but revealed differentiation-dependent differences in the subcellular expression of the two channels in the different regions. In the epithelium and outer cortex, intense TRPV1 and TRPV4 labeling was predominately associated with the cytoplasm. In a discrete zone in the inner cortex, labeling for both proteins was greatly diminished, but could be enhanced by incubating sections with the detergent Triton X-100 to reveal TRPV1 and TRPV4 labelling that was associated with the membrane. This suggests that in this region of the lens there is a potential interacting protein that masks the binding of the TRPV1 and TRPV4 antibodies to their respective epitopes in the lens inner cortex. In the core of the lens, which contains the embryonic nucleus, TRPV1 and TRPV4 labelling was associated exclusively with fibre cell membranes. This labelling in the lens core of the adult mouse lens appeared to originate in early development as a similar membrane labelling was observed at embryonic day 10 (E10) of the cells in the lens vesicle that subsequently forms the embryonic nucleus in the adult lens. During subsequent stages of embryonic development TRPV1 and TRPV4 remained membranous in the inner cortex and core, while showing labelling that was associated with the cytoplasm in the superficial outer cortical region. The extent of cytoplasmic labelling for TRPV4, but not TRPV1, in this cortical region could however be dynamically regulated by cutting the zonules that normally attach the lens to the ciliary body. We have shown an early onset and continuous expression of TRPV1 and TRPV4 across all lens regions, and that TRPV4 can be dynamically trafficked into the membranes of differentiating fibre cells, results that suggests that these mechanosensitive channels may also be functionally active in lens fibre cells.
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Affiliation(s)
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Rosica S Petrova
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, New Zealand.
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