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Millington-Ward S, Palfi A, Shortall C, Finnegan LK, Bargroff E, Post IJM, Maguire J, Irnaten M, O′Brien C, Kenna PF, Chadderton N, Farrar GJ. AAV-NDI1 Therapy Provides Significant Benefit to Murine and Cellular Models of Glaucoma. Int J Mol Sci 2024; 25:8876. [PMID: 39201561 PMCID: PMC11354491 DOI: 10.3390/ijms25168876] [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: 07/09/2024] [Revised: 08/02/2024] [Accepted: 08/04/2024] [Indexed: 09/02/2024] Open
Abstract
Glaucoma, a leading cause of blindness, is a multifactorial condition that leads to progressive loss of retinal ganglion cells (RGCs) and vision. Therapeutic interventions based on reducing ocular hypertension are not always successful. Emerging features of glaucoma include mitochondrial dysfunction and oxidative stress. In the current study, NDI1-based gene therapy, which improves mitochondrial function and reduces reactive oxygen species, was delivered intraocularly via an adeno-associated viral vector (AAV). This AAV-NDI1 therapy protected RGCs from cell death in treated (1552.4 ± 994.0 RGCs/mm2) versus control eyes (1184.4 ± 978.4 RGCs/mm2, p < 0.05) in aged DBA/2J mice, a murine model of glaucoma. The photonegative responses (PhNRs) of RGCs were also improved in treated (6.4 ± 3.3 µV) versus control eyes (5.0 ± 3.1 µV, p < 0.05) in these mice. AAV-NDI1 also provided benefits in glaucomatous human lamina cribrosa (LC) cells by significantly increasing basal and maximal oxygen consumption rates and ATP production in these cells. Similarly, NDI1 therapy significantly protected H2O2-insulted primary porcine LC cells from oxidative stress. This study highlights the potential utility of NDI1 therapies and the benefits of improving mitochondrial function in the treatment of glaucoma.
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Affiliation(s)
- Sophia Millington-Ward
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Arpad Palfi
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Ciara Shortall
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Laura K. Finnegan
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Ethan Bargroff
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Iris J. M. Post
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - John Maguire
- The Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin 2, D02XK51 Dublin, Ireland;
| | - Mustapha Irnaten
- UCD Clinical Research Centre, Mater Misericordiae University Hospital, Dublin 7, D07K201 Dublin, Ireland; (M.I.); (C.O.)
| | - Colm O′Brien
- UCD Clinical Research Centre, Mater Misericordiae University Hospital, Dublin 7, D07K201 Dublin, Ireland; (M.I.); (C.O.)
| | - Paul F. Kenna
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
- The Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin 2, D02XK51 Dublin, Ireland;
| | - Naomi Chadderton
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - G. Jane Farrar
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
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2
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Henry C, Wilcox M, Asirvatham AL. Forskolin-mediated cAMP activation upregulates TNF-α expression despite NF-κB downregulation in LPS-treated Schwann cells. PLoS One 2024; 19:e0302223. [PMID: 38625986 PMCID: PMC11020835 DOI: 10.1371/journal.pone.0302223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 03/30/2024] [Indexed: 04/18/2024] Open
Abstract
Although Schwann cells have been found to play a key role in inflammation and repair following nerve injury, the exact pathway is still unknown. To explore the mechanism by which Schwann cells exert their effects in the neuron microenvironment, we investigated two main inflammatory pathways: the NF-κB and cAMP pathways, and their downstream signaling molecules. In this study, lipopolysaccharide (LPS), a bacterial endotoxin, was used to activate the NF-κB pathway, and forskolin, a plant extract, was used to activate the cAMP pathway. The rat RT4-D6P2T Schwann cell line was treated with 0.1, 1, or 10 μg/mL of LPS, with or without 2 μM of forskolin, for 1, 3, 12, and 24 hours to determine the effects of elevated cAMP levels on LPS-treated cell viability. To investigate the effects of elevated cAMP levels on the expression of downstream signaling effector proteins, specifically NF-κB, TNF-α, AKAP95, and cyclin D3, as well as TNF-α secretion, RT4-D6P2T cells were incubated in the various treatment combinations for a 3-hour time period. Overall, results from the CellTiter-Glo viability assay revealed that forskolin increased viability in cells treated with smaller doses of LPS for 1 and 24 hours. For all time points, 10 μg/mL of LPS noticeably reduced viability regardless of forskolin treatment. Results from the Western blot analysis revealed that, at 10 μg/mL of LPS, forskolin upregulated the expression of TNF-α despite a downregulation of NF-κB, which was also accompanied by a decrease in TNF-α secretion. These results provide evidence that cAMP might regulate TNF-α expression through alternate pathways. Furthermore, although cAMP activation altered AKAP95 and cyclin D3 expression at different doses of LPS, there does not appear to be an association between the expression of AKAP95 or cyclin D3 and the expression of TNF-α. Exploring the possible interactions between cAMP, NF-κB, and other key inflammatory signaling pathways might reveal a potential therapeutic target for the treatment of nerve injury and inflammation.
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Affiliation(s)
- Caitlyn Henry
- Department of Biology, Misericordia University, Dallas, PA, United States of America
| | - Mackenzie Wilcox
- Department of Biology, Misericordia University, Dallas, PA, United States of America
| | - Angela L. Asirvatham
- Department of Biology, Misericordia University, Dallas, PA, United States of America
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3
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Hariani HN, Ghosh AK, Rosen SM, Tso HY, Kessinger C, Zhang C, Jones WK, Sappington RM, Mitchell CH, Stubbs EB, Rao VR, Kaja S. Lysyl oxidase like-1 deficiency in optic nerve head astrocytes elicits reactive astrocytosis and alters functional effects of astrocyte derived exosomes. Exp Eye Res 2024; 240:109813. [PMID: 38331016 PMCID: PMC10962968 DOI: 10.1016/j.exer.2024.109813] [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: 12/03/2023] [Revised: 01/27/2024] [Accepted: 01/29/2024] [Indexed: 02/10/2024]
Abstract
Glaucoma is a multifactorial progressive ocular pathology that manifests clinically with damage to the optic nerve (ON) and the retina, ultimately leading to blindness. The optic nerve head (ONH) shows the earliest signs of glaucoma pathology, and therefore, is an attractive target for drug discovery. The goal of this study was to elucidate the effects of reactive astrocytosis on the elastin metabolism pathway in primary rat optic nerve head astrocytes (ONHA), the primary glial cell type in the unmyelinated ONH. Following exposure to static equibiaxial mechanical strain, we observed prototypic molecular and biochemical signatures of reactive astrocytosis that were associated with a decrease in lysyl oxidase like 1 (Loxl1) expression and a concomitant decrease in elastin (Eln) gene expression. We subsequently investigated the role of Loxl1 in reactive astrocytosis by generating primary rat ONHA cultures with ∼50% decreased Loxl1 expression. Our results suggest that reduced Loxl1 expression is sufficient to elicit molecular signatures of elastinopathy in ONHA. Astrocyte derived exosomes (ADE) significantly increased the length of primary neurites of primary neurons in vitro. In contrast, ADE from Loxl1-deficient ONHA were deficient of trophic effects on neurite outgrowth in vitro, positing that Loxl1 dysfunction and the ensuing impaired elastin synthesis during reactive astrocytosis in the ONH may contribute to impaired neuron-glia signaling in glaucoma. Our data support a role of dysregulated Loxl1 function in eliciting reactive astrocytosis in glaucoma subtypes associated with increased IOP, even in the absence of genetic polymorphisms in LOXL1 typically associated with exfoliation glaucoma. This suggests the need for a paradigm shift toward considering lysyl oxidase activity and elastin metabolism and signaling as contributors to an altered secretome of the ONH that may lead to the progression of glaucomatous changes. Future research is needed to investigate cargo of exosomes in the context of reactive astrocytosis and identify the pathways leading to the observed transcriptome changes during reactive astrocytosis.
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Affiliation(s)
- Harsh N Hariani
- Graduate Program in Neuroscience, Loyola University Chicago, Maywood, IL, 60153, USA; Research Service, Edward Hines Jr Veterans Affairs Hospital, Hines, IL, 60141, USA
| | - Anita K Ghosh
- Graduate Program in Neuroscience, Loyola University Chicago, Maywood, IL, 60153, USA; Research Service, Edward Hines Jr Veterans Affairs Hospital, Hines, IL, 60141, USA
| | - Sasha M Rosen
- Department of Ophthalmology, Loyola University Chicago, Maywood, IL, 60153, USA; Department of Radiology, UC Davis Medical Center, Sacramento, CA, 95817, USA
| | - Huen-Yee Tso
- Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Cassidy Kessinger
- Graduate Program in Neuroscience, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Chongyu Zhang
- Graduate Program in Molecular Pharmacology and Therapeutics, Loyola University Chicago, Maywood, IL, 60153, USA
| | - W Keith Jones
- Department of Molecular Pharmacology and Neuroscience, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Rebecca M Sappington
- Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, NC, 27109, USA; Translational Eye and Vision Research Center, Wake Forest University School of Medicine, Winston-Salem, NC, 27109, USA
| | - Claire H Mitchell
- Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Evan B Stubbs
- Department of Ophthalmology, Loyola University Chicago, Maywood, IL, 60153, USA; Research Service, Edward Hines Jr Veterans Affairs Hospital, Hines, IL, 60141, USA
| | - Vidhya R Rao
- Department of Ophthalmology, Loyola University Chicago, Maywood, IL, 60153, USA; Research Service, Edward Hines Jr Veterans Affairs Hospital, Hines, IL, 60141, USA
| | - Simon Kaja
- Department of Ophthalmology, Loyola University Chicago, Maywood, IL, 60153, USA; Department of Molecular Pharmacology and Neuroscience, Loyola University Chicago, Maywood, IL, 60153, USA; Research Service, Edward Hines Jr Veterans Affairs Hospital, Hines, IL, 60141, USA.
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4
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Cameron EG, Nahmou M, Toth AB, Heo L, Tanasa B, Dalal R, Yan W, Nallagatla P, Xia X, Hay S, Knasel C, Stiles TL, Douglas C, Atkins M, Sun C, Ashouri M, Bian M, Chang KC, Russano K, Shah S, Woodworth MB, Galvao J, Nair RV, Kapiloff MS, Goldberg JL. A molecular switch for neuroprotective astrocyte reactivity. Nature 2024; 626:574-582. [PMID: 38086421 PMCID: PMC11384621 DOI: 10.1038/s41586-023-06935-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 12/05/2023] [Indexed: 01/27/2024]
Abstract
The intrinsic mechanisms that regulate neurotoxic versus neuroprotective astrocyte phenotypes and their effects on central nervous system degeneration and repair remain poorly understood. Here we show that injured white matter astrocytes differentiate into two distinct C3-positive and C3-negative reactive populations, previously simplified as neurotoxic (A1) and neuroprotective (A2)1,2, which can be further subdivided into unique subpopulations defined by proliferation and differential gene expression signatures. We find the balance of neurotoxic versus neuroprotective astrocytes is regulated by discrete pools of compartmented cyclic adenosine monophosphate derived from soluble adenylyl cyclase and show that proliferating neuroprotective astrocytes inhibit microglial activation and downstream neurotoxic astrocyte differentiation to promote retinal ganglion cell survival. Finally, we report a new, therapeutically tractable viral vector to specifically target optic nerve head astrocytes and show that raising nuclear or depleting cytoplasmic cyclic AMP in reactive astrocytes inhibits deleterious microglial or macrophage cell activation and promotes retinal ganglion cell survival after optic nerve injury. Thus, soluble adenylyl cyclase and compartmented, nuclear- and cytoplasmic-localized cyclic adenosine monophosphate in reactive astrocytes act as a molecular switch for neuroprotective astrocyte reactivity that can be targeted to inhibit microglial activation and neurotoxic astrocyte differentiation to therapeutic effect. These data expand on and define new reactive astrocyte subtypes and represent a step towards the development of gliotherapeutics for the treatment of glaucoma and other optic neuropathies.
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Affiliation(s)
- Evan G Cameron
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA.
| | - Michael Nahmou
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Anna B Toth
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Lyong Heo
- Stanford Center for Genomics and Personalized Medicine, Stanford University, Palo Alto, CA, USA
| | - Bogdan Tanasa
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Roopa Dalal
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Wenjun Yan
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Pratima Nallagatla
- Stanford Center for Genomics and Personalized Medicine, Stanford University, Palo Alto, CA, USA
| | - Xin Xia
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Sarah Hay
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Cara Knasel
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | | | | | - Melissa Atkins
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Catalina Sun
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Masoumeh Ashouri
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Minjuan Bian
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Kun-Che Chang
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Kristina Russano
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Sahil Shah
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
- University of California, San Diego, La Jolla, CA, USA
| | - Mollie B Woodworth
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Joana Galvao
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Ramesh V Nair
- Stanford Center for Genomics and Personalized Medicine, Stanford University, Palo Alto, CA, USA
| | - Michael S Kapiloff
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
- Department of Medicine and Stanford Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Jeffrey L Goldberg
- Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA.
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Shim MS, Dixon A, Nettesheim A, Perkumas KM, Stamer WD, Sun Y, Liton PB. Shear stress induces autophagy in Schlemm's canal cells via primary cilia-mediated SMAD2/3 signaling pathway. AUTOPHAGY REPORTS 2023; 2:2236519. [PMID: 37637387 PMCID: PMC10448710 DOI: 10.1080/27694127.2023.2236519] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 06/05/2023] [Accepted: 06/13/2023] [Indexed: 08/29/2023]
Abstract
The Schlemm's canal (SC) is a circular, lymphatic-like vessel located at the limbus of the eye that participates in the regulation of aqueous humor drainage to control intraocular pressure (IOP). Circumferential flow of aqueous humor within the SC lumen generates shear stress, which regulates SC cell behaviour. Using biochemical analysis and real-time live cell imaging techniques, we have investigated the activation of autophagy in SC cells by shear stress. We report, for the first time, the primary cilium (PC)-dependent activation of autophagy in SC cells in response to shear stress. Moreover, we identified PC-dependent shear stress-induced autophagy to be positively regulated by phosphorylation of SMAD2 in its linker and C-terminal regions. Additionally, SMAD2/3 signaling was found to transcriptionally activate LC3B, ATG5 and ATG7 in SC cells. Intriguingly, concomitant to SMAD2-dependent activation of autophagy, we also report here the activation of mTOR pathway, a classical autophagy inhibitor, in SC cells by shear stress. mTOR activation was found to also be dependent on the PC. Moreover, pharmacological inhibition of class I PI3K increased phosphorylation of SMAD2 at the linker and activated autophagy. Together, our data indicates an interplay between PI3K and SMAD2/3 signaling pathways in the regulation of PC-dependent shear stress-induced autophagy in SC cells.
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Affiliation(s)
- Myoung Sup Shim
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - Angela Dixon
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - April Nettesheim
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - Kristin M. Perkumas
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - W. Daniel Stamer
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| | - Yang Sun
- Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Paloma B. Liton
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
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Ju WK, Perkins GA, Kim KY, Bastola T, Choi WY, Choi SH. Glaucomatous optic neuropathy: Mitochondrial dynamics, dysfunction and protection in retinal ganglion cells. Prog Retin Eye Res 2023; 95:101136. [PMID: 36400670 DOI: 10.1016/j.preteyeres.2022.101136] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/04/2022] [Accepted: 11/03/2022] [Indexed: 11/18/2022]
Abstract
Glaucoma is a leading cause of irreversible blindness worldwide and is characterized by a slow, progressive, and multifactorial degeneration of retinal ganglion cells (RGCs) and their axons, resulting in vision loss. Despite its high prevalence in individuals 60 years of age and older, the causing factors contributing to glaucoma progression are currently not well characterized. Intraocular pressure (IOP) is the only proven treatable risk factor. However, lowering IOP is insufficient for preventing disease progression. One of the significant interests in glaucoma pathogenesis is understanding the structural and functional impairment of mitochondria in RGCs and their axons and synapses. Glaucomatous risk factors such as IOP elevation, aging, genetic variation, neuroinflammation, neurotrophic factor deprivation, and vascular dysregulation, are potential inducers for mitochondrial dysfunction in glaucoma. Because oxidative phosphorylation stress-mediated mitochondrial dysfunction is associated with structural and functional impairment of mitochondria in glaucomatous RGCs, understanding the underlying mechanisms and relationship between structural and functional alterations in mitochondria would be beneficial to developing mitochondria-related neuroprotection in RGCs and their axons and synapses against glaucomatous neurodegeneration. Here, we review the current studies focusing on mitochondrial dynamics-based structural and functional alterations in the mitochondria of glaucomatous RGCs and therapeutic strategies to protect RGCs against glaucomatous neurodegeneration.
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Affiliation(s)
- Won-Kyu Ju
- Hamilton Glaucoma Center and Viterbi Family Department of Ophthalmology and Shiley Eye Institute, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Guy A Perkins
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA
| | - Tonking Bastola
- Hamilton Glaucoma Center and Viterbi Family Department of Ophthalmology and Shiley Eye Institute, University of California San Diego, La Jolla, CA, 92093, USA
| | - Woo-Young Choi
- Hamilton Glaucoma Center and Viterbi Family Department of Ophthalmology and Shiley Eye Institute, University of California San Diego, La Jolla, CA, 92093, USA; Department of Plastic Surgery, College of Medicine, Chosun University, Gwang-ju, South Korea
| | - Soo-Ho Choi
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
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7
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Zhao GL, Zhou H, Guo YH, Zhong SM, Zhou H, Li F, Lei B, Wang Z, Miao Y. Modulation of Rac1/PAK1/connexin43-mediated ATP release from astrocytes contributes to retinal ganglion cell survival in experimental glaucoma. Glia 2023; 71:1502-1521. [PMID: 36794533 DOI: 10.1002/glia.24354] [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: 07/01/2022] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 02/17/2023]
Abstract
Connexin43 (Cx43) is a major gap junction protein in glial cells. Mutations have been found in the gap-junction alpha 1 gene encoding Cx43 in glaucomatous human retinas, suggestive of the involvement of Cx43 in the pathogenesis of glaucoma. However, how Cx43 is involved in glaucoma is still unknown. We showed that increased intraocular pressure in a glaucoma mouse model of chronic ocular hypertension (COH) downregulated Cx43, which was mainly expressed in retinal astrocytes. Astrocytes in the optic nerve head where they gather and wrap the axons (optic nerve) of retinal ganglion cells (RGCs) were activated earlier than neurons in COH retinas and the alterations in astrocytes plasticity in the optic nerve caused a reduction in Cx43 expression. A time course showed that reductions of Cx43 expression were correlated with the activation of Rac1, a member of the Rho family. Co-immunoprecipitation assays showed that active Rac1, or the downstream signaling effector PAK1, negatively regulated Cx43 expression, Cx43 hemichannel opening and astrocyte activation. Pharmacological inhibition of Rac1 stimulated Cx43 hemichannel opening and ATP release, and astrocytes were identified to be one of the main sources of ATP. Furthermore, conditional knockout of Rac1 in astrocytes enhanced Cx43 expression and ATP release, and promoted RGC survival by upregulating the adenosine A3 receptor in RGCs. Our study provides new insight into the relationship between Cx43 and glaucoma, and suggests that regulating the interaction between astrocytes and RGCs via the Rac1/PAK1/Cx43/ATP pathway may be used as part of a therapeutic strategy for managing glaucoma.
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Affiliation(s)
- Guo-Li Zhao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Hong Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yun-Hui Guo
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Shu-Min Zhong
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Han Zhou
- 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
| | - 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, China
| | - Zhongfeng Wang
- 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
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8
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The Intertwined Roles of Oxidative Stress and Endoplasmic Reticulum Stress in Glaucoma. Antioxidants (Basel) 2022; 11:antiox11050886. [PMID: 35624748 PMCID: PMC9137739 DOI: 10.3390/antiox11050886] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 04/26/2022] [Accepted: 04/28/2022] [Indexed: 02/04/2023] Open
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide, and the burden of the disease continues to grow as the global population ages. Currently, the only treatment option is to lower intraocular pressure. A better understanding of glaucoma pathogenesis will help us to develop novel therapeutic options. Oxidative stress has been implicated in the pathogenesis of many diseases. Oxidative stress occurs when there is an imbalance in redox homeostasis, with reactive oxygen species producing processes overcoming anti-oxidant defensive processes. Oxidative stress works in a synergistic fashion with endoplasmic reticulum stress, to drive glaucomatous damage to trabecular meshwork, retinal ganglion cells and the optic nerve head. We discuss the oxidative stress and endoplasmic reticulum stress pathways and their connections including their key intermediary, calcium. We highlight therapeutic options aimed at disrupting these pathways and discuss their potential role in glaucoma treatment.
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Rasmussen M, Zhou J, Schwede F, Ekström P. Enhanced cGMP Interactor Rap Guanine Exchange Factor 4 (EPAC2) Expression and Activity in Degenerating Photoreceptors: A Neuroprotective Response? Int J Mol Sci 2022; 23:ijms23094619. [PMID: 35563009 PMCID: PMC9103912 DOI: 10.3390/ijms23094619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/17/2022] [Accepted: 04/19/2022] [Indexed: 11/25/2022] Open
Abstract
The disease retinitis pigmentosa (RP) leads to photoreceptor degeneration by a yet undefined mechanism(s). In several RP mouse models (i.e., rd mice), a high cyclic GMP (cGMP) level within photoreceptors is detected, suggesting that cGMP plays a role in degeneration. The rap guanine exchange factor 4 (EPAC2) is activated by cyclic AMP (cAMP) and is an accepted cGMP-interacting protein. It is unclear whether and how cGMP interacts with EPAC2 in degenerating photoreceptors; we therefore investigated EPAC2 expression and interactions with cGMP and cAMP in retinas of the rd1 and rd10 models for retinal degeneration. EPAC2 expression in the photoreceptor layer increased significantly during rd1 and rd10 degeneration, and an increase in EPAC2 interactions with cGMP but not cAMP in the rd1 was also seen via a proximity ligation assay on histological sections. Retinal explant cultures revealed that pharmacological inhibition of the EPAC2 activity reduced the photoreceptor layer thickness in the rd10 retina, suggesting that EPAC2 inhibition promotes degeneration. Taken together, our results support the hypothesis that high degeneration-related cGMP leads to increased EPAC2 and cGMP interactions, inhibiting EPAC2. By inference, EPAC2 could have neuroprotective capacities that may be exploited in the future.
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Affiliation(s)
- Michel Rasmussen
- Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, 22184 Lund, Sweden; (J.Z.); (P.E.)
- Correspondence:
| | - Jiaming Zhou
- Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, 22184 Lund, Sweden; (J.Z.); (P.E.)
| | - Frank Schwede
- BIOLOG Life Science Institute GmbH & Co. KG, 28199 Bremen, Germany;
| | - Per Ekström
- Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, 22184 Lund, Sweden; (J.Z.); (P.E.)
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10
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Nangia V, O'Connell J, Chopra K, Qing Y, Reppert C, Chai CM, Bhasiin K, Colodner KJ. Genetic reduction of tyramine β hydroxylase suppresses Tau toxicity in a Drosophila model of tauopathy. Neurosci Lett 2021; 755:135937. [PMID: 33910059 DOI: 10.1016/j.neulet.2021.135937] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/23/2021] [Accepted: 04/23/2021] [Indexed: 01/21/2023]
Abstract
Tauopathies are a class of neurodegenerative diseases characterized by the abnormal phosphorylation and accumulation of the microtubule-associated protein, Tau. These diseases are associated with degeneration and dysfunction of the noradrenergic system, a critical regulator of memory, locomotion, and the fight or flight response. Though Tau pathology accumulates early in noradrenergic neurons, the relationship between noradrenaline signaling and tauopathy pathogenesis remains unclear. The fruit fly, Drosophila melanogaster, is a valuable model organism commonly used to investigate factors that promote Tau-mediated degeneration. Moreover, Drosophila contain the biogenic amine, octopamine, which is the functional homolog to noradrenaline. Using a Drosophila model of tauopathy, we conducted a candidate modifier screen targeting tyramine β hydroxylase (tβh), the enzyme that controls the production of octopamine in the fly, to determine if levels of this enzyme modulate Tau-induced degeneration in the fly eye. We found that genetic reduction of tβh suppresses Tau toxicity, independent of Tau phosphorylation. These findings show that reduction of tβh, a critical enzyme in the octopaminergic pathway, suppresses Tau pathogenicity and establishes an interaction that can be further utilized to determine the relationship between noradrenergic-like signaling and Tau toxicity in Drosophila.
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Affiliation(s)
- Varuna Nangia
- Program in Neuroscience & Behavior, Mount Holyoke College, South Hadley, MA, USA
| | - Julia O'Connell
- Program in Neuroscience & Behavior, Mount Holyoke College, South Hadley, MA, USA
| | - Kusha Chopra
- Program in Neuroscience & Behavior, Mount Holyoke College, South Hadley, MA, USA
| | - Yaling Qing
- Program in Neuroscience & Behavior, Mount Holyoke College, South Hadley, MA, USA
| | - Camille Reppert
- Program in Neuroscience & Behavior, Mount Holyoke College, South Hadley, MA, USA
| | - Cynthia M Chai
- Program in Neuroscience & Behavior, Mount Holyoke College, South Hadley, MA, USA
| | - Kesshni Bhasiin
- Program in Neuroscience & Behavior, Mount Holyoke College, South Hadley, MA, USA
| | - Kenneth J Colodner
- Program in Neuroscience & Behavior, Mount Holyoke College, South Hadley, MA, USA.
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11
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Samelska K, Zaleska-Żmijewska A, Bałan B, Grąbczewski A, Szaflik JP, Kubiak AJ, Skopiński P. Immunological and molecular basics of the primary open angle glaucoma pathomechanism. Cent Eur J Immunol 2021; 46:111-117. [PMID: 33897292 PMCID: PMC8056342 DOI: 10.5114/ceji.2021.104328] [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: 08/03/2020] [Accepted: 10/26/2020] [Indexed: 02/07/2023] Open
Abstract
Glaucoma is a degenerative process of the optic nerve. Increased intraocular pressure is believed to be the main factor leading to the glaucomatous damage. The in vitro and in vivo animal glaucoma research models provide insight into the molecular changes in the retina in response to the injury factor. The damage is a complex process incorporating molecular and immunological changes. Such changes involve NF kB activity and complement activation. The processes affect the human antigen, JNK, MAPK, p53, MT2 and DBA/2J molecular pathways, activate the autophagy processes and compromise neuroprotective mechanisms. Activation and inhibition of immunological responses contribute to cell injury. The immunological mechanisms of glaucomatous degeneration include glial response, the complement, tumor necrosis factor α (TNF-α) pathways and toll-like receptors athways. Oxidative stress and excitotoxicity are factors contributing to cell death in glaucoma. The authors present an up-to-date review of the mechanisms involved and update on research focusing on a possible innovative glaucoma treatment.
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Affiliation(s)
- Katarzyna Samelska
- SPKSO Ophthalmic University Hospital, Warsaw, Poland
- Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland
| | - Anna Zaleska-Żmijewska
- SPKSO Ophthalmic University Hospital, Warsaw, Poland
- Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland
| | - Barbara Bałan
- Department of Immunology Biochemistry and Nutrition, Medical University of Warsaw, Warsaw, Poland
| | | | - Jacek Paweł Szaflik
- SPKSO Ophthalmic University Hospital, Warsaw, Poland
- Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland
| | | | - Piotr Skopiński
- SPKSO Ophthalmic University Hospital, Warsaw, Poland
- Department of Histology and Embryology, Medical University of Warsaw, Warsaw, Poland
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12
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Mohiuddin MS, Himeno T, Yamada Y, Morishita Y, Kondo M, Tsunekawa S, Kato Y, Nakamura J, Kamiya H. Glucagon Prevents Cytotoxicity Induced by Methylglyoxal in a Rat Neuronal Cell Line Model. Biomolecules 2021; 11:biom11020287. [PMID: 33672050 PMCID: PMC7919475 DOI: 10.3390/biom11020287] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 12/14/2022] Open
Abstract
Although diabetic polyneuropathy (DPN) is a frequent diabetic complication, no effective therapeutic approach has been established. Glucagon is a crucial hormone for glucose homeostasis but has pleiotropic effects, including neuroprotective effects in the central nervous system. However, the importance of glucagon in the peripheral nervous system (PNS) has not been clarified. Here, we hypothesized that glucagon might have a neuroprotective function in the PNS. The immortalized rat dorsal root ganglion (DRG) neuronal cell line 50B11 was treated with methylglyoxal (MG) to mimic an in vitro DPN model. The cells were cultured with or without glucagon or MG. Neurotoxicity, survival, apoptosis, neurite projection, cyclic adenosine monophosphate (cAMP), and protein kinase A (PKA) were examined. Glucagon had no cytotoxicity and rescued the cells from neurotoxicity. Cell survival was increased by glucagon. The ratio of apoptotic cells, which was increased by MG, was reduced by glucagon. Neurite outgrowth was accelerated in glucagon-treated cells. Cyclic AMP and PKA accumulated in the cells after glucagon stimulation. In conclusion, glucagon protected the DRG neuronal cells from MG-induced cellular stress. The cAMP/PKA pathway may have significant roles in those protective effects of glucagon. Glucagon may be a potential target for the treatment of DPN.
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13
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Kim KY, Ju WK. cAMP/PKA pathway and mitochondrial protection in oxidative stress-induced optic nerve head astrocytes. Neural Regen Res 2021; 16:108-109. [PMID: 32788457 PMCID: PMC7818876 DOI: 10.4103/1673-5374.286962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Keun-Young Kim
- National Center for Microscopy and Imaging Research and Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Won-Kyu Ju
- Hamilton Glaucoma Center and Shiley Eye Institute, The Viterbi Family Department of Ophthalmology, University of California, San Diego, La Jolla, CA, USA
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14
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Wang Y, Kang Y, Qi C, Zhang T, Zhao H, Ji X, Yan W, Huang Y, Cui R, Zhang G, Shi G. Pentoxifylline enhances antioxidative capability and promotes mitochondrial biogenesis for improving age-related behavioral deficits. Aging (Albany NY) 2020; 12:25487-25504. [PMID: 33231568 PMCID: PMC7803534 DOI: 10.18632/aging.104155] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 09/09/2020] [Indexed: 12/15/2022]
Abstract
Pentoxifylline (PTX) is a non-specific phosphodiesterase inhibitor with pleiotropic effects that is routinely used to treat peripheral vascular disease. In this study, we tested whether PTX could also counteract the detrimental effects of aging in the brain. To accomplish that, we treated aged rats with PTX and measured resulting behavioral alterations as well as changes in dopaminergic neurochemical levels, oxidative balance markers, mitochondrial function, nuclear factor erythroid 2-related factor 2 (Nrf2), peroxisome proliferator activated receptor-gamma coactivator 1-alpha (PGC-1α) and downstream gene expression, and cyclic adenosine monophosphate (cAMP) content in the brain. The results demonstrated that PTX improved motor and cognitive deficits and restored levels of dopamine and its metabolites in the brains of aged rats. PTX also reduced malondialdehyde levels and increased the GSH/GSSG ratio, mitochondrial ATP, nuclear Nrf2, and cAMP levels, and upregulated PGC-1α, nuclear respiratory factor 1, and mitochondrial transcription factor A expression in the substantia nigra and hippocampus of aged rats. Thus, increased nuclear Nrf2 levels and upregulation of PGC-1α, which enhance antioxidative capability and promote mitochondrial biogenesis, may be responsible for PTX-induced amelioration of behavioral deficits in aged rats.
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Affiliation(s)
- Yu Wang
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Yunxiao Kang
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Chunxiao Qi
- Department of Anatomy, Hebei Medical University, Shijiazhuang 050017, China
| | - Tianyun Zhang
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Hui Zhao
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Xiaoming Ji
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Wensheng Yan
- Department of Sports Medicine, Hebei Sport University, Shijiazhuang 050017, China
| | - Yuanxiang Huang
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Rui Cui
- Department of Anatomy, Hebei Medical University, Shijiazhuang 050017, China
| | - Guoliang Zhang
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China.,Department of Anatomy, Hebei Medical University, Shijiazhuang 050017, China
| | - Geming Shi
- Department of Neurobiology, Hebei Medical University, Shijiazhuang 050017, China.,Neuroscience Research Center, Hebei Medical University, Shijiazhuang 050017, China.,Hebei Key Laboratory of Neurodegenerative Disease Mechanism, Hebei Medical University, Shijiazhuang 050017, China
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15
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Rh-CSF1 Attenuates Oxidative Stress and Neuronal Apoptosis via the CSF1R/PLCG2/PKA/UCP2 Signaling Pathway in a Rat Model of Neonatal HIE. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:6801587. [PMID: 33101590 PMCID: PMC7568161 DOI: 10.1155/2020/6801587] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022]
Abstract
Oxidative stress (OS) and neuronal apoptosis are major pathological processes after hypoxic-ischemic encephalopathy (HIE). Colony stimulating factor 1 (CSF1), binding to CSF1 receptor (CSF1R), has been shown to reduce neuronal loss after hypoxic-ischemia- (HI-) induced brain injury. In the present study, we hypothesized that CSF1 could alleviate OS-induced neuronal degeneration and apoptosis through the CSF1R/PLCG2/PKA/UCP2 signaling pathway in a rat model of HI. A total of 127 ten-day old Sprague Dawley rat pups were used. HI was induced by right common carotid artery ligation with subsequent exposure to hypoxia for 2.5 h. Exogenous recombinant human CSF1 (rh-CSF1) was administered intranasally at 1 h and 24 h after HI. The CSF1R inhibitor, BLZ945, or phospholipase C-gamma 2 (PLCG2) inhibitor, U73122, was injected intraperitoneally at 1 h before HI induction. Brain infarct volume measurement, cliff avoidance test, righting reflex test, double immunofluorescence staining, western blot assessment, 8-OHdG and MitoSOX staining, Fluoro-Jade C staining, and TUNEL staining were used. Our results indicated that the expressions of endogenous CSF1, CSF1R, p-CSF1R, p-PLCG2, p-PKA, and uncoupling protein2 (UCP2) were increased after HI. CSF1 and CSF1R were expressed in neurons and astrocytes. Rh-CSF1 treatment significantly attenuated neurological deficits, infarct volume, OS, neuronal apoptosis, and degeneration at 48 h after HI. Moreover, activation of CSF1R by rh-CSF1 significantly increased the brain tissue expressions of p-PLCG2, p-PKA, UCP2, and Bcl2/Bax ratio, but reduced the expression of cleaved caspase-3. The neuroprotective effects of rh-CSF1 were abolished by BLZ945 or U73122. These results suggested that rh-CSF1 treatment attenuated OS-induced neuronal degeneration and apoptosis after HI, at least in part, through the CSF1R/PLCG2/PKA/UCP2 signaling pathway. Rh-CSF1 may serve as therapeutic strategy against brain damage in patients with HIE.
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16
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Kim HN, Seo BR, Kim H, Koh JY. Cilostazol restores autophagy flux in bafilomycin A1-treated, cultured cortical astrocytes through lysosomal reacidification: roles of PKA, zinc and metallothionein 3. Sci Rep 2020; 10:9175. [PMID: 32514052 PMCID: PMC7280249 DOI: 10.1038/s41598-020-66292-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 05/18/2020] [Indexed: 12/21/2022] Open
Abstract
Cilostazol, a phosphodiesterase 3 inhibitor, reduces the amyloid-beta (Aβ) burden in mouse models of Alzheimer disease by as yet unidentified mechanisms. In the present study, we examined the possibility that cilostazol ameliorates lysosomal dysfunction. Astrocytes treated with bafilomycin A1 (BafA1) exhibited markedly reduced DND-189 and acridine orange (AO) fluorescence, indicating reduced lysosomal acidity. In both cases, BafA1-induced alkalization was reversed by addition of cilostazol, dibutyryl cAMP or forskolin. All three agents significantly increased free zinc levels in lysosomes, and addition of the zinc chelator TPEN abrogated lysosomal reacidification. These treatments did not raise free zinc levels or reverse BafA1-mediated lysosomal alkalization in metallothionein 3 (Mt3)-null astrocytes, indicating that the increases in zinc in astrocytes were derived mainly from Mt3. Lastly, in FITC-Aβ-treated astrocytes, cilostazol reversed lysosomal alkalization, increased cathepsin D activity, and reduced Aβ accumulation in astrocytes. Cilostazol also reduced mHtt aggregate formation in GFP-mHttQ74–expressing astrocytes. Collectively, our results present the novel finding that cAMP/PKA can overcome the v-ATPase blocking effect of BafA1 in a zinc- and Mt3-dependent manner.
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Affiliation(s)
- Ha Na Kim
- Neural Injury Lab, Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea
| | - Bo-Ra Seo
- Neural Injury Lab, Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea
| | - Hyunjin Kim
- Department of Neurology, University of Ulsan College of Medicine, Seoul, Korea; Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jae-Young Koh
- Department of Neurology, University of Ulsan College of Medicine, Seoul, Korea; Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. .,Neural Injury Lab, Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea.
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17
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Falero-Perez J, Sheibani N, Sorenson CM. Bim expression modulates the pro-inflammatory phenotype of retinal astroglial cells. PLoS One 2020; 15:e0232779. [PMID: 32365083 PMCID: PMC7197808 DOI: 10.1371/journal.pone.0232779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 04/21/2020] [Indexed: 01/01/2023] Open
Abstract
Apoptosis of neurovascular cells, including astroglial cells, contributes to the pathogenesis of diseases in which neurovascular disruption plays a central role. Bim is a pro-apoptotic protein that modulates not only apoptosis but also various cellular functions such as migration and extracellular matrix protein expression. Astroglial cells act as an intermediary between neural and vascular cells facilitating retinal vascular development and remodeling while maintaining normal vascular function and neuronal integrity. We previously showed that Bim deficient (Bim -/-) mice were protected from hyperoxia mediated vessel obliteration and ischemia-mediated retinal neovascularization. However, the underlying mechanisms and more specifically the role Bim expression in astroglial cells play remains elusive. Here, using retinal astroglial cells prepared from wild-type and Bim -/- mice, we determined the impact of Bim expression in retinal astroglial cell function. We showed that astroglial cells lacking Bim expression demonstrate increased VEGF expression and altered matricellular protein production including increased expression of thrombospondin-2 (TSP2), osteopontin and SPARC. Bim deficient astroglial cells also exhibited altered proliferation, migration, adhesion to various extracellular matrix proteins and increased expression of inflammatory mediators. Thus, our data emphasizes the importance of Bim expression in retinal astroglia cell autonomous regulatory mechanisms, which could influence neurovascular function.
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Affiliation(s)
- Juliana Falero-Perez
- Departments of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
| | - Nader Sheibani
- Departments of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
- Department of Biomedical Engineering, University of Wisconsin, Madison, WI, United States of America
| | - Christine M. Sorenson
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States of America
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18
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Edwards G, Perkins GA, Kim KY, Kong Y, Lee Y, Choi SH, Liu Y, Skowronska-Krawczyk D, Weinreb RN, Zangwill L, Strack S, Ju WK. Loss of AKAP1 triggers Drp1 dephosphorylation-mediated mitochondrial fission and loss in retinal ganglion cells. Cell Death Dis 2020; 11:254. [PMID: 32312949 PMCID: PMC7170863 DOI: 10.1038/s41419-020-2456-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/14/2022]
Abstract
Impairment of mitochondrial structure and function is strongly linked to glaucoma pathogenesis. Despite the widely appreciated disease relevance of mitochondrial dysfunction and loss, the molecular mechanisms underlying mitochondrial fragmentation and metabolic stress in glaucoma are poorly understood. We demonstrate here that glaucomatous retinal ganglion cells (RGCs) show loss of A-kinase anchoring protein 1 (AKAP1), activation of calcineurin (CaN) and reduction of dynamin-related protein 1 (Drp1) phosphorylation at serine 637 (Ser637). These findings suggest that AKAP1-mediated phosphorylation of Drp1 at Ser637 has a critical role in RGC survival in glaucomatous neurodegeneration. Male mice lacking AKAP1 show increases in CaN and total Drp1 levels, as well as a decrease in Drp1 phosphorylation at Ser637 in the retina. Ultrastructural analysis of mitochondria shows that loss of AKAP1 triggers mitochondrial fragmentation and loss, as well as mitophagosome formation in RGCs. Loss of AKAP1 deregulates oxidative phosphorylation (OXPHOS) complexes (Cxs) by increasing CxII and decreasing CxIII-V, leading to metabolic and oxidative stress. Also, loss of AKAP1 decreases Akt phosphorylation at Serine 473 (Ser473) and threonine 308 (Thr308) and activates the Bim/Bax signaling pathway in the retina. These results suggest that loss of AKAP1 has a critical role in RGC dysfunction by decreasing Drp1 phosphorylation at Ser637, deregulating OXPHOS, decreasing Akt phosphorylation at Ser473 and Thr308, and activating the Bim/Bax pathway in glaucomatous neurodegeneration. Thus, we propose that overexpression of AKAP1 or modulation of Drp1 phosphorylation at Ser637 are potential therapeutic strategies for neuroprotective intervention in glaucoma and other mitochondria-related optic neuropathies.
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Affiliation(s)
- Genea Edwards
- Hamilton Glaucoma Center and Shiley Eye Center, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Guy A Perkins
- National Center for Microscopy and Imaging Research and Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research and Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - YeEun Kong
- Hamilton Glaucoma Center and Shiley Eye Center, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Yonghoon Lee
- Hamilton Glaucoma Center and Shiley Eye Center, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Soo-Ho Choi
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Yujia Liu
- Department of Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA
| | - Dorota Skowronska-Krawczyk
- Hamilton Glaucoma Center and Shiley Eye Center, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Robert N Weinreb
- Hamilton Glaucoma Center and Shiley Eye Center, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Linda Zangwill
- Hamilton Glaucoma Center and Shiley Eye Center, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Stefan Strack
- Department of Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA
| | - Won-Kyu Ju
- Hamilton Glaucoma Center and Shiley Eye Center, The Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.
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19
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Ghosh AK, Rao VR, Wisniewski VJ, Zigrossi AD, Floss J, Koulen P, Stubbs EB, Kaja S. Differential Activation of Glioprotective Intracellular Signaling Pathways in Primary Optic Nerve Head Astrocytes after Treatment with Different Classes of Antioxidants. Antioxidants (Basel) 2020; 9:antiox9040324. [PMID: 32316287 PMCID: PMC7222350 DOI: 10.3390/antiox9040324] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 02/03/2023] Open
Abstract
Optic nerve head astrocytes are the specialized glia cells that provide structural and trophic support to the optic nerve head. In response to cellular injury, optic nerve head astrocytes undergo reactive astrocytosis, the process of cellular activation associated with cytoskeletal remodeling, increases in the rate of proliferation and motility, and the generation of Reactive Oxygen Species. Antioxidant intervention has previously been proposed as a therapeutic approach for glaucomatous optic neuropathy, however, little is known regarding the response of optic nerve head astrocytes to antioxidants under physiological versus pathological conditions. The goal of this study was to determine the effects of three different antioxidants, manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin (Mn-TM-2-PyP), resveratrol and xanthohumol in primary optic nerve head astrocytes. Effects on the expression of the master regulator nuclear factor erythroid 2-related factor 2 (Nrf2), the antioxidant enzyme, manganese-dependent superoxide dismutase 2 (SOD2), and the pro-oxidant enzyme, nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), were determined by quantitative immunoblotting. Furthermore, efficacy in preventing chemically and reactive astrocytosis-induced increases in cellular oxidative stress was quantified using cell viability assays. The results were compared to the effects of the prototypic antioxidant, Trolox. Antioxidants elicited highly differential changes in the expression levels of Nrf2, SOD2, and NOX4. Notably, Mn-TM-2-PyP increased SOD2 expression eight-fold, while resveratrol increased Nrf2 expression three-fold. In contrast, xanthohumol exerted no statistically significant changes in expression levels. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) uptake and lactate dehydrogenase (LDH) release assays were performed to assess cell viability after chemically and reactive astrocytosis-induced oxidative stress. Mn-TM-2-PyP exerted the most potent glioprotection by fully preventing the loss of cell viability, whereas resveratrol and xanthohumol partially restored cell viability. Our data provide the first evidence for a well-developed antioxidant defense system in optic nerve head astrocytes, which can be pharmacologically targeted by different classes of antioxidants.
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Affiliation(s)
- Anita K. Ghosh
- Graduate Program in Biochemistry and Molecular Biology, Loyola University Chicago, Health Sciences Campus, Maywood, IL 60153, USA
- Research Service, Edward Hines Jr. Veterans Administration Hospital, Hines, IL 60141, USA
| | - Vidhya R. Rao
- Research Service, Edward Hines Jr. Veterans Administration Hospital, Hines, IL 60141, USA
- Department of Ophthalmology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
| | - Victoria J. Wisniewski
- Department of Molecular Pharmacology and Neuroscience, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
| | - Alexandra D. Zigrossi
- Department of Ophthalmology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
| | - Jamie Floss
- Department of Molecular Pharmacology and Neuroscience, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
| | - Peter Koulen
- Department of Ophthalmology and Biomedical Sciences, Vision Research Center, University of Missouri—Kansas City, School of Medicine, Vision Research Center, Kansas City, MO 64108, USA
| | - Evan B Stubbs
- Research Service, Edward Hines Jr. Veterans Administration Hospital, Hines, IL 60141, USA
- Department of Ophthalmology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
| | - Simon Kaja
- Research Service, Edward Hines Jr. Veterans Administration Hospital, Hines, IL 60141, USA
- Department of Ophthalmology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
- Department of Molecular Pharmacology and Neuroscience, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
- Correspondence: ; Tel.: +1-708-216-9223
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Inhibition of cAMP/PKA Pathway Protects Optic Nerve Head Astrocytes against Oxidative Stress by Akt/Bax Phosphorylation-Mediated Mfn1/2 Oligomerization. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:8060962. [PMID: 31781352 PMCID: PMC6875302 DOI: 10.1155/2019/8060962] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 09/18/2019] [Indexed: 11/19/2022]
Abstract
Glaucoma is characterized by a progressive optic nerve degeneration and retinal ganglion cell loss, but the underlying biological basis for the accompanying neurodegeneration is not known. Accumulating evidence indicates that structural and functional abnormalities of astrocytes within the optic nerve head (ONH) have a role in glaucomatous neurodegeneration. Here, we investigate the impact of activation of cyclic adenosine 3′,5′-monophosphate (cAMP)/protein kinase A (PKA) pathway on mitochondrial dynamics of ONH astrocytes exposed to oxidative stress. ONH astrocytes showed a significant loss of astrocytic processes in the glial lamina of glaucomatous DBA/2J mice, accompanied by basement membrane thickening and collagen deposition in blood vessels and axonal degeneration. Serial block-face scanning electron microscopy data analysis demonstrated that numbers of total and branched mitochondria were significantly increased in ONH astrocytes, while mitochondrial length and volume density were significantly decreased. We found that hydrogen peroxide- (H2O2-) induced oxidative stress compromised not only mitochondrial bioenergetics by reducing the basal and maximal respiration but also balance of mitochondrial dynamics by decreasing dynamin-related protein 1 (Drp1) protein expression in rat ONH astrocytes. In contrast, elevated cAMP by dibutyryl-cAMP (dbcAMP) or isobutylmethylxanthine treatment significantly increased Drp1 protein expression in ONH astrocytes. Elevated cAMP exacerbated the impairment of mitochondrial dynamics and reduction of cell viability to oxidative stress in ONH astrocytes by decreasing optic atrophy type 1 (OPA1), and mitofusin (Mfn)1/2 protein expression. Following combined treatment with H2O2 and dbcAMP, PKA inhibition restored mitochondrial dynamics by increasing mitochondrial length and decreasing mitochondrial number, and this promoted cell viability in ONH astrocytes. Also, PKA inhibition significantly promoted Akt/Bax phosphorylation and Mfn1/2 oligomerization in ONH astrocytes. These results suggest that modulation of the cAMP/PKA signaling pathway may have therapeutic potential by activating Akt/Bax phosphorylation and promoting Mfn1/2 oligomerization in glaucomatous ONH astrocytes.
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The protective effects of mangiferin on metabolic and organs functions in the adolescent rat model of alcohol abuse. J Funct Foods 2018. [DOI: 10.1016/j.jff.2018.04.056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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