1
|
Covey DF, Evers AS, Izumi Y, Maguire JL, Mennerick SJ, Zorumski CF. Neurosteroid enantiomers as potentially novel neurotherapeutics. Neurosci Biobehav Rev 2023; 149:105191. [PMID: 37085023 PMCID: PMC10750765 DOI: 10.1016/j.neubiorev.2023.105191] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 04/23/2023]
Abstract
Endogenous neurosteroids and synthetic neuroactive steroids (NAS) are important targets for therapeutic development in neuropsychiatric disorders. These steroids modulate major signaling systems in the brain and intracellular processes including inflammation, cellular stress and autophagy. In this review, we describe studies performed using unnatural enantiomers of key neurosteroids, which are physiochemically identical to their natural counterparts except for rotation of polarized light. These studies led to insights in how NAS interact with receptors, ion channels and intracellular sites of action. Certain effects of NAS show high enantioselectivity, consistent with actions in chiral environments and likely direct interactions with signaling proteins. Other effects show no enantioselectivity and even reverse enantioselectivity. The spectrum of effects of NAS enantiomers raises the possibility that these agents, once considered only as tools for preclinical studies, have therapeutic potential that complements and in some cases may exceed their natural counterparts. Here we review studies of NAS enantiomers from the perspective of their potential development as novel neurotherapeutics.
Collapse
Affiliation(s)
- Douglas F Covey
- Departments of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA; Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA; Anesthesiology Washington University School of Medicine, St. Louis, MO, USA; The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - Alex S Evers
- Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA; Anesthesiology Washington University School of Medicine, St. Louis, MO, USA; The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - Yukitoshi Izumi
- Departments of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA; The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - Jamie L Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Steven J Mennerick
- Departments of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA; The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA
| | - Charles F Zorumski
- Departments of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA; The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St. Louis, MO, USA.
| |
Collapse
|
2
|
Comitato A, Subramanian P, Turchiano G, Montanari M, Becerra SP, Marigo V. Pigment epithelium-derived factor hinders photoreceptor cell death by reducing intracellular calcium in the degenerating retina. Cell Death Dis 2018; 9:560. [PMID: 29752430 PMCID: PMC5948223 DOI: 10.1038/s41419-018-0613-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 04/16/2018] [Accepted: 04/19/2018] [Indexed: 12/21/2022]
Abstract
Calcium ions play a critical role in neuronal cell death. Pigment epithelium-derived factor (PEDF) is a promising neuroprotective protein for photoreceptor cells but the mechanisms mediating its effects against retinal degeneration are still not well characterized. We addressed this question in the rd1 degenerating mouse retina that bears a mutation in the Pde6b gene encoding one subunit of the phosphodiesterase enzyme. Loss of phosphodiesterase activity in rod photoreceptor cells increases cyclic guanosine monophosphate (cGMP) levels leading to a rise in intracellular calcium. Short-term treatments with recombinant human PEDF protein decreased intracellular calcium in photoreceptors in vivo. Taking advantage of calcium pump blockers, we defined that PEDF signaling acts on PMCA calcium pumps to lower intracellular calcium. PEDF restrained cell death pathways activated by high calcium levels and engaging calpains, BAX and AIF. The neurotrophic effects were mediated by the PEDF receptor (PEDF-R), encoded by the PNPLA2 gene. Finally, peptides containing the neurotrophic domain of PEDF targeted these same cell death pathways in vivo. The findings reveal rescue from death of degenerating photoreceptor cells by a PEDF-mediated preservation of intracellular calcium homeostasis.
Collapse
Affiliation(s)
- Antonella Comitato
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Preeti Subramanian
- Section of Protein Structure and Function, Laboratory of Retinal Cell and Molecular Biology, NEI, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Giandomenico Turchiano
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.,Institute for Cell and Gene Therapy & Center for Chronic Immunodeficiency - University of Freiburg, Freiburg, Germany
| | - Monica Montanari
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - S Patricia Becerra
- Section of Protein Structure and Function, Laboratory of Retinal Cell and Molecular Biology, NEI, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Valeria Marigo
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy. .,Center for Neuroscience and Neurotechnology, University of Modena and Reggio Emilia, Modena, Italy.
| |
Collapse
|
3
|
LaVail MM, Nishikawa S, Steinberg RH, Naash MI, Duncan JL, Trautmann N, Matthes MT, Yasumura D, Lau-Villacorta C, Chen J, Peterson WM, Yang H, Flannery JG. Phenotypic characterization of P23H and S334ter rhodopsin transgenic rat models of inherited retinal degeneration. Exp Eye Res 2018; 167:56-90. [PMID: 29122605 PMCID: PMC5811379 DOI: 10.1016/j.exer.2017.10.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/25/2017] [Accepted: 10/31/2017] [Indexed: 02/07/2023]
Abstract
We produced 8 lines of transgenic (Tg) rats expressing one of two different rhodopsin mutations in albino Sprague-Dawley (SD) rats. Three lines were generated with a proline to histidine substitution at codon 23 (P23H), the most common autosomal dominant form of retinitis pigmentosa in the United States. Five lines were generated with a termination codon at position 334 (S334ter), resulting in a C-terminal truncated opsin protein lacking the last 15 amino acid residues and containing all of the phosphorylation sites involved in rhodopsin deactivation, as well as the terminal QVAPA residues important for rhodopsin deactivation and trafficking. The rates of photoreceptor (PR) degeneration in these models vary in proportion to the ratio of mutant to wild-type rhodopsin. The models have been widely studied, but many aspects of their phenotypes have not been described. Here we present a comprehensive study of the 8 Tg lines, including the time course of PR degeneration from the onset to one year of age, retinal structure by light and electron microscopy (EM), hemispheric asymmetry and gradients of rod and cone degeneration, rhodopsin content, gene dosage effect, rapid activation and invasion of the outer retina by presumptive microglia, rod outer segment disc shedding and phagocytosis by the retinal pigmented epithelium (RPE), and retinal function by the electroretinogram (ERG). The biphasic nature of PR cell death was noted, as was the lack of an injury-induced protective response in the rat models. EM analysis revealed the accumulation of submicron vesicular structures in the interphotoreceptor space during the peak period of PR outer segment degeneration in the S334ter lines. This is likely due to the elimination of the trafficking consensus domain as seen before as with other rhodopsin mutants lacking the C-terminal QVAPA. The 8 rhodopsin Tg lines have been, and will continue to be, extremely useful models for the experimental study of inherited retinal degenerations.
Collapse
Affiliation(s)
- Matthew M LaVail
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Shimpei Nishikawa
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Roy H Steinberg
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, 3517 Cullen Blvd., Room 2011, Houston, TX 77204-5060, USA.
| | - Jacque L Duncan
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Nikolaus Trautmann
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Michael T Matthes
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Douglas Yasumura
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA
| | - Cathy Lau-Villacorta
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Jeannie Chen
- Zilka Neurogenetic Institute, USC Keck School of Medicine, Los Angeles, CA 90089-2821, USA.
| | - Ward M Peterson
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Haidong Yang
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - John G Flannery
- School of Optometry, UC Berkeley, Berkeley, CA 94720-2020, USA.
| |
Collapse
|
4
|
Moos WH, Faller DV, Glavas IP, Harpp DN, Irwin MH, Kanara I, Pinkert CA, Powers WR, Steliou K, Vavvas DG, Kodukula K. Epigenetic Treatment of Neurodegenerative Ophthalmic Disorders: An Eye Toward the Future. Biores Open Access 2017; 6:169-181. [PMID: 29291141 PMCID: PMC5747116 DOI: 10.1089/biores.2017.0036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Eye disease is one of the primary medical conditions that requires attention and therapeutic intervention in ageing populations worldwide. Further, the global burden of diabetes and obesity, along with heart disease, all lead to secondary manifestations of ophthalmic distress. Therefore, there is increased interest in developing innovative new approaches that target various mechanisms and sequelae driving conditions that result in adverse vision. The research challenge is even greater given that the terrain of eye diseases is difficult to landscape into a single therapeutic theme. This report addresses the burden of eye disease due to mitochondrial dysfunction, including antioxidant, autophagic, epigenetic, mitophagic, and other cellular processes that modulate the biomedical end result. In this light, we single out lipoic acid as a potent known natural activator of these pathways, along with alternative and potentially more effective conjugates, which together harness the necessary potency, specificity, and biodistribution parameters required for improved therapeutic outcomes.
Collapse
Affiliation(s)
- Walter H. Moos
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California San Francisco, San Francisco, California
- ShangPharma Innovation, Inc., South San Francisco, California
| | - Douglas V. Faller
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts
- Cancer Research Center, Boston University School of Medicine, Boston, Massachusetts
| | - Ioannis P. Glavas
- Department of Ophthalmology, New York University School of Medicine, New York, New York
| | - David N. Harpp
- Department of Chemistry, McGill University, Montreal, QC, Canada
| | - Michael H. Irwin
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, Alabama
| | | | - Carl A. Pinkert
- Department of Biological Sciences, College of Arts and Sciences, The University of Alabama, Tuscaloosa, Alabama
| | - Whitney R. Powers
- Department of Health Sciences, Boston University, Boston, Massachusetts
- Department of Anatomy, Boston University School of Medicine, Boston, Massachusetts
| | - Kosta Steliou
- Cancer Research Center, Boston University School of Medicine, Boston, Massachusetts
- PhenoMatriX, Inc., Natick, Massachusetts
| | - Demetrios G. Vavvas
- Retina Service, Angiogenesis Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts
| | - Krishna Kodukula
- ShangPharma Innovation, Inc., South San Francisco, California
- PhenoMatriX, Inc., Natick, Massachusetts
- Bridgewater College, Bridgewater, Virginia
| |
Collapse
|
5
|
Engler-Chiurazzi EB, Covey DF, Simpkins JW. A novel mechanism of non-feminizing estrogens in neuroprotection. Exp Gerontol 2016; 94:99-102. [PMID: 27818250 DOI: 10.1016/j.exger.2016.10.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/25/2016] [Accepted: 10/30/2016] [Indexed: 01/01/2023]
Abstract
Estrogens are potent and efficacious neuroprotectants both in vitro and in vivo in a variety of models of neurotoxicity. We determined the structural requirements for neuroprotection in an in vitro assay using a panel of >70 novel estratrienes, synthesized to reduce or eliminate estrogen receptor (ER) binding. We observed that neuroprotection could be enhanced by as much as 200-fold through modifications that positioned a large bulky group at the C2 or C4 position of the phenolic A ring of the estratriene. Further, substitutions on the B, C or D rings either reduced or did not markedly change neuroprotection. Collectively, there was a negative correlation between binding to ERs and neuroprotection with the more potent compounds showing no ER binding. In an in vivo model for neuroprotection, transient cerebral ischemia, efficacious compounds were active in protection of brain tissue from this pro-oxidant insult. We demonstrated that these non-feminizing estrogens engage in a redox cycle with glutathione, using the hexose monophosphate shunt to apply cytosolic reducing potential to cellular membranes. Together, these results demonstrate that non-feminizing estrogens are neuroprotective and protect brain from the induction of ischemic- and Alzheimer's disease (AD)-like neuropathology in an animal model. These features of non-feminizing estrogens make them attractive compounds for assessment of efficacy in AD and stroke, as they are not expected to show the side effects of chronic estrogen therapy that are mediated by ER actions in the liver, uterus and breast.
Collapse
Affiliation(s)
- Elizabeth B Engler-Chiurazzi
- Center for Basic and Translational Stroke Research, West Virginia University, Morgantown, WV 26505, United States.
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63130, United States
| | - James W Simpkins
- Center for Basic and Translational Stroke Research, West Virginia University, Morgantown, WV 26505, United States
| |
Collapse
|
6
|
|
7
|
Jerry Chiang WC, Lin JH. The effects of IRE1, ATF6, and PERK signaling on adRP-linked rhodopsins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:661-7. [PMID: 24664756 DOI: 10.1007/978-1-4614-3209-8_83] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Many mutations in rhodopsin gene linked to retinitis pigmentosa (RP) cause rhodopsin misfolding. Rod photoreceptor cells expressing misfolded rhodopsin eventually die. Identifying mechanisms to prevent rhodopsin misfolding or to remove irreparably misfolded rhodopsin could provide new therapeutic strategies. IRE1, ATF6, and PERK signaling pathways, collectively called the unfolded protein response (UPR), regulate the functions of endoplasmic reticulum, responsible for accurate folding of membrane proteins such as rhodopsin. We used chemical and genetic approaches to selectively activate IRE1, ATF6, or PERK signaling pathways one at a time and analyzed their effects on mutant rhodopsin linked to RP. We found that both artificial IRE1 and ATF6 signaling promoted the degradation of mutant rhodopsin with lesser effects on wild-type rhodopsin. Furthermore, IRE1 and ATF6 signaling preferentially reduced levels of aggregated rhodopsins. By contrast, PERK signaling reduced levels of wild-type and mutant rhodopsin. These studies indicate that activation of either IRE1, ATF6, or PERK prevents mutant rhodopsin from accumulating in the cells. In addition, activation of IRE1 or ATF6 can selectively remove aggregated or mutant rhodopsin from the cells and may be useful in treating RP associated with rhodopsin protein misfolding.
Collapse
Affiliation(s)
- Wei-Chieh Jerry Chiang
- Department of Pathology, University of California at San Diego, 9500 Gilman Dr., 92093-0612, La Jolla, CA, USA,
| | | |
Collapse
|
8
|
Zhang N, Kolesnikov AV, Jastrzebska B, Mustafi D, Sawada O, Maeda T, Genoud C, Engel A, Kefalov VJ, Palczewski K. Autosomal recessive retinitis pigmentosa E150K opsin mice exhibit photoreceptor disorganization. J Clin Invest 2012; 123:121-37. [PMID: 23221340 DOI: 10.1172/jci66176] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 10/04/2012] [Indexed: 12/13/2022] Open
Abstract
The pathophysiology of the E150K mutation in the rod opsin gene associated with autosomal recessive retinitis pigmentosa (arRP) has yet to be determined. We generated knock-in mice carrying a single nucleotide change in exon 2 of the rod opsin gene resulting in the E150K mutation. This novel mouse model displayed severe retinal degeneration affecting rhodopsin's stabilization of rod outer segments (ROS). Homozygous E150K (KK) mice exhibited early-onset retinal degeneration, with disorganized ROS structures, autofluorescent deposits in the subretinal space, and aberrant photoreceptor phagocytosis. Heterozygous (EK) mice displayed a delayed-onset milder retinal degeneration. Further, mutant receptors were mislocalized to the inner segments and perinuclear region. Though KK mouse rods displayed markedly decreased phototransduction, biochemical studies of the mutant rhodopsin revealed only minimally affected chromophore binding and G protein activation. Ablation of the chromophore by crossing KK mice with mice lacking the critical visual cycle protein LRAT slowed retinal degeneration, whereas blocking phototransduction by crossing KK mice with GNAT1-deficient mice slightly accelerated this process. This study highlights the importance of proper higher-order organization of rhodopsin in the native tissue and provides information about the signaling properties of this mutant rhodopsin. Additionally, these results suggest that patients heterozygous for the E150K mutation should be periodically reevaluated for delayed-onset retinal degeneration.
Collapse
Affiliation(s)
- Ning Zhang
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44160, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Chiang WC, Hiramatsu N, Messah C, Kroeger H, Lin JH. Selective activation of ATF6 and PERK endoplasmic reticulum stress signaling pathways prevent mutant rhodopsin accumulation. Invest Ophthalmol Vis Sci 2012; 53:7159-66. [PMID: 22956602 DOI: 10.1167/iovs.12-10222] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE Many rhodopsin mutations that cause retinitis pigmentosa produce misfolded rhodopsin proteins that are retained within the endoplasmic reticulum (ER) and cause photoreceptor cell death. Activating transcription factor 6 (ATF6) and protein kinase RNA-like endoplasmic reticulum kinase (PERK) control intracellular signaling pathways that maintain ER homeostasis. The aim of this study was to investigate how ATF6 and PERK signaling affected misfolded rhodopsin in cells, which could identify new molecular therapies to treat retinal diseases associated with ER protein misfolding. METHODS To examine the effect of ATF6 on rhodopsin, wild-type (WT) or mutant rhodopsins were expressed in cells expressing inducible human ATF6f, the transcriptional activator domain of ATF6. Induction of ATF6f synthesis rapidly activated downstream genes. To examine PERK's effect on rhodopsin, WT or mutant rhodopsins were expressed in cells expressing a genetically altered PERK protein, Fv2E-PERK. Addition of the dimerizing molecule (AP20187) rapidly activated Fv2E-PERK and downstream genes. By use of these strategies, it was examined how selective ATF6 or PERK signaling affected the fate of WT and mutant rhodopsins. RESULTS ATF6 significantly reduced T17M, P23H, Y178C, C185R, D190G, K296E, and S334ter rhodopsin protein levels in the cells with minimal effects on monomeric WT rhodopsin protein levels. By contrast, the PERK pathway reduced both levels of WT, mutant rhodopsins, and many other proteins in the cell. CONCLUSIONS This study indicates that selectively activating ATF6 or PERK prevents mutant rhodopsin from accumulating in cells. ATF6 signaling may be especially useful in treating retinal degenerative diseases arising from rhodopsin misfolding by preferentially clearing mutant rhodopsin and abnormal rhodopsin aggregates.
Collapse
Affiliation(s)
- Wei-Chieh Chiang
- Department of Pathology, University of California at San Diego, La Jolla, California, USA
| | | | | | | | | |
Collapse
|
10
|
Belokopytov M, Shulman S, Dubinsky G, Belkin M, Rosner M. Intravitreal saline injection ameliorates laser-induced retinal damage in rats. Retina 2012; 32:1165-70. [PMID: 22290081 DOI: 10.1097/iae.0b013e318234942f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE Injury to the central nervous system has been shown to trigger a physiologic response in the form of some degree of natural self-repair. This beneficial reaction may be boosted by appropriate preconditioning via a reversible injury to the retina. Here we report the ameliorative effect of intravitreal saline injection on laser-induced retinal damage. METHODS Standard argon laser lesions (514 and 544 nm, 200 μm, 0.1 W, 0.05 seconds) were induced in the eyes of 36 Dark Agouti pigmented rats and immediately followed by injection of saline either intravitreally (5 μL) or intravenously (0.5 mL). Lesions were evaluated histologically and morphometrically after 3, 20, and 60 days. RESULTS At all 3 time points, the eyes of rats injected intravitreally showed less laser-induced retinal cell loss (P < 0.05) and smaller lesion diameters (P < 0.05) than those of intravenously injected rats. CONCLUSION Intravitreal saline injection evidently has a neuroprotective effect on the rat retina. The mechanism of action of this effect should be further elucidated and its clinical applicability tested.
Collapse
Affiliation(s)
- Mark Belokopytov
- Goldschleger Eye Research Institute, Sackler School of Medicine, Tel Aviv University, Sheba Medical Center, Tel Hashomer, Israel.
| | | | | | | | | |
Collapse
|
11
|
Nixon E, Simpkins JW. Neuroprotective effects of nonfeminizing estrogens in retinal photoreceptor neurons. Invest Ophthalmol Vis Sci 2012; 53:4739-47. [PMID: 22700711 DOI: 10.1167/iovs.12-9517] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
PURPOSE Retinal diseases such as macular degeneration and glaucoma are disorders that target specific retinal neurons that can ultimately lead to vision loss. Under these conditions and pathologies, retinal neurons can die via apoptosis that may be due to increased oxidative stress. The neuroprotective effects of 17β-estradiol (E2) and three synthetic nonfeminizing estrogen analogs (ZYC-26, ZYC-23, and ZYC-3) were investigated to examine their abilities to protect retinal neurons against glutamate toxicity. METHODS Using an in vitro model of glutamate-induced cell death in 661W cells, a mouse cone photoreceptor cell line, shown to express both estrogen receptors (ERs) via immunoblotting, was pretreated with E2 and its analogs and cell viability were assessed. RESULTS It was observed that E2 and estrogen analogs, ZYC-26 and ZYC-3, were protective against a 5 mM glutamate insult in 661W cells. The neuroprotective abilities of ZYC-26 and ZYC-3 were autonomous of estrogen receptor-α (ERα) and ERβ demonstrated by their ability to protect in the presence of ICI 182780, a pan-ER antagonist with a high affinity for the estrogen receptor. Treatment with PPT and DPN, ERα- and ERβ-specific agonists, respectively, did not protect the 661W cells from the glutamate insult. Studying the membrane ER (mER) or GPR30 did show that activation of the receptor by G1 protected the retinal neuron from insult, whereas G15, an antagonist of the mER was not able to antagonize the protection previously seen. CONCLUSIONS These data demonstrate that nonfeminizing estrogens may emerge as useful compounds for neuroprotection of retinal cells.
Collapse
Affiliation(s)
- Everett Nixon
- Department of Pharmacology and Neuroscience, Institute for Aging and Alzheimer's Disease Research, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | | |
Collapse
|
12
|
Stanniocalcin-1 rescued photoreceptor degeneration in two rat models of inherited retinal degeneration. Mol Ther 2012; 20:788-97. [PMID: 22294148 DOI: 10.1038/mt.2011.308] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Oxidative stress and photoreceptor apoptosis are prominent features of many forms of retinal degeneration (RD) for which there are currently no effective therapies. We previously observed that mesenchymal stem/stromal cells reduce apoptosis by being activated to secrete stanniocalcin-1 (STC-1), a multifunctional protein that reduces oxidative stress by upregulating mitochondrial uncoupling protein-2 (UCP-2). Therefore, we tested the hypothesis that intravitreal injection of STC-1 can rescue photoreceptors. We first tested STC-1 in the rhodopsin transgenic rat characterized by rapid photoreceptor loss. Intravitreal STC-1 decreased the loss of photoreceptor nuclei and transcripts and resulted in measurable retinal function when none is otherwise present in this rapid degeneration. We then tested STC-1 in the Royal College of Surgeons (RCS) rat characterized by a slower photoreceptor degeneration. Intravitreal STC-1 reduced the number of pyknotic nuclei in photoreceptors, delayed the loss of photoreceptor transcripts, and improved function of rod photoreceptors. Additionally, STC-1 upregulated UCP-2 and decreased levels of two protein adducts generated by reactive oxygen species (ROS). Microarrays from the two models demonstrated that STC-1 upregulated expression of a similar profile of genes for retinal development and function. The results suggested that intravitreal STC-1 is a promising therapy for various forms of RD including retinitis pigmentosa and atrophic age-related macular degeneration (AMD).
Collapse
|
13
|
Iezzi R, Guru BR, Glybina IV, Mishra MK, Kennedy A, Kannan RM. Dendrimer-based targeted intravitreal therapy for sustained attenuation of neuroinflammation in retinal degeneration. Biomaterials 2012; 33:979-88. [DOI: 10.1016/j.biomaterials.2011.10.010] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 10/06/2011] [Indexed: 10/15/2022]
|
14
|
Baltmr A, Duggan J, Nizari S, Salt TE, Cordeiro MF. Neuroprotection in glaucoma - Is there a future role? Exp Eye Res 2010; 91:554-66. [PMID: 20800593 DOI: 10.1016/j.exer.2010.08.009] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/26/2010] [Accepted: 08/06/2010] [Indexed: 02/06/2023]
Abstract
In glaucoma, the major cause of global irreversible blindness, there is an urgent need for treatment modalities that directly target the RGCs. The discovery of an alternative therapeutic approach, independent of IOP reduction, is highly sought after, due to the indirect nature and limited effectiveness of IOP lowering therapy in preventing RGC loss. Several mechanisms have been implicated in initiating the apoptotic cascade in glaucomatous retinopathy and numerous drugs have been shown to be neuroprotective in animal models of glaucoma. These mechanisms and their potential treatment include excitotoxicity, protein misfolding, mitochondrial dysfunction, oxidative stress, inflammation and neurotrophin deprivation. All of these mechanisms ultimately lead to programmed cell death with loss of RGCs. In this article we summarize the mechanisms involved in glaucomatous disease, highlight the rationale for neuroprotection in glaucoma management and review current potential neuroprotective strategies targeting RGCs from the laboratory to the clinic.
Collapse
Affiliation(s)
- Abeir Baltmr
- Glaucoma and Retinal Neurodegeneration Research Group, Visual Neurosciences Department, University College London Institute of Ophthalmology, Bath Street, London EC1V 9EL, United Kingdom
| | | | | | | | | |
Collapse
|
15
|
|
16
|
Ciavatta VT, Kim M, Wong P, Nickerson JM, Shuler RK, McLean GY, Pardue MT. Retinal expression of Fgf2 in RCS rats with subretinal microphotodiode array. Invest Ophthalmol Vis Sci 2009; 50:4523-30. [PMID: 19264883 DOI: 10.1167/iovs.08-2072] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To test the hypothesis that subretinal electrical stimulation from a microphotodiode array (MPA) exerts a neuroprotective effect in Royal College of Surgeons (RCS) rats through the induction of growth factors. METHODS At postnatal day 21, RCS rats were divided into four groups in which one eye per rat received treatment: (A) active MPA, (M) minimally active MPA, (S) sham surgery, or (C) no surgery and the opposite eye was unoperated. Dark- and light-adapted ERGs were recorded 1 week after surgery. A second set of A-, M-, and C-treated RCS rats had weekly ERG recordings for 4 weeks. Real-time RT-PCR was used to measure relative expression of mRNAs (Bdnf, Fgf2, Fgf1, Cntf, Gdnf, and Igf1) in retina samples collected 2 days after the final ERG. RESULTS One week after surgery, there was a slight difference in dark-adapted ERG b-wave at the brightest flash intensity. Mean retinal Fgf2 expression in the treated eye relative to the opposite eye was greater for the A group (4.67 +/- 0.72) than for the M group (2.80 +/- 0.45; P = 0.0501), S group (2.03 +/- 0.45; P < 0.01), and C group (1.30 +/- 0.22; P < 0.001). No significant change was detected for Bdnf, Cntf, Fgf1, Gdnf, and Igf1. Four weeks after surgery, the A group had significantly larger dark- and light-adapted ERG b-waves than for the M and C groups (P < 0.01). Simultaneously, mean relative Fgf2 expression was again greater for the A group (3.28 +/- 0.61) than for the M (1.28 +/- 0.32; P < 0.05) and C (1.05 +/- 0.04; P < 0.05) groups. CONCLUSIONS The results show subretinal implantation of an MPA induces selective expression of Fgf2 above that expected from a retina-piercing injury. Preservation of ERG b-wave amplitude 4 weeks after implantation is accompanied by elevated Fgf2 expression. These results suggest that Fgf2 may play a role in the neuroprotection provided by subretinal electrical stimulation.
Collapse
|
17
|
Dykens JA, Marroquin LD, Will Y. Strategies to reduce late-stage drug attrition due to mitochondrial toxicity. Expert Rev Mol Diagn 2007; 7:161-75. [PMID: 17331064 DOI: 10.1586/14737159.7.2.161] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mitochondrial dysfunction is increasingly implicated in the etiology of drug-induced toxicities and negative side-effect profiles. Early identification of mitochondrial liabilities for new chemical entities is therefore crucial for avoiding late-stage attrition during drug development. Limitations of traditional methods for assessing mitochondrial dysfunction have discouraged routine evaluation of mitochondrial liabilities. To circumvent this bottleneck, a high-throughput screen has been developed that measures oxygen consumption; one of the most informative parameters for the assessment of mitochondrial status. This technique has revealed that some, but not all, members of many major drug classes have mitochondrial liabilities. This dichotomy encourages optimism that efficacy can be disassociated from mitochondrial toxicity, resulting in safer drugs in the future.
Collapse
Affiliation(s)
- James A Dykens
- Pfizer DSRD, 10646 Science Center Drive, San Diego, CA 92121, USA.
| | | | | |
Collapse
|
18
|
Abstract
Hereditary degenerations of the human retina are genetically heterogeneous, with well over 100 genes implicated so far. This Seminar focuses on the subset of diseases called retinitis pigmentosa, in which patients typically lose night vision in adolescence, side vision in young adulthood, and central vision in later life because of progressive loss of rod and cone photoreceptor cells. Measures of retinal function, such as the electroretinogram, show that photoreceptor function is diminished generally many years before symptomic night blindness, visual-field scotomas, or decreased visual acuity arise. More than 45 genes for retinitis pigmentosa have been identified. These genes account for only about 60% of all patients; the remainder have defects in as yet unidentified genes. Findings of controlled trials indicate that nutritional interventions, including vitamin A palmitate and omega-3-rich fish, slow progression of disease in many patients. Imminent treatments for retinitis pigmentosa are greatly anticipated, especially for genetically defined subsets of patients, because of newly identified genes, growing knowledge of affected biochemical pathways, and development of animal models.
Collapse
Affiliation(s)
- Dyonne T Hartong
- Ocular Molecular Genetics Institute, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA
| | | | | |
Collapse
|
19
|
Dykens JA, Moos WH, Howell N. Development of 17alpha-estradiol as a neuroprotective therapeutic agent: rationale and results from a phase I clinical study. Ann N Y Acad Sci 2006; 1052:116-35. [PMID: 16024755 DOI: 10.1196/annals.1347.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
17alpha-estradiol (17alpha-E2) differs from its isomer, the potent feminizing hormone 17beta-estradiol (17beta-E2), only in the stereochemistry at one carbon, but this is sufficient to render it at least 200-fold less active as a transactivating hormone. Despite its meager hormonal activity, 17alpha-E2 is as potent as 17beta-E2 in protecting a wide variety of cell types, including primary neurons, from a diverse array of lethal and etiologically relevant stressors, including amyloid toxicity, serum withdrawal, oxidative stress, excitotoxicity, and mitochondrial inhibition, among others. Moreover, both estradiol isomers have shown efficacy in animal models of stroke, Alzheimer's disease (AD), and Parkinson's disease (PD). Data from many labs have yielded a mechanistic model in which 17alpha-E2 intercalates into cell membranes, where it terminates lipid peroxidation chain reactions, thereby preserving membrane integrity, and where it in turn is redox cycled by glutathione or by NADPH through enzymatic coupling. Maintaining membrane integrity is critical to mitochondrial function, where loss of impermeability of the inner membrane initiates both necrotic and apoptotic pathways. Thus, by serving as a mitoprotectant, 17alpha-E2 forestalls cell death and could correspondingly provide therapeutic benefit in a host of degenerative diseases, including AD, PD, Friedreich's ataxia, and amyotrophic lateral sclerosis, while at the same time circumventing the common adverse effects elicited by more hormonally active analogues. Positive safety and pharmacokinetic data from a successful phase I clinical study with oral 17alpha-E2 (sodium sulfate conjugate) are presented here, and several options for its future clinical assessment are discussed.
Collapse
Affiliation(s)
- James A Dykens
- MIGENIX Corporation, 12780 High Bluff Dr., San Diego, CA 92130, USA.
| | | | | |
Collapse
|
20
|
Simpkins JW, Wen Y, Perez E, Yang S, Wang X. Role of nonfeminizing estrogens in brain protection from cerebral ischemia: an animal model of Alzheimer's disease neuropathology. Ann N Y Acad Sci 2006; 1052:233-42. [PMID: 16024766 DOI: 10.1196/annals.1347.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Estrogens are potent and efficacious neuroprotectants both in vitro and in vivo in a variety of models of neurotoxicity. We determined the structural requirements for neuroprotection in in vitro assays using a library of more than 70 novel estratrienes, synthesized to reduce or eliminate estrogen receptor (ER) binding. We observed that neuroprotection could be enhanced by as much as 200-fold through modifications that positioned a large, bulky group at the C2 and/or C4 position of the phenolic A ring of the estratriene. Further, substitutions on the B, C, or D rings either reduced or did not markedly change neuroprotection. For this library of compounds, there was a negative correlation between ER binding and neuroprotection, as the more potent compounds showed weaker or no ER binding. In an in vivo model for neuroprotection, transient cerebral ischemia, efficacious compounds were active in protection of brain tissue from this pro-oxidant insult. Finally, estradiol protected brains from insult-induced Alzheimer's disease (AD) neuropathology, including activation of apoptosis, stimulation of Abeta production, hyperphosphorylation of tau, activation of cyclin-dependent kinases, and activation of catastrophic attempts at neuronal mitosis. Collectively, these results demonstrate that nonfeminizing estrogens are neuroprotective and protect the brain from the induction of AD-like neuropathology in an animal model. These features of nonfeminizing estrogens make them attractive compounds for assessment of efficacy in AD and stroke, because they are not expected to show the side effects of chronic estrogen therapy that are ER mediated in the liver, uterus, and breast.
Collapse
Affiliation(s)
- James W Simpkins
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA.
| | | | | | | | | |
Collapse
|
21
|
Dykens JA, Wersinger C, Sidhu A. 17β- and 17α-estradiol are non-competitive inhibitors of dopamine uptake: implications for Parkinson's disease models and therapeutics. Drug Dev Res 2006. [DOI: 10.1002/ddr.20055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
22
|
Cegelski L, Rice CV, O'Connor RD, Caruano AL, Tochtrop GP, Cai ZY, Covey DF, Schaefer J. Mapping the locations of estradiol and potent neuroprotective analogues in phospholipid bilayers by REDOR. Drug Dev Res 2006. [DOI: 10.1002/ddr.20048] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
23
|
Howell N, Dykens J, Moos WH. Alzheimer's disease, estrogens, and clinical trials: a case study in drug development for complex disorders. Drug Dev Res 2006. [DOI: 10.1002/ddr.20046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|