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Wang HN, Qian WJ, Zhao GL, Li F, Miao YY, Lei B, Sun XH, Wang ZF. L- and T-type Ca 2+ channels dichotomously contribute to retinal ganglion cell injury in experimental glaucoma. Neural Regen Res 2023; 18:1570-1577. [PMID: 36571364 PMCID: PMC10075096 DOI: 10.4103/1673-5374.360277] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Retinal ganglion cell apoptotic death is the main pathological characteristic of glaucoma, which is the leading cause of irreversible blindness. Disruption of Ca2+ homeostasis plays an important role in glaucoma. Voltage-gated Ca2+ channel blockers have been shown to improve vision in patients with glaucoma. However, whether and how voltage-gated Ca2+ channels are involved in retinal ganglion cell apoptotic death are largely unknown. In this study, we found that total Ca2+ current densities in retinal ganglion cells were reduced in a rat model of chronic ocular hypertension experimental glaucoma, as determined by whole-cell patch-clamp electrophysiological recordings. Further analysis showed that L-type Ca2+ currents were downregulated while T-type Ca2+ currents were upregulated at the later stage of glaucoma. Western blot assay and immunofluorescence experiments confirmed that expression of the CaV1.2 subunit of L-type Ca2+ channels was reduced and expression of the CaV3.3 subunit of T-type Ca2+ channels was increased in retinas of the chronic ocular hypertension model. Soluble tumor necrosis factor-α, an important inflammatory factor, inhibited the L-type Ca2+ current of isolated retinal ganglion cells from control rats and enhanced the T-type Ca2+ current. These changes were blocked by the tumor necrosis factor-α inhibitor XPro1595, indicating that both types of Ca2+ currents may be mediated by soluble tumor necrosis factor-α. The intracellular mitogen-activated protein kinase/extracellular signal-regulated kinase pathway and nuclear factor kappa-B signaling pathway mediate the effects of tumor necrosis factor-α. TUNEL assays revealed that mibefradil, a T-type calcium channel blocker, reduced the number of apoptotic retinal ganglion cells in the rat model of chronic ocular hypertension. These results suggest that T-type Ca2+ channels are involved in disrupted Ca2+ homeostasis and apoptosis of retinal ganglion cells in glaucoma, and application of T-type Ca2+ channel blockers, especially a specific CaV3.3 blocker, may be a potential strategy for the treatment of glaucoma.
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Affiliation(s)
- Hong-Ning Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Wen-Jing Qian
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Guo-Li Zhao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yan-Ying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Bo Lei
- Institutes of Neuroscience and Third Affiliated Hospital, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, Henan Province, China
| | - Xing-Huai Sun
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, NHC Key Laboratory of Myopia, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Zhong-Feng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
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Wei HX, Guan YN, Chen PP, Rao ZZ, Yang JS. Upregulation of EphA4 deteriorate brain damage by shifting microglia M1-polarization via NF-κB signaling after focal cerebral ischemia in rats. Heliyon 2023; 9:e18429. [PMID: 37519758 PMCID: PMC10375859 DOI: 10.1016/j.heliyon.2023.e18429] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 07/13/2023] [Accepted: 07/17/2023] [Indexed: 08/01/2023] Open
Abstract
Ischemic stroke is the main reason of disability and mortality in many countries, and currently has limited treatments. The post-stroke inflammation characterized with microglia activation and polarization has been regarded as a promising therapeutic target for ischemic stroke. After ischemia, the activated microglia polarize to classical (M1) phenotype or alternative (M2) phenotype and exhibit biphasic function. Promoting microglia phenotype shift from deleterious M1 phenotype to neuroprotective M2 phenotype will be promising in stroke treatment. Increasing evidence indicates that the erythropoietin-producing human hepatocellular (Eph) receptor A4 (EphA4), a kind of abundant Eph receptor, distributes mainly in neuron and participates in multiple links of pathological changes after ischemia. This paper discussed the hypothesis that EphA4 receptor could affect ischemic brain injury through EphA4/ephrin bidirectional signaling between neuron and microglia, and then explored its underlying mechanisms. We manipulated EphA4/ephrin signaling with either EphA4 overexpression lentiviral vectors or the short hairpin RNA (shRNA) to upregulate or knock down neuronal EphA4 expression. NF-κB inhibitor pyrrolidine dithiocarbamate ammonium salt (PDTC) was applied to block NF-κB pathway. According to the experimental results, upregulated neuronal EphA4 induced by ischemia deteriorated neurological function as well as brain damage by shifting microglia M1-polarization via promoting NF-κB signaling.
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Affiliation(s)
- Hui-Xing Wei
- Department of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, PR China
- Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, PR China
- Department of Neurology, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, PR China
| | - Yun-Ni Guan
- Department of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, PR China
- Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, PR China
| | - Ping-Ping Chen
- Department of Neurology, Xiang'an Hospital of Xiamen University, Xiamen, PR China
| | - Zhao-Zeng Rao
- Department of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, PR China
- Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, PR China
- Department of Neurology, Longyan People's Hospital, Longyan, PR China
| | - Jin-Shan Yang
- Department of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, PR China
- Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, PR China
- Department of Neurology, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, PR China
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Yin N, Wang HN, Ding WW, Zhou H, Li SY, Miao Y, Li F, Lei B, Wang Z. Dopamine receptor-mediated roles on retinal ganglion cell hyperexcitability and injury in experimental glaucoma. Cell Signal 2023:110781. [PMID: 37354963 DOI: 10.1016/j.cellsig.2023.110781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 06/14/2023] [Accepted: 06/21/2023] [Indexed: 06/26/2023]
Abstract
Extraordinary excitability (hyperexcitability) is closely related to retinal ganglion cell (RGC) injury in glaucoma. Dopamine (DA) and its receptors are involved in modulating RGC excitability. We investigated how DA system affects RGC injury in chronic ocular hypertension (COH) experimental glaucoma model. Western blotting and immunohistochemistry results revealed that expression of DA D2-like receptor (D2R) in RGCs was increased in COH retinas. Patch-clamp recordings showed that outward K+ currents were downregulated, while Na+ currents and NaV1.6 expression were upregulated in RGCs of COH retinas, which could be reversed by intravitreal pre-injection of the D2R antagonist sulpiride, but not by the D1-like receptor (D1R) antagonist SCH23390. However, pre-injection of the D1R agonist SKF81297 could partially reverse the increased expression of NaV1.6 proteins. Consistently, the numbers of evoked action potentials induced by current injections were increased in RGCs of COH retinas, indicating that RGCs may be in a condition of hyperexcitability. The increased frequency of evoked action potentials could be partially block by pre-injection of sulpiride, SKF81297 or DA, respectively. Furthermore, the increased number of TUNEL-positive RGCs in COH retinas could be partially reduced by intravitreal pre-injection of sulpiride, but not by pre-injection of SCH23390. Moreover, pre-injection of SKF81297 or DA could reduce the number of TUNEL-positive RGCs in COH retinas. All these results indicate that in COH retina, activation of D2R enhances RGC hyperexcitability and injury, while activation of D1R results in the opposite effects. Selective inhibition of D2R or activation of D1R may be an effective strategy for treatment of glaucoma.
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Affiliation(s)
- Ning Yin
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Hong-Ning Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Wen-Wen Ding
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Han Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Shu-Ying Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Bo Lei
- Institutes of Neuroscience and Third Affiliated Hospital, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou 450003, China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
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Miao Y, Zhao GL, Cheng S, Wang Z, Yang XL. Activation of retinal glial cells contributes to the degeneration of ganglion cells in experimental glaucoma. Prog Retin Eye Res 2023; 93:101169. [PMID: 36736070 DOI: 10.1016/j.preteyeres.2023.101169] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/12/2023] [Accepted: 01/24/2023] [Indexed: 02/04/2023]
Abstract
Elevation of intraocular pressure (IOP) is a major risk factor for neurodegeneration in glaucoma. Glial cells, which play an important role in normal functioning of retinal neurons, are well involved into retinal ganglion cell (RGC) degeneration in experimental glaucoma animal models generated by elevated IOP. In response to elevated IOP, mGluR I is first activated and Kir4.1 channels are subsequently inhibited, which leads to the activation of Müller cells. Müller cell activation is followed by a complex process, including proliferation, release of inflammatory and growth factors (gliosis). Gliosis is further regulated by several factors. Activated Müller cells contribute to RGC degeneration through generating glutamate receptor-mediated excitotoxicity, releasing cytotoxic factors and inducing microglia activation. Elevated IOP activates microglia, and following morphological and functional changes, these cells, as resident immune cells in the retina, show adaptive immune responses, including an enhanced release of pro-inflammatory factors (tumor neurosis factor-α, interleukins, etc.). These ATP and Toll-like receptor-mediated responses are further regulated by heat shock proteins, CD200R, chemokine receptors, and metabotropic purinergic receptors, may aggravate RGC loss. In the optic nerve head, astrogliosis is initiated and regulated by a complex reaction process, including purines, transmitters, chemokines, growth factors and cytokines, which contributes to RGC axon injury through releasing pro-inflammatory factors and changing extracellular matrix in glaucoma. The effects of activated glial cells on RGCs are further modified by the interplay among different types of glial cells. This review is concluded by presenting an in-depth discussion of possible research directions in this field in the future.
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Affiliation(s)
- Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Guo-Li Zhao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Shuo Cheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
| | - Xiong-Li Yang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
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Zhou ZX, Xu LJ, Wang HN, Cheng S, Li F, Miao Y, Lei B, Gao F, Wang Z. EphA4/ephrinA3 reverse signaling mediated downregulation of glutamate transporter GLAST in Müller cells in an experimental glaucoma model. Glia 2023; 71:720-741. [PMID: 36416239 DOI: 10.1002/glia.24307] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 11/07/2022] [Accepted: 11/12/2022] [Indexed: 11/24/2022]
Abstract
Deficiency of glutamate transporter GLAST in Müller cells may be culpable for excessive extracellular glutamate, which involves in retinal ganglion cell (RGC) damage in glaucoma. We elucidated how GLAST was regulated in rat chronic ocular hypertension (COH) model. Western blot and whole-cell patch-clamp recordings showed that GLAST proteins and GLAST-mediated current densities in Müller cells were downregulated at the early stages of COH. In normal rats, intravitreal injection of the ephrinA3 activator EphA4-Fc mimicked the changes of GLAST in COH retinas. In purified cultured Müller cells, EphA4-Fc treatment reduced GLAST expression at mRNA and protein levels, which was reversed by the tyrosine kinase inhibitor PP2 or transfection with ephrinA3-siRNA (Si-EFNA3), suggesting that EphA4/ephrinA3 reverse signaling mediated GLAST downregulation. EphA4/ephrinA3 reverse signaling-induced GLAST downregulation was mediated by inhibiting PI3K/Akt/NF-κB pathways since EphA4-Fc treatment of cultured Müller cells reduced the levels of p-Akt/Akt and NF-κB p65, which were reversed by transfecting Si-EFNA3. In Müller cells with ephrinA3 knockdown, the PI3K inhibitor LY294002 still decreased the protein levels of NF-κB p65 in the presence of EphA4-Fc, and the mRNA levels of GLAST were reduced by LY294002 and the NF-κB inhibitor SN50, respectively. Pre-injection of the PI3K/Akt pathway activator 740 Y-P reversed the GLAST downregulation in COH retinas. Western blot and TUNEL staining showed that transfecting of Si-EFNA3 reduced Müller cell gliosis and RGC apoptosis in COH retinas. Our results suggest that activated EphA4/ephrinA3 reverse signaling induces GLAST downregulation in Müller cells via inhibiting PI3K/Akt/NF-κB pathways, thus contributing to RGC damage in glaucoma.
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Affiliation(s)
- Zhi-Xin Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Lin-Jie Xu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Hong-Ning Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Shuo Cheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Bo Lei
- Institutes of Neuroscience and Third Affiliated Hospital, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Feng Gao
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, NHC Key Laboratory of Myopia, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
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Xu LJ, Wang HN, Zhou H, Li SY, Li F, Miao Y, Lei B, Sun XH, Gao F, Wang Z. EphA4/ephrinA3 reverse signaling induced Müller cell gliosis and production of pro-inflammatory cytokines in experimental glaucoma. Brain Res 2023; 1801:148204. [PMID: 36529265 DOI: 10.1016/j.brainres.2022.148204] [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: 10/12/2022] [Revised: 11/18/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
Previous work showed that ephrinA3/EphA4 forward signaling contributed to retinal ganglion cell (RGC) damage in experimental glaucoma. Since up-regulated patterns of ephrinA3 and EphA4 were observed in Müller cells and RGCs, an EphA4/ephrinA3 reverse signaling may exist in Müller cells of chronic ocular hypertension (COH) retina. We investigated effects of EphA4/ephrinA3 reverse signaling activation on Müller cells in COH retina. Intravitreal injection of the ephrinA3 agonist EphA4-Fc increased glial fibrillary acidic protein (GFAP) levels in normal retinas, suggestive of Müller cell gliosis, which was confirmed in purified cultured Müller cells treated with EphA4-Fc. These effects were mediated by intracellular STAT3 signaling pathway as phosphorylated STAT3 (p-STAT3) levels and ratios of p-STAT3/STAT3 were significantly increased in both COH retinas and EphA4-Fc intravitreally injected retinas, as well as in EphA4-Fc treated purified cultured Müller cells. The increase of GFAP protein levels in EphA4-Fc-injected retinas and EphA4-Fc treated purified cultured Müller cells could be partially eliminated by stattic, a selective STAT3 blocker. Co-immunoprecipitation results testified to the presence of interaction between ephrinA3 and STAT3/p-STAT3. In addition, intravitreal injection of EphA4-Fc or EphA4-Fc treatment of cultured Müller cells significantly up-regulated mRNA and protein contents of pro-inflammatory cytokines. Moreover, intravitreal injection of EphA4-Fc increased the number of apoptotic RGCs, which could be reversed by the tyrosine kinase blocker PP2. Overall, EphA4/ephrinA3 reverse signaling may induce Müller cell gliosis and increases release of pro-inflammatory factors, which could contribute to RGC death in glaucoma. Inhibition of EphA4/ephrinA3 signaling may provide an effective neuroprotection in glaucoma.
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Affiliation(s)
- Lin-Jie Xu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Hong-Ning Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Han Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Shu-Ying Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Bo Lei
- Institute of Neuroscience and Third Affiliated Hospital, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou 450003, China
| | - Xing-Huai Sun
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, NHC Key Laboratory of Myopia, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai 200031, China.
| | - Feng Gao
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, NHC Key Laboratory of Myopia, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai 200031, China.
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
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Pathologically high intraocular pressure disturbs normal iron homeostasis and leads to retinal ganglion cell ferroptosis in glaucoma. Cell Death Differ 2023; 30:69-81. [PMID: 35933500 PMCID: PMC9883496 DOI: 10.1038/s41418-022-01046-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 07/10/2022] [Accepted: 07/12/2022] [Indexed: 02/01/2023] Open
Abstract
Glaucoma can result in retinal ganglion cell (RGC) death and permanently damaged vision. Pathologically high intraocular pressure (ph-IOP) is the leading cause of damaged vision during glaucoma; however, controlling ph-IOP alone does not entirely prevent the loss of glaucomatous RGCs, and the underlying mechanism remains elusive. In this study, we reported an increase in ferric iron in patients with acute primary angle-closure glaucoma (the most typical glaucoma with ph-IOP damage) compared with the average population by analyzing free iron levels in peripheral serum. Thus, iron metabolism might be involved in regulating the injury of RGCs under ph-IOP. In vitro and in vivo studies confirmed that ph-IOP led to abnormal accumulation of ferrous iron in cells and retinas at 1-8 h post-injury and elevation of ferric iron in serum at 8 h post-injury. Nuclear receptor coactivator 4 (NCOA4)-mediated degradation of ferritin heavy polypeptide 1(FTH1) is essential to disrupt iron metabolism in the retina after ph-IOP injury. Furthermore, knockdown of Ncoa4 in vivo inhibited FTH1 degradation and reduced the retinal ferrous iron level. Elevated ferrous iron induced by ph-IOP led to a marked accumulation of pro-ferroptotic factors (lipid peroxidation and acyl CoA synthetase long-chain family member 4) and a depletion of anti-ferroptotic factors (glutathione, glutathione peroxidase 4, and nicotinamide adenine dinucleotide phosphate). These biochemical changes resulted in RGC ferroptosis. Deferiprone can pass through the blood-retinal barrier after oral administration and chelated abnormally elevated ferrous iron in the retina after ph-IOP injury, thus inhibiting RGC ferroptosis and protecting visual function. In conclusion, this study revealed the role of NCOA4-FTH1-mediated disturbance of iron metabolism and ferroptosis in RGCs during glaucoma. We demonstrate the protective effect of Deferiprone on RGCs via inhibition of ferroptosis, providing a research direction to understand and treat glaucoma via the iron homeostasis and ferroptosis pathways.
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Role of EphA4 in Mediating Motor Neuron Death in MND. Int J Mol Sci 2021; 22:ijms22179430. [PMID: 34502339 PMCID: PMC8430883 DOI: 10.3390/ijms22179430] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 11/26/2022] Open
Abstract
Motor neuron disease (MND) comprises a group of fatal neurodegenerative diseases with no effective cure. As progressive motor neuron cell death is one of pathological characteristics of MND, molecules which protect these cells are attractive therapeutic targets. Accumulating evidence indicates that EphA4 activation is involved in MND pathogenesis, and inhibition of EphA4 improves functional outcomes. However, the underlying mechanism of EphA4’s function in MND is unclear. In this review, we first present results to demonstrate that EphA4 signalling acts directly on motor neurons to cause cell death. We then review the three most likely mechanisms underlying this effect.
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Cheng S, Wang HN, Xu LJ, Li F, Miao Y, Lei B, Sun X, Wang Z. Soluble tumor necrosis factor-alpha-induced hyperexcitability contributes to retinal ganglion cell apoptosis by enhancing Nav1.6 in experimental glaucoma. J Neuroinflammation 2021; 18:182. [PMID: 34419081 PMCID: PMC8380326 DOI: 10.1186/s12974-021-02236-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/09/2021] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Neuroinflammation plays an important role in the pathogenesis of glaucoma. Tumor necrosis factor-alpha (TNF-α) is a major pro-inflammatory cytokine released from activated retinal glial cells in glaucoma. Here, we investigated how TNF-α induces retinal ganglion cell (RGC) hyperexcitability and injury. METHODS Whole-cell patch-clamp techniques were performed to explore changes in spontaneous firing and evoked action potentials, and Na+ currents in RGCs. Both intravitreal injection of TNF-α and chronic ocular hypertension (COH) models were used. Western blotting, immunofluorescence, quantitative real-time polymerase chain reaction (q-PCR), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) techniques were employed to investigate the molecular mechanisms of TNF-α effects on RGCs. RESULTS Intravitreal injection of soluble TNF-α significantly increased the spontaneous firing frequencies of RGCs in retinal slices. When the synaptic transmissions were blocked, more than 90% of RGCs still showed spontaneous firing; both the percentage of cells and firing frequency were higher than the controls. Furthermore, the frequency of evoked action potentials was also higher than the controls. Co-injection of the TNF-α receptor 1 (TNFR1) inhibitor R7050 eliminated the TNF-α-induced effects, suggesting that TNF-α may directly act on RGCs to induce cell hyperexcitability through activating TNFR1. In RGCs acutely isolated from TNF-α-injected retinas, Na+ current densities were upregulated. Perfusing TNF-α in RGCs of normal rats mimicked this effect, and the activation curve of Na+ currents shifted toward hyperpolarization direction, which was mediated through p38 MAPK and STAT3 signaling pathways. Further analysis revealed that TNF-α selectively upregulated Nav1.6 subtype of Na+ currents in RGCs. Similar to observations in retinas of rats with COH, intravitreal injection of TNF-α upregulated the expression of Nav1.6 proteins in both total cell and membrane components, which was reversed by the NF-κB inhibitor BAY 11-7082. Inhibition of TNFR1 blocked TNF-α-induced RGC apoptosis. CONCLUSIONS TNF-α/TNFR1 signaling induces RGC hyperexcitability by selectively upregulating Nav1.6 Na+ channels, thus contributing to RGC apoptosis in glaucoma.
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Affiliation(s)
- Shuo Cheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Hong-Ning Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Lin-Jie Xu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Bo Lei
- Institute of Neuroscience and Third Affiliated Hospital, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450003, China
| | - Xinghuai Sun
- Department of Ophthalmology at Eye & ENT Hospital, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, 200031, China.
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
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